Publications by authors named "Josef Köhrle"

180 Publications

Testing for heterotopia formation in rats after developmental exposure to selected in vitro inhibitors of thyroperoxidase.

Environ Pollut 2021 Apr 12;283:117135. Epub 2021 Apr 12.

Division of Diet, Disease Prevention and Toxicology, National Food Institute, Technical University of Denmark, Kgs. Lyngby, DK-2800, Denmark. Electronic address:

The thyroperoxidase (TPO) enzyme is expressed by the thyroid follicular cells and is required for thyroid hormone synthesis. In turn, thyroid hormones are essential for brain development, thus inhibition of TPO in early life can have life-long consequences for brain function. If environmental chemicals with the capacity to inhibit TPO in vitro can also alter brain development in vivo through thyroid hormone dependent mechanisms, however, remains unknown. In this study we show that the in vitro TPO inhibiting pesticide amitrole alters neuronal migration and induces periventricular heterotopia; a thyroid hormone dependent brain malformation. Perinatal exposure to amitrole reduced pup serum thyroxine (T4) concentrations to less than 50% of control animals and this insufficiency led to heterotopia formation in the 16-day old pup's brain. Two other in vitro TPO inhibitors, 2-mercaptobenzimidazole and cyanamide, caused reproductive toxicity and had only minor sporadic effects on the thyroid hormone system; consequently, they did not cause heterotopia. This is the first demonstration of an environmental chemical causing heterotopia, a brain malformation until now only reported for rodent studies with the anti-thyroid drugs propylthiouracil and methimazole. Our results highlight that certain TPO-inhibiting environmental chemicals can alter brain development through thyroid hormone dependent mechanisms. Improved understanding of the effects on the brain as well as the conditions under which chemicals can perturb brain development will be key to protect human health.
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http://dx.doi.org/10.1016/j.envpol.2021.117135DOI Listing
April 2021

Obesity and Pregnancy. Guideline of the German Society of Gynecology and Obstetrics (S3-Level, AWMF Registry No. 015-081, June 2019).

Geburtshilfe Frauenheilkd 2021 Mar 5;81(3):279-303. Epub 2021 Mar 5.

Klinik für Gynäkologie und Geburtshilfe, Sana-Klinikum, Duisburg, Germany.

Obesity is an increasing problem, even in young women of reproductive age. Obesity has a negative impact on conception, the course of pregnancy, and neonatal outcomes. Caring for obese pregnant women is becoming an increasingly important aspect of standard prenatal care. This guideline aims to improve the care offered to obese pregnant women. This S3-guideline was compiled following a systemic search for evidence and a structured process to achieve consensus. Evidence-based recommendations for the care of obese pregnant women were developed, which cover such as areas as preconception counselling, identification of risks, special aspects of prenatal care and prenatal diagnostic procedures, intrapartum management, and long-term effects on mother and child.
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http://dx.doi.org/10.1055/a-1330-7466DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7938937PMC
March 2021

Comparative Analysis of the Effects of Long-Term 3,5-diiodothyronine Treatment on the Murine Hepatic Proteome and Transcriptome Under Conditions of Normal Diet and High-Fat Diet.

Thyroid 2021 Apr 7. Epub 2021 Apr 7.

Charité-Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Institut für Experimentelle Endokrinologie, Berlin, Germany.

The thyroid hormone (TH) metabolite 3,5-diiodothyronine (3,5-T2) is considered as a potential drug for treatment of nonalcoholic fatty liver disease (NAFLD) based on its prominent antisteatotic effects in murine models of obesity without the detrimental thyromimetic side effects known for classical TH. To expand our understanding of its mode of action, we comprehensively characterized the effects of 3,5-T2 on hepatic gene expression in a diet-induced murine model of obesity by a combined liver proteome and transcriptome analysis. Male C57BL/6 mice fed high-fat diet (HFD) to induce NAFLD or standard diet (SD) as control were treated with 2.5 μg/g body weight 3,5-T2 or saline for 4 weeks. We performed mass spectrometry analyses and integrated those proteome data with earlier published microarray-based transcriptome data from the same animals. In addition, concentrations of several sex steroids in serum and different tissues were determined by gas chromatography-tandem mass spectrometry. We observed limited concordance between transcripts and proteins exhibiting differential abundance under 3,5-T2 treatment, which was only partially explainable by methodological reasons and might, therefore, reflect noncanonical post-transcriptional events. The treatment affected the levels of more and partially different proteins under HFD as compared with SD, demonstrating response modulation by the hepatic lipid load. The hepatic physiological signatures of 3,5-T2 treatment inferable from the omics data comprised the reduction of oxidative stress and alteration of apolipoprotein profiles, both due to decreased liver fat content. In addition, induction of several classical TH target genes and genes involved in the biosynthesis of cholesterol, bile acids (BAs), and male sex steroids was observed. The latter finding was supported by hepatic sex steroid measurements. While confirming the beneficial hepatic liver fat reduction by 3,5-T2 treatment, our data suggest that besides the well-known induction of fatty acid oxidation the stimulation of cholesterol- and BA synthesis with subsequent excretion of the latter through bile might represent a further important mechanism in this context. The obvious intensified male sex steroid exposition of the liver in 3,5-T2-treated HFD animals can be predicted to cause enhanced hepatic "masculinization," with not yet clear but potentially detrimental physiological consequences.
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http://dx.doi.org/10.1089/thy.2020.0160DOI Listing
April 2021

Selenium in Endocrinology-Selenoprotein-Related Diseases, Population Studies, and Epidemiological Evidence.

Authors:
Josef Köhrle

Endocrinology 2021 02;162(2)

Institut für Experimentelle Endokrinologie, Charité-Universitätsmedizin Berlin, Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany.

Selenium (Se), apart from iodine, iron, and calcium, is one of the nutrient-derived key elements strongly affecting the endocrine system. However, no specific hormonal "feedback" regulation for Se status has yet been identified, in contrast to the fine-tuned hormone network regulating Ca2+ and phosphate balance or hepcidin-related iron status. Since its discovery as an essential trace element, the effects of Se excess or deficiency on the endocrine system or components of the hypothalamic-pituitary-periphery feedback circuits, the thyroid hormone axis, glucoregulatory and adrenal hormones, male and female gonads, the musculoskeletal apparatus, and skin have been identified. Analysis of the Se status in the blood or via validated biomarkers such as the hepatically derived selenoprotein P provides valuable diagnostic insight and a rational basis for decision making on required therapeutic or preventive supplementation of risk groups or patients. Endocrine-related epidemiological and interventional evidence linking Se status to beneficial or potentially adverse actions of selected selenoproteins mediating most of the (patho-) physiological effects are discussed in this mini-review. Autoimmune thyroid disease, diabetes and obesity, male fertility, as well as osteoporosis are examples for which observational or interventional studies have indicated Se effects. The currently prevailing concept relating Se and selenoproteins to "oxidative stress," reactive oxygen species, radical hypotheses, and related strategies of pharmacological approaches based on various selenium compounds will not be the focus. The crucial biological function of several selenoproteins in cellular redox-regulation and specific enzyme reactions in endocrine pathways will be addressed and put in clinical perspective.
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http://dx.doi.org/10.1210/endocr/bqaa228DOI Listing
February 2021

Adversity Considerations for Thyroid Follicular Cell Hypertrophy and Hyperplasia in Nonclinical Toxicity Studies: Results From the 6th ESTP International Expert Workshop.

Toxicol Pathol 2020 12;48(8):920-938

Food Safety Commission of Japan, Tokyo, Japan.

The European Society of Toxicologic Pathology organized an expert workshop in May 2018 to address adversity considerations related to thyroid follicular cell hypertrophy and/or hyperplasia (FCHH), which is a common finding in nonclinical toxicity studies that can have important implications for risk assessment of pharmaceuticals, food additives, and environmental chemicals. The broad goal of the workshop was to facilitate better alignment in toxicologic pathology and regulatory sciences on how to determine adversity of FCHH. Key objectives were to describe common mechanisms leading to thyroid FCHH and potential functional consequences; provide working criteria to assess adversity of FCHH in context of associated findings; and describe additional methods and experimental data that may influence adversity determinations. The workshop panel was comprised of representatives from the European Union, Japan, and the United States. Participants shared case examples illustrating issues related to adversity assessments of thyroid changes. Provided here are summary discussions, key case presentations, and panel recommendations. This information should increase consistency in the interpretation of adverse changes in the thyroid based on pathology findings in nonclinical toxicity studies, help integrate new types of biomarker data into the review process, and facilitate a more systematic approach to communicating adversity determinations in toxicology reports.
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http://dx.doi.org/10.1177/0192623320972009DOI Listing
December 2020

Mass Spectrometry-Based Determination of Thyroid Hormones and Their Metabolites in Endocrine Diagnostics and Biomedical Research - Implications for Human Serum Diagnostics.

Exp Clin Endocrinol Diabetes 2020 Jun 16;128(6-07):358-374. Epub 2020 Jun 16.

Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health; Berlin, Germany; Institut für Experimentelle Endokrinologie, Berlin, Germany.

The wide spectrum of novel applications for the LC-MS/MS-based analysis of thyroid hormone metabolites (THM) in blood samples and other biological specimen highlights the perspectives of this novel technology. However, thorough development of pre-analytical sample workup and careful validation of both pre-analytics and LC-MS/MS analytics, is needed, to allow for quantitative detection of the thyronome, which spans a broad concentration range in these biological samples.This minireview summarizes recent developments in advancing LC-MS/MS-based analytics and measurement of total concentrations of THM in blood specimen of humans, methods in part further refined in the context of previous achievements analyzing samples derived from cell-culture or tissues. Challenges and solutions to tackle efficient pre-analytic sample extraction and elimination of matrix interferences are compared. Options for automatization of pre-analytic sample-preparation and comprehensive coverage of the wide thyronome concentration range are presented. Conventional immunoassay versus LC-MS/MS-based determination of total and free THM concentrations are briefly compared.
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http://dx.doi.org/10.1055/a-1175-4610DOI Listing
June 2020

Disruption of BMP Signaling Prevents Hyperthyroidism-Induced Bone Loss in Male Mice.

J Bone Miner Res 2020 10 15;35(10):2058-2069. Epub 2020 Jun 15.

Department of Medicine III, Universitätsklinikum Dresden, Technische Universität Dresden, Dresden, Germany.

Thyroid hormones (TH) are key regulators of bone health, and TH excess in mice causes high bone turnover-mediated bone loss. However, the underlying molecular mechanisms of TH actions on bone remain poorly defined. Here, we tested the hypothesis whether TH mediate their effects via the pro-osteogenic bone morphogenetic protein (BMP) signaling pathway in vitro and in vivo. Primary murine osteoblasts treated with 3,3',5-triiodo-L-thyronine (T ) showed an enhanced differentiation potential, which was associated with activated canonical BMP/SMAD signaling reflected by SMAD1/5/8 phosphorylation. Blocking BMP signaling at the receptor (LDN193189) and ligand level (noggin, anti-BMP2/BMP4 neutralizing antibodies) inhibited T -induced osteogenic differentiation. In vivo, TH excess over 4 weeks in male C57BL/6JRj mice led to severe trabecular bone loss with a high bone turnover that was completely prevented by treatment with the BMP ligand scavenger ALK3-Fc. Thus, TH activate the canonical BMP pathway in osteoblasts to promote their differentiation and function. Importantly, this study indicates that blocking the BMP pathway may be an effective strategy to treat hyperthyroidism-induced bone loss. © 2020 The Authors. Journal of Bone and Mineral Research published by American Society for Bone and Mineral Research.
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http://dx.doi.org/10.1002/jbmr.4092DOI Listing
October 2020

Endocrine, Metabolic and Pharmacological Effects of Thyronamines (TAM), Thyroacetic Acids (TA) and Thyroid Hormone Metabolites (THM) - Evidence from in vitro, Cellular, Experimental Animal and Human Studies.

Exp Clin Endocrinol Diabetes 2020 Jun 25;128(6-07):401-413. Epub 2020 May 25.

Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany Institut für Experimentelle Endokrinologie, Berlin, Germany.

Thyroid hormone metabolites (THM) with few or no iodine substituents such as 3,5-T2, the thyronamines 3-T1AM and T0AM, and their oxidation products, the thyroacetic acids (TA) formed by monoamine oxidases, have recently attracted major interest due to their metabolic actions which are in part distinct from those of the classical thyromimetic hormone T3, the major ligand of T3 receptors. This review compiles and discusses effects of 3,5-T2, TAM and TA reported for thyrocytes, pancreatic islets and hepatocytes as well as findings from studies in mouse models after single or repeated administration of pharmacological doses of these agents. Comparison of the 3,5-T2 effects on the transcriptome with not yet published proteome data in livers of obese mice on high fat diet indicate a distinct anti-steatotic effect of this THM. Furthermore, uptake, metabolism, and cellular actions via various receptors such as trace amine-associated receptors (TAAR), alpha-adrenergic, GPCR and T3 receptors are discussed. Studies on postulated pathways of biosynthesis of 3-T1AM, its effects on the HPT-axis and thyroid gland as well as insulin secretion are reviewed. 3-T1AM also acts on hepatocytes and interferes with TRPM8-dependent signaling in human cell lines related to the eye compartment. Human studies are presented which address potential biosynthesis routes of 3,5-T2 and 3-T1AM from THM precursors, especially T3. The current state of diagnostic analytics of these minor THM in human blood is portrayed comparing and critically discussing the still divergent findings based on classical immunoassay and recently developed liquid-chromatography/mass- spectrometry methods, which allow quantification of the thyronome spectrum from one single small volume serum sample. The clinical perspectives of use and potential abuse of these biologically active THM is addressed.
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http://dx.doi.org/10.1055/a-1139-9200DOI Listing
June 2020

Removing Critical Gaps in Chemical Test Methods by Developing New Assays for the Identification of Thyroid Hormone System-Disrupting Chemicals-The ATHENA Project.

Int J Mol Sci 2020 Apr 28;21(9). Epub 2020 Apr 28.

Department of Environment and Health, Vrije Universiteit Amsterdam, VUA, 1081 HV Amsterdam, The Netherlands.

The test methods that currently exist for the identification of thyroid hormone system-disrupting chemicals are woefully inadequate. There are currently no internationally validated in vitro assays, and test methods that can capture the consequences of diminished or enhanced thyroid hormone action on the developing brain are missing entirely. These gaps put the public at risk and risk assessors in a difficult position. Decisions about the status of chemicals as thyroid hormone system disruptors currently are based on inadequate toxicity data. The ATHENA project (Assays for the identification of Thyroid Hormone axis-disrupting chemicals: Elaborating Novel Assessment strategies) has been conceived to address these gaps. The project will develop new test methods for the disruption of thyroid hormone transport across biological barriers such as the blood-brain and blood-placenta barriers. It will also devise methods for the disruption of the downstream effects on the brain. ATHENA will deliver a testing strategy based on those elements of the thyroid hormone system that, when disrupted, could have the greatest impact on diminished or enhanced thyroid hormone action and therefore should be targeted through effective testing. To further enhance the impact of the ATHENA test method developments, the project will develop concepts for better international collaboration and development in the area of thyroid hormone system disruptor identification and regulation.
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http://dx.doi.org/10.3390/ijms21093123DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7247692PMC
April 2020

CD5L Constitutes a Novel Biomarker for Integrated Hepatic Thyroid Hormone Action.

Thyroid 2020 06 21;30(6):908-923. Epub 2020 Apr 21.

Department of Molecular Endocrinology, Center of Brain, Behavior and Metabolism, Institute for Endocrinology and Diabetes, University of Lübeck, Lübeck, Germany.

Pathological conditions of the thyroid hormone (TH) system are routinely diagnosed by using serum concentrations of thyrotropin (TSH), which is sufficient in most cases. However, in certain conditions, such as resistance to TH due to mutations in (RTHb) or TSH-releasing pituitary adenoma (TSHoma), TSH may be insufficient for a correct diagnosis, even in combination with serum TH concentrations. Likewise, under TH replacement therapy, these parameters can be misleading and do not always allow optimal treatment. Hence, additional biomarkers to assess challenging clinical conditions would be highly beneficial. Data from untargeted multi-omics analyses of plasma samples from experimental thyrotoxicosis in human and mouse were exploited to identify proteins that might represent possible biomarkers of TH function. Subsequent mouse studies were used to identify the tissue of origin and the involvement of the two different TH receptors (TR). For in-depth characterization of the underlying cellular mechanisms, primary mouse cells were used. The analysis of the plasma proteome data sets revealed 16 plasma proteins that were concordantly differentially abundant under thyroxine treatment compared with euthyroid controls across the two species. These originated predominantly from liver, spleen, and bone. Independent studies in a clinical cohort and different mouse models identified CD5L as the most robust putative biomarker under different serum TH states and treatment periods. studies revealed that CD5L originates from proinflammatory M1 macrophages, which are similar to liver-residing Kupffer cells, and is regulated by an indirect mechanism requiring the secretion of a yet unknown factor from hepatocytes. In agreement with the role of TRα1 in immune cells and the TRβ-dependent hepatocyte-derived signaling, the regulation of expression depended on both TR isoforms. Our results identify several novel targets of TH action in serum, with CD5L as the most robust marker. Although further studies will be needed to validate the specificity of these targets, CD5L seems to be a promising candidate to assess TH action in hepatocyte-macrophage crosstalk.
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http://dx.doi.org/10.1089/thy.2019.0635DOI Listing
June 2020

3,5-T2-A Janus-Faced Thyroid Hormone Metabolite Exerts Both Canonical T3-Mimetic Endocrine and Intracrine Hepatic Action.

Front Endocrinol (Lausanne) 2019 8;10:787. Epub 2020 Jan 8.

Division of Endocrinology, Georgetown University, Washington, DC, United States.

Over the last decades, thyroid hormone metabolites (THMs) received marked attention as it has been demonstrated that they are bioactive compounds. Their concentrations were determined by immunoassay or mass-spectrometry methods. Among those metabolites, 3,5-diiodothyronine (3,5-T2), occurs at low nanomolar concentrations in human serum, but might reach tissue concentrations similar to those of T4 and T3, at least based on data from rodent models. However, the immunoassay-based measurements in human sera revealed remarkable variations depending on antibodies used in the assays and thus need to be interpreted with caution. In clinical experimental approaches in euthyroid volunteers and hypothyroid patients using the immunoassay as the analytical tool no evidence of formation of 3,5-T2 from its putative precursors T4 or T3 was found, nor was any support found for the assumption that 3,5-T2 might represent a direct precursor for serum 3-T1-AM generated by combined deiodination and decarboxylation from 3,5-T2, as previously documented for mouse intestinal mucosa. We hypothesized that lowered endogenous production of 3,5-T2 in patients requiring T4 replacement therapy after thyroidectomy or for treatment of autoimmune thyroid disease, compared to production of 3,5-T2 in individuals with intact thyroid glands might contribute to the discontent seen in a subset of patients with this therapeutic regimen. So far, our observations do not support this assumption. However, the unexpected association between high serum 3,5-T2 and elevated urinary concentrations of metabolites related to coffee consumption requires further studies for an explanation. Elevated 3,5-T2 serum concentrations were found in several situations including impaired renal function, chronic dialysis, sepsis, non-survival in the ICU as well as post-operative atrial fibrillation (POAF) in studies using a monoclonal antibody-based chemoluminescence immunoassay. Pilot analysis of human sera using LC-linear-ion-trap-mass-spectrometry yielded 3,5-T2 concentrations below the limit of quantification in the majority of cases, thus the divergent results of both methods need to be reconciliated by further studies. Although positive anti-steatotic effects have been observed in rodent models, use of 3,5-T2 as a muscle anabolic, slimming or fitness drug, easily obtained without medical prescription, must be advised against, considering its potency in suppressing the HPT axis and causing adverse cardiac side effects. 3,5-T2 escapes regular detection by commercially available clinical routine assays used for thyroid function tests, which may be seriously disrupted in individuals self-administering 3,5-T2 obtained over-the counter or from other sources.
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http://dx.doi.org/10.3389/fendo.2019.00787DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6960127PMC
January 2020

Lack of the Thyroid Hormone Transporter Mct8 in Osteoblast and Osteoclast Progenitors Increases Trabecular Bone in Male Mice.

Thyroid 2020 02 31;30(2):329-342. Epub 2020 Jan 31.

Department of Medicine III, Universitätsklinikum Dresden, Dresden, Germany.

Bone is an important target of thyroid hormones (THs), which require transport into target cells to exert their actions. Recently, the TH-specific monocarboxylate transporter 8 (Mct8) was reported as a regulator of bone mass in male mice. However, its global deletion leads to high 3,3',5-L-triiodothyronine (T3) serum concentrations that may mask direct effects of Mct8-deficiency on bone. In this study, we assessed the bone cell intrinsic function of Mct8 and using conditional -knockout lines specifically targeting osteoclast and osteoblast progenitors, as well as mature osteoblasts and osteocytes. Twelve-week-old male mice with a global Mct8-deficiency or a conditional -knockout in osteoclast precursors, osteoprogenitors, or mature osteoblasts/osteocytes were analyzed regarding their bone microarchitecture, turnover, and strength. Furthermore, studies were conducted to investigate the role of Mct8 in bone cell differentiation and functionality, as well as TH uptake. Global -knockout mice demonstrated 1.7-fold higher T3 serum concentrations and trabecular bone loss (-28%) likely due to an increased bone turnover as shown by increased osteoblast (+45%) and osteoclast numbers (+41%). However, cortical bone mineral density was increased. cultures of bone marrow-derived osteoblasts and osteoclasts revealed highest expression of in mature bone cells. In addition, Mct8-deficiency resulted in a lower mRNA expression of osteoblast and osteoclast differentiation markers, as well as a reduced mineralization capacity and osteoclast numbers, respectively, indicating a bone cell intrinsic role of Mct8. In fact, conditional -knockout and inhibition of Mct8 in osteoblasts led to an attenuated T3 uptake . , osteoprogenitor-specific -knockout enhanced trabecular bone volume (+16%) with osteoblast numbers being increased 3.7 fold. Interestingly, Mct8-deficiency in osteoprogenitors and late osteoblasts/osteocytes both resulted in cortical bone loss. Finally, -deletion in osteoclast progenitors increased trabecular bone volume (+20%) due to reduced osteoclast numbers (-32%), whereas osteoblast numbers were enhanced (+25%). This study confirms that high systemic T3 in global knockout mice masks the direct effect of Mct8. Moreover, it identifies Mct8 as a critical regulator of trabecular vs. cortical bone by regulating T3 uptake and highlights its cell intrinsic role in osteoclast and osteoblast progenitors.
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http://dx.doi.org/10.1089/thy.2019.0271DOI Listing
February 2020

A Thyroid Hormone-Independent Molecular Fingerprint of 3,5-Diiodothyronine Suggests a Strong Relationship with Coffee Metabolism in Humans.

Thyroid 2019 12 11;29(12):1743-1754. Epub 2019 Nov 11.

Department of Functional Genomics, Interfaculty Institute for Genetics and Functional Genomics, University Medicine Greifswald, Greifswald, Germany.

In numerous studies based predominantly on rodent models, administration of 3,5-diiodo-L-thyronine (3,5-T2), a metabolite of the thyroid hormones (TH) thyroxine (T4) and triiodo-L-thyronine (T3), was reported to cause beneficial health effects, including reversal of steatohepatosis and prevention of insulin resistance, in most instances without adverse thyrotoxic side effects. However, the empirical evidence concerning the physiological relevance of endogenously produced 3,5-T2 in humans is comparatively poor. Therefore, to improve the understanding of 3,5-T2-related metabolic processes, we performed a comprehensive metabolomic study relating serum 3,5-T2 concentrations to plasma and urine metabolite levels within a large general population sample. Serum 3,5-T2 concentrations were determined for 856 participants of the population-based Study of Health in Pomerania-TREND (SHIP-TREND). Plasma and urine metabolome data were generated using mass spectrometry and nuclear magnetic resonance spectroscopy, allowing quantification of 613 and 578 metabolites in plasma and urine, respectively. To detect thyroid function-independent significant 3,5-T2-metabolite associations, linear regression analyses controlling for major confounders, including thyrotropin and free T4, were performed. The same analyses were carried out using a sample of 16 male healthy volunteers treated for 8 weeks with 250 μg/day levothyroxine to induce thyrotoxicosis. The specific molecular fingerprint of 3,5-T2 comprised 15 and 73 significantly associated metabolites in plasma and urine, respectively. Serum 3,5-T2 concentrations were neither associated with classical thyroid function parameters nor altered during experimental thyrotoxicosis. Strikingly, many metabolites related to coffee metabolism, including caffeine and paraxanthine, formed the clearest positively associated molecular signature. Importantly, these associations were replicated in the experimental human thyrotoxicosis model. The molecular fingerprint of 3,5-T2 demonstrates a clear and strong positive association of the serum levels of this TH metabolite with plasma levels of compounds indicating coffee consumption, therefore pointing to the liver as an organ, the metabolism of which is strongly affected by coffee. Furthermore, 3,5-T2 serum concentrations were found not to be directly TH dependent. Considering the beneficial health effects of 3,5-T2 administration observed in animal models and those of coffee consumption demonstrated in large epidemiological studies, one might speculate that coffee-stimulated hepatic 3,5-T2 production or accumulation represents an important molecular link in this connection.
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http://dx.doi.org/10.1089/thy.2018.0549DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6918876PMC
December 2019

The Colorful Diversity of Thyroid Hormone Metabolites.

Authors:
Josef Köhrle

Eur Thyroid J 2019 Jun 21;8(3):115-129. Epub 2019 May 21.

Institut für Experimentelle Endokrinologie, Charité Campus Virchow-Klinikum (CVK), Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany.

Since the discovery of L-thyroxine, the main secretory product of the thyroid gland, and its major metabolite T3, which exerts the majority of thyroid hormone action via ligand-dependent modulation of the function of T3 receptors in nuclei, mitochondria, and other subcellular compartments, various other T4-derived endogenous metabolites have been identified in blood and tissues of humans, animals, and early protochordates. This review addresses major historical milestones and experimental findings resulting in the discovery of the key enzymes of thyroid hormone metabolism, the three selenoprotein deiodinases, as well as the decarboxylases and amine oxidases involved in formation and degradation of recently identified endogenous thyroid hormone metabolites, i.e. 3-iodothyronamine and 3-thyroacetic acid. The concerted action of deiodinases 2 and 3 in regulation of local T3 availability is discussed. Special attention is given to the role of the thyromimetic "hot" metabolite 3,5-T2 and the "cool" 3-iodothyronamine, especially after administration of pharmacological doses of these endogenous thyroid hormone metabolites in various animal experimental models. In addition, available information on the biological roles of the two major acetic acid derivatives of thyroid hormones, i.e. Tetrac and Triac, as well as sulfated metabolites of thyroid hormones is reviewed. This review addresses the consequences of the existence of this broad spectrum of endogenous thyroid hormone metabolites, the "thyronome," beyond the classical thyroid hormone profile comprising T4, T3, and rT3 for appropriate analytical coverage and clinical diagnostics using mass spectrometry versus immunoassays for determination of total and free concentrations of thyroid hormone metabolites in blood and tissues.
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http://dx.doi.org/10.1159/000497141DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6587369PMC
June 2019

A combined LC-MS/MS and LC-MS multi-method for the quantification of iodothyronines in human blood serum.

Anal Bioanal Chem 2019 Aug 15;411(21):5605-5616. Epub 2019 Jun 15.

Institut für Experimentelle Endokrinologie, Charité-Universitätsmedizin Berlin, Augustenburger Platz 1, 13353, Berlin, Germany.

We report here a novel approach for the extraction and analysis of thyroid hormones (TH) and their metabolites (THM) from human serum samples. Our method features a compact, 96-well micro-titre plate-based pre-analytic extraction/clean-up workflow combined with an isotope dilution LC-MS/MS-MS analytical method. In particular, these features make possible the detection of iodothyronines at their endogenous concentrations in serum differing by a factor of ca. 10, with potential to semi-automate the pre-analytics. The method was validated by the assessment of linearity, lower limits of quantification and detection (LLOQ and LLOD respectively), intra- and inter-day accuracy, precision, process efficiency (PE), matrix effect (ME) and relative recovery (RE). Calibration curves were linear in the concentration range in sample matrix from 0.1-250 nM for T, rT, T and 3-TAM and from 0.005-1 nM for 3,5-T and 3,3'-T. Using a 200-μL sample volume, the analyte dependant LLOQ were in the range 0.005 (3,5-T) to 0.25 (T) nM and LLOD were between 0.002 (3,5-T) and 0.052 nM (T). We applied the LC-MS/MS-MS method to the analysis of a cross section of patients with disorders of the thyroid hormone axis. T, T and rT concentrations (± standard deviation) were 120 ± 18, 1.9 ± 0.4 and 0.45 ± 0.09 nM respectively. 3,3'-T concentrations (± standard deviation) were 0.079 ± 0.022 nM; 3,5-T concentrations were below the LLOQ and/or LLOD in all but a single sample (0.013 nM). This method expands the analytical spectrum to endogenous thyroid hormone metabolites such as 3,5-T which exert biological actions and rT which may act as surrogate markers for disturbed thyroid hormone metabolism. Graphical abstract.
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http://dx.doi.org/10.1007/s00216-019-01941-9DOI Listing
August 2019

Aging Alters Phenotypic Traits of Thyroid Dysfunction in Male Mice With Divergent Effects on Complex Systems but Preserved Thyroid Hormone Action in Target Organs.

J Gerontol A Biol Sci Med Sci 2019 07;74(8):1162-1169

Department of Endocrinology, Diabetes, and Metabolism, University Hospital Essen, University Duisburg-Essen, Germany.

Clinical manifestation of hyperthyroidism and hypothyroidism vary with age, with an attenuated, oligosymptomatic presentation of thyroid dysfunction (TD) in older patients. We asked, whether in rodents TD phenotypes are influenced by age and whether this involves changes in systemic and/or organ thyroid hormone (TH) signaling. Chronic hyper- or hypothyroidism was induced in male mice at different life stages (5, 12, and 20 months). TH excess resulted in pronounced age-specific body weight changes (increase in youngest and decrease in old mice), neither explained by changes in food intake (similar increase at all ages), nor by thermogenic gene expression in brown adipose tissue (BAT) or TH serum concentrations. Relative increase in body temperature and activity were more pronounced in old compared to young hyperthyroid mice. An attenuated hypothyroid state was found in old mice for locomotor activity and in heart and BAT on functional (less bradycardia) and gene expression level (heart and BAT). In contrast, decrease in body weight was pronounced in old hypothyroid mice. Thus, age has divergent impact on features of TD in mice, whereby effects on highly complex systems, such as energy homeostasis are not proportional to serum TH state, in contrast to organ-specific responses in heart and BAT.
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http://dx.doi.org/10.1093/gerona/glz040DOI Listing
July 2019

The Role of Dickkopf-1 in Thyroid Hormone-Induced Changes of Bone Remodeling in Male Mice.

Endocrinology 2019 03;160(3):664-674

Department of Medicine III, Technische Universität Dresden Medical Center, Dresden, Germany.

Thyroid hormones regulate bone homeostasis, and exogenously induced hyperthyroidism and hypothyroidism in mice was recently found to be associated with an altered expression of the Wnt inhibitor Dickkopf-1 (Dkk1), a determinant of bone mass. Here, we assessed the role of Dkk1 in thyroid hormone-induced changes in bone using conditional Dkk1 knockout mice. Male mice with a global (Dkk1fl/fl;Rosa26-CreERT2) or osteocyte-specific (Dkk1fl/fl;Dmp1:Cre) deletion of Dkk1 were pharmacologically rendered hypothyroid or hyperthyroid. The bone phenotype was analyzed using micro-CT analysis, dynamic histomorphometry, and serum concentrations of bone turnover markers. Hypothyroid and hyperthyroid Cre-negative mice of either Cre line revealed the expected changes in bone volume with hypothyroid mice displaying a 40% to 60% increase in vertebral trabecular bone volume, while hyperthyroid mice lost 45% to 60% of bone volume. Similar changes were observed at the spine. Interestingly, Cre-positive mice of both lines did not gain or lose as much bone at the femur when rendered hypothyroid or hyperthyroid. While Cre-negative hypothyroid mice gained 80% to 100% bone volume, Cre-positive hypothyroid mice only increased their bone volume by 55% to 90%. Similarly, Cre-negative hyperthyroid mice lost 74% to 79% bone, while Cre-positive hyperthyroid mice merely lost 40% to 54%. Despite these site-specific differences, both global and osteocyte-specific Dkk1 knockout mice displayed similar changes in bone turnover as their Cre-negative controls in the hypothyroid and hyperthyroid states. While osteoblast and osteoclast parameters were increased in hyperthyroidism, hypothyroidism potently suppressed bone cell activities. Loss of Dkk1 is not sufficient to fully reverse thyroid hormone-induced changes in bone mass and bone turnover.
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http://dx.doi.org/10.1210/en.2018-00998DOI Listing
March 2019

3-Iodothyronamine-A Thyroid Hormone Metabolite With Distinct Target Profiles and Mode of Action.

Endocr Rev 2019 04;40(2):602-630

Institut für Experimentelle Pädiatrische Endokrinologie, Charité-Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany.

The rediscovery of the group of thyronamines (TAMs), especially the first detailed description of their most prominent congener 3-iodothyronamine (3T1AM) 14 years ago, boosted research on this thyroid hormone metabolite tremendously. TAMs exert actions partly opposite to and distinct from known functions of thyroid hormones. These fascinating metabolic, anapyrexic, cytoprotective, and brain effects quickly evoked the hope to use hormone-derived TAMs as a therapeutic option. The G protein-coupled receptor (GPCR) TAAR1, a member of the trace amine-associated receptor (TAAR) family, was identified as the first target and effector of TAM action. The initial enthusiasm on pharmacological actions of exogenous TAMs elicited many questions, such as sites of biosynthesis, analytics, modes of action, inactivation, and role of TAMs in (patho)physiology. Meanwhile, it became clear that TAMs not only interact with TAAR1 or other TAAR family members but also with several aminergic receptors and non-GPCR targets such as transient receptor potential channels, mitochondrial proteins, and the serum TAM-binding protein apolipoprotein B100, thus classifying 3T1AM as a multitarget ligand. The physiological mode of action of TAMs is still controversial because regulation of endogenous TAM production and the sites of its biosynthesis are not fully elucidated. Methods for 3T1AM analytics need further validation, as they revealed different blood and tissue concentrations depending on detection principles used such as monoclonal antibody-based immunoassay vs liquid chromatography- matrix-assisted laser desorption/ionization mass spectrometry or time-of-flight mass spectrometry. In this review, we comprehensively summarize and critically evaluate current basic, translational, and clinical knowledge on 3T1AM and its main metabolite 3-iodothyroacetic acid, focusing on endocrine-relevant aspects and open but highly challenging issues.
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http://dx.doi.org/10.1210/er.2018-00182DOI Listing
April 2019

The Effect of High Dose Isoflavone Supplementation on Serum Reverse T in Euthyroid Men With Type 2 Diabetes and Post-menopausal Women.

Front Endocrinol (Lausanne) 2018 22;9:698. Epub 2018 Nov 22.

Weill Cornell Medical College Qatar, Doha, Qatar.

The health benefits of soy are widely reported but there are queries on the effect of soy isoflavones on thyroid function and the underlying mechanism of action. We examined the effect of soy isoflavones on reverse tri-iodothyronine (or 3,3',5'-tri-iodothyronine; rT) in two studies comprising 400 patients: 200 men (study 1; 3 months) and 200 post-menopausal women (study 2; 6 months) who were randomized to consume 15 g soy protein with 66 mg of isoflavones (SPI) daily, or 15 g soy protein alone without isoflavones (SP) daily. SPI supplementation increased rT serum concentration in both men 0.41 (0.12) vs. 0.45 (0.14) nmol/L and women 0.33 (0.12) vs. 0.37 (0.09) nmol/L at 3 months compared to SP that was not seen at 6 months. Thyroid stimulating hormone (TSH) serum concentrations increased while free thyroxine (fT) concentrations decreased with 3 months of SPI compared to SP supplementation for both men and women. rT correlated with TSH in both studies ( = 0.03) but not with either fT or fT. fT levels did not differ between the SPI and SP preparations. Soy isoflavones transiently increased rT3 levels within 3 months though reverted to baseline at 6 months. The mechanism for this would be either rT3 degrading deiodinase 1 and/or deiodinase 2 activities are transiently inhibited at 3 months, or inhibition of deiodinase 3, which generates rT3 from T4 is induced at 6 months. These changes were mirrored in the TSH concentrations, suggesting that short-term high dose isoflavone transiently impairs thyroid function in the first 3 months and may impact on general health during this period. ISRCTN 90604927; ISRCTN34051237.
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http://dx.doi.org/10.3389/fendo.2018.00698DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6262038PMC
November 2018

Vascular Endothelial Growth Factor (VEGF) Induced Downstream Responses to Transient Receptor Potential Vanilloid 1 (TRPV1) and 3-Iodothyronamine (3-TAM) in Human Corneal Keratocytes.

Front Endocrinol (Lausanne) 2018 22;9:670. Epub 2018 Nov 22.

Klinik für Augenheilkunde, Charité-Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany.

This study was undertaken to determine if crosstalk among the transient receptor potential (TRP) melastatin 8 (TRPM8), TRP vanilloid 1 (TRPV1), and vascular endothelial growth factor (VEGF) receptor triad modulates VEGF-induced Ca signaling in human corneal keratocytes. Using RT-PCR, qPCR and immunohistochemistry, we determined TRPV1 and TRPM8 gene and protein coexpression in a human corneal keratocyte cell line (HCK) and human corneal cross sections. Fluorescence Ca imaging using both a photomultiplier and a single cell digital imaging system as well as planar patch-clamping measured relative intracellular Ca levels and underlying whole-cell currents. The TRPV1 agonist capsaicin increased both intracellular Ca levels and whole-cell currents, while the antagonist capsazepine (CPZ) inhibited them. VEGF-induced Ca transients and rises in whole-cell currents were suppressed by CPZ, whereas a selective TRPM8 antagonist, AMTB, increased VEGF signaling. In contrast, an endogenous thyroid hormone-derived metabolite 3-Iodothyronamine (3-TAM) suppressed increases in the VEGF-induced current. The TRPM8 agonist menthol increased the currents, while AMTB suppressed this response. The VEGF-induced increases in Ca influx and their underlying ionic currents stem from crosstalk between VEGFR and TRPV1, which can be impeded by 3-TAM-induced TRPM8 activation. Such suppression in turn blocks VEGF-induced TRPV1 activation. Therefore, crosstalk between TRPM8 and TRPV1 inhibits VEGFR-induced activation of TRPV1.
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http://dx.doi.org/10.3389/fendo.2018.00670DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6262029PMC
November 2018

TRPM8 Activation via 3-Iodothyronamine Blunts VEGF-Induced Transactivation of TRPV1 in Human Uveal Melanoma Cells.

Front Pharmacol 2018 13;9:1234. Epub 2018 Nov 13.

Klinik für Augenheilkunde, Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Berlin Institute of Health, Humboldt-Universität zu Berlin, Berlin, Germany.

In human uveal melanoma (UM), tumor enlargement is associated with increases in aqueous humor vascular endothelial growth factor-A (VEGF-A) content that induce neovascularization. 3-Iodothyronamine (3-TAM), an endogenous thyroid hormone metabolite, activates TRP melastatin 8 (TRPM8), which blunts TRP vanilloid 1 (TRPV1) activation by capsaicin (CAP) in human corneal, conjunctival epithelial cells, and stromal cells. We compare here the effects of TRPM8 activation on VEGF-induced transactivation of TRPV1 in an UM cell line (92.1) with those in normal primary porcine melanocytes (PM) since TRPM8 is upregulated in melanoma. Fluorescence Ca-imaging and planar patch-clamping characterized functional channel activities. CAP (20 μM) induced Ca transients and increased whole-cell currents in both the UM cell line and PM whereas TRPM8 agonists, 100 μM menthol and 20 μM icilin, blunted such responses in the UM cells. VEGF (10 ng/ml) elicited Ca transients and augmented whole-cell currents, which were blocked by capsazepine (CPZ; 20 μM) but not by a highly selective TRPM8 blocker, AMTB (20 μM). The VEGF-induced current increases were not augmented by CAP. Both 3-TAM (1 μM) and menthol (100 μM) increased the whole-cell currents, whereas 20 μM AMTB blocked them. 3-TAM exposure suppressed both VEGF-induced Ca transients and increases in underlying whole-cell currents. Taken together, functional TRPM8 upregulation in UM 92.1 cells suggests that TRPM8 is a potential drug target for suppressing VEGF induced increases in neovascularization and UM tumor growth since TRPM8 activation blocked VEGF transactivation of TRPV1.
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http://dx.doi.org/10.3389/fphar.2018.01234DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6243059PMC
November 2018

Association Between 3-Iodothyronamine (T1am) Concentrations and Left Ventricular Function in Chronic Heart Failure.

J Clin Endocrinol Metab 2019 04;104(4):1232-1238

Department of Endocrinology, Herlev University Hospital, Herlev, Denmark.

Context: Thyroid hormone metabolites might affect the heart. The endogenous aminergic metabolite 3-iodothyronamine (T1am) reduces left ventricular ejection fraction (LVEF) in rodents.

Objective: To investigate concentration of T1am and its association with LVEF and biomarkers of heart function in patients with chronic heart failure (CHF) without thyroid disease, including patients with cardiac cachexia (nonedematous weight loss >5% over 6 months).

Methods: Cross-sectional study. CHF was characterized by LVEF <45% and symptoms. Three groups were included (n = 19 in each group, matched on age, sex, and kidney function): patients with cachexia (CAC), patients without (non-CAC), and control (C) patients with prior myocardial infarction and LVEF >45%. T1am was measured by a monoclonal antibody-based chemiluminescence immunoassay. N-amino terminal pro-BNP (NT-proBNP) concentrations were also analyzed.

Results: Mean (SD) LVEF: CAC, 32 ± 9%; non-CAC, 38 ± 8%; and C, 60 ± 8% (P < 0.0001). TSH, T4, and T3 levels did not differ between groups and did not correlate to T1am. Serum T1am (nmol/L) concentrations were higher in CHF: CAC (mean ± SD), 12.4 ± 6.6; non-CAC, 9.1 ± 5; and C, 7.3 ± 2.9. A negative association between T1am and LVEF was present after adjusting for sex, age, T3, and estimated glomerular filtration rate (P = 0.03). Further, serum T1am levels tended to be associated with NT-proBNP (P = 0.053).

Conclusion: Serum T1am levels were increased in patients with CHF and numerically highest (although nonsignificant) in patients with cardiac cachexia. Increasing T1am concentrations were independently associated with reduced LVEF, suggesting a direct effect on the human heart.
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http://dx.doi.org/10.1210/jc.2018-01466DOI Listing
April 2019

Thyroid Hormones and Derivatives: Endogenous Thyroid Hormones and Their Targets.

Authors:
Josef Köhrle

Methods Mol Biol 2018 ;1801:85-104

Charité-Universitätsmedizin Berlin, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zuBerlin, and Berlin Institute of Health, Institut für Experimentelle Endokrinologie, Berlin, Germany.

More than a century after the discovery of L-Thyroxine, the main thyroid hormone secreted solely by the thyroid gland, several metabolites of this iodinated, tyrosine-derived ancestral hormone have been identified. These are utilized as hormones during development, differentiation, metamorphosis, and regulation of most biochemical reactions in vertebrates and their precursor species. Among those metabolites are the thyromimetically active 3,3',5-Triiodo-L-thyronine (T3) and 3,5-Diiodo-L-thronine, reverse-T3 (3,3',5'-Triiodo-L-thyronine) with still unclear function, the recently re-discovered thyronamines (e.g., 3-Iodo-thyronamine), which exert in part T3-antagonistic functions, the thyroacetic acids (e.g., Tetrac and Triac), as well as various sulfated or glucuronidated metabolites of this panel of iodinated signaling compounds. In the blood most of these hydrophobic metabolites are tightly bound to the serum distributor proteins thyroxine binding globulin (TBG), transthyretin (TTR), albumin or apolipoprotein B100. Cellular import and export of these charged, highly hydrophobic amino acid derivatives requires a number of cell-membrane transporters or facilitators such as MCT8 or MCT10 and members of the OATP and LAT families of transporters. Depending on their structure, the thyroid hormone metabolites exert their cellular action by binding and thus modulating the function of various receptors systems (e.g., ανβ3 integrin receptor and transient receptor potential channels (TRPM8) of the cell membrane), in part linked to intracellular downstream kinase signaling cascades, and several isoforms of membrane-associated, mitochondrial or nuclear thyroid hormone receptors (TR), which are members of the c-erbA family of ligand-modulated transcription factors. Intracellular deiodinase selenoenzymes, which obligatory are membrane integrated enzymes, ornithine decarboxylase and monoamine oxidases control local availability of biologically active thyroid hormone metabolites. Inactivation of thyroid hormone metabolites occurs mainly by deiodination, sulfation or glucuronidation, reactions which favor their renal or fecal elimination.
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http://dx.doi.org/10.1007/978-1-4939-7902-8_9DOI Listing
February 2019

Canonical TSH Regulation of Cathepsin-Mediated Thyroglobulin Processing in the Thyroid Gland of Male Mice Requires Taar1 Expression.

Front Pharmacol 2018 20;9:221. Epub 2018 Mar 20.

Department of Life Sciences and Chemistry, Jacobs University Bremen, Bremen, Germany.

Trace amine-associated receptor 1 (Taar1) has been suggested as putative receptor of thyronamines. These are aminergic messengers with potential metabolic and neurological effects countering their contingent precursors, the thyroid hormones (THs). Recently, we found Taar1 to be localized at the primary cilia of rodent thyroid epithelial cells and . Thus, Taar1 is present in a location of thyroid follicles where it might be involved in regulation of cathepsin-mediated proteolytic processing of thyroglobulin, and consequently TH synthesis. In this study, knock-out male mice () were used to determine whether Taar1 function would entail differential alterations in thyroid states of young and adult animals. Analyses of blood serum revealed unaltered T and T concentrations and unaltered T-over-T ratios upon Taar1 deficiency accompanied, however, by elevated TSH concentrations. Interestingly, TSH receptors, typically localized at the basolateral plasma membrane domain of wild type controls, were located at vesicular membranes in thyrocytes of mice. In addition, determination of epithelial extensions in thyroids showed prismatic cells, which might indicate activation states higher than in the wild type. While gross degradation of thyroglobulin was comparable to controls, deregulated thyroglobulin turnover in mice was indicated by luminal accumulation of covalently cross-linked thyroglobulin storage forms. These findings were in line with decreased proteolytic activities of thyroglobulin-solubilizing and -processing proteases, due to upregulated cystatins acting as their endogenous inhibitors . In conclusion, Taar1-deficient mice are hyperthyrotropinemic in the absence of respective signs of primary hypothyroidism such as changes in body weight or TH concentrations in blood serum. Thyrocytes of mice are characterized by non-canonical TSH receptor localization in intracellular compartments, which is accompanied by altered thyroglobulin turnover due to a disbalanced proteolytic network. These finding are of significance considering the rising popularity of using TAAR1 agonists or antagonists as neuromodulating pharmacological drugs. Our study highlights the importance of further evaluating potential off-target effects regarding TSH receptor mislocalization and the thyroglobulin processing machinery, which may not only affect the TH-generating thyroid gland, but may emanate to other TH target organs like the CNS dependent on their proper supply.
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http://dx.doi.org/10.3389/fphar.2018.00221DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5870035PMC
March 2018

In vivo Effects of Repeated Thyronamine Administration in Male C57BL/6J Mice.

Eur Thyroid J 2018 Jan 5;7(1):3-12. Epub 2017 Dec 5.

Department of Cell and Molecular Biology, Karolinska Institutet, Stockholm, Sweden.

Objectives: Thyronamines are decarboxylated and deiodinated metabolites of thyroid hormones (THs). Of all possible thyronamine variants, only 3-iodothyronamine (3-TAM) and iodine-free thyronamine (TAM) have been detected in vivo. While intensive research has been done on the (patho-)physiological action of 3-TAM, the role of TAM has been studied less intensively.

Study Design: We determined whether a single pharmacological dose (50 mg/kg, i.p.) or repeated administration (5 mg/kg/day, i.p., for 7 days) of TAM affects metabolism, cardiovascular function, or thermoregulation in male C57BL/6J mice. Since selenium (Se) is important for proper TH function and Se metabolism is affected by TH, we additionally analyzed Se concentrations in liver, serum, and kidney using total reflection X-ray analysis.

Results: A single injection of TAM had no effect on heart rate, temperature, or activity as assessed by radio telemetry. Likewise, daily administration of TAM did not alter body weight, food or water intake, heart rate, blood pressure, brown adipose tissue thermogenesis, or body temperature, and no significant differences in hepatic glycogen content or mRNA expression of genes involved in cardiovascular function or metabolic control were determined. Also, the X-ray analysis of Se concentrations revealed no significant changes. However, hepatic TAM was significantly increased in the treated animals.

Conclusions: In summary, our data demonstrate that TAM elicits no obvious metabolic, cardiovascular, or thermoregulatory activities in mice. As TAM does also not interfere with TH or Se metabolism, we conclude that the deiodination of 3-TAM to TAM constitutes an efficient inactivation mechanism, terminating the actions of the more powerful precursor.
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http://dx.doi.org/10.1159/000481856DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5836237PMC
January 2018

Sex-specific phenotypes of hyperthyroidism and hypothyroidism in aged mice.

Biol Sex Differ 2017 12 22;8(1):38. Epub 2017 Dec 22.

Department of Endocrinology, Diabetology and Metabolism, University Hospital Essen, University Duisburg-Essen, Essen, Germany.

Background: Sex and age play a role in the prevalence of thyroid dysfunction (TD), but their interrelationship for manifestation of hyper- and hypothyroidism is still not well understood. Using a murine model, we asked whether sex impacts the phenotypes of hyper- and hypothyroidism at two life stages.

Methods: Hyper- and hypothyroidism were induced by i.p. T4 or MMI/ClO-/LoI treatment over 7 weeks in 12- and 20-months-old female and male C57BL/6N mice. Control animals underwent PBS treatment (n = 7-11 animals/sex/treatment). Animals were investigated for impact of sex on body weight, food and water intake, body temperature, heart rate, behaviour (locomotor activity, motor coordination and strength) and serum thyroid hormone (TH) status.

Results: Distinct sex impact was found in eu- and hyperthyroid mice, while phenotypic traits of hypothyroidism were similar in male and female mice. No sex difference was found in TH status of euthyroid mice; however, T4 treatment resulted in twofold higher TT4, FT4 and FT3 serum concentrations in adult and old females compared to male animals. Hyperthyroid females consistently showed higher locomotor activity and better coordination but more impairment of muscle function by TH excess at adult age. Importantly and in contrast to male mice, adult and old hyperthyroid female mice showed increased body weight. Higher body temperature in female mice was confirmed in all age groups. No sex impact was found on heart rate irrespective of TH status in adult and old mice.

Conclusions: By comparison of male and female mice with TD at two life stages, we found that sex modulates TH action in an organ- and function-specific manner. Sex differences were more pronounced under hyperthyroid conditions. Importantly, sex-specific differences in features of TD in adult and old mice were not conclusively explained by serum TH status in mice.
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http://dx.doi.org/10.1186/s13293-017-0159-1DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5741944PMC
December 2017

Restoration of type 1 iodothyronine deiodinase expression in renal cancer cells downregulates oncoproteins and affects key metabolic pathways as well as anti-oxidative system.

PLoS One 2017 22;12(12):e0190179. Epub 2017 Dec 22.

Department of Biochemistry and Molecular Biology, Centre of Postgraduate Medical Education, Warsaw, Poland.

Type 1 iodothyronine deiodinase (DIO1) contributes to deiodination of 3,5,3',5'-tetraiodo-L-thyronine (thyroxine, T4) yielding of 3,5,3'-triiodothyronine (T3), a powerful regulator of cell differentiation, proliferation, and metabolism. Our previous work showed that loss of DIO1 enhances proliferation and migration of renal cancer cells. However, the global effects of DIO1 expression in various tissues affected by cancer remain unknown. Here, the effects of stable DIO1 re-expression were analyzed on the proteome of renal cancer cells, followed by quantitative real-time PCR validation in two renal cancer-derived cell lines. DIO1-induced changes in intracellular concentrations of thyroid hormones were quantified by L-MS/MS and correlations between expression of DIO1 and potential target genes were determined in tissue samples from renal cancer patients. Stable re-expression of DIO1, resulted in 26 downregulated proteins while 59 proteins were overexpressed in renal cancer cells. The 'downregulated' group consisted mainly of oncoproteins (e.g. STAT3, ANPEP, TGFBI, TGM2) that promote proliferation, migration and invasion. Furthermore, DIO1 re-expression enhanced concentrations of two subunits of thyroid hormone transporter (SLC7A5, SLC3A2), enzymes of key pathways of cellular energy metabolism (e.g. TKT, NAMPT, IDH2), sex steroid metabolism and anti-oxidative response (AKR1C2, AKR1B10). DIO1 expression resulted in elevated intracellular concentration of T4. Expression of DIO1-affected genes strongly correlated with DIO1 transcript levels in tissue samples from renal cancer patients as well as with their poor survival. This first study addressing effects of deiodinase re-expression on proteome of cancer cells demonstrates that induced DIO1 re-expression in renal cancer robustly downregulates oncoproteins, affects key metabolic pathways, and triggers proteins involved in anti-oxidative protection. This data supports the notion that suppressed DIO1 expression and changes in local availability of thyroid hormones might favor a shift from a differentiated to a more proliferation-prone state of cancer tissues and cell lines.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0190179PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5741248PMC
January 2018

Editorial: Get inspired - Lessons learned from evolution of thyroid hormone signaling in developmental processes.

Mol Cell Endocrinol 2017 12;459:1-4

Charité-Universitätsmedizin, Berlin, Germany.

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http://dx.doi.org/10.1016/j.mce.2017.11.012DOI Listing
December 2017

Noncanonical thyroid hormone signaling mediates cardiometabolic effects in vivo.

Proc Natl Acad Sci U S A 2017 12 11;114(52):E11323-E11332. Epub 2017 Dec 11.

Department of Endocrinology, Diabetes and Metabolism, University Hospital Essen, University of Duisburg-Essen, 45147 Essen, Germany;

Thyroid hormone (TH) and TH receptors (TRs) α and β act by binding to TH response elements (TREs) in regulatory regions of target genes. This nuclear signaling is established as the canonical or type 1 pathway for TH action. Nevertheless, TRs also rapidly activate intracellular second-messenger signaling pathways independently of gene expression (noncanonical or type 3 TR signaling). To test the physiological relevance of noncanonical TR signaling, we generated knockin mice with a mutation in the TR DNA-binding domain that abrogates binding to DNA and leads to complete loss of canonical TH action. We show that several important physiological TH effects are preserved despite the disruption of DNA binding of TRα and TRβ, most notably heart rate, body temperature, blood glucose, and triglyceride concentration, all of which were regulated by noncanonical TR signaling. Additionally, we confirm that TRE-binding-defective TRβ leads to disruption of the hypothalamic-pituitary-thyroid axis with resistance to TH, while mutation of TRα causes a severe delay in skeletal development, thus demonstrating tissue- and TR isoform-specific canonical signaling. These findings provide in vivo evidence that noncanonical TR signaling exerts physiologically important cardiometabolic effects that are distinct from canonical actions. These data challenge the current paradigm that in vivo physiological TH action is mediated exclusively via regulation of gene transcription at the nuclear level.
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http://dx.doi.org/10.1073/pnas.1706801115DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5748168PMC
December 2017

BMPs as new insulin sensitizers: enhanced glucose uptake in mature 3T3-L1 adipocytes via PPARγ and GLUT4 upregulation.

Sci Rep 2017 12 8;7(1):17192. Epub 2017 Dec 8.

Institute of Chemistry and Biochemistry - Biochemistry, Berlin, Germany.

Insulin-resistance is the main cause of type 2 diabetes. Here we describe the identification and characterization of BMP2 and BMP6 as new insulin-sensitizing growth factors in mature adipocytes. We show that BMP2 and BMP6 lead to enhanced insulin-mediated glucose uptake in both insulin-sensitive and -insensitive adipocytes. We exclude a direct effect of BMP2 or BMP6 on translocation of GLUT4 to the plasma membrane and demonstrate that these BMPs increase GLUT4 protein levels equipotent to Rosiglitazone. BMPs induce expression of PPARγ as the crucial mediator for the insulin-sensitizing effect. A comprehensive RNA-Seq analysis in mature adipocytes revealed regulation of both BMP/Smad and PPARγ target genes. The effects of BMP2 and BMP6 are not completely redundant and include regulation of genes involved in glucose and fatty acid metabolism and adipokine expression. Collectively, these findings suggest the BMP2 and BMP6 pathway(s) as promising new drug targets to treat insulin resistance.
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http://dx.doi.org/10.1038/s41598-017-17595-5DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5722815PMC
December 2017