Publications by authors named "Andreas Zimmer"

343 Publications

Investigation into liquisolid system processability based on the SeDeM Expert System approach.

Int J Pharm 2021 Jun 30;605:120847. Epub 2021 Jun 30.

Department of Pharmaceutical Technology and Cosmetology, University of Belgrade - Faculty of Pharmacy, Vojvode Stepe 450, 11221 Belgrade, Serbia.

Liquisolid systems are emerging formulation approach for poorly soluble drugs, based on adsorption/absorption of drug dispersion and obtaining free-flowing powder with good compressibility. SeDeM Expert System represents a powder processability evaluation method. It may provide additional insight into liquisolid systems critical quality attributes, but the contribution of this approach remains to be explored. The aims of this study were: pellet preparation by combination of liquisolid technology and water granulation/extrusion, evaluation of liquisolid based systems (pellets/admixtures) and investigation into the applicability of SeDeM Expert System in liquisolid systems characterization. Pellets/admixtures were prepared with microcrystalline cellulose as carrier and crospovidone/silicon dioxide as coating agent. Ibuprofen solution in polyethylene glycol 400 was used as liquid phase. After comprehensive sample characterization, experimentally obtained parameters were mathematically transformed and evaluated in the SeDeM Expert System framework. Pellets exhibited low aspect ratio and excellent flowability, despite liquid load up to 52.2%. The investigated liquisolid admixtures exhibited good flowability and faster drug dissolution than pellets. Single pellet crushing test results exhibited strong correlation with compact indentation hardness and may be used as indentation hardness predictor. SeDeM Expert System provides useful insight into liquisolid system processability and comparative evaluation and it may facilitate final solid dosage form development.
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http://dx.doi.org/10.1016/j.ijpharm.2021.120847DOI Listing
June 2021

Use of Protamine in Nanopharmaceuticals-A Review.

Nanomaterials (Basel) 2021 Jun 7;11(6). Epub 2021 Jun 7.

Department of Pharmaceutical Technology and Biopharmacy, Institute of Pharmaceutical Sciences, Karl-Franzens-University Graz, Universitätsplatz 1, 8010 Graz, Austria.

Macromolecular biomolecules are currently dethroning classical small molecule therapeutics because of their improved targeting and delivery properties. Protamine-a small polycationic peptide-represents a promising candidate. In nature, it binds and protects DNA against degradation during spermatogenesis due to electrostatic interactions between the negatively charged DNA-phosphate backbone and the positively charged protamine. Researchers are mimicking this technique to develop innovative nanopharmaceutical drug delivery systems, incorporating protamine as a carrier for biologically active components such as DNA or RNA. The first part of this review highlights ongoing investigations in the field of protamine-associated nanotechnology, discussing the self-assembling manufacturing process and nanoparticle engineering. Immune-modulating properties of protamine are those that lead to the second key part, which is protamine in novel vaccine technologies. Protamine-based RNA delivery systems in vaccines (some belong to the new class of mRNA-vaccines) against infectious disease and their use in cancer treatment are reviewed, and we provide an update on the current state of latest developments with protamine as pharmaceutical excipient for vaccines.
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http://dx.doi.org/10.3390/nano11061508DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8230241PMC
June 2021

Impact of Surface Properties of Core Material on the Stability of Hot Melt-Coated Multiparticulate Systems.

Pharmaceutics 2021 Mar 10;13(3). Epub 2021 Mar 10.

Department of Pharmaceutical Technology and Biopharmacy, Institute of Pharmaceutical Science, University of Graz, 8010 Graz, Austria.

Hot melt coating (HMC) of an active pharmaceutical ingredient (API) powder with lipid-based excipients is an innovative method for manufacturing patient-convenient dosage forms. However, drug release instability is still its main industrial challenge. The correlation between the unstable pharmaceutical product performance with the solid-state alteration of lipids is currently well-investigated. The remaining problem is the inconsistent release alteration of different APIs coated with the same lipid after storage, such as faster release in some cases and slower release in others. The interaction between API surface and lipid-based coating and its alteration during storage were investigated in this work. The surface properties of five different APIs and the coating composition of tripalmitin and polysorbate 65 were screened via Washburn and pendant drop methods, respectively. Metformin hydrochloride and hydrochlorothiazide particles were each coated with the coating composition. The water sorption alteration of coated particles and the crystal growth of tripalmitin in the coating after storage were measured via tensiometry and X-ray diffraction. The cleavage work necessary to overcome the adhesion of coating composition on the core surface was calculated for each API. The accelerated release of the polar core (metformin) after storage was correlated with a low cleavage work and a distinctive phase separation. In contrast, a decelerated release of the hydrophobic core (hydrochlorothiazide) was favored by the crystal growth of the lipid-based coating. The gained knowledge can be used to design the product stability during the formulation development.
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http://dx.doi.org/10.3390/pharmaceutics13030366DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8001618PMC
March 2021

Cannabinoid receptor 1 signalling modulates stress susceptibility and microglial responses to chronic social defeat stress.

Transl Psychiatry 2021 03 15;11(1):164. Epub 2021 Mar 15.

Institute of Molecular Psychiatry, Medical Faculty, University of Bonn, Bonn, Germany.

Psychosocial stress is one of the main environmental factors contributing to the development of psychiatric disorders. In humans and rodents, chronic stress is associated with elevated inflammatory responses, indicated by increased numbers of circulating myeloid cells and activation of microglia, the brain-resident immune cells. The endocannabinoid system (ECS) regulates neuronal and endocrine stress responses via the cannabinoid receptor 1 (CB1). CB1-deficient mice (Cnr1) are highly sensitive to stress, but if this involves altered inflammatory responses is not known. To test this, we exposed Cnr1 and Cnr1 mice to chronic social defeat stress (CSDS). Cnr1 mice were extremely sensitive to a standard protocol of CSDS, indicated by an increased mortality rate. Therefore, a mild CSDS protocol was established, which still induced a behavioural phenotype in susceptible Cnr1 mice. These mice also showed altered glucocorticoid levels after mild CSDS, suggesting dysregulation of the hypothalamic-pituitary-adrenal (HPA) axis. Mild CSDS induced weak myelopoiesis in the periphery, but no recruitment of myeloid cells to the brain. In contrast, mild CSDS altered microglial activation marker expression and morphology in Cnr1 mice. These microglial changes correlated with the severity of the behavioural phenotype. Furthermore, microglia of Cnr1 mice showed increased expression of Fkbp5, an important regulator of glucocorticoid signalling. Overall, the results confirm that CB1 signalling protects the organism from the physical and emotional harm of social stress and implicate endocannabinoid-mediated modulation of microglia in the development of stress-related pathologies.
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http://dx.doi.org/10.1038/s41398-021-01283-0DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7961142PMC
March 2021

Porokeratosis Plantaris, Palmaris et Disseminata Caused by Con- genital Pathogenic Variants in the MVD Gene and Loss of Hetero-zygosity in Affected Skin.

Acta Derm Venereol 2021 Feb 16;101(2):adv00397. Epub 2021 Feb 16.

Institute of Human Genetics, Medical Center - University of Freiburg, Faculty of Medicine, University of Freiburg, DE-79106 Freiburg, Germany.

Porokeratoses are a heterogeneous group of keratinization disorders. For linear porokeratosis and disseminated superficial actinic porokeratosis, a heterozygous pathogenic germline variant in a mevalonate pathway gene and a postzygotic second hit mutation present in affected skin have been shown to be the patho-genetic mechanism for the development of the lesions. However, the molecular mechanism leading to development of porokeratosis plantaris, palmaris et disseminata is not known. This study analysed a cohort of 4 patients with linear porokeratosis and 3 patients with porokeratosis plantaris, palmaris et disseminata, and performed mutation analyses of DNA extracted from blood samples and skin biopsies. All of the study patients carried the heterozygous germline variant c.70+5G>A in the MVD gene. Loss of heterozygosity due to a second hit mutation was found in affected skin of 3 patients with linear porokeratosis and 2 patients with porokeratosis plantaris, palmaris et disseminata. These results suggest that porokeratosis plantaris, palmaris et disseminata shares the same pathogenetic mechanism as other porokeratosis subtypes and belongs to the phenotypic spectrum of MVD-associated porokeratosis.
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http://dx.doi.org/10.2340/00015555-3753DOI Listing
February 2021

Meta-Analysis of Mutations in or Identified in a Large Cohort of 224 Patients.

Genes (Basel) 2021 01 9;12(1). Epub 2021 Jan 9.

Department of Medical Sciences/Dermatology, Uppsala University, SE-751 85 Uppsala, Sweden.

The autosomal recessive congenital ichthyoses (ARCI) are a nonsyndromic group of cornification disorders that includes lamellar ichthyosis, congenital ichthyosiform erythroderma, and harlequin ichthyosis. To date mutations in ten genes have been identified to cause ARCI: , , , , , , , , , and . The main focus of this report is the mutational spectrum of the genes and , which encode the epidermal lipoxygenases arachidonate 12-lipoxygenase, i.e., 12R type (12R-LOX), and the epidermis-type lipoxygenase-3 (eLOX3), respectively. Deficiency of 12R-LOX and eLOX3 disrupts the epidermal barrier function and leads to an abnormal epidermal differentiation. The type and the position of the mutations may influence the ARCI phenotype; most patients present with a mild erythrodermic ichthyosis, and only few individuals show severe erythroderma. To date, 88 pathogenic mutations in and 27 pathogenic mutations in have been reported in the literature. Here, we presented a large cohort of 224 genetically characterized ARCI patients who carried mutations in these genes. We added 74 novel mutations in and 25 novel mutations in . We investigated the spectrum of mutations in and in our cohort and additionally in the published mutations, the distribution of these mutations within the gene and gene domains, and potential hotspots and recurrent mutations.
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http://dx.doi.org/10.3390/genes12010080DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7826849PMC
January 2021

Lack of Cannabinoid Receptor Type-1 Leads to Enhanced Age-Related Neuronal Loss in the Locus Coeruleus.

Int J Mol Sci 2020 Dec 22;22(1). Epub 2020 Dec 22.

Institute of Molecular Psychiatry, Medical Faculty, University of Bonn, Venusberg-Campus 1, 53127 Bonn, Germany.

Our laboratory and others have previously shown that cannabinoid receptor type-1 (CB1r) activity is neuroprotective and a modulator of brain ageing; a genetic disruption of CB1r signaling accelerates brain ageing, whereas the pharmacological stimulation of CB1r activity had the opposite effect. In this study, we have investigated if the lack of CB1r affects noradrenergic neurons in the locus coeruleus (LC), which are vulnerable to age-related changes; their numbers are reduced in patients with neurodegenerative diseases and probably also in healthy aged individuals. Thus, we compared LC neuronal numbers between cannabinoid 1 receptor knockout () mice and their wild-type littermates. Our results reveal that old mice have less noradrenergic neurons compared to their age-matched wild-type controls. This result was also confirmed by the analysis of the density of noradrenergic terminals which proved that mice had less compared to the wild-type controls. Additionally, we assessed pro-inflammatory glial activity in the LC. Although the density of microglia in mice was enhanced, they did not show enhanced inflammatory profile. We hypothesize that CB1r activity is necessary for the protection of noradrenergic neurons, but its anti-inflammatory effect probably only plays a minor role in it.
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http://dx.doi.org/10.3390/ijms22010005DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7792602PMC
December 2020

Neonatal presentation of COG6-CDG with prominent skin phenotype.

JIMD Rep 2020 Sep 7;55(1):51-58. Epub 2020 Aug 7.

Institute of Human Genetics, Medical Center University of Freiburg, Faculty of Medicine, University of Freiburg Freiburg Germany.

Many of the genetic childhood disorders leading to death in the perinatal period follow autosomal recessive inheritance and bear specific challenges for genetic counseling and prenatal diagnostics. Often, affected children die before a genetic diagnosis can be established, thereby precluding targeted carrier testing in parents and prenatal or preimplantation genetic diagnosis in further pregnancies. The clinical phenotype of congenital disorders of glycosylation (CDG) is very heterogeneous and ranges from relatively mild symptoms to severe multisystem dysfunction and even a fatal course. A very rare subtype, COG6-CDG, is caused by deficiency of subunit 6 of the conserved oligomeric Golgi complex and is usually characterized by growth retardation, developmental delay, microcephaly, liver and gastrointestinal disease, joint contractures and episodic fever. It has been proposed that a distinctive feature of COG6-CDG can be ectodermal signs such as hypohidrosis/hyperthermia, hyperkeratosis and tooth anomalies. In a Greek family, who had lost two children in the neonatal period, with prominent skin features initially resembling restrictive dermopathy, severe arthrogryposis, respiratory insufficiency and a rapid fatal course trio whole-exome sequencing revealed the homozygous nonsense mutation c.511C>T, p.(Arg171*) in the gene. Skin manifestations such as dry skin and hyperkeratosis have been reported in only five out of the 21 reported COG6-CDG cases so far, including two patients with the c.511C>T variant in but with milder ectodermal symptoms. Our case adds to the phenotypic spectrum of COG6-CDG with prominent ectodermal manifestations at birth and underlines the importance of considering CDG among the possible causes for congenital syndromic genodermatoses.
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http://dx.doi.org/10.1002/jmd2.12154DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7463048PMC
September 2020

Intestine-specific DGAT1 deficiency improves atherosclerosis in apolipoprotein E knockout mice by reducing systemic cholesterol burden.

Atherosclerosis 2020 10 10;310:26-36. Epub 2020 Aug 10.

Gottfried Schatz Research Center, Medical University of Graz, Graz, Austria; BioTechMed-Graz, Graz, Austria. Electronic address:

Background And Aims: Acyl-CoA:diacylglycerol acyltransferase 1 (DGAT1) is the rate-limiting enzyme catalyzing the final step of triglyceride synthesis by esterifying a diglyceride with a fatty acid. We have previously shown that apolipoprotein E-knockout (ApoE) mice lacking Dgat1 have reduced intestinal cholesterol absorption and potentiated macrophage cholesterol efflux, and consequently, exhibit attenuated atherogenesis. However, hematopoietic Dgat1 deficiency lacked beneficial effects on atherosclerosis. Due to our recent results on the critical role of intestinal Dgat1 in murine cholesterol homeostasis, we delineated whether intestinal Dgat1 deficiency regulates atherogenesis in mice.

Methods: We generated intestine-specific Dgat1 mice on the ApoE background (iDgat1ApoE) and determined cholesterol homeostasis and atherosclerosis development.

Results: When fed a Western-type diet, iDgat1ApoE mice exhibited a substantial decrease in fasting plasma cholesterol content in ApoB-containing lipoproteins. Although lipid absorption was delayed, iDgat1ApoE mice had reduced acute and fractional cholesterol absorption coupled with an elevated fecal caloric loss. In line, increased appearance of i.v. administered [³H]cholesterol in duodena and stool of iDgat1ApoE animals suggested potentiated cholesterol elimination. Atherosclerotic lesions were markedly smaller with beneficial alterations in plaque composition as evidenced by reduced macrophage infiltration and necrotic core size despite unaltered collagen content, indicating improved plaque stability.

Conclusions: Disruption of Dgat1 activity solely in the small intestine of ApoE mice strongly decreased plasma cholesterol levels by abrogating the assimilation of dietary cholesterol, partly by reduced absorption and increased excretion. Consequently, the reduced cholesterol burden significantly attenuated atherogenesis and improved the lesion phenotype in iDgat1ApoE mice.
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http://dx.doi.org/10.1016/j.atherosclerosis.2020.07.030DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7116265PMC
October 2020

Diacylglycerol lipase alpha in astrocytes is involved in maternal care and affective behaviors.

Glia 2021 Feb 2;69(2):377-391. Epub 2020 Sep 2.

Institute of Molecular Psychiatry, Medical Faculty, University of Bonn, Bonn, Germany.

Genetic deletion of cannabinoid CB1 receptors or diacylglycerol lipase alpha (DAGLa), the main enzyme involved in the synthesis of the endocannabinoid (eCB) 2-arachidonoylglycerol (2-AG), produced profound phenotypes in animal models of depression-related behaviors. Furthermore, clinical studies have shown that antagonists of CB1 can increase the incidence and severity of major depressive episodes. However, the underlying pathomechanisms are largely unknown. In this study, we have focused on the possible involvement of astrocytes. Using the highly sensitive RNAscope technology, we show for the first time that a subpopulation of astrocytes in the adult mouse brain expresses Dagla, albeit at low levels. Targeted lipidomics revealed that astrocytic DAGLa only accounts for a minor percentage of the steady-state brain 2-AG levels and other arachidonic acid derived lipids like prostaglandins. Nevertheless, the deletion of Dagla in adult mouse astrocytes had profound behavioral consequences with significantly increased depressive-like behavioral responses and striking effects on maternal behavior, corresponding with increased levels of serum progesterone and estradiol. Our findings therefore indicate that lipids from the DAGLa metabolic axis in astrocytes play a key regulatory role in affective behaviors.
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http://dx.doi.org/10.1002/glia.23903DOI Listing
February 2021

Telangiectasia-ectodermal dysplasia-brachydactyly-cardiac anomaly syndrome is caused by de novo mutations in .

J Med Genet 2021 Jun 17;58(6):415-421. Epub 2020 Aug 17.

Institute of Human Genetics, Medical Center - University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany

Background: We describe two unrelated patients who display similar clinical features including telangiectasia, ectodermal dysplasia, brachydactyly and congenital heart disease.

Methods: We performed trio whole exome sequencing and functional analysis using in vitro kinase assays with recombinant proteins.

Results: We identified two different de novo mutations in ( NM_002742.2): c.1774G>C, p.(Gly592Arg) and c.1808G>A, p.(Arg603His), one in each patient. (, HGNC:9407) encodes a kinase that is a member of the protein kinase D (PKD) family of serine/threonine protein kinases involved in diverse cellular processes such as cell differentiation and proliferation and cell migration as well as vesicle transport and angiogenesis. Functional analysis using in vitro kinase assays with recombinant proteins showed that the mutation c.1808G>A, p.(Arg603His) represents a gain-of-function mutation encoding an enzyme with a constitutive, lipid-independent catalytic activity. The mutation c.1774G>C, p.(Gly592Arg) in contrast shows a defect in substrate phosphorylation representing a loss-of-function mutation.

Conclusion: The present cases represent a syndrome, which associates symptoms from several different organ systems: skin, teeth, bones and heart, caused by heterozygous de novo mutations in and expands the clinical spectrum of mutations, which have hitherto been linked to syndromic congenital heart disease and limb abnormalities.
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http://dx.doi.org/10.1136/jmedgenet-2019-106564DOI Listing
June 2021

Protective role of neuronal and lymphoid cannabinoid CB receptors in neuropathic pain.

Elife 2020 07 20;9. Epub 2020 Jul 20.

Laboratory of Neuropharmacology, Department of Experimental and Health Sciences, Universitat Pompeu Fabra, Barcelona, Spain.

Cannabinoid CB receptor (CB) agonists are potential analgesics void of psychotropic effects. Peripheral immune cells, neurons and glia express CB; however, the involvement of CB from these cells in neuropathic pain remains unresolved. We explored spontaneous neuropathic pain through on-demand self-administration of the selective CB agonist JWH133 in wild-type and knockout mice lacking CB in neurons, monocytes or constitutively. Operant self-administration reflected drug-taking to alleviate spontaneous pain, nociceptive and affective manifestations. While constitutive deletion of CB disrupted JWH133-taking behavior, this behavior was not modified in monocyte-specific CB knockouts and was increased in mice defective in neuronal CB knockouts suggestive of increased spontaneous pain. Interestingly, CB-positive lymphocytes infiltrated the injured nerve and possible CBtransfer from immune cells to neurons was found. Lymphocyte CBdepletion also exacerbated JWH133 self-administration and inhibited antinociception. This work identifies a simultaneous activity of neuronal and lymphoid CBthat protects against spontaneous and evoked neuropathic pain.
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http://dx.doi.org/10.7554/eLife.55582DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7384863PMC
July 2020

Vancomycin Loaded Glycerol Monooleate Liquid Crystalline Phases Modified with Surfactants.

Pharmaceutics 2020 Jun 8;12(6). Epub 2020 Jun 8.

Department of Pharmaceutical Technology and Biopharmacy, Institute of Pharmaceutical Sciences, University of Graz, NAWI Graz, Universitätsplatz 1, 8010 Graz, Austria.

The influence of two tuning agents, polyglycerol ester (PE) and triblock copolymer (TC), on the properties of glycerol monooleate (MO) liquid crystalline phase (LCP) was investigated to achieve the therapeutic concentration of vancomycin hydrochloride (VHCl) into the eye, topically during 60 min (1 h) and intravitreally during 2880 min (48 h). Different techniques were used to elucidate the impact of surfactants on the structure of the LCP: polarized light microscopy (PLM), small-angle X-ray scattering (SAXS), and in vitro release tests I and II (simulating local and intravitreal application in the eye). The structure analysis by SAXS depicts that the inclusion of PE into the MO LCP provided partial transition of a hexagonal phase into a lamellar phase, and TC induced a partial transition of a hexagonal phase into an LCP which identification was difficult. The LCP modulated with PE and TC demonstrated different VHCl's release patterns and were evaluated by comparing our release data with the literature data. The comparison indicated that the LCP modulated with 30% / PE could be a promising VHCl delivery system intravitreally during 2880 min.
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http://dx.doi.org/10.3390/pharmaceutics12060521DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7356114PMC
June 2020

Hot Melt Coating of Amorphous Carvedilol.

Pharmaceutics 2020 Jun 6;12(6). Epub 2020 Jun 6.

Department of Pharmacy, University of Copenhagen, Universitetsparken 2, DK-2100 Copenhagen, Denmark.

The use of amorphous drug delivery systems is an attractive approach to improve the bioavailability of low molecular weight drug candidates that suffer from poor aqueous solubility. However, the pharmaceutical performance of many neat amorphous drugs is compromised by their tendency for recrystallization during storage and lumping upon dissolution, which may be improved by the application of coatings on amorphous surfaces. In this study, hot melt coating (HMC) as a solvent-free coating method was utilized to coat amorphous carvedilol (CRV) particles with tripalmitin containing 10% () and 20% () of polysorbate 65 (PS65) in a fluid bed coater. Lipid coated amorphous particles were assessed in terms of their physical stability during storage and their drug release during dynamic in vitro lipolysis. The release of CRV during in vitro lipolysis was shown to be mainly dependent on the PS65 concentration in the coating layer, with a PS65 concentration of 20% () resulting in an immediate release profile. The physical stability of the amorphous CRV core, however, was negatively affected by the lipid coating, resulting in the recrystallization of CRV at the interface between the crystalline lipid layer and the amorphous drug core. Our study demonstrated the feasibility of lipid spray coating of amorphous CRV as a strategy to modify the drug release from amorphous systems but at the same time highlights the importance of surface-mediated processes for the physical stability of the amorphous form.
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http://dx.doi.org/10.3390/pharmaceutics12060519DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7356097PMC
June 2020

Activation of Somatostatin Interneurons by Nicotinic Modulator Lypd6 Enhances Plasticity and Functional Recovery in the Adult Mouse Visual Cortex.

J Neurosci 2020 07 28;40(27):5214-5227. Epub 2020 May 28.

Department of Psychiatry, Icahn School of Medicine at Mount Sinai, New York, New York 10029

The limitation of plasticity in the adult brain impedes functional recovery later in life from brain injury or disease. This pressing clinical issue may be resolved by enhancing plasticity in the adult brain. One strategy for triggering robust plasticity in adulthood is to reproduce one of the hallmark physiological events of experience-dependent plasticity observed during the juvenile critical period: to rapidly reduce the activity of parvalbumin (PV)-expressing interneurons and disinhibit local excitatory neurons. This may be achieved through the enhancement of local inhibitory inputs, particularly those of somatostatin (SST)-expressing interneurons. However, to date the means for manipulating SST interneurons for enhancing cortical plasticity in the adult brain are not known. We show that SST interneuron-selective overexpression of Lypd6, an endogenous nicotinic signaling modulator, enhances ocular dominance plasticity in the adult primary visual cortex (V1). Lypd6 overexpression mediates a rapid experience-dependent increase in the visually evoked activity of SST interneurons as well as a simultaneous reduction in PV interneuron activity and disinhibition of excitatory neurons. Recapitulating this transient activation of SST interneurons using chemogenetics similarly enhanced V1 plasticity. Notably, we show that SST-selective Lypd6 overexpression restores visual acuity in amblyopic mice that underwent early long-term monocular deprivation. Our data in both male and female mice reveal selective modulation of SST interneurons and a putative downstream circuit mechanism as an effective method for enhancing experience-dependent cortical plasticity as well as functional recovery in adulthood. The decline of cortical plasticity after closure of juvenile critical period consolidates neural circuits and behavior, but this limits functional recovery from brain diseases and dysfunctions in later life. Here we show that activation of cortical somatostatin (SST) interneurons by Lypd6, an endogenous modulator of nicotinic acetylcholine receptors, enhances experience-dependent plasticity and recovery from amblyopia in adulthood. This manipulation triggers rapid reduction of PV interneuron activity and disinhibition of excitatory neurons, which are known hallmarks of cortical plasticity during juvenile critical periods. Our study demonstrates modulation of SST interneurons by Lypd6 to achieve robust levels of cortical plasticity in the adult brain and may provide promising targets for restoring brain function in the event of brain trauma or disease.
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http://dx.doi.org/10.1523/JNEUROSCI.1373-19.2020DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7329312PMC
July 2020

Influence of Cannabinoid Receptor Deficiency on Parameters Involved in Blood Glucose Regulation in Mice.

Int J Mol Sci 2020 Apr 30;21(9). Epub 2020 Apr 30.

Institute of Anatomy and Cell Biology, Medical Faculty of Martin Luther, University Halle-Wittenberg, 06108 Halle (Saale), Germany.

Cannabinoids are known to influence hormone secretion of pancreatic islets via G protein‑coupled cannabinoid receptor type 1 and 2 (CB and CB). The present study was designed to further investigate the impact of cannabinoid receptors on the parameters involved in insulin secretion and blood glucose recognition. To this end, CB and CB receptor knockout mice (10-12 week old, both sexes) were characterised at basal state and compared to wild-type mice. The elimination of cannabinoid receptor signalling resulted in alterations of blood glucose concentrations, body weights and insulin levels. Changes were dependent on the deleted receptor type and on the sex. Analyses at mRNA and protein levels provided evidence for the impact of cannabinoid receptor deficiency on the glucose sensing apparatus in the pancreas. Both receptor knockout mouse lines showed decreased mRNA and protein amounts of glucose transporters Glut1 and Glut2, combined with alterations in immunostaining. In addition, pancreatic glucokinase expression was elevated and immunohistochemical labelling was modified in the pancreatic islets. Taken together, CB and CB signalling pathways seem to influence glucose sensing in β-cells by affecting glucose transporters and glucokinase. These alterations were more pronounced in CB knockout mice, resulting in higher blood glucose and lower plasma insulin levels.
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http://dx.doi.org/10.3390/ijms21093168DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7246639PMC
April 2020

Severe metabolic alterations in liver cancer lead to ERK pathway activation and drug resistance.

EBioMedicine 2020 Apr 21;54:102699. Epub 2020 Apr 21.

Department of Medicine II, Molecular Hepatology Section, Medical Faculty Mannheim, University of Heidelberg, 68167 Mannheim, Germany. Electronic address:

Background: The extracellular signal-regulated kinase (ERK) pathway regulates cell growth, and is hyper-activated and associated with drug resistance in hepatocellular carcinoma (HCC). Metabolic pathways are profoundly dysregulated in HCC. Whether an altered metabolic state is linked to activated ERK pathway and drug response in HCC is unaddressed.

Methods: We deprived HCC cells of glutamine to induce metabolic alterations and performed various assays, including metabolomics (with C-glucose isotope tracing), microarray analysis, and cell proliferation assays. Glutamine-deprived cells were also treated with kinase inhibitors (e.g. Sorafenib, Erlotinib, U0126 amongst other MEK inhibitors). We performed bioinformatics analysis and stratification of HCC tumour microarrays to determine upregulated ERK gene signatures in patients.

Findings: In a subset of HCC cells, the withdrawal of glutamine triggers a severe metabolic alteration and ERK phosphorylation (pERK). This is accompanied by resistance to the anti-proliferative effect of kinase inhibitors, despite pERK inhibition. High intracellular serine is a consistent feature of an altered metabolic state and contributes to pERK induction and the kinase inhibitor resistance. Blocking the ERK pathway facilitates cell proliferation by reprogramming metabolism, notably enhancing aerobic glycolysis. We have identified 24 highly expressed ERK gene signatures that their combined expression strongly indicates a dysregulated metabolic gene network in human HCC tissues.

Interpretation: A severely compromised metabolism lead to ERK pathway induction, and primes some HCC cells to pro-survival phenotypes upon ERK pathway blockade. Our findings offer novel insights for understanding, predicting and overcoming drug resistance in liver cancer patients. FUND: DFG, BMBF and Sino-German Cooperation Project.
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http://dx.doi.org/10.1016/j.ebiom.2020.102699DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7182727PMC
April 2020

Age-dependent Alteration in Mitochondrial Dynamics and Autophagy in Hippocampal Neuron of Cannabinoid CB1 Receptor-deficient Mice.

Brain Res Bull 2020 07 12;160:40-49. Epub 2020 Apr 12.

Faculty of Science and Engineering, Waseda University, 169-8555, Shinjuku, Tokyo, Japan. Electronic address:

Endocannabinoid system activity contributes to the homeostatic defense against aging and thus may counteract the progression of brain aging. The cannabinoid type 1 (CB1) receptor activity declines with aging in the brain, which impairs neuronal network integrity and cognitive functions. However, the underlying mechanisms that link CB1 activity and memory decline remain unknown. Mitochondrial activity profoundly influences neuronal function, and age-dependent mitochondrial activity change is one of the known hallmarks of brain aging. As CB1 receptor is expressed on mitochondria and may regulate neuronal energy metabolism in hippocampus, we hypothesized that CB1 receptors might influence mitochondria in hippocampal neurons. Here, we found that CB1 receptor significantly affected mitochondrial autophagy (mitophagy) and morphology in an age-dependent manner. Serine 65-phosphorylated ubiquitin, a key marker for mitophagy, was reduced in adult CB1-deficient mice (CB1-KO) compared to those in wild type controls, particularly in CA1 pyramidal cell layer. Transmission electron microscopy (TEM) analysis showed reduced mitophagy-like events in hippocampus of adult CB1-KO. TEM analysis also showed that mitochondrial morphology in adult CB1-KO mice was altered shown by an increase in thin and elongated mitochondria in hippocampal neurons. 3D reconstruction of mitochondrial morphology after scanning electron microscopy additionally revealed an enhanced density of interconnected mitochondria. Altogether, these findings suggest that reduced CB1 signaling in CB1-KO mice leads to reduced mitophagy and abnormal mitochondrial morphology in hippocampal neurons during aging. These mitochondrial changes might be due to the impairments in mitochondrial quality control system, which links age-related decline in CB1 activity and impaired memory.
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http://dx.doi.org/10.1016/j.brainresbull.2020.03.014DOI Listing
July 2020

Revisiting CB cannabinoid receptor detection and the exploration of its interacting partners.

J Neurosci Methods 2020 05 4;337:108680. Epub 2020 Mar 4.

Laboratory of Neuroinflammation, Hospital Nacional de Parapléjicos (SESCAM), Toledo, Spain. Electronic address:

Background: Cannabinoid receptor 1 (CB) identification by western blot (WB) has generated a great deal of controversial data making the interpretation of the results difficult. Our purpose is to find the most adequate experimental conditions to detect CB by WB and immunoprecipitation (IP) as a first step towards the study of CB interactome.

New Method: We use CB knockout mice tissue as negative controls and describe appropriate sample handling conditions for CB detection by WB and IP from brain and cortical neuron cultures.

Results: Sample heating above 65 °C greatly impaired CB detection by WB, since it favored the formation of high molecular weight aggregates. We also show the convenience of using n-dodecyl-β-d-maltoside (DDM) as a detergent for the detection of CB by WB and, mostly, for IP.

Comparison With Existing Method(s): We obtain consistent and specific CB detection by WB and IP using four different commercial antibodies and KO tissue for an accurate CB identification. We clarify the identification of the receptor in complex samples compared with the diverse and unclear results obtained using standard WB methods.

Conclusions: We establish experimental guidelines for the detection of CB by WB and the study of CB interacting proteins by IP. We propose a new interpretation of CB WB and IP data based on the folding and packing state of the protein and the detergent used. The standardization of the most advantageous conditions for coimmunoprecipitation (CoIP) would be a useful tool for the future study of the interactome of CB.
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http://dx.doi.org/10.1016/j.jneumeth.2020.108680DOI Listing
May 2020

Modulation of feeding behavior and metabolism by dynorphin.

Sci Rep 2020 03 2;10(1):3821. Epub 2020 Mar 2.

Institute of Molecular Psychiatry, University of Bonn, Medical Faculty, Venusberg-Campus 1, 53127, Bonn, Germany.

The neuronal regulation of metabolic and behavioral responses to different diets and feeding regimens is an important research area. Herein, we investigated if the opioid peptide dynorphin modulates feeding behavior and metabolism. Mice lacking dynorphin peptides (KO) were exposed to either a normal diet (ND) or a high-fat diet (HFD) for a period of 12 weeks. Additionally, mice had either time-restricted (TR) or ad libitum (AL) access to food. Body weight, food intake and blood glucose levels were monitored throughout the 12-week feeding schedule. Brain samples were analyzed by immunohistochemistry to detect changes in the expression levels of hypothalamic peptides. As expected, animals on HFD or having AL access to food gained more weight than mice on ND or having TR access. Unexpectedly, KO females on TR HFD as well as KO males on AL ND or AL HFD demonstrated a significantly increased body weight gain compared to the respective WT groups. The calorie intake differed only marginally between the genotypes: a significant difference was present in the female ND AL group, where dynorphin KO mice ate more than WT mice. Although female KO mice on a TR feeding regimen consumed a similar amount of food as WT controls, they displayed significantly higher levels of blood glucose. We observed significantly reduced levels of hypothalamic orexigenic peptides neuropeptide Y (NPY) and orexin-A in KO mice. This decrease became particularly pronounced in the HFD groups and under AL condition. The kappa opiod receptor (KOR) levels were higher after HFD compared to ND feeding in the ventral pallidum of WT mice. We hypothesize that HFD enhances dynorphin signaling in this hedonic center to maintain energy homeostasis, therefore KO mice have a more pronounced phenotype in the HFD condition due to the lack of it. Our data suggest that dynorphin modulates metabolic changes associated with TR feeding regimen and HFD consumption. We conclude that the lack of dynorphin causes uncoupling between energy intake and body weight gain in mice; KO mice maintained on HFD become overweight despite their normal food intake. Thus, using kappa opioid receptor agonists against obesity could be considered as a potential treatment strategy.
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http://dx.doi.org/10.1038/s41598-020-60518-0DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7052232PMC
March 2020

Internalization mechanisms of cell-penetrating peptides.

Beilstein J Nanotechnol 2020 9;11:101-123. Epub 2020 Jan 9.

Institute of Pharmaceutical Sciences, Department of Pharmaceutical Technology and Biopharmacy, University of Graz, 8010 Graz, Austria.

In today's modern era of medicine, macromolecular compounds such as proteins, peptides and nucleic acids are dethroning small molecules as leading therapeutics. Given their immense potential, they are highly sought after. However, their application is limited mostly due to their poor in vivo stability, limited cellular uptake and insufficient target specificity. Cell-penetrating peptides (CPPs) represent a major breakthrough for the transport of macromolecules. They have been shown to successfully deliver proteins, peptides, siRNAs and pDNA in different cell types. In general, CPPs are basic peptides with a positive charge at physiological pH. They are able to translocate membranes and gain entry to the cell interior. Nevertheless, the mechanism they use to enter cells still remains an unsolved piece of the puzzle. Endocytosis and direct penetration have been suggested as the two major mechanisms used for internalization, however, it is not all black and white in the nanoworld. Studies have shown that several CPPs are able to induce and shift between different uptake mechanisms depending on their concentration, cargo or the cell line used. This review will focus on the major internalization pathways CPPs exploit, their characteristics and regulation, as well as some of the factors that influence the cellular uptake mechanism.
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http://dx.doi.org/10.3762/bjnano.11.10DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6964662PMC
January 2020

Cannabinoid Receptor 2 Modulates Maturation of Dendritic Cells and Their Capacity to Induce Hapten-Induced Contact Hypersensitivity.

Int J Mol Sci 2020 Jan 11;21(2). Epub 2020 Jan 11.

Department of Psychiatry, University of Münster, 48149 Münster, Germany.

Contact hypersensitivity (CHS) is an established animal model for allergic contact dermatitis. Dendritic cells (DCs) play an important role in the sensitization phase of CHS by initiating T cell responses to topically applied haptens. The cannabinoid receptors 1 (CB1) and 2 (CB2) modulate DC functions and inflammatory skin responses, but their influence on the capacity of haptenized DCs to induce CHS is still unknown. We found lower CHS responses to 2,4-dinitro-1-fluorobenzene (DNFB) in wild type (WT) mice after adoptive transfer of haptenized and bone marrow (BM) DCs as compared to transfer of WT DCs. In contrast, induction of CHS was not affected in WT recipients after transfer of DCs. In vitro stimulated DCs showed lower CCR7 and CXCR4 expression when compared to WT cells, while in vitro migration towards the chemokine ligands was not affected by CB2. Upregulation of MHC class II and co-stimulatory molecules was also reduced in DCs. This study demonstrates that CB2 modulates the maturation phenotype of DCs but not their chemotactic capacities . These findings and the fact that CHS responses mediated by 2 DCs are reduced suggest that CB2 is a promising target for the treatment of inflammatory skin conditions.
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http://dx.doi.org/10.3390/ijms21020475DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7013892PMC
January 2020

Biological Activity Of miRNA-27a Using Peptide-based Drug Delivery Systems.

Int J Nanomedicine 2019 25;14:7795-7808. Epub 2019 Sep 25.

Department of Pharmaceutical Technology and Biopharmacy, Institute of Pharmaceutical Sciences, University of Graz, Graz 8010, Austria.

Background: Endogenously expressed microRNAs (miRNAs) have attracted attention as important regulators in post-transcriptionally controlling gene expression of various physiological processes. As miRNA dysregulation is often associated with various disease patterns, such as obesity, miRNA-27a might therefore be a promising candidate for miRNA mimic replacement therapy by inhibiting adipogenic marker genes. However, application of naked nucleic acids faces some limitations concerning poor enzymatic stability, bio-membrane permeation and cellular uptake. To overcome these obstacles, the development of appropriate drug delivery systems (DDS) for miRNAs is of paramount importance.

Methods: In this work, a triple combination of atomic force microscopy (AFM), brightfield (BF) and fluorescence microscopy was used to trace the cellular adhesion of N-TER peptide-nucleic acid complexes followed by time-dependent uptake studies using confocal laser scanning microscopy (cLSM). To reveal the biological effect of miRNA-27a on adipocyte development after transfection treatment, Oil-Red-O (ORO)- staining was performed to estimate the degree of in lipid droplets accumulated ORO in mature adipocytes by using light microscopy images as well as absorbance measurements.

Results: The present findings demonstrated that amphipathic N-TER peptides represent a suitable DDS for miRNAs by promoting non-covalent complexation through electrostatic interactions between both components as well as cellular adhesion of the N-TER peptide - nucleic acid complexes followed by uptake across cell membranes and intracellular release of miRNAs. The anti-adipogenic effect of miRNA-27a in 3T3-L1 cells could be detected in mature adipocytes by reduced lipid droplet formation.

Conclusion: The present DDS assembled from amphipathic N-TER peptides and miRNAs is capable of inducing the anti-adipogenic effect of miRNA-27a by reducing lipid droplet accumulation in mature adipocytes. With respect to miRNA mimic replacement therapies, this approach might provide new therapeutic strategies to prevent or treat obesity and obesity-related disorders.
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http://dx.doi.org/10.2147/IJN.S208446DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6768125PMC
November 2019

Comparison of PEGylated and non-PEGylated proticles: An in vitro and in vivo study.

Eur J Pharm Sci 2019 Nov 2;139:105063. Epub 2019 Sep 2.

Institute of Pharmaceutical Sciences, Department of Pharmaceutical Technology and Biopharmacy, Karl-Franzens-University Graz, Universitätsplatz 1, 8010 Graz, Austria. Electronic address:

The development of so-called Proticles opens attractive possibilities for new drug delivery systems. Proticles are nanoparticles (NPs), which are formed by self-assembly of negatively charged oligonucleotides in combination with the positively charged peptide protamine. Polyethylene glycol (PEG) is a widely known pharmaceutical agent to stop particle growth and prolong circulation half-life of drug delivery systems. Therefore, two different NP formulations - one PEGylated and one non-PEGylated - were used in this work to gain information about the biological stability and half-life in circulation of Proticles. Thus, this study presents data of in vitro stability and in vivo pharmacokinetics of both, non-PEGylated and PEGylated Proticles radiolabeled with InCl. The study demonstrated that successful radiolabeling of both Proticle-formulations was performed resulting in high radiochemical yields (> 85 %). Furthermore, the influence of PEGylation on the in vitro stability of In-radiolabeled NPs was investigated. No significant difference due to PEGylation was found. Unlike in vitro results, non-PEGylated In-Proticles seemed to degrade faster in vivo than PEGylated In-proticles, resulting in significantly higher blood values (In-PEG-proticles: 0.23 ± 0.01 % ID/g 1 h p.i.; In-proticles: 0.06 ± 0.01 % ID/g 1 h p.i.; p < 0.05). Visualized by SPECT imaging urinary excretion represented the major pathway of elimination for both NP-formulations. In conclusion, this study provides data indicating a positive influence of PEG-derivatization on the biodistribution and pharmacokinetics of Proticles. These results form the basis for further developments as drug delivery and active drug targeting devices.
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http://dx.doi.org/10.1016/j.ejps.2019.105063DOI Listing
November 2019

A Protocol To Characterize Peptide-Based Drug Delivery Systems for miRNAs.

ACS Omega 2019 Apr 18;4(4):7014-7022. Epub 2019 Apr 18.

Department of Pharmaceutical Technology and Biopharmacy, Institute of Pharmaceutical Sciences, University of Graz, 8010 Graz, Austria.

Micro RNA (miRNA)-based medicines have attracted attention as new therapeutic strategies to treat genetic diseases and metabolic and immunological disorders. MiRNAs have emerged as key mediators of metabolic processes fulfilling regulatory functions in maintaining physiological conditions, while altered miRNA expression profiles are often associated with genetic diseases. However, naked miRNAs exhibit poor enzymatic stability, biomembrane permeation, and cellular uptake. To overcome these limitations, the development of appropriate drug delivery systems (DDS) is necessary. Herein, a DDS is characterized being assembled from miRNA-27a (negative regulator in fat metabolism) and the amphipathic N-TER peptide. Dynamic light scattering (DLS), electrophoretic light scattering, and atomic force microscopy (AFM) are used to investigate physicochemical properties (i.e., size, shape, and charge) of the DDS. Although surface charges should provide decent stabilization, the AFM results confirm a state of agglomeration, which is also suggested by DLS. Furthermore, AFM studies reveal adhesion on hydrophilic as well as hydrophobic substrates, which is related to the amphipathic properties of the N-TER peptide. Physicochemical properties of DDS are important parameters, which have an impact on cell internalization/uptake and have to be taken into account for in vitro studies to develop a successful peptide-based DDS for miRNA replacement therapy in metabolic diseases, such as obesity and others.
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http://dx.doi.org/10.1021/acsomega.8b03562DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6648615PMC
April 2019

Genetical, clinical, and functional analysis of a large international cohort of patients with autosomal recessive congenital ichthyosis due to mutations in NIPAL4.

Hum Mutat 2019 12 6;40(12):2318-2333. Epub 2019 Sep 6.

Institute of Human Genetics, Medical Center - University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany.

Autosomal recessive congenital ichthyosis (ARCI) belongs to a heterogeneous group of disorders of keratinization. To date, 10 genes have been identified to be causative for ARCI. NIPAL4 (Nipa-Like Domain-Containing 4) is the second most commonly mutated gene in ARCI. In this study, we present a large cohort of 101 families affected with ARCI carrying mutations in NIPAL4. We identified 16 novel mutations and increase the total number of pathogenic mutations in NIPAL4 to 34. Ultrastructural analysis of biopsies from six patients showed morphological abnormalities consistent with an ARCI EM type III. One patient with a homozygous splice site mutation, which leads to a loss of NIPAL4 mRNA, showed additional ultrastructural aberrations together with a more severe clinical phenotype. Our study gives insights into the frequency of mutations, a potential hot spot for mutations, and genotype-phenotype correlations.
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http://dx.doi.org/10.1002/humu.23883DOI Listing
December 2019

Myocardial maladaptation to pressure overload in CB2 receptor-deficient mice.

J Mol Cell Cardiol 2019 08 7;133:86-98. Epub 2019 Jun 7.

Department of Cardiac Surgery, University Clinical Centre Bonn, Germany. Electronic address:

Background: Adaptation to aortic valve stenosis leads to myocardial hypertrophy, which has been associated with inflammation, fibrosis and activation of the endocannabinoid system. Since the endocannabinoid system and the CB2 receptor provide cardioprotection and modulate immune response in experimental ischemia, we investigated the role of CB2 in a mouse model of cardiac pressure overload.

Methods: Transverse aortic constriction was performed in CB2 receptor-deficient (Cnr2) mice and their wild-type littermates (Cnr2). After echocardiography and Millar left heart catheter hemodynamic evaluation hearts were processed for histological, cellular and molecular analyses.

Results: The endocannabinoid system showed significantly higher anandamide production and CB2 receptor expression in Cnr2 mice. Histology showed non-confluent, interstitial fibrosis with rare small areas of cardiomyocyte loss in Cnr2 mice. In contrast, extensive cardiomyocyte loss and confluent scar formation were found in Cnr2 mice accompanied by significantly increased apoptosis and left ventricular dysfunction when compared with Cnr2 mice. The underlying cardiac maladaptation in Cnr2 mice was associated with significantly reduced expression of myosin heavy chain isoform beta and less production of heme oxygenase-1. Cnr2 hearts presented after 7 days with stronger proinflammatory response including significantly higher TNF-alpha expression and macrophage density, but lower density of CD4+ and B220+ cells. At the same time, we found increased apoptosis of macrophages and adaptive immune cells. Higher myofibroblast accumulation and imbalance in MMP/TIMP-regulation indicated adverse remodeling in Cnr2 mice.

Conclusions: Our study provides mechanistic evidence for the role of the endocannabinoid system in myocardial adaptation to pressure overload in mice. The underlying mechanisms include production of anandamide, adaptation of contractile elements and antioxidative enzymes, and selective modulation of immune cells action and apoptosis in order to prevent the loss of cardiomyocytes.
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http://dx.doi.org/10.1016/j.yjmcc.2019.06.003DOI Listing
August 2019

A structure-function approach identifies L-PGDS as a mediator responsible for glucocorticoid-induced leptin expression in adipocytes.

Biochem Pharmacol 2019 08 24;166:203-211. Epub 2019 May 24.

Institute of Biotechnology and Pharmaceutical Research, National Health Research Institutes, Miaoli 35053, Taiwan. Electronic address:

Leptin is an adipokine predominantly secreted by adipocytes and has many physiological roles, including in energy homeostasis. We identified that AM630, a cannabinoid receptor 2 (CB2) antagonist, down-regulated leptin expression in mature adipocytes differentiated from either stromal vascular fractions isolated from inguinal fat pads of C57BL/6J mice or 3T3-L1 preadipocytes. However, the leptin-suppressive effects of AM630 preserved in CB2-deficient adipocytes indicated the off-target activity of AM630 in leptin expression. Pharmacological and genetic studies, cheminformatics, and docking simulation were applied to identify the potential protein target of AM630 that modulates leptin expression in differentiated primary preadipocytes. Screening of the reported off-targets of AM630 identified a synthetic cannabinoid WIN55212-2 exerting the same function. Target deconvolution and docking simulation suggested that AM630 and WIN55212-2 were both inhibitors of lipocalin-type prostaglandin D2 synthase (L-PGDS). Further studies showed that L-PGDS positively regulates leptin expression. Although glucocorticoid and aldosterone were previously reported to induce expression of both L-PGDS and leptin, our data demonstrated that L-PGDS mediates only glucocorticoid-induced leptin expression in differentiated primary preadipocytes. No effect was observed after aldosterone treatment. This newly discovered glucocorticoid - L-PGDS - leptin pathway may provide insights into current clinical use of glucocorticoid and management of their undesired effects such as obesity.
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http://dx.doi.org/10.1016/j.bcp.2019.05.022DOI Listing
August 2019

Correlation between the solid state of lipid coating and release profile of API from hot melt coated microcapsules.

Int J Pharm 2019 Jun 14;565:569-578. Epub 2019 May 14.

Institute of Pharmaceutical Sciences, Department of Pharmaceutical Technology and Biopharmacy, University of Graz, Graz, Austria.

Solvent-free hot melt coating (HMC) provides a safer and more economic process compared to the conventional solvent coating techniques. However, drug release instability and the lack of fundamental understanding on it are limiting factors for application of HMC for industrial productions. In this work, we investigated glyceryl dibehenate, glyceryl monostearate and behenoyl polyoxyl-8 glyceride as HMC materials. The microstructure and solid state alteration of lipids were studied via polarized light microscopy, DSC and powder x-ray diffraction. Microcapsules of N-acetylcysteine particles were provided with these excipients and stored under long term and accelerated conditions for 3 months. The feasibility of selected lipids as HMC excipients was confirmed. The drug release from freshly coated microcapsules was dictated by microstructure, solid state and HLB of lipid coating. Alterations in the release profiles after storage under accelerated conditions were correlated with time-dependent structural alterations of selected lipids. The faster drug release from glyceryl dibehenate and behenoyl polyoxyl-8 glyceride microcapsules was correlated with a low-melting small fraction composed by mixed phases in glyceryl dibehenate and the amorphous region of polyoxyl part in behenoyl polyoxyl-8 glyceride, respectively. The slower drug release from glyceryl dibehenate after storage was explained by the transition of lipid crystals to the β-form with dense crystalline structure. The gained information can be used to design effective tempering strategies for providing stable pharmaceutical products.
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http://dx.doi.org/10.1016/j.ijpharm.2019.05.036DOI Listing
June 2019
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