Publications by authors named "Iwona Ksiazek"

11 Publications

  • Page 1 of 1

Farnesoid X Receptor Agonism, Acetyl-Coenzyme A Carboxylase Inhibition, and Back Translation of Clinically Observed Endpoints of Lipogenesis in a Murine NASH Model.

Hepatol Commun 2020 Jan 8;4(1):109-125. Epub 2019 Nov 8.

Disease Area X Novartis Institutes for BioMedical Research Basel Switzerland.

A promising approach for the treatment of nonalcoholic steatohepatitis (NASH) is the inhibition of enhanced hepatic lipogenesis (DNL), which is the synthesis of fatty acids from nonlipid sources. This study assesses three approaches to DNL suppression in a newly developed dietary NASH mouse model: i) dietary intervention (switch from NASH-inducing diet to normal diet); ii) inhibition of acetyl-coenzyme A carboxylase (ACC), the enzyme catalyzing the rate-limiting step in DNL; and iii) activation of farnesoid X receptor (FXR), a major transcriptional regulator of DNL. C57BL/6J mice on a high-fat diet combined with consumption of a fructose-sucrose solution developed several of the liver histologic features seen in human disease, including steatosis, inflammation, and fibrosis, accompanied by elevated fibrosis biomarkers and liver injury enzymes. Obesity and metabolic impairments were associated with increased intestinal permeability and progression to adenoma and hepatocellular carcinoma. All three approaches led to resolution of established NASH with fibrosis in mice; however, some differences were noted, e.g., with respect to the degree of hepatic steatosis attenuation. While ACC inhibition resulted in elevated blood triglycerides and peripheral obesity, FXR activation prevented peripheral obesity in NASH mice. Comparative transcriptome analysis underlined the translatability of the mouse model to human NASH and revealed novel mechanistic insights into differential regulation of lipid, inflammatory, and extracellular matrix pathways by FXR agonism and ACC inhibition. Novel insights are provided on back translation of clinically observed endpoints of DNL inhibition by targeting ACC or FXR, which are promising therapeutic options for the treatment of NASH, in a newly developed diet-induced NASH mouse model.
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http://dx.doi.org/10.1002/hep4.1443DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6939503PMC
January 2020

UTS2B Defines a Novel Enteroendocrine Cell Population and Regulates GLP-1 Secretion Through SSTR5 in Male Mice.

Endocrinology 2019 12;160(12):2849-2860

Novartis Institutes for BioMedical Research, Basel, Switzerland.

The gut-pancreas axis plays a key role in the regulation of glucose homeostasis and may be therapeutically exploited to treat not only type 2 diabetes but also hypoglycemia and hyperinsulinemia. We identify a novel enteroendocrine cell type expressing the peptide hormone urotensin 2B (UTS2B). UTS2B inhibits glucagon-like peptide-1 (GLP-1) secretion in mouse intestinal crypts and organoids, not by signaling through its cognate receptor UTS2R but through the activation of the somatostatin receptor (SSTR) 5. Circulating UTS2B concentrations in mice are physiologically regulated during starvation, further linking this peptide hormone to metabolism. Furthermore, administration of UTS2B to starved mice demonstrates that it is capable of regulating blood glucose and plasma concentrations of GLP-1 and insulin in vivo. Altogether, our results identify a novel cellular source of UTS2B in the gut, which acts in a paracrine manner to regulate GLP-1 secretion through SSTR5. These findings uncover a fine-tuning mechanism mediated by a ligand-receptor pair in the regulation of gut hormone secretion, which can potentially be exploited to correct metabolic unbalance caused by overactivation of the gut-pancreas axis.
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http://dx.doi.org/10.1210/en.2019-00549DOI Listing
December 2019

DPP9 enzymatic activity in hematopoietic cells is dispensable for mouse hematopoiesis.

Immunol Lett 2018 06 27;198:60-65. Epub 2018 Apr 27.

Novartis Institute for Biomedical Research, CH-4056, Basel, Switzerland. Electronic address:

Dipeptidyl peptidase 9 (DPP9) is a ubiquitously expressed intracellular prolyl peptidase implicated in immunoregulation. However, its physiological relevance in the immune system remains largely unknown. We investigated the role of DPP9 enzyme in immune system by characterizing DPP9 knock-in mice expressing a catalytically inactive S729A mutant of DPP9 enzyme (DPP9 mice). DPP9 mice show reduced number of lymphoid and myeloid cells in fetal liver and postnatal blood but their hematopoietic cells are fully functional and able to reconstitute lymphoid and myeloid lineages even in competitive mixed chimeras. These studies demonstrate that inactivation of DPP9 enzymatic activity does not lead to any perturbations in mouse hematopoiesis.
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http://dx.doi.org/10.1016/j.imlet.2018.04.008DOI Listing
June 2018

Response to Letter to the Editor.

Dev Biol 2018 07 15;439(1). Epub 2017 Dec 15.

Novartis Institute for Biomedical Research, CH-4056 Basel, Switzerland. Electronic address:

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http://dx.doi.org/10.1016/j.ydbio.2017.12.010DOI Listing
July 2018

DPP9 enzyme activity controls survival of mouse migratory tongue muscle progenitors and its absence leads to neonatal lethality due to suckling defect.

Dev Biol 2017 11 6;431(2):297-308. Epub 2017 Sep 6.

Novartis Institute for Biomedical Research, CH-4056 Basel, Switzerland. Electronic address:

Dipeptidyl peptidase 9 (DPP9) is an intracellular N-terminal post-proline-cleaving enzyme whose physiological function remains largely unknown. We investigated the role of DPP9 enzyme in vivo by characterizing knock-in mice expressing a catalytically inactive mutant form of DPP9 (S729A; DPP9 mice). We show that DPP9 mice die within 12-18h after birth. The neonatal lethality can be rescued by manual feeding, indicating that a suckling defect is the primary cause of neonatal lethality. The suckling defect results from microglossia, and is characterized by abnormal formation of intrinsic muscles at the distal tongue. In DPP9 mice, the number of occipital somite-derived migratory muscle progenitors, forming distal tongue intrinsic muscles, is reduced due to increased apoptosis. In contrast, intrinsic muscles of the proximal tongue and extrinsic tongue muscles, which derive from head mesoderm, develop normally in DPP9 mice. Thus, lack of DPP9 activity in mice leads to impaired tongue development, suckling defect and subsequent neonatal lethality due to impaired survival of a specific subset of migratory tongue muscle progenitors.
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http://dx.doi.org/10.1016/j.ydbio.2017.09.001DOI Listing
November 2017

Effects of the fibroblast activation protein inhibitor, PT100, in a murine model of pulmonary fibrosis.

Eur J Pharmacol 2017 Aug 12;809:64-72. Epub 2017 May 12.

Musculoskeletal Diseases Department, Novartis Institutes for BioMedical Research, CH-4056 Basel, Switzerland. Electronic address:

Bleomycin (BLM) induced lung injury is detectable in C57BL/6 mice using magnetic resonance imaging (MRI). We investigated the effects of the fibroblast activation protein (FAP) inhibitor, PT100, in this model. BLM (0.5mg/kg/day) was administered on days -7, -6, -5, -2, -1, 0 in the nostrils of male mice. PT100 (40µg/mouse) or vehicle (0.9%NaCl) was dosed per os twice daily from day 1-14. MRI was performed before BLM and at days 0, 7 and 14. After the last MRI acquisition, animals were euthanised and the lungs harvested for histological and quantitative real-time polymerase chain reaction (qRT-PCR) analyses. As evidenced longitudinally by MRI, the BLM-elicited lesions in the lungs of vehicle-treated mice progressed over time. In contrast, responses elicited by BLM did not progress in animals receiving PT100. Histology demonstrated significant less fibrosis in PT100- than in vehicle-treated, BLM-challenged mice. Significant correlation (R=0.91, P<0.001, N=24) was found between the volumes of BLM-induced lesions detected in vivo by MRI and the collagen content determined histologically (picrosirius staining). FAP was overexpressed in the lungs of BLM-challenged mice. Upon PT100 treatment, FAP expression was reduced. Significant differences in the MMP-12, MIP-1α, and MCP-3 mRNA expression levels in the lungs of PT100- compared to vehicle-treated mice were also revealed by qRT-PCR. The IBA-1 level determined histologically was higher in the lungs of PT100- compared to vehicle-treated mice. Taken together, these observations suggest that treatment with PT100 in this murine model of pulmonary fibrosis had an anti-fibro-proliferative effect and increased macrophage activation.
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http://dx.doi.org/10.1016/j.ejphar.2017.05.022DOI Listing
August 2017

Progression of Alport Kidney Disease in Col4a3 Knock Out Mice Is Independent of Sex or Macrophage Depletion by Clodronate Treatment.

PLoS One 2015 10;10(11):e0141231. Epub 2015 Nov 10.

Developmental and Molecular Pathways, Novartis Institute for Biomedical Research, Basel, Switzerland.

Alport syndrome is a genetic disease of collagen IV (α3, 4, 5) resulting in renal failure. This study was designed to investigate sex-phenotype correlations and evaluate the contribution of macrophage infiltration to disease progression using Col4a3 knock out (Col4a3KO) mice, an established genetic model of autosomal recessive Alport syndrome. No sex differences in the evolution of body mass loss, renal pathology, biomarkers of tubular damage KIM-1 and NGAL, or deterioration of kidney function were observed during the life span of Col4a3KO mice. These findings confirm that, similar to human autosomal recessive Alport syndrome, female and male Col4a3KO mice develop renal failure at the same age and with similar severity. The specific contribution of macrophage infiltration to Alport disease, one of the prominent features of the disease in human and Col4a3KO mice, remains unknown. This study shows that depletion of kidney macrophages in Col4a3KO male mice by administration of clodronate liposomes, prior to clinical onset of disease and throughout the study period, does not protect the mice from renal failure and interstitial fibrosis, nor delay disease progression. These results suggest that therapy targeting macrophage recruitment to kidney is unlikely to be effective as treatment of Alport syndrome.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0141231PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4640715PMC
June 2016

A modified RMCE-compatible Rosa26 locus for the expression of transgenes from exogenous promoters.

PLoS One 2012 13;7(1):e30011. Epub 2012 Jan 13.

Novartis Institute for Biomedical Research, Developmental and Molecular Pathways, Novartis Pharma AG, Basel, Switzerland.

Generation of gain-of-function transgenic mice by targeting the Rosa26 locus has been established as an alternative to classical transgenic mice produced by pronuclear microinjection. However, targeting transgenes to the endogenous Rosa26 promoter results in moderate ubiquitous expression and is not suitable for high expression levels. Therefore, we now generated a modified Rosa26 (modRosa26) locus that combines efficient targeted transgenesis using recombinase-mediated cassette exchange (RMCE) by Flipase (Flp-RMCE) or Cre recombinase (Cre-RMCE) with transgene expression from exogenous promoters. We silenced the endogenous Rosa26 promoter and characterized several ubiquitous (pCAG, EF1α and CMV) and tissue-specific (VeCad, αSMA) promoters in the modRosa26 locus in vivo. We demonstrate that the ubiquitous pCAG promoter in the modRosa26 locus now offers high transgene expression. While tissue-specific promoters were all active in their cognate tissues they additionally led to rare ectopic expression. To achieve high expression levels in a tissue-specific manner, we therefore combined Flp-RMCE for rapid ES cell targeting, the pCAG promoter for high transgene levels and Cre/LoxP conditional transgene activation using well-characterized Cre lines. Using this approach we generated a Cre/LoxP-inducible reporter mouse line with high EGFP expression levels that enables cell tracing in live cells. A second reporter line expressing luciferase permits efficient monitoring of Cre activity in live animals. Thus, targeting the modRosa26 locus by RMCE minimizes the effort required to target ES cells and generates a tool for the use exogenous promoters in combination with single-copy transgenes for predictable expression in mice.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0030011PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3258265PMC
May 2012

Neuropathology in mice expressing mouse alpha-synuclein.

PLoS One 2011 26;6(9):e24834. Epub 2011 Sep 26.

Novartis Institutes for BioMedical Research, Novartis Pharma AG, Basel, Switzerland.

α-Synuclein (αSN) in human is tightly linked both neuropathologically and genetically to Parkinson's disease (PD) and related disorders. Disease-causing properties in vivo of the wildtype mouse ortholog (mαSN), which carries a threonine at position 53 like the A53T human mutant version that is genetically linked to PD, were never reported. To this end we generated mouse lines that express mαSN in central neurons at levels reaching up to six-fold compared to endogenous mαSN. Unlike transgenic mice expressing human wildtype or mutant forms of αSN, these mαSN transgenic mice showed pronounced ubiquitin immunopathology in spinal cord and brainstem. Isoelectric separation of mαSN species revealed multiple isoforms including two Ser129-phosphorylated species in the most severely affected brain regions. Neuronal Ser129-phosphorylated αSN occurred in granular and small fibrillar aggregates and pathological staining patterns in neurites occasionally revealed a striking ladder of small alternating segments staining either for Ser129-phosphorylated αSN or ubiquitin but not both. Axonal degeneration in long white matter tracts of the spinal cord, with breakdown of myelin sheaths and degeneration of neuromuscular junctions with loss of integrity of the presynaptic neurofilament network in mαSN transgenic mice, was similar to what we have reported for mice expressing human αSN wildtype or mutant forms. In hippocampal neurons, the mαSN protein accumulated and was phosphorylated but these neurons showed no ubiquitin immunopathology. In contrast to the early-onset motor abnormalities and muscle weakness observed in mice expressing human αSN, mαSN transgenic mice displayed only end-stage phenotypic alterations that manifested alongside with neuropathology. Altogether these findings show that increased levels of wildtype mαSN does not induce early-onset behavior changes, but drives end-stage pathophysiological changes in murine neurons that are strikingly similar to those evoked by expression of human wildtype or mutant forms.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0024834PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3180287PMC
March 2012

Synapse loss in cortex of agrin-deficient mice after genetic rescue of perinatal death.

J Neurosci 2007 Jul;27(27):7183-95

Biozentrum, University of Basel, CH-4056 Basel, Switzerland.

Agrin-deficient mice die at birth because of aberrant development of the neuromuscular junctions. Here, we examined the role of agrin at brain synapses. We show that agrin is associated with excitatory but not inhibitory synapses in the cerebral cortex. Most importantly, we examined the brains of agrin-deficient mice whose perinatal death was prevented by the selective expression of agrin in motor neurons. We find that the number of presynaptic and postsynaptic specializations is strongly reduced in the cortex of 5- to 7-week-old mice. Consistent with a reduction in the number of synapses, the frequency of miniature postsynaptic currents was greatly decreased. In accordance with the synaptic localization of agrin to excitatory synapses, changes in the frequency were only detected for excitatory but not inhibitory synapses. Moreover, we find that the muscle-specific receptor tyrosine kinase MuSK, which is known to be an essential component of agrin-induced signaling at the neuromuscular junction, is also localized to a subset of excitatory synapses. Finally, some components of the mitogen-activated protein (MAP) kinase pathway, which has been shown to be activated by agrin in cultured neurons, are deregulated in agrin-deficient mice. In summary, our results provide strong evidence that agrin plays an important role in the formation and/or the maintenance of excitatory synapses in the brain, and we provide evidence that this function involves MAP kinase signaling.
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http://dx.doi.org/10.1523/JNEUROSCI.1609-07.2007DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6794585PMC
July 2007

Agrin is highly expressed by chondrocytes and is required for normal growth.

Histochem Cell Biol 2007 Apr 21;127(4):363-74. Epub 2006 Dec 21.

Department of Orthopedics, Division for Biochemistry of Joint and Connective Tissue Diseases, University of Ulm, RKU, Oberer Eselsberg 45, 89081, Ulm, Germany.

Agrin is a heparan sulfate proteoglycan that is best known for its crucial involvement in the organization and maintenance of postsynaptic structures at the neuromuscular junction. Consistent with this role, mice deficient of agrin die at birth due to respiratory failure. Here we examined the early postnatal development of agrin-deficient mice in which perinatal death was prevented by transgenic expression of neural agrin in motor neurons. Such transgenic, agrin-deficient mice were born at Mendelian ratio but exhibited severe postnatal growth retardation. Growth plate morpholgy was markedly altered in these mice, with changes being most prominent in the hypertrophic zone. Compression of this zone was not caused by reduced viability of hypertrophic chondrocytes, as no differences in the apoptosis rates could be observed. Furthermore, deposition of the major cartilage matrix components collagen type II and aggrecan was slightly reduced in these mice. Consistent with a role for agrin in skeletal development, we show for the first time that agrin is highly expressed by chondrocytes and localizes to the growth plate in wild-type mice. Our data show that agrin is expressed in cartilage and that it plays a critical role in normal skeletal growth.
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http://dx.doi.org/10.1007/s00418-006-0258-2DOI Listing
April 2007