Biology subjects

Loerch, C.

Publications and source records attributed to Loerch, C..

3 recordsLinked to original sources

bioRxiv2026

SAHA increases chaperone expression and reduces Z-alpha-1-antitrypsin polymers in a patient specific iPSC-based liver model for alpha-1-antitrypsin deficiency

The most severe phenotype of alpha-1-antitrypsin deficiency (AATD) is caused by the Z-mutation within the SERPINA1 gene. The Glu342Lys substitution causes misfolding and polymerisation of the alpha-1-antitrypsin (AAT) protein, its accumulation in the ER and increases the susceptibility of hepatocytes towards ER-stress. Here, we present an induced pluripotent stem cell (iPSC)-based hepatic model to study AATD. We demonstrate that iPSCs from AATD patients differentiate equally well to hepatocyte-like cells (HLCs) as control iPSCs. We detected ZAAT polymers in patient-derived HLCs which could be reduced by SAHA or CBZ treatment. Transcriptome analyses revealed major differences in metabolism and signalling between control and AATD HLCs and indicated increased stress levels affecting intracellular organelles. Importantly, the transcriptomes of control and patient-derived cells separated into distinct clusters with respect to the expression of Heat-shock protein (HSP) encoding genes. SAHA treatment increased expression of various HSPs which might contribute towards reduced ZAAT polymers.

cell biology↗

bioRxiv2025

Urinary proteins from Sickle Cell patients induce inflammation and kidney injury via the TGFβ-p53 axis in a podocyte cell culture model.

BackgroundSickle cell disease (SCD) is an inherited blood disorder affecting the oxygen-carrying hemoglobin in red blood cells making them deform into a sickle shape. Hemolysis and vaso-occlusion associated with this process can lead to complications in many organs and frequently to renal complications. Numerous factors are considered to contribute towards the development of proteinuria (PU) in SCD including hyperfiltration, ischemia, oxidative stress and decreased nitric oxide (NO) bioavailability but the detailed pathophysiology still needs further elucidation. MethodsEmploying arrays, we investigated cytokines and kidney injury-associated markers in the urine of a cohort of SCD patients from Ghana carrying the SS and SC genotypes which were further sub-divided into groups with proteinuria (SCD_PU) and without proteinuria (SCD). ResultsWe identified up-and down-regulated proteins when comparing SCD with and without proteinuria. Amongst these is the well-established kidney injury marker-Clusterin which was up-regulated and could be validated in an ELISA-based assay. Refining the study to the SS and SC genotypes, we identified (and confirmed by ELISA) another established kidney injury marker-NGAL, as up-regulated in both genotypes and SCD with and without proteinuria. Metascape-based analysis of biological processes revealed "Cellular component disassembly" associated with proteins expressed in SCD but not regulated between PU and no PU and "leukocyte chemotaxis" down-regulated in SCD_PU vs. SCD. Interestingly, "Integrin-cell-surface interactions" was associated with proteins up-regulated between SCD_PU vs. SCD which is consistent with endothelial hyperplasia in the setting of glomerular hyperfiltration. To investigate the effect secreted urine proteins have on human podocytes in vitro, immortalized podocytes supplemented with SCD_PU urine showed elevated p53 levels in both immunofluorescence staining and RT-PCR compared to SCD. Additionally, RT-PCR revealed elevated levels of VEGF, NGAL and the pro-inflammatory proteins-TGF{beta}, IL6, IL8 and TNF. ConclusionWe hypothesize that the increased number of endothelial cells in hyperplasia and hyperfiltration leads to more Integrin-mediated links to podocyte foot processes at the glomerular basement membrane and to glomerular fibrosis. Severe inflammation and kidney injury in SCD_PU patients is induced by the TGF{beta}-p53 axis.

molecular biology↗

bioRxiv2024

Inhibiting DPP4 activity protects hiPSC-derived steatotic HLCs by supporting fatty acid and purine metabolism and dampening inflammation

BackgroundMetabolic dysfunction-associated steatotic liver disease (MAFLD) has a high prevalence and high co-morbidity for other diseases. Due to the complexity of this multifactorial disease, therapy options are still rather limited. We employed an in vitro pluripotent stem cell-based model to decipher potential disease-associated molecular pathways and to study the mode of action of prospective drugs. Dipeptidyl peptidase 4 (DPP4) or Cluster of differentiation 26 (CD26) is involved in inflammation, infections, immune disorders, type 2 diabetes, kidney disease and cancer. MethodsWe induced the steatosis phenotype in human induced pluripotent stem cell (iPSC) derived hepatocyte-like cells (HLCs) by oleic acid (OA)-feeding and confirmed regulation of clinically relevant pathways by NGS-based global transcriptomic analyses. Analysis of the secretome of steatotic HLCs revealed DPP4 as a potential key mediator of the disease. To further elucidate its role in the development of MAFLD, we inhibited DPP4 activity with Vildagliptin (VILDA) and analyzed the global transcriptome changes as well as specific gene and protein expression of steatosis-associated genes with and without DPP4 inhibition. ResultsMAFLD-associated pathways such as PPAR- and TNF signaling were differentially regulated in hiPSC-derived steatotic HLCs. We found increased hepatic DPP4 activity and secretion upon OA. Gene expression of fatty acid and purine metabolism and inflammation-associated pathways were regulated upon DPP4 inhibition. ConclusionsOur HLC-model confirmed association of DPP4 with metabolism and inflammation which foster the development of MAFLD. Inhibiting DPP4 with VILDA partially relieved the steatotic phenotype on a global transcriptomic level. Impact and implicationsGiven the difficulties of identifying suitable anti-MAFLD drugs, novel model systems are urgently needed. Our in vitro HLC-model reproduced DPP4-dependent aspects of the disease and responded positively to Vildagliptin treatment. Further elucidation of the role of DPP4 in the etiology of MAFLD and other diseases is warranted.

cell biology↗