Boima, V. | Search bioRxiv

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↗

bioRxiv2022

Urine-based detection of biomarkers indicative of chronic kidney disease in a patient cohort from Ghana

Chronic kidney disease (CKD) is a global health burden with a continuously increasing prevalence associated with an increasing incidence of diabetes and hypertension in aging populations. The CKD definition of a more than three months lasting low glomerular filtration rate (GFR) or other renal impairments including proteinuria implies that multiple factors may contribute to the disease. While there are indications of ethnic differences it is hard to disentangle these from confounding social factors. Usually, CKD is detected in later stages of the disease when irreversible renal damage has already occurred, thus suggesting a need for early non-invasive diagnostic markers. In this study, we explored the urine secretome of a CKD patient cohort from Ghana employing a kidney-injury and a more general cytokine assay. We identified panels of kidney-specific cytokine markers which were also gender-specific and a panel of gender-independent cytokine markers. The gender-specific markers are IL10 and MME for male and CLU, RETN, AGER, EGFR and VEGFA for female. The gender-independent cytokine markers were APOA1, ANGPT2, C5, CFD, GH1, ICAM1, IGFBP2, IL8, KLK4, MMP9 and SPP1 (up-regulated) and FLT3LG, CSF1, PDGFA, RETN and VEGFA (down-regulated). APOA1 - the major component of HDL particles - was up-regulated in Ghanaian CKD patients and its co-occurrence with APOL1 in a subpopulation of HDL particles may point to specific CKD-predisposing APOL1 haplotypes in patients of African descent - this however needs further investigation. The identified panels may lay down the foundation for CKD-biomarker assays to be confirmed in further studies with a larger cohort of patients.

molecular biology↗