Kidney fibrosis is a hallmark of chronic kidney diseases. Evidence shows that genetic variability and complement component 3 (C3) might influence tubulointerstitial fibrosis. Still, the role of renal C3 production in the epithelial-to-mesenchymal transition (EMT) and genetically determined fibrosis progression remains undiscovered. The kidneys of fibrosis-resistant C57Bl/6J (B6) and fibrosis-prone CBA/J (CBA) and BALB/cJ (BalbC) mice (n = 4–8/group) were subjected to unilateral ureteral obstruction (UUO) and analyzed after 1, 3, and 7 days, along with human focal glomerular sclerotic (FSGS) and healthy kidneys. Mouse primary tubular epithelial cells (PTECs) were investigated after 24 h of treatment with transforming growth factor β (TGFβ) or complement anaphylatoxin 3a (C3a) agonist (n = 4/group). UUO resulted in delayed kidney injury in fibrosis-resistant B6 mice, but very early renal C3 messenger RNA (mRNA) induction in fibrosis-prone CBA and BalbC mice, along with collagen I (Col1a1) and collagen III (Col3a1). CBA depicted the fastest fibrosis progression with the highest C3, lipocalin-2 (Lcn2), Tgfb1, and chemokine (C-C motif) ligand 2 (Ccl2) expression. Human FSGS kidneys depicted C3 mRNA over-expression and strong tubular C3 immunostaining. In PTECs, C3a agonist treatment induced pro-fibrotic early growth response protein 1 (EGR1) expression and the EMT, independent of TGFβ signaling. We conclude that de novo renal tubular C3 synthesis is associated with the genetically determined kidney fibrosis progression rate in mice and the pathogenesis of FSGS in humans. This tubular C3 overproduction can, through local pro-fibrotic effects, influence the progression of chronic kidney disease.

Abstract Background and Aims Renal complement expression has been observed in both experimental and human kidney diseases. We have previously reported massive tubular C3 expression in fibrotic TGF-beta1 transgenic mice (Nephrol Dial Transpl 2015, 30; S3:FP301). Still, little is known whether this intra-renal complement is only an inflammatory marker of renal fibrosis or also exerts direct pro-fibrotic effects in the pathogenesis. In the present study we aimed to investigate the effect of C3a receptor activation in murine primary tubular epithelial cells. Method Primary tubular epithelial cells (TEC) were isolated from kidneys of four weeks-old male C57Bl6 mouse. The cells were grown in DMEM/12 medium supplemented with 2% FBS and recombinant 5 ng/ml EGF, and characterized for epithelial and mesenchymal markers. Verified TEC between P4 and P10 passages were used for the experiments. TEC cells were seeded on 6-well plates and treated for 24 hours with PBS (CTL, n=3), 100 nM C3a receptor agonist peptide (C3aR, n=3) or 10 ng/ml recombinant TGF-beta1 (TGFb, n=3). Then, mRNA and protein expressions were assessed and evaluated using Kruskal-Wallis test (p<0.05). Results TGF-beta induced a 2-fold Col1a1 and 1,6-fold Tgfb1 mRNA expression, accompanied by 4-fold Egr2 but did not affect Ccl2 or C3 mRNA expression. In contrast, C3aR group depicted 1,6-fold C3 and 1,8-fold Ccl2 mRNA expression, an only 1,6-fold Egr2 but a 2-fold Col1a1 and 1,5-fold Tgfb1 mRNA expression. Despite the similar Tgfb1 mRNA overexpression in TGFb and C3aR groups, marked TGFB1 protein overexpression (15-fold) was only observed in TGF-beta treated cells but not in the C3aR group. Conclusion Our study data indicate that renal complement C3 production can exert autocrine / paracrine direct pro-fibrotic effects on tubular epithelial cells unrelated to TGF-beta protein levels. Therefore, local C3 overexpression might play a significant pathogenetic role in kidney fibrosis.

Kidney transplantation is the preferred treatment for patients with end-stage kidney disease. Maintaining organ viability between donation and transplantation, as well as minimizing ischemic injury, are critically important for long-term graft function and survival. Moreover, the increasing shortage of transplantable organs is a considerable problem; thus, optimizing the condition of grafts is a pivotal task. Here, rodent models of kidney transplantation and cold storage were used to demonstrate that supplementation of a preservation solution with Sigma-1 receptor (S1R) agonist fluvoxamine (FLU) reduces cold and warm ischemic injury. Post-transplant kidney function was improved, histological injury was mitigated, and mRNA expression of two tubular injury markers-kidney injury molecule-1 and neutrophil gelatinase-associated lipocalin-was robustly reduced. In addition, renal inflammation was diminished, as shown by reduced leukocyte infiltration and pro-inflammatory cytokine expression. In the cold ischemia model, FLU ameliorated structural injury profoundly after 2 h as well as 24 h. The reduced number of TUNEL-positive and Caspase 3-positive cells suggests the anti-apoptotic effect of FLU. None of these beneficial effects of FLU were observed in S1R(-/-) mice. Of note, organ damage in FLU-treated kidneys after 24 h of cold storage was similar to just 2 h without FLU. These results indicate that S1R agonists can prolong storage time and have great potential in improving organ preservation and in alleviating the problem of organ shortages.

The primordial germ cells (PGCs) are the precursors for both the oocytes and spermatogonia. Recently, a novel culture system was established for chicken PGCs, isolated from embryonic blood. The possibility of PGC long-term cultivation issues a new advance in germ cell preservation, biotechnology, and cell biology. We investigated the consequence of gga-miR-302b-5P (5P), gga-miR-302b-3P (3P) and dual inhibition (5P/3P) in two male and two female chicken PGC lines. In treated and control cell cultures, the cell number was calculated every four hours for three days by the XLS Imaging system. Comparing the cell number of control and treated lines on the first day, we found that male lines had a higher proliferation rate independently from the treatments. Compared to the untreated ones, the proliferation rate and the number of apoptotic cells were considerably reduced at gga-miR-302b-5P inhibition in all PGC lines on the third day of the cultivation. The control PGC lines showed a significantly higher proliferation rate than 3P inhibited lines on Day 3 in all PGC lines. Dual inhibition of gga-miR-302b mature miRNAs caused a slight reduction in proliferation rate, but the number of apoptotic cells increased dramatically. The information gathered by examining the factors affecting cell proliferation of PGCs can lead to new data in stem cell biology.

Abstract BACKGROUND AND AIMS The balance of matrix metalloproteinases (MMPs) and their tissue inhibitors (TIMP) is disrupted in diabetic nephropathy and renal TIMP-1 overexpression is observed in both animal experimental models and human biopsies. The STAT3 transcription factor participates in several inflammatory pathways; however, its interaction with TIMP-1 in diabetes remains unknown. We aimed to investigate the progression of nephropathy and its relationship to renal STAT3 activation in type-1 diabetic TIMP-1 knock-out (KO) mice. METHOD Diabetes was induced in 6-week-old male TIMP-1 KO (DM-KO, n = 8) and C57Bl6 wild type (DM, n = 5) mice by intraperitoneal streptozotocin injections (50 mg/kg/day for 5 days). Control mice (CTL, n = 6) received citrate buffer injections. Eight weeks after onset of diabetes blood and urine chemistries, renal histology, renal mRNA and protein expression were assessed. Statistical significance was evaluated using Kruskal–Wallis test and Tukey post-hoc analysis. RESULTS Despite similar hyperglycemia, DM-KO mice developed significantly less proteinuria (P <0.01) and histologically milder glomerulosclerosis and tubular damage as compared with wild type DM mice. Kidneys of DM mice depicted 4-fold STAT3 phosphorylation, but DM-KO kidneys had similar values as CTL nondiabetic controls. DM kidneys also showed 20-fold CCL2, 10-fold C3 and 2.5-fold C4 overexpression, which in DM-KO kidneys remained all near control (CTL) levels. CONCLUSION Based on our results, we conclude that TIMP-1 influences the progression of diabetic kidney disease in mice not solely through the inhibition of MMP-s, but also by influencing the extent of renal inflammation via STAT3 phosphorylation. Therefore, TIMP-1 might emerge as promising future therapeutic target. FUNDING Hungarian Academy of Sciences BO/00 304/20/5, ÚNKP-21–5-SE-1.

COVID-19 is a disease-causing current pandemic. It prevails in patients with pre-existing conditions such as diabetes and hypertension. Renin-angiotensin system was identified as a center of COVID-19 pathophysiology. There is a current controversy concerning the usage of ACE inhibitors and AR blockers in patients with COVID-19. Multiple clinical trials are on the way to determine the effect of RAS blockers in patients with COVID-19. ACE2 receptor is thought to be the point of entry utilized by a coronavirus. However, other factors have been identified which potentially facilitate SARS-CoV-2 entry into the cell. ADAM17 could facilitate viral entry in hyperglycemic and diabetic patients. Insulin is an ADAM17 inhibitor. Heme oxygenase (HO)-1 level is reduced in diabetic patients, contributing to the worst outcome for patients with poor glycemic control. The combined therapy of glycemic control and antioxidant response to oxidative stress could be explored in patients with COVID-19.