The possibility of differentiating bone marrow-derived mesenchymal stem cells (BMSCs) into tubular epithelial-like cells is explored in vitro. Purified BMSCs from Sprague-Dawley rats were obtained by density gradient centrifugation. Third generation BMSCs were divided into six groups and were cultured under different conditions. The expression of alkaline phosphatase and cytokeratin (CK)-18 protein was detected through staining and immunocytochemistry, respectively, and the expression of E-cadherin proteins was recorded through immunofluorescence. Some cells in ischemia/reperfusion (I/R), all-trans retinoic acid (ATRA), epidermal growth factor (EGF) and bone morphogenetic protein-7 (BMP-7) groups turned positive, whereas the positive cells in the combined group significantly increased compared with the other groups. Compared with the control group, the positive expression rates of CK-18 in the I/R, ATRA, EGF, BMP-7 and the combined group were 11·50% ± 3·84%, 27·40% ± 2·70%, 29·60% ± 4·51%, 26·80% ± 5·00% and 44·00% ± 3·16%, respectively, and CK-18 mRNA expression in the combined group was obviously higher than that in the other groups (P < 0·01). Immunofluorescence detection showed that E-cadherin expression was not detectable in the control group, whereas the positive expression rates of E-cadherin in the I/R, ATRA, EGF, BMP-7 and the combined group were 6·75% ± 2·13%, 16·40% ± 2·69%, 18·25% ± 3·50%, 16·06% ± 2·00% and 30·26% ± 5·16%, respectively. The addition of ATRA, EGF and BMP-7 induces BMSCs differentiation into tubular epithelial-like cells in stimulated acute renal failure microenvironment in vitro.

Complement C3 plays a prominent role in inflammatory processes, and its increase exacerbates ischemia reperfusion injury (IRI)-induced acute kidney injury (AKI). Infiltrated neutrophils can be stimulated to form neutrophil extracellular traps (NETs), leading to renal injury. However, the relationship between the increase of C3 and the release of NETs in AKI was not clear. Here we found that IRI in the mouse kidney leads to increased neutrophils infiltration and NET formation. Furthermore, neutrophils depletion by anti-Ly6G IgG (1A8) did not reduce C3 activation but reduced kidney injury and inflammation, indicating a link between neutrophils infiltration and renal tissue damage. Pretreatment with 1A8 suppressed ischemia-induced NET formation, proving that extracellular traps (ETs) in renal tissue were mainly derived from neutrophils. Renal ischemia injury also leads to increased expression of C3. Moreover, C3 KO mice (C3 KO) with IRI exhibited attenuated kidney damage and decreased neutrophils and NETs. In vitro, C3a primed neutrophils to form NETs, reflected by amorphous extracellular DNA structures that colocalized with CitH3 and MPO. These data reveal that C3 deficiency can ameliorate AKI by reducing the infiltration of neutrophils and the formation of NETs. Targeting C3 activation may be a new therapeutic strategy for alleviating the necroinflammation of NETs in AKI.

Injured renal tubular epithelial cells (RTECs) have been recently thought to directly contribute to the accumulation of myofibroblasts in renal tubulointerstitial fibrosis through a process of epithelial to mesenchymal transition (EMT). However, the factors inducing RTECs to undergo EMT and the underlying mechanisms need to be further elucidated. This study aimed to determine the EMT-inducing activity of proinflammatory cytokine TNF-α and the role for complement 3 (C3) in this activity in an in vitro model of human RTECs (HK-2 cells). Wild type HK-2 cells were treated with TNF-α, IFN-γ or C3a; C3 siRNA- or control siRNA-carrying HK-2 cells were treated with TNF-α. Changes in the cell morphology and phenotype were assessed by microscopy, RT-PCR, western blotting, and immunostaining. TNF-α effectively induced HK-2 cells to express C3 and to transform into morphologically myofibroblast-like cells that lost E-cadherin (a classical epithelial cell marker) expression but acquired alpha-smooth muscle actin (α-SMA, a classical myofibroblast differentiation marker) expression. C3 siRNA robustly attenuated all the morphologic and phenotypic changes induced by TNF-α but the control siRNA showed no effect. Our preliminary observations suggest that TNF-α may induce EMT in RTECs through inducing C3 expression.

In human HN, inflammation involving complement C3 activation and macrophage infiltration as well as interactions between them, may play important roles in the pathogenesis and progression of interstitial fibrosis and kidney damage.
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ObjectiveTo investigate the prevalence of obesity in young adults and to analyze the influencing factors on renal functions and proteinuria in this population.MethodsThis study comprised civil servants between 20 and 39 years old, who received physical examinations at the First Affiliated Hospital of Fujian Medical University. The subjects were categorized into four groups based on age (20–24, 25–29, 30–34 and 35–39 years) and the number of risk factors they had (hypertension, dyslipidemia, hyperglycemia and hyperuricemia). The relationships between obesity and the prevalence of proteinuria, between obesity and risk factors and between estimated glomerular filtration rate (eGFR) and proteinuria were analyzed.ResultsAmong the 2293 young civil servants, in men the prevalence of obesity was 33.3 % and proteinuria was 2.5 %. However in women the prevalence of obesity and proteinuria was 7.5 % and 1.7 %, respectively. The levels of blood pressure, serum uric acid (UA), cholesterol (TC), triglyceride (TG), fasting glucose (FBG) and low-density lipoprotein cholesterol (LDL-C) were lower and the level of serum high-density lipoprotein cholesterol (HDL-C) was higher in nonobese groups compared with obese groups. There were no significant differences in eGFR between the two groups. The eGFR in male subjects was associated with age, UA, body mass index (BMI), FBG, TC, TG, LDL and HDL, and in female subjects associated with UA, age, BMI, diastolic blood pressure, FBG and LDL. BMI in both males and females increased with the higher number of risk factors. Multiple regression analysis revealed that hypertension, dyslipidemia, hyperglycemia and hyperuricemia were independently associated with obesity. eGFR decreased with a higher number of risk factors. Obesity, blood pressure, dyslipidemia, hyperglycemia and hyperuricemia were independently associated with proteinuria.ConclusionObesity can pose an independent risk factor for proteinuria in young adults. Hypertension, dyslipidemia, hyperglycemia and hyperuricemia were independently associated with obesity. eGFR decreased with a higher number of risk factors.