Modulation of IL-6 Expression by KLF4-Mediated Transactivation and PCAF-Mediated Acetylation in Sublytic C5b-9-Induced Rat Glomerular Mesangial Cells

Interleukin-6 (IL-6) overproduction has been considered to contribute to inflammatory damage of glomerular mesangial cells (GMCs) in human mesangial proliferative glomerulonephritis (MsPGN) and its rat model called Thy-1 nephritis (Thy-1N). However, the regulatory mechanisms of IL-6 expression in GMCs upon sublytic C5b-9 timulation remain poorly understood. We found that Krüppel-like factor 4 (KLF4) bound to the IL-6 promoter (−618 to −126 nt) and activated IL-6 gene transcription. Furthermore, lysine residue 224 of KLF4 was acetylated by p300/CBP-associated factor (PCAF), which was important for KLF4-mediated transactivation. Moreover, lysine residue 5 on histone H2B and lysine residue 9 on histone H3 at the IL-6 promoter were also acetylated by PCAF, which resulted in an increase in IL-6 transcription. Besides, NF-κB activation promoted IL-6 expression by elevating the expression of PCAF. Overall, these findings suggest that sublytic C5b-9-induced the expression of IL-6 involves KLF4-mediated transactivation, PCAF-mediated acetylation of KLF4 and histones, and NF-κB activation in GMCs.

Serum and urine ANGPTL8 expression levels are associated with hyperlipidemia and proteinuria in primary nephrotic syndrome

Background This study aimed to investigate the expression characteristics of ANGPTL8 in patients with primary nephrotic syndrome and its possible correlation with hyperlipidemia and proteinuria. Methods ANGPTL8 levels were determined using an enzyme-linked immunosorbent assay in 133 subjects with PNS and 60 healthy controls. Results Compared with healthy controls, subjects with primary nephrotic syndrome had higher levels of serum and urine ANGPTL8 (P < 0.001). In primary nephrotic syndrome patients, serum ANGPTL8 was positively correlated with cholesterol (r = 0.209, P < 0.05) and triglycerides (r = 0.412, P < 0.001), while there was no correlation with 24 hUTP. Urine ANGPTL8 was positively correlated with high-density lipoprotein cholesterol (r = 0.181, P < 0.05) and was significantly negatively correlated with creatinine (r = − 0.323, P < 0.001), eGFR (r = − 0, P < 0.001) and 24 hUTP (r = − 0.268, P = 0.002). Interestingly, the urine ANGPTL8 concentrations in membranous nephropathy and mesangial proliferative glomerulonephritis pathological types were different. Conclusions Serum and urine ANGPTL8 levels in primary nephrotic syndrome patients were correlated with blood lipid levels and proteinuria, respectively, suggesting that ANGPTL8 may play a role in the development of primary nephrotic syndrome hyperlipidemia and proteinuria.

Serum and Urine ANGPTL8 Expression Levels are Associated with Hyperlipidemia and Proteinuria in Primary Nephrotic Syndrome

Background: This study aimed to investigate the expression characteristics of ANGPTL8 in patients with primary nephrotic syndrome and its possible correlationwith hyperlipidemia and proteinuria.Methods: ANGPTL8 levels were determined using Enzyme‑linked immunosorbentassay in 133 subjects with PNS, and 60 subjects with healthy controls.Results: Subjects with primary nephrotic syndrome had higher levels of serum andurine ANGPTL8 than healthy controls subjects (P < 0.001). In primary nephroticsyndrome patients, serum ANGPTL8 was positively correlated with cholesterol (r =0.209, P < 0.05) and triglycerides (r = 0.412, P < 0.001), while no correlation with24hUTP. Urine ANGPTL8 was positively correlated with high density lipoprotein-cholesterol (r = 0.181, P < 0.05), while urine ANGPTL8 was significantly negativelycorrelated with creatinine (r = -0.323, P<0.001) and 24hUTP (r = -0.268, P = 0.002).Interestingly, urine ANGPTL8 concentrations were different between membranousnephropathy and mesangial proliferative glomerulonephritis pathological types.Conclusions: Serum and urine ANGPTL8 levels in primary nephrotic syndromepatients were correlated with blood lipid levels and proteinuria, respectively, suggestingthat ANGPTL8 may play a role in the development of primary nephrotic syndromehyperlipidemia and proteinuria.

Mesangial Cells and Glomerular Endothelial Cells Crosstalk in Rat Anti-Thy-1 Nephritis through VEGFA/VEGFAR2 and Angpt2/Tie2 pathway

BACKGROUNDMesangial proliferative glomerulonephritis is characterized by the proliferation of mesangial cells (MCs). Endothelial cells (ECs) are affected by signals from MCs, resulting in capillary proliferation, but the specific signaling pathway associated with this activity remains unclear.RESULTSIn this study, the expression of PCNA, RECA-1 and CD34 in the glomeruli increased on the 7th day after anti-Thy-1 nephritis establishment, indicating the occurrence of ECs proliferation. After coculturing MCs and ECs in vitro, we observed that activated MCs could promote ECs proliferation, migration and α-SMA expression. Moreover, activated ECs had the same effects on MCs. RT-qPCR showed that activated MCs could increasingly secrete VEGFA, and Angpt2 expression in VEGFA-activated ECs was enhanced. Considering that Angpt2-mediated inhibition of ECs surface receptor Tie2 phosphorylation causes ECs proliferation, we hypothesized that VEGFA/VEGFR2 and Angpt2/Tie2 signaling is involved in the interaction between MCs and ECs. Our results showed that blocking VEGFA or adding the Angpt2 antagonist Angpt1 to the coculture system decreased the number of EdU-positive cells，Angpt2，p-VEGFR2 and p-MAPK expression, but increased p-Tie2 in ECs. To determine whether Angpt1 could effectively alleviate the pathological changes of anti-Thy-1 nephritis, we performed Vasculotide (Angpt1 mimic peptide) treatment assays in vivo. The results confirmed that the addition of Vasculotide could effectively reduce PCNA, RECA-1 and α-SMA expression and promote p-Tie2.CONCLUSIONIn summary, the study showed that the VEGFA/VEGFR2 and Angpt2/Tie2 signaling pathway mediate interactions between MCs and ECs, providing an important theoretical basis for the treatment of mesangial proliferative glomerulonephritis.