Background: Enhanced inflammation and reduced Klotho are common features in chronic kidney disease (CKD). Inflammation induces DNA hypermethylation. This study assessed the performance of inflammatory marker C-C motif chemokine 5 (CCL5) in epigenetic regulation of Klotho expression.Methods: Fifty CKD patients and 25 matched controls were enrolled, and serum CCL5 level, sKlotho level, and DNA methylation were evaluated in these subjects. A renal interstitial fibrosis (RIF) model with CKD was induced in mice via unilateral ureteral obstruction (UUO) in vivo and human proximal tubular epithelial (HK-2) cells treated with CCL5 in vitro. 5-aza-2′-deoxycytidine (5-Aza), a DNA methyltransferase inhibitor was given to UUO mice. Hematoxylin and eosin (HE) and Masson trichrome staining were adopted to evaluate renal pathological changes. Methylation-specific PCR was performed to assess DNA methylation of Klotho promoter in the peripheral blood leucocytes (PBLs) from CKD patients and obstructive kidney from UUO mice. CCL5, Klotho, and DNA methyltransferases (DNMTs) were determined by ELISAs, immunofluorescence, or western blotting. HK-2 cells were exposed to CCL5 with or without 5-Aza and stattic, a p-signal transducer and activator of transcription 3 (STAT3) inhibitor, and expressions of p-STAT3, DNMT1, and Klotho were determined by western blotting.Results: CCL5 upregulation concomitant with Klotho downregulation in serum and global DNA methylation in PBLs were observed in CKD samples. UUO contributed to severe renal interstitial fibrosis and enhanced expressions of fibrotic markers. Moreover, UUO increased the CCL5 level, induced Klotho promoter methylation, suppressed Klotho level, activated p-STAT3 signaling, and upregulated DNMT1 level. A similar observation was made in HK-2 cells treated with CCL5. More importantly, 5-Aza inhibited UUO-induced Klotho hypermethylation, reversed Klotho, downregulated p-STAT3 expressions, and ameliorated RIF in vivo. The consistent findings in vitro were also obtained in HK-2 cells exposed to 5-Aza and stattic.Conclusion: The CCL5/p-STAT3/DNMT1 axis is implicated in epigenetic regulation of Klotho expression in CKD. This study provides novel therapeutic possibilities for reversal of Klotho suppression by CKD.

The pathogenesis of membranous nephropathy (MN) involves podocyte injury that is attributed to inflammatory responses induced by local immune deposits. Astragaloside IV (AS-IV) is known for its robust anti-inflammatory properties. Here, we investigated the effects of AS-IV on passive Heymann nephritis (PHN) rats and TNF-α-induced podocytes to determine the underlying molecular mechanisms of MN. Serum biochemical parameters, 24-h urine protein excretion and renal histopathology were evaluated in PHN and control rats. The expression of tumor necrosis factor receptor associated factor 6 (TRAF6), the phosphorylation of nuclear factor kappa B (p-NF-κB), the expression of associated proinflammatory cytokines (TNF-α, IL-6 and IL-1β) and the ubiquitination of TRAF6 were measured in PHN rats and TNF-α-induced podocytes. We detected a marked increase in mRNA expression of TNF-α, IL-6 and IL-1β and in the protein abundance of p-NF-κB and TRAF6 within the renal tissues of PHN rats and TNF-α-induced podocytes. Conversely, there was a reduction in the K48-linked ubiquitination of TRAF6. Additionally, AS-IV was effective in ameliorating serum creatinine, proteinuria, and renal histopathology in PHN rats. This effect was concomitant with the suppression of NF-κB pathway activation and decreased expression of TNF-α, IL-6, IL-1β and TRAF6. AS-IV decreased TRAF6 levels by promoting K48-linked ubiquitin conjugation to TRAF6, which triggered ubiquitin-mediated degradation. In summary, AS-IV averted renal impairment in PHN rats and TNF-α-induced podocytes, likely by modulating the inflammatory response through the TRAF6/NF-κB axis. Targeting TRAF6 holds therapeutic promise for managing MN.

Background: This study aimed to investigate the protective effect and mechanism of lentinan (LNT) on acute kidney injury (AKI) in septic rats. Methods: A total 72 male SD rats were randomly divided into 6 groups with 12 rats in each group. Except for the sham group, all groups, including the burn sepsis group (BS group), the positive drug control group (dexamethasone, 5 mg/kg, PC group), the LNT low-concentration group (LNT-L group) (50 mg/kg), the LNT medium-concentration group (LNT-M group) (100 mg/kg), and the LNT high-concentration group (LNT-H group) (200 mg/kg), were intraperitoneally injected with the same amount of normal saline 30 min before injury. The levels of serum interleukin (IL)-4, IL-6, IL-10, and tumor necrosis factor alpha (TNF-α); the indexes of blood urea nitrogen (BUN) and creatinine (Cr); and the protein expression levels of inducible nitric oxide synthase (iNOS), intercellular adhesion molecule 1 (ICAM-1), and nuclear factor-κB (NF-κB) in renal tissue were detected 24 hours after the model was established. Results: Compared with the sham group, the BUN and Cr of the other groups were significantly higher, while those of the LNT group with different concentrations were significantly lower than those of the BS group (P<0.05). Compared with the sham group, the protein expression levels of NF-κB, iNOS, and ICAM-1 along with the levels of pro-inflammatory factors TNF-α and IL-6 in serum were significantly increased, while the levels of anti-inflammatory factors IL-4 and IL-10 were obviously lower in the BS group. Compared with the BS group, the protein expression levels of NF-κB, iNOS, and ICAM-1 along with the levels of pro-inflammatory factors TNF-α and IL-6 in serum were significantly decreased, while the levels of anti-inflammatory factors IL-4 and IL-10 were obviously increased in the LNT group with different concentrations. Conclusions: LNT has a certain protective effect on AKI in septic rats, and its mechanism may involve inhibiting the activation of NF-κB, which suppresses the expression of proinflammatory factors in turn, thus promoting the release of anti-inflammatory factors.

This study aimed to assess the associations of serum soluble klotho and fibroblast growth factor 23 (FGF-23) with the occurrence of carotid artery calcification. Peritoneal dialysis patients treated from June 2018 to June 2019 were retrospectively analyzed. They were divided into the carotid artery calcification and non-carotid artery calcification groups according to color Doppler ultrasound findings. Basic indicators in both groups were compared, and the influencing factors of carotid artery calcification were analyzed by logistic regression. Among the 73 continuous ambulatory peritoneal dialysis (CAPD) patients enrolled, 40 (54.8%) had carotid artery calcification. Significant differences were found in age (68.85 ± 7.45 vs 46.62 ± 5.51 years), dialysis time (8.15 ± 1.42 vs 6.02 ± 1.14 months), klotho amounts (325.56 ± 41.15 vs 436.65 ± 45.58 pg/mL) and FGF-23 levels (114.45 ± 15.56 vs 70.15 ± 12.23 pg/mL) between the carotid artery calcification and non-carotid artery calcification groups (all P < .001). The above factors were associated with carotid artery calcification occurrence in univariate analysis. Multivariate analysis showed that elevated age (odds ratio [OR] = 1.55, 95% confidence interval [CI] 1.13–1.74; P = .025) and FGF-23 (OR = 2.16, 95% CI 2.01–2.44; P = .042), and lower klotho (OR = 0.66, 95% CI 0.47–0.85; P = .036) were independent risk factors for carotid artery calcification in CAPD. Serum FGF-23 and age are risk factors for carotid artery calcification in patients with CAPD, whereas klotho is a protective factor.

Aim: The correlation between soluble Klotho (sKlotho) levels and clinical outcomes remains inconclusive for patients undergoing maintenance haemodialysis (MHD). We aimed to evaluate the potential predictive significance of sKlotho in this population by conducting a meta-analysis. Methods: PubMed, Embase, Web of Science and Cochrane Library were comprehensively searched for studies concerning the association between sKlotho level and clinical outcomes including cardiovascular (CV) events and all-cause mortality. The pooled hazard ratios (HR) and 95% confidence intervals (CI) were generated using either random or fixed effects models. Sensitivity and subgroup analyses were used to explore heterogeneity sources. Results: Eight prospective studies with 992 MHD participants were included and reduced sKlotho levels predicted more adverse outcomes in this meta-analysis. The pooled HRs and 95% CIs related to CV events, mortality, or composite outcomes were 1.73 (95% CI 1.08–2.76, p = 0.02), 2.34 (95% CI 1.34–2.07, p = 0.003) or 1.75 (95% CI 1.19–2.57, p = 0.005). Moderate heterogeneity was observed in the composite adverse outcomes ( I² = 57%, p = 0.05). Age and sKlotho level were the main sources of heterogeneities in the subgroup analysis. Conclusion: Lower sKlotho levels were associated with more CV events and all-cause mortality, suggesting that sKlotho may have predictive value in CKD patients receiving haemodialysis.

Long-term peritoneal dialysis (PD) is accompanied by low-grade intraperitoneal inflammation and may eventually lead to peritoneal membrane injury with a high solute transport rate and ultrafiltration failure. Osteopontin (OPN) is highly expressed through the stimulation of pro-inflammatory cytokines in many cell types. This study aimed to investigate the potential of OPN as a new indicator of peritoneal deterioration. One hundred nine continuous ambulatory PD patients were analyzed. The levels of OPN and IL-6 in peritoneal effluents or serum were analyzed by ELISA kits. The mean effluent OPN concentration was 2.39 ± 1.87 ng/mL. The OPN levels in drained dialysate were correlated with D/P Cr ( p < 0.0001, R = 0.54) and D/D0 glucose ( p < 0.0001, R = 0.39). Logistic regression analysis showed that the OPN levels in peritoneal effluents were an independent predictive factor for the increased peritoneal solute transport rate (PSTR) obtained by the peritoneal equilibration test ( p < 0.001). The area under the receiver operating characteristic curve of OPN was 0.84 (95% CI: 0.75–0.92) in predicting the increased PSTR with a sensitivity of 86% and a specificity of 67%. The joint utilization of effluent OPN with age, effluent IL-6, and serum albumin further increased the specificity (81%). Thus, OPN may be a useful indicator of peritoneal deterioration in patients with PD.