Chronic kidney disease (CKD) patients are prone to disturbances in the intestinal microbiota, which contributes to CKD progression and complications. We previously reported a reduction of serum phosphorus (P) levels i...Chronic kidney disease (CKD) patients are prone to disturbances in the intestinal microbiota, which contributes to CKD progression and complications. We previously reported a reduction of serum phosphorus (P) levels in hemodialysis patients receiving oral encapsulated bifidobacteria. The present study was conducted to clarify the mechanisms of P-lowering effect of bifidobacteria on CKD rats. CKD was induced in rats by 5/6 nephrectomy. Five weeks later, the rats were fed for 4 weeks on a powder diet containing encapsulated bifidobacteria. At the end of the study, intestinal contents were sampled for analyses of pH, intestinal flora and short-chain fatty acids (SCFAs). Oral administration of bifidobacteria halted the onset and progression of hyperphosphatemia in CKD rats. The increased number of bifidobacteria was confirmed in the cecum. In addition, the increase in intestinal pH in CKD rats was decreased after bifidobacteria treatment, along with increases in some SCFAs. Furthermore, positive correlation between serum P levels and intestinal pH was observed. In conclusion, the mechanism for the P-lowering effect of bifidobacteria was supposed as follows: CKD conditions increase aerobic bacteria which hydrolyze urea into ammonia. Elevated pH decreases ionization of intestinal calcium (Ca) which leads to an increase in free phosphate ions through reduction of Ca phosphate crystal precipitation. Administered bifidobacteria fermented carbohydrates to produce SCFAs, resulting in acidification of the intestinal lumen. The resulting low intestinal pH increases Ca ionization, which binds with free phosphate ions as an intrinsic P binder, resulting in the reduction of serum P levels.展开更多
Objective Obesity-induced kidney injury contributes to the development of diabetic nephropathy(DN).Here,we identified the functions of ubiquitin-specific peptidase 19(USP19)in HK-2 cells exposed to a combination of hi...Objective Obesity-induced kidney injury contributes to the development of diabetic nephropathy(DN).Here,we identified the functions of ubiquitin-specific peptidase 19(USP19)in HK-2 cells exposed to a combination of high glucose(HG)and free fatty acid(FFA)and determined its association with TGF-beta-activated kinase 1(TAK1).Methods HK-2 cells were exposed to a combination of HG and FFA.USP19 mRNA expression was detected by quantitative RT-PCR(qRT-PCR),and protein analysis was performed by immunoblotting(IB).Cell growth was assessed by Cell Counting Kit-8(CCK-8)viability and 5-ethynyl-2′-deoxyuridine(EdU)proliferation assays.Cell cycle distribution and apoptosis were detected by flow cytometry.The USP19/TAK1 interaction and ubiquitinated TAK1 levels were assayed by coimmunoprecipitation(Co-IP)assays and IB.Results In HG+FFA-challenged HK-2 cells,USP19 was highly expressed.USP19 knockdown attenuated HG+FFA-triggered growth inhibition and apoptosis promotion in HK-2 cells.Moreover,USP19 knockdown alleviated HG+FFA-mediated PTEN-induced putative kinase 1(PINK1)/Parkin pathway inactivation and increased mitochondrial reactive oxygen species(ROS)generation in HK-2 cells.Mechanistically,USP19 stabilized the TAK1 protein through deubiquitination.Importantly,increased TAK1 expression reversed the USP19 knockdown-mediated phenotypic changes and PINK1/Parkin pathway activation in HG+FFA-challenged HK-2 cells.Conclusion The findings revealed that USP19 plays a crucial role in promoting HK-2 cell dysfunction induced by combined stimulation with HG and FFAs by stabilizing TAK1,providing a potential therapeutic strategy for combating DN.展开更多
文摘Chronic kidney disease (CKD) patients are prone to disturbances in the intestinal microbiota, which contributes to CKD progression and complications. We previously reported a reduction of serum phosphorus (P) levels in hemodialysis patients receiving oral encapsulated bifidobacteria. The present study was conducted to clarify the mechanisms of P-lowering effect of bifidobacteria on CKD rats. CKD was induced in rats by 5/6 nephrectomy. Five weeks later, the rats were fed for 4 weeks on a powder diet containing encapsulated bifidobacteria. At the end of the study, intestinal contents were sampled for analyses of pH, intestinal flora and short-chain fatty acids (SCFAs). Oral administration of bifidobacteria halted the onset and progression of hyperphosphatemia in CKD rats. The increased number of bifidobacteria was confirmed in the cecum. In addition, the increase in intestinal pH in CKD rats was decreased after bifidobacteria treatment, along with increases in some SCFAs. Furthermore, positive correlation between serum P levels and intestinal pH was observed. In conclusion, the mechanism for the P-lowering effect of bifidobacteria was supposed as follows: CKD conditions increase aerobic bacteria which hydrolyze urea into ammonia. Elevated pH decreases ionization of intestinal calcium (Ca) which leads to an increase in free phosphate ions through reduction of Ca phosphate crystal precipitation. Administered bifidobacteria fermented carbohydrates to produce SCFAs, resulting in acidification of the intestinal lumen. The resulting low intestinal pH increases Ca ionization, which binds with free phosphate ions as an intrinsic P binder, resulting in the reduction of serum P levels.
基金supported by Natural Science Foundation of Shaanxi Province(No.2023-JC-YB-743 and No.2021JQ-905).
文摘Objective Obesity-induced kidney injury contributes to the development of diabetic nephropathy(DN).Here,we identified the functions of ubiquitin-specific peptidase 19(USP19)in HK-2 cells exposed to a combination of high glucose(HG)and free fatty acid(FFA)and determined its association with TGF-beta-activated kinase 1(TAK1).Methods HK-2 cells were exposed to a combination of HG and FFA.USP19 mRNA expression was detected by quantitative RT-PCR(qRT-PCR),and protein analysis was performed by immunoblotting(IB).Cell growth was assessed by Cell Counting Kit-8(CCK-8)viability and 5-ethynyl-2′-deoxyuridine(EdU)proliferation assays.Cell cycle distribution and apoptosis were detected by flow cytometry.The USP19/TAK1 interaction and ubiquitinated TAK1 levels were assayed by coimmunoprecipitation(Co-IP)assays and IB.Results In HG+FFA-challenged HK-2 cells,USP19 was highly expressed.USP19 knockdown attenuated HG+FFA-triggered growth inhibition and apoptosis promotion in HK-2 cells.Moreover,USP19 knockdown alleviated HG+FFA-mediated PTEN-induced putative kinase 1(PINK1)/Parkin pathway inactivation and increased mitochondrial reactive oxygen species(ROS)generation in HK-2 cells.Mechanistically,USP19 stabilized the TAK1 protein through deubiquitination.Importantly,increased TAK1 expression reversed the USP19 knockdown-mediated phenotypic changes and PINK1/Parkin pathway activation in HG+FFA-challenged HK-2 cells.Conclusion The findings revealed that USP19 plays a crucial role in promoting HK-2 cell dysfunction induced by combined stimulation with HG and FFAs by stabilizing TAK1,providing a potential therapeutic strategy for combating DN.
