Berberine ameliorates chronic kidney disease through inhibiting the production of gut-derived uremic toxins in the gut microbiota

At present, clinical interventions for chronic kidney disease are very limited, and most patients rely on dialysis to sustain their lives for a long time. However, studies on the gut-kidney axis have shown that the gut microbiota is a potentially effective target for correcting or controlling chronic kidney disease. This study showed that berberine, a natural drug with low oral availability, significantly ameliorated chronic kidney disease by altering the composition of the gut microbiota and inhibiting the production of gut-derived uremic toxins, including p-cresol. Furthermore, berberine reduced the content of p-cresol sulfate in plasma mainly by lowering the abundance of g_Clostridium_sensu_stricto_1 and inhibiting the tyrosine-p-cresol pathway of the intestinal flora. Meanwhile, berberine increased the butyric acid producing bacteria and the butyric acid content in feces, while decreased the renal toxic trimethylamine N-oxide. These findings suggest that berberine may be a therapeutic drug with significant potential to ameliorate chronic kidney disease through the gut-kidney axis.

Strategy to delay the progression of chronic kidney disease by targeting gut microbiota and uremic toxins metabolism pathway / 药学学报

Chronic kidney disease (CKD) is a serious chronic disease with high incidence, poor prognosis, and a variety of complications. Indoxyl-sulfate (IS) and p-cresol sulfate (PCS) are two typical gut-derived uremic toxins, which are produced by the co-metabolism of intestinal microbes and the host. With the progression of CKD, gut-derived uremic toxins such as IS and PCS accumulate in patients with CKD and thereafter accelerate the progression of CKD. Gut microbiota is closely related with CKD, and targeting gut microbiota to regulate gut-derived uremic toxins synthesis and metabolic pathways may be a promising strategy to delay the progression of CKD. In this paper, the relationship between gut microbiota, gut-derived uremic toxins, and CKD was analyzed, and the strategy to delay the progression of CKD by targeting gut microbiota and uremic toxins metabolism pathway was proposed.

Key microbial populations involved in anaerobic degradation of phenol and p-cresol using different inocula

Background: Anaerobic digestion is an alternative bioprocess used to treat effluents containing toxic compounds such as phenol and p-cresol. Selection of an adequate sludge as inoculum containing an adapted microbial consortium is a relevant factor to improve the removal of these pollutants. The objective of this study is to identify the key microorganisms involved in the anaerobic digestion of phenol and p-cresol and elucidate the relevance of the bamA gene abundance (a marker gene for aromatic degraders) in the process, in order to establish new strategies for inocula selection and improve the system's performance. Results: Successive batch anaerobic digestion of phenol and p-cresol was performed using granular or suspended sludge. Granular sludge in comparison to suspended sludge showed higher degradation rates both for phenol (11.3 ± 0.7 vs 8.1 ± 1.1 mg l-1 d-1) and p-cresol (7.8 ± 0.4 vs 3.7 ± 1.0 mg l-1 d-1). After three and four re-feedings of phenol and p-cresol, respectively, the microbial structure from both sludges was clearly different from the original sludges. Anaerobic digestion of phenol and p-cresol generated an abundance increase in Syntrophorhabdus genus and bamA gene, together with hydrogenotrophic and aceticlastic archaea. Analysis of results indicates that differences in methanogenic pathways and levels of Syntrophorhabdus and bamA gene in the inocula, could be the causes of dissimilar degradation rates between each sludge. Conclusions: Syntrophorhabdus and bamA gene play relevant roles in anaerobic degradation of phenolics. Estimation of these components could serve as a fast screening tool to find the most acclimatized sludge to efficiently degrade mono-aromatic compounds.

Melatonin Rescues Mesenchymal Stem Cells from Senescence Induced by the Uremic Toxin p-Cresol via Inhibiting mTOR-Dependent Autophagy

p-Cresol, found at high concentrations in the serum of chronic kidney failure patients, is known to cause cell senescence and other complications in different parts of the body. p-Cresol is thought to mediate cytotoxic effects through the induction of autophagy response. However, toxic effects of p-cresol on mesenchymal stem cells have not been elucidated. Thus, we aimed to investigate whether p-cresol induces senescence of mesenchymal stem cells, and whether melatonin can ameliorate abnormal autophagy response caused by p-cresol. We found that p-cresol concentration-dependently reduced proliferation of mesenchymal stem cells. Pretreatment with melatonin prevented pro-senescence effects of p-cresol on mesenchymal stem cells. We found that by inducing phosphorylation of Akt and activating the Akt signaling pathway, melatonin enhanced catalase activity and thereby inhibited the accumulation of reactive oxygen species induced by p-cresol in mesenchymal stem cells, ultimately preventing abnormal activation of autophagy. Furthermore, preincubation with melatonin counteracted other pro-senescence changes caused by p-cresol, such as the increase in total 5′-AMP-activated protein kinase expression and decrease in the level of phosphorylated mechanistic target of rapamycin. Ultimately, we discovered that melatonin restored the expression of senescence marker protein 30, which is normally suppressed because of the induction of the autophagy pathway in chronic kidney failure patients by p-cresol. Our findings suggest that stem cell senescence in patients with chronic kidney failure could be potentially rescued by the administration of melatonin, which grants this hormone a novel therapeutic role.

An in vitro study of effects of the uremic toxin p-cresol on release of inflammatory cytokines from monocytes / 解放军医学杂志

Objective To evaluate the effect of uremic toxin p-cresol on the release of inflammatory cytokines from monocytes and explore its potential mechanism. Methods CCK-8 was employed to evaluate the proliferation status of monocytes cell-line THP-1 after being exposed to 20, 40, 80, 160mg/L of p-cresol for 6, 12 or 24h, while 40mg/L and 80mg/L were assigned as low-dose group and high-dose group. RNA and protein were extracted. RT-PCR and Western blotting were employed to evaluate the mRNA and protein expression of proinflammatory cytokine TNF-α, anti-inflammatory cytokine IL-10, as well as Toll-like receptor-4 (TLR-4) of THP-1 cell exposed to p-cresol for 24h. Results P-cresol depressed the proliferation ability of THP-1 in a dose-and time-dependent manner (P<0.05). RT-PCR and Western blotting showed that both TNF-α and TLR-4 were over-expressed in THP-1 cell exposed to p-cresol, while the expression of IL-10 was reduced (P<0.05). Conclusion P-cresol may inhibit both the proliferation of THP-1 cell and the release of IL-10. By up-regulating the expression of TLR-4, p-cresol may stimulate the release of TNF-α, resulting in microinflammation.

Effects of D-cresol on the proliferation and cell cycle of human umbilical vein endothelial cells / 中华肾脏病杂志

Objective To investigate the effects of p-cresol on human umbilical vein endothelial cells.Methods The effects of p-cresol on endothelial cell growth,cell cycle,cell morphological change and p21 protein were detected by the CCK-8 assay,flow cytometry assay,inverted microscope and Western blotting.Results P-cresol could inhibit the growth of human umbilical vein endothelial cells in dose-and time-dependent manners (all P ＜ 0.05).The human umbilical vein endothelial cells treated with p-cresol became elongated processes,cloudy cytoplasm,and irregular shapes.The p-cresol stopped human umbilical vein endothelial cells at cell cycle G1 and had no effect on cell apoptosis.The p-cresol could increase protein expression of p21 in a dose dependent manner (P ＜ 0.05).Conclusion P-cresol can increase protein expression of p21,induce cell cycle arrest at G1 stage and inhibit the proliferation of human umbilical vein endothelial cells.