Alleviation of cholestatic liver injury and intestinal permeability by lubiprostone treatment in bile duct ligated rats: role of intestinal FXR and tight junction proteins claudin-1, claudin-2, and occludin

Therapeutic effects of composite probiotics derived from fermented camel milk on metabolic dysregulation and intestinal barrier integrity in type 2 diabetes rats

Background

In the Kazakh community of Xinjiang, China, fermented camel milk has been traditionally used to manage diabetes. This study evaluates the effects of composite probiotics derived from fermented camel milk (CPCM) on metabolic disturbances in a rat model of Type 2 diabetes (T2DM).

Methods

T2DM was induced in Wistar rats using streptozotocin. Experimental groups included a diabetic control, Metformin, and low- and high-dose CPCM. Measurements over 6 weeks included body weight (BW), fasting blood glucose (FBG), oral glucose tolerance test (OGTT), glycated hemoglobin (HbA1c), C-peptide (CP), lipid profiles, inflammatory markers, fecal short-chain fatty acids (SCFAs), and tight junction protein expression in colonic tissues.

Results

High-dose CPCM significantly increased BW by 22.2% (p < 0.05) and reduced FBG by 6.5 mmol/L (p < 0.001). The OGTT AUC decreased by 40.1% (p < 0.001), and HbA1c levels fell by 22.9% (p < 0.01). CP levels rose by 21.8% (p < 0.05). Lipid profiles improved: TC decreased by 40.0%, TG by 17.1%, and LDL-C by 30.4% (all p < 0.001). Fecal SCFAs, including acetate (75.4%, p < 0.001), methyl acetate (18.9%, p < 0.05), and butyrate (289.9%, p < 0.001), increased, with total SCFAs rising by 89.7% (p < 0.001). Inflammatory markers IL-1β (12.7%, p < 0.01), TNF-α (16.7%, p < 0.05), and IL-6 (17.3%, p < 0.01) were significantly reduced. Tight junction protein expression (ZO-1, occludin, claudin-1) and mucin (MUC2) in colonic tissues increased (p < 0.05). CPCM treatment also reduced serum total bile acids by 24.9%, while hepatic and fecal bile acids increased by 114.0% and 37.8% (all p < 0.001). CPCM lowered serum DAO, D-lactate, and LPS levels (all p < 0.001). mRNA levels of TGR5 and CYP7A1 in the liver, and TGR5 and FXR in the colon, were markedly elevated (all p < 0.001). Histological examinations revealed reduced pancreatic inflammation and hepatic steatosis, with restored colonic structure.

Conclusion

CPCM treatment significantly improved metabolic dysregulation in the T2DM rat model, reducing blood glucose and lipid levels, enhancing intestinal barrier function, and increasing insulin secretion. These findings highlight the therapeutic potential of CPCM in T2DM management and probiotics' role in metabolic health.

HO-1-induced autophagy establishes a HO-1-p62-Nrf2 positive feedback loop to reduce gut permeability in cholestatic liver disease

OBJECTIVES

The gut-liver axis disruption is a unified pathogenetic principle of cholestatic liver disease (CSLD). Increased gut permeability is the leading cause of gut-liver axis disruption. HO-1 is capable of protecting against gut-liver axis injury. However, it has rarely been reported whether autophagy is involved in HO-1 protecting gut-liver barrier integrity and the underlying mechanism.

MATERIALS AND METHODS

Mice underwent bile duct ligation (BDL) was established as CSLD model in vivo. Caco-2 cells with LPS treatment was established as in vitro cell model. Immunofluorescence, western blot and transepithelial electrical resistance (TER) assay were used to observe epithelial tight junction (TJ) and autophagy. Liver injury and fibrosis were evaluated as well through H&E staining, masson staining, sirius red staining and ELISA.

RESULTS AND CONCLUSIONS

Our study demonstrated that the epithelial TJ and TER were notably reduced both in BDL mice and in LPS treated intestinal epithelial cells. Increased HO-1 expression could significantly induce intestinal epithelial cell autophagy. Additionally, this increased autophagy level reversed the reduction effects of BDL or LPS on epithelial TJ and TER in vivo and in vitro, therefore decreased transaminase level in serum and relieved liver fibrosis in BDL mice. Besides, increased autophagy level in turn upregulated the expression of HO-1 by p62 degradation of Keap1 and subsequent activation of Nrf2 pathway. Collectively, these results indicate that HO-1 reduces gut permeability by enhancing autophagy level in CSLD, the increased autophagy establishes a HO-1-p62-Nrf2 positive feedback loop to further improve gut-liver axis disruption. Therefore, our study confirms the critical role of autophagy in HO-1 ameliorating gut-liver axis injury during CSLD, highlighting HO-1 as a promising therapeutic target.

D-beta-hydroxybutyrate up-regulates Claudin-1 and alleviates the intestinal hyperpermeability in lipopolysaccharide-treated mice

The hyperpermeability of intestinal epithelium is a key contributor to the occurrence and development of systemic inflammation. Although D-beta-hydroxybutyrate (BHB) exhibits various protective effects, whether it affects the permeability of intestinal epithelium in systemic inflammation has not been clarified. In this study, we investigated the effects of BHB on the intestinal epithelial permeability, the epithelial marker E-cadherin and the tight junction protein Claudin-1 in colon in the lipopolysaccharide (LPS)-induced systemic inflammation mouse model. Intraperitoneal injection of LPS was used to induce systemic inflammation and BHB was given by oral administration. The permeability of intestinal epithelium, the morphological changes of colonic epithelium, the distribution and generation of colon E-cadherin, and the Claudin-1 generation and its epithelial distribution in colon were detected. The results confirmed the intestinal epithelial hyperpermeability and inflammatory changes in colonic epithelium, with disturbed E-cadherin distribution in LPS-treated mice. Besides, colon Claudin-1 generation was decreased and its epithelial distribution in colon was weakened in LPS-treated mice. However, BHB treatments alleviated the LPS-induced hyperpermeability of intestinal epithelium, attenuated the colonic epithelial morphological changes and promoted orderly distribution of E-cadherin in colon. Furthermore, BHB up-regulated colon Claudin-1 generation and promoted its colonic epithelial distribution and content in LPS-treated mice. In conclusion, BHB may alleviate the hyperpermeability of intestinal epithelium via up-regulation of Claudin-1 in colon in LPS-treated mice.