Mechanism of Ulcerative Colitis-Aggravated Liver Fibrosis: The Activation of Hepatic Stellate Cells and TLR4 Signaling Through Gut-Liver Axis

Role of Olive Leaf Extract, Mesenchymal Stem Cells or Low Radiation Dose in Alleviating Hepatic Injury in Rats

Objectives

This study was conducted to determine the efficacy of mesenchymal stem cells (MSCs) or low-dose gamma radiation (LDR) on liver injury compared to the effect of olive leaf extract as a hepatoprotective agent.

Methods

Rats were allocated into six groups; group I served as the negative control. Group II received 5% dextran sodium sulfate (DSS) in its drinking water for 1 week. Group III was injected with a single dose of 1 × 106 bone marrow-derived mesenchymal stem cells (BM-MSCs) intravenously. Group IV was treated as in group III after 5% DSS treatment. Group V was given 5% DSS, followed by olive leaf extract (OLE) (1000 mg/ kg, oral). Group VI: 5% DSS for 1 week, then was exposed to low-dose gamma radiation (LDR) (0.05 Gy).

Results

Rats treated with OLE, BM-MSCs, or exposed to LDR exerted significant alleviation in all hepatic biomarkers, significant enhancements in oxidative stress parameters, and improvements in inflammatory biomarkers Interleukin-1 beta (IL-1β) and Interferon gamma (INF-γ) hepatic contents compared with those of the DSS group. Histological pictures emphasized the biochemical findings.

Conclusions

BM-MSCs might be a valuable therapeutic approach to overcome hepatic injury. Exposure to LDR provided protective mechanisms that allow the body to survive better.

Alleviating effect of selenium-enriched Lactobacillus plantarum 6076 on dextran sulfate sodium-induced colitis and liver inflammation in mice

The aim of this study is to investigate the alleviating effect of selenium-enriched Lactobacillus plantarum (SL) 6076 on colitis and liver inflammation induced by sodium dextran sulfate (DSS) in mice and its potential molecular mechanisms. Lactobacillus plantarum (LA) was cultured for 3 generations on MRS medium containing sodium selenite to generate SL. LA (3.2 × 1011 CFU mL-1), low selenium Lactobacillus plantarum (LS) (3.9 × 1010 CFU mL-1, 0.35 mg mL-1 Se) and high selenium Lactobacillus plantarum (HS) (2.8 × 1010 CFU mL-1, 0.52 mg mL-1 Se) were continuously fed to mice for 21 d to observe their effects on DSS-induced colitis and liver inflammation in mice. The composition of gut microbiota was detected through high-throughput 16S rRNA sequencing, and inflammatory cytokines, oxidative stress parameters, and serum biochemical indicators were measured in the colon and liver using quantitative polymerase chain reaction (qPCR) and biochemical analysis methods. The results showed that SL alleviated inflammation symptoms in the colon and liver, reduced the expression of inflammatory factors in the colon and liver, regulated oxidative stress responses in the colon, downregulated NF-κB-P65 pathway factors, and altered the composition and structure of the gut microbiota. In summary, DSS-induced colitis may cause liver inflammation, and SL had a significant relieving effect on both colon and liver inflammation. The intervention effect of SL was better than that of LA, while HS was better than LS. SL had a significant alleviating effect on DSS-induced colitis, and may exert its therapeutic effect by downregulating NF-κB-P65 signaling pathways and regulating the structure of intestinal microbiota. This study provides a new approach for the treatment of colitis.

Shared biomarkers and immune cell infiltration signatures in ulcerative colitis and nonalcoholic steatohepatitis

The coexistence of ulcerative colitis (UC) and nonalcoholic steatohepatitis (NASH) involves a intricate interplay, though the precise pathophysiological mechanisms remain elusive. To shed light on this, our study endeavors to unravel the shared gene signatures and molecular mechanisms by employing quantitative bioinformatics analysis on a publicly available RNA-sequencing database. Gene expression profiles of UC (GSE87466) and NASH (GSE89632) were retrieved from the Gene Expression Omnibus (GEO) database. Differentially expressed genes (DEGs) were analyzed using R software. After identifying common DEGs, functional enrichment analysis, protein-protein interaction (PPI) network analysis and module construction were performed to obtain candidate hub genes. GSE47908 for UC and GSE159676 for NASH were selected to validate the obtained candidate genes. A total of 119 common DEGs were found in NASH and UC patients. Functional and pathway analyses emphasized that viral infection, inflammation and immune response were enriched in these two diseases. After module construction and validation, CD2, CD8A, GNLY, IFI44, NKG7 and OAS2 were identified as hub genes. 6 hub genes and their combined prediction scores were found with an impressive accuracy and sensitivity. Functional estimation, gene set enrichment analysis and immune infiltration signature identification showed notable associations of the six hub genes with T cells, natural killer cells and type I interferon levels. In addition, we constructed UC combined with NASH mice model successfully with significantly higher expression of hub genes in both liver and colonic tissues than those in control group. Our study elucidates 6 hub genes of UC and NASH, which may participate in immune, inflammatory and antiviral effects. These findings provide some potential biochemical markers for further exploration of UC coexistence with NASH.

Activated Hepatic Nuclear Factor-κB in Experimental Colitis Regulates CYP2A5 and Metronidazole Disposition

Systemic exposure of metronidazole is increased in patients with inflammatory bowel diseases (IBDs), while the underlying mechanism remains unknown. Here, we aim to decipher the mechanisms by which experimental colitis regulates metronidazole disposition in mice. We first confirmed that the systemic exposure of metronidazole was elevated in dextran sulfate sodium (DSS)-induced experimental colitis. Hepatic microsomal incubation with metronidazole revealed that the production rate of 2-hydroxymetronidazole was inhibited, suggestive of a diminished hydroxylation reaction upon colitis. Remarkably, the hydroxylation reaction of metronidazole was selectively catalyzed by CYP2A5, which was downregulated in the liver of colitis mice. In addition, hepatic nuclear factor (NF)-κB (a prototypical and critical signaling pathway in inflammation) was activated in colitis mice. Luciferase reporter and chromatin immunoprecipitation assay indicated that NF-κB downregulated Cyp2a5 transcription through binding to an NF-κB binding site (-1711 to -1720 bp) in the promoter. We further verified that the regulatory effects of colitis on CYP2A5 depended on the disease itself rather than the DSS compound. First, one-day administration of DSS did not alter mRNA and protein levels of CYP2A5. Moreover, CYP2A5 was suppressed in the Il-10^-/- spontaneously developing colitis model. Furthermore, Cyp2a5 expression was downregulated in both groups of mice with modest or severe colitis, whereas the expression change was much more significant in severe colitis as compared to modest colitis. Altogether, activated hepatic NF-κB in experimental colitis regulates CYP2A5 and metronidazole disposition, revealing the mechanism of pharmacokinetic instability under IBDs, and providing a theoretical foundation for rational drug use in the future.

Dysregulated hepatic UDP-glucuronosyltransferases and flavonoids glucuronidation in experimental colitis

Glucuronidation catalyzed by UDP-glucuronosyltransferases (UGTs) is one of the most important phase II mechanisms, facilitating drug clearance via conjugation of glucuronic acid with polar groups of xenobiotics. Accumulating evidence suggests that IBDs impact drug disposition, but whether and how IBDs regulate UGTs and drug glucuronidation remains undefined. In this study, we aim to investigate the expression of UGTs and drug glucuronidation in experimental colitis. Given that glucuronidation occurs primarily in the liver, we analyzed the mRNA changes in hepatic UGTs with a DSS-induced mouse colitis model. Twelve UGTs were downregulated in the liver of colitis mice including UGT1A1 and UGT1A9 (two representative UGTs). Colitis in mice downregulated UGT1A1 and UGT1A9 in the liver but not in small intestine, colon, and kidney. We also established that the downregulation of UGTs was attributed to the disease itself rather than the DSS compound. Moreover, colitis-reduced UGT1A1 and UGT1A9 lead to dampened baicalein and puerarin glucuronidation. PXR was the only UGT regulator significantly downregulated in colitis mice, suggesting dysregulation of PXR is associated with the downregulation of UGT1A1 and UGT1A9, thereby potentially resulting in dysfunction of baicalein and puerarin glucuronidation. Collectively, we establish that UGTs and glucuronidation are dysregulated in colitis, and this effect may cause variation in drug responsiveness in IBDs.

Comprehensive Phenotyping in Inflammatory Bowel Disease: Search for Biomarker Algorithms in the Transkingdom Interactions Context

Inflammatory bowel disease (IBD) is the most common form of intestinal inflammation associated with a dysregulated immune system response to the commensal microbiota in a genetically susceptible host. IBD includes ulcerative colitis (UC) and Crohn's disease (CD), both of which are remarkably heterogeneous in their clinical presentation and response to treatment. This translates into a notable diagnostic challenge, especially in underdeveloped countries where IBD is on the rise and access to diagnosis or treatment is not always accessible for chronic diseases. The present work characterized, for the first time in our region, epigenetic biomarkers and gut microbial profiles associated with UC and CD patients in the Buenos Aires Metropolitan area and revealed differences between non-IBD controls and IBD patients. General metabolic functions associated with the gut microbiota, as well as core microorganisms within groups, were also analyzed. Additionally, the gut microbiota analysis was integrated with relevant clinical, biochemical and epigenetic markers considered in the follow-up of patients with IBD, with the aim of generating more powerful diagnostic tools to discriminate phenotypes. Overall, our study provides new insights into data analysis algorithms to promote comprehensive phenotyping tools using quantitative and qualitative analysis in a transkingdom interactions network context.

Effects of Dextran Sulfate Sodium-Induced Ulcerative Colitis on the Disposition of Tofacitinib in Rats

Tofacitinib, a Janus kinase 1 and 3 inhibitor, is mainly metabolized by CYP3A1/2 and CYP2C11 in the liver. The drug has been approved for the chronic treatment of severe ulcerative colitis, a chronic inflammatory bowel disease. This study investigated the pharmacokinetics of tofacitinib in rats with dextran sulfate sodium (DSS)-induced ulcerative colitis. After 1-min of intravenous infusion of tofacitinib (10 mg/kg), the area under the plasma concentration-time curves from time zero to time infinity (AUC) of tofacitinib significantly increased by 92.3%. The time-averaged total body clearance decreased significantly by 47.7% in DSS rats compared with control rats. After the oral administration of tofacitinib (20 mg/kg), the AUC increased by 85.5% in DSS rats. These results could be due to decreased intrinsic clearance of the drug caused by the reduction of CYP3A1/2 and CYP2C11 in the liver and intestine of DSS rats. In conclusion, ulcerative colitis inhibited CYP3A1/2 and CYP2C11 in the liver and intestines of DSS rats and slowed the metabolism of tofacitinib, resulting in increased plasma concentrations of tofacitinib in DSS rats.

TAK-242 Ameliorates Hepatic Fibrosis by Regulating the Liver-Gut Axis

Objective. The aims of this study were to investigate the impact of TAK-242 on the Toll-like receptor 4 (TLR4)/myeloid differentiation factor 88 (MyD88)/nuclear transcription factor-κB (NF-κB) signal transduction pathway in rats with hepatic fibrosis (HF) using the liver gut axis and to investigate the molecular mechanism of its intervention on HF. Methods. SPF grade SD male rats were randomly allocated to the control, model, and TAK-242 groups. For 8 weeks, the model and TAK-242 groups received 3 mL·kg-1 (the initial dose 5 mL·kg-1) intraperitoneal injections of 40% CCL4 olive oil solution. TAK-242 (5 mg·kg-1) was administered once a day for 5 days after modeling. The pathological alterations of liver and small intestine tissues in each group were observed using H&E and Masson staining. ELISA was used to measure serum levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST), direct bilirubin (DBIL), total bilirubin (TBIL), interleukin-1β (IL-1β), interleukin-6 (IL-6), and tumor necrosis factor alpha (TNF-α). RT-qPCR was utilized to identify the mRNA expression level of IL-1β, IL-6, TNF-α, TLR4, MyD88, and NF-κB in rat liver and small intestine tissues. The protein level of IL-1β, IL-6, TNF-α, TLR4, MyD88, and NF-κB protein in rat liver and small intestine tissues was determined utilizing Western blot and IHC. Results. TAK-242 significantly reduced AST, ALT, TBIL, and DBIL expression in HF rats’ serum ( $P<0.01$ ) and alleviated liver tissue injury. Hematoxylin-eosin (H&E) and Masson staining revealed inflammatory cell infiltration and fibrous proliferation in the liver and small intestine tissue in the model group and partial cell swelling in the TAK-242 group, which indicated a considerable improvement compared to the model group. RT-qPCR, Western blot, and IHC data indicated that TAK-242 reduced the IL-1β, IL-6, TNF-α, TLR4, MyD88, and NF-κB expression in the liver and small intestine tissues of HF rats. Conclusion. TAK-242 might downregulate the TLR4/MyD88/NF-κB signal pathway through the liver-gut axis, suppress the inflammatory response, and eventually alleviate HF in rats.