Bi-directional Mendelian randomization analysis provides evidence for the causal involvement of dysregulation of CXCL9, CCL11 and CASP8 in the pathogenesis of ulcerative colitis

Causal relationship between circulating immune cells and inflammatory bowel disease: A Mendelian randomization analysis

Inflammatory bowel disease (IBD) is an immune-mediated inflammation of the gastrointestinal tract that includes Crohn disease and ulcerative colitis (UC). Although IBD is associated with elevated levels of innate and adaptive immunity, the relationship between circulating immune cells and IBD remains largely unknown. Therefore, we conducted a bidirectional 2-sample Mendelian randomization (MR) study to determine their causal relationship. Genome-wide association study summary statistics were extracted from publicly available databases regarding immune cell phenotypes and IBD traits (including IBD, Crohn disease, and UC). MR analysis was conducted using 5 MR methods, with inverse-variance-weighted (IVW) as the primary analysis method. False discovery rate correction (FDR) was used to reduce the likelihood of type 1 errors. We also conducted MR-Egger-intercept tests to evaluate horizontal pleiotropy. After FDR adjustment of the P values for the IVW method, the results indicated no causal relationship between immune cell phenotypes and IBD or UC, but 4 immune characteristics were causally associated with Crohn disease. The percentage of human leukocyte antigen DR+ CD4+ T cells in lymphocytes was positively associated with the development of Crohn disease (odd ratio [OR], 1.13; 95% confidence interval [CI], 1.07-1.21; P < .001; PFDR = 0.019), whereas the percentage of IgD- CD27- B cells in lymphocytes (OR, 0.85; 95% CI, 0.79-0.92; P < .001; PFDR = 0.014), CD28 on CD39+ secreting CD4 regulatory T cells (OR, 0.92; 95% CI, 0.89-0.96; P < .001; PFDR = 0.019), and the percentage of naïve CD4+ T cells in all CD4+ T cells (OR, 0.90; 95% CI, 0.85-0.95; P < .001; PFDR = 0.027) were negatively related to the risk of Crohn disease. MR analysis of the above 4 immune cell phenotypes revealed no horizontal pleiotropy. In the reverse MR analysis, Crohn disease was not causally associated with any of these immune cell phenotypes. The findings provide insight into the relationship between immune cells and IBD pathogenesis, and may serve as a basis for developing novel immunotherapies.

Dietary quercetin intake is associated with lower ulcerative colitis risk but not Crohn's disease in a prospective cohort study and in vivo experiments

Objectives: Previous preclinical evidence indicates a protective role of quercetin against inflammatory bowel disease (IBD). However, there is no evidence from human populations, resulting in knowledge gaps regarding the role of quercetin in the IBD development. We aimed to prospectively evaluate the associations between dietary quercetin intake and IBD in humans and in vivo animal models. Methods: We included 187 709 IBD-free participants from the UK Biobank. Dietary information was collected using validated 24-hour dietary recalls and the quercetin intake was estimated based on national nutrient databases. Incident IBD was ascertained via inpatient and primary care data. Cox proportional hazard models were used to estimate the multi-variable adjusted hazard ratios (aHRs) and 95% confidence intervals (CIs). Experiments were conducted in two chemical-induced (dextran sulfate sodium salt and trinitro-benzene-sulfonic acid) mouse models orally pretreated with quercetin (CAS number: 117-39-5) solution to evaluate the effects of quercetin at physiological levels. Results: After a mean follow-up of 9.7 years, we documented 863 incident IBD. Compared to participants with the lowest quintile intake of quercetin, those in the highest quintiles were associated with a lower risk of IBD (aHR 0.76, 95% CI 0.60-0.95; P-trend = 0.004) and ulcerative colitis (aHR 0.69, 95% CI 0.53-0.91; P-trend = 0.001), but not Crohn's disease (aHR 0.95, 95% CI 0.62-1.45; P-trend = 0.765). Mouse models showed that pretreatment with quercetin could attenuate the chemically induced colitis. Conclusions: Higher quercetin intake was associated with a lower risk of IBD, especially UC. The protective role of quercetin is promising in humans and warrants further investigation into downstream mechanisms.

Integrated multi-omics analyses revealed the association between rheumatoid arthritis and colorectal cancer: MYO9A as a shared gene signature and an immune-related therapeutic target

BACKGROUND

Our study aims to explore the relationship, shared gene signature, and the underlying mechanisms that connect rheumatoid arthritis (RA) to colorectal cancer (CRC).

METHODS

Mendelian randomization (MR) analysis was conducted to assess the causality between RA and CRC. Summary statistic data-based Mendelian randomization (SMR) leveraging eQTL data was employed to identify the CRC-related causal genes. Integrated analyses of single-cell RNA sequencing and bulk RNA sequencing were employed to comprehensively investigate the shared gene signature and potential mechanisms underlying the pathogenesis of both RA and CRC. Predictive analysis of the shared hub gene in CRC immunotherapy response was performed. Pan-cancer analyses were conducted to explore the potential role of MYO9A in 33 types of human tumors.

RESULTS

MR analysis suggested that RA might be associated with a slight increased risk of CRC (Odds Ratio = 1.04, 95% Confidence Interval = 1.01-1.07, P = 0.005). SMR analysis combining transcriptome analyses identified MYO9A as a causal gene in CRC and a shared gene signature in both RA and CRC. MYO9A may contribute to tumor suppression, while downregulation of MYO9A may impact CRC tumorigenesis by disrupting epithelial polarity and architecture, resulting in a worse prognosis in CRC. Additionally, MYO9A shows promise as a powerful predictive biomarker for cancer prognosis and immunotherapy response in CRC. Pan-cancer analyses demonstrated MYO9A may have a protective role in the occurrence and progression of various human cancers.

CONCLUSION

RA might be associated with a slight increased risk of CRC. MYO9A is a shared gene signature and a potential immune-related therapeutic target for both CRC and RA. Targeting the MYO9A-mediated loss of polarity and epithelial architecture could be a novel therapeutic approach for CRC.

The effect and mechanism of Huangqin-Baishao herb pair in the treatment of dextran sulfate sodium-induced ulcerative colitis

Background

The haungqing (Scutellariae Radix) and baishao (Paeoniae Radix Alba) herb pair (HBHP) is a common prescribed herbal formula or is added to other traditional Chinese medicine (TCM) prescriptions to treat ulcerative colitis (UC). However, the underlying mechanism is unclear.

Purpose

Elucidate the efficacy and potential mechanism of HBHP against UC.

Methods

First, The UC model of mice induced by dextran sulfate sodium (DSS) was established. The mice were randomly divided into Control group, DSS group, SASP group (390 mg/kg), and HPHP group (1.95 g/kg), with 8 mice per group. Drugs were administrated via oral gavage for 7 days. Then, Disease activity index (DAI), length of the colon, histopathology, and changes in inflammatory cytokines in colonic tissues were analyzed to assess the effect of HBHP on UC. Besides, Network pharmacology was applied to identify the active compounds, core targets of HBHP in the treatment of UC, and the corresponding signaling pathways to explore the underlying mechanisms. Finally, Western blot (WB), immunohistochemistry (IHC) and molecular docking were performed to validate the results.

Results

HBHP significantly reduced DAI score and decreased colon length shortening in DSS-induced UC mice. The administration of HBHP was able to effectively alleviated mucosal ulceration and epithelial destruction. In addition, HBHP treatment obviously - reduced the expressions of TNF-α, IL-6, and IL-1β in colon tissues (p < 0.05 or p < 0.01). 35 bioactive compounds and 290 HBHP targets related to UC were obtained. Among them 3 key active compounds (baicalein, panicolin, and norwogonin) with higher degree values in the drug-compound-target network and 21 hub genes (STAT3, JAK2, SRC, AKT1, PIK3CA, and VEGFA, etc.) were identified. KEGG enrichment analysis suggested that HBHP's mechanisms mainly involve the JAK-STAT pathway. Abnormal activation of JAK/STAT signaling is believed to be involved in the pathogeneses of UC. Notably, WB and IHC showed that HBHP significantly down-regulated the protein expression levels of p-JAK2 (p < 0.05) and p-STAT3 (p < 0.05 or p < 0.01). JAK2 and STAT3 might be core targets for the action of HBHP; this possibility was also supported by molecular docking.

Conclusions

HBHP could alleviate DSS-induced UC, reduce tissue inflammation, and its mechanism might primarily be achieved by inhibiting JAK2/STAT3 signaling pathway. Meanwhile, our work revealed that network pharmacology combined with experimental verification is a cogent means of studying the mechanism of TCM.

Analysis of the interferon-γ-induced secretome of intestinal endothelial cells: putative impact on epithelial barrier dysfunction in IBD

The development of inflammatory bowel diseases (IBD) involves the breakdown of two barriers: the epithelial barrier and the gut-vascular barrier (GVB). The destabilization of each barrier can promote initiation and progression of the disease. Interestingly, first evidence is available that both barriers are communicating through secreted factors that may accordingly serve as targets for therapeutic modulation of barrier functions. Interferon (IFN)-γ is among the major pathogenesis factors in IBD and can severely impair both barriers. In order to identify factors transmitting signals from the GVB to the epithelial cell barrier, we analyzed the secretome of IFN-γ-treated human intestinal endothelial cells (HIEC). To this goal, HIEC were isolated in high purity from normal colon tissues. HIEC were either untreated or stimulated with IFN-γ (10 U/mL). After 48 h, conditioned media (CM) were harvested and subjected to comparative hyper reaction monitoring mass spectrometry (HRM™ MS). In total, 1,084 human proteins were detected in the HIEC-CM. Among these, 43 proteins were present in significantly different concentrations between the CM of IFN-γ- and control-stimulated HIEC. Several of these proteins were also differentially expressed in various murine colitis models as compared to healthy animals supporting the relevance of these proteins secreted by inflammatory activated HIEC in the inter-barrier communication in IBD. The angiocrine pathogenic impact of these differentially secreted HIEC proteins on the epithelial cell barrier and their perspectives as targets to treat IBD by modulation of trans-barrier communication is discussed in detail.