Identification of a Disease-Associated Network of Intestinal Immune Cells in Treatment-Naive Inflammatory Bowel Disease

Mediating role of chiro-inositol metabolites on the effects of HLA-DR-expressing CD14 + monocytes in inflammatory bowel disease

BACKGROUND

Inflammatory bowel disease (IBD), a chronic inflammatory condition, is caused by several factors involving aberrant immune responses. Genetic factors are crucial in IBD occurrence. Mendelian randomization (MR) can offer a new perspective in understanding IBD's genetic background.

METHODS

Single nucleotide polymorphisms (SNPs) were considered instrumental variables (IVs). We analyzed the relationship between 731 immunophenotypes, 1,400 metabolite phenotypes, and IBD. The total effect was decomposed into indirect and direct effects, and the ratio of the indirect effect to the total effect was calculated.

RESULTS

We identified the causal effects of HLA-DR-expressing CD14 + monocytes on IBD through MR analysis. The phenotype "HLA-DR expression on CD14 + monocytes" showed the strongest association among the selected 48 immune phenotypes. Chiro-inositol metabolites mediated the effect of CD14 + monocytes expressing HLA-DR on IBD. An increase in Chiro-inositol metabolites was associated with a reduced risk of IBD occurrence, accounting for 4.97%.

CONCLUSION

Our findings revealed a new pathway by which HLA-DR-expressing CD14 + monocytes indirectly reduced the risk of IBD occurrence by increasing the levels of Chiro-inositol metabolites. The results provided a new perspective on the immunoregulatory mechanisms underlying IBD, laying a theoretical foundation for developing new therapeutic targets in the future.

Causal role of immune cells in inflammatory bowel disease: A Mendelian randomization study

Inflammatory bowel disease (IBD) is characterized by an inflammatory response closely related to the immune system, but the relationship between inflammation and IBD remains unclear. We performed a comprehensive 2-sample Mendelian randomization (MR) analysis to determine the causal relationship between immune cell characteristics and IBD. Using publicly available genetic data, we explored the relationship between 731 immune cell characteristics and IBD risk. Inverse-variance weighting was the primary analytical method. To test the robustness of the results, we used the weighted median-based, MR-Egger, simple mode, and mode-based methods. Finally, we performed a reverse MR analysis to assess the possibility of reverse causality. We identified suggestive associations between 2 immune cell traits and IBD risk (P = 4.18 × 10-5 for human leukocyte antigen-DR on CD14+ monocytes, OR: 0.902; 95% CI: 0.859-0.947; for CD39+ CD4+ T cells, P = 6.24 × 10-5; OR: 1.042; 95% CI: 1.021-1.063). Sensitivity analysis results of these immune cell traits were consistent. In reverse MR analysis, we found no statistically significant association between IBD and these 2 cell traits. Our study demonstrates the close connection between immune cells and IBD using MR, providing guidance for future clinical and basic research.

Deciphering the different phases of preclinical inflammatory bowel disease

Inflammatory bowel disease (IBD) is an immune-mediated inflammatory disease (IMID) of the gastrointestinal tract and includes two subtypes: Crohn's disease and ulcerative colitis. It is well-recognized that IBD is associated with a complex multifactorial aetiology that includes genetic predisposition and environmental exposures, with downstream dysregulation of systemic immune function and host-microbial interactions in the local environment in the gut. Evidence to support the notion of a multistage development of IBD is growing, as has been observed in other IMIDs such as rheumatoid arthritis and systemic lupus erythematosus. With the rising worldwide incidence of IBD, it is increasingly important to understand the complex interplay of pathological events during the different stages of disease development to enable IBD prediction and prevention strategies. In this article, we review comprehensively the current evidence pertaining to the preclinical phase of IBD, including at-risk, initiation and expansion phases. We also discuss the framework of preclinical IBD, expanding on underlying pathways in IBD development, future research directions and IBD development in the context of other IMIDs.

Pediatric IBD patients show medication and disease activity dependent changes in NK cell and CD4 memory T cell populations

Objectives

CD4+ memory T cells facilitate long-termed adaptive immune responses while NK cells are predominately rapid effector cells with significant functions for both intestinal homeostasis and inflammation. We wanted to study both populations in health and pediatric inflammatory bowel disease (IBD) and correlate them with disease activity and medication.

Methods

We performed flow cytometric analyses of peripheral blood CD4 + CD45RO+ memory T cells and CD3-CD16 + CD56+ NK cells in 30 patients with IBD and 31 age-matched controls and correlated percentages of subsets with disease activity (PUCAI/PCDAI) and medication.

Results

We found a significant reduction of peripheral NK cells in overall IBD patients with both clinical remission and disease activity, which was even more pronounced in patients treated with azathioprine. Otherwise, circulating CD4+ memory T cell populations were significantly enhanced in active IBD compared to controls. Enhancement of memory T cells was particularly found in new onset disease and correlated with disease activity scores.

Discussion

Our single center cohort confirms previous results showing enhanced memory T cell populations in pediatric IBD patients, which correlate with disease activity scores. CD4+ memory T cells are a relevant pathogenic leukocyte population for disease development and perpetuation in IBD. In addition, we found a decrease of NK cells in IBD patients, which was pronounced by use of azathioprine. Surveillance of both cellular populations could possibly serve as biomarker for therapy control in pediatric IBD.

The role and mechanism of flavonoid herbal natural products in ulcerative colitis

Ulcerative colitis (UC) is a chronic inflammatory disease of the intestine that presents clinically with abdominal pain, mucopurulent stools, and posterior urgency. The lesions of UC are mainly concentrated in the rectal and colonic mucosa and submucosa. For patients with mild to moderate UC, the best pharmacological treatment includes glucocorticoids, immunosuppressants, antibiotics, and biologics, but the long-term application can have serious toxic side effects. Currently, nearly 40% of UC patients are treated with herbal natural products in combination with traditional medications to reduce the incidence of toxic side effects. Flavonoid herbal natural products are the most widely distributed polyphenols in plants and fruits, which have certain antioxidant and anti-inflammatory activities. Flavonoid herbal natural products have achieved remarkable efficacy in the treatment of UC. The pharmacological mechanisms are related to anti-inflammation, promotion of mucosal healing, maintenance of intestinal immune homeostasis, and regulation of intestinal flora. In this paper, we summarize the flavonoid components of anti-ulcerative colitis and their mechanisms reported in the past 10 years, to provide a basis for rational clinical use and the development of new anti-ulcerative colitis drugs.

Revealing immune infiltrate characteristics and potential diagnostic value of immune-related genes in ulcerative colitis: An integrative genomic analysis

Objectives

Ulcerative colitis (UC) is an autoimmune disease of the colon. The aim of this study was to explore the characteristics of immune infiltrates in UC patients and identify immune-related diagnostic biomarkers for UC.

Methods

Three gene expression profiles were acquired from the GEO database, followed by identification of differentially expressed genes (DEGs) by Linear Modeling of Microarray Data. Enrichment analysis of Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG) and Disease Ontology (DO) were performed to analyze the biological functions of DEGs. Subsequently, the single sample gene set enrichment analysis (ssGSEA) was performed to identify immune infiltration characteristics of UC. Correlations between diagnostic genes and immune infiltration were explored to identify markers with the greatest diagnostic potential, and a UC diagnostic model was subsequently constructed. Finally, the prediction performance of the model was quantified by nomogram, non-correlated nomogram, and ROC curve.

Results

A total of 3111 DEGs (1,608 up-regulated and 1,503 down-regulated genes) were identified. DEGs were significantly involved in the immune system and UC-related pathways. Immune infiltration profiles of colonic tissue were significantly different between healthy individuals and UC patients. High proportions of resting of aDCs, B cells, CD8⁺ T cells, DCs, iDCs, Macrophages, Neutrophils, pDCs, T helper cells, Tfh, Th1 cells, Th2 cells, TIL and Treg were found in UC samples. A 5-gene based diagnostic prediction model was constructed and the results of nomogram, non-correlated nomogram and ROC curve suggested the powerful diagnostic value of the model.

Conclusions

This study identified the immune infiltrate characteristics and 5 immune-related genes for UC. The model based on the immune-related genes facilitates the early diagnosis of UC and provides a basis for the evaluation of the prognosis of UC.

(Not) Home alone: Antigen presenting cell - T Cell communication in barrier tissues

Priming of T cells by antigen presenting cells (APCs) is essential for T cell fate decisions, enabling T cells to migrate to specific tissues to exert their effector functions. Previously, these interactions were mainly explored using blood-derived cells or animal models. With great advances in single cell RNA-sequencing techniques enabling analysis of tissue-derived cells, it has become clear that subsets of APCs are responsible for priming and modulating heterogeneous T cell effector responses in different tissues. This composition of APCs and T cells in tissues is essential for maintaining homeostasis and is known to be skewed in infection and inflammation, leading to pathological T cell responses. This review highlights the commonalities and differences of T cell priming and subsequent effector function in multiple barrier tissues such as the skin, intestine and female reproductive tract. Further, we provide an overview of how this process is altered during tissue-specific infections which are known to cause chronic inflammation and how this knowledge could be harnessed to modify T cell responses in barrier tissue.