Thalidomide Attenuates Colitis and Is Associated with the Suppression of M1 Macrophage Polarization by Targeting the Transcription Factor IRF5

Overcoming cancer risk in inflammatory bowel disease: new insights into preventive strategies and pathogenesis mechanisms including interactions of immune cells, cancer signaling pathways, and gut microbiota

Inflammatory bowel disease (IBD), characterized primarily by gastrointestinal inflammation, predominantly manifests as Crohn's disease (CD) and ulcerative colitis (UC). It is acknowledged that Inflammation plays a significant role in cancer development and patients with IBD have an increased risk of various cancers. The progression from inflammation to carcinogenesis in IBD is a result of the interplay between immune cells, gut microbiota, and carcinogenic signaling pathways in epithelial cells. Long-term chronic inflammation can lead to the accumulation of mutations in epithelial cells and the abnormal activation of carcinogenic signaling pathways. Furthermore, Immune cells play a pivotal role in both the acute and chronic phases of IBD, contributing to the transformation from inflammation to tumorigenesis. And patients with IBD frequently exhibit dysbiosis of the intestinal microbiome. Disruption of the gut microbiota and subsequent immune dysregulation are central to the pathogenesis of both IBD and colitis associated colorectal cancer (CAC). The proactive management of inflammation combined with regular endoscopic and tumor screenings represents the most direct and effective strategy to prevent the IBD-associated cancer.

Hsa_circRNA_103124 upregulation in Crohn's disease promoted macrophage M1 polarization to maintain an inflammatory microenvironment via activation of the AKT2 and TLR4/NF-κB pathways

An accumulating body of research indicates that circular RNAs participate in the pathogenesis of Crohn's disease (CD). Hsa_circRNA_103124, which was upregulated in the peripheral blood mononuclear cells of patients with CD, was reported to inhibit autophagy in our previous studies. However, how hsa_circRNA_103124 participates in CD progression remains unclear. In this study, TLR4 was found to be upregulated in THP1 cells overexpressing hsa_circRNA_103124. Bioinformatic analysis indicated that overexpressed hsa_circRNA_103124 was associated with the PI3K/AKT signaling pathway and TLR4-associated innate immunity in inflammatory bowel disease. Therefore, we inferred a possible role for hsa_circRNA_103124 in macrophage polarization. Hsa_circRNA_103124, AKT2 and TLR4 were significantly upregulated in the PBMCs of patients with CD. Further analysis revealed a positive correlation between hsa_circRNA_103124 and AKT2 (r = 0.8029, p < 0.0001), TLR4 (r = 0.2529, p = 0.0089) and the Crohn's disease activity index (r = 0.4535, p < 0.0001) in patients with CD. Notably, hsa_circRNA_103124 promoted macrophage M1 polarization with increased expression of CD80 and CD86, while it inhibited macrophage M2 polarization with decreased expression of CD206 and CD163. Hsa_circRNA_103124 promoted an inflammatory microenvironment by activating the AKT2 and TLR4/NF-κB signaling pathways in M1 polarized THP1 cells. Nevertheless, hsa-miR-650 reversed the role of hsa_circRNA_103124 in M1 polarization. Hsa_circRNA_103124 promoted the formation of neutrophil extracellular traps and reduced the expression of ZO-1. In summary, the results of this study indicated that hsa_circRNA_103124 promoted macrophage M1 polarization to maintain an inflammatory microenvironment via activation of the TLR4/NF-κB pathway in a hsa-miR-650/AKT2 dependent manner. Hsa_circRNA_103124 could serve as a potential biomarker and a novel therapeutic target in CD progression.

Update and latest advances in mechanisms and management of colitis-associated colorectal cancer

Colitis-associated colorectal cancer (CAC) is defined as a specific cluster of colorectal cancers that develop as a result of prolonged colitis in patients with inflammatory bowel disease (IBD). Patients with IBD, including ulcerative colitis and Crohn's disease, are known to have an increased risk of developing CAC. Although the incidence of CAC has significantly decreased over the past few decades, individuals with CAC have increased mortality compared to individuals with sporadic colorectal cancer, and the incidence of CAC increases with duration. Chronic inflammation is generally recognized as a major contributor to the pathogenesis of CAC. CAC has been shown to progress from colitis to dysplasia and finally to carcinoma. Accumulating evidence suggests that multiple immune-mediated pathways, DNA damage pathways, and pathogens are involved in the pathogenesis of CAC. Over the past decade, there has been an increasing effort to develop clinical approaches that could help improve outcomes for CAC patients. Colonoscopic surveillance plays an important role in reducing the risk of advanced and interval cancers. It is generally recommended that CAC patients undergo endoscopic removal or colectomy. This review summarizes the current understanding of CAC, particularly its epidemiology, mechanisms, and management. It focuses on the mechanisms that contribute to the development of CAC, covering advances in genomics, immunology, and the microbiome; presents evidence for management strategies, including endoscopy and colectomy; and discusses new strategies to interfere with the process and development of CAC. These scientific findings will pave the way for the management of CAC in the near future.

The Role of Tissue-Resident Macrophages in the Development and Treatment of Inflammatory Bowel Disease

Inflammatory bowel disease (IBD), comprising Crohn’s disease and ulcerative colitis, is a refractory disease with many immune abnormalities and pathologies in the gastrointestinal tract. Because macrophages can distinguish innocuous antigens from potential pathogens to maintain mucosa barrier functions, they are essential cells in the intestinal immune system. With numerous numbers in the intestinal tract, tissue-resident macrophages have a significant effect on the constant regeneration of intestinal epithelial cells and maintaining the immune homeostasis of the intestinal mucosa. They also have a significant influence on IBD through regulating pro-(M1) or anti-inflammatory (M2) phenotype polarization according to different environmental cues. The disequilibrium of the phenotypes and functions of macrophages, disturbed by intracellular or extracellular stimuli, influences the progression of disease. Further investigation of macrophages’ role in the progression of IBD will facilitate deciphering the pathogenesis of disease and exploring novel targets to develop novel medications. In this review, we shed light on the origin and maintenance of intestinal macrophages, as well as the role of macrophages in the occurrence and development of IBD. In addition, we summarize the interaction between gut microbiota and intestinal macrophages, and the role of the macrophage-derived exosome. Furthermore, we discuss the molecular and cellular mechanisms participating in the polarization and functions of gut macrophages, the potential targeted strategies, and current clinical trials for IBD.

YAP Activates STAT3 Signalling to Promote Colonic Epithelial Cell Proliferation in DSS-Induced Colitis and Colitis Associated Cancer

BACKGROUND AND AIMS

Yes-associated protein (YAP) is a key transcriptional coactivator of cell proliferation and differentiation. In this study, we sought to identify the roles of YAP in colonic epithelial regeneration and tumourigenesis.

METHODS

Murine DSS-induced colitis and YAP overexpression models were constructed via lentiviral intraperitoneal injection. Stable YAP-overexpressing cells, protein immunoprecipitation, and ChIP were used to deeply explore the molecular mechanism.

RESULTS

We found that the expression of YAP was dramatically diminished in the colonic crypts during the acute colitis phase, while YAP was strikingly enhanced to initiate tissue repair after DSS withdrawal. Overexpressing YAP in mice drastically accelerated epithelial regeneration, presenting with more intact structural integrity and reduced inflammatory cell infiltration in the mucosa. Further mechanistic studies showed that the expression of YAP in the nucleus was significantly increased by 2 h post-DSS removal, accompanied by upregulated protein levels of activated STAT3. Overexpression of YAP (YAP^WT) elevated the expression of activated STAT3 and its transcriptional targets and strengthened the proliferation and "wound healing" ability of colonic cells. However, these effects were reversed when STAT3 was silenced in YAP^WT cells. Moreover, YAP could directly interact with STAT3 in the nucleus, and c-Myc and CyclinD1 were the transcriptional targets. Finally, during colitis-associated cancer (CAC), YAP^WT promoted the progression of CAC, while the phosphomimetic YAP downregulated the expression of STAT3 and inhibited the development and progression of CAC.

CONCLUSION

YAP activates STAT3 signalling to facilitate mucosal regeneration after DSS-induced colitis. However, excessive YAP activation in the colonic epithelium promotes CAC development.

Chemokines and chemokine receptors in inflammatory bowel disease: Recent findings and future perspectives

Despite the benefits of current therapeutic options for treating inflammatory bowel disease (IBD), there are still patients who are refractory to these therapies. Moreover, the relapses caused by incomplete intestinal mucosa healing are frequent. Therefore, there is a need for novel pharmacological targets that can improve the existing IBD therapeutic armamentarium. Chemokine and chemokine receptors have emerged as appealing options to this end. As well as controlling leukocyte trafficking to inflamed tissues, these proteins regulate many other processes related to the development of intestinal inflammation. In this review, we summarise the most recent preclinical studies, along with the putative application of chemokine-based therapies in patients with IBD.