Dysregulated Up-Frameshift Protein 1 Promotes Ulcerative Colitis Pathogenesis Through the TNFR1-NF-κB/MAPKs Pathway

Nuclear Factor Kappa B Signaling Complexes in Acute Inflammation

Significance: Nuclear factor kappa B (NF-κB) is a master regulator of the inflammatory response and represents a key regulatory node in the complex inflammatory signaling network. In addition, selective NF-κB transcriptional activity on specific target genes occurs through the control of redox-sensitive NF-κB interactions. Recent Advances: The selective NF-κB response is mediated by redox-modulated NF-κB complexes with ribosomal protein S3 (RPS3), Pirin (PIR). cAMP response element-binding (CREB)-binding protein (CBP)/p300, peroxisome proliferator-activated receptor gamma coactivator 1 alpha (PGC-1α), activator protein-1 (AP-1), signal transducer and activator of transcription 3 (STAT3), early growth response protein 1 (EGR-1), and SP-1. NF-κB is cooperatively coactivated with AP-1, STAT3, EGR-1, and SP-1 during the inflammatory process, whereas NF-κB complexes with CBP/p300 and PGC-1α regulate the expression of antioxidant genes. PGC-1α may act as selective repressor of phospho-p65 toward interleukin-6 (IL-6) in acute inflammation. p65 and nuclear factor erythroid 2-related factor 2 (NRF2) compete for binding to coactivator CBP/p300 playing opposite roles in the regulation of inflammatory genes. S-nitrosylation or tyrosine nitration favors the recruitment of specific NF-κB subunits to κB sites. Critical Issues: NF-κB is a redox-sensitive transcription factor that forms specific signaling complexes to regulate selectively the expression of target genes in acute inflammation. Protein-protein interactions with coregulatory proteins, other transcription factors, and chromatin-remodeling proteins provide transcriptional specificity to NF-κB. Furthermore, different NF-κB subunits may form distinct redox-sensitive homo- and heterodimers with distinct affinities for κB sites. Future Directions: Further research is required to elucidate the whole NF-κB interactome to fully characterize the complex NF-κB signaling network in redox signaling, inflammation, and cancer.

PTPRO exaggerates inflammation in ulcerative colitis through TLR4/NF-κB pathway

Previous studies have implicated protein tyrosine phosphatase receptor type O (PTPRO) as a key regulator in inflammation-associated diseases; however, its role in ulcerative colitis (UC) remains largely unknown. Thus, we aim to elucidate the potential role and underlying mechanism of PTPRO in UC. In this study, increased expression of PTPRO, toll-like receptor (TLR4) and inflammatory cytokines were observed in mucosal tissues (MTs) from inflamed areas and lamina propria mononuclear cells (LPMCs) of patients with UC compared with those from healthy controls. Then, it was manifested that PTPRO promoted the expression of TLR4 and proinflammatory cytokines in lipopolysaccharide-induced (LPS-induced) inflammatory macrophage model. Besides, PTPRO inhibited the proliferation of intestinal epithelial cells (IECs) but enhanced the apoptosis of IECs in macrophages. Moreover, levels of phosphorylated nuclear factor κB (NF-κB)/p65 and inhibitor of NF-κB α (IκBα) were more significantly increased in PTPRO overexpressed macrophages. In addition, the area under receiver operating characteristic curve was 0.807 (95%CI = 0.686-0.958, P < .001) suggesting PTPRO as an ideal diagnostic marker for UC. Taken these, the present study shows strong evidence that PTPRO exaggerates inflammation in UC via TLR4/NF-κB signaling pathway.

The protective effect of nigeglanine on dextran sulfate sodium-induced experimental colitis in mice and Caco-2 cells

Ulcerative colitis (UC) was a nonspecific inflammatory disease. The treatment of UC is imperative. The present study aimed to investigate the effect of nigeglanine on dextran sulfate sodium-induced UC in experimental mice and Caco-2 cells and define the underlying mechanism. The nigeglanine was shown a significant protective effect on the colon, significantly reduced the weight and colon length loss and inhibited intestinal epithelial cell damage. Nigeglanine also reduced proinflammatory factors and increased anti-inflammatory factor production. The results indicate that nigeglanine suppresses the nuclear factor kappa B and mitogen-activated protein kinases pathways in addition to NLRP3 inflammasome action, inhibiting colon epithelial cell pyroptosis. Surprisingly, ZO-1 and occludin protein levels increased with nigeglanine treatment, suggesting that nigeglanine plays a protective role in barrier integrity, reducing colitis progression. The present study suggests that dietary therapy with nigeglanine may be a useful treatment for prophylaxis and palliative UC.