Chromofungin

Chromogranin-A (CHGA) is a prohormone secreted by neuroendocrine cells and is a precursor of several bioactive peptides, which are implicated in different and distinctive biological and immune functions. Chromofungin (CHR: CHGA47-66) is a short peptide with antimicrobial effects and encodes from CHGA exon-IV. Inflammatory bowel disease (IBD) is characterized by alterations in the activation of pro-inflammatory pathways, pro-inflammatory macrophages (M1), and nuclear transcription factor kappa B (NF-κB) signaling leading to the perpetuation of the inflammatory process. Here, we investigated the activity of CHR (CHGA Exon-IV) in persons with active ulcerative colitis (UC) and the underlying mechanisms in dextran sulfate sodium (DSS)-colitis in regard to macrophages activation and migration. Tissue mRNA expression of CHR (CHGA Exon-IV) was down regulated in active UC compared to healthy individuals and negatively correlated with pro-inflammatory macrophages (M1) cytokines, toll-like receptors (TLR)-4, and pNF-κB activity. In DSS colitis, CHR (CHGA Exon-IV) expression was reduced, and exogenous CHR treatment decreased the severity of colitis associated with a reduction of M1 macrophages markers and pNF-κB. In vitro, CHR treatment reduced macrophages migration, decreased pro-inflammatory cytokines production and pNF-κB. Targeting CHR may represent a promising new direction in research to define new therapeutic targets and biomarkers associated with IBD.

Background: Chromofungin (CHR: chromogranin-A 47-66) is a chromogranin-A derived peptide with anti-inflammatory and anti-microbial properties. Ulcerative colitis (UC) is characterized by a colonic decrease of CHR and a dysregulation of dendritic CD11c+ cells. Aim: To investigate the association between CHR treatment and dendritic cells (DCs)-related markers in different immune compartments in colitis. Methods: A model of acute UC-like colitis using dextran sulphate sodium (DSS) was used in addition to biopsies collected from UC patients. Results: Intrarectal CHR treatment reduced the severity of DSS-induced colitis and was associated with a significant decrease in the expression of CD11c, CD40, CD80, CD86 and interleukin (IL)-12p40 in the inflamed colonic mucosa and CD11c, CD80, CD86 IL-6 and IL-12p40 within the mesenteric lymph nodes and the spleen. Furthermore, CHR treatment decreased CD80 and CD86 expression markers of splenic CD11c+ cells and decreased NF-κB expression in the colon and of splenic CD11c+ cells. In vitro, CHR decreased CD40, CD80, CD86 IL-6 and IL-12p40 expression in naïve bone marrow-derived CD11c+ DCs stimulated with lipopolysaccharide. Pharmacological studies demonstrated an impact of CHR on the NF-κB pathway. In patients with active UC, CHR level was reduced and showed a negative linear relationship with CD11c and CD86. Conclusion: CHR has protective properties against intestinal inflammation via the regulation of DC-related markers and CD11c+ cells. CHR could be a potential therapy of UC.

Ulcerative colitis (UC) is characterized by a functional dysregulation of alternatively activated macrophage (AAM) and intestinal epithelial cells (IECs) homeostasis. Chromogranin-A (CHGA) secreted by neuroendocrine cells is implicated in intestinal inflammation and immune dysregulation. CHGA undergoes proteolytic processing to generate CHGA-derived peptides. Chromofungin (CHR: CHGA47-66) is a short CHGA-derived peptide encoded by CHGA Exon-IV and is involved in innate immune regulation, but the basis is poorly investigated. We investigated the expression of CHR in colonic tissue of patients with active UC and assessed the effects of the CHR in dextran sulfate sodium (DSS) colitis in mice and on macrophages and human colonic epithelial cells. We found that mRNA expression of CHR correlated positively with mRNA levels of AAM markers and gene expression of tight junction (TJ) proteins and negatively with mRNA levels of interleukin (IL)-8, IL-18, and collagen in patients with active UC. Moreover, AAM markers correlated positively with gene expression of TJ proteins and negatively with IL-8, IL-18, and collagen gene expression. Experimentally, intracolonic administration of CHR protected against DSS-induced colitis by priming macrophages into AAM, reducing colonic collagen deposition, and maintaining IECs homeostasis. This effect was associated with a significant increase of AAM markers, reduction of colonic IL-18 release and conservation of gene expression of TJ proteins. In vitro, CHR enhanced AAM polarization and increased the production of anti-inflammatory mediators. CHR-treated AAM conditioned medium increased Caco-2 cell migration, viability, proliferation, and mRNA levels of TJ proteins, and decreased oxidative stress-induced apoptosis and proinflammatory cytokines release. Direct CHR treatments had the same effect. In conclusion, CHR treatment reduces the severity of colitis and the inflammatory process via enhancing AAM functions and maintaining IECs homeostasis. CHR is involved in the pathogenesis of inflammation in experimental colitis. These findings provide insight into the mechanisms of colonic inflammation and could lead to new therapeutic strategies for UC.