#18 Chromofungin Is A Novel Potential Therapeutic Target For Inflammatory Bowel Disease
Nour Eissa, University of Manitoba; Laëtitia Kermarrec, University of Manitoba; Omar Elgazzar, University of Manitoba; Charles N Bernstein, University of Manitoba; Jean-Eric Ghia, University of Manitoba
Chromogranin-A (CHGA) is secreted by neuroendocrine cells and is a precursor of several bioactive peptides including chromofungin (CHR: CHGA47-66), which 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 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 active ulcerative colitis (UC) patients and the underlying mechanisms in dextran sulfate sodium (DSS)-colitis in regard to macrophages activation and migration.
Expression of Exon-IV and its correlation with classically activated macrophages (CAMs) markers (IL1B, IL6, TNFA, SLAM7, TLR4, CD120B), and NFKB were determined in human colonic tissues. Colitis was induced in C57BL/6 mice by administration of DSS (5%, 5 days). Preventive CHR (2.5 mg/kg/day) treatment or vehicle started 1-day before colitis induction and lasted for 5-days. Disease severity and colonic CAMs markers were evaluated. CHR (200ng/ml) treated naïve peritoneal macrophages were exposed for 6 h to LPS (100ng/ml) and CAMs markers were quantified. Moreover, phosphorylated-NF-κB levels were quantified in mice colonic mucosa and CAMs using Western Blot. In vitro chemotaxis activity of CHR (200ng/ml) on naïve macrophages were assessed by transwell migration assay.
mRNA expression of CHR-(CHGA Exon-IV) was down regulated in active UC compared to healthy individuals and negatively correlated with CAMs markers, 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 CAMs markers and pNF-κB. In vitro, CHR treatment reduced macrophages migration, decreased pro-inflammatory cytokines production and pNF-κB.
CHR protects against colitis via by decreasing CAMs and NF-κB activation. Targeting CHR may represent a promising new direction in research to define new therapeutic targets and biomarkers associated with IBD.