Targeting ICAM1- driven immune dysfunction in ulcerative colitis: Integrative evidence from in-vivo and in-silico studies

Background: Ulcerative colitis is chronic inflammatory bowel disease defined by aberrant immune response and recurrent intestinal mucosal inflammation. Anti-inflammatory and antioxidant sesquiterpene alpha-cubebene is thought to ameliorate UC pathogenesis via down-regulation of ICAM1 expression, inhibition of NFκB and MAPK-mediated inflammatory pathways. Objectives: To investigate ICAM1 as a biomarker and therapeutic target for cell adhesion and leukocyte migration, and to explore alpha-cubebene as a potential ICAM1 inhibitor for the first time. Methods: ICAM1 structure was retrieved from RCSB PDB database and docked by CB-dock2. ADMET and drud likeness analysis of alpha-cubebene were evaluated by SwissADME, pkCSM and Deep-PK softwares. Stereochemistry of ICAM1 was assessed through Ramachandran plot and hydrophobicity analysis. Protein-protein interaction was established by STRING analysis and Gene Ontology (GO) followed by MD simulation. For in-vivo validation, Ulcerative colitis was induced in 30 male Albino Wistar rats using 2% DSS administered orally for four weeks, randomized into six groups (n = 5/group) and then treated with different concentrations of α-cubebene and Mesalamine for one month. Therapeutic efficacy was evaluated by assessing disease activity and experimental parameters and histopathological analysis. Results: Molecular docking and MD simulation of ICAM1 and alpha-cubebene revealed Vina score of -6.1kcal/mol showing it a stable protein. Network pharmacology, protein-protein interactions, STRING and GO enrichment analysis revealed therapeutic targeting of ICAM1 interactions can be a potential therapeutic approach for alleviating UC. In in-vivo studies, DSS administration significantly increased the disease activity score compared with normal control (P = 0.001), while α-cubebene treatment markedly and dose-dependently attenuated disease severity. The highest α-cubebene dose (100 µL, 10 mg/kg/day) restored the disease activity score of ICAM1 towards normal and demonstrated greater therapeutic efficacy than Mesalamine. Histopathological results further confirmed it. Conclusion: Alpha-cubebene could serve as an effective candidate for phytotherapy of UC via specifically affecting inflammatory response mediated by ICAM1.