Effects of Spirulina phycocyanin on Caco-2 cell injury and ulcerative colitis in mice

Inflammatory bowel disease (IBD) is global chronical colonic phlogosis closely related to immunity system dysfunction. IBD includes Crohn's disease (CD) and ulcerative colitis (UC). However, the current treatments for UC still have significant limitations such as insufficient efficacy, obvious side effects and large individual differences. As a natural pigment protein extracted from dry Spirulina platensis powder, phycocyanin (PC) attracted wide focus due to significant antioxidant and anti-inflammatory abilities. However, the role and value of PC in treatment of UC have not been fully studied. This paper aimed to elucidate the effects of Spirulina PC on UC from multiple aspects. This paper revealed that PC treatment could alleviate consequences of colonitis (intestinal mucosal atrophy, loss of weight, the increase in organ indices). After PC treatment, the contents of proinflammatory factors including interleukin-1β (IL-1β), tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) reduced and the contents of anti-inflammatory factor interleukin-10 (IL-10) increased in colitis mice. Oxidative stress was regulated by PC. After PC treatment, enzyme activities of catalase (CAT), total superoxide dismutase (T-SOD) and glutathione peroxidase (GSH-Px) increased apparently, levels of myeloperoxidase (MPO) and malondialdehyde (MDA) reduced significantly in colitis mice. PC elevated levels of tight junction proteins including Occludin, zona occludens-1 (ZO-1), Claudin-1, and played positive role to keep integrity of mouse colonic mucosa. Microbial composition and metabolites analysis of colonic contents revealed that PC improved ratio of beneficent germs and reduced ratio of harmful germs in colitis mice. The contents of beneficial metabolites increased in colitis mice, these beneficial metabolites involved in metabolism of amino acids, lipids, carbohydrates, nucleotides and secondary metabolites. This study suggested that PC had great potential to prevent and alleviate UC as dietary supplement.