This study aimed to investigate the dose-response effect of Bifidobacterium breve CCFM683 on relieving psoriasis and its underlying patterns. Specifically, the expression of keratin 16, keratin 17, and involucrin were substantially decreased by administration of 109 CFU and 1010 CFU per day. Moreover, interleukin (IL)-17 and TNF-α levels were substantially decreased by 109 and 1010 CFU/day. Furthermore, the gut microbiota in mice treated with 109 or 1010 CFU/day was rebalanced by improving the diversity, regulating microbe interactions, increasing Lachnoclostridium, and decreasing Oscillibacter. Moreover, the concentrations of colonic bile acids were positively correlated with the effectiveness of the strain in relieving psoriasis. The gavage dose should be more than 108.42 CFU/day to improve psoriasis according to the dose-effect curve. In conclusion, CCFM683 supplementation alleviated psoriasis in a dose-dependent manner by recovering microbiota, promoting bile acid production, regulating the FXR/NF-κB pathway, diminishing proinflammatory cytokines, regulating keratinocytes, and maintaining the epidermal barrier function. These results may help guide probiotic product development and clinical trials in psoriasis.
Keywords: Bifidobacterium breve; FXR/NF-κB pathway; bile acids; dose–response efficacy; gut microbiota; psoriasis.