Immunomodulatory effect of Qihuang Biwen decoction and its postbiotic product

Microbial fermentation is a promising strategy to enhance the efficacy and functional properties of herbs. A traditional Chinese medicine formula, known as the Qihuang Biwen decoction (QHBW), has been shown to have immunomodulatory benefits in clinical and experimental studies. Nevertheless, few studies have investigated the effects of microbial-fermented QHBW (FQHBW) on immunity. In this study, we used one-way and Plackett-Burman analyses to establish the preparation process of FQHBW (crucial parameters: ratio of bacterial strains LZU-J-TSL6 and LZU-S-ZCJ was 3:1, inoculum quantity was 3%, temperature was 37℃, time was 37 h). The study found that FQHBW has increased total polysaccharide, total acid, and antioxidant capacities. The increased constituents after fermentation potentially contribute to improving the ability of FQHBW to regulate immunity. Next, its immunostimulatory activity was evaluated in cyclophosphamide (CTX)-treated mice, and the possible mechanism was studied by microbiome-metabolome analysis. As expected, FQHBW effectively ameliorated CTX-induced immunosuppression by improving organ index, lymphocyte proliferation, phagocytic function, cytokine secretion, and antioxidant profile. It protected against CTX-induced intestinal dysbiosis by promoting the abundance of Oscillospira, Allobaculum, and Coprococcus, while moderately increasing Akkermansia and reducing Staphylococcus and Streptococcus. FQHBW primarily influenced amino acid and nucleotide metabolism to benefit immunity. Unlike QHBW, FQHBW uniquely up-regulates dopamine synapses, tryptophan metabolism, and nicotinate and nicotinamide metabolism, promoting host anti-oxidation, immune system remodeling, and disease resistance. This study suggests that microbial fermentation is indeed an effective strategy to alter the properties and function of QHBW. FQHBW has the potential to replace QHBW as a novel immunoenhancer and intestinal microecological regulator.