According to traditional Chinese medicine (TCM) constitutional theory, individuals with phlegm-dampness constitution (PDC) are at increased risk for metabolic disorders. Previous studies have indicated that PDC individuals exhibit gene expression changes associated with metabolic disorders, even individuals with normal metabolic indices. However, the biological mechanisms underlying these changes remain unclear. The gut microbiota has recently emerged as a promising avenue for elucidating TCM principles. Here, we revealed that individuals with PDC have distinct gut microbiota and serum metabolite profiles. A decrease in phytosphingosine was associated with increased PDC scores and metabolic disorder severity. Subsequent experiments demonstrated that Flavonifractor plautii can biosynthesize phytosphingosine, which was also negatively correlated with the PDC score. Interestingly, both F. plautii and phytosphingosine levels decreased in PDC subjects with normal metabolic indices. Fecal transplantation from these individuals accelerated the development of metabolic disorders in mice. However, supplementation with F. plautii and phytosphingosine ameliorated metabolic disorders by increasing phytosphingosine levels in the gut‒hepatic axis. Mechanistic investigations confirmed that phytosphingosine can directly bind to hepatic peroxisome proliferator-activated receptor α (PPARα) and activate its nuclear transcription activity, thereby regulating downstream gene expression related to glucose‒lipid metabolism. Our research indicates that the decrease in F. plautii and its product, phytosphingosine, contributes to gene expression changes related to metabolic disorders in PDC individuals and increases their susceptibility to metabolic disorders. These findings suggest that diagnosing PDC may be beneficial for identifying at-risk populations among apparently healthy individuals, thereby advancing the broader field of metabolic disorder prevention and TCM integration.
Inflammatory bowel disease is becoming increasingly prevalent and represents a major concern in global public health. However, conventional therapies often come with various adverse effects. Phytosphingosine (PS), a key metabolite in sphingolipid metabolism, is widely found in plants and fungi and possesses notable anti-inflammatory properties. In this study, we aimed to evaluate the protective effects of PS against dextran sulfate sodium (DSS)-induced experimental colitis in mice and elucidate its underlying mechanisms. Our results showed that oral administration of PS significantly alleviated DSS-induced colonic injury and reduced levels of proinflammatory cytokines such as TNF-α and IL-1β. Additionally, PS improved intestinal barrier function disrupted by DSS, as indicated by increased expression of mucin-2 and tight junction proteins. Furthermore, PS suppressed the activation of the NF-κB signaling pathway, oxidative stress and enhanced PPARγ expression. We also observed that PS mitigated DSS-induced gut dysbiosis in mice, characterized by an increase in Bacteroidota and a decrease in Proteobacteria . To explore the role of the gut microbiota in PS-mediated protection against colitis, fecal microbiota transplantation (FMT) was conducted in DSS-treated mice. Recipients of FMT from PS-treated donors exhibited reduced inflammatory responses and improved intestinal integrity, accompanied by a higher abundance of Bacteroidota in the gut. Additionally, PS treatment modified the profile of short-chain fatty acids in the mice, with a notable increase in the levels of butyrate and propionate. Overall, our findings demonstrate that PS attenuates DSS-induced colitis in mice through modulation of the gut microbiota, providing a potential strategy for IBD intervention via microbiota regulation.
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