Differential alleviation of DSS-induced colitis in mice by black tea extracts of different origins via enhancing gut barrier and gut microbiota modulation

Black tea is commonly used for tea beverage production and has been shown to be an effective natural ingredient to prevent experimentally induced colitis. However, there is limited evidence to show whether black teas of different origins demonstrate similar anti-inflammatory capacity in colitic mice. In this study, mice were daily administered with black tea extracts of lapsang, keemun or dianhong for 1 week prior to receiving 4% dextran sulfate sodium for inducing colitis. Both the lapsang and keemun extracts exhibited better anti-inflammatory effects than dianhong extract, as evidenced by the former two tea extracts that enhanced intestinal barrier functions (up-regulation of MUC2 and ZO-1 and increased population of goblet cells), and decreased colonic and serum pro-inflammatory cytokines. We deduced that GC might be a key contributor to the anti-colitis effects of black tea, potentially through synergistic interactions with other components at an optimal ratio to enhance anti-inflammatory efficacy. Fecal microbiome analysis showed that gut microbiome was differentially modulated by lapsang and keemun extracts. Their anti-colitic effects were dependent on gut microbiome as shown by the loss of such protection in DSS mice treated with broad-spectrum antibiotics (ABX) for significant microbiome alterations. Mechanistically, colonic transcriptomic analysis showed the differential impact of lapsang and keemun extracts on colitis via modulating gene expressions of IL-17 pathway and glutamatergic synapse, respectively. Further qPCR and immunohistochemistry assays verified aforementioned pathway modulation. Together, our study provided a roadmap for understanding the effects of different black tea types on colitis and for providing potential directions on nutritional modulation of colitis.