Painong-San extract alleviates dextran sulfate sodium-induced colitis in mice by modulating gut microbiota, restoring intestinal barrier function and attenuating TLR4/NF-κB signaling cascades.

The intestinal barrier dysfunction and the gut microbiota dysbiosis with excessive progress of inflammation contribute to the occurrence and acceleration of ulcerative colitis (UC). Painong Powder, a traditional Chinese medicine prescription, consists of Aurantii Fructus Immaturus, Paeoniae Radix Alba and Platycodonis Radix, which has been found to defend against colitis, but it is unclear whether its role in preventing UC is related to gut microbiota. This study aims to evaluate the effects of Painong-San extract (PNS) on UC and reveals the mechanisms related to gut microbiota. Firstly, a total of 125 chemical compounds, including 42 flavonoids, 29 triterpenoids, 21 monoterpenoids, 11 polyphenols, 6 limonoids, 5 alkaloids, 4 coumarins and 7 other compounds, were identified from PNS using ultra-performance liquid chromatography-quadrupole time-of-flight mass spectrometry. Then, the results in vivo studies demonstrated that PNS treatment reduced the weight loss and the disease activity index, prevented colon shortening and alleviated colonic tissue damage in dextran sulfate sodium (DSS)-induced colitis mice. The intestinal barrier damage was repaired after PNS administration through promoting the expression of tight junction proteins (claudin-1, occludin and zonula occludens-1). More interestingly, PNS regulated gut microbiota dysbiosis, suppressed the overgrowth of conditional pathogenic gut bacteria, such as Oscillospiraceae and Helicobacter, while the probiotic gut microbiota like Romboutsia, Lactobacillus, Bifidobacterium and Akkermansia were increased. Furthermore, PNS remarkably ameliorated colonic inflammatory response through inhibiting intestinal TLR4/NF-κB signaling pathway by down-regulating the protein expressions of TLR4, MyD88, p-NF-κB p65 and p-IκBα. Taken together, PNS effectively improved DSS-induced colitis through the modulation of gut microbiota, restoration of intestinal barrier function and attenuation of TLR4/NF-κB signaling cascades, which may provide a new explanation of the mechanisms of PNS against UC.

Wang K ，Guo J ，Chang X ，Gui S ... -  《-》

Glycyrrhiza uralensis Fisch. alleviates dextran sulfate sodium-induced colitis in mice through inhibiting of NF-κB signaling pathways and modulating intestinal microbiota.

Licorice is widely used in traditional Chinese Medicine (TCM) for compound compatibility, which could reduce toxicity and increase efficacy of certain herbal medicine, and its active components prominently effects of inhibit of inflammation and regulate of immunity. The study probed into the mechanism of the anti-inflammatory and immunomodulatory effects of licorice based on the domination of the T helper type 17/regulatory T cells (Th17/Treg) differentiation balance and the composition and structure of the intestinal flora through the nuclear factor kappa B (NF-κB) signaling pathway. BALB/c mice were inoculated with dextran sulfate sodium (DSS) to establish animal models of ulcerative colitis (UC). For the pharmacodynamic study, UC mice were observed for the anti-inflammatory effect of licorice water extraction (LWE) in vivo, including clinical observation and measurement of colon length. Hematoxylin-eosin (HE) staining was used to evaluate pathological conditions. Immunohistochemistry (IHC) and transmission electron microscopy (TEM) were performed to observe the intestinal barrier of the colons. Inflammatory cytokine levels were measured using with enzyme-linked immunosorbent assay (ELISA) kits. The proportions of T helper (Th) cells in the colons was assessed using flow cytometry. Gut microbiota diversity was detected using 16S ribosomal (r)DNA sequencing. In addition, Western blot (WB) assays were used to verify ROR-γt, Foxp3, TLR4, MyD88 and NF-κB expression according to a standard protocol. LWE exerted a pharmacological anti-inflammatory effect by attenuating inflammation in the colonic tissues through affecting the protein expression of TLR4/MyD88/NF-κB, and increasing the expression of tight junction (TJ) protein in the colons, improving the integrity of the intestinal mucosal barrier in vivo. Moreover, LWE reversed the imbalance in Th17/Treg cells differentiation and influenced the protein expression of ROR-γt and Foxp3 in UC mouse colons. In particular, LWE significantly affected the diversity of the gut microbiota in UC mice, ameliorated the composition of dominant species, and significantly increased the type and quantity of probiotics. Licorice tends to reduce inflammation and enhance the protective action of the intestinal mucosal barrier via the TLR4/MyD88/NF-κB signal transduction pathway and alter the imbalance of Th-cell differentiation. Notably, licorice may affect the diversity of intestinal microbiota and the content of beneficial bacteria in the colon, which is a potential mechanism for understanding anti-inflammatory and immunomodulatory effects in UC mice in vivo.

Shi G ，Kong J ，Wang Y ，Xuan Z ，Xu F ... -  《-》

Pinocembrin alleviates ulcerative colitis in mice via regulating gut microbiota, suppressing TLR4/MD2/NF-κB pathway and promoting intestinal barrier.

Pinocembrin, a plant-derived flavonoid, has a variety of pharmacological activities, including anti-infection, anti-cancer, anti-inflammation, cardiovascular protection, etc. However, the mechanism of pinocembrin on the anti-colitis efficacy remains elusive and needs further investigation. Here, we reported that pinocembrin eased the severity of dextran sulfate sodium (DSS)-induced colitis in mice by suppressing the abnormal activation of toll-like receptor 4 (TLR4)/nuclear factor-kappa B (NF-κB) signal pathway in vivo. In addition, the gut microbiota was disordered in DSS colitis mice, which was associated with a significant decrease in microbiota diversity and a great shift in bacteria profiles; however, pinocembrin treatment improved the imbalance of gut microbiota and made it similar to that in normal mice. On the other hand, in vitro, pinocembrin down-regulated the TLR4/NF-κB signaling cascades in lipopolysaccharide (LPS)-stimulated macrophages. At the upstream level, pinocembrin competitively inhibited the binding of LPS to myeloid differentiation protein 2 (MD2), thereby blocking the formation of receptor multimer TLR4/MD2·LPS. Furthermore, pinocembrin dose-dependently promoted the expression of tight junction proteins (ZO-1, Claudin-1, Occludin and JAM-A) in Caco-2 cells. In conclusion, our work presented evidence that pinocembrin attenuated DSS-induced colitis in mouse, at least in part, via regulating intestinal microbiota, inhibiting the over-activation of TLR4/MD2/NF-κB signaling pathway, and improving the barriers of intestine.

Yue B ，Ren J ，Yu Z ，Luo X ，Ren Y ，Zhang J ，Mani S ，Wang Z ，Dou W ... -  《-》

Mesona chinensis Benth Polysaccharides Alleviate DSS-Induced Ulcerative Colitis via Inhibiting of TLR4/MAPK/NF-κB Signaling Pathways and Modulating Intestinal Microbiota.

Ulcerative colitis (UC) is a severe disease of the intestinal tract. To investigate the role of TLR4/Mitogen-activated protein kinase (MAPK)/Nuclear factor kappa-B(NF-κB) pathways and intestinal flora in UC, and the protective mechanisms of Mesona chinensis Benth polysaccharides (MBP), potential therapeutic agents due to their diabetes-relieving, cancer-suppressing, and immunomodulatory properties. A dextran sulfate sodium (DSS)-induced mouse colitis model is used for experiments; the histopathology, immunohistochemistry, and Western blotting's results suggest that MBP can alleviate the colitis symptoms, inhibits the overproduction of TNF-α, IL-1β, promote IL-10, reduces myeloperoxidase activity, and alleviates the inflammatory response probably by inhibiting the activation of TLR4/MAPK/NF-κB pathways. Furthermore, MBP improvs the ratio of Bcl-2/BAX, maintains the intestinal integrity by promoting the levels of zonulin occludin-1 (ZO-1), occluding and mucin mucin-2 (MUC-2), reduces the levels of endotoxin (ET), lipopolysaccharide binding protein (LBP) in serum, and oxidative stress in liver. Moreover, using 16S rRNA Gene Sequencing analysis, MBP regulates gut microbiota by decreasing the abundances of Helicobacter and Prevotella and increasing the abundances of Lactobacillus and Coprococcus, reverses microbiota dysbiosis caused by DSS. These findings confirm the anti-inflammatory effects of MBP, restoration of the intestinal barrier and intestinal flora, and have therapeutic potential to attenuate the development of UC.

Lu H ，Shen M ，Chen T ，Yu Y ，Chen Y ，Yu Q ，Chen X ，Xie J ... -  《-》

Kaempferol Alleviates Murine Experimental Colitis by Restoring Gut Microbiota and Inhibiting the LPS-TLR4-NF-κB Axis.

Intestinal microbiota dysbiosis is an established characteristic of ulcerative colitis (UC). Regulating the gut microbiota is an attractive alternative UC treatment strategy, considering the potential adverse effects of synthetic drugs used to treat UC. Kaempferol (Kae) is an anti-inflammatory and antioxidant flavonoid derived from a variety of medicinal plants. In this study, we determined the efficacy and mechanism of action of Kae as an anti-UC agent in dextran sulfate sodium (DSS)-induced colitis mice. DSS challenge in a mouse model of UC led to weight loss, diarrhea accompanied by mucous and blood, histological abnormalities, and shortening of the colon, all of which were significantly alleviated by pretreatment with Kae. In addition, intestinal permeability was shown to improve using fluorescein isothiocyanate (FITC)-dextran administration. DSS-induced destruction of the intestinal barrier was also significantly prevented by Kae administration via increases in the levels of ZO-1, occludin, and claudin-1. Furthermore, Kae pretreatment decreased the levels of IL-1β, IL-6, and TNF-α and downregulated transcription of an array of inflammatory signaling molecules, while it increased IL-10 mRNA expression. Notably, Kae reshaped the intestinal microbiome by elevating the Firmicutes to Bacteroidetes ratio; increasing the linear discriminant analysis scores of beneficial bacteria, such as Prevotellaceae and Ruminococcaceae; and reducing the richness of Proteobacteria in DSS-challenged mice. There was also an evident shift in the profile of fecal metabolites in the Kae treatment group. Serum LPS levels and downstream TLR4-NF-κB signaling were downregulated by Kae supplementation. Moreover, fecal microbiota transplantation from Kae-treated mice to the DSS-induced mice confirmed the effects of Kae on modulating the gut microbiota to alleviate UC. Therefore, Kae may exert protective effects against colitis mice through regulating the gut microbiota and TLR4-related signaling pathways. This study demonstrates the anti-UC effects of Kae and its potential therapeutic mechanisms, and offers novel insights into the prevention of inflammatory diseases using natural products.

Qu Y ，Li X ，Xu F ，Zhao S ，Wu X ，Wang Y ，Xie J ... -  《Frontiers in Immunology》