Inhibition of α2,6-sialyltransferase relieves symptoms of ulcerative colitis by regulating Th17 cells polarization.

Ulcerative colitis (UC) is a chronic, relapsing inflammatory disease that affects human intestines. Immune imbalance is one of the important factors inducing UC. After the activation of CD4+ T cells, pro-inflammatory cytokines are produced to induce colonic inflammation. α2,6-Sialylation, catalyzed by α2,6-sialyltransferase (ST6GAL1), affects the proliferation, activation, and T cell receptor (TCR) signaling of CD4+ T cells, but its role in CD4+ T cell polarization, regulation of Th17 / Treg balance, and its role in UC are still unclear. We found the number of CD4+ T and Th17 cells increased in colonic tissue with UC. The level of α2,6-sialylation of CD4+ T cells in patients with UC was significantly increased. De-α2,6-sialylation significantly reduced the symptoms of UC in rats. ST6GAL1 gene knockout inhibited the polarization of CD4+ T cells to Th17 cells, and promoted the polarization of CD4+ T cells to Treg cells. ST6GAL1 knockout significantly inhibited the IL-17 signaling pathway in CD4+ T cells and inhibited the secretion of pro-inflammatory cytokine IL-17a. ST6GAL1 and IL-17a are highly expressed in patients with UC, and there is a positive correlation between them. In conclusion, reduced α2,6-sialylation inhibits the polarization of CD4+ T cells to Th17 cells, inhibits IL-17a signaling pathway and reduces the level of pro-inflammatory cytokine IL-17a to alleviate the symptoms of UC, which is a potential novel target for the clinical treatment of UC.

Hyper α2,6-Sialylation Promotes CD4+ T-Cell Activation and Induces the Occurrence of Ulcerative Colitis.

α2,6-sialylation, catalyzed by α2,6-sialyltransferase (ST6GAL1), plays a pivotal role in immune responses. However, the role of ST6GAL1 in the pathogenesis of ulcerative colitis (UC) remains unknown. ST6GAL1 mRNA is highly expressed in UC tissues compared with the corresponding adjacent normal tissues, and α2,6-sialylation is significantly increased in the colon tissues of patients with UC. The expression of ST6GAL1 and proinflammatory cytokines, such as interleukin (IL)-2, IL-6, IL-17, and interferon-gamma, is also increased. The number of CD4+ T cells increases in UC patients. St6gal1 gene knockout (St6gal1-/- ) rats are established by clustered regularly interspaced short palindromic repeats (CRISPR)-associated gene knockout system. St6gal1 deficiency reduces the levels of pro-inflammatory cytokines and alleviates colitis symptoms in UC model rats. Ablation of α2,6-sialylation inhibits the transport of the TCR to lipid rafts and suppresses CD4+ T-cell activation. The attenuation of TCR signaling downregulates the expression of NF-κB in ST6GAL1-/- CD4+ T-cells. Moreover, NF-κB could bind to the ST6GAL1 promoter to increase its transcription. Ablation of ST6GAL1 downregulates the expression of NF-κB and reduces the production of proinflammatory cytokines to relieve UC pathogenesis, which is a potential novel target for the clinical treatment of UC.

Lactobacillus spp. create a protective micro-ecological environment through regulating the core fucosylation of vaginal epithelial cells against cervical cancer.

Vaginal dysbiosis often occurs in patients with cervical cancer. The fucosylation of mucosal epithelial cells is closely related to microbial colonization, and play an important role in protecting the vaginal mucosal epithelial cells. However, no reports on the relationship between vaginal dysbiosis and abnormal mucosal epithelial cell fucosylation, and their roles in the occurrence and development of cervical cancer are unavailable. Here we report that core fucosylation levels were significantly lower in the serum, exfoliated cervical cells and tumor tissue of cervical cancer patients. Core fucosyltransferase gene (Fut8) knockout promoted the proliferation and migration of cervical cancer cells. In patients with cervical cancer, the vaginal dysbiosis, and the abundance of Lactobacillus, especially L. iners, was significantly reduced. Meanwhile, the abundance of L.iners was positively correlated with core fucosylation levels. The L. iners metabolite lactate can activate the Wnt pathway through the lactate-Gpr81 complex, which increases the level of core fucosylation in epidermal cells, inhibiting the proliferation and migration of cervical cancer cells, and have application prospects in regulating the vaginal microecology and preventing cervical cancer.