TLR7 rs2897827 Polymorphism Affects TLR7 Gene mRNA Expression and Serum Apolipoprotein A1 Level of Ischemic Stroke Patients in a Chinese Han Population

Intestinal expression of toll-like receptor gene changes early after gastric bypass surgery and association with type 2 diabetes remission

OBJECTIVES

Abnormal activation of toll-like receptors (TLRs) is observed in obese rodents and is correlated with local dysbiosis and increased gut permeability. These purported changes trigger systemic inflammation associated with obesity-related comorbidities, including type 2 diabetes (T2D). Roux-en-Y gastric bypass (RYGB) surgery is an effective treatment for severe obesity and known to induce changes in the gut microbiota and decrease systemic inflammation in humans. This study examined the intestinal expression of TLR-encoding genes in obese women (n = 20) treated with RYGB surgery and the relationship of these genes with T2D remission (T2Dr METHODS: Intestinal biopsies were performed before and 3 months after RYGB surgery. Partial and complete T2Dr after 1 year was assessed using the American Diabetes Association criteria. Affymetrix Human GeneChip 1.0 ST array (microarray) and TaqMan assay (real-time quantitative polymerase chain reaction) were used to analyze intestinal gene expression, and associations with systemic markers of energy homeostasis were examined.

RESULTS

Patients experienced significant weight loss (P < 0.001) and altered gut TLR gene expression 3 months after surgery. The main effects were a reduction in jejunal TLR4 expression in patients with complete and partial T2Dr (P < 0.05). There was a postoperative decrease in jejunal TLR7 expression in patients with complete T2Dr that correlated inversely with high-density lipoprotein cholesterol and positively with triglyceride concentrations, but not with weight loss.

CONCLUSIONS

RYGB-induced weight loss-independent changes in the expression of intestinal TLR-encoding genes in obese women and complete T2Dr that was correlated with systemic markers of energy homeostasis. The modulation of intestinal TLRs may mediate inflammatory mechanisms linked to T2Dr after RYGB surgery.

EV71 infection induces neurodegeneration via activating TLR7 signaling and IL-6 production

As a neurotropic virus, human Enterovirus 71 (EV71) infection causes hand-foot-and-mouth disease (HFMD) and may develop severe neurological disorders in infants. Toll-like receptor 7 (TLR7) acts as an innate immune receptor and is also a death receptor in the central nervous system (CNS). However, the mechanisms underlying the regulation of TLR7-mediated brain pathogenesis upon EV71 infection remain largely elusive. Here we reveal a novel mechanism by which EV71 infects astrocytes in the brain and induces neural pathogenesis via TLR7 and interleukin-6 (IL-6) in C57BL/6 mice and in human astroglioma U251 cells. Upon EV71 infection, wild-type (WT) mice displayed more significant body weight loss, higher clinical scores, and lower survival rates as compared with TLR7^-/- mice. In the cerebral cortex of EV71-infected mice, neurofilament integrity was disrupted, and inflammatory cell infiltration and neurodegeneration were induced in WT mice, whereas these were largely absent in TLR7^-/- mice. Similarly, IL-6 production, Caspase-3 cleavage, and cell apoptosis were significantly higher in EV71-infected WT mice as compared with TLR7^-/- mice. Moreover, EV71 preferentially infected and induced IL-6 in astrocytes of mice brain. In U251 cells, EV71-induced IL-6 production and cell apoptosis were suppressed by shRNA-mediated knockdown of TLR7 (shTLR7). Moreover, in the cerebral cortex of EV71-infected mice, the blockade of IL-6 with anti-IL-6 antibody (IL-6-Ab) restored the body weight loss, attenuated clinical scores, improved survival rates, reduced the disruption of neurofilament integrity, decreased cell apoptotic induction, and lowered levels of Caspase-3 cleavage. Similarly, in EV71-infected U251 cells, IL-6-Ab blocked EV71-induced IL-6 production and cell apoptosis in response to viral infection. Collectively, it’s exhibited TLR7 upregulation, IL-6 induction and astrocytic cell apoptosis in EV71-infected human brain. Taken together, we propose that EV71 infects astrocytes of the cerebral cortex in mice and human and triggers TLR7 signaling and IL-6 release, subsequently inducing neural pathogenesis in the brain.

Enterovirus 71 (EV71) infection causes aseptic meningitis, poliomyelitis-like paralysis and fatal encephalitis in infants. Besides an immune receptor, toll-like receptor 7 (TLR7) serves as a death receptor in central nervous system (CNS). However, the role of TLR7 in EV71-induced neural pathogenesis remains ambiguous. This study reveals a distinct mechanism by which EV71 induces neurodegeneration via TLR7 and interleukin-6 (IL-6). Upon EV71 infection, TLR7^-/- mice displayed less body weight loss, lower clinical score, and higher survival rate as compared with wild-type (WT) mice. Meanwhile, a severer histopathologic neurofilaments disruption, neurodegeneration and cell apoptosis were observed in brain of EV71-infected WT mice. IL-6 release, cell apoptosis, and Caspase-3 cleavage were attenuated by shRNA targeting TLR7 (shTLR7) in EV71-infected U251 cells. Moreover, anti-IL-6 antibody (IL-6-Ab) suppressed EV71-induced body weight loss, clinical score increase, and survival rate decrease as well as neurofilaments disruption and neurodegeneration in mice, and it also attenuated EV71-induced cell apoptosis and Caspase-3 cleavage in U251 cells. It’s retrospectively observed that TLR7 upregulation, IL-6 induction and astrocytic cell apoptosis in EV71-infected human brain. Therefore, TLR7 is required for neural pathogenesis by IL-6 induction upon EV71 infection.