Debierre-Grockiego Françoise, Campos Marco A, Azzouz Nahid, Schmidt Jörg, Bieker Ulrike, Resende Marianne Garcia, Mansur Daniel Santos, Weingart Ralf, Schmidt Richard R, Golenbock Douglas T, Gazzinelli Ricardo T, Schwarz Ralph T
Institut für Virologie, AG Parasitologie, Philipps University, Marburg, Germany.
J Immunol. 2007 Jul 15;179(2):1129-37. doi: 10.4049/jimmunol.179.2.1129.
GPIs isolated from Toxoplasma gondii, as well as a chemically synthesized GPI lacking the lipid moiety, activated a reporter gene in Chinese hamster ovary cells expressing TLR4, while the core glycan and lipid moieties cleaved from the GPIs activated both TLR4- and TLR2-expressing cells. MyD88, but not TLR2, TLR4, or CD14, is absolutely needed to trigger TNF-alpha production by macrophages exposed to T. gondii GPIs. Importantly, TNF-alpha response to GPIs was completely abrogated in macrophages from TLR2/4-double-deficient mice. MyD88(-/-) mice were more susceptible to death than wild-type (WT), TLR2(-/-), TLR4(-/-), TLR2/4(-/-), and CD14(-/-) mice infected with the ME-49 strain of T. gondii. The cyst number was higher in the brain of TLR2/4(-/-), but not TLR2(-/-), TLR4(-/-), and CD14(-/-), mice, as compared with WT mice. Upon infection with the ME-49 strain of T. gondii, we observed no decrease of IL-12 and IFN-gamma production in TLR2-, TLR4-, or CD14-deficient mice. Indeed, splenocytes from T. gondii-infected TLR2(-/-) and TLR2/4(-/-) mice produced more IFN-gamma than cells from WT mice in response to in vitro stimulation with parasite extracts enriched in GPI-linked surface proteins. Together, our results suggest that both TLR2 and TLR4 receptors may participate in the host defense against T. gondii infection through their activation by the GPIs and could work together with other MyD88-dependent receptors, like other TLRs or even IL-18R or IL-1R, to obtain an effective host response against T. gondii infection.
从刚地弓形虫中分离出的糖基磷脂酰肌醇（GPI），以及一种缺乏脂质部分的化学合成GPI，在表达TLR4的中国仓鼠卵巢细胞中激活了报告基因，而从GPI上切割下来的核心聚糖和脂质部分则激活了表达TLR4和TLR2的细胞。巨噬细胞暴露于刚地弓形虫GPI时，触发肿瘤坏死因子-α（TNF-α）产生绝对需要髓样分化因子88（MyD88），而不是TLR2、TLR4或CD14。重要的是，在TLR2/4双缺陷小鼠的巨噬细胞中，对GPI的TNF-α反应完全消除。与感染刚地弓形虫ME-49株的野生型（WT）、TLR2缺陷型、TLR4缺陷型、TLR2/4缺陷型和CD14缺陷型小鼠相比，MyD88缺陷型小鼠更容易死亡。与WT小鼠相比，TLR2/4缺陷型小鼠（而非TLR2缺陷型、TLR4缺陷型和CD14缺陷型小鼠）大脑中的囊肿数量更多。感染刚地弓形虫ME-49株后，我们在TLR2、TLR4或CD14缺陷型小鼠中未观察到白细胞介素-12（IL-12）和干扰素-γ（IFN-γ）产生减少。事实上，刚地弓形虫感染的TLR2缺陷型和TLR2/4缺陷型小鼠的脾细胞在受到富含GPI连接表面蛋白的寄生虫提取物体外刺激时，产生的IFN-γ比WT小鼠的细胞更多。总之，我们的结果表明，TLR2和TLR4受体都可能通过被GPI激活而参与宿主对刚地弓形虫感染的防御，并可能与其他依赖MyD88的受体（如其他TLR，甚至IL-18R或IL-1R）协同作用，以获得针对刚地弓形虫感染的有效宿主反应。
