Gonnella Patricia A, Waldner Hanspeter, Del Nido Pedro J, McGowan Francis X
Department of Anesthesiology, Children's Hospital and Harvard Medical School, 320 Longwood Ave., Boston, MA 02115, USA.
J Autoimmun. 2008 Sep;31(2):180-7. doi: 10.1016/j.jaut.2008.06.002. Epub 2008 Aug 19.
Toll-like receptors (TLR) are pattern recognition receptors that are an essential feature of host defense against pathogens. Expression of TLR-4 on dendritic cells was reported to be required for initiation of experimental autoimmune myocarditis (EAM) but the mechanism by which TLR-4 signaling affects autoimmunity is incompletely understood. To determine the role of TLR-4 in EAM, wild type and TLR-4-/- mice were immunized with myosin peptide (614-629) in CFA. TLR-4-/- mice demonstrated decreased myosin specific proliferation and decreased production of INF-gamma and IL-2. Immunization with myosin induced greater severity of myocarditis in wild type compared to TLR-4-/- mice as evidenced by lesions in the myocardium. TcR Vbeta 8.1, 8.2+ CD4+ T cells, detected in lesions were isolated from splenocytes by flow cytometry and found to undergo increased apoptosis in TLR-4-/- mice. In situ immunohistochemistry showed increased colocalization of cleaved caspase 3 and TcR Vbeta 8.1, 8.2+ CD4+ T cells in TLR-4-/- mice compared to wild type. Increased apoptosis was associated with impaired activation of NF-kB p65 and decreased cell viability in the presence of TNF-alpha. These results demonstrate that infiltrating TcR Vbeta 8.1, 8.2+ CD4+ T cells are deleted by the mechanism of apoptosis in TLR-4-/- mice with EAM.
Toll样受体（TLR）是模式识别受体，是宿主抵御病原体的重要特征。据报道，树突状细胞上TLR-4的表达是实验性自身免疫性心肌炎（EAM）启动所必需的，但TLR-4信号传导影响自身免疫的机制尚不完全清楚。为了确定TLR-4在EAM中的作用，用CFA中的肌球蛋白肽（614-629）免疫野生型和TLR-4基因敲除小鼠。TLR-4基因敲除小鼠表现出肌球蛋白特异性增殖降低以及INF-γ和IL-2产生减少。与TLR-4基因敲除小鼠相比，野生型小鼠用肌球蛋白免疫后心肌炎的严重程度更高，心肌病变证明了这一点。通过流式细胞术从脾细胞中分离出病变中检测到的TcR Vβ8.1、8.2 + CD4 + T细胞，发现其在TLR-4基因敲除小鼠中凋亡增加。原位免疫组化显示，与野生型相比，TLR-4基因敲除小鼠中裂解的半胱天冬酶3与TcR Vβ8.1、8.2 + CD4 + T细胞的共定位增加。凋亡增加与NF-κB p65激活受损以及在TNF-α存在下细胞活力降低有关。这些结果表明，在患有EAM的TLR-4基因敲除小鼠中，浸润的TcR Vβ8.1、8.2 + CD4 + T细胞通过凋亡机制被清除。
