CD226 expression deficiency causes high sensitivity to apoptosis in NK T cells from patients with systemic lupus erythematosus |
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Authors: | Tao Deng Shangwu Liu Qun Wu Yan Liu Wei Ju Junyan Liu Feili Gong Boquan Jin Jinquan Tan |
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Institution: | Department of Internal Medicine, Renmin Hospital, Wuhan University, Wuhan, Peoples Republic of China. |
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Abstract: | Humans and mice with systemic lupus erythematosus (SLE) and related autoimmune diseases have reduced numbers of NK T cells. An association between NK T cell deficiency and autoimmune disease has been identified. However, the mechanisms for reduction of NK T cell number in patients with SLE are unknown. In the present study we report that NK T cells from active SLE patients are highly sensitive to anti-CD95-induced apoptosis compared with those from normal subjects and inactive SLE patients. CD226 expression is deficient on NK T cells from active SLE patients. The expression of one antiapoptotic member protein, survivin, is found to be selectively deficient in freshly isolated NK T cells from active SLE patients. CD226 preactivation significantly up-regulates survivin expression and activation, which can rescue active SLE NK T cells from anti-CD95-induced apoptosis. In transfected COS7 cells, we confirm that anti-CD95-mediated death signals are inhibited by activation of the CD226 pathway through stabilization of caspase-8 and caspase-3 and through activation of survivin. We therefore conclude that deficient expression of CD226 and survivin in NK T cells from active SLE is a molecular base of high sensitivity of the cells to anti-CD95-induced apoptosis. These observations offer a potential explanation for high apoptotic sensitivity of NK T cells from active SLE, and provide a new insight into the mechanism of reduction of NK T cell number in SLE and understanding the association between NK T cell deficiency and autoimmune diseases. |
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