Parihar Robin, Trotta Rossana, Roda Julie M, Ferketich Amy K, Tridandapani Susheela, Caligiuri Michael A, Carson William E
Department of Molecular Virology, Immunology, and Medical Genetics, Ohio State University, Columbus, OH 43210, USA.
Cancer Res. 2005 Oct 1;65(19):9099-107. doi: 10.1158/0008-5472.CAN-04-4424.
We have previously shown that natural killer (NK) cells secrete a distinct profile of immunomodulatory cytokines in response to dual stimulation with antibody-coated tumor cells and interleukin-12 (IL-12). This NK cell cytokine response is dependent on synergistic signals mediated by the activating receptor for the Fc portion of IgG (FcgammaRIIIa) and the IL-12 receptor (IL-12R), both constitutively expressed on NK cells. The phosphatase Src homology 2-containing inositol 5'-phosphatase 1 (SHIP1) is known to exert inhibitory effects on Fc receptor (FcR) signaling via its enzymatic activity on phosphatidylinositol 3-kinase (PI3-K) products within many cells of the immune system, most notably mast cells, B cells, and monocytes. However, its activity in the context of FcR activation on NK cells has not been fully explored. The current study focused on the regulation of FcgammaRIIIa-induced NK cell cytokine production by SHIP1. Inhibitor studies showed that NK cell IFN-gamma production following FcR stimulation in the presence of IL-12 depended, in part, on the downstream products of PI3-K. Overexpression of wild-type (WT) SHIP1, but not a catalytic-deficient mutant, via retroviral transfection of primary human NK cells, resulted in a >70% reduction of NK cell IFN-gamma production in response to costimulation. In addition, NK cells from SHIP1-/- mice produced 10-fold greater amounts of IFN-gamma following culture with antibody-coated tumor cells plus IL-12 compared with NK cells from WT mice. Further, activation of the mitogen-activated protein kinase (MAPK) family member extracellular signal-regulated kinase (Erk; a downstream target of PI3-K) was significantly enhanced within SHIP1-/- NK cells compared with WT NK cells following costimulation. Pharmacologic inhibition of Erk activity, but not Jnk MAPK activity, led to significantly decreased IFN-gamma production from both SHIP1-/- and WT NK cells under these conditions. These results are the first to show a physiologic role for SHIP1 in the regulation of NK cell cytokine production and implicate PI3-K in the induction of MAPK signal transduction following costimulation of NK cells via the FcR and the IL-12R.
我们之前已经表明，自然杀伤（NK）细胞在受到抗体包被的肿瘤细胞和白细胞介素-12（IL-12）双重刺激时，会分泌独特的免疫调节细胞因子谱。这种NK细胞细胞因子反应依赖于由IgG的Fc部分的激活受体（FcγRIIIa）和IL-12受体（IL-12R）介导的协同信号，这两种受体在NK细胞上组成性表达。已知含Src同源2结构域的肌醇5'-磷酸酶1（SHIP1）通过其对免疫系统许多细胞内磷脂酰肌醇3-激酶（PI3-K）产物的酶活性，对Fc受体（FcR）信号传导发挥抑制作用，最显著的是肥大细胞、B细胞和单核细胞。然而，其在NK细胞上FcR激活背景下的活性尚未得到充分研究。当前的研究聚焦于SHIP1对FcγRIIIa诱导的NK细胞细胞因子产生的调节作用。抑制剂研究表明，在IL-12存在的情况下，FcR刺激后NK细胞IFN-γ的产生部分依赖于PI3-K的下游产物。通过对原代人NK细胞进行逆转录病毒转染，野生型（WT）SHIP1而非催化缺陷型突变体的过表达，导致共刺激后NK细胞IFN-γ产生减少>70%。此外，与野生型小鼠的NK细胞相比，SHIP1基因敲除（SHIP1-/-）小鼠的NK细胞在与抗体包被的肿瘤细胞加IL-12共培养后产生的IFN-γ量高10倍。此外，与野生型NK细胞相比，共刺激后SHIP1-/- NK细胞内丝裂原活化蛋白激酶（MAPK）家族成员细胞外信号调节激酶（Erk；PI3-K的下游靶点）的激活显著增强。在这些条件下，对Erk活性而非Jnk MAPK活性进行药理抑制，导致SHIP1-/-和野生型NK细胞的IFN-γ产生均显著减少。这些结果首次表明SHIP1在调节NK细胞细胞因子产生中具有生理作用，并表明PI3-K参与了NK细胞通过FcR和IL-12R共刺激后的MAPK信号转导诱导过程。
