Mouse Neutrophils Require JNK2 MAPK forToxoplasma gondii-Induced IL-12p40 and CCL2/MCP-1 Release

Abstract

The MAPK family member JNK/stress-activated MAPK (SAPK) is involved in extracellular stress and proinflammatory cytokine responses, including production of cytokines such as IL-12. The JNK1 and 2 isoforms are widely expressed, but JNK3 is largely restricted to tissues of the brain, testis, and heart. In this study, we focus on mouse neutrophils, a cell type in which JNK/SAPK expression and activity has been given little study. We used Western blot analysis to examine expression patterns of JNK/SAPK in wild-type and JNK2−/− polymorphonuclear leukocytes (PMN). Surprisingly, neutrophils displayed a major deficiency in JNK1 expression, in contrast to macrophages that expressed high levels of both JNK1 and JNK2 MAPK. JNK1 expression was steadily reduced during the neutrophil maturation in bone marrow. We used PMN infection with the protozoan parasite Toxoplasma gondii to determine whether neutrophil JNK2 was functional. The parasite induced rapid JNK2 phosphorylation and intracellular FACS staining demonstrated preferential activation in infected neutrophils. Use of JNK2−/− neutrophils revealed that this MAPK family member was required for PMN IL-12p40 and CCL2/MCP-1 production. The chemotactic response displayed a minor JNK2 dependence but phagocytosis and oxidative burst activity did not require this MAPK. These findings are important because they demonstrate 1) a previously unrecognized unusual JNK expression pattern in mouse neutrophils, 2) JNK2 in PMN is activated by Toxoplasma invasion, and 3) a requirement for JNK2 in PMN IL-12p40 and CCL2/MCP-1 production in response to a microbial pathogen.

JNK1 controls mast cell degranulation and IL-1β production in inflammatory arthritis

“…S2). These data suggested that JNK1 in neutrophils is not critical for developing arthritis and are consistent with other reports that mature neutrophils have little, if any, expression of JNK1 (29).…”

“…In addition, the repletion of WT neutrophils did not recapitulate arthritis in JNK1-deficient mice. Although FcγR expression by neutrophils contributes to the generation of arthritis (28), the paucity of JNK1 reported in mature neutrophils (29) suggested that these cells use signaling pathways that are not entirely similar to MCs. Other cell types might also be involved in the attenuated course of arthritis in JNK1-deficient mice, including macrophages.…”

Toxoplasma gondii Induces B7-2 Expression through Activation of JNK Signal Transduction

“…In neutrophils, IL-12 and CCL2/monocyte chemoattractant protein 1 (MCP-1) production require JNK2, as polymorphonuclear leukocytes (PMN) from JNK2 Ϫ/Ϫ mice were totally deficient in the production of these cytokines (56). Neutrophil chemotaxis is also partially dependent on JNK2 (56). Using pharmacological inhibitors, we found that B7-2 upregulation in T. gondiiinfected cells is dependent on JNK signaling.…”

“…In macrophages, autophosphorylation of p38 is the dominant player in activating IL-12 secretion (27). In neutrophils, IL-12 and CCL2/monocyte chemoattractant protein 1 (MCP-1) production require JNK2, as polymorphonuclear leukocytes (PMN) from JNK2 Ϫ/Ϫ mice were totally deficient in the production of these cytokines (56). Neutrophil chemotaxis is also partially dependent on JNK2 (56).…”

The Tobacco Smoke Component, Acrolein, Suppresses Innate Macrophage Responses by Direct Alkylation of c-Jun N-Terminal Kinase

“…Most notably, pharmacologic inhibition of JNK almost completely prevented LPS-mediated production of NOS2/NO and TNF-a, indicating the critical importance of JNK in these immune responses. Although JNK1 and JNK2 may have largely overlapping and redundant functions, studies using transgenic approaches or genetic deficiency of specific JNK isoforms indicate that it is primarily JNK2 that is responsible for these innate responses (56)(57)(58). In this regard, our discovery of JNK2 as the primary target for direct alkylation implicates JNK2 as a direct site for inhibition of JNK signaling and innate immune responses by acrolein.…”