IL-4 and IL-13 employ discrete signaling pathways for target gene expression in alternatively activated monocytes/macrophages

Abstract

Monocytes/macrophages are innate immune cells that play a crucial role in the resolution of inflammation. In presence of Th2 cytokines interleukin-4 (IL-4) and interleukin-13 (IL-13), they display an anti-inflammatory profile and this activation pathway is known as alternative activation. In this study we compare and differentiate pathways mediated by IL-4 and IL-13 activation of human monocytes/macrophage. Here we report differential regulation of IL-4 and IL-13 signaling in monocytes/macrophages starting from IL-4/IL-13 cytokine receptors to Jak-Stat-mediated signaling pathways that ultimately control expression of several infl1ammatory genes. Our data demonstrate that while the receptor-associated tyrosine kinases Jak2 and Tyk2 are activated after the recruitment of IL-13 to its receptor (containing IL-4Rα and IL-13Rα1), IL-4 stimulates Jak1 activation. We further show that Jak2 is upstream of Stat3 activation and Tyk2 controls Stat1 and Stat6 activation in response to IL-13 stimulation. In contrast, Jak1 regulates Stat3 and Stat6 activation in IL-4-induced monocytes. Our results further reveal that while IL-13 utilizes both IL-4Rα-Jak2-Stat3 and IL-13Rα1-Tyk2-Stat1/Stat6 signaling pathways, IL-4 can only use the IL-4Rα-Jak1-Stat3/Stat6 cascade to regulate the expression of some critical inflammatory genes including 15-lipoxygenase (15-LO), monoamine oxidase A (MAO-A) and scavenger receptor CD36. Moreover, we demonstrate here that IL-13 and IL-4 can uniquely affect the expression of particular genes like dual specificity phosphatase 1 (DUSP1) and tissue inhibitor of metalloprotease-3 (TIMP3) and do so through different Jak kinaes. As evidence of differential regulation of gene function by IL-4 and IL-13, we further report that MAO-A-mediated reactive oxygen species (ROS) generation is influenced by different Jak kinases. Collectively, these results have major implications for understanding the mechanism and function of alternatively activated monocytes/macrophages by IL-4 and IL-13 and add novel insights into the pathogenesis and potential treatment of different inflammatory diseases.

AMP-activated Protein Kinase Suppresses Arachidonate 15-Lipoxygenase Expression in Interleukin 4-polarized Human Macrophages

“…Interestingly, only a subset of IL-4-stimulated genes, most prominently ALOX15, is inhibited upon AMPK activation. It is known that, in addition to STAT6, STAT3 is involved in the regulation of ALOX15 in IL-4-treated human monocytes (22). Our data corroborate a role of STAT3 in regulating ALOX15 in response to IL-4, and we suggest that AMPK attenuates STAT3-dependent gene expression by preventing STAT3 association with upstream Jak1 tyrosine kinase, its tyrosine and serine phosphorylation, and nuclear translocation upon IL-4-treatment.…”

“…To question the involvement of STATs in AMPK-dependent ALOX15 suppression, we analyzed tyrosine phosphorylation and nuclear translocation of STAT3 and STAT6 as signs of their activation in IL-4-treated cells in the presence of AICAR or phenformin. Furthermore, we analyzed phosphorylation of Jak1 kinase, which was reported to phosphorylate STAT3 and STAT6 in IL-4-stimulated monocytes (22). IL-4 elicited robust phosphorylations of Jak1, STAT3, and STAT6 within 15 min, which returned to baseline after 3 h (Fig.…”

“…However, the STAT3 transcription factor is engaged in IL-4-induced ALOX15 expression in human monocytes (22). To question the involvement of STATs in AMPK-dependent ALOX15 suppression, we analyzed tyrosine phosphorylation and nuclear translocation of STAT3 and STAT6 as signs of their activation in IL-4-treated cells in the presence of AICAR or phenformin.…”

Cryopreserved Interleukin-4-Treated Macrophages Attenuate Murine Colitis in an Integrin β7-Dependent Manner

“…On d 3, fluorescence intensity was strongest in the peritoneal area of the M(IL-4)-treated mice ( Figure 4A), a pattern that was similar to d -2 just mechanistic studies: would M(IL-4)s suppress colitis in a manner equivalent to that observed with M(IL-4 + IL-13)s, and would cryopreserved M(IL-4)s retain their ability to inhibit colitis. It is generally accepted that IL-4 is the key cytokine in the alternative activation of macrophages and that IL-13 complements or enhances the differentiation of the AAM via STAT3 and STAT6 signaling (27,28). Assessment of canonical markers of mouse and human AAMs revealed almost identical responses to IL-4 and IL-4 + IL-13 (IL-13 alone was a less potent stimulus of an AAM phenotype), a finding in accordance with data showing that bone marrow-derived macrophages and human monocytes were more Indeed, we, and others, have shown that adoptive transfer of AAMs retrieved from mice or differentiated in vitro from bone marrow precursors or peritoneal macrophages can suppress colitis (14)(15)(16)(17)(18)(19)).…”

Role of complement in ALS: regulating peripheral immune cells in skeletal muscle of hSOD1G93A mouse model of ALS

“…or 'alternatively activated' macrophage, results from stimulation of Th2 cytokines interleukin (IL)-4 and IL3, are associated with tissue repair, wound healing and fibrosis (Bhattacharjee et al, 2013). Meanwhile, anti-inflammatory M2c macrophages induced by IL-10, release anti-inflammatory cytokines to deactivate the M1 phenotype and promote the proliferation of non-myeloid cells (Sica and Mantovani, 2012).…”