SHIP Represses the Generation of IL-3-Induced M2 Macrophages by Inhibiting IL-4 Production from Basophils

Abstract

There is a great deal of interest in determining what regulates the generation of classically activated (M1) vs alternatively activated (M2) macrophages (Mφs) because of the opposing effects that these two Mφ subsets have on tumor progression. We show herein that IL-3 and, to a lesser extent, GM-CSF skew murine Mφ progenitors toward an M2 phenotype, especially in the absence of SHIP. Specifically, the addition of these cytokines, with or without M-CSF, to adherence- or lineage-depleted (Lin−) SHIP−/− bone marrow (BM) cells induces high levels of the M2 markers, arginase I, and Ym1 in the resulting mature Mφs. These in vitro-derived mature Mφs also display other M2 characteristics, including an inability to enhance anti-CD3-stimulated splenic T cell secretion of IFN-γ and low IL-12 and high IL-10 production in response to LPS. Not surprisingly, given that IL-3 and GM-CSF utilize STAT5 to trigger many downstream signaling pathways, this M2 phenotype is suppressed when STAT5−/− BM cells are used. Unexpectedly, however, this M2 phenotype is also suppressed when STAT6−/− BM cells are used, suggesting that IL-4- or IL-13-induced signaling might be involved. Consistent with this, we found that IL-3 and GM-CSF stimulate the production of IL-4, especially from SHIP−/− Lin− BM cells, and that neutralizing anti-IL-4 Abs block IL-3-induced M2 skewing. Moreover, we found that basophil progenitors within the Lin− BM are responsible for this IL-3- and GM-CSF-induced IL-4 production, and that SHIP represses M2 skewing not by preventing skewing within Mφs themselves but by inhibiting IL-4 production from basophils.

TLR Agonists That Induce IFN-β Abrogate Resident Macrophage Suppression of T Cells

“…Each of these reagents has been shown to be biologically active in our hands in several different systems (20,(22)(23)(24)(25)(26), and V. Ho, M. Hamilton, and G. Krystal, unpublished results). We first determined whether cytokines that have been reported to alter Mf phenotype (i.e., IL-4, IL-13) (12) or restrict T cell proliferation (i.e., IL-10, TGF-b) (27) were involved.…”

Genetic Segregation of Inflammatory Lung Disease and Autoimmune Disease Severity in SHIP-1−/− Mice

“…Furthermore, we show that SHIP-1 2/2 mice are prone to autoimmunity, and that conditional loss of SHIP-1 in B cells is sufficient to cause disease; however, severity of disease is influenced by genetic background. The lung disease in young SHIP-1 2/2 mice is thought to be caused by macrophages that are skewed toward an alternatively activated (M2) phenotype, due to the hyperresponsiveness of SHIP-1 2/2 macrophage progenitors during differentiation in combination with elevated levels of M2-skewing cytokines (3,4,9,10,28,29). C57BL/6 background, but not BALB/c background SHIP-1 2/2 mice show elevated levels of Th2 and proinflammatory cytokines in serum and in BAL fluid, suggesting that aberrant cytokine production is driving the lung disease.…”

Identification of Semaphorin 4B as a Negative Regulator of Basophil-Mediated Immune Responses

“…IL-3-mediated signals in basophils are reportedly involved in the ITAM in the FcRg-spleen tyrosine kinase-ERK pathway to produce IL-4 and the IL-3Rbc-JAK-STAT5 pathway to promote proliferation and differentiation (30,36,37). Recently, it was shown that SHIP inhibited IL-4 production from basophils (42). In addition, Src homology 2 domain-containing protein tyrosine-phosphatase 1 (SHP-1) can interact with and inhibit the phosphorylation of STAT5 (43,44).…”