[HTML][HTML] SHIP represses the generation of alternatively activated macrophages

MJ Rauh, V Ho, C Pereira, A Sham, LM Sly, V Lam… - Immunity, 2005 - cell.com
MJ Rauh, V Ho, C Pereira, A Sham, LM Sly, V Lam, L Huxham, AI Minchinton, A Mui
Immunity, 2005cell.com
We recently reported that SHIP restrains LPS-induced classical (M1) activation of in vitro
differentiated, bone marrow-derived macrophages (BMMΦs) and that SHIP upregulation is
essential for endotoxin tolerance. Herein, we show that in vivo differentiated SHIP−/−
peritoneal (PMΦs) and alveolar (AMΦs) macrophages, unlike their wild-type counterparts,
are profoundly M2 skewed (alternatively activated), possessing constitutively high arginase I
(ArgI) and Ym1 levels and impaired LPS-induced NO production. Consistent with this …
Summary
We recently reported that SHIP restrains LPS-induced classical (M1) activation of in vitro differentiated, bone marrow-derived macrophages (BMMΦs) and that SHIP upregulation is essential for endotoxin tolerance. Herein, we show that in vivo differentiated SHIP−/− peritoneal (PMΦs) and alveolar (AMΦs) macrophages, unlike their wild-type counterparts, are profoundly M2 skewed (alternatively activated), possessing constitutively high arginase I (ArgI) and Ym1 levels and impaired LPS-induced NO production. Consistent with this, SHIP−/− mice display M2-mediated lung pathology and enhanced tumor implant growth. Interestingly, BMMΦs from SHIP−/− mice do not display this M2 phenotype unless exposed to TGFβ within normal mouse plasma (MP) during in vitro differentiation. Our results suggest that SHIP functions in vivo to repress M2 skewing and that macrophage polarization can occur during differentiation in response to TGFβ if progenitors have elevated PIP3.
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