| First Author | Varin A | Year | 2010 |
| Journal | Blood | Volume | 115 |
| Issue | 2 | Pages | 353-62 |
| PubMed ID | 19880493 | Mgi Jnum | J:156317 |
| Mgi Id | MGI:4420333 | Doi | 10.1182/blood-2009-08-236711 |
| Citation | Varin A, et al. (2010) Alternative activation of macrophages by IL-4 impairs phagocytosis of pathogens but potentiates microbial-induced signalling and cytokine secretion. Blood 115(2):353-62 |
| abstractText | Alternatively activated macrophages play an important role in host defense in the context of a T helper type 2 (Th2) microenvironment such as parasitic infection. However, the role of these macrophages during secondary challenge with Th1 pathogens is poorly defined. In this study, thioglycollate-elicited mouse peritoneal macrophages were treated with interleukin-4 (IL-4) or IL-13 in vitro and challenged with Neisseria meningitidis. After 8 to 12 hours of IL-4 pretreatment, the nonopsonic phagocytic uptake of N meningitidis was markedly reduced, depending on the common IL-4Ralpha chain, but independent of Scavenger receptor A and macrophage receptor with collagenous structure (MARCO), 2 known receptors for N meningitidis. Inhibition of phagocytosis extended to several other microbial particles, zymosan, and other bacteria. Concomitantly, IL-4 potentiated the secretion of proinflammatory cytokines, after additional bacterial stimulation, which depended on the MyD88 signaling pathway. Similar results were obtained after intraperitoneal stimulation of IL-4 and N meningitidis in vivo. Further in vitro studies showed a striking correlation with inhibition of Akt phosphorylation and stimulation of the mitogen-activated protein kinase pathway; inhibition of phagocytosis was associated with inhibition of phagosome formation. These findings are relevant to host defense in mixed infections within a Th2 microenvironment and shed light on immunologic functions associated with alternative priming and full activation of macrophages. |
