Rhinovirus-induced macrophage cytokine expression does not require endocytosis or replication.
Rhinovirus (RV) is responsible for the majority of virus-induced asthma exacerbations. We showed previously that RV infection of ovalbumin-sensitized and -challenged BALB/c mice induces production of type 2 cytokines from M2-polarized macrophages. In the present study, we sought to determine the mechanism of RV-induced cytokine expression. We infected bone marrow-derived macrophages (BMMs) from BALB/c mice with RV serotype 1B, a minor group virus that infects mouse cells. Selected cultures were pretreated with IL-4, a type 2 cytokine increased in allergic asthma. RV infection of untreated cells increased messenger RNA and protein expression of the M1 cytokines TNF-α, CXCL1, and IL-6 but failed to induce expression of the M2 cytokines CCL22 and CCL24. Cells pretreated with IL-4 showed decreased expression of M1 cytokines but increased expression of Ym-1, Arg-1 (M2 markers), CCL22, and CCL24. Infection with ultraviolet (UV)-irradiated, replication-deficient RV elicited similar cytokine responses, suggesting that the outcome is replication independent. Consistent with this, viral RNA copy number did not increase in RV-treated BMMs or bronchoalveolar macrophages. RV-induced cytokine expression was not affected when cells were pretreated with cytochalasin D, suggesting that viral endocytosis is not required for the response. Finally, RV-induced cytokine expression and viral attachment were abolished in BMMs from myeloid differentiation factor 88 and Toll-like receptor (TLR)2 KO mice, suggesting a specific requirement of TLR2. We conclude that RV elicits a proinflammatory cytokine response in BMMs through a cell-surface-mediated, TLR2-dependent mechanism that does not require viral endocytosis or replication.
Departments of 1 Pediatrics and Communicable Diseases and.
Thomas G
TG
Saba
Yutein
Y
Chung
Jun Young
JY
Hong
Uma S
US
Sajjan
J Kelley
JK
Bentley
Marc B
MB
Hershenson
D000818:Animals; D002478:Cells, Cultured; D054360:Chemokine CXCL1 / Q000235:genetics / Q000378:metabolism; D016207:Cytokines / Q000235:genetics* / Q000378:metabolism*; D004705:Endocytosis / Q000235:genetics*; D005260:Female; D015850:Interleukin-6 / Q000235:genetics / Q000378:metabolism; D008264:Macrophages / Q000378:metabolism* / Q000821:virology*; D051379:Mice; D008807:Mice, Inbred BALB C; D053594:Myeloid Differentiation Factor 88 / Q000235:genetics / Q000378:metabolism; D012367:RNA, Viral / Q000235:genetics; D012229:Rhinovirus / Q000235:genetics*; D051195:Toll-Like Receptor 2 / Q000235:genetics / Q000378:metabolism; D051196:Toll-Like Receptor 3 / Q000235:genetics / Q000378:metabolism; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism; D014779:Virus Replication / Q000235:genetics*
D054360:Chemokine CXCL1; C475895:Cxcl1 protein, mouse; D016207:Cytokines; D015850:Interleukin-6; C507780:Myd88 protein, mouse; D053594:Myeloid Differentiation Factor 88; D012367:RNA, Viral; C519703:TLR3 protein, mouse; C493486:Tlr2 protein, mouse; D051195:Toll-Like Receptor 2; D051196:Toll-Like Receptor 3; D014409:Tumor Necrosis Factor-alpha