Pneumocystis carinii cell wall beta-glucan induces release of macrophage inflammatory protein-2 from alveolar epithelial cells via a lactosylceramide-mediated mechanism.
Infiltration of the lungs with neutrophils promotes respiratory failure during severe Pneumocystis carinii (PC) pneumonia. Recent studies have shown that alveolar epithelial cells (AECs), in addition to promoting PC attachment, also participate in lung inflammation by the release of cytokines and chemokines. Herein, we demonstrate that a PC beta-glucan rich cell wall isolate (PCBG) stimulates the release of macrophage inflammatory protein-2 (MIP-2) from isolated AECs through a lactosylceramide-dependent mechanism. The results demonstrate that MIP-2 mRNA and protein production is significantly increased at both early and late time points after PCBG challenge. Although CD11b/CD18 (Mac-1, CR3) is the most widely studied beta-glucan receptor, we demonstrate that CD11b/CD18 is not present on AECs. This study instead demonstrates that preincubation of AECs with an antibody directed against the membrane glycosphingolipid lactosylceramide (CDw17) results in a significant decrease in MIP-2 secretion. Preincubation of the anti-CDw17 antibody with solubilized lactosylceramide reverses this effect. Furthermore, incubation of AECs with inhibitors of glycosphingolipid biosynthesis, including N-butyldeoxyno jirimycin and d-threo-1-phenyl-2-decanoylamino-3-morpholino-1-propanol-HCl, also results in a significant decrease in AEC MIP-2 production following challenge with PCBG. These data demonstrate that PC beta-glucan induces significant production of MIP-2 from AECs and that CDw17 participates in the glucan-induced inflammatory signaling in lung epithelial cells during PC infection.
Hahn
Peter Y
PY
Thoracic Diseases Research Unit, Division of Pulmonary, Critical Care, and Internal Medicine, Mayo Clinic and Foundation, Rochester, Minnesota 55905, USA.
Evans
Scott E
SE
Kottom
Theodore J
TJ
Standing
Joseph E
JE
Pagano
Richard E
RE
Limper
Andrew H
AH
D000818:Animals; D015703:Antigens, CD / Q000378:metabolism*; D002473:Cell Wall / Q000378:metabolism*; D054426:Chemokine CXCL2; D019743:Chemokines, CXC; D004847:Epithelial Cells / Q000378:metabolism; D005936:Glucans / Q000378:metabolism*; D036341:Intercellular Signaling Peptides and Proteins; D007790:Lactosylceramides / Q000378:metabolism*; D015846:Monokines / Q000235:genetics / Q000378:metabolism*; D011010:Pneumocystis / Q000378:metabolism*; D011650:Pulmonary Alveoli / Q000166:cytology / Q000378:metabolism*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley
D015703:Antigens, CD; C499706:CXCL2 protein, human; D054426:Chemokine CXCL2; D019743:Chemokines, CXC; D005936:Glucans; D036341:Intercellular Signaling Peptides and Proteins; D007790:Lactosylceramides; D015846:Monokines; D012333:RNA, Messenger; C009744:CDw17 antigen