Effect of lipopolysaccharide (LPS) and peptidoglycan (PGN) on human mast cell numbers, cytokine production, and protease composition.
BACKGROUND
Human mast cell (HuMC) maturation occurs in tissues interfacing with the external environment, exposing both mast cell progenitors and mature mast cells, to bacteria and their products. It is unknown, however, whether long- or short-term exposure to bacteria-derived toll-like receptor (TLR) ligands, such as lipopolysaccharide (LPS) or peptidoglycan (PGN), influences HuMC biology.


RESULTS
Over 6 wks of culture, LPS had minimal effect on HuMC numbers but increased CD117, tryptase and chymase expression. PGN inhibited HuMC development. For mature mast cells, LPS in the presence of rhSCF (10 ng/ml) increased CD117, tryptase, chymase and carboxypeptidase expression, primarily in CD117low HuMC. LPS decreased FcepsilonRI expression and beta-hexosaminidase release; but had no effect on LTC4 and PGD2 production. PGN reduced HuMC numbers; and CD117 and tryptase expression. IL-1beta and IL-6 (in addition to IL-8 and IL-12) were detected in short-term culture supernatants of LPS treated cells, and reproduced the increases in CD117, tryptase, chymase, and carboxypeptidase expression observed in the presence of LPS. Comparative studies with mouse bone marrow-derived mast cells from wild type, but not TLR4 knockout mice, showed increases in mRNA of mouse mast cell chymases MMCP-1, MMCP-2 and MMCP-4.


CONCLUSIONS
PGN inhibits HuMC growth, while LPS exerts its primary effects on mature HuMC by altering cytokine production and protease composition, particularly at low concentrations of SCF. These data demonstrate the ability of bacterial products to alter HuMC mediator production, granular content, and number which may be particularly relevant at mucosal sites where HuMC are exposed to these products.
Kirshenbaum
Arnold S
AS
Laboratory of Allergic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892, USA. akirshenba@niaid.nih.gov
Swindle
Emily
E
Kulka
Marianna
M
Wu
Yalin
Y
Metcalfe
Dean D
DD
D000818:Animals; D002268:Carboxypeptidases / Q000378:metabolism; D002454:Cell Differentiation / Q000187:drug effects* / Q000276:immunology; D049109:Cell Proliferation / Q000187:drug effects; D002478:Cells, Cultured; D053818:Chymases / Q000378:metabolism; D016207:Cytokines / Q000378:metabolism; D005434:Flow Cytometry; D005786:Gene Expression Regulation / Q000276:immunology; D006801:Humans; D017997:Leukotriene C4 / Q000378:metabolism; D008070:Lipopolysaccharides / Q000276:immunology* / Q000494:pharmacology; D008407:Mast Cells / Q000166:cytology / Q000201:enzymology* / Q000276:immunology*; D051379:Mice; D008809:Mice, Inbred C3H; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D010457:Peptidoglycan / Q000276:immunology* / Q000494:pharmacology; D019009:Proto-Oncogene Proteins c-kit / Q000235:genetics / Q000276:immunology / Q000378:metabolism; D022142:Secretory Vesicles / Q000276:immunology / Q000378:metabolism / Q000382:microbiology; D051195:Toll-Like Receptor 2 / Q000172:deficiency / Q000235:genetics / Q000276:immunology; D051197:Toll-Like Receptor 4 / Q000172:deficiency / Q000235:genetics / Q000276:immunology; D053802:Tryptases / Q000378:metabolism; D001619:beta-N-Acetylhexosaminidases / Q000378:metabolism
D016207:Cytokines; D008070:Lipopolysaccharides; D010457:Peptidoglycan; C493486:Tlr2 protein, mouse; C493487:Tlr4 protein, mouse; D051195:Toll-Like Receptor 2; D051197:Toll-Like Receptor 4; D017997:Leukotriene C4; D019009:Proto-Oncogene Proteins c-kit; D001619:beta-N-Acetylhexosaminidases; D002268:Carboxypeptidases; D053818:Chymases; D053802:Tryptases