IL-10 enhances MD-2 and CD14 expression in monocytes and the proteins are increased and correlated in HIV-infected patients.
Soluble proteins that bind LPS, like myeloid differentiation-2 (MD-2) and CD14, have essential roles in regulating LPS signaling through TLR4. During a gram-negative bacterial infection, the host may control the response by adjusting the levels of soluble MD-2 and CD14. To address the surface expression of MD-2 on human leukocytes, we developed a mAb, IIC1, that recognized MD-2 both free and when bound to TLR4. MD-2 was found on the surface of freshly isolated monocytes, on a subpopulation of CD19(+) B-cells and on CD15(+) neutrophils. LPS transiently reduced the MD-2 levels on monocytes, which is most likely due to endocytosis of the LPS receptor complex since MD-2 colocalized with TLR4 in early endosomes after LPS stimulation. In the absence of LPS, MD-2 partly colocalized with TLR4 in Golgi trans and medial compartments. Cultivating monocytes for 18-20 h resulted in loss of MD-2 expression on the surface, which was reversed either by LPS or IL-10. Furthermore, addition of IL-10, but not LPS, resulted in a considerable increase in mRNA for both MD-2 and CD14. Using ELISA, we demonstrated that IL-10 had a profound dose- and time-related effect on the release of soluble MD-2 and soluble CD14 from monocytes. In HIV-infected patients, the amounts of MD-2, CD14, and IL-10 increased significantly in the patient group with AIDS. Of interest, we found that IL-10, CD14, and MD-2 levels were positively correlated, suggesting that IL-10 may be a driving force for increased release of MD-2 and CD14 during systemic inflammation.
Sandanger
Øystein
Ø
Norwegian University of Science and Technology, Institute of Cancer Research and Molecular Medicine, Trondheim, Norway.
Ryan
Liv
L
Bohnhorst
Janne
J
Iversen
Ann-Charlotte
AC
Husebye
Harald
H
Halaas
Øyvind
Ø
Landrø
Linn
L
Aukrust
Pål
P
Frøland
Stig S
SS
Elson
Greg
G
Visintin
Alberto
A
Øktedalen
Olav
O
Damås
Jan Kristian
JK
Sundan
Anders
A
Golenbock
Douglas
D
Espevik
Terje
T
D000328:Adult; D000818:Animals; D000911:Antibodies, Monoclonal / Q000378:metabolism; D001666:Binding Sites, Antibody; D016466:CHO Cells; D002460:Cell Line; D006224:Cricetinae; D003412:Cricetulus; D005260:Female; D015658:HIV Infections / Q000276:immunology* / Q000378:metabolism*; D006801:Humans; D018836:Inflammation Mediators / Q000502:physiology; D016753:Interleukin-10 / Q000097:blood / Q000502:physiology*; D018950:Lipopolysaccharide Receptors / Q000096:biosynthesis* / Q000097:blood / Q000235:genetics; D051218:Lymphocyte Antigen 96 / Q000096:biosynthesis* / Q000097:blood / Q000235:genetics; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D009000:Monocytes / Q000276:immunology* / Q000378:metabolism*; D012333:RNA, Messenger / Q000096:biosynthesis; D015854:Up-Regulation / Q000276:immunology*
D000911:Antibodies, Monoclonal; D018836:Inflammation Mediators; C495377:LY96 protein, human; D018950:Lipopolysaccharide Receptors; D051218:Lymphocyte Antigen 96; D012333:RNA, Messenger; D016753:Interleukin-10