H-2g, a glucose analog of blood group H antigen, mediates mononuclear cell recruitment via Src and phosphatidylinositol 3-kinase pathways.
OBJECTIVE
Monocyte recruitment by proinflammatory cytokines is a hallmark of rheumatoid arthritis (RA). Lewis(y-6) and H (Le(y)/H) are blood group antigens up-regulated on RA synovial endothelium. We have previously shown that both soluble Le(y)/H and a glucose analog of H, H-2g, are angiogenic and mediateleukocyte-endothelial adhesion via induction of intercellular adhesion molecule 1. We hypothesized that soluble Le(y)/H plays an important role in monocyte recruitment in RA.


METHODS
We examined the role of H-2g in monocyte chemotaxis in vitro. We used an RA synovial tissue (ST)-SCID mouse chimera model to evaluate the role of H-2g in monocyte recruitment in vivo. We used Western blots to examine signaling molecules activated by H-2g in monocytes.


RESULTS
H-2g induced human monocyte migration in vitro, which was mediated by Src and phosphatidylinositol 3-kinase (PI 3-kinase), since inhibitors and antisense oligodeoxynucleotides (ODNs) of Src and PI 3-kinase significantly decreased H-2g-induced monocyte migration (P < 0.05). H-2g significantly increased mononuclear cell (MNC) homing in vivo into an RA ST-SCID mouse chimera (P < 0.05). Transfection of MNCs with Src antisense ODNs blocked H-2g-induced MNC recruitment into the RA ST-SCID mouse chimera. Additionally, H-2g induced marked phosphorylation of protein kinase CalphaI/betaII (PKCalphaI/betaII), Src, IkappaBalpha, and Akt in monocytes. Src, Akt, and NF-kappaB were shown to be downstream targets of PKCalphaI/betaII, since an inhibitor of PKCalphaI/betaII reduced H-2g-mediated phosphorylation of Src, Akt, and NF-kappaB in monocytes.


CONCLUSIONS
These data suggest that H-2g may be a novel mediator of monocyte recruitment in chronic inflammatory diseases like RA.
Amin
M Asif
MA
Department of Internal Medicine/Division of Rheumatology, University of Michigan Medical School, Ann Arbor, MI 48109-2200, USA. maamin@med.umich.edu
Ruth
Jeffrey H
JH
Haas
Christian S
CS
Pakozdi
Angela
A
Mansfield
Pamela J
PJ
Haghshenas
Jafar
J
Koch
Alisa E
AE
D000017:ABO Blood-Group System / Q000502:physiology*; D000818:Animals; D001172:Arthritis, Rheumatoid / Q000473:pathology; D002465:Cell Movement / Q000187:drug effects; D002633:Chemotaxis / Q000187:drug effects; D002678:Chimera; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005947:Glucose / Q000737:chemistry; D006183:H-2 Antigens / Q000737:chemistry / Q000502:physiology*; D006801:Humans; D007963:Leukocytes, Mononuclear / Q000187:drug effects* / Q000473:pathology; D051379:Mice; D016513:Mice, SCID; D020319:Oligodeoxyribonucleotides, Antisense / Q000494:pharmacology; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism*; D011493:Protein Kinase C / Q000378:metabolism; D064546:Protein Kinase C beta; D051571:Protein Kinase C-alpha / Q000378:metabolism; D015398:Signal Transduction / Q000502:physiology*; D013583:Synovial Membrane / Q000473:pathology; D019061:src-Family Kinases / Q000378:metabolism*
D000017:ABO Blood-Group System; D004791:Enzyme Inhibitors; D006183:H-2 Antigens; D020319:Oligodeoxyribonucleotides, Antisense; D019869:Phosphatidylinositol 3-Kinases; D019061:src-Family Kinases; D011493:Protein Kinase C; D064546:Protein Kinase C beta; D051571:Protein Kinase C-alpha; D005947:Glucose