Anti-DNA antibody induction of protein kinase C phosphorylation and fibronectin synthesis in human and murine lupus and the effect of mycophenolic acid.
OBJECTIVE
To examine fibronectin (FN) expression in human lupus nephritis and the effect of anti-DNA antibodies on transforming growth factor beta1 (TGFbeta1) and FN synthesis in cultured human mesangial cells. The effects of mycophenolic acid (MPA) on this pathway, and the effects of mycophenolate mofetil (MMF) treatment in (NZB x NZW)F(1)/J mice were also studied.


METHODS
Immunohistochemical analyses of renal biopsy samples from patients with active diffuse proliferative lupus nephritis were performed. Cultured human mesangial cells were incubated with human polyclonal anti-DNA antibodies, with or without MPA. (NZB x NZW)F(1)/J mice with active nephritis were randomized to receive either MMF (100 mg/kg/day) or vehicle treatment for 12 weeks.


RESULTS
Glomerular FN expression was increased in patients with lupus nephritis, and it colocalized with IgG deposition. Anti-DNA antibodies induced protein kinase Calpha (PKCalpha), PKCbetaI, and PKCbetaII activation, increased levels of bioactive TGFbeta1, and increased FN synthesis in human mesangial cells (P < 0.001 for each comparison versus control conditions). Pretreatment of anti-DNA antibodies with exogenous DNA reduced their cellular binding and abrogated their induction of TGFbeta1 and FN synthesis. Inhibition of PKC activation in human mesangial cells prior to anti-DNA antibody stimulation had no effect on cell proliferation, but resulted in significantly reduced antibody-mediated TGFbeta1 secretion and FN synthesis. MPA treatment down-regulated PKCalpha, PKCbetaI, and PKCbetaII phosphorylation, reduced levels of TGFbeta1 bioactivation, and decreased FN synthesis and deposition into the extracellular matrix. MMF treatment in (NZB x NZW)F(1)/J mice resulted in a reduction in glomerular IgG deposition, PKC activation, and FN expression, as well as an amelioration of proteinuria.


CONCLUSIONS
Human polyclonal anti-DNA antibodies induce TGFbeta1 and FN synthesis in human mesangial cells through PKC activation, which is inhibited by MPA.
Yung
Susan
S
University of Hong Kong, Queen Mary Hospital, Hong Kong, China.
Zhang
Qing
Q
Zhang
Chen Zhu
CZ
Chan
Kwok Wah
KW
Lui
Sing Leung
SL
Chan
Tak Mao
TM
D000328:Adult; D000818:Animals; D000974:Antibodies, Antinuclear / Q000494:pharmacology*; D001706:Biopsy; D002478:Cells, Cultured; D004195:Disease Models, Animal; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D005260:Female; D005353:Fibronectins / Q000378:metabolism*; D006801:Humans; D007074:Immunoglobulin G / Q000378:metabolism; D007668:Kidney / Q000187:drug effects / Q000378:metabolism* / Q000473:pathology; D008181:Lupus Nephritis / Q000188:drug therapy / Q000378:metabolism* / Q000473:pathology; D008297:Male; D050527:Mesangial Cells / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D051379:Mice; D008814:Mice, Inbred NZB; D008875:Middle Aged; D020929:Mitogen-Activated Protein Kinase Kinases / Q000378:metabolism; D009173:Mycophenolic Acid / Q000031:analogs & derivatives / Q000494:pharmacology* / Q000627:therapeutic use; D010766:Phosphorylation / Q000187:drug effects; D011493:Protein Kinase C / Q000378:metabolism*; D053773:Transforming Growth Factor beta1 / Q000378:metabolism
D000974:Antibodies, Antinuclear; D004791:Enzyme Inhibitors; D005353:Fibronectins; D007074:Immunoglobulin G; D053773:Transforming Growth Factor beta1; D011493:Protein Kinase C; D020929:Mitogen-Activated Protein Kinase Kinases; D009173:Mycophenolic Acid