Nephritogenic anti-DNA antibodies regulate gene expression in MRL/lpr mouse glomerular mesangial cells.
OBJECTIVE
Lupus-associated IgG anti-double-stranded DNA antibodies are thought to be pathogenic in the kidney due to cross-reaction with glomerular antigens, leading subsequently to immune complex formation in situ and complement activation. We undertook this study to determine if pathogenic anti-DNA antibodies may also contribute to renal damage by directly influencing mesangial gene expression.


METHODS
Complementary DNA microarray gene profiling was performed in primary mesangial cells (derived from lupus-prone MRL/lpr mice) treated with pathogenic, noncomplexed anti-DNA antibodies. Significant gene up-regulation induced by anti-DNA antibodies as determined by microarray analysis was further investigated by real-time polymerase chain reaction and methods to detect the relevant proteins. Induction of proinflammatory genes by pathogenic antibodies was confirmed by comparing gene expression in glomeruli of old versus young MRL/lpr mice, and by antibody injection in vivo.


RESULTS
Pathogenic, but not nonpathogenic, antibodies significantly induced a number of transcripts, including CXCL1/KC, LCN2, iNOS, CX3CL1/fractalkine, SERPINA3G, and IkappaBalpha ("marker genes"). Blocking of Fcgamma receptors or using Fcgamma chain-knockout mesangial cells had no effect on the gene regulation effect of the pathogenic antibody R4A, indicating a non-Fc-dependent mechanism. The glomerular expression of these marker genes increased over time with the development of glomerular antibody deposition and active nephritis in MRL/lpr mice. Moreover, injection of R4A into SCID mice in vivo significantly up-regulated glomerular marker gene expression.


CONCLUSIONS
These findings indicate that the renal pathogenicity of anti-DNA antibodies may be attributed in part to their ability to directly modulate gene expression in kidney mesangial cells through both Fc-dependent and non-Fc-dependent mechanisms.
Qing
Xiaoping
X
Division of Rheumatology, Forchheimer 701N, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY 10461, USA.
Zavadil
Jiri
J
Crosby
Michelle B
MB
Hogarth
Mark P
MP
Hahn
Bevra H
BH
Mohan
Chandra
C
Gilkeson
Gary S
GS
Bottinger
Erwin P
EP
Putterman
Chaim
C
D000209:Acute-Phase Proteins / Q000235:genetics / Q000378:metabolism; D000818:Animals; D000974:Antibodies, Antinuclear / Q000009:adverse effects* / Q000494:pharmacology*; D002478:Cells, Cultured; D054428:Chemokine CX3CL1; D054360:Chemokine CXCL1; D020523:Chemokines, CX3C / Q000235:genetics / Q000378:metabolism; D019743:Chemokines, CXC / Q000235:genetics / Q000378:metabolism; D005260:Female; D020672:I-kappa B Proteins / Q000235:genetics / Q000378:metabolism; D036341:Intercellular Signaling Peptides and Proteins / Q000235:genetics / Q000378:metabolism; D007674:Kidney Diseases / Q000139:chemically induced / Q000503:physiopathology; D000071068:Lipocalin-2; D054834:Lipocalins; D020945:Lupus Vasculitis, Central Nervous System / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism; D050527:Mesangial Cells / Q000187:drug effects / Q000378:metabolism* / Q000473:pathology; D051379:Mice; D008807:Mice, Inbred BALB C; D019463:Mice, Inbred MRL lpr / Q000235:genetics*; D018345:Mice, Knockout; D016513:Mice, SCID; D000072000:NF-KappaB Inhibitor alpha; D052247:Nitric Oxide Synthase Type II / Q000235:genetics / Q000378:metabolism; D011518:Proto-Oncogene Proteins / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D015843:Serpins / Q000235:genetics / Q000378:metabolism; D015854:Up-Regulation / Q000187:drug effects* / Q000502:physiology
D000209:Acute-Phase Proteins; D000974:Antibodies, Antinuclear; C515538:CX3CL1 protein, human; C475829:CXCL1 protein, human; D054428:Chemokine CX3CL1; D054360:Chemokine CXCL1; D020523:Chemokines, CX3C; D019743:Chemokines, CXC; C515539:Cx3cl1 protein, mouse; D020672:I-kappa B Proteins; D036341:Intercellular Signaling Peptides and Proteins; C489506:LCN2 protein, human; D000071068:Lipocalin-2; D054834:Lipocalins; D008565:Membrane Proteins; C000606204:NFKBIA protein, human; C000606205:Nfkbia protein, mouse; D011518:Proto-Oncogene Proteins; D012333:RNA, Messenger; C490400:Serpina3k protein, mouse; D015843:Serpins; D000072000:NF-KappaB Inhibitor alpha; D052247:Nitric Oxide Synthase Type II