Modified C-reactive protein might be a target autoantigen of TINU syndrome.
OBJECTIVE
The cross-reactive antigen(s) of tubulointerstitial nephritis and uveitis (TINU) syndrome from renal tubulointerstitia and ocular tissue remain unidentified. The authors' recent study demonstrated that the presence of serum IgG autoantibodies against modified C-reactive protein (mCRP) was closely associated with the intensity of tubulointerstitial lesions in lupus nephritis. The study presented here investigates the possible role of IgG autoantibodies against mCRP in patients with TINU syndrome.


METHODS
mCRP autoantibodies were screened by ELISA with purified human C-reactive protein in 9 patients with TINU syndrome, 11 with drug-associated acute interstitial nephritis, 20 with IgA nephropathy, 19 with minimal change disease, 20 with ANCA-associated vasculitis, 6 with Sjogren's syndrome, and 12 with amyloidosis. mCRP expression was analyzed by immunohistochemistry in renal biopsy specimens from the 9 patients with TINU syndrome and 40 from disease controls. Frozen normal human kidney and iris were used to demonstrate co-localization of human IgG and mCRP from patients with TINU syndrome with laser scanning confocal microscopy.


RESULTS
The mCRP autoantibodies were detected in all nine patients with TINU syndrome, significantly higher than that of those with disease controls (P < 0.05). The renal histologic score of mCRP in TINU syndrome was significantly higher than that in disease controls (P < 0.05). The staining of mCRP and human IgG were co-localized in renal and ocular tissues.


CONCLUSIONS
It is concluded that mCRP might be a target autoantigen in TINU syndrome.
Tan
Ying
Y
Renal Division, Department of Medicine, Peking University First Hospital and Institute of Nephrology, Peking University Key Laboratory of Renal Disease, Ministry of Health of China, Peking, People's Republic of China.
Yu
Feng
F
Qu
Zhen
Z
Su
Tao
T
Xing
Guang-Qun
GQ
Wu
Li-Hua
LH
Wang
Feng-Mei
FM
Liu
Gang
G
Yang
Liu
L
Zhao
Ming-Hui
MH
D000293:Adolescent; D000328:Adult; D000368:Aged; D001323:Autoantibodies / Q000097:blood*; D001324:Autoantigens / Q000276:immunology*; D002097:C-Reactive Protein / Q000032:analysis / Q000276:immunology*; D005260:Female; D005455:Fluorescent Antibody Technique; D006801:Humans; D007074:Immunoglobulin G / Q000097:blood*; D007150:Immunohistochemistry; D008297:Male; D018613:Microscopy, Confocal; D008875:Middle Aged; D009395:Nephritis, Interstitial / Q000097:blood / Q000276:immunology; D014605:Uveitis / Q000097:blood / Q000276:immunology
D001323:Autoantibodies; D001324:Autoantigens; D007074:Immunoglobulin G; D002097:C-Reactive Protein
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