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E.V. Nguyen, S. Mareninov, R.D. Levinson, M. Awazu, L.K. Gordon; Tubulointerstitial Nephritis and Uveitis Syndrome (TINU): Seropositivity Against a Retinal Protein . Invest. Ophthalmol. Vis. Sci. 2003;44(13):4608.
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Purpose: IgG seroreactivity against a 125 kDa kidney protein was identified in a 13-year-old patient with Tubulointerstitial Nephritis and Uveitis (TINU) Syndrome. The purpose of this study was to determine if this serum also demonstrated reactivity against an ocular antigen. Methods: Identification of candidate TINU-associated ocular antigens was performed using serum with known reactivity against a 125 kDa protein expressed in kidney cytoplasmic proximal tubules and cortical distal tubules. Microdissected human ocular tissues, including ciliary body, retina, retinal pigment epithelium (RPE) and choroid, and sclera, were used as a source of tissue-specific protein. These tissue extracts were analyzed by Western blots for antigen expression using the TINU serum and normal, age and ethnicity-matched controls. Results: The TINU serum demonstrated reproducible and specific reactivity solely with the human retinal extract, not with ciliary body, retinal pigment epithelium (RPE) and choroid, or sclera. This reactivity was not identified using the control serum. Two distinct candidate antigens were observed, one at about 125 kDa, similar to that observed in the kidney extracts. A second candidate was observed at about 52 kDa. Although reactivity with the retinal extract was not initially expected, review of the patient’s clinical course and fluorescein angiography revealed active retinal vasculitis. Conclusion: Previous studies from a Japanese female patient with TINU syndrome demonstrated serum reactivity with a kidney cytoplasmic protein of approximately 125 kDa. Serum from the same individual demonstrated a similar reactivity specific to human retinal extract. It is plausible that a shared antigen, expressed in both the kidney and the eye, is a target of inflammation in this patient. Identification of the protein and characterization of its role as an antigen in other patients with TINU may contribute to the understanding of TINU pathogenesis.
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