Tubulointerstitial nephritis in cases of lupus nephritis: An experience from a tertiary care referral center of Eastern India

Abstract

Context: Up to 60% of patients with systemic lupus erythematosus develop lupus nephritis (LN). Tubulointerstitial nephritis (TIN) includes interstitial inflammation, tubulitis, tubular atrophy (TA), and interstitial fibrosis. These are considered independent risk factors for renal outcome. Aims: To evaluate the occurrence of TIN in LN and to correlate it with clinical and histopathological variables and renal outcome. Settings and Design: It was a prospective, single-center study. Subjects and Methods: One hundred and thirty-two LN cases were evaluated. Light microscopic scoring of interstitial inflammation, fibrosis, and TA was done as follows: 0 (nil); 1+ (mild - <25% of the area of observed cortex); 2+ (moderate - >25% to 50% of the area of observed cortex); 3+ (severe - >50% of the area of observed cortex). For direct immunofluorescence study, fluorescein isothiocyanate-conjugated polyclonal rabbit antisera against human IgG, IgA, IgM, C3c, C1q, kappa, and lambda antibodies (DAKO, Germany) were used. Statistical Analysis Used: Statistical software GraphPad Prism version 6.1. Results: Significant TIN was present in 6% of cases associated with high National Institutes of Health activity and chronicity indices irrespective of the modified International Society of Nephrology and Renal Pathology Society class of LN. In the cases where inflammation and fibrosis are marked, significantly raised serum creatinine, low estimated glomerular filtration rate, high 24-h urinary protein excretion, and reduced survival without any complete remission were seen. Severe interstitial and tubular inflammations without chronicity were also associated with low survival rate due to frequent relapse and significant hypertension. Conclusions: Activity and chronicity indices describing TIN components become essential to predict the survival, therapeutic response, and disease prognosis in LN.