MO053: Are Renal Prognostic Markers Different in Patients with Exostosin 1/2 Positive or Negative Membranous Lupus Nephritis? A Single Center Experience in Turkey

Abstract BACKGROUND AND AIMS Recently, prognostic importance of antibodies in primary membranous nephropathy is well defined. However, knowledge about antibodies related to disease activity in membranous lupus nephritis (MLN) is limited. Exostosin1 and exostosin2 (EXT1/2) are novel antibodies detected in MLN, and further studies are needed for the prognostic significance of them as a marker. The aim of this study is to determine whether renal prognostic markers differ between EXT1/2 positive and negative MLN patients. METHOD This is a single-center, retrospective and observational study. Class 5 MLN patients aged 18 or older were included in the study. Clinical characteristics, results of biochemical analysis and histopathological examination were recorded from 6 to 18 months. The end-point of the study was determined as complete remission, partial remission, need for renal replacement therapy (RRT) and exitus. Group 1: EXT1/2 positive patients. Group 2: EXT1/2 negative patients. Light, immunofluorescent and electron microscopy findings and laboratory parameters were evaluated in EXT1/2 positive and negative patients. RESULTS Group 1: n = 11 patients. Group 2: n = 7 patients. The main demographic, biochemical and histopathological characteristics of the groups were shown in Table 1. EXT1/2 negative patients, a higher number of sclerotic glomeruli, interstitial fibrosis and a higher amount of proteinuria were present than positive patients (P < 0.05). EXT1/EXT2 negative patients had significantly lower C3 and C4 levels than positive patients (P < 0.05). EXT1/EXT2 negative patients had a higher RRT or exitus rate within 18 months than positive patients (P < 0.05). In contrast, EXT1/EXT2 positive patients had a higher rate of achieving complete or partial remission within 18 months than negative patients (P < 0.05). The effect of immunosuppressive drug use other than steroids and glomerulosclerosis remission was statistically significant (P = 0.04 and P = 0.011). CONCLUSION EXT1/2 negative class 5 LMN patients have more poor renal prognostic indicators than positive patients. RRT or exitus rate is higher in EXT1/EXT2 negative patients than positive patients. However, more randomized controlled studies are needed.