#2630 netosis is a prevalent immune process in lupus nephritis and neutrophil elastase scoring expresses the activity and severity in different classes

Abstract Background and Aims The release of NETs by activated neutrophils is known as NETosis. NETs are released not only on exposure to pathogens such as bacteria but also in sterile environments in autoimmune diseases such as lupus where they generate/trap autoantigens and aggravate inflammation. This study assesses the prevalence of neutrophil elastase (NE) as a marker of Netosis in lupus in renal biopsies and its presentation in different lupus classes. Method A cross-sectional study included 45 patients with lupus nephritis who underwent renal biopsy and were classified according to lupus class. NE was done for the detection of Netosis by immunohistochemistry. Results The prevalence of (NE) was 88.8% (40/45 cases). NE combined score with cut-off (>3) expresses moderate to severe Netosis. It allowed the detection of active proliferative lupus class III-IV with a sensitivity: 80.0%, specificity: 60.0%, PPV: 85.71%, and NPV: 50.0%. In class III-IV (N = 34 cases): NE combined score >3 was 83.3% (25/30 cases) with features: glomerular deposition >25% of the glomerulus in 60% (19/30 cases), strong intensity (+2) in 63.3% (19/30 cases), diffuse (>50% of the number of the glomeruli) 67.8% (19/28 cases). In non-proliferative lupus class II-V (N = 11 cases) NE combined score >3 was 20% (2/10 cases) and score<3 was 80% (8/10 cases) with features: glomerular deposition <25%/ faint intensity (+1)/ focal. On comparing both groups as regard NE combined score, distribution, intensity, and focal/diffuse p value was 0.0002, 0.099, 0.013, and 0.94 respectively. On redistribution of biopsies according to NE combined score >3 vs <3 there was a significant difference in activity index, distribution, intensity, and focal/diffuse p-value 0.0011, 0.0001, 0.0002, 0.0006 while non-significant for chronicity index p-value 0.08914. Conclusion NETOSIS is a prevalent immune process in lupus nephritis and NE combined score is a sensitive marker of proliferation that increases with class severity and activity.