Background:Classical lupus nephritis (LN) is characterized by glomerular immune complex(IC) deposition with glomerular proliferation, basement membrane destruction and cell infiltration. Non-IC mediated renal injury with thrombotic microangiopathy (TMA) was also reported in patients with systemic lupus erythematosus (SLE-renal TMA), but most studies were reported in patients with both LN and renal TMA.Objectives:In this study, clinical features and outcomes of SLE-renal TMA in absence of obvious IC in SLE patients were analyzed.Methods:Patients with glomerular TMA and/or vascular TMA in the absence of obvious subendothelial or epithelial immune deposits were screened out from 2332 biopsied in SLE patients who underwent first renal biopsy from January 2005 to August 2016. Their clinical, histological features and outcomes were retrospectively analyzed.Results:In 2332 renal biopsies obtained from SLE patients, 257 (11.0%) showed renal TMA, of which 237 showed both renal TMA and LN, and 20 biopsies had only renal TMA (SLE-renal TMA). There were 2 males and 18 females with an average age of (25 ± 10) years. The median course of SLE and LN were 3.0(1.0, 6.0) and 0.8(0.5, 1.9) months. All 20 patients deserved acute kidney injury, of which 11 (55%) needed renal replacement therapy (RRT) and 12 (60%) were nephrotic syndrome. Blood system involvement was found in all cases, including 13 cases (65.0%) with TMA triad (microvascular hemolytic anemia, thrombocytopenia and elevated lactate dehydrogenase).Pathological examination showed that 17 cases (85.0%) had both glomerular TMA and vascular TMA. Immunofluorescence and electron microscopy showed that 8 cases (40%) had no IC deposition in glomerulus and 12 cases (60%) had only IC deposition in mesangium. Acute tubulointerstitial lesions in patients requiring RRT were more serious than those no needing for RRT((43.6±24.9) %vs(21.7±20.1) %,P=0.047). The fusion range of foot process was positively correlated with proteinuria (r2= 0.347,P=0.006).All patients received high-dose methylprednisolone pulse therapy. Four patients received plasma exchange and three patients received gamma globulin, respectively. Eleven patients requiring RRT all stop RRT in a median time of 16.0 (9.0, 30.0) days. During a median follow-up of 58.0 (36.0, 92.3) months, complete remission (CR) was obtained in 15 cases, partial remission in 4 cases and no remission in 1 case. Six cases (30%) relapsed. No case died or progressed to end stage renal disease.Conclusion:Renal injury characterized by TMA is not uncommon in SLE renal biopsy cases. The clinical manifestation is special and the renal injury is serious. The renal outcome is good by intensive immunosuppressive therapy. It should be considered as a unique type of renal injury in SLE.References:[1]Moake JL. Thrombotic microangiopathies. N Engl J Med. 2002. 347(8): 589-600.[2]Anders HJ, Weening JJ. Kidney disease in lupus is not always ‘lupus nephritis’. Arthritis Res Ther. 2013. 15(2): 108.[3]Song D, Wu LH, Wang FM, et al. The spectrum of renal thrombotic microangiopathy in lupus nephritis. Arthritis Res Ther. 2013. 15(1): R12.[4]Hu WX, Liu ZZ, Chen HP, Zhang HT, Li LS, Liu ZH. Clinical characteristics and prognosis of diffuse proliferative lupus nephritis with thrombotic microangiopathy. Lupus. 2010. 19(14): 1591-8.[5]Tomov S, Lazarchick J, Self SE, Bruner ET, Budisavljevic MN. Kidney-limited thrombotic microangiopathy in patients with SLE treated with romiplostim. Lupus. 2013. 22(5): 504-9.[6]Li C, Yap D, Chan G, et al. Clinical Outcomes and Clinico-pathological Correlations in Lupus Nephritis with Kidney Biopsy Showing Thrombotic Microangiopathy. J Rheumatol. 2019 .[7]Chen MH, Chen MH, Chen WS, et al. Thrombotic microangiopathy in systemic lupus erythematosus: a cohort study in North Taiwan. Rheumatology (Oxford). 2011. 50(4): 768-75.[8]Park MH, AUID- Oho, Caselman N, Ulmer S, Weitz IC, AUID- Oho. Complement-mediated thrombotic microangiopathy associated with lupus nephritis. Blood Adv. 2018. 2(16): 2090-2094.Disclosure of Interests:None declared
Thrombotic microangiopathy in a patient with systemic lupus erythematosus and anti-factor H autoantibodies