Effect of Autoantibodies to Erythropoietin Receptor in Systemic Lupus Erythematosus with Biopsy-proven Lupus Nephritis

Objective. We examined the clinical significance of autoantibodies to the erythropoietin receptor ( EPOR) in patients with systemic lupus erythematosus ( SLE) who had biopsy-proven lupus nephritis ( LN). Methods. Forty-six Japanese patients with SLE with LN who had undergone renal biopsy during 1993-2014 were enrolled in this study and followed for a mean of 83 months. Sera from those patients were screened for anti-EPOR antibodies using ELISA. Results. Anti-EPOR antibodies were detected in 18 ( 39%) of the 46 patients with SLE with anemia. Anti-EPOR antibodies were associated with low hemoglobin concentrations and reticulocytopenia. In addition, anti-EPOR antibodies were positively correlated with SLE disease activity, even though serum levels of the complement factors 3 and 4 did not differ between the 2 groups. In patients with International Society of Nephrology/Renal Pathology Society 2003 class IV LN, anti-EPOR antibodies were associated with active lesions including cellular crescents in glomeruli. Decrease in renal function was more frequently observed in patients without complete or partial renal response than in patients with it, and serum levels of the antibodies as well as renal response to treatment were significant risk factors for progression of renal dysfunction. Conclusion. The present study suggests that anti-EPOR antibodies might be involved in overall disease activity and active renal lesions, as well as in the impaired erythropoiesis in patients with SLE with LN. Further, the levels of anti-EPOR antibodies may be an additional predictor for renal injury.