Ab0586 serum/ Urine Levels and Expression of Cd163 in Lupus Nephritis

Abstract

BackgroundCD163 is a glycosylated membrane protein expressed in monocytes and macrophages that phagocytize the hemoglobin/haptoglobin complex. As a result of proinflammatory stimuli, CD163 is shedded from the cell membrane and becomes soluble CD163. Therefore, it has been shown that serum (s) and urine (u) levels of soluble CD163 increase in acute or chronic inflammatory diseases. sCD163 and uCD163 are considered as potential biomarkers reflecting disease activity in patients with systemic lupus erythematosus (SLE).ObjectivesWe aimed to investigate the association of serum and urine soluble CD163 levels and renal CD163 expression with disease activity in patients with lupus nephritis (LN).MethodsSerum and urine levels of CD163 of 45 SLE patients (active renal 20, active non-renal 15, inactive 10) and 20 healthy volunteers were tested by ELISA. Control samples were taken from 12 active renal patients after six months of treatment and 30 renal biopsy specimens were examined for CD163 expression.ResultsOf 45 participants, 37 (82.2%) were female, with a median disease duration of 113 (1-436) months and a mean age of 38,9±13 (18-68) years. Both the frequency of uCD163 positivity and its levels were significantly higher in the active LN group compared to the inactive LN (p=0,007 and 0.02 respectively) and active non-renal SLE (p=0,001 and 0.023 respectively) groups (Table 1). sCD163 and uCD163 levels of 12 patients with active LN were significantly reduced after treatment (p=0,04 and p=0,006) (Figure 1). CD163+ macrophage expression in kidney biopsies of patients with active LN correlated with sCD163 (r= 0.597 and p=0.01) and uCD163 (r=0.507 and p=0.045) levels.ConclusionuCD163 is a promising biomarker that can differentiate active LN from inactive LN and active extrarenal SLE changing in line with treatment response. Correlation of both s and uCD163 with CD163+ macrophage expression in biopsies suggests that it may be used as an activity parameter in patients with lupus nephritis histopathologically. Further studies are awaited to confirm these results (This study was funded by Istanbul University with the project number TTU-2021-38289)Table 1.Serum and urine levels of CD163 across study groupsBiomarkerActive LN (n=20)Inactive LN (n=10)PExtrarenal active SLE (n=15)PHealthy control (n=20)PSerum CD163 % binding (mean+SD)26,7±17,622,8±18,80,5422,06±9,60,317,03±15,60,4Serum CD163 positivity n (%)%75%500,2%730,9%400,05Urine CD163 % binding (mean+SD)3,9±2,42,6±0,040,022,5±0,10,0232,6±0,50,03Urine CD163 positivity n (%)%90%400,007%330,001%12<0,001LN lupus nephritis, SLE systemic lupus erythematosus, SD standard deviationREFERENCES:NIL.Acknowledgements:NIL.Disclosure of InterestsNone Declared.