Plasma sMer, sAxl and GAS6 levels correlate with disease activity and severity in lupus nephritis

Objective The purpose of this study is to determine whether TAM receptors and ligands associated with the activity and severity of lupus nephritis. Methods Clinical data were statistically analysed and studied in 122 SLE patients, diagnosed from 2013 to 2016 in First Hospital Affiliated to Harbin Medical University. Levels of TAM receptors and ligands in the plasma of 122 SLE patients were measured by ELISA. Renal biopsies were performed to confirm lupus nephritis (LN) by histopathology in 68 patients. The associations of TAM receptors and ligands with clinical and serological parameters were analysed in 68 LN patients. Results Amongst patients with SLE, those with LN had significantly higher plasma sMer, sAxl and GAS6 levels than those without renal involvement (P < 0.01 for all comparisons). Additional comparisons on the renal function-associated clinical parameters confirmed an indicative role of the sMer, sAXL and GAS6 levels in the cohort of patients with more severe nephritis. Patients with higher sMer, sAXL and GAS6 levels of LN patients tended to suffer from proliferative glomerulonephritis. The sAXL and GAS6 levels had a strong positive correlation with activity index (AI) in LN patients. Furthermore, there was a significant drop of the sMer, sAXL and GAS6 concentrations from the time of the biopsy to month t6, but no further decrease from months t6 to t12. Conclusions These results suggest that plasma sMer, sAxl and GAS6 can be an additional clinical marker related to the disease activity and severity in LN.