gms | German Medical Science

Background: A non-invasive means to predict the onset and reoccurrence of lupus nephritis (LN) prior to overt renal injury is needed to optimize and individualize treatment. Colony stimulating factor 1 (CSF-1) is expressed by kidney tubules at the onset of LN, increases with disease progression and spills into the circulation in lupus-prone mice. We hypothesized that amplified expression of CSF-1 detected in the serum/urine correlates with intra-renal CSF-1 expression and histopathology, kidney disease activity and accurately predicts the onset and reoccurrence of nephritis in SLE patients.

Methods: We monitored serum/urine CSF-1 levels in individual SLE patients by comparing CSF-1 expression with histopathology (increased Mø accumulation, activity indices), clinical disease activity and predictability as deduced by conventional parameters of LN.

Results: We find that serum/urine CSF-1 levels increase in SLE patients with cutaneous, serositis and musculoskeletal disease; however, the increase in CSF-1 is far greater in LN. Moreover, an elevation in serum/urine CSF-1 levels correlated with increasing intra-renal CSF-1 expression and histopathology. Using longitudinally tracked SLE patients, we found that elevated serum CSF-1 heralds the initial onset, and a rise in serum/urine CSF-1 predicts recurrences of LN prior to clinical evidence of glomerular dysfunction and conventional serologic parameters, even in patients with other manifestations of SLE.

Conclusion: These findings indicate that serial monitoring for a rise in serum/urine CSF-1 levels in SLE patients reflects kidney histopathology, and offers the potential of predicting renal disease activity, and the onset and reoccurrences of LN more accurately than conventional laboratory parameters.