Decreased serum levels of TGF-β1 are associated with renal damage in female patients with systemic lupus erythematosus.

INTRODUCTION

Transforming growth factor β1 (TGF-β1) has a large role in the control of autoimmunity. TGF-β1 production by lymphocytes is reduced in systemic lupus erythematosus (SLE). Decreased levels of TGF-β1 might associate to disease susceptibility, activity and organ damage in SLE. However, the correlation between TGF-β1 levels and severity of renal damage in SLE has not been examined.

METHODS

The present study was undertaken to assess the serum levels of total and active TGF-β1 in 150 female patients with SLE and 31 healthy women. Simple and multiple regression analyses between TGF-β1 levels and the diseases-related variables were performed in patients with SLE.

RESULTS

Serum levels of both total and active TGF-β1 were significantly reduced in patients with SLE compared with levels in healthy controls (p < 0.01). Total TGF-β1 levels correlated positively with white blood cell, platelet counts, calculated glomerular filtration rate (GFR), and active TGF-β1 level, and inversely with erythrocyte sedimentation rate (ESR). In multiple regression analysis, ESR and platelet counts remained determinants of total TGF-β1. Total TGF-β1 levels were lower in patients with high disease activity (SLEDAI > 10) and severe organ damage (SLICC > 3). Significantly lower levels of total TGF-β1 were found in patients with severe renal damage, i.e. lower TGF-β1 in patients with 24-h urine protein over 3.5 g than in those with below 3.5 g (p < 0.05); lower TGF-β1 in patients with GFR less than 50 ml/min than in those with over 50 ml/min (p < 0.05). In contrast, active TGF-β1 only correlated with platelet counts. There was no association between renal damage and the levels of active TGF-β1.

CONCLUSION

This study demonstrates significantly reduced serum levels of both total and active TGF-β1 in women with SLE compared with healthy women. Total TGF-β1 levels are correlated negatively with ESR and positively with blood platelets. Total TGF-β1 levels were lower in SLE patients with high disease activity and severe organ damage. Importantly, the severity of the renal damage was associated with decreased serum levels of total TGF-β1, suggesting that TGF-β1 might be involved in pathogenesis of renal damage caused by lupus nephritis.