Increased concentration of plasma TNFR1 and TNFR2 in paediatric lupus nephritis.

Background: Juvenile-onset systemic lupus erythematous (JSLE) is a debilitating condition that frequently involves the kidneys (lupus nephritis; LN). Tumour necrosis factor alpha (TNF-α), an important pro-inflammatory cytokine, is expressed locally in the kidney and correlates with LN disease activity. The aim of this study was to ascertain whether soluble receptors for TNF-α (sTNFR1/sTNFR2) are significantly increased in children with LN.

Methods: Plasma samples were collected from JSLE patients at routine review. Concentrations of sTNFR1 and sTNFR2 were measured (median; interquartile range, IQR) using enzyme-linked immunosorbent assay (ELISA) in 25 JSLE patients (seven LN) and 20 healthy controls (HCs).

Results: sTNFR2 concentration was significantly increased in JSLE (5149 pg/dl, 3413-8561) compared to HCs (3858 pg/dl, 2254-5165; p = 0.049). sTNFR1 concentration was significantly increased in active LN (n = 7, 1765 pg/dl, IQR 1133-4167) compared to inactive LN (n = 18, 1104 pg/dl, 886-1272; p = 0.018). There was a non-significant increase in sTNFR2 concentration in active LN (9829 pg/dl, 3298-21271) compared to inactive LN (4595 pg/dl, 3345-6993; p = 0.146). sTNFR1 concentration correlated moderately with sTNFR2 (r = 0.66, p < 0.001). sTNFR2 demonstrated strong positive correlations with ESR (r = 0.941, p < 0.01) and anti-dsDNA antibodies (r = 0.998, p = 0.041). Both receptors also positively correlated with creatinine (TNFR1 r = 0.81, p < 0.001; TNFR2 r = 0.50, p = 0.015) and urinary albumin creatinine ratio (TNFR1 r = 0.64, p < 0.01; TNFR2 r = 0.63, p < 0.01).

Conclusions: These data indicate that sTNFR1 and sTNFR2 concentrations are elevated in LN and may reflect renal activity. These results provide basis for further investigation into the pathological pathways underlying LN.