Background: Inflammation is implicated in cardiovascular disease (CVD) and mortality in end-stage renal failure (ESRF). Its importance in early renal disease is yet to be defined.
Methods: Serum levels of systemic and vascular inflammatory markers in early IgA nephropathy (IgAN) and control subjects were measured and related to renal function and vascular risk factors. A parallel study in type 1 diabetes mellitus subjects with (T1DM Nx) and without nephropathy (T1DM No Nx) was performed.
Results: Fifty-one IgAN patients aged 46+/-2 years (mean+/-SEM), calculated creatinine clearance (CrCl) 88+/-5 ml/min, were compared with 51 matched control subjects. Forty-six T1DM Nx patients aged 40+/-2 years, CrCl 84+/-5 ml/min, and 73 T1DM No Nx patients aged 38+/-2 years were also compared. High sensitivity C-reactive protein (hsCRP) was elevated in IgAN, T1DM Nx and T1DM No Nx patients compared with controls [4.2+/-0.6 (P < 0.001), 4.1+/-0.6 (P < 0.001), 2.6+/-0.4 (P < 0.05) vs 1.6+/-0.3 mg/l]. Levels in T1DM Nx patients were higher than in T1DM No Nx patients (P < 0.05). Inflammation and vascular dysfunction as measured by pulse pressure (PP) were related. HsCRP correlated with PP in IgAN and T1DM Nx (r = 0.47, P = 0.001; r = 0.40, P < 0.05). PP was the strongest independent predictor of hsCRP in IgAN (T = 2.45, P < 0.001), while body mass index (T = 7.83, P < 0.001) was the strongest predictor in T1DM Nx. Endothelial cell adhesion molecules were increased in T1DM Nx > IgAN > T1DM No Nx vs controls: soluble vascular adhesion molecule-1 (sVCAM-1) 760+/-30 (P < 0.001) > 663+/-34 (P = 0.001) > 601+/-21 (P < 0.05) vs 536+/-15 ng/ml; soluble intracellular adhesion molecule-1 (sICAM-1) 320+/-8 (P < 0.001) > 313+/-13 (P < 0.001) > 307+/-8 (P < 0.001) vs 244+/-6 ng/ml. sVCAM-1 levels were higher in T1DM Nx than in T1DM No Nx, P < 0.001. In IgAN and T1DM Nx, hsCRP correlated with sICAM-1 (r = 0.33, P = 0.017; r = 0.37; P = 0.017). sVCAM-1 was related to renal function in IgAN and T1DM Nx: serum cystatin C (r = 0.63, P < 0.001: r = 0.425, P = 0.002), and urine protein:creatinine ratio in IgAN (r = 0.48; P = 0.001).
Conclusions: Systemic and vascular markers of inflammation are increased in early renal disease and relate to renal dysfunction and cardiovascular risk factors. Inflammation may be a common process in various renal diseases and may link and accelerate renal dysfunction and CVD.