To investigate the associations of serum amyloid A protein (SAA) and soluble tumor necrosis factor receptors 1 and 2 (sTNF-R1 and sTNF-R2) with diabetic retinopathy (DR) in Hispanics.
Prospective, nonrandomized, cross-sectional, family-based observational cohort study.
Four hundred seventy-three Hispanics type II diabetic subjects, in families ascertained via proband with DR.
Levels of SAA, sTNF-R1, and sTNF-R2 were measured with enzyme-linked immunosorbent assay (ELISA). DR was assessed by fundus photography and graded using modified Airlie House classification.
Main Outcome Measures
Levels of SAA, sTNF-R1, and sTNF-R2 to severity of DR with and without covariates.
A direct association of sTNF-R1 (2.37±0.13, 2.15±0.09, 3.09±0.24, 3.25±0.46, 5.02±0.61 ng/ml; p<0.0001) and sTNF-R2 (6.04±0.20, 6.25±0.52, 7.96±0.70, 8.14±1.13, 14.83±1.68 ng/ml; p<0.0001) was found for no DR, mild non-proliferative DR (NPDR), moderate NPDR, severe NPDR, and proliferative DR (PDR), respectively. These associations remained significant after adjusting for age, gender, body mass index, hemoglobin A1c, diabetes duration, systolic blood pressure, and serum creatinine (p<0.0001 for sTNF-R1 and p=0.0004 for sTNF-R2). A similar pattern was observed when we adjusted for urinary albumin-to-creatinine ratio in place of serum creatinine (p=0.005 for sTNF-R1 and p=0.02 for sTNF-R2).
Levels of sTNF-R1 and sTNF-R2 are highly correlated with severity of DR, suggesting that inflammation and insulin resistance may play a critical role in the development of DR. These may be useful biomarkers for DR, aiding in etiologic studies, and possibly in identifying at-risk patients for active intervention.