Association of Osteopontin gene single nucleotide polymorphism with Systemic Lupus Erythematosus

Introduction: Osteopontin plays an important role in the pathogenesis of Systemic Lupus Erythematosus(1) and lupus nephritis. OPN may influence the autoimmune disease, SLE through its immunoregulatory effects, enhancing the pro-inflammatory Th1 cell response and inhibiting the Th2 responses.(2,3) We carried out this study to determine the association of osteopontin gene 9250 C→T polymorphism and increased plasma osteopontin activity with systemic lupus erythematosus. Aim: The aim of the study was 1) To determine the association of single nucleotide polymorphism at 9250 C→T in exon 7 of OPN gene among the patients with SLE (with and without nephritis) and healthy controls. 2) To assess the plasma OPN activity among study groups and correlate their level with the genotype. Materials and Method: The study population includes Group 1A: 50 SLE patients with lupus nephritis, Group 1B:50 SLE patients without lupus nephritis, Group 2: 50 age and sex matched healthy individuals. OPN gene 9250 polymorphism was detected by polymerase chain reaction and restriction fragment length polymorphism (PCR-RFLP). Plasma Osteopontin level was estimated by ELISA. Results: A significant difference was observed in the frequencies of OPN gene 9250 T allele between the SLE patients with nephritis and the controls (72% vs 33%, P<0.05). Highest level (305.79ng/mL) of OPN activity in TT genotype, lowest level (96.42ng/mL) in CC genotype and intermediate level(187.84ng/mL) in CT genotype was observed in our study with significant statistical difference(p value<0.001). Conclusion: There was a significant association between OPN gene 9250 C→T polymorphism and increased plasma OPN level with SLE.