Johannes C Nossent1, Sylvia Sagen-Johnsen2, Gunnstein Bakland2. 1. From the Bone and Joint Research Group, Department of Clinical Medicine, University of Tromsø, Tromsø, Norway.J.C. Nossent, MD, PhD, Professor of Medicine; S. Sagen-Johnsen, PhD, bioengineer; G. Bakland, MD, PhD, Bone and Joint Research Group, Department of Clinical Medicine, University of Tromsø.Dr. J.C. Nossent is currently at Sir Charles Gairdner Hospital, Perth, Australia. Dr. S. Sagen-Johnsen is currently at University in Aas, Norway. Dr. G. Bakland is at University Hospital North Norway, Tromsø. hans.nossent@uit.no. 2. From the Bone and Joint Research Group, Department of Clinical Medicine, University of Tromsø, Tromsø, Norway.J.C. Nossent, MD, PhD, Professor of Medicine; S. Sagen-Johnsen, PhD, bioengineer; G. Bakland, MD, PhD, Bone and Joint Research Group, Department of Clinical Medicine, University of Tromsø.Dr. J.C. Nossent is currently at Sir Charles Gairdner Hospital, Perth, Australia. Dr. S. Sagen-Johnsen is currently at University in Aas, Norway. Dr. G. Bakland is at University Hospital North Norway, Tromsø.
Abstract
OBJECTIVE: Despite the clinical efficacy of tumor necrosis factor inhibitors (TNFi), the manner in which TNF-α contributes to disease in patients with ankylosing spondylitis (AS) remains unresolved. We investigated the relationship between TNF-α gene promoter region polymorphism, serum TNF-α levels, and clinical phenotype. METHODS: We did a cross-sectional and longitudinal cohort study in TNFi-naive patients with AS (n = 335). Clinical data and biological samples were collected during a research visit with genotyping for TNF-α -238 A/G and -308 A/G performed by Taqman RT-PCR and TNF levels determined by sandwich ELISA. Longitudinal TNF levels were monitored in unselected patients (n = 61). RESULTS: TNF-α -308 GA/AA genotype was present in 14% and TNF-α -238 GA/AA genotype in 1% of patients. TNF-α -308 GA/AA genotype was associated with a reduced risk of uveitis and better spinal function, while TNF-α -238 GA/AA genotype was associated with later age of onset and lower erythrocyte sedimentation rate (ESR). Serum TNF-α level was lower in patients with AS (151 pg/ml) than in controls (263 pg/ml), because more patients with AS had undetectable serum TNF-α (66 vs 25%, p < 0.001). TNFi treatment did not influence serum TNF-α. There was no effect of TNF-α -308/-238 or HLA-B27 genotype on serum TNF-α or subsequent initiation of TNFi. CONCLUSION: TNF-α -238 or -308 GA/AA genotypes in patients with AS are associated with signs of less severe disease. Serum TNF-α is, however, undetectable in two-thirds of patients with AS and is not influenced by TNF-α promoter genotype or TNFi therapy. These data suggest a more significant role for TNF-α at local sites of inflammation in AS than through systemic effects.
OBJECTIVE: Despite the clinical efficacy of tumor necrosis factor inhibitors (TNFi), the manner in which TNF-α contributes to disease in patients with ankylosing spondylitis (AS) remains unresolved. We investigated the relationship between TNF-α gene promoter region polymorphism, serum TNF-α levels, and clinical phenotype. METHODS: We did a cross-sectional and longitudinal cohort study in TNFi-naive patients with AS (n = 335). Clinical data and biological samples were collected during a research visit with genotyping for TNF-α -238 A/G and -308 A/G performed by Taqman RT-PCR and TNF levels determined by sandwich ELISA. Longitudinal TNF levels were monitored in unselected patients (n = 61). RESULTS:TNF-α -308 GA/AA genotype was present in 14% and TNF-α -238 GA/AA genotype in 1% of patients. TNF-α -308 GA/AA genotype was associated with a reduced risk of uveitis and better spinal function, while TNF-α -238 GA/AA genotype was associated with later age of onset and lower erythrocyte sedimentation rate (ESR). Serum TNF-α level was lower in patients with AS (151 pg/ml) than in controls (263 pg/ml), because more patients with AS had undetectable serum TNF-α (66 vs 25%, p < 0.001). TNFi treatment did not influence serum TNF-α. There was no effect of TNF-α -308/-238 or HLA-B27 genotype on serum TNF-α or subsequent initiation of TNFi. CONCLUSION:TNF-α -238 or -308 GA/AA genotypes in patients with AS are associated with signs of less severe disease. Serum TNF-α is, however, undetectable in two-thirds of patients with AS and is not influenced by TNF-α promoter genotype or TNFi therapy. These data suggest a more significant role for TNF-α at local sites of inflammation in AS than through systemic effects.