The transforming growth factor-β1 gene (TGF-β1) single nucleotide polymorphism (SNP) 869T/C is associated with hypertension in patients with RA, whereas the interleukin 6 gene (IL6) –174G/C SNP is not, research suggests.
Hypertension may be responsible for some of the harmful effects of systemic inflammation on the cardiovascular system of patients with RA, say George Kitas (Russells Hall Hospital, Dudley, UK) and colleagues.
“IL-6 and TGF-β1 are important regulators of the inflammatory response,” they explain.
In some, but not all, studies, the polymorphisms IL6 –174G/C (rs1800795) and TGF-β1 869T/C (rs1982073) have been associated with hypertension in the general population.
To determine whether these polymorphisms are associated with hypertension in patients with RA, Kitas and team used real-time polymerase chain reaction and melting curve analysis to identify TGF-β1 869T/C and IL6 –174G/C in 400 RA patients and 422 non-RA controls.
The researchers report that there were no significant differences observed between RA patients and controls for the IL6 and TGF-β1 genotypes and alleles studied.
Within the RA group, there was no significant association between IL6 –174G/C and hypertension, but TGF-β1 869T allele carriers had a significantly increased prevalence of hypertension compared with CC homozygotes.
This association remained significant after adjustment for other hypertension risk factors and medication and TGF-β1 869T allele carriers had 2-fold increased odds for hypertension compared with CC homozygotes. The association was more pronounced in patients with increased systemic inflammation.
“If this finding is confirmed in prospective studies, this polymorphism could be used as a screening tool for RA patients with higher risk for developing hypertension and lead to increased surveillance and earlier treatment,” conclude Kitas and co-authors in the journal Rheumatology.