Israel Medical Association Journal

Background: Methotrexate is the most frequently administered first-line treatment for rheumatoid arthritis (RA). The disease-modifying effects of methotrexate are mainly associated with enhanced release of free adenosine. The downstream anti-inflammatory effects of adenosine are mediated via its binding to adenosine receptor 2A (ADORA2A) and 3 (ADORA3). Many clinically important single nucleotide polymorphisms (SNPs) were reported in ADORA2A and ADORA3 genes.

Objectives: To investigate whether tagging ADORA2A and ADORA3 polymorphisms influences methotrexate treatment in RA.

Methods: In total, 212 RA patients treated with methotrexate were genotyped for tagging ADORA2A (rs2298383, rs8141793, rs2236624, rs5751876, rs35320474, and rs17004921) and ADORA3 SNPs (rs2298191, rs1544223, rs78594984, rs35511654, rs2229155, rs3393, and rs3394).

Results: RA patients who carried ADORA3 rs35511654 G allele showed a tendency toward better response to methotrexate treatment (P = 0.054). Carriers of ADORA2A polymorphic allele rs2298383 (P = 0.011), rs2236624 (P = 0.027), rs5751876 (P = 0.018), and rs35320474 (P = 0.026) were less likely to experience methotrexate induced adverse events. All associations remained significant after adjustment for clinical factors. The effects of these polymorphisms were also significant in haplotype analyses.

Conclusions: Polymorphisms in the ADORA2A gene may influence methotrexate treatment response and may be considered as a potential biomarker for methotrexate treatment in rheumatoid arthritis.

Background: Leukotriene antagonist therapy in asthmatic patients alleviates symptoms and improves exercise tolerance, however the effect of these drugs on bronchial provocation tests and exhaled nitric oxide levels are less clearly established.

Objective: To determine the effect of montelukast treatment on airway hyperresponsiveness to exercise, methacholine and adenosine-5’-monophosphate and on exhaled nitric oxide levels in steroid-naive asthmatics.

Methods: Following a 2 week run-in period, 20 mild to moderate asthmatics were enrolled in an open label 6 week trial of oral montelukast-sodium therapy. Bronchial hyperreactivity (exercise, methacholine and adenosine-5’-monophosphate challenges) and exhaled nitric oxide levels were measured before and after the 6 week period.

Results: Montelukast treatment resulted in a significant improvement in exercise tolerance: median DFEV₁ 20.0% (range 0–50) prior to treatment vs. 15.0% (range 0–50) post-treatment (P = 0.029). A significant difference was also observed for exhaled NO[1] following therapy: median NO 16.0 ppb (range 7–41) vs. 13.0 (range 4.8–26) (P = 0.016). No change was seen in baseline lung function tests (FEV₁, MEF₅₀) or in the bronchial responsiveness (PC₂₀) for methacholine and adenosine-5’-monophosphate.

Conclusions: This study demonstrates that the leukotriene antagonist, montelukast-sodium, reduces bronchial hyperreactivity in response to exercise and reduces exhaled nitric oxide levels but has little effect on bronchial responsiveness to methacholine and adenosine challenges.