Polymorphism of genes involved in methotrexate pathway: Predictors of response to methotrexate therapy in Indian rheumatoid arthritis patients.

INTRODUCTION: The adenosine pathway is one of the ways through which methotrexate (MTX) ameliorates inflammation. We therefore explored an association of polymorphism of genes involved in adenosine and MTX metabolic pathways with response to MTX. METHODS: Association of polymorphism in 7 genes (rs2236225 [MTHFD1 1958G>A], rs17602729 [AMPD1 G>A], rs1127354 [ITPA C>A], rs1431131 [TGFBR2 A>T], rs2372536 [ATIC C>G], rs11188513 [ENTPD1 C>T] and rs5751876 [ADORA2A T>C]) with efficacy of MTX was studied in Indian rheumatoid arthritis (RA) patients. The patients, classified by European League Against Rheumatology (EULAR)/American College of Rheumatology (ACR) 2010 criteria, were DMARD (disease-modifying antirheumatic drug)-naïve, with Disease Activity Score (DAS28) >3.2. After 4 months of MTX monotherapy, patients were classified as responders (R) or non-responders (NR) based on EULAR response criteria. Genotyping was done by TaqMan 5' nuclease assay and association of gene polymorphisms with response to MTX was determined by Chi-squared test. RESULTS: Two hundred and twenty-six patients (86% female, median age 40 [interquartile range, IQR = 17.25] years), with disease duration of 24 (IQR = 38.25) months and DAS28-C-reactive protein score of 4.61 (IQR = 1.34) were enrolled. After therapy, 186 patients were classified as R and 40 as NR. GG genotype of ATIC (P = .01, odds ratio [OR] 2.56, 95% CI, 1.04-6.30) and CC genotype of ITPA (P = .009, OR 1.34, 95% CI 1.02-1.76) genes were found to be associated with the response. On binary logistic regression analysis, GG genotype of ATIC and CC of ITPA genes were independent predictors of the response. CONCLUSION: Polymorphisms of ATIC and ITPA genes alone or with clinical variables were associated with response to MTX therapy in Indian RA patients.

MicroRNA-132, miR-146a, and miR-155 as potential biomarkers of methotrexate response in patients with rheumatoid arthritis.

INTRODUCTION: Rheumatoid arthritis (RA) patients have high expression levels of hsa-miR-132-3p, hsa-miR-146a-5p, and hsa-miR-155-5p in peripheral blood. We studied if baseline blood levels of these microRNAs (miRNAs) could predict response to methotrexate (MTX). METHODS: RA patients (the American College of Rheumatology (ACR)/European League Against Rheumatism (EULAR) criteria) with active disease (disease-modifying anti-rheumatic drug (DMARD)-naïve and Disease Activity Score 28 (DAS28) > 3.2) were enrolled. They were treated with MTX by gradually increasing dose up to 25 mg/week. After 4 months, the DAS28 score was calculated and EULAR response was assessed. The hsa-miR-132-3p, hsa-miR-146a-5p, and hsa-miR-155-5p levels were measured by real-time qPCR in whole-blood RNA at baseline and 4 months after therapy, using hsa-let-7a-5p as housekeeping gene. Results are expressed as median (interquartile range). RESULTS: The 94 enrolled patients (81 females) had a median age of 40 (17) years, disease duration of (24) months, and DAS28 4.61 (1.11). After 4 months of therapy, 73 were classified as responders and 21 as non-responders. Baseline levels of all three miRNAs were lower in responders than non-responders, hsa-miR-132-3p (- 8.03 (0.70) versus - 7.47 (0.85), P < 0.05), hsa-miR-146a-5p (- 5.11 (0.88) versus - 4.62 (0.90), P < 0.05), and hsa-miR-155-5p (- 7.59 (1.07) versus - 7 (0.72), P = 0.002). Receiver operating characteristic curve analysis showed that all three miRNAs were also good predictors of MTX response, showing the following values: hsa-miR-132-3p (area under curve (AUC) 0.756, P < 0.05), hsa-miR-146a-5p (AUC 0.760, P < 0.05), and hsa-miR-155-5p (AUC 0.728, P = 0.002). CONCLUSION: hsa-miR-132-3p, hsa-miR-146a-5p, and hsa-miR-155-5p are potential biomarkers of responsiveness to MTX therapy.

Myeloid-related Protein 8/14 Levels in Rheumatoid Arthritis: Marker of Disease Activity and Response to Methotrexate.

OBJECTIVE: Myeloid-related proteins (MRP) 8/14 belong to a family of calcium-binding proteins produced by myeloid cells. Baseline serum levels of MRP8/14 have been shown to predict response to biologicals in rheumatoid arthritis (RA). Because methotrexate (MTX) is the first-line therapy in RA, we studied whether MRP8/14 levels can predict response to MTX. METHODS: Patients with active RA disease who were naive to disease-modifying antirheumatic drugs were enrolled. All patients were treated with MTX only, to a maximum of 25 mg/week or the maximal tolerated dose. At 4 months, the European League Against Rheumatism response was assessed. All patients who needed rescue therapy after 2 months or who did not respond at 4 months were classified as nonresponders. RESULTS: Ninety patients were enrolled, of whom 3 discontinued MTX within 4-6 weeks, so 87 patients were analyzed [74 women, median (interquartile range; IQR) for the Disease Activity Score at 28 joints (DAS28) was 4.43 (4.1-5.1)]. The median (IQR) serum MRP8/14 level at baseline was 19.95 µg/ml (11.49-39.06). The serum MRP8/14 had good correlation with DAS28-C-reactive protein (CRP; r = 0.35, p = 0.001). The MRP8/14 levels fell significantly after 4 months of treatment (10.28 µg/ml, 5.95-16.05, p < 0.001). Among 87 patients, 69 were responders. The median (IQR) baseline level of MRP8/14 was higher among responders compared with nonresponders: 23.99 µg/ml (15.39-42.75) versus 9.58 µg/ml (6.11-24.93, p = 0.00250). The levels declined in the responders, from 23.99 µg/ml (15.39-42.75) to 10.41 µg/ml (5.83-15.61, p < 0.001), but not in the nonresponders, from 9.58 µg/ml (6.11-24.93) to 9.19 µg/ml (7.74-21.96, p = 0.687). Receiver-operation characteristic analysis showed that MRP8/14 was a better predictor of response than CRP and erythrocyte sedimentation rate, especially with early disease onset (< 1-yr duration). CONCLUSION: MRP8/14 is a good marker of disease activity in RA, and higher levels predict response to MTX.