Markers of treatment response to methotrexate in rheumatoid arthritis: where do we stand? Int J Rheumatol. 2012;2012:978396. [PMID: 22844292 PMCID: PMC3400362 DOI: 10.1155/2012/978396]

Methotrexate Polyglutamate Concentrations as a Possible Predictive Marker for Effectiveness of Methotrexate Therapy in Patients with Sarcoidosis: A Pilot Study

INTRODUCTION

Methotrexate (MTX), a folate antagonist, is often used as second-line treatment in patients with sarcoidosis. Effectiveness of MTX has large inter-patient variability and at present therapeutic drug monitoring (TDM) of MTX is not possible. Upon administration, MTX is actively transported into cells and metabolized to its active forms by adding glutamate residues forming MTXPG(n=1-5) resulting in enhanced cellular retention. In this study we address the question whether different MTXPG(n) concentrations in red blood cells (RBC) of patients with sarcoidosis after 3 months of MTX therapy correlate with response to treatment.

METHODS

We retrospectively included patients with sarcoidosis that had started on MTX therapy and from whom blood samples and FDG-PET/CT were available 3 and 6-12 months after MTX initiation, respectively. FDG-uptake was measured by SUVmax in the heart, lungs and thoracic lymph nodes. Changes in SUVmax was used to determine anti-inflammatory response after 6-12 months of MTX therapy. MTXPG(n) concentrations were measured from whole blood RBC using an LC-MS/MS method. Pearson correlation coefficients were calculated to evaluate the relationship between changes in the SUVmax and MTXPG(n) concentrations.

RESULTS

We included 42 sarcoidosis patients treated with MTX (15 mg/week); 31 with cardiac sarcoidosis and 11 with pulmonary sarcoidosis. In MTXPG3 and MTXPG4 a significant negative relation between the absolute changes in SUVmax and MTXPG(n) was found r = - 0.312 (n = 42, p = 0.047) for MTXPG3 and r = - 0.336 (n = 42, p = 0.031 for MTXPG4). The other MTXPG(n) did not correlate to changes in SUVmax.

CONCLUSION

These results suggest a relation between MTXPG(n) concentrations and the anti-inflammatory effect in patients with sarcoidosis. Further prospective validation is warranted, but if measuring MTXPG concentrations could predict treatment effect of MTX this would be a step in the direction of personalized medicine.

Drug-microbiota interactions: an emerging priority for precision medicine

Individual variability in drug response (IVDR) can be a major cause of adverse drug reactions (ADRs) and prolonged therapy, resulting in a substantial health and economic burden. Despite extensive research in pharmacogenomics regarding the impact of individual genetic background on pharmacokinetics (PK) and pharmacodynamics (PD), genetic diversity explains only a limited proportion of IVDR. The role of gut microbiota, also known as the second genome, and its metabolites in modulating therapeutic outcomes in human diseases have been highlighted by recent studies. Consequently, the burgeoning field of pharmacomicrobiomics aims to explore the correlation between microbiota variation and IVDR or ADRs. This review presents an up-to-date overview of the intricate interactions between gut microbiota and classical therapeutic agents for human systemic diseases, including cancer, cardiovascular diseases (CVDs), endocrine diseases, and others. We summarise how microbiota, directly and indirectly, modify the absorption, distribution, metabolism, and excretion (ADME) of drugs. Conversely, drugs can also modulate the composition and function of gut microbiota, leading to changes in microbial metabolism and immune response. We also discuss the practical challenges, strategies, and opportunities in this field, emphasizing the critical need to develop an innovative approach to multi-omics, integrate various data types, including human and microbiota genomic data, as well as translate lab data into clinical practice. To sum up, pharmacomicrobiomics represents a promising avenue to address IVDR and improve patient outcomes, and further research in this field is imperative to unlock its full potential for precision medicine.

Pharmacomicrobiology of Methotrexate in Rheumatoid Arthritis: Gut Microbiome as Predictor of Therapeutic Response

Rheumatoid arthritis (RA) is a disabling autoimmune disease with invasive arthritis as the main manifestation and synovitis as the basic pathological change, which can cause progressive destruction of articular cartilage and bone, ultimately leading to joint deformity and loss of function. Since its introduction in the 1980s and its widespread use in the treatment of RA, low-dose methotrexate (MTX) therapy has dramatically changed the course and outcome of RA treatment. The clinical use of this drug will be more rational with a better understanding of the pharmacology, anti-inflammatory mechanisms of action and adverse reaction about it. At present, the current clinical status of newly diagnosed RA is that MTX is initiated first regardless of the patients’ suitability. But up to 50% of patients could not reach adequate clinical efficacy or have severe adverse events. Prior to drug initiation, a prognostic tool for treatment response is lacking, which is thought to be the most important cause of the situation. A growing body of studies have shown that differences in microbial metagenomes (including bacterial strains, genes, enzymes, proteins and/or metabolites) in the gastrointestinal tract of RA patients may at least partially determine their bioavailability and/or subsequent response to MTX. Based on this, some researchers established a random forest model to predict whether different RA patients (with different gut microbiome) would respond to MTX. Of course, MTX, in turn, alters the gut microbiome in a dose-dependent manner. The interaction between drugs and microorganisms is called pharmacomicrobiology. Then, the concept of precision medicine has been raised. In this view, we summarize the characteristics and anti-inflammatory mechanisms of MTX and highlight the interaction between gut microbiome and MTX aiming to find the optimal treatment for patients according to individual differences and discuss the application and prospect of precision medicine.

Serum Exosomal miRNA-1915-3p Is Correlated With Disease Activity of Korean Rheumatoid Arthritis

BACKGROUND/AIM

It has been found that microRNAs (miRNA) affect rheumatoid arthritis (RA) pathophysiology. This study aimed to identify novel serum exosomal miRNAs related to RA disease activity in patients with an inadequate treatment response.

PATIENTS AND METHODS

The sample population comprised clinical remission (CR) and non-clinical remission (non-CR) groups of RA patients. To identify potent miRNA markers for RA disease activity, miRNA array and qPCR were performed after patient serum exosomes preparation.

RESULTS

Has-miR-1915-3p and has-miR-6511b-5p were significantly higher in the serum exosomes of the CR group. The level of serum C-reactive protein (CRP) was negatively correlated with has-miR-1915-3p level in serum exosomes.

CONCLUSION

Has-miR-1915-3p may be a potential marker for Korean RA disease activity.

The Pretreatment Gut Microbiome Is Associated With Lack of Response to Methotrexate in New-Onset Rheumatoid Arthritis

OBJECTIVE

Although oral methotrexate (MTX) remains the anchor drug for rheumatoid arthritis (RA), up to 50% of patients do not achieve a clinically adequate outcome. In addition, there is a lack of prognostic tools for treatment response prior to drug initiation. This study was undertaken to investigate whether interindividual differences in the human gut microbiome can aid in the prediction of MTX efficacy in new-onset RA.

METHODS

We performed 16S ribosomal RNA gene and shotgun metagenomic sequencing on the baseline gut microbiomes of drug-naive patients with new-onset RA (n = 26). Results were validated in an additional independent cohort (n = 21). To gain insight into potential microbial mechanisms, we conducted ex vivo experiments coupled with metabolomics analysis to evaluate the association between microbiome-driven MTX depletion and clinical response.

RESULTS

Our analysis revealed significant associations of the abundance of gut bacterial taxa and their genes with future clinical response (q < 0.05), including orthologs related to purine and MTX metabolism. Machine learning techniques were applied to the metagenomic data, resulting in a microbiome-based model that predicted lack of response to MTX in an independent group of patients. Finally, MTX levels remaining after ex vivo incubation with distal gut samples from pretreatment RA patients significantly correlated with the magnitude of future clinical response, suggesting a possible direct effect of the gut microbiome on MTX metabolism and treatment outcomes.

CONCLUSION

Taken together, these findings are the first step toward predicting lack of response to oral MTX in patients with new-onset RA and support the value of the gut microbiome as a possible prognostic tool and as a potential target in RA therapeutics.

Methotrexate Polyglutamates Analysis by Chromatography Methods in Biological Matrices: A Review

Methotrexate (MTX) is used as an immunosuppressant and antineoplastic drug in clinical practice. MTX is a parent drug and converts to MTX polyglutamates (MTXPGs) to exhibit its biological activity. Clinical studies found that MTXPG levels were associated with MTX response and toxicities, especially at low doses. Due to huge variance of MTX response and toxicities between individuals, therapeutic drug monitoring is necessary for its use in individualized therapy. Various chromatography methods coupled with ultraviolet-visible detector, fluorescence detector and mass spectrometry have been reported for MTXPG analysis in various biological matrices. The aim of this paper is to review the chromatographic based methods for the measurement of total and/or individual MTXPGs. We searched Embase, Science Direct and PubMed databases using "methotrexate polyglutamate" and "chromatography" as search terms, and found 745 articles. Of those, 14 articles were extracted for this study. The key steps for method development (sample pretreatment, parameter optimization of liquid chromatography and mass spectrometry, selection of internal standard) and validation (lower limit of quantitation, accuracy, precision, recovery, matrix effect and stability) were analyzed and summarized, which might be helpful for researchers to develop their own methods.

Effect of Biologics on Cardiovascular Inflammation: Mechanistic Insights and Risk Reduction

It is increasingly recognized that atherosclerosis and consequently cardiovascular disease (CVD) are closely linked with inflammatory processes. The latter is in the center of the pathogenic mechanism underlying autoimmune rheumatic diseases (ARD). It follows then, that optimal control of inflammation in ARDs may lead to a decrease of the accompanied CVD risk. Major trials (eg, CANTOS, CIRT), aimed at examining the possible benefits of immunomodulatory treatments in CVD, demonstrated conflicting results. On the other hand, substantial evidence is accumulating about the possible beneficial effects of biologic disease modifying antirheumatic drugs (bDMARDs) in patients with ARDs, particularly those with rheumatoid arthritis (RA). It seems that bDMARDs (some more than others) alter the lipid profile in RA patients but do not adversely affect, in most cases, the TC/HDL ratio. Favorable effects are noted for arterial stiffness and endothelial function. This is reflected in the lower risk for CVD events, seen in observational studies of RA patients treated with bDMARDs. It should be stressed that more data exist for the TNF-inhibitors than for other bDMARDs, such as tocilizumab, abatacept and rituximab. As regards the spondyloarthropathies (SpA), data are less robust. For TNF-inhibitors, effects appear to be on par with those seen in RA but no conclusions can be drawn for newer biologic drugs used in SpA (eg, IL-17 blockers). Finally, there is accumulating evidence for a beneficial effect of immunosuppressive treatment in cardiac inflammation and function in several ARDs. Introduction of newer therapeutic options in clinical practice seem to have a positive impact on CVD in the setting of ARD. This is probably due to better control of inflammation, but direct improvement in vascular pathology is also a valid hypothesis. Most data are derived from observational studies and, therefore, randomized controlled trials are needed to assess the possible favorable effect of bDMARDs on CVD outcomes.

Drug Response Diversity: A Hidden Bacterium?

Interindividual heterogeneity in response to treatment is a real public health problem. It is a factor that can be responsible not only for ineffectiveness or fatal toxicity but also for hospitalization due to iatrogenic effects, thus increasing the cost of patient care. Several research teams have been interested in what may be at the origin of these phenomena, particularly at the genetic level and the basal activity of organs dedicated to the inactivation and elimination of drug molecules. Today, a new branch is being set up, explaining the enigmatic part that could not be explained before. Pharmacomicrobiomics attempts to investigate the interactions between bacteria, especially those in the gut, and drug response. In this review, we provide a state of the art on what this field has brought as new information and discuss the challenges that lie ahead to see the real application in clinical practice.

Methotrexate impacts conserved pathways in diverse human gut bacteria leading to decreased host immune activation

Immunomodulatory drugs can inhibit bacterial growth, yet their mechanism of action, spectrum, and clinical relevance remain unknown. Methotrexate (MTX), a first-line rheumatoid arthritis (RA) treatment, inhibits mammalian dihydrofolate reductase (DHFR), but whether it directly impacts gut bacteria is unclear. We show that MTX broadly alters the human gut microbiota. Drug sensitivity varied across strains, but the mechanism of action against DHFR appears conserved between mammalian and bacterial cells. RA patient microbiotas were sensitive to MTX, and changes in gut bacterial taxa and gene family abundance were distinct between responders and non-responders. Transplantation of post-treatment samples into germ-free mice given an inflammatory trigger led to reduced immune activation relative to pre-treatment controls, enabling identification of MTX-modulated bacterial taxa associated with intestinal and splenic immune cells. Thus, conservation in cellular pathways across domains of life can result in broad off-target drug effects on the human gut microbiota with consequences for immune function.

Pharmacomicrobiomics in inflammatory arthritis: gut microbiome as modulator of therapeutic response

In the past three decades, extraordinary advances have been made in the understanding of the pathogenesis of, and treatment options for, inflammatory arthritides, including rheumatoid arthritis and spondyloarthritis. The use of methotrexate and subsequently biologic therapies (such as TNF inhibitors, among others) and oral small molecules have substantially improved clinical outcomes for many patients with inflammatory arthritis; for others, however, these agents do not substantially improve their symptoms. The emerging field of pharmacomicrobiomics, which investigates the effect of variations within the human gut microbiome on drugs, has already provided important insights into these therapeutics. Pharmacomicrobiomic studies have demonstrated that human gut microorganisms and their enzymatic products can affect the bioavailability, clinical efficacy and toxicity of a wide array of drugs through direct and indirect mechanisms. This discipline promises to facilitate the advent of microbiome-based precision medicine approaches in inflammatory arthritis, including strategies for predicting response to treatment and for modulating the microbiome to improve response to therapy or reduce drug toxicity.

Relative efficacy and safety of iguratimod monotherapy for the treatment of patients with rheumatoid arthritis: a systematic review and meta-analysis

OBJECTIVES

This study aims to compare the efficacy and the safety of the iguratimod with placebo and other disease-modifying antirheumatic drugs (DMARDs) in adults with rheumatoid arthritis.

METHODS

Two authors independently searched and selected randomized controlled trials from Cochrane library, Medline (through Pubmed), and Chinese databases, and then assessed the risk of bias (using ROB 2 tool), and graded the certainty of evidence (using the GRADEpro GDT software). We applied the RevMan 5 software for performing meta-analyses of the final consensus data.

RESULTS

We identified 12 trials involving 1938 participants. Ten trials had an overall high risk of bias. Although iguratimod had superior efficacy than placebo, the incidence of adverse events was also higher. Inferring to non-inferiority analysis with other DMARD therapy (primarily comprising methotrexate), iguratimod is likely to result in similar treatment response (20% (OR 1.04, 95% CI 0.79 to 1.36), 50% and 70% improvement in American College of Rheumatology criteria) and functional ability at 24 weeks. Although the disease state was slightly better with iguratimod (MD - 0.55, 95% CI - 0.85 to - 0.25), a clinically important improvement was not achieved. Iguratimod may have lower C-reactive protein and erythrocyte sedimentation rate values. Swollen joint count, tender joint count, pain intensity, and patient's and physician's global assessment of disease state may be comparable between the therapies. Both the therapies are likely to have similar odds (OR 0.91, 95% CI 0.67 to 1.26) of adverse events.

CONCLUSION

Our evidence suggests that iguratimod may be considered a potential alternative to methotrexate to treat rheumatoid arthritis.Key Points• The Asia Pacific League of Association for Rheumatology (APLAR) has recommended that iguratimod may be used a first-line drug for rheumatoid arthritis in specific cases.• Patients on iguratimod may have similar treatment response, functional ability, disease state, and adverse event profile at 24 weeks compared with those on methotrexate.• Iguratimod may be considered a better alternative to methotrexate in RA patients having high CRP and ESR values.• Future clinical trials in diverse population comparing the efficacy and safety of iguratimod in monotherapy or combination therapy with DMARDs (other than methotrexate) are warranted.

Association of genes ARID5B, CEBPE and folate pathway with acute lymphoblastic leukemia in a population from the Brazilian Amazon region

Acute Lymphoblastic Leukemia (ALL) is the most common childhood neoplasia. Studies have shown that susceptibility to ALL may be modulated by genetic variables. Our study investigated 21 genetic variants in the susceptibility of the population of the Brazilian Amazon region to B-cell ALL. The variants of the genes GGH, CEBPE, ARID5B, MTHFR and MTHFD1 were related to a protective effect against the development of ALL, whereas the variant of the gene ATIC was associated with a risk effect. The results suggest that genetic variants analyzed modulate of the risk of developing ALL in the studied population.

Baseline adenosine receptor mRNA expression in blood as predictor of response to methotrexate therapy in patients with rheumatoid arthritis

Methotrexate (MTX) reduces inflammation by increasing extracellular adenosine levels in rheumatoid arthritis (RA) patients. Adenosine acts via G-protein coupled receptors; ADORA1, ADORA2a, ADORA2b and ADORA3. We studied if baseline expression of whole blood adenosine receptors can predict response to MTX. RA patients [American College of Rheumatology/European-League-Against-Rheumatism (EULAR) 2010 criteria], Disease modifying anti-rheumatic drug (DMARD) naïve with active disease [Disease Activity Score 28 (DAS28) > 3.2] were enrolled. Blood samples were collected at baseline (n = 100) and at 4 months after therapy (n = 50). Patients were treated with MTX monotherapy. Based on EULAR response, patients were categorized into three groups i.e. good, moderate and non-responders. Adenosine receptors gene expression (ADORA1, ADORA2a, ADORA2b and ADORA3) in whole-blood RNA was measured using real-time PCR. HPRT1 was used as housekeeping gene. Receptor expression at baseline was correlated with response to MTX. All values are expressed as median (interquartile range). Hundred patients [87% females; age 40 (18) years]; duration of disease 24 (24.75) months; DAS28 4.7 (1.25) were enrolled. Fifty-one were classified as good, 28 moderate and 21 as non-responders. No expression of ADORA1 and ADORA2b was detected. Significant difference was observed in the expression levels of ADORA3 between good vs non-responder (P = 0.03) and moderate vs non-responder (P = 0.002). On ROC curve analysis, ADORA3 with cut-off value of less than - 0.60 (ΔCt) predicted non-response to MTX treatment (AUC: 0.7, P = 0.006). ADORA3 mRNA levels in whole blood may serve as a biomarker of response to MTX.

The possible role of heat shock protein-70 induction in collagen-induced arthritis in rats

AIM

This study aimed to evaluate the possible role of heat shock protein-70 (HSP70) induction by 17-allylaminodemethoxygeldanamycin (17-AAG) in collagen-induced arthritis in rats.

MATERIAL AND METHODS

Male Wistar rats were divided into five groups (n = 10/group) and were treated intraperitoneally twice a week for 4 weeks, namely normal control (saline), arthritis control (AR; saline), AR + 17-AAG, AR + methotrexate (MTX), and AR + 17-AAG + MTX. At the end of the treatments, arthritic score was determined and then the animals were sacrificed. Erythrocyte sedimentation rate (ESR), serum levels of HSP70, interleukin-17 (IL-17), tumor necrosis factor-alpha (TNF-α), rheumatic factor (RF), C-reactive protein (CRP), malondialdehyde (MDA), glutathione peroxidase (GPx), and matrix metalloproteinase-9 (MMP-9) were determined.

RESULTS

In the AR group, all parameters increased significantly, except for GPx, which showed a pronounced decrease. The 17-AAG and/or MTX treatments significantly reduced arthritic score, ESR, IL-17, TNF-α, RF, CRP, MDA, and MMP-9 with significant increase in GPx compared to the AR group. The HSP70 level was significantly higher in the AR + 17-AAG and the AR + 17-AAG + MTX groups but significantly lower in the AR + MTX group as compared to the AR group. Also, it was significantly lower in the AR + MTX group as compared to the AR + 17-AAG group.

CONCLUSION

We concluded that HSP70 induction by 17-AAG attenuated the inflammatory process in a rheumatoid arthritis (RA) model induced by collagen, which suggested that HSP70 inducers can be promising agents in the treatment of RA.

CD39 positive regulatory T cell frequency as a biomarker of treatment response to methotrexate in rheumatoid arthritis

AIM

Nearly one-third of patients with rheumatoid arthritis (RA) do not respond to Methotrexate (MTX), the first-line therapy in RA. CD39, an ectonucleotidase highly expressed on regulatory T cells (Tregs), is responsible for production of adenosine, an important anti-inflammatory mediator of MTX action. Higher expression of CD39 on Tregs improves their suppressive capacity. Therefore, we aimed to study the role of CD39⁺ Treg frequency as a biomarker for MTX treatment response in RA.

METHODS

Patients with active RA who were naive to disease-modifying anti-rheumatic drugs were enrolled. Frequencies of CD39⁺ Tregs (CD4⁺ CD25⁺ FoxP3⁺ CD39⁺ cells) and CD4⁺ CD25⁺ CD39⁺ cells were determined by flow cytometry in peripheral blood before the start of therapy. After 4 months of MTX monotherapy, patients were classified into responders (European League Against Rheumatism [EULAR] good/moderate response) and non-responders (EULAR no response). All samples were genotyped for single nucleotide polymorphisms (SNPs) rs11188513 and rs7071836 in the ENTPD1 (CD39) gene.

RESULTS

After 4 months of MTX monotherapy, 54 patients were classified as responders and 16 as non-responders. The baseline CD39⁺ Treg and CD4⁺ CD25⁺ CD39⁺ cell frequencies were significantly higher in the responder group as compared with the non-responder group (P < 0.05 and P < 0.01, respectively). AA genotype at SNP rs7071836 was associated with poor response to MTX (P < 0.05; odds ratio = 5.67; 95% CI = 1.12-28.75).

CONCLUSION

Higher frequencies of CD39⁺ Tregs and CD4⁺ CD25⁺ CD39⁺ cells in the peripheral blood are associated with response to MTX in RA and hence, these could be considered as potential biomarkers for prediction of response to MTX treatment.

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.

Systematic review and meta-analysis of the efficacy and safety of Biqi capsule in rheumatoid arthritis patients

Biqi capsule is a Traditional Chinese Medicine preparation for treating rheumatoid arthritis (RA), and clinical studies have indicatedthat its effect may be more beneficial than that of Western medicine. The present study aimed to estimate the efficacy and safety of Biqi capsule alone or combined with methotrexate (MTX) compared with MTX alone for treating RA by performing a meta-analysis of randomized controlled trials and controlled clinical trials. A systematic literature search of studies published until March 2017 was performed. References from relevant studies were screened to obtain additional articles. The results were independently evaluated for relevance, and full-text studies were assessed for eligibility. The risk of bias was assessed using the Cochrane collaboration tool for assessing risk of bias. Out of 558 citations that were initially retrieved, a total of 5 studies comprising 522 patients met the inclusion criteria. The risk of bias of these trials was generally unclear or high. Meta-analysis indicated that Biqi capsule had better effects on C-reactive protein [standardized mean difference (SMD), −7.05; 95% CI -(10.77–3.33)] and tender joint count [SMD, −3.02; 95% CI, -(3.81–2.22)] and fewer adverse effects (AEs) than MTX [relative risk (RR), 0.19; 95% CI, 0.08–0.43]. Biqi capsule plus MTX was superior to MTX in terms of the total effect (RR, 1.17; 95% CI, 1.06–1.28), rheumatoid factor [SMD, −12.54; 95% CI, -(16.87–8.20)], swollen joint count [SMD, −1.50; 95% CI, -(1.99–1.01)], score of joint swelling [SMD −2.07; 95% CI, -(2.76–1.38)], tender joint count [SMD, −2.16; 95% CI, -(2.86–1.47)] and score of joint tenderness [SMD, −4.69; 95% CI, -(5.92–3.47)]. There was no difference in AEs between Biqi capsule plus MTX and MTX (RR, 0.71; 95% CI, 0.34–1.50). In conclusion, the present study indicated that compared with MTX, Biqi capsule plus MTX appeared to have more benefits but that Biqi capsule alone was not better for RA patients than MTX. In the other words, Biqi capsule plus MTX is more effective and has fewer AEs compared to MTX. However, the trials selected in the present meta-analysis have various limitations, including the lack of blinding and the short duration of the treatment; therefore, the conclusions are not sufficiently definitive. More randomized controlled trials are necessary to evaluate the use of Biqi capsule for managing RA.

Liquid chromatographic methods for the therapeutic drug monitoring of methotrexate as clinical decision support for personalized medicine: A brief review

Methotrexate (MTX) is an antifolate drug used for several diseases. Depending on the disease, MTX can be administered at low dose (LDMTX) in some autoimmune diseases, like rheumatoid arthritis, or at high dose (HDMTX) in some cancers, such as acute lymphoblastic leukemia. After absorption, MTX is metabolized in the liver to 7-hydroxymethotrexate and in the intestine to 2,4-diamino-N10-methylpteroic acid (DAMPA). Moreover, inside red blood cells, MTX is converted to active metabolites, MTX polyglutamates (MTXPGs), contributing to its pharmacodynamics. Owing to its narrow therapeutic range, and inter- and intra-patient variability, either noneffectiveness and/or toxicity may occur. Because of the existence of a relationship between drug therapeutic outcome and its systemic concentration, therapeutic drug monitoring (TDM) may ensure the effectiveness and safety of MTX use. In order to monitor the optimization of patient clinical response profile, several analytical methods have been described for TDM in biological samples. These include liquid chromatography (LC) coupled with ultraviolet detection, fluorescence detection or mass spectrometry, each one presenting advantages and drawbacks. This paper reviews the most commonly used techniques for sample preparation and critically discusses the current LC methods applied for the TDM of MTX in biological samples, at LDMTX and HDMTX.

Exosomal amyloid A and lymphatic vessel endothelial hyaluronic acid receptor-1 proteins are associated with disease activity in rheumatoid arthritis

Background

Exosomes are thought to play an important role in exchanging information between cells. The proteins and lipids in exosomes play roles in mediating inflammatory and autoimmune diseases. The aim of this study was to identify exosomal candidate proteins that are related to other inflammatory parameters in rheumatoid arthritis (RA).

Methods

The study population consisted of 60 patients with RA: 30 in the clinical remission (CR) group with a Disease Activity Score in 28 joints based on erythrocyte sedimentation rate (DAS28-ESR) ≤2.6 and 30 in the non-clinical remission (non-CR) group with a DAS28-ESR >2.6. Preparation of exosomes from patient serum samples was performed with the ExoQuick kit, and protein identification/quantification was performed using tandem mass tag labeling/mass spectrometry and an enzyme-linked immunosorbent assay. Comparisons between groups were made using Student’s t test or the Mann-Whitney U test, as appropriate. Spearman’s correlation coefficients (ρ) were calculated.

Results

We identified six candidate proteins. Exosomal levels of amyloid A (AA) and lymphatic vessel endothelial hyaluronic acid receptor-1 (LYVE-1) differed between the CR and non-CR groups. Both serum and exosomal AA levels were higher in the non-CR group than in the CR group (p = 0.001). Significant positive correlations were found between exosomal AA and C-reactive protein (CRP) as well as between serum AA and CRP (ρ = 0.614, p = 0.001, and ρ = 0.624, p = 0.001, respectively). Although serum levels of LYVE-1 did not differ between the non-CR and CR groups, exosomal levels of LYVE-1 were lower in the non-CR group than in the CR group (p = 0.01). We identified positive correlations between serum/exosomal LYVE-1 and CRP only in the non-CR group (serum ρ = 0.376, p = 0.04; exosome ρ = 0.545, p = 0.002).

Conclusions

Exosomal LYVE-1 shows potential for use as an additional marker of disease activity in patients with RA, and exosomes may carry other useful markers for RA.

Much more than you expected: The non-DHFR-mediated effects of methotrexate

BACKGROUND

For decades, methotrexate (MTX; amethopterin) has been known as an antifolate inhibitor of dihydrofolate reductase (DHFR), and it is widely used for the treatment of various malignancies and autoimmune diseases. Although the inclusion of MTX in various therapeutic regimens is based on its ability to inhibit DHFR and consequently to suppress the synthesis of pyrimidine and purine precursors, recent studies have shown that MTX is also able to target other intracellular pathways that are independent of folate metabolism.

SCOPE OF REVIEW

The main aim of this review is to summarize the most important, up-to-date findings of studies regarding the non-DHFR-mediated mechanisms of MTX action.

MAJOR CONCLUSIONS

The effectiveness of MTX is undoubtedly caused by its capability to affect various intracellular pathways at many levels. Although the most important therapeutic mechanism of MTX is strongly based on the inhibition of DHFR, many other effects of this compound have been described and new studies bring new insights into the pharmacology of MTX every year.

GENERAL SIGNIFICANCE

Identification of these new targets for MTX is especially important for a better understanding of MTX action in new protocols of combination therapy.

Moving toward personalized medicine in rheumatoid arthritis: SNPs in methotrexate intracellular pathways are associated with methotrexate therapeutic outcome

AIM

Evaluate the potential of selected SNPs as predictors of methotrexate (MTX) therapeutic outcome.

PATIENTS & METHODS

In total, 35 SNPs in 14 genes involved in MTX intracellular pathways and Phase II reactions were genotyped in 233 rheumatoid arthritis (RA) patients treated with MTX. Binary logistic regressions were performed by genotype/haplotype-based approaches. Non-Response- and Toxicity-Genetic Risk Indexes (Non-RespGRI and ToxGRI) were created.

RESULTS

MTX nonresponse was associated to eight genotypes and three haplotypes: MTHFR rs1801131 AA and rs1801133 TT; MS rs1805087 AA; MTRR rs1801394 A carriers; ATIC rs2372536 C carriers, rs4673993 T carriers, rs7563206 T carriers and rs12995526 T carriers; CC for GGH rs3758149 and rs12681874; CGTTT for ATIC combination 1; and CTTTC for ATIC combination 2. From overall Non-RespGRI patients with indexes 6-8 had more than sixfold increased risk for MTX nonresponse than those patients with indexes 0-5. MTX-related toxicity was associated to five genotypes and two haplotypes: ATIC rs2372536 G carriers, rs3821353 T carriers, rs7563206 CC and rs12995526 CC; ADORA2A rs2267076 T; CTTCC for ATIC combination 1; and TC for ADORA2A rs2267076 and rs2298383. From overall ToxGRI, patients with indexes 3-4 had more than sevenfold increased risk for MTX-related toxicity than those patients with indexes 1-2.

CONCLUSION

Genotyping may be helpful to identify which RA patients will not benefit from MTX treatment and, consequently, important to personalized medicine in RA. Nevertheless, further studies are required to validate these findings.

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.

How should immunomodulators be optimized when used as combination therapy with anti-tumor necrosis factor agents in the management of inflammatory bowel disease?

In the last 15 years the management of inflammatory bowel disease has evolved greatly, largely through the increased use of immunomodulators and, especially, anti-tumor necrosis factor (anti-TNF) biologic agents. Within this time period, confidence in the use of anti-TNFs has increased, whilst, especially in recent years, the efficacy and safety of thiopurines has been questioned. Yet despite recent concerns regarding the risk: benefit profile of thiopurines, combination therapy with an immunomodulator and an anti-TNF has emerged as the recommended treatment strategy for the majority of patients with moderate-severe disease, especially those who are recently diagnosed. Concurrently, therapeutic drug monitoring has emerged as a means of optimizing the dosage of both immunomodulators and anti-TNFs. However the recommended therapeutic target levels for both drug classes were largely derived from studies of monotherapy with either agent, or studies underpowered to analyze outcomes in combination therapy patients. It has been assumed that these target levels are applicable to patients on combination therapy also, however there are few data to support this. Similarly, the timing and duration of treatment with immunomodulators when used in combination therapy remains unknown. Recent attention, including post hoc analyses of the pivotal registration trials, has focused on the optimization of anti-TNF agents, when used as either monotherapy or combination therapy. This review will instead focus on how best to optimize immunomodulators when used in combination therapy, including an evaluation of recent data addressing unanswered questions regarding the optimal timing, dosage and duration of immunomodulator therapy in combination therapy patients.

Assessment of the relationship between methotrexate polyglutamates in red blood cells and clinical response in patients commencing methotrexate for rheumatoid arthritis

BACKGROUND AND OBJECTIVES

Therapeutic drug monitoring in patients with rheumatoid arthritis (RA) receiving methotrexate (MTX, MTXGlu1) has not been established. In this study, we aim to explore the relationship between red blood cell (RBC) concentrations of MTX and its polyglutamate metabolites (MTXGlu(n); n = 2, 3, 4, 5) and clinical response in RA patients commencing MTX.

METHODS

The binding activity of MTXGlu(n) to three putative enzymes involved in the MTX mechanism of action—dihydrofolate reductase, thymidylate synthase, and 5-aminoimidazole-4-carboxamide ribonucleotide transformylase—was simulated. RBC MTXGlu(n) concentrations that gave the highest inhibition activity across all three enzymes were linked with the disease activity score DAS28-3v (C-reactive protein [CRP]). A population pharmacokinetic-pharmacodynamic model was developed to describe the relationship between RBC MTX polyglutamate concentrations and clinical response in 12 RA patients commencing MTX.

RESULTS

The highest inhibition activity was with RBC MTXGlu(3-5). These polyglutamates were further evaluated for their relationship with DAS28-3v (CRP). Three of the 12 patients had a high DAS28-3v (CRP) at baseline (mean = 6.1) and showed a delayed response to MTX treatment. The remaining nine patients with a lower DAS28-3v (CRP) baseline (mean = 3.6) showed an immediate response. The developed MTX pharmacokinetic-pharmacodynamic model provided an acceptable description of the observed DAS28-3v (CRP) across all patients.

CONCLUSIONS

The developed model describes a longitudinal relationship between RBC MTXGlu(3-5) concentrations and DAS28-3v (CRP) in patients with RA commencing MTX. Further work is required to determine whether measurement of RBC MTX polyglutamates might be useful for dose individualisation in patients with RA.

Antiinflammatory Activity of a Novel Folic Acid Targeted Conjugate of the mTOR Inhibitor Everolimus

Folate receptor (FR)-β has been identified as a promising target for antimacrophage and antiinflammatory therapies. In the present study, we investigated EC0565, a folic acid-derivative of everolimus, as a FR-specific inhibitor of the mammalian target of rapamycin (mTOR). Because of its amphiphilic nature, EC0565 was first evaluated for water solubility, critical micelle formation, stability in culture and FR-binding specificity. Using FR-expressing macrophages, the effect of EC0565 on mTOR signaling and cellular proliferation was studied. The pharmacokinetics, metabolism and bioavailability of EC0565 were studied in normal rats. The in vivo activity of EC0565 was assessed in rats with adjuvant arthritis, a "macrophage-rich" model with close resemblance to rheumatoid arthritis. EC0565 forms micellar aggregates in physiological buffers and demonstrates good water solubility as well as strong multivalent FR-binding capacity. EC0565 inhibited mTOR signaling in rat macrophages at nanomolar concentrations and induced G0/G1 cell cycle arrest in serum-starved RAW264.7 cells. Subcutaneously administered EC0565 in rats displayed good bioavailability and a relatively long half-life (~12 h). When given at 250 nmol/kg, EC0565 selectively inhibited proliferating cell nuclear antigen expression in thioglycollate-stimulated rat peritoneal cells. With limited dosing regimens, the antiarthritic activity of EC0565 was found superior to that of etanercept, everolimus and a nontargeted everolimus analog. The in vivo activity of EC0565 was also comparable to that of a folate-targeted aminopterin. Folate-targeted mTOR inhibition may be an effective way of suppressing activated macrophages in sites of inflammation, especially in nutrient-deprived conditions, such as in the arthritic joints. Further investigation and improvement upon the physical and biochemical properties of EC0565 are warranted.

Pharmacogenomics of Methotrexate Membrane Transport Pathway: Can Clinical Response to Methotrexate in Rheumatoid Arthritis Be Predicted?

Background: Methotrexate (MTX) is widely used for rheumatoid arthritis (RA) treatment. Single nucleotide polymorphisms (SNPs) could be used as predictors of patients’ therapeutic outcome variability. Therefore, this study aims to evaluate the influence of SNPs in genes encoding for MTX membrane transport proteins in order to predict clinical response to MTX. Methods: Clinicopathological data from 233 RA patients treated with MTX were collected, clinical response defined, and patients genotyped for 23 SNPs. Genotype and haplotype analyses were performed using multivariate methods and a genetic risk index (GRI) for non-response was created. Results: Increased risk for non-response was associated to SLC22A11 rs11231809 T carriers; ABCC1 rs246240 G carriers; ABCC1 rs3784864 G carriers; CGG haplotype for ABCC1 rs35592, rs2074087 and rs3784864; and CGG haplotype for ABCC1 rs35592, rs246240 and rs3784864. GRI demonstrated that patients with Index 3 were 16-fold more likely to be non-responders than those with Index 1. Conclusions: This study revealed that SLC22A11 and ABCC1 may be important to identify those patients who will not benefit from MTX treatment, highlighting the relevance in translating these results to clinical practice. However, further validation by independent studies is needed to develop the field of personalized medicine to predict clinical response to MTX treatment.

Circulating anti-citrullinated peptide antibodies, cytokines and genotype as biomarkers of response to disease-modifying antirheumatic drug therapy in early rheumatoid arthritis

Background

To measure circulating anti-citrullinated peptide antibodies (ACPA) and cytokines pre- and 6 months post-therapy as a strategy to predict and optimize responses to traditional disease-modifying antirheumatic drugs (DMARDs) in early RA, which is an unmet need in developing countries.

Patients and methods

A cohort of 140 predominantly (88.5 %) black female South African patients with early RA was treated with synthetic DMARDs, mostly methotrexate (MTX) alone, or in combination with low-dose oral corticosteroids (CS). Circulating ACPA and a panel of circulating cytokines/chemokines/growth factors were measured at baseline and after 6 months of therapy in relation to disease activity and Shared Epitope (SE).

Results

Following 6 months of therapy, the median simplified disease activity index (SDAI) declined from a baseline of 41.4 to 16.0 (p = 0.0001) for the entire cohort, which was paralleled by significant falls in median serum ACPA levels (516.6 vs. 255.7 units/ml, p = <0.0001) and several of the circulating cytokines (IL-4, IL-7, IL-8, G-CSF, VEGF; p < 0.0010 – p < 0.0001) which were most evident in the subgroup of patients treated with a combination of MTX and CS. Although biomarker concentrations decreased most notably in the low-disease activity group post-therapy, no significant correlations between these biomarkers and disease activity were observed, Baseline ACPA levels, but not SDAI or cytokines, were significantly higher in the subgroup of risk allele-positive patients (561.1 vs. 331.9 units/ml, p < 0.05), while no associations with ACPA and a smoking history were evident.

Conclusions

The use of DMARDs in RA is associated with significant decreases in ACPA and cytokines which did not correlate with changes in SDAI, precluding the utility of serial measurement of these biomarkers to monitor early responses to therapy, but may have prognostic value.

Electronic supplementary material

The online version of this article (doi:10.1186/s12891-015-0587-1) contains supplementary material, which is available to authorized users.

Ameliorating Role Exerted by Al-Hijamah in Autoimmune Diseases: Effect on Serum Autoantibodies and Inflammatory Mediators

Autoimmune diseases have common properties characterized by abnormal blood chemistry with high serum autoimmune antibodies, and inflammatory mediators. Those causative pathological substances (CPS) cannot be excreted by physiological mechanisms. Current treatments for autoimmune diseases involve steroids, cytotoxic drugs, plasmapheresis and monoclonal antibodies. Wet cupping therapy (WCT) of prophetic medicine is called Al-hijamah that treats numerous diseases having different etiology and pathogenesis via a pressure-dependent and size-dependent non-specific filtration then excretion of CPS causing clearance of blood and interstitial fluids. Al-hijamah clears blood passing through the fenestrated skin capillaries. Medical bases of Al-hijamah were reported in the evidence-based Taibah mechanism (Taibah theory). Al-hijamah was reported to be an excellent treatment for rheumatoid arthritis that improved patients' blood chemistry and induced significant clinical improvement and pharmacological potentiation. Al-hijamah improved the natural immunity and suppressed the pathological immunity through decreasing the serum level of autoantibodies, inflammatory mediators, and serum ferritin (a key player in autoimmunity). Al-hijamah reduced significantly pain severity, number of swollen joints and disease activity with no significant side effects. Main steps of Al-hijamah are skin suction (cupping), scarification (sharatmihjam in Arabic) and second suction (triple S technique) that is better therapeutically than the traditional WCT (double S technique). Whenever an excess noxious substance is to be removed from patients' blood and interstitial fluids, Al-hijamah is indicated. Shartatmihjam is a curative treatment in prophetic teachings according to the prophetic hadeeth: "Cure is in three: in shartatmihjam, oral honey and cauterization. I do not recommend my nation to cauterize". Al-hijamah may have better therapeutic benefits than plasmapheresis. Al-hijamah may be promising in treating autoimmune diseases as a sole treatment or adjuvant treatment.

Methotrexate-mediated inhibition of nuclear factor κB activation by distinct pathways in T cells and fibroblast-like synoviocytes

OBJECTIVES

Nuclear factor κB (NF-κB) is a critical activator of inflammatory processes and MTX is one of the most commonly prescribed DMARDs for treatment of RA. We sought to determine whether MTX inhibited NF-κB activity in RA and in lymphocytes and fibroblast-like synoviocytes (FLSs) and to define underlying mechanisms of action.

METHODS

An NF-κB luciferase reporter plasmid was used to measure NF-κB activation across experimental stimuli. Flow cytometry was used to quantify changes in intracellular protein levels, measure levels of reactive oxygen species and determine apoptosis. Quantitative RT-PCR was used to identify changes in MTX target genes.

RESULTS

In T cell lines, MTX (0.1 μM) inhibited activation of NF-κB via depletion of tetrahydrobiopterin (BH4) and increased Jun-N-terminal kinase (JNK)-dependent p53 activity. Inhibitors of BH4 activity or synthesis also inhibited NF-κB activation and, similar to MTX, increased JNK, p53, p21 and JUN activity. Patients with RA expressed increased levels of phosphorylated or active RelA (p65) compared with controls. Levels of phosphorylated RelA were reduced in patients receiving low-dose MTX therapy. In contrast, inhibition of NF-κB activation by MTX was not mediated via BH4 depletion and JNK activation in FLSs, but rather was completely prevented by adenosine receptor antagonists.

CONCLUSION

Our findings support a model whereby distinct pathways are activated by MTX in T cells and FLSs to inhibit NF-κB activation.

Human leucocyte antigen-Cw6 as a predictor for clinical response to ustekinumab, an interleukin-12/23 blocker, in Chinese patients with psoriasis: a retrospective analysis

BACKGROUND

Ustekinumab, an interleukin-12/23 inhibitor, is effective in the treatment of psoriasis. A recent Italian study showed more favourable response to ustekinumab in patients with positive human leucocyte antigen (HLA)-Cw6. Nonetheless, there are differences in genetic susceptibility to psoriasis between races, and no studies have specifically assessed the candidate genetic markers in predicting therapy outcome in Chinese patients with psoriasis treated with ustekinumab.

OBJECTIVES

To determine whether HLA gene polymorphisms can predict the response to ustekinumab in Chinese patients with psoriasis.

METHODS

Sixty-six patients with psoriasis treated with ustekinumab were included in the study, and the effectiveness of ustekinumab therapy was evaluated at weeks 0, 16 and 28 by Psoriasis Area and Severity Index (PASI).

RESULTS

More HLA-Cw6-positive patients achieved a PASI 75 response at week 4 compared with HLA-Cw6-negative patients (38% vs. 9%, P = 0·019). Similarly, at week 16, patients carrying the HLA-Cw6 allele showed a higher likelihood of achieving PASI 50, 75 and 90 than Cw6-negative patients, although this was not statistically significant. At week 28, a significantly higher percentage of HLA-Cw6-positive patients maintained PASI 90 response compared with Cw6-negative patients (63% vs. 26%, P = 0·035). Further analysis of other HLA allele polymorphisms did not show significant associations with therapeutic response to ustekinumab.

CONCLUSIONS

This pharmacogenetic study provides preliminary data indicating that positive HLA-Cw6 is associated with a good response to ustekinumab treatment in Chinese patients with psoriasis.

Prediction of methotrexate clinical response in Portuguese rheumatoid arthritis patients: implication of MTHFR rs1801133 and ATIC rs4673993 polymorphisms

Objective. Methotrexate (MTX), the most used drug in rheumatoid arthritis (RA) treatment, showing variability in clinical response, is often associated with genetic polymorphisms. This study aimed to elucidate the role of methylenetetrahydrofolate reductase (MTHFR) C677T and aminoimidazole carboxamide adenosine ribonucleotide transformylase (ATIC) T675C polymorphisms and clinicopathological variables in clinical response to MTX in Portuguese RA patients. Methods. Study included 233 RA patients treated with MTX for at least six months. MTHFR C677T and ATIC T675C polymorphisms were genotyped and clinicopathological variables were collected. Statistical analyses were performed and binary logistic regression method adjusted to possible confounding variables. Results. Multivariate analyses demonstrated that MTHFR 677TT (OR = 4.63; P = 0.013) and ATIC 675T carriers (OR = 5.16; P = 0.013) were associated with over 4-fold increased risk for nonresponse. For clinicopathological variables, noncurrent smokers (OR = 7.98; P = 0.001), patients positive to anti-cyclic citrullinated peptide (OR = 3.53; P = 0.004) and antinuclear antibodies (OR = 2.28; P = 0.045), with higher health assessment questionnaire score (OR = 2.42; P = 0.007), and nonsteroidal anti-inflammatory drug users (OR = 2.77; P = 0.018) were also associated with nonresponse. Contrarily, subcutaneous administration route (OR = 0.11; P < 0.001) was associated with response. Conclusion. Our study suggests that MTHFR C677T and ATIC T675C genotyping combined with clinicopathological data may help to identify patients whom will not benefit from MTX treatment and, therefore, assist clinicians in personalizing RA treatment.

SLC19A1 80G allele as a biomarker of methotrexate-related gastrointestinal toxicity in Portuguese rheumatoid arthritis patients

AIM

The aim of our study was to characterize the association of clinicopathological variables and the SLC19A1/RFC-1 G80A polymorphism in methotrexate (MTX)-related toxicity in Portuguese patients with rheumatoid arthritis.

PATIENTS & METHODS

The study included 233 consecutively recruited patients with rheumatoid arthritis under MTX treatment. The SLC19A1 G80A polymorphism was evaluated by PCR-RFLP.

RESULTS

Statistical analysis revealed that SLC19A1 80G carriers had increased risk of gastrointestinal toxicity (odds ratio [OR]: 2.61, p = 0.019) and that regular folic acid supplementation was associated with both overall and gastrointestinal toxicity protection (OR: 0.15, p < 0.001 and OR: 0.19, p < 0.001, respectively). Multivariate analysis confirmed the association of SLC19A1 80G and regular folic acid supplementation to gastrointestinal toxicity (OR: 5.53 and 0.13, respectively). Moreover, a multivariate Cox regression model demonstrated a higher risk of earlier gastrointestinal toxicity in SLC19A1 80G carriers (hazard ratio: 3.63, p = 0.002).

CONCLUSION

SLC19A1 G80A genotyping may be a useful tool for clinicians to identify patients at higher risk for developing gastrointestinal toxicity related to MTX treatment.

Low-dose methotrexate results in the selective accumulation of aminoimidazole carboxamide ribotide in an erythroblastoid cell line

Therapeutic and toxic response to low-dose methotrexate (MTX) in the treatment of autoimmune disease continues to be highly variable, resulting in a critical need to identify predictive biomarkers of response. Biomarker development has been hampered by an incomplete understanding of the molecular pharmacology of low-dose MTX. To address this issue, accumulation of the substrates for aminoimidazole carboxamide ribonucleotide transformylase (AICART) and thymidylate synthase (TS) was measured as markers of pharmacological activity of MTX in an erythroblastoid cell line. A 115-fold increase in the AICART substrate and anti-inflammatory mediator, 5-aminoimidazole-4-carboxamide-1-β-d-ribofuranosyl 5'-monophosphate (ZMP), was observed following exposure to 10 nM MTX but subsequently decreased with increasing MTX concentrations, declining to baseline levels with 1000 nM MTX. In contrast, the TS substrate, 2'-deoxyuridine 5'-monophosphate disodium salt (dUMP), displayed concentration-dependent accumulation, increasing 29-, 342-, and 471-fold over baseline with 10, 100, and 1000 nM MTX, respectively. Cellular levels of dUMP correlated with levels of the parent drug (MTX-PG1; r = 0.66, P < 0.001) and its polyglutamates (MTX-PG2-6) (r = 0.81, P < 0.001), whereas cellular levels of ZMP were only moderately correlated with MTX-PG1 (r = 0.34, P < 0.01). In contrast, accumulation of ZMP at 10 nM MTX was associated with a 2.9-fold increase in the AICART inhibitor dihydrofolate (DHF), represented primarily by long-chain DHF polyglutamates. Selectivity, defined as the ratio of ZMP to dUMP, was maximal following exposure to 6 nM MTX. Characterizing the range of MTX concentrations that selectively promote ZMP accumulation while preserving pyrimidine biosynthesis may lead to optimization of low-dose MTX therapy.

Preclinical drug evaluation system in the Plasmodium knowlesi baboon model of malaria: the methotrexate study

BACKGROUND

Drug resistance against first-line antimalarials warrants search for new lead compounds and repurposing of drugs such as methotrexate. Animal models are required for preclinical drug development before clinical testing. This study aimed to develop a preclinical drug development system in baboons infected with Plasmodium knowlesi.

METHODS

Protocols for drug administration, pharmacokinetics, clinical chemistry and haematology were developed in the baboon model. Baboons were infected with P. knowlesi and methotrexate administered orally for 5 days. Clinical signs, parasitaemia, gross and histopathology examinations were conducted to determine effect of methotrexate in baboons.

RESULTS

No major clinical chemistry, haematology and pathological changes attributable to methotrexate were observed. Parasitaemia suppression of 77.67% was achieved at a methotrexate dose of 3.0 mg/kg.

CONCLUSIONS

A protocol for preclinical drug development in the baboon was optimized. Methotrexate suppressed P. knowlesi malaria in baboons. These findings warrant further characterization of methotrexate for use in combination therapy.