Methotrexate Disposition, Anti-Folate Activity, and Metabolomic Profiling to Identify Molecular Markers of Disease Activity and Drug Response in the Collagen-Induced Arthritis Mouse Model

Plasma metabolomic profiling as a tool to identify predictive biomarkers of methotrexate efficacy in rheumatoid arthritis

OBJECTIVE

Methotrexate (MTX) remains the first-choice disease-modifying therapy in rheumatoid arthritis (RA). However, clinical response is variable, and no reliable predictive biomarkers of efficacy currently exist. In this study, plasma metabolomic profiling is evaluated as a tool to identify pretreatment biomarkers of MTX response in RA.

METHODS

Plasma collected from RA patients initiating MTX therapy (n = 20) were analyzed by metabolomic profiling totaling 648 identified metabolites. Pretreatment metabolomic profiles were compared based on clinical response after 16-weeks of MTX therapy. Clinical response to MTX was defined by a clinically meaningful reduction in disease activity score in 28 joints (DAS28-ESR) of greater than 1.2.

RESULTS

Pretreatment plasma levels of 19 metabolites were found to differ (p < 0.05) between RA patients based on response to MTX at 16-weeks. Spearman's correlation of pretreatment plasma metabolite levels with change in DAS28-ESR over the treatment period further supported three of the identified metabolites as associated with MTX response (p < 0.05). The identified metabolite levels were all found to be lower in RA patients responsive to MTX but were not found to be intercorrelated. Receiver operating characteristic analysis of each of the identified metabolites, alone or in combination, demonstrated an excellent discrimination between responders and non-responders based on pretreatment plasma levels of nornicotine (AUC = 0.84), N-methylisoleucine (AUC = 0.82), 2,3-dihydroxybutanoic acid (AUC = 0.82), and a combination biomarker panel score (AUC = 0.98).

CONCLUSION

Pretreatment plasma metabolomic profiling identified multiple metabolites associated with early response to MTX therapy in RA and represents a promising approach for the identification of clinical biomarkers of MTX response in RA.

Pterostilbene improves CFA-induced arthritis and peripheral neuropathy through modulation of oxidative stress, inflammatory cytokines and neurotransmitters in Wistar rats

Pterostilbene is a stilbene flavonoid that occurs naturally in various plants as well as produced by genetic engineering. It exhibits anti-inflammatory, analgesic, anti-oxidant and neuroprotective activities. This research was aimed to determine the potential of pterostilbene against arthritis and peripheral neuropathy in Complete Freund's Adjuvant (CFA) induced arthritis. Rat hind paw was injected with 0.1 ml CFA to induce arthritis. Standard control animals received oral methotrexate (3 mg/kg/week). Pterostilbene at 12.5, 25 and 50 mg/kg was given orally to different groups of arthritic rats from day 7-28 for 21 days. Pterostilbene significantly reduced paw diameter and retarded the decrease in body weight of arthritic rats. It profoundly (p < 0.05-0.0001) reduced lipid peroxidation and nitrites, while increased superoxide dismutase (SOD) in the liver tissue. Pterostilbene treatment significantly (p < 0.0001) reduced TNF-α and IL-6 levels. Pterostilbene markedly improved (p < 0.05-0.001) motor activity and showed analgesic effect in arthritic rats at 25 and 50 mg/kg as compared to disease control rats. Furthermore, it notably (p < 0.05-0.0001) increased SOD activity, nitrites, noradrenaline and serotonin levels in the sciatic nerve of arthritic rats. Treatment with pterostilbene also ameliorated the CFA-induced pannus formation, cartilage damage and synovial hyperplasia in the arthritic rat paws. It is determined from the current study that pterostilbene was effective in reducing CFA-induced arthritis in rats through amelioration of oxidative stress and inflammatory mediators. It was also effective to treat peripheral neuropathy through modulation of oxidative stress and neurotransmitters in sciatic nerves.

Metabolomics in rheumatoid arthritis: Advances and review

Rheumatoid arthritis (RA) is an autoimmune disease accompanied by metabolic alterations. The metabolic profiles of patients with RA can be determined using targeted and non-targeted metabolomics technology. Metabolic changes in glucose, lipid, and amino acid levels are involved in glycolysis, the tricarboxylic acid cycle, the pentose phosphate pathway, the arachidonic acid metabolic pathway, and amino acid metabolism. These alterations in metabolic pathways and metabolites can fulfill bio-energetic requirements, promote cell proliferation, drive inflammatory mediator secretion, mediate leukocyte infiltration, induce joint destruction and muscle atrophy, and regulate cell proliferation, which may reflect the etiologies of RA. Differential metabolites can be used as biomarkers for the diagnosis, prognosis, and risk prediction, improving the specificity and accuracy of diagnostics and prognosis prediction. Additionally, metabolic changes associated with therapeutic responses can improve the understanding of drug mechanism. Metabolic homeostasis and regulation are new therapeutic strategies for RA. In this review, we provide a comprehensive overview of advances in metabolomics for RA.

Special Issue on “The Application of Metabolomics in Clinical Practice: Challenges and Opportunities”

This Special Issue aimed to collect studies based on clinical applications of metabolomics in human disease [...]