A comparative study of the effects of bucillamine and salazosulfapyridine in the treatment of rheumatoid arthritis

Extracellular aaRSs drive autoimmune and inflammatory responses in rheumatoid arthritis via the release of cytokines and PAD4

OBJECTIVES

Recent studies demonstrate that extracellular-released aminoacyl-tRNA synthetases (aaRSs) play unique roles in immune responses and diseases. This study aimed to understand the role of extracellular aaRSs in the pathogenesis of rheumatoid arthritis (RA).

METHODS

Primary macrophages and fibroblast-like synoviocytes were cultured with aaRSs. aaRS-induced cytokine production including IL-6 and TNF-α was detected by ELISA. Transcriptomic features of aaRS-stimulated macrophages were examined using RNA-sequencing. Serum and synovial fluid (SF) aaRS levels in patients with RA were assessed using ELISA. Peptidyl arginine deiminase (PAD) 4 release from macrophages stimulated with aaRSs was detected by ELISA. Citrullination of aaRSs by themselves was examined by immunoprecipitation and western blotting. Furthermore, aaRS inhibitory peptides were used for inhibition of arthritis in two mouse RA models, collagen-induced arthritis and collagen antibody-induced arthritis.

RESULTS

All 20 aaRSs functioned as alarmin; they induced pro-inflammatory cytokines through the CD14-MD2-TLR4 axis. Stimulation of macrophages with aaRSs displayed persistent innate inflammatory responses. Serum and SF levels of many aaRSs increased in patients with RA compared with control subjects. Furthermore, aaRSs released PAD4 from living macrophages, leading to their citrullination. We demonstrate that aaRS inhibitory peptides suppress cytokine production and PAD4 release by aaRSs and alleviate arthritic symptoms in a mouse RA model.

CONCLUSIONS

Our findings uncovered the significant role of aaRSs as a novel alarmin in RA pathogenesis, indicating that their blocking agents are potent antirheumatic drugs.

Bucillamine Inhibits UVB-Induced MAPK Activation and Apoptosis in Human HaCaT Keratinocytes and SKH-1 Hairless Mouse Skin

Ultraviolet B (UVB) radiation is known as a culprit in skin carcinogenesis. We have previously reported that bucillamine (N-[2-mercapto-2-methylpropionyl]-L-cysteine), a cysteine derivative with antioxidant and anti-inflammatory capacity, protects against UVB-induced p53 activation and inflammatory responses in mouse skin. Since MAPK signaling pathways regulate p53 expression and activation, here we determined bucillamine effect on UVB-mediated MAPK activation in vitro using human skin keratinocyte cell line HaCaT and in vivo using SKH-1 hairless mouse skin. A single low dose of UVB (30 mJ cm^-2 ) resulted in increased JNK/MAPK phosphorylation and caspase-3 cleavage in HaCaT cells. However, JNK activation and casaspe-3 cleavage were inhibited by pretreatment of HaCaT cells with physiological doses of bucillamine (25 and 100 µm). Consistent with these results, bucillamine pretreatment in mice (20 mg kg^-1 ) inhibited JNK/MAPK and ERK/MAPK activation in skin epidermal cells at 6-12 and 24 h, respectively, after UVB exposure. Moreover, bucillamine attenuated UVB-induced Ki-67-positive cells and cleaved caspase-3-positive cells in mouse skin. These findings demonstrate that bucillamine inhibits UVB-induced MAPK signaling, cell proliferation and apoptosis. Together with our previous report, we provide evidence that bucillamine has a photoprotective effect against UV exposure.

Efficacy of conventional synthetic disease-modifying antirheumatic drugs, glucocorticoids and tofacitinib: a systematic literature review informing the 2013 update of the EULAR recommendations for management of rheumatoid arthritis

OBJECTIVES

To update a previous systematic review assessing the efficacy of conventional synthetic disease-modifying antirheumatic drugs (csDMARDs) in rheumatoid arthritis (RA).

METHODS

Two systematic reviews of the literature using PubMed, Embase and the Cochrane library were performed from 2009 until January 2013 to assess the efficacy of csDMARDs (as monotherapy or combination therapy) in adults with RA, and the efficacy of glucocorticoids in early RA. A third systematic review was performed until March 2013 to assess the efficacy of tofacitinib by meta-analysis.

RESULTS

For glucocorticoids, of 222 hits, five publications relating to four new trials were analysed for efficacy, confirming that initial treatment of RA with low-dose prednisone plus methotrexate (MTX) results in better clinical and structural outcomes at 1 and 2 years than treatment with MTX alone. For csDMARDs, of 498 studies, only two new studies were randomised controlled trials comparing MTX monotherapy with MTX in combination with another csDMARD without differences in glucocorticoid usage. Using tight control principles, clinical outcomes were no better with immediate triple therapy than with 'step-up' therapy. For tofacitinib, the pooled analysis of 10 trials showed that tofacitinib was more efficacious on signs and symptoms, disability and appeared to be more efficacious on structural damage than control treatment with placebo (OR (95% CI)--American College of Rheumatology 20% (ACR20) response: 2.44 (1.97 to 3.02)) or treatment with MTX (ACR20 response: 2.38 (1.66 to 3.43)).

CONCLUSIONS

Addition of low-dose glucocorticoids to csDMARD therapy produces benefits in early RA. Under tight control conditions, combination therapy with csDMARDs is no better than MTX monotherapy. Tofacitinib is a new DMARD with proven efficacy.

Safety and effectiveness of 6 months' etanercept monotherapy and combination therapy in Japanese patients with rheumatoid arthritis: effect of concomitant disease-modifying antirheumatic drugs

OBJECTIVE

To assess real-world safety, tolerability, and effectiveness of etanercept monotherapy, etanercept plus methotrexate (MTX), or etanercept plus other disease-modifying antirheumatic drugs (DMARD) in Japanese patients with active rheumatoid arthritis (RA) despite previous treatment with DMARD.

METHODS

In this 24-week, all-cases postmarketing surveillance study, adverse events (AE) were coded using the Medical Dictionary for Regulatory Activities. Effectiveness was assessed every 4 weeks using the 28-joint Disease Activity Score and the European League Against Rheumatism response criteria.

RESULTS

Of 13,861 patients (81% women) in the analysis, 3616, 2506, and 7739, respectively, were classified into etanercept monotherapy (ETN-mono), etanercept plus DMARD other than MTX (ETN + DMARD), and etanercept plus MTX (ETN + MTX) groups. Rates of AE and serious AE (SAE) in the ETN + MTX group were lower than in other groups. Risk of SAE or serious infections was not significantly increased with higher versus lower MTX doses at baseline or with concomitant use of salazosulfapyridine or bucillamine in ETN + DMARD versus ETN-mono groups. A greater likelihood of achieving clinical remission was seen with ETN + MTX versus ETN-mono (OR 1.36; 95% CI, 1.16-1.60; p < 0.001). Higher MTX dose at baseline was associated with a higher remission rate (> 8 mg vs 0 to ≤ 4 mg, OR 1.47, 95% CI 1.07-2.00, p = 0.016; 6 to ≤ 8 mg vs 0 to ≤ 4 mg, OR 1.27, 95% CI 1.01-1.60, p = 0.038).

CONCLUSION

Combination therapies with etanercept plus MTX or other DMARD were reasonably well tolerated, and ETN + MTX at higher doses was more effective than ETN-mono in Japanese patients with RA.