Crosstalk between tumor necrosis factor-alpha signaling and aryl hydrocarbon receptor signaling in nuclear factor -kappa B activation: A possible molecular mechanism underlying the reduced efficacy of TNF-inhibitors in rheumatoid arthritis by smoking.

OBJECTIVES: To examine the influence of smoking on biologics treatment against different therapeutic targets, such as TNFα, IL-6, and T cell, in rheumatoid arthritis (RA) and elucidate the underlying molecular mechanism. METHODS: The association between drug-discontinuation due to poor therapeutic response and smoking status was analyzed individually in biologics against different therapeutic targets by a multivariable logistic regression analysis using the "NinJa" Registry, one of the largest cohorts of Japanese RA patients. In vitro enhancement of TNFα-induced NF-κB activation and subsequent proinflammatory cytokine production by cigarette chemical components was examined by RT-PCR, qPCR, ELISA, and western blotting using an immortalized rheumatoid synovial cell line, MH7A. RESULTS: The rate of drug-discontinuation due to poor therapeutic response was higher in the current smoking group than in the never- or ever-smoking groups (the odds ratio of current/never smoking: 2.189, 95%CI; 1.305-3.672,P = 0.003; current/ever: 1.580, 95%CI; 0.879-2.839,P = 0.126) in the TNF inhibitor (TNFi) treatment group. However, this tendency was not observed in either the IL-6 or T cell inhibitor treatment groups. Cigarette smoke chemical components, such as benzo[α]pyrene, known as aryl hydrocarbon receptor (AhR) ligands, themselves activated NF-κB and induced proinflammatory cytokines, IL-1ß and IL-6. Furthermore, they also significantly enhanced TNFα-induced NF-κB activation and proinflammatory cytokine production. This enhancement was dominantly inhibited by Bay 11-7082, an NF-κB inhibitor. CONCLUSIONS: These results suggest a crosstalk between TNFα signaling and AhR signaling in NF-κB activation which may constitute one of the molecular mechanisms underlying the higher incidence of drug-discontinuation in RA patients undergoing TNFi treatment with smoking habits.

Function and expression differences between ergot and non-ergot dopamine D2 agonists on heart valve interstitial cells.

BACKGROUND AND AIM OF THE STUDY: The symptoms of Parkinson's disease are alleviated by dopamine D2 agonists, which are classified as ergot dopamine D2 agonists and non-ergot D2 agonists. Among the former, pergolide has been associated with valvular heart disease, since it has both potent D2 receptor and serotonin 5-HT(2B) receptor agonistic properties. Among the latter, pramipexole has few incidences of heart valve disease onset, since it has an absence of 5-HT(2B) receptor agonism. METHOD: A [3H]thymidine incorporation assay was performed to monitor function, and microarray global analysis to monitor gene expression, on porcine heart valve interstitial cells (VICs) treated with pergolide or pramipexole. RESULTS: The 5-HT(2B) receptor was abundantly expressed in porcine VICs. The 5-HT(2B) receptor agonist pergolide induced an increase in [3H]thymidine incorporation, accompanied by a decrease in 5-HT(2B) receptor mRNA expression. [3H]thymidine incorporation was blocked by lisuride, a 5-HT(2B) receptor antagonist, and also by LY-294002, a specific inhibitor of PI3K and Akt. Moreover, type 2 iodothyronine deiodinase (Dio2) expression in porcine VICs treated with pergolide was shown, by a global analysis of mRNA, to be markedly increased compared to that induced by pramipexole. Such changes in VICs may correlate with the mechanism of heart valve disease pathogenesis. CONCLUSION: There were substantial differences (increased [3H]thymidine incorporation, and Dio2 expression) between pergolide and pramipexole, which might correlate with the mechanism of heart valve disease onset.