Many of disease‐modifying anti‐rheumatic drugs often have side effects at high doses and/or during long‐term administration. Increased efficacy without increased toxicity is expected for combination therapy of rheumatoid arthritis (RA). The aim of the study was to examine the effect of N‐feruloylserotonin (N‐f‐5HT) and methotrexate (MTX) in monotherapy and in combination therapy on disease progression and inflammation in arthritic rats. Adjuvant arthritis was induced by intradermal injection ofMycobacterium butyricumin incomplete Freund′s adjuvant in Lewis rats. The experiment included healthy animals, arthritic animals without any drug administration, arthritic animals with administration of N‐f‐5HTin the oral daily dose of 15 mg/kg b.w., arthritic animals with administration ofMTXin the oral dose of 0.3 mg/kg b.w. twice a week and arthritic animals treated with the combination of N‐f‐5HTandMTX. N‐f‐5HTin monotherapy reduced only activation ofNF‐κB and did not have any significant effect on other parameters monitored. Low‐dose treatment ofMTXdecreased the level ofIL‐1β andMCP‐1 on day 14 and activation ofNF‐κB in liver without significant effect on other parameters. N‐f‐5HTandMTXcombination showed both the anti‐arthritic (hind paw volume and arthritic score) and anti‐inflammatory effect (plasmatic levels ofIL‐1β,IL‐17,MCP‐1,CRP, and activation ofNF‐κB in liver). In combination withMTX, N‐f‐5HTmarkedly potentiated the therapeutic effect ofMTXlow dose, which resulted in significant improvement of all parameters measured. The findings showed that the combination therapy simultaneously decreased multiple markers of inflammation, a result crucial for future therapy ofRA.

The phosphodiesterase 4 inhibitor roflumilast prevents bleomycin- (BLM-) induced lung fibrosis in animal models. However, its mechanism of action remains unknown. We investigated whether roflumilast N-oxide (RNO), the active metabolite of roflumilast, can modulatein vitrothe oxidative effects of BLM on human lung fibroblasts (HLF). In addition, since BLM increases the production of F₂-isoprostanes that haveper sefibrogenic activity, the effect of RNO on oxidative stress and fibrogenesis induced by the F₂-isoprostane 8-epi-PGF2αwas investigated. HLF were preincubated either with the vehicle or with RNO and exposed to either BLM or 8-epi-PGF2α. Proliferation and collagen synthesis were assessed as [³H]-thymidine and [³H]-proline incorporation. Reactive oxygen species (ROS) and F₂-isoprostanes were measured. NADPH oxidase 4 (NOX4) protein and mRNA were also evaluated. BLM increased both cell proliferation and collagen synthesis and enhanced ROS and F₂-isoprostane production. These effects were significantly prevented by RNO. Also, RNO significantly reduced the increase in both NOX4 mRNA and protein, induced by BLM. Finally, 8-epi-PGF2α per sestimulated HLF proliferation, collagen synthesis, and NOX4 expression and ROS generation, and RNO prevented these effects. Thus, the antifibrotic effect of RNO observedin vivomay be related to its ability to mitigate ROS generation via downregulation of NOX4.