Mirthful laughter differentially affects serum pro- and anti-inflammatory cytokine levels depending on the level of disease activity in patients with rheumatoid arthritis

Objectives. To examine the effect of mirthful laughter in rheumatoid arthritis (RA), we evaluated the levels of serum cytokines before and after patients experienced mirthful laughter. Methods. Forty-one patients with RA and 23 healthy subjects were enrolled. They listened to ‘Rakugo’, a traditional Japanese comic story, to induce mirthful laughter. We measured serum IL-6, IL-1b, TNF-a, IL-4 and IL-1 receptor antagonist (IL-1Ra) concentrations before and after patients listened to the story. The RA subjects were divided into two groups. One was designated the ‘difficult-to-control RA’ group (CRP ¸1.0 mg/dl); The other group was regarded as the ‘easily controlled RA’ group (CRP _1.0 mg/dl). Results. The basal levels of serum IL-6 and TNF-a in the RA patients were significantly higher than those in the healthy group. After experiencing mirthful laughter, the levels of serum IL-6 decreased significantly in the RA group but not in the healthy subjects. Interestingly, the level of serum TNF-a decreased only in the easily controlled RA group. Serum IL-4 concentration in the RA group was significantly higher than that in healthy subjects before the story. After the story, the level of serum IL-4 significantly decreased in the RA group, especially in the difficult-to-control RA group. In contrast, serum IL-1Ra concentration was statistically higher in the RA group than that in healthy subjects before the story, and a further increase was observed after the story, especially in the easily controlled RA group. Conclusions. Our findings suggest that mirthful laughter affects the levels of serum pro- and anti-inflammatory cytokines differentially, depending on the RA disease activity.