Traditional Chinese medicine, Xin-yi-san, reduces nasal symptoms of patients with perennial allergic rhinitis by its diverse immunomodulatory effects

Perennial allergic rhinitis (AR) is a common health problem with a high prevalence rate of 43.6% in Taiwan. In our previous study, a mixed formula of Chinese herbs consisted of Xin-yi-san, Xiao-ging-long-tang, and Xiang-sha-liu-jun-zi-tang, exerted diverse immunomodulatory effects in the treatment of patients with perennial allergic rhinitis. The aim of the present study was to determine whether Xin-yi-san (XYS) alone is effective in the treatment of AR and tried to explore its molecular mechanism of anti-allergic activity. In a randomized double-blind study, 108 patients with AR received either XYS or a placebo for 3 months. The effectiveness of XYS was evaluated by nasal symptoms, nasal airflow resistance, nostril dissection area, and serum titer of specific IgE antibodies against house dust mite allergens. In addition, the production of T helper (Th) 1 (represented by interferon-γ) and Th2 [represented by interleukin (IL)-4, IL-10, and IL-13] cytokines, the proinflammatory cytokine IL-8, soluble intercellular adhesion molecule (sICAM), and arachidonate metabolites prostagladin E2 (PGE2) and leukotriene C4 (LTC4) by polymorphonuclear neutrophils (PMNs) were compared before and after treatment between the two groups. XYS attenuated nasal symptoms (sneezing and rhinorrhea) and nasal congestion through reduction of nasal airflow resistance and increase in nostril dissection areas. We also found that XYS exerted diverse immunomodulatory effects, including suppression of serum IgE levels and increased production of IL-10, sICAM-1, and IL-8 compared to placebo group. However, XYS treatment did not affect the release of PGE2 and LTC4 from PMNs. This study originally provides the evidence that Xin-yi-san alone is an effective herb in the treatment of perennial allergic rhinitis.