Objectives: The aim of this study was to investigate whether the prevalence of group 2 innate lymphoid cells (ILC2s) in sinonasal tissues or in peripheral blood is associated with the postoperative outcome in chronic rhinosinusitis (CRS) patients. Design: A cross-sectional study of CRS patients undergoing endoscopic sinus surgery (ESS). Setting: The Department of Otorhinolaryngology-Head and Neck Surgery at Shiga University of Medical Science Hospital. Participants: Eleven patients with eosinophilic CRS (eCRS) and ten patients with non-eCRS were recruited. Main outcome measures: We examined the ILC2 prevalence in sinonasal tissues and in peripheral blood before and after ESS. Lund-Mackay computed tomography (LMK-CT) scores were used to evaluate the postoperative outcomes; cases with more than 50% improvement were categorized into the good outcome group, and cases with less than 50% improvement were categorized into the poor outcome group. Results: The ILC2 prevalence in sinonasal tissues was correlated with that in preoperative blood in the eCRS and non-eCRS patients. The ILC2 prevalence in sinonasal tissues and in preoperative blood was not correlated with the pre- or postoperative LMK-CT scores. Postoperatively, the ILC2 prevalence in blood was decreased in the eCRS and non-eCRS patients, and the decrease was associated with the good outcome group, but not the poor outcome group. Conclusion: The decreased ILC2 prevalence in blood may be related to good postoperative outcomes after ESS in eCRS and non-eCRS patients.

Background: Kimura disease (KD) is a rare, chronic inflammatory disorder characterized by blood eosinophilia, general itching, and subcutaneous head and neck mass lesions; however, the etiology of this disease is unknown. We hypothesized that group 2 innate lymphoid cells (ILC2s) in peripheral blood may play an essential role in the pathogenesis of KD. Methods: The prevalence of blood ILC2s and their ability to produce interleukin (IL) -4, IL-5, IL-13, and IL-31 in patients with KD were compared with those in control subjects and in patients with house dust mite (HDM) -induced allergic rhinitis (AR). Changes in blood ILC2 prevalence, blood eosinophilia, and clinical symptoms after surgery and steroid therapy were evaluated. Results: Blood ILC2 prevalence in patients with KD were eight times and six times higher than those in control subjects and in patients with AR, respectively. There was a strong positive correlation between ILC2 prevalence and blood eosinophilia. Patients with KD showed increased serum IL-13 and decreased IL-31 levels. KD patient-derived blood ILC2s produced large amounts of IL-5 and IL-13 in response to prostaglandin (PG) D 2 and leukotriene (LT) D 4, compared to ILC2s derived from control subjects and patients with AR. Surgery and systemic steroid therapy ameliorated general itching with a concomitant decrease in blood ILC2s and blood eosinophilia. Upon disease recurrence, blood ILC2 prevalence and blood eosinophilia increased concurrently with general itching. Conclusion: Increased blood ILC2s may be involved in blood eosinophilia and general itching through the production of IL-5 and IL-13 in patients with KD.

Increased blood group 2 innate lymphoid cells contribute to blood eosinophilia, elevated IgE, and itching in Kimura diseaseIchiro Tojima, MD, PhD, Shiori Hara, MD, Takuya Murao, MD, Keigo Nakamura, MD, Sayuri Yamamoto, MD, Hiroyuki Arai, MD, Hideaki Kouzaki, MD, PhD, Shino Shimizu, MD, PhD, Takeshi Shimizu, MD, PhDDepartment of Otorhinolaryngology, Shiga University of Medical Science, Otsu, Japan