Altered expression of IL-18, IL-18 binding protein and IL-18 receptor in blood monocytes of patients with allergic rhinitis [post]

2020 unpublished
Interleukin (IL)-18 is emerging as an attractive participant in allergic rhinitis (AR). However, correlation of IL-18 with IL-18 binding protein (BP) in plasma, and expression of IL-18, IL-18BP and IL-18 receptor (R) in AR blood monocytes remains obscure. Methods: We investigated IL-18, IL-18BP and IL-18R expression in monocytes by using flow cytometric analysis, murine AR model, and quantitative realtime PCR in the present study. Results: It was found that plasma IL-18 and IL-1β in AR patients
more » ... was higher than those in healthy control subjects. Free (f)IL-18 had a high correlation with IL-18BP, IL-1β and TNF-α in AR plasma. Proportion of IL-18 + monocytes was increased, whereas IL-18BP + monocytes were decreased in blood of patients with AR. It was found that Platanus pollen allergen extract provoked the elevated expression of IL-18 and IL-18R in AR blood monocytes. Dermatophagoides pteronyssinus , Artemisia sieversiana wild and Platanus pollen allergen extracts enhanced IL-18R protein and mRNA expression in primary monocytes from AR patients. Moreover, numbers of macrophages and IL-18R + macrophages in nasal lavage fluid (NLF) were increased, and levels of IL-18 in both plasma and NLF were elevated in AR mice. Conclusions: IL-18 is likely to participate in the development of AR as a causative factor, therefore it could be a therapeutic target for AR. Background IL-18, initially discovered as interferon (IFN)-γ-inducing factor constitutively expressed by monocytes and macrophages, and plays regulatory roles in both innate and adaptive immunity. It is reported that polymorphisms of IL-18 gene was associated with AR [1-5], and up-regulated IL-18 is found in both nasal secretion and serum of AR patients [6, 7]. It is also observed that elevated serum IL-18 during natural pollen exposure is closely associated with bronchial hyperresponsiveness in seasonal AR (sAR) patients [8]. These implicate that monocyte-and macrophage-derived IL-18 likely contributes to the pathogenesis of AR. IL-18 binds initially to IL-18R then initiates MyD88-dependent signal pathway and exert immunomodulatory functions [9]. IL-18 binding protein (IL-18BP) is an endogenous soluble antagonist 4 that specifically inhibits IL-18 action by binding to IL-18 with high affinity [10]. Free serum IL-18BP is present at 20fold higher levels than free IL-18 in physiological status [11]; however, under allergic conditions IL-18 may be in excess [12]. These suggest an imbalance between IL-18 and IL-18BP expression may account for increased IL-18 activity in AR. Indeed, we reported recently that the role of IL-18 in atopic asthma is determined by the balance of IL-18/IL-18BP/IL-18R [13]. Since level of circulating IL-18BP in AR plasma/serum has not been reported, we examined level of IL-18BP in AR plasma in the present study. It has been reported that pollen allergen specific subcutaneous immunotherapy induced increased serum IL-18 in AR patients [14] , pollen allergen extract could provoke IL-18 mRNA expression in PBMCs of patients with AR undergoing allergen immunotherapy [15] [16] [17] , suggesting that allergens may contribute to AR through PBMCs and IL-18-related mechanisms. Since monocytes are one of the major cell types of PBMCs, and little is known about expression of IL-18, IL-18BP and IL-18R at protein and mRNA levels in monocytes of AR, particularly upon allergen challenge. Therefore, the aim of the present study is to investigate levels of IL-18 and IL-18BP in AR plasma, expression of IL-18, IL-18BP and IL-18R in monocytes of patients with AR, and influence of allergens on their expression. Materials And Methods Reagents The following reagents were purchased from Biolegend (San Diego, CA, USA): human red blood cell lysis buffer, Brilliant Violet 510 TM (BV510)-conjugated donkey anti-rabbit IgG polyclonal antibody, PE/Cy7-conjugated mouse anti-human CD14 monoclonal antibody, BV510-conjugated rat anti-mouse Ly-6G/Ly-6C (Gr-1) monoclonal antibody, BV510-conjugated rat anti-mouse F4/80 monoclonal antibody, PerCP-conjugated rat anti-mouse CD11b monoclonal antibody, human Fc receptor blocking solution, rat anti-mouse CD16/32 antibody, Brefeldin A, Zombie NIR TM Fixable Viability Kit, and Zombie Green TM Fixable Viability Kit. Mouse IL-18BPd DuoSet ELISA kit, APC-conjugated mouse antihuman IL-18Rα monoclonal antibody, PE-conjugated mouse anti-human IL-18 monoclonal antibody,
doi:10.21203/rs.2.24683/v1 fatcat:inzkwue6knfdnolmq4ptcnjsoe