Synergy between TLR2 and IL-22R in airway epithelial cells during MRSA challenge

描述(申请人提供)：革兰氏阳性菌金黄色葡萄球菌在20-50%的人鼻腔内定植，由耐甲氧西林金黄色葡萄球菌(MRSA)引起的社区获得性肺炎正在增加。这表明有必要制定疫苗接种和/或治疗战略。Toll样受体2(Toll-like Receptor 2，TLR2)识别肽聚糖，启动对金黄色葡萄球菌的天然免疫。树突状细胞通过产生包括IL-1b和IL-23在内的多种因子来应答TLR配体。这些细胞因子调节T细胞在称为Th17分化的过程中产生IL-17和IL-22。白介素17和白介素22最近被证明可以控制金黄色葡萄球菌的肺部感染(Kudva，Scheller等人；免疫杂志，正在出版)。目前尚不清楚哪种细胞类型(S)必须表达TLR2才能在体内高效产生IL-1b和IL-23，或清除MRSA。由于气道上皮细胞(AECs)表达TLRs，是与肺部病原体接触的第一个点，它们可能在启动炎症中发挥作用。白介素22对上皮细胞有多种作用，包括增殖、存活和诱导抗菌蛋白。肠上皮细胞对IL-22的反应是通过产生再生胰岛衍生3(Reg3)家族基因，该家族基因可以直接抑制MRSA的生长(初步数据)。在肺中，IL-22受体(IL-22R1)仅限于血管内皮细胞，暴露于MRSA会增加Reg3的表达(初步数据)。这些数据导致假设AECs中的TLR2信号在MRSA感染期间启动Th17细胞向肺的募集，并与IL-22R协同通过诱导Reg3抗菌凝集素介导宿主防御。这一假说将通过以下目标进行验证：特定目标1：确定TLR2和IL-22R1在金黄色葡萄球菌USA300肺部感染过程中AECs表达的作用。将使用C57BL/6和TLR2-/-小鼠之间的骨髓嵌合体来研究TLR2在抗辐射细胞(如AECs)中的表达。IL-22R1在AECs中的作用将通过将上皮特异性CRE小鼠与IL22R1-Flobled小鼠杂交来确定。这些实验将确定TLR2和IL-22R1信号在MRSA感染过程中在AECs中的互补作用。具体目标2：确定Reg3家族凝集素作为IL-22R下游可能的效应因子的作用。体外实验将确定TLR配体和IL-22是否协同诱导气管上皮细胞中的Reg3。体内实验将检验Th17衍生的细胞因子在Reg3表达中的作用。Reg3g-/-小鼠将被用来阐明其在控制MRSA感染方面的作用。

DESCRIPTION (provided by applicant): The gram-positive organism Staphylococcus aureus colonizes the nasal passages in 20-50 percent of people, and community-acquired pneumonia caused by methicillin-resistant S. aureus (MRSA) is increasing. This suggests a need to develop vaccination and/or treatment strategies. Toll-like receptor 2 (TLR2) recognizes peptidoglycan and initiates natural immunity to S. aureus. Dendritic cells respond to TLR ligands by producing many factors including IL-1b and IL-23. These cytokines condition T cells to produce IL-17 and IL-22 during a process called Th17 differentiation. Interleukin-17 and IL- 22 were recently shown to control lung S. aureus infection (Kudva, Scheller, et al; J Immunol, in press). It is not known which cell type(s) must express TLR2 for efficient production of IL-1b and IL-23 in vivo, or for clearance of MRSA. Since airway epithelial cells (AECs) express TLRs and are the first point of contact with lung pathogens, they could play a role in initiating inflammation. Interleukin-22 has multiple effects on epithelial cells including proliferation, survival, and induction of antimicrobial proteins. Intestinal epithelial cells respond to IL-22 by producing regenerating islet-derived 3 (Reg3) family genes, which can directly inhibit the growth of MRSA (preliminary data). In the lung, the IL-22 receptor (IL-22R1) is restricted to AECs, and exposure to MRSA increased Reg3 expression (preliminary data). These data led to the hypothesis that TLR2 signaling in AECs initiates Th17 cell recruitment to the lung during MRSA infection, and also synergizes with IL-22R to mediate host defense through the induction of Reg3 antimicrobial lectins. This hypothesis will be tested with the following aims: Specific Aim 1: Determine the roles of TLR2 and IL-22R1 expression in AECs during lung infection with S. aureus USA300. TLR2 expression in radio-resistant cells such as AECs will be studied using bone marrow chimeras between C57BL/6 and TLR2-/- mice. The role of IL-22R1 in AECs will be determined by crossing epithelial-specific-Cre mice with IL22R1-floxed mice. These experiments will establish the complementary roles of TLR2 and IL-22R1 signaling in AECs during MRSA infection. Specific Aim 2: Determine the role of Reg3 family lectins as possible effectors downstream of IL-22R. In vitro experiments will determine if TLR ligands and IL-22 synergize to induce Reg3 in tracheal epithelial cells. In vivo experiments will examine the role of Th17-derived cytokines in Reg3 expression. Reg3g-/- mice will be used to clarify its role in controlling MRSA infection.