IL-17C mediated mechanisms of inflammation

描述(申请人提供)：IL-17C是IL-17细胞因子家族中一个新的和功能不同的成员，通过IL-17RE和IL-17RA促进上皮细胞的天然防御和调节Th17细胞的分化。在人类银屑病组织中，IL-17C在皮损中高表达，并定位于角质形成细胞(KCs)、内皮细胞(ECs)和白细胞，并对其发挥作用。我们的初步数据显示，在IL-17C刺激后，CD4T细胞来源的IL-17A和IL-22(Th17和Th22)以及EC来源的TNFa增加。有趣的是，IL-17C和肿瘤坏死因子�刺激的KCs产生与IL-17A/肿瘤坏死因子�相似的协同炎症基因反应模式(但幅度更高)，并且这些基因反应模式随着IL-17A的加入而进一步增强，表明内皮、表皮和Th17/22细胞之间存在正的促炎反馈循环。在接受TNFa抑制剂治疗的银屑病患者中，皮肤IL-17C的表达在皮肤改善前迅速下降(在72小时内)，血清IL-17A和IL-22水平下降，提示IL-17C可能是一种新的机制，放大Th17/22/TNFa介导的炎症信号对银屑病的发病至关重要。为了进一步探索IL-17C在介导银屑病样炎症中的重要性，我们通过基因工程使小鼠在KCs中过表达IL-17C。小鼠皮肤形成界限清晰的非受累组织区域，其特征是血管生成增加，在没有表皮增生的情况下有适度的白细胞渗透，以及邻近受累皮肤区域表现出强烈的表皮增生，白细胞浸润增加，以及TNFa、IL-17A和IL-22的增加；提示IL-17C与其他促炎信号结合时，导致银屑病样皮炎的发生。综上所述，这些观察结果表明，IL-17C是IL-17家族中一个快速反应的成员，它协同激活KCs、内皮细胞和Th17/22细胞之间的促炎反馈回路，可能在银屑病中起关键作用。我们将使用这一创新的新小鼠模型、基因敲除方法、cre-lox技术和抗体靶向策略，结合体外细胞共培养、小干扰RNA、细胞信号和生物测定方法来验证以下假设：IL-17C结合靶细胞上的IL-17RE/A上调与IL-17C协同结合的肿瘤坏死因子�(EC)和IL-17/IL-22(Th17/22)，从而诱导KC激活和表皮增生。我们打算确定IL-17C是启动和维持慢性皮肤炎症所需的关键的早期上游促炎细胞因子，并确定受影响的关键细胞靶点。 通过IL-17C以及用于指导KC、EC和Th17/22细胞反应的潜在机制(S)，转化为银屑病中持续的炎症和棘皮病。这项工作将为未来探索靶向IL-17C或IL-17RE治疗银屑病的治疗开发的可能性提供基础和合理性。

DESCRIPTION (provided by applicant): IL-17C is a novel and functionally distinct member of the IL-17 family of cytokines and acts through IL- 17RE and IL-17RA to promote innate defense in epithelial cells and regulate Th17 cell differentiation. In human psoriasis tissue, IL-17C is highly expressed in lesional skin and localizes to and exerts effects upon keratinocytes (KCs), endothelial cell (ECs) and leukocytes. Our preliminary data demonstrates increases in CD4+ T cell-derived IL-17A and IL-22 (Th17 and Th22) and EC-derived TNFa following IL-17C stimulation. Interestingly, KCs stimulated with IL-17C and TNF� produce similar synergistic inflammatory gene response patterns as those elicited by IL-17A/TNF� (but at higher magnitudes) and these gene response patterns are further enhanced with the addition of IL-17A, indicating a positive pro-inflammatory feedback loop between the endothelium, epidermis and Th17/22 cells. In psoriasis patients treated with TNFa inhibitors, cutaneous IL-17C expression decreases rapidly (within 72h) prior to skin improvement and decreases in serum levels of IL-17A and IL-22 suggesting IL-17C may serve as a novel mechanism for amplifying Th17/22/TNFa mediated inflammatory signaling critical for psoriasis pathogenesis. To further explore the importance of IL-17C in mediating psoriasiform inflammation, we genetically engineered mice to overexpress IL-17C in KCs. Murine skin develops well demarcated areas of uninvolved tissue, characterized by increased angiogenesis and modest leukocyte infiltration in the absence of epidermal hyperplasia as well as adjacent areas of involved skin that exhibit robust epidermal hyperplasia, increased leukocyte infiltration and increases in TNFa, IL-17A, and IL-22; suggesting that IL-17C, when coupled with other pro-inflammatory signals, leads to the development of psoriasiform skin dermatitis. Taken together, these observations suggest that IL-17C is a rapidly responsive member of the IL-17 family and that it synergistically activates a proinflammatory feedback loop between KCs, the endothelium and Th17/22 cells and may be critical in psoriasis. We will use this innovative new mouse model, genetic knockout approaches, cre-lox technologies and antibody targeting strategies coupled with in vitro cell co-culture, SiRNA, cell signaling and bioassay approaches to test the hypothesis that: IL-17C binding IL-17RE/A on target cells up regulates TNF� (EC) and IL-17/IL-22 (Th17/22) that combine synergistically with IL-17C to induce KC activation and epidermal hyperplasia. We intend to identify IL-17C as a critical early upstream proinflammatory cytokine required for initiating and sustaining chronic skin inflammation, and identify the key cellular targets affected by IL-17C as well as the potential mechanism(s) used to direct KC, EC and Th17/22 cell responses that translate to sustaining inflammation and acanthosis in psoriasis. This work will provide the basis and justification for future work exploring the potential of targeting IL-17C or IL-17RE for therapeutic development for the treatment of psoriasis.