Effective treatment of psoriasis with etanercept is linked to suppression of IL17 signaling, not immediate response TNF. Homo sapiens

The success of TNF inhibitors for treatment of psoriasis and other inflammatory diseases was previously attributed to blockade of innate immunity. In a clinical trial using etanercept TNF blocking agent to treat psoriasis vulgaris, we used affymetrix gene arrays to analyze broad gene profiles in lesional skin at multiple timepoints during drug treatment (baseline, and weeks 1, 2, 4 and 12) compared to non-lesional skin. This analysis created a temporal model of TNF-dependent gene regulation that informs molecular mechanisms of TNF-mediated inflammation. We identified four gene clusters that were differentially down-modulated during etanercept treatment: the cluster down-regulated most rapidly contained mostly dendritic cell activation genes. Culturing human keratinocytes with TNF, IFNg and IL-17 generated a list of keratinocyte genes regulated by each cytokine. The IL-17 pathway genes were strongly down-modulated early, whereas IFNg pathway genes were not down-modulated until final disease resolution at week 12. Finally, we show that TNF blockade rapidly inhibits IL-12/IL-23 p40 subunit expression, and that p40 neutralization inhibits psoriatic dermal émigré-mediated Th17 polarization. We hypothesize that etanercept inhibits myeloid dendritic cell production of IL-23, a Th17 survival cytokine, resulting in rapid downregulation of IL-17 pathway genes. This data links effects of TNF blockade on the innate immune system with the adaptive immune system. Keywords: time-course experiment Overall design: In this study 15 patients with moderate-to-severe psoriasis were given 50mg of etanercept (Amgen) biweekly for 12 weeks. And analyzed using gene array on mRNA extracted from tissue collected at each biopsy time point (non-lesional Time: 0; lesional Time: 0, weeks 1, 2, 4, and 12). Patients were stratified as “responders” or “non-responders” based on whether or not they achieved histologic disease resolution by week 12 of etanercept treatment (decreased epidermal thickening, normalization of proliferation marker Ki67, and loss of differentiation marker K16).

既往研究认为，肿瘤坏死因子（TNF）抑制剂治疗银屑病及其他炎症性疾病的疗效，源于对固有免疫的阻断。本研究采用依那西普（etanercept，TNF阻断剂）治疗寻常型银屑病患者，在药物治疗的多个时间节点（基线、第1、2、4、12周）采集皮损皮肤样本，并以非皮损皮肤作为对照，利用Affymetrix基因芯片（Affymetrix gene arrays）分析全基因表达谱。

该分析构建了TNF依赖型基因调控的时序模型，为阐明TNF介导的炎症分子机制提供了关键依据。研究团队鉴定出4个依那西普治疗期间差异下调的基因簇：其中下调速度最快的基因簇主要包含树突状细胞活化相关基因。

研究人员采用TNF、干扰素γ（IFNγ）与白细胞介素17（IL-17）培养人角质形成细胞，得到了受各细胞因子调控的角质形成细胞基因列表。IL-17通路基因在治疗早期即出现显著下调，而IFNγ通路基因仅在第12周疾病最终缓解时才发生下调。

此外，本研究证实TNF阻断可快速抑制IL-12/IL-23 p40亚基的表达，且p40中和可抑制银屑病皮肤迁出细胞介导的Th17细胞极化。研究团队提出假说：依那西普可抑制髓系树突状细胞分泌IL-23——一种Th17存活细胞因子，从而快速下调IL-17通路基因。本数据集将TNF阻断对固有免疫系统的作用与适应性免疫系统关联起来。

关键词：时序实验
整体实验设计：本研究纳入15名中重度银屑病患者，予依那西普（etanercept，安进（Amgen）公司研发）50mg，每两周给药一次，持续12周。在各活检时间点采集组织样本，提取mRNA后进行基因芯片分析：非皮损皮肤采样时间点为0；皮损皮肤采样时间点为0、第1、2、4、12周。根据患者在第12周治疗后是否达到组织学疾病缓解（表皮增厚减轻、增殖标志物Ki67恢复正常、分化标志物K16丢失），将其分为"应答者"与"无应答者"。