Hyper-Responsiveness to TLR Agonists in Wild Derived Mice

先天免疫系统对病原体的识别激活tlr介导的途径，导致NFB诱导炎症细胞因子的转录。这些分子随后引导适当的适应性反应的启动，最终导致清除或遏制入侵的病原体。然而，由于其强大的生物活性，不适当地延长或过度释放促炎介质可导致对宿主的有害影响。急性期细胞因子白细胞介素-6 （IL-6）就是一个例子，其在T细胞潜在致病性Th17亚群的发展中所起的作用最近已被描述。考虑到促炎细胞因子的双重性质，促炎细胞因子对宿主防御至关重要，但过量可能致命，哺乳动物免疫系统已经进化出许多调节机制来精确控制炎症反应的大小和时间过程。因此，用于微调这一过程的分子机制是积极研究的主题。在这里，我们提出利用对近交系（C57BL/6J）和野生衍生（MOLF/Ei, Czech/EiII, MSM/Ms）小鼠品系的正向遗传分析，作为一种新的方法来描述TLR刺激下分泌不同量的IL-6的调节。一组回交小鼠的初步研究已经确定了6号和9号染色体上的两个位点，它们对这一特征起着重要作用。此外，这两个基因座具有显著的上位性相互作用（p < 10-6, LRS 48.1）。我们之前的定位结合微阵列分析已经揭示了一个基因Simpl（又名IRAK1BP1）的身份，对表型有负贡献。我们现在建议通过减数分裂重组来定位和鉴定其他对表型有积极贡献的基因。我们还建议为它们观察到的上位相互作用建立机制基础。关于SIMPL的抗炎作用，我们拟探讨SIMPL对tlr介导的信号传导抑制作用的机制。本提案旨在通过更精细的遗传分析以及候选基因的生化和分子表征来解决问题。我们相信我们将揭示TLR信号传导的重要新机制。

Recognition of pathogens by the innate immune system activates TLR-mediated pathways, resulting in NFB induced transcription of inflammatory cytokines. These molecules subsequently direct the initiation of appropriate adaptive responses, leading ultimately to clearance or containment of the invading pathogen. Due to their potent biological activity, however, inappropriately prolonged or excessive release of pro-inflammatory mediators can result in deleterious effects for the host. This is exemplified by the acute phase cytokine interleukin-6 (IL-6), whose role in the development of the potentially pathogenic Th17 subset of T cells has recently been described. Given the dual nature of pro-inflammatory cytokines, essential for host defense but potentially lethal in excessive quantities, the mammalian immune system has evolved numerous regulatory mechanisms to precisely control the magnitude and time-course of inflammatory responses. The molecular mechanisms used in fine-tuning this process are therefore the subject of active investigation. Here we propose using a forward genetic analysis of inbred (C57BL/6J) and wild derived (MOLF/Ei, Czech/EiII, MSM/Ms) mouse strains that secrete different amounts of IL-6 in response to TLR stimulation as a novel approach to characterizing the regulation of early cytokine release. Initial studies from a panel of backcross mice have identified two loci on chromosomes 6 and 9 that make major contributions to the trait. Further, these two loci have a significant epistatic interaction (p < 10-6, LRS 48.1). Our previous mapping combined with micro-array analysis had revealed the identity of one gene as Simpl (a.k.a. IRAK1BP1) with a negative contribution to the phenotype. We now propose to map via meiotic recombination and identify other gene(s), which positively contribute to the phenotype. We also propose to establish the mechanistic basic for their observed epistatic interaction. With respect to anti-inflammatory role of SIMPL, we propose to investigate the mechanism of inhibitory effect of SIMPL in TLR-mediated signaling. This proposal aims to approach the problem through more refined genetic analysis as well as biochemical and molecular characterization of the candidate genes. We believe that we will reveal important novel mechanisms of TLR signaling.