Novel Leads for the Therapy of Gram-Positive Sepsis

描述（由申请人提供）：脓毒症是重症监护病房死亡的主要原因。脓毒症是全身性细菌感染的一种常见而严重的后遗症，仅在美国，每年就有大约20万人死于脓毒症，这一数字高于艾滋病和乳腺癌的总和。感染性休克的发病机制是宿主对细菌成分反应的结果。在革兰氏阴性菌中，外膜上发现的脂多糖在诱导全身炎症反应中起主要作用，最终导致休克状态。虽然革兰氏阴性和革兰氏阳性感染的临床结果难以区分，但直到最近，革兰氏阳性菌的致病因素尚不清楚。现在有令人信服的证据表明，脂磷胆酸是革兰氏阳性生物体细胞壁的重要组成部分。在我们继续努力寻找能够特异性结合和中和革兰氏阴性脂多糖的小分子的过程中，我们发现某些类别的化合物也能抑制革兰氏阳性休克小鼠模型的致病性。在本提案中，我们的目标是根据我们已经获得的线索对选定的化合物进行初步筛选。我们将首先比较分离的、均相的脂壁酸和肽聚糖的生物活性，并验证脂壁酸与参比脂多糖在摩尔基础上具有毒性。在过去筛选的具有抗内毒素活性的许多类化合物中，发现了三类有用的线索：(1)脂多胺类；(2)树状大分子；(3)双氨基类。这些化合物的重点文库将受到两个级别的筛选。在初级筛选中，将量化脂磷胆酸对人外周血单核细胞中关键细胞因子的抑制作用。活性化合物将进行二次筛选，其中上游细胞事件（细胞因子mRNA转录）将被检查。这是为了证明细胞因子释放的抑制，如果观察到，是由于细胞对脂磷胆酸的识别受阻。

DESCRIPTION (provided by applicant): Sepsis is the leading cause of mortality in the intensive care unit. A common and serious sequel of systemic bacterial infections, sepsis accounts for some 200,000 fatalities annually in the US alone, a figure higher than that attributable to AIDS and breast cancer combined. The pathogenesis of septic shock is a consequence of the host response to bacterial components. In the Gram-negative organism, lipopolysaccharide, found on the outer membrane, plays a major role in inducing the systemic inflammatory response that ultimately leads to the shock state. Although the clinical outcome of Gram-negative and Gram-positive infections are indistinguishable, until very recently, the causative factor in the Gram-positive organism was unknown. Compelling evidence now points to a major role for lipoteichoic acid, an integral component of the cell wall in Gram-positive organisms. In the course of our continuing efforts in identifying small-molecules that would specifically bind and neutralize Gram-negative lipopolysaccharide, we have found that certain classes of compounds also inhibit lethality in murine models of Gram-positive shock. In this proposal, we aim to initiate preliminary screening of select compounds based on the leads we have already obtained. We will first compare the biological activities of isolated, homogeneous, lipoteichoic acid and petidoglycan and verify that lipoteichoic acid is toxic on a molar basis comparable to that of reference lipopolysaccharide. Of the many classes of compounds screened in the past for anti-endotoxin activity, useful leads have been found in three classes: (1) the lipopolyamines (2) dendrimers, and (3) bis-amidines. Focused libraries of these compounds will be subjected to two levels of screening. In the primary screen, the inhibition of key cytokines induced by lipoteichoic acid in human peripheral blood mononuclear cells will be quantified. Active compounds will be subjected to a secondary screen in which upstream cellular events (cytokine mRNA transcription) will be examined. This is to demonstrate that inhibition of cytokine release, if observed, is attributable to the blockade of the cellular recognition of lipoteichoic acid.