Alcohol Intoxication and Postburn Intestinal Immunity

描述(由申请人提供)：本R01申请是对NIAAA PA-12-025的回应，目的是调查酒精暴露促进烧伤后发病的机制。研究表明，烧伤时醉酒的患者更容易感染，与受伤时未醉酒的烧伤患者相比，其发病率和死亡率明显更高。乙醇促进烧伤后发病的机制仍很不清楚。肠道是体内细菌的主要储存库；在健康的条件下，它保持着一种屏障，阻止这些细菌穿过肠腔。然而，这种屏障在酒精(乙醇)暴露和烧伤后受到损害。我们发现酒精中毒合并烧伤：1)抑制肠道相关淋巴组织[Peyer‘s patches(PP)和肠系膜淋巴结(MLN)]Th1(IL-2和IFN-β)和Th17(IL-17和IL-22)细胞因子的产生；2)增加肠道中IL-18的水平；3)导致肠道组织损伤和渗漏；4)在伤后24小时内增加肠道细菌的生长和细菌移位。细菌和/或其产物移位的这种增加可能会使全身炎症反应持续存在，并最终导致酒精暴露和烧伤后较差的结果。最近的研究表明，Th17淋巴细胞及其效应细胞因子IL-17和IL-22在维持粘膜免疫和屏障完整性方面起着至关重要的作用。我们的发现提示IL-22和IL-18在维持粘膜完整性中的作用。我们研究的总体目标是阐明酒精合并烧伤抑制Th17效应细胞因子的机制(S)，以及这种Th17细胞因子的减少与IL-18一起或不加IL-18如何导致酒精和烧伤后肠道免疫和上皮屏障受损。我们假设“烧伤前酒精中毒导致Th17效应细胞因子、IL-17和IL-22减少，当IL-18增加时，会损害肠道免疫和屏障完整性，促进肠道细菌生长和随后的肠道细菌移位。”这一假说将通过建立酒精中毒和烧伤的小鼠模型在3个目标上进行验证。目标1的研究将确定烧伤前酒精暴露导致肠道Th17细胞因子减少的机制(S)。目的2将探讨烧伤前乙醇暴露导致肠道渗漏增加的机制(S)。目标3将研究IL-22恢复是否单独或与IL-18抑制联合使用可使抗菌肽正常化(例如，Reg3？那么Reg3呢？)以及这是否可以防止酒精暴露和烧伤后肠道细菌负荷增加及其移位。总体而言，我们的研究将对乙醇中毒与烧伤合并破坏肠道屏障的机制产生新的见解，并可能有助于为这一患者群体开发更好的治疗策略。

DESCRIPTION (provided by applicant): This R01 application in response to NIAAA PA-12-025 is to investigate the mechanism by which alcohol exposure enhances post burn pathogenesis. Studies have shown that patients who are intoxicated at the time of burn injury are more susceptible to infection and exhibit significantly higher morbidity and mortality compared to burn patients who are not intoxicated at the time of injury. The mechanism by which ethanol enhances post burn pathogenesis remains largely unclear. Gut is the major reservoir of bacteria within the body; under healthy conditions it maintains a barrier which prevents these bacteria from crossing the intestinal lumen. However, this barrier is compromised following alcohol (ethanol) exposure and burn injury. We found that ethanol intoxication combined with burn injury: 1) suppresses gut associated lymphoid [Peyer's patches (PP) and mesenteric lymph nodes (MLN)] Th1 (IL-2 and IFN-?), and Th17 (IL-17 and IL-22) cytokine production; 2) increases IL-18 levels in the gut; 3) causes gut tissue damage and leakiness; and 4) increases gut bacterial growth and bacterial translocation within 24 hours after injury. Such an increase in the translocation of bacteria and/or their products may perpetuate the systemic inflammatory response and ultimately contribute to poorer outcomes following ethanol exposure and burn injury. Recent findings indicate that Th17 lymphocytes and their effector cytokines, IL-17 and IL-22, play a crucial role in maintaining mucosal immunity and barrier integrity. Our findings suggest a role for IL-22 and IL-18 in maintaining mucosal integrity The overall goal of our studies is to delineate the mechanism(s) by which ethanol combined with burn injury suppresses Th17 effector cytokines and how this decrease in Th17 cytokines with or without IL-18 contributes to impaired gut immunity and epithelial barrier following alcohol and burn injury. We hypothesize that "Ethanol intoxication prior to burn injury results in decreased Th17 effector cytokines, IL-17 and IL-22, which when combined with an increase in IL-18 compromises gut immunity and barrier integrity, facilitating gut bacterial growth and subsequent gut bacterial translocation." The hypothesis will be tested in 3 Aims using a well-established mouse model of ethanol intoxication and burn injury. Studies in Aim 1 will determine the mechanism(s) by which ethanol exposure prior to burn injury results in decreased Th17 cytokines in the intestine. Aim 2 will investigate the mechanism(s) by which ethanol exposure prior to burn injury results in increased gut leakiness. Aim 3 will investigate whether IL-22 restoration alone or in combination with IL-18 inhibition normalizes antimicrobial peptides (e.g. Reg3? and Reg3?) and whether this prevents increased gut bacterial load and their translocation following ethanol exposure and burn injury. Overall, our studies will yield novel insights into the mechanism by which ethanol intoxication combined with burn injury disrupts the gut barrier and may help in developing better therapeutic strategies for this patient population.