Post Viral Bacterial Pneumonia: Role of MicroRNA and Autophagy

病毒性细菌性肺炎后：MicroRNA 和自噬的作用

• 批准号: 9038427
• 负责人: Bethany B. Moore
• 金额: $ 38.75万
• 依托单位: UNIVERSITY OF MICHIGAN AT ANN ARBOR
• 依托单位国家: 美国
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-04-01 至 2018-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9038427
• 关键词: Address; Anti-Bacterial Agents; Antibacterial Response; Autophagocytosis; Bacteria; Bacterial Infections; Bacterial Pneumonia; Cause of Death; Cessation of life; Development; Excision; Experimental Models; Failure; Goals; Grant; Health; Host Defense; ITGAM gene; Immune response; Infection; Influenza; Interferon Type II; Interferons; LoxP-flanked allele; Lung; Mediating; MicroRNAs; Morbidity - disease rate; Mus; Natural Immunity; Outcome; Patients; Phagocytosis; Pneumococcal Infections; Pneumonia; Production; Regulation; Role; Secondary Prevention; Sirolimus; Staphylococcal Infections; Streptococcus pneumoniae; Testing; Therapeutic; Transgenic Mice; United States; Up-Regulation; Viral; Viral Pneumonia; Virus Diseases; attributable mortality; cell type; cytokine; improved; improved outcome; inhibition of autophagy; insight; killings; macrophage; methicillin resistant Staphylococcus aureus; mortality; mouse model; neutralizing monoclonal antibodies; pathogen; prevent; receptor; response; superinfection; therapeutic target; therapy development

DESCRIPTION (provided by applicant): Influenza infections are a leading cause of death in the United States and worldwide, with 50 000 of deaths occurring annually in the United states alone. Although many patients succumb to the primary viral infection, a significant number of influenza-related deaths are attributable to the development of secondary bacterial infections. Why the host is more susceptible to bacterial infections post-influenza is poorly understood. A better understanding of how the host responds to sequential influenza + bacterial infection is necessary in order to develop therapies to improve outcomes. Using a murine model of sequential pulmonary influenza and methicillin-resistant Staphylococcus aureus (MRSA) or Streptococcus pneumoniae infection, we have found that these mice have decreased survival and impaired anti-bacterial responses. We also showed that host responses to post-viral pneumonia are characterized by impaired macrophage autophagy responses, and impaired macrophage phagocytosis and killing of bacteria in the lungs. These findings correlate with significant upregulation of interferon (IFN)γ and upregulation of miR 155 when compared to mice infected with either pathogen alone. Thus, we hypothesize that impaired innate immunity against MRSA in the setting of post-influenza pneumonia is due to IFNγ-induced upregulation of miR 155 which in turn blocks protective autophagy responses and prevents bacterial phagocytosis and killing. We will address these goals with the following specific aims. Aim 1) To determine the role of IFNγ in regulating miR 155 expression, host defense, cytokine production, and macrophage autophagy following infection with influenza alone, MRSA/Streptococcus pneumoniae alone or sequential infection. This aim will characterize these outcomes in single and sequential infections, will test responses in chimeric mice generated using wild-type and IFNγ receptor-/- mice and will test a therapeutic approach to block IFNγ using a neutralizing mAb. Aim 2) To determine whether the impaired host defense noted during post-viral pneumonia is due to a failure of lung macrophages to upregulate protective autophagy responses This aim will determine whether autophagy is impaired in lung macrophages post- sequential infection compared to single infection, whether this is correlated with miR 155 inhibition of DAPK1 and whether enhancement of autophagy using rapamycin/Tat Beclin-1 can improve host defense by increasing bacterial phagocytosis and killing. Aim 3) To identify the mechanism that miR-155 uses to regulate macrophage recruitment, autophagy and to impair the anti-bacterial host-defense. This aim will characterize expression of miR 155 during post-viral pneumonia and explore inhibition of autophagy during post-viral pneumonia as a result of miR 155 inhibition of DAPK1. The ability of miR 155 to regulate bacterial phagocytosis and killing also will be explored. Additionally, transgenic mice will be generated using floxed miR155 and CD11b-Cre mice enabling cell type specific removal of miR155 from macrophages further providing mechanistic insight regarding regulation of autophagy by miR 155 expression on macrophages.

描述（由适用提供）：流感感染是美国和全球的主要死亡原因，仅美国每年在美国就发生50 000人死亡。尽管许多患者屈服于原发性病毒感染，但大量与受影响相关的死亡归因于继发性细菌感染的发展。为什么宿主更容易受到细菌感染后感染后的宿主感染。必须更好地理解宿主如何应对顺序影响 +细菌感染的方法，以开发疗法以改善预后。使用顺序肺影响和耐甲氧西林金黄色葡萄球菌（MRSA）或肺炎链球菌感染的鼠模型，我们发现这些小鼠的生存率改善并损害了抗细菌反应。我们还表明，宿主对病毒后肺炎的反应的特征是巨噬细胞自噬反应受损，巨噬细胞吞噬作用受损和肺中细菌的杀伤。与单独感染任何一种病原体的小鼠相比，这些发现与干扰素（IFN）γ的显着上调（IFN）γ和miR 155的上调相关。这就是我们假设在肺炎后肺炎的情况下，对MRSA的先天免疫学障碍是由于IFNγ诱导的miR 155的上调造成的，这又可以阻止保护性自噬反应并防止细菌吞噬吞噬和杀伤。我们将以以下特定目标来解决这些目标。目的1）确定IFNγ在单独感染影响力后，单独或单独使用MRSA/链球菌或单独感染的MRSA/链球菌或顺序感染后感染IFNγ在MIR 155表达，宿主防御，细胞因子产生和巨噬细胞自噬中的作用。这个目的将在单一和顺序感染中表征这些结果，将测试使用野生型和IFNγ产生的嵌合小鼠的反应 受体 - / - 小鼠，将使用中和mAb测试一种治疗方法来阻断IFNγ。目的2）确定在肺炎后肺炎期间注意到的受损的宿主防御是否是由于肺巨噬细胞无法上调受保护的自噬反应，这种目标将决定是否在肺巨噬细胞中受到自噬的影响，是否与单一感染相比，是否会在肺巨噬细胞中与单一感染相比，并且是否与Mir 155抑制/the nib dienant/demhection nibection nibection nibection nibection in nib the the the。 Beclin-1可以通过增加细菌吞噬作用和杀伤来改善宿主防御。目标3）确定miR-155用于调节巨噬细胞募集，自噬并损害抗细菌宿主防御的机制。该目标将表征患者后肺炎中miR 155的表达，并探索因MIR 155抑制DAPK1而导致患者后肺炎期间自噬的抑制作用。还将探索miR 155调节细菌吞噬作用和杀死的能力。另外，将使用Floxed miR155和CD11b-Cre小鼠产生转基因小鼠，从而从巨噬细胞中从巨噬细胞中对MiR155进行特异性去除，从而进一步提供了关于MiR 155在巨噬细胞上表达自噬的机械洞察力。