Boyd Angela R, Orihuela Carlos J
Department of Microbiology and Immunology, The University of Texas Health Science Center at San Antonio, 7703 Floyd Curl Drive, San Antonio Texas 78229-3900 USA.
Aging Dis. 2011 Dec;2(6):487-500.
Advances in modern medicine have led to an increase in the median life span and an expansion of the world's population over the age of 65. With increasing numbers of the population surviving to the extreme of age, those at risk for the development of pneumonia will approach 2 billion by the year 2050. Numerous age-related changes in the lung likely contribute to the enhanced occurrence of pneumonia in the elderly. Inflammation in the elderly has been shown to increase risk prior to infection; age-associated inflammation enhances bacterial ligand expression in the lungs which increases the ability of bacteria to attach and invade host cells. Conversely, the elaboration of the acute inflammatory response during early infection has been found to decrease with age resulting in a delayed immune response and diminished bacterial killing. Finally, the resolution of the inflammatory response during the convalescent stage back to "baseline" is often prolonged in the elderly and associated with negative outcomes, such as adverse cardiac events. The focus of this review will be to discuss our current understanding of the potential mechanisms by which dysregulated inflammation (both prior to and following an infectious insult) enhances susceptibility to and severity of community acquired pneumonia (CAP) in the elderly with an emphasis on pneumococcal pneumonia, the leading cause of CAP.
现代医学的进步导致了平均寿命的延长以及全球65岁以上人口数量的增加。随着越来越多的人活到高龄，到2050年，有患肺炎风险的人数将接近20亿。肺部众多与年龄相关的变化可能导致老年人肺炎发病率增加。研究表明，老年人在感染前炎症就会增加患病风险；与年龄相关的炎症会增强肺部细菌配体的表达，从而增加细菌附着和侵入宿主细胞的能力。相反，随着年龄的增长，早期感染期间急性炎症反应的程度会降低，导致免疫反应延迟和细菌杀灭能力减弱。最后，恢复期炎症反应恢复到“基线”的过程在老年人中通常会延长，并与不良后果相关，如不良心脏事件。本综述的重点将是讨论我们目前对失调炎症（感染性损伤之前和之后）增加老年人社区获得性肺炎（CAP）易感性和严重程度的潜在机制的理解，重点是肺炎球菌肺炎，这是CAP的主要病因。
