Card9- and MyD88-Mediated Gamma Interferon and Nitric Oxide Production Is Essential for Resistance to Subcutaneous Coccidioides Infection
The lungs and the skin are two natural portals of entry for Coccidioides spp. that can cause a wide spectrum of diseases, from asymptotic skin lesions to life-threatening, disseminated infection. In this report, Hung et al. (p. 1166–1175) demonstrate that wild-type mice are resistant to a subcutaneous inoculation with 5 × 104 spores, while Card9−/− and MyD88−/− mice develop disseminated disease and recruit fewer gamma interferon (IFN-γ)-, interleukin-17A (IL-17A)-, reactive oxygen species (ROS)-, and nitric oxide (NO)-producing cells to the infected hypodermis. Further studies have shown that IFN-γ and NO production characterizes resistance to subcutaneous infection. This study establishes a murine model for investigating immunity against subcutaneous coccidioidomycosis.
MyD88 Signaling Mediates the Protective Inflammatory Response to RickettsiaIn Vivo
Spotted fever group rickettsiae cause potentially life-threatening infections throughout the world. Several members of the Toll-like receptor (TLR) family are involved in the host response to rickettsiae, and yet the mechanisms by which these TLRs mediate host immunity remain incompletely understood. Bechelli et al. (p. 883–893) demonstrate that MyD88 is essential for host immune protection against Rickettsia australis through mediation of the instructive signals in dendritic cells and secretion of interleukin-1β (IL-1β) and type 1 immune cytokines. These findings suggest that MyD88-mediated signaling pathways could serve as potential targets in vaccine design and therapeutic interventions during this intracellular bacterial infection.
Streptococcus pneumoniae Colonization Disrupts the Microbial Community within the Upper Respiratory Tract of Aging Mice
Colonization within the nasopharyngeal tract by Streptococcus pneumoniae is a prerequisite for pneumonia and invasive pneumococcal diseases. Although elderly individuals have significantly lower S. pneumoniae carriage rates than children, they have a higher risk of developing the associated diseases. Analysis of the upper respiratory tract microbiome by Thevaranjan et al. (p. 906–916) reveals that communities present within this microbial niche change with age, impacting S. pneumoniae colonization within elderly individuals. Using a mouse model of pneumococcal colonization with young, middle-aged, and old mice, they are able to show changes occurring within this region with age and throughout the course of pneumococcal colonization.
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- Card9- and MyD88-Mediated Gamma Interferon and Nitric Oxide Production Is Essential for Resistance to Subcutaneous Coccidioides Infection
- MyD88 Signaling Mediates the Protective Inflammatory Response to RickettsiaIn Vivo
- Streptococcus pneumoniae Colonization Disrupts the Microbial Community within the Upper Respiratory Tract of Aging Mice
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