Innate responses to systemic infection by intracellular bacteria trigger recruitment of Ly-6Chigh monocytes to the brain.

Innate Responses to Systemic Infection by Intracellular Bacteria Trigger Recruitment of Ly-6C Monocytes to the Brain

The Ly-6Chigh monocyte subpopulation transports Listeria monocytogenes into the brain during systemic infection of mice.

Mononuclear phagocytes can be used by intracellular pathogens to disseminate throughout the host. In the bloodstream these cells are generically referred to as monocytes. However, blood monocytes are a heterogeneous population, and the exact identity of the leukocyte(s) relevant for microbial spreading is not known. Experiments reported in this study used Listeria monocytogenes-infected mice to...

Killer Cell Immunoglobulin-Like Receptors Influence the Innate and Adaptive Immune Responses

Natural killer (NK) cells are a subset of lymphocytes which play a crucial role in early innate immune response against infection and tumor transformation. Furthermore, they secrete interferon-γ (IFN-γ) and tumor necrosis factor (TNF) prompting adaptive immu-nity. NK cells distinguish the unhealthy cells from the healthy ones through an array of cell-surface receptors. Human NK cells use inhibi...

Severe Listeria monocytogenes infection induces development of monocytes with distinct phenotypic and functional features.

Monocytes perform diverse roles during infection with the facultative intracellular bacterium Listeria monocytogenes. They are essential as bactericidal cells in host defense but can also become Trojan horses transporting bacteria into the brain. To explain these contrasting roles, we characterized bone marrow (BM) monocytes in steady state and generated during lethal and sublethal L. monocytog...

TNF and CD28 Signaling Play Unique but Complementary Roles in the Systemic Recruitment of Innate Immune Cells after Staphylococcus aureus Enterotoxin A Inhalation.

Staphylococcus aureus enterotoxins cause debilitating systemic inflammatory responses, but how they spread systemically and trigger inflammatory cascade is unclear. In this study, we showed in mice that after inhalation, Staphylococcus aureus enterotoxin A rapidly entered the bloodstream and induced T cells to orchestrate systemic recruitment of inflammatory monocytes and neutrophils. To study ...