Pertussis toxin targets the innate immunity through DAP12, FcRγ, and MyD88 adaptor proteins

Mechanism of TREM2/DAP12 complex affecting β-amyloid plaque deposition in Alzheimer's disease modeled mice through mediating inflammatory response

To investigate the mechanism of TREM2/DAP12 complex in mediating inflammatory responses that affect β-amyloid plaque deposition in Alzheimer's disease (AD) modeled mice. We measured escape latency and platform crossing time using the Morris water maze image automatic acquisition and software analysis system in TREM2 and DAP12 microglia knockout AD model mouse. We monitored the deposition of Aβ plaques in the mouse hippocampus using Congo red staining and measured levels. of inflammatory factors IL-6 and TNF-α by ELISA. Newborn mice with TREM2 knockout were selected for primary microglia isolation and culture, and Aged oligomer Aβ1-42 was added to the microglial culture medium to simulate the AD environment in vivo. Co-immunoprecipitation assay was used to detect the interaction between DAP12 and TREM2, and measured the inflammatory response induced by lipopolysaccharide (LPS) in mice with TREM2 and DAP12 knockdown through adeno-associated virus in BV2 microglia. The escape latency of the AD model mice with TREM2 and DAP12 knockout was higher and the number of crossing platforms lower than in the control group, whereas Aβ deposition and levels of inflammatory factors were higher. In TREM2 knockout microglial cultured with Aβ1-42, levels of IL-6 and TNF-α increased. Immunoprecipation pull-down assays showed that TREM2 binds to the membrane receptor DAP12 to form a complex. Knockout of TREM2 or DAP12 can inhibit LPS-induced microglial inflammatory responses. The TREM2/DAP12 complex inhibits the microglial inflammatory response through the JNK signaling pathway, thereby reducing the deposition of Aβ plaques and attenuation the behavioral manifestation in a mouse AD model.

Functional Programming of Innate Immune Cells in Response to Bordetella pertussis Infection and Vaccination

Despite widespread vaccination, B. pertussis remains one of the least controlled vaccine-preventable diseases. Although it is well known that acellular and whole cell pertussis vaccines induce distinct immune functionalities in memory cells, much less is known about the role of innate immunity in this process. In this review, we provide an overview of the known differences and similarities in innate receptors, innate immune cells and inflammatory signalling pathways induced by the pertussis vaccines either licensed or in development and compare this to primary infection with B. pertussis. Despite the crucial role of innate immunity in driving memory responses to B. pertussis, it is clear that a significant knowledge gap remains in our understanding of the early innate immune response to vaccination and infection. Such knowledge is essential to develop the next generation of pertussis vaccines with improved host defense against B. pertussis.

TREM2 in Neurodegenerative Diseases

TREM2 variants have been identified as risk factors for Alzheimer's disease (AD) and other neurodegenerative diseases (NDDs). Because TREM2 encodes a receptor exclusively expressed on immune cells, identification of these variants conclusively demonstrates that the immune response can play an active role in the pathogenesis of NDDs. These TREM2 variants also confer the highest risk for developing Alzheimer's disease of any risk factor identified in nearly two decades, suggesting that understanding more about TREM2 function could provide key insights into NDD pathology and provide avenues for novel immune-related NDD biomarkers and therapeutics. The expression, signaling and function of TREM2 in NDDs have been extensively investigated in an effort to understand the role of immune function in disease pathogenesis and progression. We provide a comprehensive review of our current understanding of TREM2 biology, including new insights into the regulation of TREM2 expression, and TREM2 signaling and function across NDDs. While many open questions remain, the current body of literature provides clarity on several issues. While it is still often cited that TREM2 expression is decreased by pro-inflammatory stimuli, it is now clear that this is true in vitro, but inflammatory stimuli in vivo almost universally increase TREM2 expression. Likewise, while TREM2 function is classically described as promoting an anti-inflammatory phenotype, more than half of published studies demonstrate a pro-inflammatory role for TREM2, suggesting that its role in inflammation is much more complex. Finally, these components of TREM2 biology are applied to a discussion of how TREM2 impacts NDD pathologies and the latest assessment of how these findings might be applied to immune-directed clinical biomarkers and therapeutics.