Project Summary:
TBI is a serious public health concern, and in 2014 alone 2.53 million emergency visits, hospitalizations, and
death occurred in USA. In human post-mortem studies, accumulation of microglia/monocyte-derived
macrophages (MDM), the key mediators of chronic neuroinflammation were detected, even after several years
of TBI. Microglia -the resident immune cells- maintain the delicate neuronal microenvironment under
physiological conditions through surveillance and proliferate when needed under injury or pathological
conditions. Upon injury to the CNS from TBI, monocytes enter the brain and differentiate into MDM, and become
morphologically indistinguishable from the activated microglia. Microglia/MDMs have been reported to contribute
significantly to traumatic brain injury (TBI) pathology. However, it remains unclear how monocytes/MDM are
functionally distinct from microglia at the subcellular (RNA), cellular, and network levels. Our central hypothesis
is that after TBI, microglia and MDM contribute differently to the chronic inflammatory response, neuronal
excitability, and behavioral deficits. Hence, the objective of this study is to develop an in-depth understanding
of: i) how mRNA changes in MDMs/microglia affect injury progression, ii) how they interact with each other and
blood vessels, and iii) how MDMs influence neuronal activity and subsequent behavioral outcomes, compared
to resident microglia. This understanding may help the development of effective diagnostics, prognostics and
therapeutics. Our proposal to use double transgenic reporter mice, RNA sequencing, chronic-two photon imaging
and electrophysiological tools in blast TBI condition is the very first attempt to provide the needed knowledge.