Duringaninfection,animalsexhibitadaptivechangesinbehaviorandphysiologyaimedatincreasingsurvival. Although many causes of acute infection exist, a similar set of stereotyped symptoms occur, which includes increasedbodytemperatureorfever,decreasedappetiteandincreasedlethargy.Bothwarm-andcold-blooded animals generate a fever in response infection suggesting that fever circuits are hard-wired and highly conserved,yetexactlyhowthenervoussystemaltersbodytemperatureandassociatedbehaviorinresponseto infectionremainsunknown.Wehaveidentifiedapopulationofneuronsinthepreopticareaofthehypothalamus that are highly activated following administration of inflammatory lipopolysaccharides (LPS). Due to the close proximitybetween the organum vasculosum of the laminae terminalis (OVLT), where inflammatory cytokines enterthebraintoaffectnearbycells,andneuronsofthepreotpicarearegulatingnormalbodytemperature,and ourpreliminarydata,weproposethatthesenewlyidentifiedLPS-sensitiveneuronscontrolfeverinitiationduring animmuneresponse.Wewillusechemogeneticactivationandcellablationapproachestodemonstratethatthis populationplaysaroleinincreasingbodytemperatureandinaffectingotherfever-associatedbehaviorsupon LPSinjection.Further,wehaverecentlydevelopednewapproachesformolecularcharacterizationofgenetically defined cell populations in situ using single-cell RNA sequencing (scRNA-seq) and multiplex, error-robust, fluorescentinsituhybridization(MERFISH)togenerateaspatially-resolvedandfunctionally-awareatlasofthe preopticarea.Wewillapplyasimilarstrategytocharacterizefever-inducingneuronsaswellassurroundingnon- neuronal cell types thatare likely to play a role infevergeneration throughparacrine mechanisms.Finally, we proposetouseviral-mediatedtracingandfunctionaltoolstodeterminethedirectandindirectcircuitmechanisms by which LPS-sensitive neurons and their targets exert control over body temperature and fever-related behaviors. Our data will lead to a molecular and functional characterization of LPS-sensitive neurons in the preopticareaandtoabetterunderstandingofhowinflammatorysicknesssymptoms,suchasfeverandrelated behavioral changes, are regulated in the brain. These efforts have direct implications for understanding the mechanismsunderlying human sickness,and may inform newtherapeutic strategiesforthetreatment offever andassociatedsymptoms.
During an infection, animals display a stereotyped set of symptoms aimed at increasing survival, such as elevation in core temperature aimed to fight pathogens (fever), decreased activity and appetite. Advanced molecular and genetic technologies allow for the dissection of dedicated neural pathways involved in specific physiological and behavioral responses, providing novel targets for diagnosis and therapeutic development. This proposal aims to leverage cutting edge molecular and genetics approaches to uncover the specific neuronal populations and neural circuits underlying the generation of fever and associated sickness symptoms.
