Unfolded Protein Response Activation as a Determinant of the Host Response to M. tuberculosis

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It is estimated that roughly 10 million people fall ill with TB annually. Even when successfully cured with antibiotics, TB patients often suffer from permanently impaired lung function resulting from infection associated inflammation. Host directed therapies that limit nonproductive inflammation represent a promising tool to improve disease outcomes. Development of these therapies has been hindered by the extent of heterogeneity observed in individual responses to Mtb infection. To overcome this limitation, novel approaches must be utilized to understand the pathways underlying these variable outcomes. The applicant proposes the use of the genetically diverse collaborative cross (CC) panel of inbred recombinant mouse strains to characterize the features underlying variable responses to infection. Preliminary studies leveraging the diversity of the CC founder strains revealed that variability in unfolded protein response (UPR) activity may underlie the heterogeneity in immune responses to Mtb infection. The UPR is a mechanism for ensuring endoplasmic reticulum homeostasis and consists of three distinct signaling pathways that initiate complementary responses. The activity of these pathways is influenced by a variety of cell stress, homeostatic, and pathogen sensing pathways, emphasizing the UPRs identity as a convergence point downstream of many potential sources of host variation. This proposal aims to detail the contribution of UPR activity to myeloid responses to Mtb and to determine the feasibility of targeting the individual UPR pathways for therapeutic intervention. The experiments proposed in aim 1 will identify downstream correlates of UPR activity during infection and assess the contribution of the UPR pathways to transcriptional response heterogeneity using single cell RNAseq technology. The studies described in aim 2 will characterize the consequences of chemical and genetic inhibition of UPR pathways on macrophage functions during Mtb infection. Aim 3 will assess the impact of myeloid UPR pathway activity on disease progression following pulmonary Mtb infection using a combination of genetics- and inhibitor- based approaches. Together, these studies will provide insights regarding immune response heterogeneity and the contribution of the UPR pathways to Mtb infection outcomes. The applicant will carry out the proposed studies as part of the Sassetti research group at the University of Massachusetts Chan Medical School. This environment will provide them with the facilities necessary to complete their studies, and input from a collaborative group of scientists with expertise in relevant fields including immunology and bacteriology. By completing the proposed studies, the applicant will gain experience in a variety of experimental techniques, including single cell RNAseq, and flow cytometry. Additionally, through the training detailed in the proposal, the applicant will develop the professional and communication skills necessary for success as an independent researcher. Together, the studies and training proposed within this application will provide the applicant with the skills and experience to run an independent research program.