Microphysiological systems to recapitulate and interrogate Sjögren’s disease salivary gland pathogenesis - PROJECT SUMMARY Sjögren’s disease (SjD), a systemic autoimmune disease that affects four million people in the United States and impairs health-related quality of life, has no FDA approved disease modifying treatments available. SjD is highly heterogeneous and has multiple endotypes or pathobiologically similar subgroups. The standard for studying complex cell interactions and organ systems in SjD is mouse model work. Unfortunately mice fail to fully encapsulate all features of SjD and also are homogeneous. Thus, a system is needed that can recapitulate both the complex interactions in vivo but also the heterogeneity of SjD. Our long-term goal is to leverage microphysiological systems (MPSs) to test SjD therapeutics. The goal of this project is to capture the functional effects of a fibrotic microenvironment in SjD progression. The hypothesis of this project is that MPSs incorporating collagen density and fibroblasts will more faithfully reproduce in vivo epithelial cell and lymphocyte phenotype and transcriptome, ensuring our MPS is more physiologically relevant for future therapeutic testing. The rationale for this hypothesis is based on the fact that in mice, fibroblasts are necessary for germinal center formation in salivary glands and that fibroblasts under inflammatory conditions promote CXCR3+ CD4+ T-cell chemotaxis. Furthermore, SjD patients have more fibrosis of salivary glands than non-SjD patients, independent of age. In other diseases, fibrosis and collagen density affect lymphocyte chemotaxis. Yet, the effects of collagen density and fibroblasts remain unclear in SjD. The central hypothesis will be tested by pursuing two specific aims. Aim 1 will interrogate collagen density effects on SG-organoids and lymphocyte extravasation and chemotaxis. MPSs will be generated with various collagen densities. Lymphocyte chemotaxis to salivary gland organoids will be evaluated with and without the presence of fibroblasts. Aim 2 will compare MPSs to in vivo SjD models, using pharmacologic probes. We will contrast the effect of JAK inhibitors on lymphocyte chemotaxis as well as on peripheral blood mononuclear cells, fibroblast, and organoid cell signatures in our MPS as well as in a relevant mouse model. This project builds an interdisciplinary team with unique expertise in SjD and salivary gland biology, MPS experts, and experts in seqFISH and hybridization chain reaction. The proposed application is innovative because it uses cutting edge MPSs and approaches to measure spatial genomics and proteomics of the MPSs. It also defines the effect of collagen density on the local immune environment. This research is significant because it will improve novel therapeutics screening and selection, leveraging a complex system that recapitulates SjD. Furthermore, this MPS is capable of recreating specific SjD endotypes to tailor research to SjD heterogeneity.
