Summary: Resource Core 2: Mucosal Immunobiology Core (MIC) Compounding evidence exists for the role of microbiota and mucosal immunology in the pathogenesis of rheumatic diseases including rheumatoid arthritis (RA) and spondyloarthritis (SpA). The Mucosal Immunobiology Core (MIC) aims to provide consultation, discounted services, and development of enhanced capabilities to support the prediction and validation of mechanisms of host:microbe interactions in biospecimens of importance to rheumatic disease pathogenesis. The MIC will facilitate collaboration between individuals with expertise in microbiome, metabolome/lipidome, immunology, statistical data analysis, and rheumatic disease, which is essential for conducting this multidisciplinary research. Taken together, this core will support research into host:microbe interactions through 1) assembling individuals with diverse and complimentary expertise for promoting team science approaches focused on mucosal phenotypes and systemic consequences; 2) educating young investigators and those new to the field; 3) providing discounted services; and 4) novel methods development. More specifically, the MIC will support discounted services for the characterization of the microbiome and metabolome of biospecimens and tissues of importance in rheumatic disease pathogenesis, including feces, sputum, oral cavity, lower respiratory tract, intestinal mucosa, and cervicovaginal mucosa. Since challenges in data analysis can often be a bottleneck in conducting productive research in mucosal immunobiology, the MIC will also support free and discounted services and training in integrated ‘omic data analysis. The MIC will also support experimental validation of microbe:metabolite:immune phenotype relationships via in vitro cell stimulations, by providing services, consultation, and support in the expansion of anaerobic and aerobic bacteria and flow cytometry and density gradient based isolation of bacteria, and isolation of immune cells of interest. The MIC will develop enhanced capabilities in use of RNASeq to characterize both host and microbial gene expression simultaneously in intestinal tissue and associated multi’omic integrated data analyses. The MIC will also develop enhanced capabilities in annotation of metabolomic data through the creation of tissue specific databases for annotation of untargeted LC/MS data from feces and sputum samples. Finally, the MIC will invest in developing novel methods for isolating cell populations of interest for use in in vitro interrogations of host:microbe interactions. By integrating individuals with diverse expertise and providing discounted services, training and support, the MIC will support both early career and established investigators in the University of Colorado (CU) Rheumatic Disease Research Resource Center (RDRRC), as well as assist investigators new to the field of rheumatic disease to enhance overall research implementation and productivity.