Divergent Genetic Regulation of Nitric Oxide Production between C57BL/6J and Wild-Derived PWD/PhJ Mice Controls Postactivation Mitochondrial Metabolism, Cell Survival, and Bacterial Resistance in Dendritic Cells.

Dendritic cell (DC) activation is characterized by sustained commitment to glycolysis that is a requirement for survival in DC subsets that express inducible NO synthase (Nos2) due to NO-mediated inhibition of mitochondrial respiration. This phenomenon primarily has been studied in DCs from the classic laboratory inbred mouse strain C57BL/6J (B6) mice, where DCs experience a loss of mitochondrial function due to NO accumulation. To assess the conservation of NO-driven metabolic regulation in DCs, we compared B6 mice to the wild-derived genetically divergent PWD/PhJ (PWD) strain. We show preserved mitochondrial respiration and enhanced postactivation survival due to attenuated NO production in LPS-stimulated PWD DCs phenocopying human monocyte-derived DCs. To genetically map this phenotype, we used a congenic mouse strain (B6.PWD-Chr11.2) that carries a PWD-derived portion of chromosome 11, including Nos2, on a B6 background. B6.PWD-Chr11.2 DCs show preserved mitochondrial function and produce lower NO levels than B6 DCs. We demonstrate that activated B6.PWD-Chr11.2 DCs maintain mitochondrial respiration and TCA cycle carbon flux, compared with B6 DCs. However, reduced NO production by the PWD Nos2 allele results in impaired cellular control of Listeria monocytogenes replication. These studies establish a natural genetic model for restrained endogenous NO production to investigate the contribution of NO in regulating the interplay between DC metabolism and immune function. These findings suggest that reported differences between human and murine DCs may be an artifact of the limited genetic diversity of the mouse models used, underscoring the need for mouse genetic diversity in immunology research.

Daily, oral FMT for long-term maintenance therapy in ulcerative colitis: results of a single-center, prospective, randomized pilot study.

BACKGROUND: Fecal microbiota transplantation (FMT) is a promising new strategy in the treatment of Inflammatory Bowel Disease, but long-term delivery systems are lacking. This randomized study was designed as a safety and feasibility study of long-term FMT in subjects with mild to moderate UC using frozen, encapsulated oral FMT (cFMT). METHODS: Subjects were randomized 1:1 to receive FMT induction by colonoscopy, followed by 12 weeks of daily oral administration of frozen encapsulated cFMT or sham therpay. Subjects were followed for 36 weeks and longitudenal clinical assessments included multiple subjective and objective markers of disease severity. Ribosomal 16S bacterial sequencing was used to assess donor-induced changes in the gut microbiota. Changes in T regulatory (Treg) and mucosal associated invariant T (MAIT) cell populations were evaluated by flow cytometry as an exploratory endpoint. RESULTS: Twelve subjects with active UC were randomized: 6 subjects completed the full 12-week course of FMT plus cFMT, and 6 subjects received sham treatment by colonic installation and longitudinal oral placebo capules. Chronic administration of cFMT was found to be safe and well-tolerated but home storage concerns exist. Protocol adherence was high, and none of the study subjects experienced FMT-associated treatment emergent adverse events. Two subjects that received cFMT achieved clinical remission versus none in the placebo group (95% CI = 0.38-infinity, p = 0.45). cFMT was associated with sustained donor-induced shifts in fecal microbial composition. Changes in MAIT cell cytokine production were observed in cFMT recipients and correlated with treatment response. CONCLUSION: These pilot data suggest that daily encapsulated cFMT may extend the durability of index FMT-induced changes in gut bacterial community structure and that an association between MAIT cell cytokine production and clinical response to FMT may exist in UC populations. Oral frozen encapsulated cFMT is a promising FMT delivery system and may be preferred for longterm treatment strategies in UC and other chronic diseases but further evaluations will have to address home storage concerns. Larger trials should be done to explore the benefits of cFMT and to determine its long-term impacts on the colonic microbiome. TRIAL REGISTRATION: ClinicalTrials.gov (NCT02390726). Registered 17 March 2015, https://clinicaltrials.gov/ct2/show/NCT02390726?term=NCT02390726&draw=2&rank=1 .