Obesity affects over 2 billion people worldwide and is accompanied by peripheral neuropathy (PN) and an associated poorer quality of life. Despite high prevalence, the molecular mechanisms underlying the painful manifestations of PN are poorly understood, and therapies are restricted to use of painkillers or other drugs that do not address the underlying disease. Studies have demonstrated that the gut microbiome is linked to metabolic health and its alteration is associated with many diseases, including obesity. Pathologic changes to the gut microbiome have recently been linked to somatosensory pain, but any relationships between gut microbiome and PN in obesity have yet to be explored. Our data show that mice fed a Western diet developed indices of PN that were attenuated by concurrent fecal microbiome transplantation (FMT). In addition, we observed changes in expression of genes involved in lipid metabolism and calcium handling in cells of the peripheral nerve system (PNS). FMT also induced changes in the immune cell populations of the PNS. There was a correlation between an increase in the circulating short-chain fatty acid butyrate and pain improvement following FMT. Additionally, butyrate modulated gene expression and immune cells in the PNS. Circulating butyrate was also negatively correlated with distal pain in 29 participants with varied body mass index. Our data suggest that the metabolite butyrate, secreted by the gut microbiome, underlies some of the effects of FMT. Targeting the gut microbiome, butyrate, and its consequences may represent novel viable approaches to prevent or relieve obesity-associated neuropathies.

Gram-positive bacteria process and release small peptides, or pheromones, that act as signals for the induction of adaptive traits, including those involved in pathogenesis. One class of small signaling pheromones is the cyclic autoinducing peptides (AIPs), which regulate expression of genes that orchestrate virulence and persistence in a range of microbes, including staphylococci, listeriae, clostridia, and enterococci. In a genetic screen for Staphylococcus aureus secreted virulence factors, we identified an S. aureus mutant containing an insertion in the gene SAUSA300_1984 (mroQ), which encodes a putative membrane-embedded metalloprotease. A ΔmroQ mutant exhibited impaired induction of Toll-like receptor 2-dependent inflammatory responses from macrophages but elicited greater production of the inflammatory cytokine interleukin-1␤ and was attenuated in a murine skin and soft tissue infection model. The ΔmroQ mutant phenocopies an S. aureus mutant containing a deletion of the accessory gene regulatory system (Agr), wherein both strains have significantly reduced production of secreted toxins and virulence factors but increased surface protein A abundance. The Agr system controls virulence factor gene expression in S. aureus by sensing the accumulation of AIP via the histidine kinase AgrC and the response regulator AgrA. We provide evidence to suggest that MroQ acts within the Agr pathway to facilitate the optimal processing or export of AIP for signal amplification through AgrC/A and induction of virulence factor gene expression. Mutation of MroQ active-site residues significantly reduces AIP signaling and attenuates virulence. Altogether, this work identifies a new component of the Agr quorum-sensing circuit that is critical for the production of S. aureus virulence factors.

26Gram-positive bacteria process and release small peptides or "pheromones" that act as signals 27 for the induction of adaptive traits including those involved in pathogenesis. One class of small 28 signaling pheromones is the cyclic auto-inducing peptides (AIPs), which regulate expression of 29 genes that orchestrate virulence and persistence in a range of microbes including 30Staphylococci, Listeria, Clostridia, and Enterococci. In a genetic screen for Staphylococcus 31 aureus secreted virulence factors, we identified a S. aureus mutant containing an insertion in 32 gene SAUSA300_1984 (mroQ), which encodes a putative membrane-embedded 33 metalloprotease. A ΔmroQ mutant exhibits impaired induction of TLR2-dependent 34 inflammatory responses from macrophages, but elicits greater production of the inflammatory 35 cytokine IL-1β and is attenuated in a murine skin and soft tissue infection model. The ΔmroQ 36 mutant phenocopies a S. aureus mutant containing a deletion of the accessory gene regulatory 37 system (Agr), wherein both strains have significantly reduced production of secreted toxins and 38 virulence factors, but increased surface Protein A abundance. The Agr system controls 39 virulence factor gene expression in S. aureus through sensing accumulation of AIP via the 40 histidine kinase AgrC and response regulator AgrA. We provide evidence to suggest that MroQ 41 acts within the Agr pathway to facilitate optimal processing or export of AIP for signal 42 amplification through AgrC/A and induction of virulence factor gene expression. Mutation of 43MroQ active site residues significantly reduces AIP signaling and attenuates virulence. 44Altogether, this work identifies a new component of the Agr quorum sensing circuit that is 45 critical for the production of S. aureus virulence factors. 46 47 48 from the bacterial cell. While many signaling molecules of Gram-negative bacteria are freely 56 diffusible, the peptides of Gram-positives generally must transit the membrane via a dedicated 57 transporter (4, 5). After processing and transport, the peptide is either imported back into the 58 bacterial cell or transmits signal from the extracellular environment by binding to membrane-59 embedded sensor histidine kinases (6). Peptide signaling culminates in a change in gene 60 expression mediated by transcription factors that respond to the peptide. Many Gram-positive 61 bacterial pathogens use these "quorum-sensing" peptides to induce gene expression programs 62 that promote virulence adaptations such as competence, toxin production, biofilm formation, 63 and establishment of persistence traits. Because of its importance in activating virulence 64 programs in S. aureus, quorum-sensing inhibition has been the focus of many therapeutic 65 initiatives (7)(8)(9)(10)(11)(12)(13)(14). 66The ability of S. aureus to infect host tissues and cause acute and chronic disease is 67 partially due to its use of complex gene regulatory systems that control virulence factor gene 68 expression (15-17). S. aureus employs 16 two-compone...

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<b><i>Introduction:</i></b> Mitochondria are essential organelles required for several cellular processes ranging from ATP production to cell maintenance. To provide energy, mitochondria are transported to specific cellular areas in need. Mitochondria also need to be recycled. These mechanisms rely heavily on trafficking events. While mechanisms are still unclear, hypothalamic mitochondria are linked to obesity. <b><i>Methods:</i></b> We used C2 domain protein 5 (C2CD5, also called C2 domain-containing phosphoprotein [CDP138]) whole-body KO mice primary neuronal cultures and cell lines to perform electron microscopy, live cellular imaging, and oxygen consumption assay to better characterize mitochondrial alteration linked to C2CD5. <b><i>Results:</i></b> This study identified that C2CD5 is necessary for proper mitochondrial trafficking, structure, and function in the hypothalamic neurons. We previously reported that mice lacking C2CD5 were obese and displayed reduced functional G-coupled receptor, melanocortin receptor 4 (MC4R) at the surface of hypothalamic neurons. Our data suggest that in neurons, normal MC4R endocytosis/trafficking necessities functional mitochondria. <b><i>Discussion:</i></b> Our data show that C2CD5 is a new protein necessary for normal mitochondrial function in the hypothalamus. Its loss alters mitochondrial ultrastructure, localization, and activity within the hypothalamic neurons. C2CD5 may represent a new protein linking hypothalamic dysfunction, mitochondria, and obesity.