Project Summary/Abstract Our preliminary data, as well as our previous published studies, show that ME/CFS cases have alterations in gastrointestinal mucosal immunity and mitochondrial homeostasis. Several other studies have described significant alterations in the composition of the gut microbiome in ME/CFS cases, when compared to age and gender-matched controls, potentially implicating a pathological role for a dysbiotic microbiota in the progression of ME/CFS through the gut-microbiota-brain axis. We hypothesize that by conducting a fecal microbiota transplantation (FMT) with stool from ME/CFS cases into mice that are engrafted with a functional human immune system, we can develop an animal model that will replicate ME/CFS-associated pathology. We further hypothesize that this model can be used to conduct ME/CFS research that is not practical or possible when working with human subjects. In Specific Aim 1, we will characterize and transplant stool from ME/CFS cases and healthy controls into common C57BL/6J laboratory mice, which have a normal murine immune system, as well as mice that are engrafted with a functional human immune system. We will then evaluate these mice for exercise intolerance, neurocognitive dysfunction, and sleep disturbances; behavioral alterations consistent with those observed in human cases. In Aim 2, we will pathologically evaluate these mice to identify changes in the gut and the brain that potentially implicate the altered microbiota in ME/CFS pathophysiology. These studies will lay the foundation for a larger research focus to identify ways to target the gut-microbiota brain axis in the prevention and treatment of ME/CFS. ME/CFS is a multisystemic, debilitating, and neglected illness for which no accepted efficacious treatments are currently available. Population-based epidemiologic studies suggest that ME/CFS may affect as many as 2.5 million people in the United States alone. Moreover, ME/CFS produces an annual economic burden of at least $17 billion 4. Although ME/CFS represents a serious public health concern, after almost four decades of research, the pathophysiology of this illness is still largely unknown.

Project Narrative Several lines of evidence suggest that a gut-microbiota-brain axis connection is involved in the pathophysiology of ME/CFS. Mice that received fecal transplants from human donors with other neuroimmune diseases present with behavioral alterations consistent with these diseases, suggesting that fecal transplants may be used to create humanized mouse models of ME/CFS. Therefore, we propose to develop humanized mouse models of ME/CFS by using stool from ME/CFS subjects and healthy controls. Fecal transplants will be made using C57BL/6J mice and Hu-CD34+ NSG-SGM3 transgenic mice engrafted with a human immune system. We will then evaluate these mice for behavioral alterations and mucosal and neuroimmune alterations consistent with ME/CFS.