Publications
98 results found
Martz S-LE, McDonald JAK, Sun J, et al., 2015, Administration of defined microbiota is protective in a murine Salmonella infection model., Scientific Reports, Vol: 5, ISSN: 2045-2322
Salmonella typhimurium is a major cause of diarrhea and causes significant morbidity and mortality worldwide, and perturbations of the gut microbiota are known to increase susceptibility to enteric infections. The purpose of this study was to investigate whether a Microbial Ecosystem Therapeutic (MET-1) consisting of 33 bacterial strains, isolated from human stool and previously used to cure patients with recurrent Clostridium difficile infection, could also protect against S. typhimurium disease. C57BL/6 mice were pretreated with streptomycin prior to receiving MET-1 or control, then gavaged with S. typhimurium. Weight loss, serum cytokine levels, and S. typhimurium splenic translocation were measured. NF-κB nuclear staining, neutrophil accumulation, and localization of tight junction proteins (claudin-1, ZO-1) were visualized by immunofluorescence. Infected mice receiving MET-1 lost less weight, had reduced serum cytokines, reduced NF-κB nuclear staining, and decreased neutrophil infiltration in the cecum. MET-1 also preserved cecum tight junction protein expression, and reduced S. typhimurium translocation to the spleen. Notably, MET-1 did not decrease CFUs of Salmonella in the intestine. MET-1 may attenuate systemic infection by preserving tight junctions, thereby inhibiting S. typhimurium from gaining access to the systemic circulation. We conclude that MET-1 may be protective against enteric infections besides C. difficile infection.
Yen S, McDonald JAK, Schroeter K, et al., 2015, Metabolomic Analysis of Human Fecal Microbiota: A Comparison of Feces-Derived Communities and Defined Mixed Communities, JOURNAL OF PROTEOME RESEARCH, Vol: 14, Pages: 1472-1482, ISSN: 1535-3893
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- Citations: 51
McDonald JAK, Fuentes S, Schroeter K, et al., 2015, Simulating distal gut mucosal and luminal communities using packed-column biofilm reactors and an in vitro chemostat model, JOURNAL OF MICROBIOLOGICAL METHODS, Vol: 108, Pages: 36-44, ISSN: 0167-7012
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- Citations: 41
Correa-Betanzo J, Allen-Vercoe E, McDonald J, et al., 2014, Stability and biological activity of wild blueberry (<i>Vaccinium angustifolium</i>) polyphenols during simulated <i>in vitro</i> gastrointestinal digestion, FOOD CHEMISTRY, Vol: 165, Pages: 522-531, ISSN: 0308-8146
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- Citations: 218
Claud EC, McDonald JAK, He S-M, et al., 2014, Differential expression of 26S proteasome subunits and functional activity during neonatal development, Biomolecules, Vol: 4, Pages: 812-826, ISSN: 2218-273X
Proteasomes regulate many essential cellular processes by degrading intracellular proteins. While aging is known to be associated with dysfunction of the proteasome, there are few reports detailing activity and function of proteasomes in the early stages of life. To elucidate the function and development of mammalian proteasomes, 26S proteasomes were affinity-purified from rat intestine, spleen and liver. The developmental expression of core, regulatory and immunoproteasome subunits was analyzed by immunoblotting and reverse-transcriptase PCR of mRNA subunits, and proteasome catalytic function was determined by fluorogenic enzymatic assays. The expression of core (β2, β5, α7 and β1) and regulatory (Rpt5) subunits was found to be present at low levels at birth and increased over time particularly at weaning. In contrast, while gradual developmental progression of proteasome structure was also seen with the immunoproteasome subunits (β1i, β5i, and β2i), these were not present at birth. Our studies demonstrate a developmental pattern to 26S proteasome activity and subunit expression, with low levels of core proteasome components and absence of immunoproteasomes at birth followed by increases at later developmental stages. This correlates with findings from other studies of a developmental hyporesponsiveness of the adaptive immune system to allow establishment of microbial colonization immediately after birth.
Antunes LCM, McDonald JAK, Schroeter K, et al., 2014, Antivirulence activity of the human gut metabolome, mBio, Vol: 5, ISSN: 2150-7511
The mammalian gut contains a complex assembly of commensal microbes termed microbiota. Although much has been learned about the role of these microbes in health, the mechanisms underlying these functions are ill defined. We have recently shown that the mammalian gut contains thousands of small molecules, most of which are currently unidentified. Therefore, we hypothesized that these molecules function as chemical cues used by hosts and microbes during their interactions in health and disease. Thus, a search was initiated to identify molecules produced by the microbiota that are sensed by pathogens. We found that a secreted molecule produced by clostridia acts as a strong repressor of Salmonella virulence, obliterating expression of the Salmonella pathogenicity island 1 as well as host cell invasion. It has been known for decades that the microbiota protects its hosts from invading pathogens, and these data suggest that chemical sensing may be involved in this phenomenon. Further investigations should reveal the exact biological role of this molecule as well as its therapeutic potential.
McDonald JAK, Schroeter K, Fuentes S, et al., 2013, Evaluation of microbial community reproducibility, stability and composition in a human distal gut chemostat model, JOURNAL OF MICROBIOLOGICAL METHODS, Vol: 95, Pages: 167-174, ISSN: 0167-7012
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- Citations: 109
Strauss J, White A, Ambrose C, et al., 2008, Phenotypic and genotypic analyses of clinical <i>Fusobacterium nucleatum</i> and <i>Fusobacterium periodonticum</i> isolates from the human gut, ANAEROBE, Vol: 14, Pages: 301-309, ISSN: 1075-9964
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- Citations: 45
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