Examining interactions between Pseudomonas aeruginosa and Staphylococcus aureus from cystic fibrosis lung infections

Pseudomonas aeruginosa and Staphylococcus aureus are two common cystic fibrosis (CF) pathogens, thought to interact within the lung and influence disease progression. This study on interspecies interactions revealed that P. aeruginosa mediates antagonistic interactions with S. aureus. Further analysis was completed to identify the mechanism of negative interactions between an S. aureus CF isolate, C105, and twenty seven P. aeruginosa CF isolates – nine of which were identified as inhibitors. It was demonstrated that an inhibitory factor is secreted by P. aeruginosa; is less than 5 kDa, can induce tobramycin resistance in C105 and reduce hemolytic activity suggesting the formation of small colony variants (SCVs). GC-MS analysis revealed that the primary inhibitory factor was not 4-hydroxy-2n-heptlyquinolone-N-oxide (HQNO) rather inhibition of S. aureus by P. aeruginosa is complex and involves the secretion of multiple factors. This research suggests that P. aeruginosa produces multiple anti-staphylococcal agents that play a paradoxical role as they inhibit growth yet allow for aminoglycoside resistance in S. aureus

The emerging roles of bacterial proteases in intestinal diseases

ABSTRACTProteases are an evolutionarily conserved family of enzymes that degrade peptide bonds and have been implicated in several common gastrointestinal (GI) diseases. Although luminal proteolytic activity is important for maintenance of homeostasis and health, the current review describes recent advances in our understanding of how overactivity of luminal proteases contributes to the pathophysiology of celiac disease, irritable bowel syndrome, inflammatory bowel disease and GI infections. Luminal proteases, many of which are produced by the microbiota, can modulate the immunogenicity of dietary antigens, reduce mucosal barrier function and activate pro-inflammatory and pro-nociceptive host signaling. Increased proteolytic activity has been ascribed to both increases in protease production and decreases in inhibitors of luminal proteases. With the identification of strains of bacteria that are important sources of proteases and their inhibitors, the stage is set to develop drug or microbial therapies to restore protease balance and alleviate disease

Finding the silver lining during a global pandemic: opportunities for curriculum innovation in microbiology education

N/AThe accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author

Keeping the microbiology lab alive: essential microbiology lab skill development in the wake of COVID-19

NAThe accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author

Crohn’s disease proteolytic microbiota enhances inflammation through PAR2 pathway in gnotobiotic mice

ABSTRACTEmerging evidence implicates microbial proteolytic activity in ulcerative colitis (UC), but whether it also plays a role in Crohn’s disease (CD) remains unclear. We investigated the effects of colonizing adult and neonatal germ-free C57BL/6 mice with CD microbiota, selected based on high (CD-HPA) or low fecal proteolytic activity (CD-LPA), or microbiota from healthy controls with LPA (HC-LPA) or HPA (HC-HPA). We then investigated colitogenic mechanisms in gnotobiotic C57BL/6, and in mice with impaired Nucleotide-binding Oligomerization Domain-2 (NOD2) and Protease-Activated Receptor 2 (PAR2) cleavage resistant mice (Nod2−/−; R38E-PAR2 respectively). At sacrifice, total fecal proteolytic, elastolytic, and mucolytic activity were analyzed. Microbial community and predicted function were assessed by 16S rRNA gene sequencing and PICRUSt2. Immune function and colonic injury were investigated by inflammatory gene expression (NanoString) and histology. Colonization with HC-LPA or CD-LPA lowered baseline fecal proteolytic activity in germ-free mice, which was paralleled by lower acute inflammatory cell infiltrate. CD-HPA further increased proteolytic activity compared with germ-free mice. CD-HPA mice had lower alpha diversity, distinct microbial profiles and higher fecal proteolytic activity compared with CD-LPA. C57BL/6 and Nod2−/− mice, but not R38E-PAR2, colonized with CD-HPA had higher colitis severity than those colonized with CD-LPA. Our results indicate that CD proteolytic microbiota is proinflammatory, increasing colitis severity through a PAR2 pathway

Biogeographic Variation and Functional Pathways of the Gut Microbiota in Celiac Disease

Background & Aims: Genes and gluten are necessary but insufficient to cause celiac disease (CeD). Altered gut microbiota has been implicated as an additional risk factor. Variability in sampling site may confound interpretation and mechanistic insight, as CeD primarily affects the small intestine. Thus, we characterized CeD microbiota along the duodenum and in feces and verified functional impact in gnotobiotic mice. Methods: We used 16S rRNA gene sequencing (Illumina) and predicted gene function (PICRUSt2) in duodenal biopsies (D1, D2 and D3), aspirates, and stool from patients with active CeD and controls. CeD alleles were determined in consented participants. A subset of duodenal samples stratified according to similar CeD risk genotypes (controls DQ2–/– or DQ2+/– and CeD DQ2+/–) were used for further analysis and to colonize germ-free mice for gluten metabolism studies. Results: Microbiota composition and predicted function in CeD was largely determined by intestinal location. In the duodenum, but not stool, there was higher abundance of Escherichia coli (D1), Prevotella salivae (D2), and Neisseria (D3) in CeD vs controls. Predicted bacterial protease and peptidase genes were altered in CeD and impaired gluten degradation was detected only in mice colonized with CeD microbiota. Conclusions: Our results showed luminal and mucosal microbial niches along the gut in CeD. We identified novel microbial proteolytic pathways involved in gluten detoxification that are impaired in CeD but not in controls carrying DQ2, suggesting an association with active duodenal inflammation. Sampling site should be considered a confounding factor in microbiome studies in CeD.Fil: Constante, Marco. Mc Master University; CanadáFil: Libertucci, Josie. Mc Master University; CanadáFil: Galipeau, Heather J.. Mc Master University; CanadáFil: Szamosi, Jake C.. Mc Master University; CanadáFil: Rueda, Gaston. Mc Master University; CanadáFil: Miranda, Pedro M.. Mc Master University; CanadáFil: Pinto Sanchez, Maria Ines. Mc Master University; CanadáFil: Southward, Carolyn M.. Mc Master University; CanadáFil: Rossi, Laura. Mc Master University; CanadáFil: Fontes, Michelle E.. Mc Master University; CanadáFil: Chirdo, Fernando Gabriel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Estudios Inmunológicos y Fisiopatológicos. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Estudios Inmunológicos y Fisiopatológicos; ArgentinaFil: Surette, Michael G.. Mc Master University; CanadáFil: Bercik, Premysl. Mc Master University; CanadáFil: Caminero, Alberto. Mc Master University; CanadáFil: Verdu, Elena F.. Mc Master University; Canad