July 21, 2020

Monday's Recap - Comparative Gut Physiology Symposium

Comparative Gut Physiology Symposium

By Lauren Soranno

            On Monday, July 20th, the Comparative Gut Physiology Symposium at the ASAS-CSAS-WSASAS Virtual Annual Meeting and Trade Show highlighted the importance of understanding various gut microbiome-organ axes which have an important role in host physiology, immunity, and metabolism. Dr. Ahemd Elolimy, a postdoctoral fellow at the University of Arkansas, was presented with the Agri-King Outstanding Animal Science Graduate Student Award. Congratulations, Dr. Elolimy! Dr. Elolimy then began the presentations by discussing his research on the gut microbiome in beef and dairy cattle. With the use of residual feed intake as a measurement of an animal’s feed efficiency, Dr. Elolimy compared the most-efficient and the least-efficient finishing beef cattle, concluding that the rumen microbiome has a critical role in determining superior feed efficiency. Differences in ruminal bacteria and epithelial genes may enhance energy production and utilization and, therefore, rumen function allowing the most-efficient cattle to maintain a growth performance similar to the least-efficient cattle while consuming less DMI. Dr. Elolimy also analyzed how maternal nutrition, specifically methionine supplementation, programmed the hindgut microbiome in neonatal calves, contributing to better nutrient utilization to support greater growth rates.

            Dr. Dylan Dodd, an assistant professor at Stanford University, continued the presentations by further discussing the importance of microbiota-host interactions. He stressed that gut microbial metabolism yields hundreds of unique chemicals and these microbiota-derived metabolites vary dramatically across individuals. Dr. Dodd specifically discussed IPA which is produced by specific gut bacteria from tryptophan. These metabolites increase tight junction genes, helping to increase the mucosal barrier protection. Studying IPA deficient animals compared to wild type modelled how microbiota-derived metabolites impact host physiology. IPA deficient mice had increased intestinal permeability and an activated immune system compared with wild type mice. The next step would to be determine how to modulate these metabolites, such as IPA, to potentially alter host physiology in a favorable way.

            Next, Dr. Michael Surette, a professor at McMaster University, focused on a specific gut microbiome-organ axis: the gut-lung axis. He stressed how these organ systems are associated with each other as chronic respiratory disease is associated with a higher risk of GI disease and vice versa. The microbiome and immune system are key to this association. The microbiome co-evolves with the immune system uniquely in each individual. Perturbations to the gut and respiratory tract microbiome early in life can have long term consequences and potentially affect disease risk, such as asthma, but remains controversial. Investigating the gut-lung axis and the interaction with the immune system is important to potentially determine if intervening later in life to mitigate early life events is possible.

            Dr. Trevor Alexander, a research scientist at the Lethbridge Research and Development Centre, analyzed the gut-lung axis as well, but from a beef perspective. He focused on how respiratory microbiota affects resistance or susceptibility to BRD. Cattle are most susceptible to BRD when they are transported to feedlots due to multiple stressors affecting both the lungs and GI tract. Dr. Alexander discussed the significant changes found in respiratory microbiota of cattle during the first 14 days of placement, but how feed additives, such as yeast, and probiotics that target respiratory health may enhance systemic and lung immunity. More research needs to be conducted to understand the links between the stressors impacting the gut-lung microbiome axis to potentially lead to the development of bacterial therapeutics.

            Finally, the remaining speakers moved on to discuss the gut microbiome-reproductive axis. Dr. Rodrigo Bicalho, an associate professor at Cornell University, concentrated on metritis and endometritis. Various pathogens are linked to these multi factorial diseases and the amount present are influenced by events that happen around parturition, suggesting that environmental contamination is an important factor. The origin of the uterine microbiota is still being researched, but the potential sources are from the environment or an endogenous route via hematogenous transmission from the gut. Dr. Ehsan Khafipour, the director of microbiome research at Diamond V, specifically analyzed the mammary gland within the reproductive axis. Similar to the uterine microbiota, Dr. Khafipour analyzed two different sources for the mammary gland microbiome: maternal microbiota and exogenous microbiota. Further in vitro and in vivo investigations of mammary gland microbiota and the different niches within are needed determine the exact mechanism that links the gut and mammary gland microbiota.

Studying the numerous gut microbiome-organs axes is critical as the production of microbially sourced metabolites can alter the health and physiology of the host. Understanding how they impact the host can potentially lead to new therapeutic approaches that work by controlling these small molecules from the microbiota.