BMC Medicine at Digestive Disease Week 2019

BMC Medicine attended DDW 2019, one of the largest worldwide gatherings for gastroenterologists and hepatologists. Here we share some of the highlights presented during the sessions.

Alessandro Recchioni

Gut microbiota and the brain

In a Saturday morning session, Premysl Bercik from McMaster university highlighted the interplay between the intestinal microbiota and the brain, with data coming primarily from mouse studies.

According to Dr Bercik, there is currently a gap in translational studies between animal results and clinical applicability.

Following a widely cited 2011 PNAS study, Dr Bercik indicated that bacterial colonization alters mouse behavior and expression of multiple genes in the brain, and that mice who grow up in sterile environments show differences in the blood-brain-barrier and in other areas of their brains, compared to mice exposed to a normal microbial environment.

Although the interplay between the gut microbiota and the brain has been discussed in the past, clinical studies are more difficult to perform and human results are eagerly awaited.

Although the interplay between the gut microbiota and the brain has been discussed in the past, clinical studies are more difficult to perform and human results are eagerly awaited.

The take home messages of his talk were that microbiota colonization alters behaviour, brain structure, and chemistry of germ-free mice.

In a related talk, Dr Timothy Dinan from the University of Cork explained that the mouse brain doesn’t develop normally without gut bacteria, and transplanting bacteria from depressed to normal rats causes radical alterations in the recipients’ behavior, where animals start to show symptoms of depression, such as anhedonia.

We look forward to further studies that can elucidate the details of the gut-brain-axis in stress response.

Physical activity and liver mortality

Tracey Simon from Massachusetts General Hospital presented a session on physical activity and liver-related mortality. In her talk, she argued that exercise can improve the histology in patients with liver disease, even in absence of significant weight loss, however long term data is lacking.

In their study, data from two prospective US cohorts was included, where all subjects provided clinical and lifestyle data every two years. Patients with baseline cirrhosis or viral hepatitis were excluded.

Compared to sedentary adults, those in the highest physical activity quintile had 51% lower risk of liver-related mortality. In particular the authors found that walking at least four hours a week, ideally complemented by exercise, would be enough to decrease risk of liver-related mortality.

While Dr Simon noted that exercise and cirrhosis status was self-selected by the patients, and the cohorts included a majority of Caucasians, further research should be performed to define the type and intensity of optimal exercise to provide a meaningful reduction in the risk of death.

Celiac disease and mouse models

Manuel Encalada from the University of Mainz presented a study regarding further development of a novel in vivo model for celiac disease (CD) in mice, with humanized immune system. Currently, celiac disease is largely treated via a lifelong gluten-free diet, which can cause a number of difficulties for the patient.

As of yet, further models for celiac disease are needed, to better understand its pathophysiology and improve treatment options. The authors developed a humanized model for CD, which is useful in translational studies.

Mice that were fed with high gluten diet showed significant weight loss, and in addition, the researchers studied the expression of a number of biomarkers such as Interferon-gamma and Interleukin 1 beta.

According to the presenter, they provide a first approach to a CD mouse model, with a thoroughly humanized immune system. This study will be followed up by experiments looking at TG2 antibodies, and prolonged maintenance of human engraftment.

We look forward to future studies that may shed more light on the details of celiac disease.

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