Obesity, Bariatric Surgery, Gut Microbiome and Immunity Changes

Individuals with morbid obesity have a shorter life expectancy than individuals
with a healthy weight. Morbid obesity is also linked with changes in the immune
system, which can be reversed after bariatric surgery. Multiple studies have
shown that the accelerated aging process that is found in individuals with
morbid obesity can be a possible explanation for this. The aging process is
investigated by the determinatin of telomeres (protecting ends of DNA). The
shorter the telomeres, the older the individual. Individuals with a short
telomere have a higher risk for the development of cancer. At this moment, the
telomere lengt is determined based on leukocytes. With this study, we want to
determine whether the telomere length in leukocytes is comparable to that in
liver tissue, fat tissue en muscle tissue.

Both obesity and aging are accompanied by changes in the gut microbiome.
Studies to the gut microbiome have shone that morbid obese individuals have a
different gut microbiome than healthy individuals. Most of the studies have
been performed in mice. In our study, we will investigate whether weight loss,
either with or without bariatric surgery, influences the gut microbiome.

To investigate of the accelerated aging process in morbid obese individuals can
be stopped or reversed by bariatric surgery. We also want to investigate
whether the aging process in muscle tissue, liver tissue and fat tissue is
comparable to the aging process in leukocytes. Also, we want to investigate
whether the immunesystem changes after bariatric surgery. We also want to
investigate whether excessive weight loss, either with or without bariatric
surgery, influences the gut microbiome.

The study design of our study is a prospective cohort study.

A possible adverse event is bleeding after liver, muscle or adipose tissue
biopsy. To minimize the possible unfavourable outcome, these biopsies will be
done at the beginning of the procedure. The surgeon will have a clear view of
the location of the biopsy during the complete procedure and will have the
maximal amount of time to anticipate on a bleeding when it occurs.

There will be no extra visits to the outpatient clinic if patients participate
in our study. After 3 months, an extra vena puncture with 4 blood samples of 6
mL will be performed to determine the telomeres in the blood. Also, at 3 other
follow-up moments 4 extra blood samples of 6 mL will be taken next to the
standard blood samples at 6, 12 and 24 months postoperative.

Patients will be asked to fill out 2 questionnaires at five follow-up points
which will each take 10 minutes extra time.