REFErence Repository for healthy livers

The current estimated global prevalence of non-alcoholic fatty liver disease
(NAFLD) is 25 - 30% and
is diagnosed in up to 80% of individuals with obesity and type 2 diabetes (T2D)
1,2. The rapidly growing
prevalence of NAFLD and lack of effective treatment options to tackle this
potentially debilitating
disease, will further increase obesity-related burden on public health and
economies.
In order to develop appropriate, non-invasive diagnostic methods and treatment
options, it is critical to
deeply investigate the complex pathophysiology of NAFLD. Genome-wide analysis
of large cohorts
(containing hundreds of patients to insure the robustness of results), is
required to obtain insight in
hepatic metabolism in NAFLD. A number of such genome-wide transcriptomic
studies have indeed
characterized alterations in hepatic gene expression in individuals with NAFLD
and its more severe,
progressive form non-alcoholic steatohepatitis (NASH). Nevertheless, these
studies have thus far
not been able to define a predictive transcriptome signature for NAFLD.
Multiple confounding factors
such as differences in genetic origin, sex and unappreciated environmental
factors, including the gut
microbiota, might have contributed to this.
Our unpublished liver and adipose tissue transcriptomics, fecal metagenomics
and plasma metabolomics
data show striking differences in gene expression and metabolite profiles in
female vs male NAFLD
patients (BARIA study METC 2015_357). This implies that there are strong sex
differences in
hepatocellular and systemic processes in the pathophysiology of this disease.
In addition, this
emphasizes the uprising awareness in the field to develop tailored (men vs
women) treatment and
prevention regimes for NAFLD.
Our transcriptomics, fecal metagenomics and metabolomics data were derived from
obese NAFLD
patients. Because all participants were (morbidly) obese, and hence
metabolically challenged, it is
difficult to interpret if the strong transcriptomic/metabolic sex differences
are driven by a male- or
female-specific metabolic response to obesity or whether it is a *true* sex
difference. Obtaining liver
transcriptomic, fecal metagenomic and plasma metabolic data from non-obese,
otherwise healthy
individuals will be critical to 1) better understand the basis of NAFLD
development and 2) develop
tailored (men vs women) preventive or treatment strategies for this disease.
Our research question therefore is how omics data of several biological layers
are different between men
and women with and without NAFLD and to what extent these signatures contribute
to NAFLD
development.
To answer this question, we will establish liver transcriptomic, fecal
metagenomic and plasma
metabolomics profiles of otherwise healthy men and women. Therefore, we will
set up a cross-sectional
cohort and include non-obese, otherwise healthy individuals scheduled for
cholecystectomy. Using
state-of-the-art sequencing and systems biology approaches, we can integrate
plasma/urinary
metabolomics, liver and adipose transcriptomic and fecal metagenomics data to
create a unique much
needed signature of healthy individuals (men and women). This database will be
integrated in our large
cohort of obese men and women with and without NAFLD (BARIA study METC
2015_357).

To determine differences in omics data sets of several biological layers
between men and women with
and without NAFLD and investigate to what extent these signatures contribute to
NAFLD development.
Therefore, we will establish a reference repository of healthy liver biopsies
to establish an integrative
signature of healthy and diseased (NAFLD) liver metabolism in men and women.

Cross-sectional cohort study.

Participants scheduled for laparoscopic cholecystectomy will be recruited from
the outpatient clinics of Surgery and Internal Medicine at Spaarne Gasthuis
hospital. After provision of informed consent, biological samples (blood, urine
and feces) will be collected on the day of surgery and will be asked to fill in
a psychological questionnaire. During cholecystectomy, a liver and mesenteric,
omental and subcutaneous adipose tissue biopsy will be obtained. The risk of
bleeding from the biopsy sites during the surgery procedure is very low because
the biopsy sites are completely visible to the surgeon and local haemostasis
will be checked. Moreover, bleeding disorders are an exclusion criterion. Total
amount of blood taken is 40 ml (once for screening 20 ml and once on day of
surgery 20 ml). This study will function as a much-needed reference database
for all ongoing human trials investigating human liver disease including NAFLD.
We therefore believe that the scientific insight of our findings will outweigh
the minimal risks for the participating individuals in this study.