The effects of metformin on immune function.

Metformin is the most widely administered type 2 diabetes mellitus drug (T2DM).
It reduces plasma glucose levels by decreasing hepatic gluconeogenesis and
increasing muscular intake of glucose. Metformin has a well established safety
record with few adverse effects and decades of research that have elucidated
its cellular effects on glycaemic control and glucose metabolism. Nevertheless
metformin*s effects on the immune system are largely unknown. To date only one
study has shown that short term exposure of peritoneal macrophages and bone
marrow derived DCs to metformin result in reduced MHC antigen presentation
capacity.

Nonetheless recent data emerging from epidemiological studies show that
patients with diabetes have a 3 fold increased risk to MTB. Our in-vitro data
indicate that metformin may negatively affect We therefore wondered if the
intake of metformin had a significant effect on the immune responses of healthy
individuals to ex-vivo stimulations that include MTB.

The primary objective of the study is to evaluate the effects of orally
administered metformin on the immune and metabolic responses of stimulated
peripheral blood mononuclear cells (PBMC*s) and macrophages from healthy
individuals.

Healthy volunteers who meet all inclusion criteria, none of the exclusion
criteria, pass the screening and have given informed consent to participate in
the study will be included in this trial. The subjects will take metformin
based on the following regime for a total of 6 days.

Day 1: 1 x 500 mg (dinner)
Day 2: 1 x 500 mg (breakfast) & 1 x 500 mg (dinner)
Day 3: 1 x 500 mg (breakfast) & 1 x 500 mg (dinner)
Day 4: 1 x 500 mg (breakfast) & 2 x 500 mg (dinner) & phonecall
Day 5: 2 x 500 mg (breakfast) & 2 x 500 mg (dinner)
Day 6: 2 x 500 mg (breakfast)


On the day of screening, day -1, 0, day 5, day 8 and day 19 of the trial,
subjects will be asked to come to the research room of the internal medicine
department for blood sampling (see 3. Study design, p.11 for flowchart).
During screening we will determine BMI, kidney function (creatinine levels),
HBA1c, insulin, glucose, uric acid levels and lipid profiles to exclude persons
with kidney dysfunction and/or metabolic disorders like diabetes mellitus type
2, familial hypercholesterolemia, gout etc.
On days -1 and 0 we would like to determine (1) basal level of cytokine
production of PBMCs and macrophages in response to various stimuli. After 1
day, 3 days and 14 days of metformin ingestion we will perform the same
experiments to determine the effects of metformin on these measurements. The 3
day and 14 day timepoints will assess the long term immunological effects of
metformin.

There is no direct benefit to the participating subjects but it is expected
that these results will potentially lead to a better understanding of the
long-term effects of an extensively used drug. The risk of adverse effects is
minimized by choosing a healthy study population at the age of 18 - 45 years.
12 healthy volunteers will take the aforementioned (see Intervention) regimen
for a duration of 6 days in total. All volunteers will donate 8 tubes of blood
at 4 different time points and 10 mL of blood during screening. The risk
involving local hematoma formation at the site of the blood drawing will be
minimized through blood collection by experienced persons. The risk of lactic
acidosis is minimal (3 cases per 100,000 patient-year); moreover a recent study
published in the Cochrane Database, investigated data from 247 recent clinical
studies and found no cases of lactic acidosis among participants who were
assigned to take metformin1.