The goal of this pilot intervention trial is to investigate the biological effects of daily supplementation with different doses of indole-3-propionic acid (IPA) in healthy adults. The main scientific questions are: * Does supplementation with IPA increase the abundance regulatory T cells in the blood? Regulatory T cells are believed to play an important role in preventing autoimmune diseases. * Does supplementation with IPA increase the concentration of brain-derived neurotrophic factor (BDNF) in the blood? BDNF is believed to play an important role in maintaining brain health. * Does supplementation with IPA affect blood analyses commonly performed to assess the risk of metabolic disorders like type 2 diabetes and cardiovascular diseases? * How big a dose of IPA is necessary to achieve the above benefits? Participants will: * Take 50 mg IPA or 120 mg IPA or 500 mg IPA or placebo every morning for 14 days. * Visit the clinic at the beginning (day 1) and at the end (day 15) of IPA supplementation to deliver blood, urine and fecal samples, have simple measurements performed, fulfil questionnaires and report any side effects.
Indole-3-propionic acid (IPA) is a gut bacterial metabolite with the amino acid tryptophan as substrate. In vitro and animal studies, suggest that IPA could contribute to regulating inflammation and metabolic function, preventing oxidative damage and upregulating expression of brain-derived neurotrophic factor. With this study we aim to investigate the biochemical effects of IPA at supraphysiological levels in humans.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
BASIC_SCIENCE
Masking
QUADRUPLE
Enrollment
79
A dosis of either 50 mg IPA, 120 mg IPA or 500 mg IPA (two capsules) will be taken orally, once daily in the morning after an overnight fast for 14 consecutive days.
Two capsules of placebo will be taken orally, once daily in the morning after an overnight fast for 14 consecutive days.
Optic Neuritis Clinic, Danish Multiple Sclerosis Center, Department of Neurology, Copenhagen University Hospital, Rigshospitalet-Glostrup
Glostrup Municipality, Denmark
Regulatory T cells (first primary outcome)
FoxP3+CD25+CD127- regulatory T cells expressed as a percentage of single, live CD3+CD4+CD8- lymphocytes. Analysed in freshly isolated peripheral blood mononuclear cells using a Symphony A3 flowcytometer.
Time frame: Results from fasting blood samples taken on day 15 and adjusted for results from day 1 (fasting just before first supplement/placebo dosis).
Brain-derived neurotrophic factor (second primary outcome)
Brain-derived neurotrophic factor measured in plasma samples using ELISA or mesoscale.
Time frame: Results from fasting blood samples taken on day 15 and adjusted for results from day 1 (fasting just before first supplement/placebo dosis).
Flowcytometric profiling of T cells
T cell profiling of freshly isolated peripheral blood mononuclear cells using a Symphony A3 flowcytometer. Panel antigens: CD3, CD4, CD8, CD45RA, CCR7, CXCR3, CCR6, CCR4, CCR10, CD25, CD127, FoxP3. Target populations Th1: CXCR3+CCR4-CCR6-CCR10- Th2: CXCR3-CCR4+CCR6-CCR10- Th17: CXCR3-CCR4+CCR6+CCR10- Th17.1: CXCR3+CCR4-CCR6+CCR10- Th22: CXCR3-CCR4+CCR6+CCR10+ all of the above expressed as a percentage of single, live CD3+CD4+CD8-CD45RA- lymphocytes. Furthermore, Th1/Th2 and Th17/Treg ratios will be calculated and the expression of CCR7 will be analysed within the target populations. In addition, the expression of the above chemokine receptors will be explored within the population of FoxP3+CD25+C1D127- T regulatory cells. This will allow for monitoring of newly identified T cells subsets such as Th1-like Tregs. Lastly, an untargetted approach may be employed to allow for unbiased identification of changes in novel, yet uncharacterized populations.
Time frame: Results from fasting blood samples taken on day 15 and adjusted for results from day 1 (fasting just before first supplement/placebo dosis).
CRP
C-reactive protein (CRP) measured in plasma (mg/L) as a biomarker of infection and systemic inflammation. Lower-limit of quantification: 0,4 mg/L. Values below 0,4 mg/L are imputed as 0,2 mg/L.
Time frame: Results from blood samples taken on day 15 (just before last supplement/placebo dosis) and adjusted for results from day 1 (just before first supplement/placebo dosis).
Triglycerides
Plasma triglycerides (mmol/l).
Time frame: Results from fasting blood samples taken on day 15 and adjusted for results from day 1 (fasting just before first supplement/placebo dosis).
non-HDL cholesterol
Non-HDL cholesterol calculated as total cholesterol minus HDL cholesterol (mmol/l)
Time frame: Results from fasting blood samples taken on day 15 and adjusted for results from day 1 (fasting just before first supplement/placebo dosis).
C-peptide
Proinsulin C-peptide (pmol/l) measured in plasma.
Time frame: Results from fasting blood samples taken on day 15 and adjusted for results from day 1 (fasting just before first supplement/placebo dosis).
Fasting glucose
Plasma glucose (mmol/l). Participants abstain from eating and drinking after 22.00 the day before. Only water is allowed. Fasting blood samples are taken between 8.00-10.00 in the morning.
Time frame: Results from fasting blood samples taken on day 15 and adjusted for results from day 1 (fasting just before first supplement/placebo dosis).
Isoprostane-F2-alpha
Isoprostane-F2-alpha measured in blood or morningurine samples as a marker of lipid oxidation.
Time frame: Results from samples taken on day 15 and adjusted for results from day 1.
8-oxo-dG
8-oxo-dG (8-Oxo-2'-deoxyguanosine) measured in blood or morningurine samples as a marker of DNA-related stress damage.
Time frame: Results from samples taken on day 15 and adjusted for results from day 1.
Serum metabolomics
Targetted and untargetted liquid-chromatography mass-spectrometry-based metabolomics of serum samples. Targetted analyses aim to quantify indole-3-propionic acid and its metabolites (biomarker of compliance as well as absorptive and metabolic capacity), other bacterial- and host metabolites of tryptophan as well as short-chain fatty acids.
Time frame: Four samples in total. Day 1 prior to and again 1.5 hour after intake of first capsule of IPA/ placeblo. Day 15 prior to and again 1.5 hour after intake of last capsule of IPA/ placebo.
Total cholesterol
Plasma cholesterol (mmol/l).
Time frame: Results from fasting blood samples taken on day 15 and adjusted for results from day 1 (fasting just before first supplement/placebo dosis).
VLDL cholesterol
Plasma very low-density lipoproteins (mmol/l).
Time frame: Results from fasting blood samples taken on day 15 and adjusted for results from day 1 (fasting just before first supplement/placebo dosis).
LDL cholesterol
Plasma low-density lipoprotein (LDL) (mmol/l).
Time frame: Results from fasting blood samples taken on day 15 and adjusted for results from day 1 (fasting just before first supplement/placebo dosis).
HDL cholesterol
Plasma high-density lipoprotein (HDL) (mmol/l).
Time frame: Results from fasting blood samples taken on day 15 and adjusted for results from day 1 (fasting just before first supplement/placebo dosis).
Malondialdehyde
Malondialdehyde measured in blood or morningurine samples as a marker of oxidative stress.
Time frame: Results from samples taken on day 15 and adjusted for results from day 1.
Protein carbonyls
Protein carbonyls measured in blood or morningurine samples as a marker of protein oxidation.
Time frame: Results from samples taken on day 15 and adjusted for results from day 1.
Glycated hemoglobin (HbA1c)
HbA1c (IFCC, mmol/mol) measured in whole blood. Estimated average glucose values (mmol/l) are also calculated automatically from HbA1c by our laboratory.
Time frame: Results from fasting blood samples taken on day 15 and adjusted for results from day 1 (fasting just before first supplement/placebo dosis).
Changes in the gut microbiome
Characterization of the gut microbiome using molecular biology methods such as 16s rRNA sequencing.
Time frame: Fecal samples are collected at three time points: prior to supplementation (earliest 48 hours prior to first visit (day 1)), short after initiation of supplementation (day 3 or soonest thereafter) and again earliest 48 hours prior to last visit.
Characterization of the metabolic activity of the gut microbiota
Targetted and untargetted liquid-chromatography mass-spectrometry-based metabolomics. Targetted analyses aim to quantify indole-3-propionic acid, other bacterial- and host metabolites of tryptophan as well as short-chain fatty acids.
Time frame: Fecal samples are collected at three time points: prior to supplementation (earliest 48 hours prior to first visit (day 1)), short after initiation of supplementation (day 3 or soonest thereafter) and again earliest 48 hours prior to last visit.
Bacterial polysaccharides
Endotoxin, capsular polysaccharides or other bacterial polysaccharides measured in blood samples as biomarker of bacterial translocation across the intestinal epithelium.
Time frame: Results from samples taken on day 15 and adjusted for results from day 1.
Pre-haptoglobin 2
Measurement of pre-haptoglobin 2 in blood samples as a biomarker of intestinal permeability.
Time frame: Results from samples taken on day 15 and adjusted for results from day 1.
Intestinal fatty acid binding protein
Measurements of intestinal fatty acid binding protein in blood samples as a biomarker of enterocyte damage.
Time frame: Results from samples taken on day 15 and adjusted for results from day 1.
Citrulline
Measurement of citrulline in blood samples as a biomarker of intestinal function.
Time frame: Results from samples taken on day 15 and adjusted for results from day 1.
Calprotectin
Calprotectin measured in fecal samples as a biomarker of intestinal inflammation.
Time frame: Results from samples taken on day 15 and adjusted for results from day 1.
Neopterin
Neopterin measured in morningurine samples as a biomarker of systemic inflammation.
Time frame: Results from samples taken on day 15 and adjusted for results from day 1.
suPAR
Soluble urokinase plasminogen activator receptor (suPAR) measured in blood samples.
Time frame: Results from samples taken on day 15 and adjusted for results from day 1.
Microvesicles
Flow cytometric analyses of microvesicles/ microparticles in platelet-free plasma as biomarker of systemic inflammation.
Time frame: Results from samples taken on day 15 and adjusted for results from day 1.
Endothelial progenitor cells
Flow cytometric analyses of endothelial progenitor cells measured in platelet-free plasma as biomarker of systemic inflammation
Time frame: Results from samples taken on day 15 and adjusted for results from day 1.
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