Clinical trial NCT03183830: Influence of Dietary Nitrate on Skin Inflammation
Official title: A Double-blind, Randomised, Placebo-controlled Parallel Study to Investigate the Influence of Dietary Nitrate on Skin Inflammation in Healthy Volunteers
Study type: INTERVENTIONAL
Overall status: COMPLETED
Phase: PHASE1
Conditions: Cardiovascular Diseases
Inflammation
Inflammation; Skin
Inflammatory Response
Nitric Oxide
Keywords: Cardiovascular Disease
Inorganic nitrate
Nitric Oxide
Inflammation
Lead sponsor: Queen Mary University of London
Sponsor class: OTHER
First posted: 2017-06-12
Enrollment: 24
Sex: MALE
Minimum age (years): 18
Maximum age (years): 45
Standard ages: ADULT
Accepts healthy volunteers: yes
Allocation: RANDOMIZED
Intervention model: PARALLEL
Intervention model description: Double-blind randomised-control parallel two-limb study
Primary purpose: BASIC_SCIENCE

Brief summary: This study evaluates the potential anti-inflammatory effects of inorganic dietary nitrate in a model of acute inflammation relevant to cardiovascular disease (CVD).

Green leafy vegetables contain large amounts of inorganic nitrate, and research suggests that this nitrate has beneficial effects on the heart and blood vessels. The Ahluwalia Group have shown anti-inflammatory benefits of inorganic nitrate in pre-clinical models of CVD, early mechanistic studies in healthy volunteers, and in patients with hypertension, hypercholesterolaemia and those suffering acute heart attacks that translate to cardiovascular benefits. Understanding the mechanism of how this is achieved may open new therapeutic options in CVD.

The Investigators therefore wish to explore whether inorganic nitrate might alter inflammatory responses using a blister-model of acute skin inflammation. This study is a randomised control trial with parallel limbs where half of patients receive nitrate-rich beetroot juice, and the other half a nitrate-deplete placebo beetroot juice.

Detailed description: Nitric oxide (NO) is an important substance produced continuously by all blood vessels. It is thought to maintain health, in part, by preventing and suppressing inflammatory responses. NO is normally generated at the endothelium by a group of important enzymes called nitric oxide synthases. However, in chronic inflammatory states such as those seen in cardiovascular disease (CVD), the endothelial isoform of the enzyme becomes dysfunctional and produces less NO, and the NO that is produced is scavenged by the products of oxidative stress.

Giving NO back to the blood vessel to mediate its beneficial effects is not straightforward. However, the Ahluwalia Group have shown that dietary inorganic nitrate, both as a capsule and a dietary intervention with nitrate-rich beetroot juice, has a number of beneficial effects in CVD states. This beneficial effect is mediated through it's endogenous conversion from nitrate to nitrite in the mouth, and then from nitrite to NO via nitrite reductases within the blood vessel. The Investigators have shown benefit of inorganic nitrate in pre-clinical models of CVD, early mechanistic studies in healthy volunteers, and anti-inflammatory benefits in patients with hypertension, hypercholesterolaemia and those suffering acute heart attacks.

The Investigators wish to prospectively investigate the anti-inflammatory effects of inorganic nitrate using a cantharidin-induced blister model of acute inflammation. This allows investigation of the innate immune system's response to an acute insult and characterise the inflammatory and resolution phases. Cantharidin is commonly used as a vesicant in the treatment of plantar verrucae and molluscum contagiosum, and experimentally to study the pharmacokinetics of drugs within the interstitial space.

This will be a double-blind placebo-controlled parallel limb study supplementing 24 healthy volunteers with dietary-rich beetroot juice versus nitrate-deplete placebo juice, to investigate blister formation, and inflammatory cell recruitment and activation.

Eligibility criteria: Inclusion Criteria:

* Healthy volunteers
* Caucasian
* Willing to provide informed consent

Exclusion Criteria:

* Healthy subjects unwilling to consent
* Non-caucasian volunteers
* History of any serious illnesses, including recent infections or trauma
* Subjects taking systemic medication (other than the oral contraceptive pill)
* Subjects with self-reported use of mouthwash or tongue scrapers
* Subjects with recent or current antibiotic use
* Subjects with a history, or recent treatment of (within last 3 months) any oral condition (excluding caries), including gingivitis, periodontitis and halitosis
* Subjects with a history of skin conditions
* Subjects with and history of allergic reaction to any topical application
* Subjects with any history of a bloodborne infectious disease such Hepatitis B or C virus, or HIV

We have excluded non-caucasian volunteers due to a small incidence of prolonged skin hyperpigmentation in non-caucasians in previous studies.

We have excluded subjects using mouthwash/tongue scrapers and oral conditions as we know that the nitrate ingested from the diet (i.e. beetroot juice) is converted to nitrite by the commensal bacteria in the back of the mouth. Subjects who have oral conditions or use mouthwash/tongue scrapers would have differences in oral bacterial populations, both in number and species. Therefore, by excluding these subjects, we will try and keep this variable as similar as possible in both groups.

Primary outcomes:
measure: Change in plasma nitrate levels
timeFrame: 2 weeks
measure: Change in blister fluid leucocytes
timeFrame: 2 weeks
Secondary outcomes:
measure: Change in blister fluid cytokine composition
timeFrame: 2 weeks
measure: Change in peripheral markers of inflammation
timeFrame: 2 weeks
measure: Change in non-invasive blood pressure measurement
timeFrame: 2 weeks
Other outcomes:
Locations:
city: London
country: United Kingdom
facility: Queen Mary University of London
Study officials:
affiliation: Queen Mary University of London
name: Prof Amrita Ahluwalia, BSc PhD
role: PRINCIPAL_INVESTIGATOR
References:
citation: Khambata RS, Ghosh SM, Rathod KS, Thevathasan T, Filomena F, Xiao Q, Ahluwalia A. Antiinflammatory actions of inorganic nitrate stabilize the atherosclerotic plaque. Proc Natl Acad Sci U S A. 2017 Jan 24;114(4):E550-E559. doi: 10.1073/pnas.1613063114. Epub 2017 Jan 5.
citation: Rathod KS, Kapil V, Velmurugan S, Khambata RS, Siddique U, Khan S, Van Eijl S, Gee LC, Bansal J, Pitrola K, Shaw C, D'Acquisto F, Colas RA, Marelli-Berg F, Dalli J, Ahluwalia A. Accelerated resolution of inflammation underlies sex differences in inflammatory responses in humans. J Clin Invest. 2017 Jan 3;127(1):169-182. doi: 10.1172/JCI89429. Epub 2016 Nov 28.
citation: Kapil V, Khambata RS, Robertson A, Caulfield MJ, Ahluwalia A. Dietary nitrate provides sustained blood pressure lowering in hypertensive patients: a randomized, phase 2, double-blind, placebo-controlled study. Hypertension. 2015 Feb;65(2):320-7. doi: 10.1161/HYPERTENSIONAHA.114.04675. Epub 2014 Nov 24.
citation: Velmurugan S, Gan JM, Rathod KS, Khambata RS, Ghosh SM, Hartley A, Van Eijl S, Sagi-Kiss V, Chowdhury TA, Curtis M, Kuhnle GG, Wade WG, Ahluwalia A. Dietary nitrate improves vascular function in patients with hypercholesterolemia: a randomized, double-blind, placebo-controlled study. Am J Clin Nutr. 2016 Jan;103(1):25-38. doi: 10.3945/ajcn.115.116244. Epub 2015 Nov 25.
citation: Jones DA, Pellaton C, Velmurugan S, Rathod KS, Andiapen M, Antoniou S, van Eijl S, Webb AJ, Westwood MA, Parmar MK, Mathur A, Ahluwalia A. Randomized phase 2 trial of intracoronary nitrite during acute myocardial infarction. Circ Res. 2015 Jan 30;116(3):437-47. doi: 10.1161/CIRCRESAHA.116.305082. Epub 2014 Dec 15.
citation: Day RM, Harbord M, Forbes A, Segal AW. Cantharidin blisters: a technique for investigating leukocyte trafficking and cytokine production at sites of inflammation in humans. J Immunol Methods. 2001 Nov 1;257(1-2):213-20. doi: 10.1016/s0022-1759(01)00467-7.