Effect of Diesel Exhaust Particulate Exposures on Endothelial Function in Humans

January 14, 2013 updated by: Joel Daniel Kaufman, University of Washington

Effect of Diesel Exhaust Particulate Exposures on Endothelial Function in Humans - the Role of Oxidative Stress

Objectives: This proposal addresses the overall hypothesis that ambient fine particulate matter exerts cardiovascular health effects via alteration of endothelial homeostasis, through a mechanism mediated by oxidative stress. This project will use a controlled human inhalation exposure to diesel exhaust particulate (DEP) as a model to address the following objectives: 1) Determine whether exposure to inhaled DEP is associated with endothelial dysfunction in a concentration-related manner; 2) Determine whether exposure to inhaled DEP is associated with evidence of systemic oxidative stress; and 3) Determine whether antioxidant supplementation blunts the DEP effect on endothelial function.

Study Overview

Status

Completed

Conditions

Intervention / Treatment

Detailed Description

OBJECTIVES Evidence of the cardiovascular health effects of both acute and chronic exposure to ambient fine particulate matter (PM) has continued to accumulate in epidemiologic and experimental studies, without a demonstrated coherent pathophysiologic explanation. At the same time, the role of endothelial homeostasis in the development and triggering of cardiovascular disease has become more clear and compelling. Importantly, oxidative stress has emerged as a potential link between these two developments: Oxidative stress is known to play a role in endothelial dysfunction and is exerted by components of PM, especially of PM from combustion products. Based on this we propose an overall hypothesis: Inhalation of combustion-derived particles impact cardiovascular health by impairing endothelial function, through mechanisms mediated by increased oxidative stress.

Diesel exhaust particulate (DEP), an important contributor to ambient fine PM, has been demonstrated to exert oxidative stress in experimental systems. We propose a series of experiments to explore whether human exposure to DEP results in alteration of endothelial homeostasis and evidence of oxidative stress, and whether an antioxidant regimen can blunt the effects on endothelial function.

The objectives of this proposed research are to address the following specific hypotheses:

  1. Human exposure to inhaled DEP (at concentrations approximating 0, 100, 200 μg PM2.5/m3 [PM less than 2.5 microns in aerodynamic diameter]) results in concentration-related alteration of endothelial homeostasis, as reflected in ultrasonographic measurement of the brachial artery, plasma markers of endothelial homeostasis (endothelin-1, ICAM-1 [intercellular adhesion molecule-1], e-selectin, nitric oxide metabolites nitrate [NO3-] and nitrite [NO2-], IL-6, and TNF-α), and markers of thrombosis associated with endothelial activation or injury (plasminogen activator inhibitor-1 [PAI-1], Von Willebrand's factor [VWF], and D-dimer).
  2. Human exposure to inhaled DEP at 200 µg PM2.5/m3 results in evidence of systemic oxidative stress as assessed by markers in plasma and urine (isoprostane F-2α).
  3. Reduction in oxidant stress by ascorbate and N-acetylcysteine supplementation blunts the effect of inhaled DEP on endothelial function, as determined by ultrasonographic assessment of the brachial artery, plasma markers of endothelial homeostasis, or markers of thrombosis associated with endothelial activation.

Study Type

Interventional

Enrollment (Actual)

24

Phase

  • Not Applicable

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Locations

  • United States
    • Washington
      • Seattle, Washington, United States, 98105
        • Northlake Laboratory

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

18 years to 49 years (Adult)

Accepts Healthy Volunteers

No

Genders Eligible for Study

All

Description

Inclusion Criteria:

  • Healthy adults aged 18-49.

Exclusion Criteria:

  • Nonsmokers, no history of hypertension, asthma, diabetes, hypercholesterolemia, or other chronic conditions requiring ongoing medical care. No recent history of antioxidant, vitamin/mineral/botanical, or fatty acid supplementation beyond a daily multi-vitamin.

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Prevention
  • Allocation: Randomized
  • Interventional Model: Crossover Assignment
  • Masking: Quadruple

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Experimental: Diesel Exhaust
Drug: N-acetylcysteine, ascorbate
NAC: 600mg twice daily for the day prior to exposure and 1x pre-exposure Ascorbate: 500mg twice daily for 7 days prior to exposure
Drug: Placebo
matched appearance to acetylcysteine and ascorbate intervention
Sham Comparator: Filtered Air
Drug: N-acetylcysteine, ascorbate
NAC: 600mg twice daily for the day prior to exposure and 1x pre-exposure Ascorbate: 500mg twice daily for 7 days prior to exposure
Drug: Placebo
matched appearance to acetylcysteine and ascorbate intervention

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Time Frame
Brachial artery caliber
Time Frame: Pre-exposure, immediate post-exposure
Pre-exposure, immediate post-exposure

Secondary Outcome Measures

Outcome Measure
Time Frame
Brachial Artery Flow-Mediated Dilation
Time Frame: Post-Exposure
Post-Exposure
Plasma Endothelin-1
Time Frame: Post-exposure (adjusted for pre-exposure level)
Post-exposure (adjusted for pre-exposure level)
Serum IL-6
Time Frame: Post-exposure (adjusted for pre-exposure level)
Post-exposure (adjusted for pre-exposure level)

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

University of Washington

Collaborators

National Institutes of Health (NIH)

Investigators

  • Principal Investigator: Joel D Kaufman, M.D., MPH, University of Washington

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

General Publications

Helpful Links

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start

July 1, 2008

Primary Completion (Actual)

August 1, 2010

Study Completion (Actual)

August 1, 2010

Study Registration Dates

First Submitted

August 25, 2006

First Submitted That Met QC Criteria

February 9, 2007

First Posted (Estimate)

February 12, 2007

Study Record Updates

Last Update Posted (Estimate)

January 16, 2013

Last Update Submitted That Met QC Criteria

January 14, 2013

Last Verified

January 1, 2013

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • 22969-D
  • R830954
  • R827355
  • MO1RR-00037
  • ES015915
  • ES013195

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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