Chronic Granulomatous Lung Inflammation Elicited by Carbon Nanotubes

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DESCRIPTION (provided by applicant): Use of nanomaterials in manufactured consumer products is a rapidly expanding area but potential toxicities have not been established. Combustion-generated multiwall carbon nanotubes (MWCNT) or nanoparticles are ubiquitous in non-manufacturing environments and detectable in vapors from diesel fuel, methane, propane and natural gas. Carbon nanotubes induce granulomas or inflammation in some experimental animals. Pulmonary granulomas in human disease may form in response to environmental stimuli such as intracellular pathogens, inert materials, and organic antigens. In sarcoidosis, a prototypical granulomatous disease, etiology remains obscure. Multiple environmental risk factors have been linked to sarcoidosis, including exposure to wood-burning stoves, fireplaces, and firefighting - conditions that might favor carbon nanotube formation in ambient air. Investigation of putative nanotube environmental factors linked to sarcoidosis has not been done using animal models. This proposal will utilize a novel murine MWCNT-elicited, chronic granuloma model to investigate the impact of carbon nanotubes on specific host receptors, peroxisome proliferator-activated receptor? (PPAR?) and chemotactic cytokine receptor 5 (CCR5), reported to be dysregulated in sarcoidosis lung. PPAR?, a negative regulator of inflammation, is constitutively expressed in healthy alveolar macrophages but deficient in severe sarcoidosis. In contrast, proinflammatory CCR5 ligands are not found in healthy lung but are elevated in sarcoidosis. We noted similar findings in lungs of MWCNT-instilled mice: PPAR? is depressed and CCR5 ligands are elevated. Based on these data, we hypothesize that MWCNT repress PPAR? and upregulate CCR5 pathways to form pulmonary granulomas with chronic inflammation. Specific Aim 1 will determine the role of PPAR? in the MWCNT model by monitoring granuloma size and numbers in: (a) macrophage-specific PPAR?-null versus wild-type mice; and (b) mice treated with lentivirus-PPAR? plasmids, PPAR? agonist rosiglitazone; or PPAR? antagonist BADGE versus untreated mice. Specific Aim 2 will examine CCR5 involvement in MWCNT granulomas by quantifying CCR5 receptor and chemokines in bronchoalveolar lavage (BAL) derived alveolar macrophages, BAL fluids, and in granulomatous foci isolated by laser-capture microdissection [LCM], from untreated wild-type and PPAR? null mice versus mice treated with a CCR5 blocker. This study will afford students opportunities to gain experience with animal models of lung disease, learn effects of gene deletion in disease, and interact with physicians to learn environmental causes of human lung disease and how human lung disease is diagnosed and treated. Students will also learn lentivirus plasmid construction for gene transduction, quantitative RTPCR, LCM, Luminex assays, and imaging methodology. In summary, this unique investigation of MWCNT-elicited granulomatous lung disease is well suited for student participation in an area with environmental impact on human disease.