New instrumentation will be assembled that is capable of determining ultrafine particle chemical composition both in bulk samples of ultrafine particles collected by cascade impaction and by a novel ultrafine particle aerosol time of flight mass spectrometer designed to determine the chemical composition of ultrafine particles at the single particle level. This instrumentation will be field tested and then used to characterize ultrafine particles in the atmosphere of one western city and one eastern city during each season of the year.

In addition, archived data on ultrafine particle chemical composition measured previously during source tests by the Caltech group will be reprocessed to display the chemical composition of the smallest particles emitted. Comparisons will then be drawn between atmospheric samples and source samples to determine the extent to which the two data sets do or do not resemble each other, which will shed light on the extent to which atmospheric ultrafine particles may be affected by atmospheric chemical transformations or new particle formation. These results will serve to adjust the composition of the laboratory-generated PM for the controlled clinical, animal and in vitro studies.

The following hypotheses will be tested in patients with chronic diseases of the lung and the heart:

1. Concentration of ambient accumulation mode (AP) and ultrafine particles (UP) is associated with inflammation of the airways, as well as increases in plasma viscosity, fibrinogen and other acute phase proteins in the blood.
2. Increases in the coagulability of the blood are associated with changes in the autonomic control of the heart.
3. Exposure to UP is more closely related to the health effects than exposure to AP mass. The result of this Core will be a valuable input for the clinical, animal and in vitro studies with respect to planned mixed PM-oxidant exposures.

1. Injury to epithelial cells by reactive oxygen species, possibly enhanced in the presence of metals via Haber-Weiss and Fenton chemistry, accompanied by activation of nuclear regulatory factors, leading to elaboration of proinflammatory cytokines, including interleukins-8 (IL-8) and -6 (IL-6), and increased expression of nitric oxide synthase (NOS), with increased nitric oxide (NO) in exhaled air.
2. Activation of vascular endothelium and circulating leukocytes. Emigration of inflammatory cells from blood to tissue sites involves upregulation of adhesion molecules and other markers on vascular endothelium and on circulating leukocytes. The events in the process of leukocyte-endothelial binding include a) increased expression of adhesion molecules followed by shedding of adhesion molecules as cells "tether and roll", b) leukocyte activation, c) stable adhesion, and d) transmigration through the epithelium. Platelets become activated and adhere to endothelium and leukocytes. Endothelial activation may further contribute to the increase in exhaled NO concentrations seen with airway inflammation.
3. Increased release of IL-6 and tissue factor by activated blood monononuclear cells. Interleukin-6 initiates hepatic synthesis of acute phase proteins, including serum amyloid A (SAA), fibrinogen, and plasminogen activator inhibitor-1 (PAI-1). Monocyte tissue factor and endothelial cell activation initiate the coagulation cascade, as reflected by the presence of D-dimer, soluble fibrin, and prothrombin1+2.
4. Possible adverse cardiac events in patients with critical coronary lesions, as a consequence of increased blood coagulability, platelet activation, and endothelial dysfunction.

Thus, the overall objective of the animal studies is to identify factors which are causally associated with adverse pulmonary and cardiovascular health effects after low-level exposures to environmentally-relevant particles. These factors are related to particle characteristics (UP vs. AP; transition metals); dosimetric aspects (lung deposition and disposition); host susceptibility (advanced age; cardiovascular disorders; respiratory tract sensitization); cellular mechanisms (role of Clara cells); and pollutant co-exposure (ozone).

Our mechanistic hypothesis is that inhaled ultrafine particles activate resident inflammatory cells leading to oxidative stress and production of cytokines, and that this primary response is further amplified through inflammatory cell recruitment and elaboration of both inflammatory and epithelial cell-derived cytokines. Based upon our preliminary data, we further hypothesize that the primary response is greater to UP than AP, and which is further enhanced by endotoxin exposure. Amplification of the pulmonary response leads to a parallel amplification of the systemic acute phase response with associated changes in blood coagulability and cardiac events.

The proposed experiments are intended to provide a link between the whole animal and controlled clinical (human) exposures, described in the other programs of this PM Center, by defining mechanisms that follow particle cell contact and to test the specific hypothesis that many of the subsequent physiologic effects are the consequences of cellular oxidative stress. We further plan to examine host and environmental factors, including age, the influence of co-exposure to gaseous oxidants or prior priming or activation by pre-exposure to other inflammatory stimuli.

A key component of the proposed studies is our plan to examine these particle cell interactions in individual cell populations to begin to assess the role of epithelial, inflammatory and interstitial cells in the systemic response to UP. We suggest that production of both inflammatory and fibrotic mediators following particle interaction is not limited to classic inflammatory cells, and that pulmonary parenchymal elements including epithelial cells (type II, Clara cells) and fibroblasts may also contribute to the milieu.