Abstract
BackgroundDeclined lung function is a risk factor for particulate matter associated respiratory diseases like asthma and chronic obstructive pulmonary disease (COPD). Carbon nanoparticles (CNP) are a prominent component of outdoor air pollution that causes pulmonary toxicity mainly through inflammation. Recently we demonstrated that mice (C3H/HeJ) with higher than normal pulmonary function resolved the elicited pulmonary inflammation following CNP exposure through activation of defense and homeostasis maintenance pathways. To test whether CNP-induced inflammation is affected by declined lung function, we exposed JF1/Msf (JF1) mice with lower than normal pulmonary function to CNP and studied the pulmonary inflammation and its resolution.Methods5 μg, 20 μg and 50 μg CNP (Printex 90) were intratracheally instilled in JF1 mice to determine the dose response and the time course of inflammation over 7 days (20 μg dosage). Inflammation was assessed using histology, bronchoalveolar lavage (BAL) analysis and by a panel of 62 protein markers.Results24 h after instillation, 20 μg and 50 μg CNP caused a 25 fold and 19 fold increased polymorphonuclear leucocytes (PMN) respectively while the 5 μg represented the 'no observable adverse effect level' as reflected by PMN influx (9.7 × 10E3 vs 8.9 × 10E3), and BAL/lung concentrations of pro-inflammatory cytokines. Time course assessment of the inflammatory response revealed that compared to day1 the elevated BAL PMN counts (246.4 × 10E3) were significantly decreased at day 3 (72.9 × 10E3) and day 7 (48.5 × 10E3) but did not reach baseline levels indicating slow PMN resolution kinetics. Strikingly on day 7 the number of macrophages doubled (455.0 × 10E3 vs 204.7 × 10E3) and lymphocytes were 7-fold induced (80.6 × 10E3 vs 11.2 × 10E3) compared to day1. At day 7 elevated levels of IL1B, TNF, IL4, MDC/CCL22, FVII, and vWF were detected in JF1 lungs which can be associated to macrophage and lymphocyte activation.ConclusionThis explorative study indicates that JF1 mice with impaired pulmonary function also exhibits delayed resolution of particle mediated lung inflammation as evident from elevated PMN and accumulation of macrophages and lymphocytes on day7. It is plausible that elevated levels of IL1B, IL4, TNF, CCL22/MDC, FVII and vWF counteract defense and homeostatic pathways thereby driving this phenomenon.
Highlights
A major component of urban air pollution is particulate matter (PM)
The time course analysis revealed an intermittent decline of bronchoalveolar lavage (BAL) leucocytes almost to control level on day 3 (0.31 ± 0.07 × 10E6 cells/lung, n.s.) followed by an increase to 0.51 ± 0.11 × 10E6 cells/ lung on day 7, i.e. to 188% of that observed in sham exposed mice
polymorphonuclear leucocytes (PMN) As observed for the total cell count no significant induction of PMN was detected following i.t instillation of 5 μg Carbon nanoparticles (CNP) (8.9 ± 2.3 × 10E3 PMNs) compared to control (9.7 ± 1.5 × 10E3 PMNs, Figure 1a)
Summary
A major component of urban air pollution is particulate matter (PM). Several studies show that individuals with poor pulmonary function are expected to be at higher risk to respiratory diseases [4,5,6] like asthma or chronic obstructive pulmonary disease (COPD). Declined lung function is a risk factor for particulate matter associated respiratory diseases like asthma and chronic obstructive pulmonary disease (COPD). Carbon nanoparticles (CNP) are a prominent component of outdoor air pollution that causes pulmonary toxicity mainly through inflammation. We demonstrated that mice (C3H/HeJ) with higher than normal pulmonary function resolved the elicited pulmonary inflammation following CNP exposure through activation of defense and homeostasis maintenance pathways. To test whether CNP-induced inflammation is affected by declined lung function, we exposed JF1/Msf (JF1) mice with lower than normal pulmonary function to CNP and studied the pulmonary inflammation and its resolution
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