Study of cytokine gene expression in small cell samples: use in induced sputum

Sputum Cytokine Profiling in COPD: Comparison Between Stable Disease and Exacerbation

Purpose

Cytokines are extracellular signaling proteins that have been widely implicated in the pathogenesis of chronic obstructive pulmonary disease (COPD). Here, we investigated cytokine expression both at the mRNA and protein level in the sputum of healthy individuals, stable COPD patients, and those experiencing a severe acute exacerbation (AECOPD) requiring hospitalization.

Patients and Methods

Sputum was collected in 19 healthy controls, 25 clinically stable COPD patients, and 31 patients with AECOPD. In AECOPD patients sample collection was performed both at the time of hospital admission and at discharge following treatment. Sputum supernatant was analyzed by an antibody microarray detecting 120 cytokines simultaneously, while the mRNA expression of 14 selected cytokines in sputum cells was investigated by real-time PCR (qPCR).

Results

Proteomic analysis identified interleukin (IL)-6 and growth-regulated oncogene (GRO)α as the only sputum cytokines that were differentially expressed between stable COPD patients and healthy controls. At the onset of AECOPD, several cytokines exhibited altered sputum expression compared to stable COPD. Recovery from AECOPD induced significant changes in the sputum cytokine protein profile; however, the length of hospitalization was insufficient for most cytokines to return to stable levels. With regard to gene expression analysis by qPCR, we found that bone morphogenetic protein (BMP)-4 was up-regulated, while IL-1α, monokine-induced by interferon-γ (MIG), and BMP-6 were down-regulated at the mRNA level in patients with AECOPD compared to stable disease.

Conclusion

The sputum cytokine signature of AECOPD differs from that of stable COPD. Protein level changes are asynchronous with changes in gene expression at the mRNA level in AECOPD. The observation that the levels of most cytokines do not stabilize with acute treatment of AECOPD suggests a prolonged effect of exacerbation on the status of COPD patients.

Effects of woodsmoke exposure on airway inflammation in rural Guatemalan women

Background

More than two-fifths of the world’s population uses solid fuels, mostly biomass, for cooking. The resulting biomass smoke exposure is a major cause of chronic obstructive pulmonary disease (COPD) among women in developing countries.

Objective

To assess whether lower woodsmoke exposure from use of a stove with a chimney, compared to open fires, is associated with lower markers of airway inflammation in young women.

Design

We carried out a cross-sectional analysis on a sub-cohort of participants enrolled in a randomized controlled trial in rural Guatemala, RESPIRE.

Participants

We recruited 45 indigenous women at the end of the 18-month trial; 19 women who had been using the chimney stove for 18–24 months and 26 women still using open fires.

Measurements

We obtained spirometry and induced sputum for cell counts, gene expression of IL-8, TNF-α, MMP-9 and 12, and protein concentrations of IL-8, myeloperoxidase and fibronectin. Exhaled carbon monoxide (CO) and 48-hr personal CO tubes were measured to assess smoke exposure.

Results

MMP-9 gene expression was significantly lower in women using chimney stoves. Higher exhaled CO concentrations were significantly associated with higher gene expression of IL-8, TNF-α, and MMP-9. Higher 48-hr personal CO concentrations were associated with higher gene expression of IL-8, TNF- α, MMP-9 and MMP-12; reaching statistical significance for MMP-9 and MMP-12.

Conclusions

Compared to using an open wood fire for cooking, use of a chimney stove was associated with lower gene expression of MMP-9, a potential mediator of airway remodeling. Among all participants, indoor biomass smoke exposure was associated with higher gene expression of multiple mediators of airway inflammation and remodeling; these mechanisms may explain some of the observed association between prolonged biomass smoke exposure and COPD.

Hemolytic phospholipase C inhibition protects lung function during Pseudomonas aeruginosa infection

RATIONALE

The opportunistic pathogen Pseudomonas aeruginosa causes both acute and chronic lung infections and is particularly problematic in patients with cystic fibrosis and those undergoing mechanical ventilation. Decreased lung function contributes significantly to morbidity and mortality during P. aeruginosa infection, and damage inflicted by P. aeruginosa virulence factors contributes to lung function decline.

OBJECTIVES

We sought to describe direct contribution of a bacterial phospholipase C/sphingomyelinase, PlcHR, to alteration of host lung physiology and characterize a potential therapeutic for protection of lung function.

METHODS

We infected C57Bl/6 mice with P. aeruginosa wild-type or isogenic plcHR deletion strains and measured lung function using computer-controlled ventilators. For in vivo testing, miltefosine was delivered intraperitoneally 1 hour after infection. Infection and respiratory endpoints were at 24 hours after infection.

MEASUREMENTS AND MAIN RESULTS

P. aeruginosa wild-type infection caused significant lung function impairment, whereas the effects of a ΔplcHR strain infection were much less severe. Surfactometry analysis of bronchoalveolar lavage fluid indicated that PlcHR decreased pulmonary surfactant function. Miltefosine has structural similarity to the PC and sphingomyelin substrates of PlcHR, and we found that it inhibits the cleavage of these choline-containing lipids in vitro. Miltefosine administration after P. aeruginosa infection limited the negative effects of PlcHR activity on lung function.

CONCLUSIONS

We have directly linked production of a single virulence factor in P. aeruginosa with effects on lung function, and demonstrated that the inhibitor miltefosine protects lung function from PlcHR-dependent surfactant dysfunction.