Inflammation synergistically promotes cigarette smoke carcinogen-induced lung tumorigenesis and determines immunotherapy efficacy

Chronic obstructive pulmonary disease (COPD) is a chronic lung inflammatory disease with an increased risk of lung cancer. Pseudomonas aeruginosa (PA) are opportunistic bacteria frequently found in patients with COPD, and associated with increased lung inflammation and acute exacerbations. The impacts of COPD-related inflammation, especially those induced by the PA-produced lipopolysaccharides (LPS), on lung tumorigenesis and the efficacy of immune checkpoint blockades remain poorly understood. In this study, we established a novel murine lung cancer model by treating mice with cigarette smoke carcinogen nitrosamine (NNK) combined with recurrent LPS exposure. LPS-mediated chronic inflammation in NNK-treated mice generates an immunosuppressive microenvironment characterized by the accumulation of myeloid-derived suppressive cells (MDSCs) and regulatory T cells, induced T-cell exhaustion, and enhanced PD-1/PD-L1 activity that resulted in synergistic increases of lung tumorigenesis than NNK treatment alone (>8-fold increase in tumor numbers, P<0.0001). Immunotherapy using anti-PD-1 antibody or anti-Ly6G antibody (to deplete MDSCs) alone reduced tumor growth, and in combination further enhanced the anti-tumor activity. We also identified immune gene signatures from the RNA transcript expression data of our murine cancer model and the published datasets of PD-1 blockade, which effectively predicted treatment responses and survival outcome in cohorts with immunotherapy and conventional treatments. Our results indicate that LPS-mediated chronic inflammation creates a favorable immunosuppressive microenvironment for tumor progression and correlates with the efficacy of anti-PD-1 treatment.

Systemic inhibition of NF-kappaB activation protects from silicosis

Background

Silicosis is a complex lung disease for which no successful treatment is available and therefore lung transplantation is a potential alternative. Tumor necrosis factor alpha (TNFα) plays a central role in the pathogenesis of silicosis. TNFα signaling is mediated by the transcription factor, Nuclear Factor (NF)-κB, which regulates genes controlling several physiological processes including the innate immune responses, cell death, and inflammation. Therefore, inhibition of NF-κB activation represents a potential therapeutic strategy for silicosis.

Methods/Findings

In the present work we evaluated the lung transplant database (May 1986–July 2007) at the University of Pittsburgh to study the efficacy of lung transplantation in patients with silicosis (n = 11). We contrasted the overall survival and rate of graft rejection in these patients to that of patients with idiopathic pulmonary fibrosis (IPF, n = 79) that was selected as a control group because survival benefit of lung transplantation has been identified for these patients. At the time of lung transplantation, we found the lungs of silica-exposed subjects to contain multiple foci of inflammatory cells and silicotic nodules with proximal TNFα expressing macrophage and NF-κB activation in epithelial cells. Patients with silicosis had poor survival (median survival 2.4 yr; confidence interval (CI): 0.16–7.88 yr) compared to IPF patients (5.3 yr; CI: 2.8–15 yr; p = 0.07), and experienced early rejection of their lung grafts (0.9 yr; CI: 0.22–0.9 yr) following lung transplantation (2.4 yr; CI:1.5–3.6 yr; p<0.05). Using a mouse experimental model in which the endotracheal instillation of silica reproduces the silica-induced lung injury observed in humans we found that systemic inhibition of NF-κB activation with a pharmacologic inhibitor (BAY 11-7085) of IκBα phosphorylation decreased silica-induced inflammation and collagen deposition. In contrast, transgenic mice expressing a dominant negative IκBα mutant protein under the control of epithelial cell specific promoters demonstrate enhanced apoptosis and collagen deposition in their lungs in response to silica.

Conclusions

Although limited by its size, our data support that patients with silicosis appear to have poor outcome following lung transplantation. Experimental data indicate that while the systemic inhibition of NF-κB protects from silica-induced lung injury, epithelial cell specific NF-κB inhibition appears to aggravate the outcome of experimental silicosis.

Mitogen-activated protein kinase kinase kinase 1 protects against nickel-induced acute lung injury

Nickel compounds are environmental and occupational hazards that pose serious health problems and are causative factors of acute lung injury. The c-jun N-terminal kinases (JNKs) are regulated through a mitogen-activated protein (MAP) 3 kinase-MAP2 kinase cascade and have been implicated in nickel toxicity. In this study, we used genetically modified cells and mice to investigate the involvement of two upstream MAP3Ks, MAP3K1 and 2, in nickel-induced JNK activation and acute lung injury. In mouse embryonic fibroblasts, levels of JNK activation and cytotoxicity induced by nickel were similar in the Map3k2-null and wild-type cells but were much lower in the Map3k1/Map3k2 double-null cells. Conversely, the levels of JNK activation and cytotoxicity were unexpectedly much higher in the Map3k1-null cells. In adult mouse tissue, MAP3K1 was widely distributed but was abundantly expressed in the bronchiole epithelium of the lung. Accordingly, MAP3K1 ablation in mice resulted in severe nickel-induced acute lung injury and reduced survival. Based on these findings, we propose a role for MAP3K1 in reducing JNK activation and protecting the mice from nickel-induced acute lung injury.

T-cell receptor V beta gene segment expression in diisocyanate-induced occupational asthma

BACKGROUND

Diisocyanates are the most common cause of occupational asthma induced by low-molecular-weight chemicals. The disease appears to be immunologically mediated but is independent of IgE antibody synthesis. An underlying genetic susceptibility is suggested by the fact that the disease only develops in approximately 5% to 10% of exposed workers.

OBJECTIVE

The study was designed to determine whether disease susceptibility is influenced by HLA and T-cell receptor V beta gene segment usage.

METHODS

T-cell receptor V beta repertoires were quantitated by using primer pairs specific for V beta gene segments in conjunction with a common C beta region primer. One group of workers with diisocyanate-induced occupational asthma produced diisocyanate-specific IgG and IgE antibodies, whereas the other group did not produce specific antibodies. Occupational asthma was previously confirmed by either workplace challenge or laboratory specific diisocyanate bronchoprovocation. Control groups consisted of diisocyanate-exposed workers who were free of symptoms, patients with nonoccupational asthma, and unexposed subjects who were free of symptoms.

RESULTS

Lymphocytes from workers with diisocyanate-induced occupational asthma had significantly decreased V beta 1 and V beta 5 gene segment expression before in vitro exposure to diisocyanates, compared with control groups. Percent V beta 1 and V beta 5 gene segment expression was selectively increased when peripheral blood mononuclear cells were stimulated in vitro with diisocyanate-conjugated proteins. Low-resolution HLA class II phenotyping revealed no significant differences in the distribution of HLA-DR or HLA-DQ alleles between diisocyanate-induced occupational asthma and control groups.

CONCLUSIONS

These findings are consistent with a hypothesis that antigen-specific T-cell subpopulations may be sequestered in the lungs of workers with diisocyanate-induced occupational asthma and clonally expand after further exposure to diisocyanates.

Cigarette smoke stimulates release of neutrophil chemotactic activity from cultured bovine bronchial epithelial cells

1. Recruitment of neutrophils into the airway is a prominent feature of chronic bronchitis, a syndrome often associated with exposure to cigarette smoke. Since bronchial epithelial cells are the 'first' lung cells to come into contact with smoke, these cells may be responsible for neutrophil recruitment into the airway by release of neutrophil chemotactic activity in response to cigarette smoke. 2. To evaluate this hypothesis, we prepared bovine bronchial epithelial cells and measured their ability to release neutrophil chemotactic activity following exposure to cigarette smoke. Bronchial epithelial cells were prepared by overnight digestion with protease, filtered through 100-microns Nitex mesh and resuspended in Dulbecco's modified Eagle medium supplemented with 10% fetal calf serum and antibiotics and cultured at 2 x 10(6) cells in 2 ml of medium in 35-mm culture dishes. After 4 days, dishes were rinsed and refed with medium without fetal calf serum and incubated with and without 1:10 diluted smoke extract for 6 h at 37 degrees C. The neutrophil chemotactic activity of the supernatant fluids was measured by the blindwell chamber technique. 3. Cigarette smoke itself added to medium did not stimulate chemotaxis. In contrast, cigarette smoke did stimulate the release of neutrophil chemotactic activity from bovine bronchial epithelial cells [15 +/- 3 (control) versus 74 +/- 5 (smoke), P < 0.01]. 4. This neutrophil chemotactic activity was dialysable, pepsin and acid stable, heat sensitive and lipid extractable. Sephadex G-75 column chromatography demonstrated two peaks of neutrophil chemotactic activity.(ABSTRACT TRUNCATED AT 250 WORDS)

A method for culturing rat oviduct gamma-aminobutyric acid cells

A technique for the culture of rat oviduct gamma-aminobutyric acid (GABA) cells is described. The technique involves first explaining the fimbria and preampulla, which are the oviduct divisions with the highest density of GABA cells. The explanted tissue is cultured in a serum-free medium, to propagate the outgrowing cells. Under the experimental conditions we describe, the majority of the cells maintain GABA expression, as determined by immunostaining with a GABA antiserum.

The effects of irritant aerosols on mucus clearance from large and small conductive airways

The effects of one hour exposures of healthy nonsmoking human volunteers to submicrometer H2SO4 droplets via nasal mask on tracheobronchial mucociliary particle clearance were studied using two different sized monodisperse gamma-tagged Fe2O3 test aerosols. The larger sized Fe2O3 aerosol, 7.5 micrometers AMAD, was deposited primarily in the larger bronchial airways, while the smaller 4 micrometers AMAD aerosol had a much greater fraction deposited in the smaller and more distal conductive airways. Thoracic retention of the Fe2O3 aerosols as a function of time after a brief inhalation was measured with external collimated radiation detectors. At the highest H2SO4 exposure, 1,000 micrograms/m3, there was a pronounced transient slowing of bronchial mucociliary clearance of both the 7.5 and 4 micrometers Fe2O3. On the other hand, at the lowest H2SO4 concentration, 100 micrograms/m3, there was a marked acceleration of the clearance of the 7.5 micrometers Fe2O3, but a slowing of the clearance of the 4 micrometers Fe2O3. Thus, submicrometer H2SO4, which deposits primarily in the distal airways, can slow mucociliary clearance in those airways. In the larger airways, where its deposition is minimal, the H2SO4 can, at the same time, accelerate mucus transport.

Effects of sulfuric acid aerosol inhalations

Submicrometer H2SO4 droplets can affect pulmonary functions in humans. The lowest concentration which has been reported to produce a statistically significant effect on pulmonary mechanics is 1 mg/m3. Effects on tracheobronchial mucociliary clearance of inert particles were observed in our laboratory at much lower concentrations. For ten nonsmoking humans exposed for one hour via nasal mask to 0.1 mg/m3 of H2SO4, the mean bronchial clearance half-time was reduced by 38% (p less than 0.02) while for 1 mg/m3, it was increased by 48% (p less than 0.03). Four donkeys exposed for 1 hour daily to 0.1 mg/m3 for six months developed clearance abnormalities which persisted for at least three months after the last exposure. The patterns of mucociliary clearance responses to H2SO4 are similar to those seen previously in humans and donkeys following exposure to cigarette smoke, a known causal factor for chronic bronchitis.