Characterization of the inflammatory reaction in the peripheral airways of cigarette smokers using immunocytochemistry

Granzyme B May Act as an Effector Molecule to Control the Inflammatory Process in COPD

Chronic obstructive pulmonary disease (COPD) is caused by smoking, but only a small proportion of smokers have disease severe enough to develop COPD. COPD is not always progressive. The question then arises as to what explains the different trajectories of COPD. The role of autoimmunity and regulatory T (Treg) cells in the pathogenesis of COPD is increasingly being recognized. Nine published studies on Treg cells in the lung tissue or bronchoalveolar lavage fluid have shown that smokers with COPD have fewer Treg cells than smokers without COPD or nonsmokers. Three studies showed a positive correlation between Treg cell count and FEV1%, suggesting an important role for Treg cells in COPD progression. Treg cells can regulate immunological responses via the granzyme B (GzmB) pathway. Immunohistochemical staining for GzmB in surgically resected lungs with centrilobular emphysema showed that the relationship between the amount of GzmB+ cells and FEV1% was comparable to that between Treg cell count and FEV1% in the COPD lung, suggesting that GzmB could be a functional marker for Treg cells. The volume fraction of GzmB+  cells in the small airways, the number of alveolar GzmB+ cells, and GzmB expression measured by enzyme-linked immunosorbent assay in the lung tissue of smokers were significantly correlated with FEV1%. These results suggest that the GzmB content in lung tissue may determine the progression of COPD by acting as an effector molecule to control inflammatory process. Interventions to augment GzmB-producing immunosuppressive cells in the early stages of COPD could help prevent or delay COPD progression.

CD19 and POU2AF1 are Potential Immune-Related Biomarkers Involved in the Emphysema of COPD: On Multiple Microarray Analysis

Purpose

Emphysema is the main cause of the progression of chronic obstructive pulmonary disease (COPD). This study aimed to identify the key genes involved in COPD-related emphysema.

Patients and Methods

GSE76925 was downloaded from Gene Expression Omnibus database. Protein–protein interaction networks of differentially expressed genes (DEGs) between control and COPD groups were constructed to identify hub genes using Cytoscape. Diagnostic performance of hub genes was evaluated using receiver operating characteristic analysis. Correlation analysis was performed to identify the key genes by analyzing the relationship between the hub genes and lung function and computed tomography (CT) indexes of emphysema. COPD patients were then divided into two groups based on the median expression of key genes and DEGs between these two groups were identified. Enrichment analysis of DEGs and correlation analysis between key genes and the infiltration of the immune cells were also analyzed. Finally, the role of key genes was evaluated in a lung tissues dataset (GSE47460) and a blood dataset (GSE76705). Additionally, the expression of key genes was validated by quantitative real-time polymerase chain reaction and immunohistochemistry.

Results

CD19 and POU2AF1 had diagnostic efficacy for COPD and were significantly correlated with lung function and CT indexes of emphysema. Enrichment and immune analyses revealed that CD19 and POU2AF1 were correlated with the B cells in COPD. These results were consistent in GSE47460. The expression of CD19 and POU2AF1 in blood was the opposite of that in lung tissues, and CD19 and POU2AF1 were both significantly upregulated in COPD lung tissues at both the mRNA and protein levels.

Conclusion

CD19 and POU2AF1 may serve as key regulators of emphysema and contribute to the progression of COPD by regulating the B-cell immunology. Targeting B cells may be a promising strategy for treating COPD.

Immunosuppressive effects of mesenchymal stem cells on lung B cell gene expression in LPS-induced acute lung injury

Background

Immune system disorders play important roles in acute lung injury (ALI), and mesenchymal stem cell (MSC) treatment can reduce inflammation during ALI. In this study, we compared the changes in lung B cells during MSC treatment.

Methods

We investigated the effects of MSCs on lung B cells in a mouse model of lipopolysaccharide (LPS)-induced ALI. MSCs were administered intratracheally 4 h after LPS. As vehicle-treated controls, mice were treated with phosphate-buffered saline (PBS) containing 2% C57BL/6 (PBS group). Histopathological changes, survival rate, inflammatory factor levels, and the number of neutrophils in bronchoalveolar lavage fluid (BALF) were determined. Single-cell RNA sequencing (scRNA-Seq) analysis was performed to evaluate the transcriptional changes in lung B cells between the PBS, LPS, and LPS/MSC groups on days 3 and 7.

Results

MSC treatment ameliorated LPS-induced ALI, as indicated by the reductions in mortality, the levels of chemokines and cytokines in BALF, and the severity of lung tissue histopathology in ALI mice. Lung B cells in the PBS group remained undifferentiated and had an inhibitory phenotype. Based on our scRNA-Seq results, the differentially expressed genes (DEGs) in lung B cells in both the PBS group and LPS group were involved in chemotaxis processes and some proinflammatory pathways. MSC treatment inhibited the expression of chemokine genes that were upregulated by LPS and were related to the recruitment of neutrophils into lung tissues. Immunoglobulin-related gene expression was decreased in lung B cells of mice treated with LPS/MSC for 7 days. The DEGs regulated by MSCs were enriched in biological processes, including humoral immune response and apoptotic signaling.

Conclusions

Lung B cells played an important role in the effects of treatment of ALI with MSCs. These observations provide new insights into the mechanisms underlying the effects of MSC treatment for ALI.

Extrapulmonary effects of temporal exposure to cigarette smoke

This study aimed to evaluate the extrapulmonary effects of exposure to cigarette smoke (CS) through the analysis of blood components and histopathological examinations of the trachea and diaphragm muscle (DM) in C57BL/6 mice. Thirty-six animals were exposed to six cigarettes per day for 5 days. The mice were divided into a control group (CG) and groups exposed to CS for 1 (CS1D), 2 (CS2D), 3 (CS3D), 4 (CS4D), and 5 (CS5D) days. The trachea, DM, and blood were collected for morphometric and biochemical analyses. In comparison with the CG, CS4D and CS5D mice showed an increased influx of inflammatory cells into the DM and trachea. Increased glycogen deposits in the tracheal tissue of CS3D mice were observed, compared with that in CG, CS1D, and CS2D mice. In the blood serum, the number of inflammatory cells and the concentration of cholesterol increased in CS1D mice, compared with the CG. Alanine aminotransferase (ALT) levels were elevated in CS5D mice, compared with those in CS3D and CS4D mice. Aspartate aminotransferase (AST) levels were elevated in CS3D and CS5D mice, compared with those in the CG. Urea levels were significantly increased in CS5D mice, compared with CS1D mice. Our results showed extrapulmonary effects of short-term exposure to CS in adult mice.

Application of Euclidean distance mapping for assessment of basement membrane thickness distribution in asthma

Abnormal thickening of the airway basement membrane is one of the hallmarks of airway remodeling in asthma. The present protocols for measuring the basement membrane involve the use of stained tissue sections and measurements of the basement membrane thickness at certain intervals, followed by the calculation of the geometric mean thickness for each airway. This report describes an automated, unbiased approach which uses color segmentation to identify structures of interest on stained sections and Euclidean distance mapping to measure the thickness distribution of airway structures. This method was applied to study the thickness distribution of the basement membrane and airway epithelium in lungs donated for research from seven nonasthmatic and eight asthmatic age- and sex-matched donors. A total of 60 airways were assessed. We report that the thickness and thickness distribution of the basement membrane and airway epithelium are increased in large and small airways of asthmatics compared with nonasthmatics. Using this method we were able to demonstrate the heterogeneity in the thickness of the basement membrane and airway epithelium within individual airways of asthmatic subjects. This new computational method enables comprehensive and objective quantification of airway structures, which can be used to quantify heterogeneity of airway remodeling in obstructive lung diseases such as asthma and chronic obstructive pulmonary disease.NEW & NOTEWORTHY The described application of Euclidean distance mapping provides an unbiased approach to study the extent and thickness distribution of changes in tissue structures. This approach will enable researchers to use computer-aided analysis of structural changes within lung tissue to understand the heterogeneity of airway remodeling in lung diseases.

Differences in regional air trapping in current smokers with normal spirometry

We investigated regional air trapping on computed tomography in current smokers with normal spirometry. It was hypothesised that presence of regional air trapping may indicate a specific manifestation of smoking-related changes.

40 current smokers, 40 patients with chronic obstructive pulmonary disease (COPD), and 40 healthy never- smokers underwent computed tomography scans. Regional air trapping was assessed on end-expiratory scans and emphysema, micronodules and bronchial wall thickening on inspiratory scans. The ratio of expiratory and inspiratory mean lung attenuation (E/I) was calculated as a measure of static (fixed) air trapping.

Regional air trapping was present in 63% of current smokers, in 45% of never smokers and in 8% of COPD patients (p<0.001). Current smokers with and without regional air trapping had E/I ratio of 0.81 and 0.91, respectively (p<0.001). Forced expiratory volume in 1 s (FEV1) was significantly higher and emphysema less frequent in current smokers with regional air trapping.

Current smokers with regional air trapping had higher FEV1 and less emphysema on computed tomography. In contrast, current smokers without regional air trapping resembled COPD. Our results highlight heterogeneity among smokers with normal spirometry and may contribute to early detection of smoking related structural changes in the lungs.

The formation and function of tertiary lymphoid follicles in chronic pulmonary inflammation

Tertiary lymphoid follicles (TLFs) can develop in the respiratory tract in response to infections or chronic inflammation. However, their functional relevance remains unclear because they are implicated in both protective and pathological responses. In contrast to homeostatic conditions, external antigens and damage to the lung tissue may drive TLF formation in inflamed lungs, and once established, the presence of pulmonary TLFs may signal the progression of chronic lung disease. This novel concept will be discussed in light of recent work in chronic obstructive pulmonary disease and how changes in the pulmonary microbiota may drive and direct TLF formation and function. We will also discuss the cellularity of TLFs at the pulmonary mucosa, with emphasis on the potential roles of lymphoid tissue inducer cells, and B- and T-cell aggregates, and will examine the function of key chemokines and cytokines including CXCL13 and interleukin-17, in the formation and maintenance of pulmonary TLFs.

Novel aspects of pathogenesis and regeneration mechanisms in COPD

Chronic obstructive pulmonary disease (COPD), a major cause of death and morbidity worldwide, is characterized by expiratory airflow limitation that is not fully reversible, deregulated chronic inflammation, and emphysematous destruction of the lungs. Despite the fact that COPD is a steadily growing global healthcare problem, the conventional therapies remain palliative, and regenerative approaches for disease management are not available yet. We aim to provide an overview of key reviews, experimental, and clinical studies addressing lung emphysema development and repair mechanisms published in the past decade. Novel aspects discussed herein include integral revision of the literature focused on lung microflora changes in COPD, autoimmune component of the disease, and environmental risk factors other than cigarette smoke. The time span of studies on COPD, including emphysema, chronic bronchitis, and asthmatic bronchitis, covers almost 200 years, and several crucial mechanisms of COPD pathogenesis are described and studied. However, we still lack the holistic understanding of COPD development and the exact picture of the time-course and interplay of the events during stable, exacerbated, corticosteroid-treated COPD states, and transitions in-between. Several generally recognized mechanisms will be discussed shortly herein, ie, unregulated inflammation, proteolysis/antiproteolysis imbalance, and destroyed repair mechanisms, while novel topics such as deviated microbiota, air pollutants-related damage, and autoimmune process within the lung tissue will be discussed more extensively. Considerable influx of new data from the clinic, in vivo and in vitro studies stimulate to search for novel concise explanation and holistic understanding of COPD nowadays.

A panoramic spectrum of complex interplay between the immune system and IL-32 during pathogenesis of various systemic infections and inflammation

Cytokines have always been of great interest due to their vast potential and participation in the progression and pathogenesis of various ailments. Interleukin-32 (IL-32) is a recently identified cytokine, whose gene is located on human chromosome 16 p13.3, with eight exons and six splice variants (IL-32α to IL-32ζ). IL-32α, the most abundant form, is secreted by different types of cells including T cells, natural killer (NK) cells, monocytes, endothelial cells and epithelial cells. It acts as a preferential mediator and effector of abnormal immune responses to multiple inflammatory and auto immune diseases including rheumatoid arthritis, chronic obstructive pulmonary disease (COPD), inflammatory bowel disease (IBD), etc. It was found to stimulate the induction of various chemokines, pro-inflammatory cytokines including IL-1β, IL-6, IL-8, TNF-α and macrophage inflammatory protein-2 (MIP-2). Hence, IL-32 mediates the crucial interplay among immune system and body cells during pathogenesis of various insults. The aim of the present effort is to summarize the role, mechanism of pathogenesis and potential therapeutic applications of IL-32 in different systemic infections and diseased conditions.

Structure, Organization, and Development of the Mucosal Immune System of the Respiratory Tract

The respiratory tract is served by a variety of lymphoid tissues, including the tonsils, adenoids, nasal-associated lymphoid tissue (NALT), and bronchus-associated lymphoid tissue (BALT), as well as the lymph nodes that drain the upper and lower respiratory tract. Each of these tissues uses unique mechanisms to acquire antigens and respond to pathogens in the local environment and supports immune responses that are tailored to protect those locations. This chapter will review the important features of NALT and BALT and define how these tissues contribute to immunity in the upper and lower respiratory tract, respectively.

Cigarette smoke-induced iBALT mediates macrophage activation in a B cell-dependent manner in COPD

Chronic obstructive pulmonary disease (COPD) is characterized by a progressive decline in lung function, caused by exposure to exogenous particles, mainly cigarette smoke (CS). COPD is initiated and perpetuated by an abnormal CS-induced inflammatory response of the lungs, involving both innate and adaptive immunity. Specifically, B cells organized in iBALT structures and macrophages accumulate in the lungs and contribute to CS-induced emphysema, but the mechanisms thereof remain unclear. Here, we demonstrate that B cell-deficient mice are significantly protected against CS-induced emphysema. Chronic CS exposure led to an increased size and number of iBALT structures, and increased lung compliance and mean linear chord length in wild-type (WT) but not in B cell-deficient mice. The increased accumulation of lung resident macrophages around iBALT and in emphysematous alveolar areas in CS-exposed WT mice coincided with upregulated MMP12 expression. In vitro coculture experiments using B cells and macrophages demonstrated that B cell-derived IL-10 drives macrophage activation and MMP12 upregulation, which could be inhibited by an anti-IL-10 antibody. In summary, B cell function in iBALT formation seems necessary for macrophage activation and tissue destruction in CS-induced emphysema and possibly provides a new target for therapeutic intervention in COPD.

The development and function of mucosal lymphoid tissues: a balancing act with micro-organisms

Mucosal surfaces are constantly exposed to environmental antigens, colonized by commensal organisms and used by pathogens as points of entry. As a result, the immune system has devoted the bulk of its resources to mucosal sites to maintain symbiosis with commensal organisms, prevent pathogen entry, and avoid unnecessary inflammatory responses to innocuous antigens. These functions are facilitated by a variety of mucosal lymphoid organs that develop during embryogenesis in the absence of microbial stimulation as well as ectopic lymphoid tissues that develop in adults following microbial exposure or inflammation. Each of these lymphoid organs samples antigens from different mucosal sites and contributes to immune homeostasis, commensal containment, and immunity to pathogens. Here we discuss the mechanisms, mostly based on mouse studies, that control the development of mucosal lymphoid organs and how the various lymphoid tissues cooperate to maintain the integrity of the mucosal barrier.

Oxidative stress-mediated iNKT-cell activation is involved in COPD pathogenesis

Chronic obstructive pulmonary disease (COPD) is a major clinical challenge mostly due to cigarette smoke (CS) exposure. Invariant natural killer T (iNKT) cells are potent immunoregulatory cells that have a crucial role in inflammation. In the current study, we investigate the role of iNKT cells in COPD pathogenesis. The frequency of activated NKT cells was found to be increased in peripheral blood of COPD patients relative to controls. In mice chronically exposed to CS, activated iNKT cells accumulated in the lungs and strongly contributed to the pathogenesis. The detrimental role of iNKT cells was confirmed in an acute model of oxidative stress, an effect that depended on interleukin (IL)-17. CS extracts directly activated mouse and human dendritic cells (DC) and airway epithelial cells (AECs) to trigger interferonγ and/or IL-17 production by iNKT cells, an effect ablated by the anti-oxidant N-acetylcystein. In mice, this treatment abrogates iNKT-cell accumulation in the lung and abolished the development of COPD. Together, activation of iNKT cells by oxidative stress in DC and AECs participates in the development of experimental COPD, a finding that might be exploited at a therapeutic level.

Chronic obstructive pulmonary disease (COPD): evaluation from clinical, immunological and bacterial pathogenesis perspectives

Chronic obstructive pulmonary disease (COPD), a disease manifested by significantly impaired airflow, afflicts ∼14.2 million cases in the United States alone with an estimated 63 million people world-wide. Although there are a number of causes, the predominant cause is excessive tobacco smoke. In fact, in China, there have been estimates of 315,000,000 people that smoke. Other less frequent causes are associated with indirect cigarette smoke, air pollutants, biomass fuels, and genetic mutations. COPD is often associated with heart disease, lung cancer, osteoporosis and conditions can worsen in patients with sudden falls. COPD also affects both innate and adaptive immune processes. Cigarette smoke increases the expression of matrix metalloproteases and proinflammatory chemokines and increases lung titers of natural killer cells and neutrophils. Yet, neutrophil reactive oxygen species (ROS) mediated by the phagocytic respiratory burst and phagocytosis is impaired by nicotine. In contrast to innate immunity in COPD, dendritic cells represent leukocytes recruited to the lung that link the innate immune responses to adaptive immune responses by activating naïve T cells through antigen presentation. The autoimmune process that is also a significant part of inflammation associated with COPD. Moreover, coupled with restricted FEV1 values, are the prevalence of patients with single or multiple infections by bacteria, viruses and fungi. Finally, we focus on one of the more problematic infectious agents, the Gram-negative opportunistic pathogenic bacterium, Pseudomonas aeruginosa. Specifically, we delve into the development of highly problematic biofilm infections that are highly refractory to conventional antibiotic therapies in COPD. We offer a non-conventional, biocidal treatment that may be effective for COPD airway infections as well as with combinations of current antibiotic regimens for more effective treatment outcomes and relief for patients with COPD.

Increased numbers of NK cells, NKT-like cells, and NK inhibitory receptors in peripheral blood of patients with chronic obstructive pulmonary disease

T cells and B cells participate in the pathogenesis of COPD. Currently, NK cells and NKT cells have gained increasing attention. In the present study, 19 COPD patients and 12 healthy nonsmokers (HNS) were recruited, and their pulmonary function was assessed. The frequencies of CD3⁺ T, CD4⁺ T, CD8⁺ T, B, NK, and NKT-like cells were determined using flow cytometry. The frequencies of spontaneous and inducible IFN-γ⁺ or CD107a⁺ NK and NKT-like cells as well as activating or inhibitory receptors were also detected. The potential association of lymphocyte subsets with disease severity was further analyzed. Significantly decreased numbers of CD3⁺ and CD4⁺ T cells, and the CD4⁺/CD8⁺ ratio, but increased numbers of CD3⁻CD56⁺ NK and CD3⁺CD56⁺ NKT-like cells were observed in COPD patients compared to HNS. The frequencies of inducible IFN-γ-secreting NK and NKT-like cells were less in COPD patients. The frequencies of CD158a and CD158b on NK cells and CD158b on NKT-like cells were greater. The frequency of CD158b⁺ NK cells was negatively correlated with FEV₁% prediction and FEV₁/FVC. Our data indicate that COPD patients have immune dysfunction, and higher frequencies of inhibitory NK cells and NKT-like cells may participate in the pathogenesis of COPD.

B-lymphocyte lineage cells and the respiratory system

Adaptive humoral immune responses in the airways are mediated by B cells and plasma cells that express highly evolved and specific receptors and produce immunoglobulins of most isotypes. In some cases, such as autoimmune diseases or inflammatory diseases caused by excessive exposure to foreign antigens, these same immune cells can cause disease by virtue of overly vigorous responses. This review discusses the generation, differentiation, signaling, activation, and recruitment pathways of B cells and plasma cells, with special emphasis on unique characteristics of subsets of these cells functioning within the respiratory system. The primary sensitization events that generate B cells responsible for effector responses throughout the airways usually occur in the upper airways, tonsils, and adenoid structures that make up the Waldeyer ring. On secondary exposure to antigen in the airways, antigen-processing dendritic cells migrate into secondary lymphoid organs, such as lymph nodes, that drain the upper and lower airways, and further B-cell expansion takes place at those sites. Antigen exposure in the upper or lower airways can also drive expansion of B-lineage cells in the airway mucosal tissue and lead to the formation of inducible lymphoid follicles or aggregates that can mediate local immunity or disease.

Expression of the atypical chemokine receptor D6 in human alveolar macrophages in COPD

BACKGROUND

D6 is an atypical chemokine receptor involved in chemokine degradation and resolution of acute inflammatory responses in mice. Emerging evidence suggests that D6 might behave differently in human chronic inflammatory conditions. We, therefore, investigated the involvement of D6 in the immune responses in COPD, a chronic inflammatory condition of the lung.

METHODS

D6 expression was quantified by immunohistochemistry in surgical resected lung specimens from 16 patients with COPD (FEV(1), 57% ± 6% predicted) and 18 control subjects with normal lung function (nine smokers and nine nonsmokers). BAL was also obtained and analyzed by flow cytometry, immunofluorescence, and molecular analysis for further assessment of D6 involvement.

RESULTS

D6 expression in the lung was mainly detected in alveolar macrophages (AMs). The percentage of D6(+) AMs was markedly increased in patients with COPD as compared with both smoker and nonsmoker control subjects (P < .0005 for both). D6 expression was detected at both transcript and protein level in AMs but not in monocyte-derived macrophages. Finally, D6 expression was positively correlated with markers of immune activation (CD8(+) T lymphocytes, IL-32, tumor necrosis factor-α, B-cell activating factor of the tumor necrosis factor family, phospho-p38 mitogen-activated protein kinase) and negatively with lung function (FEV(1), FEV(1)/FVC).

CONCLUSIONS

D6 is expressed in AMs from patients with COPD, and its expression correlates with the degree of functional impairment and markers of immune activation. Upregulation of D6 in AMs could indicate that, besides its known scavenger activity in acute inflammation, D6 may have additional roles in chronic inflammatory conditions possibly promoting immune activation.

Small airway disease in asthma and COPD: clinical implications

Asthma and COPD have a high personal, societal, and economic impact. Both diseases are characterized by airway obstruction and an inflammatory process. The inflammatory process affects the whole respiratory tract, from central to peripheral airways that are <2 mm in internal diameter, the so-called small airways. There is an increased interest in small airway disease, and some new insights have been gained about the contribution of these small airways to the clinical expression of asthma and COPD, as reviewed in this article. Newly developed devices enable drugs to target the small airways, and this may have implications for treatment of patients with asthma, particularly those not responding to large-particle inhaled corticosteroids or those with uncontrollable asthma. The first studies in COPD are promising, and results from new studies are eagerly awaited.

Involvement of endogenous hydrogen sulfide in cigarette smoke-induced changes in airway responsiveness and inflammation of rat lung

Hydrogen sulfide (H₂S), recently considered the third endogenous gaseous transmitter, may have an important role in systemic inflammation. We investigated whether endogenous H₂S may be a crucial mediator in airway responsiveness and airway inflammation in a rat model of chronic exposure to cigarette smoke (CS). Rats randomly divided into control and CS-exposed groups were treated with or without sodium hydrosulfide (NaHS, donor of H₂S) or propargylglycine (PPG, inhibitor of cystathionine-γ-lyase [CSE], an H₂S-synthesizing enzyme) for 4-month exposure. Serum H₂S level and CSE protein expression in lung tissue were higher, by 2.04- and 2.33-fold, respectively, in CS-exposed rats than in controls (P<0.05). Exogenous administration of NaHS to CS-exposed rats alleviated airway reactivity induced by acetylcholine (Ach) or potassium chloride (KCl) by 17.4% and 13.8%, respectively, decreased lung pathology score by 32.7%, inhibited IL-8 and TNF- α concentrations in lung tissue by 34.2% and 31.4%, respectively, as compared with CS-exposed rats (all P<0.05). However, blocking endogenous CSE with PPG in CS-exposed rats increased airway reactivity induced by Ach or KCl, by 24.1% and 24.5%, respectively, and aggravated lung pathology score, by 44.8%, as compared with CS-exposed rats (all P<0.01). Incubation in vitro with NaHS, 1-3 mmol/L, relaxed rat tracheal smooth muscle precontracted by Ach or KCl. However, the NaHS-induced relaxation was not blocked by glibenclamide (10⁻⁴ mol/L), L-NAME (10⁻⁴ mol/L), or ODQ (1 μmol/L) or denudation of epithelium. Endogenous H₂S may have a protective role of anti-inflammation and bronchodilation in chronic CS-induced pulmonary injury.

Bronchus-associated lymphoid tissue (BALT) structure and function

Bronchus-associated lymphoid tissue (BALT) is a constitutive mucosal lymphoid tissue adjacent to major airways in some mammalian species, including rats and rabbits, but not humans or mice. A related tissue, inducible BALT (iBALT), is an ectopic lymphoid tissue that is formed upon inflammation or infection in both mice and humans and can be found throughout the lung. Both BALT and iBALT acquire antigens from the airways and initiate local immune responses and maintain memory cells in the lungs. Here, we discuss the development and function of BALT and iBALT in the context of pulmonary immunity to infectious agents, tumors, and allergens as well as autoimmunity and inflammatory diseases of the lung.

Enhanced effector function of cytotoxic cells in the induced sputum of COPD patients

Background

We have previously shown that NK (CD56⁺CD3^-) and NKT-like (CD56⁺CD3⁺) cells are reduced in both numbers and cytotoxicity in peripheral blood. The aim of the present study was to investigate their numbers and function within induced sputum.

Methods

Induced sputum cell numbers and intracellular granzyme B and perforin were analysed by flow cytometry. Immunomagnetically selected CD56⁺ cells (NK and NKT-like cells) were used in an LDH release assay to determine cytotoxicity.

Results

The proportion of NK cells and NKT-like cells in smokers with COPD (COPD subjects) was significantly higher (12.7% and 3%, respectively) than in healthy smokers (smokers) (5.7%, p < 0.01; 1%, p < 0.001) and non-smoking healthy subjects (HNS) (4.2%, p < 0.001; 0.8%, p < 0.01). The proportions of NK cells and NKT-like cells expressing both perforin and granzyme B were also significantly higher in COPD subjects compared to smokers and HNS. CD56⁺ cells from COPD subjects were significantly more cytotoxic (1414 biological lytic activity) than those from smokers (142.5; p < 0.01) and HNS (3.8; p < 0.001) and were inversely correlated to FEV₁. (r = -0.75; p = 0.0098).

Conclusion

We have shown an increased proportion of NK and NKT-like cells in the induced sputum of COPD subjects and have demonstrated that these cells are significantly more cytotoxic in COPD subjects than smokers and HNS.

Pathogenesis of inflammation and repair in advanced COPD

Chronic obstructive pulmonary disease is characterized by an abnormal persistent inflammatory response to noxious environmental stimuli, most commonly cigarette smoke. Although cigarette smoking elicits airway inflammation in all of those who smoke, persistent inflammation and clinically significant COPD occurs in only a minority of smokers. The pathogenesis of COPD involves the recruitment and regulation of neutrophils, macrophages, and lymphocytes to the lung, as well as the induction of oxidative stress, all of which result in lung parenchymal destruction and airway remodeling. Recent research has generated a greater understanding of the mechanisms responsible for COPD development, including new concepts in T cell biology and the increasing recognition that the processes governing lung cell apoptosis are upregulated. We are also starting to understand the reasons for continued inflammation even after smoking cessation, which accelerates the rate of lung function decline in COPD. Herein we review our current knowledge of the inflammatory pathways involved in COPD pathogenesis, as well as newer concepts that have begun to unfold in recent years.

Differential lymphocyte infiltration in small airways and lung parenchyma in COPD patients

BACKGROUND

In COPD, although histological lesions at both the small airways (wall thickening and tissue remodeling) and lung parenchyma (emphysematous destruction) are definitely different, the inflammatory cells involved in both processes are the same. Our study aims to determine if these histopathological phenotypes are related to two different lymphocyte profiles.

METHODS

Distribution and cell density of CD3(+), CD4(+), CD8(+) and B lymphocytes were compared in small airways and parenchymal interstitium of 9 non-smokers, 18 smokers without COPD, 16 smokers with moderate COPD and 16 patients with very severe COPD undergoing lung transplantation. Spatial distribution of lymphocytes in periemphysematous parenchyma was also assessed.

RESULTS

CD3(+) and B cell densities were significantly higher in small airways than parenchyma interstitium of very severe COPD patients. Furthermore, CD8(+) cells were increased in the epithelium of airways of moderate COPD patients compared to non-smokers. Although CD8(+) cell density was increased in parenchyma of COPD patients, CD8(+) and B cell densities were similar when comparing periemphysematous and non-emphysematous alveolar interstitium.

CONCLUSIONS

In COPD, it is true that the small airways' wall shows a clear inflammatory pattern, with a high mononuclear infiltration and tissue remodeling. However, parenchymal interstitium shows a milder CD8(+) infiltration which, moreover, is not spatially related to emphysematous destroyed areas.

Impact of female cigarette smoking on circulating B cells in vivo: the suppressed ICOSLG, TCF3, and VCAM1 gene functional network may inhibit normal cell function

As pivotal immune guardians, B cells were found to be directly associated with the onset and development of many smoking-induced diseases. However, the in vivo molecular response of B cells underlying the female cigarette smoking remains unknown. Using the genome-wide Affymetrix HG-133A GeneChip microarray, we firstly compared the gene expression profiles of peripheral circulating B cells between 39 smoking and 40 non-smoking healthy US white women. A total of 125 differential expressed genes were identified in our study, and 75.2% of them were down-regulated in smokers. We further obtained genotypes of 702 single nucleotide polymorphisms in those promising genes and assessed their associations with smoking status. Using a novel multicriteria evaluation model integrating information from microarray and the association studies, several genes were further revealed to play important roles in the response of smoking, including ICOSLG (CD275, inducible T-cell co-stimulator ligand), TCF3 (E2A immunoglobulin enhancer binding factors E12/E47), VCAM1 (CD106, vascular cell adhesion molecule 1), CCR1 (CD191, chemokine C-C motif receptor 1) and IL13 (interleukin 13). The differential expression of ICOSLG (p = 0.0130) and TCF3 (p = 0.0125) genes between the two groups were confirmed by real-time reverse transcription PCR experiment. Our findings support the functional importance of the identified genes in response to the smoking stimulus. This is the first in vivo genome-wide expression study on B cells at today's context of high prevalence rate of smoking for women. Our results highlight the potential usage of integrated analyses for unveiling the novel pathogenesis mechanism and emphasized the significance of B cells in the etiology of smoking-induced disease.

Identification and clinical association of anti-cytokeratin 18 autoantibody in COPD

The etiology of chronic obstructive pulmonary disease (COPD) remains unclear. A mechanism involving the autoimmune reaction in the pathogenesis of COPD has been proposed but not confirmed. The aim of this study was to investigate whether serum autoantibodies against pulmonary cellular proteins are present in COPD patients and to identify their autoantigens if possible. Samples from 50 COPD patients and 42 control subjects were studied. Circulating autoantibodies were detected by Western blot. Immunoprecipitation and matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry were used to identify the autoantigens. Autoantibodies against pulmonary cellular antigens were found in the sera of COPD patients. Specifically, an autoantibody against the 45-kDa human cytokeratin 18 protein was found in 76.0% of COPD patients and 23.8% of control subjects (p<0.001). Furthermore, the cytokeratin 18 autoantibody level was positively correlated with the FEV(1) (L) (p=0.013) and FEV(1) (%pred.) (p=0.043) values observed in COPD patients. This study identified the pulmonary epithelial cytokeratin 18 protein as a COPD-associated autoantigen and found that anti-cytokeratin 18 autoantibodies were prevalent in COPD patients. Our results support the hypothesis that humoral autoimmunity may be involved in the pathogenesis of COPD.

Targeted treatment in COPD: a multi-system approach for a multi-system disease

Chronic obstructive pulmonary disease is a varied condition when examined from a number of different perspectives including factors which influence disease development, pathological process and clinical features. There may be a complex interaction between the degree by which each of these processes influences the development of COPD and the subsequent clinical phenotype with which the patient presents. The varied host response and subsequent clinical phenotype has generated much interest in recent years. It is possible that failure of treatment to impact on mortality and reverse the disease process is because of the heterogeneous nature of the condition. Identification and targeted treatment of clinical and pathological phenotypes within the broad spectrum of COPD may therefore improve outcome. This article will review previous work which has attempted to phenotype COPD and identify if specific treatment for these phenotypes has been shown to be of benefit. It will examine the work on pathological processes and clinical manifestations, both pulmonary and systemic, and will focus on pharmacological therapies.

Association of soluble intercellular adhesion molecule-1 with insulin resistance and metabolic syndrome in Taiwanese

Circulating concentrations of soluble cell adhesive molecules are useful predictors for the risk of development and progression of atherosclerosis. This study was initiated to investigate the association between soluble intercellular adhesive molecule-1 (sICAM-1) levels and traditional and emerging cardiovascular risk factors, as well as insulin resistance and metabolic syndrome, in a Taiwanese population. Six hundred nine unrelated individuals recruited during routine health examinations were enrolled for the analysis. In age- and sex-adjusted regression models, sICAM-1 levels were negatively associated with high-density lipoprotein cholesterol levels and positively associated with systolic, mean, and diastolic blood pressure; body mass index; waist circumference; waist-hip ratio; the homeostasis model assessment index; fasting serum insulin; triglyceride; and C-reactive protein levels. The sICAM-1 levels were also higher in subjects with current smoking (P = .001), diabetes mellitus (P = .004), insulin resistance (P < .001), and metabolic syndrome (P < .001). The sICAM-1 levels increased in a stepwise fashion with increasing Framingham risk score quartiles (P = .001) and with increasing number of metabolic syndrome components (P < .001). In subjects with metabolic syndrome, increased C-reactive protein levels were associated with increased sICAM-1 levels (P = .003). In stepwise linear regression models, sICAM-1 levels remained associated with current smoking, insulin resistance, and metabolic syndrome. In conclusion, our data revealed that insulin resistance and metabolic syndrome were associated with sICAM-1 levels in Taiwanese. These data provide further evidence of the mechanisms of sICAM-1 as a molecular marker for atherosclerosis.

Lymphoid follicle cells in chronic obstructive pulmonary disease overexpress the chemokine receptor CXCR3

RATIONALE

The mechanisms underlying formation of lung lymphoid follicles (LF) in chronic obstructive pulmonary disease (COPD) are unknown. The chemokine receptor CXCR3 regulates immune responses in secondary lymphoid structures elsewhere in the body and is highly expressed by Th1 lymphocytes in the airway in COPD. Because chemokine receptors control inflammatory cell homing to inflamed tissue, we reasoned that CXCR3 may contribute to LF formation in COPD.

OBJECTIVES

We assessed the expression of CXCR3 and its ligands (IP-10/CXCL10, Mig/CXCL9, and ITAC/CXCL11) by LF cells in never-smokers, smokers without COPD, and subjects with COPD.

METHODS

CXCR3, IP-10, Mig, and ITAC expression were assessed in lung sections from 46 subjects (never-smokers, smokers without COPD [S], and subjects with COPD in GOLD stages 1-4) by immunohistochemistry.

MEASUREMENTS AND MAIN RESULTS

CXCR3-expressing T cells (CD8+ or CD4+) and B cells (CD20+) were topographically distributed at the follicle periphery and center, respectively. The percentage of immunohistochemically identified CXCR3+ cells increased progressively while proceeding from S through GOLD 3-4 (P < 0.01 for GOLD 3-4 vs. S). Moreover, the number of CXCR3+ follicular cells correlated inversely with FEV(1) (r = 0.60). The CXCR3 ligands IP-10 and Mig were expressed by several cell types in and around the follicle, including CD68+ dendritic cells/ macrophages, airway epithelial cells, endothelial cells, and T and B cells.

CONCLUSIONS

These results suggest that LF form in the COPD lung by recruitment and/or retention of CXCR3-expressing T and B lymphocytes, which are attracted to the region through production of CXCR3 ligands IP-10 and Mig by lung structural and follicular cells.

Airway dimensions in bronchopulmonary dysplasia: implications for airflow obstruction

The cause of lung function abnormalities in bronchopulmonary dysplasia (BPD) is incompletely understood, even in the "new era" of this disease. Altered airway wall dimensions are important in the pathogenesis of airflow obstruction in diseases such as asthma and chronic obstructive pulmonary disease. Whether airway wall dimensions contribute to lung function abnormalities in BPD is unknown. The purpose of this study was to investigate airway wall dimensions in relation to airway size in BPD. Lung tissue of patients with BPD was obtained at autopsy, and lung tissue from children who died from sudden infant death syndrome (SIDS) served as control. Airway wall dimensions and epithelial loss were measured in 75 airways from 5 BPD patients and 176 airways from 11 SIDS patients. Repeated measures analysis of variance was used to assess the relationships between airway wall dimensions and airway size for BPD and SIDS patients. Little epithelial loss was present in the BPD patients while extensive loss was observed in some of the SIDS patients. The inner wall area, outer wall area, epithelium area and smooth muscle area were all substantially larger (all P < 0.001) in BPD than in SIDS patients. It is likely that the increased thickness of the airway wall components contributes to airflow obstruction in BPD patients.

Induced sputum and peripheral blood cell profile in chronic obstructive pulmonary disease

OBJECTIVE

To determine cell profiles, as well as to identify CD4+ and CD8+ lymphocyte subgroups, in induced sputum (IS) and peripheral venous blood (PVB) of patients with chronic obstructive pulmonary disease (COPD).

METHODS

Total cell counts and counts of individual cell types, including CD4+ and CD8+ T lymphocytes, were determined in the IS and PVB of 85 subjects (38 with COPD without exacerbation, 29 smokers without obstruction and 18 nonsmokers). Mann-Whitney and Spearman non-parametric tests were used in the statistical analysis, and values of p < 0.05 were considered statistically significant.

RESULTS

Comparing the IS of subjects with COPD to that of nonsmokers, neutrophil, eosinophil and CD8+ T lymphocyte counts were higher (respectively p = 0.005, p < 0.05 and p < 0.05), whereas the percentage of macrophages was lower (p = 0.003). There were weak linear correlations (r(2) < 0.1) between each cell type in IS and forced expiratory volume in one second (FEV1), forced vital capacity (FVC) and FEV1/FVC ratio. Eosinophil and CD8+ T lymphocyte counts were also higher in PVB (p = 0.04 and p = 0.02).

CONCLUSIONS

In patients with stable COPD, CD8+ T lymphocyte counts were higher in PVB, whereas total leukocyte counts were similar to those of the other two groups analyzed, suggesting systemic inflammatory involvement. The CD8+ T lymphocyte count in blood can be a useful marker of systemic inflammation and can help identify smokers who already present a COPD inflammatory pattern.

Cells, mediators and Toll-like receptors in COPD

Chronic obstructive pulmonary disease (COPD) is a global health problem. Being a progressive disease characterized by inflammation, it deteriorates pulmonary functioning. Research has focused on airway inflammation, oxidative stress, and remodelling of the airways. Macrophages, neutrophils and T cells are thought to be important key players. A number of new research topics received special attention in the last years. The combined use of inhaled corticosteroids and long-acting beta(2)-adrenoceptor agonists produces better control of symptoms and lung function than that of the use of either compound alone. Furthermore, collagen breakdown products might be involved in the recruitment and activation of inflammatory cells by which the process of airway remodelling becomes self-sustaining. Also, TLR (Toll-like receptor)-based signalling pathways seem to be involved in the pathogenesis of COPD. These new findings may lead to new therapeutic strategies to stop the process of inflammation and self-destruction in the airways of COPD patients.

The immunopathogenesis of chronic obstructive pulmonary disease: insights from recent research

Chronic obstructive pulmonary disease (COPD) progression is characterized by accumulation of inflammatory mucous exudates in the lumens of small airways, and thickening of their walls, which become infiltrated by innate and adaptive inflammatory immune cells. Infiltration of the airways by polymorphonuclear and mononuclear phagocytes and CD4 T cells increases with COPD stage, but the cumulative volume of the infiltrate does not change. By contrast, B cells and CD8 T cells increase in both the extent of their distribution and in accumulated volume, with organization into lymphoid follicles. This chronic lung inflammation is also associated with a tissue repair and remodeling process that determines the ultimate pathologic phenotype of COPD. Why these pathologic abnormalities progress in susceptible individuals, even after removal of the original noxious stimuli, remains mysterious. However, important clues are emerging from analysis of pathologic samples from patients with COPD and from recent discoveries in basic immunology. We consider the following relevant information: normal limitations on the innate immune system's ability to generate adaptive pulmonary immune responses and how they might be overcome by tobacco smoke exposure; the possible contribution of autoimmunity to COPD pathogenesis; and the potential roles of ongoing lymphocyte recruitment versus in situ proliferation, of persistently activated resident lung T cells, and of the newly described T helper 17 (Th17) phenotype. We propose that the severity and course of acute exacerbations of COPD reflects the success of the adaptive immune response in appropriately modulating the innate response to pathogen-related molecular patterns ("the Goldilocks hypothesis").

Autoantibodies in patients with chronic obstructive pulmonary disease

RATIONALE

Adaptive immune responses are present in patients with chronic obstructive pulmonary disease (COPD), and it has been postulated that these processes could be autoreactive.

OBJECTIVES

To ascertain if humoral autoimmunity could play a role in COPD pathogenesis.

METHODS

Circulating IgG autoantibodies were detected by immunofluorescence and immunoprecipitation. Immunohistochemistry and immunofluorescence were used to evaluate intrapulmonary IgG and complement (C3) deposition in human lung explants. Autoantibody pathogenicity was also investigated with an antibody-dependent cell-mediated cytotoxicity assay.

MEASUREMENTS AND MAIN RESULTS

The prevalence of anti-HEp-2 epithelial cell autoantibodies in 47 smokers/former smokers with COPD (GOLD stages 1-4) was greater than among 8 subjects with a smoking history but normal spirometry and 21 healthy control subjects who had never smoked (68 vs. 13 vs. 10%, respectively; P < 0.0001). Antibodies against primary pulmonary epithelial cells were found in 12 of 12 patients with COPD versus 3 of 12 never-smoked control subjects (P < 0.001). Self-antigens immunoprecipitated from 34 of 35 (97%) of COPD plasmas (vs. 0/12 never-smoked controls). Antibodies against a particular 130-kD autoantigen (n = 7) were associated with decreased body mass index (23.2 +/- 2.1 vs. 29.5 +/- 1.0 kg/m(2), P = 0.007). Intrapulmonary immune complexes were present in six of six and C3 was seen in five of six COPD lung explants, unlike zero of six and one of six normals, respectively. Cytotoxicity of pulmonary epithelial cells by allogeneic mononuclear cells also increased 46% after incubation with COPD plasmas (n = 10), compared with identical treatments with eight normal specimens (P = 0.03).

CONCLUSIONS

IgG autoantibodies with avidity for pulmonary epithelium, and the potential to mediate cytotoxicity, are prevalent in patients with COPD. Autoreactive adaptive immune responses may be important in the etiology of this disease.

Airway biomarkers of the oxidant burden in asthma and chronic obstructive pulmonary disease: current and future perspectives

The pathogenesis of asthma and chronic obstructive pulmonary disease (COPD) has been claimed to be attributable to increased systemic and local oxidative stress. Detection of the oxidant burden and evaluation of their progression and phenotypes by oxidant biomarkers have proved challenging and difficult. A large number of asthmatics are cigarette smokers and smoke itself contains oxidants complicating further the use of oxidant biomarkers. One of the most widely used oxidant markers in asthma is exhaled nitric oxide (NO), which plays an important role in the pathogenesis of asthma and disease monitoring. Another oxidant marker that has been widely investigated in COPD is 8-isoprostane, but it is probably not capable of differentiating asthma from COPD, or even sensitive in the early assessment of these diseases. None of the current biomarkers have been shown to be better than exhaled NO in asthma. There is a need to identify new biomarkers for obstructive airway diseases, especially their differential diagnosis. A comprehensive evaluation of oxidant markers and their combinations will be presented in this review. In brief, it seems that additional analyses utilizing powerful tools such as genomics, metabolomics, lipidomics, and proteomics will be required to improve the specificity and sensitivity of the next generation of biomarkers.

Pathogenesis of chronic obstructive pulmonary disease

The pathogenesis of chronic obstructive pulmonary disease (COPD) encompasses a number of injurious processes, including an abnormal inflammatory response in the lungs to inhaled particles and gases. Other processes, such as failure to resolve inflammation, abnormal cell repair, apoptosis, abnormal cellular maintenance programs, extracellular matrix destruction (protease/antiprotease imbalance), and oxidative stress (oxidant/antioxidant imbalance) also have a role. The inflammatory responses to the inhalation of active and passive tobacco smoke and urban and rural air pollution are modified by genetic and epigenetic factors. The subsequent chronic inflammatory responses lead to mucus hypersecretion, airway remodeling, and alveolar destruction. This article provides an update on the cellular and molecular mechanisms of these processes in the pathogenesis of COPD.

T lymphocyte subset profile and serum alpha-1-antitrypsin in pathogenesis of chronic obstructive pulmonary disease

Chronic obstructive pulmonary disease (COPD) is an inflammatory disorder characterized by the presence of non-fully reversible airflow limitation. The study was undertaken to investigate the involvement of alpha-1-antitrypsin (alpha(1)AT) and T lymphocyte subsets in the pathogenesis of COPD. Blood samples of 50 subjects, including 25 healthy volunteers and 25 patients with COPD, were analysed. Serum trypsin inhibitory capacity (STIC) was determined by enzymatic assay. CD4(+) and CD8(+) T lymphocytes were enumerated in heparinized blood using a fluorescence activated cell sorter counter. The STIC in COPD patients was found to be decreased significantly than in controls (P < 0.01). In COPD patients with lower expression levels of alpha(1)AT, a highly significant decrease in the number of CD4(+) T lymphocytes (P < 0.0009) and CD4/CD8 ratio was observed compared with control subjects (P < 0.008). The mean +/- standard error of CD8(+) lymphocytes was found to be little different (only marginally decreased) in COPD patients compared to healthy controls; however, an alteration in the individual count of CD8(+) lymphocytes cells was observed in COPD patients. Using linear regression analysis, a negative correlation was observed between STIC and CD4(+) lymphocytes and CD8(+) lymphocytes (r = -0.40, P < 0.04; r = -0.42, P < 0.03, respectively) in COPD patients. An alteration in alpha(1)AT and T lymphocyte subsets in COPD patients suggested that interplay of these factors may be responsible for the progression of COPD.

Current concepts in mechanisms of emphysema

Over the last 10 years, there has been a remarkable degree of progress in our understanding of the pathophysiological mechanisms involved in the genesis of emphysema. This review attempts to summarize these data.

The association between small airway obstruction and emphysema phenotypes in COPD

BACKGROUND

Airflow limitation in COPD is due to a variable combination of small airway obstruction and centrilobular emphysema (CLE) and/or panlobular emphysema (PLE), but the relationship between these three different phenotypes is poorly understood. This study compares the severity of small airway obstruction in both forms of emphysema and determines its relationship with FEV(1).

METHODS

We compared the lung histology of nonsmoking control subjects without emphysema (n = 10) to that of patients with CLE (n = 30) and PLE with (n = 8) and without alpha(1)-antitrypsin (AAT) deficiency (n = 11). The degree of airspace enlargement was measured using the mean interalveolar wall distance (IAWD) [mean linear intercept, Lm], and the evenness of airspace destruction was assessed by the coefficient of variation (CV) of the IAWD. The severity of small airway obstruction was determined by dividing total wall area by the length of the basement membrane to obtain wall thickness.

RESULTS

Lm was greater in all three subgroups of emphysema than in control subjects, and in AAT deficiency than in PLE or CLE. The CV of IAWD was greater in AAT deficiency and CLE than in control subjects and in CLE than in AAT deficiency or PLE. Although small airway wall thickness was greater in CLE and PLE with AAT deficiency than in control subjects, the association between wall thickness and both Lm and FEV(1) was observed only in CLE.

CONCLUSIONS

Small airway wall thickening occurs in CLE and PLE with AAT deficiency but is more closely associated with degree of emphysema and airflow limitation in CLE.

The neutrophil in chronic obstructive pulmonary disease

Chronic obstructive pulmonary disease (COPD) is a complex, heterogeneous collection of conditions characterized by irreversible expiratory airflow limitation. The disease involves a multifaceted progressive inflammatory process leading to the development of mucus hypersecretion, tissue destruction, and disruption to the normal repair and defense mechanisms. The result is increased resistance to airflow in small conducting airways, change in lung compliance, and the premature collapse of airways during expiration that leads to air trapping. Neutrophils are necessary in healthy lungs; they are an important component of innate immunity, protecting healthy individuals against infection. However, in COPD, they play a role in the destructive processes that characterize the disease. They can be responsible for significant damage when they accumulate at sites of inflammation and are harmful to healthy tissue. In recent years, increased understanding of the role of neutrophils has led to improved knowledge of the pathogenesis of COPD and allowed new avenues of treatment to be investigated.

Abnormalities of the bronchial arteries in asthma

STUDY OBJECTIVES

The bronchial arteries supply systemic blood to the airways, tracheobronchial lymph nodes, and nerves. Their structure has not been studied in patients with asthma.

DESIGN

Case-control study of pathologic changes of bronchial arteries in asthma.

PARTICIPANTS AND METHODS

Postmortem lungs were examined from three case groups: (1) fatal asthma (n = 12), death due to asthma; (2) nonfatal asthma (n = 12), asthmatic and death due to nonrespiratory causes; and (3) nonasthmatic control subjects (n = 12), no history of asthma and death due to nonrespiratory causes. In bronchial arteries with outer diameters of 0.1 to 1.0 mm, the areas of lumen, intima, and media were measured and compared between case groups.

RESULTS

There were no significant differences in artery size (outer diameter) or in medial area between the three groups. In the two asthma groups, the intimal area was increased (p < 0.05), with a corresponding decrease in luminal area compared with the control group. There was a significant effect of gender, age, and smoking on intimal area. In the asthma cases, the area of bronchial artery intima was related to duration of asthma (p < 0.05), and this increase was associated with smooth muscle proliferation, reduplication, and calcification of the elastica, but not with inflammatory cell infiltration.

CONCLUSIONS

While the pathophysiologic significance of these changes is uncertain, the relation to duration of asthma, age, and smoking suggests a secondary response to chronic airway disease.

Morphologic alteration induced by short-term smoke exposure in rats

BACKGROUND

It is a well-established fact that cigarette smoking causes degenerative, inflammatory, and respiratory diseases in humans. Because many factors such as air pollution and harsh working conditions can easily be eliminated in animal studies, we conducted this study to identify the effect of tobacco on rat trachea.

METHODS

24 male Wistar rats were divided randomly into an experimental and a control group. The experimental group of rats was exposed to cigarette smoke for 2 h each day over a duration of 60 consecutive days and the control group was treated in an identical fashion yet exposed only to room air. A morphometric study was performed on tracheal specimens taken from 22 rats (10 smoke-exposed rats and 12 control rats).

RESULTS

Our results show that many of the morphological changes of the tracheal epithelium were found in the experimental group and significant quantitative differences were observed between the two groups. Loss of cilia, basal cell hyperplasia, goblet cell hyperplasia and an increased number of subepithelial inflammatory cells were observed by light microscopic examination of the trachea of experimental rats. We found very high levels of plasma thiocyanate after exposure to smoke in the experimental group, but no increase in the control group.

CONCLUSIONS

The oxidants contained tobacco which could play an important role in the development of these structural and functional abnormalities in the trachea after smoke exposure. In addition, smoking can recruit inflammatory cells to the trachea.

Differential distribution of inflammatory cells in large and small airways in smokers

BACKGROUND

Smoking induces structural changes in the airways, and is considered a major factor in the development of airflow obstruction in chronic obstructive pulmonary disease. However, differences in inflammatory cell distribution between large airways (LA) and small airways (SA) have not been systematically explored in smokers.

HYPOTHESIS

The content of cells infiltrating the airway wall differs between LA and SA.

AIMS

To compare the content of neutrophils, macrophages, lymphocytes and mast cells infiltrating LA and SA in smokers who underwent surgery for lung cancer.

METHODS

Lung tissue from 15 smokers was analysed. Inflammatory cells in the lamina propria were identified by immunohistochemical analysis, quantified by digital image analysis and expressed as number of cells per surface area.

RESULTS

The number of neutrophils infiltrating the lamina propria of SA (median 225.3 cells/mm(2)) was higher than that in the lamina propria of LA (median 60.2 cells/mm(2); p<0.001). Similar results were observed for mast cells: 313.3 and 133.7 cells/mm(2) in the SA and LA, respectively (p<0.001). In contrast, the number of CD4 cells was higher in LA compared with SA (median 217.8 vs 80.5 cells/mm(2); p = 0.042).

CONCLUSIONS

These findings indicate a non-uniform distribution of neutrophils and mast cells throughout the bronchial tree, and suggest that these cells may be involved in the development of smoking-related peripheral lung injury.

Smoking and Asthma

Smoking may influence the type of airway inflammation observed in asthma and its response to therapy. More studies are needed on how smoking-induced changes in lung function/structure and airway inflammation may result in a change in clinical expression. We compared clinical, physiologic, radiologic, and airway inflammatory features of 22 smoking asthma patients (cigarette smoking history, 14.0 +/- 7.6 pack-years [mean +/- SD]) and 27 nonsmoking asthma patients. Mean age/duration of asthma of smoking and nonsmoking asthma patients were 31 years/14 years and 29 years/17 years, respectively. Quality of life, FEV(1), bronchodilator response, perception of bronchoconstriction, and methacholine responsiveness were similar in the two groups. Compared to nonsmoking asthma patients, smokers had more respiratory symptoms, a lower mean forced expiratory flow at 25 to 75% of FVC, FEV(1)/FVC ratio, and lung diffusion capacity, and a higher functional residual capacity. Induced-sputum neutrophil and bronchial cell counts were higher and exhaled breath condensate pH was more acidic in smoking asthma patients. On high-resolution CT, airway and parenchymal abnormalities were more common in smoking asthma patients than in nonsmokers. In conclusion, compared with nonsmoking asthma patients, smoking asthma patients have features similar to what could be found in early stages of COPD.

Pathogenesis of chronic obstructive pulmonary disease

The current paradigm for the pathogenesis of chronic obstructive pulmonary disease is that chronic airflow limitation results from an abnormal inflammatory response to inhaled particles and gases in the lung. Airspace inflammation appears to be different in susceptible smokers and involves a predominance of CD8+ T lymphocytes, neutrophils, and macrophages. Studies have characterized inflammation in the peripheral airspaces in different stages of disease severity. Two other processes have received considerable research attention. The first is a protease-antiprotease imbalance, which has been linked to the pathogenesis of emphysema. However, the hypothesis of an increased protease burden associated with functional inhibition of antiproteases has been difficult to prove and is now considered an oversimplification. The second process, oxidative stress, has a role in many of the pathogenic processes of chronic obstructive pulmonary disease and may be one mechanism that enhances the inflammatory response. In addition, it has been proposed that the development of emphysema may involve alveolar cell loss through apoptosis. This mechanism may involve the vascular endothelial growth factor pathway and oxidative stress.