Smoking and interleukin-1 activity released from human alveolar macrophages in healthy subjects

Cigarette Smoke Exposure Inhibits Early Phase of Antibody Production through Inhibition of Immune Functions in Alveolar Macrophage

Background::

Cigarette smoke (CS) is inhaled into the lung. Alveolar macrophage (AM) is known to play an important role in the lung immune system. However, the relationship between AM functions and antibody production by CS is not fully investigated.

Objective::

Therefore, we investigated the effects of AM from CS exposed mice on antibody production. Mice were exposed to 20 cigarettes/day for 10 days. AM were obtained by broncho-alveolar lavage. Antibody production was analyzed by plaque-forming cell assay using seep red blood cell (SRBC) as antigen.

Methods::

B cell proliferation was analyzed by 3H-thymidine incorporation. Phagocytic activity using fluorescein isothiocyanate-labeled SRBC and expressions of surface antigens on AM were analyzed by flow cytometry. Cytokines and NF-κB mRNA expressions of AM were analyzed by RTPCR.

Results and Discussion:

Antibody production was decreased at the induction phase, but not at the expression phase by AM from smoked mice (SM) compared with non-smoked mice (NSM). B cell proliferation was decreased by cigarette extracts dose-dependently. Phagocytic activity of AM was decreased in SM compared with NSM. Expression of surface antigens on AM was decreased in SM compared with NSM. Cytokines or NF-κB mRNA expressions of AM were decreased in SM compared with NSM.

Conclusion::

These results suggest that the inhibition of antibody production by cigarette smoking is caused by the inhibition of phagocytosis and expressions of surface antigens associated with antigen presentation. Such inhibition of AM functions may increase the risk of bacterial and virus infections.

Are healthy smokers really healthy?

Cigarette smoke contains more than 4500 chemicals which have toxic, mutagenic and carcinogenic effects. Strong evidences have shown that current smokers take a significantly higher risk of cardiovascular diseases, chronic obstructive pulmonary disease (COPD) and lung cancer than nonsmokers. However, less attention has been paid to the smoking induced abnormalities in the individuals defined as healthy smokers who are normal with spirometry, radiographic images, routine physical exam and categorized as healthy control group in many researches. Actually, ‘healthy smokers’ are not healthy. This narrative review focuses on the smoking related pathophysiologic changes mainly in the respiratory system of healthy smokers, including inflammation and immune changes, genetic alterations, structural changes and pulmonary dysfunction.

Synergistic increase of oxidative stress and tumor markers in PAH-exposed workers

In this study, we investigated oxidative stress and tumor marker levels of polycyclic aromatic hydrocarbons (PAHs) in 136 coke oven workers and in 60 control subjects, and evaluated the correlation between oxidative stress and tumor marker levels. Questionnaires on basic demographic information were also administered. Significant differences in employment time and percentages of alcohol drinkers were observed between the control and exposed groups. PAH exposure was assessed using urinary 1-hydroxy-pyrene (1-OHP) levels and was found to be significantly higher in workers than in the controls. Significant differences (P<0.001) of MDA, GST, LDH, NSE, Cyfra21-1, and of SCC and TNF-a (P<0.0001 and P<0.05, P<0.001, respectively) levels were observed among controls and coke-oven workers, except for bottom coke oven workers. Associations between age and risk of increased TNF-a, smoking and increased GST activities, and drinking with increased MDA concentrations, were marginal (P=0.055, P=0.048, P=0.057, respectively). The association between smoking with MDA (P=0.004), NSE (P=0.005), SCC (P=0.004) and TNF-a (P<0.001), and drinking with TNF-a levels was significant (P=0.012). In addition, a significant positive correlation between oxidative stress and tumor markers was found in the present study. These results suggest that a synergistic increase of oxidative stress and tumor markers induced by PAHs may play a role in toxic responses for PAHs in coke oven workers.

Interleukin-1 as a common denominator from autoinflammatory to autoimmune disorders: premises, perils, and perspectives

A complex web of dynamic relationships between innate and adaptive immunity is now evident for many autoinflammatory and autoimmune disorders, the first deriving from abnormal activation of innate immune system without any conventional danger triggers and the latter from self-/non-self-discrimination loss of tolerance, and systemic inflammation. Due to clinical and pathophysiologic similarities giving a crucial role to the multifunctional cytokine interleukin-1, the concept of autoinflammation has been expanded to include nonhereditary collagen-like diseases, idiopathic inflammatory diseases, and metabolic diseases. As more patients are reported to have clinical features of autoinflammation and autoimmunity, the boundary between these two pathologic ends is becoming blurred. An overview of monogenic autoinflammatory disorders, PFAPA syndrome, rheumatoid arthritis, type 2 diabetes mellitus, uveitis, pericarditis, Behçet's disease, gout, Sjögren's syndrome, interstitial lung diseases, and Still's disease is presented to highlight the fundamental points that interleukin-1 displays in the cryptic interplay between innate and adaptive immune systems.

Signal transduction pathways linking the activation of alveolar macrophages with the recruitment of neutrophils to lungs in chronic obstructive pulmonary disease

Chronic obstructive pulmonary disease (COPD) is a major and increasing global health problem. It is predicted by the World Health Organization to become the third most common cause of death and the fifth most common cause of disability in the world by 2020. COPD is a complex inflammatory disease involving several types of inflammatory cells and multiple inflammatory mediators. Although abnormal numbers of inflammatory cells such as macrophages, dendritic cells, neutrophils, and T lymphocytes have been documented in COPD, the relationship between these cell types and the sequence of their appearance and persistence is largely unknown. Alveolar macrophages have been identified as one of the major cell types that plays a key role in orchestrating the inflammatory events associated with the pathophysiology of COPD. One of the major functions of macrophages is the secretion of chemotactic factors and this function is markedly increased on exposure to cigarette smoke (CS). This enhanced release of chemoattractants results in increased lung neutrophil infiltration, which is thought to be a key event in the development of COPD. The molecular basis for this amplified inflammatory response is not very clear, but it could be due to an alteration in signal transduction pathways within the macrophage. Based on existing literature, an attempt has been made to create a comprehensive review of the signal transduction pathways that link the activation of macrophages with the increased recruitment of neutrophils into the airways. Some of the major stimuli that activate macrophages and cause them to secrete chemotactic factors have been identified as CS, wood smoke, ozone, bacterial endotoxin, and proinflammatory cytokines such as interleukin (IL)-1beta and tumor necrosis factor (TNF)-alpha. These stimuli seem to activate mainly redox-sensitive transcription factors such as nuclear factor (NF)-kappa B and activator protein (AP)-1, both of which play a major role in the synthesis and secretion of chemotactic factors such as IL-8 and leukotriene B(4) (LTB(4)). The pathways involved in the synthesis and secretion of other factors such as macrophage chemotactic protein-1 (MCP-1) and growth-related oncogene-alpha (Gro-alpha) have also been reviewed.

Interaction between interleukin-1beta -31T/C gene polymorphism and drinking and smoking habits on the risk of hepatocellular carcinoma among Japanese

The risk of hepatocellular carcinoma (HCC) increases with the severity of hepatic inflammation. Interleukin (IL)-1beta and tumor necrosis factor (TNF)-alpha are proinflammatory cytokines with multiple biological effects and may play essential roles in inflammation-linked tumor development. We conducted a case-control study including 209 incident HCC cases and two control groups (275 hospital controls and 381 patients with chronic liver disease [CLD] without HCC) to investigate whether IL-1B and TNF-A gene polymorphisms influence HCC susceptibility with any interaction with alcohol and tobacco. By comparing HCC cases with CLD patients, we found that IL-1B -31T/C polymorphism was associated with HCC risk among never drinkers and current smokers; adjusted odds ratios (and 95% confidence intervals) for C/T and T/T genotypes compared with C/C genotype were 1.70 (0.76-3.77) and 2.46 (1.05-5.76) (P trend=0.03), respectively, among never drinkers, and 1.53 (0.60-3.99) and 2.54 (0.81-7.95) (P trend=0.11), respectively, among current smokers. Similarly, HCC risk associated with heavy alcohol intake and current smoking differed by this polymorphism among CLD patients. IL-1B -31T/C polymorphism may modify HCC risk in relation to alcohol intake or smoking.

Decreased level of vascular endothelial growth factor in bronchoalveolar lavage fluid of normal smokers and patients with pulmonary fibrosis

Vascular endothelial growth factor (VEGF) plays multifunctional roles in both the development of vasculature and the maintenance of vascular function. A decrease in VEGF reduces angiogenesis and induces apoptosis of vascular endothelial cells. Inhibition of the VEGF receptor causes endothelial cell apoptosis and emphysema. We postulated that VEGF concentrations might be reduced in patients with chronic lung diseases. The level of VEGF was evaluated by enzyme-liked immunosorbent assay in bronchoalveolar lavage fluid (BALF) from normal smokers, nonsmoking volunteers, idiopathic pulmonary fibrosis, pulmonary fibrosis associated with a connective tissue disease, and sarcoidosis. The isoforms of VEGF in BALF were determined by high-performance liquid chromatography. VEGF in nonsmoking volunteers was detectable at a high concentration. In contrast, VEGF in most of the normal smokers was below the detectable limit. The VEGF found in nonsmoking volunteers BALF was VEGF165. VEGF was significantly decreased in idiopathic pulmonary fibrosis, pulmonary fibrosis associated with a connective tissue disease, and sarcoidosis compared with nonsmoking volunteers. The smoking patients showed a further decrease in VEGF. These data suggest that the decrease in VEGF in smokers and patients with chronic lung diseases may reduce angiogenesis and induce apoptosis of vascular endothelial cells.

Differential inhibition of inflammatory cytokine release from cultured alveolar macrophages from smokers and non-smokers by NO2

Human alveolar macrophages (AMs) obtained from smokers and non-smokers by bronchoalveolar lavage (BAL) were subjected to various concentrations of NO2 in an inverted monolayer exposure model. Culture supernatants were collected 4 h after the exposure and assayed for secreted TNF-alpha, IL-1 beta, IL-8 and MIP-1 alpha. The steady state levels of the mRNAs for these cytokines were also analysed in the cells. The adherence of BAL cells to plastic prior to exposure to the gas elevated the steady state mRNA levels of all four cytokines tested in smoker's cells and that of TNF-alpha and IL-1 beta, but not IL-8 (MIP-1 alpha not tested), in non-smoker's cells. Interestingly, adherent cells from non-smokers released circa 15-, 3-, 1.5- and 3-fold the amounts of IL-1 beta, IL-8, TNF-alpha and MIP-1 alpha, respectively, than smoker's cells during control incubation or exposure to air. A 20 min exposure to NO2 (5 or 20 p.p.m.) did not increase the secretion of any of the cytokines from either cell type. In contrast, NO2 caused a concentration-dependent inhibition of the secretion of all cytokines except IL-1 beta from smoker's cells. Additionally, NO2 greatly diminished the release of all cytokines in response to further treatment with lipopolysaccharide (LPS). In contrast, only the secretion of TNF-alpha from non-smoker's cells was inhibited by the gas in a concentration-dependent manner, whilst LPS-induced secretion of the cytokines was not affected by the gas. The steady state levels of the respective mRNAs for each of the cytokines were not significantly affected in smoker's cells by exposure to NO2, except for a negative, dose-dependent trend in the case of TNF-alpha. Nitrogen dioxide also failed to elevate the levels of the mRNAs in non-smoker's cells but, again, tended to diminish the levels, particularly of IL-1 beta mRNA. However, exposure to the gas inhibited LPS-induced accumulation of cytokine mRNAs in smoker's cells only. The data suggest that macrophage-derived cytokine mediators of the sepsis response may not play a role in the generation of NO2-induced inflammation in the human lung. Conversely, the gas seems to non-specifically inhibit the release and/or production of cytokines, particularly from smoker's cells, at the post-transcriptional level, and impairs the ability of the cells to increase the transcription and release of the cytokines in response to bacterial LPS. The fact that NO2 seriously impaired the already diminished capacity of smoker's cells to release several important pro-inflammatory cytokines, both under control conditions and in response to LPS, strongly suggest that the inhalation of NO2 in cigarette smoke may contribute to impairing host defence against infection in the lung.

Significance of IL-1beta and IL-1 receptor antagonist (IL-1Ra) in bronchoalveolar lavage fluid (BALF) in patients with diffuse panbronchiolitis (DPB)

We evaluated the effect of erythromycin therapy on pulmonary function tests and the airway inflammatory response of patients with DPB. The number of neutrophils in BALF obtained from DPB patients was significantly higher than that of healthy volunteers. Treatment with erythromycin (600 mg/day for 12.9+/-9.5 months (mean +/- s.d.)) significantly reduced the total number of cells and neutrophils in the airway, and significantly improved pulmonary function tests. The levels of IL-1beta and IL-8 were significantly higher in DPB compared with healthy volunteers (P<0.05, P<0.05, respectively). IL-1Ra in patients is considered to have a weak inhibitory activity for IL-1beta, with approximately five-fold concentration of IL-1beta compared with that in healthy volunteers (approx. nine-fold concentration of IL-1beta). Erythromycin therapy significantly reduced these cytokines to levels comparable to those of healthy volunteers, and produced a trend toward reduction in the level of IL-1Ra in BALF. The level of IL-1beta correlated significantly with the concentration of neutrophils in BALF (r=0.72, P<0.01), as well as with the level of IL-1Ra (r=0.688, P<0.05) and IL-8 (r=0.653, P<0.05). A nearly significant or significant correlation was observed between the concentration of neutrophils and levels of IL-1Ra or IL-8 in BALF (r=0.526, P=0.053 or r=0.776, P<0.01, respectively). There was also a significant relationship between FEV(1) and the concentration of neutrophils in BALF (r=0.524, P<0.05). Our results suggest that the relative amounts of IL-1beta and IL-1Ra or IL-8 may contribute, at least in part, to the neutrophil-mediated chronic airway inflammation in patients with chronic airway disease, and long-term erythromycin therapy may down-regulate the vigorous cycle between the cytokine network and neutrophil accumulation, with resultant reduction of neutrophil-mediated inflammatory response.

Acute effects of smoking and high experimental exposure to environmental tobacco smoke (ETS) on the immune system

Controversial results have been published on the immune response to cigarette smoking while the effects of exposure to environmental tobacco smoke (ETS) have not yet been reported. In a controlled study, acute effects of smoking and of a high environmental exposure to ETS on immunological parameters have been investigated. The study consisted of four experimental days, two control and two exposure days. On control days, 1 and 3, smokers (n = 5) and nonsmokers (n = 5) sat in an unventilated 45 m3 room for 8 h. On the exposure days, 2 and 4, each of the smokers smoked 24 cigarettes in 8 h, while the nonsmokers were exposed to the ETS generated by the smoking volunteers. Blood was drawn before and after each exposure session on all four experimental days for dosimetry of tobacco smoke exposure and determination of the immune response. Flow cytometry using monoclonal antibodies was used to determine CD3+ cells (whole T cells), CD19+ cells (B lymphocytes), CD16+ and CD56+ cells (natural killer cells), CD4+ cells (T-helper cells), CD8+ cells (T-suppressor cells), the CD4+/CD8+ (helper/suppressor ratio), and Fc receptors on granulocytes. Serum was analyzed for soluble CD14 receptors (sCD14), interleukin 1, interleukin 6 and prostaglandin E2 (PGE2). Functional stimulation assays were performed to determine the basal and induced level of reactive oxygen intermediate (ROI) production by polymorphic neutrophils. Exposure to tobacco smoke in both groups was confirmed by dosimetry of carboxyhemoglobin, plasma nicotine, and cotinine levels. In comparison to nonsmokers, smokers had elevated granulocyte cell counts, increased CD16+ and CD56+ cell levels and decreased CD3+ and CD19+ levels. Acute smoking, but not exposure to ETS, resulted in a slight decrease in the number of CD19+ cells and an increase in the number of granulocytes; the latter was restricted to one subject. Acute smoking and exposure to high experimental concentrations of ETS resulted in a slight increase in CD16+ and CD56+ cells. None of the changes determined in immunological parameters after either acute smoking or exposure to ETS reached statistical significance. Serum sCD14, cytokine and PGE2, functional stimulation of in vitro ROI production, and changes in Fc receptors were not affected by acute smoking or exposure to ETS. Although no clear guidelines exist to assess immunotoxicity in man, our data do not favor immunosuppression and the possibility of increased risk of infection in nonsmokers exposed to ETS under real-life conditions.

Interrelations between interleukin-6, interleukin-1 beta, plasma C-reactive protein values, and in vitro C-reactive protein generation in patients with inflammatory bowel disease

Acute phase proteins are released from the liver in response to cytokines, and measurement of serum concentrations offers a valuable means of assessing inflammatory bowel disease. C-reactive protein (CRP) is a participating prominent component of the acute phase response in active Crohn's disease. This study aimed at determining the comparative role of the cytokines interleukin-1 beta (IL-1 beta) and interleukin-6 (IL-6), in driving CRP production in inflammatory bowel disease, and to test the hypothesis that there is a difference in the profile of cytokines generated in these two conditions. Serum CRP, the release of the cytokines IL-1 beta and IL-6 from monocytes, and the ability of monocyte conditioned medium to stimulate CRP synthesis by hepatocytes in an in vitro system was measured in patients with ulcerative colitis and Crohn's disease. Monocytes from patients with Crohn's disease produced more 1L beta-1 than monocytes from patients with ulcerative colitis or normal controls. There was no increased tendency for monocytes from Crohn's disease patients to produce more 1L-6, so the greater circulating values of IL-6 reported by a number of authors in Crohn's disease may reflect the participation of a larger number of cells of the monocyte-macrophage series, or production of IL-6 by other cell types. Correlation of cytokine production by monocytes with in vitro CRP release from cultured hepatocytes in response to monocyte conditioned medium showed that, in that system, IL-1 beta was the stronger stimulus to CRP production. Some of the differences in the inflammatory processes of ulcerative colitis and Crohn's disease may reflect differences in the amount of IL-1beta and IL-6 generated from macrophages and monocytes.

Relative release of interleukin-1 beta and interleukin-1 receptor antagonist by alveolar macrophages. A study in asbestos-induced lung disease, sarcoidosis, and idiopathic pulmonary fibrosis

We examined the influence of untreated interstitial lung disease (ILD) on the in vitro release of interleukin-1 beta (IL-1 beta) and interleukin-1 receptor antagonist (IL-Ira) from alveolar macrophages (AM); AM were harvested from normal volunteers, ILD patients, and patients with asbestos-related pleural disease but no ILD. AM were cultured for 24 h and assays for IL-1 beta and IL-1ra were done using sensitive and specific enzyme-linked immunosorbent assay. A greater amount of IL-1 beta was detected in AM supernatants from asbestosis, sarcoidosis, and IPF patients than in those from normal subjects. The IL-1 beta:IL-1ra ratio (IL-1 beta activity index [IL-1AI]) was significantly lower in supernatants of normal macrophages compared with macrophage supernatants from individuals with ILD. The IL-1AI correlated with bronchoalveolar lavage cellularity, a marker of disease activity. Current smoking was associated with lower IL-1 beta and IL-1ra release in ILD. The IL-1AI is a convenient method for comparison of IL-1 beta activity between patient populations.

Characterization of IL-1 inhibitory factor released from human alveolar macrophages as IL-1 receptor antagonist

IL-1 possesses pleiotropic properties on various cells and its activity may be stringently regulated in several ways. We have previously reported that both IL-1 and its inhibitory factor are concomitantly released from alveolar macrophages in both healthy subjects and patients with chronic inflammatory lung diseases. An increase in IL-1 activities and a decrease in inhibitory activities are characteristics found in both healthy smokers and patients with interstitial lung diseases. In this study, we further examined the biological properties of IL-1 inhibitory factor. The inhibitor exhibited a dose-dependent specific inhibition of an augmentation by IL-1 of PHA-induced murine thymocyte proliferation, while no inhibition of the augmentation by IL-2, IL-4, IL-6, or tumour necrosis factor (TNF) was found. 125I-labelled IL-1 alpha binding on PHA-stimulated murine thymocytes revealed two types of IL-1 binding sites, 44 sites/cell with a Kd of 2.7 x 10(-10) M and 230 sites/cell with a Kd of 2.5 x 10(-9) M. Alveolar macrophage culture supernatants blocked the binding of labelled IL-1 to the IL-1 receptor in a dose-dependent fashion. Scatchard plot analysis revealed that the inhibitory factor in the supernatants blocked the binding competitively. These results indicate that alveolar macrophages produce a specific IL-1 inhibitory factor, functioning as an IL-1 receptor antagonist.

Recoveries of phosphatidylcholine and alveolar macrophages in lung lavage from healthy light smokers

Twenty-one healthy volunteers, 11 light smokers and 10 non-smokers, were studied by broncho-alveolar lavage. The levels of the phosphatidylcholine (PC) in broncho-alveolar lavage were measured and used as an index of surfactant. The PC levels in broncho-alveolar lavage obtained from the smokers were significantly lower than in lavage fluid from the non-smokers. There was an inverse correlation between PC levels and cumulated tobacco smoke exposure, as estimated by the number of pack-years, and to current smoking habits as estimated by the number of cigarettes smoked per day. The number of alveolar macrophages was significantly higher in broncho-alveolar lavage obtained from smokers, and there was a significant inverse correlation between PC levels and numbers of alveolar macrophages in the lavage fluids. The potential role of alveolar macrophages in the elimination of surfactant lipids is discussed.

Reduction of the proteolytic activity of neutrophils by exposure to cigarette smoke in vitro

Human peripheral blood neutrophils were exposed in vitro, in a tonometer, to two different fractions of cigarette smoke-designated particulate phase and vapor phase. The proteolytic activity of the cells following exposure was assessed by measuring their elastase release and ability to degrade fibronectin. At levels of smoke exposure that were physiologically attainable, neither smoke fraction caused an increase in elastase release or fibronectin degradation. In most experiments, fibronectin proteolysis was suppressed by smoke exposure--an effect that was reversible on treatment with phorbol myristate acetate. These data provide evidence that the proteolytic activity of neutrophils is not enhanced by a direct effect of cigarette smoke on these cells.

IL-1 and IL-1 inhibitory activity in the culture supernatants of alveolar macrophages from patients with interstitial lung diseases

Under normal conditions, the release of interleukin 1 (IL-1) and IL-1 inhibitors play a role in tissue homeostasis. We have already reported an increase in IL-1 activity and a decrease in IL-1 inhibitory activity (IHA) in the supernatants of alveolar macrophages from healthy long-term smokers as compared with healthy nonsmokers. In this study, we report an alteration in the release of IL-1 and IL-1 IHA from alveolar macrophages in patients with interstitial lung diseases (sarcoidosis and idiopathic pulmonary fibrosis [IPF]). IL-1 activity released from alveolar macrophages stimulated by lipopolysaccharide was increased in patients with active sarcoidosis (mean +/- SD, 2.52 +/- 1.33 U/ml [n = 6] vs 1.38 +/- 0.62 U/ml [n = 15] for healthy non-current smokers [HNS]; p less than 0.05). IL-1 IHA released from alveolar macrophages was significantly different among the groups examined: a decrease of IL-1 IHA occurred in patients with active sarcoidosis (61.4 +/- 19.2 [n = 6] vs 85.9 +/- 13.9 percent:HNS; p less than 0.05) and IPF (64.7 +/- 18.5 [n = 9]; p less than 0.05). Prednisolone in the culture medium at physiologic concentrations suppressed the release of IL-1 and enhanced the release of IL-1 IHA. IL-1 IHA inhibited not only mouse thymocyte proliferation but also human fibroblast proliferation in the presence of IL-1.

Interleukin 1 production by alveolar macrophages is decreased in smokers

To evaluate the mechanism by which cigarette smoking suppresses pulmonary immune responses, we determined the capacity of alveolar macrophages (AM) to produce interleukin 1 (IL-1 in 32 normal subjects and in 40 patients with pulmonary sarcoidosis. The amount of IL-1 released from LPS-stimulated AM from smokers was significantly decreased compared with that in nonsmokers in both normal and sarcoid groups. The addition of indomethacin to the cultures in 18 normal subjects and in 22 patients with pulmonary sarcoidosis yielded similar results, thus excluding the possibility that this difference resulted from a difference in the amount of cyclooxygenase metabolites released in the culture supernatants. Similar results were obtained by enzyme-linked immunosolvent assay. Because IL-1 is thought to induce the accumulation of T cells at the site of disease and contribute to local cellular and humoral immunity of the lung, our data suggest that the reduced capacity of AM to release IL-1 in smokers affords partial protection against the initiation of immune responses in the lung and the development of granulomatous lung diseases.