Apoptosis inhibitor of macrophage (AIM) expression in alveolar macrophages in COPD

Immune Dysregulation in Chronic Obstructive Pulmonary Disease

Chronic obstructive pulmonary disease (COPD) is a disease whose incidence increase with age and is characterised by chronic inflammation and significant immune dysregulation. Inhalation of toxic substances cause oxidative stress in the lung tissue as well as airway inflammation, under the recruitment of chemokines, immune cells gathered and are activated to play a defensive role. However, persistent inflammation damages the immune system and leads to immune dysregulation, which is mainly manifested in the reduction of the body's immune response to antigens, and immune cells function are impaired, further destroy the respiratory defensive system, leading to recurrent lower respiratory infections and progressive exacerbation of the disease, thus immune dysregulation play an important role in the pathogenesis of COPD. This review summarizes the changes of innate and adaptive immune-related cells during the pathogenesis of COPD, aiming to control COPD airway inflammation and improve lung tissue remodelling by regulating immune dysregulation, for further reducing the risk of COPD progression and opening new avenues of therapeutic intervention in COPD.

The effects of apoptosis inhibitor of macrophage in kidney diseases

Kidney disease is a progressive and irreversible condition in which immunity is a contributing factor that endangers human health. It is widely acknowledged that macrophages play a significant role in developing and causing numerous kidney diseases. The increasing focus on the mechanism by which macrophages express apoptosis inhibitor of macrophages (AIM) in renal diseases has been observed. AIM is an apoptosis inhibitor that stops different things that cause apoptosis from working. This keeps AIM-bound cell types alive. Notably, the maintenance of immune cell viability regulates immunity. As our investigation progressed, we concluded that AIM has two sides when it comes to renal diseases. AIM can modulate renal phagocytosis, expedite the elimination of renal tubular cell fragments, and mitigate tissue injury. AIM can additionally exacerbate the development of renal fibrosis and kidney disease by prolonging inflammation. IgA nephropathy (IgAN) may also worsen faster if more protein is in the urine. This is because IgA and immunoglobulin M are found together and expressed. In the review, we provide a comprehensive overview of prior research and concentrate on the impacts of AIM on diverse subcategories of nephropathies. We discovered that AIM is closely associated with renal diseases by playing a positive or negative role in the onset, progression, or cure of kidney disease. AIM is thus a potentially effective therapeutic target for kidney diseases.

Apoptosis inhibitor of macrophages/CD5L enhances phagocytosis in the trabecular meshwork cells and regulates ocular hypertension

The trabecular meshwork (TM) cells of the eye are important for controlling intraocular pressure (IOP) and regulating outflow resistance in the aqueous humor. TM cells can remove particles and cellular debris by phagocytosis, decreasing both outflow resistance and IOP. However, the underlying mechanisms remain unclear. Here, we investigate whether apoptosis inhibitor of macrophages (AIM), which mediates the removal of dead cells and debris in renal tubular epithelial cells, regulates the phagocytic capacity of TM cells. In vitro experiments revealed that CD36, the main receptor for AIM, colocalized with AIM in human TM cells; additionally, phagocytosis was stimulated when AIM was provided. Furthermore, in a mouse model with transient IOP elevation induced by laser iridotomy (LI), removal of accumulated iris pigment epithelial cells or debris in the TM and recovery of IOP to baseline levels were delayed in AIM-/- mice, compared with control mice. However, treatment with AIM eyedrops rescued AIM-/- mice from the elevated IOP after LI. Since AIM is a protein known to inhibit macrophage apoptosis, we additionally verified its involvement in macrophage removal of cellular debris and IOP. There were no statistically significant differences in the number of macrophages between control mice and AIM-/- mice in the TM. Additionally, we confirmed the rescue effect of the rAIM eyedrops after macrophages had been removed by clodronate liposomes. Therefore, AIM plays an important role in regulating the phagocytic capacity of TM cells, thereby affecting outflow resistance. Our results suggest that drugs targeting the phagocytic capacity of TM cells via the AIM-CD36 pathway may be used to treat glaucoma.

Apoptosis inhibitor of macrophage (AIM)/CD5L is involved in the pathogenesis of COPD

BACKGROUND

Alveolar macrophages (AMs) and AM-produced matrix metalloprotease (MMP)-12 are known to play critical roles in the pathogenesis of chronic obstructive pulmonary disease (COPD). The apoptosis inhibitor of the macrophages (AIM)/CD5 molecule-like (CD5L) is a multifunctional protein secreted by the macrophages that mainly exists in the blood in a combined form with the immunoglobulin (Ig)M pentamer. Although AIM has both facilitative and suppressive roles in various diseases, its role in COPD remains unclear.

METHODS

We investigated the role of AIM in COPD pathogenesis using porcine pancreas elastase (PPE)-induced and cigarette smoke-induced emphysema mouse models and an in vitro model using AMs. We also analyzed the differences in the blood AIM/IgM ratio among nonsmokers, healthy smokers, and patients with COPD and investigated the association between the blood AIM/IgM ratio and COPD exacerbations and mortality in patients with COPD.

RESULTS

Emphysema formation, inflammation, and cell death in the lungs were attenuated in AIM-/- mice compared with wild-type (WT) mice in both PPE- and cigarette smoke-induced emphysema models. The PPE-induced increase in MMP-12 was attenuated in AIM-/- mice at both the mRNA and protein levels. According to in vitro experiments using AMs stimulated with cigarette smoke extract, the MMP-12 level was decreased in AIM-/- mice compared with WT mice. This decrease was reversed by the addition of recombinant AIM. Furthermore, an analysis of clinical samples showed that patients with COPD had a higher blood AIM/IgM ratio than healthy smokers. Additionally, the blood AIM/IgM ratio was positively associated with disease severity in patients with COPD. A higher AIM/IgM ratio was also associated with a shorter time to the first COPD exacerbation and higher all-cause and respiratory mortality.

CONCLUSIONS

AIM facilitates the development of COPD by upregulating MMP-12. Additionally, a higher blood AIM/IgM ratio was associated with poor prognosis in patients with COPD.

TRIAL REGISTRATION

This clinical study, which included nonsmokers, healthy smokers, and smokers with COPD, was approved by the Ethics Committee of the Hokkaido University Hospital (012-0075, date of registration: September 5, 2012). The Hokkaido COPD cohort study was approved by the Ethics Committee of the Hokkaido University School of Medicine (med02-001, date of registration: December 25, 2002).

ISM1 protects lung homeostasis via cell-surface GRP78-mediated alveolar macrophage apoptosis

Alveolar macrophages (AMs) are critical for lung immune defense and homeostasis. They are orchestrators of chronic obstructive pulmonary disease (COPD), with their number significantly increased and functions altered in COPD. However, it is unclear how AM number and function are controlled in a healthy lung and if changes in AMs without environmental assault are sufficient to trigger lung inflammation and COPD. We report here that absence of isthmin 1 (ISM1) in mice (Ism1-/- ) leads to increase in both AM number and functional heterogeneity, with enduring lung inflammation, progressive emphysema, and significant lung function decline, phenotypes similar to human COPD. We reveal that ISM1 is a lung resident anti-inflammatory protein that selectively triggers the apoptosis of AMs that harbor high levels of its receptor cell-surface GRP78 (csGRP78). csGRP78 is present at a heterogeneous level in the AMs of a healthy lung, but csGRP78high AMs are expanded in Ism1-/- mice, cigarette smoke (CS)-induced COPD mice, and human COPD lung, making these cells the prime targets of ISM1-mediated apoptosis. We show that csGRP78high AMs mostly express MMP-12, hence proinflammatory. Intratracheal delivery of recombinant ISM1 (rISM1) depleted csGRP78high AMs in both Ism1-/- and CS-induced COPD mice, blocked emphysema development, and preserved lung function. Consistently, ISM1 expression in human lungs positively correlates with AM apoptosis, suggesting similar function of ISM1-csGRP78 in human lungs. Our findings reveal that AM apoptosis regulation is an important physiological mechanism for maintaining lung homeostasis and demonstrate the potential of pulmonary-delivered rISM1 to target csGRP78 as a therapeutic strategy for COPD.

Cigarette smoke extracts induce apoptosis in Raw264.7 cells via endoplasmic reticulum stress and the intracellular Ca2+/P38/STAT1 pathway

Cigarette smoke (CS) exposure is a risk factor for chronic obstructive pulmonary disease (COPD). CS exposure impairs the ability of killing pathogens in macrophages, which might be due to the abnormal apoptosis induced by CS. This study explored the effects and mechanisms of cigarette smoke extract (CSE) on the apoptosis of macrophages in vitro. Raw264.7 cells were treated with CSE at different concentrations, and viability and apoptosis of cells was accessed. The protein expression was detected by western blot. The intracellular Ca²⁺ level was evaluated by Fluo-4 AM probe assay. CSE induced the apoptosis and increased the expression of cleaved caspase 3, which were attenuated by a caspase inhibitor. CSE increased the expression of CHOP, BiP and P-eif2α, and the inhibitor of endoplasmic reticulum stress (ERS) decreased the apoptosis induced by CSE. Phosphorylation levels of P38, JNK and ERK1/2 were increased following incubation with CSE. Only P38 inhibitor significantly reduced apoptosis induced by CSE, while ERK1/2 inhibitor promoted apoptosis. Phosphorylation of STAT1 at Ser727 was activated by CSE and attenuated by the P38 inhibitor. Finally, CSE increased the level of intracellular Ca²⁺, and calcium chelator partly attenuated the apoptosis and phosphorylation of P38 and STAT1 induced by CSE. CSE induced a caspase 3-dependent apoptosis in Raw264.7 cells via ERS and intracellular Ca²⁺/P38/STAT1 pathway.

Apoptosis inhibitor of macrophage as a biomarker for disease activity in Japanese children with IgA nephropathy and Henoch-Schönlein purpura nephritis

BACKGROUND

To evaluate the apoptosis inhibitor of macrophage (AIM) deposition patterns on the kidneys of children with IgA nephropathy (IgAN) and Henoch-Schönlein purpura nephritis (HSPN) and to investigate the clinical usefulness of serum and/or urinary AIM levels as biomarkers for the disease activity.

METHODS

Immunohistochemical study was performed in the kidneys of 37 patients with IgAN and 10 patients with HSPN. Serum and urinary AIM levels in the patients and 20 healthy controls (HCs) were quantified by enzyme-linked immunosorbent assay. The results were compared with clinical features.

RESULTS

In patients with IgAN and HSPN, AIM expression was observed in various areas, including the glomerular mesangial and capillary areas, the proximal and distal tubular epithelial cells, and on infiltrating macrophages in the glomeruli and interstitial areas. Serum and urinary AIM levels were significantly elevated in these patients compared with the HCs. Urinary AIM levels were positively correlated with the histological severity and degree of proteinuria and hematuria as well as urinary β2 microglobulin and urinary N-acetyl-β-D-glucosaminidase levels.

CONCLUSIONS

AIM plays an important role in the pathogenesis of IgAN and HSPN. Urinary AIM levels can potentially reflect active renal inflammation in these diseases and may represent a useful biomarker for disease activity.

IMPACT

Urinary AIM levels may represent a useful biomarker for disease activity of IgAN and HSPN. AIM expression was observed in the glomeruli, tubular epithelial cells, and infiltrating macrophages in glomeruli and interstitial area. U-AIM/Cr were significantly correlated not only with proteinuria, hematuria, and u-β2MG and u-NAG levels but also with the activity index of histological findings in kidney biopsy specimens. Our results can emphasize the important role of AIM in the pathogenesis of IgAN and HSPN.

Therapeutic Targeting of Apoptosis Inhibitor of Macrophage/CD5L in Sepsis

The factors involved in disturbing host homeostasis during sepsis are largely unknown. We sought to determine the immunopathological role of apoptosis inhibitor of macrophage (AIM)/CD5L in sepsis. Here, we show that blockade of AIM led to significantly increased survival after experimental sepsis, and it decreased local and systemic inflammation, reduced tissue injury, and inhibited bacterial dissemination in the blood, in particular at later time points. Supplementation of recombinant AIM in sepsis resulted in increased tissue injury, amplified inflammation, increased bacteremia, and worsened mortality. Interestingly, the most important difference in the production of cytokines and chemokines after in vivo AIM blockade or AIM administration during sepsis was IL-10. In vitro, AIM enhanced IL-10 production from macrophages, neutrophils, or lymphocytes. In vivo, the beneficial effects of AIM blockade and the detrimental effects of AIM addition on experimental sepsis were ablated by treatment with recombinant IL-10 and neutralizing anti-IL-10 antibodies, respectively. This study is the first to identify AIM as an important mediator in disturbing host homeostasis in sepsis.

CD5L contributes to the pathogenesis of methicillin-resistant Staphylococcus aureus-induced pneumonia

Staphylococcus aureus is a major causative microorganism in community- and healthcare-acquired pneumonia. CD5L is an important protein in the control of immune homeostasis. In this study, we found that patients with S. aureus pneumonia displayed increased levels of circulating CD5L. Likewise, mice with S. aureus pneumonia had elevated CD5L levels in the lungs. Anti-CD5L antibody protected mice from lethal pneumonia induced by methicillin-resistant S. aureus. The survival benefit obtained with antibody against CD5L was associated with an improvement of bacterial clearance and a reduction of pulmonary inflammatory cytokines and chemokines. Conversely, co-injection of recombinant CD5L and S. aureus markedly increased the lethality of S. aureus pneumonia. These findings suggest that CD5L contributed to the immunopathology of S. aureus pneumonia.

Elevation of serum CD5L concentration is correlated with disease activity in patients with systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is characterized by an autoantibody- and immune complex-mediated inflammatory disease. Since CD5-like (CD5L), also known as apoptosis inhibitor of macrophage (AIM), is as an apoptosis inhibitor that protects the survival of macrophages, T cells, and NKT against proapoptotic agents, which plays an important role in the pathogenesis of various inflammatory diseases, we investigated the possible aberrant production of CD5L and its clinical implications in SLE patients. We measured the serum concentration and ex vivo production of CD5L in 68 SLE patients and 60 sex- and age- matched control individuals using an enzyme-linked immunoabsorbent assay. Serum CD5L concentrations were significantly higher in SLE patients than in healthy control subjects. Increase in CD5L concentration correlated positively and significantly with SLE Disease Activity Index (SLEDAI) score in all SLE patients. Besides, CD5L titers were positively correlated with anti-double stranded DNA antibody (anti-dsDNA) titers, ESR and C-reactive protein (CRP) levels, and negatively correlated with complement 3 (C3) and C4 levels. Serum CD5L concentrations could be significantly decreased after effective treatment of SLE. In addition, the ex vivo release of CD5L upon mitogen activation of peripheral blood mononuclear cells was significantly higher in the SLE groups than in the healthy control group. The above results suggest that the up-regulated production of CD5L is important in the immunopathogenesis of SLE, and may serve as a potential disease marker for the monitoring of SLE disease severity and therapeutic efficacy.

Epidemiologic Evidence of and Potential Mechanisms by Which Second-Hand Smoke Causes Predisposition to Latent and Active Tuberculosis

Many studies have linked cigarette smoke (CS) exposure and tuberculosis (TB) infection and disease although much fewer have studied second-hand smoke (SHS) exposure. Our goal is to review the epidemiologic link between SHS and TB as well as to summarize the effects SHS and direct CS on various immune cells relevant for TB. PubMed searches were performed using the key words "tuberculosis" with "cigarette," "tobacco," or "second-hand smoke." The bibliography of relevant papers were examined for additional relevant publications. Relatively few studies associate SHS exposure with TB infection and active disease. Both SHS and direct CS can alter various components of host immunity resulting in increased vulnerability to TB. While the epidemiologic link of these 2 health maladies is robust, more definitive, mechanistic studies are required to prove that SHS and direct CS actually cause increased susceptibility to TB.

Industrial PM2.5 cause pulmonary adverse effect through RhoA/ROCK pathway

According to the Chinese Ministry of Health, industrial pollution-induced health impacts have been the leading cause of death in China. While industrial fine particulate matter (PM_2.5) is associated with adverse health effects, the major action mechanisms of different compositions of PM_2.5 are currently unclear. In this study, we treated normal human lung epithelial BEAS-2B cells with industrial organic and water-soluble PM_2.5 extracts under daily alveolar deposition dose to elucidate the molecular mechanisms underlying adverse pulmonary effects induced by PM_2.5, including oxidative damage, inflammatory response, lung epithelial barrier dysfunction, and the recruitment of macrophages. We found that water-soluble PM_2.5 extracts caused more severe cytotoxic effects on BEAS-2B cells compared with that of organic extracts. Both organic and water-soluble PM_2.5 extracts induced activation of the RhoA/ROCK pathway. Inflammatory response, epithelial barrier dysfunction, and the activation of NF-кB caused by both PM_2.5 extracts were attenuated by ROCK inhibitor Y-27632. This indicated that both PM_2.5 extracts could cause damage to epithelial cells through RhoA/ROCK-dependent NF-кB activation. Furthermore, the upregulation of macrophage adhesion induced by both PM_2.5 extracts was also attenuated by Y-27632 in a co-culture model of macrophages and the epithelial cells. Therefore, our results support that industrial PM_2.5 extracts-induced activation of the RhoA/ROCK-dependent NF-кB pathway induces pulmonary adverse effect. Thus, pharmacological inhibition of ROCK activation might have therapeutic potential in preventing lung disease associated with PM_2.5.

Orchestrating Role of Apoptosis Inhibitor of Macrophage in the Resolution of Acute Lung Injury

Appropriate resolution of inflammation is known to be essential in tissue homeostasis. In this study, we evaluated the significance of a macrophage-derived soluble protein, apoptosis inhibitor of macrophage (AIM), in LPS-induced lung injury in mice. After oropharyngeal administration of LPS, the level of free-form serum AIM increased on days 2-4, accompanied by the resolution of inflammation, which was observed in the cellular profile of bronchoalveolar lavage fluid. In an experiment using wild-type (WT) and AIM^-/- mice, the resolution of inflammation was accelerated in AIM^-/- mice when compared with the WT mice, which was reversed when recombinant AIM protein was administered. The changes in the histopathological findings and inflammatory mediators followed similar trends, and the ratio of apoptotic cells was increased in AIM^-/- mice when compared with the WT mice. In vitro analysis showed that macrophage phagocytosis of apoptotic neutrophils was suppressed in the presence of AIM, indicating that anti-resolution property of AIM involves efferocytosis inhibition. In lipidomic analysis of lung tissues, the levels of several lipid mediators increased markedly when LPS was given to WT mice. However, in AIM^-/- mice, the concentrations of these lipid mediators were not significantly upregulated by LPS. These data reflect the significant role of AIM in lipid metabolism; it may suppress lipid metabolites at baseline, and then produce an inflammatory/pathologic pattern in the event of LPS-induced lung injury. Taken together, AIM may play an orchestrating role in the resolution process of inflammation by altering the profile of pulmonary lipid mediators in mice.

Characterisation of lung macrophage subpopulations in COPD patients and controls

Lung macrophage subpopulations have been identified based on size. We investigated characteristics of small and large macrophages in the alveolar spaces and lung interstitium of COPD patients and controls. Alveolar and interstitial cells were isolated from lung resection tissue from 88 patients. Macrophage subpopulation cell-surface expression of immunological markers and phagocytic ability were assessed by flow cytometry. Inflammatory related gene expression was measured. Alveolar and interstitial macrophages had subpopulations of small and large macrophages based on size and granularity. Alveolar macrophages had similar numbers of small and large cells; interstitial macrophages were mainly small. Small macrophages expressed significantly higher cell surface HLA-DR, CD14, CD38 and CD36 and lower CD206 compared to large macrophages. Large alveolar macrophages showed lower marker expression in COPD current compared to ex-smokers. Small interstitial macrophages had the highest pro-inflammatory gene expression levels, while large alveolar macrophages had the lowest. Small alveolar macrophages had the highest phagocytic ability. Small alveolar macrophage CD206 expression was lower in COPD patients compared to smokers. COPD lung macrophages include distinct subpopulations; Small interstitial and small alveolar macrophages with more pro-inflammatory and phagocytic function respectively, and large alveolar macrophages with low pro-inflammatory and phagocytic ability.

COPD monocytes demonstrate impaired migratory ability

Background

Increased lung macrophage numbers in COPD may arise from upregulation of blood monocyte recruitment into the lungs. CCR5 is a monocyte chemokine receptor regulated by interleukin-6 (IL-6); the concentration of CCR5 ligands are known to be elevated in COPD lungs. The objective of this study was to investigate mechanisms of monocyte recruitment to the lung in COPD, including the role of CCR5 signalling.

Methods

Ninety one COPD patients, 29 smokers (S) and 37 non-smokers (NS) underwent sputum induction, plasma sampling (to measure IL-6 and soluble IL-6 receptor [sIL-6R] by immunoassay), monocyte characterization (by flow cytometry) and monocyte isolation for cell migration and quantitative polymerase chain reaction studies. Lung tissue was used for immunohistochemistry.

Results

Plasma IL-6 and sIL-6R levels were increased in COPD. Greater proportions of COPD CD14⁺⁺CD16⁺ monocytes expressed CCR5 compared to controls. Monocyte stimulation with IL-6 and sIL-6R increased CCR5 gene expression. COPD monocytes demonstrated impaired migration towards sputum supernatant compared to NS (% migration, 4.4 vs 11.5, respectively; p < 0.05). Pulmonary microvessels showed reduced monocyte recruitment (% marginated cells) in COPD compared to NS, (9.3% vs 83.1%, respectively). The proportion of replicating Ki67⁺ alveolar macrophages was reduced in COPD compared to NS. All alveolar macrophages from COPD and S expressed the anti-apoptosis marker BCL2; this protein was not present in non-smokers or COPD ex-smokers.

Conclusion

COPD monocytes show decreased migratory ability despite increased CCR5 expression. Increased COPD lung macrophage numbers may be due to delayed apoptosis.

Electronic supplementary material

The online version of this article (doi:10.1186/s12931-017-0569-y) contains supplementary material, which is available to authorized users.

Biomass smoke as a risk factor for chronic obstructive pulmonary disease: effects on innate immunity

Chronic obstructive pulmonary disease (COPD), a major cause of mortality and morbidity worldwide, is considered an archetypical disease of innate immunity, where inhaled particles and gases trigger an inflammatory response, favoring tissue proliferation in small airways and tissue destruction in lung parenchyma, in addition to the recruitment of immune cells to these compartments. Although cigarette smoking is still considered the main risk factor for developing COPD, the trend of proposing biomass smoke (BS) exposure as a principal risk factor is gaining importance, as around 3 billion people worldwide are exposed to this pollutant daily. A considerable amount of evidence has shown the potential of BS as an enhancer of lung inflammation. However, an impairment of some innate immune responses after BS exposure has also been described. Regarding the mechanisms by which biomass smoke alters the innate immune responses, three main classes of cell surface receptors-the TLRs, the scavenger receptors and the transient receptor potential channels-have shown the ability to transduce signals initiated after BS exposure. This article is an updated and comprehensive review of the immunomodulatory effects described after the interaction of BS components with these receptors.

Association of apoptosis inhibitor of macrophage (AIM) expression with urinary protein and kidney dysfunction

BACKGROUND

Apoptosis inhibitor of macrophage (AIM) expressed on macrophages prolongs inflammation by protecting macrophages from apoptosis. Most circulating AIM co-exists with immunoglobulin M (IgM). AIM's pathophysiological role in relation to IgM remains unclear. Here we evaluated the glomerular expression/deposition of AIM and IgM in the kidney using immunohistochemistry and its associations with clinical manifestations in 43 patients with biopsy-confirmed kidney diseases.

METHODS

Kidney biopsy tissue from all patients was immunostained for AIM and IgM. Staining patterns and percent stained areas within the glomeruli were determined. Cells expressing AIM were identified by co-staining with macrophage and endothelial cell surface markers. Correlations between staining results and clinical parameters were evaluated using univariate and multivariate analyses.

RESULTS

AIM was deposited in various areas, such as mesangial and capillary area. A part of AIM expression was localized to CD68-positive macrophages in the glomerulus. Amount of glomerular expression was positively correlated with urinary protein in patients with severe proteinuria (urinary protein ≥0.5 g/day) and kidney dysfunction [estimated glomerular filtration ratio (eGFR) <60 ml/min/1.73 m²]. Urinary protein was higher in patients exhibiting overlapping glomerular expression of AIM and IgM. Annual eGFR decline rate negatively correlated with AIM-positive area. AIM-positive area and initial serum creatinine were independently associated with decreased kidney function.

CONCLUSION

AIM expression in the kidney was associated with urinary protein and decline in kidney function. Co-expression with IgM appeared to exacerbate AIM's deleterious effects on kidney function. Combined glomerular AIM and IgM expression is a candidate prognostic index for kidney disease.

Nitrative stress, oxidative stress and plasma endothelin levels after inhalation of particulate matter and ozone

BACKGROUND

While exposure to ambient air contaminants is clearly associated with adverse health outcomes, disentangling mechanisms of pollutant interactions remains a challenge.

OBJECTIVES

We aimed at characterizing free radical pathways and the endothelinergic system in rats after inhalation of urban particulate matter, ozone, and a combination of particles plus ozone to gain insight into pollutant-specific toxicity mechanisms and any effect modification due to air pollutant mixtures.

METHODS

Fischer 344 rats were exposed for 4 h to a 3 × 3 concentration matrix of ozone (0, 0.4, 0.8 ppm) and EHC-93 particles (0, 5, 50 mg/m(3)). Bronchoalveolar lavage fluid (BALF), BAL cells, blood and plasma were analysed for biomarkers of effects immediately and 24 h post-exposure.

RESULTS

Inhalation of ozone increased (p < 0.05) lipid oxidation products in BAL cells immediately post-exposure, and increased (p < 0.05) total protein, neutrophils and mature macrophages in the BALF 24 h post-exposure. Ozone increased (p < 0.05) the formation of reactive oxygen species (ROS), assessed by m-, p-, o-tyrosines in BALF (Ozone main effects, p < 0.05), while formation of reactive nitrogen species (RNS), indicated by 3-nitrotyrosine, correlated with dose of urban particles (EHC-93 main effects or EHC-93 × Ozone interactions, p < 0.05). Carboxyhemoglobin levels in blood exhibited particle exposure-related increase (p < 0.05) 24 h post recovery. Plasma 3-nitrotyrosine and o-tyrosine were increased (p < 0.05) after inhalation of particles; the effect on 3-nitrotyrosine was abrogated after exposure to ozone plus particles (EHC-93 × Ozone, p < 0.05). Big endothelin-1 (BET-1) and ET-1 were increased in plasma after inhalation of particles or ozone alone, but the effects appeared to be attenuated by co-exposure to contaminants (EHC-93 × Ozone, p < 0.05). Plasma ET levels were positively correlated (p < 0.05) with BALF m- and o-tyrosine levels.

CONCLUSIONS

Pollutant-specific changes can be amplified or abrogated following multi-pollutant exposures. Oxidative and nitrative stress in the lung compartment may contribute to secondary extra-pulmonary ROS/RNS formation. Nitrative stress and endothelinergic imbalance emerge as potential key pathways of air pollutant health effects, notably of ambient particulate matter.

Nitrative stress, oxidative stress and plasma endothelin levels after inhalation of particulate matter and ozone

Background

While exposure to ambient air contaminants is clearly associated with adverse health outcomes, disentangling mechanisms of pollutant interactions remains a challenge.

Objectives

We aimed at characterizing free radical pathways and the endothelinergic system in rats after inhalation of urban particulate matter, ozone, and a combination of particles plus ozone to gain insight into pollutant-specific toxicity mechanisms and any effect modification due to air pollutant mixtures.

Methods

Fischer 344 rats were exposed for 4 h to a 3 × 3 concentration matrix of ozone (0, 0.4, 0.8 ppm) and EHC-93 particles (0, 5, 50 mg/m³). Bronchoalveolar lavage fluid (BALF), BAL cells, blood and plasma were analysed for biomarkers of effects immediately and 24 h post-exposure.

Results

Inhalation of ozone increased (p < 0.05) lipid oxidation products in BAL cells immediately post-exposure, and increased (p < 0.05) total protein, neutrophils and mature macrophages in the BALF 24 h post-exposure. Ozone increased (p < 0.05) the formation of reactive oxygen species (ROS), assessed by m-, p-, o-tyrosines in BALF (Ozone main effects, p < 0.05), while formation of reactive nitrogen species (RNS), indicated by 3-nitrotyrosine, correlated with dose of urban particles (EHC-93 main effects or EHC-93 × Ozone interactions, p < 0.05). Carboxyhemoglobin levels in blood exhibited particle exposure-related increase (p < 0.05) 24 h post recovery. Plasma 3-nitrotyrosine and o-tyrosine were increased (p < 0.05) after inhalation of particles; the effect on 3-nitrotyrosine was abrogated after exposure to ozone plus particles (EHC-93 × Ozone, p < 0.05). Big endothelin-1 (BET-1) and ET-1 were increased in plasma after inhalation of particles or ozone alone, but the effects appeared to be attenuated by co-exposure to contaminants (EHC-93 × Ozone, p < 0.05). Plasma ET levels were positively correlated (p < 0.05) with BALF m- and o-tyrosine levels.

Conclusions

Pollutant-specific changes can be amplified or abrogated following multi-pollutant exposures. Oxidative and nitrative stress in the lung compartment may contribute to secondary extra-pulmonary ROS/RNS formation. Nitrative stress and endothelinergic imbalance emerge as potential key pathways of air pollutant health effects, notably of ambient particulate matter.

Electronic supplementary material

The online version of this article (doi:10.1186/s12989-015-0103-7) contains supplementary material, which is available to authorized users.

AIM/CD5L: a key protein in the control of immune homeostasis and inflammatory disease

CD5L, a soluble protein belonging to the SRCR superfamily, is expressed mostly by macrophages in lymphoid and inflamed tissues. The expression of this protein is transcriptionally controlled by LXRs, members of the nuclear receptor family that play major roles in lipid homeostasis. Research undertaken over the last decade has uncovered critical roles of CD5L as a PRR of bacterial and fungal components and in the control of key mechanisms in inflammatory responses, with involvement in processes, such as infection, atherosclerosis, and cancer. In this review, we summarize the current knowledge of CD5L, its roles at the intersection between lipid homeostasis and immune response, and its potential use as a diagnostic biomarker in a variety of diseases, such as TB and liver cirrhosis.

Genetic variants in ADAM33 are associated with airway inflammation and lung function in COPD

BACKGROUND

Genetic factors play a role in the development and severity of chronic obstructive pulmonary disease (COPD). The pathogenesis of COPD is a multifactorial process including an inflammatory cell profile. Recent studies revealed that single nucleotide polymorphisms (SNPs) within ADAM33 increased the susceptibility to COPD through changing the airway inflammatory process and lung function.

METHODS

In this paper, we investigated associations of four polymorphisms (T1, T2, S2 and Q-1) of ADAM33 as well as their haplotypes with pulmonary function and airway inflammatory process in an East Asian population of patients with COPD.

RESULTS

We found that T1, T2 and Q-1 were significantly associated with the changes of pulmonary function and components of cells in sputum of COPD, and T1 and Q-1 were significantly associated with cytokines and mediators of inflammation in airway of COPD in recessive models. 10 haplotypes were significantly associated with transfer factor of the lung for carbon monoxide in the disease state, 4 haplotypes were significantly associated with forced expiratory volume in one second, and other haplotypes were associated with airway inflammation.

CONCLUSIONS

We confirmed for the first time that ADAM33 was involved in the pathogenesis of COPD by affecting airway inflammation and immune response in an East Asian population. Our results made the genetic background of COPD, a common and disabling disease, more apparent, which would supply genetic support for the study of the mechanism, classification and treatment for this disease.

Tobacco exposure and susceptibility to tuberculosis: is there a smoking gun?

In many regions of the world, there is a great overlap between the prevalence of cigarette smoke exposure and tuberculosis. Despite the large body of epidemiologic evidence that tobacco smoke exposure is associated with increased tuberculosis infection, active disease, severity of disease, and mortality from tuberculosis, these studies cannot distinguish whether the mechanism is principally through direct impairment of anti-tuberculosis immunity by cigarette smoke or due to potential confounders that increase risk for tuberculosis and are commonly associated with smoking--such as poverty, malnutrition, and crowded living conditions. While there are several in vivo murine and in vitro macrophage studies showing cigarette smoke impairs control of tuberculous infection, little is known of the molecular and cellular mechanisms by which this impairment occurs. Herein, we highlight the key findings of these studies. Additionally, we review key immune cells that play critical roles in host-defense or pathogenesis of tuberculosis and generate a hypothesis-driven discussion of the possible mechanisms by which cigarette smoke impairs or enhances their functions, respectively, ultimately resulting in compromised immunity against tuberculosis.

Cigarette smoke extract-induced BEAS-2B cell apoptosis and anti-oxidative Nrf-2 up-regulation are mediated by ROS-stimulated p38 activation

Cigarette smoke contains reactive oxygen (ROS) that can cause oxidative stress. It increases the number of apoptotic and necrotic lung cells and further induces the development of chronic airway disease. In this study, we investigated the effects of cigarette smoke extract (CSE) on apoptosis in human bronchial epithelial cells (BEAS-2B). CSE exposure induced ROS generation and p38 mitogen-activated protein kinase (MAPK) activation that are associated with the activation of apoptosis-regulating signal kinase 1 (ASK-1). N-acetylcysteine (a general antioxidant) attenuated the CSE-induced ASK-1 and p38 MAPK activation and cell apoptosis, suggesting a triggering role of ROS in ASK-1/p38 MAPK activation during apoptotic progression. In contrast, the inhibition and knockdown of p38 attenuated the expression of anti-oxidant master NF-E2-related factor 2 (Nrf-2) and CSE-induced apoptosis, suggesting that p38 MAPK modulates Nrf-2 expression and presumably prevents cell apoptosis. Taken together, the data presented in this manuscript demonstrate that the ROS-dependent ASK-1/p38 signaling cascade regulates CSE-induced BEAS-2B cell apoptosis. In addition, anti-oxidative Nrf-2 is also up-regulated by the ROS/p38 signaling cascade in this progression.