Differential role of CD80 and CD86 on alveolar macrophages in the presentation of allergen to T lymphocytes in asthma

Comprehensive analysis of lung macrophages and dendritic cells in two murine models of allergic airway inflammation reveals model- and subset-specific accumulation and phenotypic alterations

Introduction

Allergic asthma has been mainly attributed to T helper type 2 (Th2) and proinflammatory responses but many cellular processes remain elusive. There is increasing evidence for distinct roles for macrophage and dendritic cell (DC) subsets in allergic airway inflammation (AAI). At the same time, there are various mouse models for allergic asthma that have been of utmost importance in identifying key inflammatory pathways in AAI but that differ in the allergen and/or route of sensitization. It is unclear whether and how the accumulation and activation of specialized macrophage and DC subsets depend on the experimental model chosen for analyses.

Methods

In our study, we employed high-parameter spectral flow cytometry to comprehensively assess the accumulation and phenotypic alterations of different macrophage- and DC-subsets in the lung in an OVA- and an HDM-mediated mouse model of AAI.

Results

We observed subset-specific as well as model-specific characteristics with respect to cell numbers and functional marker expression. Generally, alveolar as opposed to interstitial macrophages showed increased MHCII surface expression in AAI. Between the models, we observed significantly increased numbers of alveolar macrophages, CD103+ DC and CD11b+ DC in HDM-mediated AAI, concurrent with significantly increased airway interleukin-4 but decreased total serum IgE levels. Further, increased expression of CD80 and CD86 on DC was exclusively detected in HDM-mediated AAI.

Discussion

Our study demonstrates a model-specific involvement of macrophage and DC subsets in AAI. It further highlights spectral flow cytometry as a valuable tool for their comprehensive analysis under inflammatory conditions in the lung.

In-silico identification and prioritization of therapeutic targets of asthma

Asthma is a "common chronic disorder that affects the lungs causing variable and recurring symptoms like repeated episodes of wheezing, breathlessness, chest tightness and underlying inflammation. The interaction of these features of asthma determines the clinical manifestations and severity of asthma and the response to treatment" [cited from: National Heart, Lung, and Blood Institute. Expert Panel 3 Report. Guidelines for the Diagnosis and Management of Asthma 2007 (EPR-3). Available at: https://www.ncbi.nlm.nih.gov/books/NBK7232/ (accessed on January 3, 2023)]. As per the WHO, 262 million people were affected by asthma in 2019 that leads to 455,000 deaths ( https://www.who.int/news-room/fact-sheets/detail/asthma ). In this current study, our aim was to evaluate thousands of scientific documents and asthma associated omics datasets to identify the most crucial therapeutic target for experimental validation. We leveraged the proprietary tool Ontosight® Discover to annotate asthma associated genes and proteins. Additionally, we also collected and evaluated asthma related patient datasets through bioinformatics and machine learning based approaches to identify most suitable targets. Identified targets were further evaluated based on the various biological parameters to scrutinize their candidature for the ideal therapeutic target. We identified 7237 molecular targets from published scientific documents, 2932 targets from genomic structured databases and 7690 dysregulated genes from the transcriptomics and 560 targets from genomics mutational analysis. In total, 18,419 targets from all the desperate sources were analyzed and evaluated though our approach to identify most promising targets in asthma. Our study revealed IL-13 as one of the most important targets for asthma with approved drugs on the market currently. TNF, VEGFA and IL-18 were the other top targets identified to be explored for therapeutic benefit in asthma but need further clinical testing. HMOX1, ITGAM, DDX58, SFTPD and ADAM17 were the top novel targets identified for asthma which needs to be validated experimentally.

Role of macrophage AHR/TLR4/STAT3 signaling axis in the colitis induced by non-canonical AHR ligand aflatoxin B1

Here we report that macrophage AHR/TLR/STAT signaling axis is implicated in the colon colitis induced by non-canonical AHR ligand aflatoxin B1 (AFB1). In BALB/c mice gavaged with 5, 25 and 50 µg/kg body weight/day AFB1, we observed severe colitis featured by over-recruitment of myeloid lineage immune cells such as monocytes/macrophage in colon lamina propria. Stressed and damaged colon epithelial cells were observed in low-dose group, while twisted and shortened intestinal crypts being found in middle dose group. Severe tissue damage was induced in the high-dose group. Dose-dependent increases of ROS, NO, and decrease of mitochondrial ROS-suppressor STAT3 were observed in the exposure groups. Further investigation in AFB1-treated human macrophage model found: (1) functional adaptations such as elevation of TNF-alpha and IL-6 secretion, stimulation of phagocytosis, elevation of LTE4 level; (2) overall inflammatory status confirmed by RNA-sequence analysis, in line with up-regulation of immune functional proteins such as ICAM-1, IDO-1, NF-kB-p65, NLRP3, COX-2 and iNOS; (3) mRNA disruption of mitochondrial oxidative phosphorylation complex I units and STATs; (4) perturbation of AHR/TLR/STAT3 signaling axis, including elevated AHR, TLR2, TLR4, and decreased STAT3, p-STAT3 Ser727. Mechanism investigation revealed regulatory links of ligand-dependent AHR/TLR4/STAT3. AHR-TLR4 together regulate MyD88, and STAT3 may be directly regulated by MyD88 (TLR4 downstream molecule) upon AHR/TLR4 binding with ligands. Solely protein level changes of AHR/TLR4 cannot regulate STAT3. Our study suggests that macrophage AHR/TLR4/STAT3 is involved with the colitis induced by sub-acute exposure to AFB1. Future follow-up study will focus on the intervention of the colitis using AHR-anti-inflammatory ligands.

Recent advances in antigen targeting to antigen-presenting cells in veterinary medicine

Advances in antigen targeting in veterinary medicine have gained traction over the years as an alternative approach for diseases that remain a challenge for traditional vaccines. In addition to the nature of the immunogen, antigen-targeting success relies heavily on the chosen receptor for its direct influence on the elicited response that will ensue after antigen uptake. Different approaches using antibodies, natural or synthetic ligands, fused proteins, and DNA vaccines have been explored in various veterinary species, with pigs, cattle, sheep, and poultry as the most frequent models. Antigen-presenting cells can be targeted using a generic approach, such as broadly expressed receptors such as MHC-II, CD80/86, CD40, CD83, etc., or focused on specific cell populations such as dendritic cells or macrophages (Langerin, DC-SIGN, XCR1, DC peptides, sialoadhesin, mannose receptors, etc.) with contrasting results. Interestingly, DC peptides show high specificity to DCs, boosting activation, stimulating cellular and humoral responses, and a higher rate of clinical protection. Likewise, MHC-II targeting shows consistent results in enhancing both immune responses; an example of this strategy of targeting is the approved vaccine against the bovine viral diarrhea virus in South America. This significant milestone opens the door to continuing efforts toward antigen-targeting vaccines to benefit animal health. This review discusses the recent advances in antigen targeting to antigen-presenting cells in veterinary medicine, with a special interest in pigs, sheep, cattle, poultry, and dogs.

Biology of lung macrophages in health and disease

Tissue-resident alveolar and interstitial macrophages and recruited macrophages are critical players in innate immunity and maintenance of lung homeostasis. Until recently, assessing the differential functional contributions of tissue-resident versus recruited macrophages has been challenging because they share overlapping cell surface markers, making it difficult to separate them using conventional methods. This review describes how scRNA-seq and spatial transcriptomics can separate these subpopulations and help unravel the complexity of macrophage biology in homeostasis and disease. First, we provide a guide to identifying and distinguishing lung macrophages from other mononuclear phagocytes in humans and mice. Second, we outline emerging concepts related to the development and function of the various lung macrophages in the alveolar, perivascular, and interstitial niches. Finally, we describe how different tissue states profoundly alter their functions, including acute and chronic lung disease, cancer, and aging.

Air Quality, Pollution and Sustainability Trends in South Asia: A Population-Based Study

INTRODUCTION

Worsening air quality and pollution lead to numerous environmental health and sustainability issues in the South Asia region. This study analyzes India, Nepal, Bangladesh, Pakistan, Sri Lanka, and Nepal for air quality data trends and sustainability indicators.

METHODOLOGY

By using a population-based study design, six South Asian countries were analyzed using a step-wise approach. Data were obtained from government websites and publicly available repositories for region dynamics and key variables.

RESULTS

Between 1990 and 2020, air quality data indicated the highest rise in CO2 emissions in India (578.5 to 2441.8 million tons) (MT), Bangladesh, Nepal, and Pakistan. Greenhouse gas emissions, from 1990 to 2018, nearly tripled in India (1990.4 to 3346.6 MT of CO2-equivalents), Nepal (20.6 to 54.6 MT of CO2-equivalents), and Pakistan, and doubled in Bangladesh. Methane emissions rose the highest in Pakistan (70.4 to 151 MT of CO2-equivalents), followed by Nepal (17 to 31 MT of CO2-equivalents) and India (524.8 to 669.3 MT of CO2-equivalents). Nitrous oxide nearly doubled in Bangladesh (16.5 to 29.3 MT of CO2-equivalents), India (141.6 to 256.9 MT of CO2-equivalents), Nepal (17 to 31 MT of CO2-equivalents), and more than doubled in Pakistan (27 to 61 MT of CO2-equivalents). On noting particulate matter 2,5 annual exposure, India saw the highest rise from 81.3 µg/m3 (in 1990) to 90.9 µg/m3 (2017), whereas trends were steady in Pakistan (60.34 to 58.3 µg/m3). The highest rise was noted in Nepal (87.6 to 99.7 µg/m3) until 2017. During the coronavirus disease 19 pandemic, the pre-and post-pandemic changes between 2018 and 2021 indicated the highest PM2.5 concentration in Bangladesh (76.9 µg/m3), followed by Pakistan (66.8 µg/m3), India (58.1 µg/m3), Nepal (46 µg/m3) and Sri Lanka (17.4 µg/m3). Overall, South Asian countries contribute to the worst air quality and sustainability trends regions worldwide.

CONCLUSIONS

Air pollution is prevalent across a majority of South Asia countries. Owing to unsustainable industrial practices, pollution trends have risen to hazardous levels. Economic, environmental, and human health impacts have manifested and require urgent, concerted efforts by governing bodies in the region.

The effect of climate and air pollution on the development of complicated appendicitis

<b>Aim:</b> The aim of this study was to examine whether there is a relationship between complicated appendicitis and seasons, weekends, and air pollution. </br></br> <b> Materials and methods:</b> Patients who had undergone appendectomy in the last three years due to acute appendicitis were filtered from the database. Patients’ demographic features, date of the surgery, pathology reports, data on atmospheric temperatures, atmospheric pressure, relative humidity, and air pollution on the date of the surgery were collected and compared between complicated and non-complicated appendicitis groups. </br></br> <b>Results:</b> Out of 360 patients, 238 were men. The median age was 39 years for women and 29 years for men. Complicated appendicitis was seen in 78 (21.7%) patients, and the incidence rates were similar between the sexes (p = 0.69); this rate increased with increasing age (p = 0.001). The day of the week in which the surgery was performed (p = 0.55) and weekdays versus weekends (p = 0.16) did not change the complicated appendicitis incidence rate. This rate was similar among seasons (p = 0.44), temperature (p = 0.81), humidity (p = 0.62), and atmospheric pressure (p = 0.95). There was no difference between the groups for all noxious gases or PM2.5 levels, but for PM10 levels there was a significant difference (p = 0.045). In multivariate analysis, age (p = 0.001) and PM10 air pollution (p = 0.045) significantly affected the development of complicated appendicitis. </br></br> <b>Conclusions:</b> Air pollution of PM10 may have a real effect on the incidence of complicated appendicitis.

Liposomal SDF-1 Alpha Delivery in Nanocomposite Hydrogels Promotes Macrophage Phenotype Changes and Skin Tissue Regeneration

Skin regeneration in chronic wounds is often delayed due to persistent inflammation induced by underlying conditions such as diabetes. This effect is mediated, in part, by macrophages present in the wound, which can be stimulated to adopt either pro- or anti-inflammatory phenotypes depending on the status of the local microenvironment. In this work, the prohealing chemokine stromal cell-derived factor-1 alpha (SDF-1α) is controllably released from a hydrogel-based biomaterial to promote skin tissue regeneration and wound closure. This innovative nanocomposite hydrogel system releases liposomal stromal cell-derived factor-1 alpha (lipoSDF) as a new treatment approach for dorsal full-thickness skin wounds in wild-type and diabetic mice. Using this strategy, the recruitment and polarization of macrophages primarily of the anti-inflammatory phenotype were observed, along with a decreased amount of open wound surface area in diabetic mice after 28 days. This was accompanied by histological observations of increased epidermal stratification and dermal angiogenesis. These findings represent an important step of investigation distinctive in its field for developing immunomodulatory biomaterials that are able to influence macrophage phenotype and promote healing as hydrogel-based wound dressings.

Viral Respiratory Pathogens and Lung Injury

Several viruses target the human respiratory tract, causing different clinical manifestations spanning from mild upper airway involvement to life-threatening acute respiratory distress syndrome (ARDS). As dramatically evident in the ongoing SARS-CoV-2 pandemic, the clinical picture is not always easily predictable due to the combined effect of direct viral and indirect patient-specific immune-mediated damage. In this review, we discuss the main RNA (orthomyxoviruses, paramyxoviruses, and coronaviruses) and DNA (adenoviruses, herpesviruses, and bocaviruses) viruses with respiratory tropism and their mechanisms of direct and indirect cell damage. We analyze the thin line existing between a protective immune response, capable of limiting viral replication, and an unbalanced, dysregulated immune activation often leading to the most severe complication. Our comprehension of the molecular mechanisms involved is increasing and this should pave the way for the development and clinical use of new tailored immune-based antiviral strategies.

Identification of macrophage activation-related biomarkers in obese type 2 diabetes that may be indicative of enhanced respiratory risk in COVID-19

Hyperactivation of the immune system through obesity and diabetes may enhance infection severity complicated by Acute Respiratory Distress Syndrome (ARDS). The objective was to determine the circulatory biomarkers for macrophage activation at baseline and after serum glucose normalization in obese type 2 diabetes (OT2D) subjects. A case-controlled interventional pilot study in OT2D (n = 23) and control subjects (n = 23). OT2D subjects underwent hyperinsulinemic clamp to normalize serum glucose. Plasma macrophage-related proteins were determined using Slow Off-rate Modified Aptamer-scan plasma protein measurement at baseline (control and OT2D subjects) and after 1-h of insulin clamp (OT2D subjects only). Basal M1 macrophage activation was characterized by elevated levels of M1 macrophage-specific surface proteins, CD80 and CD38, and cytokines or chemokines (CXCL1, CXCL5, RANTES) released by activated M1 macrophages. Two potent M1 macrophage activation markers, CXCL9 and CXCL10, were decreased in OT2D. Activated M2 macrophages were characterized by elevated levels of plasma CD163, TFGβ-1, MMP7 and MMP9 in OT2D. Conventional mediators of both M1 and M2 macrophage activation markers (IFN-γ, IL-4, IL-13) were not altered. No changes were observed in plasma levels of M1/M2 macrophage activation markers in OT2D in response to acute normalization of glycemia. In the basal state, macrophage activation markers are elevated, and these reflect the expression of circulatory cytokines, chemokines, growth factors and matrix metalloproteinases in obese individuals with type 2 diabetes, that were not changed by glucose normalisation. These differences could potentially predispose diabetic individuals to increased infection severity complicated by ARDS.

Clinical trial reg. no: NCT03102801; registration date April 6, 2017.

IRAK-M knockout promotes allergic airway inflammation, but not airway hyperresponsiveness, in house dust mite-induced experimental asthma model

Background

IL-1 receptor associated-kinase (IRAK)-M, expressed by airway epithelium and macrophages, was shown to regulate acute and chronic airway inflammation exhibiting a biphasic response in an OVA-based animal model. House dust mite (HDM) is a common real-life aeroallergen highly relevant to asthma pathogenesis. The role of IRAK-M in HDM-induced asthma remains unknown. This study was aimed to investigate the effect of IRAK-M on allergic airway inflammation induced by HDM using IRAK-M knockout (KO) mice and the potential underlying mechanisms.

Methods

IRAK-M KO and wild-type (WT) mice were sensitized and challenged with HDM. The differences in airway inflammation were evaluated 24 hours after the last challenge between the two genotypes of mice using a number of cellular and molecular biological techniques. In vitro mechanistic investigation was also involved.

Results

Lung expression of IRAK-M was significantly upregulated by HDM in the WT mice. Compared with the WT controls, HDM-treated IRAK-M KO mice showed exacerbated infiltration of inflammatory cells, particularly Th2 cells, in the airways and mucus overproduction, higher epithelial mediators IL-25, IL-33 and TSLP and Th2 cytokines in bronchoalveolar lavage (BAL) fluid. Lung IRAK-M KO macrophages expressed higher percentage of costimulatory molecules OX40L and CD 80 and exhibited enhanced antigen uptake. However, IRAK-M KO didn’t impact the airway hyperreactivity (AHR) indirectly induced by HDM.

Conclusions

The findings indicate that IRAK-M protects allergic airway inflammation, not AHR, by modifying activation and antigen uptake of lung macrophages following HDM stimulation. Optimal regulation of IRAK-M might indicate an intriguing therapeutic avenue for allergic airway inflammation.

Environmental and Health Impacts of Air Pollution: A Review

One of our era's greatest scourges is air pollution, on account not only of its impact on climate change but also its impact on public and individual health due to increasing morbidity and mortality. There are many pollutants that are major factors in disease in humans. Among them, Particulate Matter (PM), particles of variable but very small diameter, penetrate the respiratory system via inhalation, causing respiratory and cardiovascular diseases, reproductive and central nervous system dysfunctions, and cancer. Despite the fact that ozone in the stratosphere plays a protective role against ultraviolet irradiation, it is harmful when in high concentration at ground level, also affecting the respiratory and cardiovascular system. Furthermore, nitrogen oxide, sulfur dioxide, Volatile Organic Compounds (VOCs), dioxins, and polycyclic aromatic hydrocarbons (PAHs) are all considered air pollutants that are harmful to humans. Carbon monoxide can even provoke direct poisoning when breathed in at high levels. Heavy metals such as lead, when absorbed into the human body, can lead to direct poisoning or chronic intoxication, depending on exposure. Diseases occurring from the aforementioned substances include principally respiratory problems such as Chronic Obstructive Pulmonary Disease (COPD), asthma, bronchiolitis, and also lung cancer, cardiovascular events, central nervous system dysfunctions, and cutaneous diseases. Last but not least, climate change resulting from environmental pollution affects the geographical distribution of many infectious diseases, as do natural disasters. The only way to tackle this problem is through public awareness coupled with a multidisciplinary approach by scientific experts; national and international organizations must address the emergence of this threat and propose sustainable solutions.

Soluble Fc-Disabled Herpes Virus Entry Mediator Augments Activation and Cytotoxicity of NK Cells by Promoting Cross-Talk between NK Cells and Monocytes

CD160 is highly expressed by NK cells and is associated with cytolytic effector activity. Herpes virus entry mediator (HVEM) activates NK cells for cytokine production and cytolytic function via CD160. Fc-fusions are a well-established class of therapeutics, where the Fc domain provides additional biological and pharmacological properties to the fusion protein including enhanced serum t 1/2 and interaction with Fc receptor-expressing immune cells. We evaluated the specific function of HVEM in regulating CD160-mediated NK cell effector function by generating a fusion of the HVEM extracellular domain with human IgG1 Fc bearing CD16-binding mutations (Fc*) resulting in HVEM-(Fc*). HVEM-(Fc*) displayed reduced binding to the Fc receptor CD16 (i.e., Fc-disabled HVEM), which limited Fc receptor-induced responses. HVEM-(Fc*) functional activity was compared with HVEM-Fc containing the wild type human IgG1 Fc. HVEM-(Fc*) treatment of NK cells and PBMCs caused greater IFN-γ production, enhanced cytotoxicity, reduced NK fratricide, and no change in CD16 expression on human NK cells compared with HVEM-Fc. HVEM-(Fc*) treatment of monocytes or PBMCs enhanced the expression level of CD80, CD83, and CD40 expression on monocytes. HVEM-(Fc*)-enhanced NK cell activation and cytotoxicity were promoted via cross-talk between NK cells and monocytes that was driven by cell-cell contact. In this study, we have shown that soluble Fc-disabled HVEM-(Fc*) augments NK cell activation, IFN-γ production, and cytotoxicity of NK cells without inducing NK cell fratricide by promoting cross-talk between NK cells and monocytes without Fc receptor-induced effects. Soluble Fc-disabled HVEM-(Fc*) may be considered as a research and potentially therapeutic reagent for modulating immune responses via sole activation of HVEM receptors.

IL-33 delays metastatic peritoneal cancer progression inducing an allergic microenvironment

Ovarian cancer is frequently diagnosed as peritoneal carcinomatosis. Unlike other tumor locations, the peritoneal cavity is commonly exposed to gut-breaching and ascending genital microorganisms and has a unique immune environment. IL-33 is a local cytokine that can activate innate and adaptive immunity. We studied the effectiveness of local IL-33 delivery in the treatment of cancer that has metastasized to the peritoneal cavity. Direct peritoneal administration of IL-33 delayed the progression of metastatic peritoneal cancer. Prolongation in survival was not associated with a direct effect of IL-33 on tumor cells, but with major changes in the immune microenvironment of the tumor. IL-33 promoted a significant increase in the leukocyte compartment of the tumor immunoenvironment and an allergic cytokine profile. We observed a substantial increase in the number of activated CD4⁺ T-cells accompanied by peritoneal eosinophil infiltration, B-cell activation and activation of peritoneal macrophages which displayed tumoricidal capacity. Depletion of CD4⁺ cells, eosinophils or macrophages reduced the anti-tumor effects of IL-33 but none of these alone were sufficient to completely abrogate its positive benefit. In conclusion, local administration of IL-33 generates an allergic tumor environment resulting in a novel approach for treatment of metastatic peritoneal malignancies, such as advanced ovarian cancer.

Aqueous and organic extract of PM2.5 collected in different seasons and cities of Japan differently affect respiratory and immune systems

Particulate matter with diameters <2.5 μm (i.e., PM_2.5) has multiple natural and anthropological sources. The association between PM_2.5 and the exacerbation of respiratory allergy and asthma has been well studied, but the components of PM_2.5 that are responsible for allergies have not yet been determined. Here, we elucidated the effects of aqueous and organic extract of PM_2.5 collected during four seasons in November 2014-December 2015 in two cities (Kawasaki, an industrial area and Fukuoka, an urban area affected by transboundary pollution matter) of Japan on respiratory health. Ambient PM_2.5 was collected by high-volume air samplers and extracted into water soluble and lipid soluble components. Human airway epithelial cells, murine bone marrow-derived antigen-presenting cells (APC) and splenocytes were exposed to PM_2.5 extracts. We measured the cell viability and release of interleukin (IL)-6 and IL-8 from airway epithelial cells, the DEC205 and CD86 expressions on APCs and cell proliferation, and TCR and CD19 expression on splenocytes. The water-soluble or aqueous extracts, especially those from Kawasaki in fall, had a greater cytotoxic effect than the lipid-soluble or organic extracts in airway epithelial cells, but they caused almost no pro-inflammatory response. Extract of fall, especially the aqueous extract from Fukuoka, increased the DEC205 and CD86 expressions on APC. Moreover, aqueous extracts of fall, summer, and spring from Fukuoka significantly increased proliferation of splenocytes. Organic extract of spring and summer from Kawasaki significantly elevated the TCR expression, and organic extract of summer from Kawasaki decreased the CD19 expression. These results suggest that PM_2.5 extract samples are responsible for cytotoxicity in airway epithelial cells and for activating APCs and T-cells, which can contribute to the exacerbation of respiratory diseases such as asthma. These effects can differ by PM_2.5 components, collection areas and seasons.

Characterization of adipose tissue macrophages and adipose-derived stem cells in critical wounds

Background

Subcutaneous adipose tissue is a rich source of adipose tissue macrophages and adipose-derived stem cells which both play a key role in wound repair. While macrophages can be divided into the classically-activated M1 and the alternatively-activated M2 phenotype, ASCs are characterized by the expression of specific stem cell markers.

Methods

In the present study, we have investigated the expression of common macrophage polarization and stem cell markers in acutely inflamed adipose tissue. Subcutaneous adipose tissue adjacent to acutely inflamed wounds of 20 patients and 20 healthy subjects were harvested and underwent qPCR and flow cytometry analysis.

Results

Expression levels of the M1-specific markers CD80, iNOS, and IL-1b were significantly elevated in inflammatory adipose tissue when compared to healthy adipose tissue, whereas the M2-specific markers CD163 and TGF-β were decreased. By flow cytometry, a significant shift of adipose tissue macrophage populations towards the M1 phenotype was confirmed. Furthermore, a decrease in the mesenchymal stem cell markers CD29, CD34, and CD105 was observed whereas CD73 and CD90 remained unchanged.

Discussion

This is the first report describing the predominance of M1 adipose tissue macrophages and the reduction of stem cell marker expression in acutely inflamed, non-healing wounds.

Bone marrow-derived and peritoneal macrophages have different inflammatory response to oxLDL and M1/M2 marker expression - implications for atherosclerosis research

Macrophages are heterogeneous and can polarize into specific subsets, e.g. pro-inflammatory M1-like and re-modelling M2-like macrophages. To determine if peritoneal macrophages (PEMs) or bone marrow derived macrophages (BMDMs) resembled aortic macrophages from ApoE-/- mice, their M1/M2 phenotype, inflammatory status, and lipid metabolism signatures were compared. oxLDL accumulation was similar in PEMs and BMDMs. On protein expression level, BMDMs showed an M2-like CD206^highCD11c^low profile, while cholesterol loading led to enhanced CD11c expression and reduced MCP-1 secretion. In contrast, PEMs expressed low levels of CD206 and CD11c, and responded to cholesterol loading by increasing CD11c expression and MCP-1 secretion. mRNA expression of M1/M2 markers was higher in PEMS than BMDMs, while lipid metabolism genes were similarly expressed. Whole aorta flow cytometry showed an accumulation of M2-like CD206^highCD11c^low macrophages in advanced versus early atherosclerotic disease in ApoE-/- mice. In isolated lesions, mRNA levels of the M2 markers Socs2, CD206, Retnla, and IL4 were downregulated with increasing disease severity. Likewise, mRNA expression of lipid metabolism genes (SREBP2, ACSL1, SRB1, DGAT1, and cpt1a) was decreased in advanced versus early lesions. In conclusion, PEMs and BMDMs are phenotypically distinct and differ from macrophages in lesions with respect to expression of M1/M2 markers and lipid metabolism genes.

Immunologic environment influences macrophage response to Porphyromonas gingivalis

Macrophages adapt both phenotypically and functionally to the cytokine balance in host tissue microenvironments. Recent studies established that macrophages contribute an important yet poorly understood role in the development of infection-elicited oral bone loss. We hypothesized that macrophage adaptation to inflammatory signals encountered before pathogen interaction would significantly influence the subsequent immune response of these cells to the keystone oral pathobiont Porphyromonas gingivalis. Employing classically activated (M1) and alternatively activated (M2) murine bone-marrow-derived macrophage (BMDMø), we observed that immunologic activation of macrophages before P. gingivalis challenge dictated phenotype-specific changes in the expression of inflammation-associated molecules important to sensing and tuning host response to bacterial infection including Toll-like receptors 2 and 4, CD14, CD18 and CD11b (together comprising CR3), major histocompatibility complex class II, CD80, and CD86. M2 cells responded to P. gingivalis with higher expression of tumor necrosis factor-α, interleukin-6, monocyte chemoattractant protein-1, macrophage inflammatory protein-1α, regulated on activation normal T cell expressed and secreted, and KC than M1 cells. M1 BMDMø expressed higher levels of interleukin-10 to P. gingivalis than M2 BMDMø. Functionally, we observed that M2 BMDMø bound P. gingivalis more robustly than M1 BMDMø. These data describe an important contribution of macrophage skewing in the subsequent development of the cellular immune response to P. gingivalis.

The role of airway macrophages in apoptotic cell clearance following acute and chronic lung inflammation

Acute and chronic inflammatory responses in the lung are associated with the accumulation of large quantities of immune and structural cells undergoing apoptosis, which need to be engulfed by phagocytes in a process called ‘efferocytosis’. Apoptotic cell recognition and removal from the lung is mediated predominantly by airway macrophages, though immature dendritic cells and non-professional phagocytes, such as epithelial cells and mesenchymal cells, can also display this function. Efficient clearance of apoptotic cells from the airways is essential for successful resolution of inflammation and the return to lung homeostasis. Disruption of this process leads to secondary necrosis of accumulating apoptotic cells, release of necrotic cell debris and subsequent uncontrolled inflammatory activation of the innate immune system by the released ‘damage associated molecular patterns’ (DAMPS). To control the duration of the immune response and prevent autoimmune reactions, anti-inflammatory signalling cascades are initiated in the phagocyte upon apoptotic cell uptake, mediated by a range of receptors that recognise specific phospholipids or proteins externalised on, or secreted by, the apoptotic cell. However, prolonged activation of apoptotic cell recognition receptors, such as the family of receptor tyrosine kinases Tyro3, Axl and MerTK (TAM), may delay or prevent inflammatory responses to subsequent infections. In this review, we will discuss recent advances in our understanding of the mechanism controlling apoptotic cell recognition and removal from the lung in homeostasis and during inflammation, the contribution of defective efferocytosis to chronic inflammatory lung diseases, such as chronic obstructive pulmonary disease, asthma and cystic fibrosis, and implications of the signals triggered by apoptotic cells in the susceptibility to pulmonary microbial infections.

Risk of idiopathic nephrotic syndrome among children with asthma: a nationwide, population-based cohort study

BACKGROUND

Although clinical and immunological studies have shown a possible link between allergy and idiopathic nephrotic syndrome (INS), the nature of the relationship remains unclear. Asthma is the most common chronic allergic airway inflammation. However, no study has used a longitudinal design with a population cohort to investigate INS in children with asthma.

METHODS

Using nationwide claims data from 2000 through 2007, we randomly selected 251,698 asthma cases and 1,006,791 frequency-matched controls. Incidence rates of INS and hazard ratios (HRs) were calculated.

RESULTS

The INS incidence was 3.36-fold greater in the asthma cohort than in the nonasthma control (9.26 vs. 2.76 per 100,000 person-years; 95% confidence interval (CI): 2.65-4.26). The HR for INS increased for those with more asthma-related medical visits per year, from 1.49 (95% CI: 1.06-2.11) for <3 visits to 15.7 (95% CI: 11.5-21.5) for ≥6 visits (trend test, P < 0.0001). The HR for INS slightly decreased during the follow-up period, from 3.41 (95% CI: 2.66-4.38) for ≤5.5 y to 2.90 (95% CI: 1.33-6.30) for >5.5 y.

CONCLUSION

We conclude that children with asthma had an increased incidence rate of INS, and increased incidence rate correlated with asthma-related medical visits.

Small interfering RNA against CD86 during allergen challenge blocks experimental allergic asthma

Background

CD86-CD28 interaction has been suggested as the principal costimulatory pathway for the activation and differentiation of naïve T cells in allergic inflammation. However, it remains uncertain whether this pathway also has an essential role in the effector phase. We sought to determine the contribution of CD86 on dendritic cells in the reactivation of allergen-specific Th2 cells.

Methods

We investigated the effects of the downregulation of CD86 by short interfering RNAs (siRNAs) on Th2 cytokine production in the effector phase in vitro and on asthma phenotypes in ovalbumin (OVA)-sensitized and -challenged mice.

Results

Treatment of bone marrow-derived dendritic cells (BMDCs) with CD86 siRNA attenuated LPS-induced upregulation of CD86. CD86 siRNA treatment impaired BMDCs’ ability to activate OVA-specific Th2 cells. Intratracheal administration of CD86 siRNA during OVA challenge downregulated CD86 expression in the airway mucosa. CD86 siRNA treatment ameliorated OVA-induced airway eosinophilia, airway hyperresponsiveness, and the elevations of OVA-specific IgE in the sera and IL-5, IL-13, and CCL17 in the bronchoalveolar lavage fluid, but not the goblet cell hyperplasia.

Conclusion

These results suggest that local administration of CD86 siRNA during the effector phase ameliorates lines of asthma phenotypes. Targeting airway dendritic cells with siRNA suppresses airway inflammation and hyperresponsiveness in an experimental model of allergic asthma.

Reduction of eotaxin production and eosinophil recruitment by pulmonary autologous macrophage transfer in a cockroach allergen-induced asthma model

We sought to investigate the effects of cockroach allergen (CRA) exposure on the lung macrophage population to determine how different macrophage phenotypes influence exacerbation of disease. CRA exposure caused significantly reduced expression of CD86 on lung macrophages. These effects were not systemic, as peritoneal macrophage CD86 expression was not altered. To investigate whether naïve macrophages could reduce asthma-like pulmonary inflammation, autologous peritoneal macrophages were instilled into the airways 24 h before the final CRA challenge. Pulmonary inflammation was assessed by measurement of airway hyperresponsiveness, mucin production, inflammatory cell recruitment, and cytokine production. Cell transfer did not have significant effects in control mice, nor did it affect pulmonary mucin production or airway hyperresponsiveness in control or CRA-exposed mice. However, there was significant reduction in the number of eosinophils recovered in the bronchoalveolar lavage (BAL) (5.8 × 10⁵ vs. 0.88 × 10⁵), and total cell recruitment to the airways of CRA-exposed mice was markedly reduced (1.1 × 10⁶ vs. 0.57 × 10⁶). The reduced eosinophil recruitment was reflected by substantially lower levels of eosinophil peroxidase in the lung and significantly lower concentrations of eotaxins in BAL (eotaxin 1: 3 pg/ml vs. undetectable; eotaxin 2: 2,383 vs. 131 pg/ml) and lung homogenate (eotaxin 1: 1,043 vs. 218 pg/ml; eotaxin 2: 10 vs. 1.5 ng/ml). We conclude that CRA decreases lung macrophage CD86 expression. Furthermore, supplementation of the lung cell population with peritoneal macrophages inhibits eosinophil recruitment, achieved through reduction of eotaxin production. These data demonstrate that transfer of naïve macrophages will reduce some aspects of asthma-like pulmonary inflammation in response to CRA.

Emerging role of chemokine receptor 7 in atherosclerosis

The CC chemokine receptor 7 (CCR7) and its ligands CCL19 and CCL21 essentially contribute to both immunity and tolerance by directing T cells and antigen-presenting dendritic cells (DCs) to and within lymph organs. In the pathogenesis of atherosclerosis, the accumulation of cholesterol in the subendothelial space of the vessel wall represents the initial step of plaque development in which DCs acquire and process low-density lipoprotein cholesterol as antigen in the vessel wall and then migrate to draining lymph nodes and present this antigen to naive T cells. Deletion of CCR7 receptor in murine atherosclerosis not only results in a reduced atherosclerotic plaque content but also leads to a disturbed entry and exit of T cells within the inflamed vessel wall. These observations are consistent with the notion that CCR7-dependent T cell priming in secondary lymphoid organs and CCR7-dependent recirculation of T cells between secondary lymphoid organs and inflamed tissue is pivotal for atherosclerotic plaque development and may represent an interesting target for innovative immune-modulatory therapy.

The alveolar macrophages in asthma: a double-edged sword

Asthma is a complex disease of the lungs, which is characterized by airway inflammation and airway hyperresponsiveness (AHR). Alveolar macrophages (AMs), one of the prominent immune system cells found in the airways, have been implicated in the development and progression of asthma. AMs constitute a unique subset of pulmonary macrophages, which serve as a first line of defense against foreign invaders to the lung tissue. In addition, based on human and animal studies, they have also been found to regulate pro- and anti-inflammatory responses in the airways, suggesting that these cells have a critical role in asthma. In this review, our focus is to evaluate the relevance of AMs in the context of asthma, and the underlying mechanisms that regulate their functions.

The microbiology of asthma

Asthma remains an important human disease that is responsible for substantial worldwide morbidity and mortality. The causes of asthma are multifactorial and include a complex mix of environmental, immunological and host genetic factors. In addition, epidemiological studies show strong associations between asthma and infection with respiratory pathogens, including common respiratory viruses such as rhinoviruses, human respiratory syncytial virus, adenoviruses, coronaviruses and influenza viruses, as well as bacteria (including atypical bacteria) and fungi. In this Review, we describe the many roles of microorganisms in the risk of developing asthma and in the pathogenesis of and protection against the disease, and we discuss the mechanisms by which infections affect the severity and prevalence of asthma.

Vitamin D3 deficiency increases sinus mucosa dendritic cells in pediatric chronic rhinosinusitis with nasal polyps

OBJECTIVE

Dendritic cells are professional antigen presenting cells, capable of initiating Th1 or Th2 responses, and have been implicated in the pathogenesis of a number of diseases, including sinusitis. Vitamin D(3) is a steroid hormone that acts on dendritic cells in a manner similar to corticosteroids. Investigators examined whether children with allergic fungal rhinosinusitis (AFRS) or chronic rhinosinusitis with nasal polyposis (CRSwNP) were vitamin D(3) deficient and the relationship of vitamin D(3) deficiency to dendritic cell infiltrate in the sinus mucosa.

SETTING

Tertiary care university hospital.

STUDY DESIGN

Retrospective, controlled study using samples collected from pediatric patients seen from August 2009 to July 2011.

SUBJECTS AND METHODS

Plasma levels of 25-hydroxy vitamin D(3) were measured by enzyme-linked immunosorbent assay in children (≤18 years old) with AFRS, CRSwNP, or CRS without nasal polyposis (CRSsNP) and in controls undergoing surgery for adenotonsillar hypertrophy. Vitamin D(3) levels were confirmed using clinical diagnostic methods for those with CRSwNP or AFRS. Tissue samples were immunohistochemically stained for the dendritic cell marker CD209 and the costimulatory molecules CD80 and CD86.

RESULTS

There was no difference in mean vitamin D(3) levels between control and CRSsNP, whereas mean CRSwNP and AFRS levels were both well below the minimum recommended level of 30 ng/mL and significantly lower than control and CRSsNP levels. CD209(+) dendritic cells inversely correlated with vitamin D(3) but not costimulatory molecule expression.

CONCLUSIONS

These studies identify that children with CRSwNP or AFRS are vitamin D(3) deficient, which may be linked to increased dendritic cell infiltrate. These results suggest a role for vitamin D(3) as a key player in the immunopathology of pediatric CRSwNP.

Trogocytosis of CD80 and CD86 by induced regulatory T cells

Trogocytosis is a process which involves the transfer of membrane fragments and cell surface proteins between cells. Various types of T cells have been shown to be able to acquire membrane-bound proteins from antigen-presenting cells and their functions can be modulated following trogocytosis. However, it is not known whether induced regulatory T cells (iTregs) can undergo trogocytosis, and if so, what the functional consequences of this process might entail. In this study, we show that iTregs can be generated from CD80(-/-)CD86(-/-) double knockout (DKO) mice. Using flow cytometry and confocal fluorescence microscopy, we demonstrate that iTregs generated from DKO mice are able to acquire both CD80 and CD86 from mature dendritic cells (mDCs) and that the acquisition of CD86 occurs to a higher extent than that of CD80. Furthermore, we found that after co-incubation with iTregs, dendritic cells (DCs) downregulate their surface expression of CD80 and CD86. The trogocytosis of both CD80 and CD86 occurs in a cytotoxic T lymphocyte-associated antigen-4 (CTLA-4), CD28 and programmed death ligand-1 (PDL1)-independent manner. Importantly, we showed that iTregs that acquired CD86 from mDCs expressed higher activation markers and their ability to suppress naive CD4(+) T-cell proliferation was enhanced, compared to iTregs that did not acquire CD86. These data demonstrate, for the first time, that iTregs can acquire CD80 and CD86 from mDCs, and the acquisition of CD86 may enhance their suppressive function. These findings provide novel understanding of the interaction between iTregs and DCs, suggesting that trogocytosis may play a significant role in iTreg-mediated immune suppression.

Comparison of two CD40-ligand/interleukin-2 vaccines in patients with chronic lymphocytic leukemia

BACKGROUND AIMS

Several studies have demonstrated that the immunogenicity of chronic lymphocytic leukemia (CLL) cells can be increased by manipulation of the CD40/CD40-ligand (CD40L) pathway. Although immunologic, and perhaps clinical, benefits have been obtained with an autologous CLL tumor vaccine obtained by transgenic expression of CD40L and interleukin (IL)-2, there is little information about the optimal gene transfer strategies.

METHODS

We compared two different CLL vaccines prepared by adenoviral gene transfer and plasmid electroporation, analyzing their phenotype and immunostimulatory activity.

RESULTS

We found that higher expression of transgenic CD40L was mediated by adenoviral gene transfer than by plasmid transduction, and that adenoviral transfer of CD40L was associated with up-regulation of the co-stimulatory molecules CD80 and CD86 and adhesion molecule CD54. In contrast, transgenic IL-2 secretion was greater following plasmid transduction. These phenotypic differences in the vaccines were associated with different functionality, both ex vivo and following administration to patients. Thus adenoviral vaccines induced greater activation of leukemia-reactive T cells ex vivo than plasmid vaccines. In treated patients, specific T-cell (T helper 1 (Th1) and T helper 2 (Th2)) and humoral anti-leukemia responses were detected following administration of the adenoviral vaccine (n = 15), while recipients of the plasmid vaccine (n = 9) manifested only a low-level Th2 response. Progression-free survival at 2 years was 46.7% in the adenoviral vaccine recipients, versus 11.1 % in those receiving plasmid vaccine.

CONCLUSIONS

CLL vaccines expressing the same transgenes but produced by distinct methods of gene transfer may differ in the polarity of the immune response they induce in patients.

Airway immune homeostasis and implications for influenza-induced inflammation

The lung is exposed to a myriad of innocuous antigens on a daily basis and must maintain a state of immune ignorance or tolerance to these harmless stimuli to retain pulmonary homeostasis and to prevent potentially fatal immunopathology. Here, we examine how, in the lower airways, resident cell populations contribute to the immune regulatory strategies that restrain inflammation. During influenza infection, these suppressive signals must be overcome to elicit a protective immune response that eliminates the virus. We also discuss how, after resolution of infection, the lung does not return to the original homeostatic state, and how the induced altered state can persist for long periods, which leaves the lung more susceptible to other infectious insults.

Structured regulation of inflammation during respiratory viral infection

Innate immune cells including macrophages, dendritic cells, and granulocytes are resident within or patrol very different microenvironments in the host. Their activity or responsiveness to antigen is dictated by site-specific factors. Because of the constant exposure to environmental antigens and commensal microorganisms, mucosal immunity needs to be more constrained than peripheral counterparts to prevent unnecessary inflammation. The epithelial surfaces that dominate all mucosal tissues provide an ideal regulator since innate immune cells are often in intimate contact with, or lie immediately beneath, them and a breach in epithelial integrity would signal a damaging event and release innate immunity from their influence. We discuss the role of the respiratory epithelium in raising the threshold of innate immune cell activation at homoeostasis, how its absence triggers innate immunity, and how inflammatory resolution often produces an altered homoeostatic environment that can affect the next inflammatory event at this site.

An in vitro study of the effect of size and timing of administration of titanium dioxide particles on antigen presenting activity of alveolar macrophages and peripheral blood monocytes

Previous studies have shown that inhaled particles exacerbate asthma and allergic rhinitis. Several factors related to the particle may play a role in immune-stimulating activity; however, the underlying mechanisms remain unclear. We carried out in vitro studies to investigate the effects of TiO(2) particle exposure on antigen presenting activity and expression of the associated cell-surface molecules (Ia, B7.1, B7.2) in rat derived monocytes and alveolar macrophages, in terms of two aspects of the particles: (1) size (59 nm (ST) and 350 nm (LT) particles), and (2) the timing of particle exposure (before antigen exposure or co-administered). Results indicated that particle exposure prior to antigen exposure led to decreased antigen presenting activity in both types of cell. This decrease was greater with ST particles. In monocytes, the expression of cell surface molecules decreased similarly with both particles. Conversely, alveolar macrophages showed greater expression of Ia with ST than with LT exposures. Ia expression was confirmed to be functionally active by a mixed lymphocyte reaction. It is possible that particle exposure might result in poor antigen processing, thereby leading to decreased antigen presenting activity. Co-exposure of particles and antigen induced an increase in antigen presenting activity with both types of particle; however, ST exposure induced greater antigen presenting activity. The expression of Ia also increased similarly with both particle sizes. This suggests that, in a co-exposure situation, antigen may be processed without intensive retardation by particles, and factors other than Ia may affect antigen presenting activity. In conclusion, both size and timing of exposure to TiO(2) particles affect antigen presenting activity of monocytes and alveolar macrophages.

Alveolar macrophages in allergic asthma: an expression signature characterized by heat shock protein pathways

The implication of alveolar macrophages (AM) in asthma, a T_h2 disease, has not been well characterized. Thus, the goal of this study is to better characterize AM phenotype of allergic asthmatic compared with normal subjects using genomic expression analyses. Microarray analyses were performed with AM isolated from bronchoalveolar lavage. Robust multiarray analysis (RMA) normalization and Smyth's moderated t test were used to select differentially expressed genes. Fifty differentially expressed genes were identified. Nineteen have been classified in categories linked to stress or immune responses and among them; nine are part of the heat shock protein (HSP) family. Difference of expression for three (HSPD1, PRNP, SERPINH1) of the five selected genes were validated using real-time reverse transcription–polymerase chain reaction. Enzyme-linked immunosorbent assay was used to measure the protein level of heat shock protein 60 (HSP60), the protein encoded by HSPD1, and showed difference in AM protein level between allergic asthmatic and control subjects. In summary, this study suggests that HSP gene family, particularly HSP60, is involved in AM functions in a context of allergic asthma. These results also support the involvement of AM immune functions in the development of an allergic asthmatic response.

Alveolar macrophage subpopulations in bronchoalveolar lavage and induced sputum of asthmatic and control subjects

BACKGROUND

Alveolar macrophages (AM) are the most numerous immune cells in the airways and are involved in the immunological homeostasis of the lung. Intriguingly, their role in asthma remains unclear probably, in part, because of their heterogeneity.

OBJECTIVE

To characterize AM population from bronchoalveolar lavage (BAL) and induced sputum (IS) of asthmatic and normal subjects using specific biomarkers.

METHODS

Non-asthmatic non-allergic and allergic mild asthmatic subjects were recruited for this study. AM were obtained from BAL and IS and cytospins were prepared. Immunocytochemistry was performed for nine cellular markers (CD68, RFD7, CD14, CD11b, CD83, CD64, CD80, CD86, and FIZZ1).

RESULTS

Asthmatic subjects had more AM RFD7(+) in BAL compared with IS, whereas control subjects had more AM RFD7(+) in IS than in BAL. Consequently, there was an increased number of AM RFD7(+) in BAL of asthmatic subjects compared with BAL of control subjects. AM CD11b(+) was higher in BAL than in IS in both groups. The expression of FIZZ1, marker of macrophage alternative activation, was similar in asthmatic and normal subjects.

CONCLUSION

The expression of cellular markers on AM differs according to their localization in the lung. Subpopulations of AM may contribute to the inflammatory profile observed in asthmatic subjects.

Immune homeostasis in the respiratory tract and its impact on heterologous infection

Innate immunity at mucosal surfaces requires additional restraint to prevent inflammation to innocuous antigens or commensal microorganisms. The threshold above which airway macrophages become activated is raised by site-specific factors including the receptors for transforming growth factor beta, interleukin 10 and CD200; the ligands for which are produced by, or expressed on, respiratory epithelium. We discuss such site-specific regulation and how this is continually altered by prior infections. Resetting of innate reactivity represents a strategy for limiting excessive inflammation, but in some may pre-dispose to secondary bacterial pneumonia.

Schistosoma mansoni infection alters co-stimulatory molecule expression and cell activation in asthma

Chronic schistosomiasis induces Th2/T regulatory responses which are able to down-modulate allergic inflammation and asthma. Because co-stimulatory molecules and IL-10 are essential for inducing tolerance, the aim of this study was to determine by flow cytometry, the expression of CD28, CTLA4, CD40L, CD80, CD86, HLA-DR, IL-10 and IL-10 receptor, by mononuclear cells from asthmatic individuals infected with Schistosoma mansoni and compare with non-infected individuals. Peripheral blood mononuclear cells were stained with fluorochrome conjugated antibodies for the expression of co-stimulatory molecules, and for intracellular CTLA4 and IL-10 expression. There was no significant difference in the frequency of T cells expressing CD28 between the two groups. However, the frequency of TCD4(+) cells expressing CTLA4 and CD40L was higher in infected asthmatics. The frequency of monocytes expressing CD80 and CD86 did not differ between groups, while the expression of HLA-DR and IL-10 receptor was higher on monocytes of infected individuals. Furthermore, monocytes and CD4(+)CD25(+) cells of infected individuals expressed higher levels of IL-10. We conclude that, besides alternatively-activated monocytes that are, together with CD4(+)CD25(+) cells, important sources of IL-10, CTLA4 and CD40L expression may also participate in the down-modulation of inflammatory allergic response in S. mansoni-infected asthmatics.

In vivo uptake of inhaled particles by airway phagocytes is enhanced in patients with mild asthma compared with normal volunteers

BACKGROUND

The uptake of inhaled particulate matter by airway phagocytes is an important defence mechanism contributing to the clearance of potentially toxic substances, including aeroallergens, from the lung. Since airway monocytes and macrophages can also function as antigen presenting cells, their ability to engulf materials deposited on the airway surface is of particular interest in patients with allergic asthma. To determine whether airway mononuclear phagocytes of patients with allergic asthma might have enhanced phagocytic activity, the in vivo uptake of inhaled radiolabelled particles was compared in 10 patients with mild allergic asthma and 8 healthy (non-allergic) individuals.

METHODS

Phagocyte function was assessed by quantifying the proportion of radioactivity associated with cellular and supernatant fractions of induced sputum 2 h after inhalation of radiolabelled sulfur colloid particles. All subjects were pretreated with albuterol before sputum induction. A standardised breathing pattern was used to target aerosol deposition in the bronchial airways.

RESULTS

In vivo particle uptake by airway cells was significantly greater in patients with asthma than in healthy volunteers (57.2% (95% CI 46.5% to 67.9%) vs 22.3% (95% CI 4.9% to 39.6%), p<0.01), as was in vitro phagocytosis of opsonised zymosan-A bioparticles. There was also a significant correlation (r = 0.85, p<0.01) between the percentage of sputum mononuclear phagocytes and the percentage uptake of particles in the patients with asthma but not in the control subjects.

CONCLUSIONS

In vivo particle uptake by airway macrophages is enhanced in persons with mild asthma. Enhanced uptake and processing of particulate antigens could contribute to the pathogenesis and progression of allergic airways disease and may contribute to the increased risk of disease exacerbation associated with particulate exposure.

Repetitive organic dust exposure in vitro impairs macrophage differentiation and function

BACKGROUND

Organic dust exposure in the agricultural industry results in significant airway disease and lung function decrease. Mononuclear phagocytes are key cells that mediate the inflammatory and innate immune response after dust exposure.

OBJECTIVE

We sought to investigate the effect of organic dust extract (ODE) from modern swine operations on monocyte-derived macrophage (MDM) phenotype and function.

METHODS

Peripheral blood monocytes were obtained by means of elutriation methodology (>99% CD14(+)) and differentiated into macrophages in the presence of GM-CSF (1 week) with and without ODE (0.1%). At 1 week, cells were analyzed by means of flow cytometry for cell-surface marker expression (HLA-DR, CD80, CD86, Toll-like receptor 2, Toll-like receptor 4, mCD14, and CD16), phagocytosis (IgG-opsonized zymosan particles), and intracellular killing of Streptococcus pneumoniae. At 1 week, MDMs were rechallenged with high-dose ODE (1%), LPS, and peptidoglycan (PGN), and cytokine levels (TNF-alpha, IL-6, IL-10, and CXCL8/IL-8) were measured. Comparisons were made to MDMs conditioned with heat-inactivated dust, endotoxin-depleted dust, LPS, and PGN to elucidate ODE-associated factors.

RESULTS

Expression of HLA-DR, CD80, and CD86; phagocytosis; and intracellular bacterial killing were significantly decreased with ODE-challenged versus control MDMs. Responses were retained after marked depletion of endotoxin. PGN, LPS, and PGN plus LPS significantly reduced MDM surface marker expression and, except for LPS alone, also reduced phagocytosis. ODE-challenged MDMs had significantly diminished cytokine responses (TNF-alpha, IL-6, and IL-10) after repeat challenge with high-dose ODE. Cross-tolerant cytokine responses were also observed.

CONCLUSION

Repetitive organic dust exposure significantly decreases markers of antigen presentation and host defense function in MDMs. Bacterial cell components appear to be driving these impaired responses.

Therapeutic effects of anti-B7-1 antibody in an ovalbumin-induced mouse asthma model

Allergic asthma is a chronic inflammatory disorder of airways, which is characterized by attacks provoked by exposure to so-called asthma triggers, such as pet dander, second-hand tobacco smoke, dust mites, and mold spores. B7-1 (CD80), perhaps one of the most studied co-stimulatory molecules involved in asthma, plays a key role in regulating allergen-induced T cell activation in asthma, probably through T cell recruitment and Th cell differentiation upon allergen provocation. The present study was designed to test the hypothesis that anti-B7-1 antibody has therapeutic effects in asthma by blocking B7-1/CD28 pathway. The asthma model was established by ovalbumin (OVA) sensitization and challenging in female Balb/c mice. One hour after the last induction, mice were sacrificed and whole lung lavage was conducted. Cell numbers in bronchoalveolar lavage fluid (BALF) were determined and the expression levels of IFN-gamma and IL-4 in supernatant were measured by an enzyme-linked immunosorbent assay method. Sedimental cells smears were stained with Wright's-Gimsa mixed coloring method. The B7-1 expression was detected by immunohistochemistry method with frozen tissue sections. The anti-B7-1 antibody treatment could alleviate asthmatic syndromes induced by OVA. The number of recoverable eosinophils in BALF in the anti-B7-1 antibody treated group was significantly lower than that in the control group (P<0.01) and the eosinophils peribronchial infiltration was remarkably reduced in anti-B7-1 treated asthmatic mice, based on histological evaluation. The treatment with the anti-B7-1 antibody induced IFN-gamma expression and decreased IL-4 expression, compared with the asthmatic control group (P<0.01). In conclusion, the anti-B7-1 antibody approach may provide a novel therapy for allergic asthma.

Respiratory infections: do we ever recover?

Although the outcome of respiratory infection alters with age, nutritional status, and immunologic competence, there is a growing body of evidence that we all develop a unique but subtle inflammatory profile. This uniqueness is determined by the sequence of infections or antigenic insults encountered that permanently mold our lungs through experience. This experience and learning process forms the basis of immunologic memory that is attributed to the acquired immune system. But what happens if the pathogen is not homologous to any preceding it? In the absence of cross-specific acquired immunity, one would expect a response similar to that of a subject who had never been infected with anything before. It is now clear that this is not the case. Prior inflammation in the respiratory tract alters immunity and pathology to subsequent infections even when they are antigenically distinct. Furthermore, the influence of the first infection is long lasting, not dependent on the presence of T and B cells, and effective against disparate pathogen combinations. We have used the term "innate imprinting" to explain this phenomenon, although innate education may be a closer description. This educational process, by sequential waves of infection, may be beneficial, as shown for successive viral infections, or significantly worse, as illustrated by the increased susceptibly to life-threatening bacterial pneumonia in patients infected with seasonal and pandemic influenza. We now examine what these long-term changes involve, the likely cell populations affected, and what this means to those studying inflammatory disorders in the lung.

Increase in concentration of soluble CD86 after segmental allergen challenge in patients with allergic asthma

STUDY OBJECTIVE

To investigate the effects of segmental allergen challenge on the concentration of soluble CD86 (sCD86) in BAL fluids in patients with allergic asthma.

METHODS

BAL fluid and peripheral blood were collected at baseline, 24 h after segmental saline solution or allergen challenge by fiberoptic bronchoscopy and venepuncture, respectively, from 10 patients with allergic asthma. Total and differential cell counts in BAL fluid were performed, and sCD86 levels in both BAL fluid and serum were measured by enzyme-linked immunosorbent assay.

RESULTS

In allergic asthmatics, there was no significant increase in BAL sCD86 concentrations after saline solution challenge (median, 2.0 IU/L; 25th to 75th percentiles, 0 to 3.4) compared with baseline control subjects (median, 1.2 IU/L; 25th to 75th percentiles, 0 to 3.6 IU/mL; p = 0.735); however, sCD86 concentrations were significantly elevated after allergen challenge (median, 8.1 IU/L; 25th to 75th percentiles, 4.4 to 17.0 IU/mL; p < 0.001). The concentrations of sCD86 in BAL fluid after allergen challenge exceeded levels that could be accounted for passive transudation from the circulation, based on the magnitude of increases in BAL albumin concentrations.

CONCLUSIONS

These data indicate that allergen challenge results in a significant local accumulation of sCD86 within the airways, and that the local release of sCD86 may play a role in allergen-induced inflammatory processes in the asthmatic airways.

Airway smooth muscle and asthma

The airway smooth muscle is the key determinant of airway narrowing in asthma but its function in the absence of disease is unknown. Evidence for an intrinsic abnormality in the muscle in asthma is only just emerging. The airway smooth muscle is not merely a contractile cell, but also one which determines the composition of, and interacts with the extracellular matrix, and which may participate in inflammatory and allergic reactions and viral infections. The reason for the differences which have been observed in the in vitro properties of airway smooth muscle derived from asthmatic individuals may result from an inherent "supercontractility", an increased tendency to proliferate due to the absence of an inhibitory transcription factor C/EBP-alpha, the influence of an altered extracellular matrix and/or a decrease in release of factors such as PGE(2) which would under normal circumstances inhibit both proliferation and contraction. Although long acting beta agonists and corticosteroids are successful treatments for inflammation and bronchoconstriction, the structural changes which constitute airway remodelling may require additional therapeutic intervention, the nature of which will be determined by thorough investigation of the mechanisms underlying the asthmatic phenotype.

Plasma concentrations of soluble CTLA-4, CD28, CD80 and CD86 costimulatory molecules reflect disease severity of acute asthma in children

Recent studies have demonstrated an elevation of plasma soluble costimulatory molecules B7.1 (CD80) and B7.2 (CD86), and their T lymphocyte counter receptors cytotoxic T lymphocyte associated antigen-4 (CTLA-4) and CD28 in asthmatic patients. We hypothesized that these costimulatory molecules may reflect the severity of asthma and investigated the longitudinal changes of these soluble costimulatory molecules, and their clinical significance in children with an asthmatic exacerbation. Sixteen children hospitalized for asthmatic exacerbation were recruited and treated with systemic corticosteroid (CS) for 5 days. Plasma total Immunoglobulin E (IgE) and eosinophil cationic protein (ECP) concentrations were measured by microparticle immunoassay and fluorescence enzyme immunoassay, respectively. Soluble CTLA-4 (sCTLA-4), sCD28, sCD80, and sCD86 concentrations in plasma were measured by enzyme-linked immunosorbent assay, and their relationships with asthma severity, total IgE, ECP concentrations, and blood eosinophil count were analyzed. Plasma sCTLA-4, sCD28, sCD80, and sCD86 concentrations in patients were highest during the acute attack. They decreased significantly with a parallel increase of peak expiratory flow rate (PEFR) after CS treatment (all P < 0.05). Plasma sCTLA-4, sCD28, and sCD86 concentrations of patients at recruitment were inversely correlated with PEFR, whereas plasma sCD28 and sCD86 concentrations correlated positively with eosinophil count and plasma ECP concentration (all P < 0.05). Although there was no such correlation with IgE concentration, sCD28 was correlated very significantly with eosinophil count (r = 0.83, P < 0.0001). In conclusion, plasma sCTLA-4, sCD28, sCD86, and sCD80 concentrations may reflect the severity of acute asthma and more studies on larger cohorts are needed to assess whether these markers are useful for assessing asthmatic exacerbation in children.

Protein tyrosine phosphatase 1B negatively regulates macrophage development through CSF-1 signaling

Protein tyrosine phosphatase 1B (PTP-1B) is a ubiquitously expressed cytosolic phosphatase with the ability to dephosphorylate JAK2 and TYK2, and thereby down-regulate cytokine receptor signaling. Furthermore, PTP-1B levels are up-regulated in certain chronic myelogenous leukemia patients, which points to a potential role for PTP-1B in myeloid development. The results presented here show that the absence of PTP-1B affects murine myelopoiesis by modifying the ratio of monocytes to granulocytes in vivo. This bias toward monocytic development is at least in part due to a decreased threshold of response to CSF-1, because the PTP-1B -/- bone marrow presents no abnormalities at the granulocyte-monocyte progenitor level but produces significantly more monocytic colonies in the presence of CSF-1. This phenomenon is not due to an increase in receptor levels but rather to enhanced phosphorylation of the activation loop tyrosine. PTP-1B -/- cells display increased inflammatory activity in vitro and in vivo through the constitutive up-regulation of activation markers as well as increased sensitivity to endotoxin. Collectively, our data indicate that PTP-1B is an important modulator of myeloid differentiation and macrophage activation in vivo and provide a demonstration of a physiological role for PTP-1B in immune regulation.

Alveolar macrophage function is altered in patients with lung cancer

The alveolar macrophage (AM) is believed to be of central importance in the immune response against infection and tumour. We examined patients with lung cancer in order to evaluate the immuno-stimulatory potential of AM in lung cancer. Bronchoalveolar lavage fluid samples were obtained from patients with adenocarcinoma, squamous cell carcinoma, large cell undifferentiated lung carcinoma, small cell carcinoma and control subjects. AM were isolated and phagocytic function, flow cytometry and cytokine analysis were assessed. AM from patients with small and squamous cell carcinoma had impaired uptake in vitro of 40 nm fluorescent polystyrene beads. AM from patients with small, squamous and large cell undifferentiated carcinoma showed impaired uptake of 1000 nm fluorescent polystyrene beads. Secreted levels of TNF-alpha and IL-1 from AM of patients with small, squamous, and large cell undifferentiated carcinoma were decreased compared to controls. Secreted AM IL-6 levels were decreased in small and large cell undifferentiated carcinoma. AM from adenocarcinoma patients showed similar levels of IL-10, IL-6, IL-1 and TNF-alpha compared to controls. Phenotypic analysis demonstrated that patients with small cell carcinoma were the only group that showed a decrease in MHC class II surface expression. Surface expression of ICAM-1 and CD83 was decreased on AM from patients with large, squamous and small cell carcinoma compared to controls but not adenocarcinoma. Mannose receptor levels were only decreased on AM from patients with squamous and small cell carcinoma but not adenocarcinoma and large cell undifferentiated carcinoma. We conclude that there are type-specific alterations in uptake ability, cytokine secretion and phenotype of AM from lung cancer patients, which may result in an inability to stimulate anti-tumour immunity. The observed differences between lung cancer subgroups may explain previously reported inconsistencies in descriptions of AM characteristics in lung cancer.

CD28/CTLA-4--CD80/CD86 and ICOS--B7RP-1 costimulatory pathway in bronchial asthma

Costimulatory molecules are cell surface glycoproteins that can direct, modulate and fine-tune T-cell receptor signals. The B7-1/B7-2--CD28/CTLA-4 and ICOS-B7RP-1 pathway provides key second signals that can regulate the activation, inhibition and fine-tuning of T-lymphocyte responses. The expression of B7-1/B7-2--CD28/CTLA-4 molecules on clinical samples from patients with asthma have been well studied, and the results indicate that different extents of these molecules are expressed on the surface of various cells, and that the concentrations of soluble form of these molecules are elevated in the sera of patients with asthma. There is a burst of papers describing an important role for B7-1/B7-2--CD28/CTLA-4 pathway in the Th1/Th2 balance. Similarly, ICOS stimulates both Th1 and Th2 cytokine production but may have a preferential role in Th2 cell development. Moreover, The B7-1/B7-2-CD28/CTLA-4 and ICOS-B7RP-1 pathway has been suggested of being involved in the development of airway inflammation and airway hyperresponsiveness. Further study of the functions of the pathways within the CD28/CTLA-4--CD80/CD86 and ICOS--B7RP-1 superfamily individually and their interplay should provide insights into the pathogenesis of asthma, and has great therapeutic potential for treatment of asthma.

Anti-CD23 monoclonal antibody, lumiliximab, inhibited allergen-induced responses in antigen-presenting cells and T cells from atopic subjects

BACKGROUND

CD23 plays a role in the regulation of IgE production and allergy-induced immune and inflammatory responses. A novel anti-CD23 monoclonal antibody, lumiliximab, is a potential therapeutic antibody recently demonstrated to be safe in human beings.

OBJECTIVE

This study investigated the effects of lumiliximab on allergen-induced immune responses from atopic subjects compared with blocking HLA-DR and costimulatory molecules, CD80 and CD86.

METHODS

Allergen-stimulated PBMCs from atopic subjects were pretreated with lumiliximab or antibodies to CD80, CD86, and HLA-DR. Cultures were analyzed for cell proliferation and IL-1beta, TNF-alpha, and IL-5 cytokine secretion. An allergen-specific T-cell line was developed and analyzed for lymphocyte proliferation in response to allergen with or without lumiliximab. Lumiliximab's effect on CD86 expression was evaluated by flow cytometry in the U937 monocytic cell line.

RESULTS

Lumiliximab reduced allergen-induced PBMC proliferation by 50% (n = 6; P = .006). In addition, cultures pretreated with lumiliximab had a reduction in the proinflammatory cytokines IL-1beta (P < .003) and TNF-alpha (P = .05) and the T(H)2 cytokine IL-5 (P = .002). Blocking CD86 resulted in greater reduction in proliferation than lumiliximab (P = .003) but similar effects in cytokine secretion. The anti-CD80 blocking antibody had no effect on cytokine production but did reduce proliferation. Furthermore, the addition of lumiliximab to cytokine stimulated U937 cells reduced surface expression of CD86 (P = .012).

CONCLUSION

These results indicate that the anti-CD23 mAb, lumiliximab, may be involved in modulating antigen presenting cells and reducing TH2-type immune responses. The use of this antibody may provide clinical benefit for treating allergic diseases.

Increased expression of plasma and cell surface co-stimulatory molecules CTLA-4, CD28 and CD86 in adult patients with allergic asthma

The co-stimulatory interactions of the B7 family molecules CD80 and CD86 on antigen-presenting cells, together with their T cell counter receptors CD28 and cytotoxic T lymphocyte-associated antigen-4 (CTLA-4), modulate T lymphocyte-mediated immune responses in a reciprocal manner. To investigate whether there is altered expression and the clinical significance of soluble co-stimulatory molecules in asthmatic patients, plasma concentrations of sCTLA-4, sCD28, sCD80 and sCD86 in 51 adult allergic asthmatic adults with or without steroid treatment, and 35 sex- and age-matched control subjects were measured by enzyme-linked immunosorbent assay (ELISA). Cell surface expression of CTLA-4 and CD28 on peripheral blood mononuclear cells (PBMC) were analysed by flow cytometry. Results showed that the plasma sCTLA-4 concentration was significantly higher in all asthmatic patients while sCD28 and sCD86 concentrations were significantly higher in steroid and non-steroid treated asthmatic patients, respectively, compared with control subjects (all P < 0.01). Significantly increased cell surface expression of CD28 but not CTLA-4 on PBMC was found in asthmatic patients compared with controls (P < 0.05). The plasma concentration and cell surface expression of CTLA-4 were found to exhibit positive and significant correlations with those of CD28 (both P < 0.05). Serum total IgE concentration correlated positively and significantly with sCTLA-4 and sCD28 concentrations in allergic asthmatic patients (both P < 0.05). The increased expression of these soluble co-stimulatory molecules may reflect the dysregulation of T cell activation, thereby contributing to the immunopathogenesis of allergic asthma.

Elevation of plasma soluble T cell costimulatory molecules CTLA-4, CD28 and CD80 in children with allergic asthma

BACKGROUND

The surface expression of T cell costimulatory molecules CTLA-4 and CD28 and their counter-ligands, B7 molecules (CD80, CD86), is differentially induced for T cell activation and expansion in allergic asthma. However, the role of their soluble forms in plasma has not yet been elucidated. In this study, we investigated whether expression is altered and whether soluble costimulatory molecules are clinically relevant in asthmatic patients.

METHODS

Plasma concentrations of soluble CTLA-4 (sCTLA-4), CD28, CD80 and CD86 in 51 children with chronic allergic asthma with or without inhaled corticosteroid treatment, and 22 sex- and age-matched control subjects were measured by enzyme-linked immunosorbent assay. Plasma total IgE concentration was measured using a microparticle immunoassay.

RESULTS

Asthmatic patients had higher logarithmic plasma total IgE concentration (IgE(log)) than healthy subjects (p < 0.0001). In non-steroid-treated patients, plasma sCTLA-4, sCD28 and sCD80 but not sCD86 concentrations were significantly higher than those of control subjects (all p < 0.05). Plasma sCD80 and sCD86 but not sCTLA-4 and sCD28 concentrations correlated significantly with IgE(log) of all subjects (p < 0.05). There were also significant positive correlations between sCTLA-4 and sCD28 (p = 0.0007), and between sCD80 and sCD86 in all asthmatic patients (p = 0.001).

CONCLUSIONS

Plasma sCTLA-4, sCD28 and sCD80 concentrations are elevated in allergic asthma. The increased expression of these soluble proteins may reflect the dysregulation of T cell activation, contributing to the immunopathogenesis of allergic asthma.

B7-DC regulates asthmatic response by an IFN-gamma-dependent mechanism

B7-H1 (PD-L1) and B7-DC (PD-L2) are the ligands for programmed death-1 (PD-1), which is a member of the CD28/CTLA-4 family and has been implicated in peripheral tolerance. We investigated the roles of B7-H1 and B7-DC in a murine OVA-induced allergic asthma model. B7-H1 was constitutively expressed on dendritic cells, macrophages, B cells, and T cells in the lungs of naive mice, and its expression could be dramatically increased after allergen challenge. In contrast, B7-DC expression was scarcely expressed on dendritic cells in naive mice, but was up-regulated after allergen challenge, although the up-regulation of B7-DC expression on macrophages was minimal. Treatment of mice with anti-B7-DC mAb at the time of allergen challenge, but not at the time of sensitization, significantly increased their airway hyper-reactivity and eosinophilia. Such treatment also resulted in the increased production of IL-5 and IL-13, and decreased IFN-gamma production in the lungs and draining lymph node cells. These changes were diminished when mice were depleted of IFN-gamma by anti-IFN-gamma mAb pretreatment. Interestingly, treatment with anti-B7-H1 or anti-PD-1 mAb did not significantly affect the asthmatic response. These results suggest a unique role for B7-DC in the regulation of asthmatic response through an IFN-gamma-dependent, but PD-1-independent, mechanism.