Lymphocytes in the bronchoalveolar space reenter the lung tissue by means of the alveolar epithelium, migrate to regional lymph nodes, and subsequently rejoin the systemic immune system

Stem cell treatment reduces T cell apoptosis in COPD patients with chronic bronchitis but not with emphysema

BACKGROUND

Chronic obstructive pulmonary disease (COPD) is a prevalent and preventable condition. Mesenchymal stem cell (MSC) therapy is being explored to aid in the regeneration of lung cells and airway structure, aiming to restore lung function.

AIM

To examine varied responses of MSCs when cultured with peripheral blood mononuclear cells (PBMCs) from different COPD phenotypes, patients were grouped into ACOS, emphysema, and chronic bronchitis categories.

METHODS

PBMCs from these groups and controls were co-cultured with MSCs derived from dental follicles, revealing differing rates of apoptosis among COPD phenotypes compared to controls.

RESULTS

While the chronic bronchitis group exhibited the least lymphocyte viability (p<0.01), introducing MSCs notably enhanced viability across all phenotypes except emphysema, with the chronic bronchitis group showing the most improvement (p<0.05).

CONCLUSION

Stem cell therapy might reduce peripheral lymphocyte apoptosis in COPD, with varying responses based on phenotype, necessitating further research to understand mechanisms and optimize tailored therapies for each COPD subtype.

LFA-1/ICAM-1 Adhesion Pathway Mediates the Homeostatic Migration of Lymphocytes from Peripheral Tissues into Lymph Nodes through Lymphatic Vessels

Lymphocyte function-associated antigen-1 (LFA-1) and its endothelial ligand intercellular adhesion molecule-1 (ICAM-1) are important for the migration of lymphocytes from blood vessels into lymph nodes. However, it is largely unknown whether these molecules mediate the homeostatic migration of lymphocytes from peripheral tissues into lymph nodes through lymphatic vessels. In this study, we find that, in naive mice, ICAM-1 is expressed on the sinus endothelia of lymph nodes, but not on the lymphatic vessels of peripheral tissues. In in vivo lymphocyte migration assays, memory CD4+ T cells migrated to lymph nodes from peripheral tissues much more efficiently than from blood vessels, as compared to naive CD4+ T cells. Moreover, ICAM-1 deficiency in host mice significantly inhibited the migration of adoptively transferred wild-type donor lymphocytes from peripheral tissues, but not from blood vessels, into lymph nodes. The migration of LFA-1-deficient donor lymphocytes from peripheral tissues into the lymph nodes of wild-type host mice was also significantly reduced as compared to wild-type donor lymphocytes. Furthermore, the number of memory T cells in lymph nodes was significantly reduced in the absence of ICAM-1 or LFA-1. Thus, our study extends the functions of the LFA-1/ICAM-1 adhesion pathway, indicating its novel role in controlling the homeostatic migration of lymphocytes from peripheral tissues into lymph nodes and maintaining memory T cellularity in lymph nodes.

Low-Blood Lymphocyte Number and Lymphocyte Decline as Key Factors in COPD Outcomes: A Longitudinal Cohort Study

BACKGROUND

Smokers with and without chronic obstructive pulmonary disease (COPD) are at risk of severe outcomes like exacerbations, cancer, respiratory failure, and decreased survival. The mechanisms for these outcomes are unclear; however, there is evidence that blood lymphocytes (BL) number might play a role.

OBJECTIVE

The objective of this study is to investigate the relationship between BL and their possible decline over time with long-term outcomes in smokers with and without COPD.

METHODS

In 511 smokers, 302 with COPD (COPD) and 209 without COPD (noCOPD), followed long term, we investigated whether BL number and BL decline over time might be associated with long-term outcomes. Smokers were divided according to BL number in high-BL (≥1,800 cells/µL) and low-BL (<1,800 cells/µL). Clinical features, cancer incidence, and mortality were recorded during follow-up. BL count in multiple samples and BL decline over time were calculated and related to outcomes.

RESULTS

BL count was lower in COPD (1,880 cells/µL) than noCOPD (2,300 cells/µL; p < 0.001). 43% of COPD and 23% of noCOPD had low-BL count (p < 0.001). BL decline over time was higher in COPD than noCOPD (p = 0.040). 22.5% of the whole cohort developed cancer which incidence was higher in low-BL subjects and in BL decliners than high-BL (31 vs. 18%; p = 0.001) and no decliners (32 vs. 19%; p = 0.002). 26% in the cohort died during follow-up. Furthermore, low-BL count, BL decline, and age were independent risk factors for mortality by Cox regression analysis.

CONCLUSION

BL count and BL decline are related to worse outcomes in smokers with and without COPD, which suggests that BL count and decline might play a mechanistic role in outcomes deterioration. Insights into mechanisms inducing the fall in BL count could improve the understanding of COPD pathogenesis and point toward new therapeutic measures.

Experimental challenge with bovine respiratory syncytial virus in dairy calves: bronchial lymph node transcriptome response

Bovine Respiratory Disease (BRD) is the leading cause of mortality in calves. The objective of this study was to examine the response of the host’s bronchial lymph node transcriptome to Bovine Respiratory Syncytial Virus (BRSV) in a controlled viral challenge. Holstein-Friesian calves were either inoculated with virus (10^3.5 TCID₅₀/ml × 15 ml) (n = 12) or mock challenged with phosphate buffered saline (n = 6). Clinical signs were scored daily and blood was collected for haematology counts, until euthanasia at day 7 post-challenge. RNA was extracted and sequenced (75 bp paired-end) from bronchial lymph nodes. Sequence reads were aligned to the UMD3.1 bovine reference genome and differential gene expression analysis was performed using EdgeR. There was a clear separation between BRSV challenged and control calves based on gene expression changes, despite an observed mild clinical manifestation of the disease. Therefore, measuring host gene expression levels may be beneficial for the diagnosis of subclinical BRD. There were 934 differentially expressed genes (DEG) (p < 0.05, FDR <0.1, fold change >2) between the BRSV challenged and control calves. Over-represented gene ontology terms, pathways and molecular functions, among the DEG, were associated with immune responses. The top enriched pathways included interferon signaling, granzyme B signaling and pathogen pattern recognition receptors, which are responsible for the cytotoxic responses necessary to eliminate the virus.

An Increased Proportion of Apoptosis in CD4⁺ T Lymphocytes Isolated from the Peripheral Blood in Patients with Stable Chronic Obstructive Pulmonary Disease

BACKGROUND

The pathophysiology of chronic obstructive pulmonary disease (COPD) includes inflammation, oxidative stress, an imbalance of proteases and antiproteases and apoptosis which has been focused on lately. Abnormal apoptotic events have been demonstrated in both epithelial and endothelial cells, as well as in inflammatory cells including neutrophils and lymphocytes in the lungs of COPD patients. An increased propensity of activated T lymphocytes to undergo apoptosis has been observed in the peripheral blood of COPD patients. Therefore, the apoptosis of T lymphocytes without activating them was investigated in this study.

METHODS

Twelve control subjects, 21 stable COPD patients and 15 exacerbated COPD patients were recruited in the study. The T lymphocytes were isolated from the peripheral blood using magnetically activated cell sorting. Apoptosis of the T lymphocytes was assessed with flow cytometry using Annexin V and 7-aminoactinomycin D. Apoptosis of T lymphocytes at 24 hours after the cell culture was measured so that the T lymphocyte apoptosis among the control and the COPD patients could be compared.

RESULTS

Stable COPD patients had increased rates of CD4⁺ T lymphocyte apoptosis at 24 hours after the cell culture, more than the CD4⁺ T lymphocyte apoptosis which appeared in the control group, while the COPD patients with acute exacerbation had an amplified response of CD4⁺ T lymphocyte apoptosis as well as of CD8⁺ T lymphocyte apoptosis at 24 hours after the cell culture.

CONCLUSION

Stable COPD patients have more apoptosis of CD4⁺ T lymphocytes, which can be associated with the pathophysiology of COPD in stable conditions.

Blood cytotoxic/inflammatory mediators in non-eosinophilic asthma

BACKGROUND

Non-eosinophilic asthma (NEA) is a distinct, often corticosteroid-resistant inflammatory asthma phenotype. NK and NKT-like cells are effector lymphocytes that we have shown, like CD28null T cells, to be relatively resistant to steroids and major sources of pro-inflammatory/cytotoxic mediators. We hypothesized that these cells and mediators would be increased in peripheral blood in NEA.

METHODS

Adults with severe asthma and variable airflow obstruction, poorly controlled despite maintenance therapy with inhaled glucocorticosteroids and long-acting bronchodilators, were recruited. Blood was assessed in those with eosinophilic asthma (n = 12), NEA (n = 25) and healthy non-smoking controls (n = 30). We applied flow cytometry to measure T, CD28null, NK and NKT-like cells and their expression of granzyme B, perforin, and killer inhibitory/activating receptors CD94(Kp43), CD158b and CD107A. Intracellular pro-inflammatory cytokine production (IFN-γ and TNF-α) was assessed in 18 controls and 10 patients with asthma/group.

RESULTS

In NEA, there was increased expression of granzyme B by CD8+ T cells vs.

CONTROLS

There was increased expression of granzyme B and CD158 and decreased CD94 on NK cells, vs. healthy controls and those with eosinophilic asthma. IFN-γ production by NK cells and TNF-α production by NKT-like cells in NEA were significantly increased vs.

CONTROLS

In both eosinophilic and NEA phenotypes, there were significant increases in CD4+28null T cells (72% and 81% increases, respectively, vs. controls) and their expression of pro-inflammatory cytokines. Significant correlations were noted between blood CD4+28null T cells and neutrophil numbers in induced sputum, and between corticosteroid dose and blood NKT-like cells, and their production of granzyme B and TNF-α and NK IFN-γ.

CONCLUSION AND CLINICAL RELEVANCE

In poorly controlled asthma, altered expression of cytotoxic/pro-inflammatory mediators can be seen on a variety of lymphocyte subsets in the peripheral blood; these changes are most apparent in NEA. Whether this pattern of expression is a marker of treatment responsiveness and future risk of exacerbations remains to be determined.

In vitro modeling of COPD inflammation and limitation of p38 inhibitor - SB203580

Background

Systemic inflammation and steroid resistance are the hallmarks of COPD. We examined the impact of p38 inhibitor (SB203580) in in vitro assays of systemic inflammation using pulmonary cells and patients’ sera.

Objective and methods

Data from 66 COPD patients and 15 age-/sex-matched healthy controls were compared. Interleukin-10 (IL-10), tumor necrosis factor-α (TNF-α), and CCL5 were measured in serum samples and culture media from peripheral blood mononuclear cells. The impact of sera on IL-10 and CCL5 expression in alveolar macrophage cell line (MH-S) was examined. The in vitro effects of SB203580 on lipopolysaccharide-induced inflammation were investigated.

Results

Peripheral blood mononuclear cells from Global initiative for chronic Obstructive Lung Disease (GOLD) D patients produced more CCL5 and TNF-α, and less IL-10 compared to GOLD A–C patients. SB203580 treatment suppressed CCL5 and TNF-α and stimulated IL-10 production; however, the effect of SB203580 on IL-10 was lower in the COPD group. Culture of MH-S cells with COPD serum showed a significant increase in CCL5 and a significant decrease in IL-10 compared to healthy serum. This effect was not suppressed with SB203580 treatment.

Conclusion

COPD serum has a potent proinflammatory effect on pulmonary cells. Inhibition of p38 phoshorylation had a limited effect in restoring impaired lymphocyte function and suppressing inflammation induced by COPD serum, implying important p38-independent inflammatory mechanisms in COPD.

Targeting peripheral blood pro-inflammatory cytotoxic lymphocytes by inhibiting CD137 expression: novel potential treatment for COPD

Background

We have shown that chronic obstructive pulmonary disease (COPD) is associated with increased production of pro-inflammatory cytokines and the cytotoxic mediator, granzyme B by peripheral blood steroid resistant CD28nullCD137 + CD8+ T cells and granzyme B by NKT-like and NK cells. We hypothesized that we could target these pro-inflammatory/cytotoxic lymphocytes by inhibiting co-stimulation through CD137.

Methods

Isolated PBMC from patients with COPD and healthy controls were stimulated with phytohaemagglutinin (PHA) ± blocking anti-CD137 ± 10^-6 M methylprednislone (MP) (±stimulatory anti-CD137 ± control antibodies). Pro-inflammatory cytokine profiles and expression of granzyme B, by T, NKT-like CD28 ± subsets and NK cells were determined using flow cytometry.

Results

There was a significant decrease in the percentage of T, NKT-like subsets and NK cells producing IFNγ, TNFα and granzyme B in all subjects in the presence of anti-CD137 blocking antibody compared with PHA alone (eg, 60% decrease in CD8 + granzyme B + cells) or MP. Stimulatory anti-CD137 was associated with an increase in the percentage of pro-inflammatory/cytotoxic cells. The inhibitory effect of anti-CD137 on IFNγ, TNFα and granzyme B production by CD28null cells was greater than by CD28+ cells.

Conclusions

Blocking CD137 expression is associated with downregulation of IFNγ, TNFα and granzyme B by CD8+ T and NKT-like and NK cells. Targeting CD137 may have novel therapeutic implications for patients with COPD.

Targeting peripheral blood pro-inflammatory CD28null T cells and natural killer T-like cells by inhibiting CD137 expression: possible relevance to treatment of bronchiolitis obliterans syndrome

BACKGROUND

We have shown that bronchiolitis obliterans syndrome (BOS) is associated with attenuated suppression of pro-inflammatory cytokines and granzyme B by steroid-resistant peripheral blood CD28nullCD137+ T cells and natural killer T (NKT)-like cells. We hypothesized that we could target these steroid-resistant lymphocytes by inhibiting costimulation through CD137.

METHODS

Isolated peripheral blood mononuclear cells from transplant patients with stable lung function, patients with BOS, and healthy controls were stimulated with anti-CD3 with and without blocking anti-CD137 and with and without 10(-6) mol/liter methylprednisolone (MP) (with and without stimulatory anti-CD137). Pro-inflammatory cytokine profiles and expression of the cytotoxic mediator, granzyme B, by CD28null T and NKT-like cells were determined using flow cytometry.

RESULTS

There was a significant decrease in the percentage of CD28null T and NKT-like cells producing interferon (IFN)-γ, tumor necrosis factor (TNF)-α, and granzyme B in all individuals in the presence of anti-CD137 blocking antibody compared with anti-CD3 alone (eg, 30% decrease in CD8+CD28null TNF-α+ cells). Stimulatory anti-CD137 was associated with an increase in pro-inflammatory/cytotoxic cells. Treatment with anti-CD137 blocking with prednisolone further reduced IFN-γ, TNF-α, and granzyme B in these cells.

CONCLUSIONS

Blocking CD137 expression in CD28null T cells and NKT-like cells is associated with down-regulation of IFN-γ, TNF-α, and granzyme B. Targeting CD137 reduces pro-inflammatory/cytotoxic expression in steroid-resistant CD28null T and NKT-like cells and may have therapeutic implications for patients with BOS.

Up-regulation of alternate co-stimulatory molecules on proinflammatory CD28null T cells in bronchiolitis obliterans syndrome

Bronchiolitis obliterans syndrome (BOS) is associated with lack of immunosuppression of T cell proinflammatory cytokines and increased T cell granzyme B. Repeated antigen-driven proliferation down-regulates T cell CD28. We hypothesized that down-regulation of CD28 and up-regulation of alternate co-stimulatory molecules (CD134, CD137, CD152 and CD154) on T cells may be associated with BOS. Co-stimulatory molecules, granzyme B, perforin and intracellular cytokines were measured by flow cytometry on T cells from stable lung transplant patients (n = 38), patients with BOS (n = 20) and healthy controls (n = 10). There was a significant increase in the percentage of CD4/28(null) and CD8/28(null) T cells producing granzyme B, interferon (IFN)-γ and tumour necrosis factor (TNF)-α in BOS compared with stable patients. Down-regulation of CD28 was associated with steroid resistance and up-regulation of CD134, CD137, CD152 and CD154 on CD4(+) T cells and CD137 and CD152 on CD8(+) T cells. There was a significant correlation between increased CD28(null) /CD137 T cells producing IFN-γ, TNF-α with BOS grade (r = 0·861, P < 0·001 for CD28(null) /CD137 IFN-γ/CD8) and time post-transplant (r = 0·698, P < 0·001 for CD28(null) /CD137 IFN-γ/CD8). BOS is associated with down-regulation of CD28 and up-regulation of alternate co-stimulatory molecules on steroid-resistant peripheral blood proinflammatory CD4(+) and CD8(+) T cells. Therapeutic targeting of alternate co-stimulatory molecules on peripheral blood CD28(null) T cells and monitoring response using these assays may help in the management of patients with BOS.

Tissue exit: a novel control point in the accumulation of antigen-specific CD8 T cells in the influenza a virus-infected lung

Memory/effector T cells efficiently migrate into extralymphoid tissues and sites of infection, providing immunosurveillance and a first line of defense against invading pathogens. Even though it is a potential means to regulate the size, quality, and duration of a tissue infiltrate, T cell egress from infected tissues is poorly understood. Using a mouse model of influenza A virus infection, we found that CD8 effector T cells egressed from the infected lung in a CCR7-dependent manner. In contrast, following antigen recognition, effector CD8 T cell egress decreased and CCR7 function was reduced in vivo and in vitro, indicating that the exit of CD8 T cells from infected tissues is tightly regulated. Our data suggest that the regulation of T cell egress is a mechanism to retain antigen-specific effectors at the site of infection to promote viral clearance, while decreasing the numbers of bystander T cells and preventing overt inflammation.

Wild-Type Measles Virus is Intrinsically Dual-Tropic

Measles is a highly contagious disease that causes temporary and severe immunosuppression in patients. Signaling lymphocyte activation molecule (SLAM) expressed on cells of the immune system functions as a receptor for measles virus (MV). In addition to SLAM, vaccine strains of MV also use a ubiquitously expressed complement regulatory protein, CD46, as a receptor, whereas wild-type (wt) MV strains do not use this receptor. However, recent studies have indicated that SLAM is not the sole receptor for wt MV strains. These strains have an intrinsic ability to enter both immune and epithelial cells using distinct receptor binding sites in their hemagglutinin (H) protein. Recently, a clear answer was obtained through the identification of an epithelial MV receptor, nectin4, expressed at adherens junctions, thereby greatly improving our knowledge of MV receptors. It is now clear that MV specifically targets two cell types, immune cells and epithelial cells, using SLAM and nectin4, respectively. MV loses the ability to use either SLAM or nectin4 when it possesses specific mutations in the H protein. However, nectin4-blind MV still infects SLAM-positive immune cells efficiently (SLAM-tropic), and conversely, SLAM-blind MV infects nectin4-positive epithelial cells efficiently (nectin4-tropic). In this regard, MV is intrinsically dual-tropic to immune cells and epithelial cells. Although many aspects and molecular mechanisms underlying immunosuppressive effects and a highly contagious nature of MV still remain to be elucidated, analyses of physiological functions of these two receptors would provide deep insights into MV pathogenesis.

Role of increased CD8/CD28(null) T cells and alternative co-stimulatory molecules in chronic obstructive pulmonary disease

Chronic obstructive pulmonary disease (COPD) is a chronic inflammatory lung disease; it is a leading cause of death and existing treatments have no proven disease-modifying effect. The mechanisms underlying this resistance are largely unknown, but suggest the presence of some self-maintaining pathogenic process, possibly initiated by cigarette smoking, that prevents the normal resolution of inflammation. We have previously reported increased production of proinflammatory cytokines and granzyme b by CD8(+) T cells in COPD; costimulatory receptor/ligand interactions required include CD80:86/CD28, B7-1/CTLA4, 4-1BB/1BBL and OX40/OX40L. We hypothesized that a dysregulated expression/function of these molecules may play a role in inflammatory/autoimmune components of COPD. We analysed T cell co-stimulatory molecules in blood from 34 controls, 15 smokers and 48 COPD subjects. We assessed the potential functional relevance of CD8/CD28(null) cells in COPD by measuring their production of proinflammatory cytokines, co-stimulatory molecules, granzyme and perforin. A smoke-exposed murine model was applied to investigate the relative expression of CD8/CD28(null) T cells in blood, lung tissue and airway. CD8/CD28(null) cells were increased in both current- and ex-smoker COPD groups; these cells expressed significantly more interferon (IFN)-γ, OX40, 4-1BB, CTLA4, granzyme and perforin when stimulated than CD8/CD28(+) T cells. There were no changes in CD4/CD28(null) T cells. In mice exposed to cigarette smoke for 12 weeks, CD8/CD28(null) T cells were significantly increased in the airway with a trend for an increase in lung tissue and blood. Increased production of proinflammatory cytokines and expression of alternative co-stimulatory molecules by CD8/CD28(null) T cells may play a role in inflammatory or autoimmune responses in COPD and identify therapeutic targets.

B lymphocytes in inflammatory airway diseases

B lymphocytes are key players in all facets of adaptive immune responses and are responsible for the production of IgE antibodies, initiators of allergic hypersensitivity reactions. Recent evidence indicates that B cells may be a crucial player in allergic and inflammatory airway pathology, directly populating upper and lower airway tissues. This review examines human and animal studies that directly demonstrated the presence of B lymphocytes in airway tissues and elaborates on their function as antibody-secreting cells, antigen-presenting cells and producers of inflammatory and regulatory cytokines. B lymphocytes appear to contribute to multiple facets of immune homeostasis in inflammatory diseases of the upper and lower airways.

Resolution of cell-mediated airways diseases

"Inflammation resolution" has of late become a topical research area. Activation of resolution phase mechanisms, involving select post-transcriptional regulons, transcription factors, 'autacoids', and cell phenotypes, is now considered to resolve inflammatory diseases. Critical to this discourse on resolution is the elimination of inflammatory cells through apoptosis and phagocytosis. For major inflammatory diseases such as asthma and COPD we propose an alternative path to apoptosis for cell elimination. We argue that transepithelial migration of airway wall leukocytes, followed by mucociliary clearance, efficiently and non-injuriously eliminates pro-inflammatory cells from diseased airway tissues. First, it seems clear that numerous infiltrated granulocytes and lymphocytes can be speedily transmitted into the airway lumen without harming the epithelial barrier. Then there are a wide range of 'unexpected' findings demonstrating that clinical improvement of asthma and COPD is not only associated with decreasing numbers of airway wall inflammatory cells but also with increasing numbers of these cells in the airway lumen. Finally, effects of inhibition of transepithelial migration support the present hypothesis. Airway inflammatory processes have thus been much aggravated when transepithelial exit of leukocytes has been inhibited. In conclusion, the present hypothesis highlights risks involved in drug-induced inhibition of transepithelial migration of airway wall leukocytes. It helps interpretation of common airway lumen data, and suggests approaches to treat cell-mediated airway inflammation.

Dynamic T cell migration program provides resident memory within intestinal epithelium

Migration to intestinal mucosa putatively depends on local activation because gastrointestinal lymphoid tissue induces expression of intestinal homing molecules, whereas skin-draining lymph nodes do not. This paradigm is difficult to reconcile with reports of intestinal T cell responses after alternative routes of immunization. We reconcile this discrepancy by demonstrating that activation within spleen results in intermediate induction of homing potential to the intestinal mucosa. We further demonstrate that memory T cells within small intestine epithelium do not routinely recirculate with memory T cells in other tissues, and we provide evidence that homing is similarly dynamic in humans after subcutaneous live yellow fever vaccine immunization. These data explain why systemic immunization routes induce local cell-mediated immunity within the intestine and indicate that this tissue must be seeded with memory T cell precursors shortly after activation.

Wild-type measles virus infection of primary epithelial cells occurs via the basolateral surface without syncytium formation or release of infectious virus

The lymphotropic and myelotropic nature of wild-type measles virus (wt-MV) is well recognized, with dendritic cells and lymphocytes expressing the MV receptor CD150 mediating systemic spread of the virus. Infection of respiratory epithelial cells has long been considered crucial for entry of MV into the body. However, the lack of detectable CD150 on these cells raises the issue of their importance in the pathogenesis of measles. This study utilized a combination of in vitro, ex vivo and in vivo model systems to characterize the susceptibility of epithelial cells to wt-MV of proven pathogenicity. Low numbers of MV-infected epithelial cells in close proximity to underlying infected lymphocytes or myeloid cells suggested infection via the basolateral side of the epithelium in the macaque model. In primary cultures of human bronchial epithelial cells, foci of MV-infected cells were only observed following infection via the basolateral cell surface. The extent of infection in primary cells was enhanced both in vitro and in ex vivo cornea rim tissue by disrupting the integrity of the cells prior to the application of virus. This demonstrated that, whilst epithelial cells may not be the primary target cells for wt-MV, areas of epithelium in which tight junctions are disrupted can become infected using high m.o.i. The low numbers of MV-infected epithelial cells observed in vivo in conjunction with the absence of infectious virus release from infected primary cell cultures suggest that epithelial cells have a peripheral role in MV transmission.

Increased levels of (class switched) memory B cells in peripheral blood of current smokers

There is increasing evidence that a specific immune response contributes to the pathogenesis of COPD. B-cell follicles are present in lung tissue and increased anti-elastin titers have been found in plasma of COPD patients. Additionally, regulatory T cells (Tregs) have been implicated in its pathogenesis as they control immunological reactions. We hypothesize that the specific immune response in COPD is smoke induced, either by a direct effect of smoking or as a result of smoke-induced lung tissue destruction (i.e. formation of neo-epitopes or auto antigens). Furthermore, we propose that Tregs are involved in the suppression of this smoke-induced specific immune response.

The presence of B cells, memory B cells and Tregs was assessed by flow cytometry in peripheral blood of 20 COPD patients and 29 healthy individuals and related to their current smoking status.

COPD patients had lower (memory) B-cell percentages and higher Treg percentages in peripheral blood than healthy individuals, with a significant negative correlation between these cells. Interestingly, current smokers had higher percentages of (class-switched) memory B cells than ex-smokers and never smokers, irrespective of COPD.

This increase in (class-switched) memory B cells in current smokers is intriguing and suggests that smoke-induced neo-antigens may be constantly induced in the lung. The negative correlation between B cells and Tregs in blood is in line with previously published observations that Tregs can suppress B cells. Future studies focusing on the presence of these (class switched) memory B cells in the lung, their antigen specificity and their interaction with Tregs are necessary to further elucidate the specific B-cell response in COPD.

Autoimmune T cell responses to antigenic peptides presented by bronchoalveolar lavage cell HLA-DR molecules in sarcoidosis

The etiology of sarcoidosis remains unknown. Recently, by mass spectrometric sequencing of peptides eluted from HLA-DR molecules of bronchoalveolar lavage (BAL) cells from DRB10301(pos) patients, we identified potential self-antigens in sarcoidosis. The aim of the present study was to investigate the capacity of selected peptides to stimulate lung and blood T cells of sarcoidosis patients using an interferon-gamma ELISPOT assay. In peripheral blood, there were strong T cell responses to a peptide derived from the cytoskeletal protein vimentin in 6 out of 11 DRB10301(pos) patients with active disease but not in patients with other HLA types. BAL T cell responses against peptides derived from ATP synthase or from lysyl-tRNA synthetase were detected in DRB10301(pos) as well as DRB10301(neg) patients. By using antigenic peptides presented in vivo in the lungs of sarcoidosis patients, we have identified blood and lung T cell autoimmune responses that may help sustain the inflammation in this disease.

What is the clinical relevance of different lung compartments?

The lung consists of at least seven compartments with relevance to immune reactions. Compartment 1 - the bronchoalveolar lavage (BAL), which represents the cells of the bronchoalveolar space: From a diagnostic point of view the bronchoalveolar space is the most important because it is easily accessible in laboratory animals, as well as in patients, using BAL. Although this technique has been used for several decades it is still unclear to what extent the BAL represents changes in other lung compartments. Compartment 2 - bronchus-associated lymphoid tissue (BALT): In the healthy, BALT can be found only in childhood. The role of BALT in the development of the mucosal immunity of the pulmonary surfaces has not yet been resolved. However, it might be an important tool for inhalative vaccination strategies. Compartment 3 - conducting airway mucosa: A third compartment is the bronchial epithelium and the submucosa, which both contain a distinct pool of leukocytes (e.g. intraepithelial lymphocytes, IEL). This again is also accessible via bronchoscopy. Compartment 4 - draining lymph nodes/Compartment 5 - lung parenchyma: Transbronchial biopsies are more difficult to perform but provide access to two additional compartments - lymph nodes with the draining lymphatics and lung parenchyma, which roughly means "interstitial" lung tissue. Compartment 6 - the intravascular leukocyte pool: The intravascular compartment lies between the systemic circulation and inflamed lung compartments. Compartment 7 - periarterial space: Finally, there is a unique, lung-specific space around the pulmonary arteries which contains blood and lymph capillaries. There are indications that this "periarterial space" may be involved in the pulmonary host defense.

All these compartments are connected but the functional network is not yet fully understood. A better knowledge of the complex interactions could improve diagnosis and therapy, or enable preventive approaches of local immunization.

Altered effector function of peripheral cytotoxic cells in COPD

Background

There is mounting evidence that perforin and granzymes are important mediators in the lung destruction seen in COPD. We investigated the characteristics of the three main perforin and granzyme containing peripheral cells, namely CD8⁺ T lymphocytes, natural killer (NK; CD56⁺CD3^-) cells and NKT-like (CD56⁺CD3⁺) cells.

Methods

Peripheral blood mononuclear cells (PBMCs) were isolated and cell numbers and intracellular granzyme B and perforin were analysed by flow cytometry. Immunomagnetically selected CD8+ T lymphocytes, NK (CD56⁺CD3^-) and NKT-like (CD56⁺CD3⁺) cells were used in an LDH release assay to determine cytotoxicity and cytotoxic mechanisms were investigated by blocking perforin and granzyme B with relevant antibodies.

Results

The proportion of peripheral blood NKT-like (CD56⁺CD3⁺) cells in smokers with COPD (COPD subjects) was significantly lower (0.6%) than in healthy smokers (smokers) (2.8%, p < 0.001) and non-smoking healthy participants (HNS) (3.3%, p < 0.001). NK (CD56⁺CD3^-) cells from COPD subjects were significantly less cytotoxic than in smokers (16.8% vs 51.9% specific lysis, p < 0.001) as were NKT-like (CD56⁺CD3⁺) cells (16.7% vs 52.4% specific lysis, p < 0.001). Both cell types had lower proportions expressing both perforin and granzyme B. Blocking the action of perforin and granzyme B reduced the cytotoxic activity of NK (CD56⁺CD3^-) and NKT-like (CD56⁺CD3⁺) cells from smokers and HNS.

Conclusion

In this study, we show that the relative numbers of peripheral blood NK (CD56⁺CD3^-) and NKT-like (CD56⁺CD3⁺) cells in COPD subjects are reduced and that their cytotoxic effector function is defective.

Peripheral T cell functions correlate with the severity of chronic obstructive pulmonary disease

Adaptive immune processes have been implicated in the pathogenesis of chronic obstructive pulmonary disease (COPD). We hypothesized that peripheral T cell abnormalities may be present in afflicted patients. We tested this hypothesis by characterizing circulating T cells in COPD patients and correlated these findings with disease severity, smoking status, and use of inhaled glucocorticosteroids (ICS). Compared with normal controls, a lesser proportion of peripheral CD4 T cells from COPD subjects produced IL-10, whereas the CD8 T cells from these patients were more often activated and more frequently produced both IFN-gamma and IL-4. COPD severity was significantly and inversely associated with the proportion of circulating CD4 T cells and directly correlated with CD4 production of IL-2, as well as frequency of CD8 T cell activation and CD8 IFN-gamma production. Adjustments for current smoking status and ICS use by linear regression showed independent, and generally inhibitory, effects of these clinical variables on the abnormal T cell functions of these patients. We conclude that circulating T cells from COPD patients are abnormally activated and elaborate proinflammatory mediators with admixed features of Th1 and Th2 responses. Furthermore, many of these effector processes are significantly correlated with disease severity. These findings further implicate adaptive immune processes in COPD progression and indicate that facile assays of peripheral lymphocytes may provide useful insights into disease mechanisms. Current smoking and ICS use had independent effects on T cell functions among the COPD subjects, illustrating the importance of controlling for clinical parameters as covariates in immunological studies of patients afflicted with this disease.

Role of T-lymphocytes and pro-inflammatory mediators in the pathogenesis of chronic obstructive pulmonary disease

Chronic obstructive pulmonary disease (COPD) is the fourth leading cause of death in the US and a major worldwide healthcare problem. The pathophysiologic mechanisms that drive development and progression of this disease are complex and only poorly understood. While tobacco smoking is the primary risk factor, other disease processes also appear to play a role. Components of the innate immune system (eg, macrophages and neutrophils) have long been believed to be important in the development of COPD. More recent evidence also suggests involvement of the adaptive immune system in pathogenesis of this disease. Here we will review the literature supporting the participation of T-cells in the development of COPD, and comment on the potential antigenic stimuli that may account for these responses. We will further explore the prospective contributions of T-cell derived mediators that could contribute to the inflammation, alveolar wall destruction, and small airway fibrosis of advanced COPD. A better understanding of these complex immune processes will lead to new insights that could result in improved preventative and/or treatment strategies.

Polarized localization of epithelial CXCL11 in chronic obstructive pulmonary disease and mechanisms of T cell egression

The exit of lymphocytes from the interstitium of the lung, across the bronchial epithelium and into the airway lumen, is known as egression, or luminal clearance. Egression is important for immune surveillance and the resolution of inflammation, but the mechanisms involved are unknown. We show that egression of human T cells across the bronchial epithelium is a multistep process, driven in part by a polarized transepithelial gradient of CXCL11 that is up-regulated in patients with chronic obstructive airways disease. Previous studies have shown that T cells can migrate across a disrupted bronchial epithelium, but we provide evidence that egression does not require epithelial injury, and can take place across an intact epithelial barrier. After negotiating the extracellular matrix, the T cell adheres to the basal surface of the bronchial epithelial cell using alpha(4) and leukocyte function associated-1 integrins before crossing the epithelium in an leukocyte function associated-1-dependent way. We demonstrate an egression-dependent decrease in transepithelial resistance across the epithelium without gross alteration in tight-junction proteins. The process of egression has been relatively overlooked when considering the control of leukocyte trafficking in the lung and other epithelial organs. This study highlights the role of the respiratory epithelium in the trafficking of T lymphocytes from the pulmonary interstitium and into the large airways, during the onset and resolution of pulmonary inflammation.

Use of monoclonal antibodies to assess expression of anaphylatoxin receptors in rat and murine models of lung inflammation

The anaphylatoxins C3a and C5a are involved in the pathophysiology of microbial as well as allergic inflammation in the lungs. Besides their expression in leukocytes, receptors for C3a and C5a (C3aR and C5aR) have been noted in alveolar and bronchial epithelial cells, bronchial smooth muscle cells as well as in vascular endothelial and smooth muscle cells of normal and inflamed human and murine lungs. Recently, however, expression of anaphylatoxin receptors in parenchymal cells of the lung (and kidney) has been challenged. Using well-characterized monoclonal antibodies (mabs) against murine and rat anaphylatoxin receptors, we reexamined the pulmonary distribution of C3aR and C5aR. Immunohistochemistry was performed on frozen sections of lung tissues from normal mice and rats as well as from animals subjected to lipopolysaccharide (LPS)-induced inflammation or from MRL/lpr mice suffering from autoimmune disease. Furthermore, ovalbumin (OVA)-induced models of allergic asthma in the rat and mouse were investigated. Prominent expression of both anaphylatoxin receptors was detectable in resident as well as infiltrating leukocytes. No C3aR protein was observed in alveolar macrophages. Upon LPS- and OVA-challenge as well as in autoimmune inflammation, numbers of infiltrating leukocytes expressing prominent amounts of anaphylatoxin receptors increased. Even under these highly inflammatory conditions, however, expression of C3aR and C5aR was not inducible in parenchymal cells. Thus, our findings identify infiltrating leukocytes as a prominent source of anaphylatoxin receptors in inflamed lungs. A direct involvement of parenchymal cells in anaphylatoxin-mediated pulmonary inflammation is unlikely.

Increased airway granzyme b and perforin in current and ex-smoking COPD subjects

Increased bronchial epithelial cell apoptosis and CD8+ T-cell numbers in the blood and airways have been reported in COPD. These cells can induce apoptosis via the granzyme-b/perforin-mediated pathway. We hypothesized that increased levels of granzyme-b/perforin would be detected in COPD, contributing to apoptosis and tissue damage. Intracellular granzyme-b/perforin were measured in blood-derived T-cells and natural killer (NK) cells from COPD subjects (30 current and 30 ex-smokers), 20 asymptomatic current-smokers and 30 never-smokers, and bronchoalveolar lavage (BAL)-derived T-cells from a cohort of these subjects using flow cytometry. Soluble granzyme-b was determined by ELISA. In blood, there was an increased percentage of T-cells expressing intracellular granzyme-b/perforin for both COPD groups but not asymptomatic smokers (versus never-smokers). Soluble granzyme-b was undetectable. In BAL, soluble granzyme-b levels and the percentage of T-cells expressing intracellular granzyme-b/perforin were increased in both COPD groups and asymptomatic smokers. There was a significant correlation between granzyme-b expression in BAL and apoptosis of bronchial epithelial cells. Most circulating NK cells expressed granzyme-b/perforin, with the median fluorescence intensity of staining increased in both COPD groups and asymptomatic smokers. Granzyme-mediated apoptosis may thus be one mechanism of lung injury in COPD. The changes that persist despite smoking cessation in COPD likely reflect pathophysiological changes in COPD as opposed to the effects of smoking per se.

The alveolar epithelial type I-like cell line as an adequate model for leukocyte migration studies in vitro

The lung is unique as leukocytes not only migrate into the bronchoalveolar space but also return to the parenchyma and then via the lymphatics to the draining lymph node. The aim of this study was to investigate the migration of leukocytes via an epithelial monolayer in a Transwell system against a chemokine gradient. Rat type I-like R3/1 alveolar epithelial cells were cultivated on a Transwell polyester membrane (pore diameter 3 microm) for 3 days until a monolayer was formed. The tightness of the monolayer was determined by transepithelial transport of horseradish peroxidase. Isolated human and rat peripheral blood mononuclear cells (PBMC) were placed in the upper chamber, and different concentrations of monocyte chemotactic protein-1 (MCP-1) in the lower chamber. The transmigration of PBMC was quantified and investigated by light and transmission electron microscopy. PBMC migrated through the epithelial cell barrier intercellularly as well as transcellularly. The migration of PBMC against the MCP-1 gradient was dose dependent. The results indicate that this model could help in the study of key events involved in chemokine-induced cell migration from the airways into tissue.

Differential Rates of Apoptosis in Bronchoalveolar Lavage and Blood of Lung Transplant Patients

BACKGROUND

Lung transplant tolerance depends on effective control of T-cell proliferation and activation. Commonly used immunosuppressive agents promote peripheral blood-derived lymphocyte apoptosis and inhibit production of cytokines involved in lymphocyte proliferation and survival. However, there have been no studies of the effectiveness of immunosuppressive treatments on apoptosis of T cells derived from the airways of lung transplant recipients. Our main aim was to compare apoptosis of T cells derived from peripheral blood and bronchoalveolar lavage (BAL) from lung transplant recipients, with no evidence of chronic or acute cellular rejection, and healthy volunteers. Lung transplantation may also be associated with increased apoptosis of airway epithelial cells. To investigate this possibility, we also examined apoptosis of epithelial cells derived from bronchial brushing.

METHODS

BAL, blood, and bronchial brushings were obtained from lung transplant recipients (n = 9) and age-matched controls (n = 15). T cell and epithelial cell apoptosis, Fas, Bax, Bcl-2, and p53 were evaluated by flow cytometry.

RESULTS

Increased apoptosis of peripheral blood T cells and decreased Bcl-2 were observed in the transplant patients. In contrast, there was no significant change in apoptosis of airway T cells or apoptosis-related proteins. Increased apoptosis and increased p53 were observed in the airway epithelial cells from the transplant recipients, possibly as a result of ineffective control of infiltrating cytotoxic T cells.

CONCLUSIONS

Immunosuppressive agents may not be as effective in inducing apoptosis of airway-derived T cells as peripheral blood-derived T cells after lung transplantation. These findings may have implications on the outcome of the immune response in the airways after immunosuppressive therapy and may be particularly relevant to lung allograft rejection.

Chemokine receptor CCR7 guides T cell exit from peripheral tissues and entry into afferent lymphatics

T cell circulation between peripheral tissues and the lymphoid compartment is critical for immunosurveillance and host defense. However, the factors that determine whether T cells remain in peripheral tissue or return to the circulation are undefined. Here we demonstrate that the chemokine receptor CCR7 is a critical signal that determines T cell exit from peripheral tissue. Both CCR7(-) and CCR7(+) effector T cells entered mouse asthmatic lung and while CCR7(-) T cells accumulated, CCR7(+) T cells continued to migrate into afferent lymph. Delivery of both CCR7(+) and CCR7(-) T cells directly into the airways showed that only CCR7(+) T cells exited the lung and entered draining lymph nodes. Our study establishes a molecular basis for T cell exit from peripheral tissues.

Engraftment of neonatal lung fibroblasts into the normal and elastase-injured lung

Interstitial fibroblasts are an integral component of the alveolar wall. These cells produce matrix proteins that maintain the extracellular scaffold of alveolar structures. Emphysema is characterized by airspace enlargement resulting from the loss of alveolar cellularity and matrix. In this study, we explored the endotracheal delivery of fibroblasts to the lung parenchyma as a means of repairing damaged alveolar structures directly or indirectly for the delivery of transgenes. Fibroblasts were isolated from the lungs of neonatal transgenic mice expressing GFP during the period of rapid alveolarization. These GFP+ cells maintained their myofibroblast phenotype in culture and expressed elastin and alpha-smooth muscle actin mRNA. We administered GFP+ fibroblasts to saline- and elastase-treated mice by endotracheal instillation. We detected more GFP+ fibroblasts in the alveolar walls and in the interstitial areas of elastase-injured lungs than in normal lungs as assessed by immunohistochemistry and fluorescent imaging. The presence of GFP+ fibroblasts in the interstitium demonstrated transepithelial migration of these cells. Expression of GFP+ fibroblasts in recipient lungs was maintained for at least 20 d after endotracheal administration. These cells synthesize matrix components including elastin in vitro and could contribute to restoring the structural integrity of the alveolar wall.

Increased peripheral blood T-cell apoptosis and decreased Bcl-2 in chronic obstructive pulmonary disease

Chronic obstructive pulmonary disease (COPD) is an inflammatory airway disease, usually associated with cigarette smoking. Stimulated peripheral blood T cells from patients with COPD have an increased propensity to undergo apoptosis. The mitochondrial apoptotic pathway is regulated by pro-apoptotic proteins (including p53 and Bax) as well as anti-apoptotic proteins (e.g. Bcl-2) and cytokines (IL-2, IL-4 and IL-7). We hypothesized that alterations in expression of these apoptosis-related proteins, cytokines and cytokine receptors may be important in determining the susceptibility of T cells to undergoing apoptosis in COPD. We further hypothesized that inhaled corticosteroids (GCS) contribute to the increased rates of T-cell apoptosis observed in COPD. The process of apoptosis (assessed by Annexin V and ssDNA staining), as well as Bcl-2, Bax, p53, IL-2, IL-4 and receptors IL-7R, IL-4R and IL-2Rgamma were investigated in PHA-stimulated peripheral blood-derived T cells, using flow cytometry. Fifteen patients with COPD receiving inhaled GCS (four of who received additional prednisolone), eight patients with COPD receiving symptom control medication, and 16 control subjects were studied. T cells (CD4(+) and CD8(+)) from GCS-treated COPD patients showed an increased propensity to undergo apoptosis, associated with significantly decreased Bcl-2 and IL-7 receptor expression. No significant differences were observed for the COPD patients who were receiving symptom control medication. These findings may suggest a negative peripheral effect of inhaled GCS on the immune system in COPD, although the clinical significance of these effects remains uncertain.

Intracellular cytokines in blood T cells in lung transplant patients--a more relevant indicator of immunosuppression than drug levels

Allograft rejection remains a major cause of morbidity and mortality following lung transplantation and is associated with an increase in T-cell pro-inflammatory cytokine expression. Systemic levels of immunosuppressive drugs used to reduce pro-inflammatory cytokine expression are closely monitored to their 'therapeutic range'. However, it is currently unknown if levels of these drugs correlate with pro-inflammatory cytokine expression in peripheral blood T cells. To investigate the immunomodulatory effects of currently used immunosuppressive regimes on peripheral blood T-cell cytokine production, whole blood from stable lung transplant patients and control volunteers were stimulated in vitro and cytokine production by CD8+ and CD4+ T-cell subsets determined using multiparameter flow cytometry. T-cell IL-2 and TNFalpha production was significantly reduced from lung transplant patients compared to controls. CD4+ T-cell production of IFNgamma was also significantly reduced from lung transplant patients but production of IFNgamma by CD8+ T cells remained unchanged. There was an excellent correlation between the percentage of CD8+ T cells and the percentage of CD8+ T cells producing IFNgamma from transplant patients. T-cell IL-4 and CD8+ T-cell production of TGFbeta was significantly increased from lung transplant patients. We now provide evidence that current immunosuppression protocols have limited effect on peripheral blood IFNgamma production by CD8+ T-cells but do up-regulate T-cell anti-inflammatory cytokines. Drugs that effectively reduce IFNgamma production by CD8+ T cells may improve current protocols for reducing graft rejection in these patients. Intracellular cytokine analysis using flow cytometry may be a more appropriate indicator of immunosuppression than drug levels in these patients. This technique may prove useful in optimizing therapy for individual patients.

CC chemokine receptor 7 expression by effector/memory CD4+ T cells depends on antigen specificity and tissue localization during influenza A virus infection

The lung is an important entry site for respiratory pathogens such as influenza A virus. In order to combat such invading infectious agents, effector/memory T cells home to the lung and other peripheral tissues as well as lymphoid organs. In this process, chemokines and their receptors fulfill important roles in the guidance of T cells into such organs and specialized microenvironments within tissues. In this study, we determined if CD4(+) T cells residing in different lung compartments and draining lymph nodes of influenza A virus-infected and naïve mice express receptors allowing their recirculation into secondary lymphoid tissues. We found high levels of l-selectin and CC chemokine receptor 7 (CCR7) expression in lung-derived CD4(+) T cells, similar to that detected on T cells in secondary lymphoid organs. Upon influenza A virus infection, the bulk of gamma interferon-positive (IFN-gamma(+)) and IFN-gamma(-) CD4(+) T cells recovered from lung parenchyma retained functional CCR7, whereas virus-specific IFN-gamma-producing T cells were CCR7(-). In contrast, a majority of virus-specific IFN-gamma(+) T cells in the lung draining lymph node were CCR7(+). Independent of infection, CD4(+) T cells obtained from the lung airways exhibited the lowest expression level of l-selectin and CCR7, indicating that T cells at this anatomical site represent the most differentiated effector cell type, lacking the ability to recirculate. Our results suggest that effector/memory T cells that enter inflammatory sites retain functional CCR7 expression, which is lost only upon response to viral antigen and after localization to the final effector site.

Helicobacter pylori-Related Immunoglobulins in Sarcoidosis

Background/Purpose

The purpose of this study was to determine serum antibody titers against a common bacterial antigen, Helicobacter pylori (H. pylori), in subjects with sarcoidosis, comparing those titers to those present in a healthy population.

Subjects and Methods

With the approval of the Institutional Review Board of the University of Missouri-Kansas City, patients with sarcoidosis (pulmonary and extrapulmonary) who visited the Truman Medical Center-Hospital Hill pulmonary clinic were recruited to enter the study. A serum sample was frozen at -70°C for later testing ( n = 20). Specific information collected on subjects included corticosteroid use, use of histamine2 blockers and antacids, date of first diagnosis, and stage of sarcoidosis. Normal controls and demographically matched individuals who lacked pulmonary diseases, including sarcoidosis, were also recruited. Serum samples were processed as above. Antibody capture enzyme immunoassay was completed for H. pylori and urease antigens by serum dilution assay for each subject, from which titers for antigen-specific immunoglobulin (lg)G and IgA were calculated. Nonspecific serum IgE was also measured.

Results

An increased incidence of high-titer IgG antibody directed against H. pylori antigens was found in subjects with sarcoidosis compared with controls. The sarcoidosis and control groups were significantly different with respect to IgG and IgA against H. pylori, both at p = .001. IgG directed against urease was also significantly different between sarcoidosis and control patients ( p = .001), but IgA directed against urease was very low in all subjects and did not yield significant differences between groups.

Conclusions

Specific H. pylori and urease IgG antibodies exceeded those expected in the population studied. The data suggest that in pulmonary sarcoidosis, the relationship of H. pylori and its products to sarcoid granuloma formation warrants further investigation.

CD4+ T cells migrate from airway to bone marrow after antigen inhalation in rats

BACKGROUND

IL-5-producing T lymphocytes increase in rat bone marrow after inhalational challenge with allergen.

OBJECTIVE

To test the hypothesis that T cells migrate from the airways to the marrow, we examined the trafficking of T cells in Brown Norway rats after sensitization and challenge with ovalbumin.

METHODS

Purified CD4+ T cells, harvested from cervical lymph nodes of naive and ovalbumin-sensitized donors, were labeled with carboxy fluorescein diacetate succinimidyl ester; 20 x 10(6) cells were placed in the trachea of naive or sensitized recipients under anesthesia, and 18 hours later, animals were challenged with inhaled ovalbumin. Cells were harvested 24 hours later from the bone marrow, bronchoalveolar lavage fluid, lungs, the lung blood pool of cells, lung draining lymph nodes, peripheral blood, and spleen.

RESULTS

The number of carboxy fluorescein diacetate succinimidyl ester-positive cells, measured by fluorescence-activated cell sorter, in the bone marrow of ovalbumin sensitized, primed T-cell recipients was higher than either the sham-sensitized, primed T-cell recipients or sham-sensitized, naive T-cell recipients (P < .05). The number of eosinophils in both bone marrow and bronchoalveolar lavage fluid was increased in ovalbumin-sensitized, primed T-cell recipients. The expression of the T-cell chemoattractants eotaxin and IL-16, evaluated by immunohistochemistry, was higher in the bone marrow of ovalbumin-sensitized, primed T-cell recipients.

CONCLUSIONS

CD4+ T cells travel from airway to bone marrow after antigen inhalation. The homing of the CD4+ T cells might be facilitated by eotaxin and IL-16 expression in the bone marrow and might contribute to the stimulation of eosinophilopoiesis after airway allergen exposure.

Increased production of TGF-beta and apoptosis of T lymphocytes isolated from peripheral blood in COPD

Chronic obstructive pulmonary disease (COPD) is associated with inflammation of airway epithelium, including an increase in the number of intraepithelial T cells. Increased apoptosis of these T cells has been reported in the airways in COPD, and although this process is critical for clearing excess activated T cells, excessive rates of apoptosis may result in unbalanced cellular homeostasis, defective clearance of apoptotic material by monocytes/macrophages, secondary necrosis, and prolongation of the inflammatory response. Lymphocytes are known to traffic between the airway and the peripheral circulation, thus we hypothesized that in COPD, circulating T cells may show an increased propensity to undergo apoptosis. We analyzed phytohemagglutinin (PHA)-stimulated peripheral blood T cells from COPD patients and controls for apoptosis using flow cytometry and staining with annexin V and 7-aminoactinomycin D. As several pathways are involved in induction of apoptosis of T cells, including transforming growth factor (TGF)-beta/TGF receptor (TGFR), TNF-alpha/TNFR1, and Fas/Fas ligand, these mediators were also investigated in peripheral blood samples from these subject groups. Significantly increased apoptosis of PHA-stimulated T cells was observed in COPD (annexin positive 75.0 +/- 14.7% SD vs. control 50.2 +/- 21.8% SD, P = 0.006), along with upregulation of TNF-alpha/TNFR1, Fas, and TGFR. Monocyte production of TGF-beta was also increased. In conclusion we have demonstrated the novel finding of increased apoptosis of stimulated T cells in COPD and have also shown that the increased T-cell death may be associated with upregulation of apoptotic pathways, TGF-beta, TNF-alpha, and Fas in the peripheral blood in COPD.

Enhanced immunogenicity and protective efficacy against Mycobacterium tuberculosis of bacille Calmette-Guérin vaccine using mucosal administration and boosting with a recombinant modified vaccinia virus Ankara

Heterologous prime-boost immunization strategies can evoke powerful T cell immune responses and may be of value in developing an improved tuberculosis vaccine. We show that recombinant modified vaccinia virus Ankara, expressing Mycobacterium tuberculosis Ag 85A (M.85A), strongly boosts bacille Calmette-Guérin (BCG)-induced Ag 85A specific CD4(+) and CD8(+) T cell responses in mice. A comparison of intranasal (i.n.) and parenteral immunization of BCG showed that while both routes elicited comparable T cell responses in the spleen, only i.n. delivery elicited specific T cell responses in the lung lymph nodes, and these responses were further boosted by i.n. delivery of M.85A. Following aerosol challenge with M. tuberculosis, i.n. boosting of BCG with either BCG or M.85A afforded unprecedented levels of protection in both the lungs (2.5 log) and spleens (1.5 log) compared with naive controls. Protection in the lung correlated with the induction of Ag 85A-specific, IFN-gamma-secreting T cells in lung lymph nodes. These findings support further evaluation of mucosally targeted prime-boost vaccination approaches for tuberculosis.

A single intratracheal dose of the growth factor Fms-like tyrosine kinase receptor-3 ligand induces a rapid differential increase of dendritic cells and lymphocyte subsets in lung tissue and bronchoalveolar lavage, resulting in an increased local antibody production

Repetitive doses of the growth factor Fms-like tyrosine kinase receptor-3 ligand (Flt3L) have resulted in increased numbers of dendritic cells (DC) in various organs, and the effect on protective or tolerogeneic responses in the gut wall has been documented in the literature. In this study, for the first time, Flt3L was locally applied in the trachea of rats using a single dose only. A dose-dependent increase not only of DC, but also of T lymphocytes (CD4(+) and CD8(+)), was seen with a maximum on day 3. The effects on the cells in the lung interstitium and the bronchoalveolar space showed some differences. The use of tetanus toxoid as a model Ag applied intratracheally after the local Flt3L stimulation resulted in increased levels of specific IgA and IgG in the lung. Thus, this novel approach of locally stimulating APCs by topical application of a DC growth factor before applying the Ag offers a new vaccination strategy.

Expression of vascular adhesion protein-1 in normal and inflamed mice lungs and normal human lungs

Recently, vascular adhesion protein-1 (VAP-1) was implicated in adhesion and transmigration of lymphocytes across endothelial cells in liver and other organs. There is very little information on VAP-1 expression in normal and inflamed lungs. Therefore, we conducted a study to localize VAP-1 in normal mice and human lungs and in two distinct murine models of lung inflammation. Normal mice and human lungs revealed VAP-1 expression in the endothelium of large and mid-sized pulmonary vessels but not in alveolar septae, airway epithelium or blood cells. Mice that lack the lpr(-/-) gene and develop extensive lymphocytic infiltration in their lungs showed VAP-1 expression similar to the normal mice lungs. Mice subjected to cecal ligation and puncture developed acute lung inflammation and showed VAP-1 not only in endothelial cells but also in inflammatory cells in perivascular areas at 72 h after the procedure. We concluded that VAP-1 expression may contribute to the functional heterogeneity of endothelial cells within the lung to create distinct sites for the recruitment of inflammatory cells. Furthermore, since VAP-1 is expressed over a longer period of time in inflamed lungs, it may even be a suitable target for drug delivery and therapeutic manipulations.