Experimental hypersensitivity pneumonitis: influence of Th2 bias

Hypersensitivity pneumonitis : a broader perspective

Hypersensitivity pneumonitis (HP) represents a group of lung disorders caused by the inhalation of a wide variety of organic particles by susceptible individuals. HP occurs mainly in nonsmokers, but smoking may promote an insidious and chronic disease. The prevalence of HP is difficult to estimate accurately since several antigens can produce the disease, but the range spans infancy to old age. Regardless of the causative antigen or its environmental setting, the clinical manifestations are essentially the same. Three different clinical presentations have been recognized: acute, subacute, and chronic. In the acute form, patients show flu-like symptomatology, followed by dyspnea and dry cough. Symptoms subside a few hours or days later. The subacute and chronic forms result from recurrent low-level antigen exposure and are characterized by progressive dyspnea and dry cough. Other constitutional symptoms such as fatigue, anorexia, and weight loss can be apparent. Fever may occur in the subacute form. Importantly, chronic HP may evolve insidiously or may result from repeated acute/subacute episodes. Recurrent acute, subacute, and chronic HP may progress to irreversible lung fibrosis or provoke emphysematous changes.HP can be difficult to identify, and precise diagnosis requires a history of exposure and a constellation of clinical, imaging, laboratory, bronchoalveolar lavage and pathologic findings. General laboratory tests show an increase of acute phase reactants. Specific precipitating antibodies, when present, are evidence of antigen exposure, and are a hallmark for diagnosis. Chest radiograph usually reveals widespread ground-glass attenuation, and nodular or reticulonodular shadowing. High-resolution CT features include diffuse or patchy ground-glass opacities with small poorly defined nodules and air trapping. Pulmonary function tests are characterized by a predominantly restrictive ventilatory defect with loss of lung volume and hypoxemia at rest that worsens with exercise. Bronchoalveolar lavage reveals a significant increase in lymphocytes, mostly over 40%. In the acute form there is also an increase in neutrophils. Antigen-induced lymphocyte proliferation, and environmental or laboratory-controlled inhalation challenge, may be used for diagnostic purposes and can help to establish a diagnosis of insidious forms of HP. In subacute or chronic cases, lung biopsy may be necessary. Typical findings include bronchiolitis, lymphocytic alveolitis, and loosely formed granulomas, although occasionally other morphologic patterns such as nonspecific interstitial pneumonia may exist. Treatment focuses on avoiding further exposure to the offending antigen(s). Corticosteroids are recommended in subacute and chronic forms. The usual regimen consists of initial high doses of systemic corticosteroid (e.g. prednisone 0.5-1.0 mg/kg/day), followed by gradual tapering.

Role of interleukin 4 and its receptor in clinical presentation of chronic extrinsic allergic alveolitis: a pilot study

Background

Th-2 cytokine milieu including interleukin 4 (IL-4) was detected in fibrotic lung diseases. Chronic extrinsic allergic alveolitis (EAA) may be also accompanied by marked fibrogenesis. The aim of this study was to determine if IL-4 and its receptor (IL-4R-alpha) play any role in the clinical presentation and pathogenesis of chronic EAA.

Methods

Twenty patients originally investigated for interstitial lung disease and finally diagnosed affected with chronic EAA and sarcoidosis were prospectively enrolled into the study. Concentrations of IL-4, IL-4R-aplha and total protein were assessed in the bronchoalveolar lavage fluid (BALF) of all enrolled subjects as well as high resolution computed tomography (HRCT) scores and pulmonary function tests.

Results

BALF IL-4R-alpha and total protein concentrations were significantly higher in chronic EAA patients (p < 0.05). Concentrations of BALF IL-4R-alpha were significantly higher in men than in women (p < 0.05) in EAA group. Total protein BALF levels were significantly elevated in ex-smokers with EAA compared to nonsmokers (p < 0.05). A positive correlation (p < 0.01) between IL-4R-alpha BALF concentrations and HRCT interstitial scores were observed in chronic EAA group; the IL-4R-alpha/total protein ratio showed the same significant positive correlation. A negative correlation between lung function results and IL-4R-alpha, and IL-4R-alpha/total protein as well, was also found (p < 0.05).

Conclusions

We suggest a clinical relevance for the IL-4/IL-4R axis in the etiopathogenesis of chronic EAA. IL-4R-alpha could serve as a potential biomarker of lung fibrogenesis.

Anti-CD33-antibodies labelled with the alpha-emitter Bismuth-213 kill CD33-positive acute myeloid leukaemia cells specifically by activation of caspases and break radio- and chemoresistance by inhibition of the anti-apoptotic proteins X-linked inhibitor of apoptosis protein and B-cell lymphoma-extra large

AIM

The emerging interest in radioimmunotherapies employing alpha-emitters for cancer treatment like high risk-leukaemia leads to the question of how these radionuclides exhibit their cytotoxicity. To clarify the molecular mechanisms of cell death induction, we investigated the molecular effects of the alpha-emitter Bismuth-213 (Bi-213) bound to a monoclonal anti-CD33-antibody ([Bi-213]anti-CD33) on the cell cycle and on apoptosis induction in sensitive as well as in beta- and gamma-radiation-resistant CD33-positive acute myeloid leukaemia (AML) cells.

METHODS

The cytotoxic potential of the radioimmunoconjugate [Bi-213]anti-CD33 was analysed in the CD33-expressing human AML cell line HL-60 and in radiation- and chemoresistant HL-60-derived cell lines. Cell cycle and apoptosis induction analyses were performed via flow cytometry. Activation of apoptosis pathways was determined by immunodetection.

RESULTS

[Bi-213]anti-CD33 induced apoptotic cell death in CD33-positive AML cells specifically. Molecular analyses revealed that the intrinsic mitochondrial pathway of apoptosis was activated resulting in caspase-9 activation. In the apoptotic executioner cascade caspase-3 was activated and its substrate poly (ADP-ribose) polymerase (PARP) was cleaved. Notably, [Bi-213]anti-CD33 overcame radio- and chemoresistance by reversing deficient activation of apoptosis pathways in resistant CD33-positive AML cells and by the downregulation of inhibitors of apoptosis B-cell lymphoma-extra large (Bcl-xL) and X-linked inhibitor of apoptosis protein (XIAP) involved in leukaemia resistance.

CONCLUSION

[Bi-213]anti-CD33 exhibits its cytotoxic effects specifically in CD33-expressing AML cells via induction of the intrinsic, mitochondrial pathway of apoptosis. The abrogation of chemo- and radioresistances and the reactivation of apoptotic pathways seem to be promising for the treatment of patients with so far untreatable resistant AML and underline the importance of this emerging therapeutic approach of targeted alpha-therapies.

The effect of CTLA-4Ig, a CD28/B7 antagonist, on the lung inflammation and T cell subset profile during murine hypersensitivity pneumonitis

Hypersensitivity pneumonitis (HP) is an inflammatory lung disease characterized by an influx of activated T cells to the lung, in which the CD28/B7 costimulatory signals are essential for the T cell activation and the outcome of the inflammatory response. In this study, we investigated the effect of the CD28/B7 antagonist, CTLA-4Ig, on the lung inflammation and the T cell subset profile in experimental Saccharopolyspora recivirgula (SR)-induced HP. C57BL/6 mice were treated with SR or saline during two and three weeks and in addition of CTLA-4Ig was administrated after either the second or third week and mice were sacrificed seven days later. The extent of the lung inflammation was quantified by histopathology and the lung T cell subsets (Treg, Th17, γδT and NKT) were analyzed by flow cytometry. Mice treated with CTLA-4Ig showed a significant decrease in the extent of lung damage (p<0.05), and exhibited a decreased number of inflammatory cells in the bronchoalveolar lavage (BAL) with diminished CD4/CD8 T cell ratio. Also, a significant increase in the percentage of lung γδT (p<0.01) and NKT (p<0.05) cells was observed in two weeks SR-treated mice with the administration of CTLA-4Ig/SR. At 3 weeks, SR-treated mice showed an increased percentage of regulatory T cells but no significantly differences were found in the percentage of Th17 cells when compared with CTLA-4Ig/SR-treated mice. Our findings suggest that the treatment with CTLA-4Ig affects the HP progression and the lung T cell subset kinetics in mice.

Where asthma and hypersensitivity pneumonitis meet and differ: noneosinophilic severe asthma

Asthma is a type-I allergic airway disease characterized by Th(2) cells and IgE. Episodes of bronchial inflammation, eosinophilic in nature and promoting bronchoconstriction, may become chronic and lead to persistent respiratory symptoms and irreversible structural airway changes. Representative mostly of mild to moderate asthma, this clinical definition fails to account for the atypical and often more severe phenotype found in a considerable proportion of asthmatics who have increased neutrophil cell counts in the airways as a distinguishing trait. Neutrophilic inflammation is a hallmark of another type of allergic airway pathology, hypersensitivity pneumonitis. Considered as an immune counterpart of asthma, hypersensitivity pneumonitis is a prototypical type-III allergic inflammatory reaction involving the alveoli and lung interstitium, steered by Th(1) cells and IgG and, in its chronic form, accompanied by fibrosis. Although pathologically very different and commonly approached as separate disorders, as discussed in this review, clinical studies as well as data from animal models reveal undeniable parallels between both airway diseases. Danger signaling elicited by the allergenic agent or by accompanying microbial patterns emerges as critical in enabling immune sensitization and in determining the type of sensitization and ensuing allergic disease. On this basis, we propose that asthma allergens cause severe noneosinophilic asthma because of sensitization in the presence of hypersensitivity pneumonitis-promoting danger signaling.

Optimization of the use of C57BL/6 mice as a laboratory animal model for Neospora caninum vaccine studies

The development and testing of vaccines for Neospora caninum in mice require challenge studies to demonstrate a reduction in clinical signs or prevention of vertical transmission of the parasite after vaccination. Genetic susceptibility to N. caninum varies with the strain of mice. In this study, C57BL/6 mice were evaluated as a model for Neospora vaccine studies. A lethal challenge model was developed and the LD(50) was determined to be 1.5 x 10(7)N. caninum tachyzoites/mouse, delivered intraperitoneally. Brain lesions encountered in sections from sub-lethally challenged mice were scored on the basis of severity and total number of lesions to develop a histopathological scoring system for vaccine efficacy. A vertical transmission model for N. caninum vaccine studies was developed by studying mice that were infected either 2 weeks prior to mating or between days 12 and 14 of pregnancy. It was found that infection prior to mating reduced the average number of pups per litter. DNA extracted from fetal tissue was examined by a N. caninum specific polymerase chain reaction (PCR). The rate of vertical transmission was 0, 100 and 90.5% for the uninfected controls, mice infected during pregnancy and mice infected before mating, respectively. This study demonstrates that the C57BL/6 strain of mice is a good model for N. caninum vaccine studies because it is possible to establish a clear-cut lethal challenge model in C57BL/6 mice and they transmit the disease to their offspring efficiently.

Les pneumopathies d’hypersensibilité en milieu professionnel

INTRODUCTION

Hypersensitivity pneumonitis (HP) is a granulomatous disease of the lungs due to immune reactions following chronic inhalation of organic dusts or chemicals especially encountered in the occupational environment. The main purpose of this review is to report current concepts regarding aetiologies, epidemiology, diagnosis, treatment as well as legal aspects of HP.

STATE OF THE ART

The following aspects will be focused: (1) increase in new etiological circumstances, especially occupational and news antigens, (2) for diagnosis, the major contribution of chest high resolution CT scan which often shows characteristic images but also recent developments in simple diagnostic criteria that may be used for an epidemiological approach, (3) importance of bronchial obstruction and even emphysema as a long term sequelae, finally (4) the possibility of continuing occupational activities in certain circumstances where preventive measures can be used.

PERSPECTIVES

The increasing knowledge of etiological agents and circumstances as well as the development of secondary and especially primary preventive measures should lead to reduce the frequency of this disease and of its medico-social consequences.

Hypersensitivity pneumonitis: a multifaceted deceiving disorder

Hypersensitivity pneumonitis (HP) represents a group of immunologically mediated lung disorders provoked by recurrent exposure to various environmental agents. HP is multifaceted and may mimic almost any interstitial lung disease, some infectious diseases,and even bronchiolar disorders. In the absence of a diagnostic gold standard,diagnosis of HP requires a combination of clinical, environmental, radiologic, physiologic,and pathologic findings that represent a diagnostic challenge for clinicians and-in the chronic form-even for experienced pathologists. Therapeutic approach includes avoiding further exposure and, depending on the clinical form, the administration of a course of prednisone. New anti-inflammatory, immunoregulatory, and antifibrotic drugs are urgently needed for this and other interstitial lung diseases.

Experimental hypersensitivity pneumonitis: role of MCP-1

Inhalation of Saccharopolyspora rectivirgula causes "farmer's lung" disease, a classic example of hypersensitivity pneumonitis (HP). Monocyte chemoattractant protein-1 (MCP-1) is increased in the bronchoalveolar lavage fluid of mice challenged with S rectivirgula, and S rectivirgula induces MCP-1 secretion by alveolar macrophages. We tested the hypothesis that MCP-1 and its receptor CC chemokine receptor-2 (CCR2) are essential to the development of experimental HP by treating mice with MCP-1 antibody and using CCR2(-/-) mice. Administration of anti-MCP-1 did not change the response to intratracheally administered S rectivirgula. CCR2(-/-) animals responded in a fashion similar to that of wild-type animals to intratracheally administered.S rectivirgula. To determine the influence of the MCP-1-CCR2 interaction in vitro, we transferred S rectivirgula-cultured spleen cells from S rectivirgula-sensitized mice, to naïve recipients. Later, challenge of the recipients with intratracheal S rectivirgula and examination of both lung histology and bronchoalveolar lavage fluid characteristics were used to determine whether adoptive transfer had occurred. We found that cultured cells from CCR2(-/-) animals were fully capable of adoptive transfer. We conclude that interaction of MCP-1 with CCR2 is not necessary for the development of pulmonary inflammation in response to intratracheally administered S rectivirgula or cells able to adoptively transfer experimental HP.

Anti-avian antibodies and rheumatoid factor in pigeon hypersensitivity pneumonitis

BACKGROUND

Although several immunological abnormalities may be present in pigeon hypersensitivity pneumonitis (HP), few specific hallmarks have been described.

OBJECTIVE

To determine whether the presence of rheumatoid factor (RF) could be useful to discriminate pigeon HP from asymptomatic breeders (AB) and other interstitial lung diseases.

METHODS

Fifty-three patients with pigeon HP, 47 AB, 31 idiopathic pulmonary fibrosis (IPF) patients and a rheumatoid arthritis (RA) group were studied. IgM RF was determined through enzyme-linked immunosorbent assay (ELISA) and western blot using human IgG and IgG Fc fragment as antigens. IgG and IgA anti-avian antibodies (AA) against pigeon serum antigen were also measured. The use of F(ab')2 fraction of peroxidase-labelled anti-human immunoglobulins prevented endogenous interferences. Possible cross-binding of RF with avian antigens and the reactivity against human IgG by AA were studied.

RESULTS

RF tests were frequently positive in HP (52.8%) in comparison to AB (4.2%) and IPF (12.9%; P = 2.6 x 10-10 and 4.1 x 10-5). Therefore, the presence of RF in pigeon HP showed a sensitivity of 52% and was highly specific considering the results of AB and IPF (95 and 87%, respectively). The RA group revealed positive RF but negative AA tests. RF activity was confirmed through western blot using purified IgG Fc fragment. Overlapping levels of IgG and IgA AA were found in HP and AB. The frequency of AA was low in IPF. The cross-reaction of RF with avian antigens was excluded, and no reactivity against human IgG by AA was detected. Other endogenous interferences were ruled out.

CONCLUSION

No single immunological test may definitively distinguish pigeon HP from AB and other interstitial lung disorders; however, positive RF, together with high AA levels, seems to be useful in differentiating the diagnosis.

Hypersensitivity pneumonitis

Hypersensitivity pneumonitis (HP) is a group of immunologically mediated lung diseases caused by the inhalation of environmental agents in susceptible individuals. Most HP patients are non-smokers and have been exposed to organic dusts from vegetable or animal products. Some HP cases are associated with exposures to relatively simple chemical compounds. HP may present as an acute, subacute, or chronic disease and may follow various clinical courses. The type of exposure is thought to be more important in the clinical outcome than the nature of the antigen. A diagnosis of HP is often considered on the basis of clinical history of exposure with resulting respiratory symptoms, but the definitive diagnosis requires a constellation of clinical, radiologic, laboratory, and pathologic findings. The characteristic histologic triad in HP includes bronchiolitis, interstitial lymphocytic infiltration, and granulomas; however, biopsy in HP cases may lack the diagnostic triad and manifest as nonspecific interstitial pneumonia (NSIP). Avoiding exposure to the offending antigen(s) is usually sufficient to resolve symptoms and physiological abnormalities. Pulmonary fibrosis and physiological abnormalities occurring in chronic HP may be irreversible. Steroid therapy is helpful for symptomatic relief, but probably does not affect the long-term prognosis. Type III and type IV hypersensitivity reactions are involved in the pathogenesis; alveolar macrophages and T cells (Th-1 type) play a central role in the immune responses after antigen exposure via their increased interaction and secretion of regulatory mediators.

Takes your breath away--the immunology of allergic alveolitis

Extrinsic allergic alveolitis (synonym: hypersensitivity pneumonitis) is caused by inhaling antigenic aerosols which induce hypersensitivity responses in susceptible individuals. It is an interstitial inflammatory disease affecting the distal, gas-exchanging parts of the lung, in contrast to allergic asthma where the inflammation is more proximal, affecting the conducting airways. The aims of this review are to describe current concepts of the immunology of this model of lung inflammation, to describe some of the constitutional and environmental characteristics which affect disease susceptibility and development, and to describe topics for prospective study.

Mediators of hypersensitivity pneumonitis

Inhalation of Saccharopolyspora rectivirgula (S. rectivirgula) causes farmer's lung disease, a classic example of hypersensitivity pneumonitis (HP). HP is characterized by bronchoalveolar lavage fluid (BALF) neutrophilia (within the first 48 hours after inhalation), followed by BALF lymphocytosis. We utilized a well-described murine model of HP to determine the timing of the appearance of the C-C chemokines monocyte chemoattractant protein-1 (MCP-1) and macrophage inflammatory protein-1alpha (MIP-1alpha); the inflammatory cytokines tumor necrosis factor (TNF), interleukin-1alpha (IL-1alpha), and interleukin-6 (IL-6); and the Th1 -differentiating cytokine interleukin-12 (IL-12) in BALF. After a single intratracheal administration of S. rectivirgula, there was remarkable BALF neutrophilia (peak 24 to 48 hours), followed by a BALF lymphocytosis (peak 48 to 72 hours) in both C57Bl/6 and BALB/c mice that was preceded by the appearance of MIP-1alpha in BALF (peak 4 to 6 hours) and MCP-1 (peak at 48 hours). In both strains of mice there was a striking increase of BALF IL-12 (peak 48 to 72 hours). There was also an increase in BALF IL-6, IL-1alpha, and TNF that was greater in the BALB/c mice than in the C57Bl/6 mice. S. rectivirgula induced the secretion of MIP-1alpha, MCP-1, IL-6, IL-1alpha, and IL-12 from the murine macrophage cell line J774A.1; MIP-1alpha, IL-6, IL-1alpha, IL-12, and TNF from C57Bl/6 alveolar macrophages; and IL-1alpha, IL-6, and TNF-but not IL-12-from BALB/c alveolar macrophages. We conclude that chemokines and cytokines induced by intratracheal administration of S. rectivirgula precede BALF neutrophilia and lymphocytosis and may cause differentiation of Th1 cells; we also conclude that pulmonary macrophages represent a potential source of these substances.