Production of eosinophilic chemokines by normal pleural mesothelial cells

A common secretomic signature across epithelial cancers metastatic to the pleura supports IL-6 axis therapeutic targeting

Background

Many cancers metastasize to the pleura, resulting in effusions that cause dyspnea and discomfort. Regardless of the tissue of origin, pleural malignancies are aggressive and uniformly fatal, with no treatment shown to prolong life. The pleural mesothelial monolayer is joined by tight junctions forming a contained bioreactor-like space, concentrating cytokines and chemokines secreted by the mesothelium, tumor, and infiltrating immune cells. This space represents a unique environment that profoundly influences tumor and immune cell behavior. Defining the pleural secretome is an important step in the rational development localized intrapleural immunotherapy.

Method

We measured cytokine/chemokine content of 252 malignant pleural effusion (MPE) samples across multiple cancers using a 40-analyte panel and Luminex multiplexing technology.

Results

Eleven analytes were consistently present in concentrations ≥ 10.0 pM: CXCL10/IP10 (geometric mean = 672.3 pM), CCL2/MCP1 (562.9 pM), sIL-6Rα (403.1 pM), IL-6 (137.6 pM), CXCL1/GRO (80.3 pM), TGFβ1 (76.8 pM), CCL22/MDC (54.8 pM), CXCL8/IL-8 (29.2 pM), CCL11/Eotaxin (12.6 pM), IL-10 (11.3 pM), and G-CSF (11.0 pM). All are capable of mediating chemotaxis, promotion of epithelial to mesenchymal transition, or immunosuppression, and many of are reportedly downstream of a pro-inflammatory cytokine cascade mediated by cytokine IL-6 and its soluble receptor.

Conclusion

The data indicate high concentrations of several cytokines and chemokines across epithelial cancers metastatic to the pleura and support the contention that the pleural environment is the major factor responsible for the clinical course of MPE across cancer types. A sIL-6Rα to IL-6 molar ratio of 2.7 ensures that virtually all epithelial, immune and vascular endothelial cells in the pleural environment are affected by IL-6 signaling. The central role likely played by IL-6 in the pathogenesis of MPE argues in favor of a therapeutic approach targeting the IL-6/IL-6R axis.

Eosinophilic pleural effusion due to Staphylococcus epidermidis infection: A case report

Eosinophilic pleural effusion is rare, and the cause is often obscure. A 73-year-old man with no relevant medical history presented with exertional dyspnea. Chest imaging revealed left-sided pleural effusion, and pleural fluid examination revealed eosinophilic pleural effusion. Blood tests revealed an increased peripheral blood eosinophil count and elevated Immunoglobulin E levels. Staphylococcus epidermidis was detected in pleural specimens collected via thoracoscopy. Antimicrobial therapy targeting Staphylococcus epidermidis resolved the eosinophilic pleural effusion and elevated peripheral blood eosinophil count. Staphylococcus epidermidis infection may be considered as a cause of eosinophilic pleural effusion when the diagnosis is difficult.

Necroptosis triggers spatially restricted neutrophil-mediated vascular damage during lung ischemia reperfusion injury

Intravital imaging, oxidative lipidomics, and a transplant model were used to define mechanisms that regulate neutrophil recruitment into lungs during ischemia reperfusion injury, a clinically relevant form of sterile inflammation. We found that early neutrophil-mediated damage is largely confined to the subpleural vasculature, a process that is orchestrated by a spatially restricted distribution of nonclassical monocytes that produce chemokines following necroptosis of pulmonary cells. Neutrophils disrupt the integrity of subpleural capillaries, which is associated with impaired lung function. Neutrophil-mediated vascular leakage is dependent on TLR4 expression on vascular endothelium, NOX4 signaling, and formation of neutrophil extracellular traps. Our research provides insights into mechanisms that regulate neutrophil recruitment during sterile lung inflammation and lays the foundation for developing new therapies.

Ischemia reperfusion injury represents a common pathological condition that is triggered by the release of endogenous ligands. While neutrophils are known to play a critical role in its pathogenesis, the tissue-specific spatiotemporal regulation of ischemia-reperfusion injury is not understood. Here, using oxidative lipidomics and intravital imaging of transplanted mouse lungs that are subjected to severe ischemia reperfusion injury, we discovered that necroptosis, a nonapoptotic form of cell death, triggers the recruitment of neutrophils. During the initial stages of inflammation, neutrophils traffic predominantly to subpleural vessels, where their aggregation is directed by chemoattractants produced by nonclassical monocytes that are spatially restricted in this vascular compartment. Subsequent neutrophilic disruption of capillaries resulting in vascular leakage is associated with impaired graft function. We found that TLR4 signaling in vascular endothelial cells and downstream NADPH oxidase 4 expression mediate the arrest of neutrophils, a step upstream of their extravasation. Neutrophil extracellular traps formed in injured lungs and their disruption with DNase prevented vascular leakage and ameliorated primary graft dysfunction. Thus, we have uncovered mechanisms that regulate the initial recruitment of neutrophils to injured lungs, which result in selective damage to subpleural pulmonary vessels and primary graft dysfunction. Our findings could lead to the development of new therapeutics that protect lungs from ischemia reperfusion injury.

Clinical and pathophysiological characteristics of valproate-induced pleural effusion

INTRODUCTION

Valproic acid is a carboxylic acid derivative commonly prescribed for several types of seizure disorders or for acute manic episodes in patients with bipolar disorder. Several cases of valproate-induced pleural effusion have been reported, although the precise pathophysiological mechanism remains unknown.

OBJECTIVE

To describe the presentation of pleural effusion associated with valproate use and to categorize published case reports according to clinical, immunological, and pleural effusion cell type.

METHODS

PubMed/MEDLINE and Embase databases were systematically searched from January 1970 until November 2020 using the following search terms: "valproic acid" OR "valproate" OR "pleural fluid" OR "exudative effusion" OR "transudative effusion" OR "valproic lung adverse events". These searches yielded 171 references of which 135 articles were considered irrelevant, leaving 36 potentially relevant references which were carefully scrutinized. Twenty-eight cases of valproate-induced pleural effusion were identified after excluding two articles reporting five patients with lung parenchymal adverse reactions to treatment with valproic acid; two articles reporting three patients in whom the pleural effusion could not be attributed to valproic acid alone; one case discussing valproate therapy and fungal pleural effusion; and one describing a patient who suffered from severe cardiac failure. There were also two cases, in an abstract form, with pericardial and pleural effusion, but without any further informative details, and, thus, they were also excluded from this survey.

EXUDATIVE EOSINOPHILIC PLEURAL EFFUSION

This was the most common type of valproate-induced pleural effusion reported in 17 out of 28 cases (60.7%), with concurrent peripheral eosinophilia in ten. Acute hypersensitivity reaction, inflammation of the pleural cavity induced by the drug, drug toxicity, and damage to mesothelial cells due to oxidants, comprise the possible pivotal mechanisms.

EXUDATIVE LYMPHOCYTIC PLEURAL EFFUSION

This was reported in two cases, with concurrent pericardial effusion in one. Discontinuation of valproate led to resolution of the effusion, although the underlying pathophysiological mechanisms remain abstruse. Interestingly, a patient presented with recurrent pleural effusion characterized by transition from eosinophilic to lymphocytic predominance after readministration of valproate.

TRANSUDATIVE PLEURAL EFFUSION

Three out of 28 cases (10.7%) were characterized by neutrophilic transudative pleural effusion after long-term therapy with valproate, while concurrent pericardial effusion was also noted in two.

VALPROATE-INDUCED LUPUS ERYTHEMATOSUS WITH PLEURAL EFFUSION

Five patients receiving valproate therapy (17.9% out of the 28 cases) developed drug-induced lupus erythematosus with concurrent pleural effusion that was eosinophilic in three. All patients had positive antinuclear antibodies; anti-histone antibodies were positive in two.

CONCLUSIONS

Valproate-induced pleural effusion is rare, but patients receiving treatment with valproic acid who develop respiratory symptoms should be examined for valproate-induced pleural effusion.

Eosinophilic Pleural Effusion in a Young Woman With Pleural Nodularity and Lytic Skeletal Lesions

CASE PRESENTATION

A 21-year-old woman, a housewife with no known comorbidities, presented to the outpatient department with complaints of dry cough, left-sided pleuritic chest pain, modified Medical Research Council grade II breathlessness and backache. She had started developing these symptoms 1 month earlier. There was no history of fever, hemoptysis, or significant weight loss. She had no features suggestive of connective tissue disorder. There was no history of recurrent respiratory infections in the past. She was married for 1 year and had no children. Her sleep, bowel, and bladder habits were normal. No significant family history or medication history was noted.

Molecular Biology of Atherosclerotic Ischemic Strokes

Among the causes of global death and disability, ischemic stroke (also known as cerebral ischemia) plays a pivotal role, by determining the highest number of worldwide mortality, behind cardiomyopathies, affecting 30 million people. The etiopathogenetic burden of a cerebrovascular accident could be brain ischemia (~80%) or intracranial hemorrhage (~20%). The most common site when ischemia occurs is the one is perfused by middle cerebral arteries. Worse prognosis and disablement consequent to brain damage occur in elderly patients or affected by neurological impairment, hypertension, dyslipidemia, and diabetes. Since, in the coming years, estimates predict an exponential increase of people who have diabetes, the disease mentioned above constitutes together with stroke a severe social and economic burden. In diabetic patients after an ischemic stroke, an exorbitant activation of inflammatory molecular pathways and ongoing inflammation is responsible for more severe brain injury and impairment, promoting the advancement of ischemic stroke and diabetes. Considering that the ominous prognosis of ischemic brain damage could by partially clarified by way of already known risk factors the auspice would be modifying poor outcome in the post-stroke phase detecting novel biomolecules associated with poor prognosis and targeting them for revolutionary therapeutic strategies.

MKEY, a Peptide Inhibitor of CXCL4-CCL5 Heterodimer Formation, Protects Against Stroke in Mice

Background

MKEY, a synthetic cyclic peptide inhibitor of CXCL4–CCL5 heterodimer formation, has been shown to protect against atherosclerosis and aortic aneurysm formation by mediating inflammation, but whether it modulates neuroinflammation and brain injury has not been studied. We therefore studied the role of MKEY in stroke‐induced brain injury in mice.

Methods and Results

MKEY was injected into mice after stroke with 60 minutes of middle cerebral artery occlusion. Infarct volume and neurological deficit scores were measured. Protein levels of CCL5 and its receptor CCR5 were detected by Western blot and fluorescence‐activated cell sorting (FACS), respectively. Numbers of microglia‐derived macrophages (MiMΦs) and monocyte‐derived MΦs (MoMΦs) in the brain, and their subsets, based on the surface markers CD45, CD11b, CCR2, CX3CR1, and Ly6C, were analyzed by FACS. MΦs and neutrophil infiltration in the ischemic brain were stained with CD68 and myeloperoxidase (MPO), respectively, and assessed by immunofluorescent confocal microscopy. The results showed that expressions of CCL5 and its receptor CCR5, were increased in the ischemic brain after stroke. MKEY injection significantly reduced infarct sizes and improved neurological deficit scores measured 72 hours after stroke. In addition, MKEY injection inhibited the number of MoMΦs, but not MiMΦs, in the ischemic brain. Furthermore, MKEY inhibited protein expression levels of Ly6C,CCR2, and CX3CR1 on MoMΦs. Lastly, the confocal study also suggests that the number of CD68‐positive MΦs and MPO‐positive neutrophils was inhibited by MKEY injection.

Conclusions

MKEY injection protects against stroke‐induced brain injury, probably by inhibiting MoMΦ‐mediated neuroinflammation.

CREB-induced inflammation is important for malignant mesothelioma growth

Malignant mesothelioma (MM) is an aggressive tumor with no treatment regimen. Previously we have demonstrated that cyclic AMP response element binding protein (CREB) is constitutively activated in MM tumor cells and tissues and plays an important role in MM pathogenesis. To understand the role of CREB in MM tumor growth, we generated CREB-inhibited MM cell lines and performed in vitro and in vivo experiments. In vitro experiments demonstrated that CREB inhibition results in significant attenuation of proliferation and drug resistance of MM cells. CREB-silenced MM cells were then injected into severe combined immunodeficiency mice, and tumor growth in s.c. and i.p. models of MM was followed. We observed significant inhibition in MM tumor growth in both s.c. and i.p. models and the presence of a chemotherapeutic drug, doxorubicin, further inhibited MM tumor growth in the i.p. model. Peritoneal lavage fluids from CREB-inhibited tumor-bearing mice showed a significantly reduced total cell number, differential cell counts, and pro-inflammatory cytokines and chemokines (IL-6, IL-8, regulated on activation normal T cell expressed and secreted, monocyte chemotactic protein-1, and vascular endothelial growth factor). In vitro studies showed that asbestos-induced inflammasome/inflammation activation in mesothelial cells was CREB dependent, further supporting the role of CREB in inflammation-induced MM pathogenesis. In conclusion, our data demonstrate the involvement of CREB in the regulation of MM pathogenesis by regulation of inflammation.

Eotaxin-1 is involved in parasite clearance during chronic filarial infection

Eosinophil migration as key feature of helminth infection is increased during infection with filarial nematodes. In a mouse model of filariasis, we investigated the role of the eosinophil-attracting chemokine Eotaxin-1 on disease outcome. BALB/c and Eotaxin-1(-/-) mice were infected with the rodent filaria Litomosoides sigmodontis, and parasitic parameters, cellular migration to the site of infection, and cellular responsiveness were investigated. We found increased parasite survival but unaffected eosinophil migration to the site of infection in Eotaxin-1(-/-) mice. Expression of CD80 and CD86 was reduced on eosinophils from Eotaxin-1(-/-) mice after in vitro TLR2 stimulation and exposure to filarial antigen, respectively, suggesting a potential reduced activation state of eosinophils in Eotaxin-1 deficient mice. We further demonstrated that macrophages from Eotaxin-1(-/-) mice produce decreased amounts of IL-6 in vitro, a cytokine found to be associated with parasite containment, suggesting possible mechanisms by which Eotaxin-1 regulates activation of inflammatory cells and thus parasite survival.

Extracellular signal-regulated kinase 5: a potential therapeutic target for malignant mesotheliomas

PURPOSE

Malignant mesothelioma is a devastating disease with a need for new treatment strategies. In the present study, we showed the importance of extracellular signal-regulated kinase 5 (ERK5) in malignant mesothelioma tumor growth and treatment.

EXPERIMENTAL DESIGN

ERK5 as a target for malignant mesothelioma therapy was verified using mesothelial and mesothelioma cell lines as well as by xenograft severe combined immunodeficient (SCID) mouse models.

RESULTS

We first showed that crocidolite asbestos activated ERK5 in LP9 cells and mesothelioma cell lines exhibit constitutive activation of ERK5. Addition of doxorubicin resulted in further activation of ERK5 in malignant mesothelioma cells. ERK5 silencing increased doxorubicin-induced cell death and doxorubicin retention in malignant mesothelioma cells. In addition, shERK5 malignant mesothelioma lines exhibited both attenuated colony formation on soft agar and invasion of malignant mesothelioma cells in vitro that could be related to modulation of gene expression linked to cell proliferation, apoptosis, migration/invasion, and drug resistance as shown by microarray analysis. Most importantly, injection of shERK5 malignant mesothelioma cell lines into SCID mice showed significant reduction in tumor growth using both subcutaneous and intraperitoneal models. Assessment of selected human cytokine profiles in peritoneal lavage fluid from intraperitoneal shERK5 and control tumor-bearing mice showed that ERK5 was critical in regulation of various proinflammatory (RANTES/CCL5, MCP-1) and angiogenesis-related (interleukin-8, VEGF) cytokines. Finally, use of doxorubicin and cisplatin in combination with ERK5 inhibition showed further reduction in tumor weight and volume in the intraperitoneal model of tumor growth.

CONCLUSION

ERK5 inhibition in combination with chemotherapeutic drugs is a beneficial strategy for combination therapy in patients with malignant mesothelioma.

CCL25 induces α₄β₇ integrin-dependent migration of IL-17⁺ γδ T lymphocytes during an allergic reaction

Herein, we provide evidence that during allergic inflammation, CCL25 induces the selective migration of IL-17(+) γδ T cells mediated by α(4) β(7) integrin. Intrapleural injection of CCL25 into ovalbumin (OVA)-immunized C57BL/6 mice triggered the accumulation of γδ T lymphocytes expressing CCR9 (CCL25 receptor) and α(4) β(7) integrin in the pleura, but failed to attract αβ T lymphocytes. CCL25 attracted CCR6(+) γδ T cells producing IL-17 (but not IFN-γ or IL-4). OVA challenge triggered increased production of CCL25 followed by the accumulation of CCR9(+) , α(4) β(7) (+) , and CCR6(+) /IL-17(+) γδ T cells into the pleural cavities of OVA-immunized mice, which was inhibited by the in vivo neutralization of CCL25. The in vivo blockade of α(4) β(7) integrin also inhibited the migration of IL-17(+) γδ T lymphocytes (but not of αβ T lymphocytes) into mouse pleura after OVA challenge, suggesting that the CCL25/α(4) β(7) integrin pathway is selective for γδ T cells. In addition, α(4) β(7) integrin blockade impaired the in vitro transmigration of γδ T cells across endothelium (which expresses α(4) β(7) ligands VCAM-1 and MadCAM-1), which was induced by CCL25 and by cell-free pleural washes recovered from OVA-challenged mice. Our results reveal that during an allergic reaction, CCL25 drives IL-17(+) γδ T-cell mobilization to inflamed tissue via α(4) β(7) integrin and modulates IL-17 levels.

The chemokine CXCL12 is essential for the clearance of the filaria Litomosoides sigmodontis in resistant mice

Litomosoides sigmodontis is a cause of filarial infection in rodents. Once infective larvae overcome the skin barrier, they enter the lymphatic system and then settle in the pleural cavity, causing soft tissue infection. The outcome of infection depends on the parasite's modulatory ability and also on the immune response of the infected host, which is influenced by its genetic background. The goal of this study was to determine whether host factors such as the chemokine axis CXCL12/CXCR4, which notably participates in the control of immune surveillance, can influence the outcome of the infection. We therefore set up comparative analyses of subcutaneous infection by L. sigmodontis in two inbred mouse strains with different outcomes: one susceptible strain (BALB/c) and one resistant strain (C57BL/6). We showed that rapid parasite clearance was associated with a L. sigmodontis-specific CXCL12-dependent cell response in C57BL/6 mice. CXCL12 was produced mainly by pleural mesothelial cells during infection. Conversely, the delayed parasite clearance in BALB/c mice was neither associated with an increase in CXCL12 levels nor with cell influx into the pleural cavity. Remarkably, interfering with the CXCL12/CXCR4 axis in both strains of mice delayed filarial development, as evidenced by the postponement of the fourth molting process. Furthermore, the in vitro growth of stage 4 filariae was favored by the addition of low amounts of CXCL12. The CXCL12/CXCR4 axis thus appears to have a dual effect on the L. sigmodontis life cycle: by acting as a host-cell restriction factor for infection, and as a growth factor for worms.

Quercetin regulates Th1/Th2 balance in a murine model of asthma

Quercetin is found to be the most active of the flavonoids in studies and many medicinal plants owe much of their activity to their high Quercetin content. Quercetin has demonstrated significant anti-inflammatory activity because of direct inhibition of several initial processes of inflammation. However, its anti-allergic effect in the Th1/Th2 immune response was poorly understood. Recently, it was shown that T-bet and GATA-3 were master Th1 and Th2 regulatory transcription factors. In this study, we have attempted to determine whether Quercetin regulates Th1/Th2 cytokine production, T-bet and GATA-3 gene expression in OVA-induced asthma model mice. Quercetin reduced the increased levels of IL-4, Th2 cytokine production in OVA-sensitized and -challenged mice. The other side, it increased IFN-gamma, Th1 cytokine production in Quercetin administrated mice. We also examined to ascertain whether Quercetin could influence Eosinophil peroxidase (EPO) activity. The administration of Quercetin before the last airway OVA challenge resulted in a significant inhibition of all asthmatic reactions. Accordingly, this study may provide evidence that Quercetin plays a critical role in the amelioration of the pathogenetic process of asthma in mice. These findings provide new insight into the immunopharmacological role of Quercetin in terms of its effects in a murine model of asthma, and also broaden current perspectives in our understanding of the immunopharmacological functions of Quercetin.

Expression of CXC and CC type of chemokines and its receptors in tuberculous and non-tuberculous effusions

Chemokines mediate their biological functions by transmigration of various immune cells to the site of infection. Tuberculous pleurisy provides an effective model to study the role of chemokines in the recruitment of immune cells to the pleura. Our aim was to understand the cumulative effect of chemokines (IP-10, MIG, IL-8, MCP-1, MIP-1alpha and RANTES) and its receptors (CXCR2, CXCR3, CCR1, CCR2, CCR5 and CCR7) in the recruitment of CD4(+) T cells obtained from blood (BL) and pleural fluid (PF) of tuberculous (TB) and non-tuberculous (NTB) patients. We observed significant increase in CD4(+) T cells in TB PF indicating lymphocytic rich effusion. All chemokines except RANTES were significantly high in PF compared to BL in TB group, whereas IL-8 and MCP-1 showed significant increase only in NTB PF. The significantly high levels of IFN-gamma and TauNuF-alpha in TB PF and their positive correlation with IP-10 and MIP-1alpha indicated their synergistic action to elicit a strong protective Th1 response. In spite of high levels of Th1 cytokines and chemokines in TB PF, significantly lower levels of RANTES indicated its limited role at the site. The CXC receptors in PF of both the groups and CC receptors except CCR5 in TB PF were significantly high compared to BL. Only CXCR2, CCR5 and CCR7 showed significant increase in TB compared to NTB. Thus a selective concentration of chemokines, cytokines and abundant expression of chemokine receptors confirm the accumulation of activated and memory T cells at the site of infection and help in polarizing Th1 immune response.

Involvement of CC chemokines in gammadelta T lymphocyte trafficking during allergic inflammation: the role of CCL2/CCR2 pathway

In the present study, we show that the intra-thoracic injection of ovalbumin (OVA, 12.5 microg per cavity) into C57BL/10 mice induced a significant increase in gammadelta T lymphocyte numbers in the pleural cavity, blood and thoracic lymph node of challenged mice. Such increase was significant within 12 h, peaked within 48 h and returned to basal counts within 120 h. Levels of CC chemokine ligand (CCL)-2/monocyte chemotactic protein-1, CCL5/regulated upon activation, normal T cell expressed and secreted, CCL3/macrophage inflammatory protein-1 alpha and CCL25/thymus-expressed chemokine were above control values in pleural washes recovered 24 h after OVA challenge (OPW) and were likely produced by pleural macrophages and mesothelial cells. Antigenic challenge also induced an up-regulation in CC chemokine receptor (CCR)-2, CCR5 and CCR9 on gammadelta T cells from pleural cavities, blood and lymph nodes, suggesting that cells found in mice pleural cavity migrate from secondary lymphoid organs into the inflammatory site via blood stream. The in vitro neutralization of CCL2 (but not of CCL3, CCL5 or CCL25) abrogated OPW-induced gammadelta T lymphocyte transmigration. Confirming such results, the in vivo administration of alpha-CCL2 mAb inhibited gammadelta T lymphocyte accumulation in the pleural cavity of challenged mice, whereas the blockade of CCL3, CCL5 or CCL25 showed no effect on gammadelta T cell mobilization. In addition, OVA challenge failed to induce gammadelta T lymphocyte accumulation in the pleural cavity of C57BL/6 CCR2 knockout mice, which also showed decreased numbers of these cells in blood and lymph nodes when compared with wild-type mice. Overall, such results demonstrate that CCR2/CCL2 pathway is crucial for gammadelta T lymphocyte mobilization during the allergic response.

Overexpression of suppressor of cytokine signalling-5 augments eosinophilic airway inflammation in mice

BACKGROUND

Enhanced expression of the suppressor of cytokine signalling (SOCS)-5 might be of therapeutic benefit for T-helper type 2 (Th2) dominant diseases, as its expression is reported to result in a reduction of Th2 differentiation in vitro due to the inhibition of IL-4 signalling.

OBJECTIVE

To investigate the regulatory role of SOCS-5 in vivo, we explored the phenotype of an experimental asthma model developed in SOCS-5 transgenic (Tg) mice.

METHODS

The SOCS-5 Tg mice or wild-type (WT) mice were sensitized and repeatedly challenged with ovalbumin (OVA). We examined bronchoalveolar lavage fluid (BALF), lung specimens, and airway hyperresponsiveness (AHR) to methacholine.

RESULTS

The production of IFN-gamma by CD4(+) T cells from unprimed SOCS-5 Tg mice was significantly increased in comparison with unprimed wild-type mice, indicating that SOCS-5 Tg mice have a Th1-polarizing condition under natural conditions. However, in an asthma model, significantly more eosinophils in the airways and higher levels of IL-5 and IL-13 in BALF were observed in the SOCS-5 Tg than the wild-type mice. AHR in the asthma model of SOCS-5 Tg was also more enhanced than that of wild-type mice. OVA-stimulated CD4(+) T cells from the primed SOCS-5 Tg mice produced significantly more IL-5 and IL-13 than CD4(+) T cells from wild-type mice.

CONCLUSION

Our results demonstrate that the overexpression of SOCS-5 does not inhibit Th2 response, but rather augments the phenotype of the asthma model in vivo. This finding throws into question the therapeutic utility of using enhancement of SOCS-5 expression for Th2-dominant disease.

Anti-tumor necrosis factor-alpha antibody treatment reduces pulmonary inflammation and methacholine hyper-responsiveness in a murine asthma model induced by house dust

BACKGROUND/AIMS

Recent studies documented that sensitization and exposure to cockroach allergens significantly increase children's asthma morbidity as well as severity, especially among inner city children. TNF-alpha has been postulated to be a critical mediator directly contributing to the bronchopulmonary inflammation and airway hyper-responsiveness in asthma. This study investigated whether an anti-TNF-alpha antibody would inhibit pulmonary inflammation and methacholine (Mch) hyper-responsiveness in a mouse model of asthma induced by a house dust extract containing both endotoxin and cockroach allergens.

METHODS

A house dust sample was extracted with phosphate-buffered saline and then used for immunization and two additional pulmonary challenges of BALB/c mice. Mice were treated with an intravenous injection of anti-TNF-alpha antibody or control antibody 1 h before each pulmonary challenge.

RESULTS

In a kinetic study, TNF-alpha levels within the bronchoalveolar lavage (BAL) fluid increased quickly peaking at 2 h while BAL levels of IL-4, IL-5, and IL-13 peaked at later time-points. Mch hyper-responsiveness was measured 24 h after the last challenge, and mice were killed 24 h later. TNF inhibition resulted in an augmentation of these Th2 cytokines. However, the allergic pulmonary inflammation was significantly reduced by anti-TNF-alpha antibody treatment as demonstrated by a substantial reduction in the number of BAL eosinophils, lymphocytes, macrophages, and neutrophils compared with rat IgG-treated mice. Mch hyper-responsiveness was also significantly reduced in anti-TNF-alpha antibody-treated mice and the pulmonary histology was also significantly improved. Inhibition of TNF significantly reduced eotaxin levels within the lung, suggesting a potential mechanism for the beneficial effects. These data indicate that anti-TNF-alpha antibody can reduce the inflammation and pathophysiology of asthma in a murine model of asthma induced by a house dust extract.

Synergy in cytokine and chemokine networks amplifies the inflammatory response

The inflammatory response is a highly co-ordinated process involving multiple factors acting in a complex network as stimulators or inhibitors. Upon infection, the sequential release of exogenous agents (e.g. bacterial and viral products) and induction of endogenous mediators (e.g. cytokines and chemokines) contribute to the recruitment of circulating leukocytes to the inflamed tissue. Microbial products trigger multiple cell types to release cytokines, which in turn are potent inducers of chemokines. Primary cytokines act as endogenous activators of the immune response, whereas inducible chemokines act as secondary mediators to attract leukocytes. Interaction between exogenous and endogenous mediators thus enhances the inflammatory response. In this review, the synergistic interaction between cytokines to induce chemokine production and the molecular mechanisms of the cooperation amongst co-induced chemokines to further increase leukocyte recruitment to the site of inflammation are discussed.

A novel effect for annexin 1-derived peptide ac2-26: reduction of allergic inflammation in the rat

Previous investigations have provided evidence that the N-terminal peptide of annexin 1 (peptide Ac2-26) has the capacity of reproducing the anti-inflammatory actions of the full-length protein in many systems. In the current study, we report the effectiveness of the peptide Ac2-26 as an antiallergic tool in a model of rat pleurisy and provide indication for some of the mechanisms involved. In rats inflamed by injection of ovalbumin into the pleural cavity 14 days postsensitization, peptide Ac2-26 (50-200 microg/cavity) inhibited mast cell degranulation, plasma protein leakage, and the accumulation of both neutrophils and eosinophils. Treatment with either peptide Ac2-26 (200 microg/cavity) or dexamethasone (1 mg/kg i.p.) inhibited ovalbumin-induced eotaxin release in the pleural effluents. In vitro, peptide Ac2-26 inhibited ovalbumin-evoked histamine release from subcutaneous tissue fragments obtained from sensitized rats (33-66 microM) and interleukin-13-evoked eotaxin generation from cultured rat mesothelial cells (16-33 microM) but not eosinophil chemotaxis. This work demonstrates that the annexin 1 mimetic peptide Ac2-26 prevents allergen-evoked eosinophilic inflammatory response in rats. Combined analysis of the in vivo and in vitro experiments presented herein suggests that the blockade of secretion of pivotal mediators for the allergic response, such as histamine and eotaxin, could be responsible for the inhibitory actions displayed by peptide Ac2-26.

Pathogenesis of the eosinophilic pleural effusions

PURPOSE OF REVIEW

Eosinophilic pleural effusions (EPE) are defined as those that contain at least 10% eosinophils. EPEs account for 5 to 16% of exudative pleural effusions. However, their pathogenesis is poorly understood. The purpose of this review is to discuss the mechanisms that lead to eosinophilic pleural inflammation.

RECENT FINDINGS

Eosinophilic pleural effusions are caused by the presence of air or blood or both in the pleural space, infectious or other inflammatory diseases, malignancy, pulmonary emboli, asbestos exposure, and drug reactions. Differences in the clinical features suggest that a variety of mechanisms operate to induce eosinophilic pleural inflammation and pleural fluid accumulation. Human and animal studies indicate that interleukin (IL)-5 is an important common contributor of different pathogenetic pathways. The possible role of other cytokines, chemokines, and adhesion molecules in the development of EPE is under investigation.

SUMMARY

Understanding the pathogenesis of EPE will permit the development of novel therapies for the persistent, symptomatic, posttraumatic and idiopathic EPE. Anti-IL-5 treatment is an interesting option that requires further research.

The role of RANTES in a murine model of food allergy

Food allergy is an important and common health issue, and there is a need to identify and characterize the sensitizing mechanisms. One of the common causes of food allergy is ovalbumin (OVA), a dietary antigen from eggs. We hypothesized that OVA-induced food allergy in the gut involves the activation of the chemokine regulated on activation, normal T cell expressed and secreted (RANTES), which then recruits eosinophils to lesioned tissue. The purpose of this study was to clarify whether RANTES expression correlates with eosinophil infiltration in the gut of OVA-sensitized BALB/c mice in response to oral OVA challenge. BALB/c mice were immunized with OVA 1 microg and sensitized after 2 weeks by intragastric administration of OVA. Sensitization to the oral OVA challenge was analyzed by examining eosinophil infiltration into the gut tissue (immunohistochemistry), mucosal eosinophil cationic protein (ECP) concentration, and RANTES mRNA expression (reverse-transcriptase polymerase chain reaction and Southern blotting) at 3, 6, 12, and 24 h after the challenge. There was marked edema of the intestinal villi, and eosinophil infiltration to the lamina propria peaked at 6 h in OVA-sensitized mice. RANTES mRNA expression peaked at 3 h and 6 h and declined thereafter. The expression of RANTES mRNA in the allergic mice was much higher than in the nonallergic, normal, or unsensitized control mice. Tissue eosinophilia and intestinal ECP levels were significantly correlated with the RANTES mRNA level. We conclude that RANTES may play a central role in the pathogenesis of food-mediated gastrointestinal allergy.

CCL11 (Eotaxin) induces CCR3-dependent smooth muscle cell migration

OBJECTIVE

CCL11 (Eotaxin) is a potent eosinophil chemoattractant that is abundant in atheromatous plaques. The major receptor for CCL11 is CCR3, which is found on leukocytes and on some nonleukocytic cells. We sought to determine whether vascular smooth muscle cells (SMCs) possessed functional CCR3.

METHODS AND RESULTS

CCR3 mRNA (by RT-PCR) and protein (by Western blot analysis and flow cytometry) were present in mouse aortic SMCs. CCL11 induced concentration-dependent SMC chemotaxis in a modified Boyden chamber, with maximum effect seen at 100 ng/mL. SMC migration was markedly inhibited by antibody to CCR3, but not to CCR2. CCL11 also induced CCR3-dependent SMC migration in a scrape-wound assay. CCL11 had no effect on SMC proliferation. CCR3 and CCL11 staining were minimal in the normal arterial wall, but were abundant in medial SMC and intimal SMC 5 days and 28 days after mouse femoral arterial injury, respectively, times at which SMCs possess a more migratory phenotype.

CONCLUSIONS

These data demonstrate that SMCs possess CCR3 under conditions associated with migration and that CCL11 is a potent chemotactic factor for SMCs. Because CCL11 is expressed abundantly in SMC-rich areas of the atherosclerotic plaque and in injured arteries, it may play an important role in regulating SMC migration.

IFN-γ-induced SOCS-1 regulates STAT6-dependent eotaxin production triggered by IL-4 and TNF-α

The production of eotaxin, which is a critical mediator for airway inflammation, is inhibited by IFN-gamma. Here, we investigated the precise mechanisms underlying IFN-gamma-dependent inhibition of eotaxin production using mouse embryonic fibroblasts (MEF). MEF produced high levels of eotaxin in STAT6-dependent manner when they were cultured with both IL-4 and TNF-alpha. However, the eotaxin production by MEF was strongly inhibited by addition of IFN-gamma. Western-blotting analysis demonstrated that IFN-gamma downmodulated STAT6 phosphorylation induced by IL-4 and TNF-alpha. Moreover, IFN-gamma did not exhibit its inhibitory effect on both STAT6-phosphorylation and eotaxin production in MEF obtained from deficient mice in STAT1, a key molecule of IFN-gamma signaling. We also demonstrated that SOCS-1, a potent inhibitory molecule of IL-4 signaling, was induced by IFN-gamma in STAT1-dependent manner. This indicated that SOCS-1 might be involved in IFN-gamma-mediated STAT1-dependent inhibition of eotaxin production. In SOCS-1(-/-) MEF, IFN-gamma inhibited neither STAT6 phosphorylation nor eotaxin production induced by IL-4 and TNF-alpha. Conversely, retroviral transduction of SOCS-1 into MEF inhibited STAT6 phosphorylation and eotaxin production induced by IL-4 and TNF-alpha, in the absence of IFN-gamma. Thus, we demonstrated that IFN-gamma-induced inhibition of STAT6 phosphorylation and eotaxin production were mediated by SOCS-1 induced in STAT1-dependent manner.

Resistance and susceptibility to filarial infection with Litomosoides sigmodontis are associated with early differences in parasite development and in localized immune reactions

In order to understand natural resistance to filariasis, we compared Litomosoides sigmodontis primary infection of C57BL/6 mice, which eliminate the worms before patency, and BALB/c mice, in which worms complete their development and produce microfilariae. Our analysis over the first month of infection monitoredmigration of the infective larvae from the lymph nodes to the pleural cavity, where the worms settle. Although immune responses from the mouse strains differed from the outset, the duration of lymphatic migration (4 days) and filarial recovery rates were similar, thus confirming that the proportion of larvae that develop in the host species upon infection is not influenced by host genetic variability. The majority of worms reached the adult stage in both mouse strains; however, worm growth and molting were retarded in resistant C57BL/6 mice. Surprisingly, the only immune responses detected at 60 h postinfection occurred in the susceptible mice and only upon stimulation of cells from lymph nodes draining the inoculation site with infective larva extract: massive production of interleukin-6 (IL-6) and IL-5 (the latter cytokine was previously suspected to have an effect on L. sigmodontis growth). However, between days 10 and 30 postinfection, extraordinarily high levels of type 1 and type 2 cytokines and expansion of pleural leukocyte infiltration were seen in the resistant C57BL/6 mice, explaining the destruction of worms later. Our results suggest that events early in the infection determine susceptibility or resistance to subsequent microfilarial production and a parasite strategy to use specific immune responses to its own benefit.

Mesothelial cells: their structure, function and role in serosal repair

The mesothelium is composed of an extensive monolayer of specialized cells (mesothelial cells) that line the body's serous cavities and internal organs. Traditionally, this layer was thought to be a simple tissue with the sole function of providing a slippery, non-adhesive and protective surface to facilitate intracoelomic movement. However, with the gradual accumulation of information about serosal tissues over the years, the mesothelium is now recognized as a dynamic cellular membrane with many important functions. These include transport and movement of fluid and particulate matter across the serosal cavities, leucocyte migration in response to inflammatory mediators, synthesis of pro-inflammatory cytokines, growth factors and extracellular matrix proteins to aid in serosal repair, release of factors to promote both the deposition and clearance of fibrin, and antigen presentation. Furthermore, the secretion of molecules, such as glycosaminoglycans and lubricants, not only protects tissues from abrasion, but also from infection and possibly tumour dissemination. Mesothelium is also unlike other epithelial-like surfaces because healing appears diffusely across the denuded surface, whereas in true epithelia, healing occurs solely at the wound edges as sheets of cells. Although controversial, recent studies have begun to shed light on the mechanisms involved in mesothelial regeneration. In the present review, the current understanding of the structure and function of the mesothelium and the biology of mesothelial cells is discussed, together with recent insights into the mechanisms regulating its repair.