What is eotaxin doing in the pleura? Insights into innate immunity from pleural mesothelial cells

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.

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.

Gene expression patterns and susceptibility to allergic responses

Allergic diseases are due to hypersensitive immune responses against otherwise innocuous allergens, and involve the dysregulated expression of numerous genes in cells from both the innate and adaptive immune systems. Allergic diseases are characterized by the enhanced production of type 2 T helper (Th2) cytokines, including interleukin-4, -5 and -13. These cytokines induce many of the pathophysiologic hallmarks of allergy, and their expression is tightly regulated at the level of gene transcription by both positively and negatively-acting transcription factors. In this review, the authors summarize data indicating that some of these factors represent checkpoints in the development of allergic diseases. Th2 gene expression is also controlled at the level of chromatin remodeling, and the implications of chromatin-based Th2 gene regulation in allergic disorders is also discussed. The differentiation of Th2 cells from naive precursors is critically dependent upon instruction received from dendritic cells, although the precise signals involved in this process are not well understood. Current thinking regarding some of the environmental cues interpreted by dendritic cells during allergen encounter, and how they promote Th2 responses will be reviewed. Understanding the cross-talk between dendritic cells and T cells holds great promise for deciphering the dysregulated immune response in allergy.

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.

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.

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.