IL-5 in post-traumatic eosinophilic pleural effusion

Pneumothorax-Associated Pleural Eosinophilia in Mice Is Interleukin-5 but Not Interleukin-13 Dependent

STUDY OBJECTIVES

To establish a murine model of pneumothorax-associated pleural eosinophilia and to examine the role of interleukin (IL)-5 and IL-13 in the pathogenesis of this reaction.

DESIGN

An animal study.

INTERVENTIONS

One hundred thirty-seven C57/Bl-6 mice were used in this study. Wild-type animals were injected intrapleurally with 0.4 mL of air and were killed at different time points (30 min to 7 days) after the injection. IL-5 knockout and IL-13 knockout animals were killed 24 h and 48 h after the injection. Pleural inflammation was assessed by pleural lavage (PL).

MEASUREMENTS AND RESULTS

PL cells were significantly increased following the induction of pneumothorax. The peak number of neutrophils, observed at 12 h, was 900 times higher than the control. The peak number of eosinophils, observed at 48 h, was 700 times higher than the control. Lymphocytes and mononuclear cells increased threefold and fourfold, respectively. IL-5 knockout mice had significantly less PL eosinophils than that the wild-type or the IL-13 knockout mice at 24 h (150 +/- 46/microL, 903 +/- 244/microL, and 912 +/- 168/microL, respectively; p = 0.013) and 48 h (181 +/- 45/microL, 1,587 +/- 212/microL, and 1,379 +/- 364/microL, respectively; p = 0.003).

CONCLUSION

Pneumothorax induces an inflammatory reaction of the mouse pleura, mainly characterized by increased neutrophils and eosinophils. IL-5 but not IL-13 is required for pneumothorax-associated pleural eosinophilia.

Eotaxin-3 and interleukin-5 pleural fluid levels are associated with pleural fluid eosinophilia in post-coronary artery bypass grafting pleural effusions

OBJECTIVES

The primary aim of this study was to examine the association between pleural fluid (PF) eosinophilia, and the PF and serum levels of interleukin (IL)-5, eotaxin-2, eotaxin-3, and vascular cell adhesion molecule (VCAM)-1 in patients with post-coronary artery bypass grafting (CABG) pleural effusions.

DESIGN

A prospective observational study.

SETTING

A tertiary teaching hospital.

PATIENTS AND METHODS

Thirty-eight patients with post-CABG pleural effusions were recruited into the study. An effusion that contained at least 10% eosinophils was called "eosinophilic." The PF and serum levels of the cytokines and VCAM-1 were measured using an enzyme-linked immunosorbent assay.

RESULTS

(1) The number of PF eosinophils significantly correlated with the number of blood eosinophils. (2) PF IL-5 levels were significantly higher than the corresponding serum levels, and there was a significant correlation between the PF and serum IL-5 levels. PF IL-5 levels significantly correlated with the PF eosinophil count, and serum IL-5 levels significantly correlated with the number of blood eosinophils. (3) PF eotaxin-3 levels were significantly higher than serum levels, and PF eotaxin-3 levels significantly correlated with the PF eosinophil count. (4) PF VCAM-1 levels were significantly lower than the corresponding serum levels, and PF VCAM-1 levels were significantly higher in eosinophilic pleural effusions (EPEs) than in non-EPEs.

CONCLUSION

In patients with post-CABG pleural effusions, IL-5 and eotaxin-3 are produced preferentially in the pleural cavity, and they are strongly associated with PF eosinophilia.

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.

Eosinophilic pleural effusions

Eosinophilic pleural effusions, defined as a pleural effusion that contains at least 10% eosinophils, may be caused by almost every condition that can cause pleural disease. Eosinophilic pleural effusion occurs most commonly during conditions associated with the presence of blood or air in the pleural space, infections, and malignancy. Drug-induced pleural effusions, pleural effusions accompanying pulmonary embolism, and benign asbestos pleural effusions are also among the common causes of eosinophilic pleural effusion. No etiology is found in as many as one third of patients. Because studies evaluating different diagnostic approaches with eosinophilic pleural effusions are lacking, the authors suggest that certain noninvasive and invasive diagnostic tools must be used based on the patient's clinical characteristics.

Diagnostic value of eosinophils in pleural effusion: a prospective study of 26 cases

Eosinophilic pleural effusions (EPFs), defined as the presence of 10% or more eosinophils in the pleural fluid, are relatively rare. Their diagnostic and prognostic significance, however, remains controversial, as most of the studies are based almost entirely on retrospective case studies. This prospective study examines 26 eosinophilic pleural effusions from among 444 consecutive pleural effusions investigated at this tertiary health care center from October 1999 to April 2002. This study was attempted to unravel the diagnostic and prognostic significance of these eosinophilic effusions and assess their clinical implications, if any. Koss and Light's criteria were applied in the analysis, which comprised macroscopic, biochemical, cytological, and microbiological examinations. Of the 26 EPFs studied, five were associated with tuberculosis and three with metastatic disease. Nineteen patients had significant associated lymphocytosis. Twenty-four patients have been followed up and are in good health to date and have had no recurrence of effusion. Thus, EPF could be associated with inflammatory, benign, and malignant conditions. Hence, a closer search for a definite etiological agent is warranted in the setting of such an effusion, especially in populations endemic for tuberculosis, as in a developing country like India and in populations with a high prevalence of malignancy.

Pleural fluid levels of interleukin-5 and eosinophils are closely correlated

BACKGROUND

The mechanisms responsible for the accumulation of eosinophils in pleural fluid are not fully understood. The purpose of this study was to evaluate the relationship between eosinophil accumulation and the levels of interleukin (IL)-5, IL-3, and granulocyte/macrophage colony-simulating factor (GM-CSF) in pleural effusions.

METHODS

We evaluated 30 patients with eosinophilic pleural effusions (eosinophil count > 10% nucleated cells in pleural fluid) and 10 patients with noneosinophilic pleural effusions. The patients with eosinophilic pleural effusions included 22 patients with post-coronary artery bypass graft surgery pleural effusions and 8 patients with eosinophilic pleural effusions caused by other causes. IL-5, IL-3, and GM-CSF in all pleural fluids were measured using enzyme-linked immunosorbent assay kits.

RESULTS

The mean level of IL-5 in eosinophilic pleural effusions (283.1 +/- 341.6 pg/mL) was significantly (p < 0.025) higher than that in the noneosinophilic effusions (28.2 +/- 19.0 pg/mL). The absolute eosinophil count and percentage correlated significantly with the level of IL-5 in all patients (r = 0.55, p < 0.001, and r = 0.54, p < 0.001, respectively). There was no significant correlation between IL-5 levels and RBC counts in all patients (r = 0.24, p > 0.05). GM-CSF and IL-3 levels were below the detectable range in all pleural fluids.

CONCLUSION

There is a significant relationship between the levels of IL-5 in pleural fluid and the total number and percentage of eosinophils in the pleural fluid. IL-5 seems to be related to the eosinophil accumulation associated with blood or air in the pleural space and other eosinophilic pleural effusions.

Analysis of pleural fluid in idiopathic spontaneous pneumothorax; correlation of eosinophil percentage with the duration of air in the pleural space

Pleural fluid analysis was performed in patients with idiopathic spontaneous pneumothorax. The objective of the study was to define the cell differentiation, and part of the cytokine profile, in relation to the duration of pneumothorax. In the 23 consecutive patients (19 men, mean age 34.2 years, 17 smokers), pleural fluid was obtained immediately after chest tube drainage (n = 6), or during thoracoscopy (n = 17). Cytospins were carried out, and supernatant analysis of the different cytokines was performed using sandwich ELISA. All concentrations were corrected for dilution. The duration of the pneumothorax was correlated with the rise in eosinophil percentage (r = 0.81, P < 0.00001) in pleural fluid. RANTES, platelet-activating factor (PAF), and monocyte chemotactic protein-1 (MCP-1) were detectable but no relationship with eosinophils or duration of the pneumothorax was found. Granulocyte-macrophage colony stimulating factor (GM-CSF) and interluekin-8 (IL-8) were not detectable. Interleukin-5 (IL-5) concentration correlated with the eosinophil concentration (r = 0.84, P = 0.037) and the eosinophil percentage (r = 0.68, P = 0.005) in the pleural fluid. Idiopathic spontaneous pneumothorax causes a time-related rise in the eosinophil percentage in the pleural space, which correlates with the level of IL-5.

Etiology and prognostic significance of eosinophilic pleural effusions. A prospective study

STUDY OBJECTIVE

To determine the diagnostic and prognostic significance of eosinophilic pleural effusions.

DESIGN

A prospective cohort study of patients undergoing thoracentesis between September 1990 and September 1995.

SETTING

A university-affiliated VA Medical Center.

PATIENTS

Four hundred seventy-six consecutive patients.

MEASUREMENTS AND RESULTS

Eosinophilic pleural effusions were identified in 44 of the 476 patients (9.2%). Malignancy was diagnosed as frequently in eosinophilic as in noneosinophilic effusions (20.5% vs 20.1%). The only diagnoses that were significantly associated with eosinophilic effusions were idiopathic (25% vs 8%; p = 0.001) and postthoracic surgery (11% vs 3%; p = 0.023). Median survival was 7.7 months for those with a noneosinophilic effusion compared to 16.8 months for those with eosinophilia (p = 0.017). This difference in survival persisted after adjustment for age and diagnosis.

CONCLUSIONS

We conclude that malignancy is as prevalent among eosinophilic as noneosinophilic pleural effusions. However, the survival of patients with pleural fluid eosinophilia may be better than that of patients with noneosinophilic effusions.