Cytokine levels in pleural effusions of patients under intensive care

Vaccination with Mycoplasma pneumoniae membrane lipoproteins induces IL-17A driven neutrophilia that mediates Vaccine-Enhanced Disease

Bacterial lipoproteins are an often-underappreciated class of microbe-associated molecular patterns with potent immunomodulatory activity. We previously reported that vaccination of BALB/c mice with Mycoplasma pneumoniae (Mp) lipid-associated membrane proteins (LAMPs) resulted in lipoprotein-dependent vaccine enhanced disease after challenge with virulent Mp, though the immune responses underpinning this phenomenon remain poorly understood. Herein, we report that lipoprotein-induced VED in a mouse model is associated with elevated inflammatory cytokines TNF-α, IL-1β, IL-6, IL-17A, and KC in lung lavage fluid and with suppurative pneumonia marked by exuberant neutrophilia in the pulmonary parenchyma. Whole-lung-digest flow cytometry and RNAScope analysis identified multiple cellular sources for IL-17A, and the numbers of IL-17A producing cells were increased in LAMPs-vaccinated/Mp-challenged animals compared to controls. Specific IL-17A or neutrophil depletion reduced disease severity in our VED model—indicating that Mp lipoproteins induce VED in an IL-17A-dependent manner and through exuberant neutrophil recruitment. IL-17A neutralization reduced levels of TNF-α, IL-1β, IL-6, and KC, indicating that IL-17A preceded other inflammatory cytokines. Surprisingly, we found that IL-17A neutralization impaired bacterial clearance, while neutrophil depletion improved it—indicating that, while IL-17A appears to confer both maladaptive and protective responses, neutrophils play an entirely maladaptive role in VED. Given that lipoproteins are found in virtually all bacteria, the potential for lipoprotein-mediated maladaptive inflammatory responses should be taken into consideration when developing vaccines against bacterial pathogens.

Features of Parapneumonic Effusions

Introduction: Parapneumonic effusions, as a complication of community-acquired pneumonia (CAP), usually have a good course, but they sometimes progress into complicated parapneumonic effusion (CPPE) and empyema, thus becoming a significant clinical problem.

Aim: To review clinical and radiological features, as well as diagnostic and therapeutic options in parapneumonic effusions.

Material and methods: The analysis included 94 patients with parapneumonic effusion hospitalized at the University Infectious Diseases Clinic in Skopje during a 4 year period. Out of 755 patients with CAP, 175 (23.18%), had parapneumonic effusion. Thoracentesis was performed in 94 (53.71%) patients, 50 patients were with uncomplicated parapneumonic effusions (UCPPE) and 44 with complicated parapneumonic effusions (CPPE).

Results: More patients (59.57%) were male; the average age was 53.82±17.5 years. The most common symptoms included: fever (91; 96.81%), cough (80; 85.11%), pleuritic chest pain (68; 72.34%), dyspnea (65; 69.15%). Alcoholism was the most common comorbidity registered in 12 (12.77%) patients. Macroscopically, effusion was yellow and clear in most cases (36; 38.29%). Localization of pleural effusion was often in the left costophrenic angle (53; 56.38%) and ultrasonographic non-septated complex. Between the two groups of effusions there was a significant difference between the ERS, WBC and CRP in serum and CRP in pleural fluid. Statistical difference existed in terms of days of hospitalization with a longer hospital stay for patients with CPPE (p <0.0001).

Conclusion: Patients with parapneumonic effusion have the symptoms of acute respiratory infection and frequent accompanying diseases. Future diagnostic and therapeutic treatment depends on pleural fluid features and imaging lung findings.

Diagnosis of infectious pleural effusion using predictive models based on pleural fluid biomarkers

INTRODUCTION:

Diagnosis of pleural infection (PI) may be challenging. The purpose of this paper is to develop and validate a clinical prediction model for the diagnosis of PI based on pleural fluid (PF) biomarkers.

METHODS:

A prospective study was conducted on pleural effusion. Logistic regression was used to estimate the likelihood of having PI. Two models were built using PF biomarkers. The power of discrimination (area under the curve) and calibration of the two models were evaluated.

RESULTS:

The sample was composed of 706 pleural effusion (248 malignant; 28 tuberculous; 177 infectious; 48 miscellaneous exudates; and 212 transudates). Areas under the curve for Model 1 (leukocytes, percentage of neutrophils, and C-reactive protein) and Model 2 (the same markers plus interleukin-6 [IL-6]) were 0.896 and 0.909, respectively (not significant differences). However, both models showed higher capacity of discrimination than their biomarkers when used separately (P < 0.001 for all). Rates of correct classification for Models 1 and 2 were 88.2% (623/706: 160/177 [90.4%] with infectious pleural effusion [IPE] and 463/529 [87.5%] with non-IPE) and 89.2% (630/706: 153/177 [86.4%] of IPE and 477/529 [90.2%] of non-IPE), respectively.

CONCLUSIONS:

The two predictive models developed for IPE showed a good diagnostic performance, superior to that of any of the markers when used separately. Although IL-6 contributes a slight greater capacity of discrimination to the model that includes it, its routine determination does not seem justified.

Diagnostic value of proinflammatory interleukins in parapneumonic effusions

Pleural effusion appears in approximately 40% of patients with pneumonia. Given that microbiology results are often negative, its diagnosis is frequently based on clinical criteria. Our study consisted of 266 patients, divided into infectious (n = 34), tuberculous (n = 54), paraneoplastic (n = 63), miscellaneous exudates (n = 53), and transudates (n = 62). Interleukin (IL)-6, IL-8, and IL-1beta were measured in the pleural fluid and serum of all patients, as well as the different cell populations in the pleural fluid. Analysis of the receiver operating characteristic curves of the different ILs in pleural fluid for the diagnosis of parapneumonic/empyematous effusion showed IL-6 with a sensitivity of 38.2% and specificity of 97.4%, IL-8 with a sensitivity of 73.5% and specificity of 65.1%, IL-1beta with a sensitivity of 55.6% and specificity of 91.3%, and total neutrophil count in pleural fluid (PNEU) with a sensitivity of 62.9% and specificity of 91.1%. The combination of IL-1beta and PNEU improved the yield, with a sensitivity of 75.7% and a specificity of 83.1%.