A novel biomarker for pleural effusion diagnosis: Interleukin-36γ in pleural fluid

Infective Pleural Effusions-A Comprehensive Narrative Review Article

Infective pleural effusions are mainly represented by parapneumonic effusions and empyema. These conditions are a spectrum of pleural diseases that are commonly encountered and carry significant mortality and morbidity rates reaching upwards of 50%. The causative etiology is usually an underlying bacterial pneumonia with the subsequent seeding of the infectious culprit and inflammatory agents to the pleural space leading to an inflammatory response and fibrin deposition. Radiographical evaluation through a CT scan or ultrasound yields high specificity and sensitivity, with features such as septations or pleural thickening indicating worse outcomes. Although microbiological yields from pleural studies are around 56% only, fluid analysis assists in both diagnosis and prognosis by evaluating pH, glucose, and other biomarkers such as lactate dehydrogenase. Management centers around antibiotic therapy for 2-6 weeks and the drainage of the infected pleural space when the effusion is complicated through tube thoracostomies or surgical intervention. Intrapleural enzymatic therapy, used to increase drainage, significantly decreases treatment failure rates, length of hospital stay, and surgical referrals but carries a risk of pleural hemorrhage. This comprehensive review article aims to define and delineate the progression of parapneumonic effusions and empyema as well as discuss pathophysiology, diagnostic, and treatment modalities with aims of broadening the generalist's understanding of such complex disease by reviewing the most recent and relevant high-quality evidence.

Thoracic empyema: aetiology, diagnosis, treatment, and prevention

PURPOSE OF REVIEW

The aim of this study was to review current key points in the aetiology, diagnosis, treatment, and prevention of empyema thoracis. Early postpandemic trends have seen an increasing global incidence and evolution in the aetiology of empyema. Due to varied aetiology and typically lengthy treatment, empyema will be disproportionately affected by the rising tide of antimicrobial resistance (AMR), thus warranting attention and further research.

RECENT FINDINGS

Multiple novel biomarkers (e.g. IL-36γ) are under investigation to aid diagnosis, while oral health assessment tools are now available for prognosticating and risk-stratifying patients with thoracic empyema. There exists an ongoing lack of evidence-based guidance surrounding antibiotic treatment duration, surgical intervention indication, and prognostic scoring utility.

SUMMARY

Understanding aetiologies in different global regions and settings is pivotal for guiding empirical treatment. Antimicrobial resistance will make thoracic empyema increasingly challenging to treat and should prompt increased awareness of prescribing practices. Novel biomarkers are under investigation which may speed up differentiation of pleural effusion types, allowing faster cohorting of patients.Although newly identified predictors of morbidity and mortality have been suggested to be beneficial for incorporation into clinical practice, further work is required to prognosticate, risk-stratify, and standardize treatment.

The diagnostic value of interleukin-36 cytokines in pleural effusions of varying etiologies

BACKGROUND

The clinical management of pleural effusion (PE) poses challenges due to its diverse etiologies. The objective of this research was to investigate the concentrations of interleukin-36 (IL-36) cytokines in pleural fluid (PF) from different etiologies and assess their diagnostic efficacy in distinguishing the causes of PE.

METHODS

This study enrolled 89 patients with confirmed PE, comprising 11 cases classified as transudate, 24 cases as malignant pleural effusion (MPE), 24 cases as tuberculous pleural effusion (TPE), and 30 cases as parapneumonic pleural effusion (PPE). The PPE group was further subdivided into 20 cases of uncomplicated parapneumonic effusion (UPPE) and 10 cases of complicated parapneumonic effusion (CPPE)/empyema. The concentrations of IL-36 cytokines in the PF of all 89 patients were quantified by the enzyme-linked immunosorbent assay (ELISA).

RESULTS

IL-36α exhibited excellent diagnostic accuracy in TPE, achieving a sensitivity of 91.7 % and specificity of 83.1 %, along with a cut-off value of 435.3 pg/ml. IL-36Ra also demonstrated relatively favorable diagnostic performance in PPE, with a sensitivity of 80.0 % and specificity of 76.3 %, along with a cut-off value of 390.8 pg/ml. Multivariable logistic regression models were successfully developed for both TPE and PPE, confirming their diagnostic utility. Furthermore, the levels of IL-36Ra were notably elevated in CPPE/empyema in comparison to UPPE. Moreover, in PF, IL-36γ exhibited positive associations with both IL-36α and IL-36Ra.

CONCLUSION

IL-36α and IL-36Ra may serve as novel biomarkers for diagnosing TPE and PPE, respectively. The multivariate models established significantly enhance the diagnostic efficacy of both TPE and PPE. Furthermore, IL-36Ra can function as an indicator for assessing the extent of pleural inflammation. Additionally, the interaction among IL-36 cytokines in PF may contribute to their expression modulation.