Analysis of Cytokine Levers in Pleural Effusions of Tuberculous Pleurisy and Tuberculous Empyema

Diagnostic accuracy of interleukin-6 in multiple diseases: An umbrella review of meta-analyses

Objective

This review aims to conduct a comprehensive study of the diagnostic accuracy of interleukin-6 (IL-6) for multiple diseases by utilizing existing systematic reviews and meta-analyses.

Methods

We performed a thorough search of Embase, Web of Science, PubMed, and Cochrane Database of Systematic Reviews up to April 2023 to gather meta-analyses that investigate the diagnostic accuracy of IL-6. To assess the methodological quality of the studies, we employed the Assessing the Methodological Quality of Systematic Reviews-2 and Grading of Recommendations, Assessment, Development and Evaluation criteria.

Results

We included 34 meta-analyses out of the 3024 articles retrieved from the search. These meta-analyses covered 9 categories of diseases of the International Classification of Diseases-11. Studies rated as "Critically Low" or "Very Low" in the quality assessment process were excluded, resulting in a total of 6 meta-analyses that encompassed sepsis, colorectal cancer, tuberculous pleural effusion (TPE), endometriosis, among others. Among these diseases, IL-6 demonstrated a relatively high diagnostic potential in accurately identifying TPE and endometriosis.

Conclusions

IL-6 exhibited favorable diagnostic accuracy across multiple diseases, suggesting its potential as a reliable diagnostic biomarker in the near future. Substantial evidence supported its high diagnostic accuracy, particularly in the cases of TPE and endometriosis.

Interleukin-6 and -27 as potential novel biomarkers for human pleural tuberculosis regardless of the immunological status

Tuberculosis (TB) is the leading cause of pleural exudative effusions. Inflammatory markers, such as IFNγ and ADA, have been used as proxies for its diagnosis. We evaluated ex vivo levels of several cytokines in 83 pleural effusion specimens from patients with TB (including 10 with HIV co-infection) and 26 patients with other pleuritis using multiplex and ELISA assays. IL-6 and IL-27 levels were higher (p ≤ 0.04) in TB patients, regardless of the HIV status and the approach. IL-2, IL-4, IL-8, IFNγ, TNF and G-CSF showed variable results depending on the assay. This warranty these markers to be further validated.

Potential diagnostic value of pleural fluid cytokines levels for tuberculous pleural effusion

Patients with tuberculous pleural effusion (TPE) or malignant pleural effusions (MPE) frequently have similar pleural fluid profiles. New biomarkers for the differential diagnosis of TPE are required. We determined whether cytokine profiles in the PE of patients could aid the differential diagnosis of TPE. 30 patients with TPE, 30 patients with MPE, 14 patients with empyema (EMP) and 14 patients with parapneumonic effusion (PPE) were enrolled between Dec 2018 and 2019. The levels of interleukin (IL)-6, IL-18, IL-27, CXCL8, CCL-1 and IP-10 were determined in PE by ELISA along with measurements of adenosine deaminase (ADA). The best predictors of TPE were combined ADA.IL-27 [optimal cut-off value = 42.68 (10³ U ng/l²), sensitivity 100%, specificity 98.28%], ADA [cut off value 27.5 (IU/l), sensitivity 90%, specificity 96.5%] and IL-27 [cut-off value = 2363 (pg/ml), sensitivity 96.7%, specificity 98.3%, p ≤ 0.0001]. A high level of IL-6 [cut-off value = 3260 (pg/ml), sensitivity 100%, specificity 67.2%], CXCL8 [cut-off value = 144.5 (pg/ml), sensitivity 93.3%, specificity 58.6%], CCL1 [cut-off value = 54 (pg/ml), sensitivity 100%, specificity 70.7%] and IP-10 [cut-off value = 891.9 (pg/ml), sensitivity 83.3%, specificity 48.3%] were also predictive of TPE. High ADA.IL-27, ADA and IL-27 levels differentiate between TPE and non-TPE with improved specificity and diagnostic accuracy and may be useful clinically.

The Role of gp130 Cytokines in Tuberculosis

Protective immune responses to Mycobacterium tuberculosis (Mtb) infection substantially depend on a delicate balance within cytokine networks. Thus, immunosuppressive therapy by cytokine blockers, as successfully used in the management of various chronic inflammatory diseases, is often connected with an increased risk for tuberculosis (TB) reactivation. Hence, identification of alternative therapeutics which allow the treatment of inflammatory diseases without compromising anti-mycobacterial immunity remains an important issue. On the other hand, in the context of novel therapeutic approaches for the management of TB, host-directed adjunct therapies, which combine administration of antibiotics with immunomodulatory drugs, play an increasingly important role, particularly to reduce the duration of treatment. In both respects, cytokines/cytokine receptors related to the common receptor subunit gp130 may serve as promising target candidates. Within the gp130 cytokine family, interleukin (IL)-6, IL-11 and IL-27 are most explored in the context of TB. This review summarizes the differential roles of these cytokines in protection and immunopathology during Mtb infection and discusses potential therapeutic implementations with respect to the aforementioned approaches.

Diagnostic Value of Soluble Form of Mer Tyrosine Kinase (sMerTK) in Tuberculous Pleural Effusion and Malignant Pleural Effusion

Objectives. With the development of proteomics, it has been indicated that differentially expressed proteins are biological markers for the diagnosis of different types of pleural effusion (PE). The aim of our study was to explore the value of sMerTK (soluble form of Mer tyrosine kinase) in the differential diagnosis of tuberculous pleural effusion (TPE) and malignant pleural effusion (MPE). In addition, we also wanted to explore whether MerTK was associated with IL-1β and TNF-α, which are inflammatory factors related to pleural effusion. Methods. We screened all patients who underwent thoracoscopy and had a definite diagnosis. In total, 136 patients were enrolled in this study and classified into two groups, with 64 patients in the TPE group and 72 patients in the MPE group. The concentrations of sMerTK in the TPE and MPE groups were detected by ELISA. The diagnostic accuracy was determined by generating receiver operating characteristic (ROC) curves and calculating the area under the curve (AUC). Correlations between the expression level of sMerTK and those of the inflammatory factors interleukin 1 beta (IL-1β) and tumor necrosis factor alpha (TNF-α) were also studied using Pearson’s linear correlation analysis. Results. The concentrations of sMerTK were $\mathrm{5,278.77}\pm \mathrm{2,479.98}\text{ng}/\text{L}$ and $859.91\pm 540.45\text{ng}/\text{L}$ in the TPE and MPE groups, respectively. The concentration of sMerTK in TPE was shown to be significantly higher than that in MPE ( $P<0.05$ ). The area under the ROC curve for sMerTK in distinguishing TPE from MPE was 0.958, with a cutoff value of 2,122 ng/L. The sensitivity and specificity for sMerTK were 98.61% and 90.63% ( $P<0.05$ ). The expression levels of sMerTK in these two groups were not correlated with those of the inflammatory factors IL-1β and TNF-α ( $P>0.05$ ). Conclusions. The expression level of sMerTK in PE could be a potential biomarker for common use in the diagnosis of TPE and MPE.

Risk factors for tuberculous empyema in pleural tuberculosis patients

Tuberculous empyema (TE) is associated with high mortality and morbidity. In the retrospective cohort study, we aimed to find risk factors for TE among pleural tuberculosis (TB) patients. Between July 2011 and September 2015, all culture-confirmed pleural TB patients (474 cases) were enrolled in our study. Empyema was defined as grossly purulent pleural fluid. Demographic and epidemiological data were collected for further analysis. Multivariate logistic regression analysis was used to evaluate risk factors of TE in pleural TB, age–adjusted odds ratio (OR) and 95% confidence interval (CI) were calculated to show the risk. The mean age was 35.7 ± 18.1 years old, males comprised 79.1% of the participants (375 cases). Forty-seven patients (9.9%) were multidrug-resistant TB (MDR-TB), 29 (6.1%) had retreatment TB, 26 (5.5%) had diabetes mellitus. The percentage of empyema patients was 8.9% (42 cases). Multivariate analysis revealed that male (adjusted OR = 4.431, 95% CI: 1.411, 13.919), pleural adenosine deaminase (ADA, >88 U/L) (adjusted OR = 3.367, 95% CI: 1.533, 7.395) and white blood cell (WBC, >9.52 10⁹/L) (adjusted OR = 5.763, 95% CI: 2.473, 13.431) were significant risk factors for empyema in pleural TB, while pulmonary TB (adjusted OR = 0.155, 95% CI: 0.072, 0.336) was the protective factor for the patients. TE remains a serious threat to public health in China. Male sex is a significant risk factor for TE while the presence of pulmonary TB is protective, and high levels of pleural ADA and WBC count could aid in early diagnosis of TE. This finding would help towards reducing the mortality and morbidity associated with TE.

Formation of Foamy Macrophages by Tuberculous Pleural Effusions Is Triggered by the Interleukin-10/Signal Transducer and Activator of Transcription 3 Axis through ACAT Upregulation

The ability of Mycobacterium tuberculosis (Mtb) to persist in its human host relies on numerous immune evasion strategies, such as the deregulation of the lipid metabolism leading to the formation of foamy macrophages (FM). Yet, the specific host factors leading to the foamy phenotype of Mtb-infected macrophages remain unknown. Herein, we aimed to address whether host cytokines contribute to FM formation in the context of Mtb infection. Our approach is based on the use of an acellular fraction of tuberculous pleural effusions (TB-PE) as a physiological source of local factors released during Mtb infection. We found that TB-PE induced FM differentiation as observed by the increase in lipid bodies, intracellular cholesterol, and expression of the scavenger receptor CD36, as well as the enzyme acyl CoA:cholesterol acyl transferase (ACAT). Importantly, interleukin-10 (IL-10) depletion from TB-PE prevented the augmentation of all these parameters. Moreover, we observed a positive correlation between the levels of IL-10 and the number of lipid-laden CD14⁺ cells among the pleural cells in TB patients, demonstrating that FM differentiation occurs within the pleural environment. Downstream of IL-10 signaling, we noticed that the transcription factor signal transducer and activator of transcription 3 was activated by TB-PE, and its chemical inhibition prevented the accumulation of lipid bodies and ACAT expression in macrophages. In terms of the host immune response, TB-PE-treated macrophages displayed immunosuppressive properties and bore higher bacillary loads. Finally, we confirmed our results using bone marrow-derived macrophage from IL-10^-/- mice demonstrating that IL-10 deficiency partially prevented foamy phenotype induction after Mtb lipids exposure. In conclusion, our results evidence a role of IL-10 in promoting the differentiation of FM in the context of Mtb infection, contributing to our understanding of how alterations of the host metabolic factors may favor pathogen persistence.

Comparison of laboratory testing methods for the diagnosis of tuberculous pleurisy in China

To evaluate the diagnostic utilities of different methods for Mycobacterium tuberculosis (M. tuberculosis) detection in pleural fluid that represent potentially cost-effective measures for resource-limited settings in China. We compared diagnostic characteristics of the AmpSure simultaneous amplification and testing method, the BACTEC MGIT 960 system, and acid-fast bacilli staining of specimen smears for detection of M. tuberculosis in pleural fluids of 438 patients with suspected tuberculous pleurisy. Chest radiographs, computed tomography scans and the results of sputum and pleural biopsy testing were used for confirmations of tuberculosis diagnoses. The sensitivity of the AmpSure test (21.2%) was significantly higher than that of smear analysis (3.1%; p < 0.001), but was similar to that of the BACTEC culture method (17.8%; p > 0.05). The specificity of the AmpSure, BACTEC, and smear tests were 100%, 96.4%, and 100%, respectively. The positive and negative predictive values of the AmpSure, BACTEC, and smear tests were 100%/23.1%; 78.6%/19.8%; and 100%/22.4%, respectively. The sensitivity of ADA, IFNγ and histopathological analyses of pleural biopsies were all 100%. The sensitivities of all three methods were suboptimal for the detection of M. tuberculosis in pleural fluid. Future studies of a composite diagnostic index consisting of a combination of these tests are warranted.