Diagnostic Performance of Different Pleural Fluid Biomarkers in Tuberculous Pleurisy

Diagnostic value of soluble biomarkers for parapneumonic pleural effusion

Parapneumonic pleural effusion (PPE) is a common complication in patients with pneumonia. Timely and accurate diagnosis of PPE is of great value for its management. Measurement of biomarkers in circulating and pleural fluid have the advantages of easy accessibility, short turn-around time, objectiveness and low cost and thus have utility for PPE diagnosis and stratification. To date, many biomarkers have been reported to be of value for the management of PPE. Here, we review the values of pleural fluid and circulating biomarkers for the diagnosis and stratification PPE. The biomarkers discussed are C-reactive protein, procalcitonin, presepsin, soluble triggering receptor expressed on myeloid cells 1, lipopolysaccharide-binding protein, inflammatory markers, serum amyloid A, soluble urokinase plasminogen activator receptor, matrix metalloproteinases, pentraxin-3 and cell-free DNA. We found that none of the available biomarkers has adequate performance for diagnosing and stratifying PPE. Therefore, further work is needed to identify and validate novel biomarkers, and their combinations, for the management of PPE.

A scoring model for diagnosis of tuberculous pleural effusion

Background

Due to the low efficiency of a single clinical feature or laboratory variable in the diagnosis of tuberculous pleural effusion (TBPE), the diagnosis of TBPE is still challenging. This study aimed to build a scoring diagnostic model based on laboratory variables and clinical features to differentiate TBPE from non-tuberculous pleural effusion (non-TBPE).

Methods

A retrospective study of 125 patients (63 with TBPE; 62 with non-TBPE) was undertaken. Univariate analysis was used to select the laboratory and clinical variables relevant to the model composition. The statistically different variables were selected to undergo binary logistic regression. Variables B coefficients were used to define a numerical score to calculate a scoring model. A receiver operating characteristic (ROC) curve was used to calculate the best cut-off value and evaluate the performance of the model. Finally, we add a validation cohort to verify the model.

Results

Six variables were selected in the scoring model: Age ≤ 46 years old (4.96 points), Male (2.44 points), No cancer (3.19 points), Positive T-cell Spot (T-SPOT) results (4.69 points), Adenosine Deaminase (ADA) ≥ 24.5U/L (2.48 point), C-reactive Protein (CRP) ≥ 52.8 mg/L (1.84 points). With a cut-off value of a total score of 11.038 points, the scoring model’s sensitivity, specificity, and accuracy were 93.7%, 96.8%, and 99.2%, respectively. And the validation cohort confirms the model with the sensitivity, specificity, and accuracy of 92.9%, 93.3%, and 93.1%, respectively.

Conclusion

The scoring model can be used in differentiating TBPE from non-TBPE.

Pleural Fluid Soluble Interleukin-2 Receptor as a Biomarker for the Diagnosis of Tuberculosis Pleural Effusion: A Systematic Review and Meta-Analysis

Background

Several studies have assessed the diagnostic accuracy of pleural fluid soluble interleukin-2 receptor (sIL-2R) for tuberculous pleural effusion (TPE) but with varied results. Therefore, we conducted this systematic review and meta-analysis to evaluate the accuracy of sIL-2R for TPE.

Methods

PubMed, Ovid, and Web of Science databases were searched from inception to 23 March 2021 to identify eligible studies concerning the diagnostic accuracy of fluid sIL-2R for TPE. The sensitivity and specificity of sIL-2R for TPE were pooled with a bivariate model. We estimated the global diagnostic accuracy of PE sIL-2R with a summary receiver operating characteristic (sROC) curve. The revised Quality Assessment for Diagnostic Accuracy Studies tool (QUADAS-2) was used to assess the quality of eligible studies.

Results

A total of nine studies with 270 TPEs and 586 non-TPEs were included in the final analysis. The pooled sensitivity and specificity were 0.81 (95% CI: 0.76–0.86) and 0.92 (95% CI: 0.77–0.98), respectively. The area under the sROC curve (AUC) was 0.82 (95% CI: 0.79–0.86). No significant publication bias was observed.

Conclusions

Pleural fluid sIL-2R is a useful diagnostic marker for TPE. However, the diagnostic accuracies of already available biomarkers such as pleural fluid adenosine deaminase, interferon-γ, and interleukin-27 appear to be superior relative to sIL-2R. Therefore, it might not be preferable to use sIL-2R for diagnosing TPE.

Associations between lung-deposited dose of particulate matter and culture-positive pulmonary tuberculosis pleurisy

Epidemiological studies identified the relationship between air pollution and pulmonary tuberculosis. Effects of lung-deposited dose of particulate matter (PM) on culture-positive pulmonary tuberculosis remain unclear. This study investigates the association between lung-deposited dose of PM and pulmonary tuberculosis pleurisy. A case-control study of subjects undergoing pleural effusion drainage of pulmonary tuberculosis (case) and chronic heart failure (control) was conducted. Metals and biomarkers were quantified in the pleural effusion. The air pollution exposure was measured and PM deposition in the head, tracheobronchial, alveolar region, and total lung region was estimated by Multiple-path Particle Dosimetry (MPPD) Model. We performed multiple logistic regression to examine the associations of these factors with the risk of tuberculosis. We observed that 1-μg/m³ increase in PM₁₀ was associated with 1.226-fold increased crude odds ratio (OR) of tuberculosis (95% confidence interval (CI): 1.023-1.469, p<0.05), 1-μg/m³ increase in PM_2.5-10 was associated with 1.482-fold increased crude OR of tuberculosis (95% CI: 1.048-2.097, p < 0.05), 1-ppb increase in NO₂ was associated with 1.218-fold increased crude OR of tuberculosis (95% CI: 1.025-1.447, p < 0.05), and 1-ppb increase in O₃ was associated with 0.735-fold decreased crude OR of tuberculosis (95% CI: 0.542 0.995). We observed 1-μg/m³ increase in PM deposition in head and nasal region was associated with 1.699-fold increased crude OR of tuberculosis (95% CI: 1.065-2.711, p < 0.05), 1-μg/m³ increase in PM deposition in tracheobronchial region was associated with 1.592-fold increased crude OR of tuberculosis (95% CI: 1.095-2.313, p < 0.05), 1-μg/m³ increase in PM deposition in alveolar region was associated with 3.981-fold increased crude OR of tuberculosis (95% CI: 1.280-12.386, p < 0.05), and 1-μg/m³ increase in PM deposition in total lung was associated with 1.511-fold increased crude OR of tuberculosis (95% CI: 1.050-2.173, p < 0.05). The results indicate that particle deposition in alveolar region could cause higher risk of pulmonary tuberculosis pleurisy than deposition in other lung regions.

Comparative accuracy of pleural fluid unstimulated interferon-gamma and adenosine deaminase for diagnosing pleural tuberculosis: A systematic review and meta-analysis

Objective

We compared diagnostic accuracy of pleural fluid adenosine deaminase (ADA) and interferon-gamma (IFN-γ) in diagnosing tuberculous pleural effusion (TPE) through systematic review and comparative meta-analysis.

Methods

We queried PubMed and Embase databases to identify studies providing paired data for sensitivity and specificity of both pleural fluid ADA and IFN-γ for diagnosing TPE. We used hierarchical summary receiver operating characteristic (HSROC) plots and HSROC meta-regression to model individual and comparative diagnostic performance of the two tests.

Results

We retrieved 376 citations and included 45 datasets from 44 publications (4974 patients) in our review. Summary estimates for sensitivity and specificity for ADA were 0.88 (95% CI 0.85–0.91) and 0.91 (95% CI 0.89–0.92), while for IFN-γ they were 0.91 (95% CI 0.89–0.94) and 0.96 (95% CI 0.94–0.97), respectively. HSROC plots showed consistently greater diagnostic accuracy for IFN-γ over ADA across the entire range of observations. HSROC meta-regression using test-type as covariate yielded a relative diagnostic odds ratio of 2.22 (95% CI 1.68–2.94) in favour of IFN-γ, along with better summary sensitivity and specificity figures. No prespecified subgroup variable significantly influenced the summary diagnostic accuracy estimates.

Conclusion

Pleural fluid IFN-γ estimation has better diagnostic accuracy than ADA estimation for diagnosis of TPE.

Biomarkers of Distinguishing Neutrophil-Predominant Tuberculous Pleural Effusion from Parapneumonic Pleural Effusion

BACKGROUND

Tuberculous pleural effusion (TPE) is usually characterized by lymphocytic predominance and high pleural fluid adenosine deaminase (pfADA), while parapneumonic pleural effusion (PPE) is usually characterized by neutrophilic predominance. However, in some cases, neutrophils can be predominant in TPE. In such cases, the differential diagnosis between TPE and PPE is challenging and has been rarely investigated. The aim of this study was to evaluate the accuracy of pfADA, pleural fluid lactate dehydrogenase (pfLDH) and other parameters, such as age/pfADA in the differential diagnosis of neutrophil-predominant TPE (NP-TPE) and PPE.

METHODS

Between January 2003 and August 2018, 19 patients with NP-TPE and 54 patients with PPE at Shanghai Jiao Tong University Affiliated Sixth People's Hospital were retrospectively reviewed. Age, blood and pleural fluid findings, and eight ratios that consisted of routine biomarkers were compared between the two groups in ≤50 and >50 years old groups. ROC curve analysis was used to evaluate diagnostic performance.

RESULTS

The three parameters with the largest AUC were age/pfADA, pfADA and pfLDH in ≤ 50 years old group, and pfADA, age/pfADA and the percentage of neutrophils in pleural fluid (pfN%) in >50 years old group. For patients ≤ 50 years old, pfADA combined with pfLDH or age/pfADA combined with pfLDH could increase the specificity to 100%, while the sensitivity of the former was high (84.6% vs 76.9%). For patients >50 years old, both pfADA combined with pfN% and age/pfADA combined with pfN% could increase the specificity to 90.3% with the same sensitivity.

CONCLUSIONS

Although pfADA played an important role in the discrimination of NP-TPE from PPE, combining pfADA with pfLDH for patients ≤50 years old or combining pfADA with pfN% for patients >50 years old might improve diagnostic performance.

Pleural fluid tumor necrosis factor for diagnosis of pleural tuberculosis: A systematic review and meta-analysis

OBJECTIVE

Tumor necrosis factor (TNF) is an important local host response mediator in tuberculous pleural effusion (TPE) and is proposed as a potential biomarker for diagnosing TPE. We assessed the performance of pleural fluid TNF in the diagnosis of TPE, and evaluated its ability to distinguish TPE from parapneumonic or malignant effusions.

METHODS

We queried the PubMed and Embase databases for studies indexed till August 2020. We included studies that (a) provided data on sensitivity and specificity of pleural fluid TNF for the diagnosis of TPE, or (b) compared pleural fluid TNF levels between TPE and malignant or parapneumonic effusions. We used a hierarchical summary receiver operating characteristic plot to model summary sensitivity and specificity. A random effects model was used to pool standardized mean differences (SMD) across studies comparing TPE and other effusions. We explored heterogeneity using subgroup analysis. We also performed meta-regression to identify factors significantly influencing results.

RESULTS

We retrieved 1090 citations, and included 38 publications, in our review. The summary estimates for sensitivity, specificity, and diagnostic odds ratio were 0.79 (95% CI 0.72-0.84), 0.82 (95% CI 0.76-0.87), and 16.84 (95% CI 9.47-29.95) respectively. Pleural fluid TNF levels were significantly higher in TPE than in malignant effusions (summary SMD 1.50, 95% CI 1.13-1.87), but not parapneumonic effusions (summary SMD 0.61, 95% CI -0.14 to 1.35). None of the prespecified subgroup variables significantly influenced summary estimates.

CONCLUSION

Pleural fluid TNF has poor diagnostic accuracy for diagnosing TPE and imperfectly discriminates TPE from parapneumonic pleural effusions.

Role of cancer ratio and other new parameters in the differential diagnosis of malignant pleural effusion

OBJECTIVES

We compared the diagnostic potential of cancer ratio (CR, serum lactate dehydrogenase [LDH]/pleural fluid adenosine deaminase [pfADA]), cancer ratio plus (CR plus, cancer ratio/pleural lymphocyte percentage), and age/pfADA ratio with pfADA in malignant pleural effusion.

METHODS

Data from 100 patients with malignant pleural effusion (MPE) and 119 patients with tuberculous pleural effusion (TPE) were retrospectively collected. PfADA, age/pfADA ratio, CR, and CR plus were compared between patients with MPE and those with TPE in two age groups (≤50 and >50 years). The best cut-off value was determined, and the diagnostic performance was evaluated according to the receiver operating characteristic curve.

RESULTS

PfADA was statistically significantly lower while age/pfADA ratio, CR, and CR plus were significantly higher in the MPE group than in the TPE group in both age groups (p<0.05). For patients aged ≤50 years, the differential diagnostic value of pfADA for MPE was better than those of age/pfADA ratio, CR, and CR plus. At a cut-off value of 13.0 U/L, the sensitivity, specificity, and accuracy were 88.9%, 100.0%, and 98.9%, respectively. For patients aged >50 years, the diagnostic performance of CR plus was superior to those of pfADA, age/pfADA ratio, and CR. At a cut-off value of 22.6, the sensitivity, specificity, and accuracy of CR plus for the diagnosis of MPE were 86.8%, 84.6%, and 86.2%, respectively.

CONCLUSIONS

The best parameter for diagnosing MPE was different for patients aged ≤50 years and >50 years. For patients aged >50 years, CR plus was a good parameter for the differential diagnosis of MPE. For patients aged ≤50 years, pfADA was better.

Fatty acid oxidation of alternatively activated macrophages prevents foam cell formation, but Mycobacterium tuberculosis counteracts this process via HIF-1α activation

The ability of Mycobacterium tuberculosis (Mtb) to persist inside host cells relies on metabolic adaptation, like the accumulation of lipid bodies (LBs) in the so-called foamy macrophages (FM), which are favorable to Mtb. The activation state of macrophages is tightly associated to different metabolic pathways, such as lipid metabolism, but whether differentiation towards FM differs between the macrophage activation profiles remains unclear. Here, we aimed to elucidate whether distinct macrophage activation states exposed to a tuberculosis-associated microenvironment or directly infected with Mtb can form FM. We showed that the triggering of signal transducer and activator of transcription 6 (STAT6) in interleukin (IL)-4-activated human macrophages (M(IL-4)) prevents FM formation induced by pleural effusion from patients with tuberculosis. In these cells, LBs are disrupted by lipolysis, and the released fatty acids enter the β-oxidation (FAO) pathway fueling the generation of ATP in mitochondria. Accordingly, murine alveolar macrophages, which exhibit a predominant FAO metabolism, are less prone to become FM than bone marrow derived-macrophages. Interestingly, direct infection of M(IL-4) macrophages with Mtb results in the establishment of aerobic glycolytic pathway and FM formation, which could be prevented by FAO activation or inhibition of the hypoxia-inducible factor 1-alpha (HIF-1α)-induced glycolytic pathway. In conclusion, our results demonstrate that Mtb has a remarkable capacity to induce FM formation through the rewiring of metabolic pathways in human macrophages, including the STAT6-driven alternatively activated program. This study provides key insights into macrophage metabolism and pathogen subversion strategies.

Tuberculosis is a deadly disease caused by Mycobacterium tuberculosis. Although progress has been made in tuberculosis control, there are unexplored aspects of how the immune system deals with the pathogen that need to be addressed. M. tuberculosis primarily lives in macrophages, immune cells which can destroy mycobacteria. In spite of the multiple microbicidal properties, the bacterium still manipulates the metabolism of macrophages, reflected in the accumulation lipid droplets and consequent differentiation into foamy macrophages. These lipid-laden macrophages constitute a favorable niche for the bacteria to persist hidden from our immune defense. Macrophages are classified into different programs depending on how they are activated by environmental signals, ranging from classically (microbicidal/inflammatory) to alternatively (tissue remodeling/repair/growth) activated spectrum extremes. We found that, unlike other programs, alternatively activated macrophages are reluctant to accumulate lipid droplets due to the signal transducer and activator of transcription 6 (STAT6), which promotes the degradation of those lipids. Notwithstanding, M. tuberculosis counteracts lipolysis by rewiring the metabolism of alternatively activated macrophages towards the accumulation of lipid droplets via the activation of the hypoxia-inducible factor 1-alpha (HIF-1α). Therefore, this study contributes to the better understanding of how bacillus shifts the metabolism of macrophages, which can be crucial to therapeutic purposes.

The diagnostic utility of pleural markers for tuberculosis pleural effusion

Tuberculosis pleural effusion (TPE) is common in clinical practice, and its diagnosis remains a challenge for clinicians. Ziehl-Neelsen staining, PE Mycobacterium tuberculosis culture, and biopsy are the gold standards for TPE diagnosis; however, they are time-consuming, invasive, observer-dependent, and insensitive. PE markers represent a rapid, low-cost, and non-invasive objective diagnostic tool for TPE. In the past decades, several PE biomarkers have been developed, and their diagnostic accuracy has been evaluated in many studies. Here, we reviewed the literature to summarize the diagnostic accuracy of these biomarkers, especially using the evidence from systematic review and meta-analysis. The current research strongly suggests that adenosine deaminase (ADA), interferon-gamma (IFN-γ), and interleukin 27 (IL-27) have extremely higher diagnostic accuracy for TPE, while the diagnostic accuracy of interferon gamma release assays (IGRAs), tumor necrosis factor-α (TNF-α), and interferon-γ-induced protein 10 kDa (IP-10) is moderate. Although some evidence supports C-X-C motif chemokine ligand 9 (CXCL9), CXCL11, CXCL12, sFas ligand, angiotensin-converting enzyme (ACE), calpain-1, spectrin breakdown products (SBDP), matrix metalloproteinase-1 (MMP-1), soluble CD26 (sCD26), soluble interleukin 2 receptor (sIL-2R) as useful diagnostic markers for TPE, more support is needed to validate their diagnostic accuracy. Finally, nucleic acid amplification tests (NAATs) have extremely high diagnostic specificity, but their sensitivity is low. Taken together, ADA is the preferred marker for TPE because its low cost and suitability for standardization.

Identifying tuberculous pleural effusion using artificial intelligence machine learning algorithms

BACKGROUND

The differential diagnosis of tuberculous pleural effusion (TPE) is challenging. In recent years, artificial intelligence (AI) machine learning algorithms have started being used to an increasing extent in disease diagnosis due to the high level of efficiency, objectivity, and accuracy that they offer.

METHODS

Data samples on 192 patients with TPE, 54 patients with parapneumonic pleural effusion (PPE), and 197 patients with malignant pleural effusion (MPE) were retrospectively collected. Based on 28 different features obtained via statistical analysis, TPE diagnostic models using four machine learning algorithms (MLAs), namely logistic regression, k-nearest neighbors (KNN), support vector machine (SVM) and random forest (RF) were established and their respective diagnostic performances were calculated. The respective diagnostic performances of each of the four algorithmic models were compared with that of pleural fluid adenosine deaminase (pfADA). Based on 12 features with the most significant impacts on the accuracy of the RF model, a new RF model was designed for clinical application. To demonstrate its external validity, a prospective study was conducted and the diagnostic performance of the RF model was calculated.

RESULTS

The respective sensitivity and specificity of each of the four TPE diagnostic models were as follows: logistic regression - 80.5 and 84.8%; KNN- 78.6 and 86.6%; SVM - 83.2 and 85.9%; and RF - 89.1 and 93.6%. The sensitivity and specificity of pfADA were 85.4 and 84.1%, respectively, at the best cut-off value of 17.5 U/L. RF was the superior method among the four MLAs, and was also superior to pfADA. The newly designed RF model (based on 12 out of 28 features) exhibited an acceptable performance rate for the diagnosis of TPE with a sensitivity and specificity of 90.6 and 92.3%, respectively. In the prospective study, its sensitivity and specificity were 100.0 and 90.0%, respectively.

CONCLUSIONS

Establishing a model for the diagnosis of TPE using RF resulted in a more effective, economical, and faster diagnostic method. This method could enable clinicians to diagnose and treat TPE more effectively.

Impact of age on the diagnostic yield of four different biomarkers of tuberculous pleural effusion

The diagnostic value of pleural fluid biomarkers in tuberculous pleurisy (TP) is firmly established. However, it is less clear whether patients' age affects the diagnostic accuracy of TP biomarkers. The aim of the study was to assess the impact of age, on the predictive value of ADA, IFN-γ, IP-10 and Fas ligand in patients with pleural effusion. The study included 222 patients, median age 64.5 (54-77) years, 58.6% men, with pleural effusion: TPE (60 patients; 27.0%), malignant PE (90 patients; 40.5%), parapneumonic effusion/pleural empyema (35 patients; 15.8%), pleural transudate (30 patients, 13.5%) and other causes of PE (7 patients; 3.2%). The odds ratio for the diagnosis of TPE significantly decreased with increasing age (OR = 0.62/10 years) and significantly increased with increasing level of all evaluated pleural fluid biomarkers. Age affected the diagnostic accuracy of ADA with a trend towards reduction in OR for TPE in older patients (P = 0.077, 95% CI 0.59-1.03). Younger age and high pleural fluid ADA level are associated with very high probability of TP. This probability significantly decreases not only with decreasing pleural fluid ADA, but also with increasing age. Patient's age does not affect the diagnostic yield of pleural fluid IFN-γ, IP-10 and sFas.

Significance of congestive heart failure as a cause of pleural effusion: Pilot data from a large multidisciplinary teaching hospital

BACKGROUND

Epidemiological data on the causes of pleural effusion (PE) are scarce. Data on the local prevalence of various causes of PE may play a crucial role in the management strategy of patients with PE. The aim of the study was to investigate the causes of PE and to assess 30-day mortality rate in unselected adult patients treated in a large, multidisciplinary hospital.

METHODS

Retrospective analysis of medical records, including chest radiographs, of 2835 consecutive patients admitted to the hospital was performed. Radiograhic signs of PE were found in 195 of 1936 patients in whom chest radigraphs were available. These patients formed the study group.

RESULTS

The leading causes of PE were as follows: congestive heart failure (CHF; 37.4%), pneumonia (19.5%), malignancy (15.4%), liver cirrhosis (4.2%) and pulmonary embolism. The cause of PE in 6.7% patients was not established. There was a significant predominance of small volume PE as compared to a moderate or large volume PEs (153, 28 and 14 patients, respectively). Almost 80% of patients with CHF presented with small volume PE, while almost 50% of patients with malignant PE demonstrated moderate or large volume PE. Thirty-day mortality rate ranged from 0% for tuberculous pleurisy to 40% for malignant PE (MPE).

CONCLUSIONS

Pleural effusion was found in 10.1% of patients treated in a large multidisciplinary hospital. CHF was the leading cause of PE. Although 30-day mortality in patients with CHF was rela-tively high, it was lower than that in parapneumonic PE and MPE.

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.

Diagnostic value of interleukins for tuberculous pleural effusion: a systematic review and meta-analysis

BACKGROUND

The ability of interleukins (ILs) to differentiate tuberculous pleural effusion from other types of effusion is controversial. The aim of our study was to summarize the evidence for its use of ruling out or in tuberculous pleural effusion.

METHODS

Two investigators independently searched PubMed, EMBASE, Web of Knowledge, CNKI, WANFANG, and WEIPU databases to identify studies assessing diagnostic role of ILs for tuberculous pleural effusion published up to January, 2017. Study quality was assessed using Quality Assessment of Diagnostic Accuracy Studies-2. The pooled diagnostic sensitivity and specificity of ILs were calculated by using Review Manager 5.3. Area under the summary receiver operating characteristic curve (AUC) was used to summarize the overall diagnostic performance of individual markers.

RESULTS

Thirty-eight studies met our inclusion criteria. Pooled sensitivity, specificity and AUC for chosen ILs were as follows: IL-2, 0.67,0.76 and 0.86; IL-6, 0.86, 0.84 and 0.90; IL-12, 0.78, 0.83 and 0.86; IL-12p40, 0.82,0.65 and 0.76; IL-18, 0.87, 0.92 and 0.95; IL-27, 0.93, 0.95 and 0.95; and IL-33, 0.84, 0.80 and 0.88.

CONCLUSIONS

Some of these ILs may assist in diagnosing tuberculous pleural effusion, though no single IL is likely to show adequate sensitivity or specificity on its own. Further studies on a large scale with better study design should be performed to assess the diagnostic potential of ILs.

Pleural fluid tests to diagnose tuberculous pleuritis

PURPOSE OF REVIEW

This article summarizes current data regarding the accuracy of pleural fluid tests assisting the diagnosis of tuberculous pleuritis (TBP).

RECENT FINDINGS

No pleural fluid test reliably rules-in TBP in settings with low TBP prevalence. Interferon-γ) alone or in combination with adenosine deaminase (ADA) is more reliable than ADA for this purpose in nonlow prevalences. ADA can reliably rule-out TBP in prevalences of less than 40% although in higher prevalences the product of interleukin-27 and ADA is the most accurate rule-out test.

SUMMARY

The definite diagnosis of TBP requires the isolation of Mycobacterium tuberculosis from pleural fluid or biopsies. Because of the low sensitivity of pleural fluid cultures and the invasiveness of pleural biopsy techniques, the concept of a pleural fluid test that accurately establishes or excludes TBP diagnosis has been proposed. Numerous pleural fluid tests have been evaluated for this purpose with ADA being the most widely accepted one. During the last years, it has been demonstrated that the ability of ADA to rule-in or rule-out TBP is affected by the prevalence of TBP in the setting where the test is used. The complementary use of interferon-γ or interleukin-27 increases the ability of ADA to rule-in or rule-out the disease, respectively.

Advances in the diagnosis of tuberculous pleuritis

Pleural tuberculosis (TB) remains difficult to diagnose. In about two-thirds of the cases the diagnosis is reliant upon clinical suspicion along with consistent fluid biochemistries (i.e., lymphocytic predominant exudates) and exclusion of other potential causes for the effusion. Microbiological methods for a confirmatory diagnosis of pleural TB, which include acid-fast smears (Ziehl-Nelseen), cultures on solid media (Lowenstein-Jensen) and polymerase chain reaction tests from either pleural fluid or sputum samples, remain suboptimal since they are positive in only a minority of patients. Liquid media, however, significantly increase sensitivity while shortening culture positivity as compared with solid cultures. A number of pleural fluid biomarkers such as adenosine deaminase (ADA), interferon-Ƴ, interferon-Ƴ-induced protein of 10 KDa (IP-10) and interleukin-27 (IL-27), have shown promise for the rapid diagnosis of TB, but only ADA combines the accuracy and simplicity required to be considered a mainstay investigative tool for clinical decisions, particularly in areas with medium to high TB prevalence. In countries where ADA is not available, pleural biopsies to evaluate for caseating granulomas are a standard diagnostic approach. They are now frequently performed under ultrasound guidance to optimize yield and patient safety.

Analysis of Plasma Cytokine and Chemokine Profiles in Patients with and without Tuberculosis by Liquid Array-Based Multiplexed Immunoassays

The aim of this study was to establish plasma cytokine/chemokine profiles in patients with 3 different presentations of active tuberculosis (TB), compared to the profiles observed in bacillus Calmette-Guérin (BCG)-vaccinated healthy individuals and patients with other pulmonary diseases (non-TB patients). To this end, plasma samples were collected from 151 TB patients including 68 pulmonary TB (PTB), 43 endobronchial TB, and 40 tuberculosis pleurisy (TP) patients, as well as 107 no-TB cases including 26 non-TB patients and 81 BCG-vaccinated healthy controls. A liquid array-based multiplexed immunoassay was used to screen plasma samples for 20 distinct cytokines and chemokines. Multinomial logistic regression was used to analyze associations between cytokines/chemokines and TB/non-TB patients. Compared to our findings with the no-TB donors, the median plasma levels of the proinflammatory cytokines/chemokines TNF-α, IL-6, IP-10, IFN-γ, and MIP-1β were significantly elevated in TB patients, suggesting their potential use as biomarkers for diagnosing TB patients. Further comparisons with healthy donors showed that only the median TNF-α plasma level was highly produced in the plasma of all 3 types of TB patients. Plasma IL-6 production was higher only in TP patients, while the plasma levels of IP-10, IFN-γ, and MIP-1β were markedly enhanced in both PTB and TP patients. Unexpectedly, among the above cytokines/chemokines, MIP-1β was also highly expressed in non-TB patients, compared with healthy donors. Our results suggested that TNF-α may be an ideal biomarker for diagnosing the 3 forms of TB presentation, while the other factors (IL-6, IP-10, MCP-1, and IFN-γ) can potentially facilitate differential diagnosis for the 3 TB presentation types. Further characterization of immune responses associated with different types of TB diseases will provide a basis for developing novel TB diagnostics.

Development and Evaluation of the New Predictive Models in Tuberculous Pleuritis

Different pleural fluid biomarkers have been found useful in the discrimination between tuberculous pleural effusion (TPE) and non-TPE, with interferon gamma (IFN-γ) showing the highest single marker diagnostic accuracy. The aim of the present study was to develop predictive models based on clinical data and pleural fluid biomarkers, other than IFN-γ, which could be applied in differentiating TPE and non-TPE. Two hundred and forty two patients with newly diagnosed pleural effusion were prospectively enrolled. Upon completion of the diagnostic procedures, the underlying disease was identified in 203 patients (117 men and 86 women, median age 65 years; 44 patients with TPE and 159 with non-TPE) who formed the proper study group. Pleural fluid level of ADA, IFN-γ, IL-2, IL-2sRα, IL-12p40, IL-18, IL-23, IP-10, Fas-ligand, MDC, and TNF-α was measured and then ROC analysis and multivariate logistic regression were used to construct the predictive models. Two predictive models with very high diagnostic accuracy (AUC > 0.95) were developed. The first model included body temperature, white blood cell count, pleural fluid ADA and IP-10. The second model was based on age, sex, body temperature, white blood cell count, pleural fluid lymphocyte percentage, and IP-10 level. We conclude that two new predictive models based on clinical and laboratory data demonstrate very high diagnostic performance and can be potentially used in clinical practice to differentiate between TPE and non-TPE.