Expression Profiles of Cytokine mRNAs in the Pleural Fluid Reveal Differences Among Tuberculosis, Malignancies, and Pneumonia-Exudative Pleural Effusions

Reanalysis and validation of the transcriptional pleural fluid signature in pleural tuberculosis

Introduction

Pleural tuberculosis (PlTB), the most common site of extrapulmonary TB, is characterized by a paucibacillary nature and a compartmentalized inflammatory response in the pleural cavity, both of which make diagnosis and management extremely challenging. Although transcriptional signatures for pulmonary TB have already been described, data obtained by using this approach for extrapulmonary tuberculosis and, specifically, for pleural tuberculosis are scarce and heterogeneous. In the present study, a set of candidate genes previously described in pulmonary TB was evaluated to identify and validate a transcriptional signature in clinical samples from a Brazilian cohort of PlTB patients and those with other exudative causes of pleural effusion.

Methods

As a first step, target genes were selected by a random forest algorithm with recursive feature elimination (RFE) from public microarray datasets. Then, peripheral blood (PB) and pleural fluid (PF) samples from recruited patients presenting exudative pleural effusion were collected during the thoracentesis procedure. Transcriptional analysis of the selected top 10 genes was performed by quantitative RT-PCR (RT-qPCR).

Results

Reanalysis of the public datasets identified a set of candidate genes (CARD17, BHLHE40, FCGR1A, BATF2, STAT1, BTN3A1, ANKRD22, C1QB, GBP2, and SEPTIN4) that demonstrated a global accuracy of 89.5% in discriminating pulmonary TB cases from other respiratory diseases. Our validation cohort consisted of PlTB (n = 35) patients and non-TB (n = 34) ones. The gene expressions of CARD17, GBP2, and C1QB in PF at diagnosis were significantly different between the two (PlTB and non-TB) groups (p < 0.0001). It was observed that the gene expressions of CARD17 and GBP2 were higher in PlTB PF than in non-TB patients. C1QB showed the opposite behavior, being higher in the non-TB PF. After anti-TB therapy, however, GBP2 gene expression was significantly reduced in PlTB patients (p < 0.001). Finally, the accuracy of the three above-cited highlighted genes in the PF was analyzed, showing AUCs of 91%, 90%, and 85%, respectively. GBP2 was above 80% (sensitivity = 0.89/specificity = 0.81), and CARD17 showed significant specificity (Se = 0.69/Sp = 0.95) in its capacity to discriminate the groups.

Conclusion

CARD17, GBP2, and C1QB showed promise in discriminating PlTB from other causes of exudative pleural effusion by providing accurate diagnoses, thus accelerating the initiation of anti-TB therapy.

Maresin-1 and Its Receptors RORα/LGR6 as Potential Therapeutic Target for Respiratory Diseases

Maresin-1 is one of the representative specialized pro-resolving mediators that has shown beneficial effects in inflammatory disease models. Recently, two distinct types of receptor molecules were discovered as the targets of maresin-1, further revealing the pro-resolution mechanism of maresin-1. One is retinoic acid-related orphan receptor α (RORα) and the another one is leucine-rich repeat domain-containing G protein-coupled receptor 6 (LGR6). In this review, we summarized the detailed role of maresin-1 and its two different receptors in respiratory diseases. RORα and LGR6 are potential targets for the treatment of respiratory diseases. Future basic research and clinical trials on MaR1 and its receptors should provide useful information for the treatment of respiratory diseases.

The Inflammatory Cytokine Profile of Patients with Malignant Pleural Effusion Treated with Pleurodesis

Patients with malignant pleural effusion (MPE) who underwent successful pleurodesis survive longer than those for whom it fails. We hypothesize that the therapy-induced inflammatory responses inhibit the cancer progression, and thereby lead to a longer survival. Thirty-three consecutive patients with MPE that were eligible for bleomycin pleurodesis between September 2015 and December 2017 were recruited prospectively. Nineteen patients (57.6%) achieved fully or partially successful pleurodesis, while 14 patients either failed or survived less than 30 days after pleurodesis. Two patients without successful pleurodesis were excluded because of missing data. Interleukin (IL)-1 beta, IL-6, IL-10, transforming growth factor beta, tumor necrosis factor alpha (TNF-α), and vascular endothelial growth factor in the pleural fluid were measured before, and after 3 and 24 h of pleurodesis. Their pleurodesis outcome and survival were monitored and analyzed. Patients who underwent successful pleurodesis had a longer survival rate. Patients without successful pleurodesis had significantly higher TNF-α and IL-10 levels in their pleural fluid than in the successful patients before pleurodesis. Following pleurodesis, there was a significant increment of IL-10 in the first three hours in the successful patients. In contrast, significant increments of TNF-α and IL-10 were found in the unsuccessful patients between 3 and 24 h after pleurodesis. The ability to produce specific cytokines in the pleural space following pleurodesis may be decisive for the patient’s outcome and survival. Serial measurement of cytokines can help allocate the patients to adequate treatment strategies. Further study of the underlying mechanism may shed light on cytokine therapies as novel approaches.

Predominance of Th1 Immune Response in Pleural Effusion of Patients with Tuberculosis among Other Exudative Etiologies

Pleural tuberculosis (PlTB), a common form of extrapulmonary TB, remains a challenge in the diagnosis among many causes of pleural effusion. We recently reported that the combinatorial analysis of interferon gamma (IFN-γ), IFN-γ-inducible protein 10 (IP-10), and adenosine deaminase (ADA) from the pleural microenvironment was useful to distinguish pleural effusion caused by TB (microbiologically confirmed or not) among other etiologies. In this cross-sectional cohort study, a set of inflammatory mediators was quantified in blood and pleural fluid (PF) from exudative pleural effusion cases, including PlTB (n = 27) and non-PlTB (nTB) (n = 25) patients. The levels of interleukin-2 (IL-2), IL-4, IL-6, IL-10, IL-17A, IFN-γ, tumor necrosis factor (TNF), IP-10, transforming growth factor β1 (TGF-β), and ADA were determined using cytometric bead assay, enzyme-linked immunosorbent assay (ELISA), or biochemical tests. IFN-γ, IP-10, TNF, TGF-β, and ADA quantified in PF showed significantly higher concentrations in PlTB patients than in nTB patients. When blood and PF were compared, significantly higher concentrations of IL-6 and IL-10 in PF were identified in both groups. TGF-β, solely, showed significantly increased levels in PF and blood from PlTB patients when both clinical specimens were compared to those from nTB patients. Principal-component analysis (PCA) revealed a T helper type 1 (Th1) pattern attributed mainly to higher levels of IP-10, IFN-γ, TGF-β, and TNF in the pleural cavity, which was distinct between PlTB and nTB. In conclusion, our findings showed a predominantly cellular immune response in PF from TB cases, rather than other causes of exudative effusion commonly considered in the differential diagnosis of PlTB.

A subset of CD1c+ dendritic cells is increased in patients with tuberculosis and promotes Th17 cell polarization

The role of primary subsets of DCs in Mycobacterium tuberculosis infection in humans is incompletely understood. In this study, we identified a CD1c DC subset with phenotype of CD1c⁺CD11c⁺CD19^-CD11b⁺ that was significantly increased in tuberculous pleural effusions and in peripheral blood from patients with TB compared with that from healthy controls (p < 0.0001). Sputum smear/culture-positive patients with tuberculosis had significantly higher frequency of CD1c⁺CD11b⁺ DC subset than sputum smear/culture-negative patients (p < 0.0001). After effective anti-TB chemotherapy, the frequency of CD1c⁺CD11b⁺ DC subset in peripheral blood and tuberculous pleural effusions was decreased. CD1c⁺CD11b⁺ DC subset from tuberculous pleural effusions expressed higher levels of TLR2, TLR4, CD172a, CD206 and FcεRⅠ, but lower levels of CD80, CD83 and CD86 compared with CD1c⁺CD11b^- DC subset. Expression of IL-1β, IL-6, IL-8, IL-23, TNF-α, IFN-γ and TGF-β mRNA in CD1c⁺CD11b⁺ DCs was higher than in CD1c⁺CD11b^- DC subset. Co-culture of autologous naive CD4⁺ T cells with sorted CD1c⁺CD11b⁺ DCs expressed significantly increased levels of IL-17A and RORγt transcripts as compared with those co-cultured with CD11b^- subset. In conclusion, a CD1c⁺CD11b⁺ DC subset with elevated frequency in patients with tuberculosis was identified and it promoted Th17 cell differentiation.

Integrated semi-targeted metabolomics analysis reveals distinct metabolic dysregulation in pleural effusion caused by tuberculosis and malignancy

BACKGROUND

Tuberculous pleural effusion (TPE) and malignant pleural effusion (MPE) are the 2 most frequent causes of exudative pleural effusions (PEs). However, the clinical differentiation is challenging.

METHODS

Metabolic signatures in pleural effusion from 156 patients were profiled. An integrated semi-targeted metabolomics platform was incorporated for high throughput metabolite identification and quantitation. In this platform, orbitrap based mass spectrometry with data dependent MS/MS acquisition was applied in the analysis. In-house database containing ~1000MS/MS spectra were established and "MetaInt" was developed for metabolite alignment.

RESULTS

Using this strategy, lower levels of amino acids, citric acid cycle intermediates and free fatty acids accompanied with elevated acyl-carnitines and bile acids were observed, demonstrating increased energy expenditure caused by TPE. Kynurenine pathway from tryptophan was significantly enhanced in TPE. The ratio of tryptophan/kynurenine exhibited decent performance in differentiating TPE from MPE with sensitivity of 92.7% and specificity of 86.1%. After two further independent validations, it turns out that the ratio of tryptophan/kynurenine can be applied confidently as a potential biomarker together with adenosine deaminase (ADA) for clinical diagnosis of TPE.

CONCLUSIONS

Conclusively, the integrated in-house platform for high throughput semi-targeted metabolomics analysis reliably identified great potential of tryptophan/kynurenine ratio as a novel diagnostic biomarker to distinguish pleural effusion caused by tuberculosis and malignancy.