Current and future options for the diagnosis of malignant pleural effusion

Microbiome profile associated with malignant pleural effusion

Introduction

There is ongoing research into the development of novel molecular markers that may complement fluid cytology malignant pleural effusion (MPE) diagnosis. In this exploratory pilot study, we hypothesized that there are distinct differences in the pleural fluid microbiome profile of malignant and non-malignant pleural diseases.

Method

From a prospectively enrolled pleural fluid biorepository, samples of MPE were included. Non-MPE effusion were included as comparators. 16S rRNA gene V4 region amplicon sequencing was performed. Exact Sequence Variants (ESVs) were used for diversity analyses. The Shannon and Richness indices of alpha diversity and UniFrac beta diversity measures were tested for significance using permutational multivariate analysis of variance. Analyses of Composition of Microbiome was used to identify differentially abundant bacterial ESVs between the groups controlled for multiple hypothesis testing.

Results

38 patients with MPE and 9 with non-MPE were included. A subgroup of patients with metastatic adenocarcinoma histology were identified among MPE group (adenocarcinoma of lung origin (LA-MPE) = 11, breast origin (BA-MPE) = 11). MPE presented with significantly greater alpha diversity compared to non-MPE group. Within the MPE group, BA-MPE was more diverse compared to LA-MPE group. In multivariable analysis, ESVs belonging to family S24-7 and genera Allobaculum, Stenotrophomonas, and Epulopiscium were significantly enriched in the malignant group compared to the non-malignant group.

Conclusion

Our results are the first to demonstrate a microbiome signature according to MPE and non-MPE. The role of microbiome in pleural effusion pathogenesis needs further exploration.

Biomarkers for malignant pleural mesothelioma: a meta-analysis

Malignant pleural mesothelioma (MPM) is a rare but aggressive cancer, and early detection is associated with better survival. Mesothelin, fibulin-3 and osteopontin have been suggested as screening biomarkers. The study conducted a meta-analysis of the mean differences of mesothelin, osteopontin and fibulin-3 in blood and pleural samples. PubMed searches were conducted for studies that measured levels of mesothelin, osteopontin and fibulin-3 in participants with MPM compared with malignancy, benign lung disease or healthy participants. Thirty-two studies with mesothelin levels, 12 studies with osteopontin levels and 9 studies with fibulin-3 levels were included in the meta-analysis. Statistically significant mean differences were seen between MPM patients and all other comparison groups for mesothelin blood and pleural levels. Statistically significant differences in blood osteopontin levels were seen between participants with benign lung disease and healthy participants compared with participants with MPM, but not when comparing participants with cancer with MPM participants. There were not enough studies that reported osteopontin levels in pleural fluid to complete a meta-analysis. Statistically significant differences were seen in both blood and pleural levels of fibulin-3 in MPM patients compared with all other groups. On the basis of these results, mesothelin and fibulin-3 levels appear to be significantly lower in all control groups compared with those with MPM, making them good candidates for screening biomarkers. Osteopontin may be a useful biomarker for screening healthy individuals or those with benign lung disease but would not be useful for screening patients with malignancies.

Identification of differential expressed PE exosomal miRNA in lung adenocarcinoma, tuberculosis, and other benign lesions

Pleural effusion (PE) is a common clinical complication of many pulmonary and systemic diseases, including lung cancer and tuberculosis. Nevertheless, there is no clinical effective biomarker to identify the cause of PE. We attempted to investigate differential expressed exosomal miRNAs in PEs of lung adenocarcinoma (APE), tuberculous (TPE), and other benign lesions (NPE) by using deep sequencing and quantitative polymerase chain reaction (qRT-PCR). As a result, 171 differentiated miRNAs were observed in 3 groups of PEs, and 11 significantly differentiated exosomal miRNAs were validated by qRT-PCR. We identified 9 miRNAs, including miR-205-5p, miR-483-5p, miR-375, miR-200c-3p, miR-429, miR-200b-3p, miR-200a-3p, miR-203a-3p, and miR-141-3p which were preferentially represented in exosomes derived from APE when compared with TPE or NPE, while 3 miRNAs, including miR-148a-3p, miR-451a, and miR-150-5p, were differentially expressed between TPE and NPE. These different miRNAs profiles may hold promise as biomarkers for differential diagnosis of PEs with more validation based on larger cohorts.

CD163+CD14+ macrophages, a potential immune biomarker for malignant pleural effusion

BACKGROUND

Malignant pleural effusion (MPE) is a common complication caused by malignant diseases. However, subjectivity, poor sensitivity, and substantial false-negative rates of cytology assay hamper accurate MPE diagnosis. The aim of this study was to assess whether CD163+CD14+ tumor-associated macrophages (TAMs) could be used as a biomarker for enabling sensitive and specific MPE diagnosis.

METHODS

Pleural effusion samples and peripheral blood samples were collected from 50 MPE patients and 50 non-malignant pleural effusion (NMPE) patients, respectively. Flow cytometry was performed to analyze cell phenotypes, and RT-qPCR was used to detect cytokine expression in these monocytes and macrophages. A blinded validation study (n = 40) was subsequently performed to confirm the significance of CD163+CD14+ TAMs in MPE diagnosis. Student's t test, rank sum test, and receiver operating characteristic curve analysis were used for statistical analysis.

RESULTS

Notably, CD163+CD14+ cell frequency in MPE was remarkably higher than that in NMPE (P < 0.001). In a blinded validation study, a sensitivity of 78.9 % and a specificity of 100 % were obtained with CD163+CD14+ TAMs as a MPE biomarker. In total (n = 140), by using a cutoff level of 3.65 %, CD163+CD14+ cells had a sensitivity of 81.2 % and a specificity of 100 % for MPE diagnosis. Notably, MPE diagnosis by estimating CD163+CD14+ cells in pleural effusion could be obtained one week earlier than that obtained by cytological examination.

CONCLUSIONS

CD163+CD14+ macrophages could be potentially used as an immune diagnostic marker for MPE and has better assay sensitivity than that of cytological analysis.

Diagnostic accuracy of endostatin for malignant pleural effusion: A clinical study and meta-analysis

BACKGROUND

The diagnosis of malignant pleural effusion (MPE) remains a clinical challenge. Many studies suggest that endostatin is a potential marker for MPE. This study aimed to determine the diagnostic value of endostatin with respect to MPE and to summarize the overall diagnostic performance of endostatin via a meta-analysis.

METHODS

Pleural effusion samples from patients with both malignant and nonmalignant disease were collected, and the pleural levels of endostatin and carcino-embryonic antigen (CEA) were subsequently measured. The diagnostic performances of endostatin and CEA were analyzed via standard receiver operator characteristic curve analysis methods, using the AUC as a measure of accuracy. The overall diagnostic accuracy of endostatin for MPE was summarized through a bivariate meta-analysis with standard method recommended.

RESULTS

Fifty-two patients with MPEs and 64 patients with benign pleural effusions (BPEs) were included this study. Pleural endostatin levels were significantly increased in the setting of MPE compared with BPE (104.78 ± 64.58 vs. 56.81 ± 28.84 ng/ml; p < 0.001). Using a cutoff value of 79.7 ng/ml, the sensitivity and specificity of endostatin in diagnosing MPE were shown to be 51.92% and 85.94%, respectively, and the AUC was 0.747. The combination of endostatin and CEA enhanced diagnostic performance with respect to MPE. In addition to this study, another eight studies were included in this meta-analysis. The pooled diagnostic estimates were 0.69 for sensitivity and 0.78 for specificity. The positive likelihood ratio and negative likelihood ratio for endostatin were 3.16 and 0.40, respectively. The diagnostic odds ratio was 7.89, and the AUC of the summary receiver operator characteristic curve was 0.79.

CONCLUSION

Pleural levels of endostatin are increased in the setting of MPE. However, endostatin exhibits a limited efficacy for the diagnosis of MPE and shows a relatively low sensitivity. The assessment of endostatin in combination with CEA may enhance diagnostic accuracy with respect to MPE.

"Dry" pleural mesothelioma successfully diagnosed on endobronchial ultrasound (EBUS)-guided transbronchial needle aspiration (TBNA)

The acquisition of histologic material is obligatory in order to establish the diagnosis of malignant pleural mesothelioma (MPM). In particular, tissue acquisition in cases of "dry" MPM (focal pleural thickening without pleural effusion or mediastinal lymph node involvement) is usually performed via a thoracoscopic pleural biopsy. In contrast, the techniques for performing echoendoscopic (transbronchial or transesophageal) needle aspiration of pleural lesions have only rarely been reported due to the theoretical limitations of tissue acquisition in such cases. We herein report the first case of "dry" MPM successfully diagnosed via endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA) in a 73-year-old man presenting with a pleural mass in the right costovertebral recess, adjacent to the carina. The patient underwent radical resection, and a definitive pathological examination confirmed the diagnosis of epithelioid MPM.