Abstract
To clarify the predominance of Th1 or Th2 immune responses in malignant and tuberculous pleural effusion (MPE and TPE, respectively), we performed a meta-analysis of previously published results of the levels of Th1/Th2 cytokines associated with these two types of pleural effusion to evaluate the use of Th1/Th2 cytokine profiles in distinguishing TPE from MPE. We searched the PubMed and EMBASE databases for studies indexed from 2000 to March 2021. We included studies that (a) diagnosed TPE and MPE based on culture or pleural tissue biopsy and that (b) compared levels of Th1/Th2 cytokines between TPE and MPE. Pooled data based on a random-effects model or fixed-effects model and standardized mean differences (SMDs) across studies were used to compare TPE and MPE. We also performed Egger’s test to assess publication bias. Of 917 identified studies, a total of 42 studies were selected for the meta-analysis. Compared with MPE subjects, TPE subjects had a significantly higher level of TNF-α [2.22, (1.60–2.84)], an elevated level of IFN-γ [3.30, (2.57–4.40)] in pleural effusion, a situation where the Th1 immune response dominated. Conversely, the levels of interleukin-4 (IL-4) and IL-10 (Th2 cytokines) were higher in the MPE subjects than in the TPE subjects, showing statistically nonsignificant tiny effects [−0.15, (−0.94 to 0.63) and −0.04, (−0.21 to 0.12), respectively]. We confirmed that TPE, a situation in which the Th1 cytokines are predominant. The slight preponderance of Th2 cytokines in MPE, which is not convincing enough to prove.
Highlights
MethodsThis meta-analysis was carried out in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-analysis (PRISMA) S tatement[14], and it had been registered with International Platform of Registered Systematic Review and Meta-analysis Protocols (No INPLASY202210005)
A total of 917 potentially relevant studies identified from the database were retrieved, of which 43 studies were included in the final meta-analytical processes
Consistent with the results of other studies, our study found higher levels of IL-6 in TPE subjects, which suggested that IL-6, as an important cytokine, may be involved in the formation of TPE and play an important role in the occurrence and development of pulmonary tuberculosis (PTB)
Summary
This meta-analysis was carried out in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-analysis (PRISMA) S tatement[14], and it had been registered with International Platform of Registered Systematic Review and Meta-analysis Protocols (No INPLASY202210005). An approval from the institutional review board was not necessary, as we extracted only summary information from previously published articles. A systematic search was conducted (Zeng Y.L. and Qi Y.) of the PubMed and EMBASE databases from 2000 to March 2021. The following key words were used in the database search: malignant pleural effusion, tuberculous pleural effusion, tumor necrosis factor-alpha, TNF-α, interferon gamma, IFN-γ, interleukin 2, IL-2, interleukin 4, IL-4, interleukin 5, IL-5, interleukin 6, IL-6, interleukin 10, and IL-10. The details of the strategy are available in Supplementary Methods
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