A Preliminary Study of Microbiota Diversity in Saliva and Bronchoalveolar Lavage Fluid from Patients with Primary Bronchogenic Carcinoma

Abstract

Background The present study aimed to evaluate the difference in microbiota diversity in the oral cavity and fluid bronchoalveolar lavage (BALF) of patients with lung cancer. Material/Methods Buccal (saliva) and lower respiratory tract BALF samples were collected from 51 patients with primary bronchogenic carcinoma and 15 healthy controls, and bacterial genomic DNA was extracted. High-throughput 16S rDNA amplicon sequencing was performed, and microbial diversity, composition, and functions of microbiota were analyzed by bioinformatics methods. Results Patients with lung cancer have lower microbial diversity than healthy controls in both saliva and BALF samples. Significant segregation was observed between the different pathological types of lung cancer groups and the control group regardless of the sampling site. Treponema and Filifactor were identified as potential bacterial biomarkers in BALF samples, while Filifactor was ideal to distinguish healthy controls from lung cancer patients. Moreover, the predictive variation analysis of the KEGG (Kyoto Encyclopedia of Genes and Genomes) metabolic pathway showed that the metabolic differences in microbiota varied by sampling site. Conclusions Lung cancer patients carry a different and less diverse microorganism community than healthy controls. Certain bacterial taxa might be associated with lung cancer, but the exact species depends on the sampling site and the pathological type. This study provides basic data on the microbiota diversity in BALF and saliva samples from lung cancer patients. Further investigation with a larger sample size should help validate the enriched species in different pathological types of lung cancers.

Microbiota Core in Central Lung Cancer with Streptococcal Enrichment as a Possible Diagnostic Marker

“…In terms of beta diversity, the tissues involved in cancer and the contralateral bronchus had almost identical compositions, as its have been previously published [6,34,35] especially Pseudomonas, has been also previously corroborated [5,6,37]. Higher concentrations of Streptococcus, Blautia, Akkermansia, and Rothia were observed in patients, but Streptococcus was consistently the major marker linked to lung cancer.…”

“…Low biodiversity is usually observed in various pathologies, including cancer, but we found significantly higher alpha-diversity values in cancer than in the control group. Other authors have published analogous [8] and opposing results [5,6,35]. Moreover advanced cancer stages [36] and reduced recurrence-free survival and disease-free survival [35] have been associated with higher values of alpha diversity.…”

“…However, recent data clearly indicate that the microbiota contributes to the prognosis of cancer and determines the response to treatments, particularly responses to the new immunomodulatory therapies [9,28]. Criteria for the normal composition of lung microbiota have not yet been established, but the available data indicate that their composition in cancer patients differs considerably from that of healthy individuals [4][5][6][7][8].…”

“…Significant differences in the lung ecosystem have been described based on health status or a lung cancer diagnosis in sputum [33], bronchoalveolar lavage [5], protected specimen brushing [6], cytological brushing [34], and surgical tissue [7,8,35]. The major contribution of our work is the study of the microbiome surrounding central cancer via direct sampling, but our results are not necessarily applicable to the distal airway.…”

“…Dysbiosis is typically detected surrounding tumors tissues [3], and this trait has been poorly explored in the respiratory airway tissues, and using only surgical samples [4][5][6][7][8]. An understanding of the microbiota is necessary to decipher its possible causal role in cancer, and also to elucidate the prognosis and response to immunomodulatory therapies, because microorganisms and/or their metabolites shape the local microenvironment, influence the immune response, and impact the final battle against cancer [9].…”