The Lung Microbiome in Health and Lung Carcinogenesis

Abstract

It is now well-established that the human microbiota can have both a beneficial and a detrimental impact on the human body, with imbalanced microbial composition (dysbiosis) having been reported to play an essential role in different diseases including cancer. It has been suggested that the host microbiome promotes cancer development by inducing inflammatory responses, genotoxicity, dysregulation of the host immune responses and metabolism. Most of cancer- associated microbiota studies over the last decades have been extensively conducted on the gut microbiota and its role in gastrointestinal cancers. Given the initial idea that the lung is a sterile and microbial free organ, a small number of studies have started to focus on the contribution of lung microbial communities in lung cancer development. These recent studies observed that dysbiosis of certain bacterial taxa is associated with lung carcinogenesis. The main purpose of this review is to organise and summarise the current findings on the lung microbiome and its role in malignant lung tumour development and progression, as well as to understand the mechanisms underlying the involvement of lung microbiota in lung cancer. Lastly, the limitations and challenges that the lung microbiome research field is facing, in addition to how the current knowledge on lung microbiota can have a critical impact on lung cancer diagnosis and therapeutic approaches establishment, are extensively being discussed.