Lung microbiome

An overview of the lung microbiome and its implications in health and disease.

Lung microbiome refers to the community of microorganisms, including bacteria, viruses, fungi, and archaea, that reside in the respiratory tract. This complex ecosystem plays a crucial role in maintaining respiratory health and influencing disease processes.

Introduction

The concept of the lung microbiome challenges the traditional view that the lungs are sterile. Advances in sequencing technologies have revealed that the lungs harbor a diverse array of microorganisms, which are essential for immune regulation and respiratory health.

Composition of the Lung Microbiome

The lung microbiome is composed of various microbial communities that differ in composition from those found in other parts of the body, such as the gut microbiome. The predominant phyla in the lung microbiome include Firmicutes, Bacteroidetes, Proteobacteria, and Actinobacteria.

Bacteria

Bacteria are the most studied components of the lung microbiome. Common genera include Streptococcus, Prevotella, and Veillonella. These bacteria are thought to play roles in modulating immune responses and protecting against pathogenic infections.

Viruses

The lung virome includes both commensal and pathogenic viruses. Respiratory viruses such as rhinoviruses, coronaviruses, and influenza viruses can alter the lung microbiome composition and impact respiratory health.

Fungi

Fungal species such as Candida and Aspergillus are part of the lung mycobiome. While typically present in low abundance, these fungi can become pathogenic under certain conditions, such as immunosuppression.

Functions of the Lung Microbiome

The lung microbiome contributes to respiratory health through several mechanisms:

• Immune Modulation: The lung microbiome interacts with the host immune system, influencing the development and function of immune cells.
• Barrier Protection: Microbial communities help maintain the integrity of the respiratory epithelium, preventing colonization by pathogens.
• Metabolic Functions: Microbes in the lungs can produce metabolites that affect host physiology and immune responses.

Lung Microbiome and Disease

Alterations in the lung microbiome, known as dysbiosis, have been associated with various respiratory diseases:

• Asthma: Changes in the lung microbiome composition have been linked to asthma pathogenesis and exacerbations.
• Chronic Obstructive Pulmonary Disease (COPD): Dysbiosis in COPD patients is associated with disease severity and progression.
• Cystic Fibrosis: The lung microbiome in cystic fibrosis patients is often dominated by pathogenic bacteria such as Pseudomonas aeruginosa.
• Lung Cancer: Emerging evidence suggests that the lung microbiome may influence lung cancer development and response to therapy.

Research and Future Directions

Ongoing research aims to better understand the lung microbiome's role in health and disease. Potential therapeutic strategies include microbiome modulation through probiotics, prebiotics, and antibiotics.

Also see

• Gut microbiome
• Human microbiome
• Respiratory tract infections
• Microbiome in health and disease