Letter to the Editor – Oral microbiota, health and cancer: the dual face of the same coin in the field of the host-microbe interactome

Dear Editor In recent years, within the extensive research regarding human microbiota and chronic diseases, new medical and laboratory technologies have played a crucial role in understanding more complex biological pathways between human cells and microbes. On the other hand, molecular and cellular diversity and their involvement in health responses to changing host conditions have only recently been understood, through the development of brand-new laboratory tools based on ‘omics approaches. The continuous insertion of already conceptualized, new experimental large datasets and raw data onto bibliographic platforms means that they are now accessible for subsequent elaboration by other researchers. This aspect has allowed the creation of an interactive mesh of proteins, genes, and small molecules, usually called, interactome or interactomics. Oral microbiota a “conditio sine qua non “in health and disease The Microbiota associated with the human oral cavity represent a collective-interactive group of microbial species, mainly composed of bacteria (Firmicutes, Bacillus, Proteobacteria, and Actinomycetes) but also with some protozoa, fungi, and viral species, and is one of the most complex microbial communities in the human body1,2. These microorganisms are closely associated and disposed of as biofilm in different distinct habitats of the oral cavity, such as the tongue, teeth, mucosal surfaces, so that about 6-7 different microbiotas are present in the mouth, with the tongue dorsum showing the main extensive microbial community in the oral cavity. The types of bacteria found in oral microbiota do not change significantly; in fact, healthy people from different countries with different alimentary habits have similar compositions of oral microbiota, in this condition microorganisms coexisting in normal human tissues and provide proper functional activity in the host. This process activates the control of different fundamental processes such as immunity signal transduction, gene expression patterns and metabolism. The imbalance of oral microflora, normally called dysbiosis, has been strictly correlated with the genesis of different chronic diseases such as cancer3. For example, the anaerobic oral bacteria Fusobacterium nucleatum, which regularly lives on the tongue dorsum, normally conducts a commensal-type cell life, activating various useful biological processes such as: oral-nasal innate immunity, food flavour, and others4. In these conditions, the oral i