The recent COVID-19 pandemic promoted efforts to better understand the organization of the respiratory microbiome and its evolution from birth to adulthood and how it interacts with external pathogens and the host immune system. This review aims to deepen understanding of the essential physiological functions of the resident microbiome of the respiratory system on human health and diseases. First, the general characteristics of the normal microbiota in the different anatomical sites of the airways have been reported in relation to some factors such as the effect of age, diet and others on its composition and stability. Second, we analyze in detail the functions and composition and the correct functionality of the microbiome in the light of current knowledge. Several studies suggest the importance of preserving the micro-ecosystem of commensal, symbiotic and pathogenic microbes of the respiratory system, and, more recently, its relationship with the intestinal microbiome, and how it also leads to the maintenance of human health, has become better understood.

Poor diet, obesity and a sedentary lifestyle have a significant impact on natural microbiota disorders; specifically, the intestinal one. This in turn can lead to a multitude of organ dysfunctions. The gut microbiota contains more than 500 species of bacteria and constitutes 95% of the total number of cells in the human body, thus contributing significantly to the host’s resistance to infectious diseases. Nowadays, consumers have turned to purchased foods, especially those containing probiotic bacteria or prebiotics, that constitute some of the functional food market, which is constantly expanding. Indeed, there are many products available that incorporate probiotics, such as yogurt, cheese, juices, jams, cookies, salami sausages, mayonnaise, nutritional supplements, etc. The probiotics are microorganisms that, when taken in sufficient amounts, contribute positively to the health of the host and are the focus of interest for both scientific studies and commercial companies. Thus, in the last decade, the introduction of DNA sequencing technologies with subsequent bioinformatics processing contributes to the in-depth characterization of the vast biodiversity of the gut microbiota, their composition, their connection with the physiological function—known as homeostasis—of the human organism, and their involvement in several diseases. Therefore, in this study, we highlighted the extensive investigation of current scientific research for the association of those types of functional foods containing probiotics and prebiotics in the diet and the composition of the intestinal microbiota. As a result, this study can form the foundation for a new research path based on reliable data from the literature, acting a guide in the continuous effort to monitor the rapid developments in this field.

Aim: This historical medical literature review aims at understanding the evolution of the medical existence of oral cancer over times, particularly better comprehending if the apparent lower prevalence of this type of cancer in antiquity is a real value due to the absence of modern environmental and lifestyle factors or it is linked to a misinterpretation of ancient foreign terms found in ancient medical texts regarding oral neoplasms. Methods: The databases MedLne, PubMed, Web of Science, Elsevier’s EMBASE.com, Cochrane Review, National Library of Greece (Stavros Niarchos Foundation, Athens) and the Library of the School of Health Sciences of the National and Kapodistrian University of Athens (Greece) were extensively searched for relevant studies published during the past century on the history of oral cancer and its treatment from antiquity to modern times, in addition to the WHO website to analyse the latest epidemiological data. In addition, we included historical books on the topic of interest and original sources. Results: Historical references reveal that the cradle of the oral oncology was in ancient Egypt, the Asian continent and Greece and cancer management was confined to an approximate surgical practice, in order to remove abnormal masses and avoid bleeding with cauterization. In the Medieval Age, little progress occurred in medicine in general, oral cancers management included. It is only from the Renaissance to modern times that knowledge about its pathophysiological mechanisms and histopathology and its surgical and pharmacological treatment approaches became increasingly deep all over the world, evolving to the actual integrated treatment. Despite the abundant literature exploring oncology in past civilizations, the real prevalence of oral cancer in antiquity is much less known; but a literature analysis cannot exclude a consistent prevalence of this cancer in past populations, probably with a likely lower incidence than today, because many descriptions of its aggressiveness were found in ancient medical texts, but it is still difficult to be sure that each single description of oral masses could be associated to cancer, particularly for what concerns the period before the Middle Ages. Conclusions: Modern oncologists and oral surgeons must learn a lot from their historic counterparts in order to avoid past unsuccessful efforts to treatment oral malignancies. Several descriptions of oral cancers in the antiquity that we found let us think that this disease might be linked to mechanisms not strictly dependent on environmental risk factors, and this might guide future research on oral cavity treatments towards strategical cellular and molecular techniques.

Several studies have shown that the gut microbiota influences behavior and, in turn, changes in the immune system associated with symptoms of depression or anxiety disorder may be mirrored by corresponding changes in the gut microbiota. Although the composition/function of the intestinal microbiota appears to affect the central nervous system (CNS) activities through multiple mechanisms, accurate epidemiological evidence that clearly explains the connection between the CNS pathology and the intestinal dysbiosis is not yet available. The enteric nervous system (ENS) is a separate branch of the autonomic nervous system (ANS) and the largest part of the peripheral nervous system (PNS). It is composed of a vast and complex network of neurons which communicate via several neuromodulators and neurotransmitters, like those found in the CNS. Interestingly, despite its tight connections to both the PNS and ANS, the ENS is also capable of some independent activities. This concept, together with the suggested role played by intestinal microorganisms and the metabolome in the onset and progression of CNS neurological (neurodegenerative, autoimmune) and psychopathological (depression, anxiety disorders, autism) diseases, explains the large number of investigations exploring the functional role and the physiopathological implications of the gut microbiota/brain axis.

Background: Various microorganisms such as bacteria, virus, and fungi can infect humans and cause not just a simple infection but septic conditions, organ dysfunction, and precancerous conditions or cancer involving various organ systems. After the discovery of the microscope, it was easier to discover and study such microorganisms, as in the case of Helicobacter pylori, a pathogen that was seen in the distant era of the nineteenth century but without being recognized as such. It took 100 years to later discover the pathogenesis and the cancer that this bacterium can cause. Since it was discovered, until today, there has been a continuous search for the understanding of its pathogenetic mechanisms, and the therapeutic approach is continuously updated. Methods: We investigated how diagnosis and therapy were dealt with in the past and how researchers sought to understand, exactly, the pathogenetic biomolecular mechanisms of H. pylori, from the genesis of the infection to the current knowledge, with an analysis of carcinogenic mechanisms in the stomach. We have examined the scientific evolution of the knowledge of the disease over these 40 years in the gastroenterological and pharmacological fields. This was possible through a search in the databases of Medline, the WHO website, the Centers for Disease Control and Prevention (CDC) website, PubMed, and Web of Science to analyze the earlier and the latest data regarding H. pylori. Results: With the scientific discoveries over time, thanks to an increasing number of progressions in scientific research in the analysis of the gastric mucosa, the role of Helicobacter pylori in peptic ulcer, carcinogenesis, and in some forms of gastric lymphoma was revealed. Furthermore, over the years, the biomolecular mechanism involvement in some diseases has also been noted (such as cardiovascular ones), which could affect patients positive for H. pylori. Conclusions: Thanks to scientific and technological advances, the role of the bacterium H. pylori in carcinogenesis has been discovered and demonstrated, and new prospective research is currently attempting to investigate the role of other factors in the stomach and other organs. Cancer from H. pylori infection had a high incidence rate compared to various types of cancer, but in recent years, it is improving thanks to the techniques developed in the detection of the bacterium and the evolution of therapies. Thus, although it has become an increasingly treatable disease, there is still continuous ongoing research in the field of treatment for resistance and pharma compliance. Furthermore, in this field, probiotic therapy is considered a valid adjuvant.

This study is focused on the epidemiological characteristics and biomolecular mechanisms that lead to the development of precancerous and cancerous conditions of oral lesions related to Human Papilloma Virus (HPV) infections. Current evidence from the literature demonstrates the role of HPV in potentially malignant oral disorders. Therefore, the underlying biomolecular processes can give arise, or contribute to, benign lesions as well as to oral carcinogenesis.