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Pulpitis, inflammation of the dental pulp, is a disease that often necessitates emergency dental care. While pulpitis is considered to be a microbial disease primarily caused by bacteria, viruses have also been implicated in its pathogenesis. Here, we determined the expression of the SARS-CoV2 receptor, angiotensin converting enzyme 2 (ACE2) and its associated cellular serine protease TPMRSS2 in the dental pulp under normal and inflamed conditions. Next, we explored the relationship between the SARS-CoV-2/human interactome and genes expressed in pulpitis. Using existing datasets we show that both ACE2 and TPMRSS2 are expressed in the dental pulp and, that their expression does not change under conditions of inflammation. Furthermore, Master Regulator Analysis of the SARS-CoV2/human interactome identified 75 relevant genes whose expression values are either up-regulated or down-regulated in both the human interactome and pulpitis. Our results suggest that the dental pulp is vulnerable to SARS-CoV2 infection and that SARS-CoV-2 infection of the dental pulp may contribute to worse outcomes of pulpitis.

OBJECTIVE: In human pathology, SARS-CoV-2 utilizes multiple molecular pathways to determine structural and biochemical changes within the different organs and cell types. The clinical picture of patients with COVID-19 is characterized by a very large spectrum. The reason for this variability has not been clarified yet, causing the inability to make a prognosis on the evolution of the disease. MATERIALS AND METHODS: PubMed search was performed focusing on the role of ACE 2 receptors in allowing the viral entry into cells, the role of ACE 2 downregulation in triggering the tissue pathology or in accelerating previous disease states, the role of increased levels of Angiotensin II in determining endothelial dysfunction and the enhanced vascular permeability, the role of the dysregulation of the renin angiotensin system in COVID-19 and the role of cytokine storm. RESULTS: The pathological changes induced by SARS-CoV-2 infection in the different organs, the correlations between the single cell types targeted by the virus in the different human organs and the clinical consequences, COVID-19 chronic pathologies in liver fibrosis, cardiac fibrosis and atrial arrhythmias, glomerulosclerosis and pulmonary fibrosis, due to the systemic fibroblast activation induced by angiotensin II are discussed. CONCLUSIONS: The main pathways involved showed different pathological changes in multiple tissues and the different clinical presentations. Even if ACE2 is the main receptor of SARS-CoV-2 and the main entry point into cells for the virus, ACE2 expression does not always explain the observed marked inter-individual variability in clinical presentation and outcome, evidencing the complexity of this disorder. The proper interpretation of the growing data available might allow to better classifying COVID-19 in human pathology.

Despite the unprecedented effort of the scientific community, the novel SARS-CoV-2 virus has infected more than 46 million people worldwide, killing over one million two hundred thousand. Understanding the mechanisms by which some individuals are more susceptible to SARS-CoV-2 infection and why a subgroup of them are prone to experience severe pneumonia, and death should lead to a better approach and more effective treatments for COVID-19. Here, we focus our attention on ACE2, a primary receptor of SARS-CoV-2. We will discuss its biology, tissue expression, and post-translational regulation that determine its potential to be employed by SARS-CoV-2 for cell entry. Particular attention will be given to how the ACE2 soluble form can have a great impact on disease progression and thus be used in a potential therapeutic strategy. Furthermore, we will discuss repercussions that SARS-CoV-2/ACE2 binding has on the renin–angiotensin system and beyond. Indeed, although mostly neglected, ACE2 can also act on [des-Arg 937]-bradykinin of the kinin–kallikrein system regulating coagulation and inflammation. Thorough comprehension of the role that ACE2 plays in different pathways will be the key to assess the impact that SARS-CoV-2/ACE2 binding has on organismal physiology and will help us to find better therapies and diagnostic tools.