Covid-19 and oral diseases: Crosstalk, synergy or association?

The coronavirus disease 2019 (Covid-19) is a viral infection caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) that clinically affects multiple organs of the human body. Cells in the oral cavity express viral entry receptor angiotensin-converting enzyme 2 that allows viral replication and may cause tissue inflammation and destruction. Recent studies have reported that Covid-19 patients present oral manifestations with multiple clinical aspects. In this review, we aim to summarise main signs and symptoms of Covid-19 in the oral cavity, its possible association with oral diseases, and the plausible underlying mechanisms of hyperinflammation reflecting crosstalk between Covid-19 and oral diseases. Ulcers, blisters, necrotising gingivitis, opportunistic coinfections, salivary gland alterations, white and erythematous plaques and gustatory dysfunction were the most reported clinical oral manifestations in patients with Covid-19. In general, the lesions appear concomitant with the loss of smell and taste. Multiple reports show evidences of necrotic/ulcerative gingiva, oral blisters and hypergrowth of opportunistic oral pathogens. SARS-CoV-2 exhibits tropism for endothelial cells and Covid-19-mediated endotheliitis can not only promote inflammation in oral tissues but can also facilitate virus spread. In addition, elevated levels of proinflammatory mediators in patients with Covid-19 and oral infectious disease can impair tissue homeostasis and cause delayed disease resolution. This suggests potential crosstalk of immune-mediated pathways underlying pathogenesis. Interestingly, few reports suggest recurrent herpetic lesions and higher bacterial growth in Covid-19 subjects, indicating SARS-CoV-2 and oral virus/bacteria interaction. Larger cohort studies comparing SARS-CoV-2 negative and positive subjects will reveal oral manifestation of the virus on oral health and its role in exacerbating oral infection.

Oral ulcers in HIV-positive Peruvian patients: an immunohistochemical and in situ hybridization study.

BACKGROUND: This study describes the histopathological, immunohistochemical (IHC) and in situ hybridization (ISH) data of 25 cases of oral ulcers in HIV-positive patients, with clinical and microscopical features similar to ulcers not otherwise specified (NOS)/necrotizing ulcerative stomatitis (NUS). METHODS: Sex, age and clinical history were obtained from the clinical records. Histological analysis for H&E, Gomori-Grocott and Ziehl-Neelsen stains, IHC analysis to detect infectious agents and to characterize inflammatory cellular infiltrate, and ISH for cytomegalovirus (CMV) and EBER1/2 were performed. RESULTS: Twenty-one patients were men and four were women (mean age of 34.6 years). The tongue was preferentially affected. Microscopically, the lesions showed extensive necrosis, leukocytoclasia, vasculitis with luminal fibrin clots and an intense inflammatory cellular infiltrate predominated by CD68(+) atypical large cells, normal-sized and crescent-shaped nuclei macrophages, interspersed by CD8(+) T lymphocytes. Mast cells were also observed in all samples studied. CD4(+) T lymphocytes, CD20(+) B lymphocytes and VS38c(+) plasma cells were practically absent. CMV and EBER1/2 were identified in scarce cells of 3 and 16 of 25 cases respectively. CONCLUSION: These results show that CD68(+) macrophages, followed by CD8(+) T lymphocytes, were the predominant inflammatory cells, indicating they are relevant to the pathogenesis of the ulcers, possibly reflecting an abnormal immune response in the oral mucosa. The clinicopathological and immunoprofile features of the present cases are similar to NOS ulcers/NUS in HIV-positive patients.