SARS-CoV-2 structural proteins cause periodontal fibrosis

In a recent study posted on bioRxiv* In a preprint server, researchers investigated the pathological effects of structural components of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) on human periodontal cells and tissues, and investigated the effects of coronavirus disease 2019 (COVID-19). 19) and their relationship with deterioration of oral health.

Background

Recent studies have shown that long-lasting coronavirus disease (COVID) symptoms extend beyond the pulmonary system, with persistent complications also occurring in the heart, kidneys, and nervous system. In addition to nasal swabs, saliva samples have been used to test for SARS-CoV-2, and the oral cavity is believed to be a virus reservoir. COVID-19 can pose a serious risk to periodontal health as periodontal tissue is vulnerable to infection. However, the pathogenesis of exacerbation of periodontal disease by COVID-19 remains unclear.

The SARS-CoV-2 spike protein region is the most studied structural part of the virus. This is because most mutations that give rise to variants with improved transmissibility and immune escape occur in the receptor-binding domain of the spike protein. The spike protein is also a prime target for vaccines and monoclonal antibody therapy. However, SARS-CoV-2 is also composed of three other structural components: envelope, membrane and nucleocapsid proteins, and their pathological roles have not been comprehensively investigated.

About research

In this study, researchers used cultured human periodontal ligament fibroblasts (HPLF) and human gingival epithelial cells (HGEPp) to investigate the pathology of COVID-19-associated periodontal fibrosis.

Using immunofluorescence analysis, angiotensin converting enzyme-2 (ACE-2) and transmembrane serine protease 2 (TMPRSS2) receptor for gingival epithelium and periodontal ligament cells, confirmed using Western blot analysis. The possibility of SARS-CoV-2 infecting HPLF was investigated by treating cells with his SARS-CoV-2 spike protein conjugated with a polyhistidine tag (His Tag). An anti-His-tag His allophycocyanin (APC)-conjugated antibody was then used to identify the spike protein by immunofluorescence analysis.

To investigate whether COVID-19 caused periodontal fibrosis, HPLF were infected with lentiviruses carrying plasmids for the envelope, membrane, and nucleocapsid proteins of SARS-CoV-2 or recombinant SARS. – Treated with CoV-2. spike proteinPeriodontal fibroblasts were stimulated for acute and long-term infection, and cell proliferation was assessed by immunostaining for anti-bromodeoxyuridine (BrdU) antibody. Furthermore, to assess periodontal ligament tissue integrity, we used western blotting to determine the production of collagen I and metalloproteinase-1 (MMP1) in the extracellular matrix.

Periodontal ligament fibroblasts treated with SARS-CoV-2 structural components underwent proteomic analysis to determine the molecular mechanisms controlling COVID-19 pathology. Additionally, the Seahorse Mito stress test was performed to understand the impact of SARS-CoV-2 infection on the function of the mitochondrial fatty acid pathway. The results were validated using etomoxir, which inhibits the mitochondrial β-oxidation pathway.

result

As a result, ACE-2 and TMPRSS2 are expressed at high levels in periodontal tissue, and exposure to SARS-CoV-2 structural components, such as membrane and envelope proteins, is associated with hyperproliferation of periodontal fibroblasts, along with apoptosis and senescence. was found to increase the

The molecular mechanisms mediating periodontal fibrosis mainly consisted of the downregulation of mitochondrial β-oxidation by SARS-CoV-2 membrane and envelope proteins. Other studies have revealed an association between downregulated mitochondrial β-oxidation and lung and kidney fibrosis. The results also highlighted the role of SARS-CoV-2 structural components other than the spike protein in disease pathology. The authors discussed various studies that identified alternative mechanisms by which envelope proteins enhance the virulence of SARS-CoV-2, such as increasing pH within the Golgi apparatus and forming cation channels.

Researchers also performed terminal deoxynucleotidyl transferase deoxyuridine triphosphate (dUTP) nick end labeling (TUNEL) to understand the involvement of SARS-CoV-2 structural components in increasing apoptosis and senescence. . increased apoptosis and senescence, and only envelope and membrane proteins did. contributed to

Conclusion

Overall, this study provided new insights into the impact of SARS-CoV-2 infection on periodontal health. The results revealed that SARS-CoV-2 membrane and envelope proteins alter the mitochondrial fatty acid degradation pathway, which is essential for maintaining energy homeostasis. Dysregulation of the mitochondrial β-oxidation pathway causes hyperproliferation of periodontal fibroblasts, leading to fibrosis and increased apoptosis and senescence.These results may contribute to a better understanding of long-term COVID-symptoms Appears in other organ systems and provides therapeutic targets.

*Important Notices

bioRxiv publishes non-peer-reviewed, preliminary scientific reports and should not be considered conclusive, to guide clinical practice/health-related actions, or to be treated as established information .