TLR4 and periodontitis: The conjunction of LPS and SARS-CoV-2 S protein activates toll-like receptor 4 (TLR4) in extremely low concentrations of LPS, e.g. of 1ng/ml, causing NET formation via the NF-κB activation (86), is a phenomenon playing a crucial role for the severe COVID-19 course in patients with LGE such as those with obesity, diabetes, CVD and periodontitis.