Transcriptional regulation and small compound targeting of ACE2 in lung epithelial cells.

Angiotensin-converting enzyme 2 (ACE2) is the receptor of COVID-19 pathogen SARS-CoV-2, but the transcription factors (TFs) that regulate the expression of the gene encoding ACE2 (ACE2) have not been systematically dissected. In this study we evaluated TFs that control ACE2 expression, and screened for small molecule compounds that could modulate ACE2 expression to block SARS-CoV-2 from entry into lung epithelial cells. By searching the online datasets we found that 24 TFs might be ACE2 regulators with signal transducer and activator of transcription 3 (Stat3) as the most significant one. In human normal lung tissues, the expression of ACE2 was positively correlated with phosphorylated Stat3 (p-Stat3). We demonstrated that Stat3 bound ACE2 promoter, and controlled its expression in 16HBE cells stimulated with interleukin 6 (IL-6). To screen for medicinal compounds that could modulate ACE2 expression, we conducted luciferase assay using HLF cells transfected with ACE2 promoter-luciferase constructs. Among the 64 compounds tested, 6-O-angeloylplenolin (6-OAP), a sesquiterpene lactone in Chinese medicinal herb Centipeda minima (CM), represented the most potent ACE2 repressor. 6-OAP (2.5 µM) inhibited the interaction between Stat3 protein and ACE2 promoter, thus suppressed ACE2 transcription. 6-OAP (1.25-5 µM) and its parental medicinal herb CM (0.125%-0.5%) dose-dependently downregulated ACE2 in 16HBE and Beas-2B cells; similar results were observed in the lung tissues of mice following administration of 6-OAP or CM for one month. In addition, 6-OAP/CM dose-dependently reduced IL-6 production and downregulated chemokines including CXCL13 and CX3CL1 in 16HBE cells. Moreover, we found that 6-OAP/CM inhibited the entry of SARS-CoV-2 S protein pseudovirus into target cells. These results suggest that 6-OAP/CM are ACE2 inhibitors that may potentially protect lung epithelial cells from SARS-CoV-2 infection.

[Clinical features of Gorham-Stout syndrome and literature review].

OBJECTIVE: To describe the clinical presentations, radiographic findings and histological pathology of bones, diagnosis, treatment options and prognosis for patients with Gorham-Stout syndrome (GSS). METHODS: Clinical data of 5 GSS patients seen from January 1980 to January 2008 were reviewed. RESULTS: (1) There were 2 males and 3 females, aged 15 years to 37 years (mean age was 30.2 years). (2) All of them had osteolysis, but the site and extent of involved bones were not the same. Three cases had large amount of bloody pleural effusion and two of them had also chylous effusion. All of the 5 cases had no evidence of malignancies. Four cases accepted bone biopsy. Among them,2 cases having local puncture and open biopsy showed typical bone pathologic manifestations. (3) Various forms of treatment including bisphosphonates, calcium supplementation, active vitD3 treatment, local radiation therapy and surgical ligation of thoracic duct were tried. (4) Follow up and clinical outcomes: the two cases, who had only bone osteolysis remained stable. Of the other three cases who had bone osteolysis associated with pleural effusion, one patient needed interrupted effusion drainage with stable bone impairment and the other two cases were out of contact. CONCLUSIONS: GSS is a rare disorder characterized by progressive osteolysis. The clinical presentations of this disease are variable and depend on the sites of involvement. There were no standard therapy available. Prognosis depends on the site of involvement, extent of the disease and presence of complications. Those who have pleural effusion had poor prognosis.