Rising level of pulmonary dioxin might trigger CMV and HSV-1 reactivation via bHLH/PAS/AhR:ARNT transcription pathway in lungs of immunocompetent COVID-19 patients with ARDS

ABSTRACT

Study objective. It has been shown that human common viruses are new target genes for host cell dioxin receptor transcriptional (AhR-ARNT) complex initially proven to up-regulate mammalian genes containing dioxin-response elements (DRE) in the promoters [doi10.1016/j.ijid.2012.05.265]. Initially, transactivation of HIV-1 and HBV by 2,3,7,8-tetrachlodibenzop- dioxin (TCDD) at low nanomolar range was demonstrated [doi10.3109/00498259309057034]. Noteworthy, transactivation of human cytomegalovirus (CMV) was shown with 0.3 ppt dioxin, i.e. lower than its current background level in the general population (~3.0 ppt). Recently, reactivation of CMV infection was found to influence worse clinical outcome following SARS-CoV-2 infection (doi 10.1186/s12979-020- 00185-x). Other findings showed that CMV and herpes simplex virus 1 (HSV-1) reactivation were observed in immunocompetent patients with COVID-19 acute respiratory distress syndrome (ARDS) (doi.org/10.1186/s13054-020-03252-3). Addressing occurrence of Herpesviridae reactivation in severe COVID-19 patients, and still unspecified real triggers of CMV and HSV-1 reactivations, we tested TCDD, which current body burden (DBB) ranges from 20 pg/g (TEQ in fat) in general population to 100 pg/g in older people. Methods. In Silico quantitation of active DRE in promoters of viral genes. Virus DNA hybridization assay. Clinical and epidemiological analyses. Results and Discussion. In this study, a computational search for DRE in CMV and HSV-1 genes was performed by SITECON, a tool recognizing potentially active transcriptional factor binding sites. In silico analysis revealed in regulatory region of CMV IE genes from 5 to 10 DRE, and from 6 to 8 DRE in regulatory region of HSV-1 IE genes.We established that a low picomolar TCDD can trigger up-regulation of CMV and HSV-1 genes via AhRArnt transcription factor in macrophage(doi.org/10.1016/ j.ijid.2012.05.265) and glial human cell lines (doi.org/10.1016/j. jalz.2016.06.1268), respectively. In fact, viral reactivation may be triggered in COVID-19 ARDS patients by higher pulmonary TCDD concentrations, because "lipid storm" within lungs of severe COVID-19 patients has been recently reported (doi.org/ 10.1101/2020.12.04.20242115). TCDD is known as the most potent xenobiotic, which bioaccumulates and has estimation half-life in humans of up to 10 yr. Due to hydrophobic character (Log P octanol/water 7.05), TCDD partitions into inflammatory lipids in lung tissue thus augmenting its local concentration. Population-based epidemiological data on SARS-CoV-2 first wave of pandemic revealed high level of CMV seropositivity and cumulative mortality rate 4.5 times in Lombardi region of Italy, where after Seveso industrial accident TCDD plasma level in pre-exposed subjects is 15 times the level in rest of Italy (doi. org/10.3389/fpubh.2020.620416). Also, Arctic Native (AN) peoples consume dioxin-contaminated fat in seafood and have TCDD DBB, i.e. 7 times that in general population. To the point of this paper, their COVID-19 mortality is 2.2 times of that among non-AN Alaskans (doi 10.15585/mmwr.mm6949a3). Conclusion(s) TCDD in the picomolar range may trigger CMV expression in lung cells and commit virus to the lytic cycle, which can be applied to reactivation of Herpesviridae infection in immunocompetent patients with COVID-19 ARDS syndrome.Copyright © 2023 The American Society for Biochemistry and Molecular Biology, Inc.