Understanding COVID-19 through adverse outcome pathways - 2nd CIAO AOP Design Workshop.

The CIAO project (Modelling the Pathogenesis of COVID-19 using the Adverse Outcome Pathway framework) aims at a holistic assembly of knowledge to deliver a truly transdisciplinary description of the entire COVID-19 physiopathology starting with the initial contact with the SARS-CoV-2 virus and ending with one or several adverse outcomes, e.g., respiratory failure. On 27-28 January 2021, a group of 50+ scientists from numerous organizations around the world met in the 2nd CIAO AOP Design Workshop to discuss the depiction of the COVID-19 disease process as a series of key events (KEs) in a network of AOPs. During the workshop, 74 such KEs forming 13 AOPs were identified, covering COVID-19 manifestations that affect the respiratory, neurological, liver, cardiovascular, kidney and gastrointestinal systems. Modulating factors influencing the course and severity of the disease were also addressed, as was a possible extension of the investigations beyond purely biological phenomena. The workshop ended with the creation of seven working groups, which will further elaborate on the AOPs to be presented and discussed in the 3rd CIAO workshop on 28-29 April 2021.

Prioritization of Contaminants of Emerging Concern in Wastewater Treatment Plant Discharges Using Chemical:Gene Interactions in Caged Fish.

We examined whether contaminants present in surface waters could be prioritized for further assessment by linking the presence of specific chemicals to gene expression changes in exposed fish. Fathead minnows were deployed in cages for 2, 4, or 8 days at three locations near two different wastewater treatment plant discharge sites in the Saint Louis Bay, Duluth, MN and one upstream reference site. The biological impact of 51 chemicals detected in the surface water of 133 targeted chemicals was determined using biochemical endpoints, exposure activity ratios for biological and estrogenic responses, known chemical:gene interactions from biological pathways and knowledge bases, and analysis of the covariance of ovary gene expression with surface water chemistry. Thirty-two chemicals were significantly linked by covariance with expressed genes. No estrogenic impact on biochemical endpoints was observed in male or female minnows. However, bisphenol A (BPA) was identified by chemical:gene covariation as the most impactful estrogenic chemical across all exposure sites. This was consistent with identification of estrogenic effects on gene expression, high BPA exposure activity ratios across all test sites, and historical analysis of the study area. Gene expression analysis also indicated the presence of nontargeted chemicals including chemotherapeutics consistent with a local hospital waste stream. Overall impacts on gene expression appeared to be related to changes in treatment plant function during rain events. This approach appears useful in examining the impacts of complex mixtures on fish and offers a potential route in linking chemical exposure to adverse outcomes that may reduce population sustainability.

Tracheal occlusion modulates the gene expression profile of the medial thalamus in anesthetized rats.

Conscious awareness of breathing requires the activation of higher brain centers and is believed to be a neural gated process. The thalamus could be responsible for the gating of respiratory sensory information to the cortex. It was reasoned that if the thalamus is the neural gate, then tracheal obstructions will modulate the gene expression profile of the thalamus. Anesthetized rats were instrumented with an inflatable cuff sutured around the trachea. The cuff was inflated to obstruct 2-4 breaths, then deflated for a minimum of 15 breaths. Obstructions were repeated for 10 min followed by immediate dissection of the medial thalamus. Following the occlusion protocol, 588 genes were found to be altered (P < 0.05; log(2) fold change ≥ 0.4), with 327 genes downregulated and 261 genes upregulated. A significant upregulation of the serotonin HTR2A receptor and significant downregulation of the dopamine DRD1 receptor genes were found. A pathway analysis was performed that targeted serotonin and dopamine receptor pathways. The mitogen-activated protein kinase 1 (MAPK1) gene was significantly downregulated. MAPK1 is an inhibitory regulator of HTR2A and facilitatory regulator for DRD1. Downregulation of MAPK1 may be related to the significant upregulation of HTR2A and downregulation of DRD1, suggesting an interaction in the medial thalamus serotonin-dopamine pathway elicited by airway obstruction. These results demonstrate an immediate change in gene expression in thalamic arousal, fear, anxiety motivation-related serotonin and dopamine receptors in response to airway obstruction. The results support the hypothesis that the thalamus is a component in the respiratory mechanosensory neural pathway.

Expression signatures for a model androgen and antiandrogen in the fathead minnow (Pimephales promelas) ovary.

Trenbolone, an anabolic androgen, and flutamide, an antiandrogen, are prototypical model compounds for agonism and antagonism of the androgen receptor. We hypothesized that 48 h exposures of female fathead minnows (Pimephales promelas) to environmentally relevant concentrations of these chemicals would alter genes regulated by the androgen receptor and that a mixture of the two compounds would block the effects. Gene expression in the ovaries was analyzed using a fathead minnow-specific 22,000-gene microarray. Flutamide altered abouttwicethe number of genes astrenbolone, most of which appeared to be through pathways not associated with the androgen receptor. A group of 70 genes, of which we could identify 37, were reciprocally regulated by trenbolone and flutamide. These are candidates for specific biomarkers for androgen receptor mediated gene expression. Four genes stand out as specifically related to reproduction: sperm associated antigen 8 (SPAG8), CASP8 and FADD-like apoptosis regulator (CFLAR), corticotropin releasing hormone (CRH), and 3beta-hydroxysteroid dehydrogenases (3beta-HSD). Three notable transcriptional regulators including myelocytomatosis viral oncogene homologue (MYC), Yin Yang 1 (YY1), and interferon regulator factor 1 (IRF1) may function as early molecular switches to control phenotypic changes in ovary tissue architecture and function in response to androgen or antiandrogen exposure.