Nav: Home

How upregulation of a single gene by SARS-CoV-2 can result in a cytokine storm

June 29, 2020

Amsterdam NL, June 29, 2020 - The SARS-CoV-19 virus initially has a limited capability to invade, attacking only one intracellular genetic target, the aryl hydrocarbon receptors (AhRs). Yet it leads to widely diverse clinical symptoms, suggesting multiple pathogenic mechanisms. Writing in Restorative Neurology and Neuroscience, investigators describe how excessive activation of AhRs via the IDO1-kynurenine-AhR signaling pathway, which is used by many pathogens to establish infection, leads to "Systemic AhR Activation Syndrome" (SAAS). The authors also hypothesize that therapies targeting downregulation of AhRs and IDO1 genes should decrease severity of infection.

SAAS underlies inflammation, thromboembolism, and fibrosis that may lead to severe disease and death from COVID-19. When corona virus (CoV) infection persists, it activates IDO1 by massively releasing cytokines. This in turn perpetuates the already extensive viral activation of AhRs, and the self-limiting control mechanisms of the host immune response may derail, triggering the cytokine storm underlying the most severe symptoms of COVID-19.

"The SARS-CoV-19 virus is a living example of viral simplicity complicated by extreme target complexity," explains lead author Waldemar A. Turski, MD, PhD, Department of Experimental and Clinical Pharmacology, Medical University in Lublin, Poland. "Direct activation of AhRs by CoVs may lead to diverse sets of phenotypic disease pictures, depending on time after infection, overall state of health, hormonal balance, age, gender, comorbidities, but also diet and environmental factors modulating AhRs."

The authors demonstrate that CoVs are perfect viruses leaving nothing to chance and show how difficult it is to stop them after cell invasion. They describe how many of the features and symptoms of COVID-19 may be dependent on AhR activation, including thromboembolism, fibrosis, multiple organ injury, and brain damage. They also explore how environmental factors, such as urban dust and diesel fumes, may activate AhRs and make humans more prone to pathogens, including CoV. However, physical exercise plays a positive role in IDO1 function and downregulates AhRs.

The investigators hypothesize that when AhRs remain activated and clinical symptoms are mild, eliminating factors known to increase AhR activation or implementing factors known to suppress AhR activation should decrease the severity of infection. When the disease is fully established and symptoms are severe, IDO1 is believed to be continuously activated in addition to the CoV activation of AhRs. "Such a vicious cycle can only be efficiently interrupted by simultaneous downregulation of both AhR and IDO1. There is currently, however, no licensed medication specifically and simultaneously downregulating the activity of both AhR and IDO1," notes co-author Les Turski, MD, PhD, German Center for Neurodegenerative Diseases, Bonn, Germany.

Co-author Artur Wnorowski, PhD, Department of Biopharmacy, Faculty of Pharmacy, Medical University in Lublin, Poland, undertook an intriguing challenge that yielded surprising results. "I analyzed major databases to identify chemicals that downregulate both AhR and IDO1, or AhR gene expression. I selected 596 molecules and an in-depth analysis of 23,526 experiments involving these molecules identified either a single molecule that repeatedly reduced AhR and IDO1 or AhR gene expression in human cells."

The molecules were dexamethasone for AhR and IDO1, and calcitriol, the active form of vitamin D, which is also known to inhibit the spread of other viral infections, for the AhR gene. Likewise, tocopherol, a form of Vitamin E, might downregulate IDO1 and is known to play a positive role in response to viral infections and inflammation in aging. The authors call for epidemiological studies and prospective trials to determine if calcitriol and tocopherol supplementation should be recommended for the prevention of SARS-CoV-2 infections.

"Our concept is based on 40 years of research experience with the metabolism of tryptophan. Activation of IDO1 in immune cells leads to release of kynurenine, a tryptophan metabolite, activates AhR. IDO1 was the clue that brought us to the AhR-IDO1 axis concept and exposed the role that AhR may play in the pathogenesis of COVID-19," says Dr. Waldemar Turski.

The Editor-in-Chief of Restorative Neurology and Neuroscience, Professor Bernhard Sabel from the University of Magdeburg, Germany, in recognition of novelty of the authors' vision says: "The turning point defined by the authors' concepts requires critical review of our habits, our relationships with the environment, and our education and research in the context of AhR modulation. We seem to be at the very beginning of novel discovery pathways and only see the very tip of an iceberg of unknown size that may critically affect our future."

Because the authors are reporting on changes in gene expression only, their hypotheses need to be tested before claiming that there are benefits of any therapy in modulating the SARs-CoV-2 infection. Randomized controlled trials and large observational studies are needed.
-end-


IOS Press

Related Neuroscience Articles:

Researchers rebuild the bridge between neuroscience and artificial intelligence
In an article in the journal Scientific Reports, researchers reveal that they have successfully rebuilt the bridge between experimental neuroscience and advanced artificial intelligence learning algorithms.
The evolution of neuroscience as a research
When the first issue of the JDR was published, the field of neuroscience did not exist but over subsequent decades neuroscience has emerged as a scientific field that has particular relevance to dentistry.
Diabetes-Alzheimer's link explored at Neuroscience 2019
Surprising links exist between diabetes and Alzheimer's disease, and researchers are beginning to unpack the pathology that connects the two.
Organoid research revealed at Neuroscience 2019
Mini-brains, also called organoids, may offer breakthroughs in clinical research by allowing scientists to study human brain cells without a human subject.
The neuroscience of autism: New clues for how condition begins
UNC School of Medicine scientists found that a gene mutation linked to autism normally works to organize the scaffolding of brain cells called radial progenitors necessary for the orderly formation of the brain.
Harnessing reliability for neuroscience research
Neuroscientists are amassing the large-scale datasets needed to study individual differences and identify biomarkers.
Blue Brain solves a century-old neuroscience problem
In a front-cover paper published in Cerebral Cortex, EPFL's Blue Brain Project, a Swiss Brain Research Initiative, explains how the shapes of neurons can be classified using mathematical methods from the field of algebraic topology.
Characterizing pig hippocampus could improve translational neuroscience
Researchers have taken further steps toward developing a superior animal model of neurological conditions such as traumatic brain injury and epilepsy, according to a study of miniature pigs published in eNeuro.
The neuroscience of human vocal pitch
Among primates, humans are uniquely able to consciously control the pitch of their voices, making it possible to hit high notes in singing or stress a word in a sentence to convey meaning.
Study tackles neuroscience claims to have disproved 'free will'
For several decades, some researchers have argued that neuroscience studies prove human actions are driven by external stimuli -- that the brain is reactive and free will is an illusion.
More Neuroscience News and Neuroscience Current Events

Trending Science News

Current Coronavirus (COVID-19) News

Top Science Podcasts

We have hand picked the top science podcasts of 2020.
Now Playing: TED Radio Hour

Listen Again: The Power Of Spaces
How do spaces shape the human experience? In what ways do our rooms, homes, and buildings give us meaning and purpose? This hour, TED speakers explore the power of the spaces we make and inhabit. Guests include architect Michael Murphy, musician David Byrne, artist Es Devlin, and architect Siamak Hariri.
Now Playing: Science for the People

#576 Science Communication in Creative Places
When you think of science communication, you might think of TED talks or museum talks or video talks, or... people giving lectures. It's a lot of people talking. But there's more to sci comm than that. This week host Bethany Brookshire talks to three people who have looked at science communication in places you might not expect it. We'll speak with Mauna Dasari, a graduate student at Notre Dame, about making mammals into a March Madness match. We'll talk with Sarah Garner, director of the Pathologists Assistant Program at Tulane University School of Medicine, who takes pathology instruction out of...
Now Playing: Radiolab

What If?
There's plenty of speculation about what Donald Trump might do in the wake of the election. Would he dispute the results if he loses? Would he simply refuse to leave office, or even try to use the military to maintain control? Last summer, Rosa Brooks got together a team of experts and political operatives from both sides of the aisle to ask a slightly different question. Rather than arguing about whether he'd do those things, they dug into what exactly would happen if he did. Part war game part choose your own adventure, Rosa's Transition Integrity Project doesn't give us any predictions, and it isn't a referendum on Trump. Instead, it's a deeply illuminating stress test on our laws, our institutions, and on the commitment to democracy written into the constitution. This episode was reported by Bethel Habte, with help from Tracie Hunte, and produced by Bethel Habte. Jeremy Bloom provided original music. Support Radiolab by becoming a member today at Radiolab.org/donate.     You can read The Transition Integrity Project's report here.