Cannabidiol has been shown to inhibit SARS-CoV-2 infection in human cells and mice

An interdisciplinary team of researchers from the University of Chicago has found evidence that cannabidiol (CBD), a product of the cannabis plant, can inhibit SARS-CoV-2 infection in human cells and in mice .

The study, published on January 20, 2022, in Scientists progress, found that CBD showed a significant negative association with positive SARS-CoV-2 tests in a nationwide sample of medical records of patients taking the FDA-approved drug for the treatment of epilepsy. Researchers now say clinical trials should be done to determine if CBD could possibly be used as a preventative or early treatment for COVID-19. They caution, however, that the COVID-blocking effects of CBD only come from a high-purity, specially formulated dose taken in specific situations. The study results do not suggest that consuming commercially available products with CBD additives that vary in potency and quality can prevent COVID-19.

Scientists have been searching for new therapies for people infected with the coronavirus and emerging variants, especially those without access to vaccines, as the pandemic continues across the country and the world and breakthrough infections become more common.

CBD: An unexpected avenue to fight COVID-19

The idea of ​​testing CBD as a potential therapeutic for COVID-19 was fortuitous. “CBD has anti-inflammatory effects, so we thought it might stop the second phase of COVID infection involving the immune system, the so-called ‘cytokine storm.’ Surprisingly, it directly inhibited viral replication in lung cells,” said Marsha Rosner, PhD, Charles B. Huggins Professor in the Ben May Department of Cancer Research and lead study author.

To see this effect, the researchers first treated human lung cells with a non-toxic dose of CBD for two hours before exposing the cells to SARS-CoV-2 and monitoring them for the virus and spike protein. viral. They found that above a certain concentration threshold, CBD inhibited the ability of the virus to replicate. Further investigation revealed that CBD had the same effect in two other cell types and for three SARS-CoV-2 variants in addition to the original strain.

CBD did not affect the ability of SARS-CoV-2 to enter the cell. Instead, CBD was effective in blocking replication early in the infection cycle and six hours after the virus had already infected the cell.

Like all viruses, SARS-CoV-2 affects the host cell by hijacking its gene expression machinery to produce more copies of itself and its viral proteins. This effect can be observed by tracking virus-induced changes in cellular RNAs. High concentrations of CBD almost completely eradicated the expression of viral RNAs. It was a completely unexpected result.

We just wanted to know if CBD would affect the immune system. No sane person would ever think it blocked viral replication, but it did.”

Marsha Rosner, PhD, Charles B. Huggins Professor in the Ben May Department of Cancer Research and lead study author

Researchers have shown that the mechanism by which CBD blocks SARS-CoV-2 replication involves CBD activating one of the host cell’s stress responses and generating interferon, an antiviral cellular protein. .

Real-world data: Patients who test positive for COVID-19 at lower rates

The researchers wanted scientific data to show that CBD prevents viral replication in live animals. The team showed pretreatment with CBD for a week prior to infection with suppressed SARS-CoV-2 infection in both lungs and nasal passages of mice. “These results provide major support for a clinical trial of CBD in humans,” Rosner said.

And CBD’s success hasn’t been limited to the lab: An analysis of 1,212 patients from the National COVID Cohort Collaborative found that patients taking a doctor-prescribed CBD oral solution for the treatment of epilepsy tested positive for COVID-19 at significantly lower rates than a sample of matched patients from similar demographic backgrounds who were not taking CBD.

CBD’s potential to treat patients recently exposed or infected with SARS-CoV-2 does not precede the first lines of defense against COVID-19, which include getting vaccinated and following existing public health guidelines for the masking in interior spaces and social distancing. But the published results offer a potential new therapeutic, something that is still needed as the pandemic rages on.

“A clinical trial is needed to determine if CBD is truly effective in preventing or suppressing SARS-CoV-2 infection, but we believe it may have potential as a prophylactic treatment,” Rosner said. “Maybe you’re in a hotspot or you think you’ve been exposed or you’ve just tested positive – that’s where we think CBD might have an effect.”

Not the CBD from your dispensary

The research team pointed out that the COVID-blocking effects of CBD were strictly limited to high purity and high concentrations of CBD. Closely related cannabinoids such as CBDA, CBDV, and THC, the enriched psychoactive element in marijuana plants, did not have the same potency. In fact, combining CBD with equal amounts of THC actually reduced the effectiveness of CBD.

“Going to your corner bakery and buying CBD muffins or gummy bears probably won’t do anything,” Rosner said. “The commercially available CBD powder we reviewed, which was commercially available and something you could order online, was sometimes surprisingly high in purity but also inconsistent in quality. to come in an oral solution that can be absorbed without the special FDA-approved formulation,” Rosner said.

Additionally, the use of CBD is not without potential risks. It appears to be extremely safe when consumed in food or drink, but methods of use such as vaping can have negative side effects, including potential heart and lung damage. It is also not well-studied in certain populations, such as pregnant women, and should therefore only be used under the supervision of a physician and with caution.

Although the study results are exciting, further study is needed to determine the precise dosage of CBD that is effective in preventing SARS-CoV-2 infection in humans as well as its safety profile and any potential side effects.

“We are very excited to see clinical trials on this topic start,” Rosner said. “Especially as we see that the pandemic is not yet close to an end – determining whether this generally safe, well-tolerated and non-psychoactive cannabinoid could have antiviral effects against COVID-19 is of critical importance. .”

Rosner was also thrilled that this research project was a case study in the power of scientific collaboration by bringing together a group of highly interdisciplinary researchers. The lead authors listed in the article came from three different research universities and departments as diverse as microbiology, molecular engineering, cancer biology and chemistry.

“It was really a team science effort, and that’s something that really excites me,” Rosner said. “From clinicians to David Meltzer’s group that did patient testing to virologists like Glenn Randall, and it goes on and on. That’s how science should be done.”


Journal reference:

Nguyen, LC, et al. (2021) Cannabidiol inhibits SARS-CoV-2 replication through induction of host ER stress and innate immune responses. Scientific advances.

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