THC Can Treat Lung Inflammations in Mice, Study Says
THC, the psychoactive compound behind the cannabis high, may also be able to treat potentially deadly lung inflammations, according to new research.
Published in the British Journal of Pharmacology, the new study found that THC could relieve inflamed pathways in the lungs of lab mice, as well as benefit the bacteria living the rodents’ lungs and guts.
In the lungs
If a person’s lungs become inflamed following an infection, breathing can become a lot harder. As a consequence, many tissues can become starved of vital oxygen and the body can enter a deadly spiral of organ failure. This life-threatening condition is termed acute respiratory distress syndrome (ARDS).
Because of the coronavirus pandemic, cases of ARDS have become more prevalent in hospitals all over the world.
But as there are no drugs currently approved to act on ARDS by the US Food and Drug Administration, most cases in the US are primarily treated with breathing machines and antibiotics, should the infection be bacterial – which Covid-19 is not.
To investigate whether THC could be an effective therapeutic for ARDS, researchers at the University of South Carolina first induced the syndrome in lab mice by infecting the rodents with a toxin from Staphylococcus aureus bacteria. Each mouse was then given three doses of THC during the first 48 hours of the infection.
After analyzing the mice’s lung tissue and fecal matter, the researchers concluded that the cannabinoid had successfully reduced lung inflammation.
“Analysis demonstrated that THC could attenuate acute lung injury, reduce congestion and minimize [a blood clot protein] in mice with ARDS which was accompanied by a decrease in the infiltration of the immune cells in the lung tissues when compared to vehicle controls,” the researchers wrote.
So, what’s behind this anti-inflammatory effect? Well, the researchers believe it has something to do with the mice’s cytokines, the small proteins that coordinate an immune response and set off inflammation. If too many cytokines are released, the subsequent “cytokine storm” can trigger ARDS. But THC, the researchers say, can inhibit cytokine production, thus reducing unnecessary inflammation.
“Cytokine storm is a huge clinical issue which leads to multiorgan failure and often death,” Prakash Nagarkatti, vice president for research at the University of South Carolina and co-author of the study, said in a statement.
“We have been working on cannabinoids for over 20 years and found that cannabinoids such as THC are highly anti-inflammatory,” he added.
Prakash and his colleagues also found that THC boosted the proportion of beneficial bacteria found in the mice’s lungs – a biological change that could improve an infection response.
“The results demonstrated that THC could significantly increase the species of Ruminococcus gnavus, but significantly decrease the species of Akkermansia muciniphila systemically following [toxin] exposure,” the researchers wrote.
Ruminococcus gnavus helps to modulate the production of mucus in the lungs, which is key to managing infections. As such, R. gnavus could be considered beneficial bacteria. Akkermansia muciniphila is known to increase cytokine production in the colon, so a fall in the numbers of the bacteria could help reduce unnecessary inflammation.
A Covid connection?
As morbidity of ARDS has become more notable during the coronavirus pandemic, more attention has been given to new potential treatments. THC, the South Carolina researchers say, is one such promising treatment.
“Our studies raise the exciting suggestion to test THC against ARDS seen in Covid-19 patients,” Nagarkatti said in a statement.
But even if THC’s effects on Covid-19 are further investigated and trialed, it will likely be years before researchers come to a clinical consensus on its viability. And during such studies, new findings may make researchers question the value of THC’s anti-inflammatory effects.
As Kevin Hill, an associate professor of psychiatry at Harvard Medical School – who was not involved in the new THC study – wrote recently in Cannabis and Cannabinoid Research, “Cannabinoids could possibly be a part of a treatment regimen, with nonsteroidal anti-inflammatory drugs (NSAIDs) and other medications that target immune pathways, that could downregulate the cytokine storm.”
“[But] anti-inflammatory activity may not be an advantage when combating viruses because it may mitigate host immune responses to acute viral infections, leading to disease progression and possibly death.”