Hookworms are often associated with malodorous gastrointestinal infections in humans. But now, scientists are turning this bad reputation around as they’ve found proteins secreted by the hookworm may alleviate asthma symptoms.
Human infections by the wriggly, squirmy parasites are pretty common, especially in developing parts of the world with poor sanitation. It’s estimated that nearly 3 billion people are infected with the large roundworm, the hookworm or the whipworm.
But what do worms have to do with good human health? As it turns out, in some instances, scientists have found that humans can be unaffected by the worm infections (commensalism relationship), or even benefited by the worms (symbiotic relationship). In the latter case, researchers found that purposely infecting patients with certain hookworms appeared to have bolstered their immune system.
The notion that a parasite can actually challenge the immune system in a good way comes from scientists observing, paradoxically, more autoimmune diseases with less pathogen. This is known as the Hygiene Hypothesis, and it suggests that sterile-like environments and limited exposure to bacteria and allergens could cause the immune system to be overly sensitive. This idea could explain, in part, why the prevalence of allergies is increasing worldwide in developed countries.
But while whole hookworms are being tested in clinical trials, researchers also found that certain hookworm proteins
may do the trick for asthma.
“We found that you don’t need the whole parasite to see protection against inflammation. The products that they secrete in their spit [are] where all the protective properties lie,” said Severine Navarro, an immunologist at James Cook University, and the study’s first author.
Specifically, hookworms secrete an anti-inflammatory protein, known as AIP-2. These dampen the pro-inflammatory responses in the body, which in turn, lessens asthma reactions like coughing and wheezing.
In mouse studies, injecting a “soup” of AIP-2 proteins was enough to nearly reverse asthma symptoms. At the molecular level, the lung functions and breathing were markedly improved while proteins normally involved with the inflammatory process were decreased.
In humans, AIP-2 seemed to also prevent inflammatory responses for people exposed to dust mite through the skin prick test.
Navarro is hopeful to turn AIP-2 into a pill form to help people with asthmas and other allergies. According to the team, the pill would circumvent the “ick factor” along with the risks associated with infecting live worms into patients, while still reaping the benefits of this notorious parasite.
Additional sources: Popular Science