This Spotlight feature explains how three critters could open new pathways in medical research.
Humans have always had a love-hate relationship with critters, which tend to fascinate and repulse us in equal measure.
One study published in 2017 and covered on Medical News Today found that humans' fear of creepy crawlies may be "stamped" into our brains and that we may have this mistrust of creatures, such as spiders, even in infancy.
Yet, insects, arachnids, and other critters also fascinate humans — perhaps because they are so very different from us. After all, butterflies can taste with their feet, spiders can "hear" through the little hairs on their legs, and a worm cut in half can regenerate the "tail" of its body.
Writers and other artists have been peering into the insect world for hundreds of years, in awe of what they found there.
The 18th-century poet and painter William Blake was so taken with minuscule creatures that he once, allegedly, thought he had seen the ghost of a flea in his dreams, which he then proceeded to paint.
Turn-of-the-century author, Franz Kafka, on the other hand, famously built on the disgust that many people experience when coming across bugs in their beloved homes by writing the story "The Metamorphosis."
In this tale, the main character, Gregor Samsa, wakes up one morning not feeling like himself. He has become "ungeheures Ungeziefer," which roughly translated from German means "scary pest" — a hair-raising insect.
But recent research suggests that critters are fascinating and worth studying not just because of their "otherworldliness" or ibecause of their relationship with humans and other species.
These minibeasts may actually have lots to teach and offer in the context of clinical research. In this Spotlight feature, we look at how three creepy crawlies may change the face of health and medical therapy.
1. Spiders may weave new treatments
Irritable bowel syndrome (IBS) refers to a coexisting group of gastrointestinal symptoms, including diarrhea and abdominal pain that can severely affect a person's quality of life. According to data published in 2014, approximately 11% of the world's population lives with IBS.
Spider venom could kickstart new therapies, while its silk may help researchers design better biomaterials.
In 2016, researchers from the University of Adelaide in Australia, Johns Hopkins University in Baltimore, MD, and other collaborating institutions found a new potential target for IBS-related pain treatment — in spider venom.
More specifically, the team found that the toxins produced by a species of tarantula, Heteroscodra maculate, were able to activate a protein (ion channel), NaV1.1 that is present in the intestinal nerves that send out pain signals.
The researchers believed that this discovery could lead to more targeted treatments for IBS pain. And indeed, in 2018, members of the initial team published a new study reporting that they had found a way of blocking the pain signal in mouse models of IBS.
Also in 2018, investigators from the University of Queensland and the Florey Institute of Neuroscience and Mental Health — both in Australia — zeroed in on the therapeutic properties of a peptide present in spider venom: Hm1a.
The team, led by Prof. Glenn King from University of Queensland, was able to use Hm1a to selectively activate NaV1.1 in mouse models of Dravet syndrome, a severe form of epilepsy. By doing so, the researchers were able to eliminate seizures in the mice they treated with the spider venom molecule.
"Spiders kill their prey through venom compounds that target the nervous system," notes study co-author Prof. Steven Petrou.
"Millions of years of evolution have refined spider venom to specifically target certain ion channels, without causing side effects on others, and drugs derived from spider venoms retain this accuracy," Prof. Petrou continues, arguing that his team's current findings could lead to more effective treatments for seizures in Dravet's syndrome.
The secrets and potential of spider silk
But spider venom is not the only focus in biomedical research. "Spider silks are the toughest biological material," says Jessica Garb, who is an associate professor in the Department of Biological Sciences at the University of Massachusetts Lowell.
"They are tougher than steel, yet weigh much less, and some spider silks can be stretched up to three times their length without breaking," she continues. For these reasons, Garbs and colleagues have been studying this incredibly thin and resilient material, aiming to find out what gives spider silk its strength and versatility.
In 2018, Garb and colleagues received a $335,000 grant from the National Science Foundation for their research on spider silk. By unlocking its secret, the investigators hope that they will be able to come up with a formula for next-generation biomaterials.
"For example, these materials could be used to improve helmets and body armor or other protective equipment, medical devices like prosthetics, bandages, and sutures, even sports gear."
2. Cockroaches: From pest to potion
The much-maligned cockroach also appears to be full of potential when it comes to aiding health research. Reports from last year indicate that in China, there are cockroach farms, in which entrepreneurs allow cockroaches to breed freely in a thoroughly sanitized environment.
Cockroach brains may have antibiotic properties.
However, the farm seals the fate of these poor critters. When they reach maturity, the "cockroach farmers" ground them into a paste that is supposed to help treat gastrointestinal problems.
This practice has its roots in ancient Chinese traditions that claim cockroaches can have a therapeutic use. But is this true?
According to preliminary research conducted in 2010 by investigators from the University of Nottingham in the United Kingdom, the brains of cockroaches and locusts contain no fewer than nine molecules that could kill potent, antibiotic-resistant bacteria. The investigators tested the American cockroach, as well as two different species of locusts.
"We hope that these molecules could eventually be developed into treatments for Escherichia coli and MRSA [methicillin-resistant Staphylococcus aureus] infections that are increasingly resistant to current drugs," notes Simon Lee, one of the researchers involved in this study.
"These new antibiotics could potentially provide alternatives to currently available drugs that may be effective but have serious and unwanted side effects," Lee argues.
What cockroach mothers can teach us
Cockroaches could also be our next great source of protein, according to a study featured in the International Union of Crystallography Journal in 2016. One species of cockroach, Diploptera punctata (the Pacific beetle cockroach), actually produces a form of milk to feed its live young.
This milk, researchers have found, forms protein crystals in the gut of the young. These crystals contain a high amount of protein, so high, in fact, that study co-author Subramanian Ramaswamy has referred to them as "a complete food."
Although the investigator has suggested that the cockroach milk could become a part of the novelty protein drinks arena, he has also admitted that the process would be challenging. Since it is not possible to milk the insects, researchers would have to find a way to produce the milk artificially.
D. punctata could also become the new animal model of preference for some aspects of clinical research, according to Emily Jennings and colleagues from the University of Cincinnati in Ohio.
Jennings has studied genetic markers of pregnant female D. punctata to understand what happens at various stages during the insect's pregnancy.
The new model, the researcher hopes, could have larger applications, and cockroaches could provide cheaper animals that are easier to work with than mammals, such as mice.
"We have over 1,000 cockroaches in a fairly small space, an enormous population compared to what you can keep with mice. The feeding regimen of the cockroaches is the cost of a large bag of dog food that can last for years," Jennings notes.
3. All the buzz about wasp venom
Many of us are terrified by wasps, mainly because of their seemingly random aggressive behavior, and because their sting can produce allergic reactions, which can range from mild swelling to full-blown anaphylaxis.
Wasp venom has surprising therapeutic potential against aggressive bacteria and even cancer.
But there is also a curative potential in their sting — at least according to a range of clinical studies conducted in the past few years. For instance, one study published in the journal Toxins in 2015 identified three peptides present in bee and wasp venoms, which, the authors, argue, have applications in biomedicine.
One of these peptides, mastoparan, is present in the venom of hornets, paper wasps, and social wasps. It has antimicrobial and anti-viral properties, among other types of therapeutic potential.
"Mastoparan alone or in combination with other antibiotics could be a promising alternative for combating multiple-antibiotic-resistant bacteria in clinical practice," the study authors write.
However, the researchers also warn that this peptide can be toxic to healthy tissue, attacking bacteria and surrounding cells alike. "Thus, the development of new strategies to reduce the toxic side effects of mastoparan, thereby improving the feasibility of clinical applications, are required," the study authors point out.
Another study, also from 2015, suggested that Polybia-MP1 — a mastoparan present in the venom of the social wasp Polybia paulista — was able to inhibit the proliferation of bladder and prostate cancer cells, as well as of drug-resistant leukemia cells.
The peptide does this by poking holes into the membranes of cancer cells, making them "leak" their molecular content.
Even more surprisingly, research from the University of California in Riverside — published last year in Biochemistry — identified a new class of wasp venom peptides, ampulexins, produced by Ampulex compressa (the emerald jewel wasp), which could open a new pathway for Parkinson's treatments.
The emerald jewel wasp is infamous — it stings cockroaches, first to paralyze them and then to "control" their brain so that the cockroaches become lethargic and easy to manipulate.
Ultimately, this allows the wasps to insert their eggs in the cockroaches' bodies so that when they hatch, the wasp larvae can use this as their first source of food.
As gruesome as this process is, it gave the University of California an important lead — the immobile state of the stung cockroaches is similar to some symptoms of Parkinson's disease.
Since ampulexins appear to be responsible for inducing the immobility, the investigators aim to study them in the hope that these will allow them to find a new cellular target for Parkinson's treatments.
This Spotlight feature may not have done much to alleviate your mistrust of tiny critters. However, after having read it, maybe next time you want to run away at the sight of a wasp or throw a slipper at a spider, you will think again and consider that the poor little minibeast may someday lead the way to the next great medical discovery.