We talk a lot about vaccines these days, and for good reason. But it’s easy to forget that, even in the excitement swirling around COVD-19 vaccine development, other bio-medical research is quietly also being conducted in our nation’s cleanrooms and laboratories. So we’re going to take a mini ‘Pandemic Pause’ today and shift the focus of discussion away from coronavirus and towards an intriguing topic that we came across recently: antibiotics. Wait! Before you consider scrolling past, this is not a story about old-style antibiotics: this is truly next gen. They’re antibiotics with therapeutic superpowers; broad spectrum antibiotics that can go head to head with the most resistant of bacterial infections and come out fighting. What are they? Let’s pose a couple of questions: what is the link between polypeptides, reptile blood, and Sharon Stone? And what on earth is happening at George Mason University? Curious? Grab a coffee…it’s time to dive in!
This year has seen some challenges and changes, it must be admitted. Legions of us are working from home offices, newly aware how much we owe to those ‘essential workers’ who make our safety possible. Many of us have discovered novel passions or re-discovered old ones to help pass the time in quarantine or shelter-in-place. And still others of us, mindful of our emotional health, have turned to animal companions to counter the loneliness of prolonged isolation. Cats, dogs, the occasional alpaca perhaps (we mean, have you seen those faces?) have found their way from shelters to sofas (maybe not the alpacas…) and these relationships can serve both sides well. But what about reptiles? Is anyone opening their home to snakes and lizards for companionship? Maybe, but one place they’re certainly putting out the welcome mat is at the research laboratories of George Mason University (GMU). That said, this red carpet treatment is reserved, almost exclusively, for Varanus komodoensis, also known as Komodo dragons.
According to an article published in LabRoots, a social networking site that ‘emphasizes digital innovation in scientific collaboration and learning,’ Komodo dragons are indeed the newest star of the bio-med research field.(1) Native to Indonesia, Komodos are a type of monitor lizard that typically grows to around 154 pounds (70 kilograms) in weight. According to the Smithsonian’s National Zoo and Conservation Biology Institute in Washington, D.C., however, the largest ‘verified specimen reached a length of 10.3 feet (3.13 meters) and weighed 366 pounds (166 kilograms).’(2) At this size, with a face like a brewing storm and a glower rarely seen outside of a severe Monday morning hangover, this lizard is not one to be tangled with. Dragons feed on surprisingly large prey – goats, wild boars and deer are favorites but will also embrace a distinctly cannibalistic side, should the opportunity arise. In terms of self-defense (if indeed a 300lb+, scaly, venomous, and curiously fleet of foot reptile requires actual strategies), dragons can not only throw up the contents of their stomachs to gain an advantage but also survive extensive blood loss, even the amputation of a limb, relatively unscathed.
And that’s indeed the genesis of this creature’s Very Important Predator status – at least with researchers working to open up a field of next generation antibiotic development. The fact that V. komodoensis is able to survive major trauma without succumbing to sepsis is a characteristic prompts questions about its biochemistry. According to an article in The Telegraph, the reptile is not exactly known for its fastidious hygiene habits. In addition to comfortably tolerating less than sanitary living conditions, ‘Komodo dragon’s mouths are also teeming with more than 80 strains of bacteria, some of which cause blood poisoning or sepsis in bitten humans and animals, but the dragon itself is not affected – suggesting they have some sort of immunity.’(3)
Of course, this should hardly come as a surprise given the animal’s ancient evolutionary tenure but it does pose the question: What biochemical/immunological property is responsible for such broad spectrum immune defense? At GMU, Monique Van Hoek, associate director of research at the School of Systems Biology, aims to answer exactly that question and has pivoted from her earlier research into the blood properties of the American alligator (Alligator mississippiensis) to that of the V. komodoensis. A paper published in 2017, ‘Cathelicidin antimicrobial peptide from Alligator mississippiensis has antibacterial activity against multi-drug resistant Acinetobacter baumanii and Klebsiella pneumoniae,’ details Van Hoek’s work discovering that alligator serum has ‘antibacterial activity beyond that of human serum [which is believed to be] partially due to cationic antimicrobial peptides (CAMPs)’(4) These polypeptides – chains of amino acids linked by peptide bonds – are integral to some animals’ immune system and may offer a clue to future treatments against otherwise resistant bacterial infections. Van Hoek’s work used Basic Local Alignment Search Tool (BLAST) alignment to discover the cathelicidin and analyze it in comparison to the polypeptides of other reptiles. During the course of this initial project, it was discovered that the material exhibited ‘strong activity against multiple Gram-negative bacteria, including clinical isolates of multi-drug resistant (MDR) Acinetobacter baumannii and carbapenem-resistant Klebsiella pneumoniae. [Moreover] it was found that these peptides permeabilize the bacterial membrane and are less sensitive to salt inhibition than many other known CAMPs.’(5)
But would the same mechanism of membrane penetration be detrimental to host cells? Not according to Van Hoek: ‘The alligator cathelicidin peptides were not hemolytic against sheep red blood cells at 300 μg/ml and were not significantly cytotoxic against A549 human lung epithelial cells after 24 h exposure in 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assays.’(6) The bottom line in terms of the American alligator tests? ‘[D]ue to their activities against MDR bacteria and lack of cytotoxicity, [the] peptides could be an attractive platform for further development as a potential therapeutic.’(7)
And this potential therapeutic use could be even stronger in blood plasma of the Komodo dragon. While Van Hoek et al had already established that a synthetic version of reptilian blood – DRGN-1 – promoted the healing of Pseudomonas aeruginosa- and Staphylococcus aureus– (MRSA) infected wounds in rodent test subjects, the next phase of her research went a step further. Published in the Journal of Medical Microbiology, ‘Komodo-dragon cathelicidin-inspired peptides are antibacterial against carbapenem-resistant Klebsiella pneumoniae’ described a methodology that included a characterization of the ‘abilities of these peptides to disrupt the hyperpolarization of the bacterial membrane as well as their ability to form pores in the membrane’ of the virulent pathogen than causes severe pneumonia.(8) This new serum, termed DRGN-6, demonstrated ‘significant antibacterial activity against Carbapenem-resistant Klebsiella pneumoniae (CRKP), as good as colistin, a known antibiotic, indicating that with further modification, this peptide is promising for future development.’(9) We’ll watch this with great interest.
In terms of laboratories, we can’t be completely sure about the specifics that are being used to research the antibiotic potential of dragon blood, but we can be sure that cleanrooms and other contamination controlled environments play a major part. According to its own literature, GMU’s Neural Engineering Laboratory offers ‘two fully outfitted wet labs comprising 700 sq feet with chemical hoods, dedicated electrophysiology, chemical solution preparation, and electrochemistry workstations. In addition, between the two laboratories is a shared 200 sq ft cell culture facility which is fully operational.’(10) The site lists all available equipment, highlights of which include an Omniplex multichannel data acquisition system, a Digidata/pCLAMP data acquisition system, a Axopatch 200 patch clamp amplifier, and a PatchStar Micromanipulator is also at hand. In addition, researchers have access to two multichannel electrochemical stations, dual stack CO2incubators, laminar flow biosafety cabinet, freezer with temperatures as low as -80°C, a centrifuge, an in vitro microelectrode array system, inverted microscopes equipped for fluorescence immunohistochemistry, and a trinocular inverted microscope for cell culture use. And finally: ‘Neural Engineering Laboratory personnel make use of the Georgetown Nanoscience and Microtechnology Laboratory (GNuLab) […] a Class 1000 cleanroom which provides access to a range of material characterization tools including a scanning electron microscope (Zeiss SUPRA55-VP) and stylus film thickness profilometer (Dektak 3030).’(11)
It’s hard not to feel some significant gear envy over here.
So is it safe to assume that all of this equipment is in service to discovering treatment options for just one bacterial infection? Absolutely not. According to Van Hoek’s article, K. pneumoniae, a Gram-negative rod-shaped bacterium of the family Enterobacteriaceae, ‘has been associated with a range of human diseases, including urinary tract infections, bacteremia and pneumonia, both in community and hospital-associated infections.’(12) Furthermore, enterobacter species form part of the ‘ESKAPE family of pathogens, a group of bacteria that are responsible for the majority of nosocomial infections (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumanni, Pseudomonas aeruginosa and Enterobacter species) [and] many strains of ESKAPE pathogens are multidrug resistant (MDR).’(13)
Once again we come back to the issue of drug resistance.
In a period when all attention is focused on combating viral contagion, it’s easy to overlook the ever-present threats from bacterial pathogens. But we do still face an impending crisis of antimicrobial resistance (AMR) and Van Hoek’s research with reptile polypeptides as therapeutics could prove to be both significant and timely. In October this year Dr. Timothy Jinks, Head of Drug Resistant Infections Priority Program at the Wellcome Trust, informed the World Health Summit that ‘while billions have been poured into the development of vaccines and treatments against Covid-19, the same sense of urgency has not seen with AMR.’ Moreover, Jinks described the business of antibiotic R&D as being in crisis: ‘The fact is that we do not have a system that is sustainable for supporting the discovery, invention, and development of the new antibiotics that we need as drug resistant infections are expanding throughout the world.’(14) While not receiving much media interest, Jinks’ warning is a pointed reminder that while the coronavirus currently enjoys the limelight of centerstage, in the wings legions of bacteria are quietly evolving and transforming, ready for the next act.
Act…play…theater…drama. OK, we threaded our way back to the link with Sharon Stone. You didn’t think we’d forget, did you? According to several sources, the actor – perhaps better remembered for her fatal attraction to lagomorphs (ahem) – is not so brave when it comes to reptiles. Having spotted a Komodo dragon sauntering along her Beverly Hills street, she tweeted a video of a truly enormous specimen, eventually removed by Animal Control Services.(15) And, unlikely as this all sounds, it was not Stone’s first rodeo when it comes to such dangerous encounters. In a private tour of the Los Angeles zoo in 2001, Stone’s then-husband Phil Bronstein was mauled by what the zoo described as a relatively tame resident. Following surgery ‘to reattach severed tendons and rebuild the casing of his big toe,’ Bronstein was treated with pain medications and a course of antibiotics, albeit presumably not one based upon dragon blood research. And the fate of the attacker? ‘The 4-year-old dragon was unscathed in the incident.’(16)
Reptiles:1 and Rabbits: 0.
Reptilian blood and antibiotics – are you surprised by the link? How do you see the future of this research? We’d love to know your thoughts!