For Salmonella and many other disease-causing bacteria that find their way into our bodies, infection begins with a poke. That’s because these bad bugs are equipped with a needle-like protein filament that punctures the outer membrane of human cells and then, like a syringe, injects dozens of toxic proteins that help them replicate.
Cammie Lesser at Massachusetts General Hospital and Harvard Medical School, Cambridge, and her colleagues are now on a mission to bioengineer strains of bacteria that don’t cause disease to make these same syringes, called type III secretion systems. The goal is to use such “good” bacteria to deliver therapeutic molecules, rather than toxins, to human cells. Their first target is the gastrointestinal tract, where they hope to knock out hard-to-beat bacterial infections or to relieve the chronic inflammation that comes with inflammatory bowel disease (IBD).
Tags: antibodies, bacteria, bacterial toxins, bioengineering, digestion, drug delivery, drug delivery vehicles, E. coli, Escherichia coli, gastrointestinal tract, IBD, inflammation, inflammatory bowel disease, intestine, microbiology, NIH Director’s 2016 Transformative Research Award, probiotics, secretion system, Shigella, single-domain antibodies, synthetic biology, technology, type III secretion systems
Caption: This “spooky” video ends with a scientific image of intestinal crypts (blue and green) plus organoids made from cultured crypt stem cells (pink).
As Halloween approaches, some of you might be thinking about cueing up the old TV series “Tales from the Crypt” and diving into its Vault of Horror for a few hours. But today I’d like to share the story of a quite different and not nearly so scary kind of crypt: the crypts of Lieberkühn, more commonly called intestinal crypts.
This confocal micrograph depicts a row of such crypts (marked in blue and green) lining a mouse colon. In mice, as well as in humans, the intestines contain millions of crypts, each of which has about a half-dozen stem cells at its base that are capable of regenerating the various types of tissues that make up these tiny glands. What makes my tale of the crypt particularly interesting are the oval structures (pink), which are organoids that have been engineered from cultured crypt stem cells and then transplanted into a mouse model. If you look at the organoids closely, you’ll see Paneth cells (aqua blue), which are immune cells that support the stem cells and protect the intestines from bacterial invasion.
A winner in the 2016 “Image Awards” at the Koch Institute Public Galleries, Massachusetts Institute of Technology (MIT), Cambridge, this image was snapped by Jatin Roper, a physician-scientist in the lab of Omer Yilmaz, with the help of his MIT collaborator Tuomas Tammela. Roper and his colleagues have been making crypt organoids for a few years by placing the stem cells in a special 3D chamber, where they are bathed with the right protein growth factors at the right time to spur them to differentiate into the various types of cells found in a crypt.
Once the organoids are developmentally complete, Roper can inject them into mice and watch them take up residence. Then he can begin planning experiments.
For example, Roper’s group is now considering using the organoids to examine how high-fat and low-calorie diets affect intestinal function in mice. Another possibility is to use similar organoids to monitor the effect of aging on the colon or to test which of a wide array of targeted therapies might work best for a particular individual with colon cancer.
Video: Gut Reaction (Jatin Roper)
Jatin Roper (Tufts Medical Center, Boston)
Omer Yilmaz (Massachusetts Institute of Technology, Cambridge)
NIH Support: National Cancer Institute; National Institute on Aging
Tags: art, BioArt, colon, colon cancer, crypts, crypts of Lieberkühn, diet, high-fat diet, intestinal crypts, intestine, low-calorie diet, organoids, Paneth cells, stem cells, The Koch Institute Galleries
Recently, we humans have started to pay a lot more attention to the legions of bacteria that live on and in our bodies because of research that’s shown us the many important roles they play in everything from how we efficiently metabolize food to how well we fend off disease. And, as it turns out, bacteria may not be the only interior bugs with the power to influence our biology positively—a new study suggests that an entirely different kingdom of primarily single-celled microbes, called protists, may be in on the act.
In a study published in the journal Cell, an NIH-funded research team reports that it has identified a new protozoan, called Tritrichomonas musculis (T. mu), living inside the gut of laboratory mice. That sounds bad—but actually this little wriggler was potentially providing a positive benefit to the mice. Not only did T. mu appear to boost the animals’ immune systems, it spared them from the severe intestinal infection that typically occurs after eating food contaminated with toxic Salmonella bacteria. While it’s not yet clear if protists exist that can produce similar beneficial effects in humans, there is evidence that a close relative of T. mu frequently resides in the intestines of people around the world.
Tags: B, bacteria, Colombia, Dientamoeba fragilis, food poisoning, Giardia, global health, gut, IBD, immunology, intestinal infection, intestine, irritable bowel syndrome, mice, microbe, microbiology, microbiome, parasite, protist, protozoan, Salmonella, Salmonella typhimurium, T. mu, Toxoplasma gondii, Tritrichomonas musculis