Carbohydrate-binding proteins fill in gaps in immune defenses
Our bodies produce a family of proteins that recognize and kill bacteria whose carbohydrate coatings resemble those of our own cells too closely, scientists have discovered.
Called galectins, these proteins recognize carbohydrates from a broad range of disease-causing bacteria, and could potentially be deployed as antibiotics to treat certain infections. The results are scheduled for publication in Nature Chemical Biology.
Researchers at Emory University School of Medicine made the discovery with the aid of glass slides coated with an array of over 300 different glycans (carbohydrates found on the surfaces of cells) derived from bacteria, many of which are found in the intestine. One can think of these slides – called microbial glycan microarrays – as wardrobes displaying a variety of clothes worn by gut bacteria.
"Many microbes cover themselves with glycans that somewhat resemble our own cells," says Richard D. Cummings, PhD, professor and chair of the Department of Biochemistry at Emory University School of Medicine. "That limits how well the immune system can use antibodies to respond to those microbes."
To prevent auto-immune attack, our bodies usually don't make antibodies against molecules found on our own cells. That leaves gaps in our defenses that bacteria could exploit. Several of those gaps are filled by galectins, the researchers found.
The discovery expands upon an initial finding, published in Nature Medicine in 2010, describing galectins that recognize and kill bacteria that express the human blood group B antigen.
The Emory researchers collaborated with the laboratory of James C. Paulson, PhD, at the Scripps Research Institute (TSRI). Co-first authors of the paper are Sean Stowell, MD/PhD (a resident in in laboratory and transfusion medicine at Emory), Connie Arthur, PhD (postdoctoral fellow at Emory with Stowell), and research assistant Ryan McBride at TSRI.
In contrast to antibodies, the galectins kill the bacteria directly, without needing other parts of the immune system to pile on. The researchers identified several varieties of bacteria (Pseudomonas aeruginosa, Providencia alcalifaciens, Klebsiella pneumoniae, and Serratia marcescens, for example) targeted for killing by galectins. In some cases, only certain strains of a given bacteria were vulnerable, because only those strains carried the target glycan.
"These studies have opened the way to understanding the ways in which adaptive or antibody-based factors work together with innate or galectin-based factors to give us immunity against a broad range of microbes," Cummings says.
In addition, the microarray technology provides tools to study glycan-binding antibodies and galectins in populations, he says.
"These studies use tiny amounts of blood – just a few drops – and show how glycan microarrays could supersede previous technology," he says. "Using these tools, investigators could identify developmental- and age-specific differences in anti-microbial glycan antibodies in humans, which may predict susceptibility to disease."
Quinn Eastman | Eurek Alert!
Fish Oil-Diet Benefits May be Mediated by Gut Microbes
28.08.2015 | University of Gothenburg
Bio-fabrication of Artificial Blood Vessels with Laser Light
28.08.2015 | Fraunhofer-Institut für Lasertechnik ILT
A University of Oklahoma astrophysicist and his Chinese collaborator have found two supermassive black holes in Markarian 231, the nearest quasar to Earth, using observations from NASA's Hubble Space Telescope.
The discovery of two supermassive black holes--one larger one and a second, smaller one--are evidence of a binary black hole and suggests that supermassive...
A team of European researchers have developed a model to simulate the impact of tsunamis generated by earthquakes and applied it to the Eastern Mediterranean. The results show how tsunami waves could hit and inundate coastal areas in southern Italy and Greece. The study is published today (27 August) in Ocean Science, an open access journal of the European Geosciences Union (EGU).
Though not as frequent as in the Pacific and Indian oceans, tsunamis also occur in the Mediterranean, mainly due to earthquakes generated when the African...
In mountainous regions earthquakes often cause strong landslides, which can be exacerbated by heavy rain. However, after an initial increase, the frequency of these mass wasting events, often enormous and dangerous, declines, in fact independently of meteorological events and aftershocks.
These new findings are presented by a German-Franco-Japanese team of geoscientists in the current issue of the journal Geology, under the lead of the GFZ...
Bacteria do not cease to amaze us with their survival strategies. A research team from the University of Basel's Biozentrum has now discovered how bacteria enter a sleep mode using a so-called FIC toxin. In the current issue of “Cell Reports”, the scientists describe the mechanism of action and also explain why their discovery provides new insights into the evolution of pathogens.
For many poisons there are antidotes which neutralize their toxic effect. Toxin-antitoxin systems in bacteria work in a similar manner: As long as a cell...
It comes when called, bringing care utensils with it and recording how they are used: Fraunhofer IPA is developing an intelligent care cart that provides care staff with physical and informational support in their day-to-day work. The scientists at Fraunhofer IPA have now completed a first prototype. In doing so, they are continuing in their efforts to improve working conditions in the care sector and are developing solutions designed to address the challenges of demographic change.
Technical assistance systems can improve the difficult working conditions in residential nursing homes and hospitals by helping the staff in their work and...
20.08.2015 | Event News
20.08.2015 | Event News
19.08.2015 | Event News
28.08.2015 | Physics and Astronomy
28.08.2015 | Health and Medicine
28.08.2015 | Life Sciences