Researchers from the University of Basel in Switzerland have clarified the role of the enzyme MPO. In fighting infections, this enzyme, which gives pus its greenish color, produces a highly aggressive acid that can kill pathogens without damaging the surrounding tissue. The findings, published in the current issue of Nature Microbiology, may provide new approaches for immunity strengthening therapies.
In the human body’s fight against bacterial pathogens, white blood cells are in the front line. They identify and ingest the invaders, and render them harmless using highly toxic substances. It is important that these substances only destroy bacteria but cause as little collateral damage as possible to the surrounding tissue.
The research groups headed by Prof. Dirk Bumann from the Biozentrum and Dr. Nina Khanna from the Department of Biomedicine at the University and the University Hospital Basel discovered how white blood cells solve this difficult task.
The enzyme myeloperoxidase (MPO) attaches directly to the surface of the bacterium where it produces an extremely aggressive acid. The acid reacts instantly in the immediate environment, burning a hole into the bacterial cell envelope which kills the bacterium. In combating bacterial infections, the enzyme acts like a sniper: Equipped with highly explosive ammunition, it targets extremely precisely, without causing collateral damage to their surroundings.
The function of MPO – the greenish color in pus
White blood cells fight bacterial invaders by producing hydrogen peroxide – a toxic substance, which is generally known for its use in bleaching hair. The enzyme MPO then converts hydrogen peroxide into hypochlorous acid. This acid, which is highly aggressive, immediately reacts on the surface of the bacteria and kills the invader. “Bacteria are helpless against this acid bomb,” explains Dirk Bumann. “As hypochloric acid is so highly reactive, the bomb reacts immediately with the closest biomolecules. It is ignited locally and does not spread to the wider surroundings. The bacteria die and the surrounding tissue is spared.” These findings enabled the research team to elucidate the precise function of the enzyme MPO, which is responsible for the greenish color seen in pus.
Long-term effects of collateral damage have not been sufficiently investigated
In their study, the researchers also investigated cells from humans who lack the enzyme MPO due to a genetic defect. This defect affects around one in 5000 people, making it quite rare. In these individuals, the hydrogen peroxide is not converted into hypochlorous acid and accumulates until it leaks out into the blood cells as well as the surrounding tissue. “The bacteria are still killed even without MPO. However, not only the bacteria but also the blood cells and their surroundings are damaged,” explains Bumann. “The collateral damage of blood cells and tissues without MPO may cause long-term consequences such as accelerated aging and cancer, but this has not yet been systematically investigated,” adds Nina Khanna.
MPO – an enzyme with two faces
“As we are confronted by fewer infections today than in the past when MPO evolved, the collateral damage issue and its control by MPO might play less important roles,” says Khanna. On the other hand, it may be possible to develop new treatment strategies to fight bacterial infections, which support the immune response by strengthening the MPO mechanism. “Currently, only drugs that do the opposite and inhibit MPO are being developed. The reason is that MPO can have negative effects in the case of heart disease,” points out Dirk Bumann. However, if such MPO inhibitors were used broadly, patients with infections might suffer.
Nura Schürmann, Pascal Forrer, Olivier Casse, Jiagui Li, Boas Felmy, Anne-Valérie Burgener, Nikolaus Ehrenfeuchter, Wolf-Dietrich Hardt, Mike Recher, Christoph Hess, Astrid Tschan-Plessl, Nina Khanna, Dirk Bumann
Myeloperoxidase targets oxidative host attacks to Salmonella and prevents collateral tissue damage
Nature Microbiology (2017), doi: 10.1038/nmicrobiol.2016.268
Prof. Dr. Dirk Bumann, University of Basel, Biozentrum, Tel. +41 61 207 23 82, Email: firstname.lastname@example.org
Heike Sacher, University of Basel, Biozentrum, Communications, Tel. +41 61 207 14 49, Email: email@example.com
Heike Sacher | Universität Basel
O2 stable hydrogenases for applications
23.07.2018 | Max-Planck-Institut für Chemische Energiekonversion
Scientists uncover the role of a protein in production & survival of myelin-forming cells
19.07.2018 | Advanced Science Research Center, GC/CUNY
A new manufacturing technique uses a process similar to newspaper printing to form smoother and more flexible metals for making ultrafast electronic devices.
The low-cost process, developed by Purdue University researchers, combines tools already used in industry for manufacturing metals on a large scale, but uses...
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
23.07.2018 | Materials Sciences
23.07.2018 | Information Technology
23.07.2018 | Health and Medicine