When the body senses an infection, one of the first lines of defense is to send immune molecules called host-derived antimicrobial peptides (AMPs) to target and kill bacteria. However, bacteria have learned to resist AMPs through a series of countermeasures such as remodeling their outer membrane surface to be less permeable. Nontypeable Haemophilus influenzae (NTHI) is such a bacterium.
NTHI resides in the human upper airway, typically without causing any harm. However, NTHI has the ability to change from a non-harmful bacterium to a disease causing pathogen, responsible for pink eye, sinusitis, middle ear infection and complications of cystic fibrosis. "When transitioning to a harmful pathogen, NTHI defends against increased production of AMPs by using the Sap, which stands for sensitivity to antimicrobial peptides, proteins to arm against attack, " said Kevin M. Mason, PhD, principal investigator in the Center for Microbial Pathogenesis at The Research Institute at Nationwide Children's Hospital and lead study author. "Yet, it's unclear just how the Sap transporter complex provides protection against AMPs."
To help explain the mechanisms that NTHI uses to protect itself from AMPs, Dr. Mason's team examined an animal model of middle ear infection. They had previously shown that NTHI bacteria lacking the protein SapA were susceptible to AMP attack. In the study, they describe the Sap transporter system that recognizes and transports host immune defense molecules into the bacterial cell. This system is necessary for the bacteria to survive in the host.
"It seems that NTHI senses the presence of these immune molecules, steals them from the host and arms itself to protect against future attacks," said Dr. Mason. "NTHI imports AMPs into the bacterial cell and then degrades them in the interior of the cell. By remodeling its membranes, the bacterium appears as already attacked, which protects it from being bothered by additional AMPs. Basically, transporting AMPs acts as a counter strategy to evade innate immune defense and ultimately benefits the bacterium nutritionally." This study provides the first direct evidence that the protein SapA contributes to bacterial survival by providing protection from AMPs in the host.
Dr. Mason says that targeting the Sap transport system may provide a way to use AMP derivatives as alternatives to antibiotics to treat NTHI infections. "Our long-range goal is to block this uptake system and starve the bacterium of essential nutrients. If we could develop a small molecule inhibitor that could block binding and transport, we could render NTHI susceptible to immune attack, while preserving the body's normal bacteria that are often disrupted by conventional antibiotic use."
For more information about Dr. Kevin Mason, visit http://www.nationwidechildrens.org/kevin-mason
For more information about the Center for Microbial Pathogenesis, visit http://www.nationwidechildrens.org/microbial-pathogens
Erin Pope | EurekAlert!
New photocatalyst speeds up the conversion of carbon dioxide into chemical resources
29.05.2017 | DGIST (Daegu Gyeongbuk Institute of Science and Technology)
Copper hydroxide nanoparticles provide protection against toxic oxygen radicals in cigarette smoke
29.05.2017 | Johannes Gutenberg-Universität Mainz
The world's highest gain high power laser amplifier - by many orders of magnitude - has been developed in research led at the University of Strathclyde.
The researchers demonstrated the feasibility of using plasma to amplify short laser pulses of picojoule-level energy up to 100 millijoules, which is a 'gain'...
Staphylococcus aureus is a feared pathogen (MRSA, multi-resistant S. aureus) due to frequent resistances against many antibiotics, especially in hospital infections. Researchers at the Paul-Ehrlich-Institut have identified immunological processes that prevent a successful immune response directed against the pathogenic agent. The delivery of bacterial proteins with RNA adjuvant or messenger RNA (mRNA) into immune cells allows the re-direction of the immune response towards an active defense against S. aureus. This could be of significant importance for the development of an effective vaccine. PLOS Pathogens has published these research results online on 25 May 2017.
Staphylococcus aureus (S. aureus) is a bacterium that colonizes by far more than half of the skin and the mucosa of adults, usually without causing infections....
Physicists from the University of Würzburg are capable of generating identical looking single light particles at the push of a button. Two new studies now demonstrate the potential this method holds.
The quantum computer has fuelled the imagination of scientists for decades: It is based on fundamentally different phenomena than a conventional computer....
An international team of physicists has monitored the scattering behaviour of electrons in a non-conducting material in real-time. Their insights could be beneficial for radiotherapy.
We can refer to electrons in non-conducting materials as ‘sluggish’. Typically, they remain fixed in a location, deep inside an atomic composite. It is hence...
Two-dimensional magnetic structures are regarded as a promising material for new types of data storage, since the magnetic properties of individual molecular building blocks can be investigated and modified. For the first time, researchers have now produced a wafer-thin ferrimagnet, in which molecules with different magnetic centers arrange themselves on a gold surface to form a checkerboard pattern. Scientists at the Swiss Nanoscience Institute at the University of Basel and the Paul Scherrer Institute published their findings in the journal Nature Communications.
Ferrimagnets are composed of two centers which are magnetized at different strengths and point in opposing directions. Two-dimensional, quasi-flat ferrimagnets...
24.05.2017 | Event News
23.05.2017 | Event News
22.05.2017 | Event News
29.05.2017 | Earth Sciences
29.05.2017 | Life Sciences
29.05.2017 | Physics and Astronomy