How The Immune System invention Listeria & Other Bad Bacteria
Original category: Infectious Diseases / Bacteria / Viruses
Millions of "good" bacteria exist harmoniously on the skin and in the intestines of healthy people. When harmful bacteria attack, the immune system fights back by sending out white blood cells to destroy the disease-causing interlopers. But how do white blood cells know which bacteria are good and which are harmful?
Northwestern University Feinberg School of Medicine researchers studied one type of white blood cell known as a macrophage, which is among the immune system's first to detect and eliminate harmful bacteria. The research team, led by Christian Stehlik, John P. Gallagher Research Professor of Rheumatology at Feinberg, discovered that the protein NLRP7 serves as a "scout" in macrophage cells, identifying bacterial cell wall components in harmful gram-positive bacteria such as Staphylococcus aureus and Listeria monocytogenes.
The findings were published in the February 23 issue of the journal Immunity.
"NLRP7 is a novel intracellular pattern recognition receptor that specifically recognizes bacterial cell wall components, known as lipopeptides, in harmful bacteria," says Stehlik, who worked closely with collaborators Andrea Dorfleutner, research assistant professor of medicine at Feinberg, and Yon Rojanasakul, Robert C. Byrd Distinguished Professor and Benedum Distinguished Professor at West Virgina University. "We show that activation of NLRP7 is necessary for eradicating bacterial infections through the formation of protein complexes called inflammasomes, which enable the production of defense factors in immune cells."
Identifying the molecule was complicated, says Sonal Khare, postdoctoral fellow at Feinberg and first author on the research paper, because the family of proteins within macrophages is quite large. "There were 22 likely candidates. To determine which one of these proteins is able to recognize bacteria in macrophages, we had to remove each one of them," she says. Through process of elimination, the team identified NLRP7 as the required protein.
Stehlik says the finding is significant because it contributes to a better understanding of how bacteria such as Listeria and Staphylococcus are recognized by the immune system. Listeria is found in uncooked meats, vegetables, and fruits such as cantaloupes. In 2011, listeria was the cause of the deadliest food contamination outbreak in the U.S. in more than a decade. S. aureus infections are most commonly contracted in hospitals, and 500,000 patients acquire Staphylococcus infections annually in the U.S. Methicillin-resistant S. aureus, or MRSA, strains are highly resistant to commonly-used antibiotics.
Understanding how the immune system recognizes these deadly intruders could one day lead to novel treatment strategies to combat these infections.
"The next phase of research related to NLRP7 and inflammasomes is progressing," says Stehlik. "We are continuing the research to explore mechanisms behind how this NLRP7 inflammasome is formed. We want to know whether we can manipulate this process to make the response stronger. We also will be exploring the use of mouse models in this pathway to study this response in vivo."
Continue reading:
Listeriosis is an illness that arises from infection caused by eating food contaminated with the bacterium Listeria monocytogenes. Listeriosis has a very low incidence in humans. However, pregnant women are much more likely than the rest of the population to contract it. Infection in a pregnant woman can lead to early delivery, infection of the newborn, and death of the baby.
What is MRSA?
MRSA stands for methicillin-resistant Staphylococcus aureus. The term is used to describe a number of strains of the bacteria, Staphylococcus aureus, that are resistant to a number of antibiotics, including methicillin.
Staphylococcus aureus is a group of bacteria that live on the surface of people's skin and inside the nose. It is normally harmless: most people who are carrying it are totally unaware that they have it. In fact, it is thought that up to 30% of the general UK population carries these bacteria in their nose or on their skin.
The word antibiotic comes from the Greek anti meaning 'against' and bios meaning 'life' (a bacterium is a life form).' Antibiotics are also known as antibacterials, and they are drugs used to treat infections caused by bacteria. Bacteria are tiny organisms that can sometimes cause illness to humans and animals. The singular word for bacteria is bacterium.
Such illnesses as tuberculosis, salmonella, syphilis and some forms of meningitis are caused by bacteria. Some bacteria are not harmful, while others are good for us.
Before bacteria can multiply and cause symptoms our immune system can usually destroy them. We have special white blood cells that attack harmful bacteria. Even if symptoms do occur, our immune system can usually cope and fight off the infection. There are occasions, however, when it is all too much and our bodies need some help - from antibiotics.
The first antibiotic was penicillin. Such penicillin-related antibiotics as ampicillin, amoxicillin and benzylpenicilllin are widely used today to treat a variety of infections - these antibiotics have been around for a long time. There are several different types of modern antibiotics and they are only available with a doctor's prescription in industrialized countries.
Scientists are reporting use of a new technology for sifting through the world's largest remaining pool of potential antibiotics to discover two new antibiotics that work against deadly resistant microbes, including the "super bugs" known as MRSA. Their report appears in the Journal of the American Chemical Society.
Sean Brady and colleagues explain that an urgent need exists for new medications to cope with microbes that shrug off the most powerful traditional antibiotics. Methicillin-resistant Staphylococcus aureus (MRSA) infections, for instance, are resistant to most known antibiotics. MRSA strikes at least 280,000 people in the U.S. alone every year, and almost 20,000 of those patients die. The typical way of discovering new antibiotics involves identifying and growing new bacteria from soil and other environmental samples in culture dishes in the laboratory. That environmental treasure-trove is the largest remaining potential source of new antibiotics. Researchers then analyze the bacteria to see if they make substances that could be used as antibiotics to kill other microbes. But most bacteria found in nature can't grow in the laboratory. That's why Brady and colleagues took a new approach to this problem.
The researchers removed DNA from soil bacteria that wouldn't grow in the lab. Then, they put this DNA into different bacteria that do grow well in culture dishes, and these bacteria acted like incubators for the new DNA. The approach enabled Brady's team to study the substances made by the soil bacteria's DNA in the lab. With this "metagenomics" method, they identified two new possible antibiotics called fasamycin A and fasamycin B that killed MRSA and vancomycin-resistant Enterococcus faecalis, which also is becoming more resistant to known antibiotics. They also determined how the new antibiotics work. "Metagenomics has the potential to access large numbers of previously inaccessible natural antibiotics," say the researchers.
Original category: Infectious Diseases / Bacteria / Viruses
Millions of "good" bacteria exist harmoniously on the skin and in the intestines of healthy people. When harmful bacteria attack, the immune system fights back by sending out white blood cells to destroy the disease-causing interlopers. But how do white blood cells know which bacteria are good and which are harmful?
Northwestern University Feinberg School of Medicine researchers studied one type of white blood cell known as a macrophage, which is among the immune system's first to detect and eliminate harmful bacteria. The research team, led by Christian Stehlik, John P. Gallagher Research Professor of Rheumatology at Feinberg, discovered that the protein NLRP7 serves as a "scout" in macrophage cells, identifying bacterial cell wall components in harmful gram-positive bacteria such as Staphylococcus aureus and Listeria monocytogenes.
The findings were published in the February 23 issue of the journal Immunity.
"NLRP7 is a novel intracellular pattern recognition receptor that specifically recognizes bacterial cell wall components, known as lipopeptides, in harmful bacteria," says Stehlik, who worked closely with collaborators Andrea Dorfleutner, research assistant professor of medicine at Feinberg, and Yon Rojanasakul, Robert C. Byrd Distinguished Professor and Benedum Distinguished Professor at West Virgina University. "We show that activation of NLRP7 is necessary for eradicating bacterial infections through the formation of protein complexes called inflammasomes, which enable the production of defense factors in immune cells."
Identifying the molecule was complicated, says Sonal Khare, postdoctoral fellow at Feinberg and first author on the research paper, because the family of proteins within macrophages is quite large. "There were 22 likely candidates. To determine which one of these proteins is able to recognize bacteria in macrophages, we had to remove each one of them," she says. Through process of elimination, the team identified NLRP7 as the required protein.
Stehlik says the finding is significant because it contributes to a better understanding of how bacteria such as Listeria and Staphylococcus are recognized by the immune system. Listeria is found in uncooked meats, vegetables, and fruits such as cantaloupes. In 2011, listeria was the cause of the deadliest food contamination outbreak in the U.S. in more than a decade. S. aureus infections are most commonly contracted in hospitals, and 500,000 patients acquire Staphylococcus infections annually in the U.S. Methicillin-resistant S. aureus, or MRSA, strains are highly resistant to commonly-used antibiotics.
Understanding how the immune system recognizes these deadly intruders could one day lead to novel treatment strategies to combat these infections.
"The next phase of research related to NLRP7 and inflammasomes is progressing," says Stehlik. "We are continuing the research to explore mechanisms behind how this NLRP7 inflammasome is formed. We want to know whether we can manipulate this process to make the response stronger. We also will be exploring the use of mouse models in this pathway to study this response in vivo."
Continue reading:
What Is Listeria Infection?
What is MRSA?
MRSA stands for methicillin-resistant Staphylococcus aureus. The term is used to describe a number of strains of the bacteria, Staphylococcus aureus, that are resistant to a number of antibiotics, including methicillin.
What is Staphylococcus aureus?
What Are Antibiotics?
Such illnesses as tuberculosis, salmonella, syphilis and some forms of meningitis are caused by bacteria. Some bacteria are not harmful, while others are good for us.
Before bacteria can multiply and cause symptoms our immune system can usually destroy them. We have special white blood cells that attack harmful bacteria. Even if symptoms do occur, our immune system can usually cope and fight off the infection. There are occasions, however, when it is all too much and our bodies need some help - from antibiotics.
The first antibiotic was penicillin. Such penicillin-related antibiotics as ampicillin, amoxicillin and benzylpenicilllin are widely used today to treat a variety of infections - these antibiotics have been around for a long time. There are several different types of modern antibiotics and they are only available with a doctor's prescription in industrialized countries.
The world's largest remaining pool of potential antibiotics to discover two new antibiotics
Original category: MRSA / Drug Resistance news.Scientists are reporting use of a new technology for sifting through the world's largest remaining pool of potential antibiotics to discover two new antibiotics that work against deadly resistant microbes, including the "super bugs" known as MRSA. Their report appears in the Journal of the American Chemical Society.
Sean Brady and colleagues explain that an urgent need exists for new medications to cope with microbes that shrug off the most powerful traditional antibiotics. Methicillin-resistant Staphylococcus aureus (MRSA) infections, for instance, are resistant to most known antibiotics. MRSA strikes at least 280,000 people in the U.S. alone every year, and almost 20,000 of those patients die. The typical way of discovering new antibiotics involves identifying and growing new bacteria from soil and other environmental samples in culture dishes in the laboratory. That environmental treasure-trove is the largest remaining potential source of new antibiotics. Researchers then analyze the bacteria to see if they make substances that could be used as antibiotics to kill other microbes. But most bacteria found in nature can't grow in the laboratory. That's why Brady and colleagues took a new approach to this problem.
The researchers removed DNA from soil bacteria that wouldn't grow in the lab. Then, they put this DNA into different bacteria that do grow well in culture dishes, and these bacteria acted like incubators for the new DNA. The approach enabled Brady's team to study the substances made by the soil bacteria's DNA in the lab. With this "metagenomics" method, they identified two new possible antibiotics called fasamycin A and fasamycin B that killed MRSA and vancomycin-resistant Enterococcus faecalis, which also is becoming more resistant to known antibiotics. They also determined how the new antibiotics work. "Metagenomics has the potential to access large numbers of previously inaccessible natural antibiotics," say the researchers.
Comments
Post a Comment