Researchers advance understanding in immune response to infections

July 16, 2014

University of Leicester researchers have released evidence substantiating an unexpected dual role of an important component of the immune system.

Findings by researchers at the University's Department of Infection, Immunity and Inflammation – including three PhD graduates – are published in a paper for the journal 'Medical Microbiology and Immunology'.

The paper presents significant new findings about the protein properdin – an important part of the . It is a positive regulator in the alternative pathway of complement activation – which means it plays a key part in one of the body's main techniques for tackling infections and foreign bodies known as antigens.

The new findings show that in some situations a lack of properdin can actually have major benefits – while in others it can be a big disadvantage.

Using mouse models, the researchers investigated the differences in immune responses between individuals deficient in properdin and those with normal amounts of the protein.

When individuals were infected with Streptococcus pneumoniae - bacteria which can cause sepsis and pneumonia in humans – those deficient in properdin had higher survival rates than those with normal levels.

But when individuals were infected with Listeria monocytogenes – which cause an infection called listeriosis in humans – those deficient in properdin had lower levels of survival.

Cellular analysis by the researchers suggests that properdin-deficiency is likely to cause the body to use more of a type of white blood cell known as M2 macrophages – involved in tissue repair – rather than M1 macrophages, whose main role is to kill pathogens.

This allowed the researchers to conclude that properdin controls the strength of the body's by affecting the role of macrophages during infection and inflammation.

Principal investigator and corresponding author, Dr Cordula Stover, Senior Lecturer in Immunology at the University's Department of Infection, Immunity and Inflammation, said: "The PhD graduates' projects together elucidate a critically instructive role of an innate immune protein, complement properdin, in shaping the inflammatory response.

"The work is the first to show that complement properdin controls the strength of immune responses by affecting humoral as well as cellular phenotypes during acute bacterial infection and ensuing ."

Dr Stover also stresses that using mouse models can be very useful for understanding disease mechanisms – but there are limitations with the value of mouse models.

She said: "We are asking mice to react to human pathogens or diseases of significance for man, not mouse. Mice are genetically homogenous, unlike man, and have comparable, not identical, scope of cells and antibodies.

"To be meaningful, disease concepts need to be tested in patient samples, in order to have direct application of the research."

Explore further: Instant immune booster dramatically improves outcome of bacterial meningitis and pneumonia

More information: The complete paper is available online: link.springer.com/article/10.1 … leAuthor/onlineFirst

Related Stories

Instant immune booster dramatically improves outcome of bacterial meningitis and pneumonia

March 24, 2014
A breakthrough study from University of Leicester shows low dose injections of artificial properdin provides substantial protection against septic diseases in mice.

Bacterial respiratory tract colonization prior to catching the flu may protect against severe illness

July 10, 2014
Many studies have shown that more severe illness and even death are likely to result if you develop a secondary respiratory infection after developing influenza. Now, however, a team of researchers based at The Wistar Institute ...

Molecule regulates production of antibacterial agent used by immune cells

June 20, 2014
Researchers have discovered how a protein molecule in immune cells promotes the production of nitric oxide, a potent weapon in the cells' arsenal to defend the body from bacterial attack. The protein may offer a target for ...

Scientists discover immune system component that resists sepsis in mice

July 9, 2014
Molecular microbiologists from the Keck School of Medicine of the University of Southern California (USC) have discovered that mice lacking a specific component of the immune system are completely resistant to sepsis, a potentially ...

On the link between periodontitis and atherosclerosis

July 10, 2014
Chronic oral infection with the periodontal disease pathogen, Porphyromonas gingivalis, not only causes local inflammation of the gums leading to tooth loss but also is associated with an increased risk of atherosclerosis. ...

Recommended for you

Genetic immune deficiency could hold key to severe childhood infections

July 18, 2017
A gene mutation making young children extremely vulnerable to common viruses may represent a new type of immunodeficiency, according to a University of Queensland researcher.

What are the best ways to diagnose and manage asthma?

July 18, 2017
What are the best ways to diagnose and manage asthma in adults? This can be tricky because asthma can stem from several causes and treatment often depends on what is triggering the asthma.

Large multi-ethnic study identifies many new genetic markers for lupus

July 17, 2017
Scientists from an international consortium have identified a large number of new genetic markers that predispose individuals to lupus.

Study finds molecular explanation for struggles of obese asthmatics

July 17, 2017
A large, bouquet-shaped molecule called surfactant protein A, or SP-A, may explain why obese asthma patients have harder-to-treat symptoms than their lean and overweight counterparts, according to a new study led by scientists ...

Team identifies potential cause for lupus

July 14, 2017
Leading rheumatologist and Feinstein Institute for Medical Research Professor Betty Diamond, MD, may have identified a protein as a cause for the adverse reaction of the immune system in patients suffering from lupus. A better ...

Immunosuppression underlies resistance to anti-angiogenic therapy

July 14, 2017
A Massachusetts General Hospital (MGH) research team has identified a novel mechanism behind resistance to angiogenesis inhibitors - drugs that fight cancer by suppressing the formation of new blood vessels. In their report ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.