Category: Immune System

Categories : Immune SystemTags : Leave a comment

Peacekeeper Cells Protect the Body from Autoimmunity During Infection

On By ModernMedia
Scanning electron microscope image of T regulatory cells (red) interacting with antigen-presenting cells (blue). T regulatory cells can suppress responses by T cells to maintain homeostasis in the immune system. Credit: National Institute of Allergy and Infectious Diseases/NIH

In the flurry of immune activity in an infection, immune cells need to be prevented from mistakenly attacking each other. New research from the University of Chicago shows how a specially trained population of immune cells keeps the peace by preventing other immune cells from attacking their own. The study, published in Science, provides a better understanding of immune regulation during infection and could provide a foundation for interventions to prevent or reverse autoimmune diseases.

Several groups of white blood cells help coordinate immune responses. Dendritic cells take up proteins from foreign pathogens, chop them up into peptides called antigens, and display them on their surface. CD4+ conventional T (Tconv) cells, or helper T cells, inspect the peptides presented by dendritic cells. If the peptides are foreign antigens, the T cells expand in numbers and transform into an activated state, specialized to eradicate the pathogen. If the dendritic cell is carrying a “self-peptide,” or peptides from the body’s own tissue, the T cells are supposed to lay off.

During an autoimmune response, the helper T cells don’t distinguish between foreign peptide antigens and self-peptides properly and go on the attack no matter what. To prevent this from happening, another group of T cells called CD4+ regulatory T (Treg) cells, are supposed to intervene and prevent friendly fire from the Tconv cells.

“You can think of them [Treg cells] as peacekeeper cells,” said Pete Savage, PhD, Professor of Pathology at UChicago and senior author of the new study. Tregs obviously do their job well most of the time, but Savage said that it has never been clear how they know when to intervene and prevent helper T cells from starting an autoimmune response, and when to hold back and let them fight an infection.

So, Savage and his team, led by David Klawon, PhD, a former graduate student in his lab who is now a postdoctoral fellow at the Massachusetts Institute of Technology (MIT), wanted to explore this property of the immune system, known in the field as self-nonself discrimination. T cells are produced in the thymus, a specialised organ of the immune system. During development, Treg cells are trained to recognise specific peptides, including self-peptides from the body. When dendritic cells present a self-peptide, the Treg cells trained to spot them intervene to stop helper T cells from getting triggered.

For the study, Savage and Klawon worked in close collaboration with co-first author Nicole Pagane, a graduate student at MIT, as well as co-corresponding authors Harikesh Wong at the Ragon Institute of the Massachusetts General Hospital, MIT and Harvard University, and Ron Germain at the National Institutes of Health.

T cell specificity is what the team found makes a crucial difference in self-nonself discrimination. The researchers experimentally depleted Treg cells in mice that were specific to a single self-peptide from the prostate. In healthy mice in the absence of infection, this change did not trigger autoimmunity to the prostate. When the researchers infected mice with a bacterium that expressed the prostate self-peptide, however, the absence of matched, prostate-specific Treg cells triggered prostate-reactive T helper cells and introduced autoimmunity to the prostate.

Interestingly though, this alteration did not impair the ability of helper T cells to control the bacterial infection by responding to foreign peptides.

“It’s like a doppelganger population of T cells. The CD4 helper cells that could induce disease by attacking the self share an equivalent, matched population of these peacekeeper Treg cells,” Savage said. “When we removed Treg cells reactive to a single self-peptide, the T helper cells reactive to that self-peptide were no longer controlled, and they induced autoimmunity.”

The root causes of autoimmune disease are a complex interaction of genetics, the environment, lifestyle, and the immune system. Classic, conventional thinking in the immunology field promoted the idea that the immune system establishes self-nonself discrimination by purging the body of helper T cells that are reactive to self-peptides, thereby preventing autoimmunity. Savage said this study shows that purging is inefficient though, and that specificity matching by Treg cells may be equally as important.

“The idea is that specificity matters, and for a fully healthy immune system, you need to have a good collection of these doppelganger Treg cells,” he said. As long as the immune system generates enough matched Treg cells, they can prevent autoimmune responses without impacting responses to infections.

“It’s like flipping the idea of self-nonself discrimination upside down. Instead of having to delete all helper T cells reactive to self-antigens, you simply generate enough of these Treg peacekeeper cells instead,” Savage said.

Source: University of Chicago

Categories : Dermatology Immune SystemTags :

New Study Identifies a Key Protein’s Role in Psoriasis

On By ModernMedia
Photo: CC0

A new study on psoriasis has determined that a protein called NF-kB c-Rel can intensify the condition’s symptoms when activated by signals from the body’s immune system. Understanding how “c-Rel” affects skin inflammation could lead to new treatments, said the researchers at Case Western Reserve University School of Medicine.

The study, published recently in eBioMedicine, examined how c-Rel contributes to the function of dendritic cells (DCs), a type of immune cell. The study examined how c-Rel responds to specific immunological signals through Toll Like Receptor 7 (TLR7), which regulates innate immunity and inflammation, exacerbating psoriasis.

The researchers also found the absence of c-Rel alleviates inflammation that causes red, scaly patches on the skin. TLR7 meanwhile is known to be activated by diseases such as HIV and HPV, which are also linked to the development psoriasis.

“We believe that by focusing on c-Rel and TLR7, scientists might be able to create more targeted treatments that reduce inflammation and help psoriasis symptoms,” said Parameswaran Ramakrishnan, associate professor of pathology, member of the Case Comprehensive Cancer Center and researcher at Louis Stokes Cleveland VA Medical Center, the study’s principal investigator.

“This may help relieve the discomfort millions of people live with skin inflammation.”

The researchers examined skin samples from psoriasis patients and a mouse model with similar skin changes.

They analysed c-Rel levels and its behaviour in specially engineered cells lacking the protein; they also examined the mouse model lacking c-Rel.

Their goal: to better understand how c-Rel impacts the immune response in psoriasis.

“Our research shows that c-Rel plays a major role in psoriasis inflammation,” said Angela Liu, lead author and a recent graduate of the School of Medicine’s pathology department.

“We saw higher levels of c-Rel in psoriasis; mice lacking c-Rel were significantly protected from developing psoriasis and showed less inflammation.”

Ramakrishnan said their study revealed the potential role for TLR7 and c-Rel signalling in human psoriasis. A range of viruses that activates TLR7, including human immunodeficiency virus (HIV), human papilloma virus (HPV) and hepatitis C virus (HCV), are linked to the development of psoriasis.

“The research warrants future studies on TLR7-c-Rel-dependent molecular mechanism regulating DC function as a potential link for how viral TLR7 activation is involved in worsening psoriatic disease,” Ramakrishnan said. “From a broad perspective, it would be interesting to further explore the role of c-Rel and TLR7 in other biologically relevant diseases involving these proteins, such as systemic lupus erythematosus and wound-healing in diabetes.”

Source: Case Western Reserve University

Categories : Dermatology Immune SystemTags :

Topical Mupirocin Reduces Cutaneous Lupus Inflammation

On By ModernMedia
A woman with Systemic Lupus Erythematosus. Source: Wikimedia CC0

Researchers have found that topical mupirocin is effective in reducing rashes caused by systemic lupus erythematosus. Instead of directly lowering inflammation, the treatment kills bacteria that promote it. The findings are published in Arthritis & Rheumatology.

Cutaneous lupus erythematosus is a common manifestation of systemic lupus erythematosus, caused by the autoimmune conditions. The condition is characterised by rashes on various parts of the body including the face and scalp, hair loss and scarring of the skin.

The standard treatment for cutaneous lupus erythematosus is using immunosuppressants and biologic drugs to reduce inflammation. While the medications can be helpful, many patients with systemic lupus erythematosus already take several drugs and are looking for alternatives to pills.

J. Michelle Kahlenberg, MD, PhD, a professor of internal medicine in the Division of Rheumatology at University of Michigan Health led a team of researchers investigating topical mupirocin which is one such alternatives.

This trial was based on Kahlenberg’s previous discovery that cutaneous lupus rashes are often colonised with a common skin bacteria, Staphyloccous areus, also known as staph, and contributes to inflammation in the rashes. Mupirocin kills this type of bacteria.

The study randomly selected systemic lupus erythematosus patients currently experiencing cutaneous lupus erythematosus flares to treat their skin lesions with mupirocin or with an inactive control, petrolatum jelly.

Samples from the nose and lesional skin were used to determine baseline and post treatment Staphylococcus abundance and microbial community profiles. Paired samples collected prior to treatment with the topical solution and seven days after treatment showed decreases in lesional staphylococcus aureus in the mupirocin treated samples.

Importantly, the reduction in staph also was accompanied by a reduction in inflammatory signals, including interferon-driven gene expression, in the lesions.

“In addition to decreasing the inflammation by decreasing lesional staphylococcus aureus, the mupirocin treatment also lowered skin monocyte levels, which are important in driving cutaneous lupus,” said Kahlenberg.

Mupirocin is a prescription treatment, and while this early study showed signs of decreasing inflammation, the study wasn’t designed to see if it can decrease the rash of cutaneous lupus erythematosus.

“Additional larger studies are needed to determine whether topical antibiotics will be helpful to make rashes go away,” Kahlenberg said.

“However, this is an exciting first step to show that there may be additional treatments that can improve inflammation beyond our usual immunosuppressant and biologic drugs.”

Source: Michigan Medicine – University of Michigan

Categories : Immune System Obstetrics & GynaecologyTags :

Pregnancy Enhances Natural Immunity to Block Severe Flu

On By ModernMedia
Photo by Anna Hecker on Unsplash

McGill University scientists have discovered that pregnancy may trigger a natural immunity to boost protection against severe flu infection. Contrary to the common belief that pregnancy increases vulnerability to infections, researchers found that it strengthened an immune defence in mice, blocking the Influenza A virus from spreading to the lungs, where it can cause severe infection.

“Our results are surprising because of the current dogma, but it makes sense from an evolutionary perspective,” said co-lead author Dr Maziar Divangahi, Professor in McGill’s Faculty of Medicine and Health Sciences and Senior Scientist at the Research Institute of the McGill University Health Centre (The Institute).

“A mother needs to stay healthy to protect her developing baby, so the immune system adapts to provide stronger defenses. This fascinating response in the nasal cavity is the body’s way of adding an extra layer of protection, which turns on during pregnancy.”

Exploring benefits for pregnancy and beyond

The researchers used a mouse model to observe how a certain type of immune cell activates in the nasal cavity of mice during pregnancy, producing a powerful molecule that boosts the body’s antiviral defenses, especially in the nose and upper airways.

“Influenza A virus remains among the deadliest threats to humanity,” said first author Julia Chronopoulos, who carried out the research while completing her PhD at McGill. “This natural immunity in pregnancy could change the way we think about flu protection for expectant mothers.”

The Public Health Agency of Canada recommends pregnant women and pregnant individuals get the flu vaccine, as they are at high risk of severe illness and complications like preterm birth. The new insights offer promise for more targeted vaccines for influenza, which is among the top 10 leading causes of death in Canada.

“The broader population could also benefit, as our findings suggest the immune response we observed could be replicated beyond pregnancy,” said co-lead author Dr James Martin, Professor in McGill’s Faculty of Medicine and Health Sciences and Senior Scientist at the RI-MUHC. This could mean new nasal vaccines or treatments that increase protective molecules, known as Interleukin-17.

The team’s next focus is on finding ways to reduce lung damage during viral infections like the flu or COVID. Rather than targeting the virus, as previous research has done, they aim to prevent dysregulated immune systems from overreacting, an approach that could lower the risk of serious complications associated with flu infection.

Source: McGill University

Categories : Immune SystemTags :

Immune ‘Brake’ Reveals Drug Targets for Cancer and Autoimmune Disease

On By ModernMedia
Killer T cells about to destroy a cancer cell. Credit: NIH

Researchers have discovered a genomic ‘brake’ in a subset of immune cells that could help advance immunotherapy for cancer and autoimmune disease. The findings, led by a team at the Peter MacCallum Cancer Centre in collaboration with researchers at the Garvan Institute and Kirby Institute, provide new insights into how the body’s immune defence mechanisms can go awry in these diseases and open a new class of potential drug targets that could activate immune cells in tumour tissue.

The research was published in the journal Immunity.

Discovering an immune brake

Specialised killer T cells are released during an infection, trained to recognise and destroy the threat. When unchecked, these cells can cause autoimmune diseases such as type 1 diabetes or rheumatoid arthritis if they mistakenly attack the body’s own healthy tissues.

The immune system employs a mechanism to prevent autoimmune attacks called ‘tolerance’ – a process that can be exploited by cancer cells to shield them from the body’s natural defences.

“Until now, it was not fully understood how tolerance works at a molecular level. We used advanced sequencing techniques to identify a unique genomic signature in ‘tolerant’ T cells that differentiated them from killer T cells that were activated in response to viral infection,” says Dr Timothy Peters, co-first author from Garvan.

“These precise genome locations have never before been observed and allowed us to track precisely how killer T cells progress through the tolerance pathway, and how specific gene networks enable tolerance to be abused.”

Breakthrough for cancer and autoimmune disease

Dr Ian Parish, who led the research at the Peter MacCallum Cancer Centre said this breakthrough helps to understand why cancer treatments fail and opens the door to developing new treatments in the future.

“Current cancer immunotherapy treatments target the exhaustion phase of the immune response,” he said. “Our research suggests that a second, earlier ‘off-switch’ called tolerance may explain how many cancers resist current immunotherapies by blocking anti-cancer immunity from getting off the ground. We’re excited as these findings can be exploited for new treatments. Our next step is to understand if we can disrupt tolerance and engage the immune system to restart and attack those cancers resistant to treatment.”

Professor Chris Goodnow, Head of the Immunogenomics Lab at Garvan, says this new understanding of T cell tolerance opens up opportunities to develop new drugs that could selectively alter this pathway.

“The discovery of these gene locations provides us with a roadmap for developing future drugs, which could block the tolerance mechanisms to boost cancer-killing ability for immunotherapies. Conversely, for autoimmune diseases, enhancing tolerance could prevent harmful autoimmune attack,” he says.

In next steps, the researchers will focus on understanding how to disrupt the tolerance mechanism and engage the immune system to restart.

“These findings have revealed around 100 new potential targets for drugs to target the tolerance mechanism in T cells, which have until now been largely developed by trial and error,” says Professor Goodnow. “This could lead to a whole new class of treatments for autoimmunity and cancer.”

Professor Chris Goodnow is The Bill and Patricia Ritchie Foundation Chair and Director of the Cellular Genomics Futures Institute, UNSW Sydney. Dr Tim Peters is a Conjoint Lecturer at St Vincent’s Clinical School, UNSW Medicine and Health.

Source: Garvan Institute of Medical Research

Categories : Cancer Immune SystemTags :

Chronic Activation of the Innate Immune System can Unleash Cancer

On By ModernMedia
Photo by Sangharsh Lohakare on Unsplash

Along with defending against pathogens, the body’s innate immune system helps to protect the stability of our genomes in unexpected ways that have important implications for the development of cancer, researchers at Memorial Sloan Kettering Cancer Center (MSK) are discovering.

In a pair of recent papers, scientists in the lab of molecular biologist John Petrini, PhD, showed that innate immune signaling plays a key role in maintaining genome stability during DNA replication. Furthermore, the researchers showed that chronic activation of these immune pathways can contribute to tumour development in a mouse model of breast cancer.

Not only do the findings add vital insights to our understanding of fundamental human biology, says Dr Petrini, they may also shed new light on tumour initiation and present potential opportunities for new therapies.

“Living organisms have evolved complex pathways to sense, signal, and repair damaged DNA,” he says. “Here we’re learning new things about the role of the innate immune system in responding to that damage – both in the context of cancer and also in human health more generally.”

How Chronic Activation of the Innate Immune System Can Lead to Cancer

The newest paper, led by first author Hexiao Wang, PhD, a postdoctoral fellow in the Petrini Lab, and published in Genes & Development, reveals a connection between innate immune signaling and tumour development in breast tissue. And, Dr Petrini says, the data suggest that when instability arises in the genome, chronic activation of the innate immune system can greatly increase the chances of developing cancer.

The study focused on a protein complex called the Mre11 complex, which plays a pivotal role in maintaining the stability of the genome by sensing and repairing double-strand breaks in DNA.

To study how problems with the Mre11 complex can lead to cancer, the team manipulated copies of the protein in mammary tissue organoids (miniature lab-grown model organs) and then implanted them into laboratory animals.

When oncogenes (genes known to drive cancer) were activated in these mice, tumors arose about 40% of the time, compared with about 5% in their normal counterparts. And the tumors in the mice with mutant Mre11 organoids were highly aggressive.

The research further showed that the mutant Mre11 led to higher activation of interferon-stimulated genes (ISGs). Interferons are signaling molecules that are released by cells in response to viral infections, immune responses, and other cellular stressors.

They also found that the normally tightly controlled packaging of DNA was improperly accessible in these organoids — making it more likely that genes will get expressed, when they otherwise would be inaccessible for transcription.

“We actually saw differences in the expression of more than 5600 genes between the two different groups of mice,” Dr Petrini says.

And strikingly, these profound effects depended on an immune sensor called IFI205.

When the organoids were further manipulated so they would lack IFI205, the packaging of DNA returned almost to normal, and the mice developed cancer at essentially the same rate as normal mice.

“So what we learned is that problems with Mre11 – which can be inherited or develop during life like other mutations – can create an environment where the activation of an oncogene is much more likely to lead to cancer,” Dr Petrini says. “And that the real lynch pin of this cascade is this innate immune sensor, IFI205, which detects that there’s a problem and starts sending out alarm signals. In other words, when problems with Mre11 occur, chronic activation of this innate immune signaling can significantly contribute to the development of cancer.”

New Understandings Could Pave the Way for Future Treatments

The work builds on a previous study, led by Christopher Wardlaw, PhD, a former senior scientist in the Petrini Lab, that appeared in Nature Communications.

That study focused on the role of the Mre11 complex in maintaining genomic integrity. It found that when the Mre11 complex is inactive or deficient, it results in the accumulation of DNA in the cytoplasm of cells and in the activation of innate immune signaling. This research primarily looked at the involvement of ISG15, a protein made by an interferon-stimulating gene, in protecting against replication stress and promoting genomic stability.

“Together, these studies shed new light on how the Mre11 complex works to protect the genome when cells replicate, and how, when it’s not working properly, it can trigger the innate immune system in ways that can promote cancer,” D. Petrini says.

By shedding light on the interrelationships between these complex systems and processes, the researchers hope to identify new strategies to prevent or treat cancer, he adds, such as finding ways to short-circuit the increased DNA accessibility when Mre11 isn’t working properly.

Source: Memorial Sloan Kettering Cancer Center

Categories : COVID Immune SystemTags :

SARS-CoV-2 Hijacks Three Key Proteins in the Complement System

On By ModernMedia
SARS-CoV-2 viruses (yellow) infecting a human cell (blue). Photo by CDC on Pexels

Researchers at the Medical University of Vienna and the Medical University of Innsbruck discovered that SARS-CoV-2 hijacks three important host proteins that dampen the activity of the complement system, a key component of early antiviral immunity. This significantly impairs viral clearance which may affect the course of both acute COVID infections and post-COVID sequelae. The study was recently published in the journal Emerging Microbes & Infections.

An early and effective immune response is crucial for resolving viral infections and preventing post-infectious complications. The complement system, a pivotal element of antiviral immunity, is a cascade of proteins found in the bloodstream and at mucosal sites, such as the respiratory tract. Activated through three different pathways, complement facilitates the clearance of virus particles by directly inducing their destruction (lysis). To prevent bystander damage to host cells, complement is rapidly inactivated by a set of host molecules referred to as complement regulatory proteins. The new study led by Anna Ohradanova-Repic and colleagues from the Center for Pathophysiology, Infectiology and Immunology at the Medical University of Vienna in collaboration with the team of Heribert Stoiber from the Institute of Virology at the Medical University of Innsbruck shows that SARS-CoV-2 hijacks three of these regulatory proteins, CD55, CD59 and Factor H, and thereby successfully shields itself from complement-mediated lysis.

Hijacking host proteins for effective complement resistance

By propagating SARS-CoV-2 in human cells the researchers discovered that the virus particles acquire the cellular proteins CD55 and CD59. Further experiments showed that SARS-CoV-2 also binds to Factor H, another complement regulatory protein that is primarily found in the bloodstream. Confronting the virus particles with active complement revealed that they are partially resistant to complement-mediated lysis. By removing CD55, CD59 and Factor H from the virus surface or inhibiting their biological functions, the researchers could successfully restore complement-mediated clearance of SARS-CoV-2.

“Through hijacking these three proteins, SARS-CoV-2 can evade all three complement pathways, resulting in reduced or delayed viral clearance by the infected host,” Anna Ohradanova-Repic, the leader of the study explains. Because complement is intricately linked with other components of the immune system, this not only affects virus elimination but can also cause significant inflammation, a core feature of both severe COVID-19 and Long COVID. “Uncovering immune evasion mechanisms that allow the virus to linger within the host for longer, deepen our understanding of the acute and long-term impacts of SARS-CoV-2 infection,” says first author Laura Gebetsberger.

Source: Medical University of Vienna

Categories : COVID Immune SystemTags :

New Discovery Explains How SARS-CoV-2 Evades Anti-viral Immunity

On By ModernMedia
Image by Fusion Medical on Unsplash

The novel coronavirus SARS-CoV-2 has an enzyme that can counteract a cell’s innate defence mechanism against viruses, explaining why it is more infectious than the previous SARS and MERS-causing viruses. This discovery, from Kobe University, may point the way to the development of more effective drugs against this and possibly similar, future diseases.

When a virus attacks, the body’s immune response has two basic layers of defence: the innate and the adaptive immune systems. While the adaptive immune system grows stronger against a specific pathogen as the body is exposed to it multiple times and which forms the basis of vaccinations, the innate immune system is an assortment of molecular mechanisms that work against a broad range of pathogens at a basic level. The Kobe University virologist SHOJI Ikuo says, “The new coronavirus, however, is so infectious that we wondered what clever mechanisms the virus employs to evade the innate immune system so effectively.”

Shoji’s team previously worked on the immune response to hepatitis viruses and investigated the role of a molecular tag called “ISG15” the innate immune system attaches to the virus’s building blocks. Having learned that the novel coronavirus has an enzyme that is especially effective in removing this tag, he decided to use his team’s expertise to elucidate the effect of the ISG15 tag on the coronavirus and the mechanism of the virus’s countermeasures.

In a paper in the Journal of Virology, the Kobe University-led team is now the first to report that the ISG15 tag gets attached to a specific location on the virus’s nucleocapsid protein, the scaffold that packages the pathogen’s genetic material. For the virus to assemble, many copies of the nucleocapsid protein need to attach to each other, but the ISG15 tag prevents this, which is the mechanism behind the tag’s antiviral action. “However, the novel coronavirus also has an enzyme that can remove the tags from its nucleocapsid, recovering its ability to assemble new viruses and thus overcoming the innate immune response,” explains Shoji.

The novel coronavirus shares many traits with the SARS and MERS viruses, which all belong to the same family of viruses – which also have an enzyme that can remove the ISG15 tag. But their versions are less efficient at it than the one in the novel coronavirus, Shoji’s team found. And in fact, it has been reported recently that the previous viruses’ enzymes have a different primary target. “These results suggest that the novel coronavirus is simply better at evading this aspect of the innate immune system’s defence mechanism, which explains why it is so infectious,” says Shoji.

But understanding just why the novel coronavirus is so effective also points the way to developing more effective treatments. The Kobe University researcher explains: “We may be able to develop new antiviral drugs if we can inhibit the function of the viral enzyme that removes the ISG15 tag. Future therapeutic strategies may also include antiviral agents that directly target the nucleocapsid protein, or a combination of these two approaches.”

Source: Kobe University

Categories : Immune System New Compounds and TreatmentsTags :

“Two for the Price of One” – New Process that Drives Anti-viral Immunity is Discovered

On By ModernMedia

Scientists at Trinity College Dublin have discovered a new process in the immune system that leads to the production of an important family of anti-viral proteins called interferons. They hope the discovery will now lead to new, effective therapies for people with some autoimmune and infectious diseases.

Reporting in Nature Metabolism, Luke O’Neill, Professor of Biochemistry in the School of Biochemistry and Immunology at Trinity, and his team have found that a natural metabolite called Itaconate can stimulate immune cells to make interferons by blocking an enzyme called SDH. 

Co-lead author, Shane O’Carroll, from Trinity’s School of Biochemistry and Immunology, said: “We have linked the enzyme SDH to the production of interferons in an immune cell type called the macrophage. We hope our work will help the effort to develop better strategies to fight viruses because interferons are major players in how our innate immune system eliminates viruses – including COVID-19.” 

Co-lead author, Christian Peace, from Trinity’s School of Biochemistry and Immunology, added: “Itaconate is a fascinating molecule made by macrophages during infections. It’s already known to suppress damaging inflammation but now we have found how it promotes anti-viral interferons.”

Working with drug companies Eli Lilly and Sitryx Ltd, the next step is to test new therapies  based on Itaconate in various diseases, with some autoimmune diseases and some infectious diseases on the likely list. And the work potentially extends to other disease contexts in which SDH is inhibited, such as cancer, and could reveal a new therapeutic target for SDH-deficient tumours.

Prof O’Neill said: “With Itaconate you get two for the price of one – not only can it block harmful inflammation, but it can also help fight infections. We have discovered important mechanisms for both and the hope now is that patients will benefit from new therapies that exploit Itaconate and its impacts.” 

Clinical trials in patients are set to start next year.  

Source: Trinity College Dublin

Categories : Immune SystemTags :

Rip and Tear: How a Key Immune Protein Defeats Bacterial Membranes

On By ModernMedia
Illustration of how GBP1 proteins (blue and purple) attach to the membrane of a bacterium (yellow), zoomed in from an image taken with an electron microscope (in grayscale). Credit: Delft University

The protein GBP1 is a vital immune system component which fights against bacteria and parasites by enveloping them in a protein coat, but how the substance manages to do this has remained unknown until now. Researchers from Delft University of Technology report in Nature Structural & Molecular Biology how this protein operates – ripping and tearing until the bacterial membrane is undone. Their findings could aid in the development of medications and therapies for individuals with weakened immune systems.

So-called Guanylate Binding Proteins (GBPs) play a crucial role in our innate immune system, explains biophysicist Arjen Jakobi: “GBPs form the first line of defence against various infectious diseases caused by bacteria and parasites. Examples of such diseases include dysentery, typhoid fever caused by Salmonella bacteria, and tuberculosis. The protein also plays a significant role in the sexually transmitted infection chlamydia as well as in toxoplasmosis, which is particularly dangerous during pregnancy and for unborn children.”

Coat around bacteria

In their publication, Jakobi and his colleagues describe for the first time how the innate immune system fights against bacteria using GBP1 proteins. “The protein surrounds bacteria by forming a sort of coat around them,” explains Tanja Kuhm, PhD candidate in Jakobi’s research group and the lead author of the article. “By pulling this coat tighter, it breaks the membrane of the bacteria – the protective layer surrounding the intruder – after which immune cells can clear the infection.”

Deciphering the defence strategy

To decode the defence strategy of GBPs, the researchers examined how GBP1 proteins bind to bacterial membranes using a cryogenic electron microscope. This allowed them to see the process in great detail down to the molecular level. Jakobi: “We were able to obtain a detailed three-dimensional image of how the protein coat forms. Together with biophysical experiments conducted in Sander Tans’ research group at research institute AMOLF, which enabled us to manipulate the system precisely, we succeeded in deciphering the mechanism of the antibacterial function.”

Medications

According to Jakobi, this research helps us understand better how our body is capable of combating bacterial infections. “If we can grasp this well, and we can specifically activate or deactivate the involved proteins through medication, it may offer opportunities to speed up getting rid of certain infections.”

Source: Delft University