Category: Micro-biology

New research identifying a 'brake' which limits spontaneous pain could lead to the development of new pain relief  treatments.

Spontaneous pain is ongoing and can occur constantly (slow burning pain) or intermittently (sharp shooting pain), with no obvious cause. Although they can be very debilitating, the mechanisms behind such conditions can be poorly understood and they are therefore difficult to treat. 

Continuous activity in small sensory nerve fibers, known as C-fiber nociceptors (pain neurons), has been shown to cause spontaneous burning pain, with greater activity resulting in greater pain.

Scientists at the University of Bristol discovered that the presence of a particular ion channel, TREK2, in the membranes of these neurons provides a natural innate protection against this pain.

Ion channels form pores through the neuronal membrane. Leak potassium channels, which are open most of the time, allow positive potassium ions (K+) to leak out of the cell, which is the main cause of negative membrane potentials in all neurons. TREK2 is a leak potassium channel and C-nociceptors that express it have much more negative membrane potentials.

Removal of TREK2 from the proximity of the cell membrane resulted in those neurons becoming less negative. This also occurred when the neuron was prevented from synthesising the TREK2.

Lowering the levels of synthesis of TREK2 in these C-fiber neurons was found to increase spontaneous pain associated with skin inflammation.

The team concluded that TREK2 keeps membrane potentials more negative in these C-fiber nociceptors, stabilising their membrane potential and reducing firing. This limited the the amount of spontaneous burning pain.

Professor Sally Lawson from the School of Physiology and Pharmacology at Bristol University said: "We demonstrated that TREK2 in C-fiber nociceptors is important for stabilizing their membrane potential and decreasing the likelihood of firing. It became apparent that TREK2 was thus likely to act as a natural innate protection against pain. Our data supported this, indicating that in chronic pain states, TREK2 is acting as a brake on the level of spontaneous pain."

It is hoped that the findings will lead to new treatments for sufferers of ongoing spontaneous burning pain by enhancing the actions of TREK2.

A new study published in the Journal of Biology describes how a protein that promotes cell growth allows cells to metastasise and spread through the bloodstream. 

Cancer cells are confined to the tissue in which they arise unless they can find a way into the bloodstream. The growth factor VEGF enables cells to do this by loosening connections between endothelial cells that form the lining of blood vessel walls.

VEGF triggers the phosphorylation of a protein called VEC, which serves to fasten endothelial cells together. As a result of this process, complexes that contain VEC fall apart, opening gaps between endothelial cells. Focal adhesion kinase (FAK), which accumulates at cell-to-cell junctions in the presence of VEGF, may play a role in VEC phosphorylation.

Scientists from the UC San Diego Moores Cancer Center gave a FAK inhibitor to a group of mice with fast-spreading breast cancer and a group with ovarian tumors in an attempt to pinpoint the function of the protein. It was discovered that the inhibitor prevented phosphorylation of a specific amino acid, known as tyrosine 658, in VEC from tumor-associated blood vessels.

VEGF was injected into a group of control mice and into mice with an inactive variant of FAK in their endothelial cells. Phosphorylation of VEC's tyrosine 658 occurred in the control rodents but not in the animals expressing inactive FAK, suggesting FAK controls the event.

Research was then conducted to determine the effect of FAK on endothelial cell layers.
VEGF-releasing tumor cells slipped through endothelial cells in experiments conducted on cell cultures. When endothelial cells produced an inactive version of FAK, however, cells did not pass through.

Further experiments conducted on mice revealed animals that expressed inactive FAK in their endothelial cells developed fewer tumours in their lungs compared with a group of control mice. Metastasis was curbed but tumour growth was unaffected.

The results show how endothelial FAK plays a role in controlling metastasis. They suggests it helps VEGF-expressing cancer cells open endothelial cell layers and clinical trials on FAK inhibitors are now being conducted.

Researchers have identified a protein which plays a role in the development of memory loss that affects patients suffering from Alzheimer's disease.

Scientists at the Cleveland Clinic, Ohio, found that a protein known as Neuroligin-1 (NLGN1), which is known to play a role in the formation of memories, is also linked to amyloid-associated memory loss. The results of the study are published in the journal Nature Neuroscience.

Alzheimer's disease involves the accumulation of amyloid beta proteins in the brains of sufferers, which serve to induce inflammation. As a result of the inflammation, certain gene modifications occur, causing memory loss by interrupting the functioning of synapses in the brain.

The researchers at the Cleveland Clinic conducted a study on animal models and discovered that the epigenetic modification of NLGN1 plays a key role in the neuroinflammatory process by disrupting the brain's synaptic network, which is responsible for developing and maintaining memories. The destruction of this network can lead to the type of memory loss exhibited by patients suffering from Alzheimer's disease.

"Alzheimer's is a challenging disease that researchers have been approaching from all angles," said Mohamed Naguib, the Cleveland Clinic physician who led the study. "This discovery could provide us with a new approach for preventing and treating Alzheimer's disease."

The same group of researchers previously identified a novel compound known as MDA7, which has the potential to halt the neuroinflammatory process that causes the modification of NLGN1. Studies conducted on an animal model found treatment with the compound led to the restoration of cognition, memory and synaptic plasticity – a crucial neurological foundation of learning and memory.

Preliminary work for the first human trial of MDA7 has been completed, including in-vitro studies and preliminary clinical toxicology and pharmacokinetic work. Phase I of the studies on the safety of these compounds is expected to begin in the near future.

More than half a million people suffer from Alzheimer's disease in the UK. It accounts for around two-thirds of the cases of dementia among elderly people.

A new study on the effects of vitamin D on Parkinson's Disease (PD) suggests early intervention may be a fruitful method of preventing or delaying cognitive impairment and depression.

Scientists conducted a cross-sectional analysis of 286 patients suffering from PD. Higher plasma vitamin D levels were associated with lower symptom severity, better cognition, and less depression in the entire group. The results were stronger in the group which was not suffering from dementia.

Patients were given a number of tests measuring global cognitive function, verbal memory, semantic verbal fluency, executive function, and depression. Measurements of serum 25-hydroxyvitamin D levels were also taken.

Some 61 of the subjects were considered to be suffering from dementia, according to a consensus panel using the Diagnostic and Statistical Manual of the American Psychiatric Association (4th edition). 

Researchers found there were significant negative associations between vitamin D levels and disease severity.

Higher levels of serum vitamin D3 were associated with greater fluency for naming vegetables and animals and immediate and delayed recall on a verbal learning test across the whole group.

Dividing the group into those suffering from dementia and those who were not, significant findings with vitamin D were found for fluency and verbal learning only for those not suffering from the condition. 

"The fact that the relationship between vitamin D concentration and cognitive performance seemed more robust in the non-demented subset suggests that earlier intervention before dementia is present may be more effective," said Amie Peterson, MD, of the Oregon Health and Sciences University.

It was also found that there was a significant negative association between vitamin D levels and depression, covering the entire group and those subjects not suffering from dementia. No such relationship was found in the sub-set who were suffering from dementia.

The study's authors said that causation could not determined – low vitamin D levels could affect cognitive performance, but patients suffering from dementia could have low levels due to the fact that they spend a lot of time indoors and are thus not exposed to sunlight.

In recent years, a number of studies have linked low vitamin D levels to a range of conditions, including multiple sclerosis and type 2 diabetes mellitus.

New research conducted into breast cancer cells has identified two states in which they exist and each of these plays a role in the spread of the disease.

"The lethal part of cancer is its metastasis so understanding how metastasis occurs is critical," says senior study author Max Wicha, MD, distinguished professor of oncology and director of the University of Michigan Comprehensive Cancer Center. "We have evidence that cancer stem cells are responsible for metastasis – they are the seeds that mediate cancer’s spread. Now we’ve discovered how the stem cells do this."

A type of stem cell exists on the outside of the tumour known as the epithelial-mesenchymal transition (EMT) state. These cells are able to enter the bloodstream and travel to distant parts of the body.

The cells transform into a second state, the mesenchymal-epithelial transition state (MET), when they reach their destination. These cells are able to produce new tumours by growing and copying themselves.

Both forms of cancer stem cells are necessary if cells are to metastasise and grow in other organs. They are unable to do this if only one or the other is present.

The team's findings have implications for breast cancer treatments, as researchers must now find out whether potential cures need to target both types of stem cell. As each type of stem cell is regulated by a different pathway, it may be that effective therapies have to target multiple pathways.

It may also pave the way for new testing methods. Currently, EMT cells do not seem to be captured by the tests for tumour cells circulating in the blood – and these are the cancer cells that travel through the bloodstream.

University of Michigan researchers are currently collaborating with a team from the university's College of Engineering to develop ways of isolating the EMT cells. Identifying the stem cells will enable the team to use markers to improve the effectiveness of treatments.

Although the study focussed on breast cancer, the findings may also apply to other types of the disease.

Scientists have identified a mutated gene which causes a particularly debilitating kind of brain tumour, possibly leading the way to new treatments for the condition.

The only treatments currently available for the tumours, which affect less than one in 100,000 people, are repeated surgery and radiation therapy. 

Research conducted by scientists from Dana-Farber/Boston Children's Cancer and Blood Disorders Center, Massachusetts General Hospital, and the Broad Institute of MIT and Harvard, reveals that drugs currently used to treat other kinds of tumours could be used to treat tumours known as craniopharyngiomas.

There are two types of craniopharyngiomas: adamantinomatous and papillary. They form in the base of the brain near the pituitary gland, hypothalamus, and optic nerves. 

A mutated gene known as BRAF was discovered in all samples of papillary craniopharyngiomas, which mainly occur in adults. 

The other type, adamantinomatous, occurs mainly in children. A different mutant gene was found to drive these tumours. The researchers said drugs to treat these tumours could become clinically available in the future.

"From a clinical perspective, identifying the BRAF mutation in the papillary tumors is really wonderful, because we have drugs that get into the brain and inhibit this pathway," said Sandro Santagata, MD, PhD, a co-senior author of the paper. "Previously, there were no medical treatments – only surgery and radiation – and now we may be able to go from this discovery right to a well-established drug therapy."

Malignant melanoma is currently treated using BRAF inhibitors and plans are now underway to test the effectiveness of this treatment in patients with papillary craniopharyngiomas.

Craniopharyngiomas can cause a number of debilitating conditions, including headaches, visual impairment, hormonal imbalances, obesity and short stature. Tumours often recur and, although they do not metastasise, are difficult to treat even using advanced neurosurgical techniques.

A single mutated BRAF gene was found to be the sole driver of 95 per cent of the papillary craniopharyngiomas analysed by the team with whole-exome DNA sequencing.

If the inhibitors prove successful in halting or reversing the growth of tumours, they could be used to reduce their size in order to prevent the need for major surgery.

New research into the role played by dysfunction of regulatory proteins that keep an oncogene in check could lead to the developments in drugs used to treat head and neck cancers.

Previous research has revealed activation and signalling of a protein known as Signal Transducer and Activator of Transcription 3 (STAT3) in many cancers. The increased activity of this protein is often associated with poor prognosis. In adult tissues, proteins that promote the growth and development of cancer cells are triggered by STAT3.

The new study, conducted at the University of Pittsburgh School of Medicine, could provide a reason for the hyperactivation of STAT3 and help to develop new drugs.

It was noted that STAT3 did not commonly occur in head and neck cancers so the team looked for mutations in other proteins associated with STAT3.

A phosphate group needs to be added to STAT3 in order to activate it. Cancer drugs tend to work by inhibiting enzymes that encourage this process.

However, the team focussed on the process by which enzymes known as phosphatases deactivate proteins by removing the phosphatases.

It was discovered that head and neck tumours with high levels of STAT3 were linked with mutations in the PTPR group of phosphatases. Computational and lab models were developed to replicate the mutations and it was found that they led to dysfunction of the enzymes.

Jennifer Grandis, distinguished professor of otolaryngology at the Pitt School of Medicine, and director of the head and neck program at the University of Pittsburgh Cancer Institute (UPCI), partner with UPMC CancerCenter, said: "Because the phosphatases don't work properly, phosphate groups don't get removed from STAT3 appropriately, and it stays activated. These mutations essentially get rid of the brakes that might otherwise slow or even stop cancer development."

Tumours could be screened for mutations to the PTPR group and they could be treated with drugs that inhibit STAT3's activity.

The team's findings are published in the early online version of the Proceedings of the National Academy of Sciences.

New research at the University of Texas South Western Medical Centre has identified a potential method of improving the odds of corneal transplant acceptance.

In a study conducted on mice, researchers found that blocking the action of an immune system molecule called interferon-gamma (IFN-y) led to corneal transplants being accepted 90 per cent of the time when the mice shared the same major histocompatibility complex (MHC) genotype as the donor cornea.

"Our findings indicate that neither MHC matching alone nor administration of anti-IFN-y antibody alone enhances graft survival. However, we found that when MHC matching is combined with anti-IFN-y therapy, long-term corneal transplant survival is almost guaranteed," said Dr Jerry Niederkorn, professor of ophthalmology and microbiology at UT Southwestern and senior author of the study.

Corneal transplants are a common operation. However, the body rejects the transplant in an estimated ten per cent of patients and the odds of a second procedure being successful are poor.

Surprisingly, the study found that IFN-y could act as an immune system suppressor or activator. Whether it does so depends on the context of the histocompatibility antigens perceived by the immune system. 

Earlier studies found that IFN-y caused the immune system to reject transplants and disabling it would improve acceptance rates. But the new research found that the rejection rate was 100 per cent when IFN-y is disabled and there is no MHC matching between the mice and the transplants.

In the latter case, IFN-y was needed to maintain the T-regulatory cells that suppress the body's immune response.

Dr Niederkorn suggested that transplant matching and inactivation of IFN-γ would make most sense for those individuals whose bodies have already rejected a cornea or those believed to be at risk of rejection, rather than all first-time recipients. 

Further study is necessary before a clinical trial can take place. The team are currently attempting to develop an IFN-γ antibody in eye-drop form but they will need to test this in animal models.

A new study has been published which sheds light on how strands of parasitic DNA proliferate as part of the ageing process.

Genomes of all organisms contain elements that, when not suppressed, copy themselves and spread, potentially affecting health. It has already been discovered that these parts, known as  "retrotransposable elements" (RTEs), are able to free themselves from the genome's control in cultures of human cells.

The new research, conducted at Brown University, examined the process in mice and found that RTEs became increasingly able to break free and copy themselves as the animals aged. This process was found to occur in cancerous tumours but can be combated by restricting calories.

Jill Kreiling, a research assistant professor at Brown, said: "This may be a very important mechanism in leading to genome instability. A lot of the chronic diseases associated with ageing, such as cancer, have been associated with genome instability."

It is not known whether the proliferation of RTEs only has negative effects. However, scientists do know that the body tries to control the rogue elements by wrapping them in a tight configuration known as heterochromatin. The study found that heterochromatin became more common in mouse tissues as they aged, although some tissues containing RTEs were loosened up.

The new study shows that the proliferation of RTEs is linked to the ageing of the whole organism. Although previous studies demonstrated the process at work in cell cultures, the process of replication in such cultures does not mirror that which occurs during ageing.

Researchers examined cells from the liver and skeletal muscle of mice aged five, 24 and 36 months. They found elevated expressions of RTEs in both types of tissue after 24 months and the RTEs also copied themselves and showed up elsewhere in the genome.

Mice which were adequately nourished but fed 40 per cent fewer calories than animals on a normal diet were found to have fewer RTEs. A restricted calorie intake is known to mitigate the ageing process in different animal models.

There was also an observed correlation between the presence of RTEs and tissues affected by naturally-occurring cancers, but there is not yet sufficient evidence to establish a causal link.

A new technique is being pioneered by researchers at Penn State University to regenerate functional neurons after brain injury and in those affected by Alzheimer's disease.

The scientists have used the brain's supporting cells, known as glial cells, to grow healthy neurons which are essential for transmitting brain signals.

When the brain is damaged, normal neurons often die or degenerate. Reactive glial cells proliferate as a defence mechanism against bacteria and toxins – but this leads to the formation of glial scars, which prevent the growth of healthy neurons.

Led by Gong Chen, a professor of biology at Penn State University, the team set about trying to transform glial cells back into normal brain cells.

The researchers studied how reactive glial cells respond to a protein known as NeuroD1, which plays an important role in the formation of nerve cells in the part of the brain known as the hippocampus. They reasoned that expressing the protein into reactive glial cells at a site of injury may help to generate new neurons.

A retrovirus which affects glial cells but not other neurons was used to introduce the genetic code for the NeuroD1 protein. The retrovirus was unable to replicate and thus could not destroy the host cells.

NeuroD1 retrovirus was introduced into the brains of mice. It was discovered that two types of reactive glial cells were reprogrammed into normal neurons within a week of being infected with the retrovirus.

In a second study on a mouse model with Alzheimer's disease, it was found that glial cells could be converted into functional neurons – even after the mice had reached 14 months, which is the equivalent of a 60-year-old human being.

The team tested the method on human cells in culture and found that they also regenerated and were able to transmit impulses.

"Our passionate motivation for this research is the idea that an Alzheimer's patient, who for a long time was not able to remember things, could start to have new memories after regenerating new neurons as a result of our in vivo conversion method, and that a stroke victim who could not even move his legs might start to walk again," Professor Chen explained.