Category: Allergies

Categories : Allergies T-cellsTags :

Itching in Severe Eczema Uses a Different Pathway

On By ModernMedia

A study shows that there are two molecular pathways for conveying sensations of itching, with the itching of severe eczema following an unexpected route.

In normal eczema, cells in the skin convey the itching sensation, releasing histamines. This can be blocked with antihistamines.

“Years ago, we used to think that itch and pain were carried along the same subway lines in the nerves to the brain, but it turned out they weren’t, and these new findings show there’s another pathway entirely that’s causing these episodes of acute itching in eczema patients,” said principal investigator Brian S Kim, MD, Washington University School of Medicine. “The itch can be maddening. Patients may rate their chronic itch at around a 5 on a scale of 10, but that goes up to 10 during acute itch flares. Now that we know those acute flares are being transmitted in an entirely different way, we can target that pathway, and maybe we can help those patients.”

With severe itching in eczema, different cells in the blood are activated, transmitting great quantities of non-histamine molecules which also convey the itching sensation. This renders antihistamines usesles in trying to control the itch. The discovery of this new pathway offers new possibilities for treating other conditions as well. Recent studies have tried to block Immunoglobulin E (IgE) in response to allergies.

“We’ve connected acute itching in eczema to allergic reactions transmitted by an entirely different population of cells,” explained Kim. “In patients who experience episodes of acute itching, their bodies react in the same way as in people with acute allergy. If we can block this pathway with drugs, it might represent a strategy for treating not only itch but other problems, including perhaps hay fever and asthma.”

The team found that when mice with eczema made IgE in response to environmental allergens, they began to itch. However, instead of activating mast cells which produced histamine, the IgE activated basophils (a kind of white blood cell), activating a different nerve pathway to normal itching.

The discovery that eczema is exacerbated by allergens may help people avoid severe itching episodes, as well has helping the development of new targets for treatment.

Source: News-Medical.Net

Journal information: Wang, F., et al, A basophil-neuronal axis promotes itch. Cell, 2021 doi.org/10.1016/j.cell.2020.12.033.

Categories : Allergies GastrointestinalTags :

Stomach Bugs Induce Irritable Bowel Syndrome

On By ModernMedia

Researchers have pinpointed a localised biological mechanism behind irritable bowel syndrome (IBS), a chronic gastrointestinal condition where eating certain foods causes subsequent abdominal pain or discomfort.

Around 20% of people experience IBS, and diets such as gluten-free ones provide some relief. However, the exact cause was unknown, as the patients did not have allergic responses nor did they have coeliac disease, causing many physicians to dismiss it as psychological.A healthy immune system tolerates foods, and the first link is understanding how the tolerance is removed. Previous work showed that there was a link between mast cells and food, and that blocking histamine in people with IBS relieved the symptoms.

People with IBS often report their symptoms begin following a gastrointestinal infection, so the researchers reasoned that an infection associated with a particular type of food in the guy might sensitise the immune system to that food.The team fed mice with ovalbumin (an egg protein) and then infected them with a stomach bug. The mice were then fed ovalbumin again, and the researchers recorded elevated mast cell activation, histamine levels and digestive intolerance. In control mice who were fed with ovalbumin but who were not infected with the stomach bug, there was no response.

Breaking down the chain of events leading to the sensitisation, the researchers discovered that there was a localised immune response in the part of the guy infected by the bacteria, but did not produce the more generalised symptoms of a food allergy.  

Lead author Prof Guy Boeckxstaens, a gastroenterologist at KU Leuven thinks this may point to a spectrum of food-related immune disorders. He said, “At one end of the spectrum, the immune response to a food antigen is very local, as in IBS. At the other end of the spectrum is food allergy, comprising a generalised condition of severe mast cell activation, with an impact on breathing, blood pressure, and so on.”

When researchers injected IBS-associated food antigens into the intestinal walls of IBS patients, they observed localised reactions similar to what they saw in the mice, and there were no reactions in healthy patients. Larger clinical trials will be needed to confirm these observations.

“This is further proof that the mechanism we have unraveled has clinical relevance,”  Prof Guy Boeckxstaens said. “But knowing the mechanism that leads to mast cell activation is crucial, and will lead to novel therapies for these patients,” he goes on. “Mast cells release many more compounds and mediators than just histamine, so if you can block the activation of these cells, I believe you will have a much more efficient therapy.”

Source: Medical Xpress

Journal information: Local immune response to food antigens drives meal-induced abdominal pain, Nature (2021). DOI: 10.1038/s41586-020-03118-2 , www.nature.com/articles/s41586-020-03118-2

Categories : Allergies Uncategorized UrogenitalTags :

New Research Links Bladder Pain Flare-ups to Pollen

On By ModernMedia

High pollen counts have long been associated with allergic rhinitis with its well known symptoms such as itching eyes, running nose and sneezing, but now new research suggests that it may be aggravating a completely unexpected condition: chronic bladder pain.

In the United States, more than 10 million people are believed to suffer from urologic chronic pelvic pain syndrome (UCPPS) – a mysterious cluster of problems which include bladder pain syndrome and interstitial cystitis in women, chronic pelvic pain syndrome, and in men, chronic prostatitis.

Researchers regard it as “one of the most frustrating urologic conditions to understand and manage”, requiring a multidisciplinary and multimodal approach to management. However, it has been known to be associated with flare-ups of allergies, prompting Washington University epidemiologist Siobhan Sutcliffe to lead a team to investigate a possible connection. Their study recruited 290 participants diagnosed with UCPPS, and tracked pollen levels from three days before and on the day against UCPPS symptoms. Daily pollen counts did not correlate with UCPPS symptoms, but in participants with when pollen count was medium or high, there was a significant association with symptoms. The mast cell activation involved in pollen allergies release histamines which may be a contributing factor in UCPPS. Evidence for this comes from animal studies which have shown that exposure to histamine makes the bladder hypersensitive. Histamines also stays resident in the bladder longer than in the bloodstream as they are excreted via urine.

Sutcliffe said: “Our study provides evidence to suggest increased pollen counts may trigger symptom flares in people living with UCPPS.”This research may bring an avenue for some now forms of relief to UCPPS sufferers, but further research is needed to eliminate confounding factors, such as environmental factors associated with high pollen counts – strong levels of wind and thunderstorms may trigger pollen allergies but also exert some other kind of separate influence.

“Patients may benefit from taking antihistamines on days with high pollen levels, or from allergy testing and immunotherapy,” concluded Sutcliffe.

Source: Science Alert

Journal information: Javed I, Yu T, Li J et al. Does Pollen Trigger Urologic Chronic Pelvic Pain Syndrome Flares? A Case-Crossover Analysis in the Multidisciplinary Approach to the Study of Chronic Pelvic Pain Research Network. Journal of Urology. 2020. doi:10.1097/ju.0000000000001482