Researchers have found that chewing food prompts the release of an immune cell that can protect against infection. According to the study team, led by Dr Joanne Konkel of the University of Manchester in the United Kingdom, in the gut and the skin, Th17 cells are produced through the presence of friendly bacteria. However, the researchers note that the mechanisms by which Th17 cells are produced in the mouth have been unclear. Dr Konkel and colleagues note that the mechanical force required by mastication leads to physiological abrasion and damage in the mouth. With this in mind, the team set out to investigate whether such damage might play a role in oral Th17 cell production. The researchers came to their findings by feeding weaning mice soft-textured foods, which required less chewing, until they reached 24 weeks of age. At 24 weeks, the release of Th17 cells in the rodents’ mouths was measured. A significant reduction in oral Th17 cell production was noted, which the team speculated was down to a reduction in mastication-induced physiological damage. Confirming their theory, the researchers found that increasing the levels of physiological damage in the rodents’ mouths – by rubbing the oral cavity with a sterile cotton applicator – led to an increase in the production of Th17 cells. Dr Konkel and colleagues believe these findings indicate that chewing food may help to protect us from illness. Dr Joanne Konkel said, “The immune system performs a remarkable balancing act at barrier sites such as the skin, mouth and gut by fighting off harmful pathogens while tolerating the presence of normal friendly bacteria. Our research shows that, unlike at other barriers, the mouth has a different way of stimulating Th17 cells: not by bacteria but by mastication. Therefore mastication can induce a protective immune response in our gums.” In their study, the team also found that long-term exposure to physiological damage caused by mastication could exacerbate the effects of periodontitis. They came to this finding by feeding weaning mice hardened food pellets up until 24 weeks of age. Compared with mice fed soft food, the mice fed hard food showed more mastication-induced physiological damage in their mouths and increased periodontal bone loss. Still, the researchers believe that their findings could lead to new strategies to combat an array of illnesses. “Importantly, because inflammation in the mouth is linked to development of diseases all around the body,” said Dr Konkel, “understanding the tissue-specific factors that regulate immunity at the oral barrier could eventually lead to new ways to treat multiple inflammatory conditions”. Meanwhile, a new study says that early-life asthma may contribute to childhood obesity. The researchers – led by Zhanghua Chen, a research associate of environmental health at the Keck School of Medicine at USC – examined the medical records of 2,171 non-obese children between 5-8 years old. The USC researchers examined 10 years’ worth of data collected in the CHS, and they also performed a replication analysis on an independent sample of 2,684 CHS children. This latter cohort was followed from the average age of 9.7 years to 17.8 years. During this time, researchers measured the children’s height and weight annually, categorising them into normal, overweight, and obese. Children were deemed overweight or obese if their body mass index (BMI) was at or above the 85th and 95th percentile, respectively, compared with the BMI standards set by the CDC. Chen and team assessed the children’s asthma using the physician’s diagnosis as reported by the children or by their parents. After statistical adjustments, the researchers found that early childhood asthma did contribute to the development of obesity in subsequent years, mainly during early childhood and adolescence. Compared with non-obese, asthma-free children, the non-obese children who did have asthma were 51 percent more likely to develop obesity during follow-up. The results stayed the same following sociodemographic adjustments and adjustments for other variables. Additionally, children with a history of wheezing were at a 42 percent higher risk of developing obesity. The age of asthma onset did not seem to influence the obesity risk. Regarding the link between the use of asthma medications and obesity, the researchers made another interesting discovery. They found that the use of asthma rescue medications, such as an asthma inhaler, significantly lowered the risk of obesity. These results were independent of physical activity. Frank Gilliland, the study’s senior author, points out that a combination of asthma and obesity can trigger other metabolic diseases in adulthood, including prediabetes and type-2 diabetes.