Medical Bulletin 22/ January/ 2025
Here are the top medical news for the day:
How Cigarette Smoke Weakens Lung Immune Cells: Study Finds
A new study showed the effects of cigarette smoke on mucosal-associated invariant T (MAIT) cells, a type of immune cell found in the lungs and other tissues of the body. MAIT cells help fight off bacterial and viral infections and can promote inflammation or tissue repair. The findings are published in the Journal of Experimental Medicine (JEM), suggests that these alterations make cigarette smokers, and those exposed to second- and third-hand smoke, more susceptible to respiratory infections, and worsen smoking-related inflammatory diseases such as chronic obstructive pulmonary disease (COPD).
MAIT cells are activated by a protein called MR1 that is found in almost every cell of the body. MR1 recognizes chemicals produced by bacteria and presents them at the surface of infected cells in order to activate MAIT cells and initiate an immune response.
The researchers used computer modeling to predict which components of cigarette smoke might be recognized by MR1 and found that several of these molecules not only bound to the protein but also either increased or decreased its amounts on the surface of cells. These chemicals, including benzaldehyde derivatives that are also used as flavorings in cigarettes, e-cigarettes, blocked activation of human MAIT cells by compounds produced by bacteria.
The research team then studied the effects of cigarette smoke on MAIT cells from human blood and mice and showed they reduced MAIT cell function. Mice repeatedly exposed to cigarette smoke developed symptoms of lung disease and this was worsened if also infected by influenza. Researchers found that long-term exposure to cigarette smoke altered the protection provided to mice by their MAIT cells, making them less able to fight off influenza infections and more prone to the development of COPD disease.
Reference: Wael Awad, Jemma R. Mayall, Weijun Xu, Matt D. Johansen, Timothy Patton, Xin Yi Lim, Izabela Galvao, Lauren J. Howson, Alexandra C. Brown, Tatt Jhong Haw, Chantal Donovan, Shatarupa Das, Gesa J. Albers, Tsung-Yu Pai, Elinor Hortle, Caitlin M. Gillis, Nicole G. Hansbro, Jay C. Horvat, Ligong Liu, Jeffrey Y.W. Mak, James McCluskey, David P. Fairlie, Alexandra J. Corbett, Philip M. Hansbro, Jamie Rossjohn; Cigarette smoke components modulate the MR1–MAIT axis. J Exp Med 3 February 2025; 222 (2): e20240896. doi: https://doi.org/10.1084/jem.20240896
Suffering from Chronic Back Pain? Lifestyle Modification May Make Difference
A new study, published in JAMA Network Open, found integrating lifestyle support into back pain care could reduce disability and enhance quality of life.
The randomised controlled trial included 346 participants from across Australia, all of whom had chronic low back pain and at least one lifestyle risk factor, such as obesity, poor diet, sedentary habits, or smoking. Participants were randomly assigned to one of two groups: the "Healthy Lifestyle Program (HeLP)" or standard guideline-based physiotherapy care for managing their low back pain.
The HeLP participants received support from physiotherapists, dietitians and telephone health coaches who helped them work out which lifestyle habits might be influencing their back pain, such as weight, inactivity, poor diet, poor sleep, smoking or excessive alcohol use. They were then provided evidence-based advice over a six-month period to help address the lifestyle challenge.
The approach showed several benefits compared to standard care including reduced disability, with participants scoring an average of 1.3 points lower on the Roland Morris Disability Questionnaire (higher scores indicate greater disability). HeLP participants also lost an average of 1.6kg more than the control group.
Chief Investigator Associate Professor Chris Williams explained that the findings challenge traditional views of back pain management:
"Resolving back pain needs to focus on more than the back. Our bodies are not like machines, we are more like ecosystems where lots of factors interact and determine how we work and feel. Back pain is no different. So, when someone has back pain that doesn't get better, they should expect to get comprehensive care about a range of health factors, not just a focus on what's happening in their spine. We should shout this message from roof tops."
Reference: https://www.sydney.edu.au/news-opinion/news/2025/01/13/healthy-lifestyle-changes-shown-to-help-low-back-pain.html
Study Reveals Fatty Muscle Increases Heart Disease Risk
People with pockets of fat hidden inside their muscles are at a higher risk of dying or being hospitalised from a heart attack or heart failure, regardless of their body mass index, according to research published in the European Heart Journal.
The new finding adds evidence that existing measures, such as body mass index or waist circumference, are not adequate to evaluate the risk of heart disease accurately for all people.
The new research included 669 people who were being evaluated at the Brigham and Women’s Hospital for chest pain and/or shortness of breath and found to have no evidence of obstructive coronary artery disease. These patients had an average age of 63. All the patients were tested with cardiac positron emission tomography/computed tomography (PET/CT) scanning to assess how well their hearts were functioning. Researchers also used CT scans to analyse each patient’s body composition, measuring the amounts and location of fat and muscle in a section of their torso. To quantify the amount of fat stored within muscles, researchers calculated the ratio of intermuscular fat to total muscle plus fat, a measurement they called the fatty muscle fraction.
Patients were followed up for around six years and researchers recorded whether any patients died or were hospitalised for a heart attack or heart failure.
Researchers found that people with higher amounts of fat stored in their muscles were more likely to have damage to the tiny blood vessels that serve the heart, and they were more likely to go on to die or be hospitalised for heart disease. For every 1% increase in fatty muscle fraction, there was a 2% increase in the risk of coronary microvascular dysfunction and a 7% increased risk of future serious heart disease, regardless of other known risk factors and body mass index.
People who had high levels of intermuscular fat and evidence of coronary microvascular dysfunction were at an especially high risk of death, heart attack and heart failure. In contrast, people with higher amounts of lean muscle had a lower risk. Fat stored under the skin did not increase the risk.
Professor Viviany Taqueti, Director of the Cardiac Stress Laboratory at Brigham and Women's Hospital and Faculty at Harvard Medical School, Boston, USA said: “Compared to subcutaneous fat, fat stored in muscles may be contributing to inflammation and altered glucose metabolism leading to insulin resistance and metabolic syndrome. In turn, these chronic insults can cause damage to blood vessels, including those that supply the heart, and the heart muscle itself.
Reference: Ana Carolina do A H Souza, Amelie S Troschel, Jan P Marquardt, Ibrahim Hadžić, Borek Foldyna, Filipe A Moura, Jon Hainer, Sanjay Divakaran, Ron Blankstein, Sharmila Dorbala, Marcelo F Di Carli, Hugo J W L Aerts, Michael T Lu, Florian J Fintelmann, Viviany R Taqueti, Skeletal muscle adiposity, coronary microvascular dysfunction, and adverse cardiovascular outcomes, European Heart Journal, 2025;, ehae827, https://doi.org/10.1093/eurheartj/ehae827
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