Obesity impairs key immune cells, making individuals more susceptible to severe outcomes from viral and bacterial infections, according to a new study led by Dr Ciara Flynn at Maynooth University. The research, published in JCI Insight, found that obesity disrupts the metabolism of gamma delta (γδ) T cells, a specialized group of immune cells.
These cells, particularly a subset called Vδ2+ T cells, are part of the body’s first line of defense and respond rapidly to infection. However, the researchers found that people living with obesity had fewer Vδ2+ T cells in their blood and that the cells were less active when stimulated.
This discovery sheds light on why people living with obesity face a higher risk of severe illness, as seen during COVID-19. More than one billion adults worldwide live with obesity, which is linked to a greater risk of severe outcomes from viral and bacterial infections.
The results suggest that excess weight interferes with the metabolic activity of these cells, restricting the energy supply needed to combat disease. Interestingly, this disruption can be corrected through specific surgical procedures like the Roux-en-Y gastric bypass (RYGB).
Patients who underwent RYGB experienced major enhancements in metabolic pathways supporting immune cell operations, alongside a noticeable return of the cells’ reactivity. Prof Andrew Hogan, the lead researcher from Maynooth University’s Obesity Immunology Research Group, described these results as revealing new connections between obesity and immune dysfunction.
Prof Helen Heneghan, a bariatric surgeon at St Vincent’s University Hospital, pointed out that effectively treating obesity via RYGB corrects the immune issues. Patients who have had bariatric surgery have a 40-50% lower chance of developing cancer and other obesity complications.
The investigation was a partnership between Prof Helen Heneghan and Prof Donal O’Shea at St Vincent’s University Hospital and University College Dublin, with financial support from the Health Research Board.
Professor Paul Moynagh, Director of the Kathleen Lonsdale Institute for Human Health Research at Maynooth University, said: “This study is an excellent example of highly impactful translational research. It has been achieved by Professors Hogan and Heneghan bringing their scientific and clinical expertise together to provide new insights into how obesity and its treatment affect the immune system in fighting infections and cancer.”