Researchers have observed that increased fat tissue mass results in increased risk of tendon disease and injury ('tendinopathy') which we feel as joint aches, pains and stiffness. The increased load on the tendons could partly explain this association but tendon degeneration also occurs in non-weight bearing sites, such as upper limbs. This means that other factors besides a simple increase in the amount of fat tissue are involved.
Dr David Musson leads the Tendon and Mechanobiology Research Programme within the Bone and Joint Research Group of the Department of Medicine at the University of Auckland. In his most recent AMRF project and with funding for his Senior Research Fellowship from the Auckland Medical Research Foundation, he is working to find and understand the mechanisms that are driving the fat related increased risk of tendinopathy.
In these studies, they found that animals that were fed fatty diets and had higher percentage body fat had weaker tendons that heal poorly. They also found that exposing tendon cells directly to fat tissue made them grow faster, have higher inflammatory gene expression, and increased expression of genes involved in tendon matrix remodeling.
All of these results suggest that increased fat tissue causes negative changes in tendon cell behaviour, but also importantly, they showed that switching back to a normal diet can attenuate some of these changes, although the timing of this is important to see benefits in tendon healing after injury.
Dr Musson says: "We now know some of the metabolic hormones and adipokines (fat-derived hormones) that affect tendon cell behaviour and thus affect the mechanical properties that are important for tendons to remain healthy. We are now looking at ways to reduce their impact and keep tendons healthier, longer." Dr Musson says.
"We are also collecting and comparing tendons from people with different body mass indices (BMI), so with different fat tissue mass, to determine how these findings translate into the clinical setting so that we can target these factors and work toward the ultimate goal of improving patient wellbeing."
"As always, I'm incredibly grateful for the funding received to complete this project and the support of the generous donors to the Auckland Medical Research Foundation."
Read more about how tendon research can save millions of dollars for the health system.