Joshua Baker, MD, on the Association of Adipocytokines and Abnormal Body Composition in Rheumatoid Arthritis

Dr Baker, an assistant professor of medicine and immunology at the University of Pennsylvania, discusses his research into the relationship between body composition—specifically, the levels of fat and lean muscle— and rheumatoid arthritis.

Joshua Baker, MD, is an assistant professor of medicine and immunology at the University of Pennsylvania.

TRANSCRIPT:

Hi everybody, my name is Josh Baker. I am an associate professor at the University of Pennsylvania and the Philadelphia VA Hospital. I'm going to talk to you today about our study about adipocytokines and body composition in rheumatoid arthritis.

The reason that we're interested in studying this question is that body composition turns out to be important in rheumatoid arthritis. Body composition is simply the way your body is made up of muscle and fat. Somebody with rheumatoid arthritis can have an abnormal body composition simply because the inflammation from the disease can lead to a proportional loss of muscle mass compared to fat mass.

People with very severe rheumatoid arthritis can lose weight, but when they're losing weight, they're losing more muscle than they are fat. When we measure body composition in patients with RA, they can have a disproportionately low muscle mass compared to their fat mass.

We were interested in this problem in rheumatoid arthritis, because body composition is very, very strongly associated with a lot of important outcomes, in particular, with physical functioning. Patients that have lost a lot of muscle, as you can imagine, are more likely to have disability and poor physical functioning.

Body composition, unfortunately, it's a little bit difficult to measure in the clinic. We can measure weight, but as I just mentioned, measuring weight does not tell us about how much of the weight is composed of lean or muscle and fat. We can send people for imaging tests to do this, but we can't always do that in clinic.

We were interested in looking at different biomarkers and how they might be associated with body composition in patients with RA. Some of the biomarkers that have been thought about are things called adipokines. Adipokines are hormone markers and metabolic regulators that are produced by the fat.

If somebody has a change in their weight or gains weight, there are changes in these molecules in order to regulate metabolism. We hypothesized that we would see an association between some of these metabolic regulators and body composition in our patients with RA.

We studied 3 different body composition cohorts. These were from 3 different institutions. We combine them into a single cohort. We measured adipokines in these 3 cohorts and looked at body composition and the association with the adipokines.

What we found was that adipokines are particularly strongly associated with low lean mass. Patients who had low lean mass relative to their fat mass had much higher levels of adipokines. When we combined the adipokines, we could actually predict who had low lean mass with pretty good accuracy.

We suggested that this might be a good screening test for patients that have abnormal body composition, particularly in the setting where we don't have imaging where we can't image everybody and measure body composition directly.

Basically, the main takeaways from the study are that measuring adipokines is a pretty simple thing to do and it can actually identify people who are at risk for having abnormal body composition, particularly, in patients with RA.

We propose that this might be something that we could do to screen patients in clinic for abnormal body composition and maybe then take those people that look like they're at risk and do additional testing.

Once you've identified that someone has abnormal body composition, the only thing we really know how to do is to get people moving and to exercise to build up their muscle mass, but also treating the disease, and making sure that people have well-controlled rheumatoid arthritis can also help prevent deterioration's in body composition.

Identifying people at risk may help us target those patients for preventing muscle loss and trying to build up the muscle and prevent physical functioning loss.

Thank you very much for your time. I appreciate the opportunity to talk to you today and thank you very much.

Reference:

Baker JF, Katz P, Weber DR, et al. Adipocytokines and associations with abnormal body composition in rheumatoid arthritis. 2021; Arthritis Care Res. Accepted author manuscript. https://doi.org/10.1002/acr.24790