Adipose tissue in patients with multiple sclerosis is marked by an activated lipolytic metabolic state.
AMSTERDAM—Patients with multiple sclerosis (MS) have an altered metabolic flexibility after glucose load, both at rest and during exercise, researchers reported at the Fifth Joint Triennial Congress of the European and Americas Committees for Treatment and Research in MS.
Persons with MS had a higher baseline respiratory quotient at rest than healthy controls did, which may indicate that the former have a higher rate of carbohydrate oxidation and a lower rate of lipid oxidation than the latter do. Also, after 40 minutes of light exercise, patients with MS showed greater energy expenditure than controls did.
Measuring Metabolismin Patients With MS
One symptom of MS is an intolerance to exercise, but it is not clear whether this symptom results from a metabolic change. To test the hypothesis that altered metabolic flexibility contributes to exercise intolerance in patients with MS, Anja Mähler, a nutritionist at the Experimental and Clinical Research Center and NeuroCure Clinical Research Center, Charité University Medicine, Berlin, and colleagues conducted a prospective study of 16 patients (eight men), with MS who were taking glatiramer acetate.
The patients’ mean age was 45, their mean BMI was 25.2, and they had had MS for a median of 133 months. Eight healthy men and eight healthy women also were studied as controls. The mean age of members of the control group was 40, and their mean BMI was 23.3.
In two separate tests, the researchers compared the groups’ postprandial and exercise activity metabolism with their resting metabolism, both after an oral glucose load. Blood marker metabolites and calorimetry were used to study systemic metabolism, and adipose tissue and skeletal muscle microdialysis were used to examine local metabolism.
Altered Metabolic Flexibility Could Result From MS
After an oral glucose load, patients with MS expended slightly less postprandial energy than controls did. Baseline and postprandial respiratory quotients, however, were higher in patients with MS than in controls, which indicated that the patients had higher carbohydrate and lower lipid oxidation rates than did controls. In addition, higher baseline and postprandial levels of dialysate glucose and lactate in adipose tissue in patients with MS indicated an activated lipolytic metabolic state.
The respiratory quotient kinetics were different in patients with MS than in controls during exercise, according to the study. Respiratory quotient did not reach a plateau in patients with MS as it did in controls.
The altered metabolic flexibility in patients with MS at rest and during exercise “might be attributed to an autonomic dysfunction,” said the investigators. The activated lipolytic metabolic state seen in the adipose tissue of patients with MS “could be caused by local monocyte/macrophage infiltration due to systemic inflammation,” they remarked. Future studies should investigate whether these two factors contribute to mitochondrial dysfunction in patients with MS, the investigators concluded.
—Erik Greb