Transforming Growth Factor Beta Signalling in the Development of Muscle Weakness in Pulmonary Arterial Hypertension

Pulmonary arterial hypertension (PAH) is a disease that causes raised blood pressure in blood vessels that pick up oxygen from the lungs. It has a life expectancy similar to some cancers. There is treatment available but there is no cure. We now know that PAH is associated with weakness in the muscles in the legs, which contributes to the symptoms patients' experience. Researchers believe that certain proteins found in high levels in the blood of patients with other chronic diseases can affect muscle function and growth. One of these proteins is called growth differentiating factor (GDF) 8, high levels of which are associated with muscle weakness in chronic obstructive pulmonary disease(COPD) and heart failure (HF). Interestingly there are drugs available which block the actions of GDF-8 on muscle cells which has been shown in animals to result in increased muscle size. A related protein called GDF-15 is found in elevated levels in patients PAH, and is linked to prognosis. Our preliminary data suggests that GDF-15 can also directly influence muscle size in a number of situations. We aim to investigate the role of GDF-15 and related molecules in the development of muscle weakness in patients with PAH. We will do this by measuring certain markers of muscle weakness and taking blood and muscle samples in patients and controls. We will then compare the levels of GDF-15 in these tissues in those with and without muscle wasting. We hope this work will lead to a greater understanding of the role of GDF-15 in the development of muscle weakness in patients with PAH. GDF-15 levels may be important in allowing us to define which patients have muscle weakness. In the future we aim to perform a clinical trial of drugs which block the actions of GDF-15.