Lipedema – lack of evidence for the involvement of tyrosine kinases

Lipedema is a chronic disorder characterized by abnormal distribution of subcutaneous adipose tissue on the proximal extremities, pain and capillary fragility. Its etiology is unknown but in analogy to central obesity, chronic low-level inflammation in adipose tissue has been suggested. There seems to be an increased propagation of pre-adipocytes into mature adipocytes contributing to the massive enlargement of subcutaneous adipose tissue. We investigated whether tyrosine kinases might be involved. Proteins from adipose tissue harvested during microcannular tumescent liposuction in lipedema and in lipomas were subjected to 10% polyacrylamide-gel, transferred to a polyvinylidenfluorid membrane and immunoblotted with indicated P-Tyr-100 antibody followed by enhanced chemiluminescence reaction. A survey of all blots did not reveal tyrosine-phosphorylated proteins with a molecular weight >100 kD in lipedema tissue and controls. These investigations suggest absence of activated growth factor receptors. Some signals indicating unspecific tyrosine-phosphorylation of smaller proteins were detected in tissue of both lipedema patients and controls. The present data suggest that there is no enduring activation of tyrosine kinase pathways of adipogenesis in lipedema as in lipoma controls.