Soluble urokinase receptor (uPAR, CD 87) is present in serum and cerebrospinal fluid in patients with neurologic diseases

Background: The receptor for urokinase plasminogen activator (uPAR) promotes invasion by neoplastic or inflammatory cells by focusing proteolysis of urokinase to the cell surface. In pathologic conditions, soluble forms of the receptor (suPAR) are released, and activate cell receptors to promote chemotaxis. In the CNS, suPAR and other components of the plasminogen activation system (PAS) could be associated with an increase of the blood-brain barrier (BBB) permeability and subsequent neural damage. Objective: To detect suPAR in the serum and cerebrospinal fluid (CSF) of patients with diverse neurologic conditions. Patients and methods: Serum and CSF from 121 patients with cancer, bacterial and viral infection, stroke, demyelinating disease and peripheral neuropathy were examined for the presence of suPAR. Results: suPAR was elevated in the serum of patients with paraneoplastic syndromes, and carcinomatous meningitis and infections, but less in stroke and demyelinating disease patients. CSF suPAR was present in the cancer and CNS infection groups, but not in the other groups. The levels of serum and CSF suPAR were correlated, and CSF suPAR correlated with the albumin index. Conclusions: suPAR is present in serum and CSF of patients with carcinomatous meningitis, paraneoplastic disorders and bacterial and viral infection of the CNS. suPAR could be associated with BBB disruption and with promotion of CNS invasion by chemotactically active cells, macromolecules, and microbes.