MATRIX METALLOPROTEINASE EXPRESSION DURING EXPERIMENTAL AUTOIMMUNE ENCEPHALOMYELITIS AND EFFECTS OF A COMBINED MATRIX METALLOPROTEINASE ANDTUMOR-NECROSIS-FACTOR-ALPHA INHIBITOR

Matrix metalloproteinases (MMPs) are a large family of Zn2+ endopeptid ases that are expressed in inflammatory conditions and are capable of degrading connective tissue macromolecules. MMP-like enzymes are also involved in the processing of a variety of cell surface molecules incl uding the pro-inflammatory cytokine TNF-alpha. MMPs and TNF-alpha have both been implicated in the pathology associated with neuro-inflammat ory diseases (NIDs), particularly multiple sclerosis (MS) and its anim al model experimental autoimmune encephalomyelitis (EAE). We have show n that BB-1101, a broad spectrum hydroxamic acid-based combined inhibi tor of MMP activity and TNF processing, reduces the clinical signs and weight loss in an acute EAE model in Lewis rats. However, little is k nown about which MMPs are involved in the neuroinflammatory process. I n order to determine the optimum inhibitory profile for an MMP inhibit or in the treatment of NID, we investigated the profile of MMP express ion and activity during EAE. The development of disease symptoms was a ssociated with a 3-fold increase in MMP activity in the cerebrospinal fluid (CSF), which could be inhibited by treatment with BB-1101, and a n increase in 92 kDa gelatinase activity detected by gelatin substrate zymography. Quantitative PCR analysis of normal and EAE spinal cord r evealed the expression of at least seven MMPs. Of these, matrilysin sh owed the most significant change, being elevated over 500 fold with on set of clinical symptoms and peaking at maximum disease severity. Of t he other six MMPs detected, 92 kDa gelatinase showed a modest 5 fold i ncrease which peaked at the onset of clinical signs and then declined during the most severe phase of the disease. Matrilysin was localised by immunohistochemistry to the invading macrophages within the inflamm atory lesions of the spinal cord. Matrilysin's potent broad spectrum p roteolytic activity and its localisation to inflammatory lesions in th e CNS suggest this enzyme could be particularly involved in the pathol ogical processes associated with neuro-inflammatory disease.