Impact of Minocycline on Extracellular Matrix Metalloproteinase Inducer, a Factor Implicated in Multiple Sclerosis Immunopathogenesis

Extracellular matrix metalloproteinase inducer (EMMPRIN, CD147) is a transmembrane glycoprotein that is upregulated on leukocytes in active lesions in multiple sclerosis (MS) and its animal model, experimental autoimmune encephalomyelitis (EAE). Administration of anti-EMMPRIN Abs reduces the severity of EAE. Minocycline is a tetracycline antibiotic with immune-modulatory properties that decreases the severity of EAE; it was recently found to attenuate the conversion from a first demyelinating event to clinically definite MS in a phase III trial. We investigated whether and how minocycline affects the expression of EMMPRIN on T cells in culture and in mice afflicted with EAE. EMMPRIN expression in cultures of mouse splenocytes or human PBMCs was elevated upon polyclonal T cell activation, and this was reduced by minocycline correspondent with decreased P-Akt levels. An established MS medication, IFN-beta, also diminished EMMPRIN levels on human cells whereas this was not readily observed for fingolimod or monomethylfumarate. In EAE-afflicted mice, minocycline treatment significantly reduced EMMPRIN levels on splenic lymphocytes at the presymptomatic (day 7) phase, and prevented the development of disease. Day 7 spleen transcripts from minocycline-treated EAE mice had a significantly lower MMP-9/TIMP-1 ratio, and significantly lower MCT-1 and CD98 levels, factors associated with EMMPRIN function. Day 16 (peak clinical severity) CNS samples from EAE mice had prominent representation of inflammatory perivascular cuffs, inflammatory molecules and EMMPRIN, and these were abrogated by minocycline. Overall, minocycline attenuated the activation-induced elevation of EMMPRIN on T cells in culture and in EAE mice, correspondent with reduced immune function and EAE CNS pathology.