Application of a triple‐helical peptide inhibitor of MMP‐2/MMP‐9 to examine T‐cell activation in experimental autoimmune encephalomyelitis

Multiple sclerosis (MS) is an inflammatory demyelinating disease whereby pathology includes multifocal perivascular mononuclear cell infiltration into the central nervous system, oligodendrocyte loss and demyelination, and variable axonal loss. Little is known about the causative agent in MS, but the matrix metalloproteinase (MMP) family of proteolytic enzymes has been implicated in disease progression and resolution. Recent studies revealed that MMP‐2 and/or MMP‐9 are required for an effective T‐cell‐mediated immune response to antigenic stimulation. In the present studies, we used an MMP‐2/MMP‐9 selective triple‐helical peptide inhibitor (THPI) to examine the role of these enzymes in antigen specific T‐cell responses. We found that treatment of murine CD4+ T‐cells with the THPI, followed by CD3/CD28 stimulation of the T‐cell receptor (TCR), resulted in reduced cell proliferation and production of interleukin 2 (IL‐2), interferon gamma (IFN‐γ), and tumor‐necrosis factor alpha (TNF‐α). Application of the THPI in experimental autoimmune encephalomyelitis (EAE), a widely accepted animal model of MS, reduced clinical severity of the disease and weight loss. Splenocytes isolated from THPI‐treated EAE animals had reduced proliferation compared with untreated animals. In an in vitro recall experiment, splenocytes isolated from EAE mice were treated with the THPI, followed by CD3/CD28 stimulation of the TCR. Treated splenocytes had reduced production of IL‐2, IL‐6, IL‐10, IFN‐γ, and TNF‐α compared with untreated splenocytes isolated from EAE mice. Overall, the MMP‐2/MMP‐9‐targeting THPI modulates T‐cell response to antigenic stimulation, including proliferation and immune cell production of specific cytokines, providing insight as to why the THPI is effective in reducing the clinical severity of EAE.