Myxoma virus derived immune modulating proteins, M-T7 and Serp-1, reduce early inflammation after spinal cord injury in the rat model

Abstract

Spinal cord injury (SCI)-initiated inflammation was treated with anti-inflammatory reagents. We compared local spinal cord or intraperitoneal infusion of two Myxoma virus derived immune modulating proteins, Serp-1 and M-T7, with dexamethasone (DEX). Hemorrhage and necrosis after SCI initiate a complex pathogenesis dominated by early, severe and highly destructive inflammatory macrophage infiltration. We examined sustained, 7-day, subdural infusion of either M-T7, a chemokine modulator or Serp-1, a plasminogen activator and factor inhibitor. Mature male rats had epidural balloon crush SCI and sustained subdural infusion of Serp-1, M-T7, DEX or saline for 7 days via the osmotic pump. A separate group of rats with SCI had intra-peritoneal infusion. Clinical evaluation included endpoint monitoring with body weight, hemorrhagic cystitis and bilateral toe pinch response. Sections of the spinal cord were analyzed histologically and macrophage numbers counted by standardized protocol in the cavity of injury (COI). While the rats administered DEX demonstrated substantial body weight loss, dehydration and dermal atrophy consistent with steroid toxicity, rats infused with Serp-1 and M-T7 had no toxicity. Serp-1 improved withdrawal responses. Subdural infusion of Serp-1, M-T7 and DEX significantly reduced numbers of phagocytic, CD68-positive macrophages. With intraperitoneal infusion only M-T7 reduced macrophage counts, Serp-1 showed only a trend. Local infusion of highly active immune modulating proteins; Serp-1 and M-T7, targeting serine protease and chemokine pathways demonstrated excellent potential for neuroprotection after severe SCI in a rat model, without adverse side effects. Sustained subdural infusion offers an alternative route of administration for treatment of SCI.

Prolonged inflammation leads to ongoing damage after spinal cord injury

“…It appears that an anti-inflammatory/neuroprotective therapy for SCI should involve reducing the numbers of macrophages during the inflammatory phase to inhibit myelin damage (Fig. 2b) [24].…”

“…The longevity of the inflammatory phase seen after SCI indicates that 24-48 hrs of intravenous infusion of high dose anti-inflammatory treatments such as methylprednisolone succinate [23] may provide a partial explanation for why short term high dose steroid infusions are unlikely to be effective as has been demonstrated by a lack of efficacy in prior clinical trials for steroid infusions given early after SCI. High dose steroids additionally cause severe toxicity [1], indicating the need for novel anti-inflammatory compounds of low toxicity that can target central mediators of ongoing inflammation and injury, with potential for sustained long-term administration designed to reduce prolonged inflammation after SCI [13, 24].…”

Addition of a Viral Immunomodulatory Domain to Etanercept Generates a Bifunctional Chemokine and TNF Inhibitor

“…Serin protease inhibitors (Serpins) encoded by poxviruses have shown potent anti-inflammatory activity in a number of disease models [37]. The M-T7 vCKBP encoded by myxoma virus, in combination with viral Serpin-1, reduces the early inflammatory response after spinal cord injury [38].…”

Local Serpin Treatment via Chitosan-Collagen Hydrogel after Spinal Cord Injury Reduces Tissue Damage and Improves Neurologic Function

“…Treatment for SCI with short term, intravenous methylprednisolone (steroid, NASCIS studies) [4][5][6][7][8][9][10], or steroid cocktails have been used, but with limited proven efficacy and have been associated with severe side effects [8,[10][11][12][13]. Steroid use after SCI has remained hotly debated for decades [14,15].…”

“…Indeed, the American Association of Neurological Surgeons and the Congress of Neurological Surgeons published a medical evidence-based guideline with recommendation against the use of methylprednisolone in SCI [16]. Many minimally invasive and regenerative therapeutics are under investigation ranging from regenerative therapy with hydrogel implants, stem cells, growth factors, magnesium and antioxidants, among others, but without proven long term benefits at this time [1,2,[4][5][6][7][11][12][13]17,18]. Chitosan hydrogels with or without growth factors have been proven to promote SCI restoration and axon regeneration in rat and monkey models [19][20][21].…”