Effects of Minocycline Plus Tissue Plasminogen Activator Combination

Emerging evidence suggests that stroke comorbidities are associated with tissue plasminogen activator (tPA)–associated intracerebral hemorrhage (ICH) complication, a major limitation of tPA therapy. Clinical investigations have documented a correlation between increased ICH and worse neurological outcomes after tPA thrombolysis in stroke patients with diabetes mellitus or poststroke hyperglycemia. Therefore, development of therapeutic approaches for improving tPA thrombolysis in patients with diabetes mellitus or poststroke hyperglycemia is considered a high clinical priority. Although the pathophysiology of stroke patients with diabetes mellitus or posthyperglycemia is complex, experimental animal studies have suggested that vascular inflammation and blood– brain barrier disruption may be 2 major contributors to increased hemorrhagic transformation and worse neurological outcomes after stroke and tPA thrombolytic therapy. Combination of neuroprotective and anti-inflammatory agents with tPA thrombolysis would be a reasonable approach to overcome the above shortcomings. Minocycline might be a compelling candidate. Minocycline is a semisynthetic tetracycline, which has been clinically used as an antibiotic and anti-inflammatory drug. Accumulating experimental evidence has demonstrated that minocycline is neuroprotective in multiple neurological disorders, including ischemic and hemorrhagic stroke. Ongoing clinical trials suggest that minocycline may be safe and potentially beneficial in humans. Although its underlying molecular mechanisms remain to be fully defined, minocycline possesses a wide array of anti-inflammatory, antiapoptotic, antioxidative, and vascular protective properties. These effects may be especially important in Background and Purpose—Poststroke hyperglycemia is associated with resistance to tissue plasminogen activator (tPA) reperfusion, higher risk of intracerebral hemorrhage, and worse neurological outcomes. In this study, we asked whether minocycline combined with intravenous tPA may ameliorate inflammation and brain injury after focal embolic stroke in type 1 diabetic rats. Methods—Type 1 diabetic rats were subjected to a focal embolic stroke. Three treatment groups were used: (1) saline at 1.5 hours after stroke; (2) tPA alone at 1.5 hours after stroke; (3) combined minocycline (intravenously) at 1 hour plus tPA at 1.5 hours, and second treatment of minocycline (intraperitoneally) at 12 hours after stroke. Acute brain tissue damages were assessed at 24 hours after stroke. Inflammatory biomarkers interleukin-1β and matrix metalloproteinases 2 and 9 were examined in plasma. Neutrophil infiltration, microglia activation, matrix metalloproteinase activation, and degradation of the tight junction protein claudin-5 were examined in the brain. Results—Compared with saline or tPA alone treatments, minocycline plus tPA combination therapy significantly reduced brain infarction, intracerebral hemorrhage, and hemispheric swelling at 24 hours after stroke. The combination also significantly suppressed the elevated plasma levels of matrix metalloproteinase-9 and interleukin-1β up to 24 hours after stroke. At 16 hours after stroke, neutrophil infiltration, microglia activation, matrix metalloproteinase-9, and tight junction protein claudin-5 degradation in the peri-infarct brain tissues were also significantly attenuated by the combination therapy. Conclusions—Combination therapy with minocycline plus tPA may be beneficial in ameliorating inflammation and reducing infarction, brain swelling, and hemorrhage after ischemic stroke with diabetes mellitus/hyperglycemia. (Stroke. 2013;44:745-752.)