Modulation of Abundance and Location of High-Mobility Group Box 1 in Human Microglia and Macrophages under Oxygen–Glucose Deprivation

While stroke represents one of the main causes of death worldwide, available effective drug treatment options remain limited to classic thrombolysis with recombinant tissue plasminogen activator (rtPA) for arterial-clot occlusion. Following stroke, multiple pathways become engaged in producing a vicious proinflammatory cycle through the release of damage-associated molecular patterns (DAMPs) such as high-mobility group box 1 (HMGB1) and heat shock protein 70 kDa (HSP72). HMGB1, in particular, can activate proinflammatory cytokine production when acetylated (AcHMGB1), a form that prefers cytosolic localization and extracellular release. This study aimed at determining how HMGB1 and HSP72 are modulated and affected following treatment with the anti-inflammatory compound resveratrol and novel platelet membrane-derived nanocarriers loaded with rtPA (CSM@rtPA) recently developed by our group for ischemic artery recanalization. Under ischemic conditions of oxygen–glucose deprivation (OGD), nuclear abundance of HMGB1 and AcHMGB1 in microglia and macrophages decreased, whereas treatment with CSM@rtPA did not alter nuclear or cytosolic abundance. Resveratrol treatment markedly increased the cytosolic abundance of HSP72 in microglia. Using proximity ligation assays, we determined that HSP72 interacted with HMGB1 and with acetylated HMGB1. The interaction was differentially affected under the OGD conditions. Resveratrol treatment under the OGD further decreased HSP72-HMGB1 interactions, whereas, in contrast, treatment increased HSP72-AcHMGB1 interactions in microglia. This study points out a salient molecular interaction suited for a two-pronged nanotherapeutic intervention in stroke: enhancement of rtPA's thrombolytic activity and modulation of cytosolic interactions between HMGB1 and HSP72 by resveratrol.