Gp91phox (NOX2) in classically activated microglia exacerbates traumatic brain injury

<p>Abstract</p> <p>Background</p> <p>We hypothesized that gp91^phox(NOX2), a subunit of NADPH oxidase, generates superoxide anion (O₂^-) and has a major causative role in traumatic brain injury (TBI). To evaluate the functional role of gp91^phoxand reactive oxygen species (ROS) on TBI, we carried out controlled cortical impact in gp91^phoxknockout mice (gp91^phox-/-). We also used a microglial cell line to determine the activated cell phenotype that contributes to gp91^phoxgeneration.</p> <p>Methods</p> <p>Unilateral TBI was induced in gp91^phox-/-and wild-type (Wt) mice (C57/B6J) (25-30 g). The expression and roles of gp91^phoxafter TBI were investigated using immunoblotting and staining techniques. Levels of O₂^-and peroxynitrite were determined <it>in situ </it>in the mouse brain. The activated phenotype in microglia that expressed gp91^phoxwas determined in a microglial cell line, BV-2, in the presence of IFNγ or IL-4.</p> <p>Results</p> <p>Gp91^phoxexpression increased mainly in amoeboid-shaped microglial cells of the ipsilateral hemisphere of Wt mice after TBI. The contusion area, number of TUNEL-positive cells, and amount of O₂^-and peroxynitrite metabolites produced were less in gp91^phox-/-mice than in Wt. In the presence of IFNγ, BV-2 cells had increased inducible nitric oxide synthase and nitric oxide levels, consistent with a classical activated phenotype, and drastically increased expression of gp91^phox.</p> <p>Conclusions</p> <p>Classical activated microglia promote ROS formation through gp91^phoxand have an important role in brain damage following TBI. Modulating gp91^phoxand gp91^phox-derived ROS may provide a new therapeutic strategy in combating post-traumatic brain injury.</p

Clinical Study Status of Systemic Oxidative Stress during Therapeutic Hypothermia in Patients with Post-Cardiac Arrest Syndrome

Therapeutic hypothermia (TH) is thought to be due to the downregulation of free radical production, although the details of this process remain unclear. Here, we investigate changes in oxidative stress and endogenous biological antioxidant potential during TH in patients with post-cardiac arrest syndrome (PCAS). Nineteen PCAS patients were enrolled in the study. Brain temperature was decreased to the target temperature of 33 ∘ C, and it was maintained for 24 h. Patients were rewarmed slowly (0.1 ∘ C/h, &lt;1 ∘ C/day). The generation of reactive oxygen metabolites (ROMs) was evaluated in plasma samples by d-ROM test. Plasma antioxidant capacity was measured by the biological antioxidant potential (BAP) test. Levels of d-ROMs and BAP levels during the hypothermic stage (33 ∘ C) were suppressed significantly compared with pre-TH induction levels ( &lt; 0.05), while both d-ROM and BAP levels increased with rewarming (33-36 ∘ C) and were correlated with brain temperature. Clinical monitoring of oxidative stress and antioxidant potential is useful for evaluating the redox state of patients undergoing TH after PCAS. Additional therapy to support the antioxidant potential in the rewarming stage following TH may reduce some of the observed side effects associated with the use of TH

Status of Systemic Oxidative Stress during Therapeutic Hypothermia in Patients with Post-Cardiac Arrest Syndrome

Therapeutic hypothermia (TH) is thought to be due to the downregulation of free radical production, although the details of this process remain unclear. Here, we investigate changes in oxidative stress and endogenous biological antioxidant potential during TH in patients with post-cardiac arrest syndrome (PCAS). Nineteen PCAS patients were enrolled in the study. Brain temperature was decreased to the target temperature of 33°C, and it was maintained for 24 h. Patients were rewarmed slowly (0.1°C/h, <1°C/day). The generation of reactive oxygen metabolites (ROMs) was evaluated in plasma samples by d-ROM test. Plasma antioxidant capacity was measured by the biological antioxidant potential (BAP) test. Levels of d-ROMs and BAP levels during the hypothermic stage (33°C) were suppressed significantly compared with pre-TH induction levels (P<0.05), while both d-ROM and BAP levels increased with rewarming (33–36°C) and were correlated with brain temperature. Clinical monitoring of oxidative stress and antioxidant potential is useful for evaluating the redox state of patients undergoing TH after PCAS. Additional therapy to support the antioxidant potential in the rewarming stage following TH may reduce some of the observed side effects associated with the use of TH