4-hydroxy-2-nonenal and Brain-Injuries--Traumatic

Traumatic brain injury (TBI) encompasses a broad range of injury mechanisms and severity. A detailed determination of TBI severity can be a complex challenge, with current clinical tools sometimes insufficient to tailor a clinical response to a spectrum of patient needs. Blood biomarkers of TBI may supplement clinical assessments but currently available biomarkers have limited sensitivity and specificity. While oxidative stress is known to feature in damage mechanisms following TBI, investigation of blood biomarkers of oxidative stress has been limited. This exploratory pilot study of a subset of 18 trauma patients with TBI of varying severity, quantifies circulating concentrations of the structural damage indicators S100b, and myelin basic protein (MBP), and the biomarkers of oxidative stress hydroxynonenal (HNE), malondialdehyde (MDA), carboxy-methyl-lysine (CML), and 8-hydroxy-2'-deoxy-guanosine (8-OHDG). Significant increases in circulating S100b, MBP, and HNE were observed in TBI patient samples compared to 8 uninjured controls, and there was a significant decrease in CML. This small exploratory study supports the current literature on S100b and MBP elevation in TBI, and reveals potential for the use of peripheral oxidative stress markers to assist in determination of TBI severity. Further investigation is required to validate results and confirm trends.

Topics: Adult; Aldehydes; Biomarkers; Brain Injuries, Traumatic; Female; Humans; Male; Myelin Basic Protein; Oxidative Stress; Pilot Projects; Prospective Studies; S100 Calcium Binding Protein beta Subunit; Treatment Outcome

Lipid peroxidation (LP) is a key contributor to the pathophysiology of traumatic brain injury (TBI). Traditional antioxidant therapies are intended to scavenge the free radicals responsible for either initiation or propagation of LP. A more recently explored approach involves scavenging the terminal LP breakdown products that are highly reactive and neurotoxic carbonyl compounds, 4-hydroxynonenal (4-HNE) and acrolein (ACR), to prevent their covalent modification and rendering of cellular proteins nonfunctional leading to loss of ionic homeostasis, mitochondrial failure, and subsequent neuronal death. Phenelzine (PZ) is a U.S. Food and Drug Administration-approved monoamine oxidase (MAO) inhibitor (MAO-I) used for treatment of refractory depression that possesses a hydrazine functional group recently discovered by other investigators to scavenge reactive carbonyls. We hypothesized that PZ will protect mitochondrial function and reduce markers of oxidative damage by scavenging LP-derived aldehydes. In a first set of in vitro studies, we found that exogenous application of 4-HNE or ACR significantly reduced respiratory function and increased markers of oxidative damage (p < 0.05) in isolated noninjured rat brain cortical mitochondria, whereas PZ pre-treatment significantly prevented mitochondrial dysfunction and oxidative modification of mitochondrial proteins in a concentration-related manner (p < 0.05). This effect was not shared by a structurally similar MAO-I, pargyline, which lacks the hydrazine group, confirming that the mitochondrial protective effects of PZ were related to its carbonyl scavenging and not to MAO inhibition. In subsequent in vivo studies, we documented that PZ treatment begun at 15 min after controlled cortical impact TBI significantly attenuated 72-h post-injury mitochondrial respiratory dysfunction. The cortical mitochondrial respiratory protection occurred together with a significant increase in cortical tissue sparing.

Topics: Acrolein; Aldehydes; Animals; Brain Injuries, Traumatic; Cerebral Cortex; Disease Models, Animal; Male; Mitochondria; Monoamine Oxidase Inhibitors; Neuroprotective Agents; Phenelzine; Rats; Rats, Sprague-Dawley

Gastrointestinal dysfunction is one of several physiologic complications in patients with traumatic brain injury (TBI). TBI can result in increased intestinal permeability resulting from apoptosis of intestinal epithelial cells, which contain a large number of mitochondria for persisting barrier function. Autophagy of damaged mitochondria (mitophagy) controls the quality of the mitochondria and regulates cellular homeostasis. However, the exact mechanism of mitophagy that underlies the pathological changes induced by TBI is unknown. Here, we report that mitophagy decreases the intestinal epithelial cell damage and apoptosis that are activated in a rat model of controlled cortical impact (CCI). CCI-induced mitophagy is associated with an increase in 3-nitrotyrosine and 4-hydroxynonenal, indicating that oxidative stress may increase in response to mitochondrial disturbance. CCI also results in the expression of the tight junction proteins zonula occludens-1 (ZO-1) and occludin, which may regulate the in vivo intestinal hyperpermeability induced by CCI. Additionally, CCI-induced mitophagy was shown to be mediated by the oxidative stress-related extracellular signal-regulated kinase (ERK)/nuclear factor-erythroid2-like2 (Nrf2)/heme oxygenase-1 (HO-1) signaling pathway, which may serve to reduce the apoptosis induced by oxidative stress. These results suggest that CCI-induced mitophagy serves to diminish apoptosis-mediated intestinal epithelial cell damage and to improve intestinal permeability, via ERK/Nrf2/HO-1 signaling. These findings may be useful in the design of rational approaches for the prevention and treatment of symptoms associated with TBI.

Topics: Aldehydes; Animals; Brain Injuries, Traumatic; Epithelial Cells; Extracellular Signal-Regulated MAP Kinases; Heme Oxygenase-1; Intestinal Mucosa; Male; Mitophagy; NF-E2-Related Factor 2; Oxidative Stress; Rats; Rats, Sprague-Dawley; Signal Transduction; Tyrosine

Injury severity in blast induced Traumatic Brain Injury (bTBI) increases with blast overpressure (BOP) and impulse in dose-dependent manner. Pure primary blast waves were simulated in compressed gas shock-tubes in discrete increments. Present work demonstrates 24 hour survival of rats in 0-450 kPa (0-800 Pa∙s impulse) range at 10 discrete levels (60, 100, 130, 160, 190, 230, 250, 290, 350 and 420 kPa) and determines the mortality rate as a non-linear function of BOP. Using logistic regression model, predicted mortality rate (PMR) function was calculated, and used to establish TBI severities. We determined a BOP of 145 kPa as upper mild TBI threshold (5% PMR). Also we determined 146-220 kPa and 221-290 kPa levels as moderate and severe TBI based on 35%, and 70% PMR, respectively, while BOP above 290 kPa is lethal. Since there are no standards for animal bTBI injury severity, these thresholds need further refinements using histopathology, immunohistochemistry and behavior. Further, we specifically investigated mild TBI range (0-145 kPa) using physiological (heart rate), pathological (lung injury), immuno-histochemical (oxidative/nitrosative and blood-brain barrier markers) as well as blood borne biomarkers. With these additional data, we conclude that mild bTBI occurs in rats when the BOP is in the range of 85-145 kPa.

Topics: Aldehydes; Animals; Blast Injuries; Blood-Brain Barrier; Bradycardia; Brain; Brain Injuries, Traumatic; Explosions; Lung Injury; Male; Microvessels; NADPH Oxidases; Nitric Oxide Synthase Type II; Nitrosative Stress; Rats, Sprague-Dawley; Tyrosine

Traumatic brain injury (TBI) is a major cause of death and disability worldwide. Neuronal apoptosis in the hippocampus has been detected after TBI. The hippocampal dysfunction may result in cognitive deficits in learning, memory, and spatial information processing. Our previous studies demonstrated that a p53 inhibitor, pifithrin-α oxygen analogue (PFT-α (O)), significantly reduced cortical cell death, which is substantial following controlled cortical impact (CCI) TBI, and improved neurological functional outcomes via anti-apoptotic mechanisms. In the present study, we examined the effect of PFT-α (O) on CCI TBI-induced hippocampal cellular pathophysiology in light of this brain region's role in memory. To investigate whether p53-dependent apoptosis plays a role in hippocampal neuronal loss and associated cognitive deficits and to define underlying mechanisms, SD rats were subjected to experimental CCI TBI followed by the administration of PFT-α or PFT-α (O) (2mg/kg, i.v.) or vehicle at 5h after TBI. Magnetic resonance imaging (MRI) scans were acquired at 24h and 7days post-injury to assess evolving structural hippocampal damage. Fluoro-Jade C was used to stain hippocampal sub-regions, including CA1 and dentate gyrus (DG), for cellular degeneration. Neurological functions, including motor and recognition memory, were assessed by behavioral tests at 7days post injury. p53, p53 upregulated modulator of apoptosis (PUMA), 4-hydroxynonenal (4-HNE), cyclooxygenase-IV (COX IV), annexin V and NeuN were visualized by double immunofluorescence staining with cell-specific markers. Levels of mRNA encoding for caspase-3, p53, PUMA, Bcl-2, Bcl-2-associated X protein (BAX) and superoxide dismutase (SOD) were measured by RT-qPCR. Our results showed that post-injury administration of PFT-α and, particularly, PFT-α (O) at 5h dramatically reduced injury volumes in the ipsilateral hippocampus, improved motor outcomes, and ameliorated cognitive deficits at 7days after TBI, as evaluated by novel object recognition and open-field test. PFT-α and especially PFT-α (O) significantly reduced the number of FJC-positive cells in hippocampus CA1 and DG subregions, versus vehicle treatment, and significantly decreased caspase-3 and PUMA mRNA expression. PFT-α (O), but not PFT-α, treatment significantly lowered p53 and elevated SOD2 mRNA expression. Double immunofluorescence staining demonstrated that PFT-α (O) treatment decreased p53, annexin V and 4-HNE positive neurons in the hippoc

Topics: Aldehydes; Animals; Annexin A5; Apoptosis Regulatory Proteins; Benzothiazoles; Brain; Brain Injuries, Traumatic; Cognition Disorders; Disease Models, Animal; Electron Transport Complex IV; Exploratory Behavior; Fluoresceins; Magnetic Resonance Imaging; Male; Oxygen; Rats; Rats, Sprague-Dawley; Recognition, Psychology; RNA, Messenger; Time Factors; Toluene; Tumor Suppressor Protein p53