Effects of controlled cortical impact and docosahexaenoic acid on rat pup fatty acid profiles

Progress in research on the role of clinical nutrition in treating traumatic brain injury affecting the neurovascular unit

The neurovascular unit (NVU) is composed of neurons, glial cells, and blood vessels. NVU dysfunction involves the processes of neuroinflammation, and microcirculatory disturbances, as well as neuronal injury after traumatic brain injury (TBI). Traditional anti-inflammatory drugs have limited efficacy in improving the prognosis of TBI. Thus, treatments that target NVU dysfunction may provide a breakthrough. A large number of clinical studies have shown that the nutritional status of patients with TBI was closely related to their conditions and prognoses. Nutrient complexes and complementary therapies for the treatment of TBI are therefore being implemented in many preclinical studies. Importantly, the mechanism of action for this treatment may be related to repair of NVU dysfunction by ensuring adequate omega-3 fatty acids, curcumin, resveratrol, apigenin, vitamins, and minerals. These nutritional supplements hold promise for translation to clinical therapy. In addition, dietary habits also play an important role in the rehabilitation of TBI. Poor dietary habits may worsen the pathology and prognosis of TBI. Adjusting dietary habits, especially with a ketogenic diet, may improve outcomes in patients with TBI. This article discusses the impact of clinical nutrition on NVU dysfunction after TBI, focusing on nutritional complexes and dietary habits.

Docosahexaenoic acid decreased inflammatory gene expression, but not 18-kDa translocator protein binding, in rat pup brain after controlled cortical impact

BACKGROUND

Traumatic brain injury is the leading cause of acquired neurologic disability in children. In our model of pediatric traumatic brain injury, controlled cortical impact (CCI) in rat pups, docosahexaenoic acid (DHA) improved lesion volume and cognitive testing as late as postinjury day (PID) 50. Docosahexaenoic acid decreased proinflammatory messenger RNA (mRNA) in microglia and macrophages at PIDs 3 and 7, but not 30. We hypothesized that DHA affected inflammatory markers differentially relative to impact proximity, early and persistently after CCI.

METHODS

To provide a temporal snapshot of regional neuroinflammation, we measured 18-kDa translocator protein (TSPO) binding using whole brain autoradiography at PIDs 3, 7, 30, and 50. Guided by TSPO results, we measured mRNA levels in contused cortex and underlying hippocampus for genes associated with proinflammatory and inflammation-resolving states at PIDs 2 and 3.

RESULTS

Controlled cortical impact increased TSPO binding at all time points, most markedly at PID 3 and in regions closest to impact, not blunted by DHA. Controlled cortical impact increased cortical and hippocampal mRNA proinflammatory markers, blunted by DHA at PID 2 in hippocampus.

CONCLUSION

Controlled cortical impact increased TSPO binding in the immature brain in a persistent manner more intensely with more severe injury, not altered by DHA. Controlled cortical impact increased PIDs 2 and 3 mRNA levels of proinflammatory and inflammation-resolving genes. Docosahexaenoic acid decreased proinflammatory markers associated with inflammasome activation at PID 2. We speculate that DHA's salutary effects on long-term outcomes result from early effects on the inflammasome. Future studies will examine functional effects of DHA on microglia both early and late after CCI.

Microglial Metabolism After Pediatric Traumatic Brain Injury - Overlooked Bystanders or Active Participants?

Microglia play an integral role in brain development but are also crucial for repair and recovery after traumatic brain injury (TBI). TBI induces an intense innate immune response in the immature, developing brain that is associated with acute and chronic changes in microglial function. These changes contribute to long-lasting consequences on development, neurologic function, and behavior. Although alterations in glucose metabolism are well-described after TBI, the bulk of the data is focused on metabolic alterations in astrocytes and neurons. To date, the interplay between alterations in intracellular metabolic pathways in microglia and the innate immune response in the brain following an injury is not well-studied. In this review, we broadly discuss the microglial responses after TBI. In addition, we highlight reported metabolic alterations in microglia and macrophages, and provide perspective on how changes in glucose, fatty acid, and amino acid metabolism can influence and modulate the microglial phenotype and response to injury.

Impact of pediatric traumatic brain injury on hippocampal neurogenesis

Traumatic brain injury (TBI) is a major cause of mortality and morbidity in the pediatric population. With advances in medical care, the mortality rate of pediatric TBI has declined. However, more children and adolescents are living with TBI-related cognitive and emotional impairments, which negatively affects the quality of their life. Adult hippocampal neurogenesis plays an important role in cognition and mood regulation. Alterations in adult hippocampal neurogenesis are associated with a variety of neurological and neurodegenerative diseases, including TBI. Promoting endogenous hippocampal neurogenesis after TBI merits significant attention. However, TBI affects the function of neural stem/progenitor cells in the dentate gyrus of hippocampus, which results in aberrant migration and impaired dendrite development of adult-born neurons. Therefore, a better understanding of adult hippocampal neurogenesis after TBI can facilitate a more successful neuro-restoration of damage in immature brains. Secondary injuries, such as neuroinflammation and oxidative stress, exert a significant impact on hippocampal neurogenesis. Currently, a variety of therapeutic approaches have been proposed for ameliorating secondary TBI injuries. In this review, we discuss the uniqueness of pediatric TBI, adult hippocampal neurogenesis after pediatric TBI, and current efforts that promote neuroprotection to the developing brains, which can be leveraged to facilitate neuroregeneration.