How do immune cells support and shape the brain in health, disease, and aging?

Hemoglobin as a source of iron overload in multiple sclerosis: does multiple sclerosis share risk factors with vascular disorders?

Although iron is known to be essential for the normal development and health of the central nervous system, abnormal iron deposits are found in and around multiple sclerosis (MS) lesions that themselves are closely associated with the cerebral vasculature. However, the origin of this excess iron is unknown, and it is not clear whether this is one of the primary causative events in the pathogenesis of MS, or simply another consequence of the long-lasting inflammatory conditions. Here, applying a systems biology approach, we propose an additional way for understanding the neurodegenerative component of the disease caused by chronic subclinical extravasation of hemoglobin, in combination with multiple other factors including, but not limited to, dysfunction of different cellular protective mechanisms against extracellular hemoglobin reactivity and oxidative stress. Moreover, such considerations could also shed light on and explain the higher susceptibility of MS patients to a wide range of cardiovascular disorders.

Reversal of Neuronal Atrophy: Role of Cellular Immunity in Neuroplasticity and Aging

Emerging evidence indicates that neuroimmunological changes in the brain can modify intrinsic brain processes that are involved in regulating neuroplasticity. Increasing evidence suggests that in some forms of motor neuron injury, many neurons do not die, but reside in an atrophic state for an extended period of time. In mice, facial motor neurons in the brain undergo a protracted period of degeneration or atrophy following resection of their peripheral axons. Reinjuring the proximal nerve stump of the chronically resected facial nerve stimulates a robust reversal of motor neuron atrophy which results in marked increases in both the number and size of injured motor neurons in the facial motor nucleus. In this brief review, we describe research from our lab which indicates that the reversal of atrophy in this injury model is dependent on normal cellular immunity. The role of T cells in this unique form of neuroplasticity following injury and in brain aging, are discussed. The potential role of yet undiscover intrinsic actions of recombination activating genes in the brain are considered. Further research using the facial nerve reinjury model could identify molecular signals involved in neuroplasticity, and lead to new ways to stimulate neuroregenerative processes in neurotrauma and other forms of brain insult and disease.

Attenuated migration by green tea extract (−)-epigallocatechin gallate (EGCG): involvement of 67 kDa laminin receptor internalization in macrophagic cells

Inhibition of macrophagic cell migration induced by green tea polyphenol EGCG may be linked to the internalization of 67 kDa laminin receptor.

5. T cell immunity and neuroplasticity

The proneuronal effects of T cells that impact the brain occur from both T cells trafficking into the brain, and from signals in the periphery (e.g., cytokine release and regulation). Recent data indicates that neuroimmunological changes in the brain can modify intrinsic brain processes that are involved in regulating neuroplasticity (e.g., T-cell/microglial interactions, neurotrophins, neurogenesis). We describe: 1) work from our lab and others showing that injury-induced loss of neuronal phenotype and reversal of motor neuron atrophy are associated with normal T cell immunity, and; 2) research indicating that these and other neuroimmunological processes may be generalizable to mechanisms of neuroplasticity involved in cognitive and emotional behavior. These findings are discussed in relation to our lab's working hypothesis, that T cell immunosenesence may contribute to alterations in brain neuroplasticity related to aging. Greater understanding of the role of adaptive T cell immunity on neuroplasticity could have important clinical implications for developing novel treatment strategies for neurodegenerative diseases (e.g., Alzheimer's) and brain injury (e.g., stroke, trauma).