Neuroimmunology

Neuroimmunology is a field combining neuroscience, the study of the nervous system, and immunology, the study of the immune system. Neuroimmunologists seek to better understand the interactions of these two complex systems during development, homeostasis, and response to injuries. A long-term goal of this rapidly developing research area is to further develop our understanding of the pathology of certain neurological diseases, some of which have no clear etiology. In doing so, neuroimmunology contributes to development of new pharmacological treatments for several neurological conditions. Many types of interactions involve both the nervous and immune systems including the physiological functioning of the two systems in health and disease, malfunction of either and or both systems that leads to disorders, and the physical, chemical, and environmental stressors that affect the two systems on a daily basis. Neuroimmunology is a field combining neuroscience, the study of the nervous system, and immunology, the study of the immune system. Neuroimmunologists seek to better understand the interactions of these two complex systems during development, homeostasis, and response to injuries. A long-term goal of this rapidly developing research area is to further develop our understanding of the pathology of certain neurological diseases, some of which have no clear etiology. In doing so, neuroimmunology contributes to development of new pharmacological treatments for several neurological conditions. Many types of interactions involve both the nervous and immune systems including the physiological functioning of the two systems in health and disease, malfunction of either and or both systems that leads to disorders, and the physical, chemical, and environmental stressors that affect the two systems on a daily basis. Neural targets that control thermogenesis, behavior, sleep, and mood can be affected by pro-inflammatory cytokines which are released by activated macrophages and monocytes during infection. Within the central nervous system production of cytokines has been detected as a result of brain injury, during viral and bacterial infections, and in neurodegenerative processes. From the US National Institute of Health: 'Despite the brain's status as an immune privileged site, an extensive bi-directional communication takes place between the nervous and the immune system in both health and disease. Immune cells and neuroimmune molecules such as cytokines, chemokines, and growth factors modulate brain function through multiple signaling pathways throughout the lifespan. Immunological, physiological and psychological stressors engage cytokines and other immune molecules as mediators of interactions with neuroendocrine, neuropeptide, and neurotransmitter systems. For example, brain cytokine levels increase following stress exposure, while treatments designed to alleviate stress reverse this effect. 'Neuroinflammation and neuroimmune activation have been shown to play a role in the etiology of a variety of neurological disorders such as stroke, Parkinson's and Alzheimer's disease, multiple sclerosis, pain, and AIDS-associated dementia. However, cytokines and chemokines also modulate CNS function in the absence of overt immunological, physiological, or psychological challenges. For example, cytokines and cytokine receptor inhibitors affect cognitive and emotional processes. Recent evidence suggests that immune molecules modulate brain systems differently across the lifespan. Cytokines and chemokines regulate neurotrophins and other molecules critical to neurodevelopmental processes, and exposure to certain neuroimmune challenges early in life affects brain development. In adults, cytokines and chemokines affect synaptic plasticity and other ongoing neural processes, which may change in aging brains. Finally, interactions of immune molecules with the hypothalamic-pituitary-gonadal system indicate that sex differences are a significant factor determining the impact of neuroimmune influences on brain function and behavior.' Recent research demonstrates that reduction of lymphocyte populations can impair cognition in mice, and that restoration of lymphocytes restores cognitive abilities. Epigenetic medicine encompasses a new branch of neuroimmunology that studies the brain and behavior. This new branch has already provided unique insights into the mechanisms underlying brain development, evolution, neuronal and network plasticity and homeostasis, senescence, the etiology of diverse neurological diseases and neural regenerative processes. This new study is leading to the discovery of environmental stressors that dictate initiation of specific neurological disorders and specific disease biomarkers. The goal of this is to 'promote accelerated recovery of impaired and seemingly irrevocably lost cognitive, behavioral, sensorimotor functions through epigenetic reprogramming of endogenous regional neural stem cells'. Understanding epigenetic medicine is important to understanding possible future pharmacological treatments. Many of the immediate gaps in knowledge are attributed to basic lack of understanding of gene expression and regulation and are thus the limiting factors for creating advanced treatments or cures to many diseases. To better understand these processes, neuroimmunological experiments are being created and tested to once and for all amass a more complete anthology of knowledge pertaining to the complex interactions between the nervous and immune systems along with that of gene expression. While some disorders may affect the nervous and immune systems independently of one another, it is impossible to truly understand neuroimmnulogical science without a complex understanding of how each system works independently and also how they work together. Several studies have shown that regulation of stem cell maintenance and the subsequent fate determinations are quite complex. The complexity of determining the fate of a stem cell can be best understood by knowing the 'circuitry employed to orchestrate stem cell maintenance and progressive neural fate decisions'. Neural fate decisions include the utilization of multiple neurotransmitter signal pathways along with the use of epigenetic regulators. The advancement of neuronal stem cell differentiation and glial fate decisions must be orchestrated timely to determine subtype specification and subsequent maturation processes including myelination. Neurodevelopmental disorders result from impairments of growth and development of the brain and nervous system and lead to many disorders. Examples of these disorders include Asperger syndrome, traumatic brain injury, communication, speech and language disorders, genetic disorders such as fragile-X syndrome, Down syndrome, epilepsy, and fetal alcohol syndrome. Studies have shown that autism spectrum disorders (ASDs) may present due to basic disorders of epigenetic regulation. Other neuroimmunological research has shown that deregulation of correlated epigenetic processes in ASDs can alter gene expression and brain function without causing classical genetic lesions which are more easily attributable to a cause and effect relationship. These findings are some of the numerous recent discoveries in previously unknown areas of gene misexpression.