Track 12: Neuroimmunology

Sub Tracks:

 Immune System and the Nervous System, Microglia and Immune Cells in the CNS,Neuroinflammation, Blood-Brain Barrier Dysfunction, Autoimmune Diseases of the CNS, Neurodegenerative Diseases and Immune System Involvement, Role of Cytokines and Chemokines in Neuroinflammation

Neuroimmunology is the study of the interactions between the nervous system and the immune system. It focuses on how immune cells and molecules influence the function of the brain and spinal cord, and conversely, how the nervous system regulates immune responses. The field is particularly important for understanding how immune system dysfunction contributes to neurological diseases such as neuroinflammatory, neurodegenerative, and autoimmune diseases.

1. The Immune System and the Nervous System

Innate Immunity in the CNS: The innate immune system is the first line of defense and is essential for responding to injury and infection in the brain. Microglia, the resident immune cells of the central nervous system (CNS), play a crucial role in maintaining homeostasis, clearing dead cells, and responding to injury or disease.

Adaptive Immunity in the CNS: Involves T cells and B cells, which are part of the adaptive immune system. Under normal conditions, these cells do not typically enter the brain but may be recruited during neuroinflammatory or autoimmune responses.

2. The Blood-Brain Barrier (BBB)

The blood-brain barrier is a selective permeability barrier that regulates the movement of cells and molecules between the bloodstream and the brain. It serves to protect the CNS from pathogens, toxins, and excessive immune cells.

BBB Dysfunction: In various neuroinflammatory and neurodegenerative diseases, such as multiple sclerosis (MS), the BBB becomes compromised, allowing immune cells to enter the brain and cause damage.

3. Microglia and Astrocytes: The Immune Cells of the CNS

Microglia: These are the resident macrophage-like cells of the CNS, crucial for detecting injury, infection, and disease. Microglia are involved in neuroinflammation and can either protect or harm neurons depending on the activation state.

Astrocytes: Astrocytes play an important role in supporting neurons, maintaining the blood-brain barrier, and modulating immune responses in the brain. When activated in disease conditions, they can contribute to neuroinflammation.

4. Neuroinflammation

Acute vs. Chronic Neuroinflammation:

Acute Neuroinflammation: This is a temporary, protective response to injury, infection, or disease. It usually resolves once the threat is eliminated.

Chronic Neuroinflammation: Long-term or unresolved inflammation in the CNS can contribute to neurodegenerative diseases like Alzheimer’s disease, Parkinson’s disease, and multiple sclerosis.

Cytokines and Chemokines: These small signaling molecules play a critical role in regulating immune responses in the CNS. Inflammatory cytokines, such as TNF-α, IL-1β, and IL-6, promote inflammation, while chemokines recruit immune cells to the site of inflammation.

5. Autoimmune Diseases of the CNS

Multiple Sclerosis (MS): A chronic autoimmune disorder where the immune system attacks and damages the myelin sheath that insulates nerve fibers in the CNS. T cells and B cells play significant roles in the disease process, leading to demyelination, inflammation, and neuronal damage.

Neuromyelitis Optica (NMO): An autoimmune disorder affecting the optic nerves and spinal cord, often caused by antibodies against the aquaporin-4 channel, which is critical for maintaining the blood-brain barrier.

Guillain-Barré Syndrome (GBS): An autoimmune disease that affects the peripheral nervous system (PNS), often triggered by infections. The immune system mistakenly attacks peripheral nerves, leading to muscle weakness and paralysis.

6. Neurodegenerative Diseases and Immune System Involvement

Alzheimer’s Disease (AD): Chronic inflammation, particularly the activation of microglia, plays a role in the progression of Alzheimer's disease. The accumulation of amyloid-beta plaques and tau tangles triggers an immune response that can lead to neuronal damage.

Parkinson’s Disease (PD): Neuroinflammation is a key feature of PD, with microglia activation contributing to the degeneration of dopaminergic neurons in the substantia nigra.

Amyotrophic Lateral Sclerosis (ALS): ALS, a neurodegenerative disorder that affects motor neurons, is associated with microglial activation and inflammation, which exacerbate motor neuron death.