Cytokines and Chemokines in Immune Responses and Disease Pathogenesis

Cytokines and Chemokines: The Crossroads of Immune Responses and Disease Pathogenesis

Cytokines and chemokines are small proteins that act as signaling molecules at picomolar or nanomolar concentrations to regulate immune responses throughout the body. They play a crucial role in maintaining immune surveillance, facilitating leukocyte traffic, and recruiting other inflammatory factors. These molecules are involved in the regulation of CNS-immune system interactions and are produced not only by white blood cells but also by various other cells in response to pathogens or abnormal cells.

Cytokines

Cytokines are a diverse group of pro- or anti-inflammatory factors that are involved in regulating cell survival, differentiation, and activation. They function by binding to specific receptors on the surface of target cells, triggering a cascade of signaling events that regulate various cellular functions such as cell adhesion, phagocytosis, cytokine secretion, cell activation, cell proliferation, cell survival, and cell death.

Chemokines

Chemokines belong to the family of cytokines and are involved in the induction of cell migration. They are classified into four families based on the positioning of the N-terminal cysteine residue: CC, CXC, C, and CX3C. The most common chemokines belong to the CC and CXC families. These small proteins (8–12 kDa) achieve their effects by binding to G-protein coupled cell-surface receptors. CCR receptors bind only CCL chemokine ligands, while CXCR receptors bind CXCL ligands[144].

Cytokines and Chemokines in Neuroinflammation and Disease Pathogenesis

In the context of neuroinflammation, cytokines and chemokines play a significant role in the development of neurodegenerative diseases such as bacterial Lyme neuroborreliosis, human immunodeficiency virus encephalitis, and neuropathic pain. They can affect neuroinflammation and disease pathogenesis by inducing cell migration, mediating neuronal and glial cell injury and death, and perpetuating inflammation through a feedback loop.

Cytokines and Chemokines in Osteoarthritis Pathogenesis

Osteoarthritis (OA) is a common musculoskeletal condition that affects all joint tissues, including cartilage, bone, and connective tissue. A disturbed cytokine balance in favor of proinflammatory cytokines is a well-established factor in the pathogenesis of OA. The most important inflammatory mediators in OA are IL-1β, TNF-α, and IL-6, which activate a variety of signaling pathways and promote the secretion of inflammatory factors. Chemokines, stimulated by cytokines, attract inflammatory cells to the joint, further promoting inflammation and disease progression.

In summary, cytokines and chemokines are essential for regulating immune responses and maintaining immune surveillance in the body. Their dysregulation can lead to pathological states, such as neuroinflammation and OA, which can exacerbate disease progression. Understanding the role and mechanisms of these molecules can provide insights into potential therapeutic targets for various diseases.