Interleukin-6 (IL-6) is a cytokine originally identified as a B-cell differentiation factor, playing a critical role in immune response and various physiological systems, including the central nervous system (CNS). IL-6 is part of the neuropoietin family, which includes cytokines such as IL-11, IL-27, and others. It binds to class I cytokine receptors, including gp130, and can signal through trans-signaling via soluble receptors. IL-6 is expressed in various CNS cells, including neurons, astrocytes, microglia, and endothelial cells, and is involved in neurogenesis, gliogenesis, and neuroinflammation. It has been implicated in several CNS diseases, including Alzheimer's disease, multiple sclerosis, stroke, and trauma. IL-6 also plays a role in normal brain function, such as regulating body weight, food intake, and energy expenditure. In disease contexts, IL-6 can have both protective and detrimental effects, depending on the condition and the cellular environment. For example, in stroke, IL-6 may have neuroprotective effects, while in multiple sclerosis, it can contribute to neuroinflammation. IL-6 is also involved in the regulation of immune responses, including the transition from innate to adaptive immunity. The role of IL-6 in the CNS is complex, with both pro-inflammatory and neuroprotective functions. Therapeutic approaches targeting IL-6, including its receptors and signaling pathways, are being explored for the treatment of various neurological disorders.Interleukin-6 (IL-6) is a cytokine originally identified as a B-cell differentiation factor, playing a critical role in immune response and various physiological systems, including the central nervous system (CNS). IL-6 is part of the neuropoietin family, which includes cytokines such as IL-11, IL-27, and others. It binds to class I cytokine receptors, including gp130, and can signal through trans-signaling via soluble receptors. IL-6 is expressed in various CNS cells, including neurons, astrocytes, microglia, and endothelial cells, and is involved in neurogenesis, gliogenesis, and neuroinflammation. It has been implicated in several CNS diseases, including Alzheimer's disease, multiple sclerosis, stroke, and trauma. IL-6 also plays a role in normal brain function, such as regulating body weight, food intake, and energy expenditure. In disease contexts, IL-6 can have both protective and detrimental effects, depending on the condition and the cellular environment. For example, in stroke, IL-6 may have neuroprotective effects, while in multiple sclerosis, it can contribute to neuroinflammation. IL-6 is also involved in the regulation of immune responses, including the transition from innate to adaptive immunity. The role of IL-6 in the CNS is complex, with both pro-inflammatory and neuroprotective functions. Therapeutic approaches targeting IL-6, including its receptors and signaling pathways, are being explored for the treatment of various neurological disorders.