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Microglia also constantly monitor neuronal functions through direct somatic contacts via their microglial processes, and exert neuroprotective effects when needed. [ 10 ] [ 11 ] The brain and spinal cord, which make up the CNS, are not usually accessed directly by pathogenic factors in the body's circulation due to a series of endothelial cells ...
Due to their role in phagocytosis, macrophages are involved in many diseases of the immune system. For example, they participate in the formation of granulomas, inflammatory lesions that may be caused by a large number of diseases. Some disorders, mostly rare, of ineffective phagocytosis and macrophage function have been described, for example ...
Tumor-associated macrophages/microglia are the main infiltrate in gliomas, comprising up to 40% of the tumor mass. [22] TAMs are either of peripheral origin (macrophages) or representing brain-intrinsic, yolk sac-derived microglia, that create a supportive stroma for neoplastic cell expansion and invasion. [21]
Macrophages are diffusely scattered in the connective tissue and in liver (Kupffer cells), spleen and lymph nodes (sinus histiocytes), lungs (alveolar macrophages), and central nervous system (microglia). The half-life of blood monocytes is about 1 day, whereas the life span of tissue macrophages is several months or years.
Micrograph showing gliosis in the cerebellum. Reactive astrocytes on the left display severe proliferation and domain overlap. Reactive astrogliosis is the most common form of gliosis and involves the proliferation of astrocytes, a type of glial cell responsible for maintaining extracellular ion and neurotransmitter concentrations, modulating synapse function, and forming the blood–brain ...
Various cell types in the brain may produce cytokines and chemokines such as microglia, astrocytes, endothelial cells, and other glial cells. Physiologically, chemokines and cytokines function as neuromodulators that regulate inflammation and development. In the healthy brain, cells secrete cytokines to produce a local inflammatory environment ...
Tumor necrosis factor (TNF), formerly known as TNF-α, is a chemical messenger produced by the immune system that induces inflammation. [5] TNF is produced primarily by activated macrophages, and induces inflammation by binding to its receptors on other cells. [6]
Macrophage polarization is a process by which macrophages adopt different functional programs in response to the signals from their microenvironment. This ability is connected to their multiple roles in the organism: they are powerful effector cells of the innate immune system, but also important in removal of cellular debris, embryonic development and tissue repair.