Glial scar shown to stimulate growth-inhibitory proteoglycans by astrocytes. Experimental reduction of TGFβ-1 and TGFβ-2 has been shown to partially reduce glial scarring. Interleukins are another potential family of scar-inducing cellular messengers. Particularly, interleukin-1, a protein produced by mononuclear phagocytes, helps to initiate the inflammatory response in astrocytes, leading to reactive astrogliosis and the formation of the glial scar. The cytokine family of glial scar inducers include interferon-γ (IFNγ) and fibroblast growth factor 2 (FGF2). IFNγ has been shown to induce astrocyte proliferation and increase the extent of glial scarring in injured brain models. Further, FGF2 production increases after injury to the
Nasal glial heterotopia there is a large amount of associated fibrosis. The lesions are usually <2 cm in greatest dimension. A trichrome stain will highlight the dual components well, with the glial tissue staining red, while the background fibrosis stains a bright blue. The glial tissue is highlighted with S100 protein and with glial fibrillary acidic protein, although the latter is much more sensitive for glial tissue. The most common missed lesion is within the nasal cavity, where a fibrosed nasal polyp may be considered. However, it does not have glial tissue. Further, a polyp usually has mucoserous glands. The lesion is frequently