Читать книгу Graves' Orbitopathy - Группа авторов - Страница 70

Orbit connective/adipose tissue and extraocular muscles are particularly rich in GAGs, mainly chondroitin sulphate and hyaluronan (HA), an especially hydrophilic molecule. HA synthases are strongly expressed by orbital fibroblasts and upregulated in the presence of various cytokines. Furthermore, there are reports of undetectable hyaluronidase activity (the enzyme complex which degrades HA) in orbital fibroblasts in vitro [10], although the mRNA transcripts for all hyaluronidase isoforms have been detected in GO tissues ex vivo [11]. Enlargement of intraorbital tissues is largely accounted for by the accumulation of GAG and oedema within the connective tissue, both within and outside the muscles.