heparitin-sulfate and Glaucoma

During human embryogenesis, neural crest cells migrate to the anterior chamber of the eye and then differentiate into the inner layers of the cornea, the iridocorneal angle, and the anterior portion of the iris. When proper development does not occur, this causes iridocorneal angle dysgenesis and intraocular pressure (IOP) elevation, which ultimately results in developmental glaucoma. Here, we show that heparan sulfate (HS) deficiency in mouse neural crest cells causes anterior chamber dysgenesis, including corneal endothelium defects, corneal stroma hypoplasia, and iridocorneal angle dysgenesis. These dysfunctions are phenotypes of the human developmental glaucoma, Peters anomaly. In the neural crest cells of mice embryos, disruption of the gene encoding exostosin 1 (Ext1), which is an indispensable enzyme for HS synthesis, resulted in disturbed TGF-beta2 signaling. This led to reduced phosphorylation of Smad2 and downregulated expression of forkhead box C1 (Foxc1) and paired-like homeodomain transcription factor 2 (Pitx2), transcription factors that have been identified as the causative genes for developmental glaucoma. Furthermore, impaired interactions between HS and TGF-beta2 induced developmental glaucoma, which was manifested as an IOP elevation caused by iridocorneal angle dysgenesis. These findings suggest that HS is necessary for neural crest cells to form the anterior chamber via TGF-beta2 signaling. Disturbances of HS synthesis might therefore contribute to the pathology of developmental glaucoma.

Topics: Animals; Anterior Chamber; Cell Proliferation; Forkhead Transcription Factors; Glaucoma; Heparitin Sulfate; Homeobox Protein PITX2; Homeodomain Proteins; Integrases; Mice; Mice, Inbred C57BL; N-Acetylglucosaminyltransferases; Neural Crest; Signal Transduction; Transcription Factors; Transforming Growth Factor beta2; Wnt1 Protein

We evaluated histochemically the distribution of proteoglycans in the trabecular tissue of goniodysgenetic (developmental) glaucoma. Nine trabecular tissue specimens obtained at trabeculectomy from seven patients with goniodysgenetic glaucoma were stained with either cuprolinic blue or cupromeronic blue in combination with a series of enzyme and nitrous acid treatments. Within the extracellular matrix of the trabecular meshwork, many cupromeronic blue- or cuprolinic blue-positive filaments were observed in association with collagen fibrils, basal lamina, and basal lamina-like material. The extracellular matrices of elastin-like fibers, fine fibrillar materials, and fine granular materials were free from any reaction products. The enzyme and nitrous acid treatments disclosed that the reaction products associated with collagen fibrils represented both chondroitin sulfate and dermatan sulfate types, while those with basal lamina and basal lamina-like material represented heparan sulfate-type proteoglycans. Extensive accumulations of basal lamina-like material contained a great deal of heparan sulfate-type proteoglycans in the thick subcanalicular tissue of goniodysgenetic glaucoma. These results indicate that the class and distribution of proteoglycans in the goniodsygenetic trabecular tissues are virtually the same as that in the normal tissues. However, the large accumulation of basal lamina-like material with heparan sulfate-type proteoglycans can be one of the causes of the intraocular pressure increase in goniodysgenetic glaucoma.

Topics: Adolescent; Adult; Anterior Eye Segment; Child; Child, Preschool; Chondroitin Sulfates; Dermatan Sulfate; Glaucoma; Heparitin Sulfate; Humans; Indicators and Reagents; Indoles; Infant; Male; Organometallic Compounds; Trabecular Meshwork; Trabeculectomy