TGFbeta2 effects on IOP may be transduced by TGFbeta type-I receptor-mediated changes in TM secretion of ECM-related factors such as fibronectin and PAI-1. Modulation of TGFbeta2-induced changes in the ECM may provide a novel and viable approach to the management of glaucoma.
The incidence of chronic wounds is increased among older adults, and the impact of chronic wounds on quality of life is particularly profound in this population. It is well established that wound healing slows with age. However, the basic biology underlying chronic wounds and the influence of age-associated changes on wound healing are poorly understood. Most studies have used in vitro approaches and various animal models, but observed changes translate poorly to human healing conditions. The impact of age and accompanying multi-morbidity on the effectiveness of existing and emerging treatment approaches for chronic wounds is also unknown, and older adults tend to be excluded from randomized clinical trials. Poorly defined outcomes and variables, lack of standardization in data collection, and variations in the definition, measurement, and treatment of wounds also hamper clinical studies. The Association of Specialty Professors, in conjunction with the National Institute on Aging and the Wound Healing Society, held a workshop, summarized in this paper, to explore the current state of knowledge and research challenges, engage investigators across disciplines, and identify key research questions to guide future study of age-associated changes in chronic wound healing.
Purpose. Glaucoma is a leading cause worldwide of blindness and visual impairment. Transforming growth factor-beta2 (TGFbeta2) has been implicated in the pathogenesis of primary open-angle glaucoma (POAG) based on elevated levels in glaucomatous aqueous humor and its ability to induce extracellular matrix (ECM) remodeling in the trabecular meshwork (TM). The goal of this study was to generate a rodent model of POAG using viral gene transfer of human TGFbeta2. Methods. Latent (hTGFbeta2(WT)) or active (C226S, C228S; hTGFbeta2(226/228)) TGFbeta2-encoding cDNA was cloned into the pac.Ad5.CMV.K-N.pA shuttle vector for generation of replication-deficient adenovirus. Empty adenovirus (Ad5.CMV.K-N.pA) was used as a control. Adenoviral expression of active and total TGFbeta2 was assayed in vitro by the transduction of Chinese hamster ovary and trabecular meshwork cells. BALB/cJ mice or Wistar rats were injected either intracamerally or intravitreally with the adenovectors and assessed for changes in intraocular pressure (IOP) using the rebound tonometer. At peak IOP, aqueous outflow facility and total TGFbeta2 levels in aqueous humor were measured. Mouse eye morphology was assessed by hematoxylin and eosin staining. Results. Adenoviral gene transfer of hTGFbeta2(226/228), but not hTGFbeta2(WT), to the rodent eye elevated IOP in rat (43%, P < 0.001) and mouse (110%, P < 0.001) and reduced aqueous humor outflow facility in the mouse. The TGFbeta2-induced ocular hypertension correlated with anterior segment TGFbeta2 expression levels (P < 0.0001). Conclusions. The adenoviral TGFbeta2 rodent model displays the glaucoma risk factors of elevated IOP and decreased aqueous outflow facility and may potentially serve as a model for studying glaucoma.
Until recently, very little was known about the molecular mechanisms responsible for the development of glaucoma, a leading cause of blindness worldwide. Mutations in the glaucoma gene myocilin (MYOC, GLC1A) are associated with elevated intraocular pressure and the development of autosomal dominant juvenile glaucoma and a subset of adult-onset glaucoma. MYOC is expressed in the trabecular meshwork (TM), a tissue responsible for drainage of aqueous humor from the eye, and the tissue involved in elevated intraocular pressure associated with glaucoma. To better understand the role of MYOC in glaucoma pathogenesis, we examined the expression of normal and mutant myocilin in cultured ocular (TM) and non-ocular cells as well as in the aqueous humor of patients with and without MYOC glaucoma. Normal myocilin was secreted from cultured cells, but very little to no myocilin was secreted from cells expressing five different mutant forms of MYOC. In addition, no mutant myocilin was detected in the aqueous humor of patients harboring a nonsense MYOC mutation (Q368X). Co-transfection of cultured cells with normal and mutant myocilin led to suppression of normal myocilin secretion. These studies suggest that MYOC glaucoma is due either to insufficient levels of secreted myocilin or to compromised TM cell function caused by congestion of the TM secretory pathway.
The normal gene expression profiles of the tissues in the eye are a valuable resource for considering genes likely to be involved with disease processes. We profiled gene expression in ten ocular tissues from human donor eyes using Affymetrix Human Exon 1.0 ST arrays. Ten different tissues were obtained from six different individuals and RNA was pooled. The tissues included: retina, optic nerve head (ONH), optic nerve (ON), ciliary body (CB), trabecular meshwork (TM), sclera, lens, cornea, choroid/retinal pigment epithelium (RPE) and iris. Expression values were compared with publically available Expressed Sequence Tag (EST) and RNA-sequencing resources. Known tissue-specific genes were examined and they demonstrated correspondence of expression with the representative ocular tissues. The estimated gene and exon level abundances are available online at the Ocular Tissue Database.
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