ABSTRACT
Recent evidence has demonstrated that the global public health burden of myopia is rising rapidly. Highly myopic eyes are associated with increased frequency of eye disorders that can lead to irreversible visual impairment. With recent technological advancement in ophthalmic imaging modalities, various macular complications associated with pathologic myopia are being elucidated. The development and progression of myopic chorioretinal atrophy, myopic macular neovascularization, myopic traction maculopathy and dome-shaped macula are vision-threatening myopic macular diseases. In order to overcome the challenges in managing patients with pathologic myopia, it is important to have a complete understanding in the natural course of these myopic macular diseases. Standardising the classification criteria of pathologic myopia is essential for enhancing clinical surveillance. Personalised pharmaceutical therapy and surgical interventions will help to optimise the treatment outcomes in patients suffering from these myopic macular diseases.
Subject(s)
Macula Lutea , Myopia, Degenerative , Retinal Degeneration , Retinal Diseases , Humans , Myopia, Degenerative/complications , Myopia, Degenerative/diagnosis , Myopia, Degenerative/epidemiology , Retrospective Studies , Retinal Diseases/etiology , Macula Lutea/pathology , Vision Disorders , Tomography, Optical CoherenceABSTRACT
AIM: To elucidate the role of Na+ /H+ exchanger 3 (NHE3) in sodium-glucose co-transporter 1 (SGLT1)-mediated small intestinal brush border membrane (BBM) glucose absorption and its functional implications in type 2 diabetes mellitus (T2DM). MATERIALS AND METHODS: Human jejunal samples were obtained from patients undergoing gastrectomy. 14 C-glucose absorption was measured by liquid scintillation counting. NHE3 expression was suppressed by siRNA-mediated knockdown or augmented in Caco2 cells. Glucose and insulin tolerance in db/db and m+/db mice was assessed with oral and intraperitoneal glucose tolerance tests, and an intraperitoneal insulin tolerance test. Insulin resistance and ß-cell function were assessed using homeostatic model assessment of insulin resistance and ß-cell function. RESULTS: NHE3 expression was upregulated in db/db mouse jejunal BBM and high-glucose-treated Caco2 cells. NHE3 blockade impaired SGLT1-mediated glucose absorption in human jejunum, m+/db and db/db mouse jejunums, and Caco2 cells, via serum/glucocorticoid-regulated kinase 1 (SGK1). NHE3 knockdown suppressed SGLT1-mediated glucose uptake and reduced mRNA and protein levels of SGK1 and SGLT1, which were conversely enhanced by NHE3 overexpression. Chronic S3226 treatment diminished postprandial glucose levels and ameliorated glucose intolerance in db/db mice. CONCLUSION: NHE3 is essential in the modulation of small intestinal BBM glucose absorption. Our findings provide a rationale for future possible clinical application of NHE3 for treatment of T2DM through reducing intestinal glucose uptake and counteracting postprandial hyperglycaemia.
