Epigenetic modifications such as DNA methylation, histone post-translational modifications, non-coding RNA are reversible, heritable alterations which are induced by environmental stimuli. Major risk factors of diabetes and diabetic complications including hyperglycemia, oxidative stress and advanced glycation end products, can lead to abnormal epigenetic modifications in retinal vascular endothelial cells and retinal pigment epithelium cells. Epigenetic mechanisms are involved in the pathogenesis of macular edema and neovascularization of diabetic retinopathy (DR), as well as diabetic metabolic memory. The heritable nature of epigenetic marks also playsakey role in familial diabetes mellitus. Further elucidation of epigenetic mechanisms in DR can open the way for the discovery of novel therapeutic targets to prevent DR progression.
To perform a meta-analysis of single nucleotide polymorphism needs to calculate gene frequency. This paper employs allele model as an example to introduce how to calculate gene frequency and display the process of a meta-analysis of single nucleotide polymorphism data using Review Manager 5.3 software.
Retinal neuronal cells are crucial in the formation of vision. Injury or death of these cells may lead to irreversible damage to visual function due to their low regenerative capacity. The P2X7 receptor is a trimeric adenosine triphosphate (ATP)-gated cation channel. Recent studies have shown that P2X7 receptor plays a role in retinal neuronal death. In a series of animal models, when exposed to conditions of hypoxia or ischemia, elevated ocular pressure, trauma and exogenous agonists, P2X7 receptor activated by extracellular ATP can cause death of retinal neuronal cells such as retinal ganglion cells and photoreceptor cells through direct or indirect pathways. Blocking the expression and function of P2X7 receptor by its specific antagonist and gene knocking-out, the loss of retinal neuronal cells is significantly attenuated. P2X7 receptor may become a potential novel neuroprotective target for diseases related to the loss of retinal neurons.
Idiopathic intracranial hypertension (IIH) is a neurological disease, characterized by increased intracranial pressure and papilledema, and often associated with headache, transient loss of vision and pulsatile tinnitus. IIH typically occurs in women of childbearing age. Over 90.0% of patients are with obesity or over weighted. Loss of sensory visual function is the major morbidity associated with IIH and some patients even develop into blindness. Most patients will have varied degrees of visual impairment, or even a few become blind. Frisén grading system, visual field examination and spectral-domain optical coherence tomography can be used to evaluate and monitor the IIH papilledema functionally and morphologically. In recent years, IIH treatment trials in other countries confirmed that, weight loss and low-salt diet combined with acetazolamide treatment has a clear improvement for IIH patients with mild visual impairment. In-depth understanding of the etiology, clinical manifestations, diagnostic criteria and the main treatment has important clinical significance for IIH patients
Age-related macular degeneration (AMD) is one of the leading irreversible causes of blindness in China. The pathogenesis of AMD is not fully understood at present. Under various stress conditions, cellular senescence is activated, characterized by telomere shortening, mitochondrial dysfunction, DNA damage, and the release of various senescence-related secretory phenotype factors. Senescence is implicated in the pathogenesis of AMD through multiple pathways, contributing to chronic inflammation and the onset and progression of AMD. Mechanisms such as oxidative stress, lipofuscin, β amyloid protein and the membrane attack complex have become hotspots of study in the pathogenesis of AMD. The cyclic guanosine phosphate - adenosine synthase - interferon stimulating factor synthase-stimulator of interferon gene pathway has emerged as a critical signaling pathway in the early development of AMD, providing direction for further research on AMD. Currently, senolytics, selective agents targeting the induction of senescent cell apoptosis, show significant potential in the treatment of AMD. The integration of new technologies with cellular senescence may offer a novel approach to AMD treatment, and intervening in the AMD treatment through anti-cellular senescence pathways holds promising prospects.
The human hereditary retinal degeneration is one of the main cause of irreversible blindness in the world. the mechanisms leading to retinal photoreceptor degeneration are not entirely clear. However, microglia acting as innate immune monitors are found to be activated early in retinal degeneration in many retinitis pigmentosa animal models. These activated microglia are involved in phagocyte rod cell fragments of degenerated retina, and also produce high levels of cytotoxic substances such as pro-inflammatory cytokines and chemokines, which aggravate the death of adjacent healthy photoreceptor cells. It suggests that microglia activation plays an important role in photoreceptor degeneration. At the same time, a series of studies have confirmed that some drugs can prevent or reduce neuronal death and slow the occurrence and progression of retinal degeneration by interfering with abnormal activation of microglia. It is expected to be a new choice for the treatment of hereditary retinal degeneration.
Fundus neovascularization is a significant cause of ocular diseases, mainly including retinal neovascularization and choroidal neovascularization. Anti-vascular endothelial growth factor therapy, though effective, has limitations such as a short half-life, non-responsiveness, and drug resistance. 6-Phosphofructo-2-kinase/fructose-2,6-bisphosphatase 3 (PFKFB3), a key regulator of glycolysis, affects the generation of pathological blood vessels by modulating the metabolism of vascular endothelial cells. Small molecule inhibitors targeting PFKFB3 protein have been confirmed in animal and cell models to significantly inhibit pathological angiogenesis, showing good therapeutic potential. However, most of them are still in the preclinical research stage. In the future, it is necessary to further investigate the mechanism of PFKFB3 gene, optimize the specificity and safety of the inhibitors, and explore the effects of combining them with existing therapies, so as to provide new strategies for the treatment of fundus neovascular diseases.
Inherited retinal degeneration (IRD) is a group of fundus diseases characterized by a high degree of genetic heterogeneity and clinical heterogeneity, and more than 300 genetic mutations have been identified in association with IRD. Dysregulation of the intracellular second messenger cyclic guanosine monophosphate (cGMP) plays an important role in the development of IRD. cGMP participates in phototransduction process in photoreceptors. Abnormally elevated cGMP over-activate protein kinase G and cyclic nucleotide-gated channel, causing protein phosphorylation and Ca2+ overload, respectively, and these two cGMP-dependent pathways may individually or collectively drive photoreceptor degenerative lesions and death; therefore, reducing cGMP synthesis and blocking downstream signaling can be considered as treatment strategies. Investigating the molecular mechanisms of cGMP dysregulation in photoreceptor degeneration may provide a more comprehensive picture of the pathogenesis of IRD, as well as ideas for finding new therapeutic targets and designing therapeutic programs.
The neuroretinal injuries of diabetic retinopathy (DR) include retinal neuronal damage and reactive gliosis, both of which are induced by hyperglycemia and presented as early features of DR. They promote to develop mutually and accelerate the progression of DR. The molecular mechanisms study of neuronal damage mainly focuses on the alterations of extracellular environment and related signaling pathways, include inflammation, oxidative stress, endoplasmic reticulum stress, the formation of advanced glycation end products, glutamate toxicity and so on. These alterations mainly result in neuronal apoptosis and autophagy. The damaged neurons activate the glial cells with apparent changes in morphology, cell counts and the level of intracellular protein expression. In non-proliferative DR, glial cells are moderately hypertrophic and slightly increased in numbers. In proliferative DR, there is a significant rise in glial cell number with enhanced level of inflammatory factors and vascular active substances which lead a further neuronal damage. Signaling pathways of extracellular signal-regulated kinase 1/2, c-Fos and p38 mitogen-activated protein kinase are associated with their activation. Researches on the molecular mechanisms and signaling pathways of the DR will promote controlling the DR progression at the cellular level.
Vitrectomy combined with internal limiting membrane (ILM) peeling and vitreous tamponade is a conventional method for treating macular hole (MH), but the visual acuity and MH closure rate remains to be further improved. After removal of posterior vitreous cortex, the ILM is grasped with an ILM forceps and peeled off in a circular fashion for approximately 1 disc diameters around the MH. During the circumferential peeling, the ILM is not removed completely from the retina but is left attached to the edges of the MH. The ILM was then massaged gently over the MH from all sides until the ILM became inverted and then peel all other ILM within vascular arcades. Inverted ILM flap technique is one of the important improvement methods in MH vitrectomy, especially for MH with large diameter and unhealed MH after ILM peeling. Compared with conventional vitrectomy combined with ILM peeling, inverted ILM flap technique can enhance MH closure and improve visual acuity. Due to lack of large sample observation in clinical trials of inverted ILM flap technique, we still need more cases and longer follow-up of this technology to more accurately evaluate the effectiveness and safety of this technique.