The hallmark lesions of age-related macular degeneration (AMD) are drusen and basal linear deposit which are lipid substances deposited in Bruch membrane or the compartment on the Bruch membrane. There is a prevailing hypothesis that lipid and its oxidized derivant deposited in retina may have important roles in the pathogenesis of AMD. Lipid oxidation products are toxic, may affect the adjacent cells, induce inflammation, and trigger neovascularization.7-ketocholestoral (7KCh), a naturally occurring oxidized form of cholesterol, had been found to be toxic to retinal cells and able to induce chronic inflammation, which may play a critical role in the development of AMD. However the precise mechanism remains to be elucidated. Thus we will make a brief review of 7KCh and its association with AMD.
ObjectiveTo observe the expression of vascular endothelial growth factor (VEGF), fibrogenic mediators and inflammatory mediators in the retinal pigment epithelium (RPE)-choroid complex of mice with experimental subretinal fibrosis. MethodsBy subretinal injection of inflammatory macrophages after retinal photocoagulation, experimental subretinal fibrosis was induced in 64 adult C57BL/6(B6) female mice (7-8 weeks). Masson staining and glial fibrillary acidic protein (GFAP) staining of choroidal wholemont were performed to verify that the subretinal fibrosis at day 7 after subretinal injection. Before subretinal injection and at day 1, 2, 3, 5 and 7 after subretinal injection, the mRNA expression level of VEGF, transforming growth factor (TGF)-β1, TGF-β2, TGF-β3, interleukin (IL)-6, IL-10 and IL-13 in RPE-choroid complex were evaluated by quantitative reverse transcription-polymerase chain reaction. Enzyme-linked immune sorbent assay was next used to detect protein expression of these factors. ResultsAt seven days after subretinal injection of inflammatory macrophages, experimental subretinal fibrosis was detected by Masson staining and GFAP staining. The mRNA level of VEGF, TGF-β1 and TGF-β2 reached the peak at day 5 after modeling, while the mRNA expression of IL-6, IL-10, IL-13 reached the peak at day 2 after modeling. TGF-β3 mRNA was not detected either in naive mice or during the development of experimental subretinal fibrosis. At day 2, 3, 5 and 7 after modeling, compared with the pre-modeling, the mRNA expression of VEGF (t=2.38, 3.65, 4.03, 2.26), TGF-β1 (t=2.58, 2.30, 3.89, 4.15) and TGF-β2 (t=4.37, 4.20, 3.77, 3.98) were significantly increased (P < 0.05). At day 1, 2 and 3 after modeling, compared with the pre-modeling, the mRNA expression of IL-6 were significantly increased (t=2.36, 4.54, 4.01; P < 0.05). At day 2 and 3 after modeling, compared with the pre-modeling, the mRNA expression of IL-10 and IL-13 were significantly increased (t=3.87, 4.20, 2.44, 2.58; P < 0.05). At day 5 after modeling, compared with the pre-modeling, the protein expression of VEGF, total TGF-β1, active TGF-β1, total TGF-β2 and active TGF-β2 were significantly increased (t=2.57, 3.37, 2.45, 3.83, 2.74; P < 0.05). IL-6, IL-10 and IL-13 protein were not detected at pre-modeling eyeballs, but were found at day 2 after modeling. ConclusionThe expression of VEGF, fibrogenic mediators and inflammatory mediators in RPE-choroid complex in mice with experimental subretinal fibrosis are increase significantly.
Choroidal neovascularization is the leading causes of central vision loss in wet age-related macular degeneration (wAMD) patients. Smoking not only aggravates the incidence and severity of the choroidal neovascularization of wAMD, but also affects the clinical treatment, making the prognosis worse. Nicotine, as an important harmful substance in tobacco, is an easily addictive and highly toxic alkaloid. Animal experiments and clinical studies have confirmed that nicotine can aggravate wAMD by mediating angiogenesis through nicotinic acetylcholine receptor, bone marrow blasts, inflammation, complement system, etc. Therefore, in order to early take appropriate intervention measures to prevent and delay the development, we should actively explore the exact pathogenesis by which nicotine aggravates the choroidal neovascularization.
MiRNAs are stable small RNAs that are expressed abundantly in animals and plants. They can bind to the 3'-untranslated region of the target mRNA, and regulate its expression at the post-transcriptional level. The miRNAs’ abnormal expression and its following abnormal biological regulation are closely related to the occurrence and development of age-related macular degeneration (AMD), including inflammatory response, oxidative stress injury, phagocytosis dysfunction and abnormal angiogenesis. Since the dysregulation of miR-155, miR-125b and miR-34a seems to play a more important role in AMD, these microRNAs may be expected to become the new biomarkers and therapeutic targets for AMD.
The etiology and pathogenesis of age-related macular degeneration (AMD) are unclear and difficult fot treatment. Some genetic research evidences in recent years have shown that the relationship between lipid metabolism-related gene polymorphism and AMD is statistically significant; it has also been found that blood lipid levels are related to AMD, and lipid-lowering drugs may have the effect of delaying the development of AMD in clinically. Abnormal lipid metabolism may play an important role in the occurrence and development of AMD. Clarifying the role of lipid metabolism in the occurrence and development of diseases will help reveal the pathogenesis of diseases and promote early diagnosis, monitoring and prevention of diseases, and provide an entry point for treatment.
Dysregulation and activation of immune processes are important in age-related macular degeneration (AMD) pathogenesis. The single nucleotide polymorphism of complement factor H is widely recognized as a risk factor to AMD. Over-activation of nod-like receptor3 and polymorphism of Toll-Like Receptor 3 also associated with AMD. Except for innate immune processes, adaptive immunity also play a critical role in AMD, a growing body of evidence supports that auto-antibodies and T cells are related with AMD. Additionally A2E and lipid oxidation byproducts might also have a role in AMD pathogenesis.
Purpose To detect whether a 3243 point mutation existed in age-related macular degeneration (AMD). MethodsTwenty-six cases of wet form AMD patients, ten cases of dry form AMD patients were selected,and compared with twenty nomal controls. After collecting anti-coagulated blood samples, total cellular DNA were extracted and purified. Using polymerase chain reaction and restriction fragment long polymorphism techniques, the mtDNA Ararr;G point mutation at position 3243 were detected. Results After cleaveded by restriction endonuclease Apa I, a 294 bp fragment remained only in all detected DNA samples including twenty-six wet form AMD, and ten dry form AMD. No any other fragment appeared. The result showed that there was no Ararr;G mutation at position 3243 found in AMD. Conclusion It is suggested that mtDNA 3243 point mutation due to maternal inheritance might be not concerned with both wet form AMD and dry form AMD. (Chin J Ocul Fundus Dis,2000,16:231-232)