Background:Retinopathy of prematurity(ROP),the most common cause of blindness in premature infants,has long been associated with pathologic retinal vasculature.However,recent studies reveal choroidal involution in ado...Background:Retinopathy of prematurity(ROP),the most common cause of blindness in premature infants,has long been associated with pathologic retinal vasculature.However,recent studies reveal choroidal involution in adolescent patients formerly afflicted with ROP.We have recently demonstrated that choroidal thinning occurs early in retinopathy and persists into adulthood.Unlike retinal vessels,the damaged choroidal vasculature in ROP is incapably to regenerate.Herein,we investigated the molecular mechanism implicated in the lack of choroidal repair in ischemic retinopathy.Methods:The oxygen-induced retinopathy(OIR)model was used.Newborn Sprague-Dawley(albino)or Long-Evans rats(pigmented)rats were placed under oxygen concentration which cycles at 50%±1%or 10%±1%every 24 hours(hr)from postnatal day(P)0 to P14.On P14,all rats were returned to room air.Western blotting and qPCR were used to quantify protein and RNA abundances,respectively.The Dual-Luciferase®Reporter Assay System was used to confirm microRNA(miRNA)-mRNA interaction.Results:We detected a substantial oxidative stress in retinal pigment epithelium(RPE)and choroidal tissue,accompanied by a drastic reduction in insulin-like growth factor 1 receptor(IGF1R),a critical player in post-injury revascularization.The mechanism of decreasing IGF1R involves the over-activation of the p53 tumor suppressor that regulates miRNA let-7b,which subsequently silences Igf1r mRNA in the RPE/choroid complex of OIR subjects.Luciferase reporter assay confirmed that let-7b directly targets Igf1r mRNA at its 3’untranslated region(UTR).Indeed,silencing p53 resulted in a decreased let-7b expression,and re-established IGF1R abundance that promoted choroidal regeneration.Conclusions:Together,this study sets forth new mechanistic notion by uncovering the novel p53/let-7b/IGF1R axis;timely intervention of this pathway facilitates healthy choroidal revascularization.Future investigations on anti-angiogenic miRNAs can better our understanding on degenerative choroidopathy,such as geographic atrophy.展开更多
Background:Retinal pigment epithelium(RPE)is vital for the homeostasis of the subretina including photoreceptors and choroid.Interestingly,our previous results suggested that the recently discovered lactate receptor G...Background:Retinal pigment epithelium(RPE)is vital for the homeostasis of the subretina including photoreceptors and choroid.Interestingly,our previous results suggested that the recently discovered lactate receptor GPR81 is abundantly expressed in RPE.To date,only one previous study has shown that activating GPR81 could enhance DNA repair by activating HDAC1.Consequently,we investigated whether GPR81 exhibits epigenetic modification in the subretina by using GPR81−/−mice.Methods:GPR81−/−mice and wide type littermates were generated on a background of C57BL/6J mice.The thicknesses of their choroid were evaluated by immunohistochemistry.Meanwhile,Q-PCR,western blot and choroid sprout assay were performed.In vitro,primary retinal pigment epithelium(pRPE)cells were isolated from mice,and cultured for treatments.Results:The thickness of choroid was reduced in GPR81−/−mice compared to GPR81+/+mice,suggesting that GPR81 is important for the integrity of choroid.In the choroid sprout assay,lactate treated RPE/choroid complex showed a significant increase in angiogenesis compared to controls while lactate treated KO RPE/choroid complex showed no difference compared to their controls.For Q-PCR,most of the genes screened elevated their expression in GPR81−/−mice compared to WT mice,suggesting epigenetic modification may exist,which were confirmed by histone acetylation and HDACs activity assay.Conclusions:Taking together,the lactate receptor GPR81 in RPE is very important for maintaining homeostasis of the subretina.This novel discovery sheds new light on the relationship between metabolism and epigenetic modification.展开更多
Background:We investigated the role of beta-adrenergic receptor(B-AR)on choroidal neovascularization(CNV)in an animal model of age-related macular degeneration in mice.Methods:The angiogenic effect of the B-AR was eva...Background:We investigated the role of beta-adrenergic receptor(B-AR)on choroidal neovascularization(CNV)in an animal model of age-related macular degeneration in mice.Methods:The angiogenic effect of the B-AR was evaluated in retinal pigment epithelium(RPE)-choroid explants from C57Bl6 mice stimulated with propranolol or isoproterenol(10μM)(respectively antagonist and agonist of the B-AR)during 24 h.Conversely,a classic choroidal neovascularization(CNV)model induced by laser burn in C57Bl6 mice(8 weeks)was used to assess the anti-angiogenic effect of propranolol.In this experiment,mice were treated with intraperitoneal propranolol(6 mg/kg/d)or vehicle(saline solution)daily for 10 days,starting on day 4 after laser burn and until sacrifice(day 14).Immunostaining analysis on retinal flatmounts and cryosections were performed to determine the surface of CNV,the distribution of B-AR and the number and morphology of microglia/macrophages associated with CNV.To explore if the antiangiogenic effect of propranolol involved the modulation of the inflammatory microenvironment associated with CNV,we used RPE primary cells,J774 macrophages cell line and polarized M1 and M2 bone marrow-derived macrophage(BMDM).Choroidal explants treated with conditioned media(CM)from J774 or polarized M1/M2 BMDM pre-treated with propranolol to confirm the anti-angiogenic effect of propranolol.Expression of angiogenic factors was evaluated by RT PCR and Elisa.Results:The expression and distribution of the B-1,B-2 and B-3 adrenergic receptors were localized in the choroid and RPE cells.The stimulation of RPE-choroid explants with isoproterenol increased CNV compared to vehicle,while propranolol decreased CNV.In vivo,propranolol inhibited significantly the levels of VEGF and CNV growth in laser burn model compared to the vehicle.Additionally,the treatment with propranolol decremented the number of activated(amoeboid shape)microglia/macrophages but surprisingly,the number of non-activated microglia/macrophages around the CNV was higher than with the vehicle treatment.In vitro,propranolol modulated the angiogenic balance in macrophages promoting anti-angiogenic factors expression,especially with M2 BMDM.CM from macrophages pre-treated with propranolol reduced CNV on choroidal explants.Conclusions:These ex vivo and in vivo studies highlight the importance of B-adrenergic receptor in the CNV.Propranolol can inhibit CNV by decreasing the levels of VEGF and modulating microglia/macrophages activation.Further work will investigate the role of B-adrenergic receptor on suppression of the inflammatory environment in order to understand the link between neovascularization and inflammation in CNV during age-related macular degeneration.展开更多
Subretinal inflammation plays a critical role in retinal degenerative diseases.Although activated macrophages have been shown to play a key role in the progression of retinopathies and specifically in age-related macu...Subretinal inflammation plays a critical role in retinal degenerative diseases.Although activated macrophages have been shown to play a key role in the progression of retinopathies and specifically in age-related macular degeneration,little is known about the mechanisms involved in the loss of photoreceptors leading to vision impairment.In our study on retinal damages induced by photo-oxidative stress,we have observed that CD36-deficient mice featured less subretinal macrophage accumulation with attenuated photoreceptor degeneration compared to wild-type(WT)mice.Treatment with CD36-selective azapeptide ligand(labelled MPE-001)as modulator of the inflammatory environment of the retina reduced subretinal macrophage/activated microglia accumulation with preservation of photoreceptor layers and function assessed by ERG in WT,in a CD36-dependent manner.The azapeptide modulated the transcriptome of subretinal macrophage/activated microglia by reducing pro-inflammatory markers.In isolated macrophages,the CD36-selective azapeptide induced dissociation of the CD36-TLR2/6 heterodimer complex(using FRET)altering the TLR2 signaling pathway,thus decreasing NF-κB activation and inflammasome activity.The azapeptide also incurred cytoprotection against photoreceptor apoptosis elicited by activated macrophages.These findings suggest that the azapeptide as ligand of co-receptor CD36 decreases the inflammatory response by modulating CD36-TLR2/6 complex signaling pathway in macrophages,and suggests its potential application in the treatment of retinal degenerative diseases.展开更多
文摘Background:Retinopathy of prematurity(ROP),the most common cause of blindness in premature infants,has long been associated with pathologic retinal vasculature.However,recent studies reveal choroidal involution in adolescent patients formerly afflicted with ROP.We have recently demonstrated that choroidal thinning occurs early in retinopathy and persists into adulthood.Unlike retinal vessels,the damaged choroidal vasculature in ROP is incapably to regenerate.Herein,we investigated the molecular mechanism implicated in the lack of choroidal repair in ischemic retinopathy.Methods:The oxygen-induced retinopathy(OIR)model was used.Newborn Sprague-Dawley(albino)or Long-Evans rats(pigmented)rats were placed under oxygen concentration which cycles at 50%±1%or 10%±1%every 24 hours(hr)from postnatal day(P)0 to P14.On P14,all rats were returned to room air.Western blotting and qPCR were used to quantify protein and RNA abundances,respectively.The Dual-Luciferase®Reporter Assay System was used to confirm microRNA(miRNA)-mRNA interaction.Results:We detected a substantial oxidative stress in retinal pigment epithelium(RPE)and choroidal tissue,accompanied by a drastic reduction in insulin-like growth factor 1 receptor(IGF1R),a critical player in post-injury revascularization.The mechanism of decreasing IGF1R involves the over-activation of the p53 tumor suppressor that regulates miRNA let-7b,which subsequently silences Igf1r mRNA in the RPE/choroid complex of OIR subjects.Luciferase reporter assay confirmed that let-7b directly targets Igf1r mRNA at its 3’untranslated region(UTR).Indeed,silencing p53 resulted in a decreased let-7b expression,and re-established IGF1R abundance that promoted choroidal regeneration.Conclusions:Together,this study sets forth new mechanistic notion by uncovering the novel p53/let-7b/IGF1R axis;timely intervention of this pathway facilitates healthy choroidal revascularization.Future investigations on anti-angiogenic miRNAs can better our understanding on degenerative choroidopathy,such as geographic atrophy.
文摘Background:Retinal pigment epithelium(RPE)is vital for the homeostasis of the subretina including photoreceptors and choroid.Interestingly,our previous results suggested that the recently discovered lactate receptor GPR81 is abundantly expressed in RPE.To date,only one previous study has shown that activating GPR81 could enhance DNA repair by activating HDAC1.Consequently,we investigated whether GPR81 exhibits epigenetic modification in the subretina by using GPR81−/−mice.Methods:GPR81−/−mice and wide type littermates were generated on a background of C57BL/6J mice.The thicknesses of their choroid were evaluated by immunohistochemistry.Meanwhile,Q-PCR,western blot and choroid sprout assay were performed.In vitro,primary retinal pigment epithelium(pRPE)cells were isolated from mice,and cultured for treatments.Results:The thickness of choroid was reduced in GPR81−/−mice compared to GPR81+/+mice,suggesting that GPR81 is important for the integrity of choroid.In the choroid sprout assay,lactate treated RPE/choroid complex showed a significant increase in angiogenesis compared to controls while lactate treated KO RPE/choroid complex showed no difference compared to their controls.For Q-PCR,most of the genes screened elevated their expression in GPR81−/−mice compared to WT mice,suggesting epigenetic modification may exist,which were confirmed by histone acetylation and HDACs activity assay.Conclusions:Taking together,the lactate receptor GPR81 in RPE is very important for maintaining homeostasis of the subretina.This novel discovery sheds new light on the relationship between metabolism and epigenetic modification.
文摘Background:We investigated the role of beta-adrenergic receptor(B-AR)on choroidal neovascularization(CNV)in an animal model of age-related macular degeneration in mice.Methods:The angiogenic effect of the B-AR was evaluated in retinal pigment epithelium(RPE)-choroid explants from C57Bl6 mice stimulated with propranolol or isoproterenol(10μM)(respectively antagonist and agonist of the B-AR)during 24 h.Conversely,a classic choroidal neovascularization(CNV)model induced by laser burn in C57Bl6 mice(8 weeks)was used to assess the anti-angiogenic effect of propranolol.In this experiment,mice were treated with intraperitoneal propranolol(6 mg/kg/d)or vehicle(saline solution)daily for 10 days,starting on day 4 after laser burn and until sacrifice(day 14).Immunostaining analysis on retinal flatmounts and cryosections were performed to determine the surface of CNV,the distribution of B-AR and the number and morphology of microglia/macrophages associated with CNV.To explore if the antiangiogenic effect of propranolol involved the modulation of the inflammatory microenvironment associated with CNV,we used RPE primary cells,J774 macrophages cell line and polarized M1 and M2 bone marrow-derived macrophage(BMDM).Choroidal explants treated with conditioned media(CM)from J774 or polarized M1/M2 BMDM pre-treated with propranolol to confirm the anti-angiogenic effect of propranolol.Expression of angiogenic factors was evaluated by RT PCR and Elisa.Results:The expression and distribution of the B-1,B-2 and B-3 adrenergic receptors were localized in the choroid and RPE cells.The stimulation of RPE-choroid explants with isoproterenol increased CNV compared to vehicle,while propranolol decreased CNV.In vivo,propranolol inhibited significantly the levels of VEGF and CNV growth in laser burn model compared to the vehicle.Additionally,the treatment with propranolol decremented the number of activated(amoeboid shape)microglia/macrophages but surprisingly,the number of non-activated microglia/macrophages around the CNV was higher than with the vehicle treatment.In vitro,propranolol modulated the angiogenic balance in macrophages promoting anti-angiogenic factors expression,especially with M2 BMDM.CM from macrophages pre-treated with propranolol reduced CNV on choroidal explants.Conclusions:These ex vivo and in vivo studies highlight the importance of B-adrenergic receptor in the CNV.Propranolol can inhibit CNV by decreasing the levels of VEGF and modulating microglia/macrophages activation.Further work will investigate the role of B-adrenergic receptor on suppression of the inflammatory environment in order to understand the link between neovascularization and inflammation in CNV during age-related macular degeneration.
文摘Subretinal inflammation plays a critical role in retinal degenerative diseases.Although activated macrophages have been shown to play a key role in the progression of retinopathies and specifically in age-related macular degeneration,little is known about the mechanisms involved in the loss of photoreceptors leading to vision impairment.In our study on retinal damages induced by photo-oxidative stress,we have observed that CD36-deficient mice featured less subretinal macrophage accumulation with attenuated photoreceptor degeneration compared to wild-type(WT)mice.Treatment with CD36-selective azapeptide ligand(labelled MPE-001)as modulator of the inflammatory environment of the retina reduced subretinal macrophage/activated microglia accumulation with preservation of photoreceptor layers and function assessed by ERG in WT,in a CD36-dependent manner.The azapeptide modulated the transcriptome of subretinal macrophage/activated microglia by reducing pro-inflammatory markers.In isolated macrophages,the CD36-selective azapeptide induced dissociation of the CD36-TLR2/6 heterodimer complex(using FRET)altering the TLR2 signaling pathway,thus decreasing NF-κB activation and inflammasome activity.The azapeptide also incurred cytoprotection against photoreceptor apoptosis elicited by activated macrophages.These findings suggest that the azapeptide as ligand of co-receptor CD36 decreases the inflammatory response by modulating CD36-TLR2/6 complex signaling pathway in macrophages,and suggests its potential application in the treatment of retinal degenerative diseases.
