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L-DNase II expression and activity in light-exposed rat retinas. (A) Rats were exposed to continuous white light for 2 days (2d) or kept in a normal, cycling light (Ctl). Previous to illumination the inhibitor of PKC zeta was intravitreally injected in the right eye. The left eye was injected with the vehicle. After killing, the retinas were dissected, extracted and analysed for L-DNase II activity using a supercoiled plasmid in ionic DNase II activating conditions. The right panel is a quantification of the lower band (product of degradation). This is a representative experiment out of three. (B) Same experiment as in A but in this case LEI/L-DNase II was analysed by Western blot right panel represent a representative experiment out of four. Right panel represents the quantification of the L-DNase II band; P < 0.05 (*).
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Light-induced retinal degeneration is characterized by photoreceptor cell death. Many studies showed that photoreceptor demise is caspase-independent. In our laboratory we showed that leucocyte elastase inhibitor/LEI-derived DNase II (LEI/L-DNase II), a caspase-independent apoptotic pathway, is responsible for photoreceptor death. In this work, we...
Citations
... ns: non-significant between all groups, #: compared to NE, #p < 0.05, ##p < 0.01, **p < 0.01, ***p < 0.001.Scientific Reports| (2024) 14:6839 | https://doi.org/10.1038/s41598-024-56980-9www.nature.com/scientificreports/ over-activation of PKCζ in RPE is involved in the loss of the RPE barrier integrity13,[22][23][24][25] . However, blue light exposure does not activate this pathway, suggesting that the blue part of the spectrum is not responsible for this effect. ...
Light is known to induce retinal damage affecting photoreceptors and retinal pigment epithelium. For polychromatic light, the blue part of the spectrum is thought to be the only responsible for photochemical damage, leading to the establishment of a phototoxicity threshold for blue light (445 nm). For humans it corresponds to a retinal dose of 22 J/cm². Recent studies on rodents and non-human primates suggested that this value is overestimated. In this study, we aim at investigating the relevance of the current phototoxicity threshold and at providing new hints on the role of the different components of the white light spectrum on phototoxicity. We use an in vitro model of human induced pluripotent stem cells (hiPSC)-derived retinal pigment epithelial (iRPE) cells and exposed them to white, blue and red lights from LED devices at doses below 22 J/cm². We show that exposure to white light at a dose of 3.6 J/cm² induces an alteration of the global cellular structure, DNA damage and an activation of cellular stress pathways. The exposure to blue light triggers DNA damage and the activation of autophagy, while exposure to red light modulates the inflammatory response and inhibits autophagy.
... It was soon revealed that light intensity and duration of exposure are two critical determinants for the retinal injury. Since then, various investigations were performed to comprehend the detailed mechanisms of light-induced retinal degeneration (LIRD) across multiple animal models, and the effects of various light sources and wavelength characteristics [2][3][4][5][6][7][8]. Visible light in the spectral range of 400-500 nm is most damaging to the retina, while white fluorescent light is reported to cause significant damage to the experimental animal retina [9]. ...
Iron is implicated in ocular diseases such as in age-related macular degeneration. Light is also considered as a pathological factor in this disease. Earlier, two studies reported the influence of constant light environment on the pattern of expressions of iron-handling proteins. Here, we aimed to see the influence of light in 12-h light–12-h dark (12L:12D) cycles on the expression of iron-handling proteins in chick retina. Chicks were exposed to 400 lx (control) and 5000 lx (experimental) light at 12L:12D cycles and sacrificed at variable timepoints. Retinal ferrous ion (Fe2+) level, ultrastructural changes, lipid peroxidation level, immunolocalization and expression patterns of iron-handling proteins were analysed after light exposure. Both total Fe2+ level (p = 0.0004) and lipid peroxidation (p = 0.002) significantly increased at 12-, 48- and 168-h timepoint (for Fe2+) and 48- and 168-h timepoint (for lipid peroxidation), and there were degenerative retinal changes after 168 h of light exposure. Intense light exposure led to an increase in the levels of transferrin and transferrin receptor-1 (at 168-h) and ferroportin-1, whereas the levels of ferritins, hephaestin, (at 24-, 48- and 168-h timepoint) and ceruloplasmin (at 168-h timepoint) were decreased. These changes in iron-handling proteins after light exposure are likely due to a disturbance in the iron storage pool evident from decreased ferritin levels, which would result in increased intracellular Fe2+ levels. To counteract this, Fe2+ is released into the extracellular space, an observation supported by increased expression of ferroportin-1. Ceruloplasmin was able to convert Fe2+ into Fe3+ until 48 h of light exposure, but its decreased expression with time (at 168-h timepoint) resulted in increased extracellular Fe2+ that might have caused oxidative stress and retinal cell damage.
... While chronic blue light illumination blocked proliferation of melanoma cells and induced apoptosis in vivo (316), repeated high-intensity exposure caused necrotic cell death of cultured fibroblasts (59). Moreover, sustained illumination -even at domestically-relevant luminance levels -induced retinal toxicity, macular lesions and necrotic cell death (86,171,217,404). Hence, the extent of phototoxic damage within a given tissue appears to be highly dependent on (i) the frequency and duration of the illumination periods, (ii) the wavelength used for excitation (shorter wavelengths are more harmful than longwavelengths), and (iii) the specific target cell type. ...
Impairments of vision and hearing are highly prevalent conditions limiting the quality of life and presenting a major socioeconomic burden. For long, retinal and cochlear disorders have remained intractable for causal therapies, with sensory rehabilitation limited to glasses, hearing aids, and electrical cochlear or retinal implants. Recently, the application of gene therapy and optogenetics to eye and ear has generated hope for a fundamental improvement of vision and hearing restoration. To date, one gene therapy for the restoration of vision has been approved and undergoing clinical trials will broaden its application including gene replacement, genome editing, and regenerative approaches. Moreover, optogenetics, i.e. controlling the activity of cells by light, offers a more general alternative strategy. Over little more than a decade, optogenetic approaches have been developed and applied to better understand the function of biological systems, while protein engineers have identified and designed new opsin variants with desired physiological features. Considering potential clinical applications of optogenetics, the spotlight is on the sensory systems. Multiple efforts have been undertaken to restore lost or hampered function in eye and ear. Optogenetic stimulation promises to overcome fundamental shortcomings of electrical stimulation, namely poor spatial resolution and cellular specificity, and accordingly to deliver more detailed sensory information. This review aims at providing a comprehensive reference on current gene therapeutic and optogenetic research relevant to the restoration of hearing and vision. We will introduce gene-therapeutic approaches and discuss the biotechnological and optoelectronic aspects of optogenetic hearing and vision restoration.
... Our results suggested that blue-light (470 nm) induced oxidative stress and damaged paracellular junctions. These results are in line with previous studies by Jaadane et al. (2015) and Omri et al. (2013). Jaadane et al. (2015) demonstrated that oxidative stress produced by LED exposure upregulated the unfolded protein response genes, lead to endoplasmic reticulum stress activation and induced pro-inflammatory cytokine response. ...
... These results are in line with previous studies by Jaadane et al. (2015) and Omri et al. (2013). Jaadane et al. (2015) demonstrated that oxidative stress produced by LED exposure upregulated the unfolded protein response genes, lead to endoplasmic reticulum stress activation and induced pro-inflammatory cytokine response. Pro-inflammatory cytokines activate PKC-ζ (Jaadane et al., 2015;Omri et al., 2013). ...
... Jaadane et al. (2015) demonstrated that oxidative stress produced by LED exposure upregulated the unfolded protein response genes, lead to endoplasmic reticulum stress activation and induced pro-inflammatory cytokine response. Pro-inflammatory cytokines activate PKC-ζ (Jaadane et al., 2015;Omri et al., 2013). PKC-ζ is identified as a key player in the regulation of tight junctions. ...
... Preliminary studies suggest that aPKC may also regulate degeneration of the neural retina and retinal pigment epithelium, potentially through TNFaemediated inflammatory signaling. 22,23 Accordingly, aPKC inhibitors have therapeutic potential in retinal neurodegeneration, which is a likely topic of future investigations. ...
This commentary highlights the article by Lin et al that demonstrates the therapeutic potential of small-molecule atypical protein kinase C inhibitors in inflammatory ocular disease.
... As the oxidation of the different components (proteins, lipids, etc.) was difficult to label in RPE (not shown), we used indirect signs of oxidative stress by studying its cellular responses. PKC zeta, an atypical protein kinase [24], was activated after 4.75 hrs of LED exposure as indicated by its plasma membrane translocation [25][26][27] (Fig. 2A, arrows). This location is progressively lost and after 18 hrs of exposure, and PKC zeta is translocated to the nucleus ( Fig. 2A, white arrows, co-labelling with DAPI (blue)/PKC zeta (red)). ...
... Actually, its inhibition partially restored the barrier function of the RPE in a rat model of diabetes mellitus [29]. To investigate whether this was also the case here, we inhibited PKC zeta as before [27]. The leakage of the BRB was quantified by measuring the surface of the rat serum albumin seen at the photoreceptors segments layer (see Fig. 2D). ...
... The stress generated by LED light exposure induces also survivalpromoting signals. We show the activation of the PKC zeta/NFkB axis involved in different types of retinal damage [29] [13] [27]. Following stress, activated PKC zeta (phosphorylated at threonine 410) triggers the phosphorylation cascade that leads to the activation of NFkB (by phosphorylation on serine 311) [28,30,51]. ...
Ageing and alteration of the functions of the retinal pigment epithelium (RPE) are at the origin of lost of vision seen in age-related macular degeneration (AMD). The RPE is known to be vulnerable to high-energy blue light. The white light-emitting diodes (LED) commercially available have relatively high content of blue light, a feature that suggest that they could be deleterious for this retinal cell layer. The aim of our study was to investigate the effects of "white LED" exposure on RPE. For this, commercially available white LEDs were used for exposure experiments on Wistar rats. Immunohistochemical stain on RPE flat mount, transmission electron microscopy and Western blot were used to exam the RPE. LED-induced RPE damage was evaluated by studying oxidative stress, stress response pathways and cell death pathways as well as the integrity of the outer blood-retinal barrier (BRB). We show that white LED light caused structural alterations leading to the disruption of the outer blood-retinal barrier. We observed an increase in oxidized molecules, disturbance of basal autophagy and cell death by necrosis. We conclude that white LEDs induced strong damages in rat RPE characterized by the breakdown of the BRB and the induction of necrotic cell death.
... We investigated then the activation of both NFkB and PKC zeta ( Fig. 6B and C, and Supplementary Fig. 9). PKC zeta is an upstream activator of NFkB that we have already seen activated in LIRD [59]. The activation of PKC zeta, as materialized by its phosphorylated form, seemed activated in all but Nichia blue-green LEDs. ...
Spectra of "white LED" are characterized by an intense emission in the blue region of the visible spectrum, absent in day light spectra. This blue component and the high intensity of emission are the main sources of concern about the health risks of LEDs with respect to their toxicity to the eye and the retina.
The aim of our study was to elucidate the role of blue light from LEDs in retinal damage.
Commercially available white LED and four different blue LEDs (507, 473, 467 and 449nm) were used for exposure experiments on Wistar rats. Immunohistochemical stain, transmission electron microscopy and western blot were used to exam the retinas. We evaluated LED-induced retinal cell damage by studying oxidative stress, stress response pathways and the identification of cell death pathways.
LED light caused a state of suffering of the retina with oxidative damage and retinal injury. We observed a loss of photoreceptors and the activation of caspase independent apoptosis, necroptosis and necrosis. A wavelength dependence of the effects was observed.
Phototoxicity of LEDs on the retina is characterized by a strong damage of photoreceptors and by the induction of necrosis.
Copyright © 2015. Published by Elsevier Inc.
Phototoxicity animal models have been largely studied due to their degenerative com-
munalities with human pathologies, e.g., age-related macular degeneration (AMD). Studies have
documented not only the effects of white light exposure, but also other wavelengths using LEDs,
such as blue or green light. Recently, a blue LED-induced phototoxicity (LIP) model has been devel-
oped that causes focal damage in the outer layers of the superior-temporal region of the retina in
rodents. In vivo studies described a progressive reduction in retinal thickness that affected the most
extensively the photoreceptor layer. Functionally, a transient reduction in a- and b-wave amplitude
of the ERG response was observed. Ex vivo studies showed a progressive reduction of cones and an
involvement of retinal pigment epithelium cells in the area of the lesion and, in parallel, an activation
of microglial cells that perfectly circumscribe the damage in the outer retinal layer. The use of
neuroprotective strategies such as intravitreal administration of trophic factors, e.g., basic fibroblast
growth factor (bFGF), brain-derived neurotrophic factor (BDNF), ciliary neurotrophic factor (CNTF)
or pigment epithelium-derived factor (PEDF) and topical administration of the selective alpha-2
agonist (Brimonidine) have demonstrated to increase the survival of the cone population after LIP.
In recent years, important advances have been made to decipher the multiple defense mechanisms of the retina (a highly specialized sense tissue) against several extreme conditions, such as constant exposure to systemic toxins, oxidative stress, and focused light rays. These studies have importantly contributed to improving our understanding of the principles underlying various drug- and light-induced disease processes, specifically at the eye level. When the different retinal cell layer defenses are overwhelmed by various xenobiotics, environmental agents such as pollution, cigarette smoke, or excessive light exposure, particularly high-frequency blue light and ultraviolet light, a pathological process may develop. Herein, we describe the main aspects of the structure and function of the retina in connection to some of the most relevant mechanisms which may generate retinal toxicity, and possible alternatives to counteract these effects. Furthermore, we summarize current knowledge about light-induced retinal toxicity as well as the effects of different natural and synthetic compounds on the molecular mechanisms underlying toxicity in the retina. Finally, the potential approaches undertaken to counteract these toxic effects, i.e., polyphenols and others, are discussed.
SERPINB1, also called Leukocyte Elastase Inhibitor (LEI) is a member of the clade B of SERPINS. It is an intracellular protein and acts primarily to protect the cell from proteases released into the cytoplasm during stress. Its role in inflammation is clear due to its involvement in the resolution of chronic inflammatory lung and bowel diseases. LEI/SERPINB1 intrinsically possesses two enzymatic activities: an antiprotease activity dependent on its reactive site loop, which is analogous to the other proteins of the family and an endonuclease activity which is unveiled by the cleavage of the reactive site loop. The conformational change induced by this cleavage also unveils a bipartite nuclear localization signal allowing the protein to translocate to the nucleus. Recent data indicate that it has also a role in cell migration suggesting that it could be involved in diverse processes like wound healing and malignant metastases.
