Light-induced Reactive Oxygen Species Research Articles

Effects of Light Exposure and Use of Intraocular Lens on Retinal Pigment Epithelial Cells In Vitro

To investigate the effect of a blue light-filtering intraocular lens (IOL) and a UV-absorbing IOL on light-induced damage to retinal pigment epithelial (RPE) cells laden with the lipofuscin fluorophore N-retinylidene-N-retinylethanolamine (A2E), A2E-laden RPE cells were exposed to white light which was filtered by either a blue light-filtering IOL or a UV-absorbing IOL. After 30 min of illumination the cell viability and the level of reactive oxygen species (ROS), free glutathione (GSH), vascular endothelial growth factor (VEGF) and pigment epithelium-derived factor (PEDF) were determined. In the absence of an IOL, the white light exposure decreased cell viability to 37.2% of the nonirradiated control. The UV-absorbing IOL tended to reduce light-induced cell death; however, the decrease was not significant. The blue light-filtering IOL significantly attenuated light-induced cell damage, increasing cell viability to 79.5% of the nonirradiated control. The presence of the blue light-filtering IOL significantly increased GSH and PEDF levels, and decreased ROS and VEGF levels. This study suggests that a blue light-filtering IOL may be more protective against A2E-induced light damage and inhibit more light-induced ROS and VEGF production than a conventional UV-absorbing IOL.

Tetrapyrrole photosensitisers, determinants of subcellular localisation and mechanisms of photodynamic processes in therapeutic approaches

Background: Tetrapyrrole photosensitisers are the main drugs used in the various photodynamic therapies. They are based on light-induced reactive oxygen species whose lifetimes are very short, limiting their diffusion in space. The photoinduced alterations primarily affect the labelled structures, at the systemic and subcellular levels. Thus, in parallel to the improvement of the photophysical and photochemical properties of photosensitisers, focus has been given to the parameters governing their localisation. Objectives and Methods: We analyse the parameters that support the efficiency of photosensitisers, paying particular attention to their structural and physicochemical characteristics, especially the dynamics of photosensitisers towards membranes. Conclusion: The determinants of systemic and subcellular targeting are discussed with regard to the induced response.

A reasonable mechanism for visible light-induced skin rejuvenation

In recent years, much research has been done in the field of non-ablative skin rejuvenation. This comes as a response to the continuous demand for a simple method of treating rhytides, UV exposure, and acne scars. Numerous researches involve visible light-pulsed systems (20-30 J/cm(2)). The mechanism of action is believed to be a selective heat-induced denaturalization of dermal collagen that leads to subsequent reactive synthesis (Bitter Jr., Dermatol. Surg., 26:836-843, 2000; Fitzpatrick et al., Arch. Dermatol., 132:395-402, 1996; Kauvar and Geronemus, Dermatol. Clin., 15:459-467, 1997; Negishi et al., Lasers Surg. Med., 30:298-305, 2002; Goldberg and Cutler, Lasers Surg. Med., 26:196-200, 2000; Hernandez-Perez and Ibeitt, Dermatol. Surg., 28:651-655, 2002). In this study, we suggest a different mechanism for photorejuvenation based on light-induced reactive oxygen species (ROS) formation. We irradiated collagen in vitro with a broadband of visible light (400-800 nm, 24-72 J/cm(2)) and used the spin trapping coupled with electron paramagnetic resonance spectroscopy to detect ROS. Irradiated collagen resulted in hydroxyl radicals formation. We propose, as a new concept, that visible light at the energy doses used for skin rejuvenation (20-30 J/cm(2)) produces high amounts of ROS, which destroy old collagen fibers, encouraging the formation of new ones. On the other hand, at inner depths of the skin, where the light intensity is much weaker, low amounts of ROS are formed, which are well known to stimulate fibroblast proliferation.

ESR Detection of 1O2 Reveals Enhanced Redox Activity in Illuminated Cell Cultures

Low-energy visible light (LEVL) has previously been found to modulate various processes in different biological systems. One explanation for the stimulatory effect of LEVL is light-induced reactive oxygen species formation. In the present study, both sperm and skin cells were illuminated with LEVL and were found to generate singlet oxygen (1O2). The detection of 1O2 was performed using a trapping probe, 2,2,6,6-tetramethyl-4-piperidone, coupled with electron paramagnetic resonance spectroscopy. In addition, we have shown that, together with 1O2 generation, LEVL illumination increases the reductive capacity of the cells, which explains the difficulties encountered in 1O2 detection. The potential of visible light to change the cellular redox state may explain the recently observed biostimulative effects exerted by LEVL.

Biostimulative effects of low‐energy lasers and their implications for medicine

The biostimulative effects exerted by various low-energy lasers in the visible light have been used in medicine for treating a wide range of pathological conditions. Because clinical endpoints in phototherapy are initiated by a sequence of events at the molecular and cellular levels, the present overview summarizes recent results that might clarify the stimulatory effects of visible light on various tissues. It appears that light-induced reactive oxygen species and changes in Ca2+ homeostasis are of paramount importance in visible light–tissue interaction. Drug Dev. Res. 50:471–475, 2000. © 2000 Wiley-Liss, Inc.

Biostimulative effects of low-energy lasers and their implications for medicine

The biostimulative effects exerted by various low-energy lasers in the visible light have been used in medicine for treating a wide range of pathological conditions. Because clinical endpoints in phototherapy are initiated by a sequence of events at the molecular and cellular levels, the present overview summarizes recent results that might clarify the stimulatory effects of visible light on various tissues, It appears that light-induced reactive oxygen species and changes in Ca 2+ homeostasis are of paramount importance in visible light-tissue interaction.