Reactive oxygen species prevent lysosome coalescence during PIKfyve inhibition

Lysosomes are terminal, degradative organelles of the endosomal pathway that undergo repeated fusion-fission cycles with themselves, endosomes, phagosomes, and autophagosomes. Lysosome number and size depends on balanced fusion and fission rates. Thus, conditions that favour fusion over fission can reduce lysosome numbers while enlarging their size. Conversely, favouring fission over fusion may cause lysosome fragmentation and increase their numbers. PIKfyve is a phosphoinositide kinase that generates phosphatidylinositol-3,5-bisphosphate to modulate lysosomal functions. PIKfyve inhibition causes an increase in lysosome size and reduction in lysosome number, consistent with lysosome coalescence. This is thought to proceed through reduced lysosome reformation and/or fission after fusion with endosomes or other lysosomes. Previously, we observed that photo-damage during live-cell imaging prevented lysosome coalescence during PIKfyve inhibition. Thus, we postulated that lysosome fusion and/or fission dynamics are affected by reactive oxygen species (ROS). Here, we show that ROS generated by various independent mechanisms all impaired lysosome coalescence during PIKfyve inhibition and promoted lysosome fragmentation during PIKfyve re-activation. However, depending on the ROS species or mode of production, lysosome dynamics were affected distinctly. H2O2 impaired lysosome motility and reduced lysosome fusion with phagosomes, suggesting that H2O2 reduces lysosome fusogenecity. In comparison, inhibitors of oxidative phosphorylation, thiol groups, glutathione, or thioredoxin, did not impair lysosome motility but instead promoted clearance of actin puncta on lysosomes formed during PIKfyve inhibition. Additionally, actin depolymerizing agents prevented lysosome coalescence during PIKfyve inhibition. Thus, we discovered that ROS can generally prevent lysosome coalescence during PIKfyve inhibition using distinct mechanisms depending on the type of ROS.

Pharmacological Activation of Autophagy Restores Cellular Homeostasis in Ultraviolet-(B)-Induced Skin Photodamage

Ultraviolet (UV) exposure to the skin causes photo-damage and acts as the primary etiological agent in photo-carcinogenesis. UV-B exposure induces cellular damage and is the major factor challenging skin homeostasis. Autophagy allows the fundamental adaptation of cells to metabolic and oxidative stress. Cellular dysfunction has been observed in aged tissues and in toxic insults to cells undergoing stress. Conversely, promising anti-aging strategies aimed at inhibiting the mTOR pathway have been found to significantly improve the aging-related disorders. Recently, autophagy has been found to positively regulate skin homeostasis by enhancing DNA damage recognition. Here, we investigated the geno-protective roles of autophagy in UV-B-exposed primary human dermal fibroblasts (HDFs). We found that UV-B irradiation to HDFs impairs the autophagy response in a time- and intensity-independent manner. However, improving autophagy levels in HDFs with pharmacological activators regulates the UV-B-induced cellular stress by decreasing the induction of DNA photo-adducts, promoting the DNA repair process, alleviating oxidative and ER stress responses, and regulating the expression levels of key cell cycle regulatory proteins. Autophagy also prevents HDFs from UV-B-induced nuclear damage as is evident in TUNEL assay and Acridine Orange/Ethidium Bromide co-staining. Salubrinal (an eIF2α phosphatase inhibitor) relieves ER stress response in cells and also significantly alleviates DNA damage and promotes the repair process in UV-B-exposed HDFs. P62-silenced HDFs show enhanced DNA damage response and also disturb the tumor suppressor PTEN/pAKT signaling axis in UV-B-exposed HDFs whereas Atg7-silenced HDFs reveal an unexpected consequence by decreasing the UV-B-induced DNA damage. Taken together, these results suggest that interventional autophagy offers significant protection against UV-B radiation-induced photo-damage and holds great promise in devising it as a suitable therapeutic strategy against skin pathological disorders.

Peeling with 25% trichloroacetic acid in the treatment of facial skin photoaging

Introduction: The chemical peel consists of the application of chemical exfoliants that eliminate the layers of the skin so that it can regenerate with an improved texture and pigmentation. It is currently a valuable therapy in dermatology, however, few studies objectively evaluate its efficacy. Objective: To evaluate the efficacy and safety of peeling with 25% trichloroacetic acid in the treatment of facial skin rejuvenation. Method: An observational, analytical and longitudinal study was carried out in 250 patients from two hospitals (Surgical Clinic: “Hermanos Ameijeiras” and General Teaching: “Enrique Cabrera”), in the period between January 2010 and January 2020. Treatment It was applied monthly for 6 months. The final evaluation was carried out 3 months after the end of the treatment. Results: 238 women and 12 men were treated with an average age of 30.5 (± 8.4) years. After treatment, there were significant changes in the Glogau Photo Damage Scale (P=0.012), in the Lemperle Wrinkle Assessment Scale (P=0.016) and in the Global Aesthetic Improvement Scale (P=0.021). The adverse events found were burning, inflammation and scaling. The degree of satisfaction reported by the patients was good (4.4%) and very good (95.6%) (P=0.011). Conclusion: The 25% trichloroacetic acid peel proved to be effective and safe to reduce the signs of facial skin aging, associated with a high degree of patient satisfaction.

Efficacy and Safety of Autologous Platelet Concentrate in The Treatment of aging of The Neck.

Introduction: Neck rejuvenation has a certain degree of difficulty, both due to its location and mobility, as well as its anatomical characteristics. Objective: To evaluate the efficacy and safety of intradermal microinjection of autologous platelet concentrate (APC) in the treatment of signs of neck aging. Method: An observational, analytical and longitudinal study was carried out in 60 patients from the Hospital Clínico Quirúrgico: “Hermanos Ameijeiras”, in the period between March 1, 2017 and March 31, 2020. The treatment was applied monthly for 1 year. The final evaluation was carried out 3 months after the end of the treatment. Results: 60 women with an average age of 45 ± 4.3 years were treated. After treatment, there were significant changes in the Glogau Photo Damage Scale (P = = 0.024), in the Global Aesthetic Improvement Scale (P <0.002) and in the Allergan Neck Transverse Lines Scale (P = 0.013). The adverse events found were pain, inflammation and ecchymosis. The degree of satisfaction reported by the patients was good (10.0%) and very good (90.0%) (P < 0.0012). Conclusions: The autologous platelet concentrate proved to be effective and safe to reduce the signs of aging in the neck, associated with a high degree of patient satisfaction.

Peeling with 30% Salicylic acid in the treatment of facial skin photoaging

Introduction: Chemical peeling consists of the application of one or more chemical ablative agents to the surface of the skin to induce keratolysis or keratocoagulation, with subsequent regeneration, achieving improved texture and pigmentation. It is currently a popular tool in the dermatology therapeutic arsenal, however, few studies objectively evaluate its efficacy. Objective: To evaluate the efficacy and safety of the 30% salicylic acid peeling in the treatment of facial skin rejuvenation. Method: An observational, analytical and longitudinal study was carried out in 280 patients from two hospitals (Surgical Clinic: “Hermanos Ameijeiras” and General Teaching: “Enrique Cabrera”), in the period between January 2010 and January 2020. Treatment It was applied monthly for 6 months. The final evaluation was carried out 3 months after the end of the treatment. Results: 256 women and 24 men were treated with an average age of 34.2 (± 6.3) years. After treatment, there were significant changes in the Glogau Photo Damage Scale (P = 0.015), in the Global Aesthetic Improvement Scale (P = 0.023) and in the Lemperle Wrinkle Assessment Scale (P = 0.017). The adverse events found were burning, inflammation and scaling. The degree of satisfaction reported by the patients was good (6.4%) and very good (93.5%) (P = 0.001). Conclusions: The 30% salicylic acid peel proved to be effective and safe to reduce the signs of facial skin aging, associated with a high degree of patient satisfaction.

The desert green algae Chlorella ohadii thrives at excessive high light intensities by exceptionally enhancing the mechanisms that protect photosynthesis from photoinhibition

Although light is the driving force of photosynthesis, excessive light can be harmful. One of the main processes that limits photosynthesis is photoinhibition (PI), the process of light-induced photo-damage. When the absorbed light exceeds the amount that is dissipated by photosynthetic electron flow and other processes, damaging radicals are formed that mostly inactivate photosystem II (PSII). Damaged PSII must be replaced by a newly repaired complex in order to preserve full photosynthetic activity. Chlorella ohadii is a green micro-alga, isolated from biological soil crusts in the desert that thrive under extreme high light and is highly resistant to PI. Therefore, C. ohadii is an ideal candidate for study the molecular protection mechanisms from PI. To charac-terize these protection mechanisms in C. ohadii, we compared thylakoids of cells that were grown under low light versus extreme high light intensities. C. ohadii were found to employ all three known PI protection mechanisms: i) performance of massive reduction of the PSII antenna size; ii) accumulate protective carotenoids; and iii) possess a very fast repair cycle of photo-damaged reaction center proteins. This work elucidated the molecular mechanisms of photoinhibition resistance in one of the most light-tolerant photosynthetic organisms and shows how photoinhibition protection mechanisms evolved to marginal conditions enabling photosynthesis-dependent life in severe habitats.One Sentence HighlightAnalysis of the photosynthetic properties of a desert algae that thrives at extreme high light in-tensities reveals how protection from photoinhibition is achieved by a remarkable enhancement of three protection mechanisms.