A Negative Feedback Loop in Ultraviolet A-Induced Senescence in Human Dermal Fibroblasts Formed by SPCA1 and MAPK

LncRNA PVT1 delays skin photoaging by sequestering miR-551b-3p to release AQP3 expression via ceRNA mechanism

Understanding human skin photoaging requires in-depth knowledge of the molecular and functional mechanisms. Human dermal fibroblasts (HDFs) gradually lose their ability to produce collagen and renew intercellular matrix with aging. Therefore, our study aims to reveal the mechanistic actions of a novel ceRNA network in the skin photoaging by regulating HDF activities. Photoaging-related genes were obtained in silico, followed by GO and KEGG enrichment analyses. Differentially expressed lncRNAs and miRNAs were screened from the GEO database to construct the ceRNA co-expression network. In skin photoaging samples, PVT1 and AQP3 were poorly expressed, while miR-551b-3p was highly expressed. The relationships among the lncRNA, miRNA and mRNA were explored through the ENCORI database and dual luciferase reporter assay. Mechanistically, PVT1 could sequester miR-551b-3p to upregulate the expression of AQP3, which further inactivated the ERK/p38 MAPK signaling pathway. HDFs were selected to construct an in vitro cell skin photoaging model, where the senescence, cell cycle distribution and viability of young and senescent HDFs were detected by SA-β-gal staining, flow cytometry and CCK-8 assay. In vitro cell experiments confirmed that overexpression of PVT1 or AQP3 enhanced viability of young and senescent HDFs and inhibited HDF senescence, while miR-551b-3p upregulation counteracted the effect of PVT1. In conclusion, PVT1-driven suppression of miR-551b-3p induces AQP3 expression to inactivate the ERK/p38 MAPK signaling pathway, thereby inhibiting HDF senescence and ultimately delaying the skin photoaging.

Post-exposure persistence of nitric oxide upregulation in skin cells irradiated by UV-A

Evidence suggests that exposure to UV-A radiation can liberate nitric oxide from skin cells eliciting vasodilation in-vivo. However, the duration of nitric oxide release in skin cells after UV exposure is not well studied, with emphasis on UV-B mediated iNOS upregulation. The current study demonstrated persistence of nitric oxide release in a dark reaction after moderate UV-A exposure, peaking around 48 h post exposure; this effect was shown in keratinocytes, fibroblasts and endothelial cells from neonatal donors and keratinocytes from aged donors and confirmed the hypothesis that UV-A exposure appeared to upregulate cNOS alongside iNOS. Release of nitric oxide in the skin cells induced by a moderate exposure to UV-A in sunlight may be especially beneficial for some demographic groups such as the elderly, hypertensive patients or those with impaired nitric oxide function, not only during exposure but many hours and days after that.

M1-derived extracellular vesicles enhance photodynamic therapy and promote immunological memory in preclinical models of colon cancer

Extracellular vesicles (EVs) are promising drug carriers of photosensitizers for photodynamic therapy (PDT) in cancer treatment, due to their ability to circulate in blood and enter cells efficiently. The therapeutic potential of EVs has been suggested to depend on the type and physiological state of their cell of origin. However, the effects of deriving EVs from various cells in different physiological states on their antitumor capacity are rarely evaluated. In the present study, we compared the antitumor efficacy of EV-mediated PDT by incorporating the photosensitizer Zinc Phthalocyanine (ZnPc) into EVs from multiple cells sources. ZnPc was incorporated by a direct incubation strategy into EVs derived from immune cells (M1-like macrophages and M2-like macrophages), cancer cells (B16F10 melanoma cancer cells) and external sources (milk). Our data show that all EVs are suitable carriers for ZnPc and enable efficient PDT in vitro in co-culture models and in vivo. We observed that EV-mediated PDT initiates immunogenic cell death through the release and exposure of damage associated molecular patterns (DAMPs) on cancer cells, which subsequently induced dendritic cell (DC) maturation. Importantly, of all ZnPc-EVs tested, in absence of light only M1-ZnPc displayed toxicity to MC38, but not to DC, in monoculture and in co-culture, indicating specificity for cancer over immune cells. In MC38 tumor-bearing mice, only M1-ZnPc induced a tumor growth delay compared to control in absence of light. Interestingly, M1- but not M2-mediated PDT, induced complete responses against MC38 tumors in murine models (100% versus 38% of cases, respectively), with survival of all animals up to at least 60 days post inoculation. Finally, we show that all cured animals are protected from a rechallenge with MC38 cells, suggesting the induction of immunological memory after EV-mediated PDT. Together, our data show the importance of the cell type from which the EVs are obtained and highlight the impact of the immunological state of these cells on the antitumor efficacy of EV-mediated PDT.

Tachycardiomyopathy entails a dysfunctional pattern of interrelated mitochondrial functions

Tachycardiomyopathy is characterised by reversible left ventricular dysfunction, provoked by rapid ventricular rate. While the knowledge of mitochondria advanced in most cardiomyopathies, mitochondrial functions await elucidation in tachycardiomyopathy. Pacemakers were implanted in 61 rabbits. Tachypacing was performed with 330 bpm for 10 days (n = 11, early left ventricular dysfunction) or with up to 380 bpm over 30 days (n = 24, tachycardiomyopathy, TCM). In n = 26, pacemakers remained inactive (SHAM). Left ventricular tissue was subjected to respirometry, metabolomics and acetylomics. Results were assessed for translational relevance using a human-based model: induced pluripotent stem cell derived cardiomyocytes underwent field stimulation for 7 days (TACH-iPSC-CM). TCM animals showed systolic dysfunction compared to SHAM (fractional shortening 37.8 ± 1.0% vs. 21.9 ± 1.2%, SHAM vs. TCM, p < 0.0001). Histology revealed cardiomyocyte hypertrophy (cross-sectional area 393.2 ± 14.5 µm² vs. 538.9 ± 23.8 µm², p < 0.001) without fibrosis. Mitochondria were shifted to the intercalated discs and enlarged. Mitochondrial membrane potential remained stable in TCM. The metabolite profiles of ELVD and TCM were characterised by profound depletion of tricarboxylic acid cycle intermediates. Redox balance was shifted towards a more oxidised state (ratio of reduced to oxidised nicotinamide adenine dinucleotide 10.5 ± 2.1 vs. 4.0 ± 0.8, p < 0.01). The mitochondrial acetylome remained largely unchanged. Neither TCM nor TACH-iPSC-CM showed relevantly increased levels of reactive oxygen species. Oxidative phosphorylation capacity of TCM decreased modestly in skinned fibres (168.9 ± 11.2 vs. 124.6 ± 11.45 pmol·O₂·s^-1·mg^-1 tissue, p < 0.05), but it did not in isolated mitochondria. The pattern of mitochondrial dysfunctions detected in two models of tachycardiomyopathy diverges from previously published characteristic signs of other heart failure aetiologies.

Increase in NO causes osteoarthritis and chondrocyte apoptosis and chondrocyte ERK plays a protective role in the process

BACKGROUND

Nitric oxide (NO) and reactive oxygen species (ROS) play an important role in the pathology of human osteoarthritis (OA). Ankylosing spondylitis (AS) and atypical OA have similar clinical manifestations and often require differential diagnosis. The mechanism is however not totally clear yet. This study aims to investigate the effects of excessive NO-ROS in OA patients and the effects of extracellular signal-regulated kinases (ERK) pathway in NO-induced apoptosis of chondrocytes during OA progress.

METHODS AND RESULTS

Serum samples from OA or AS as pathological control patients and healthy controls were collected for NO and related chemical measurements. The rabbit articular chondrocytes were cultured in vitro, and NO was applied by Sodium Nitroprusside (SNP) in culture medium to mimic OA condition in patients. The level of SNP-evoked chondrocyte apoptosis with or without PD98059 (ERK-specific inhibitor) was evaluated by TUNEL assay, Annexin V flow cytometry and Western blotting. The activity and mRNA expression of caspase-3 in chondrocytes were measured by assay kits and RT-PCR. The levels of NO and malondialdehyde (MDA) in serum were significantly higher in OA patients, while only MDA was significantly higher in AS patients. However, the level of superoxide dismutase (SOD) was lower in both OA and AS patients. SNP induced chondrocyte apoptosis was enhanced by PD98059 with increased protein expression and functional activity of caspase-3.

CONCLUSIONS

The increase in nitric oxide occurs specifically in OA patients. ERK pathway may play a protective role on the NO-induced chondrocyte apoptosis, and inhibition of ERK pathway enhances the NO-induced apoptosis.