Resveratrol protects photoreceptors by blocking caspase- and PARP-dependent cell death pathways

Synthesis and Evaluation of Glucosyl-, Acyl- and Silyl- Resveratrol Derivatives as Retinoprotective Agents: Piceid Octanoate Notably Delays Photoreceptor Degeneration in a Retinitis Pigmentosa Mouse Model

BACKGROUND

Retinitis pigmentosa (RP), the leading cause of inherited blindness in adults, is marked by the progressive degeneration of rod photoreceptors in the retina. While gene therapy has shown promise in treating RP in patients with specific mutations, no effective therapies currently exist for the majority of patients with diverse genetic backgrounds. Additionally, no intervention can yet prevent or delay photoreceptor loss across the broader RP patient population. Resveratrol (RES), a naturally occurring polyphenol, has shown cytoprotective effects in various neurodegenerative disease models; however, its therapeutic potential is limited by low bioavailability.

METHODS

In this study, we synthesized novel RES derivatives and assessed their retinoprotective effects in a murine model of RP (rd10 mice).

RESULTS

Among these derivatives, piceid octanoate (PIC-OCT) significantly delayed photoreceptor degeneration in the RP model, demonstrating superior efficacy compared to RES.

CONCLUSIONS

PIC-OCT shows strong potential as a leading candidate for developing new therapeutic strategies for RP.

Oxidative Stress, Oxidative Damage, and Cell Apoptosis: Toxicity Induced by Arecoline in Caenorhabditis elegans and Screening of Mitigating Agents

As the areca nut market is expanding, there is a growing concern regarding areca nut toxicity. Areca nut alkaloids are the major risky components in betel nuts, and their toxic effects are not fully understood. Here, we investigated the parental and transgenerational toxicity of varied doses of areca nut alkaloids in Caenorhabditis elegans. The results showed that the minimal effective concentration of arecoline is 0.2-0.4 mM. First, arecoline exhibited transgenerational toxicity on the worms' longevity, oviposition, and reproduction. Second, the redox homeostasis of C. elegans was markedly altered under exposure to 0.2-0.4 mM arecoline. The mitochondrial membrane potential was thereafter impaired, which was also associated with the induction of apoptosis. Moreover, antioxidant treatments such as lycopene could significantly ameliorate the toxic effects caused by arecoline. In conclusion, arecoline enhances the ROS levels, inducing neurotoxicity, developmental toxicity, and reproductive toxicity in C. elegans through dysregulated oxidative stress, cell apoptosis, and DNA damage-related gene expression. Therefore, the drug-induced production of reactive oxygen species (ROS) may be crucial for its toxic effects, which could be mitigated by antioxidants.

Differences between long- and short-wavelength light-induced retinal damage and the role of PARP-1 in retinal injury induced by blue light

Photobiomodulation (PBM) therapy uses light of different wavelengths to treat various retinal degeneration diseases, but the potential damage to the retina caused by long-term light irradiation is still unclear. This study were designed to detect the difference between long- and short-wavelength light (650-nm red light and 450-nm blue light, 2.55 mW/cm2, reference intensity in PBM)-induced injury. In addition, a comparative study was conducted to investigate the differences in retinal light damage induced by different irradiation protocols (short periods of repeated irradiation and a long period of constant irradiation). Furthermore, the protective role of PARP-1 inhibition on the molecular mechanism of blue light-induced injury was confirmed by a gene knockdown technique or a specific inhibitor through in vitro and in vivo experiments. The results showed that the susceptibility to retinal damage caused by irradiation with long- and short-wavelength light is different. Shorter wavelength lights, such as blue light, induce more severe retinal damage, while the retina exhibits better resistance to longer wavelength lights, such as red light. In addition, repeated irradiation for short periods induces less retinal damage than constant exposure over a long period. PARP-1 plays a critical role in the molecular mechanism of blue light-induced damage in photoreceptors and retina, and inhibiting PARP-1 can significantly protect the retina against blue light damage. This study lays an experimental foundation for assessing the safety of phototherapy products and for developing target drugs to protect the retina from light damage.

Piceid Octanoate Protects Retinal Cells against Oxidative Damage by Regulating the Sirtuin 1/Poly-ADP-Ribose Polymerase 1 Axis In Vitro and in rd10 Mice

Retinitis pigmentosa is a common cause of inherited blindness in adults, which in many cases is associated with an increase in the formation of reactive oxygen species (ROS) that induces DNA damage, triggering Poly-ADP-Ribose Polymerase 1 (PARP1) activation and leading to parthanatos-mediated cell death. Previous studies have shown that resveratrol (RSV) is a promising molecule that can mitigate PARP1 overactivity, but its low bioavailability is a limitation for medical use. This study examined the impact of a synthesized new acylated RSV prodrug, piceid octanoate (PIC-OCT), in the 661W cell line against H2O2 oxidative stress and in rd10 mice. PIC-OCT possesses a better ADME profile than RSV. In response to H2O2, 661W cells pretreated with PIC-OCT preserved cell viability in more than 38% of cells by significantly promoting SIRT1 nuclear translocation, preserving NAD+/NADH ratio, and suppressing intracellular ROS formation. These effects result from expressing antioxidant genes, maintaining mitochondrial function, reducing PARP1 nuclear expression, and preventing AIF nuclear translocation. In rd10 mice, PIC-OCT inhibited PAR-polymer formation, increased SIRT1 expression, significantly reduced TUNEL-positive cells in the retinal outer nuclear layer, preserved ERGs, and enhanced light chamber activity (all p values < 0.05). Our findings corroborate that PIC-OCT protects photoreceptors by modulating the SIRT1/PARP1 axis in models of retinal degeneration.

Evidence-based mechanistic role of chrysin towards protection of cardiac hypertrophy and fibrosis in rats

Cardiac hypertrophy is the enlargement of cardiomyocytes in response to persistent release of catecholamine which further leads to cardiac fibrosis. Chrysin, flavonoid from honey, is well known for its multifarious properties like antioxidant, anti-inflammatory, anti-fibrotic and anti-apoptotic. To investigate the cardioprotective potential of chrysin against isoproterenol (ISO), cardiac hypertrophy and fibrosis are induced in rats. Acclimatised male albino Wistar rats were divided into seven groups (n 6): normal (carboxymethyl cellulose at 0·5 % p.o.; as vehicle), hypertrophy control (ISO 3 mg/kg, s.c.), CHY15 + H, CHY30 + H & CHY60 + H (chrysin; p.o.15, 30 and 60 mg/kg respectively + ISO at 3 mg/kg, s.c.), CHY60 (chrysin 60 mg/kg in per se) and LST + H (losartan 10 mg/kg p.o. + ISO 3 mg/kg, s.c.) were treated for 28 d. After the dosing schedule on day 29, haemodynamic parameters were recorded, after that blood and heart were excised for biochemical, histological, ultra-structural and molecular evaluations. ISO administration significantly increases heart weight:body weight ratio, pro-oxidants, inflammatory and cardiac injury markers. Further, histopathological, ultra-structural and molecular studies confirmed deteriorative changes due to ISO administration. Pre-treatment with chrysin of 60 mg/kg reversed the ISO-induced damage to myocardium and prevent cardiac hypertrophy and fibrosis through various anti-inflammatory, anti-apoptotic, antioxidant and anti-fibrotic pathways. Data demonstrated that chrysin attenuated myocardial hypertrophy and prevented fibrosis via activation of transforming growth factor-beta (TGF-β)/Smad signalling pathway.

Comparison of the chronic and multigenerational toxicity of racemic glufosinate and l-glufosinate to Caenorhabditis elegans at environmental concentrations

Glufosinate-ammonium, the second largest transgene crop resistant herbicide, is classified as a mobile persistent pollutant by the U.S. Environmental Protection Agencybecause of its slow decomposition and easy mobile transfer in a water environment. The chronic and multigeneration toxicity of this compound to environmental organisms are alarming. In this study, racemic glufosinate-ammonium and the effective isomer, l-glufosinate-ammonium, were used as the test agents. The developmental, neurotoxic and reproductive toxicities of Caenorhabditis elegans to their parents and progeny were studied by continuous exposure in water at concentrations of 0.1, 1, 10 and 100 μg/L. The causes of toxicity differences were analysed from oxidative stress and transcription levels. Through oxidative stress of C. elegans, racemic glufosinate-ammonium and l-glufosinate-ammonium both mediated the developmental toxicity (shortened developmental cycle, reduced body length and width, promoted ageingand decreased longevity), neurotoxicity (inhibited head swinging, body bending frequency and acetylcholinesterase [AchE] activity) and reproductive toxicity (significant reductions in the number of eggs and offspring in vivo and induced apoptosis of gonadal cells). These phenomena caused oxidative damage (protein and membrane lipid peroxidation) and further induced apoptosis. The changes in various indicators caused by racemic glufosinate-ammonium exposure were more significant than those caused by l-glufosinate-ammonium exposure, and the reproduction-related indicators were more significant than the developmental and neurological indicators. A continuous accumulation of toxicity was observed after multiple generations of continuous exposure. These research results provide a data reference for the ecotoxicological evaluation and risk assessment of glufosinate-ammonium and contribute to the revision and improvement of the related environmental policies of glufosinate-ammonium.

Potential therapeutic strategies for photoreceptor degeneration: the path to restore vision

Photoreceptors (PRs), as the most abundant and light-sensing cells of the neuroretina, are responsible for converting light into electrical signals that can be interpreted by the brain. PR degeneration, including morphological and functional impairment of these cells, causes significant diminution of the retina's ability to detect light, with consequent loss of vision. Recent findings in ocular regenerative medicine have opened promising avenues to apply neuroprotective therapy, gene therapy, cell replacement therapy, and visual prostheses to the challenge of restoring vision. However, successful visual restoration in the clinical setting requires application of these therapeutic approaches at the appropriate stage of the retinal degeneration. In this review, firstly, we discuss the mechanisms of PR degeneration by focusing on the molecular mechanisms underlying cell death. Subsequently, innovations, recent developments, and promising treatments based on the stage of disorder progression are further explored. Then, the challenges to be addressed before implementation of these therapies in clinical practice are considered. Finally, potential solutions to overcome the current limitations of this growing research area are suggested. Overall, the majority of current treatment modalities are still at an early stage of development and require extensive additional studies, both pre-clinical and clinical, before full restoration of visual function in PR degeneration diseases can be realized.

A PARP1 PROTAC as a novel strategy against PARP inhibitor resistance via promotion of ferroptosis in p53-positive breast cancer

Therapeutic targeting of the nuclear enzyme poly (ADP-ribose) polymerase 1 (PARP1) with PARP inhibitors (PARPis) in patients with a homologous recombination (HR)- deficient phenotype based on the mechanism of synthetic lethality has been shown tremendous success in cancer therapy. With the clinical use of various PARPis, emerging evidence has shown that some PARPis offer hope for breakthroughs in triple-negative breast cancer (TNBC) therapy, regardless of HR status. However, similar to other conventional cytotoxic drugs, PARPis are also subject to the intractable problem of drug resistance. Notably, acquired resistance to PARPis caused by point mutations in the PARP1 protein is hard to overcome with current strategies. To explore modalities to overcome resistance and identify patients who are most likely to benefit from PARP1-targeted therapy, we developed a proteolysis-targeted chimaera (PROTAC) to degrade mutant PARP1 in TNBC. Here, we investigated a PARP1 PROTAC termed "NN3″, which triggered ubiquitination and proteasome-mediated degradation of PARP1. Moreover, NN3 degraded PARP1 with resistance-related mutations. Interestingly, compared with other reported PARP1 degraders, NN3 exhibited a unique antitumor mechanism in p53-positive breast cancer cells that effectively promoted ferroptosis by downregulating the SLC7A11 pathway. Furthermore, NN3 showed potent activity and low toxicity in vivo. In conclusion, we propose PROTAC-mediated degradation of PARP1 as a novel strategy against mutation-related PARPi resistance and a paradigm for targeting breast cancer with functional p53 via ferroptosis induction.

PARP-1 Is a Potential Marker of Retinal Photooxidation and a Key Signal Regulator in Retinal Light Injury

Advancements in technology have resulted in increasing concerns over the safety of eye exposure to light illumination, since prolonged exposure to intensive visible light, especially to short-wavelength light in the visible spectrum, can cause photochemical damage to the retina through a photooxidation-triggered cascade reaction. Poly(ADP-ribose) polymerase-1 (PARP-1) is the ribozyme responsible for repairing DNA damage. When damage to DNA occurs, including nicks and breaks, PARP-1 is rapidly activated, synthesizing a large amount of PAR and recruiting other nuclear factors to repair the damaged DNA. However, retinal photochemical damage may lead to the overactivation of PARP-1, triggering PARP-dependent cell death, including parthanatos, necroptosis, and autophagy. In this review, we retrieved targeted articles with the keywords such as “PARP-1,” “photoreceptor,” “retinal light damage,” and “photooxidation” from databases and summarized the molecular mechanisms involved in retinal photooxidation, PARP activation, and DNA repair to clarify the key regulatory role of PARP-1 in retinal light injury and to determine whether PARP-1 may be a potential marker in response to retinal photooxidation. The highly sensitive detection of PARP-1 activity may facilitate early evaluation of the effects of light on the retina, which will provide an evidentiary basis for the future assessment of the safety of light illumination from optoelectronic products and medical devices.

Gestational exposure to GenX induces hepatic alterations by the gut-liver axis in maternal mice: A similar mechanism as PFOA

GenX is an alternative to perfluorooctanoic acid (PFOA) and was included in the accession list of Substances of Very High Concern in 2019. Gestational GenX exposure induces maternal hepatotoxicity in animals. However, the mechanisms of GenX toxicity have not been explored. In the present study, pregnant Balb/c mice were administered with PFOA (1 mg/kg BW/day), GenX (2 mg/kg BW/day), or Milli-Q water by gavage during gestation. Similar hepatic pathological changes, including enlargement of hepatocytes, cytoplasm loss, nucleus migration, inflammatory cell infiltration, and reduction of glycogen storage, were observed in PFOA and GenX groups. Increased expression levels of indicators of the TLR4 pathway indicated activation of inflammation in the liver of maternal mice after exposure to PFOA or GenX, consistent with the pathological changes. Overexpression of cleaved PARP-1, cleaved caspase 3, Bax and decreased Bcl-2 proteins indicated activation of apoptosis, whereas overexpression of ULK-1, p62, beclin-1, LC3-II proteins and downregulation of p-mTOR implied that PFOA and GenX exposure initiated autophagy. Decreased secretion of mucus, reduced expression levels of tight junction proteins, and higher serum levels of lipopolysaccharide indicated disruption of the intestinal barrier. Translocation of lipopolysaccharide may be recognized by TLR4, thus triggering inflammatory pathway in the maternal liver. In summary, gestational exposure to PFOA or GenX induced maternal hepatic alterations through the gut-liver axis.

The Molecular Mechanism of Retina Light Injury Focusing on Damage from Short Wavelength Light

Natural visible light is an electromagnetic wave composed of a spectrum of monochromatic wavelengths, each with a characteristic color. Photons are the basic units of light, and their wavelength correlates to the energy of light; short-wavelength photons carry high energy. The retina is a fragile neuronal tissue that senses light and generates visual signals conducted to the brain. However, excessive and intensive light exposure will cause retinal light damage. Within the visible spectrum, short-wavelength light, such as blue light, carries higher energy, and thus the retinal injury, is more significant when exposed to these wavelengths. The damage mechanism triggered by different short-wavelength light varies due to photons carrying different energy and being absorbed by different photosensitive molecules in the retinal neurons. However, photooxidation might be a common molecular step to initiate cell death. Herein, we summarize the historical understanding of light, the key molecular steps related to retinal light injury, and the death pathways of photoreceptors to further decipher the molecular mechanism of retinal light injury and explore potential neuroprotective strategies.

The Antitumor Effect of TPD52L2 Silencing on Oxaliplatin-Resistant Gastric Carcinoma Is Related to Endoplasmic Reticulum Stress In Vitro

Tumor protein D52-like 2 or simply TPD52L2 belongs to the TPD52 family which has been implicated in a variety of human carcinomas. However, the TPD52L2 function in the gastric carcinoma oxaliplatin (OXA) resistance remains elusive. The main objective of this study is to evaluate the TPD52L2 effect in OXA-resistant gastric carcinoma cells in vitro. Oxaliplatin-resistant gastric carcinoma cells were generated in MGC-803 and SGC-7901 cells. siRNA-mediated knockdown of TPD52L2 was investigated in OXA-resistant MGC-803-OXA and SGC-7901-OXA cells. qRT-PCR was performed to assess the expression level of TPD52L2 mRNA. TPD52L2 protein expression level, apoptosis, and endoplasmic reticulum (ER) stress-associated proteins were identified via immunoblotting analysis. MTT assay was conducted for the evaluation of cell viability, while colony-forming activity was carried out via crystal violet staining. SGC-7901-OXA and MGC-803-OXA cells were found to be more resistant to OXA, as compared to the parental cell lines. The expression of TPD52L2 was found to be upregulated in OXA-resistant cells. Knockdown of TPD52L2 suppressed cell colony-forming potency, cell growth, and development in OXA-resistant cells. TPD52L2 knockdown also enhanced the PARP and caspase-3 cleavage. ER-associated proteins such as PERK, GRP78, CHOP, and IRE1α were found to be elevated in TPD52L2 knockdown cells. ER stress might be involved in TPD52L2 knockdown-induced apoptosis in OXA-resistant gastric carcinoma cells.

ε-Viniferin and α-viniferin alone or in combination induced apoptosis and necrosis in osteosarcoma and non-small cell lung cancer cells

This study investigated the effects and molecular mechanisms of ε-viniferin and α-viniferin in non-small cell lung cancer cell line A549, melanoma cell line A2058, and osteosarcoma cell lines HOS and U2OS. Results showed ε-viniferin having antiproliferative effects on HOS, U2OS, and A549 cells. Compared with ε-viniferin at the same concentration, α-viniferin had higher antiproliferative effects on HOS cells, but not the same effect on U2OS and A549 cells. Lower dose combination of α-viniferin and ε-viniferin had more synergistic effects on A549 cells than either drug alone. α-Viniferin induced apoptosis in HOS cells by decreasing expression of phospho-c-Jun-N-terminal kinase 1/2 (p-JNK1/2) and increasing expression of cleaved Poly (ADP-ribose) polymerase (PARP), whereas α-viniferin in combination with ε-viniferin induced apoptosis in A549 cells by decreasing expression of phospho-protein kinase B (p-AKT) and increasing expression of cleaved PARP and cleaved caspase-3. ε-Viniferin and α-viniferin have not been studied using in vivo tumor models for cancer. This research is the first showing that ε-viniferin treatment resulted in significant inhibition of tumor growth in A549-cell xenograft-bearing nude mice compared with the control group. Consequently, ε-viniferin and α-viniferin may prove to be new approaches and effective therapeutic agents for osteosarcoma and lung cancer treatment.

Protective Role of 4-Octyl Itaconate in Murine LPS/D-GalN-Induced Acute Liver Failure via Inhibiting Inflammation, Oxidative Stress, and Apoptosis

Oxidative stress, inflammation, and apoptosis are crucial in the pathogenesis of acute liver failure (ALF). 4-Octyl itaconate (OI) showed antioxidative and anti-inflammatory properties in many disease models. However, its role in lipopolysaccharide- (LPS-)/D-galactosamine- (D-GalN-) induced ALF is still not investigated. Here, we established an ALF murine model induced by LPS/D-GalN administration. And we found that OI improved survival rate in the murine ALF model. Our results also showed that OI alleviated LPS/D-GalN-induced hepatic histopathological injury and reduced the serum activities of alanine transaminase and aspartate transaminase. Moreover, OI reduced serum levels of proinflammatory cytokines such as monocyte chemotactic protein-1, tumor necrosis factors-α, and interlukin-6. Additionally, OI mitigated oxidative stress and alleviated lipid peroxidation in a murine model of ALF. This was evaluated by a reduction of thiobarbituric acid reactive substances (TBARS) in liver tissues. In addition, OI increased the ratio of reduced glutathione/oxidized glutathione and the activities of antioxidant enzymes including catalase and superoxide dismutase. Moreover, the apoptosis of hepatocytes in the liver was inhibited by OI. Furthermore, we found that OI inhibited LPS-induced nuclear translocation and activation of factor-kappa B (NF-κB) p65 in macrophages which could be inhibited by OI-induced activation of nuclear factor erythroid-2-related factor (Nrf2) signaling. Additionally, D-GalN-induced reactive oxygen species (ROS) generation and apoptosis in hepatocytes were inhibited by OI-induced activation of Nrf2 signaling. Therefore, the underlying mechanism for OI's protective effect in LPS/D-GalN-induced ALF may be associated with deactivation of NF-κB signaling in macrophages to reduce inflammation and inhibition of ROS-related hepatocyte apoptosis by activating Nrf2. In conclusion, OI showed a protective role in LPS/D-GalN-induced ALF by reducing inflammation, enhancing antioxidant capacity, and inhibiting cell apoptosis.

The hepatoprotective potential of resveratrol in an experimental model of ruptured abdominal aortic aneurysm via oxidative stress and apoptosis

The mortality rate in ruptured abdominal aortic aneurysms can today be reduced through cardiovascular surgery. However, ischemia and reperfusion-induced tissue damage develop due to aortic cross-clamping applied during surgery. The present study aimed to reduce oxidative stress-induced hepatic damage resulting from ischemia and reperfusion due to aortic cross-clamping during surgery by means of resveratrol administration. Forty male Sprague-Dawley rats were randomly assigned into four groups: control (healthy), glycerol+ischemia/reperfusion (I/R) (sham), I/R, and I/R + Resveratrol. In all groups scheduled for I/R, 60 min of shock was followed by 60 min of ischemia. In the I/R + Resveratrol group, 10 mg/kg of resveratrol was administered 15 min before ischemia and immediately before reperfusion via the intraperitoneal route. In addition, 120 min of reperfusion was applied under anesthesia after ischemia in all groups. Intralobar and interlobar necrosis, vascular congestion, and edematous fields resulting from aortic occlusion were present. Liver tissue malondialdehyde (MDA) levels and cleaved caspase-3 positivity increased, while glutathione (GSH) levels decreased. However, resveratrol administration reduced intralobular and interlobar necrosis, vascular congestion and edematous fields, cleaved caspase-3 positivity, and MDA levels, and increased GSH levels. Our findings suggest that resveratrol is effective against aortic occlusion-induced liver injury by reducing oxidative stress and apoptosis.

Nicotinamide Riboside and Pterostilbene Cooperatively Delay Motor Neuron Failure in ALS SOD1G93A Mice

Oxidative stress-induced damage is a major mechanism in the pathophysiology of amyotrophic lateral sclerosis (ALS). A recent human clinical trial showed that the combination of nicotinamide riboside (NR) and pterostilbene (PT), molecules with potential to interfere in that mechanism, was efficacious in ALS patients. We examined the effect of these molecules in SOD1G93A transgenic mice, a well-stablished model of ALS. Assessment of neuromotor activity and coordination was correlated with histopathology, and measurement of proinflammatory cytokines in the cerebrospinal fluid. Cell death, Nrf2- and redox-dependent enzymes and metabolites, and sirtuin activities were studied in isolated motor neurons. NR and PT increased survival and ameliorated ALS-associated loss of neuromotor functions in SOD1G93A transgenic mice. NR and PT also decreased the microgliosis and astrogliosis associated with ALS progression. Increased levels of proinflammatory cytokines were observed in the cerebrospinal fluid of mice and humans with ALS. NR and PT ameliorated TNFα-induced oxidative stress and motor neuron death in vitro. Our results support the involvement of oxidative stress, specific Nrf2-dependent antioxidant defenses, and sirtuins in the pathophysiology of ALS. NR and PT interfere with the mechanisms leading to the release of proapoptotic molecular signals by mitochondria, and also promote mitophagy.

Network Pharmacology-Based Approach to Comparatively Predict the Active Ingredients and Molecular Targets of Compound Xueshuantong Capsule and Hexuemingmu Tablet in the Treatment of Proliferative Diabetic Retinopathy

Background

Compound Xueshuantong capsule (CXC) and Hexuemingmu tablet (HXMMT) are two important Chinese patent medicines (CPMs) frequently used to treat proliferative diabetic retinopathy (PDR), especially when complicated with vitreous hemorrhage (VH). However, a network pharmacology approach to understand the therapeutic mechanisms of these two CPMs in PDR has not been applied.

Objective

To identify differences in the active ingredients between CXC and HXMMT and to comparatively predict and further analyze the molecular targets shared by these CPMs and PDR. Materials and methods. The differentially expressed messenger RNAs (mRNAs) between normal retinal tissues in healthy individuals and active fibrovascular membranes in PDR patients were retrieved from the Gene Expression Omnibus database. The active ingredients of CXC and HXMMT and the targets of these ingredients were retrieved from the Traditional Chinese Medicine Systems Pharmacology database. The intersections of the CPM (CXC and HXMMT) targets and PDR targets were determined. Then, Gene Ontology and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses were performed, and the ingredient-target networks, protein-protein interaction networks, and KEGG-target (KEGG-T) networks were constructed.

Results

CXC contains 4 herbs, and HXMMT contains 19. Radix salviae is the only herb common to both. CXC had 34 potential therapeutic targets in PDR, while HXMMT had these 34 and 10 additional targets. Both CPMs shared the following main processes: response to reactive oxygen species and oxidative stress, regulation of blood vessel diameter and size, vasoconstriction, smooth muscle contraction, hemostasis, and blood coagulation. The shared pathways included the AGE-RAGE signaling pathway in diabetic complications, TNF signaling pathway, relaxin signaling pathway, and IL-17 signaling pathway.

Conclusions

Both CXC and HXMMT include components effective at treating PDR and affect the following main processes: response to reactive oxygen species and oxidative stress, regulation of blood vessels, and blood coagulation. Radix salviae, the only herb common to both CPMs, contains many useful active ingredients. The PDR-CXC and PDR-HXMMT networks shared 34 common genes (RELA, HSPA8, HSP90AA, HSP90AB1, BRCA, EWSR1, CUL7, HNRNPU, MYC, CTNNB1, MDM2, YWHAZ, CDK2, AR, FN1, HUWE1, TP53, TUBB, EP300, GRB2, VCP, MCM2, EEF1A1, NTRK1, TRAF6, EGFR, PRKDC, SRC, HDAC5, APP, ESR1, AKT1, UBC, and COPS5), and the PDR-HXMMT network has 10 additional genes (RNF2, VNL, RPS27, COPS5, XPO1, PARP1, RACK1, YWHAB, and ITGA4). The top 5 pathways with the highest gene ratio in both networks were the AGE-RAGE signaling pathway in diabetic complications, TNF signaling pathway, relaxin signaling pathway, IL-17 signaling pathway, and focal adhesion. Additional pathways such as neuroactive ligand-receptor interaction, chemokine signaling pathway, and AMPK signaling pathway were enriched with HXMMT targets. Thus, HXMMT has more therapeutic targets shared by different active ingredients and more abundant gene functions than CXC, which may be two major reasons why HXMMT is more strongly recommended than CXC as an auxiliary treatment for new-onset VH secondary to PDR. However, the underlying mechanisms still need to be further explored.

Insight into the potential application of polyphenol-rich dietary intervention in degenerative disease management

In recent times, a great number of plants have been studied in order to identify new components with nutraceutical properties, among which are polyphenols. Dietary polyphenols represent a large group of bioactive molecules widely found in the food of plant origin and they have been found able to prevent the onset and progression of degenerative diseases, and to reduce and control their symptoms. These health protective effects have been mainly related to their antioxidant and anti-inflammatory properties. However, it must be considered that the application of isolated polyphenols as nutraceuticals is quite limited due to their poor systemic distribution and relative bioavailability. The present review highlights the potential effect of dietary intervention with polyphenol-rich food and plant extracts in patients with cancer, diabetes and neurodegenerative, autoimmune, cardiovascular and ophthalmic diseases, as well as the possible molecular mechanisms of action suggested in numerous studies with animal models.

Synthesis and Photoactivated Toxicity of 2-Thiophenylfuranocoumarin Induce Midgut Damage and Apoptosis in Aedes aegypti Larvae

Furanocoumarins are photoactive compounds derived from secondary plant metabolites. They possess many bioactivities, including antioxidative, anticancer, insecticidal, and bactericidal activities. Here, we designed a new scheme for synthesizing 2-arylfuranocoumarin derivatives by condensation, esterification, bromination, and Wittig reaction. We found that 2-thiophenylfuranocoumarin (Iy) had excellent photosensitive activity. Three Iy concentrations (LC₂₅, LC₅₀, and LC₇₅) were used to treat the fourth instar larvae of Aedes aegypti (A. aegypti). The photoactivated toxicity, sublethal dose, mitochondrial dysfunction, oxidative stress level, intestinal barrier dysfunction, and apoptosis were studied. The results showed that Iy induced reactive oxygen species (ROS) production in midgut cells under ultraviolet light. Ultrastructural analysis demonstrated that mitochondria were damaged, and the activities of related enzymes were inhibited. Ultimately, Iy exposure led to excessive ROS production followed by the inhibition of antioxidant enzymes, including SOD, CAT, GPx, and GR, which diminished ROS elimination and escalated oxidative stress in midgut cells, aggravating the degree of oxidative damage in these cells. Histopathological changes were observed in the midgut, which led to intestinal barrier dysfunction. When the elimination of ROS was blocked and it accumulated in cells, apoptosis-related genes, including AeDronc, AeCaspase7, and AeCaspase8, were induced and activated. In addition, Iy affected the growth and development of A. aegypti at sublethal concentrations, and there was an obvious post-lethal effect. Thus, we found that Iy caused midgut damage and apoptosis in A. aegypti larvae under ultraviolet light, which preliminarily revealed the mode of action of Iy in A. aegypti.

Microfluidic and Microscale Assays to Examine Regenerative Strategies in the Neuro Retina

Bioengineering systems have transformed scientific knowledge of cellular behaviors in the nervous system (NS) and pioneered innovative, regenerative therapies to treat adult neural disorders. Microscale systems with characteristic lengths of single to hundreds of microns have examined the development and specialized behaviors of numerous neuromuscular and neurosensory components of the NS. The visual system is comprised of the eye sensory organ and its connecting pathways to the visual cortex. Significant vision loss arises from dysfunction in the retina, the photosensitive tissue at the eye posterior that achieves phototransduction of light to form images in the brain. Retinal regenerative medicine has embraced microfluidic technologies to manipulate stem-like cells for transplantation therapies, where de/differentiated cells are introduced within adult tissue to replace dysfunctional or damaged neurons. Microfluidic systems coupled with stem cell biology and biomaterials have produced exciting advances to restore vision. The current article reviews contemporary microfluidic technologies and microfluidics-enhanced bioassays, developed to interrogate cellular responses to adult retinal cues. The focus is on applications of microfluidics and microscale assays within mammalian sensory retina, or neuro retina, comprised of five types of retinal neurons (photoreceptors, horizontal, bipolar, amacrine, retinal ganglion) and one neuroglia (Müller), but excludes the non-sensory, retinal pigmented epithelium.

Natural Products: Evidence for Neuroprotection to Be Exploited in Glaucoma

Glaucoma, a leading cause of irreversible blindness worldwide, is an optic neuropathy characterized by the progressive death of retinal ganglion cells (RGCs). Elevated intraocular pressure (IOP) is recognized as the main risk factor. Despite effective IOP-lowering therapies, the disease progresses in a significant number of patients. Therefore, alternative IOP-independent strategies aiming at halting or delaying RGC degeneration is the current therapeutic challenge for glaucoma management. Here, we review the literature on the neuroprotective activities, and the underlying mechanisms, of natural compounds and dietary supplements in experimental and clinical glaucoma.

Suppressing endoplasmic reticulum stress-related autophagy attenuates retinal light injury

Excessive light exposure is a principal environmental factor, which can cause damage to photoreceptors and retinal pigment epithelium (RPE) cells and may accelerate the progression of age-related macular degeneration (AMD). In this study, oxidative stress, endoplasmic reticulum (ER) stress and autophagy caused by light exposure were evaluated in vitro and in vivo. Light exposure caused severe photo-oxidative stress and ER stress in photoreceptors (661W cells) and RPE cells (ARPE-19 cells). Suppressing either oxidative stress or ER stress was protective against light damage in 661W and ARPE-19 cells and N-acetyl-L-cysteine treatment markedly inhibited the activation of ER stress caused by light exposure. Moreover, suppressing autophagy with 3-methyladenine significantly attenuated light-induced cell death. Additionally, inhibiting ER stress either by knocking down PERK signals or with GSK2606414 treatment remarkably suppressed prolonged autophagy and protected the cells against light injury. In vivo experiments verified neuroprotection via inhibiting ER stress-related autophagy in light-damaged retinas of mice. In conclusion, the above results suggest that light-induced photo-oxidative stress may trigger subsequent activation of ER stress and prolonged autophagy in photoreceptors and RPE cells. Suppressing ER stress may abrogate over-activated autophagy and protect the retina against light injury.

Erdosteine salvages cardiac necrosis: Novel effect through modulation of MAPK and Nrf-2/HO-1 pathway

Isoproterenol (ISO) induced oxidative stress and inflammation is involved in the pathogenesis of myocardial necrosis. To optimize the effect of erdosteine against myocardial necrosis, male albino Wistar rats were divided into eight groups (n = 6), that is, normal, ISO-control, erdosteine pretreatment with ISO. Rats were administered erdosteine orally for 28 days. Two doses of ISO (85 mg/kg), s.c. were given to ISO-C and erdosteine treatment groups on the 27th and 28th day. On the 29th day, hemodynamic parameters were recorded and the heart was excised for further parameters. In ISO-C rats, significantly increased levels of inflammatory markers, pro-oxidants, and structural damage were observed as compared with normal group. Furthermore, immunohistochemistry and terminal deoxynucleotidyl transferase dUTP nick end labeling revealed an increased expression of apoptotic proteins. Erdosteine at 80 mg/kg reversed the deleterious effects of ISO and normalized myocardium. Erdosteine showed anti-inflammatory, antiapoptotic, and antioxidant activities through inhibition of MAPK and Nrf-2/HO-1 pathways. To conclude, erdosteine was found protective in ISO-induced myocardial necrosis through MAPK and Nrf-2/HO-1 pathway.

mTOR may interact with PARP-1 to regulate visible light-induced parthanatos in photoreceptors

BACKGROUND

Excessive light exposure is a detrimental environmental factor that plays a critical role in the pathogenesis of retinal degeneration. However, the mechanism of light-induced death of retina/photoreceptor cells remains unclear. The mammalian/mechanistic target of rapamycin (mTOR) and Poly (ADP-ribose) polymerase-1 (PARP-1) have become the primary targets for treating many neurodegenerative disorders. The aim of this study was to elucidate the mechanisms underlying light-induced photoreceptor cell death and whether the neuroprotective effects of mTOR and PARP-1 inhibition against death are mediated through apoptosis-inducing factor (AIF).

METHODS

Propidium iodide (PI)/Hoechst staining, lentiviral-mediated short hairpin RNA (shRNA), Western blot analysis, cellular fraction separation, plasmid transient transfection, laser confocal microscopy, a mice model, electroretinography (ERG), and hematoxylin-eosin (H & E) staining were employed to explore the mechanisms by which rapamycin/3-Aminobenzamide (3AB) exert neuroprotective effects of mTOR/PARP-1 inhibition in light-injured retinas.

RESULTS

A parthanatos-like death mechanism was evaluated in light-injured 661 W cells that are an immortalized photoreceptor-like cell line that exhibit cellular and biochemical feature characteristics of cone photoreceptor cells. The death process featured over-activation of PARP-1 and AIF nuclear translocation. Either PARP-1 or AIF knockdown played a significantly protective role for light-damaged photoreceptors. More importantly, crosstalk was observed between mTOR and PARP-1 signaling and mTOR could have regulated parthanatos via the intermediate factor sirtuin 1 (SIRT1). The parthanatos-like injury was also verified in vivo, wherein either PARP-1 or mTOR inhibition provided significant neuroprotection against light-induced injury, which is evinced by both structural and functional retinal analysis. Overall, these results elucidate the mTOR-regulated parthanatos death mechanism in light-injured photoreceptors/retinas and may facilitate the development of novel neuroprotective therapies for retinal degeneration diseases.

CONCLUSIONS

Our results demonstrate that inhibition of the mTOR/PARP-1 axis exerts protective effects on photoreceptors against visible-light-induced parthanatos. These protective effects are conducted by regulating the downstream factors of AIF, while mTOR possibly interacts with PARP-1 via SIRT1 to regulate parthanatos. Video Abstract Schematic diagram of mTOR interacting with PARP-1 to regulate visible light-induced parthanatos. Increased ROS caused by light exposure penetrates the nuclear membrane and causes nuclear DNA strand breaks. PARP-1 detects DNA breaks and synthesizes PAR polymers to initiate the DNA repair system that consumes a large amount of cellular NAD+. Over-production of PAR polymers prompts the release of AIF from the mitochondria and translocation to the nucleus, which leads to parthanatos. Activated mTOR may interact with PARP-1 via SIRT1 to regulate visible light-induced parthanatos.

Bone marrow mesenchymal stem cells enhance autophagy and help protect cells under hypoxic and retinal detachment conditions

Our study aimed to evaluate the protective role and mechanisms of bone marrow mesenchymal stem cells (BMSCs) in hypoxic photoreceptors and experimental retinal detachment. The cellular morphology, viability, apoptosis and autophagy of hypoxic 661w cells and cells cocultured with BMSCs were analysed. In retinal detachment model, BMSCs were intraocularly transplanted, and then, the retinal morphology, outer nuclear layer (ONL) thickness and rhodopsin expression were studied as well as apoptosis and autophagy of the retinal cells. The hypoxia‐induced apoptosis of 661w cells obviously increased together with autophagy levels increasing and peaking at 8 hours after hypoxia. Upon coculturing with BMSCs, hypoxic 661w cells had a better morphology and fewer apoptosis. After autophagy was inhibited, the apoptotic 661w cells under the hypoxia increased, and the cell viability was reduced, even in the presence of transplanted BMSCs. In retina‐detached eyes transplanted with BMSCs, the retinal ONL thickness was closer to that of the normal retina. After transplantation, apoptosis decreased significantly and retinal autophagy was activated in the BMSC‐treated retinas. Increased autophagy in the early stage could facilitate the survival of 661w cells under hypoxic stress. Coculturing with BMSCs protects 661w cells from hypoxic damage, possibly due to autophagy activation. In retinal detachment models, BMSC transplantation can significantly reduce photoreceptor cell death and preserve retinal structure. The capacity of BMSCs to reduce retinal cell apoptosis and to initiate autophagy shortly after transplantation may facilitate the survival of retinal cells in the low‐oxygen and nutrition‐restricted milieu after retinal detachment.

The Retinoid and Non-Retinoid Ligands of the Rod Visual G Protein-Coupled Receptor

G protein-coupled receptors (GPCRs) play a predominant role in the drug discovery effort. These cell surface receptors are activated by a variety of specific ligands that bind to the orthosteric binding pocket located in the extracellular part of the receptor. In addition, the potential binding sites located on the surface of the receptor enable their allosteric modulation with critical consequences for their function and pharmacology. For decades, drug discovery focused on targeting the GPCR orthosteric binding sites. However, finding that GPCRs can be modulated allosterically opened a new venue for developing novel pharmacological modulators with higher specificity. Alternatively, focus on discovering of non-retinoid small molecules beneficial in retinopathies associated with mutations in rhodopsin is currently a fast-growing pharmacological field. In this review, we summarize the accumulated knowledge on retinoid ligands and non-retinoid modulators of the light-sensing GPCR, rhodopsin and their potential in combating the specific vision-related pathologies. Also, recent findings reporting the potential of biologically active compounds derived from natural products as potent rod opsin modulators with beneficial effects against degenerative diseases related to this receptor are highlighted here.

Structure-based identification of novel sirtuin inhibitors against triple negative breast cancer: An in silico and in vitro study

Triple-negative breast cancer (TNBC) is an aggressive disease exemplified by a poor prognosis, greater degrees of relapse, the absence of hormonal receptors for coherent utilization of targeted therapy, poor response to currently available therapeutics and development of chemoresistance. Aberrant activity of sirtuins (SIRTs) has strong implications in the metastatic and oncogenic progression of TNBC. Synthetic SIRT inhibitors are effective, however, they have shown adverse side effects emphasizing the need for plant-derived inhibitors (PDIs). In the current study, we identified potential plant-derived sirtuin inhibitors using in silico approach i.e. molecular docking, ADMET and molecular dynamics simulations (MD). Docking studies revealed that Sulforaphane, Kaempferol and Apigenin exhibits the highest docking scores against SIRT1 & 5, 3 and 6 respectively. ADMET analysis of above hits demonstrated drug-like profile. MD of prioritized SIRTs-PDIs complexes displayed stability with insignificant deviations throughout the trajectory. Furthermore, we determined the effect of our prioritized molecules on cellular viability, global activity as well as protein expression of sirtuins and stemness of TNBC cells utilizing in vitro techniques. Our in vitro findings complements our in silico results. Collectively, these findings provide a better insight into the structural basis of sirtuin inhibition and can facilitate drug design process for TNBC management.

14-Deoxycoleon U-induced endoplasmic reticulum stress-mediated apoptosis, autophagy, and cell cycle arrest in lung adenocarcinoma

Objective

14-Deoxycoleon U is a natural abietane-type diterpene and exerts an inhibitory effect on tumor cells proliferation, which suggests that 14-Deoxycoleon U may be a potent anti-cancerous lead compound for lung cancer treatment. This study was to evaluate potential of 14-Deoxycoleon U to treat lung adenocarcinoma in vitro and in vivo.

Methods

In the present study, the cell viability and apoptosis morphology of 14-Deoxycoleon U-treated A549 and LLC cells were explored using cell counting kit-8 assay and Hoechst 33258 staining. Then, the protein expressions about apoptosis, endoplasmic reticulum (ER) stress, autophagy and cell cycle were measured using Western blot. The autophagosome formation of 14-Deoxycoleon U-treated A549 cells was visualized using a confocal microscopy. LLC lung adenocarcinoma model was established.

Results

The results indicated that 14-Deoxycoleon U significantly inhibited A549 and LLC cell proliferation in a dose-dependent manner via caspase-dependent apoptosis. Furthermore, apoptosis of both cells was mediated by 14-Deoxycoleon U-induced ER stress. In addition, 14-Deoxycoleon U-induced A549 and LLC cell autophagy, thus promoting their death. Moreover, 14-Deoxycoleon U-induced cell cycle arrest in both cells via inhibition of cyclin D3, cyclin-dependent kinase 6, CDC2 and up-regulation of p21. In vivo results showed that administration of 14-Deoxycoleon U significantly suppressed LLC growth and adverse effects of 14-Deoxycoleon U on organs might be lower than of adriamycin.

Conclusion

Overall, our results demonstrated that 14-Deoxycoleon U represses in vitro and in vivo growth of lung adenocarcinoma through ER stress-mediated apoptosis accompanied by autophagy and cell cycle arrest.

Cell death induced by α-terthienyl via reactive oxygen species-mediated mitochondrial dysfunction and oxidative stress in the midgut of Aedes aegypti larvae

α-Terthienyl (α-T) is a photosensitizer that produces many reactive oxygen species (ROS) under ultraviolet light. Here, we aimed to evaluate the oxidation mechanism of the 25%, 50%, and 75% lethal concentrations in Aedes aegypti larvae; the lethal concentration of α-T was used as the test value. The effects on mitochondria, oxidative stress, and cell death patterns caused by ROS were evaluated. The results showed that α-T mainly produced large amounts of ROS in the midgut of larvae. Moreover, mitochondrial ROS were increased in midgut cells, and the production of ROS sites, such as complex enzymes, was inhibited, resulting in enhanced production of ROS. Ultrastructural analysis of mitochondria revealed significant vacuolation, decreased activity of tricarboxylic acid cycle enzymes, and reduced ATP content and mitochondrial membrane potential in the high concentration group compared with those in the control group. Additionally, mitochondrial biosynthesis was blocked in the high concentration group. Thus, exposure to α-T disrupted mitochondrial function, although the mitochondrial DNA content may have increased because of mitochondrial self-protection mechanisms against oxidative stress. Furthermore, high concentrations of α-T aggravated oxidative stress and increased the number of intracellular oxidative damage products. Reverse transcription polymerase chain reaction and fluorescence staining showed that ROS induced by low α-T concentrations upregulated apoptotic genes, including Dronc (P < 0.05), thereby promoting apoptosis. Moderate concentrations of α-T promoted autophagy through induction of ROS, inhibited apoptosis, and induced necrosis. In contrast, high α-T concentrations induced high levels of ROS, which caused mitochondrial dysfunction and increased cytoplasmic Ca²⁺ concentration, directly inducing cell necrosis. We also found that α-T may disrupt the permeability of the peritrophic membrane, leading to intestinal barrier dysfunction. These results provided insights into the mode of action of α-T in Aedes aegypti.

Decrease of MLK4 prevents hepatocellular carcinoma (HCC) through reducing metastasis and inducing apoptosis regulated by ROS/MAPKs signaling

Hepatocellular carcinoma (HCC) results in large amounts of deaths each year worldwide. To develop more effective treatments for HCC, it is very necessary to define the molecular mechanisms in hepatocarcinogenesis. Mixed lineage kinase (MLK)-4 is a member of the MLK family of mitogen-activated protein kinase kinase kinases, and modulates different cellular responses. However, its role in the meditation of HCC progression remains unclear. In the study, we found that MLK4 was over-expressed in tumor samples of HCC patients. High MLK4 expression was significantly associated with shorter overall survival in HCC. Knockdown of MLK4 inhibited HCC cell proliferation and metastasis, which was partly through reducing matrix metalloproteinase (MMP)-13, MMP2, enhancer of zeste homolog 2 (EZH2) and Vimentin expressions. Apoptosis was significantly induced by MLK4 knockdown in HCC cells via decreasing Bcl-2 and increasing cleaved poly (ADP-ribose) polymerase (PARP), Caspase-7 and -3 expression levels. In addition, MLK4 silence led to a significant reactive oxygen species (ROS) production in liver cancer cells, accompanied with elevated expression of phosphorylated p38, c-Jun N-terminal kinase (JNK) and ERK1/2. Notably, reducing ROS generation and blocking MAPKs (p38/JNK/ERK1/2) signaling markedly abrogated MLK4 knockdown-induced apoptosis in HCC cells. Moreover, MLK4 silence-prevented metastasis was also rescued by scavenging ROS generation and repressing MAPKs pathway. In vivo, injection of MLK4 siRNA markedly inhibited liver tumor growth in xenograft models, and MLK4 knockdown reduced HCC lung metastasis. Together, our study indicated the essential function of MLK4 in HCC progression, providing crucial therapeutic hypothesis for the prevention of hepatocellular carcinoma.