High glucose induces an early and transient cytoprotective autophagy in retinal Müller cells

Diphlorethohydroxycarmalol inhibits Müller cell gliosis by disrupting CXCR4/CXCL12 interaction in violet-blue light-induced retinal phototoxicity

Müller gliosis is a complex process that impairs the ability of retinal Müller glial cells to respond to various forms of retinal injury or disease, leading to retinal damage. Blue light (BL) exposure is a known cause of retinal damage. In this study, we aimed to investigate the potential of DPHC in inhibiting Müller gliosis in models of BL-exposure. We conducted in silico binding analysis to evaluate the binding of DPHC to CXCR4. Then, we developed in vitro and in vivo experimental models to assess the effects of DPHC and BL exposure on Müller gliosis using MIO-M1 cells and zebrafish. Our findings show that DPHC can suppress the Müller gliosis process in BL-exposed MIO-M1 cells in vitro and in BL-exposed zebrafish in vivo. In silico molecular docking, we identified CXCR4 as the target of active site 1 of DPHC. In BL-exposed MIO-M1 cells, DPHC inhibited CXCR4 activity and altered the expression of Müller gliosis markers and NF-κB-related ERK and AKT signaling. In BL-exposed zebrafish, DPHC prevented retinal thickness reduction and inhibited CXCR4 expression and retinal cell apoptosis. This study suggests that DPHC could be a potential therapeutic agent for retinal diseases involving Müller gliosis. By inhibiting CXCR4 activity, DPHC downregulates the ERK/AKT/NF-κB pathway, reducing retinal cell apoptosis and altered expression of Müller gliosis markers. These findings highlight the potential of natural bioactive compounds for treating various diseases, and further research should investigate the therapeutic potential of DPHC and its derivatives.

Underlying mechanisms of traditional Chinese medicine in the prevention and treatment of diabetic retinopathy: Evidences from molecular and clinical studies

As one of the most serious microvascular complications of diabetes mellitus (DM), diabetic retinopathy (DR) can cause visual impairment and even blindness. With the rapid increase in the prevalence of DM, the incidence of DR is also rising year by year. Preventing and effectively treating DR has become a major focus in the medical field. Traditional Chinese medicine (TCM) has a wealth of experience in treating DR and has achieved significant results with various herbs and TCM prescriptions. Traditional Chinese Medicine (TCM) provides a comprehensive therapeutic strategy for diabetic retinopathy (DR), encompassing anti-inflammatory and antioxidant actions, anti-neovascularization, neuroprotection, regulation of glucose metabolism, and inhibition of apoptosis. This review provides an overview of the current status of TCM treatment for DR in recent years, including experimental studies and clinical researches, to explore the clinical efficacy and the underlying modern mechanisms of herbs and TCM prescriptions. Besides, we also discussed the challenges TCM faces in treating DR, such as drug-drug interactions among TCM components and the lack of high-quality evidence-based medicine practice, which pose significant obstacles to TCM's application in DR.

In Vitro Models of Diabetes: Focus on Diabetic Retinopathy

Diabetic retinopathy is a major eye complication in patients with diabetes mellitus, and it is the leading cause of blindness and visual impairment in the world. Chronic hyperglycemia induces endothelial damage with consequent vascular lesions, resulting in global vasculitis, which affects the small vessels of the retina. These vascular lesions cause ischemic conditions in certain areas of the retina, with a consequent increase in the release of pro-angiogenic mediators. In addition to pharmacological interventions for controlling the blood glycaemic level, the main strategies for treating diabetic retinopathy are the intravitreal injections of drugs, surgical treatments, and vitrectomies. The complexity of diabetic retinopathy is due to its close interactions with different cell types (endothelial cells, astrocytes, and Müller cells). The evaluation of the efficacy of novel pharmacological strategies is mainly performed through in vivo models. However, the use of different animal species leads to heterogenic results and ethical concerns. For these reasons, the development of new and reliable in vitro models, such as cell co-cultures and eye organoids, represents an urgent need in this area of research. This review features an overview of the in vitro models used to date and highlights the advances in technology used to study this pathology.

ANXA2 promotes osteogenic differentiation and inhibits cellular senescence of periodontal ligament cells (PDLCs) in high glucose conditions

Background

Periodontal ligament cells (PDLCs) are a major component of the periodontal ligament and have an important role in the regeneration of periodontal tissue and maintenance of homeostasis. High glucose can affect the activity and function of PDLCs in a variety of ways; therefore, it is particularly important to find ways to alleviate the effects of high glucose on PDLCs. Annexin A2 (ANXA2) is a calcium- and phospholipid-binding protein involved in a variety of cellular functions and processes, including cellular cytokinesis, cytophagy, migration, and proliferation.

Aim

The aim of this study was to exploring whether ANXA2 attenuates the deleterious effects of high glucose on PDLCs and promotes osteogenic differentiation capacity.

Methods and results

Osteogenic differentiation potential, cellular senescence, oxidative stress, and cellular autophagy were detected. Culturing PDLCs with medium containing different glucose concentrations (CTRL, 8 mM, 10 mM, 25 mM, and 40 mM) revealed that high glucose decreased the protein expression of ANXA2 (p < 0.0001). In addition, high glucose decreased the osteogenic differentiation potential of PDLCs as evidenced by decreased calcium deposition (p = 0.0003), lowered ALP activity (p = 0.0010), and a decline in the expression of osteogenesis-related genes (p = 0.0008). Moreover, β-Galactosidase staining and expression of p16, p21 and p53 genes showed that it increased cellular senescence in PDLCs (p < 0.0001). Meanwhile high glucose increased oxidative stress in PDLCs as shown by ROS (p < 0.0001). However, these damages caused by high glucose were inhibited after the addition of 1 µM recombinant ANXA2 (rANXA2), and we found that rANXA2 enhanced autophagy in PDLCs under high glucose conditions.

Conclusions and discussion

Therefore, our present study demonstrates that alterations in ANXA2 under high glucose conditions may be a factor in the decreased osteogenic differentiation potential of PDLCs. Meanwhile, ANXA2 is associated with autophagy, oxidative stress, and cellular senescence under high glucose conditions.

FTY720 Suppresses Pathogenic Retinal Müller Cell Activation and Chronic Progression by Inhibiting the mTOR/NF-κB Signaling Pathway and Regulating Autophagy

PURPOSE

FTY720 is an agonist of the Sphingosine-1-phosphate (S1P) receptor 1, 3, 4, and 5 and a functional antagonist of the S1P1 receptor; it can inhibit the activation of mTOR/NF-κB and has therapeutic potential in inflammatory disease. This study was designed to determine the role of the inflammatory process in diabetic retinopathy and investigate the effect of FTY720 on high glucose (HG)-induced rat retinal Müller cells (rMC-1 cells).

METHODS

In the present study, the role of FTY720 in inhibiting inflammation and its underlying mechanism were investigated. rMC-1 cells were treated without or with HG, FTY720, CQ, or RAP. Cell viability was examined by CCK-8 assay; cell activation was assessed by western blot analysis and IF staining; and cell migration was evaluated by a scratch wound healing assay. The expression of inflammation-associated proteins and autophagy-related proteins was evaluated by transmission electron microscopy, AO staining, MDC-labeled autophagic vacuoles, western blot analysis and ELISA.

RESULTS

Western blot analysis and IF staining showed that the level of the rMC-1 cell marker GFAP was decreased, while GS was increased in FTY720 groups compared to that in the HG group. The healing assay results showed that compared with HG treatment, FTY720 treatment significantly reduced cell migration. Western blot analysis, ELISA and IF staining showed that compared with HG, FTY720 reduced proinflammatory proteins by inhibiting the mechanistic target of the mTOR/NF-κB signaling pathway and regulating autophagy.

CONCLUSIONS

This study suggests that in an HG-induced rMC-1 cell model, FTY720 significantly inhibited the production of inflammatory cytokines by inhibiting mTOR/NF-κB signaling and regulating autophagy. These findings were associated with a decrease in rMC-1 cell injury, suggesting that FTY720 or related compounds may be valuable modulators of HG-induced retinal injury.

Prostaglandin F2 Receptor Negative Regulator (PTGFRN) Expression Correlates With a Metastatic-like Phenotype in Epidermoid Carcinoma, Pediatric Medulloblastoma, and Mesothelioma

Prostaglandin F2 receptor negative regulator (PTGFRN) is a transmembrane protein associated with metastatic characteristics of certain cancer types. However, it remains poorly characterized and its direct function in cancer remains unclear. The study presented here aims to further examine whether PTGFRN expression affects a cancer cell's phenotype, as well as metastatic-like characteristics. We used stable shRNA and cDNA transfections to respectively knockdown and overexpress PTGFRN in three different cancer cell lines, two of which are representative of rare and aggressive cancers (Mesothelioma and Pediatric Medulloblastoma). We then examined the characteristics of the resulting clones and showed a decrease in proliferation, migration, colony formation, and spheroid growth capabilities in cells where PTGFRN expression had been inhibited, while cells overexpressing PTGFRN showed the opposite. In addition, we showed that PTGFRN displayed direct binding to two protein partners, Integrin β1 and E. Cadherin, the latter of which is a novel direct binding partner to PTGFRN. Furthermore, silencing PTGFRN expression impacted the cellular process of autophagy, thereby providing another avenue by which PTGFRN potentially contributes to a cancer cell phenotype. Our findings demonstrate the potential role of PTGFRN in cancer metastasis and suggest PTGFRN as a future target for drug development in the treatment of metastatic cancers.

Eye Diseases: When the Solution Comes from Plant Alkaloids

Plants are an incredible source of metabolites showing a wide range of biological activities. Among these, there are the alkaloids, which have been exploited for medical purposes since ancient times. Nowadays, many plant-derived alkaloids are the main components of drugs used as therapy for different human diseases. This review deals with providing an overview of the alkaloids used to treat eye diseases, describing the historical outline, the plants from which they are extracted, and the clinical and molecular data supporting their therapeutic activity. Among the different alkaloids that have found application in medicine so far, atropine and pilocarpine are the most characterized ones. Conversely, caffeine and berberine have been proposed for the treatment of different eye disorders, but further studies are still necessary to fully understand their clinical value. Lastly, the alkaloid used for managing hypertension, reserpine, has been recently identified as a potential drug for ameliorating retinal disorders. Other important aspects discussed in this review are different solutions for alkaloid production. Given that the industrial production of many of the plant-derived alkaloids still relies on extraction from plants, and the chemical synthesis can be highly expensive and poorly efficient, alternative methods need to be found. Biotechnologies offer a multitude of possibilities to overcome these issues, spanning from genetic engineering to synthetic biology for microorganisms and bioreactors for plant cell cultures. However, further efforts are needed to completely satisfy the pharmaceutical demand.

Cellular and Molecular Mechanisms of Neuronal Degeneration in Early-Stage Diabetic Retinopathy

BACKGROUND

Studies on the early retinal changes in Diabetic Retinopathy (DR) have demonstrated that neurodegeneration precedes vascular abnormalities like microaneurysms or intraretinal hemorrhages. Therefore, there is a growing field of study to analyze the cellular and molecular pathways involved to allow for the development of novel therapeutics to prevent the onset or delay the progression of DR. Molecular Mechanisms: Oxidative stress and mitochondrial dysfunction contribute to neurodegeneration through pathways involving polyol, hexosamine, advanced glycation end products, and protein kinase C. Potential interventions targeting these pathways include aldose reductase inhibitors and protein kinase C inhibitors. Neurotrophic factor imbalances, notably brain-derived neurotrophic factor and nerve growth factor, also play a role in early neurodegeneration, and supplementation of these neurotrophic factors show promise in mitigating neurodegeneration. Cellular Mechanisms: Major cellular mechanisms of neurodegeneration include caspase-mediated apoptosis, glial cell reactivity, and glutamate excitotoxicity. Therefore, inhibitors of these pathways are potential therapeutic avenues. Vascular Component: The nitric oxide pathway, critical for neurovascular coupling, is disrupted in DR due to increased reactive oxygen species. Vascular Endothelial Growth Factor (VEGF), a long-known angiogenic factor, has demonstrated both damaging and neuroprotective effects, prompting a careful consideration of long-term anti-VEGF therapy.

CONCLUSION

Current DR treatments primarily address vascular symptoms but fall short of preventing or halting the disease. Insights into the mechanisms of retinal neurodegeneration in the setting of diabetes mellitus not only enhance our understanding of DR but also pave the way for future therapeutic interventions aimed at preventing disease progression and preserving vision.

Antitumoral effects of Bortezomib in malignant mesothelioma: evidence of mild endoplasmic reticulum stress in vitro and activation of T cell response in vivo

BACKGROUND

Malignant mesothelioma (MM) is a rare tumor with a dismal prognosis. The low efficacy of current treatment options highlights the urge to identify more effective therapies aimed at improving MM patients' survival. Bortezomib (Bor) is a specific and reversible inhibitor of the chymotrypsin-like activity of the 20S core of the proteasome, currently approved for the treatment of multiple myeloma and mantle cell lymphoma. On the other hand, Bor appears to have limited clinical effects on solid tumors, because of its low penetration and accumulation into tumor tissues following intravenous administration. These limitations could be overcome in MM through intracavitary delivery, with the advantage of increasing local drug concentration and decreasing systemic toxicity.

METHODS

In this study, we investigated the effects of Bor on cell survival, cell cycle distribution and modulation of apoptotic and pro-survival pathways in human MM cell lines of different histotypes cultured in vitro. Further, using a mouse MM cell line that reproducibly forms ascites when intraperitoneally injected in syngeneic C57BL/6 mice, we investigated the effects of intraperitoneal Bor administration in vivo on both tumor growth and the modulation of the tumor immune microenvironment.

RESULTS

We demonstrate that Bor inhibited MM cell growth and induced apoptosis. Further, Bor activated the Unfolded Protein Response, which however appeared to participate in lowering cells' sensitivity to the drug's cytotoxic effects. Bor also affected the expression of EGFR and ErbB2 and the activation of downstream pro-survival signaling effectors, including ERK1/2 and AKT. In vivo, Bor was able to suppress MM growth and extend mice survival. The Bor-mediated delay of tumor progression was sustained by increased activation of T lymphocytes recruited to the tumor microenvironment.

CONCLUSIONS

The results presented herein support the use of Bor in MM and advocate future studies aimed at defining the therapeutic potential of Bor and Bor-based combination regimens for this treatment-resistant, aggressive tumor.

Autophagy in the retinal neurovascular unit: New perspectives into diabetic retinopathy

Diabetic retinopathy (DR) is one of the most prevalent retinal disorders worldwide, and it is a major cause of vision impairment in individuals of productive age. Research has demonstrated the significance of autophagy in DR, which is a critical intracellular homeostasis mechanism required for the destruction and recovery of cytoplasmic components. Autophagy maintains the physiological function of senescent and impaired organelles under stress situations, thereby regulating cell fate via various signals. As the retina's functional and fundamental unit, the retinal neurovascular unit (NVU) is critical in keeping the retinal environment's stability and supporting the needs of retinal metabolism. However, autophagy is essential for the normal NVU structure and function. We discuss the strong association between DR and autophagy in this review, as well as the many kinds of autophagy and its crucial physiological activities in the retina. By evaluating the pathological changes of retinal NVU in DR and the latest advancements in the molecular mechanisms of autophagy that may be involved in the pathophysiology of DR in NVU, we seek to propose new ideas and methods for the prevention and treatment of DR.