Role of Adrenomedullin 2/Intermedin in the Pathogenesis of Neovascular Age-Related Macular Degeneration

An innovative rheology analysis method applies to the formulation optimization of Panax notoginseng total saponins ocular gel

Emphasizing the viscoelasticity of ophthalmic gels is crucial for understanding the residence time, structure, and stability of hydrogels. This study primarily aimed to propose an innovative rheology analysis method for ophthalmic gels, considering complex eye movements. This method was applied to select ophthalmic gels with favorable rheological characteristics. Additionally, the physical characteristics and in vitro release of the selected Panax notoginseng total saponins (PNS) gel were demonstrated. The selected PNS gel significantly increased the activities of SOD and decreased intracellular levels of MDA, TNF-α, and IL-1β in H2O2-treated ARPE-19 cells. Finally, the optimal formulation was selected as a suitable platform for ophthalmic delivery and was shown to significantly rescue ARPE-19 cells from oxidative cellular damage.

The impact of NF-κB on inflammatory and angiogenic processes in age-related macular degeneration

Age-related macular degeneration (AMD) is a prominent cause of vision loss, characterized by two different types, dry (atrophic) and wet (neovascular). Dry AMD is distinguished by the progressive deterioration of retinal cells, which ultimately causes a decline in vision. In contrast, wet AMD is defined by the abnormal development of blood vessels underneath the retina, leading to a sudden and severe vision impairment. The course of AMD is primarily driven by chronic inflammation and pathological angiogenesis, in which the NF-κB signaling pathway plays a crucial role. The activation of NF-κB results in the generation of pro-inflammatory cytokines, chemokines, and angiogenic factors like VEGF, which contribute to inflammation and the formation of new blood vessels in AMD. This review analyzes the intricate relationship between NF-κB signaling, inflammation, and angiogenesis in AMD and assesses the possibility of using NF-κB as a target for therapy. The evaluation involves a comprehensive examination of preclinical and clinical evidence that substantiates the effectiveness of NF-κB inhibitors in treating AMD by diminishing inflammation and pathological angiogenesis.

Intermedin Alleviates Diabetic Cardiomyopathy by Up-Regulating CPT-1β through Activation of the Phosphatidyl Inositol 3 Kinase/Protein Kinase B Signaling Pathway

Diabetic cardiomyopathy (DCM), one of the most serious long-term consequences of diabetes, is closely associated with myocardial fatty acid metabolism. Carnitine palmitoyltransferase-1β (CPT-1β) is the rate-limiting enzyme responsible for β-oxidation of long-chain fatty acids. Intermedin (IMD) is a pivotal bioactive small molecule peptide, participating in the protection of various cardiovascular diseases. However, the role and underlying mechanisms of IMD in DCM are still unclear. In this study, we investigated whether IMD alleviates DCM via regulating CPT-1β. A rat DCM model was established by having rats to drink fructose water for 12 weeks. A mouse DCM model was induced by feeding mice a high-fat diet for 16 weeks. We showed that IMD and its receptor complexes levels were significantly down-regulated in the cardiac tissues of DCM rats and mice. Reduced expression of IMD was also observed in neonatal rat cardiomyocytes treated with palmitic acid (PA, 300 μM) in vitro. Exogenous and endogenous IMD mitigated cardiac hypertrophy, fibrosis, dysfunction, and lipid accumulation in DCM rats and IMD-transgenic DCM mice, whereas knockout of IMD worsened these pathological processes in IMD-knockout DCM mice. In vitro, IMD alleviated PA-induced cardiomyocyte hypertrophy and cardiac fibroblast activation. We found that CPT-1β enzyme activity, mRNA and protein levels, and acetyl-CoA content were increased in T2DM patients, rats and mice. IMD up-regulated the CPT-1β levels and acetyl-CoA content in T2DM rats and mice. Knockdown of CPT-1β blocked the effects of IMD on increasing acetyl-CoA content and on inhibiting cardiomyocyte hypertrophy and cardiac fibroblast activation. IMD receptor antagonist IMD17-47 and the phosphatidyl inositol 3 kinase (PI3K)/protein kinase B (Akt) inhibitor LY294002 reversed the effects of IMD on up-regulating CPT-1β and acetyl-CoA expression and on inhibiting cardiomyocyte hypertrophy and cardiac fibroblast activation. We revealed that IMD alleviates DCM by up-regulating CPT-1β via calcitonin receptor-like receptor/receptor activity-modifying protein (CRLR/RAMP) receptor complexes and PI3K/Akt signaling. IMD may serve as a potent therapeutic target for the treatment of DCM.

The role of lipid peroxidation in epithelial-mesenchymal transition of retinal pigment epithelial cells

Epithelial-Mesenchymal Transition (EMT) of retinal pigment epithelial (RPE) cells is recognized as pivotal in various retinal diseases. Previous studies have suggested a reciprocal regulation between reactive oxygen species (ROS) and EMT, though the involvement of peroxidized lipids or the effects of reducing them has remained unclear. The present study disclosed that EMT of ARPE-19 cells induced by TGF-β2 and TNF-α involves increased lipid peroxidation, and Ferrostatin-1 (Fer-1), a lipophilic antioxidative agent, successfully inhibited the increase in lipid peroxidation. Fer-1 suppressed the formation of EMT-associated fibrotic deposits, while EMT induction or Fer-1 treatment did not influence the cell viability or proliferation. Functionally, Fer-1 impeded EMT-driven cell migration and reduction in transepithelial electrical resistance. It demonstrated regulatory prowess by downregulating the mesenchymal marker fibronectin, upregulating the epithelial marker ZO-1, and inhibiting the EMT-associated transcriptional factor ZEB1. Additionally, VEGF, a major pathogenic cytokine in various retinal diseases, is also upregulated during EMT, and Fer-1 significantly mitigated the effect. The present study disclosed the involvement of lipid peroxidation in EMT of RPE cells, and suggests the suppression of lipid peroxidation may be a potential therapeutic target in retinal diseases in which EMT is implicated.

PI3Kδ Mediates Fibrosis by Patient-Derived Vitreous

The epithelial-mesenchymal transition (EMT) is a fundamental process in developing fibrotic diseases, including forming epiretinal membranes (ERMs). ERMs can result in irreversible vision loss. Previous research has demonstrated that vitreous (VIT) derived from patients with proliferative diabetic retinopathy can stimulate angiogenesis through the Axl/PI3K/Akt pathway. Building upon this knowledge, we aimed to explore the influence of VIT from patients with macular membranes in ARPE-19 cells. Our findings reveal that patient-derived VIT from individuals with macular membranes promotes EMT and phosphoinositide 3-kinase-delta (PI3Kδ) expression in ARPE-19 cells. To elucidate the function of PI3Kδ in the ERM, we conducted experiments involving the knockout of p110δ, a key subunit of PI3Kδ, and observed that its absence hinders EMT induced by patient-derived VIT. Moreover, p110δ depletion reduces cell proliferation and migration in ARPE-19 cells. Remarkably, these effects were further corroborated by applying the p110δ inhibitor idelalisib, which blocks fibrosis in the laser-induced fibrosis model. Collectively, our results propose that p110δ plays a critical role in the progression of ERMs. Consequently, targeting p110δ emerges as a promising therapeutic approach for mitigating fibrosis. These findings contribute to a better understanding of the underlying mechanisms involved in ERM formation and highlight the potential for p110δ-directed antifibrotic therapy in retinal diseases.