Senescence marker protein 30 (SMP30) protects against high glucose-induced apoptosis, oxidative stress and inflammatory response in retinal ganglion cells by enhancing Nrf2 activation via regulation of Akt/GSK-3β pathway

SMP30 alleviates cerebral ischemia/reperfusion-induced neuronal injury by inhibiting HDAC4/PSD-95 to preserve mitochondrial function

Ischemic stroke is a major cause of global death and permanent disability. Major consequences of ischemic stroke include neuronal mitochondrial dysfunction. We investigated the effects of senescence marker protein 30 (SMP30) on mitochondria-mediated apoptosis and histone deacetylase 4 (HDAC4)/postsynaptic density-95 (PSD-95) signaling in stroke models in vivo and in vitro. Rats with middle cerebral artery occlusion/reperfusion (MCAO/R) were used to simulate cerebral ischemia/reperfusion (I/R) injury. SMP30 was downregulated in the brain tissues of rats after I/R induction. SMP30 overexpression decreased MCAO/R-induced infarct volumes and improved neurologic function and histopathological changes. Increasing SMP30 expression suppressed neuronal apoptosis and reduced mitochondrial dysfunction. SMP30 overexpression in SH-SY5Y and PC12 cells treated with oxygen-glucose deprivation/reoxygenation (OGD/R) decreased HDAC4 and PSD-95 expression; PSD-95 could bind to HDAC4. Furthermore, HDAC4 upregulation abolished the effects of SMP30 overexpression on OGD/R-induced apoptosis and mitochondrial dysfunction in SH-SY5Y cells. Together, these findings indicate that SMP30 alleviates cerebral I/R-induced neuronal injury by inhibiting HDAC4/PSD-95 to preserve mitochondrial function. These interactions might provide new treatment methods for patients with ischemic stroke.

Advancing osteoarthritis therapy with GMOCS hydrogel-loaded BMSCs-exos

This study investigated the mechanism of the extracellular matrix-mimicking hydrogel-mediated TGFB1/Nrf2 signaling pathway in osteoarthritis using bone marrow mesenchymal stem cell-derived exosomes (BMSCs-Exos). A GMOCS-Exos hydrogel was synthesized and evaluated for its impact on chondrocyte viability and neutrophil extracellular traps (NETs) formation. In an OA rat model, GMOCS-Exos promoted cartilage regeneration and inhibited NETs formation. Transcriptome sequencing identified TGFB1 as a key gene, with GMOCS-Exos activating Nrf2 signaling through TGFB1. Depletion of TGFB1 hindered the cartilage-protective effect of GMOCS-Exos. This study sheds light on a promising therapeutic strategy for osteoarthritis through GMOCS-Exos-mediated TGFB1/Nrf2 pathway modulation.

Mechanistic insights into the alterations and regulation of the AKT signaling pathway in diabetic retinopathy

In the early stages of diabetic retinopathy (DR), diabetes-related hyperglycemia directly inhibits the AKT signaling pathway by increasing oxidative stress or inhibiting growth factor expression, which leads to retinal cell apoptosis, nerve proliferation and fundus microvascular disease. However, due to compensatory vascular hyperplasia in the late stage of DR, the vascular endothelial growth factor (VEGF)/phosphatidylinositol 3 kinase (PI3K)/AKT cascade is activated, resulting in opposite levels of AKT regulation compared with the early stage. Studies have shown that many factors, including insulin, insulin-like growth factor-1 (IGF-1), VEGF and others, can regulate the AKT pathway. Disruption of the insulin pathway decreases AKT activation. IGF-1 downregulation decreases the activation of AKT in DR, which abrogates the neuroprotective effect, upregulates VEGF expression and thus induces neovascularization. Although inhibiting VEGF is the main treatment for neovascularization in DR, excessive inhibition may lead to apoptosis in inner retinal neurons. AKT pathway substrates, including mammalian target of rapamycin (mTOR), forkhead box O (FOXO), glycogen synthase kinase-3 (GSK-3)/nuclear factor erythroid 2-related factor 2 (Nrf2), and nuclear factor kappa-B (NF-κB), are a research focus. mTOR inhibitors can delay or prevent retinal microangiopathy, whereas low mTOR activity can decrease retinal protein synthesis. Inactivated AKT fails to inhibit FOXO and thus causes apoptosis. The GSK-3/Nrf2 cascade regulates oxidation and inflammation in DR. NF-κB is activated in diabetic retinas and is involved in inflammation and apoptosis. Many pathways or vital activities, such as the Janus kinase (JAK)/signal transducer and activator of transcription (STAT) and mitogen-activated protein kinase (MAPK) signaling pathways, interact with the AKT pathway to influence DR development. Numerous regulatory methods can simultaneously impact the AKT pathway and other pathways, and it is essential to consider both the connections and interactions between these pathways. In this review, we summarize changes in the AKT signaling pathway in DR and targeted drugs based on these potential sites.

Diabetic retinopathy: Involved cells, biomarkers, and treatments

Diabetic retinopathy (DR), a leading cause of vision loss and blindness worldwide, is caused by retinal neurovascular unit dysfunction, and its cellular pathology involves at least nine kinds of retinal cells, including photoreceptors, horizontal and bipolar cells, amacrine cells, retinal ganglion cells, glial cells (Müller cells, astrocytes, and microglia), endothelial cells, pericytes, and retinal pigment epithelial cells. Its mechanism is complicated and involves loss of cells, inflammatory factor production, neovascularization, and BRB impairment. However, the mechanism has not been completely elucidated. Drug treatment for DR has been gradually advancing recently. Research on potential drug targets relies upon clear information on pathogenesis and effective biomarkers. Therefore, we reviewed the recent literature on the cellular pathology and the diagnostic and prognostic biomarkers of DR in terms of blood, protein, and clinical and preclinical drug therapy (including synthesized molecules and natural molecules). This review may provide a theoretical basis for further DR research.