N,N-Dimethyl-3β-hydroxycholenamide attenuates neuronal death and retinal inflammation in retinal ischemia/reperfusion injury by inhibiting Ninjurin 1

IRF1 regulates autophagy and microglia polarization in retinal ischemia-reperfusion through NCOA1/Wnt/β-catenin signalling pathway

BACKGROUND

Interferon regulatory factor 1 (IRF1) is an important regulatory factor in the development of eyes, and it has been proved to be involved in the regulation of ischemia-reperfusion process. But its role in retinal ischemia-reperfusion (RIR) remains unclear.

METHODS

RIR rat model was induced by increasing intraocular pressure. Hematoxylin and eosin (HE) staining, immunofluorescence (IF) staining, and western blot experiments were used to explore the levels of IRF1, autophagy, and microglia polarization in RIR. Western blot, transmission electron microscope, IF, and ELISA assays were used to explore the effects of IRF1, Nuclear receptor coactivator 1 (NCOA1), and Wnt/β-catenin signalling pathways in OGD/R-induced autophagy and polarization of rat retinal microglia. CHIP and dual-luciferase experiments verify the interaction between IRF1 and NCOA1. CHIP and dual-luciferase experiments were used to verify the interaction between IRF1 and NCOA1. Adeno-associated viruses interfering with IRF1 and NCOA1 were injected into the vitreous of rats to explore the functions of IRF1 and NCOA1 in RIR rats.

RESULTS

IRF1 and M1-type markers of microglia in retina of RIR rats increased, and autophagy level decreased. Knockdown of IRF1 and NCOA1 increased autophagy of OGD/R-induced retinal microglia, inhibited M1-type polarization and inflammatory cytokines, alleviated RIR injury in rats, and inhibited the activation of Wnt/β-catenin signalling pathway. The Wnt/β-catenin signalling pathway activator HLY78 partially reversed the effect of knocking down NCOA1 on retinal microglia. Mechanically, knockdown of IRF1 inhibited the activation of Wnt/β-catenin signalling pathway by inhibiting the transcription of NCOA1.

CONCLUSION

Inhibition of IRF1 has a protective effect on RIR damage by regulating NCOA1/Wnt/β-catenin signalling pathway.

Unraveling the mechanisms of NINJ1-mediated plasma membrane rupture in lytic cell death and related diseases

Plasma membrane rupture (PMR), the ultimate event during lytic cell death, releases damage-associated molecular patterns (DAMPs) that trigger inflammation and immune responses in the development of various diseases. Recent years have witnessed significant advances in understanding the PMR mediated by ninjurin1 (NINJ1) in different lytic cell death processes. NINJ1 oligomerizes and ruptures the membrane in pyroptosis and other lytic cell death, participating in the pathogenesis of multiple diseases. Although the membrane-permeabilizing function of NINJ1 is well recognized, the role of NINJ1 in different types of lytic cell death and its impact on multiple disease processes have yet to be fully elucidated. This review summarizes the latest advances in the mechanisms of NINJ1-mediated PMR, discusses the membrane-inducing activity of NINJ1 in different lytic cell death, explains the implications of NINJ1 in lytic cell death-related diseases, and lists the inhibitory strategies for NINJ1. We expect to provide new insights into targeting NINJ1 to suppress lytic cell death for therapeutic benefit, which may become a new strategy to control inflammatory cell lysis-related diseases.

Preclinical Retinal Disease Models: Applications in Drug Development and Translational Research

Retinal models play a pivotal role in translational drug development, bridging preclinical research and therapeutic applications for both ocular and systemic diseases. This review highlights the retina as an ideal organ for studying advanced therapies, thanks to its immune privilege, vascular and neuronal networks, accessibility, and advanced imaging capabilities. Preclinical retinal disease models offer unparalleled insights into inflammation, angiogenesis, fibrosis, and hypoxia, utilizing clinically translatable bioimaging tools like fundoscopy, optical coherence tomography, confocal scanning laser ophthalmoscopy, fluorescein angiography, optokinetic tracking, and electroretinography. These models have driven innovations in anti-inflammatory, anti-angiogenic, and neuroprotective strategies, with broader implications for systemic diseases such as rheumatoid arthritis, Alzheimer's, and fibrosis-related conditions. By emphasizing the integration of the 3Rs principles and novel imaging modalities, this review highlights how retinal research not only enhances therapeutic precision but also minimizes ethical concerns, paving the way for more predictive and human-relevant approaches in drug development.

Tetrahedral Framework Nucleic Acid-Based Delivery of DJ-1-saRNA Prevent Retinal Ischaemia-Reperfusion Injury via Inhibiting Ferroptosis

Retinal ischaemia/reperfusion injury (RI/RI) is the primary pathophysiological mechanism underlying retinal ischaemic diseases, potentially resulting in significant and irreversible visual impairment. Currently, there are no effective treatments available for RI/RI, and oxidative stress is a critical factor that contributes to the associated damage. DJ-1, an important endogenous antioxidant, has been proposed as a promising therapeutic agent for RI/RI owing to its potential for overexpression. In this study, tetrahedral frame nucleic acids (tFNAs) were utilised as an effective delivery vehicle for DJ-1 small activating RNA (saRNA), resulting in the synthesis of a novel nanocomposite (tFNAs-DJ-1-saRNA). In vitro experiments demonstrated that tFNAs effectively delivered DJ-1-saRNA to R28 cells, thus exerting a repair effect on oxidative stress injury. In vivo investigations revealed that the intravitreal injection of tFNAs-DJ-1-saRNA facilitated retinal DJ-1 gene expression and mitigated retinal atrophy induced by RI/RI. Mechanistically, tFNAs-DJ-1-saRNA activated the xCT/GPX4 pathway, thereby inhibiting ferroptosis, reducing ganglion cell damage and protecting the retinal tissue. In conclusion, this study demonstrated that the tFNAs-DJ-1-saRNA complex can ameliorate RI/RI by inhibiting ferroptosis, suggesting its potential as a novel agent for the treatment of retinal ischaemic diseases.

Multifaceted roles of ninjurin1 in immunity, cell death, and disease

Ninjurin1 (NINJ1) is initially identified as a nerve injury-induced adhesion molecule that facilitates axon growth. It is initially characterized to promote nerve regeneration and mediate the transendothelial transport of monocytes/macrophages associated with neuroinflammation. Recent evidence indicates that NINJ1 mediates plasma membrane rupture (PMR) in lytic cell death. The absence or inhibition of NINJ1 can delay PMR, thereby mitigating the spread of inflammation resulting from cell lysis and preventing the progression of various cell death-related pathologies, suggesting a conserved regulatory mechanism across these processes. Further research elucidated the structural basis and mechanism of NINJ1-mediated PMR. Although the role of NINJ1 in PMR is established, the identity of its activating factors and its implications in diseases remain to be fully explored. This review synthesizes current knowledge regarding the structural basis and mechanism of NINJ1-mediated PMR and discusses its significance and therapeutic targeting potential in inflammatory diseases, neurological disorders, cancer, and vascular injuries.

HMGB2 knockdown ameliorates retinal ganglion cell injury by inhibiting NLRP3 inflammasome activation after retinal ischemia

AIM

To explore the neuroprotective effects of high mobility group box 2 (HMGB2) knockdown on retinal ganglion cells (RGCs) in the retinal ischemia-reperfusion injury (RIRI).

METHODS

Oxygen-glucose deprivation (OGD)-injured RGCs from postnatal three-day C57BL/6 mice pups and high intraocular pressure (IOP)-induced RIRI mice were used as cellular and animal models of RIRI. The expression of HMGB2 in the retina of RIRI mice and OGD-injured RGCs was detected through reverse transcription-polymerase chain reaction (RT-qPCR) and Western blotting. The effects of HMGB2 silencing on the morphological changes, RGCs survival, and cell apoptosis in mouse retinal tissues were observed through H&E staining, immunofluorescence staining with RNA-binding protein with multiple splicing (RBPMS) antibody, and TUNEL staining, respectively. RGC viability and apoptosis were examined by CCK-8 and flow cytometry assays. The levels of proteins associated with NOD-like receptor thermal protein domain associated protein 3 (NLRP3)-mediated pyroptosis [NLRP3, Caspase-1, GSDMD-N, interleukin (IL)-1β, IL-18] in vivo and in vitro were measured by Western blotting.

RESULTS

HMGB2 protein and NLRP3 were upregulated in the retina of RIRI mice and OGD-injured RGCs (P<0.001). The retina was edematous, accompanied by disorganized cell arrangement and decreased thickness of all layers, and obvious vacuoles in ganglion cell layer. HMGB2 silencing alleviated the reduction in total retinal thickness and the severity of retinal tissue damage as well as suppressed RGC loss and retinal cell apoptosis in RIRI mice. OGD-induced RGC apoptosis was ameliorated after downregulation of HMGB2 in vitro. Intravitreal injection of the AAV-sh-HMGB2 and si-HMGB2 resulted in significantly decrease of NLRP3, Caspase-1, GSDMD-N, IL-1β, and IL-18 protein levels in the retinal tissues of RIRI mice and OGD-injured RGCs, respectively (all P<0.001).

CONCLUSION

HMGB2 knockdown protects against RGC apoptosis and pyroptosis after RIRI through suppressing NLRP3 inflammasome activation.

Astragalus polysaccharide attenuates retinal ischemia reperfusion-induced microglial activation through sortilin-related vacuolar protein sorting 10 domain containing receptor 2/laminin subunit alpha 1 upregulation

Objective

Microglial activation is a hallmark of pathogenic retinal conditions such as retinal ischemia-reperfusion (RIR). While sortilin-related vacuolar protein sorting 10 domain containing receptor 2 (Sorcs2) and laminin subunit alpha 1 (Lama1) have been implicated in neuroinflammatory processes, their roles in regulating microglial activation in RIR are not reported. The current work studied the potential of Sorcs2 and Lama1 as negative regulators of microglial activation in RIR and assessed the therapeutic potential of Astragalus polysaccharide (AP).

Material and Methods

Transcriptome profiling was conducted in retinal specimens of RIR group 72 h after RIR induction. Oxygen-glucose deprivation/reperfusion (OGD/R) in rat microglial cells was employed as the cellular induction model of RIR. The functional role of Sorcs2 and Lama1 in dictating microglial activation was investigated in vitro and in vivo using lentivirus-based gene expression. Further, the potential effect of AP on RIR-mediated microglial activation was investigated.

Results

Sorcs2 and Lama1 were identified as two downregulated genes in retinal samples following RIR. OGD/R induction triggered pro-inflammatory microglial activation and induced the downregulation of Sorcs2 and Lama1. Sorcs2 or Lama1 overexpression hindered OGD/R-induced microglial activation in vitro and attenuated inflammatory expansion of microglia cells in RIR-induced rat retinal samples. AP treatment was able to neutralize the oxidative stress, promote the expression of Sorcs2 and Lama1, and suppress microglial activation.

Conclusion

Our findings pinpoint Sorcs2 and Lama1 as negative regulators of microglial activation in RIR. AP could be employed as an antioxidant to attenuate microglial activation and ameliorate the inflammatory damages in RIR.

Neuroprotective effect of ciclopirox olamine in retinal ischemia/reperfusion injury

Retinal ischemia-reperfusion (IR) injury is a basic pathological procedure in clinic and associated with various ischemic retinal diseases, including glaucoma, diabetic retinopathy, retinal vascular occlusion, etc. The purpose of this work is to investigate the effect of ciclopirox olamine (CPX) on retinal IR injury and further explore the underlying mechanism. In vitro assay exhibited that CPX exhibited significant neuroprotection against oxygen glucose deprivation (OGD) and oxidative stress-induced injuries in 661W photoreceptor cells. OGD injury showed a proinflammatory phenotype characterized by significantly increased production of cytokines (IL-6, IL-23 and TNF-α), while CPX significantly inhibited their secretion. In addition, the in vivo experiment demonstrated that CPX significantly preserved the normal thickness of the retina. Therefore, we suggest that CPX is identified in our research as a prospective therapeutic agent for retinal IR injury.

Roflumilast Attenuates Microglial Senescence and Retinal Inflammatory Neurodegeneration Post Retinal Ischemia Reperfusion Injury Through Inhibiting NLRP3 Inflammasome

Purpose

Retinal ischemia-reperfusion (RIR) injury is implicated in various retinal diseases, leading to retinal ganglion cells (RGCs) degeneration. Microglial senescence exacerbates inflammation, contributing to neurodegeneration. This study aimed to investigate the potential therapeutic role of Roflumilast (Roflu) in ameliorating microglial senescence and neuroinflammation following RIR injury.

Methods

C57BL/6J mice underwent RIR surgery, and Roflu treatment was administered intraperitoneally. BV2 microglial cells were subjected to oxygen-glucose deprivation and reoxygenation (OGD/R) to simulate ischemic conditions in vitro. SA-β-gal staining was used to detect cellular senescence. Quantitative PCR and ELISA were used to examine the levels of senescence-associated secretory phenotype (SASP) factors. Hematoxylin and eosin (H&E) staining was performed on retinal sections to assess retinal morphology and thickness. Surviving RGCs were labeled and quantified in retinal whole-mounts using immunofluorescence (IF). Furthermore, Western blot and IF staining were used to quantify the proteins associated with the cell cycle and NLRP3 inflammasomes.

Results

Roflu treatment reduced microglial senescence, ROS production, and secretion of pro-inflammatory cytokines in OGD/R-exposed BV2 cells. It also restored cell proliferation capacity and reversed OGD/R-induced cell cycle arrest. In vivo, Roflu alleviated retinal senescence, preserved retinal thickness, and protected against RGCs death in the RIR mouse model. Mechanistically, Roflu inhibited the NLRP3 inflammasome activation and suppressed DNA damage signaling pathway in microglia.

Conclusions

Roflu exerts neuroprotective effects by mitigating microglial senescence and inflammation via inhibition of the NLRP3 inflammasome in RIR injury. These findings suggest that Roflu may serve as a promising therapeutic strategy for retinal diseases associated with ischemic injury by targeting microglial senescence.

Targeting inflammasomes and pyroptosis in retinal diseases-molecular mechanisms and future perspectives

Retinal diseases encompass various conditions associated with sight-threatening immune responses and are leading causes of blindness worldwide. These diseases include age-related macular degeneration, diabetic retinopathy, glaucoma and uveitis. Emerging evidence underscores the vital role of the innate immune response in retinal diseases, beyond the previously emphasized T-cell-driven processes of the adaptive immune system. In particular, pyroptosis, a newly discovered programmed cell death process involving inflammasome formation, has been implicated in the loss of membrane integrity and the release of inflammatory cytokines. Several disease-relevant animal models have provided evidence that the formation of inflammasomes and the induction of pyroptosis in innate immune cells contribute to inflammation in various retinal diseases. In this review article, we summarize current knowledge about the innate immune system and pyroptosis in retinal diseases. We also provide insights into translational targeting approaches, including novel drugs countering pyroptosis, to improve the diagnosis and treatment of retinal diseases.

Immunological Landscape of Retinal Ischemia-Reperfusion Injury: Insights into Resident and Peripheral Immune Cell Responses

Retinal ischemia-reperfusion injury (RIRI) is a complex condition characterized by immune cell-mediated inflammation and consequent neuronal damage. This review delves into the immune response mechanisms in RIRI, particularly emphasizing the roles played by resident and peripheral immune cells. It highlights the pivotal role of microglia, the primary resident immune cells, in exacerbating neuroinflammation and neuronal damage through their activation and subsequent release of pro-inflammatory mediators. Additionally, the review explores the contributions of other glial cell types, such as astrocytes and Müller cells, in modulating the immune response within the retinal environment. The dual role of the complement system in RIRI is also examined, revealing its complex functions in both safeguarding and impairing retinal health. Inflammasomes, triggered by various danger signals, are discussed as crucial contributors to the inflammatory pathways in RIRI, with an emphasis on the involvement of different NOD-like receptor family proteins. The review further analyzes the infiltration and impact of peripheral immune cells like neutrophils, macrophages, and T cells, which migrate to the retina following ischemic injury. Critical to this discussion is the interplay between resident and peripheral immune cells and its implications for RIRI pathophysiology. Finally, the review outlines future research directions, focusing on basic research and the potential for clinical translation to enhance understanding and treatment of RIRI.

Single-cell sequencing of the retina shows that LDHA regulates pathogenesis of autoimmune uveitis

Autoimmune uveitis (AU) is a severe disorder causing poor vision and blindness. However, the cellular dynamics and pathogenic mechanisms underlying retinal injury in uveitis remain unclear. In this study, single-cell RNA sequencing of the retina and cervical draining lymph nodes in experimental autoimmune uveitis mice was conducted to identify the cellular spatiotemporal dynamics and upregulation of the glycolysis-related gene LDHA. Suppression of LDHA can rescue the imbalance of T effector (Teff) cells/T regulator (Treg) cells under inflammation via downregulation of the glycolysis-PI3K signaling circuit and inhibition of the migration of CXCR4+ Teff cells towards retinal tissue. Furthermore, LDHA and CXCR4 are upregulated in the peripheral blood mononuclear cells of Vogt-Koyanagi-Harada patients. The LDHA inhibitor suppresses CD4+ T cell proliferation in humans. Therefore, our data indicate that the autoimmune environment of uveitis regulates Teff cell accumulation in the retina via glycolysis-associated LDHA. Modulation of this target may provide a novel therapeutic strategy for treating AU.