mTOR regulates neuroprotective effect of immunized CD4+Foxp3+ T cells in optic nerve ischemia

Integrated bioinformatics analysis of retinal ischemia/reperfusion injury in rats with potential key genes

The tissue damage caused by transient ischemic injury is an essential component of the pathogenesis of retinal ischemia, which mainly hinges on the degree and duration of interruption of the blood supply and the subsequent damage caused by tissue reperfusion. Some research indicated that the retinal injury induced by ischemia-reperfusion (I/R) was related to reperfusion time.In this study, we screened the differentially expressed circRNAs, lncRNAs, and mRNAs between the control and model group and at different reperfusion time (24h, 72h, and 7d) with the aid of whole transcriptome sequencing technology, and the trend changes in time-varying mRNA, lncRNA, circRNA were obtained by chronological analysis. Then, candidate circRNAs, lncRNAs, and mRNAs were obtained as the intersection of differentially expression genes and trend change genes. Importance scores of the genes selected the key genes whose expression changed with the increase of reperfusion time. Also, the characteristic differentially expressed genes specific to the reperfusion time were analyzed, key genes specific to reperfusion time were selected to show the change in biological process with the increase of reperfusion time.As a result, 316 candidate mRNAs, 137 candidate lncRNAs, and 31 candidate circRNAs were obtained by the intersection of differentially expressed mRNAs, lncRNAs, and circRNAs with trend mRNAs, trend lncRNAs and trend circRNAs, 5 key genes (Cd74, RT1-Da, RT1-CE5, RT1-Bb, RT1-DOa) were selected by importance scores of the genes. The result of GSEA showed that key genes were found to play vital roles in antigen processing and presentation, regulation of the actin cytoskeleton, and the ribosome. A network included 4 key genes (Cd74, RT1-Da, RT1-Bb, RT1-DOa), 34 miRNAs and 48 lncRNAs, and 81 regulatory relationship axes, and a network included 4 key genes (Cd74, RT1-Da, RT1-Bb, RT1-DOa), 9 miRNAs and 3 circRNAs (circRNA_10572, circRNA_03219, circRNA_11359) and 12 regulatory relationship axes were constructed, the subcellular location, transcription factors, signaling network, targeted drugs and relationship to eye diseases of key genes were predicted. 1370 characteristic differentially expressed mRNAs (spec_24h mRNA), 558 characteristic differentially expressed mRNAs (spec_72h mRNA), and 92 characteristic differentially expressed mRNAs (spec_7d mRNA) were found, and their key genes and regulation networks were analyzed.In summary, we screened the differentially expressed circRNAs, lncRNAs, and mRNAs between the control and model groups and at different reperfusion time (24h, 72h, and 7d). 5 key genes, Cd74, RT1-Da, RT1-CE5, RT1-Bb, RT1-DOa, were selected. Key genes specific to reperfusion time were selected to show the change in biological process with the increased reperfusion time. These results provided theoretical support and a reference basis for the clinical treatment.

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.

Autophagy in glaucoma pathogenesis: Therapeutic potential and future perspectives

Glaucoma is a common blinding eye disease characterized by progressive loss of retinal ganglion cells (RGCs) and their axons, progressive loss of visual field, and optic nerve atrophy. Autophagy plays a pivotal role in the pathophysiology of glaucoma and is closely related to its pathogenesis. Targeting autophagy and blocking the apoptosis of RGCs provides emerging guidance for the treatment of glaucoma. Here, we provide a systematic review of the mechanisms and targets of interventions related to autophagy in glaucoma and discuss the outlook of emerging ideas, techniques, and multidisciplinary combinations to provide a new basis for further research and the prevention of glaucomatous visual impairment.

Computational research of mTORC1 inhibitor on cerebral ischemia-reperfusion injury

Ischemic stroke contributes to more than 80% of all strokes and has the four characteristics of high prevalence, high disability, high mortality, and high recurrence. Stroke is a preventable and controllable disease. In addition to controlling the primary disease, effective prevention and control measures need to be given to the occurrence and development of stroke. With the development and progress of modern treatment methods for ischemic stroke, the mortality and disability rate have decreased significantly. At present, the main treatment methods for ischemic stroke include thrombolysis, thrombus removal at the ultra-early stage, and treatment of improving collateral circulation in the acute phase. However, the ultra-early and early blood reperfusion involves reperfusion injury, which will cause secondary nerve damage, which is called cerebral ischemia/reperfusion injury (CIRI). Studies have found that autophagy is involved in the entire process of CIRI and can reduce the damage of CIRI. The mammalian target of Rapamycin (mTORC1) is the primary signal pathway regulating autophagy. And the mTORC1 inhibitor, Rapamycin, has been proved to exert neuroprotective effects in the ultra-early and early cerebral ischemia-reperfusion. Therefore, screening and designing mTORC1 inhibitors is very important to control reperfusion injury and reduce neuronal death and apoptosis. In this research, plenty of computer-assisted was applied to virtually screen and select potential mTORC1's inhibitors. We used Libdock to screen the structure and performed toxicity predictions, ADME (absorption, distribution, metabolism, excretion) to predict small molecules' pharmacological and toxicological properties. To assess the binding mechanism and affinity between the mTORC1 dimer and the ligand, molecular docking was performed. Then, the pharmacophore of small molecules in the docking conformation with the protein was supplemented by Schrodinger. Additionally, molecular dynamics simulations were conducted to assess if the ligand-receptor complex was stable in a natural environment. Furthermore, an experiment was performed to verify the inhibitory effect of compound 1 and compound 2 on mTOR protein. All in all, the study provides a hand of candidate drugs as well as pharmacological properties, which can play an essential role in mTORC1 inhibitors.

The Role of Autophagy in Chemical Proteasome Inhibition Model of Retinal Degeneration

We recently demonstrated that chemical proteasome inhibition induced inner retinal degeneration, supporting the pivotal roles of the ubiquitin–proteasome system in retinal structural integrity maintenance. In this study, using beclin1-heterozygous (Becn1-Het) mice with autophagic dysfunction, we tested our hypothesis that autophagy could be a compensatory retinal protective mechanism for proteasomal impairment. Despite the reduced number of autophagosome, the ocular tissue morphology and intraocular pressure were normal. Surprisingly, Becn1-Het mice experienced the same extent of retinal degeneration as was observed in wild-type mice, following an intravitreal injection of a chemical proteasome inhibitor. Similarly, these mice equally responded to other chemical insults, including endoplasmic reticulum stress inducer, N-methyl-D-aspartate, and lipopolysaccharide. Interestingly, in cultured neuroblastoma cells, we found that the mammalian target of rapamycin-independent autophagy activators, lithium chloride and rilmenidine, rescued these cells against proteasome inhibition-induced death. These results suggest that Becn1-mediated autophagy is not an effective intrinsic protective mechanism for retinal damage induced by insults, including impaired proteasomal activity; furthermore, autophagic activation beyond normal levels is required to alleviate the cytotoxic effect of proteasomal inhibition. Further studies are underway to delineate the precise roles of different forms of autophagy, and investigate the effects of their activation in rescuing retinal neurons under various pathological conditions.

Matrine treatment reduces retinal ganglion cell apoptosis in experimental optic neuritis

Inflammatory demyelination and axonal injury of the optic nerve are hallmarks of optic neuritis (ON), which often occurs in multiple sclerosis and is a major cause of visual disturbance in young adults. Although a high dose of corticosteroids can promote visual recovery, it cannot prevent permanent neuronal damage. Novel and effective therapies are thus required. Given the recently defined capacity of matrine (MAT), a quinolizidine alkaloid derived from the herb Radix Sophorae flavescens, in immunomodulation and neuroprotection, we tested in this study the effect of matrine on rats with experimental autoimmune encephalomyelitis, an animal model of multiple sclerosis. MAT administration, started at disease onset, significantly suppressed optic nerve infiltration and demyelination, with reduced numbers of Iba1⁺ macrophages/microglia and CD4⁺ T cells, compared to those from vehicle-treated rats. Increased expression of neurofilaments, an axon marker, reduced numbers of apoptosis in retinal ganglion cells (RGCs). Moreover, MAT treatment promoted Akt phosphorylation and shifted the Bcl-2/Bax ratio back towards an antiapoptotic one, which could be a mechanism for its therapeutic effect in the ON model. Taken as a whole, our results demonstrate that MAT attenuated inflammation, demyelination and axonal loss in the optic nerve, and protected RGCs from inflammation-induced cell death. MAT may therefore have potential as a novel treatment for this disease that may result in blindness.

Complement Has Brains-Do Intracellular Complement and Immunometabolism Cooperate in Tissue Homeostasis and Behavior?

The classical liver-derived and serum-effective complement system is well appreciated as a key mediator of host protection via instruction of innate and adaptive immunity. However, recent studies have discovered an intracellularly active complement system, the complosome, which has emerged as a central regulator of the core metabolic pathways fueling human immune cell activity. Induction of expression of components of the complosome, particularly complement component C3, during transmigration from the circulation into peripheral tissues is a defining characteristic of monocytes and T cells in tissues. Intracellular complement activity is required to induce metabolic reprogramming of immune cells, including increased glycolytic flux and OXPHOS, which drive the production of the pro-inflammatory cytokine IFN-γ. Consequently, reduced complosome activity translates into defects in normal monocyte activation, faulty Th1 and cytotoxic T lymphocyte responses and loss of protective tissue immunity. Intriguingly, neurological research has identified an unexpected connection between the physiological presence of innate and adaptive immune cells and certain cytokines, including IFN-γ, in and around the brain and normal brain function. In this opinion piece, we will first review the current state of research regarding complement driven metabolic reprogramming in the context of immune cell tissue entry and residency. We will then discuss how published work on the role of IFN-γ and T cells in the brain support a hypothesis that an evolutionarily conserved cooperation between the complosome, cell metabolism and IFN-γ regulates organismal behavior, as well as immunity.

CCL26 regulates the proportion of CD4+CD25+FOXP3+ Tregs and the production of inflammatory factors in peripheral blood mononuclear cells following acute ischemic stroke via the STAT5 pathway

Acute ischemic stroke (AIS) is the most common type of stroke. Recent studies have found that AIS is closely involved in the immune regulation function of regulatory T cells (Tregs). C-C motif chemokine ligand 26 (CCL26) is a member of the chemokine family that plays an essential role in cell activation, cell differentiation, lymphocyte homing, and inflammatory and immune responses. The present study aimed to investigate the role of CCL26 in the regulation of Tregs in AIS. Peripheral blood mononuclear cells (PBMCs) were incubated with a CCL26-neutralizing antibody. The proportion of cluster of differentiation (CD)4⁺CD25⁺ forkhead box P3 (FOXP3)⁺ Tregs was increased, and the expression of FOXP3, phosphorylated signal transducer and activator of transcription 5 (p-STAT5), and that of the immunosuppressive factors, interleukin (IL)-10 and transforming growth factor (TGF)-β1, was upregulated. Conversely, the expression of immune-promoting factors, such as tumor necrosis factor (TNF)-α and IL-6 was significantly downregulated. Further experiments using CCL26 recombinant protein-treated PBMCs revealed a decreased proportion of CD4⁺CD25⁺FOXP3⁺ Tregs and the downregulated expression of FOXP3, p-STAT5, TGF-β1 and IL-10. Moreover, the expression of immunostimulatory factors, such as CX3C chemokine receptor 1, TNF-α and IL-6 was significantly upregulated. On the whole, these results demonstrate that CCL26 regulates the proportion of CD4⁺CD25⁺FOXP3⁺ Tregs and the production of inflammatory factors in PBMCs following AIS via the STAT5 pathway.

Protective effects of autophagy inhibitor 3-methyladenine on ischemia-reperfusion-induced retinal injury

OBJECTIVE

To investigate the protective effects of autophagy inhibitor 3-methyladenine (3-MA) in a rat model of ischemic-reperfusion injury (IRI).

METHODS

Forty Sprague-Dawley male rats (weight 220-250 g) were randomly divided into four groups: a control group (NC, n = 10), a Sham surgery group (n = 10), an IRI group (n = 10), and a 3-MA-treated IRI group [10 μL 3-MA (10 mmol/L) was injected in vitreous after the injury, n = 10]. The retinal IRI was induced by elevating the intraocular pressure to 110 mmHg for 60 min. Hematoxylin and eosin (HE) staining was used to calculate the number of retinal ganglion cells (RGCs). The level of microtubule-associated protein 1A/1B light chain 3 (LC3), Beclin-1, and Caspase-3 in the retina was detected using the immunofluorescence staining method. The LC3, Beclin-1, B-cell lymphoma/leukemia-2 (Bcl-2), and Caspase-3 protein levels were examined by Western blotting.

RESULTS

The number of RGCs in IRI group was significantly lower than that in NC group (P < 0.05), demonstrated by HE staining. Western blotting results indicated that the protein expression of LC3 and Beclin-1 in the IRI group was significantly elevated compared with those in the NC group (P < 0.05). However, with 3-MA treatment, the number of RCGs in 3-MA-treated IRI group was elevated and protein levels of LC3, Beclin-1 were down-regulated, compared with those in the IRI group (P < 0.05). Further immunohistochemistry staining and Western blot showed that 3-MA-treated IRI group presented down-regulated Caspase-3 and up-regulated Bcl-2 protein expression with comparison of IRI group (P < 0.05).

CONCLUSIONS

Retina IRI-caused RGCs loss involved activated autophagy pathway and apoptosis, which could be prevented by autophagy inhibitor 3-MA. Autophagy inhibitor 3-MA may act as a potent therapeutic tool in attenuating retina IRI.

The Role of Autophagy in Glaucomatous Optic Neuropathy

Autophagy is a conserved lysosomal-dependent pathway responsible for the degradation of cytoplasmic macromolecules. Based on the mechanism of cargo delivery to lysosomes, mammalian cells can undergo micro, macro, and chaperone-mediated autophagy. Other than physiological turnover of proteins and organelles, autophagy regulates cellular adaptation to different metabolic states and stressful conditions by allowing cellular survival or, when overactivated, participating to cell death. Due to their structure and function, neurons are highly dependent on autophagy efficiency and dysfunction of the pathway has been associated with neurodegenerative disorders. Glaucomatous optic neuropathies, a leading cause of blindness, are characterized by the progressive loss of a selective population of retinal neurons, i.e., the retinal ganglion cells (RGCs). Here we review the current literature on the role of autophagy in the pathogenic process that leads to the degeneration of RGC in various experimental models of glaucoma exploring the modulation of the pathway as a potential therapeutic intervention.

Selenium nanoparticles for targeted stroke therapy through modulation of inflammatory and metabolic signaling

Ischemic cerebral stroke is a major cause of death and morbidity. Currently, no neuroprotective agents have been shown to impact the clinical outcomes in cerebral stroke cases. Here, we report therapeutic effects of Se nanoparticles on ischemic stroke in a murine model. Anti-transferrin receptor monoclonal antibody (OX26)-PEGylated Se nanoparticles (OX26-PEG-Se NPs) were designed and synthesized and their neuroprotective effects were measured using in vitro and in vivo approaches. We demonstrate that administration of the biodegradable nanoparticles leads to resolution of brain edema, protection of axons in hippocampus region, and myelination of hippocampal area after cerebral ischemic stroke. Our nanoparticle design ensures efficient targeting and minimal side effects. Hematological and biochemical analyses revealed no undesired NP-induced changes. To gain mechanistic insights into the therapeutic effects of these particles, we characterized the changes to the relevant inflammatory and metabolic signaling pathways. We assessed metabolic regulator mTOR and related signaling pathways such as hippo, Ubiquitin-proteasome system (ERK5), Tsc1/Tsc2 complex, FoxO1, wnt/β-catenine signaling pathway. Moreover, we examined the activity of jak2/stat3 signaling pathways and Adamts1, which are critically involved in inflammation. Together, our study provides a promising treatment strategy for cerebral stroke based on Se NP induced suppression of excessive inflammation and oxidative metabolism.

Rapamycin and fasting sustain autophagy response activated by ischemia/reperfusion injury and promote retinal ganglion cell survival

Autophagy, the cellular process responsible for degradation and recycling of cytoplasmic components through the autophagosomal–lysosomal pathway, is fundamental for neuronal homeostasis and its deregulation has been identified as a hallmark of neurodegeneration. Retinal hypoxic–ischemic events occur in several sight-treating disorders, such as central retinal artery occlusion, diabetic retinopathy, and glaucoma, leading to degeneration and loss of retinal ganglion cells. Here we analyzed the autophagic response in the retinas of mice subjected to ischemia induced by transient elevation of intraocular pressure, reporting a biphasic and reperfusion time-dependent modulation of the process. Ischemic insult triggered in the retina an acute induction of autophagy that lasted during the first hours of reperfusion. This early upregulation of the autophagic flux limited RGC death, as demonstrated by the increased neuronal loss observed in mice with genetic impairment of basal autophagy owing to heterozygous ablation of the autophagy-positive modulator Ambra1 (Ambra1^+/gt). Upregulation of autophagy was exhausted 24 h after the ischemic event and reduced autophagosomal turnover was associated with build up of the autophagic substrate SQSTM-1/p62, decreased ATG12-ATG5 conjugate, ATG4 and BECN1/Beclin1 expression. Animal fasting or subchronic systemic treatment with rapamycin sustained and prolonged autophagy activation and improved RGC survival, providing proof of principle for autophagy induction as a potential therapeutic strategy in retinal neurodegenerative conditions associated with hypoxic/ischemic stresses.