Toll-like receptor 4 inhibitor protects against retinal ganglion cell damage induced by optic nerve crush in mice

Evaluating the Evidence for Neuroprotective and Axonal Regenerative Activities of Different Inflammatory Cell Types After Optic Nerve Injury

The optic nerve contains retinal ganglion cell (RGC) axons and functions to transmit visual stimuli to the brain. Injury to the optic nerve from ischemia, trauma, or disease leads to retrograde axonal degeneration and subsequent RGC dysfunction and death, causing irreversible vision loss. Inflammatory responses to neurological damage and axonal injuries in the central nervous system (CNS) are typically harmful to neurons and prevent recovery. However, recent evidence indicates that certain inflammatory cell types and signaling pathways are protective after optic nerve injury and promote RGC survival and axonal regeneration. The objective of this review is to examine the evidence for diverse effects of inflammatory cell types on the retina and optic nerve after injury. Additionally, we highlight promising avenues for further research.

Impacts of sulfate polysaccharide JCS1S2 on retinal neovascularization in oxygen-induced retinopathy rats

Retinal neovascularization, a pathological form of angiogenesis, is a leading cause of blindness. This study investigated the effects of Dendrobium sulfate polysaccharide JCS1S2, derived from Dendrobium chrysogenum, on oxygen-induced retinopathy (OIR) in rat models and Müller cells of the rat retina. To this end, we established an OIR rat model and divided the rats into three primary groups, namely, Group I (control), Group II (OIR), and Group III (OIR + JCS1S2). Group III was further subdivided into three subgroups treated with different concentrations of JCS1S2 (10 μg/μL, 20 μg/μL, and 40 μg/μL). After finding the optimal concentration of JCS1S2 by ADP and HE, PCR, Western blot and transcriptome sequencing were used to analyze the role of JCS1S2 in Müller cells of OIR rats and rat retinas. ADP and hematoxylin and eosin (HE) staining revealed that JCS1S2 dose-dependently inhibited retinal neovascularization. Quantitative polymerase chain reaction (qPCR) and Western blot analyses showed significant downregulation of vascular endothelial growth factor A (VEGF-A), VEGF-B, VEGF-D, VEGF receptor 1 (VEGF-R1), and VEGF receptor 2 (VEGF-R2) following JCS1S2 treatment. Transcriptome analysis suggested that JCS1S2 may suppress the activation of the Toll-like receptor (TLR) signaling pathway, regulate the expression of genes associated with endothelial activation and angiogenesis, and participate in the inflammatory and metabolic pathways of the retina. Western blotting data indicate that JCS1S2 can markedly reduce abnormal retinal angiogenesis and Müller cell activation in OIR rats through the TLR4/p-NF-κB/VEGF pathway, JCS1S2 may have the potential as a therapeutic agent for retinal neovascularization.

Cytokines in age-related eye diseases: pathogenesis and potential targets for innovative therapies

Age-related eye diseases (AREDs), such as dry eye disease (DED), age-related macular degeneration (AMD), glaucoma, and diabetic retinopathy (DR), are significant worldwide health concerns due to their rising prevalence and debilitating effects. Despite substantial research on the pathobiology of AREDs, the impact of immune-related alterations caused by aging is still not well understood. Tissue-resident cells and invading immune cells in the eye control innate responses in the event of damage or infection. However, as cells age, they gradually lose their ability to perform their protective duties and develop abnormal characteristics. Therefore, the disrupted regulation of immune responses in the eyes of older individuals enhances their vulnerability to and the intensity of eye disorders. Cytokines, immune system components, have a role in developing AREDs by contributing to inflammation. This paper examines the deficiencies in the pathogenic and therapeutic aspects of pro-inflammatory cytokines in AREDs that require further investigation in future studies.

Microglial cGAS-STING signaling underlies glaucoma pathogenesis

Characterized by progressive degeneration of retinal ganglion cells (RGCs) and vision loss, glaucoma is the primary cause of irreversible blindness, incurable and affecting over 78 million patients. However, pathogenic mechanisms leading to glaucoma-induced RGC loss are incompletely understood. Unexpectedly, we found that cGAS-STING (2'3'-cyclic GMP-AMP-stimulator of interferon genes) signaling, which surveils displaced double-stranded DNA (dsDNA) in the cytosol and initiates innate immune responses, was robustly activated during glaucoma in retinal microglia in distinct murine models. Global or microglial deletion of STING markedly relieved glaucoma symptoms and protected RGC degeneration and vision loss, while mice bearing genetic cGAS-STING supersensitivity aggravated retinal neuroinflammation and RGC loss. Mechanistically, dsDNA from tissue injury activated microglial cGAS-STING signaling, causing deleterious macroglia reactivity in retinas by cytokine-mediated microglia-macroglia interactions, progressively driving apoptotic death of RGCs. Remarkably, preclinical investigations of targeting cGAS-STING signaling by intraocular injection of TBK1i or anti-IFNAR1 antibody prevented glaucoma-induced losses of RGCs and vision. Therefore, we unravel an essential role of cGAS-STING signaling underlying glaucoma pathogenesis and suggest promising therapeutic strategies for treating this devastating disease.

Protective effects of sumatriptan against optic nerve injury in rats via modulation of kynurenine pathway, oxidative stress and apoptosis

Introduction

Traumatic optic neuropathy (TON) is an acute visual dysfunction subsequent to head and neck trauma. Despite immense efforts, there is no effective treatment to minimize the damage caused by TON. Due to its anti-inflammatory and neuroprotective properties, we aimed to measure the effect of sumatriptan on optic nerve injury in rats.

Methods

Bulldog forceps were used to induce optic nerve crush. Immediately after trauma, a single dose of sumatriptan was intravitreally injected and rats were just observed for 1 week. Visual evoked potential (VEP) was recorded to assess optic nerve function on days 2, 5, and 7 after optic nerve injury. Retinas were extracted seven days after trauma to assess molecular and microscopic changes.

Results

Crushing force reduced cell survival, decreased the amplitude of the waves, and prolonged their latency in VEP. In contrast, sumatriptan significantly increased cell survival and shortened the latency of P2 and N2 waves. Likewise, sumatriptan significantly decreased the tissue levels of toll-like receptor 4 (TLR4), phosphorylated extracellular signal-regulated kinase (p-ERK), malondialdehyde (MDA), indole-amine 2,3-dioxygenase 1 (IDO), tumor necrosis factor α (TNF-α), interferon γ (INF-γ), and kynurenine in the retinas of rats.

Conclusion

These findings suggest that sumatriptan can enhance retinal cell viability, improve optic nerve function, and decrease inflammation, possibly through attenuation of TLR4, ERK, and kynurenine signaling pathways. Thus, future clinical trials should assess the efficacy of low-dose intravitreal sumatriptan for patients with TON.

TLR4 deficiency does not alter glaucomatous progression in a mouse model of chronic glaucoma

Glaucoma is a leading cause of irreversible blindness worldwide. Toll-like receptor 4 (TLR4) is a pattern-recognition transmembrane receptor that induces neuroinflammatory processes in response to injury. Tlr4 is highly expressed in ocular tissues and is known to modulate inflammatory processes in both anterior and posterior segment tissues. TLR4 activation can lead to mitochondrial dysfunction and metabolic deficits in inflammatory disorders. Due to its effects on inflammation and metabolism, TLR4 is a candidate to participate in glaucoma pathogenesis. It has been suggested as a therapeutic target based on studies using acute models, such as experimentally raising IOP to ischemia-inducing levels. Nevertheless, its role in chronic glaucoma needs further evaluation. In the current study, we investigated the role of TLR4 in an inherited mouse model of chronic glaucoma, DBA/2J. To do this, we analyzed the effect of Tlr4 knockout (Tlr4 -/-) on glaucoma-associated phenotypes in DBA/2J mice. Our studies found no significant differences in intraocular pressure, iris disease, or glaucomatous progression in Tlr4 -/- compared to Tlr4 +/+ DBA/2J mice. These data do not identify a role for TLR4 in this chronic glaucoma, but further research is warranted to understand its role in other glaucoma models and different genetic contexts.

AIBP: A New Safeguard against Glaucomatous Neuroinflammation

Glaucoma is a group of ocular diseases that cause irreversible blindness. It is characterized by multifactorial degeneration of the optic nerve axons and retinal ganglion cells (RGCs), resulting in the loss of vision. Major components of glaucoma pathogenesis include glia-driven neuroinflammation and impairment of mitochondrial dynamics and bioenergetics, leading to retinal neurodegeneration. In this review article, we summarize current evidence for the emerging role of apolipoprotein A-I binding protein (AIBP) as an important anti-inflammatory and neuroprotective factor in the retina. Due to its association with toll-like receptor 4 (TLR4), extracellular AIBP selectively removes excess cholesterol from the plasma membrane of inflammatory and activated cells. This results in the reduced expression of TLR4-associated, cholesterol-rich lipid rafts and the inhibition of downstream inflammatory signaling. Intracellular AIBP is localized to mitochondria and modulates mitophagy through the ubiquitination of mitofusins 1 and 2. Importantly, elevated intraocular pressure induces AIBP deficiency in mouse models and in human glaucomatous retina. AIBP deficiency leads to the activation of TLR4 in Müller glia, triggering mitochondrial dysfunction in both RGCs and Müller glia, and compromising visual function in a mouse model. Conversely, restoring AIBP expression in the retina reduces neuroinflammation, prevents RGCs death, and protects visual function. These results provide new insight into the mechanism of AIBP function in the retina and suggest a therapeutic potential for restoring retinal AIBP expression in the treatment of glaucoma.

Restoring AIBP expression in the retina provides neuroprotection in glaucoma

Glaucoma is a neurodegenerative disease manifested in retinal ganglion cell (RGC) death and irreversible blindness. While lowering intraocular pressure (IOP) is the only proven therapeutic strategy in glaucoma, it is insufficient for preventing disease progression, thus justifying the recent focus on targeting retinal neuroinflammation and preserving RGCs. We have identified apolipoprotein A-I binding protein (AIBP) as the protein regulating several mechanisms of retinal neurodegeneration. AIBP controls excessive cholesterol accumulation via upregulating the cholesterol transporter ATP-binding cassette transporter 1 (ABCA1) and reduces inflammatory signaling via toll-like receptor 4 (TLR4) and mitochondrial dysfunction. ABCA1, TLR4 and oxidative phosphorylation components are genetically linked to primary open-angle glaucoma. Here we demonstrated that AIBP and ABCA1 expression was decreased, while TLR4, interleukin 1 beta (IL-1 beta), and the cholesterol content increased in the retina of patients with glaucoma and in mouse models of glaucoma. Restoring AIBP expression by a single intravitreal injection of adeno-associated virus (AAV)-AIBP protected RGCs in glaucomatous DBA/2J mice, in mice with microbead-induced chronic IOP elevation, and optic nerve crush. In addition, AIBP expression attenuated TLR4 and IL-1 beta expression, localization of TLR4 to lipid rafts, reduced cholesterol accumulation, and ameliorated visual dysfunction. These studies collectively indicate that restoring AIBP expression in the glaucomatous retina reduces neuroinflammation and protects RGCs and Muller glia, suggesting the therapeutic potential of AAV-AIBP in human glaucoma.

Electroacupuncture restores intestinal mucosal barrier through TLR4/NF-κB p65 pathway in functional dyspepsia-like rats

Functional dyspepsia (FD) is a common functional gastrointestinal disorder with high morbidity. Electroacupuncture (EA) has been applied to treat FD for a long time. The aim of this study was to investigate the effects of EA and its mechanism about intestinal mucosal barrier in rodent model of FD. Male Sprague-Dawley rats were randomly divided into the control group and the model group. Then, the rats in model group were established to the FD model by multifactor interventions. In Experiment 1, qualified FD-like rats were randomly divided into three groups: FD, EA, and acupuncture (AP) groups. The interventions of EA and AP lasted 14 days, food intake, and body weight were recorded every 5 days. In Experiment 2, qualified FD-like rats were randomly divided into five groups: FD, EA, AP, EA + TAK242, and TAK242 groups. The interventions of EA and AP lasted 14 days, while TAK242 injection continued for 6 days. The rats were sacrificed for the measurement of serum Interleukin- 6 (IL-6) and Tumor necrosis factor-α (TNF-α) assayed by ELISA. Western blotting was used to assess the expression of TLR4, Myd88, NF-κB p65, p-NF-κB p65, TRAF6, ZO-1, and occludin in the duodenum. The transmission electron microscope was used to observe the ultrastructure of intestinal epithelial cells. Compared with the rats in the group FD, the rats in EA group had significantly increase of body weight, food intake, and protein expressions of ZO-1 and occludin, while expressions of TLR4, Myd88, NF-κB p65, p-NF-κB p65, TRAF6 in the duodenum and IL-6, and TNF-α in serum were decreased. The EA + TAK242 treatment had similar effects to the EA treatment but with increased potency; compared with EA, AP showed similar but reduced effects. Our data demonstrated that EA is more effective than AP in improving intestine mucosal barrier. The possible mechanisms of EA may involve the TLR4/NF-κB p65 pathway.

Contralateral Astrocyte Response to Acute Optic Nerve Damage Is Mitigated by PANX1 Channel Activity

Glial reactivity is considered a hallmark of damage-induced innate immune responses in the central nervous system. In the visual system, unilateral optic nerve damage elicits dramatic glial reactivity in the retina directly affected by the lesion and a similar, albeit more modest, effect in the contralateral eye. Evaluation of astrocyte changes in a mouse model of optic nerve crush indicates that astrocyte reactivity, as a function of retinal coverage and cellular hypertrophy, occurs within both the experimental and contralateral retinas, although the hypertrophic response of the astrocytes in the contralateral eyes is delayed for at least 24 h. Evaluation of astrocytic reactivity as a function of Gfap expression indicates a similar, muted but significant, response in contralateral eyes. This constrained glial response is completely negated by conditional knock out of Panx1 in both astrocytes and Müller cells. Further studies are required to identify if this is an autocrine or a paracrine suppression of astroglial reactivity.

Immunomodulatory and Antioxidant Drugs in Glaucoma Treatment

Glaucoma, a group of diseases characterized by progressive retinal ganglion cell loss, cupping of the optic disc, and a typical pattern of visual field defects, is a leading cause of severe visual impairment and blindness worldwide. Elevated intraocular pressure (IOP) is the leading risk factor for glaucoma development. However, glaucoma can also develop at normal pressure levels. An increased susceptibility of retinal ganglion cells to IOP, systemic vascular dysregulation, endothelial dysfunction, and autoimmune imbalances have been suggested as playing a role in the pathophysiology of normal-tension glaucoma. Since inflammation and oxidative stress play a role in all forms of glaucoma, the goal of this review article is to present an overview of the inflammatory and pro-oxidant mechanisms in the pathophysiology of glaucoma and to discuss immunomodulatory and antioxidant treatment approaches.

Activation of retinal glial cells contributes to the degeneration of ganglion cells in experimental glaucoma

Elevation of intraocular pressure (IOP) is a major risk factor for neurodegeneration in glaucoma. Glial cells, which play an important role in normal functioning of retinal neurons, are well involved into retinal ganglion cell (RGC) degeneration in experimental glaucoma animal models generated by elevated IOP. In response to elevated IOP, mGluR I is first activated and Kir4.1 channels are subsequently inhibited, which leads to the activation of Müller cells. Müller cell activation is followed by a complex process, including proliferation, release of inflammatory and growth factors (gliosis). Gliosis is further regulated by several factors. Activated Müller cells contribute to RGC degeneration through generating glutamate receptor-mediated excitotoxicity, releasing cytotoxic factors and inducing microglia activation. Elevated IOP activates microglia, and following morphological and functional changes, these cells, as resident immune cells in the retina, show adaptive immune responses, including an enhanced release of pro-inflammatory factors (tumor neurosis factor-α, interleukins, etc.). These ATP and Toll-like receptor-mediated responses are further regulated by heat shock proteins, CD200R, chemokine receptors, and metabotropic purinergic receptors, may aggravate RGC loss. In the optic nerve head, astrogliosis is initiated and regulated by a complex reaction process, including purines, transmitters, chemokines, growth factors and cytokines, which contributes to RGC axon injury through releasing pro-inflammatory factors and changing extracellular matrix in glaucoma. The effects of activated glial cells on RGCs are further modified by the interplay among different types of glial cells. This review is concluded by presenting an in-depth discussion of possible research directions in this field in the future.

Glaucoma and microglia-induced neuroinflammation

Glaucoma is a multifactorial neurodegenerative disease characterized by a progressive optic neuropathy resulting in visual field defects. Elevated intraocular pressure (IOP) is the greatest risk factor for the development of glaucoma, and IOP reduction therapy is the only treatment currently available. However, there are many cases in which retinal degeneration progresses despite sufficient control of IOP. Therefore, it is important to elucidate the pathophysiology of glaucoma that is resistant to current IOP lowering therapies. Experiments using animal glaucoma models show the relationships between microglial neuroinflammatory responses and damage of retinal ganglion cells (RGCs). Inhibition of neuroinflammatory pathways associated with microglial activation appears to be neuroprotective, indicating that microglia may be an important therapeutic target for RGC protection. In this review, we will focus on microglia-induced neuroinflammation in the pathogenesis of glaucoma to offer new insights into the possibility of developing novel neuroprotective therapies targeting microglia.

Emerging Targets for Modulation of Immune Response and Inflammation in Stroke

The inflammatory and immunological responses play a significant role after stroke. The innate immune activation stimulated by microglia during stroke results in the migration of macrophages and lymphocytes into the brain and are responsible for tissue damage. The immune response and inflammation following stroke have no defined targets, and the intricacies of the immunological and inflammatory processes are only partially understood. Innate immune cells enter the brain and meninges during the acute phase, which can cause ischemia damage. Activation of systemic immunity is caused by danger signals sent into the bloodstream by injured brain cells, which is followed by a significant immunodepression that encourages life-threatening infections. Neuropsychiatric sequelae, a major source of post-stroke morbidity, may be induced by an adaptive immune response that is initiated by antigen presentation during the chronic period and is directed against the brain. Thus, the current review discusses the role of immune response and inflammation in stroke pathogenesis, their role in the progression of injury during the stroke, and the emerging targets for the modulation of the mechanism of immune response and inflammation that may have possible therapeutic benefits against stroke.

Microbiome Dysbiosis: A Pathological Mechanism at the Intersection of Obesity and Glaucoma

The rate at which obesity is becoming an epidemic in many countries is alarming. Obese individuals have a high risk of developing elevated intraocular pressure and glaucoma. Additionally, glaucoma is a disease of epidemic proportions. It is characterized by neurodegeneration and neuroinflammation with optic neuropathy and the death of retinal ganglion cells (RGC). On the other hand, there is growing interest in microbiome dysbiosis, particularly in the gut, which has been widely acknowledged to play a prominent role in the etiology of metabolic illnesses such as obesity. Recently, studies have begun to highlight the fact that microbiome dysbiosis could play a critical role in the onset and progression of several neurodegenerative diseases, as well as in the development and progression of several ocular disorders. In obese individuals, gut microbiome dysbiosis can induce endotoxemia and systemic inflammation by causing intestinal barrier malfunction. As a result, bacteria and their metabolites could be delivered via the bloodstream or mesenteric lymphatic vessels to ocular regions at the level of the retina and optic nerve, causing tissue degeneration and neuroinflammation. Nowadays, there is preliminary evidence for the existence of brain and intraocular microbiomes. The altered microbiome of the gut could perturb the resident brain-ocular microbiome ecosystem which, in turn, could exacerbate the local inflammation. All these processes, finally, could lead to the death of RGC and neurodegeneration. The purpose of this literature review is to explore the recent evidence on the role of gut microbiome dysbiosis and related inflammation as common mechanisms underlying obesity and glaucoma.

Anti-inflammatory effect of glucagon-like Peptide-1 receptor agonist on the neurosensory retina in an acute optic nerve injury rat model

PURPOSE

To explore the possibility of using glucagon-like peptide-1 receptor agonist (GLP-1RA) as a new treatment for neuroinflammation, by analyzing retinal pathological changes in an optic nerve crush rat model.

METHODS

Eight-week-old male Sprague-Dawley rats were divided into lixisenatide (LIX, n = 10), traumatic control (T-CON, n = 10), and normal control (n = 5) groups. The optic nerves of left eyes in the LIX and T-CON groups were crushed in a standardized manner. The LIX group was treated with subcutaneous injections of lixisenatide (200 μg/kg/day) for 5 days. One week after initiating treatment, quantitative polymerase chain reaction, Western blot, and immunohistochemistry analyses were performed on the retinal tissues of each group to identify inflammatory markers.

RESULTS

The LIX group showed significantly lower mRNA levels of interleukin 1 beta (IL-1β), tumor necrosis factor-alpha (TNF-α), thioredoxin interacting protein (TXNIP), and glial fibrillary acidic protein (GFAP) than the T-CON group. Also, the LIX group exhibited decreased TXNIP and GFAP expression compared with the T-CON group, and similar expression to the normal control group, according to Western blot analysis. Significantly increased immunohistochemistry staining of Brn3a and decreased TUNEL staining were seen in the LIX group compared with the T-CON group, indicating that lixisenatide contributes to retinal ganglion cell survival in cases of acute optic nerve injury.

CONCLUSIONS

Neuroinflammation was significantly reduced in lixisenatide-treated retinas compared with untreated retinas in our acute optic nerve injury rat model. The neuroprotective effect of lixisenatide indicates that it can serve a new treatment option against clinically intractable traumatic optic neuropathy.

Targeting Differential Roles of Tumor Necrosis Factor Receptors as a Therapeutic Strategy for Glaucoma

Glaucoma is an irreversible sight-threatening disorder primarily due to elevated intraocular pressure (IOP), leading to retinal ganglion cell (RGC) death by apoptosis with subsequent loss of optic nerve fibers. A considerable amount of empirical evidence has shown the significant association between tumor necrosis factor cytokine (TNF; TNFα) and glaucoma; however, the exact role of TNF in glaucoma progression remains unclear. Total inhibition of TNF against its receptors can cause side effects, although this is not the case when using selective inhibitors. In addition, TNF exerts its antithetic roles via stimulation of two receptors, TNF receptor I (TNFR1) and TNF receptor II (TNFR2). The pro-inflammatory responses and proapoptotic signaling pathways predominantly mediated through TNFR1, while neuroprotective and anti-apoptotic signals induced by TNFR2. In this review, we attempt to discuss the involvement of TNF receptors (TNFRs) and their signaling pathway in ocular tissues with focus on RGC and glial cells in glaucoma. This review also outlines the potential application TNFRs agonist and/or antagonists as neuroprotective strategy from a therapeutic standpoint. Taken together, a better understanding of the function of TNFRs may lead to the development of a treatment for glaucoma.

miR-195 Inhibits Proliferation and Enhances Apoptosis of OSCC Cells via Targeting TLR4

The aim of this research was to assess the function of microribonucleic acid (miR)-195 in the apoptosis and proliferation of oral squamous cell carcinoma (OSCC) cells as well as its action mechanism. The downstream target protein of miR-195 was predicted using the biological software. A quantitative polymerase chain reaction (qPCR) was implemented to examine the changes in expressions of miR-195 and its target protein toll-like receptor 4 (TLR4) in OSCC cell lines (TSCCA, Tca8223, Tb3.1, and CAL-27) and normal adult human gingival fibroblasts (HGFs), and the relation between their expressions was assessed. The expressions of phosphorylated proteins in nuclear factor-κB (NF-κB) pathway were determined through western blotting. miR-195 was expressed at a noticeably lower level in four OSCC cells than in HGFs, and the lowest level appeared in CAL-27 cells. Compared with miR-195 control, the miR-195 mimic could obviously raise the expression of miR-195. In CAL-27 cells with high expression of miR-195, the proliferation was inhibited and the apoptosis was evidently enhanced. OSCC cells exhibited evidently reduced protein and mRNA expression of TLR4, and miR-195 expression was inversely associated with TLR4 expression. It was uncovered from the dual-luciferase reporter assay that cells with wild-type TLR4 had prominently weakened luciferase activity relative to cells with mutant-type TLR4, revealing that the direct target of miR-195 is TLR4. The NF-κB pathway was impeded in cells that lowly expressed TLR4. miR-195 blocks the NF-κB pathway via inhibiting the expression of TLR4 in OSCC cells, thereby exerting an antitumor effect.

Ouabain-Na+/K+-ATPase Signaling Regulates Retinal Neuroinflammation and ROS Production Preventing Neuronal Death by an Autophagy-Dependent Mechanism Following Optic Nerve Axotomy In Vitro

Ouabain is a classic Na+K+ATPase ligand and it has been described to have neuroprotective effects on neurons and glial cells at nanomolar concentrations. In the present work, the neuroprotective and immunomodulatory potential of ouabain was evaluated in neonatal rat retinal cells using an optic nerve axotomy model in vitro. After axotomy, cultured retinal cells were treated with ouabain (3 nM) at different periods. The levels of important inflammatory receptors in the retina such as TNFR1/2, TLR4, and CD14 were analyzed. We observed that TNFR1, TLR4, and CD14 were decreased in all tested periods (15 min, 45 min, 24 h, and 48 h). On the other hand, TNFR2 was increased after 24 h, suggesting an anti-inflammatory potential for ouabain. Moreover, we showed that ouabain also decreased Iba-1 (microglial marker) density. Subsequently, analyses of retrograde labeling of retinal ganglion cells (RGC) were performed after 48 h and showed that ouabain-induced RGC survival depends on autophagy. Using an autophagy inhibitor (3-methyladenine), we observed a complete blockage of the ouabain effect. Western blot analyses showed that ouabain increases the levels of autophagy proteins (LC3 and Beclin-1) coupled to p-CREB transcription factor and leads to autophagosome formation. Additionally, we found that the ratio of cleaved/pro-caspase-3 did not change after ouabain treatment; however, p-JNK density was enhanced. Also, ouabain decreased reactive oxygen species production immediately after axotomy. Taken together, our results suggest that ouabain controls neuroinflammation in the retina following optic nerve axotomy and promotes RGC neuroprotection through activation of the autophagy pathway.

Quantitative proteomic analysis after neuroprotective MyD88 inhibition in the retinal degeneration 10 mouse

Progressive photoreceptor death occurs in blinding diseases such as retinitis pigmentosa. Myeloid differentiation primary response protein 88 (MyD88) is a central adaptor protein for innate immune system Toll-like receptors (TLR) and induces cytokine secretion during retinal disease. We recently demonstrated that inhibiting MyD88 in mouse models of retinal degeneration led to increased photoreceptor survival, which was associated with altered cytokines and increased neuroprotective microglia. However, the identity of additional molecular changes associated with MyD88 inhibitor-induced neuroprotection is not known. In this study, we used isobaric tags for relative and absolute quantification (iTRAQ) labelling followed by LC-MS/MS for quantitative proteomic analysis on the rd10 mouse model of retinal degeneration to identify protein pathways changed by MyD88 inhibition. Quantitative proteomics using iTRAQ LC-MS/MS is a high-throughput method ideal for providing insight into molecular pathways during disease and experimental treatments. Forty-two proteins were differentially expressed in retinas from mice treated with MyD88 inhibitor compared with control. Notably, increased expression of multiple crystallins and chaperones that respond to cellular stress and have anti-apoptotic properties was identified in the MyD88-inhibited mice. These data suggest that inhibiting MyD88 enhances chaperone-mediated retinal protection pathways. Therefore, this study provides insight into molecular events contributing to photoreceptor protection from modulating inflammation.

Protective effect and potential mechanism of Schwann cell-derived exosomes on mechanical damage of rat dorsal root ganglion cells

BACKGROUND

Pudendal nerve (PN) injury was one of the most important pathogenesis of stress urinary incontinence (SUI). Schwann cell (SC)-derived exosomes could promote axonal regeneration. Wnt protein could significantly promote axonal regeneration and participate in the regulation of proliferation and differentiation of neural stem cells. Therefore, we sought to determine whether SCs-derived exosomes might also protect against damaged dorsal root ganglion cells (DRGs) through the Wnt/β-catenin pathway.

MATERIAL AND METHODS

The DRGs injury model was fabricated using a four-point bending system. The exosomes were separated from the SCs supernatant. XAV939, which was a small molecule inhibitor, was used to inhibit the Wnt/β-catenin pathway. Next, Cell Counting Kit-8 (CCK8) kit was used to detect cell activity. We evaluated the proliferative activity of DRG cells using the cell cycle and apoptosis detection kit. We assessed the cell apoptotic rates through the Annexin V/PE double staining. Finally, we detect the expression of downstream proteins of Wnt/β-catenin pathway in DRG cells using western blotting.

RESULTS

SC-derived exosomes had protective effects on DRGs after mechanical damage, which could promote cell proliferation, transition of the cell cycle to the G2 phase, and inhibit cell apoptosis. Exogenous administration of XAV939 suppressed the promoting effect of SCs -derived exosomes on DRG cells and the expression of downstream proteins of Wnt/β-catenin pathway in DRG cells was also suppressed.

CONCLUSION

These results suggested that SC-derived exosomes have a repairing effect on DRG cells injury caused by cyclic mechanical stretching (CMS) and the Wnt/β-catenin pathway is potentially involved in the process.

Epac1 regulates TLR4 signaling in the diabetic retinal vasculature

Toll-like receptor 4 (TLR4) polymorphisms occur in diabetic patients. Previous work showed that TLR4 is in the retina of diabetic mice, as well as in retinal endothelial cells (REC) and Müller cells. Since we have shown that exchange protein activated by cAMP 1 (Epac1) can reduce inflammatory mediators, we hypothesized that Epac1 would inhibit TLR4 signaling. We also hypothesized that direct TLR4 inhibition would protect the diabetic retina. Human REC in normal and high glucose were treated with an Epac1 agonist to explore the actions of Epac1 on TLR4 signaling in vitro. Subsequently, 2-month diabetic endothelial cell specific knockout mice for Epac1 (Cdh5Cre-Epac1) and Epac1 floxed mice retinas were used for Western blotting for TLR4 signaling pathways. We also used direct inhibition of TLR4 via Tak242 to investigate diabetes-induced changes in retinal permeability and neuronal loss in the mice. The Epac1 agonist reduced TLR4 signaling in REC grown in high glucose. TLR4 levels and both MyD88-dependent and -independent signaling pathways are increased in Cdh5Cre-Epac1 mice compared to Epac1 floxed mice. Tak242 reduced TLR4 signaling in diabetic mice and reduced diabetes-induced increases in permeability and cell loss in the ganglion cell layer in the Epac1 floxed and Cdh5Cre-Epac1 mice. In conclusion, Epac1 reduced TLR4 signaling in the retina and in REC. Direct inhibition of TLR4 was able to protect the retina against diabetes-induced changes in permeability and cell numbers in the ganglion cell layer.

Retrograde fluorogold labeling of retinal ganglion cells in neonatal mice

Background

The neonatal period, especially postnatal day 10 (P10), is important for mouse retinal ganglion cells (RGCs) development, and an effective labeling technique to track neonatal RGCs is needed. Retrograde fluorogold (FG) labeling is widely used for adult mouse RGCs, but its applicability for the neonatal mouse is still unknown. This study aimed to evaluate the safety and efficiency of retrograde FG labeling in P10 mice.

Methods

The anatomic location of the superior colliculus (SC) of P10 wild-type C57/BL6J mice was clarified by histological brain section and hematoxylin and eosin (H&E) staining. Three doses of 3% FG were injected into the SC of 30 mice, and 3 days post-surgery, labeling efficiency was quantified by retinal flat-mounts, and labeling safety was evaluated by mice mortality.

Results

Samples of brain tissue from 2–3.5 mm posterior to the bregma, and from 0.5–2.0 mm lateral to the midline showed major SC-related structures. The FG-positive RGC density in the 0.3 µL group was 3,563.9±311.9 cells/mm², significantly more than in the 0.6 µL group (1,718.6±177.1 cells/mm²) or 1.0 µL group (2,496.8±342.2 cells/mm²). The mortality rate was 10% in both the 0.3 and 0.6 µL groups, but 40% in the 1.0 µL group.

Conclusions

The appropriate labeling site in P10 mice was confirmed and 0.3 µL FG is an appropriate dose for retrograde labeling of RGCs.

Loss of TLR4 in endothelial cells but not Müller cells protects the diabetic retina

Others have previously reported that global loss of toll-like receptor 4 (TLR4) reduced retinal inflammation. To determine cell specific actions of TLR4 in the retina, we generated diabetic endothelial cell specific and Müller cell specific TLR4 knockout mice. Diabetic Cdh5-Cre TLR4 mice, PDGFRα-Cre TLR4 mice, and TLR4 floxed mice were evaluated for retinal permeability, neuronal damage, and numbers of degenerate capillaries, all changes commonly observed in the diabetic retina. We also measured protein levels of key inflammatory mediators. We found that diabetes increased permeability, neuronal, and vascular damage in all mice. Loss of TLR4 in the retinal endothelial cells protected against these changes when compared to diabetic TLR4 floxed mice. In contrast, loss of TLR4 in Müller cells did not reduce diabetes-induced increases in permeability or neuronal and vascular damage. Elimination of TLR4 in either mouse model reduced inflammatory mediators, as well as VEGF levels. Taken together, our findings suggest that loss of TLR4 in endothelial cells is protective against diabetic-induced damage, while Müller cell TLR4 is not involved in the damage.

New perspectives of immunomodulation and neuroprotection in glaucoma

Glaucoma is the neurodegenerative disease of retinal ganglion cells. The main risk factor for glaucoma is increased intraocular pressure. The processes leading to cell death due to presence of the injury factor comprise multiple molecular mechanisms, as well as the immunological response. The knowledge of immunological mechanisms occurring in glaucomatous degeneration makes it possible to introduce glaucoma treatment modulating the cellular degradation. The glaucoma treatment of the future will make it possible not only to lower the intraocular pressure, but also to moderate the intracellular mechanisms in order to prevent retinal cell degeneration. Citicoline is a drug modulating glutamate excitotoxicity that is already in use. Rho kinase inhibitors were found to stimulate neurite growth and axon regeneration apart from lowering intraocular pressure. The complementary action of brimonidine is to increase neurotrophic factor (NTF) concentrations and inhibit glutamate toxicity. Immunomodulatory therapies with antibodies and gene therapies show promising effects in the current studies. The supplementation of NTFs prevents glaucomatous damage. Resveratrol and other antioxidants inhibit reactive oxygen species formation. Cell transplantation of stem cells, Schwann cells and nerve extracts was reported to be successful so far. Our review presents the most promising new strategies of neuroprotection and immunomodulation in glaucoma.

Treatment with GDF15, a TGFβ superfamily protein, induces protective effect on retinal ganglion cells

Growth differentiation factor 15 (GDF15) is a protein belonging to the transforming growth factor beta (TGF-β) superfamily. The precursor GDF15 is cleaved and activated as a mature GDF15 by protease. GDF15 has been detected in the aqueous humor of the primary open angle glaucoma patients, however the localization and the effect on the retinal ganglion cells (RGCs) are still unknown. Thus, the purpose of this study was to elucidate the effect of GDF15 on mouse optic nerve crush (ONC) model and primary culture of rat RGCs. Immunostaining showed that the GDF15 was in the ganglion cell layer (GCL), and colocalized with GFAP-positive cells in the GCL and the optic nerve. Western blotting analysis showed that the mature GDF15 was upregulated in the retina and the optic nerve after the ONC. Intravitreal injection of GDF15 suppressed RGCs loss of the ONC model mice in vivo. The neurites length of the primary culture of rat RGCs were increased by mature GDF15 treatment. In addition, the neurotrophic effect of GDF15 was canceled by RET inhibitor treatment. These findings indicate that GDF15 has neuroprotective effect on RGCs via GFRAL-RET pathway. Therefore, GDF15 may be one of novel therapeutic targets in RGC degenerative diseases.

AIBP protects retinal ganglion cells against neuroinflammation and mitochondrial dysfunction in glaucomatous neurodegeneration

Glaucoma is a leading cause of blindness worldwide in individuals 60 years of age and older. Despite its high prevalence, the factors contributing to glaucoma progression are currently not well characterized. Glia-driven neuroinflammation and mitochondrial dysfunction play critical roles in glaucomatous neurodegeneration. Here, we demonstrated that elevated intraocular pressure (IOP) significantly decreased apolipoprotein A-I binding protein (AIBP; gene name Apoa1bp) in retinal ganglion cells (RGCs), but resulted in upregulation of TLR4 and IL-1β expression in Müller glia endfeet. Apoa1bp^-/- mice had impaired visual function and Müller glia characterized by upregulated TLR4 activity, impaired mitochondrial network and function, increased oxidative stress and induced inflammatory responses. We also found that AIBP deficiency compromised mitochondrial network and function in RGCs and exacerbated RGC vulnerability to elevated IOP. Administration of recombinant AIBP prevented RGC death and inhibited inflammatory responses and cytokine production in Müller glia in vivo. These findings indicate that AIBP protects RGCs against glia-driven neuroinflammation and mitochondrial dysfunction in glaucomatous neurodegeneration and suggest that recombinant AIBP may be a potential therapeutic agent for glaucoma.

Adipose-derived mesenchymal stem cells protect against CMS-induced depression-like behaviors in mice via regulating the Nrf2/HO-1 and TLR4/NF-κB signaling pathways

Increasing studies show that inflammatory processes may be involved in depressive disorders. Nuclear factor erythroid-2 related factor 2 (Nrf2) modulates tissue microglial M1 phenotypic changes to the M2 phenotype, which is implicated in protection against inflammatory diseases. We have reported that the adipose-derived mesenchymal stem cells (ADSCs) display anti-inflammatory activity. In this study we explored whether the mechanism of anti-inflammatory activity of ADSCs was related to Nrf2. ADSCs were isolated from mouse fat pads and intravenously administered to chronic mild stress (CMS)-exposed C57BL/6 mice at the dose of 1 × 10⁶ once a week for 3 weeks. We showed that ADSC administration significantly remedied CMS-induced depressive-like behaviors in sucrose preference test, tail suspension test, and forced swim test accompanied by suppressing microglial activation and the expression of inflammatory factors including MCP-1, TNF-α, IL-1β, and IL-6. Furthermore, ADSC administration promoted both the expression of BDNF and TrkB, and promoted Nrf2/HO-1 signaling but suppressed TLR4/NF-κB signaling in brain tissue. In order to elucidate the role of Nrf2/HO-1 signaling in ADSC-caused neuroprotection, Nrf2-modified ADSCs were cocultured with BV2 microglial cells, then exposed to lipopolysaccharide (LPS). Downregulation of Nrf2 in ADSCs decreased the protective effects of ADSCs against LPS-induced microglial activation and M1 polarization. Nrf2 overexpression in ADSCs markedly suppressed LPS-induced TLR4 and NF-κB expression in microglial cells. These results suggest a possible antidepressive mechanism correlated with microglial polarization for anti-inflammatory agents, which may provide a new microglia-targeted strategy for depression therapy.

Increased Neuroprotective Microglia and Photoreceptor Survival in the Retina from a Peptide Inhibitor of Myeloid Differentiation Factor 88 (MyD88)

Myeloid differentiation factor 88 (MyD88) is an adaptor protein for the Toll-like receptor (TLR) and interleukin 1 receptor (IL-1R) families of innate immunity receptors that mediate inflammatory responses to cellular injury. TLR/IL1R/MyD88 signaling is known to contribute to retinal degeneration, although how MyD88 regulates neuronal survival, and the effect of MyD88 on the inflammatory environment in the retina, is mostly unknown. In this study, we tested the hypothesis that blocking MyD88-mediated signaling early in retinal degeneration promotes transition of microglia towards a neuroprotective anti-inflammatory phenotype, resulting in enhanced photoreceptor survival. We also tested whether systemic delivery of a pharmacologic MyD88 inhibitor has therapeutic potential. The rd10 mouse model of retinal degeneration was injected intraperitoneally with increasing doses of a MyD88 blocking peptide or control peptide early in degeneration, and inflammatory responses and photoreceptor survival were measured at specific time points using flow cytometry, cytokine profiling, and electroretinograms. Our results demonstrated that rd10 mice injected with a low dose of MyD88 inhibitor peptide showed increased rod photoreceptor function and reduced apoptosis compared with control peptide and uninjected mice. MyD88 inhibition also resulted in fewer microglia/macrophage cells in the photoreceptor layer whereas total peripheral and retinal macrophage were not changed. Furthermore, increased number of cells expressing the Arg1 marker of neuroprotective microglia in the photoreceptor layer and higher MCP-1 and anti-inflammatory cytokine IL-27 were associated with photoreceptor survival. Therefore, these data suggest that the MyD88 inhibitor modified the retina environment to become less inflammatory, leading to improved photoreceptor function and survival.

Integrin CD11b Deficiency Aggravates Retinal Microglial Activation and RGCs Degeneration After Acute Optic Nerve Injury

Neuroinflammation plays a vital role in the process of a variety of retinal ganglion cells (RGCs) degenerative diseases including traumatic optic neuropathy (TON). Retinal microglial activation is believed as a harbinger of TON, and robust microglial activation can aggravate trauma-induced RGCs degeneration, which ultimately leads to RGCs loss. Toll like receptor 4 (TLR4)-triggered inflammation is of great importance in retinal inflammatory response after optic nerve injury. CD11b on macrophage and brain microglia can inhibit TLR4-triggered inflammation. However, the functional role of CD11b in retinal microglia is not well understood. Here, using an optic nerve crush model and CD11b gene deficient mice, we found that CD11b protein expression was mainly on retinal microglia, significantly increased after optic nerve injury, and still maintained at a high level till at least 28 days post crush. Compared with wild type mice, following acute optic nerve injury, CD11b deficient retinae exhibited more exacerbated microglial activation, accelerated RGCs degeneration, less growth associated protein-43 expression, as well as more proinflammatory cytokines such as interleukin-6 and tumor necrosis factor α while less anti-inflammatory factors such as arginase-1 and interleukin-10 production. We conclude that CD11b is essential in regulating retinal microglial activation and neuroinflammatory responses after acute optic nerve injury, which is critical for subsequent RGCs degeneration and loss.

Neuro-protection and neuro-regeneration of the optic nerve: recent advances and future directions

PURPOSE OF REVIEW

Optic neuropathies refer to a collection of diseases in which retinal ganglion cells (RGCs), the specialized neuron of the retina whose axons make up the optic nerve, are selectively damaged. Blindness secondary to optic neuropathies is irreversible as RGCs do not have the capacity for self-renewal and have a limited capacity for self-repair. Numerous strategies are being developed to either prevent further RGC degeneration or replace the cells that have degenerated. In this review, we aim to discuss known limitations to regeneration in central nervous system (CNS), followed by a discussion of previous, current, and future strategies for optic nerve neuroprotection as well as approaches for neuro-regeneration, with an emphasis on developments in the past two years.

RECENT FINDINGS

Neuro-regeneration in the CNS is limited by both intrinsic and extrinsic factors. Environmental barriers to axon regeneration can be divided into two major categories: failure to clear myelin and formation of glial scar. Although inflammatory scars block axon growth past the site of injury, inflammation also provides important signals that activate reparative and regenerative pathways in RGCs. Neuroprotection with neurotrophins as monotherapy is not effective at preventing RGC degeneration likely secondary to rapid clearance of growth factors. Novel approaches involve exploiting different technologies to provide sustained delivery of neurotrophins. Other approaches include application of anti-apoptosis molecules and anti-axon retraction molecules. Although stem cells are becoming a viable option for generating RGCs for cell-replacement-based strategies, there are still many critical barriers to overcome before they can be used in clinical practice. Adjuvant treatments, such as application of electrical fields, scaffolds, and magnetic field stimulation, may be useful in helping transplanted RGCs extend axons in the proper orientation and assist with new synapse formation.

SUMMARY

Different optic neuropathies will benefit from neuro-protective versus neuro-regenerative approaches. Developing clinically effective treatments for optic nerve disease will require a collaborative approach that not only employs neurotrophic factors but also incorporates signals that promote axonogenesis, direct axon growth towards intended targets, and promote appropriate synaptogenesis.

Piezo channel plays a part in retinal ganglion cell damage

Piezo channel is one of the mechanosensitive channels that senses pressure and shearing stress. Previous reports show that Piezo channel is expressed in many tissues such as skin and lung and they have many important roles. In addition, the mRNA of Piezo has been detected in astrocytes in the optic nerve head of mice. However, it is not yet clear where Piezo channel localize in eye and what kind of effects it have. Thus, the purpose of this study was to determine the expression sites of Piezo channel in mouse eyes and effect of Piezo channel on retinal ganglion cells. Immunostaining analysis showed that the Piezo 1/2 were expressed in the cornea, trabecular meshwork of the anterior ocular segment, lens epithelial cells, and on the retinal ganglion cell layer. The expression of retinal Piezo 2 was increased in retinal disorder model mouse caused by high IOP. Piezo 1 agonist Yoda 1 suppressed neurite outgrowth in retinal ganglion cells. On the other hand, Piezo antagonist GsMTx4 promoted neurite outgrowth in retinal ganglion cells. These findings indicate that Piezo channel may contribute to diseases relating the IOP such as glaucoma.

Associations between TLR4 Polymorphisms and Open Angle Glaucoma: A Meta-Analysis

Background

Previous studies exploring the association between toll-like receptor 4 (TLR4) polymorphisms and open angle glaucoma (OAG) presented inconsistent results. We aimed to investigate the association between TLR4 polymorphisms and OAG.

Methods

A systematic literature search was conducted in PubMed, EMBASE, ISI Web of Knowledge, and the Cochrane Library up to 31 December 2018. Odds ratio (OR) and 95% confidence interval (95%CI) were calculated, followed by stratification analyses according to ethnicity and glaucoma subtype.

Results

TLR4 rs7037117 polymorphism had significant associations with increased risk of OAG in allelic model (OR=1.25; 95%CI: 1.09-1.44; P=0.002) and recessive model (OR=1.49; 95%CI: 1.08-2.04; P=0.01). With regard to rs10759930, rs12377632, and rs2149356, the results showed significant increased risks in all genetic models (all P<0.05), whereas, for rs1927914, rs11536889, and rs7045953, no significant associations were identified in any genetic model (all P>0.05). Furthermore, the association of rs1927911 with OAG risk was found to be significant in recessive model (OR=1.34; 95%CI: 1.06-1.71; P=0.02). As for rs4986790 and rs4986791, meta-analyses were not performed due to the limited number of studies and the ethnic differences. Subgroup analysis indicated that the above polymorphisms with significant differences might increase the susceptibility in POAG patients. As for the ethnicity, rs7037117, rs10759930, and rs1927911 might increase the risk in Asians, while rs12377632 and rs2149356 might increase the risk in Asians and Mexicans.

Conclusion

The meta-analysis highlighted that certain mutations of some TLR4 polymorphisms might increase the susceptibility of OAG. However, TLR4 polymorphisms are still far from being candidate genetic biomarkers for OAG. Additional researches involving larger scale epidemiological studies are warranted to validate our results.

Understanding the Role of Innate Immunity in the Response to Intracortical Microelectrodes

Intracortical microelectrodes exhibit enormous potential for researching the nervous system, steering assistive devices and functional electrode stimulation systems for severely paralyzed individuals, and augmenting the brain with computing power. Unfortunately, intracortical microelectrodes often fail to consistently record signals over clinically useful periods. Biological mechanisms, such as the foreign body response to intracortical microelectrodes and self-perpetuating neuroinflammatory cascades, contribute to the inconsistencies and decline in recording performance. Unfortunately, few studies have directly correlated microelectrode performance with the neuroinflammatory response to the implanted devices. However, of those select studies that have, the role of the innate immune system remains among the most likely links capable of corroborating the results of different studies, across laboratories. Therefore, the overall goal of this review is to highlight the role of innate immunity signaling in the foreign body response to intracortical microelectrodes and hypothesize as to appropriate strategies that may become the most relevant in enabling brain-dwelling electrodes of any geometry, or location, for a range of clinical applications.

Natural Dietary Supplementation of Curcumin Protects Mice Brains against Ethanol-Induced Oxidative Stress-Mediated Neurodegeneration and Memory Impairment via Nrf2/TLR4/RAGE Signaling

The aim of the current study was to explore the underlying neuroprotective mechanisms of curcumin (50 mg/kg, for six weeks) against ethanol (5 mg/kg i.p., for six weeks) induced oxidative stress and inflammation-mediated cognitive dysfunction in mice. According to our findings, ethanol triggered reactive oxygen species (ROS), apoptosis, neuroinflammation, and memory impairment, which were significantly inhibited with the administration of curcumin, as assessed by ROS, lipid peroxidation (LPO), and Nrf2/HO-1 (nuclear factor erythroid 2-related factor 2/Heme-oxygenase-1) expression in the experimental mice brains. Moreover, curcumin regulated the expression of the glial cell markers in ethanol-treated mice brains, as analyzed by the relative expression TLR4 (Toll like Receptor 4), RAGE (Receptor for Advanced Glycations End products), GFAP (Glial fibrillary acidic protein), and Iba-1 (Ionized calcium binding adaptor molecule 1), through Western blot and confocal microscopic analysis. Moreover, our results showed that curcumin downregulated the expression of p-JNK (Phospo c-Jun N-Terminal Kinase), p-NF-kB (nuclear factor kappa-light-chain-enhancer of activated B cells), and its downstream targets, as assessed by Western blot and confocal microscopic analysis. Finally, the expression of synaptic proteins and the behavioral results also supported the hypothesis that curcumin may inhibit memory dysfunction and behavioral alterations associated with ethanol intoxication. Altogether, to the best of our knowledge, we believe that curcumin may serve as a potential, promising, and cheaply available neuroprotective compound against ethanol-associated neurodegenerative diseases.

VGF nerve growth factor inducible is involved in retinal ganglion cells death induced by optic nerve crush

VGF nerve growth factor inducible (VGF) is a polypeptide that is induced by neurotrophic factors and is involved in neurite growth and neuroprotection. The mRNA of the Vgf gene has been detected in the adult rat retina, however the roles played by VGF in the retina are still undetermined. Thus, the purpose of this study was to determine the effects of VGF on the retinal ganglion cells (RGCs) of mice in the optic nerve crush (ONC) model, rat-derived primary cultured RGCs and human induced pluripotent stem cells (iPSCs)-derived RGCs. The mRNA and protein of Vgf were upregulated after the ONC. Immunostaining showed that the VGF was located in glial cells including Müller glia and astrocytes but not in the retinal neurons and their axons. AQEE-30, a VGF peptide, suppressed the loss of RGCs induced by the ONC, and it increased survival rat-derived RGCs and promoted the outgrowth of neurites of rat and human iPSCs derived RGCs in vitro. These findings indicate that VGF plays important roles in neuronal degeneration and has protective effects against the ONC on RGCs. Thus, VGF should be considered as a treatment of RGCs degeneration.

MicroRNA-335-5p suppresses lower extremity deep venous thrombosis by targeted inhibition of PAI-1 via the TLR4 signalingpathway

This study aims to investigate the effects of microRNA-335-5p (miR-335-5p) on lower-extremity deep vein thrombosis (LEDVT) by targeting PAI-1 through the TLR4 signaling pathway in rat models. siRNA, mimic, and inhibitor were used for transfection. The miR-335-5p expression was detected by in situ hybridization. CCK-8 assay and flow cytometry were adopted to detect proliferation, cell cycle, and apoptosis, respectively. Scratch test and Matrigel-based tube formation assay were used to detect the effect of miR-335-5p on cell migration ability and tube formation ability. A miR-335-5p lentivirus plasmid was constructed and injected into LEDVT rats. The length and weight of thrombus were measured, changes of thrombus recanalization were observed by CD34 immunohistochemistry, and levels of PAI-1 and inflammatory factors in femoral vein blood were detected by ELISA. LEDVT rats showed a higher AOD value of PAI-1, higher expression of PAI-1, NF-κB, Rac1, IL-1β, and TLR4 and a lower miR-335-5p expression. PAI-1 and miR-335-5p were negatively correlated. Compared to the blank and siRNA-NC groups, the miR-335-5p mimic and siRNA-PAI-1 groups showed declined expression of PAI-1, TLR4, NF-κB, Rac1, and IL-1β, increased proliferation and tube formation abilities, less cells in G0/G1 phase, and decreased apoptosis, decreased length and weight of thrombus, organized thrombus, increased new blood vessels, and decreased levels of PAI-1, IL-1, IL-6, and Tnf-a. miR-335-5p may suppress the occurrence and development of LEDVT in rats by repressing the activation of the TLR4 signaling pathway by targeted inhibition of PAI-1.