IL-17 signaling induces iNOS+ microglia activation in retinal vascular diseases

MDSCs promote pathological angiogenesis in ocular neovascular disease

BACKGROUND

Ocular neovascular diseases, which contribute significantly to vision loss, lack effective preventive treatments. Recent studies have highlighted the significant involvement of immune cells in neovascular retinopathy. Myeloid-derived suppressor cells (MDSCs) promote the development of neovascularization, but it is unknown whether they participate in pathological neovascularization and whether they are expected to be a therapeutic target.

METHOD

We investigated the role of MDSCs in promoting pathological angiogenesis using an oxygen-induced retinopathy (OIR) model, employing flow cytometry, immunofluorescence, and smart-seq analysis. Then, we evaluated the proportion of MDSCs in patient blood samples using flow cytometry. Additionally, we assessed the effect of MDSC depletion using an anti-Gr-1 monoclonal antibody on retinal vasculopathy and alterations in retinal microglia.

RESULTS

In the OIR model, an elevated ratio of MDSCs was observed in both blood and retinal tissue during phase II (Neovascularization). The depletion of MDSCs resulted in reduced retinal neovascularization and vaso-obliteration, along with a decrease in microglia within the neovascularization area. Furthermore, analysis of gene transcripts associated with MDSCs indicated activation of vascular endothelial growth factor (VEGF) regulation and inflammation. Importantly, infants with ROP exhibited a higher proportion of MDSCs in their blood samples.

CONCLUSION

Our results suggested that excessive MDSCs represent an unrecognized feature of ocular neovascular diseases and be responsible for the retinal vascular inflammation and angiogenesis, providing opportunities for new therapeutic approaches to ocular neovascular disease.

Targeting TNF-α: The therapeutic potential of certolizumab pegol in the early period of cerebral ischemia reperfusion injury in mice

The neuroinflammatory response triggered by cerebral ischemia-reperfusion injury (CIRI) is characterized by the upsurge of pro-inflammatory cytokines, including TNF-α, IL-1β, and IL-6, which promote leukocyte infiltration and subsequent accumulation in the ischemic zone. This accumulation further intensifies inflammation and aggravates ischemic damage. Certolizumab pegol (CZP), a monoclonal antibody targeting TNF-α, is widely used in treating various inflammatory diseases. This study explored the therapeutic potential of CZP in a mouse model of CIRI, induced by middle cerebral artery occlusion (MCAO), focusing on its influence on the microglial inflammatory response. In vitro analyses revealed that CZP markedly inhibits TNF-α-stimulated inflammation in primary microglia with an EC50 of 1.743 ng/mL. In vivo, MCAO mice treated with CZP (10 μg/mouse, i.p.) for 3 days showed reduced infarct volume, partially improved neurological function, and diminished blood-brain barrierdisruption. Additionally, CZP treatment curtailed microglial activation and the release of pro-inflammatory mediators in the early stages of stroke. It also favorably modulated microglial M1/M2 polarization, rebalanced Th17/Treg cells dynamics, and inhibited Caspase-8-mediated GSDMD cleavage, preventing microglial pyroptosis. Collectively, this study described that the treatment with CZP reversed damaging process caused by CIRI, offering a promising therapeutic strategy for the treatment of ischemic stroke.

Interleukin-17A in diabetic retinopathy: The crosstalk of inflammation and angiogenesis

Diabetic retinopathy (DR) is a severe ocular complication of diabetes which can leads to irreversible vision loss in its late-stage. Chronic inflammation results from long-term hyperglycemia contributes to the pathogenesis and progression of DR. In recent years, the interleukin-17 (IL-17) family have attracted the interest of researchers. IL-17A is the most widely explored cytokine in IL-17 family, involved in various acute and chronic inflammatory diseases. Growing body of evidence indicate the role of IL-17A in the pathogenesis of DR. However, the pro-inflammatory and pro-angiogenic effect of IL-17A in DR have not hitherto been reviewed. Gaining an understanding of the pro-inflammatory role of IL-17A, and how IL-17A control/impact angiogenesis pathways in the eye will deepen our understanding of how IL-17A contributes to DR pathogenesis. Herein, we aimed to thoroughly review the pro-inflammatory role of IL-17A in DR, with focus in how IL-17A impact inflammation and angiogenesis crosstalk.

Increased levels and activation of the IL-17 receptor in microglia contribute to enhanced neuroinflammation in cerebellum of hyperammonemic rats

BACKGROUND

Patients with liver cirrhosis may show minimal hepatic encephalopathy (MHE) with mild cognitive impairment and motor incoordination. Rats with chronic hyperammonemia reproduce these alterations. Motor incoordination in hyperammonemic rats is due to increased GABAergic neurotransmission in cerebellum, induced by neuroinflammation, which enhances TNFα-TNFR1-S1PR2-CCL2-BDNF-TrkB pathway activation. The initial events by which hyperammonemia triggers activation of this pathway remain unclear. MHE in cirrhotic patients is triggered by a shift in inflammation with increased IL-17. The aims of this work were: (1) assess if hyperammonemia increases IL-17 content and membrane expression of its receptor in cerebellum of hyperammonemic rats; (2) identify the cell types in which IL-17 receptor is expressed and IL-17 increases in hyperammonemia; (3) assess if blocking IL-17 signaling with anti-IL-17 ex-vivo reverses activation of glia and of the TNFα-TNFR1-S1PR2-CCL2-BDNF-TrkB pathway.

RESULTS

IL-17 levels and membrane expression of the IL-17 receptor are increased in cerebellum of rats with hyperammonemia and MHE, leading to increased activation of IL-17 receptor in microglia, which triggers activation of STAT3 and NF-kB, increasing IL-17 and TNFα levels, respectively. TNFα released from microglia activates TNFR1 in Purkinje neurons, leading to activation of NF-kB and increased IL-17 and TNFα also in these cells. Enhanced TNFR1 activation also enhances activation of the TNFR1-S1PR2-CCL2-BDNF-TrkB pathway which mediates microglia and astrocytes activation.

CONCLUSIONS

All these steps are triggered by enhanced activation of IL-17 receptor in microglia and are prevented by ex-vivo treatment with anti-IL-17. IL-17 and IL-17 receptor in microglia would be therapeutic targets to treat neurological impairment in patients with MHE.

Edaravone dexborneol alleviates cerebral ischemia-reperfusion injury through NF-κB/NLRP3 signal pathway

Inflammatory injury following ischemia-reperfusion (I/R) severely limits the efficacy of stroke treatment. Edaravone dexborneol (C.EDA) has been shown to reduce inflammation following a cerebral hemorrhage. However, the precise anti-inflammatory mechanism of C.EDA is unknown. In this study, we investigated whether C.EDA provides neuroprotection after I/R in rats, as well as the potential mechanisms involved. A middle cerebral artery occlusion/reperfusion (I/R) model was created using Sprague-Dawley rats. The blood flow of the central cerebral artery was monitored by a laser speckle imaging system. The neurological score was used to assess behavioral improvement. Cerebral infarction volume was measured by TTC staining. And the integrity of the blood-brain barrier was detected by Evan's blue staining. The expression of the nuclear factor kappa-B (NF-κB)/ the NOD-like receptor protein (NLRP3) inflammasome signal pathway and microglia polarization were detected by immunofluorescence and Western blotting. The cerebral blood flow ratio indicates that the cerebral I/R model was successfully established. After reperfusion for 72 h, the improvement of neurological scores, infarct volume reduction, and integrity of the blood-brain barrier was observed in I/R rats with C.EDA treatment. Meanwhile, the immunofluorescence result showed that the expression of iNOS, NLRP3, and NF-κB protein was decreased and the level of Arg1 was increased. Western blot analysis showed that the expression of NF-κB/NLRP3 signal pathway-related protein was decreased. In conclusion, this study indicates that C.EDA alleviates I/R injury by blocking the activation of the NLRP3 inflammasome and regulating the polarization of M1/M2 microglia via the NF-κB signal pathway.

Knockdown of A20 attenuates microglial susceptibility to OGD/R-induced ferroptosis and upregulates inflammatory responses

The A20 protein is considered to have a potent anti-inflammatory effect, but its mechanism of action in the regulation of ferroptosis and inflammation after stroke is still unknown. In this study, the A20-knockdown BV2 cell line (sh-A20 BV2) was constructed at first, and the oxygen-glucose deprivation/re-oxygenation (OGD/R) cell model was constructed. Both the BV2 and sh-A20 BV2 cells were treated with the ferroptosis inducer erastin for 48 h, the ferroptosis-related indicators were detected by western blot. The mechanism of ferroptosis was explored by western blot and immunofluorescence. Under OGD/R pressure, the oxidative stress level of sh-A20 BV2 cells was inhibited, but the secretion of the inflammatory factors TNF-α, IL-1β, and IL-6 was significantly upregulated. And sh-A20 BV2 cells had higher expression levels of GPX4 and NLRP3 proteins under OGD/R induction. Western blot further confirmed that sh-A20 BV2 cells inhibited OGD/R-induced ferroptosis. Under the effect of erastin of the ferroptosis inducer (0-1000 nM), sh-A20 BV2 cells had higher cell viability than wild-type BV2 cells and significantly inhibited the accumulation of ROS and the level of oxidative stress damage. It was confirmed that A20 could promote the activation of the IκBα/NFκB/iNOS pathway. It was confirmed by an iNOS inhibitor that iNOS inhibition could reverse the resistance effect of BV2 cells to OGD/R-induced ferroptosis after A20 knockdown. In conclusion, this study demonstrated that inhibition of A20 mediates a stronger inflammatory response while enhancing microglial resistance by knocking down A20 in BV2 cells.

Macrophage/microglia polarization for the treatment of diabetic retinopathy

Macrophages/microglia are immune system defense and homeostatic cells that develop from bone marrow progenitor cells. According to the different phenotypes and immune responses of macrophages (Th1 and Th2), the two primary categories of polarized macrophages/microglia are those conventionally activated (M1) and alternatively activated (M2). Macrophage/microglial polarization is a key regulating factor in the development of inflammatory disorders, cancers, metabolic disturbances, and neural degeneration. Macrophage/microglial polarization is involved in inflammation, oxidative stress, pathological angiogenesis, and tissue healing processes in ocular diseases, particularly in diabetic retinopathy (DR). The functional phenotypes of macrophages/microglia affect disease progression and prognosis, and thus regulate the polarization or functional phenotype of microglia at different DR stages, which may offer new concepts for individualized therapy of DR. This review summarizes the involvement of macrophage/microglia polarization in physiological situations and in the pathological process of DR, and discusses the promising role of polarization in personalized treatment of DR.

Thermos-responsive hydrogel system encapsulated engineered exosomes attenuate inflammation and oxidative damage in acute spinal cord injury

Introduction: Spinal cord injury (SCI) is a serious and disabling condition, and the effectiveness of conventional treatment is limited, such as supportive treatment and emergency surgery. Exosomes derived from umbilical cord mesenchymal stem cells (UCMSC-Exos) have potential therapeutic effects on SCI but are limited by delivery efficiency. Our study aimed to further investigate the therapeutic effects of miR-138-modified UCMSC-exosomes (Exos-138) following SCI. Methods: We developed an injectable triblock polymer of polyglycolic acid copolymer and polyethylene glycol (PLGA-PEG-PLGA)-loaded temperature-sensitive hydrogel of miR-138-modified stem cell exosomes and characterised its biocompatibility in vitro. In Sprague-Dawley rats with SCI, the hydrogel was injected into the injury site, behavioural scores were measured, and pathological analysis was conducted postoperatively to assess neurological recovery. Results: In vitro, our data demonstrated that miR-138-5p-modified UCMSC-Exos can reduce inflammation levels in BV-2 cells through the NLRP3-caspase1 signalling pathway and reduce neuronal apoptosis by downregulating intracellular reactive oxygen species levels through the Nrf2-keap1 signalling cascade. The results of in vivo experiments showed that the P-Exos-138 hydrogel promoted neurological recovery in rats with SCI. Discussion: Our study explored a novel exosome delivery system that can be a potential therapeutic strategy for SCI. Our study, currently, has theoretical value; however, it can serve as a basis for further investigations on the treatment approaches at various stages of SCI development in inflammation-dependent injury of the central nervous system.

Cochlear implantation impairs intracochlear microcirculation and counteracts iNOS induction in guinea pigs

Introduction

Preservation of residual hearing remains a great challenge during cochlear implantation. Cochlear implant (CI) electrode array insertion induces changes in the microvasculature as well as nitric oxide (NO)-dependent vessel dysfunction which have been identified as possible mediators of residual hearing loss after cochlear implantation.

Methods

A total of 24 guinea pigs were randomized to receive either a CI (n = 12) or a sham procedure (sham) by performing a cochleostomy without electrode array insertion (n = 12). The hearing threshold was determined using frequency-specific compound action potentials. To gain visual access to the stria vascularis, a microscopic window was created in the osseous cochlear lateral wall. Cochlear blood flow (CBF) and cochlear microvascular permeability (CMP) were evaluated immediately after treatment, as well as after 1 and 2 h, respectively. Finally, cochleae were resected for subsequent immunohistochemical analysis of the iNOS expression.

Results

The sham control group showed no change in mean CBF after 1 h (104.2 ± 0.7%) and 2 h (100.8 ± 3.6%) compared to baseline. In contrast, cochlear implantation resulted in a significant continuous decrease in CBF after 1 h (78.8 ± 8.1%, p < 0.001) and 2 h (60.6 ± 11.3%, p < 0.001). Additionally, the CI group exhibited a significantly increased CMP (+44.9% compared to baseline, p < 0.0001) and a significant increase in median hearing threshold (20.4 vs. 2.5 dB SPL, p = 0.0009) compared to sham after 2 h. Intriguingly, the CI group showed significantly lower iNOS-expression levels in the organ of Corti (329.5 vs. 54.33 AU, p = 0.0003), stria vascularis (596.7 vs. 48.51 AU, p < 0.0001), interdental cells (564.0 vs. 109.1 AU, p = 0.0003) and limbus fibrocytes (119.4 vs. 18.69 AU, p = 0.0286).

Conclusion

Mechanical and NO-dependent microvascular dysfunction seem to play a pivotal role in residual hearing loss after CI electrode array insertion. This may be facilitated by the implantation associated decrease in iNOS expression. Therefore, stabilization of cochlear microcirculation could be a therapeutic strategy to preserve residual hearing.

Tumor-secreted lactate contributes to an immunosuppressive microenvironment and affects CD8 T-cell infiltration in glioblastoma

Introduction

Glioblastoma is a malignant brain tumor with poor prognosis. Lactate is the main product of tumor cells, and its secretion may relate to immunocytes' activation. However, its role in glioblastoma is poorly understood.

Methods

This work performed bulk RNA-seq analysis and single cell RNA-seq analysis to explore the role of lactate in glioblastoma progression. Over 1400 glioblastoma samples were grouped into different clusters according to their expression and the results were validated with our own data, the xiangya cohort. Immunocytes infiltration analysis, immunogram and the map of immune checkpoint genes' expression were applied to analyze the potential connection between the lactate level with tumor immune microenvironment. Furthermore, machine learning algorithms and cell-cell interaction algorithm were introduced to reveal the connection of tumor cells with immunocytes. By co-culturing CD8 T cells with tumor cells, and performing immunohistochemistry on Xiangya cohort samples further validated results from previous analysis.

Discussion

In this work, lactate is proved that contributes to glioblastoma immune suppressive microenvironment. High level of lactate in tumor microenvironment can affect CD8 T cells' migration and infiltration ratio in glioblastoma. To step further, potential compounds that targets to samples from different groups were also predicted for future exploration.

Alpinetin inhibits neuroinflammation and neuronal apoptosis via targeting the JAK2/STAT3 signaling pathway in spinal cord injury

BACKGROUND

A growing body of research shows that drug monomers from traditional Chinese herbal medicines have antineuroinflammatory and neuroprotective effects that can significantly improve the recovery of motor function after spinal cord injury (SCI). Here, we explore the role and molecular mechanisms of Alpinetin on activating microglia-mediated neuroinflammation and neuronal apoptosis after SCI.

METHODS

Stimulation of microglia with lipopolysaccharide (LPS) to simulate neuroinflammation models in vitro, the effect of Alpinetin on the release of pro-inflammatory mediators in LPS-induced microglia and its mechanism were detected. In addition, a co-culture system of microglia and neuronal cells was constructed to assess the effect of Alpinetin on activating microglia-mediated neuronal apoptosis. Finally, rat spinal cord injury models were used to study the effects on inflammation, neuronal apoptosis, axonal regeneration, and motor function recovery in Alpinetin.

RESULTS

Alpinetin inhibits microglia-mediated neuroinflammation and activity of the JAK2/STAT3 pathway. Alpinetin can also reverse activated microglia-mediated reactive oxygen species (ROS) production and decrease of mitochondrial membrane potential (MMP) in PC12 neuronal cells. In addition, in vivo Alpinetin significantly inhibits the inflammatory response and neuronal apoptosis, improves axonal regeneration, and recovery of motor function.

CONCLUSION

Alpinetin can be used to treat neurodegenerative diseases and is a novel drug candidate for the treatment of microglia-mediated neuroinflammation.

Microglia-Derived Spp1 Promotes Pathological Retinal Neovascularization via Activating Endothelial Kit/Akt/mTOR Signaling

Pathological retinal neovascularization (RNV) is the main character of ischemic ocular diseases, which causes severe visual impairments. Though retinal microglia are well acknowledged to play important roles in both physiological and pathological angiogenesis, the molecular mechanisms by which microglia communicates with endothelial cells (EC) remain unknown. In this study, using single-cell RNA sequencing, we revealed that the pro-inflammatory secreted protein Spp1 was the most upregulated gene in microglia in the mouse model of oxygen-induced retinopathy (OIR). Bioinformatic analysis showed that the expression of Spp1 in microglia was respectively regulated via nuclear factor-kappa B (NF-κB) and hypoxia-inducible factor 1α (HIF-1α) pathways, which was further confirmed through in vitro assays using BV2 microglia cell line. To mimic microglia-EC communication, the bEnd.3 endothelial cell line was cultured with conditional medium (CM) from BV2. We found that adding recombinant Spp1 to bEnd.3 as well as treating with hypoxic BV2 CM significantly enhanced EC proliferation and migration, while Spp1 neutralizing blocked those CM-induced effects. Moreover, RNA sequencing of BV2 CM-treated bEnd.3 revealed a significant downregulation of Kit, one of the type III tyrosine kinase receptors that plays a critical role in cell growth and activation. We further revealed that Spp1 increased phosphorylation and expression level of Akt/mTOR signaling cascade, which might account for its pro-angiogenic effects. Finally, we showed that intravitreal injection of Spp1 neutralizing antibody attenuated pathological RNV and improved visual function. Taken together, our work suggests that Spp1 mediates microglia-EC communication in RNV via activating endothelial Kit/Akt/mTOR signaling and is a potential target to treat ischemic ocular diseases.

Induced Inflammatory and Oxidative Markers in Cerebral Microvasculature by Mentally Depressive Stress

Background

Cerebrovascular disease (CVD) is recognized as the leading cause of permanent disability worldwide. Depressive disorders are associated with increased incidence of CVD. The goal of this study was to establish a chronic restraint stress (CRS) model for mice and examine the effect of stress on cerebrovascular inflammation and oxidative stress responses.

Methods

A total of forty 6-week-old male C57BL/6J mice were randomly divided into the CRS and control groups. In the CRS group (n = 20), mice were placed in a well-ventilated Plexiglas tube for 6 hours per day for 28 consecutive days. On day 29, open field tests (OFT) and sucrose preference tests (SPT) were performed to assess depressive-like behaviors for the two groups (n = 10/group). Macrophage infiltration into the brain tissue upon stress was analyzed by measuring expression of macrophage marker (CD68) with immunofluorescence in both the CRS and control groups (n = 10/group). Cerebral microvasculature was isolated from the CRS and controls (n = 10/group). mRNA and protein expressions of tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), interleukin-6 (IL-6), vascular cell adhesion molecule-1 (VCAM-1), and macrophage chemoattractant protein-1 (MCP-1) in the brain vessels were measured by real-time PCR and Western blot (n = 10/group). Reactive oxygen species (ROS), hydrogen peroxide (H₂O₂), and nicotinamide adenine dinucleotide phosphate (NADPH) oxidase (NOX) activities were quantified by ELISA to study the oxidative profile of the brain vessels (n = 10/group). Additionally, mRNA and protein expressions of NOX subunits (gp91^phox, p47^phox, p67^phox, and p22^phox) in the cerebrovascular endothelium were analyzed by real-time PCR and Western blot (n = 10/group).

Results

CRS decreased the total distances (p < 0.05) and the time spent in the center zone in OFT (p < 0.001) and sucrose preference test ratio in SPT (p < 0.01). Positive ratio of CD68⁺ was increased with CRS in the entire region of the brain (p < 0.001), reflecting increased macrophage infiltration. CRS increased the expression of inflammatory factors and oxidative stress in the cerebral microvasculature, including TNF-α (p < 0.001), IL-1β (p < 0.05), IL-6 (p < 0.05), VCAM-1 (p < 0.01), MCP-1 (p < 0.01), ROS (p < 0.001), and H₂O₂ (p < 0.001). NADPH oxidase (NOX) was activated by CRS (p < 0.01), and mRNA and protein expressions of NOX subunits (gp91^phox, p47^phox, p67^phox, and p22^phox) in brain microvasculature were found to be increased.

Conclusions

To our knowledge, this is the first study to demonstrate that CRS induces depressive stress and causes inflammatory and oxidative stress responses in the brain microvasculature.

Muse cells decrease the neuroinflammatory response by modulating the proportion of M1 and M2 microglia in vitro

Neuroinflammation hinders repair of the central nervous system (CNS). Stem cell transplantation is a very promising approach for treatment of CNS injuries. However, it is difficult to select seed cells that can both facilitate nerve regeneration and improve the microenvironment in the CNS. In this study, we isolated multilineage-differentiating stress-enduring (Muse) cells from bone marrow mesenchymal stem cells. We explored the anti-inflammatory effect and mechanism of Muse cells in vitro by coculture of Muse cells with lipopolysaccharide-stimulated microglia. Our results showed that Muse cells effectively reduced the transcription and secretion of tumor necrosis factor α and interleukin-1β and increased the expression of transforming growth factor-β and interleukin-10 in microglia. In addition, Muse cells decreased the number of M1 microglia and increased the proportion of M2 microglia in an inflammatory environment more effectively than bone marrow mesenchymal stem cells. We also show that Muse cells inhibited the protein expression of toll-like receptor 4 (TLR4) and myeloid differentiation primary response protein (MyD88) and inhibited the expression of the phosphorylated forms of transcription factor p65, nuclear factor (NF)-κB inhibitor alpha, and p38 mitogen-activated protein kinase (MAPK) in microglia. Therefore, we suggest Muse cells cause antineuroinflammatory effects by inhibition of the TLR4/MyD88/NF-κB and p38 MAPK signaling pathways in microglia. Our results shed light on the function of Muse cells in relation to CNS diseases and provide insight into the selection of seed cells.

IL-4 induces reparative phenotype of RPE cells and protects against retinal neurodegeneration via Nrf2 activation

Retinal degeneration is a kind of neurodegeneration characterized by progressive neuronal death and dysfunction of retinal pigment epithelium (RPE) cells, leading to permanent visual impairment. It still lacks effective therapeutic options and new drugs are highly warranted. In this study, we found the expression of IL-4, a critical regulator of immunity, was reduced in both patients and mouse models. Importantly, exogenous intravitreal IL-4 application could exert a novel neuroprotective effect, characterized by well-preserved RPE layer and neuroretinal structure, as well as amplified wave-amplitudes in ERG. The RNA-seq analysis revealed that IL-4 treatment suppressed the essential oxidative and pro-inflammatory pathways in the degenerative retina. Particularly, IL-4 upregulated the IL-4Rα on RPE cells and induced a reparative phenotype via the activation of Nrf2 both in vitro and in vivo. Furthermore, the Nrf2-/- mice displayed no recovery in response to IL-4 application, highlighting a significant role of Nrf2 in IL-4-mediated protection. Our data provides evidence that IL-4 protects against retinal neurodegeneration by its antioxidant and anti-inflammatory property through IL-4Rα upregulation and Nrf2 activation in RPE cells. The IL-4/IL-4Rα-Nrf2 axis maybe the potential targets for the development of novel therapies for neurodegenerative diseases.

Gene Biomarkers Related to Th17 Cells in Macular Edema of Diabetic Retinopathy: Cutting-Edge Comprehensive Bioinformatics Analysis and In Vivo Validation

Background

Previous studies have shown that T-helper 17 (Th17) cell-related cytokines are significantly increased in the vitreous of proliferative diabetic retinopathy (PDR), suggesting that Th17 cells play an important role in the inflammatory response of diabetic retinopathy (DR), but its cell infiltration and gene correlation in the retina of DR, especially in diabetic macular edema (DME), have not been studied.

Methods

The dataset GSE160306 was downloaded from the Gene Expression Omnibus (GEO) database, which contains 9 NPDR samples and 10 DME samples. ImmuCellAI algorithm was used to estimate the abundance of Th17 cells in 24 kinds of infiltrating immune cells. The differentially expressed Th17 related genes (DETh17RGs) between NPDR and DME were documented by difference analysis and correlation analysis. Through aggregate analyses such as gene ontology (GO) and Kyoto Encyclopedia of Gene and Genome (KEGG) pathway enrichment analysis, a protein-protein interaction (PPI) network was constructed to analyze the potential function of DETh17RGs. CytoHubba plug-in algorithm, Lasso regression analysis and support vector machine recursive feature elimination (SVM-RFE) were implemented to comprehensively identify Hub DETh17RGs. The expression archetypes of Hub DETh17RGs were further verified in several other independent datasets related to DR. The Th17RG score was defined as the genetic characterization of six Hub DETh17RGs using the GSVA sample score method, which was used to distinguish early and advanced diabetic nephropathy (DN) as well as normal and diabetic nephropathy. Finally, real-time quantitative PCR (qPCR) was implemented to verify the transcription levels of Hub DETh17RGs in the STZ-induced DR model mice (C57BL/6J).

Results

238 DETh17RGs were identified, of which 212 genes were positively correlated while only 26 genes were negatively correlated. Six genes (CD44, CDC42, TIMP1, BMP7, RHOC, FLT1) were identified as Hub DETh17RGs. Because DR and DN have a strong correlation in clinical practice, the verification of multiple independent datasets related to DR and DN proved that Hub DETh17RGs can not only distinguish PDR patients from normal people, but also distinguish DN patients from normal people. It can also identify the initial and advanced stages of the two diseases (NPDR vs DME, Early DN vs Advanced DN). Except for CDC42 and TIMP1, the qPCR transcription levels and trends of other Hub DETh17RGs in STZ-induced DR model mice were consistent with the human transcriptome level in this study.

Conclusion

This study will improve our understanding of Th17 cell-related molecular mechanisms in the progression of DME. At the same time, it also provides an updated basis for the molecular mechanism of Th17 cell crosstalk in the eye and kidney in diabetes.

Neuron secrete exosomes containing miR-9-5p to promote polarization of M1 microglia in depression

Background

Neuroinflammation is an important component mechanism in the development of depression. Exosomal transfer of MDD-associated microRNAs (miRNAs) from neurons to microglia might exacerbate neuronal cell inflammatory injury.

Results

By sequence identification, we found significantly higher miR-9-5p expression levels in serum exosomes from MDD patients than healthy control (HC) subjects. Then, in cultured cell model, we observed that BV2 microglial cells internalized PC12 neuron cell-derived exosomes while successfully transferring miR-9-5p. MiR-9-5p promoted M1 polarization in microglia and led to over releasing of proinflammatory cytokines, such as interleukin-1β (IL-1β), interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNF-α), which exacerbated neurological damage. Furthermore, we identified suppressor of cytokine signaling 2 (SOCS2) as a direct target of miR-9-5p. Overexpression of miR-9-5p suppressed SOCS2 expression and reactivated SOCS2-repressed Janus kinase (JAK)/signal transducer and activator of transcription 3 (STAT3) pathways. Consistently, we confirmed that adeno-associated virus (AAV)-mediated overexpression of miR-9-5p polarized microglia toward the M1 phenotype and exacerbated depressive symptoms in chronic unpredictable mild stress (CUMS) mouse mode.

Conclusion

MiR-9-5p was transferred from neurons to microglia in an exosomal way, leading to M1 polarization of microglia and further neuronal injury. The expression and secretion of miR-9-5p might be novel therapeutic targets for MDD.

Graphical Abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s12951-022-01332-w.