Journal of Neuroinflammation最新文献

Background: Chronic ethanol exposure (CEE) is recognized as an important risk factor for depression, and the gut-brain axis has emerged as a key mechanism underlying chronic ethanol exposure-induced anxiety and depression-like behaviors. Short-chain fatty acids (SCFAs), which are the key metabolites generated by gut microbiota from insoluble dietary fiber, exert protective roles on the central nervous system, including the reduction of neuroinflammation. However, the link between gut microbial disturbances caused by chronic ethanol exposure, production of SCFAs, and anxiety and depression-like behaviors remains unclear.

Methods: Initially, a 90-day chronic ethanol exposure model was established, followed by fecal microbiota transplantation model, which was supplemented with SCFAs via gavage. Anxiety and depression-like behaviors were determined by open field test, forced swim test, and elevated plus-maze. Serum and intestinal SCFAs levels were quantified using GC-MS. Changes in related indicators, including the intestinal barrier, intestinal inflammation, neuroinflammation, neurotrophy, and nerve damage, were detected using Western blotting, immunofluorescence, and Nissl staining.

Results: Chronic ethanol exposure disrupted with gut microbial homeostasis, reduced the production of SCFAs, and led to anxiety and depression-like behaviors. Recipient mice transplanted with fecal microbiota that had been affected by chronic ethanol exposure exhibited impaired intestinal structure and function, low levels of SCFAs, intestinal inflammation, activation of neuroinflammation, a compromised blood-brain barrier, neurotrophic defects, alterations in the GABA system, anxiety and depression-like behaviors. Notably, the negative effects observed in these recipient mice were significantly alleviated through the supplementation of SCFAs.

Conclusion: SCFAs not only mitigate damage to intestinal structure and function but also alleviate various lesions in the central nervous system, such as neuroinflammation, and reduce anxiety and depression-like behaviors, which were triggered by transplantation with fecal microbiota that had been affected by chronic ethanol exposure, adding more support that SCFAs serve as a bridge between the gut and the brain.

Retinal neovascularization (RNV) disease is one of the leading causes of blindness, yet the molecular underpinnings of this condition are not well understood. To delve into the critical aspects of cell-mediated angiogenesis, we analyzed our previously published single-cell data. Our analysis revealed that retinal pigment epithelium (RPE) cells serve a crucial promotional function in angiogenesis. RPE cells were regulated by N6-methyladenosine (m6A). Next, we detected several critical m6A methylase in hypoxic ARPE-19 cells and in oxygen-induced retinopathy (OIR) mice, our results revealed a significant decrease in the level of methyltransferase like 3 (METTL3). METTL3 specific inhibitor STM2457 intravitreal injection or METTL3 conditional knockout mice both showed a significantly reduced neovascularization area of retina. Additionally, the angiogenesis-related abilities of human retinal endothelial cells (HRECs) were diminished after co-cultured with ARPE-19 treated with STM2457 or sh-METTL3 in vitro. Furthermore, through the integration of Methylated RNA immunoprecipitation (MeRIP) sequencing and RNA sequencing, we discovered that the metabolic enzyme quinolinate phosphoribosyltransferase (QPRT) was directly modified by METTL3 and recognized by the YTH N6-methyladenosine RNA binding protein C1 (YTHDC1). Moreover, after over-expressing QPRT, the angiogenic abilities of HRECs were improved through the phosphorylated phosphatidylinositol-3-kinase (p-PI3K)/ phosphorylated threonine kinase (p-AKT) pathway. Collectively, our study provided a novel therapeutic target for retinal angiogenesis.

Background: Immune cell metabolism governs the outcome of immune responses and contributes to the development of autoimmunity by controlling lymphocyte pathogenic potential. In this study, we evaluated the metabolic profile of myelin-specific murine encephalitogenic T cells, to identify novel therapeutic targets for autoimmune neuroinflammation.

Methods: We performed metabolomics analysis on actively-proliferating encephalitogenic T cells to study their overall metabolic profile in comparison to resting T cells. Metabolomics, phosphoproteomics, in vitro functional assays, and in vivo studies in experimental autoimmune encephalomyelitis (EAE), a mouse model of multiple sclerosis (MS), were then implemented to evaluate the effect of metabolic targeting on autoreactive T cell pathogenicity. Finally, we confirmed the translational potential of our targeting approach in human pro-inflammatory T helper cell subsets and in T cells from MS patients.

Results: We found that autoreactive encephalitogenic T cells display an altered coenzyme A (CoA) synthesis pathway, compared to resting T cells. CoA fueling with the CoA precursor pantethine (PTTH) affected essential immune-related processes of myelin-specific T cells, such as cell proliferation, cytokine production, and cell adhesion, both in vitro and in vivo. Accordingly, pre-clinical treatment with PTTH before disease onset inhibited the development of EAE by limiting T cell pro-inflammatory potential in vivo. Importantly, PTTH also significantly ameliorated the disease course when administered after disease onset in a therapeutic setting. Finally, PTTH reduced pro-inflammatory cytokine production by human T helper 1 (Th1) and Th17 cells and by T cells from MS patients, confirming its translational potential.

Conclusion: Our data demonstrate that CoA fueling with PTTH in pro-inflammatory and autoreactive T cells may represent a novel therapeutic approach for the treatment of autoimmune neuroinflammation.

Neural stem cells have intact innate immune responses that protect them from virus infection and cell death. Yet, viruses can antagonize such responses to establish neuropathogenesis. Using a forebrain organoid model system at two developmental time points, we identified that neural stem cells, in particular radial glia, are basally primed to respond to virus infection by upregulating several antiviral interferon-stimulated genes. Infection of these organoids with a neuropathogenic Enterovirus-D68 strain, demonstrated the ability of this virus to impede immune activation by blocking interferon responses. Together, our data highlight immune gene signatures present in different types of neural stem cells and differential viral capacity to block neural-specific immune induction.

Background: Immune dysregulation is a hallmark of autoimmune diseases of the central nervous system (CNS), characterized by an excessive immune response, and primary CNS tumors (pCNS-tumors) showing a highly immunosuppressive parenchymal microenvironment.

Methods: Aiming to provide novel insights into the pathogenesis of CNS autoimmunity and cerebral tumor immunity, we analyzed the peripheral blood (PB) and cerebrospinal fluid (CSF) of 81 autoimmune limbic encephalitis (ALE), 148 relapsing-remitting multiple sclerosis (RRMS), 33 IDH-wildtype glioma, 9 primary diffuse large B cell lymphoma of the CNS (CNS-DLBCL), and 110 controls by flow cytometry (FC). Additionally, an in-depth immunophenotyping of the PB from an independent cohort of 20 RRMS and 18 IDH-wildtype glioblastoma patients compared to 19 controls was performed by FC combined with unsupervised computational approaches.

Results: We identified alterations in peripheral and intrathecal adaptive immunity, mainly affecting the T cell (Tc) but also the B cell (Bc) compartment in ALE, RRMS, and pCNS-tumors compared to controls. ALE, RRMS, and pCNS-tumors featured higher expression of the T cell activation marker HLA-DR, which was even more pronounced in pCNS-tumors than in ALE or RRMS. Glioblastoma patients showed signs of T cell exhaustion that were not visible in RRMS patients. In-depth characterization of the PB revealed differences mainly in the T effector and memory compartment between RRMS and glioblastoma patients and similar alterations in the Bc compartment, including atypical Bc, CD19⁺CD20^- double negative Bc, and plasma cells. PB and CSF mFC together with CSF routine parameters could reliably differentiate ALE and RRMS from pCNS-tumors facilitating early diagnosis and treatment.

Conclusions: ALE, RRMS, and pCNS-tumors show distinct but partially overlapping changes mainly in HLA-DR⁺ Tc, memory Tc, exhausted Tc, and Bc subsets providing insights into disease pathogenesis. Moreover, mFC shows diagnostic potential facilitating early diagnosis and treatment.

Acute intoxication with cholinesterase inhibiting organophosphates (OP) can produce life-threatening cholinergic crisis and status epilepticus (SE). Survivors often develop long-term neurological consequences, including spontaneous recurrent seizures (SRS) and impaired cognition. Numerous studies implicate OP-induced neuroinflammation as a pathogenic mechanism contributing to these chronic sequelae; however, little is known about the inflammatory phenotype of innate immune cells in the brain following acute OP intoxication. Thus, the aim of this study was to characterize the natural history of microglial and astrocytic inflammatory phenotypes following acute intoxication with the OP, diisopropylfluorophosphate (DFP). Adult male and female Sprague-Dawley rats were administered a single dose of DFP (4 mg/kg, sc) followed by standard medical countermeasures. Within minutes, animals developed benzodiazepine-resistant SE as determined by monitoring seizures using a modified Racine scale. At 1, 3, 7, 14, and 28 d post-exposure (DPE), neuroinflammation was assessed using translocator protein (TSPO) positron emission tomography (PET) and magnetic resonance imaging (MRI). In both sexes, we observed consistently elevated radiotracer uptake across all examined brain regions and time points. A separate group of animals was euthanized at these same time points to collect tissues for immunohistochemical analyses. Colocalization of IBA-1, a marker for microglia, with iNOS or Arg1 was used to identify pro- and anti-inflammatory microglia, respectively; colocalization of GFAP, a marker for astrocytes, with C3 or S100A10, pro- and anti-inflammatory astrocytes, respectively. We observed shifts in the inflammatory profiles of microglia and astrocyte populations during the first month post-intoxication, largely in hyperintense inflammatory lesions in the piriform cortex and amygdala regions. In these areas, iNOS⁺ proinflammatory microglial cell density peaked at 3 and 7 DPE, while anti-inflammatory Arg1⁺ microglia cell density peaked at 14 DPE. Pro- and anti-inflammatory astrocytes emerged within 7 DPE, and roughly equal ratios of C3⁺ pro-inflammatory and S100A10⁺ anti-inflammatory astrocytes persisted at 28 DPE. In summary, microglia and astrocytes adopted mixed inflammatory phenotypes post-OP intoxication, which evolved over one month post exposure. These activated cell populations were most prominent in the piriform and amygdala areas and were more abundant in males compared to females. The temporal relationship between microglial and astrocytic responses suggests that initial microglial activity may influence delayed, persistent astrocytic responses. Further, our findings identify putative windows for inhibition of OP-induced neuroinflammatory responses in both sexes to evaluate the therapeutic benefit of anti-inflammation in this context.

Genome-wide association studies have identified a protective mutation in the phospholipase C gamma 2 (PLCG2) gene which confers protection against Alzheimer's disease (AD)-associated cognitive decline. Therefore, PLCG2, which is primarily expressed in immune cells, has become a target of interest for potential therapeutic intervention. The protective allele, known as P522R, has been shown to be hyper-morphic in microglia, increasing phagocytosis of amyloid-beta (Aβ), and increasing the release of inflammatory cytokines. However, the effect of this protective mutation on peripheral tissue-resident macrophages, and the extent to which sex modifies this effect, has yet to be assessed. Herein, we show that peripheral macrophages carrying the P522R mutation do indeed show functional differences compared to their wild-type (WT) counterparts, however, these alterations occur in a sex-dependent manner. In macrophages from females, the P522R mutation increases lysosomal protease activity, cytokine secretion, and gene expression associated with cytokine secretion and apoptosis. In contrast, in macrophages from males, the mutation causes decreased phagocytosis and lysosomal protease activity, modest increases in cytokine secretion, and induction of gene expression associated with negative regulation of the immune response. Taken together, these results suggest that the mutation may be conferring different effects dependent on sex and cell type, and highlight the importance of considering sex as a biological variable when assessing the effects of genetic variants and implications for potential immune system-targeted therapies.

Background: The Interleukin-6 (IL-6)-signal transducer and activator of transcription 3 (STAT3) pathway, along with the cyclic GMP-AMP synthase (cGAS)-stimulator of interferon genes (STING) pathway, are critical contributors to neuroinflammation in Alzheimer's disease (AD). Although previous research outside the context of AD has indicated that the IL-6-STAT3 pathway may regulate the cGAS-STING pathway, the exact molecular mechanisms through which IL-6-STAT3 influences cGAS-STING in AD are still not well understood.

Methods: The activation of the IL-6-STAT3 and cGAS-STING pathways in the hippocampus of 5×FAD and WT mice was analyzed using WB and qRT-PCR. To explore the effects of IL-6 deficiency, Il6^+/- mice were crossed with 5×FAD mice, and the subsequent impact on hippocampal STAT3 pathway activity, cGAS-STING pathway activation, amyloid pathology, neuroinflammation, and cognitive function was evaluated through WB, qRT-PCR, immunohistochemistry, ThS staining, ELISA, and behavioral tests. The regulatory role of STAT3 in the transcription of the Cgas and Sting genes was further validated using ChIP-seq and ChIP-qPCR on hippocampal tissue from 5×FAD and Il6^-/-: 5×FAD mice. Additionally, in the BV2 microglial cell line, the impact of STAT3 activation on the transcriptional regulation of Cgas and Sting genes, as well as the production of inflammatory mediators, was examined through WB and qRT-PCR.

Results: We observed marked activation of the IL-6-STAT3 and cGAS-STING pathways in the hippocampus of AD mice, which was attenuated in the absence of IL-6. IL-6 deficiency reduced beta-amyloid deposition and neuroinflammation in the hippocampus of AD mice, contributing to cognitive improvements. Further analysis revealed that STAT3 directly regulates the transcription of both the Cgas and Sting genes. These findings suggest a potential mechanism involving the STAT3-cGAS-STING pathway, wherein IL-6 deficiency mitigates neuroinflammation in AD mice by modulating this pathway.

Conclusion: These findings indicate that the STAT3-cGAS-STING pathway is critical in mediating neuroinflammation associated with AD and may represent a potential therapeutic target for modulating this inflammatory process in AD.

Background: Secondary autoimmune disease (SAID) in the context of alemtuzumab treatment is one of the main safety concerns that may arise following administration in people with multiple sclerosis (pwMS). Contributing factors underlying this adverse event are not well understood. The purpose of this systematic review was to appraise the literature investigating the role of alemtuzumab in the development of SAID in pwMS following treatment and identify potential biomarkers/ risk factors that may be predictive of onset of this manifestation.

Methods: Relevant publications were retrieved from PubMed, Embase, and Web of Science using a three-pronged search strategy containing the following keywords: "multiple sclerosis"; "alemtuzumab"; and "autoimmunity". Studies that fulfilled the specified eligibility criteria and investigated SAID development after alemtuzumab in pwMS were included in the final analysis.

Results: 19 papers were included in the final review. Approximately, 47.92% of pwMS treated with alemtuzumab experienced SAID. A variety of biomarkers and risk factors were noted in the development of SAID, with a focus on immunological changes, including: increased homeostatic proliferation and T cell cycling, along with consistently elevated baseline serum IL-21 levels and thyroid autoantibodies. There was no significant association between known human leukocyte antigen (HLA) risk alleles, lymphocyte profile or dynamics and SAID development.

Conclusions: While the mechanism underlying SAID following alemtuzumab is not fully understood, potential biomarkers and risk factors that may assist in elucidating mechanisms underlying this phenomenon have been documented in several independent studies. Following immunodepletion from alemtuzumab, an IL-21 driven increase in homeostatic proliferation and T cell cycling may disrupt tolerance mechanisms leading to an increase in the propensity toward alemtuzumab-induced autoimmunity. Further research is necessary to clarify the physiological changes after alemtuzumab therapy that trigger SAID in pwMS.