NLR-Dependent Regulation of Inflammation in Multiple Sclerosis

Inflammation in Metal-Induced Neurological Disorders and Neurodegenerative Diseases

Essential metals play critical roles in maintaining human health as they participate in various physiological activities. Nonetheless, both excessive accumulation and deficiency of these metals may result in neurotoxicity secondary to neuroinflammation and the activation of microglia and astrocytes. Activation of these cells can promote the release of pro-inflammatory cytokines. It is well known that neuroinflammation plays a critical role in metal-induced neurotoxicity as well as the development of neurological disorders, such as Alzheimer's disease (AD), Parkinson's disease (PD), and multiple sclerosis (MS). Initially seen as a defense mechanism, persistent inflammatory responses are now considered harmful. Astrocytes and microglia are key regulators of neuroinflammation in the central nervous system, and their excessive activation may induce sustained neuroinflammation. Therefore, in this review, we aim to emphasize the important role and molecular mechanisms underlying metal-induced neurotoxicity. Our objective is to raise the awareness on metal-induced neuroinflammation in neurological disorders. However, it is not only just neuroinflammation that different metals could induce; they can also cause harm to the nervous system through oxidative stress, apoptosis, and autophagy, to name a few. The primary pathophysiological mechanism by which these metals induce neurological disorders remains to be determined. In addition, given the various pathways through which individuals are exposed to metals, it is necessary to also consider the effects of co-exposure to multiple metals on neurological disorders.

NLRP12-associated autoinflammatory disease: A novel causal mutation and bioinformatics analyses

Nucleotide-binding leucine-rich repeat-containing receptor 12-associated autoinflammatory disease (NLRP12-AID) is a rare autosomal dominant disorder. In this study, we reported a case of this rare disease with a novel NLRP12 mutation (A218V, rs749659859). The patient displayed typical symptoms, including recurrent fever, arthralgia, and skin allergies. Elevated serum IgE, decreased apolipoprotein A1, high-density lipoprotein cholesterol, and fluctuating levels of various leukocyte subtypes, procalcitonin, IL6, creatine kinase, and 25-hydroxyvitamin D were also detected. Inflammatory lesions were observed in multiple organs using 18F-FDG PET/CT. By mining single-cell transcriptome data, we identified relatively high expression of NLRP12 in monocytes compared to other human peripheral blood mononuclear cells. NLRP12-positive monocytes exhibited reduced expression of IL18, CCL3, and TNFA compared to NLRP12-negative monocytes. Structural analyses suggested that the A218V mutation, along with A218T and F402L, may reduce the ATP-binding affinity of the NLRP12 protein. These findings may provide new insights into the mechanisms of NLRP12-AID, and suggest the potential ATP-based therapy for further investigation.

Bioinformatics analysis and experimental verification of NLRX1 as a prognostic factor for esophageal squamous cell carcinoma

Nucleotide binding and oligomeric domain-like receptor X1 (NLRX1), a member of the NLR family, is associated with the physiological and pathological processes of inflammation, autophagy, immunity, metabolism and mitochondrial regulation, and has been demonstrated to have pro- or antitumor effects in various tumor types. However, the biological function of NLRX1 in esophageal squamous cell carcinoma (ESCC) has remained elusive. In the present study, by using bioinformatics methods, the differential expression of NLRX1 at the mRNA level was examined. Overall survival, clinical correlation, receiver operating characteristic curve, Cox regression, co-expression, enrichment, immune infiltration and drug sensitivity analyses were carried out. A nomogram and a calibration curve were constructed. Changes in protein expression levels were investigated by immunohistochemistry and western blotting. The impact of NLRX1 on i) cell proliferation was evaluated by Cell Counting Kit-8 assays; ii) migration was examined by wound-healing assays; iii) migration and invasion were evaluated by Transwell assays; and iv) apoptosis was assessed by Annexin V/PI staining and flow cytometry. The results revealed that, compared to normal adjacent tissue, NLRX1 was lowly expressed in ESCC, and patients with low NLRX1 expression had a shorter survival time. NLRX1 was an independent prognostic factor for ESCC and was associated with tumor grading. Patients in the low-NLRX1 group showed a decrease in the infiltration of activated natural killer cells, monocytes and M0 macrophages, and these immune-cell infiltration levels were positively correlated with NLRX1 expression. Knocking down NLRX1 promoted the proliferation of KYSE450 cells, while overexpression of NLRX1 inhibited the proliferation of ECA109 cells. NLRX1 negatively regulated the PI3K/AKT signaling pathway in ESCC. These findings indicate that, through several mechanisms, NLRX1 suppresses tumor growth in ESCC, which offers new insight for investigating the causes and progression of ESCC, as well as for identifying more efficient therapeutic approaches.

Hippocampal HDAC6 promotes POCD by regulating NLRP3-induced microglia pyroptosis via HSP90/HSP70 in aged mice

BACKGROUND

Postoperative Cognitive Dysfunction (POCD) has attracted increased attention, but its precise mechanism remains to be explored. This study aimed to figure out whether HDAC6 could regulate NLRP3-induced pyroptosis by modulating the functions of HSP70 and HSP90 in microglia to participate in postoperative cognitive dysfunction in aged mice.

METHODS

Animal models of postoperative cognitive dysfunction in aged mice were established by splenectomy under sevoflurane anesthesia. Morris water maze was used to examine the cognitive function and motor ability. Sixteen-months-old C57BL/6 male mice were randomly divided into six groups: control group (C group), sham surgery group (SA group), splenectomy group (S group), splenectomy + HDAC6 inhibitor ACY-1215 group (ACY group), splenectomy + HDAC6 inhibitor ACY-1215 + HSP70 inhibitor Apoptozole group (AP group), splenectomy + solvent control group (SC group). The serum and hippocampus of mice were taken after mice were executed. The protein levels of HDAC6, HSP90, HSP70, NLRP3, GSDMD-N, cleaved-Caspase-1 (P20), IL-1β were detected by western blotting. Serum IL-1β, IL-6 and S100β were measured using ELISA assay, and cell localization of HDAC6 was detected by immunofluorescence. In vitro experiments, BV2 cells were used to validate whether this mechanism worked in microglia. The protein levels of HDAC6, HSP90, HSP70, NLRP3, GSDMD-N, P20, IL-1β were detected by western blotting and the content of IL-1β in the supernatant was measured using ELISA assay. The degree of acetylation of HSP90, the interaction of HSP70, HSP90 and NLRP3 were analyzed by coimmunoprecipitation assay.

RESULTS

Splenectomy under sevoflurane anesthesia in aged mice could prolong the escape latency, reduce the number of crossing platforms, increase the expression of HDAC6 and activate the NLRP3 inflammasome to induce pyroptosis in hippocampus microglia. Using ACY-1215 could reduce the activation of NLRP3 inflammasome, the pyroptosis of microglia and the degree of spatial memory impairment. Apoptozole could inhibit the binding of HSP70 to NLRP3, reduce the degradation of NLRP3 and reverse the protective effect of HDAC6 inhibitors. The results acquired in vitro experiments closely resembled those in vivo, LPS stimulation led to the pyroptosis of BV2 microglia cells and the release of IL-1β due to the activation of the NLRP3 inflammasome, ACY-1215 showed the anti-inflammatory effect and Apoptozole exerted the opposite effect.

CONCLUSIONS

Our findings suggest that hippocampal HDAC6 promotes POCD by regulating NLRP3-induced microglia pyroptosis via HSP90/HSP70 in aged mice.

NLRX1 Inhibits LPS-Induced Microglial Death via Inducing p62-Dependent HO-1 Expression, Inhibiting MLKL and Activating PARP-1

The activation of microglia and the production of cytokines are key factors contributing to progressive neurodegeneration. Despite the well-recognized neuronal programmed cell death regulated by microglial activation, the death of microglia themselves is less investigated. Nucleotide-binding oligomerization domain, leucine-rich repeat-containing X1 (NLRX1) functions as a scaffolding protein and is involved in various central nervous system diseases. In this study, we used the SM826 microglial cells to understand the role of NLRX1 in lipopolysaccharide (LPS)-induced cell death. We found LPS-induced cell death is blocked by necrostatin-1 and zVAD. Meanwhile, LPS can activate poly (ADP-ribose) polymerase-1 (PARP-1) to reduce DNA damage and induce heme oxygenase (HO)-1 expression to counteract cell death. NLRX1 silencing and PARP-1 inhibition by olaparib enhance LPS-induced SM826 microglial cell death in an additive manner. Less PARylation and higher DNA damage are observed in NLRX1-silencing cells. Moreover, LPS-induced HO-1 gene and protein expression through the p62-Keap1-Nrf2 axis are attenuated by NLRX1 silencing. In addition, the Nrf2-mediated positive feedback regulation of p62 is accordingly reduced by NLRX1 silencing. Of note, NLRX1 silencing does not affect LPS-induced cellular reactive oxygen species (ROS) production but increases mixed lineage kinase domain-like pseudokinase (MLKL) activation and cell necroptosis. In addition, NLRX1 silencing blocks bafilomycin A1-induced PARP-1 activation. Taken together, for the first time, we demonstrate the role of NLRX1 in protecting microglia from LPS-induced cell death. The underlying protective mechanisms of NLRX1 include upregulating LPS-induced HO-1 expression via Nrf2-dependent p62 expression and downstream Keap1-Nrf2 axis, mediating PARP-1 activation for DNA repair via ROS- and autophagy-independent pathway, and reducing MLKL activation.

NLRX1: Versatile functions of a mitochondrial NLR protein that controls mitophagy

NLRX1 is a member of the of the Nod-like receptor (NLR) family, and it represents a unique pattern recognition molecule (PRM) as it localizes to the mitochondrial matrix in resting conditions. Over the past fifteen years, NLRX1 has been proposed to regulate multiple cellular processes, including antiviral immunity, apoptosis, reactive oxygen species (ROS) generation and mitochondrial metabolism. Similarly, in vivo models have shown that NLRX1 was associated with the control of a number of diseases, including multiple sclerosis, colorectal cancer and ischemia-reperfusion injury. This apparent versatility in function hinted that a common and general overarching role for NLRX1 may exist. Recent evidence has suggested that NLRX1 controls mitophagy through the detection of a specific "danger signal", namely the defective import of proteins into mitochondria, or mitochondrial protein import stress (MPIS). In this review article, we propose that mitophagy regulation may represent the overarching process detected by NLRX1, which could in turn impact on a number of diseases if dysfunctional.

The function of NLRP3 in anti-infection immunity and inflammasome assembly of common carp (Cyprinus carpio L.)

NLRP3 inflammasome can be activated by a variety of stimuli and plays an important role in protecting host from pathogen invasion and maintaining homeostasis. However, the activation mechanism of NLRP3 inflammasome in fish is still unclear. In the present study, the NLRP3 gene (CcNLRP3) was identified from common carp, which was 3069 bp in length and encoded a protein with five domains. Sequence analysis showed that NLRP3 was evolutionarily conserved, and CcNLRP3 was closely related to that in grass carp and zebrafish. Real-time PCR showed that CcNLRP3 was widely expressed in various immune-related tissues of healthy common carp, and significantly increased after stimulation with E. tarda, A. hydrophila and Cyprinus spring viremia virus (SVCV), suggesting that CcNLRP3 might be involved in the immune defense of common carp. The results of co-IP, spot formation, oligomerization and fluorescence localization showed that CcNLRP3 could interact with CcASC and assemble into inflammasome. The cytotoxicity assays showed that CcNLRP3 inflammasome was involved in the pyroptosis induced by CcGSDME. At the same time, CcNLRP3 could directly interact with CcCaspase-A/B and result in increased Caspase-B enzyme activity and LDH release, indicating that CcNLRP3 could also form inflammasome through ASC-independent pathway. Taken together, the results provide targets and theoretical basis for the prevention and control of infectious diseases in aquaculture.

Dietary Inflammatory Potential in Pediatric Diseases: A Narrative Review

Inflammatory status is one of the main drivers in the development of non-communicable diseases (NCDs). Specific unhealthy dietary patterns and the growing consumption of ultra-processed foods (UPFs) may influence the inflammation process, which negatively modulates the gut microbiota and increases the risk of NCDs. Moreover, several chronic health conditions require special long-term dietary treatment, characterized by altered ratios of the intake of nutrients or by the consumption of disease-specific foods. In this narrative review, we aimed to collect the latest evidence on the pro-inflammatory potential of dietary patterns, foods, and nutrients in children affected by multifactorial diseases but also on the dietetic approaches used as treatment for specific diseases. Considering multifactorial diet-related diseases, the triggering effect of pro-inflammatory diets has been addressed for metabolic syndrome and inflammatory bowel diseases, and the latter for adults only. Future research is required on multiple sclerosis, type 1 diabetes, and pediatric cancer, in which the role of inflammation is emerging. For diseases requiring special diets, the role of single or multiple foods, possibly associated with inflammation, was assessed, but more studies are needed. The evidence collected highlighted the need for health professionals to consider the entire dietary pattern, providing balanced and healthy diets not only to permit the metabolic control of the disease itself, but also to prevent the development of NCDs in adolescence and adulthood. Personalized nutritional approaches, in close collaboration between the hospital, country, and families, must always be promoted together with the development of new methods for the assessment of pro-inflammatory dietary habits in pediatric age and the implementation of telemedicine.

Impact of Microbiome-Brain Communication on Neuroinflammation and Neurodegeneration

The gut microbiome plays a pivotal role in maintaining human health, with numerous studies demonstrating that alterations in microbial compositions can significantly affect the development and progression of various immune-mediated diseases affecting both the digestive tract and the central nervous system (CNS). This complex interplay between the microbiota, the gut, and the CNS is referred to as the gut-brain axis. The role of the gut microbiota in the pathogenesis of neurodegenerative diseases has gained increasing attention in recent years, and evidence suggests that gut dysbiosis may contribute to disease development and progression. Clinical studies have shown alterations in the composition of the gut microbiota in multiple sclerosis patients, with a decrease in beneficial bacteria and an increase in pro-inflammatory bacteria. Furthermore, changes within the microbial community have been linked to the pathogenesis of Parkinson's disease and Alzheimer's disease. Microbiota-gut-brain communication can impact neurodegenerative diseases through various mechanisms, including the regulation of immune function, the production of microbial metabolites, as well as modulation of host-derived soluble factors. This review describes the current literature on the gut-brain axis and highlights novel communication systems that allow cross-talk between the gut microbiota and the host that might influence the pathogenesis of neuroinflammation and neurodegeneration.

Sulfur-Element containing metabolic pathways in human health and crosstalk with the microbiome

In humans, methionine derived from dietary proteins is necessary for cellular homeostasis and regeneration of sulfur containing pathways, which produce inorganic sulfur species (ISS) along with essential organic sulfur compounds (OSC). In recent years, inorganic sulfur species have gained attention as key players in the crosstalk of human health and the gut microbiome. Endogenously, ISS includes hydrogen sulfide (H2S), sulfite (SO32-), thiosulfate (S2O32-), and sulfate (SO42-), which are produced by enzymes in the transsulfuration and sulfur oxidation pathways. Additionally, sulfate-reducing bacteria (SRB) in the gut lumen are notable H2S producers which can contribute to the ISS pools of the human host. In this review, we will focus on the systemic effects of sulfur in biological pathways, describe the contrasting mechanisms of sulfurylation versus phosphorylation on the hydroxyl of serine/threonine and tyrosine residues of proteins in post-translational modifications, and the role of the gut microbiome in human sulfur metabolism.

Periventricular Microglia Polarization and Morphological Changes Accompany NLRP3 Inflammasome-Mediated Neuroinflammation after Hypoxic-Ischemic White Matter Damage in Premature Rats

White matter damage (WMD) is a primary cause of cerebral palsy and cognitive impairment in preterm infants, and no effective treatments are available. Microglia are a major component of the innate immune system. When activated, they form typical pro-inflammatory (M1) and anti-inflammatory (M2) phenotypes and regulate myelin development and synapse formation. Therefore, they may play a pivotal role in hypoxic-ischemic (HI) WMD. Herein, we investigated neural inflammation and long-term microglia phenotypic polarization in a neonatal rat model of hypoxia-ischemia-induced WMD and elucidated the underlying pathophysiological processes. We exposed 3-day-old (P3) Sprague-Dawley rats to hypoxia (8% oxygen) for 2.5 hr after unilateral common carotid artery ligation. The activation of NLRP3 inflammatory bodies, microglia M1/M2 polarization, myelination, and synaptic development in our model were monitored 7, 14, and 21 days after birth. In addition, the Morris water maze test was performed on postnatal Day 28. We confirmed myelination disturbance in the periventricular white matter, abnormal synaptic development, and behavioral changes in the periventricular area during the development of HI WMD. In addition, we found an association between the occurrence and development of HI WMD and activation of the NLRP3 inflammasome, microglial M1/M2 polarization, and the release of inflammatory factors. NLRP3 inhibition can play an anti-inflammatory role by inhibiting the differentiation of microglia into the M1 phenotype, thereby improving myelination and synapse formation. In conclusion, microglia are key mediators of the inflammatory response and exhibit continuous phenotypic polarization 7-21 days after HI-induced WMD. This finding can potentially lead to a new treatment regimen targeting the phenotypic polarization of microglia early after HI-induced brain injury.

IL-11 induces NLRP3 inflammasome activation in monocytes and inflammatory cell migration to the central nervous system

The objective of this study is to examine IL-11-induced mechanisms of inflammatory cell migration to the central nervous system (CNS). We report that IL-11 is produced at highest frequency by myeloid cells among the peripheral blood mononuclear cell (PBMC) subsets. Patients with relapsing-remitting multiple sclerosis (RRMS) have an increased frequency of IL-11+ monocytes, IL-11+ and IL-11R+ CD4+ lymphocytes, and IL-11R+ neutrophils in comparison to matched healthy controls. IL-11+ and granulocyte-macrophage colony-stimulating factor (GM-CSF)+ monocytes, CD4+ lymphocytes, and neutrophils accumulate in the cerebrospinal fluid (CSF). The effect of IL-11 in-vitro stimulation, examined using single-cell RNA sequencing, revealed the highest number of differentially expressed genes in classical monocytes, including up-regulated NFKB1, NLRP3, and IL1B. All CD4+ cell subsets had increased expression of S100A8/9 alarmin genes involved in NLRP3 inflammasome activation. In IL-11R+-sorted cells from the CSF, classical and intermediate monocytes significantly up-regulated the expression of multiple NLRP3 inflammasome-related genes, including complement, IL18, and migratory genes (VEGFA/B) in comparison to blood-derived cells. Therapeutic targeting of this pathway with αIL-11 mAb in mice with RR experimental autoimmune encephalomyelitis (EAE) decreased clinical scores, CNS inflammatory infiltrates, and demyelination. αIL-11 mAb treatment decreased the numbers of NFκBp65+, NLRP3+, and IL-1β+ monocytes in the CNS of mice with EAE. The results suggest that IL-11/IL-11R signaling in monocytes represents a therapeutic target in RRMS.

Microbiota and Glucidic Metabolism: A Link with Multiple Aspects and Perspectives

The global prevalence of overweight and obesity has dramatically increased in the last few decades, with a significant socioeconomic burden. In this narrative review, we include clinical studies aiming to provide the necessary knowledge on the role of the gut microbiota in the development of diabetic pathology and glucose-metabolism-related disorders. In particular, the role of a certain microbial composition of the fermentative type seems to emerge without a specific link to the development in certain subjects of obesity and the chronic inflammation of the adipose tissues, which underlies the pathological development of all the diseases related to glucose metabolism and metabolic syndrome. The gut microbiota plays an important role in glucose tolerance. Conclusion. New knowledge and new information is presented on the development of individualized therapies for patients affected by all the conditions related to reduced glucose tolerance and insulin resistance.

NLRC3 Participates in Inhibiting the Pulmonary Inflammatory Response of Sepsis-Induced Acute Lung Injury

Acute lung injury (ALI) progresses rapidly, is difficult to treat, and has a high fatality rate. The excessive inflammatory response is an important pathological mechanism of ALI. NLRC3 (NLR family CARD domain-containing 3), a non-inflammasome member of the NLR family, has been found that it could negatively regulates various biological pathways associated with inflammatory response, such as NF-κB (nuclear factor kappa B), PI3K (Phosphatidylinositol 3'-kinase)-Akt (protein kinase B)-mTOR (mammalian target of the rapamycin), and STING (stimulator of interferon genes) pathways, which are responsible for the progression of pulmonary inflammation and participate in regulating the pathological progression of ALI. However, the effects of NLRC3 in sepsis-induced pathological injury of lung tissue remain unclear. In this study, we aimed to investigate the potential effects of NLRC3 in the sepsis-induced ALI. To investigate whether NLRC3 participates in inhibiting the pulmonary inflammatory response of sepsis-induced ALI. Sepsis-induced ALI mice models were established by intrabronchial injection of lipopolysaccharide (LPS) or cecum ligation and puncture (CLP). The lentivirus with overexpression of NLRC3 (LV-NLRC3) and downregulation of NLRC3 (LV-NLRC3-RNAi) were transfected to LPS-induced ALI mice. The expression of NLRC3 was upregulated or downregulated in the lung tissue of sepsis-induced ALI mice. Transfection with NLRC3-overexpression lentivirus significantly decreased inflammatory response in the lung of LPS-induced ALI mice in contrast to the control group. By transfection with NLRC3-silencing lentivirus, the inflammatory response in LPS-induced ALI mice was aggravated. Our study provides evidence of the protective effect of NLRC3 in sepsis-induced ALI by inhibiting excessive inflammatory response of the lung tissue.AbbreviationsAcute lung injury: ALI; intensive care units: ICU; lipopolysaccharide: LPS; acute respiratory distress syndrome: ARDS; bronchoalveolar lavage fluid: BALF; nucleotide-binding oligomerization domain-like receptors: NLRs; NLR family CARD domain containing 3: NLRC3; nuclear factor kappa B: NF-κB; tumor necrosis factor receptor-associated factor 6: TRAF6; Phosphatidylinositol 3'-kinase: PI3K; protein kinase B: Akt; mammalian target of the rapamycin: mTOR; stimulator of interferon genes: STING; TANK-binding kinase 1: TBK1; type I interferon: IFN-I; toll-like receptors: TLRs; tumor necrosis factor: TNF; interleukin: IL; NOD-like receptor protein 3: NLRP3; enhanced green fluorescent protein: EGFP; lentivirus: LV; phosphate-buffered saline: PBS; intrabronchial: i.t.; cecum ligation and puncture: CLP; wet/dry: W/D; Real time polymerase chain reaction: RT-PCR; enzyme-linked immunosorbent assay: ELISA; hematoxylin and eosin: H&E; radio immunoprecipitation assay: RIPA; sodium dodecyl sulfate polyacrylamide gel electrophoresis: SDS-PAGE; polyvinylidene fluoride: PVDF; glyceraldehyde 3-phosphate dehydrogenase: GAPDH; bovine serum albumin: BSA; Tris buffered saline containing Tween 20: TBST; standard deviation: SD; one-way analysis of variance: ANOVA; janus kinase 2: JAK2; activators of transcription 3: STAT3; pathogen associated molecular patterns: PAMPs; danger associated molecular patterns: DAMPs.

Altered Lnc-EGFR, SNHG1, and LincRNA-Cox2 Profiles in Patients with Relapsing-Remitting Multiple Sclerosis: Impact on Disease Activity and Progression

Relapsing-remitting multiple sclerosis (RRMS) is the most prevalent MS subtype. Ample evidence has indicated that long noncoding RNAs (lncRNAs) are crucial players in autoimmune and inflammatory disorders. This study investigated the expression of lnc-EGFR, SNHG1, and lincRNA-Cox2 in RRMS patients during active relapses and in remission. Additionally, the expression of FOXP3, a master transcription factor for regulatory T cells, and NLRP3-inflammasome-related genes were determined. Relationships between these parameters and MS activity and annualized relapse rate (ARR) were also evaluated. The study included 100 Egyptian participants: 70 RRMS patients (35 during relapse and 35 in remission) and 30 healthy controls. RRMS patients showed significant downregulation of lnc-EGFR and FOXP3 and dramatic upregulation of SNHG1, lincRNA-Cox2, NLRP3, ASC, and caspase-1 compared to controls. Lower serum TGF-β1 and elevated IL-1β levels were observed in RRMS patients. Notably, patients during relapses displayed more significant alterations than those in remission. Lnc-EGFR was positively correlated with FOXP3 and TGF-β1 and negatively correlated with ARR, SNHG1, lincRNA-Cox2, and NLRP3 inflammasome components. Meanwhile, SNHG1 and lincRNA-Cox2 were positively correlated with ARR, NLRP3, ASC, caspase-1, and IL-1β. Excellent diagnostic performance for lnc-EGFR, FOXP3, and TGF-β1 was demonstrated, while all biomarkers exhibited strong prognostic potential for predicting relapses. Finally, the differential expression of lnc-EGFR, SNHG1, and lincRNA-Cox2 in RRMS patients, especially during relapses, suggests their involvement in RRMS pathogenesis and activity. Correlation between their expression and ARR implies relationships to disease progression. Our findings also highlight their promising roles as biomarkers for RRMS.

The regulation of self-tolerance and the role of inflammasome molecules

Inflammasome molecules make up a family of receptors that typically function to initiate a proinflammatory response upon infection by microbial pathogens. Dysregulation of inflammasome activity has been linked to unwanted chronic inflammation, which has also been implicated in certain autoimmune diseases such as multiple sclerosis, rheumatoid arthritis, type 1 diabetes, systemic lupus erythematosus, and related animal models. Classical inflammasome activation-dependent events have intrinsic and extrinsic effects on both innate and adaptive immune effectors, as well as resident cells in the target tissue, which all can contribute to an autoimmune response. Recently, inflammasome molecules have also been found to regulate the differentiation and function of immune effector cells independent of classical inflammasome-activated inflammation. These alternative functions for inflammasome molecules shape the nature of the adaptive immune response, that in turn can either promote or suppress the progression of autoimmunity. In this review we will summarize the roles of inflammasome molecules in regulating self-tolerance and the development of autoimmunity.

IRAK-M suppresses the activation of microglial NLRP3 inflammasome and GSDMD-mediated pyroptosis through inhibiting IRAK1 phosphorylation during experimental autoimmune encephalomyelitis

The activation of the NOD-like receptor family pyrin domain-containing protein 3 (NLRP3) inflammasome triggers pyroptosis proinflammatory cell death in experimental autoimmune encephalomyelitis (EAE). However, the underlying mechanisms of the inflammatory processes of microglia in EAE remain unclear. Our previous studies suggested that interleukin-1 receptor-associated kinase (IRAK)-M down-regulates the toll-like receptor 4/interleukin-1 receptor signaling pathway. Here, we used IRAK-M knockout (IRAK-M^-/-) mice and their microglia to dissect the role of IRAK-M in EAE. We found that deletion of IRAK-M increased the incidence rate and exacerbated the clinical symptoms in EAE mice. We then found that IRAK-M deficiency promoted the activation of microglia, activated NLRP3 inflammasomes, and enhanced GSDMD-mediated pyroptosis in the microglia of EAE. In contrast, over-expression of IRAK-M exerted inhibitory effects on neuroinflammation, NLRP3 activation, and pyroptosis. Moreover, IRAK-M deficiency enhanced the phosphorylation of IRAK1, while IRAK-M over-expression downregulated the level of phosphorylated IRAK1. Finally, we found upregulated binding of IRAK1 and TNF receptor-associated factor 6 (TRAF6) in IRAK-M^-/- EAE mice compared to WT mice, which was blocked in AAV^IRAK-M EAE mice. Our study reveals a complex signaling network of IRAK-M, which negatively regulates microglial NLRP3 inflammasomes and pyroptosis by inhibiting IRAK1 phosphorylation during EAE. These findings suggest a potential target for the novel therapeutic approaches of multiple sclerosis (MS)/EAE and NLRP3-related inflammatory diseases.

The Role of Gut Dysbiosis and Potential Approaches to Target the Gut Microbiota in Multiple Sclerosis

It has now been established that a perturbation in gut microbiome composition exists in multiple sclerosis (MS) and its interplay with the immune system and brain could potentially contribute to the development of the disease and influence its course. The effects of the gut microbiota on the disease may be mediated by direct interactions between bacteria and immune cells or through interactions of products of bacterial metabolism with immune and CNS cells. In this review article we summarize the ways in which the gut microbiome of people with MS differs from controls and how bacterial metabolites can potentially play a role in MS pathogenesis, and examine approaches to alter the composition of the gut microbiota potentially alleviating gut dysbiosis and impacting the course of MS.

Overview of the anti-inflammatory function of the innate immune sensor NLRC3

The innate immune system is the first line of defense for the host against any microbial attack. It can quickly identify microorganisms and produce an immune response, removing pathogenic microorganisms. However, a strong immune response might lead to excessive inflammation and even autoimmune diseases. NLRC3 is an important regulator of innate immune system homeostasis. It is a member of the anti-inflammatory NLR family and can inhibit excessive immune response in the body. In this review, we primarily focused on the current research progress on NLRC3 and its potential application. It can decrease the production of pro-inflammatory cytokines by inhibiting the NF-κB, MAK-ERK, PI3K-mTOR, IL-6/JAK2/STAT3, and cGAS-STING pathways. It also inhibits inflammatory responses by interfering with the assembly and activity of the NLRP3 inflammasome complexes. Additionally, NLRC3 can also reduce the functions of some antigen-presenting cells and their ability to activate and polarize CD4⁺ T cells into Th1 and Th17 subsets. NLRC3 is closely related to the development of tumors, infectious diseases, autoimmune diseases, and AD. These diseases might be treated effectively by regulating the expression of NLRC3.

Ten decadal advances in fungal biology leading towards human well-being

Fungi are an understudied resource possessing huge potential for developing products that can greatly improve human well-being. In the current paper, we highlight some important discoveries and developments in applied mycology and interdisciplinary Life Science research. These examples concern recently introduced drugs for the treatment of infections and neurological diseases; application of -OMICS techniques and genetic tools in medical mycology and the regulation of mycotoxin production; as well as some highlights of mushroom cultivaton in Asia. Examples for new diagnostic tools in medical mycology and the exploitation of new candidates for therapeutic drugs, are also given. In addition, two entries illustrating the latest developments in the use of fungi for biodegradation and fungal biomaterial production are provided. Some other areas where there have been and/or will be significant developments are also included. It is our hope that this paper will help realise the importance of fungi as a potential industrial resource and see the next two decades bring forward many new fungal and fungus-derived products.

Ketogenic and Modified Mediterranean Diet as a Tool to Counteract Neuroinflammation in Multiple Sclerosis: Nutritional Suggestions

Ketogenic Diet is a nutritional pattern often used as dietotherapy in inflammatory diseases, including neurological disorders. Applied on epileptic children since 1920, in recent years it has been taken into account again as a tool to both reduce inflammatory burdens and ameliorate the nutritional status of patients affected by different pathologies. Multiple sclerosis (MS) is considered an immune-mediated neuro-inflammatory disease and diet is a possible factor in its pathogenesis. The aim of this work is to investigate the main potential targets of MS-related impairments, in particular the cognitive deficits, focusing on the alteration of biomarkers such as the Brain Derived-Neurotrophic Factor and the Tryptophan/Kynurenine ratio that could play a role on neuroprotection and thus on MS progression. Furthermore, we here propose nutritional suggestions which are useful in the development of a ketogenic diet protocol that takes advantage of the anti-inflammatory properties of low-carbohydrate foods from the Mediterranean diet to be applied to subjects with MS. In conclusion, this approach will allow one to develop the ketogenic diet combined with a modified Mediterranean diet as a possible tool to improve neuroinflammation in multiple sclerosis.

Magnolol prevented brain injury through the modulation of Nrf2-dependent oxidative stress and apoptosis in PLP-induced mouse model of multiple sclerosis

Multiple sclerosis (MS) is an immune-mediated chronic inflammatory demyelinating disease of the central nervous system (CNS). The aim of the current study was to investigate the effects of magnolol in an experimental autoimmune encephalomyelitis (EAE) model of MS in female mice. Magnolol (0.1, 1, and 10 mg/kg) was administered once daily for 21 days after immunization of mice. Magnolol post-immunization treatment significantly reversed clinical scoring, EAE-associated pain parameters, and motor dysfunction in a dose-dependent manner. Magnolol treatment significantly inhibited oxidative stress by reducing malondialdehyde (MDA), nitric oxide (NO) production, and myeloperoxidase (MPO) activity while enhancing the level of antioxidants such as reduced glutathione (GSH), glutathione-S-transferase (GST), catalase, and superoxide dismutase (SOD) in the brain and spinal cord. It reduced cytokine levels in the brain and spinal cord. It suppressed CD8+ T cells frequency in the spleen tissue. Magnolol remarkably reversed the EAE-associated histopathology of the brain and spinal cord tissue. Magnolol significantly intensifies the antioxidant defense system by enhancing the expression level of nuclear factor erythroid 2-related factor (Nrf2) while decreasing the expression of inducible nitric oxide synthase (iNOS) and cleaved-caspase-3 in the brain. Molecular docking results showed that magnolol possesses a better binding affinity for Nrf2, iNOS, and caspase-3 proteins. Taken together, the present study demonstrated that magnolol has significant neuroprotective properties in EAE via inhibition of oxidative stress.

The interaction of O-GlcNAc-modified NLRX1 and IKK-α modulates IL-1β expression in M1 macrophages

NOD-like receptor (NLR)X1 (NLRX1) is a negative regulator of inflammation by inhibiting nuclear factor-κB (NF-κB) signaling and downstream pro-inflammatory factors. However, its post-translational modification and how it participates in regulating the inflammatory responses in macrophages are still unclear. Here, we found that NLRX1 was modified with O-linked N-acetylglucosamine (O-GlcNAc). The interaction and co-localization between NLRX1 and O-GlcNAc transferase (OGT) was validated by co-immunoprecipitation and confocal microscopy analysis, and the nucleotide-binding domain (NBD) region of NLRX1 was required for its interaction with OGT. NLRX1 protein increased significantly after treatment with a high dose of OGT inhibitor OSMI-1. Elevated O-GlcNAcylation level promoted NLRX1 ubiquitination and decreased NLRX1 stability proved by ubiquitination and cycloheximide (CHX) chase experiments, and enhanced the interaction between NLRX1 and inhibitor of nuclear factor kappaB kinase-α (IKK-α), thus reducing the expression of inflammatory cytokine IL-1β in M1 macrophages. Together, our results indicate that the interaction between NLRX1 and O-GlcNAcylation coordinates and modulates the inflammatory process in macrophages.

The innate immune receptor Nlrp12 suppresses autoimmunity to the retina

Background

Nod-like receptors (NLRs) are critical to innate immune activation and induction of adaptive T cell responses. Yet, their role in autoinflammatory diseases of the central nervous system (CNS) remains incompletely defined. The NLR, Nlrp12, has been reported to both inhibit and promote neuroinflammation in an animal model of multiple sclerosis (experimental autoimmune encephalomyelitis, EAE), where its T cell-specific role has been investigated. Uveitis resulting from autoimmunity of the neuroretina, an extension of the CNS, involves a breach in immune privilege and entry of T cells into the eye. Here, we examined the contribution of Nlrp12 in a T cell-mediated model of uveitis, experimental autoimmune uveitis (EAU).

Methods

Mice were immunized with interphotoreceptor retinoid-binding protein peptide 1–20 (IRBP_1–20) emulsified in Complete Freund’s adjuvant, CFA. Uveitis was evaluated by clinical and histopathological scoring, and comparisons were made in WT vs. Nlrp12^−/− mice, lymphopenic Rag1^−/− mice reconstituted with WT vs. Nlrp12^−/− CD4⁺ T cells, or among bone marrow (BM) chimeric mice. Antigen-specific Th-effector responses were evaluated by ELISA and intracellular cytokine staining. Cellular composition of uveitic eyes from WT or Nlrp12^−/− mice was compared using flow cytometry. Expression of Nlrp12 and of cytokines/chemokines within the neuroretina was evaluated by immunoblotting and quantitative PCR.

Results

Nlrp12^−/− mice developed exacerbated uveitis characterized by extensive vasculitis, chorioretinal infiltrates and photoreceptor damage. Nlrp12 was dispensable for T cell priming and differentiation of peripheral Th1 or Th17 cells, and uveitis in immunodeficient mice reconstituted with either Nlrp12^−/− or WT T cells was similar. Collectively, this ruled out T cells as the source of Nlrp12-mediated protection to EAU. Uveitic Nlrp12^−/− eyes had more pronounced myeloid cell accumulation than uveitic WT eyes. Transplantation of Nlrp12^−/− BM resulted in increased susceptibility to EAU regardless of host genotype, but interestingly, a non-hematopoietic origin for Nlrp12 function was also observed. Indeed, Nlrp12 was found to be constitutively expressed in the neuroretina, where it suppressed chemokine/cytokine induction.

Conclusions

Our data identify a combinatorial role for Nlrp12 in dampening autoimmunity of the neuroretina. These findings could provide a pathway for development of therapies for uveitis and potentially other autoinflammatory/autoimmune diseases of the CNS.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12974-022-02425-x.

Caffeine treatment started before injury reduces hypoxic-ischemic white-matter damage in neonatal rats by regulating phenotypic microglia polarization

BACKGROUND

Reducing neuroinflammatory damage is an effective strategy for treating white-matter damage (WMD) in premature infants. Caffeine can ameliorate hypoxia-ischemia-induced brain WMD; however, its neuroprotective effect and mechanism against hypoxic-ischemic WMD remain unclear.

METHODS

We used 3-day-old Sprague-Dawley rats to establish a model of cerebral hypoxia-ischemia-induced brain WMD after unilateral common carotid artery ligation and hypoxia exposure (8% O₂ + 92% N₂) for 2.5 h. Mechanism experiments were conducted to detect M1/M2 polarization and activation of microglia and NLRP3 inflammasome.

RESULTS

Caffeine inhibited NLRP3 inflammasome activation, reduced microglial Iba-1 activation, inhibited microglia M1 polarization, and promoted microglia M2 polarization by downregulating CD86 and iNOS protein expression, inhibiting the transcription of the proinflammatory TNF-α and IL-1β, upregulating CD206 and Arg-1 expression, and promoting the transcription of the anti-inflammatory factors IL-10 and TGF-β. Importantly, we found that these caffeine-mediated effects could be reversed after inhibiting A2aR activity.

CONCLUSIONS

Caffeine improved long-term cognitive function in neonatal rats with hypoxic-ischemic WMD via A2aR-mediated inhibition of NLRP3 inflammasome activation, reduction of microglial activation, regulation of the phenotypic polarization of microglia and the release of inflammatory factors, and improvement of myelination development.

IMPACT

The direct protective effect of caffeine on hypoxic-ischemic white-matter damage (WMD) and its mechanism remains unclear. This study elucidated this mechanism using neonatal rats as an animal model of hypoxia-ischemia-induced cerebral WMD. The findings demonstrated caffeine as a promising therapeutic tool against immature WMD to protect neonatal cognitive function. We found that caffeine pretreatment reduced WMD in immature brains via regulation of microglial activation and polarization by adenosine A2a receptor, thereby, providing a scientific basis for future clinical application of caffeine.

NOD-like receptors in autoimmune diseases

Autoimmune diseases are chronic immune diseases characterized by dysregulation of immune system, which ultimately results in a disruption in self-antigen tolerance. Cumulative data show that nucleotide-binding and oligomerization domain (NOD)-like receptors (NLRs) play essential roles in various autoimmune diseases, such as inflammatory bowel disease (IBD), rheumatoid arthritis (RA), systemic lupus erythematosus (SLE), psoriasis, multiple sclerosis (MS), etc. NLR proteins, consisting of a C-terminal leucine-rich repeat (LRR), a central nucleotide-binding domain, and an N-terminal effector domain, form a group of pattern recognition receptors (PRRs) that mediate the immune response by specifically recognizing cellular pathogen-associated molecular patterns (PAMPs) or damage-associated molecular patterns (DAMPs) and triggering numerous signaling pathways, including RIP2 kinase, caspase-1, nuclear factor kappa B (NF-κB), mitogen-activated protein kinase (MAPK) and so on. Based on their N-terminal domain, NLRs are divided into five subfamilies: NLRA, NLRB, NLRC, NLRP, and NLRX1. In this review, we briefly describe the structures and signaling pathways of NLRs, summarize the recent progress on NLR signaling in the occurrence and development of autoimmune diseases, as well as highlight numerous natural products and synthetic compounds targeting NLRs for the treatment of autoimmune diseases.

Widespread Disruptions of White Matter in Familial Multiple Sclerosis: DTI and NODDI Study

Diffusion tensor imaging (DTI) is a noninvasive, quantitative MRI technique that measures white matter (WM) integrity. Many brain dimensions are heritable, including white matter integrity measured with DTI. Family studies are valuable to provide insights into the interactive effects of non-environmental factors on multiple sclerosis (MS). To examine the contribution of familial factors to the diffusion signals across WM microstructure, we performed DTI and calculated neurite orientation dispersion plus density imaging (NODDI) diffusion parameters in two patient groups comprising familial and sporadic forms of multiple sclerosis and their unaffected relatives. We divided 111 subjects (49 men and 62 women: age range 19-60) into three groups conforming to their MS history. The familial MS group included 30 participants (patients; n = 16, healthy relatives; n = 14). The sporadic group included 41 participants (patients; n = 10, healthy relatives; n = 31). Forty age-matched subjects with no history of MS in their families were defined as the control group. To study white matter integrity, two methods were employed: one for calculating the mean of DTI, FA, and MD parameters on 18 tracts using Tracts Constrained by Underlying Anatomy (TRACULA) and the other for whole brain voxel-based analysis using tract-based spatial statistics (TBSS) on NDI and ODI parameters derived from NODDI and DTI parameters. Voxel-based analysis showed considerable changes in FA, MD, NDI, and ODI in the familial group when compared with the control group, reflecting widespread impairment of white matter in this group. The analysis of 18 tracts with TRACULA revealed increased MD and FA reduction in more tracts (left and right ILF, UNC, and SLFT, forceps major and minor) in familial MS patients vs. the control group. There were no significant differences between the patient groups. We found no consequential changes in healthy relatives of both patient groups in voxel-based and tract analyses. Considering the multifactorial etiology of MS, familial studies are of great importance to clarify the effects of certain predisposing factors on demyelinating brain pathology.

RNA Sequencing of CD4+ T Cells in Relapsing-Remitting Multiple Sclerosis Patients at Relapse: Deciphering the Involvement of Novel genes and Pathways

CD4⁺ T cells are known as a noteworthy potential modulator of inflammation in multiple sclerosis (MS). In the current study, we investigated the transcriptome profile of CD4⁺ T cells in patients with relapsing-remitting MS (RRMS) at the relapse phase. We performed RNA sequencing of CD4⁺ T cells isolated from four relapsing-remitting MS (RRMS) patients at the relapse phase and four age- and sex-matched healthy controls. The edgeR statistical method was employed to determine differentially expressed genes (DEGs). Gene set enrichment analysis was subsequently performed. Applying a physical interaction network, genes with higher degrees were selected as hub genes. A total of 1278 and 1034 genes were defined at significantly higher or lower levels, respectively, in CD4⁺ T cells of RRMS patients at the relapse phase as compared with healthy controls. The top up- and downregulated genes were JAML and KDM3A. The detected DEGs were remarkable on chromosomes 1 and 2, respectively. The DEGs were mainly enriched in the pathways "regulation of transcription, DNA-templated," "regulation of B cell receptor signaling pathway," "protein phosphorylation," "epidermal growth factor receptor signaling pathway," and "positive regulation of neurogenesis." Moreover, 16 KEGG pathways mostly associated with the immune system and viral infections were enriched. In the constructed physical interaction networks, UBA52 and TP53 were shown to be the most highly ranked hub genes among upregulated and downregulated genes, respectively. By applying global transcriptome profiling of CD4⁺ T cells, we deciphered the involvement of several novel genes and pathways in MS pathogenesis. The present results must be confirmed by in vivo and in vitro studies.

Global trends and prospects about inflammasomes in stroke: a bibliometric analysis

Background

Sterile inflammation is a key pathological process in stroke. Inflammasome activation has been implicated in various inflammatory diseases, including ischemic stroke and hemorrhagic stroke. Hence, targeting inflammasomes is a promising approach for the treatment of stroke.

Methods

We applied bibliometric methods and techniques. The Web of Science Core Collection was searched for studies indexed from database inception to November 26, 2020. We generated various visual maps to display publications, authors, sources, countries, and keywords.

Results

Our literature search yielded 427 publications related to inflammasomes involved in stroke, most of which consisted of original research articles and reviews. In particular, we found that there was a substantial increase in the number of relevant publications in 2018. Furthermore, most of the publications with the highest citation rates were published in 2014. Relatively, the field about inflammasomes in stroke developed rapidly in 2014 and 2018. Many institutions contributed to these publications, including those from China, the United States, and worldwide. We found that NLR family pyrin domain containing 3 (NLRP3) was the most studied, followed by NLRP1, NLRP2, and NLRC4 among the inflammasomes associated with stroke. Analysis of keywords suggested that the most studied mechanisms involved dysregulation of extracellular pH, efflux of Ca²⁺ ions, dysfunction of K⁺/Na⁺ ATPases, mitochondrial dysfunction, and damage to mitochondrial DNA.

Conclusions

Given the potential diagnostic and therapeutic implications, the specific mechanisms of inflammasomes contributing to stroke warrant further investigation. We used bibliometric methods to objectively present the global trend of inflammasomes in stroke, and to provide important information for relevant researchers.

NLRC5: A Potential Target for Central Nervous System Disorders

Nucleotide oligomerization domain-like receptors (NLRs), a class of pattern recognition receptors, participate in the host’s first line of defense against invading pathogenic microorganisms. NLR family caspase recruitment domain containing 5 (NLRC5) is the largest member of the NLR family and has been shown to play an important role in inflammatory processes, angiogenesis, immunity, and apoptosis by regulating the nuclear factor-κB, type I interferon, and inflammasome signaling pathways, as well as the expression of major histocompatibility complex I genes. Recent studies have found that NLRC5 is also associated with neuronal development and central nervous system (CNS) diseases, such as CNS infection, cerebral ischemia/reperfusion injury, glioma, multiple sclerosis, and epilepsy. This review summarizes the research progress in the structure, expression, and biological characteristics of NLRC5 and its relationship with the CNS.

Sensing the world and its dangers: An evolutionary perspective in neuroimmunology

Detecting danger is key to the survival and success of all species. Animal nervous and immune systems cooperate to optimize danger detection. Preceding studies have highlighted the benefits of bringing neurons into the defense game, including regulation of immune responses, wound healing, pathogen control, and survival. Here, we summarize the body of knowledge in neuroimmune communication and assert that neuronal participation in the immune response is deeply beneficial in each step of combating infection, from inception to resolution. Despite the documented tight association between the immune and nervous systems in mammals or invertebrate model organisms, interdependence of these two systems is largely unexplored across metazoans. This review brings a phylogenetic perspective of the nervous and immune systems in the context of danger detection and advocates for the use of non-model organisms to diversify the field of neuroimmunology. We identify key taxa that are ripe for investigation due to the emergence of key evolutionary innovations in their immune and nervous systems. This novel perspective will help define the primordial principles that govern neuroimmune communication across taxa.

Therapeutic potential of the target on NLRP3 inflammasome in multiple sclerosis

Inflammasomes are multi-protein macromolecular complexes that typically comprise of three units, a sensor, an adaptor and procaspase-1. The assembly of each inflammasome is dictated by a unique pattern recognition receptors (PRRs) in response to pathogen-associated molecular patterns (PAMPs) or other endogenous danger-associated molecular patterns (DAMPs) in the cytosol of the host cells, and promote the maturation and secretion of IL-1β and IL-18 during the inflammatory process. Specific inflammasomes are involved in the host defense response against different pathogens, and the latter have evolved multiple corresponding mechanisms to inhibit inflammasome activation. The nucleotide-binding oligomerization domain leucine-rich repeat and pyrin domain-containing 3 (NLRP3) inflammasome is the best understood in terms of molecular mechanisms, and is a promising therapeutic target in immune-related disorders. Multiple sclerosis (MS) is an autoimmune disease characterized by inflammatory demyelination of white matter in the central nervous system, increased levels of IL-1β in the cerebrospinal fluid (CSF) of relapsed patients, and deposition of caspase-1 in the spinal cord. The direct involvement of the NLRP3 inflammasome in the occurrence and development of MS was ascertained in the experimental autoimmune encephalomyelitis (EAE) animal model. In this review, we have focused on the mechanisms underlying activation of the NLRP3 inflammasome in MS or EAE, as well as inhibitors that specifically target the complex and alleviate disease progression, in order to unearth new therapeutic strategies against MS.

17β-Estradiol Reduces Demyelination in Cuprizone-fed Mice by Promoting M2 Microglia Polarity and Regulating NLRP3 Inflammasome

Estrogen produces a beneficial role in animal models of multiple sclerosis (MS). The effect of 17β-estradiol therapy on microglia polarization and neuroinflammation in the corpus callosum of the cuprizone-induced demyelination model has not been elucidated. In this study, mice were given 0.2% cuprizone (CPZ) for 5 weeks to induce demyelination during which they received 50 ng of 17β-estradiol (EST), injected subcutaneously in the neck region, twice weekly. Data revealed that treatment with 17β-estradiol therapy (CPZ+EST) improved neurological behavioral deficits, displayed by a significant reduction in escape latencies, in comparison to untreated CPZ mice. Also, administration of 17β-estradiol caused a decrease in demyelination levels and axonal injury, as demonstrated by staining with Luxol fast blue, immunofluorescence to myelin basic protein, and transmission electron microscopy analysis. In addition, at the transcriptional level in the brain, mice treated with 17β-estradiol (CPZ+EST) showed a decrease in the levels of M1-assosicted microglia markers (CD86, iNOS and MHC-II) whereas M2-associated genes (Arg-1, CD206 and Trem-2) were increased, compared to CPZ mice. Moreover, administration of 17β-estradiol resulted in a significant reduction (∼3-fold) in transcript levels of NLRP3 inflammasome and its downstream product IL-18, compared to controls. In summary, this study demonstrated for the first time that exogenous 17β-estradiol therapy robustly leads to the reduction of M1 phenotype, stimulation of polarized M2 microglia, and repression of NLRP3 inflammasome in the corpus callosum of CPZ demyelination model of MS. The positive effects of 17β-estradiol on microglia and inflammasome seems to facilitate and accelerate the remyelination process.

Immunoregulatory Effects of Tolerogenic Probiotics in Multiple Sclerosis

Gut microbiota has essential roles in the prevention and progression of multiple sclerosis (MS). The association between the gut microbiota and the central nervous system (CNS) or immune system response of MS patients has been documented in many studies. The composition of the gut microbiota could lead to sensitization or resistance against promotion and development of MS disease. Probiotics are the major part of gut microflorapopulation and could be substituted with tolerogenic probiotics that protect the CNS against autoimmune responses. Tolerogenic probiotics with anti-inflammatory and immuno-modulatory properties have effects on intestinal flora and can reestablish regulatory mucosal and systemic immune responses. Probiotics are able to prevent and restore excessive activation of inflammatory responses, especially autoreactive T cells and inflammatory cytokines. Tolerogenic probiotics, through induction of regulatory T cells and increase of anti-inflammatory cytokines, play a crucial role in controlling inflammation and maintaining tolerance and hemostasis. Therefore, probiotics can be considered as a preventive or therapeutic tool in MS. In the present review, we focus on the immunoregulatory effects of tolerogenic probiotics on the severity of disease, as well as Th1, Th2, and Treg populations in different experimental and human studies of MS.

Regulation of neuroimmune processes by damage- and resolution-associated molecular patterns

Sterile inflammatory processes are essential for the maintenance of central nervous system homeostasis, but they also contribute to various neurological disorders, including neurotrauma, stroke, and demyelinating or neurodegenerative diseases. Immune mechanisms in the central nervous system and periphery are regulated by a diverse group of endogenous proteins, which can be broadly divided into the pro-inflammatory damage-associated molecular patterns (DAMPs) and anti-inflammatory resolution-associated molecular patterns (RAMPs), even though there is notable overlap between the DAMP- and RAMP-like activities for some of these molecules. Both groups of molecular patterns were initially described in peripheral immune processes and pathologies; however, it is now evident that at least some, if not all, of these immunomodulators also regulate neuroimmune processes and contribute to neuroinflammation in diverse central nervous system disorders. The review of recent literature demonstrates that studies on DAMPs and RAMPs of the central nervous system still lag behind the much broader research effort focused on their peripheral counterparts. Nevertheless, this review also reveals that over the last five years, significant advances have been made in our understanding of the neuroimmune functions of several well-established DAMPs, including high-mobility group box 1 protein and interleukin 33. Novel neuroimmune functions have been demonstrated for other DAMPs that previously were considered almost exclusively as peripheral immune regulators; they include mitochondrial transcription factor A and cytochrome C. RAMPs of the central nervous system are an emerging area of neuroimmunology with very high translational potential since some of these molecules have already been used in preclinical and clinical studies as candidate therapeutic agents for inflammatory conditions, such as multiple sclerosis and rheumatoid arthritis. The therapeutic potential of DAMP antagonists and neutralizing antibodies in central nervous system neuroinflammatory diseases is also supported by several of the identified studies. It can be concluded that further studies of DAMPs and RAMPs of the central nervous system will continue to be an important and productive field of neuroimmunology.

Organic Selenium Reaches the Central Nervous System and Downmodulates Local Inflammation: A Complementary Therapy for Multiple Sclerosis?

Multiple sclerosis (MS) is an inflammatory and demyelinating disease of the central nervous system (CNS). The persistent inflammation is being mainly attributed to local oxidative stress and inflammasome activation implicated in the ensuing demyelination and axonal damage. Since new control measures remain necessary, we evaluated the preventive and therapeutic potential of a beta-selenium-lactic acid derivative (LAD-βSe), which is a source of organic selenium under development, to control experimental autoimmune encephalomyelitis (EAE) that is an animal model for MS. Two EAE murine models: C57BL/6 and SJL/J immunized with myelin oligodendrocyte glycoprotein and proteolipid protein, respectively, and a model of neurodegeneration induced by LPS in male C57BL/6 mice were used. The preventive potential of LAD-βSe was initially tested in C57BL/6 mice, the chronic MS model, by three different protocols that were started 14 days before or 1 or 7 days after EAE induction and were extended until the acute disease phase. These three procedures were denominated preventive therapy -14 days, 1 day, and 7 days, respectively. LAD-βSe administration significantly controlled clinical EAE development without triggering overt hepatic and renal dysfunction. In addition of a tolerogenic profile in dendritic cells from the mesenteric lymph nodes, LAD-βSe also downregulated cell amount, activation status of macrophages and microglia, NLRP3 (NOD-like receptors) inflammasome activation and other pro-inflammatory parameters in the CNS. The high Se levels found in the CNS suggested that the product crossed the blood-brain barrier having a possible local effect. The hypothesis that LAD-βSe was acting locally was then confirmed by using the LPS-induced neurodegeneration model that also displayed Se accumulation and downmodulation of pro-inflammatory parameters in the CNS. Remarkably, therapy with LAD-βSe soon after the first remitting episode in SJL/J mice, also significantly downmodulated local inflammation and clinical disease severity. This study indicates that LAD-βSe, and possibly other derivatives containing Se, are able to reach the CNS and have the potential to be used as preventive and therapeutic measures in distinct clinical forms of MS.

PIM2 deletion alleviates lipopolysaccharide (LPS)-induced respiratory distress syndrome (ARDS) by suppressing NLRP3 inflammasome

Inflammation has an essential role in regulating the pathogenesis of acute respiratory distress syndrome (ARDS). The serine/threonine kinase PIM2 is highly expressed in human macrophages, and exhibits regulatory role in inflammatory response. However, its effect on ARDS progression has not been investigated and still remains unclear. In the study, we attempted to investigate the potential of PIM2 during ARDS progression, and to reveal the underlying molecular mechanisms. Here, we found that PIM2 expression was dramatically up-regulated in lipopolysaccharide (LPS)-exposed murine macrophages through a dose- and time-dependent manner. Additionally, we found that PIM2 knockdown greatly alleviated LPS-triggered activation of Caspase-1, interleukin (IL)-1β, NOD-like receptor pyrin domain 3 (NLRP3) and apoptosis-associated speck-like protein (ASC) in macrophages, along with suppressed inflammatory response. Importantly, we identified that PIM2 could directly interact with NLRP3. PIM2 over-expression could further promote LPS-triggered inflammation and NLRP3 inflammasome in macrophages. Furthermore, PIM2 knockout significantly alleviated the severity of ARDS in LPS-challenged mice. Evidently decreased inflammatory response and NLRP3 inflammasome were detected in pulmonary tissues of LPS-treated mice with PIM2 deficiency. Together, our findings demonstrated that PIM2 as a promising therapeutic target for ARDS treatment through regulating NLRP3 inflammasome.

Gut Microbiota as a Trigger for Metabolic Inflammation in Obesity and Type 2 Diabetes

The gut microbiota has been linked to the development of obesity and type 2 diabetes (T2D). The underlying mechanisms as to how intestinal microbiota may contribute to T2D are only partly understood. It becomes progressively clear that T2D is characterized by a chronic state of low-grade inflammation, which has been linked to the development of insulin resistance. Here, we review the current evidence that intestinal microbiota, and the metabolites they produce, could drive the development of insulin resistance in obesity and T2D, possibly by initiating an inflammatory response. First, we will summarize major findings about immunological and gut microbial changes in these metabolic diseases. Next, we will give a detailed view on how gut microbial changes have been implicated in low-grade inflammation. Lastly, we will critically discuss clinical studies that focus on the interaction between gut microbiota and the immune system in metabolic disease. Overall, there is strong evidence that the tripartite interaction between gut microbiota, host immune system and metabolism is a critical partaker in the pathophysiology of obesity and T2D.

Experimental autoimmune encephalopathy (EAE)-induced hippocampal neuroinflammation and memory deficits are prevented with the non-opioid TLR2/TLR4 antagonist (+)-naltrexone

Multiple sclerosis (MS) is associated with burdensome memory impairments and preclinical literature suggests that these impairments are linked to neuroinflammation. Previously, we have shown that toll-like receptor 4 (TLR4) antagonists, such as (+)-naltrexone [(+)-NTX], block neuropathic pain and associated spinal inflammation in rats. Here we extend these findings to first demonstrate that (+)-NTX blocks TLR2 in addition to TLR4. Additionally, we examined in two rat strains whether (+)-NTX could attenuate learning and memory disturbances and associated neuroinflammation using a low-dose experimental autoimmune encephalomyelitis (EAE) model of MS. EAE is the most commonly used experimental model for the human inflammatory demyelinating disease, MS. This low-dose model avoided motor impairments that would confound learning and memory measurements. Fourteen days later, daily subcutaneous (+)-NTX or saline injections began and continued throughout the study. Contextual and auditory-fear conditioning were conducted at day 21 to assess hippocampal and amygdalar function. With this low-dose model, EAE impaired long-term, but not short-term, contextual fear memory; both long-term and short-term auditory-cued fear memory were spared. This was associated with increased mRNA for hippocampal interleukin-1β (IL-1β), TLR2, TLR4, NLRP3, and IL-17 and elevated expression of the microglial marker Iba1 in CA1 and DG regions of the hippocampus, confirming the neuroinflammation observed in higher-dose EAE models. Importantly, (+)-NTX completely prevented the EAE-induced memory impairments and robustly attenuated the associated proinflammatory effects. These findings suggest that (+)-NTX may exert therapeutic effects on memory function by dampening the neuroinflammatory response in the hippocampus through blockade of TLR2/TLR4. This study suggests that TLR2 and TLR4 antagonists may be effective at treating MS-related memory deficits.

Intranasal anti-caspase-1 therapy preserves myelin and glucose metabolism in a model of progressive multiple sclerosis

Inflammatory demyelination and axonal injury in the central nervous system (CNS) are cardinal features of progressive multiple sclerosis (MS), and linked to activated brain macrophage-like cells (BMCs) including resident microglia and trafficking macrophages. Caspase-1 is a pivotal mediator of inflammation and cell death in the CNS. We investigated the effects of caspase-1 activation and its regulation in models of MS. Brains from progressive MS and non-MS patients, as well as cultured human oligodendrocytes were examined by transcriptomic and morphological methods. Next generation transcriptional sequencing of progressive MS compared to non-MS patients' normal appearing white matter (NAWM) showed induction of caspase-1 as well as other inflammasome-associated genes with concurrent suppression of neuron-specific genes. Oligodendrocytes exposed to TNFα exhibited upregulation of caspase-1 with myelin gene suppression in a cell differentiation state-dependent manner. Brains from cuprizone-exposed mice treated by intranasal delivery of the caspase-1 inhibitor, VX-765 or its vehicle, were investigated in morphological and molecular studies, as well as by fluorodeoxyglucose-positron emission tomography (FDG-PET) imaging. Cuprizone exposure resulted in BMC and caspase-1 activation accompanied by demyelination and axonal injury, which was abrogated by intranasal VX-765 treatment. FDG-PET imaging revealed suppressed glucose metabolism in the thalamus, hippocampus and cortex of cuprizone-exposed mice that was restored with VX-765 treatment. These studies highlight the caspase-1 dependent interactions between inflammation, demyelination, and glucose metabolism in progressive MS and associated models. Intranasal delivery of an anti-caspase-1 therapy represents a promising therapeutic approach for progressive MS and other neuro-inflammatory diseases.

[The role of mitochondria in pathological mechanisms of innate immunity in multiple]

The review discusses the role of mitochondria in multiple sclerosis (MS). Previously, damage to the mitochondria was regarded as a manifestation of secondary damage to axons and neurons, i.e. as a marker of neurodenegation. Recently, the role of mitochondria in the early stages of MS development, when they could participate in the activation of innate immunity and trigger activation of autoimmune responses of acquired immunity, has been increasingly discussed. The role of polymorphism mitochondrial DNA changes in MS is discussed.

The role of inflammasomes in multiple sclerosis

Multiple sclerosis (MS) is considered as an inflammatory autoimmune disease of the central nervous system (CNS), with a complex and heterogenic etiology. However, the involvement of inflammation in its pathophysiology is well documented and current therapies for MS are mainly immunosuppressive drugs. Although the available drugs reduce new lesions and relapses, their long-term outcome is not completely satisfactory. Inflammasomes are multimeric protein complexes that play a critical role in the inflammatory process. Several lines of evidence suggest an association between inflammasome activation and MS. In this paper, we have reviewed current studies that demonstrate the involvement of inflammasomes in MS development, in both animal model and MS patients. Furthermore, prior studies about the effect of inflammasome inhibitor drugs on development and progression of MS are discussed.

Functional characterization of NLRX1 in rabbit during enterohemorrhagic Escherichia coli infection

Nucleotide oligomerization domain (NOD) like receptor X1 (NLRX1) is a member of pattern recognition receptor, which has been linked to viral response, cancer, and inflammatory diseases. In this study, rabbit NLRX1 (rNLRX1) was firstly cloned from RK-13 cells, which protein contained a NACHT domain and seven LRRs. rNLRX1 was widely expressed in tissues of rabbits, and highly increased in liver, spleen, kidney, and colon after infected with enterohemorrhagic Escherichia coli (EHEC). Overexpression of rNLRX1 negatively regulated NF-κB signaling, and impaired the expression of pro-inflammatory cytokines and defensins. Moreover, deficient of rNLRX1 in RK-13 cells was performed to investigate the possible roles of rNLRX1. Upon EHEC stimulation, knockdown of rNLRX1 markedly enhanced NF-κB activation and downstream responsive cytokines (IL1β and TNFα) and β-defensins (DEFB114, DEFB124, and DEFB125). Furthermore, overexpression of rNLRX1 promoted the proliferation of EHEC, whereas knockdown of rNLRX1 inhibited its growth. Our study identified that rNLRX1 acts as a negative regulatory in anti-microbial responses after EHEC infection.

DJ-1 exerts anti-inflammatory effects and regulates NLRX1-TRAF6 via SHP-1 in stroke

Background

Acute inflammation induced by reactive astrocytes after cerebral ischemia/reperfusion (I/R) injury is important for protecting the resultant lesion. Our previous study demonstrated that DJ-1 is abundantly expressed in reactive astrocytes after cerebral I/R injury. Here, we show that DJ-1 negatively regulates the inflammatory response by facilitating the interaction between SHP-1 and TRAF6, thereby inducing the dissociation of NLRX1 from TRAF6.

Methods

We used oxygen-glucose deprivation/reoxygenation (OGD/R) in vitro in primary astrocyte cultures and transient middle cerebral artery occlusion/reperfusion (MCAO/R) in vivo to mimic I/R insult.

Results

The inhibition of DJ-1 expression increased the expression of the inflammatory cytokines TNF-α, IL-1β, and IL-6. DJ-1 knockdown facilitated the interaction between NLRX1 and TRAF6. However, the loss of DJ-1 attenuated the interaction between SHP-1 and TRAF6. In subsequent experiments, a SHP-1 inhibitor altered the interaction between SHP-1 and TRAF6 and facilitated the interaction between NLRX1 and TRAF6 in DJ-1-overexpressing astrocytes.

Conclusion

These findings suggest that DJ-1 exerts an SHP-1-dependent anti-inflammatory effect and induces the dissociation of NLRX1 from TRAF6 during cerebral I/R injury. Thus, DJ-1 may be an efficacious therapeutic target for the treatment of I/R injury.

Inflammation in acquired hydrocephalus: pathogenic mechanisms and therapeutic targets

Hydrocephalus is the most common neurosurgical disorder worldwide and is characterized by enlargement of the cerebrospinal fluid (CSF)-filled brain ventricles resulting from failed CSF homeostasis. Since the 1840s, physicians have observed inflammation in the brain and the CSF spaces in both posthaemorrhagic hydrocephalus (PHH) and postinfectious hydrocephalus (PIH). Reparative inflammation is an important protective response that eliminates foreign organisms, damaged cells and physical irritants; however, inappropriately triggered or sustained inflammation can respectively initiate or propagate disease. Recent data have begun to uncover the molecular mechanisms by which inflammation - driven by Toll-like receptor 4-regulated cytokines, immune cells and signalling pathways - contributes to the pathogenesis of hydrocephalus. We propose that therapeutic approaches that target inflammatory mediators in both PHH and PIH could address the multiple drivers of disease, including choroid plexus CSF hypersecretion, ependymal denudation, and damage and scarring of intraventricular and parenchymal (glia-lymphatic) CSF pathways. Here, we review the evidence for a prominent role of inflammation in the pathogenic mechanism of PHH and PIH and highlight promising targets for therapeutic intervention. Focusing research efforts on inflammation could shift our view of hydrocephalus from that of a lifelong neurosurgical disorder to that of a preventable neuroinflammatory condition.

Pharmacological inhibition of soluble epoxide hydrolase attenuates chronic experimental autoimmune encephalomyelitis by modulating inflammatory and anti-inflammatory pathways in an inflammasome-dependent and -independent manner

We aimed to determine the effect of soluble epoxide hydrolase (sEH) inhibition on chronic experimental autoimmune encephalomyelitis (EAE), a murine model of multiple sclerosis (MS), associated with changes in inflammasome-dependent and -independent inflammatory and anti-inflammatory pathways in the CNS of mice. C57BL/6 mice were used to induce chronic EAE by using an injection of MOG_35-55 peptide/PT. Animals were observed daily and scored for EAE signs for 25 days after immunization. Following the induction of EAE, the scores were increased after 9 days and reached peak value as determined by ≥ 2 or ≤ 3 with 8% mortality rate on day 17. On day 17, mice were administered daily PBS, DMSO, or TPPU (a potent sEH inhibitor) (1, 3, or 10 mg/kg) until the end of the study. TPPU only at 3 mg/kg dose decreased the AUC values calculated from EAE scores obtained during the disease compared to EAE and vehicle control groups. On day 25, TPPU also caused an increase in the PPARα/β/γ and NLRC3 proteins and a decrease in the proteins of TLR4, MyD88, NF-κB p65, p-NF-κB p65, iNOS/nNOS, COX-2, NLRC4, ASC, caspase-1 p20, IL-1β, caspase-11 p20, NOX subunits (gp91^phox and p47^phox), and nitrotyrosine in addition to 14,15-DHET and IL-1β levels compared to EAE and vehicle control groups. Our findings suggest that pharmacological inhibition of sEH attenuates chronic EAE likely because of enhanced levels of anti-inflammatory EETs in addition to PPARα/β/γ and NLRC3 expression associated with suppressed inflammatory TLR4/MyD88/NF-κB signalling pathway, NLRC4/ASC/pro-caspase-1 inflammasome, caspase-11 inflammasome, and NOX activity that are responsible for inflammatory mediator formation in the CNS of mice.

Microglial NLRP3 inflammasome activation in multiple sclerosis

Multiple sclerosis (MS) is a chronic, autoimmune and neuroinflammatory disease of the central nervous system (CNS) mediated by autoreactive T cells directed against myelin antigens. Although the crucial role of adaptive immunity is well established in MS, the contribution of innate immunity has only recently been appreciated. Microglia are the main innate immune cells of the CNS. Similar to other myeloid cells, microglia recognize both exogenous and host-derived endogenous danger signals through pattern recognition receptors (PRRs) localized on their cell surface such as Toll Like receptor 4, or in the cytosol such as NLRP3. The second one is the sensor protein of the multi-molecular NLRP3 inflammasome complex in activated microglia that promotes the maturation and secretion of proinflammatory cytokines, interleukin-1β and interleukin-18. Overactivation of microglia and aberrant activation of the NLRP3 inflammasome have been implicated in the pathogenesis of MS. Indeed, experimental data, together with post-mortem and clinical studies have revealed an increased expression of NLRP3 inflammasome complex elements in microglia and other immune cells. In this review, we focus on microglial NLRP3 inflammasome activation in MS. First, we overview the basic knowledge about MS, microglia and the NLRP3 inflammasome. Then, we summarize studies about microglial NLRP3 inflammasome activation in MS and its animal models. We also highlight experimental therapeutic approaches that target different steps of NLRP inflammasome activation. Finally, we discuss future research avenues and new methods in this rapidly evolving area.

NLRX1 Is a Multifaceted and Enigmatic Regulator of Immune System Function

Over the last decade, significant progress has been achieved in defining mechanisms underlying NLR regulation of immune system function. However, several NLR family members continue to defy our best attempts at characterization and routinely exhibit confounding data. This is particularly true for NLR family members that regulate signaling associated with the activation of other pattern recognition receptors. NLRX1 is a member of this NLR sub-group and acts as an enigmatic regulator of immune system function. NLRX1 has been shown to negatively regulate type-I interferon, attenuate pro-inflammatory NF-κB signaling, promote reactive oxygen species production, and modulate autophagy, cell death, and proliferation. However, the mechanism/s associated with NLRX1 modulation of these pathways is not fully understood and there are inconsistencies within the field. Likewise, it is highly likely that the full repertoire of biological functions impacted by NLRX1 are yet to be defined. Recent mouse studies have shown that NLRX1 significantly impacts a multitude of diseases, including cancer, virus infection, osteoarthritis, traumatic brain injury, and inflammatory bowel disease. Thus, it is essential that the underlying mechanism associated with NLRX1 function in each of these diseases be robustly defined. Here, we summarize the current progress in understanding mechanisms associated with NLRX1 function. We also offer insight into both unique and overlapping mechanisms regulated by NLRX1 that likely contribute to disease pathobiology. Ultimately, we believe that an improved understanding of NLRX1 will result in better defined mechanisms associated with immune system attenuation and the resolution of inflammation in a myriad of diseases.