Transduction of inflammation from peripheral immune cells to the hippocampus induces neuronal hyperexcitability mediated by Caspase-1 activation

Dexamethasone induces developmental axon damage in the offspring hippocampus by activating miR-210-3p/miR-362-5p to target the aberrant expression of Sonic Hedgehog

Given the extensive application of dexamethasone in both clinical settings and the livestock industry, human exposure to this drug can occur through various sources and pathways. Prior research has indicated that prenatal exposure to dexamethasone (PDE) heightens the risk of cognitive and emotional disorders in offspring. Axonal development impairment is a frequent pathological underpinning for neuronal dysfunction in these disorders, yet it remains unclear if it plays a role in the neural damage induced by PDE in the offspring. Through RNA-seq and bioinformatics analysis, we found that various signaling pathways related to nervous system development, including axonal development, were altered in the hippocampus of PDE offspring. Among them, the Sonic Hedgehog (SHH) signaling pathway was the most significantly altered and crucial for axonal development. By using miRNA-seq and targeting miRNAs and glucocorticoid receptor (GR) expression, we identified miR-210-3p and miR-362-5p, which can target and suppress SHH expression. Their abnormal high expression was associated with GR activation in PDE fetal rats. Further testing of PDE offspring rats and infant peripheral blood samples exposed to dexamethasone in utero showed that SHH expression was significantly decreased in peripheral blood mononuclear cells (PBMCs) and was positively correlated with SHH expression in the hippocampus and the expression of the axonal development marker growth-associated protein-43. In summary, PDE-induced hippocampal GR-miR-210-3p/miR-362-5p-SHH signaling axis changes lead to axonal developmental damage. SHH expression in PBMCs may reflect axonal developmental damage in PDE offspring and could serve as a warning marker for fetal axonal developmental damage.

5-Hydroxymethylfurfural Ameliorates Allergic Inflammation in HMC-1 Cells by Inactivating NF-κB and MAPK Signaling Pathways

Allergic inflammation is the foundation of multiple allergic disorders, such as allergic rhinitis and asthma. Mast cells are effector cells that initiate inflammatory response. 5-hydroxymethylfurfural (5-HMF), a furfural compound, is the heat-processed product of various fruit, foods, drinks, as well as some Chinese herbal medicines. 5-HMF was previously reported to inhibit mast cell activation. Our study aimed to explore the functions of 5-HMF in both phorbol 12-mystate 13-acetate (PMA) plus calcium ionophore (A23187)-induced allergic inflammation in human mast cell line HMC-1 and ovalbumin (OVA)-induced asthma mouse models. HMC-1 cells were pretreated with 5-HMF and then stimulated by PMA+A23187. The cytotoxicity of 5-HMF on HMC-1 cells was evaluated by MTT assay. Histamine content in cell supernatants was measured by the o-phthaldialdehyde spectrofluorometric procedure. Intracellular calcium was determined using the fluorescent dye Fura-2AM. The production and expression of pro-inflammatory cytokines were detected by ELISA and RT-qPCR. Caspase-1 colorimetric assay was employed to examine the enzymatic activity of caspase-1. Asthma mouse models were induced by OVA sensitization. The bronchoalveolar lavage fluid (BALF) and blood samples were collected for the detection of total and differential cell count as well as aspartate aminotransferase (AST), alanine aminotransferase (ALT), OVA-immunoglobulin E (OVA-IgE), OVA-immunoglobulin G1 (OVA-IgG1), and pro-inflammatory cytokine levels. The left lung of mouse was dissected for histopathological examination by hematoxylin and eosin (H&E) staining. The protein expression of pro-caspase-1 and the phosphorylation of NF-κB and MAPK pathway-associated molecules were assessed by Western blotting. Our findings revealed that 5-HMF efficiently suppressed the PMA+A23187-induced enhancement in histamine production and intracellular calcium in HMC-1 cells. Pro-inflammatory cytokine production and expression in HMC-1 cells were elevated after PMA plus A23187 stimulation, which, however, were inhibited by pretreatment of 5-HMF. Additionally, 5-HMF suppressed the activity of caspase-1 and the phosphorylation of NF-κB and MAPK-associated molecules including p65 NF-κB, p38 MAPK, ERK, and JNK in HMC-1 cells. In vivo experiments demonstrated that 5-HMF treatment reduced the lung/body weight index and total and differential (macrophages, neutrophils, lymphocytes, and eosinophils) cell counts in BALF of asthmatic mice, but exerted no influence on serum AST and ALT levels. Besides, 5-HMF reduced serum OVA-IgE and OVA-IgG1 levels, mitigated lung inflammation, and inhibited the NF-κB and MAPK signaling pathways in asthma mouse models. 5-HMF mitigates allergic inflammation in asthma by inactivating caspase-1 and NF-κB and MAPK signaling pathways.

Decoupling the mutual promotion of inflammation and oxidative stress mitigates cognitive decline and depression-like behavior in rmTBI mice by promoting myelin renewal and neuronal survival

BACKGROUND

Repetitive mild traumatic brain injury (rmTBI) can lead to somatic, emotional, and cognitive symptoms that persist for years after the initial injury. Although the ability of various treatments to promote recovery after rmTBI has been explored, the optimal time window for early intervention after rmTBI is unclear. Previous research has shown that hydrogen-rich water (HRW) can diffuse through the blood-brain - barrier, attenuate local oxidative stress, and reduce neuronal apoptosis in patients with severe traumatic brain injury. However, research on the effect of HRW on rmTBI is scarce.

AIMS

The objectives of this study were to explore the following changes after rmTBI and HRW treatment: (i) temporal changes in inflammasome activation and oxidative stress-related protein expression through immunoblotting, (ii) temporal changes in neuron/myelin-related metabolite concentrations in vivo through magnetic resonance spectroscopy, (iii) myelin structural changes in late-stage rmTBI via immunofluorescence, and (iv) postinjury anxiety/depression-like behaviors and spatial learning and memory impairment.

RESULTS

NLRP-3 expression in the rmTBI group was elevated at 7 and 14 DPI, and inflammasome marker levels returned to normal at 30 DPI. Oxidative stress persisted throughout the first month postinjury. HRW replacement significantly decreased Nrf2 expression in the prefrontal cortex and hippocampal CA2 region at 14 and 30 DPI, respectively. Edema and local gliosis in the hippocampus and restricted diffusion in the thalamus were observed on MR-ADC images. The tCho/tCr ratio in the rmTBI group was elevated, and the tNAA/tCr ratio was decreased at 30 DPI. Compared with the mice in the other groups, the mice in the rmTBI group spent more time exploring the open arms in the elevated plus maze (P < 0.05) and were more active in the maze (longer total distance traveled). In the sucrose preference test, the rmTBI group exhibited anhedonia. In the Morris water maze test, the latency to find the hidden platform in the rmTBI group was longer than that in the sham and HRW groups (P < 0.05).

CONCLUSION

Early intervention with HRW can attenuate inflammasome assembly and reduce oxidative stress after rmTBI. These changes may restore local oligodendrocyte function, promote myelin repair, prevent axonal damage and neuronal apoptosis, and alleviate depression-like behavior and cognitive impairment.

TRP Ion Channels in Immune Cells and Their Implications for Inflammation

The transient receptor potential (TRP) ion channels act as cellular sensors and mediate a plethora of physiological processes, including somatosensation, proliferation, apoptosis, and metabolism. Under specific conditions, certain TRP channels are involved in inflammation and immune responses. Thus, focusing on the role of TRPs in immune system cells may contribute to resolving inflammation. In this review, we discuss the distribution of five subfamilies of mammalian TRP ion channels in immune system cells and how these ion channels function in inflammatory mechanisms. This review provides an overview of the current understanding of TRP ion channels in mediating inflammation and may offer potential avenues for therapeutic intervention.

Differentiation of Neurons, Astrocytes, Oligodendrocytes and Microglia From Human Induced Pluripotent Stem Cells to Form Neural Tissue-On-Chip: A Neuroinflammation Model to Evaluate the Therapeutic Potential of Extracellular Vesicles Derived from Mesenchymal Stem Cells

Advances in stem cell (SC) technology allow the generation of cellular models that recapitulate the histological, molecular and physiological properties of humanized in vitro three dimensional (3D) models, as well as production of cell-derived therapeutics such as extracellular vesicles (EVs). Improvements in organ-on-chip platforms and human induced pluripotent stem cells (hiPSCs) derived neural/glial cells provide unprecedented systems for studying 3D personalized neural tissue modeling with easy setup and fast output. Here, we highlight the key points in differentiation procedures for neurons, astrocytes, oligodendrocytes and microglia from single origin hiPSCs. Additionally, we present a well-defined humanized neural tissue-on-chip model composed of differentiated cells with the same genetic backgrounds, as well as the therapeutic potential of bone marrow mesenchymal stem cells (BMSCs)-derived extracellular vesicles to propose a novel treatment for neuroinflammation derived diseases. Around 100 nm CD9 + EVs promote a more anti-inflammatory and pro-remodeling of cell-cell interaction cytokine responses on tumor necrosis factor-α (TNF-α) induced neuroinflammation in neural tissue-on-chip model which is ideal for modeling authentic neural-glial patho-physiology.

The NLRP3 Inflammasome in Neurodegenerative Disorders: Insights from Epileptic Models

Neuroinflammation represents a dynamic process of defense and protection against the harmful action of infectious agents or other detrimental stimuli in the central nervous system (CNS). However, the uncontrolled regulation of this physiological process is strongly associated with serious dysfunctional neuronal issues linked to the progression of CNS disorders. Moreover, it has been widely demonstrated that neuroinflammation is linked to epilepsy, one of the most prevalent and serious brain disorders worldwide. Indeed, NLRP3, one of the most well-studied inflammasomes, is involved in the generation of epileptic seizures, events that characterize this pathological condition. In this context, several pieces of evidence have shown that the NLRP3 inflammasome plays a central role in the pathophysiology of mesial temporal lobe epilepsy (mTLE). Based on an extensive review of the literature on the role of NLRP3-dependent inflammation in epilepsy, in this review we discuss our current understanding of the connection between NLRP3 inflammasome activation and progressive neurodegeneration in epilepsy. The goal of the review is to cover as many of the various known epilepsy models as possible, providing a broad overview of the current literature. Lastly, we also propose some of the present therapeutic strategies targeting NLRP3, aiming to provide potential insights for future studies.

Complement C1q drives microglia-dependent synaptic loss and cognitive impairments in a mouse model of lipopolysaccharide-induced neuroinflammation

Activated microglia and subsequent release of pro-inflammatory cytokines result in neuroinflammatory status which further damage neurological function including cognitive impairments in various neurological conditions. However, the underlying molecular mechanisms during these pathological processing remain unknown. In the current study, mice received intraperitoneal administrations of LPS (0.5 mg/kg, daily, Escherichia coli O55:B5) for seven consecutive days and their different cohorts were used for behavioral assessment with open field, Y maze, and novel object recognition test or for electrophysiology recordings of mEPSC, LFP or LTP in in vivo or ex vivo preparation. The hippocampus from some cohorts were harvested for immunostaining or Western blotting of c1q, Iba-1, CD68, PSD95 and dendritic spine density or for transcriptome and proteomics analysis. Repeated LPS injections induced an up-regulation of complement system protein c1q and distinct microglial phenotype with an enrichment of the complement-phagosome pathway. Microglial synaptic engulfment and profound synaptic loss were found. These pathological changes were accompanied with the significantly decreased excitatory synaptic transmission, disturbed theta oscillations, impaired hippocampal long-term potentiation, and cognitive impairments. Notably, neutralization of c1q signaling robustly prevented these changes. Collectively, our data provide evidence that activated microglia and complement cascade c1q signaling in the hippocampus may account for synaptic loss and cognitive impairments in a mouse model of neuroinflammation induced by repeated LPS injections. Our work implicates that complement system may be a therapeutic target for developing therapies to prevent or treat cognitive disorders related to neuroinflammation or other disease conditions including neurodegenerative disease per se.

Exergame and/or conventional training-induced neuroplasticity and cognitive improvement by engaging epigenetic and inflammatory modulation in elderly women: A randomized clinical trial

OBJECTIVE

To evaluate the acute and long-term impact of exergaming (EXE) and conventional therapy (CON) in the peripheral levels of brain-derived neurotrophic factor (BDNF), inflammatory markers (interleukin [IL]-1b, IL-6, IL-8, and tumor necrosis factor-alpha [TNF-α]) and epigenetic mechanisms (global histone H3 and H4 acetylation levels in mononuclear cells) of healthy elderly women. We also evaluated the effect of intervention on cognitive performance in these individuals.

METHODS

Twenty-two elderly women were randomly assigned into two groups: EXE (n = 12) and CON (n = 10). Both interventions were performed twice a week for 6 weeks (12 sessions). Blood samples were obtained before intervention, after the first session, and 1 hour after the last session. Cognitive performance was evaluated before and after intervention.

RESULTS

Both EXE and CON interventions ameliorated cognitive performance, improved inflammatory profile, enhanced BDNF levels, and induced histone H4 and H3 hyperacetylation status in elderly women.

CONCLUSION

Our study demonstrated that the proposed interventions can be considered important strategies capable of promoting cognitive improvement in healthy elderly women. The acetylation status of histones and inflammatory cytokines are possible molecular mechanisms that mediate this beneficial response, being distinctly modulated by acute and long-term exposure.

Sudden cardiac deaths have higher proportion of left stellate ganglionitis

One of the hypothesized mechanisms of sudden cardiac death in humans is an arrhythmia precipitated by increased sympathetic outflow to a compromised heart. The stellate ganglia provide the main sympathetic innervation to the heart, where the left stellate ganglion appears to play a role in arrhythmogenesis. Case reports of sudden cardiac death have described left stellate ganglion inflammation but no larger studies have been performed. Thus, we have specifically assessed whether the left stellate ganglion was inflamed in those dying from sudden cardiac death versus other causes of death. Thirty-one left stellate ganglia were resected from cadavers diagnosed with sudden cardiac deaths and compared with 18 ganglia from cadavers diagnosed with non-sudden cardiac deaths. Ganglia were stained with hematoxylin and eosin and lymphocytic aggregates compared. The proportion of left stellate ganglion inflammation (77%) was significantly higher in deaths from sudden cardiac deaths than non-sudden cardiac deaths (33%). This study provides information on a previously recognized, but understudied, structure that may help understand sudden cardiac death. We found high prevalence of stellate ganglion inflammation and propose that this may trigger sympathetic storms.