MicroRNA-155 Promotes Heat Stress-Induced Inflammation via Targeting Liver X Receptor α in Microglia

Liver X receptor α contribution to neuroinflammation and glial cells activation induced by MPTP: Implications for Parkinson's disease

Parkinson's disease (PD) is the second most common neurodegenerative disorder whose etiology remains unknown. The immune system has been implicated in hallmarks of PD including aggregation of α-synuclein and death of dopaminergic neurons in the substantia nigra. As a core regulator of immune response and inflammation, liver X receptors (LXRs) have been shown to have protective effects in a 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced mouse model of PD. With two isoforms of LXRs (LXRα and LXRβ) expressed in the brain, their roles and distributions in this tissue remain largely unexplored. Here, we used MPTP to mimic symptoms and biomedical changes seen in PD in LXRα-/- and wild-type mice to investigate the role of LXRα in the etiology and progression of PD. We found that MPTP is unable to induce motor deficits, anxiety-like behavior in LXRα-/- mice, which has been seen in WT mice. Gene ontology analysis of RNA sequencing revealed that knockout of LXRα led to enrichment of the process, including immune response and inflammation in the midbrain. In addition, MPTP did not lead to dopaminergic neuron death in the striatum and substantia nigra in LXRα-/- mice, the basal GFAP protein level, and pro-inflammatory cytokines were elevated in LXRα-/- mice. Lastly, the microglia activation and astrogliosis caused by MPTP intoxication we found in WT mice were abolished in LXRα-/- mice. To sum up, we conclude that LXRα is a critical regulator in MPTP intoxication and may play a unique role in astrogliosis seen in the neuroinflammation of PD.

Epigenetics in thyroid cancer: a bibliometric analysis

Background

Epigenetics, which involves regulatory modifications that do not alter the DNA sequence itself, is crucial in the development and progression of thyroid cancer. This study aims to provide a comprehensive analysis of the epigenetic research landscape in thyroid cancer, highlighting current trends, major research areas, and potential future directions.

Methods

A bibliometric analysis was performed using data from the Web of Science Core Collection (WOSCC) up to 1 November 2023. Analytical tools such as VOSviewer, CiteSpace, and the R package 'bibliometrix' were employed for comprehensive data analysis and visualization. This process identified principal research themes, along with influential authors, institutions, and countries contributing to the field.

Results

The analysis reveals a marked increase in thyroid cancer epigenetics research over the past two decades. Emergent key themes include the exploration of molecular mechanisms and biomarkers, various subtypes of thyroid cancer, implications for therapeutic interventions, advancements in technologies and methodologies, and the scope of translational research. Research hotspots within these themes highlight intensive areas of study and the potential for significant breakthroughs.

Conclusion

This study presents an in-depth overview of the current state of epigenetics in thyroid cancer research. It underscores the potential of epigenetic strategies as viable therapeutic options and provides valuable insights for researchers and clinicians in advancing the understanding and treatment of this complex disease. Future research is vital to fully leverage the therapeutic possibilities offered by epigenetics in the management of thyroid cancer.

Heat stroke: Pathogenesis, diagnosis, and current treatment

Recently, the incidence of heat-related illnesses has exhibited a steadily upward trend, which is closely associated with several environmental factors such as climate change and air pollution. The progression of heat-related illnesses is a continuous process and can progress to the terminal period when it transforms into heat stroke, the most severe form. Heat stroke is markedly by a core body temperature above 40°C and central nervous system dysfunction. Current knowledge suggests that the pathogenesis of heat stroke is complex and varied, including inflammatory response, oxidative stress, cell death, and coagulation dysfunction. This review consolidated recent research progress on the pathophysiology and pathogenesis of heat stroke, with a focus on the related molecular mechanisms. In addition, we reviewed common strategies and sorted out the drugs in various preclinical stages for heat stroke, aiming to offer a comprehensive research roadmap for more in-depth researches into the mechanisms of heat stroke and the reduction in the mortality of heat stroke in the future.

Silencing miR-155-5p alleviates hippocampal damage in kainic acid-induced epileptic rats via the Dusp14/MAPK pathway

Epilepsy with recurrent seizures is characterized by neuronal damage and glial proliferation induced by brain inflammation. Recurrent seizures can lead to changes in the microRNA (miRNA) spectrum, significantly influencing the inflammatory response of microglia. MiR-155-5p, as a pro-inflammatory miRNA, is increased in the epileptic brain. However, its specific role in acute seizures remains unknown. The study aimed to develop a new strategy for treating epilepsy by investigating how silencing of miR-155-5p initiated its anticonvulsive mechanism. The level of miR-155-5p was up-regulated in the hippocampus of epileptic immature rats induced by kainic acid (KA). The use of antago-miR-155-5p exerted significant beneficial effects on the seizure scores, brain discharges and cognition in immature rats following KA-induced epilepsy. Antago-miR-155-5p also inhibited neuron damage and microglial activation. Moreover, the silencing of miR-155-5p significantly inhibited the Dual-specificity phosphatase 14 (Dusp14)/ mitogen-activated protein kinase (MAPK) axis in vivo. MiR-155-5p interacted with dusp14 to regulate MAPK signaling way expression, verified by a dual-luciferase reporter assay. The results suggested that the silencing of miR-155-5p might reduce hippocampal damage in epileptic immature rats induced by KA via Dusp14/MAPK signaling way. This implied that miR-155-5p could serve as a therapeutic tool to prevent the development of epilepsy.

Small Differences and Big Changes: The Many Variables of MicroRNA Expression and Function in the Brain

MicroRNAs are emerging as crucial regulators within the complex, dynamic environment of the synapse, and they offer a promising new avenue for the treatment of neurological disease. These small noncoding RNAs modify gene expression in several ways, including posttranscriptional modulation via binding to complementary and semicomplementary sites on target mRNAs. This rapid, finely tuned regulation of gene expression is essential to meet the dynamic demands of the synapse. Here, we provide a detailed review of the multifaceted world of synaptic microRNA regulation. We discuss the many mechanisms by which microRNAs regulate gene expression at the synapse, particularly in the context of neuronal plasticity. We also describe the various factors, such as age, sex, and neurological disease, that can influence microRNA expression and activity in neurons. In summary, microRNAs play a crucial role in the intricate and quickly changing functional requirements of the synapse, and context is essential in the study of microRNAs and their potential therapeutic applications.

Exploring the molecular mechanisms of MSC-derived exosomes in Alzheimer's disease: Autophagy, insulin and the PI3K/Akt/mTOR signaling pathway

Alzheimer's disease (AD) is a devastating neurological condition characterized by cognitive decline, motor coordination impairment, and amyloid plaque accumulation. The underlying molecular mechanisms involve oxidative stress, inflammation, and neuronal degeneration. This study aimed to investigate the therapeutic effects of mesenchymal stem cell-derived exosomes (MSC-exos) on AD and explore the molecular pathways involved, including the PI3K/Akt/mTOR axis, autophagy, and neuroinflammation. To assess the potential of MSC-exos for the treatment of AD, rats were treated with AlCl3 (17 mg/kg/once/day) for 8 weeks, followed by the administration of an autophagy activator (rapamycin), or MSC-exos with or without an autophagy inhibitor (3-methyladenin; 3-MA+ chloroquine) for 4 weeks. Memory impairment was tested, and brain tissues were collected for gene expression analyses, western blotting, histological studies, immunohistochemistry, and transmission electron microscopy. Remarkably, the administration of MSC-exos improved memory performance in AD rats and reduced the accumulation of amyloid-beta (Aβ) plaques and tau phosphorylation. Furthermore, MSC-exos promoted neurogenesis, enhanced synaptic function, and mitigated astrogliosis in AD brain tissues. These beneficial effects were associated with the modulation of autophagy and the PI3K/Akt/mTOR signalling pathway, as well as the inhibition of neuroinflammation. Additionally, MSC-exos were found to regulate specific microRNAs, including miRNA-21, miRNA-155, miRNA-17-5p, and miRNA-126-3p, further supporting their therapeutic potential. Histopathological and bioinformatic analyses confirmed these findings. This study provides compelling evidence that MSC-exos hold promise as a potential therapeutic approach for AD. By modulating the PI3K/Akt/mTOR axis, autophagy, and neuroinflammation, MSC-exos have the potential to improve memory, reduce Aβ accumulation, enhance neurogenesis, and mitigate astrogliosis. These findings shed light on the therapeutic potential of MSC-exos and highlight their role in combating AD.

Exploring candidate genes for heat tolerance in ovine through liver gene expression

Thermotolerance has become an essential factor in the prevention of the adverse effects of heat stress, but it varies among animals. Identifying genes related to heat adaptability traits is important for improving thermotolerance and for selecting more productive animals in hot environments. The primary objective of this research was to find candidate genes in the liver that play a crucial role in the heat stress response of Santa Ines sheep, which exhibit varying levels of heat tolerance. To achieve this goal, 80 sheep were selected based on their thermotolerance and placed in a climate chamber for 10 days, during which the average temperature was maintained at 36 °C from 10 a.m. to 4 p.m. and 28 °C from 4 p.m. to 10 a.m. A subset of 14 extreme animals, with seven thermotolerant and seven non-thermotolerant animals based on heat loss (rectal temperature), were selected for liver sampling. RNA sequencing and differential gene expression analysis were performed. Thermotolerant sheep showed higher expression of genes GPx3, RGS6, GPAT3, VLDLR, LOC101108817, and EVC. These genes were mainly related to the Hedgehog signaling pathway, glutathione metabolism, glycerolipid metabolism, and thyroid hormone synthesis. These enhanced pathways in thermotolerant animals could potentially mitigate the negative effects of heat stress, conferring greater heat resistance.

Complanatuside A improves functional recovery after spinal cord injury through inhibiting JNK signaling-mediated microglial activation

BACKGROUND AND AIMS

Complanatuside A (ComA) is a flavonoid-rich compound in Astragalus membranaceus that has anti-inflammatory and neuroprotective effects. In this study, we focused on the effect of ComA on spinal cord injury (SCI) in mice and explored its possible mechanisms.

METHODS

The SCI model was constructed using C57BL/6J mice, and the effect of ComA on motor function recovery in SCI mice was evaluated through the BMS (Basso Mouse Scale) and footprint test. The histological effects of ComA on SCI mice were evaluated by hematoxylin-eosin (H&E) staining, Luxol-fast blue (LFB) staining, and Nissl staining. In both in vivo and in vitro experiments, we detected the activation of microglia and the release of inflammatory factors through molecular experiments. Immunofluorescence and Western blotting confirmed that ComA can prevent neuronal apoptosis caused by activated microglia through the c-Jun N-terminal kinase (JNK) pathway.

RESULTS

Our research results confirm that ComA can improve motor function in mice after SCI. Our in vitro results indicate that ComA can inhibit the activation of BV2 cells and the release of proinflammatory mediators. In addition, ComA can prevent neuronal cell apoptosis caused by activated BV2 cells. Finally, we found that ComA works through the JNK signaling pathway.

CONCLUSIONS

ComA can accelerate the restoration of motor function in mice after SCI, possibly by reducing neuronal apoptosis via inhibition of JNK-related signaling pathways, a reduction in microglial activation, and inhibition of inflammatory factor release. Our data indicate that ComA is a promising drug candidate for improving functional recovery in patients with SCI.

Xuebijing Injection Attenuates Heat Stroke-Induced Brain Injury through Oxidative Stress Blockage and Parthanatos Modulation via PARP-1/AIF Signaling

Heat stroke (HS) is a potentially fatal acute condition caused by an interplay of complex events including inflammation, endothelial injury, and coagulation abnormalities that make its pharmacological treatment a challenging problem. The traditional Chinese medicine Xuebijing injection (XBJ) has been shown to reduce inflammatory responses and prevent organ injuries in HS-induced mice. However, the underlying mechanism of XBJ in HS-induced brain injury remains unclear. In this study, HS-induced rat models and cell models were established to elucidate the effects and underlying mechanisms of XBJ injection on HS-induced brain injury in vivo and in vitro. The results revealed that XBJ injection improved the survival outcome of HS rats and attenuated HS-induced brain injury in a concentration-dependent manner. Subsequently, the reduction in viability and proliferation of neurons induced by HS were reversed by XBJ treatment, while the HS-induced increased ROS levels and neuron death were also inhibited by XBJ injection. Mechanistically, HS activated PARP-1/AIF signaling in vitro and in vivo, inducing the translocation of AIF from the cytoplasm to the nucleus, leading to PARP-1-dependent cell death of neurons. Additionally, we compared XBJ injection effects in young and old age rats. Results showed that XBJ also provided protective effects in HS-induced brain injury in aging rats; however, the treatment efficacy of XBJ injection at the same concentration was more significant in the young age rats. In conclusion, XBJ injection attenuates HS-induced brain injury by inhibiting oxidative stress and Parthanatos via the PARP-1/AIF signaling, which might provide a novel therapeutic strategy for HS treatment.

Emerging Insights into Liver X Receptor α in the Tumorigenesis and Therapeutics of Human Cancers

Liver X receptor α (LXRα), a member of the nuclear receptor superfamily, is identified as a protein activated by ligands that interacts with the promoters of specific genes. It regulates cholesterol, bile acid, and lipid metabolism in normal physiological processes, and it participates in the development of some related diseases. However, many studies have demonstrated that LXRα is also involved in regulating numerous human malignancies. Aberrant LXRα expression is emerging as a fundamental and pivotal factor in cancer cell proliferation, invasion, apoptosis, and metastasis. Herein, we outline the expression levels of LXRα between tumor tissues and normal tissues via the Oncomine and Tumor Immune Estimation Resource (TIMER) 2.0 databases; summarize emerging insights into the roles of LXRα in the development, progression, and treatment of different human cancers and their diversified mechanisms; and highlight that LXRα can be a biomarker and therapeutic target in diverse cancers.

Shear stress induces monocyte/macrophage-mediated inflammation by upregulating cell-surface expression of heat shock proteins

The loss of endothelial cells is associated with the accumulation of monocytes/macrophages underneath the surface of the arteries, where cells are prone to mechanical stimulation, such as shear stress. However, the impact of mechanical stimuli on monocytic cells remains unclear. To assess whether mechanical stress affects monocytic cell function, we examined the expression of inflammatory molecules and surface proteins, whose levels changed following shear stress in human THP-1 cells. Shear stress increased the inflammatory chemokine CCL2, which enhanced the migration of monocytic cells and tumor necrosis factor (TNF)-α and interleukin (IL)- 1β at transcriptional and protein levels. We identified that the surface levels of heat shock protein 70 (HSP70), HSP90, and HSP105 increased using mass spectrometry-based proteomics, which was confirmed by western blot analysis, flow cytometry, and immunofluorescence. Treatment with HSP70/HSP105 and HSP90 inhibitors suppressed the expression and secretion of CCL2 and monocytic cell migration, suggesting an association between HSPs and inflammatory responses. We also demonstrated the coexistence and colocalization of increased HSP90 immunoreactivity and CD68 positive cells in atherosclerotic plaques of ApoE deficient mice fed a high-fat diet and human femoral artery endarterectomy specimens. These results suggest that monocytes/macrophages affected by shear stress polarize to a pro-inflammatory phenotype and increase surface protein levels involved in inflammatory responses. The regulation of the abovementioned HSPs upregulated on the monocytes/macrophages surface may serve as a novel therapeutic target for inflammation due to shear stress.

L-Theanine alleviates heat stress-induced impairment of immune function by regulating the p38 MAPK signalling pathway in mice

With the current trend of global warming, heat stress-induced impairment could seriously endanger human health. L-Theanine is a non-protein amino acid in tea with various biological activities, including immunoregulatory, anti-anxiety, and anti-oxidation. However, its effect on immune function under heat stress and the underlying mechanism are currently unclear. In this study, male BALB/c mice were used as experimental objects to explore the effect of L-theanine on heat stress-induced changes in immune function and its mechanism. Three doses of L-theanine were used: low (100 mg kg^-1 d^-1), medium (200 mg kg^-1 d^-1), and high (400 mg kg^-1 d^-1). Treatment with L-theanine could attenuate the heat stress-induced reductions in body weight and feed intake in mice, alleviate damage in the liver and jejunum, and inhibit the inflammatory factors IL-6, IL-1β, and TNF-α. Aspartate aminotransferase and alanine transaminase activity levels and the malondialdehyde content decreased, while the IgA, IgM, and IgG contents increased in response to L-theanine. It is possible that L-theanine affects the P38 signalling pathway and inhibits the increase in p-P65/P65 caused by the overexpression of HSP27 and regulation of PPAR-γ and Foxp3 proteins, thereby alleviating immune dysfunction caused by heat stress.

Fever-range whole body hyperthermia leads to changes in immune-related genes and miRNA machinery in Wistar rats

OBJECTIVE

Fever is defined as a rise in body temperature upon disease. Fever-range hyperthermia (FRH) is a simplified model of fever and a well-established medical procedure. Despite its beneficial effects, the molecular changes induced by FRH remain poorly characterized. The aim of this study was to investigate the influence of FRH on regulatory molecules such as cytokines and miRNAs involved in inflammatory processes.

METHODS

We developed a novel, fast rat model of infrared-induced FRH. The body temperature of animals was monitored using biotelemetry. FRH was induced by the infrared lamp and heating pad. White blood cell counts were monitored using Auto Hematology Analyzer. In peripheral blood mononuclear cells, spleen and liver expression of immune-related genes (IL-10, MIF and G-CSF, IFN-γ) and miRNA machinery (DICER1, TARBP2) was analyzed with RT-qPCR. Furthermore, RT-qPCR was used to explore miRNA-155 levels in the plasma of rats.

RESULTS

We observed a decrease in the total number of leukocytes due to lower number of lymphocytes, and an increase in the number of granulocytes. Furthermore, we observed elevated expressions of DICER1, TARBP2 and granulocyte colony-stimulating factor (G-CSF) in the spleen, liver and PBMCs immediately following FRH. FRH treatment also had anti-inflammatory effects, evidenced by the downregulation of pro-inflammatory macrophage migration inhibitor factor (MIF) and miR-155, and the increased expression of anti-inflammatory IL-10.

CONCLUSION

FRH affects the expression of molecules involved in inflammatory processes leading to alleviated inflammation. We suppose these effects may be miRNAs-dependent and FRH can be involved in therapies where anti-inflammatory action is needed.

The heterogeneity of microglial activation and its epigenetic and non-coding RNA regulations in the immunopathogenesis of neurodegenerative diseases

Microglia are resident immune cells in the brain and play a central role in the development and surveillance of the nervous system. Extensive gliosis is a common pathological feature of several neurodegenerative diseases, such as Alzheimer's disease (AD), the most common cause of dementia. Microglia can respond to multiple inflammatory insults and later transform into different phenotypes, such as pro- and anti-inflammatory phenotypes, thereby exerting different functions. In recent years, an increasing number of studies based on both traditional bulk sequencing and novel single-cell/nuclear sequencing and multi-omics analysis, have shown that microglial phenotypes are highly heterogeneous and dynamic, depending on the severity and stage of the disease as well as the particular inflammatory milieu. Thus, redirecting microglial activation to beneficial and neuroprotective phenotypes promises to halt the progression of neurodegenerative diseases. To this end, an increasing number of studies have focused on unraveling heterogeneous microglial phenotypes and their underlying molecular mechanisms, including those due to epigenetic and non-coding RNA modulations. In this review, we summarize the epigenetic mechanisms in the form of DNA and histone modifications, as well as the general non-coding RNA regulations that modulate microglial activation during immunopathogenesis of neurodegenerative diseases and discuss promising research approaches in the microglial era.

Increased miR-155 in Microglial Exosomes Following Heat Stress Accelerates Neuronal Autophagy via Their Transfer Into Neurons

Background

Heat stroke is the outcome of excessive heat stress, which results in core temperatures exceeding 40°C accompanied by a series of complications. The brain is particularly vulnerable to damage from heat stress. In our previous studies, both activated microglia and increased neuronal autophagy were found in the cortices of mice with heat stroke. However, whether activated microglia can accelerate neuronal autophagy under heat stress conditions is still unknown. In this study, we aimed to investigate the underlying mechanism that caused neuronal autophagy upregulation in heat stroke from the perspective of exosome-mediated intercellular communication.

Methods

In this study, BV2 and N2a cells were used instead of microglia and neurons, respectively. Exosomes were extracted from BV2 culture supernatants by ultracentrifugation and then characterized via transmission electron microscopy, nanoparticle tracking analysis and Western blotting. N2a cells pretreated with/without miR-155 inhibitor were cocultured with microglial exosomes that were treated with/without heat stress or miR-155 overexpression and subsequently subjected to heat stress treatment. Autophagy in N2a cells was assessed by detecting autophagosomes and autophagy-related proteins through transmission electron microscopy, immunofluorescence, and Western blotting. The expression of miR-155 in BV2 and BV2 exosomes and N2a cells was measured using real-time reverse transcription polymerase chain reaction. Target binding analysis was verified via a dual-luciferase reporter assay.

Results

N2a autophagy moderately increased in response to heat stress and accelerated by BV2 cells through transferring exosomes to neurons. Furthermore, we found that neuronal autophagy was positively correlated with the content of miR-155 in microglial exosomes. Inhibition of miR-155 partly abolished autophagy in N2a cells, which was increased by coculture with miR-155-upregulated exosomes. Mechanistic analysis confirmed that Rheb is a functional target of miR-155 and that microglial exosomal miR-155 accelerated heat stress-induced neuronal autophagy mainly by regulating the Rheb-mTOR signaling pathway.

Conclusion

Increased miR-155 in microglial exosomes after heat stroke can induce neuronal autophagy via their transfer into neurons. miR-155 exerted these effects by targeting Rheb, thus inhibiting the activity of mTOR signaling. Therefore, miR-155 could be a promising target for interventions of neuronal autophagy after heat stroke.

Lessons From Heat Stroke for Understanding Myalgic Encephalomyelitis/Chronic Fatigue Syndrome

We here provide an overview of the pathophysiological mechanisms during heat stroke and describe similar mechanisms found in myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS). Both conditions are characterized by disturbed homeostasis in which inflammatory pathways play a central role. Splanchnic vasoconstriction, increased gut permeability, gut-related endotoxemia, systemic inflammatory response, central nervous system dysfunction, blood coagulation disorder, endothelial-cell injury, and mitochondrial dysfunction underlie heat stroke. These mechanisms have also been documented in ME/CFS. Moreover, initial transcriptomic studies suggest that similar gene expressions are altered in both heat stroke and ME/CFS. Finally, some predisposing factors for heat stroke, such as pre-existing inflammation or infection, overlap with those for ME/CFS. Notwithstanding important differences - and despite heat stroke being an acute condition - the overlaps between heat stroke and ME/CFS suggest common pathways in the physiological responses to very different forms of stressors, which are manifested in different clinical outcomes. The human studies and animal models of heat stroke provide an explanation for the self-perpetuation of homeostatic imbalance centered around intestinal wall injury, which could also inform the understanding of ME/CFS. Moreover, the studies of novel therapeutics for heat stroke might provide new avenues for the treatment of ME/CFS. Future research should be conducted to investigate the similarities between heat stroke and ME/CFS to help identify the potential treatments for ME/CFS.

Liver X Receptor as a Possible Drug Target for Blood-Brain Barrier Integrity

Purpose: blood-brain barrier (BBB) is made of specialized cells that are responsible for the selective passage of substances directed to the brain. The integrated BBB is essential for precise controlling of the different substances passage as well as protecting the brain from various damages. In this article, we attempted to explain the role of liver X receptor (LXR) in maintaining BBB integrity as a possible drug target.

Methods: In this study, various databases, including PubMed, Google Scholar, and Scopus were searched using the following keywords: blood-brain barrier, BBB, liver X receptor, and LXR until July, 2020. Additionally, contents close to the subject of our study were surveyed.

Results: LXR is a receptor the roles of which in various diseases have been investigated. LXR can affect maintaining BBB by affecting various ways such as ATP-binding cassette transporter A1 (ABCA1), matrix metalloproteinase-9 (MMP9), insulin-like growth factor 1 (IGF1), nuclear factor-kappa B (NF-κB) signaling, mitogen-activated protein kinase (MAPK), tight junction molecules, both signal transducer and activator of transcription 1 (STAT1), Wnt/β-catenin Signaling, transforming growth factor beta (TGF-β) signaling, and expressions of Smad 2/3 and Snail.

Conclusion: LXR could possibly be used either as a target for drug delivery to brain tissue or as a target for maintaining the BBB integrity in different diseases; thereby the drug will be conducted to tissues, other than the brain. If it is verified that only LXRα is necessary for protecting BBB, some specific LXRα ligands must be found and then used in medication.

Modulation of microglial phenotypes by dexmedetomidine through TREM2 reduces neuroinflammation in heatstroke

No FDA approved pharmacological therapy is available to reduce neuroinflammation following heatstroke. Previous studies have indicated that dexmedetomidine (DEX) could protect against inflammation and brain injury in various inflammation-associated diseases. However, no one has tested whether DEX has neuro-protective effects in heatstroke. In this study, we focused on microglial phenotypic modulation to investigate the mechanisms underlying the anti-inflammatory effects of DEX in vivo and in vitro. We found that DEX treatment reduced the expression of CD68, iNOS, TNF-α, and IL-1β, and increased the expression of CD206, Arg1, IL-10 and TGF-β in microglia, ameliorating heatstroke induced neuroinflammation and brain injury in mice. TREM2, whose neuro-protective function has been validated by genetic studies in Alzheimer's disease and Nasu-Hakola disease, was significantly promoted by DEX in the microglia. TREM2 esiRNA reversed the DEX-induced activation of PI3K/Akt signalling. Overall these findings indicated that DEX may serve, as a potential therapeutic approach to ameliorate heatstroke induced neuroinflammation and brain injury via TREM2 by activating PI3K/Akt signalling.

Exosomes Derived From Heat Stroke Cases Carry miRNAs Associated With Inflammation and Coagulation Cascade

The pathological mechanism underlying heat stroke (HS) is associated with the dysbalanced inflammation and coagulation cascade. Cell-derived circulating extracellular vesicles (EVs), as a novel pathway mediating intercellular communication, are associated with the immune response and inflammation in critical inflammatory syndromes, such as sepsis. Although these vesicles contain genetic material correlated with their biological function, their molecular cargo during HS remains unknown. In this study, we evaluate the presence of microRNAs (miRNAs) and messenger RNAs (mRNAs) associated with inflammatory responses and coagulation cascade in exosomes of patients with HS. Blood samples were collected from three patients with HS at the time of admission to the intensive care unit; three healthy volunteers were selected as control. Exosomes were isolated using ultracentrifugation, and their miRNA content was profiled using next-generation sequencing; mRNA content was evaluated using qPCR array. Compared with those from healthy volunteers, exosomes from patients with HS showed substantial changes in the expression of 202 exosomal miRNAs (154 upregulated and 48 downregulated miRNAs). The most upregulated miRNAs included miR-511-3p, miR-122-5p, miR-155-3p, miR-1290, and let7-5p, whereas the most downregulated ones included miR-150-3p, 146a-5p, and 151a-3p. Gene ontology enrichment of the miRNAs of patients with HS compared with control subjects were associated mostly with inflammatory response, including T cell activation, B cell receptor signaling, dendritic cell chemotaxis and leukocyte migration, and platelet activation and blood coagulation. The identified miRNAs were primarily enriched to the signal transduction pathways namely, T cell receptor signaling, Ras signaling, chemokine signaling, platelet activation, and leukocyte transendothelial migration, all of which are associated with inflammation and hemostasis. Multiple targeted mRNAs associated with the inflammatory response, blood coagulation, and platelet activation were further verified in serum exosomes. Exosomes from patients with HS convey miRNAs and mRNAs associated with pathogenic pathways, including inflammatory response and coagulation cascade. Exosomes may represent a novel mechanism for intercellular communication during HS.

Research progress of heat stroke during 1989-2019: a bibliometric analysis

BACKGROUND

Heat stroke (HS) is an acute physical disorder that is associated with a high risk of organ dysfunction and even death. HS patients are usually treated symptomatically and conservatively; however, there remains a lack of specific and effective drugs in clinical practice. An analysis of publication contributions from institutions, journals and authors in different countries/regions was used to study research progress and trends regarding HS.

METHODS

We extracted all relevant publications on HS between 1989 and 2019 from Web of Science. Using the Statistical Package for Social Science (SPSS, version 24) and the software GraphPad Prism 8, graphs were generated and statistical analyses were performed, while VOSviewer software was employed to visualize the research trends in HS from the perspectives of co-occurring keywords.

RESULTS

As of April 14, 2020, we identified 1443 publications with a citation frequency of 5216. The United States accounted for the largest number of publications (36.2%) and the highest number of citations (14,410), as well as the highest H-index at 74. Although the sum of publications from China ranked second, there was a contradiction between the quantity and quality of publications. Furthermore, Medicine & Science in Sports & Exercise published the most papers related to HS, with Lin MT publishing the most papers in this field (112), while the review by Knochel JP received the highest citation frequency at 969. The keyword heat-stress appeared most recently, with an average appearing year of 2015.5. In the clinical research cluster, exertional heat-stroke was determined to be the hotspot, while ambient-temperature and heat waves were the new trends in the epidemiological research cluster.

CONCLUSIONS

Corresponding to this important field, while the contributions of the publications from the United States were significant, the mismatch between the quantity and quality of publications from China must be examined. Moreover, it is hypothesized that clinical and epidemiological studies may become hotspots in the near future.

The roles of liver X receptor α in inflammation and inflammation-associated diseases

Liver X receptor α (LXRα; also known as NR1H3), an isoform of LXRs, is a member of the nuclear receptor family of transcription factors and plays essential roles in the transcriptional control of cholesterol homeostasis. Previous in-depth phenotypic analyses of mouse models with deficient LXRα have also demonstrated various physiological functions of this receptor within inflammatory responses. LXRα activation exerts a combination of metabolic and anti-inflammatory actions resulting in the modulation and the amelioration of inflammatory disorders. The tight "repercussions" between LXRα and inflammation, as well as cholesterol homeostasis, have suggested that LXRα could be pharmacologically targeted in pathologies such as atherosclerosis, acute lung injury, and Alzheimer's disease. This review gives an overview of the recent advances in understanding the roles of LXRα in inflammation and inflammation-associated diseases, which will help in the design of future experimental researches on the potential of LXRα and advance the investigation of LXRα as pharmacological inflammatory targets.

Water amino acid-chelated trace mineral supplementation decreases circulating and intestinal HSP70 and proinflammatory cytokine gene expression in heat-stressed broiler chickens

Heat stress (HS) is a financial and physiological burden on the poultry industry and the mitigation of the adverse effects of HS is vital to poultry production sustainability. The purpose of this study was, therefore, to determine the effects of an amino acid-chelated trace mineral supplement on growth performance, stress and inflammatory markers, and meat quality in heat-stressed broilers. One day-old Cobb 500 male broilers (n = 480) were allocated into 12 environmental chambers (24 floor pens) and divided into two groups: one group supplemented with amino acid-chelated trace mineral in drinking water and one control group. On day 28, birds were subjected to chronic heat stress (HS, 2 wk, 35 °C and 20% to 30% RH) or maintained at thermoneutral condition (TN, 24 °C) in a 2 × 2 factorial design. Feed intake (FI), water consumption, and body weight were recorded. At day 42, serum fluorescein isothiocyanate dextran (FITC-D) levels, blood gas, electrolyte, and stress markers were measured. Jejunum samples were collected to measure gene expression of stress, inflammation, and tight junction proteins. The rest of the birds were processed to evaluate carcass traits. HS resulted in an increase in core body temperature, which increased water intake and decreased FI, body weight, and feed efficiency (P < 0.05). HS reduced carcass yield and the weight of all parts (P < 0.05). HS significantly increased levels of circulating corticosterone (CORT), heat shock protein 70 (HSP70), interleukin 18 (IL-18), tumor necrosis factor alpha, C-reactive protein, and nucleotide-binding oligomerization domain leucine-rich repeat and pyrin domain-containing 3 expression. HS significantly increased serum FITC-D levels and the expression of HSP70 and IL-18 in the jejunum. Although it did not affect the growth performance, amino acid-chelated trace mineral supplementation reversed the effect of HS by reducing CORT and FITC-D levels and the expression of stress and proinflammatory cytokines in the circulation and the jejunum. However, it upregulated these parameters in birds maintained under TN conditions. Together, these data indicate that the amino acid-chelated trace mineral might alleviate stress and inflammation and improve gut integrity in heat-stressed but not thermoneutral broilers.

Bone microRNA-21 as surgical stress parameter is associated with third molar postoperative discomfort

OBJECTIVE

To evaluate an association between bone levels of inflammation/oxidative stress mediators and postoperative discomfort after third molar conventional or piezosurgery.

MATERIAL AND METHODS

Twenty-six subjects with bilaterally impacted mandibular third molars, who underwent either piezo or conventional surgery, were included in a split-mouth design study. MicroRNA-21 (miR-21) expression, interleukin-1 beta (IL-1β), and vascular endothelial growth factor (VEGF) proteins, as well as superoxide dismutase (SOD) activity in alveolar bone, were evaluated. Pain intensity, the first pain appearance, analgesic first use and total dose taken, trismus, and swelling were clinically recorded.

RESULTS

MiR-21 expression was higher while VEGF protein was lower in piezosurgery vs. conventional groups. The differences in IL-1β protein and SOD activity were not significant between groups. The pain intensity on the first day was significantly decreased in piezosurgery group. The first pain appearance and the first analgesic taken were reported sooner in conventional vs. piezosurgical group. Significantly pronounced trismus on the third day following conventional surgery was found. In conventional group, significantly increased trismus was observed on the third compared to the first postoperative day. MiR-21 showed significant correlation with the first pain appearance.

CONCLUSION

Delayed onset of less pronounced postoperative pain after piezosurgical vs. conventional extraction of impacted lower third molar was significantly associated with expression of bone miR-21.

CLINICAL RELEVANCE

Alveolar bone miR-21 may reflect surgical stress and is associated with third molar postoperative pain onset.

A Case of Exertional Heat Stroke Complicated by Hypoxic Hepatitis

Background

Exertional heat stroke is a life-threatening condition often complicated by multiorgan failure. We hereby present a case of a 25-year-old male presenting with syncope after a 10  km run in 28°C outside temperature who developed acute liver failure. Case Presentation. Initial temperature was found to be 41.1°C, and cooling measures were rapidly applied. He suffered from acute renal failure and rhabdomyolysis and proceeded to acute liver failure (ASAT 6100 U/l and ALAT 6561 U/l) due to hypoxic hepatitis on day 3. He did not meet criteria for emergency liver transplantation and recovered on supportive care.

Conclusions

Acute liver failure due to heat stroke is a life-threatening condition with often delayed onset, which nevertheless resolves on supportive care in the majority of cases; thus, a delayed referral to transplant seems to be reasonable.

Chronic ethanol exposure facilitates facial-evoked MLI-PC synaptic transmission via nitric oxide signaling pathway in vivo in mice

Ethanol (EtOH) exposure causes alterations of motor coordination, balance, behavior, speech, and certain cognitive functions are considered to be caused partly by impairment of cerebellar circuits function and modulation of synaptic transmission. The cerebellar cortical molecular layer interneuron-Purkinje cell (MLI-PC) synapses are critical for various information integration and transmission, which are sensitive to acute and chronic EtOH exposure. The aim of this study is to investigate the effect of chronic ethanol exposure on the facial stimulation-evoked MLI-PC synaptic transmission in urethane-anesthetized mice, by electrophysiological recording and pharmacological methods. Under current-clamp recording conditions, air-puff stimulation of ipsilateral whisker pad evoked MLI-PC synaptic transmission, which expressed an inhibitory component (P1) followed by a pause of simple spike (SS) firing in cerebellar PCs. Chronic ethanol exposure did not change the latency of the facial stimulation-evoked responses in cerebellar PCs, but induced significant enhancement of the stimulation-evoked MLI-PC synaptic transmission, which expressed increases in amplitude of P1 and pause of SS firing. The amplitude of P1 and pause of SS in ethanol exposure group were significant higher than that in control group. Cerebellar surface application of nitric oxide synthesis (NOS) inhibitor, L-NNA (5 mM) significantly decreased the amplitude of P1 and the pause of SS firing in EtOH exposure group, but did no effect on control group. In contrast, cerebellar surface application of NO donor, SNAP (100 μM) significantly increased the amplitude of P1 and the pause of SS firing in control group, but not in EtOH exposure group. These results indicated that chronic EtOH exposure significantly facilitated the sensory-evoked MLI-PC synaptic transmission via NO signaling pathway in mouse cerebellar cortex.

Intranasal Delivery of miR-155-5p Antagomir Alleviates Acute Seizures Likely by Inhibiting Hippocampal Inflammation

INTRODUCTION

To confront the resistance to existing antiepileptic drugs, studies have gradually begun to investigate alternative pathologies distinct from the traditional treatments that overwhelmingly target ion channels. Microglia activation is the first inflammatory response in the brain, in which miR-155-5p plays a key proinflammatory role and thus represents a promising target for inflammatory modulation in epilepsy pathologies.

METHODS

In this study, a pentetrazol-induced acute seizure model was established, and the seizure degree was evaluated within 60 min after pentetrazol administration. Animals were then sacrificed for hippocampal tissue collection for biological experiments.

RESULTS

Intranasal delivery of miR-155-5p antagomir (30 min before pentetrazol administration) increased the percentage of animals with no induced seizures by 20%, extended the latency to generalized convulsions, and decreased seizure severity. In addition, miR-155-5p antagomir treatment alleviated hippocampal damage and decreased the expression of typical inflammatory modulators (TNF-α, IL-1β and IL-6). Further research revealed that intranasal delivery of miR-155-5p antagomir significantly decreased the relative level of miR-155-5p and increased the expression of its targets LXRα and SOCS1 in IBA1-labeled microglial cells in the hippocampus.

CONCLUSION

These findings demonstrate that intranasal delivery of miR-155-5p antagomir alleviated acute seizures, likely by blocking hippocampal inflammation. However, other potential mechanisms of the effects of miR-155-5p antagomir and its long-term safety for epilepsy treatment remain to be investigated.