HSP60 plays a regulatory role in IL-1β-induced microglial inflammation via TLR4-p38 MAPK axis

Navigating the intersection: Diabetes and Alzheimer's intertwined relationship

Alzheimer's disease (AD) and Diabetes mellitus (DM) exhibit comparable pathophysiological pathways. Genetic abnormalities in APP, PS-1, and PS-2 are linked to AD, with diagnostic aid from CSF and blood biomarkers. Insulin dysfunction, termed "type 3 diabetes mellitus" in AD, involves altered insulin signalling and neuronal shrinkage. Insulin influences beta-amyloid metabolism, exacerbating neurotoxicity in AD and amyloid production in DM. Both disorders display impaired glucose transporter expression, hastening cognitive decline. Mitochondrial dysfunction and Toll-like receptor 4-mediated inflammation worsen neurodegeneration in both diseases. ApoE4 raises disease risk, especially when coupled with dyslipidemia common in DM. Targeting shared pathways like insulin-degrading enzyme activation and HSP60 holds promise for therapeutic intervention. Recognizing these interconnected mechanisms underscores the imperative for developing tailored treatments addressing the overlapping pathophysiology of AD and DM, offering potential avenues for more effective management of both conditions.

Differential expression of cellular prion protein (PrPC) in mouse hepatitis virus induced neuroinflammation

The cellular prion protein (PrPC) is an extracellular cell membrane protein. Due to its diversified roles, a definite role of PrPC has been difficult to establish. During viral infection, PrPC has been reported to play a pleiotropic role. Here, we have attempted to envision the function of PrPC in the neurotropic m-CoV-MHV-RSA59-induced model of neuroinflammation in C57BL/6 mice. A significant upregulation of PrPC at protein and mRNA levels was evident in infected mouse brains during the acute phase of neuroinflammation. Furthermore, investigation of the effect of MHV-RSA59 infection on PrPC expression in specific neuronal, microglial, and astrocytoma cell lines, revealed a differential expression of prion protein during neuroinflammation. Additionally, siRNA-mediated downregulation of prnp transcripts reduced the expression of viral antigen and viral infectivity in these cell lines. Cumulatively, our results suggest that PrPC expression significantly increases during acute MHV-RSA59 infection and that PrPC also assists in viral infectivity and viral replication.

Allopregnanolone and its antagonist modulate neuroinflammation and neurological impairment

Neuroinflammation accompanies several brain disorders, either as a secondary consequence or as a primary cause and may contribute importantly to disease pathogenesis. Neurosteroids which act as Positive Steroid Allosteric GABA-A receptor Modulators (Steroid-PAM) appear to modulate neuroinflammation and their levels in the brain may vary because of increased or decreased local production or import from the systemic circulation. The increased synthesis of steroid-PAMs is possibly due to increased expression of the mitochondrial cholesterol transporting protein (TSPO) in neuroinflammatory tissue, and reduced production may be due to changes in the enzymatic activity. Microglia and astrocytes play an important role in neuroinflammation, and their production of inflammatory mediators can be both activated and inhibited by steroid-PAMs and GABA. What is surprising is the finding that both allopregnanolone, a steroid-PAM, and golexanolone, a novel GABA-A receptor modulating steroid antagonist (GAMSA), can inhibit microglia and astrocyte activation and normalize their function. This review focuses on the role of steroid-PAMs in neuroinflammation and their importance in new therapeutic approaches to CNS and liver disease.

Medicinal herbal remedies in neurodegenerative diseases: an update on antioxidant potential

It has been widely documented that medicinal herbal remedies are effective, have fewer side effects than conventional medicine, and have a synergistic effect on health collaborations in the fight against complicated diseases. Traditional treatments for neurological problems in ancient times sometimes involved the use of herbal remedies and conventional methods from East Asian countries including India, Japan, China, and Korea. We collected and reviewed studies on plant-derived neuroprotective drugs and tested them in neurotoxic models. Basic research, preclinical and clinical transgene research can benefit from in silico, in vitro, and in vivo investigations. Research, summaries of the extracts, fractions, and herbal ingredients were compiled from popular scientific databases, which were then examined according to origin and bioactivity. Given the complex and varied causes of neurodegeneration, it may be beneficial to focus on multiple mechanisms of action and a neuroprotection approach. This approach aims to prevent cell death and restore function to damaged neurons, offering promising strategies for preventing and treating neurodegenerative diseases. Neurodegenerative illnesses can potentially be treated with natural compounds that have been identified as neuroprotective agents. To gain deeper insights into the neuropharmacological mechanisms underlying the neuroprotective and therapeutic properties of naturally occurring antioxidant phytochemical compounds in diverse neurodegenerative diseases, this study aims to comprehensively review such compounds, focusing on their modulation of apoptotic markers such as caspase, Bax, Bcl-2, and proinflammatory markers. In addition, we delve into a range of efficacies of antioxidant phytochemical compounds as neuroprotective agents in animal models. They reduce the oxidative stress of the brain and have been shown to have anti-apoptotic effects. Many researches have demonstrated that plant extracts or bioactive compounds can fight neurodegenerative disorders. Herbal medications may offer neurodegenerative disease patients' new treatments. This may be a cheaper and more culturally appropriate alternative to standard drugs for millions of people with age-related NDDs.

Regulation of microglia-mediated inflammation by host lncRNA Gm20559 upon flaviviral infection

BACKGROUND

Japanese Encephalitis Virus (JEV) and West Nile Viruses (WNV) are neurotropic flaviviruses which cause neuronal death and exaggerated glial activation in the central nervous system. Role of host long non coding RNAs in shaping microglial inflammation upon flavivirus infections has been unexplored. This study attempted to decipher the role of lncRNA Gm20559 in regulating microglial inflammatory response in context of flaviviruses.

METHODS

Antisense oligonucleotide LNA Gapmers designed against lncRNA Gm20559 and non-specific site (negative control) were used for Gm20559 knockdown in JEV and WNV-infected N9 microglial cells. Upon establishing successful Gm20559 knockdown, expression of various proinflammatory cytokines, chemokines, interferon-stimulated genes (ISGs) and RIG-I were checked by qRT-PCR and cytometric bead array. Western Blotting was done to analyse the phosphorylation level of various inflammatory markers and viral non-structural protein expression. Plaque Assays were employed to quantify viral titres in microglial supernatant upon knocking down Gm20559. Effect of microglial supernatant on HT22 neuronal cells was assessed by checking expression of apoptotic protein and viral non-structural protein by Western Blotting.

RESULTS

Upregulation in Gm20559 expression was observed in BALB/c pup brains, primary microglia as well as N9 microglia cell line upon both JEV and WNV infection. Knockdown of Gm20559 in JEV and WNV-infected N9 cell led to the reduction of major proinflammatory cytokines - IL-1β, IL-6, IP-10 and IFN-β. Inhibition of Gm20559 upon JEV infection in N9 microglia also led to downregulation of RIG-I and OAS-2, which was not the case in WNV-infected N9 microglia. Phosphorylation level of P38 MAPK was reduced in case of JEV-infected N9 microglia and not WNV-infected N9 microglia. Whereas phosphorylation of NF-κB pathway was unchanged upon Gm20559 knockdown in both JEV and WNV-infected N9 microglia. However, treating HT22 cells with JEV and WNV-infected microglial supernatant with and without Gm20559 could not trigger cell death or influence viral replication.

CONCLUSION

Knockdown studies on lncRNA Gm20559 suggests its pivotal role in maintaining the inflammatory milieu of microglia in flaviviral infection by modulating the expression of various pro-inflammatory cytokines. However, Gm20559-induced increased microglial proinflammatory response upon flavivirus infection fails to trigger neuronal death.

The role of heat shock proteins in the pathogenesis of heart failure (Review)

The influence of heat shock proteins (HSPs) on protein quality control systems in cardiomyocytes is currently under investigation. The effect of HSPs on the regulated cell death of cardiomyocytes (CMCs) is of great importance, since they play a major role in the implementation of compensatory and adaptive mechanisms in the event of cardiac damage. HSPs mediate a number of mechanisms that activate the apoptotic cascade, playing both pro‑ and anti‑apoptotic roles depending on their location in the cell. Another type of cell death, autophagy, can in some cases lead to cell death, while in other situations it acts as a cell survival mechanism. The present review considered the characteristics of the expression of HSPs of different molecular weights in CMCs in myocardial damage caused by heart failure, as well as their role in the realization of certain types of regulated cell death.

Platelet-Derived Exosomes Alleviate Knee Osteoarthritis by Attenuating Cartilage Degeneration and Subchondral Bone Loss

BACKGROUND

Osteoarthritis (OA) is the most prevalent chronic degenerative joint disease among the aged population. However, current treatments for OA are limited to alleviating symptoms, with no therapies that prevent and regenerate cartilage deterioration.

PURPOSE

To assess the effects of platelet-derived exosomes (Plt-exos) on OA and then to explore the potential molecular mechanism.

STUDY DESIGN

Controlled laboratory study.

METHODS

Exosomes derived from human apheresis platelets were isolated and identified. The effects of Plt-exos in protecting chondrocytes under interleukin 1β stimulation were evaluated by analyzing the proliferation and migration in human primary chondrocytes. RNA sequencing was later performed in vitro for primary chondrocytes to reveal the underlying mechanisms of Plt-exo treatment. Anterior cruciate ligament transection was used to construct an OA mice model, and intra-articular injection of Plt-exos was given once a week for 6 weeks. Mice were sacrificed 4 weeks after the last injection. Histologic and immunohistochemistry staining and micro-computed tomography analysis were performed to assess alterations of articular cartilage and subchondral bone.

RESULTS

Plt-exos significantly promoted proliferation and migration of chondrocytes within a dose-dependent manner, as well as dramatically promoted cartilage regeneration and attenuated abnormal tibial subchondral bone remodeling, thus slowing the progression of OA. After being treated with Plt-exos, 1797 genes were differentially expressed in chondrocytes (923 upregulated and 874 downregulated genes). Functional enrichment results and hub genes were mainly involved in anti-inflammatory effects, mediating cell adhesion, stimulating cartilage repair, promoting anabolism, and inhibiting catabolism.

CONCLUSION

Our results demonstrated that Plt-exos promoted chondrocyte proliferation and migration in vitro, as well as attenuated cartilage degeneration, improved the microarchitecture of subchondral bone, and retarded OA progression in vivo.

CLINICAL RELEVANCE

Our study illustrated that the administered Plt-exos could alleviate knee OA by attenuating cartilage degeneration and subchondral bone loss, possibly serving as a novel promising treatment for OA in the future.

CCR7+ CD4 T Cell Immunosurveillance Disrupted in Chronic SIV-Induced Neuroinflammation in Rhesus Brain

CD4 T cells survey and maintain immune homeostasis in the brain, yet their differentiation states and functional capabilities remain unclear. Our approach, combining single-cell transcriptomic analysis, ATAC-seq, spatial transcriptomics, and flow cytometry, revealed a distinct subset of CCR7+ CD4 T cells resembling lymph node central memory (T CM ) cells. We observed chromatin accessibility at the CCR7, CD28, and BCL-6 loci, defining molecular features of T CM . Brain CCR7+ CD4 T cells exhibited recall proliferation and interleukin-2 production ex vivo, showcasing their functional competence. We identified the skull bone marrow as a local niche for these cells alongside other CNS border tissues. Sequestering T CM cells in lymph nodes using FTY720 led to reduced CCR7+ CD4 T cell frequencies in the cerebrospinal fluid, accompanied by increased monocyte levels and soluble markers indicating immune activation. In macaques chronically infected with SIVCL57 and experiencing viral rebound due to cessation of antiretroviral therapy, a decrease in brain CCR7+ CD4 T cells was observed, along with increased microglial activation and initiation of neurodegenerative pathways. Our findings highlight a role for CCR7+ CD4 T cells in CNS immune surveillance and their decline during chronic SIV-induced neuroinflammation highlights their responsiveness to neuroinflammatory processes.

GRAPHICAL ABSTRACT

In Brief

Utilizing single-cell and spatial transcriptomics on adult rhesus brain, we uncover a unique CCR7+ CD4 T cell subset resembling central memory T cells (T CM ) within brain and border tissues, including skull bone marrow. Our findings show decreased frequencies of this subset during SIV- induced chronic neuroinflammation, emphasizing responsiveness of CCR7+ CD4 T cells to CNS disruptions.

Highlights

CCR7+ CD4 T cells survey border and parenchymal CNS compartments during homeostasis; reduced presence of CCR7+ CD4 T cells in cerebrospinal fluid leads to immune activation, implying a role in neuroimmune homeostasis. CNS CCR7+ CD4 T cells exhibit phenotypic and functional features of central memory T cells (T CM ) including production of interleukin 2 and the capacity for rapid recall proliferation. Furthermore, CCR7+ CD4 T cells reside in the skull bone marrow. CCR7+ CD4 T cells are markedly decreased within the brain parenchyma during chronic viral neuroinflammation.

Clinical observation and mechanism of acupuncture on amnestic mild cognitive impairment based on the gut-brain axis: study protocol for a randomized controlled trial

Background

Amnestic mild cognitive impairment (aMCI) is a pre-dementia condition associated with declined cognitive function dominated by memory impairment. The occurrence of aMCI is associated with the gut-brain axis. Previous studies have shown cognitive improvements in MCI after acupuncture treatment. This study evaluates whether acupuncture can produce a therapeutic effect in patients with aMCI by modulating the gut-brain axis.

Methods and design

This is a prospective, parallel, multicenter randomized controlled trial. A total of 40 patients with aMCI will be randomly assigned to an acupuncture group (AG) or a waiting-list group (WG), participants in both groups will receive health education on improving cognitive function at each visit, and acupuncture will be conducted twice a week for 12 weeks in the AG. Another 20 matched healthy volunteers will be enrolled as normal control. The primary outcome will be the change in Alzheimer's Disease Assessment Scale-cognitive scale score before and after treatment. Additionally, functional magnetic resonance imaging data, faeces, and blood will be collected from each participant to characterize the brain function, gut microbiota, and inflammatory cytokines, respectively. The differences between patients with aMCI and healthy participants, and the changes in the AG and WG groups before and after treatment will be observed. Ultimately, the correlation among brain function, gut microbiota, inflammatory cytokines, and clinical efficacy evaluation in patients with aMCI will be analyzed.

Discussion

This study will identify the efficacy and provide preliminary data on the possible mechanism of acupuncture in treating aMCI. Furthermore, it will also identify biomarkers of the gut microbiota, inflammatory cytokines, and brain function correlated with therapeutic effects. The results of this study will be published in peer-reviewed journals.

Clinical trial registration

http://www.chictr.org.cn, identifier ChiCTR2200062084.

Lambda-cyhalothrin enhances inflammation in nigrostriatal region in rats: Regulatory role of NF-κβ and JAK-STAT signaling

The risk to develop neurobehavioural abnormalities in humans on exposure to lambda-cyhalothrin (LCT) - a type II synthetic pyrethroid has enhanced significantly due to its extensive uses in agriculture, homes, veterinary practices and public health programs. Earlier, we found that the brain dopaminergic system is vulnerable to LCT and affects motor functions in rats. In continuation to this, the present study is focused to unravel the role of neuroinflammation in LCT-induced neurotoxicity in substantia nigra and corpus striatum in rats. Increase in the mRNA expression of proinflammatory cytokines (TNF- α, IL-1β, IL-6) and iNOS whereas decrease in anti-inflammatory cytokine (IL-10) was distinct both in substantia nigra and corpus striatum of rats treated with LCT (0.5, 1.0, 3.0 mg/kg body weight, p.o, for 45 days) as compared to control rats. Further, LCT-treated rats exhibited increased levels of glial fibrillary acidic protein (GFAP) and ionized calcium-binding adapter molecule 1 (Iba-1), the glial marker proteins both in substantia nigra and corpus striatum as compared to controls. Exposure of rats to LCT also caused alterations in the levels of heat shock protein 60 (HSP60) and mRNA expression of toll-like receptors (TLR2 and TLR4) in the substantia nigra and corpus striatum. An increase in the phosphorylation of key proteins involved in NF-kβ (P65, Iκβ, IKKα, IKKβ) and JAK/STAT (STAT1, STAT3) signaling and alteration in the protein levels of JAK1 and JAK2 was prominent in LCT-treated rats. Histological studies revealed damage of dopaminergic neurons and reactive gliosis as evidenced by the presence of darkly stained pyknotic neurons and decrease in Nissl substance and an increase in infiltration of immune cells both in substantia nigra and corpus striatum of LCT-treated rats. Presence of reactive microglia and astrocytes in LCT-treated rats was also distinct in ultrastructural studies. The results exhibit that LCT may damage dopaminergic neurons in the substantia nigra and corpus striatum by inducing inflammation as a result of stimulation of neuroglial cells involving activation of NF-κβ and JAK/STAT signaling.

ATF5 Attenuates the Secretion of Pro-Inflammatory Cytokines in Activated Microglia

The highly dynamic changes in microglia necessary to achieve a rapid neuroinflammatory response require a supply of energy from mitochondrial respiration, which leads to the accumulation of unfolded mitochondrial proteins. We previously reported that microglial activation is correlated with the mitochondrial unfolded protein response (UPRmt) in a kaolin-induced hydrocephalus model, but we still do not know the extent to which these changes in microglia are involved in cytokine release. Here, we investigated the activation of BV-2 cells and found that treatment with lipopolysaccharide (LPS) for 48 h increased the secretion of pro-inflammatory cytokines. This increase was accompanied by a concurrent decrease in oxygen consumption rate (OCR) and mitochondrial membrane potential (MMP), in association with the up-regulation of the UPRmt. Inhibition of the UPRmt by knockdown of ATF5, a key upstream regulator of the UPRmt, using small-interfering RNA against ATF5 (siATF5) not only increased production of the pro-inflammatory cytokines, interleukin-6 (IL-6), IL-1β and tumor necrosis factor-α (TNF-α), but also decreased MMP. Our results suggest that ATF5-dependent induction of the UPRmt in microglia acts as a protective mechanism during neuroinflammation and may be a potential therapeutic target for reducing neuroinflammation.

Glaucoma as a Neurodegenerative and Inflammatory Disease

Glaucoma is a neurodegenerative disease that leads to irreversible loss of vision through degeneration of the retinal ganglia cells (RGCs). Glaucoma is one of the most frequent causes of blindness in the world. Intraocular pressure is the main risk factor for the occurrence and development of this disease. Treatment is largely based on reducing internal optical pressure. However, some patients may deteriorate or become blind, despite normal or reduced internal optical pressure. The pathophysiological details are still unclear. Neuroinflammatory processes are also apparently an additional cause. In principle, innate or local responses of the adaptive immune system can be distinguished. The reaction of the innate immune system, particularly the local microglial cells, has long been studied. The macroglia with the astrocytes and Müller cells and their homeostatic effects have also long been known. On the other hand, it has long been thought that the retina with its RGZs was inert to adaptive immunological reactions - due to the function of the blood brain barrier. However, this system may be disturbed by antigen presentation, leading to a reaction of the adaptive immune system, with B cell and T cell responses. In this context, the key proteins are presumably heat shock proteins. We now know that neuroinflammation is important in glaucoma, as in other neurodegenerative diseases. It is important to increase our understanding of these phenomena. In this review article, we present our current knowledge of the role of the micro- and macroglia, the adaptive immune system, and the heat shock proteins.

miR-92b-5p negatively regulates IKK through targeting its ORF region in the innate immune responses of amphioxus (Branchiostoma belcheri)

Cephalochordate (Amphioxus), situated at a key phylogenetic position in the phylum Chordata, serves as a model organism for studying the origin and evolution of the vertebrate innate immune. In this study, five members of precursor miR-92 family (miR-92a-1, miR-92a-2, miR-92b, miR-92c and miR-92d) are identified in Branchiostoma belcheri, and their evolutionary conservation and potential molecular functions in innate immunity are analyzed. Among them, miR-92b-5p was validated in HEK293 cells to target the coding region but not classic 3'UTR of IKK (inhibitor of nuclear factor kappa-B kinase) mRNA, one integral component of MAPK and TLR4 immune signaling. Furthermore, the spatiotemporal expression patterns of miR-92b-5p and IKK were examined in different tissues or different time points (2 h, 4 h, 8 h, 12 h, 24 h and 48 h) post LPS stimulation at RNA and protein level in vivo. The seemingly inverse expression pattern between miR-92b-5p and IKK supports the involvement of miR-92b-5p in Branchiostoma belcheri innate immune response. In conclusion, our work not only illustrates the evolutionary pattern of Branchiostoma belcheri miR-92 family across chordates, but also reveals that miR-92b-5p could target IKK expression to regulate innate immune response.

Modified exosomal SIRPα variants alleviate white matter injury after intracerebral hemorrhage via microglia/macrophages

Background

Despite limited efficiency, modulation of microglia/macrophages has shown to attenuate neuroinflammation after intracerebral hemorrhage (ICH). In this context, we evaluated the efficacy of modified exosomal signal regulatory protein α (SIRPα) variants (SIRPα-v Exos) in microglia/macrophages and neuroinflammation-associated white matter injury after ICH.

Methods

SIRPα-v Exos were engineered to block CD47-SIRPα interactions. After obtaining SIRPα-v Exos from lentivirus-infected mesenchymal stem cells, C57BL/6 mice suffering from ICH underwent consecutive intravenous injections of SIRPα-v Exos (6 mg/kg) for 14 days. Afterwards, the volume of hematoma and neurological dysfunctions were assessed in mice continuously until 35 days after ICH. In addition, demyelination, electrophysiology and neuroinflammation were evaluated. Furthermore, the mechanisms of microglial regulation by SIRPα-v Exos were investigated in vitro under coculture conditions.

Results

The results demonstrated that the clearance of hematoma in mice suffering from ICH was accelerated after SIRPα-v Exo treatment. SIRPα-v Exos improved long-term neurological dysfunction by ameliorating white matter injury. In addition, SIRPα-v Exos recruited regulatory T cells (Tregs) to promote M2 polarization of microglia/macrophages in the peri-hematoma tissue. In vitro experiments further showed that SIRPα-v Exos regulated primary microglia in a direct and indirect manner in synergy with Tregs.

Conclusion

Our studies revealed that SIRPα-v Exos could accelerate the clearance of hematoma and ameliorate secondary white matter injury after ICH through regulation of microglia/macrophages. SIRPα-v Exos may become a promising treatment for ICH in clinical practice.

Graphical Abstract

Neuroinflammation in retinitis pigmentosa: Therapies targeting the innate immune system

Retinitis pigmentosa (RP) is an important cause of irreversible blindness worldwide and lacks effective treatment strategies. Although mutations are the primary cause of RP, research over the past decades has shown that neuroinflammation is an important cause of RP progression. Due to the abnormal activation of immunity, continuous sterile inflammation results in neuron loss and structural destruction. Therapies targeting inflammation have shown their potential to attenuate photoreceptor degeneration in preclinical models. Regardless of variations in genetic background, inflammatory modulation is emerging as an important role in the treatment of RP. We summarize the evidence for the role of inflammation in RP and mention therapeutic strategies where available, focusing on the modulation of innate immune signals, including TNFα signaling, TLR signaling, NLRP3 inflammasome activation, chemokine signaling and JAK/STAT signaling. In addition, we describe epigenetic regulation, the gut microbiome and herbal agents as prospective treatment strategies for RP in recent advances.

Photobiomodulation for the treatment of neuroinflammation: A systematic review of controlled laboratory animal studies

Background

Neuroinflammation is a response that involves different cell lineages of the central nervous system, such as neurons and glial cells. Among the non-pharmacological interventions for neuroinflammation, photobiomodulation (PBM) is gaining prominence because of its beneficial effects found in experimental brain research. We systematically reviewed the effects of PBM on laboratory animal models, specially to investigate potential benefits of PBM as an efficient anti-inflammatory therapy.

Methods

We conducted a systematic search on the bibliographic databases (PubMed and ScienceDirect) with the keywords based on MeSH terms: photobiomodulation, low-level laser therapy, brain, neuroinflammation, inflammation, cytokine, and microglia. Data search was limited from 2009 to June 2022. We followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guideline. The initial systematic search identified 140 articles. Among them, 54 articles were removed for duplication and 59 articles by screening. Therefore, 27 studies met the inclusion criteria.

Results

The studies showed that PBM has anti-inflammatory properties in several conditions, such as traumatic brain injury, edema formation and hyperalgesia, ischemia, neurodegenerative conditions, aging, epilepsy, depression, and spinal cord injury.

Conclusion

Taken together, these results indicate that transcranial PBM therapy is a promising strategy to treat brain pathological conditions induced by neuroinflammation.

Protective effect of ginsenoside Rh2 against Toxoplasma gondii infection-induced neuronal injury through binding TgCDPK1 and NLRP3 to inhibit microglial NLRP3 inflammasome signaling pathway

BACKGROUND

Toxoplasma gondii (T. gondii) is a neurotropic obligate intracellular parasite that can activate microglial and promote neuronal apoptosis, leading to central nervous system diseases. The NOD-like receptor family pyrin domain-containing 3 (NLRP3) inflammasome signaling complex plays a key role in inducing neuroinflammation. Our previous studies have found that ginsenoside Rh2 (GRh2) inhibits T. gondii infection-induced microglial activation and neuroinflammation by downregulating the Toll-like receptor 4/nuclear factor-kappa B signaling pathway. However, whether GRh2 reduces T. gondii infection-induced neuronal injury through actions on microglial NLRP3 inflammasome signaling has not yet been clarified.

METHODS

In this study, we employed T. gondii RH strain to establish in vitro and in vivo infection models in BV2 microglia cell line and BALB/c mice. Molecular docking, localized surface plasmon resonance assay, quantitative competitive-PCR, ELISA, western blotting, flow cytometric analysis, and immunofluorescence were performed.

RESULTS

Our results showed that GRh2 alleviated neuropathological damage and neuronal apoptosis in cortical tissue of T. gondii-infected mice. GRh2 and CY-09 (an inhibitor of NLRP3) exhibited potent anti-T. gondii effects through binding T. gondii calcium-dependent protein kinase 1 (TgCDPK1). GRh2 decreased Iba-1 (a specific microglial marker) and NLRP3 inflammasome signaling pathway-related protein expression by binding NLRP3. Co-culture of microglia/primary cortical neurons revealed that T. gondii-induced microglial activation caused neuronal apoptosis, but GRh2 reduced this effect, consistent with the effects of CY-09.

CONCLUSION

Taken together, our results show that GRh2 has a protective effect against T. gondii infection-induced neuronal injury by binding TgCDPK1 and NLRP3 to inhibit NLRP3 inflammasome signaling pathway in microglia.

HSP expression depends on its molecular construction and different organs of the chicken: a meta-analysis

Heat shock proteins (HSPs) expression protect the cell from stress, this expression varies on tissue and stress level. Here, we investigated the structure and functional expression of HSPs in different chicken organs using meta-analysis. A total of 1253 studies were collected from three different electronic databases from January 1, 2015 to February 1, 2022. Of these studies, 28 were selected based on the specific criteria for this meta-analysis. The results for the expression of HSPs and the comparative expression of HSPs (HSP90, HSP70, and HSP60) in different chicken organs (brain, heart, liver, muscle, and intestine) were analyzed using the odds ratio or the random-effects model (REM) at a confidence interval (CI) of 95%. Compared to the thermoneutral groups, heat stress groups exhibited a significant (P < 0.01) change in their HSP70 expression in the chicken liver (8 trials: REM = 1.41, 95% CI: 0.41, 4.82). The expression of different HSPs in various chicken organs varied and the different organs were categorized according to their expression levels. HSP expression differed among the heart, liver, and muscle of chickens. HSPs expression level depends on the structure and molecular weight of the HSPs, as well as the type of tissue.

The role of damage associated molecular pattern molecules (DAMPs) and permeability of the blood-brain barrier in depression and neuroinflammation

Depression is a heterogeneous mental disorder characterized by feelings of sadness and loss of interest that render the subject unable to handle basic daily activities such as sleeping, eating, or working. Neurobiological traits leading to depression include genetic background, early life abuse, life stressors, and systemic and central inflammatory profiles. Several clinical and preclinical reports documented that depression shows an increase in pro-inflammatory markers such as interleukin (IL-)1β, IL-6, IL-12, tumor necrosis factor (TNF), and interferon (IFN)-γ; and a decrease in anti-inflammatory IL-4, IL-10, and transforming growth factor (TGF)-β species. Inflammatory activation may trigger and maintain depression. Dynamic crosstalk between the peripheral immune system and the central nervous system (CNS) such as activated endothelial cells, monocytes, monocyte-derived dendritic cells, macrophages, T cells, and microglia has been proposed as a leading cause of neuroinflammation. Notably, pro-inflammatory cytokines disrupt the hypothalamic-pituitary-adrenal (HPA) axis and serotonergic, noradrenergic, dopaminergic, and glutamatergic neurotransmission. While still under investigation, peripheral cytokines can engage brain pathways and affect the central synthesis of HPA hormones and neurotransmitters through several mechanisms such as activation of the vagus nerve, increasing the permeability of the blood-brain barrier (BBB), altered cytokines transport systems, and engaging toll-like receptors (TLRs) by pathogen-associated molecular patterns (PAMPs) or damage-associated molecular patterns (DAMPs). However, physiological mechanisms that favor time-dependent central inflammation before or during illness are not totally understood. This review will provide preclinical and clinical evidence of DAMPs and the BBB permeability as contributors to depression and neuroinflammation. We will also discuss pharmacologic approaches that could potentially modulate DAMPs and BBB permeability for future interventions against major depression.

Mitochondrial Protein Homeostasis and Cardiomyopathy

Human mitochondrial disorders impact tissues with high energetic demands and can be associated with cardiac muscle disease (cardiomyopathy) and early mortality. However, the mechanistic link between mitochondrial disease and the development of cardiomyopathy is frequently unclear. In addition, there is often marked phenotypic heterogeneity between patients, even between those with the same genetic variant, which is also not well understood. Several of the mitochondrial cardiomyopathies are related to defects in the maintenance of mitochondrial protein homeostasis, or proteostasis. This essential process involves the importing, sorting, folding and degradation of preproteins into fully functional mature structures inside mitochondria. Disrupted mitochondrial proteostasis interferes with mitochondrial energetics and ATP production, which can directly impact cardiac function. An inability to maintain proteostasis can result in mitochondrial dysfunction and subsequent mitophagy or even apoptosis. We review the known mitochondrial diseases that have been associated with cardiomyopathy and which arise from mutations in genes that are important for mitochondrial proteostasis. Genes discussed include DnaJ heat shock protein family member C19 (DNAJC19), mitochondrial import inner membrane translocase subunit TIM16 (MAGMAS), translocase of the inner mitochondrial membrane 50 (TIMM50), mitochondrial intermediate peptidase (MIPEP), X-prolyl-aminopeptidase 3 (XPNPEP3), HtraA serine peptidase 2 (HTRA2), caseinolytic mitochondrial peptidase chaperone subunit B (CLPB) and heat shock 60-kD protein 1 (HSPD1). The identification and description of disorders with a shared mechanism of disease may provide further insights into the disease process and assist with the identification of potential therapeutics.

Heat Shock Proteins Alterations in Rheumatoid Arthritis

Rheumatoid arthritis (RA) is a chronic inflammatory and autoimmune disease characterized by the attack of the immune system on the body's healthy joint lining and degeneration of articular structures. This disease involves an increased release of inflammatory mediators in the affected joint that sensitize sensory neurons and create a positive feedback loop to further enhance their release. Among these mediators, the cytokines and neuropeptides are responsible for the crippling pain and the persistent neurogenic inflammation associated with RA. More importantly, specific proteins released either centrally or peripherally have been shown to play opposing roles in the pathogenesis of this disease: an inflammatory role that mediates and increases the severity of inflammatory response and/or an anti-inflammatory and protective role that modulates the process of inflammation. In this review, we will shed light on the neuroimmune function of different members of the heat shock protein (HSPs) family and the complex manifold actions that they exert during the course of RA. Specifically, we will focus our discussion on the duality in the mechanism of action of Hsp27, Hsp60, Hsp70, and Hsp90.

HSP60 regulates the cigarette smoke-induced activation of TLR4-NF-κB-MyD88 signalling pathway and NLRP3 inflammasome

Chronic obstructive pulmonary disease (COPD) is characterized by increased cellular stress and inflammation. Heat shock protein 60 (HSP60) is a highly conserved stress protein that acts as a cellular "danger" signal for immune reactions. In this study, we investigated the role of HSP60 in COPD and explored the underlying mechanisms. Expression levels of HSP60 in patients with acute exacerbation of COPD (AECOPD), stable COPD, and healthy people were detected by Western blotting and enzyme-linked immunosorbent assay (ELISA). Moreover, the effect and molecular mechanism of HSP60 in COPD were studied in cigarette smoke (CS)-treated C57BL/6 mice and macrophages. The results showed significant upregulation of HSP60 expression in the peripheral blood mononuclear cells (PBMCs) and sera of patients with AECOPD compared to those with stable COPD or healthy people. CS induced the expression of HSP60 in the COPD mouse model, accelerated the activation of toll-like receptor 4 (TLR4) and NLR family pyrin domain containing 3 (NLRP3) signalling pathways, promoted the increase of inflammatory cells in alveolar lavage fluid and serum inflammatory factors, and induced destruction of lung tissue structure. Furthermore, HSP60 knockdown affected TLR4 and MyD88 expression, IκBα degradation, and nuclear localization of NF-κB and NLRP3 inflammasome activity. Our study revealed that CS stimulates the expression of HSP60, activating the TLR4-MyD88-NF-κB signalling pathway and the NLRP3 inflammasome.

In-depth analysis of amino acid and nucleotide sequences of Hsp60: how conserved is this protein?

Chaperonin Hsp60, as a protein found in all organisms, is of great interest in medicine, since it is present in many tissues and can be used both as a drug and as an object of targeted therapy. Hence, Hsp60 deserves a fundamental comparative analysis to assess its evolutionary characteristics. It was found that the percent identity of Hsp60 amino acid sequences both within and between phyla was not high enough to identify Hsp60s as highly conserved proteins. However, their ATP binding sites are largely conserved. The amino acid composition of Hsp60s remained relatively constant. At the same time, the analysis of the nucleotide sequences showed that GC content in the Hsp60 genes was comparable to or greater than the genomic values, which may indicate a high resistance to mutations due to tight control of the nucleotide composition by DNA repair systems. Natural selection plays a dominant role in the evolution of Hsp60 genes. The degree of mutational pressure affecting the Hsp60 genes is quite low, and its direction does not depend on taxonomy. Interestingly, for the Hsp60 genes from Chordata, Arthropoda, and Proteobacteria the exact direction of mutational pressure could not be determined. However, upon further division into classes, it was found that the direction of the mutational pressure for Hsp60 genes from Fish differs from that for other chordates. The direction of the mutational pressure affects the synonymous codon usage bias. The number of high and low represented codons increases with increasing GC content, which can improve codon usage. Special server has been created for bioinformatics analysis of Hsp60: http://oka.protres.ru:4202/.

Dexmedetomidine Alleviates Microglia-Induced Spinal Inflammation and Hyperalgesia in Neonatal Rats by Systemic Lipopolysaccharide Exposure

Noxious stimulus and painful experience in early life can induce cognitive deficits and abnormal pain sensitivity. As a major component of the outer membrane of gram-negative bacteria, lipopolysaccharide (LPS) injection mimics clinical symptoms of bacterial infections. Spinal microglial activation and the production of pro-inflammatory cytokines have been implicated in the pathogenesis of LPS-induced hyperalgesia in neonatal rats. Dexmedetomidine (DEX) possesses potent anti-neuroinflammatory and neuroprotective properties through the inhibition of microglial activation and microglial polarization toward pro-inflammatory (M1) phenotype and has been widely used in pediatric clinical practice. However, little is known about the effects of DEX on LPS-induced spinal inflammation and hyperalgesia in neonates. Here, we investigated whether systemic LPS exposure has persistent effects on spinal inflammation and hyperalgesia in neonatal rats and explored the protective role of DEX in adverse effects caused by LPS injection. Systemic LPS injections induced acute mechanical hyperalgesia, increased levels of pro-inflammatory cytokines in serum, and short-term increased expressions of pro-inflammatory cytokines and M1 microglial markers in the spinal cord of neonatal rats. Pretreatment with DEX significantly decreased inflammation and alleviated mechanical hyperalgesia induced by LPS. The inhibition of M1 microglial polarization and microglial pro-inflammatory cytokines expression in the spinal cord may implicate its neuroprotective effect, which highlights a new therapeutic target in the treatment of infection-induced hyperalgesia in neonates and preterm infants.

Crosstalk Between Intestinal Serotonergic System and Pattern Recognition Receptors on the Microbiota-Gut-Brain Axis

Disruption of the microbiota-gut-brain axis results in a wide range of pathologies that are affected, from the brain to the intestine. Gut hormones released by enteroendocrine cells to the gastrointestinal (GI) tract are important signaling molecules within this axis. In the search for the language that allows microbiota to communicate with the gut and the brain, serotonin seems to be the most important mediator. In recent years, serotonin has emerged as a key neurotransmitter in the gut-brain axis because it largely contributes to both GI and brain physiology. In addition, intestinal microbiota are crucial in serotonin signaling, which gives more relevance to the role of the serotonin as an important mediator in microbiota-host interactions. Despite the numerous investigations focused on the gut-brain axis and the pathologies associated, little is known regarding how serotonin can mediate in the microbiota-gut-brain axis. In this review, we will mainly discuss serotonergic system modulation by microbiota as a pathway of communication between intestinal microbes and the body on the microbiota-gut-brain axis, and we explore novel therapeutic approaches for GI diseases and mental disorders.

Long Noncoding RNA SNHG1 Promotes Lipopolysaccharide-Induced Activation and Inflammation in Microglia via Targeting miR-181b

INTRODUCTION

Long noncoding RNA small nuclear host gene 1 (SNHG1) was involved in neuroinflammation in microglial BV-2 cells; however, its interaction with microRNA (miR)-181b in lipopolysaccharide (LPS)-induced BV-2 cells remained poor.

METHODS

BV-2 cells were treated with LPS and then were subjected to observation on morphology and immunofluorescence staining. After transfection, levels of inflammatory cytokines interleukin-1β (IL-1β), IL-6, and tumor necrosis factor-α (TNF-α) were determined with enzyme-linked immunosorbent assay (ELISA). The potential binding sites between SNHG1 and miR-181b were confirmed using dual-luciferase reporter assay. Quantitative real-time polymerase chain reaction and Western blot were applied for detecting the mRNA and protein expressions of proinflammatory cytokines, ionized calcium-binding adapter molecule 1 (Iba1), cyclooxygenase-2 (COX-2), and inducible nitric oxide synthase (iNOS).

RESULTS

LPS led to the morphological changes and activation of BV-2 cells. The transfection of SNHG1 overexpression vector further promoted LPS-induced SNHG1 upregulation, inflammatory cytokines (IL-1β, IL-6, and TNF-α) generation and Iba-1, COX-2, and iNOS expressions, whereas silencing SNHG1 did the opposite. miR-181b functions as a downstream miRNA of SNHG1. In LPS-treated cells, the inhibition of miR-181b induced by SNHG1 promoted inflammation response and the expressions of Iba-1, COX-2, and iNOS.

CONCLUSION

SNHG1 was involved in LPS-induced microglial activation and inflammation response via targeting miR-181b, providing another evidence of the roles of SNHG1 implicated in neuroinflammation of microglia.

Mechanical Stimulation of Fibroblasts by Extracorporeal Shock Waves: Modulation of Cell Activation and Proliferation Through a Transient Proinflammatory Milieu

Extracorporeal shock waves (ESWTs) are “mechanical” waves, widely used in regenerative medicine, including soft tissue wound repair. Although already being used in the clinical practice, the mechanism of action underlying their biological activities is still not fully understood. In the present paper we tried to elucidate whether a proinflammatory effect may contribute to the regenerative potential of shock waves treatment. For this purpose, we exposed human foreskin fibroblasts (HFF1 cells) to an ESWT treatment (100 pulses using energy flux densities of 0.19 mJ/mm² at 3 Hz), followed by cell analyses after 5 min, up to 48 h. We then evaluated cell proliferation, reactive oxygen species generation, ATP release, and cytokine production. Cells cultured in the presence of lipopolysaccharide (LPS), to induce inflammation, were used as a positive control, indicating that LPS-mediated induction of a proinflammatory pattern in HFF1 increased their proliferation. Here, we provide evidence that ESWTs affected fibroblast proliferation through the overexpression of selected cytokines involved in the establishment of a proinflammatory program, superimposable to what was observed in LPS-treated cells. The possibility that inflammatory circuits can be modulated by ESWT mechanotransduction may disclose novel hypothesis on their biological underpinning and expand the fields of their biomedical application.

The Anti-Neuroinflammatory Effect of Fuzi and Ganjiang Extraction on LPS-Induced BV2 Microglia and Its Intervention Function on Depression-Like Behavior of Cancer-Related Fatigue Model Mice

The Chinese herb couple Fuzi and Ganjiang (FG) has been a classic combination of traditional Chinese medicine that is commonly used clinically in China for nearly 2000 years. Traditional Chinese medicine suggests that FG can treat various ailments, including heart failure, fatigue, gastrointestinal upset, and depression. Neuroinflammation is one of the main pathogenesis of many neurodegenerative diseases in which microglia cells play a critical role in the occurrence and development of neuroinflammation. FG has been clinically proven to have an efficient therapeutic effect on depression and other neurological disorders, but its mechanism remains unknown. Cancer-related fatigue (CRF) is a serious threat to the quality of life of cancer patients and is characterized by both physical and psychological fatigue. Recent studies have found that neuroinflammation is a key inducement leading to the occurrence and development of CRF. Traditional Chinese medicine theory believes that extreme fatigue and depressive symptoms of CRF are related to Yang deficiency, and the application of Yang tonic drugs such as Fuzi and Ganjiang can relieve CRF symptoms, but the underlying mechanisms remain unknown. In order to define whether FG can inhibit CRF depression-like behavior by suppressing neuroinflammation, we conducted a series of experimental studies in vitro and in vivo. According to the UPLC-Q-TOF/MS^E results, we speculated that there were 49 compounds in the FG extraction, among which 30 compounds were derived from Fuzi and 19 compounds were derived from Ganjiang. Our research data showed that FG can effectively reduce the production of pro-inflammatory mediators IL-6, TNF-α, ROS, NO, and PGE₂ and suppress the expression of iNOS and COX2, which were related to the inhibition of NF-κB/activation of Nrf2/HO-1 signaling pathways. In addition, our research results revealed that FG can improve the depression-like behavior performance of CRF model mice in the tail suspension test, open field test, elevated plus maze test, and forced swimming test, which were associated with the inhibition of the expression of inflammatory mediators iNOS and COX2 in the prefrontal cortex and hippocampus of CRF model mice. Those research results suggested that FG has a satisfactory effect on depression-like behavior of CRF, which was related to the inhibition of neuroinflammation.

Frutescone O from Baeckea frutescens Blocked TLR4-Mediated Myd88/NF-κB and MAPK Signaling Pathways in LPS Induced RAW264.7 Macrophages

Frutescone O was isolated from the aerial parts of Baeckea frutescens L., which was commonly used as a folk medicinal material for treating anti-inflammatory disease in South East Asia. This study aimed to investigate the anti-inflammatory activity and related signaling cascade of Frutescone O (Fru) in LPS induced RAW264.7 cells. The anti-inflammation activity of Frutescone O was determined according to the inhibitory effects on the secretion of nitric oxide (NO), expression of inducible NO synthase, and pro-inflammatory cytokines. The regulation of Myeloid differentiation factor 88 (Myd88), inhibition of NF-κB, and MAPK pathways were further investigated for molecular mechanisms. Fru significantly decreased the expression of iNOS and the production of NO in LPS-stimulated RAW264.7 cells. It also dose-dependently suppressed LPS induced expression of IL-1β, IL-6, and TNF-α. Furthermore, Fru remarkably inhibited the upregulation of NF-κB (p50) expression in the nucleus and the phosphorylation ratio of p38, JNK, ERK, and Myd88 signaling protein. The molecular docking and cellular thermal shift assay (CETSA) results indicated that Fru participated in a robust and stable interaction with the active site of TLR4-MD2. Thus, Fru suppressed the LPS induced inflammation in RAW264.7 cells by blocking the TLR4 mediated signal transduction through the NF-κB and MAPK signaling pathways and inhibiting the Myd88 and iNOS expression.

Mild magnetic nanoparticle hyperthermia promotes the disaggregation and microglia-mediated clearance of beta-amyloid plaques

The formation of beta-amyloid (Aβ) plaques is a classical hallmark of Alzheimer's disease (AD) that is associated with the promotion of neuroinflammation and subsequent neurotoxicity. Given the limited therapeutic options for targeting and clearing Aβ plaques in AD, there is an urgent need to develop effective approaches to reduce plaque accumulation. The objective of this study was to validate mild magnetic nanoparticle (MNP) hyperthermia technology as a strategy to clear Aβ deposits and determine the impact on microglia functionality. Our results demonstrated that the heating of MNPs localized to Aβ aggregates upon exposure to high frequency alternating magnetic field (AMF) was sufficient to disrupt Aβ plaques, resulting in its fragmentation. Importantly, this could facilitate the phagocytic clearance of Aβ as well as attenuate pro-inflammatory responses by human microglial cells. Our results support the feasibility of mild MNP/AMF hyperthermia as a new strategy for reducing beta-amyloid burdens in Alzheimer's disease.

The effect of Remote Ischemic Preconditioning (RIPC) on myocardial injury and inflammation in patients with severe aortic valve stenosis undergoing Transcatheter Aortic Valve Replacement (TAVΙ)

BACKGROUND

Remote ischemic preconditioning (RIPC) is being evaluated as a strategy to reduce cardiac injury and inflammation in patients undergoing diverse cardiac invasive and surgical procedures. However, it is unclear whether RIPC has protective effects in patients undergoing the transfemoral- transcatheter aortic valve implantation (TF-TAVΙ) procedure.

METHODS

Between September 2013 and September 2015, 55 random consecutive patients were prospectively assigned to receive SHAM preconditioning (SHAM, 22 patients) or Remote Ischemic Preconditioning (RIPC) (4 cycles of 5 min intermittent leg ischemia and 5 min reperfusion, 33 patients) prior to TF-TAVI. The primary endpoint was to determine the serum levels of: hs-cTn-I (necrosis), CK-18 (apoptosis), and IL-1b (inflammation). Quantification was performed using commercially available ELISA kits. Patients were sampled 1-day pre TF-TAVΙ and 24-hours post TF-TAVΙ. Secondary endpoints included: total mortality, incidence of periprocedural clinical acute myocardial infarction (AMI), acute kidney injury (AKI), and stroke.

RESULTS

22 SHAM patients and 33 RIPC patients were finally analyzed. Our data revealed no significant difference in serum levels of hs-cTn-I and CK-18 among various groups. However, in the RIPC group, the increase in IL1b level was significantly lower for 24-h post TF-TAVΙ, (p < 0.01). There were no significant differences between groups in the secondary endpoints at the follow-up interval of one month. RIPC-related adverse events were not observed.

CONCLUSIONS

Our data suggest that RIPC did not exhibit significant cardiac or kidney protective effects regarding necrosis and apoptosis in patients undergoing TF-TAVΙ. However, an important anti-inflammatory effect was detected in the RIPC group.

HSP60 Regulates Monosodium Urate Crystal-Induced Inflammation by Activating the TLR4-NF-κB-MyD88 Signaling Pathway and Disrupting Mitochondrial Function

Acute gout is an inflammatory response induced by monosodium urate (MSU) crystals. HSP60 is a highly conserved stress protein that acts as a cellular "danger" signal for immune reactions. In this study, we aimed to investigate the role and molecular mechanism of HSP60 in gout. HSP60 expression was detected in peripheral blood mononuclear cells (PBMCs) and plasma of gout patients. The effect and molecular mechanism of HSP60 in gout were studied in MSU crystals treatment macrophages and C57BL/6 mice. JC-1 probe and MitoSOX Red were used to measure the mitochondrial membrane potential (MMP) and mitochondrial reactive oxygen species (mtROS). HSP60 expression was significantly upregulated in the PBMCs and sera of patients with acute gout (AG) compared to those with intercritical gout (IG) or healthy controls (HCs). MSU crystals induced the expression and secretion of HSP60 in the macrophages. HSP60 knockdown or overexpression affects TLR4 and MyD88 expression, IκBα degradation, and the nuclear localization of NF-κB in MSU crystal-stimulated inflammation. Further, HSP60 facilitates MMP collapse and mtROS production and activates the NLRP3 inflammasome in MSU crystal-stimulated macrophages. In MSU crystal-induced arthritis mouse models pretreated with HSP60 vivo-morpholino, paw swelling, myeloperoxidase (MPO) activity, and inflammatory cell infiltration significantly decreased. Our study reveals that MSU crystal stimulates the expression of HSP60, which accelerates the TLR4-MyD88-NF-κB signaling pathway and exacerbates mitochondrial dysfunction.

Neuroinflammation in Primary Open-Angle Glaucoma

Primary open-angle glaucoma (POAG) is the second leading cause of irreversible blindness worldwide. Increasing evidence suggests oxidative damage and immune response defects are key factors contributing to glaucoma onset. Indeed, both the failure of the trabecular meshwork tissue in the conventional outflow pathway and the neuroinflammation process, which drives the neurodegeneration, seem to be linked to the age-related over-production of free radicals (i.e., mitochondrial dysfunction) and to oxidative stress-linked immunostimulatory signaling. Several previous studies have described a wide range of oxidative stress-related makers which are found in glaucomatous patients, including low levels of antioxidant defences, dysfunction/activation of glial cells, the activation of the NF-κB pathway and the up-regulation of pro-inflammatory cytokines, and so on. However, the intraocular pressure is still currently the only risk factor modifiable by medication or glaucoma surgery. This present review aims to summarize the multiple cellular processes, which promote different risk factors in glaucoma including aging, oxidative stress, trabecular meshwork defects, glial activation response, neurodegenerative insults, and the altered regulation of immune response.

Functions of p38 MAP Kinases in the Central Nervous System

Mitogen-activated protein (MAP) kinases are a central component in signaling networks in a multitude of mammalian cell types. This review covers recent advances on specific functions of p38 MAP kinases in cells of the central nervous system. Unique and specific functions of the four mammalian p38 kinases are found in all major cell types in the brain. Mechanisms of p38 activation and downstream phosphorylation substrates in these different contexts are outlined and how they contribute to functions of p38 in physiological and under disease conditions. Results in different model organisms demonstrated that p38 kinases are involved in cognitive functions, including functions related to anxiety, addiction behavior, neurotoxicity, neurodegeneration, and decision making. Finally, the role of p38 kinases in psychiatric and neurological conditions and the current progress on therapeutic inhibitors targeting p38 kinases are covered and implicate p38 kinases in a multitude of CNS-related physiological and disease states.

Abnormal lipid metabolism induced apoptosis of spermatogenic cells by increasing testicular HSP60 protein expression

Long-term consumption of high-fat and high-calorie foods not only causes obesity, but also may cause a decline in sperm quality in men. Rats with abnormal lipid metabolism (high-fat rats) were established by high-fat diet for 24 weeks. HE staining was used to observe the morphological changes of testis in rats, TUNEL and flow cytometer was used to detect the cell apoptosis in rat testis and in vitro. Immunohistochemistry and Western blotting were used to detect the expression of protein. After 24 weeks of high-fat food feeding, the body weight, serum lipids and number of apoptotic spermatogenic cells in the high-fat group rat were significantly higher than those in the control group. In vivo, the expression of HSP60 protein in testis of high-fat rats was positive related to apoptosis of spermatogenic cells, cleaved caspase 3/caspase 3 protein expression and Bax/Bcl2 protein expression in testis of high-fat rats. Proportion of apoptotic spermatogenic cells was increased by up-regulation of HSP60 protein expression in vitro. Long-term consumption of high-fat diets can cause high expression of HSP60 and spermatogenic cells apoptosis in rats, while HSP60 over-expression promotes spermatogenic cell apoptosis and MAPK signal pathway in vitro.

Heat shock protein 60 and cardiovascular diseases: An intricate love-hate story

Cardiovascular diseases (CVDs) are the result of complex pathophysiological processes in the tissues comprising the heart and blood vessels. Inflammation is the main culprit for the development of cardiovascular dysfunction, and it may be traced to cellular stress events including apoptosis, oxidative and shear stress, and cellular and humoral immune responses, all of which impair the system's structure and function. An intracellular chaperone, heat shock protein 60 (HSP60) is an intriguing example of a protein that may both be an ally and a foe for cardiovascular homeostasis; on one hand providing protection against cellular injury, and on the other triggering damaging responses through innate and adaptive immunity. In this review we will discuss the functions of HSP60 and its effects on cells and the immune system regulation, only to later address its implications in the development and progression of CVD. Lastly, we summarize the outcome of various studies targeting HSP60 as a potential therapeutic strategy for cardiovascular and other diseases.

The role of commensal microflora-induced T cell responses in glaucoma neurodegeneration

Over the last decade, new evidence has become increasingly more compelling that commensal microflora profoundly influences the maturation and function of resident immune cells in host physiology. The concept of gut-retina axis is actively being explored. Studies have revealed a critical role of commensal microbes linked with neuronal stress, immune responses, and neurodegeneration in the retina. Microbial dysbiosis changes the blood-retina barrier permeability and modulates T cell-mediated autoimmunity to contribute to the pathogenesis of retinal diseases, such as glaucoma. Heat shock proteins (HSPs), which are evolutionarily conserved, are thought to function both as neuroprotectant and pathogenic antigens of T cells contributing to cell protection and tissue damage, respectively. Activated microglia recruit and interact with T cells during this process. Glaucoma, characterized by the progressive loss of retinal ganglion cells, is the leading cause of irreversible blindness. With nearly 70 million people suffering glaucoma worldwide, which doubles the number of patients with Alzheimer's disease, it represents the most frequent neurodegenerative disease of the central nervous system (CNS). Thus, understanding the mechanism of neurodegeneration in glaucoma and its association with the function of commensal microflora may help unveil the secrets of many neurodegenerative disorders in the CNS and develop novel therapeutic interventions.

Excess administration of miR-340-5p ameliorates spinal cord injury-induced neuroinflammation and apoptosis by modulating the P38-MAPK signaling pathway

Spinal cord injury (SCI) is a destructive polyneuropathy that can result in loss of sensorimotor function and sphincter dysfunction, and even death in critical situations. MicroRNAs (miRs) are a series of non-coding RNA molecules that are involved in transcriptional regulation. Previous studies have demonstrated that modulation of multiple miRs is involved in neurological recovery after SCI. However, the functions of miR-340-5p in SCI remain uncertain. Therefore, we probed the therapeutic effect and mechanism of miR-340-5p in microglia in vitro and in vivo in SCI rats. Reverse transcription-quantitative polymerase chain reaction (RT-qPCR) and western blotting were employed to examine the alterations in miR-340-5p and P38 levels in SCI rats. miR-340-5p targets in microglia were ascertained using luciferase reporter assays, immunofluorescence analyses, and western blotting. We also established an SCI model and administered miR-340-5p. The effects of miR-340-5p on the amelioration of inflammation, oxidative stress, and apoptosis following SCI were assessed using immunofluorescence, immunohistochemistry, and histological analyses. Finally, locomotor function recovery was determined using the Basso, Beattie, Bresnahan rating scale. In our study, the expression profiles and luciferase assay results clarified that P38 was a target of miR-340-5p, which was associated with activation of the P38-MAPK signaling pathway. Elevation of miR-340-5p decreased P38 expression, subsequently inhibiting the inflammatory reaction. SCI-induced secondary neuroinflammation was relieved under miR-340-5p treatment. Moreover, by controlling neuroinflammation, the increased levels of miR-340-5p might counter oxidative stress and reduce the degree of apoptosis. We also observed decreasing gliosis and glial scar formation and increasing neurotrophin expression at the chronic stage of SCI. Together, these potential effects of miR-340-5p treatment ultimately improved locomotor function recovery in SCI rats.

Hsp60 Post-translational Modifications: Functional and Pathological Consequences

Hsp60 is a chaperone belonging to the Chaperonins of Group I and typically functions inside mitochondria in which, together with the co-chaperonin Hsp10, maintains protein homeostasis. In addition to this canonical role, Hsp60 plays many others beyond the mitochondria, for instance in the cytosol, plasma-cell membrane, extracellular space, and body fluids. These non-canonical functions include participation in inflammation, autoimmunity, carcinogenesis, cell replication, and other cellular events in health and disease. Thus, Hsp60 is a multifaceted molecule with a wide range of cellular and tissue locations and functions, which is noteworthy because there is only one hsp60 gene. The question is by what mechanism this protein can become multifaceted. Likely, one factor contributing to this diversity is post-translational modification (PTM). The amino acid sequence of Hsp60 contains many potential phosphorylation sites, and other PTMs are possible such as O-GlcNAcylation, nitration, acetylation, S-nitrosylation, citrullination, oxidation, and ubiquitination. The effect of some of these PTMs on Hsp60 functions have been examined, for instance phosphorylation has been implicated in sperm capacitation, docking of H2B and microtubule-associated proteins, mitochondrial dysfunction, tumor invasiveness, and delay or facilitation of apoptosis. Nitration was found to affect the stability of the mitochondrial permeability transition pore, to inhibit folding ability, and to perturb insulin secretion. Hyperacetylation was associated with mitochondrial failure; S-nitrosylation has an impact on mitochondrial stability and endothelial integrity; citrullination can be pro-apoptotic; oxidation has a role in the response to cellular injury and in cell migration; and ubiquitination regulates interaction with the ubiquitin-proteasome system. Future research ought to determine which PTM causes which variations in the Hsp60 molecular properties and functions, and which of them are pathogenic, causing chaperonopathies. This is an important topic considering the number of acquired Hsp60 chaperonopathies already cataloged, many of which are serious diseases without efficacious treatment.

Role of Mitochondrial Stress Protein HSP60 in Diabetes-Induced Neuroinflammation

Diabetes mellitus is the most common metabolic disorder characterized by hyperglycemia and associated malfunctions of the metabolism of carbohydrates, proteins, and lipids. There is increasing evidence of a relationship between diabetes and vascular dementia. Interestingly, hyperglycemia-linked neuroinflammation in the central nervous system is considered to play a key role during vascular dementia in diabetic patients. However, the mechanisms responsible for the relationship between hyperglycemia and neuroinflammation is not clearly understood. Diabetes-induced alternations in the blood-brain barrier permit high glucose influx into the brain cells via glucose transporters and promote oxidative stress through overproduction of reactive oxygen species. Despite many studies demonstrating a link between oxidative stress and mitochondrial dysfunction, the relationship between mitochondrial dysfunction and neuron inflammation during hyperglycemia remains to be established. In this review, we will focus on diabetes-induced changes in the central nervous system and the role of mitochondrial heat shock protein 60 (HSP60) as an initiator of oxidative stress and potential modulator of neuroinflammation. We suggest that oxidative stress-mediated mitochondrial dysfunction stimulates the upregulation of mitochondrial heat shock protein 60 (HSP60) and ultimately initiates inflammatory pathways by activating pattern recognition receptors. HSP60 also could be a focal point in the development of a biomarker of neuroinflammation as HSP60 is known to be significantly elevated in diabetic patients. Interestingly, extracellular secretion of HSP60 via exosomes suggests that inflammation could spread to neighboring astrocytes by activating pattern recognition receptors of astrocytes via neuronal exosomes containing HSP60. A mechanism for linking neuron and astrocyte inflammation will provide new therapeutic approaches to modulate neuroinflammation and therefore potentially ameliorate the cognitive impairment in diabetic brains associated with vascular dementia.

Heat shock protein 60 (HSP60) modulates adiponectin signaling by stabilizing adiponectin receptor

Adiponectin, an adipokine produced and secreted by adipocytes, is involved in regulating the development and progression of insulin resistance, diabetes, and diabetic complications. Heat shock protein 60 (HSP60) is a molecular chaperone, most commonly presenting in mitochondria and participating in the maintenance of protein homeostasis. Accumulating studies have demonstrated that the elevated circulating HSP60 and the decreased intracellular HSP60 are closely associated with diabetic complications such as diabetic cardiomyopathy. However, the underlying mechanism remains poorly understood. In the present study, we reported that HSP60 interacted directly with adiponectin receptors. Its abundance was positively associated with adiponectin action. Furthermore, HSP60 depletion markedly mitigated the protective impacts of adiponectin on high glucose-induced oxidative stress and cell apoptosis in rat cardiac H9c2 cells. In addition, HSP60 knockdown significantly enhanced proteasome activity leading to the degradation of adiponectin receptor 1. Taken together, we showed for the first time that HSP60 interacted with adiponectin receptors and mediated adiponectin signaling through stabilizing adiponectin receptor. This in vitro study also provides an alternative explanation for mechanism by which adiponectin exerts its action.

Role of Nampt overexpression in a rat model of Hashimoto's thyroiditis and its mechanism of action

The present study was designed to investigate the role of nicotinamide phosphoribosyltransferase (Nampt) overexpression in a rat model of Hashimoto's thyroiditis (HT) and its mechanism of action. A rat model of HT was constructed, and the HT rats were injected with an adenoviral expression vector carrying the Nampt gene. The expression of Nampt and Toll-like receptor 4 (TLR4) in thyroid tissues was examined using immunohistochemistry (IHC), RT-qPCR and western blot analyses. Serum anti-thyroglobulin antibodies (TGAb) and anti-thyroid peroxidase antibodies (TPOAb) were measured using chemiluminescence method. Hematoxylin and eosin (H&E) and IHC staining of the rat thyroid tissues showed destroyed thyroid follicles and monocyte infiltration, as well as increased Nampt expression in the thyroid tissues of rats with HT. Furthermore, it was found that Nampt overexpression led to increased severity of inflammatory infiltration in thyroid tissues and increased levels of TPOAb in the serum of HT rats; however, the serum TGAb level was not affected by Nampt overexpression. In addition, Nampt overexpression promoted TLR4 expression in HT rats. In conclusion, it was demonstrated that Nampt was strongly expressed in the capillary region of HT rats thyroid tissues. The Nampt mRNA level was increased but the Nampt protein level was decreased in the thyroid tissues of rats with HT. Nampt overexpression has a promotive effect on HT progression, and this effect was related to TLR4. This study suggests that inhibition of Nampt activity may be valuable in the treatment of HT.

Adaptive Immunity: New Aspects of Pathogenesis Underlying Neurodegeneration in Glaucoma and Optic Neuropathy

Glaucoma is a globally unmet medical challenge and the most prevalent neurodegenerative disease, which permanently damages the optic nerve and retinal ganglion cells (RGCs), leading to irreversible blindness. Present therapies target solely at lowering intraocular ocular pressure (IOP), a major risk factor of the disease; however, elevated IOP is neither necessary nor sufficient to cause glaucoma. Glaucomatous RGC and nerve fiber loss also occur in individuals with normal IOP. Recent studies have provided evidence indicating a link between elevated IOP and T cell-mediated autoimmune responses, particularly that are specific to heat shock proteins (HSPs), underlying the pathogenesis of neurodegeneration in glaucoma. Reactive glial responses and low-grade inflammation may initially represent an adaptive reaction of the retina to primary stress stimuli; whereas, sustained and excessive glial reactions lead to expanded immune responses, including adaptive immunity, that contribute to progressive neural damage in glaucoma. Emerging data suggest a similar mechanism in play in causing neurodegeneration of other forms of optic neuropathy, such as that resulted from acute ischemia and traumatic injuries. These studies may lead to the paradigm shift and offer a new basis for the development of novel mechanism-based diagnosis, therapy, and preventive interventions for glaucoma. As HSPs are induced under various conditions of neural stress and damage in the brain and spinal cord, these findings may have broader implications for our elucidating of the etiology of other neurodegenerative disorders in the central nervous system.

Psoriasis-Like Inflammation Induced Renal Dysfunction through the TLR/NF-κB Signal Pathway

Pathological studies have shown an association between psoriasis and renal injury (RI), but the mechanism between RI and psoriasis was still unclear. This paper was designed to investigate the relationship and mechanism between psoriasis-like inflammation and renal injury in BALB/C mice. Mice were topically smeared imiquimod followed by various analyses in skin lesions, urine protein, kidney/serum inflammatory cytokines, kidney function, podocyte membrane proteins, and toll-like receptors/nuclear factor kappa-b (TLR/NF-κB) pathway-associated proteins. Meanwhile, lipopolysaccharide (LPS) and dexamethasone (DEX) were intraperitoneally injected to promote and inhibit inflammation accompanied by imiquimod to elaborate the relevance between inflammatory levels and RI. In the model group, the Psoriasis Area and Severity Index (PASI) scores of scaly and erythema obviously increased (p < 0.01), creatinine and blood urea nitrogen significantly increased (p < 0.01), the positive area of hematoxylin-eosin (HE) and periodic acid-Schiff (PAS) staining in kidney increased (p < 0.01), malondialdehyde significantly increased with superoxide dismutase (SOD) decreased (p < 0.01), 24-hour urine protein increased and the expressions of podocin and CD2 associate protein (CD2AP) decreased (p < 0.01), and kidney/serum inflammatory factors (IL-17, IL-1β, IL-6, TNF-α, and IL-22) and TLR/NF-κB-related expression (TLR2, TLR4, MyD88, and NF-κBp65) all increased (p < 0.01). The RI was aggravated with the TLR/NF-κB related expression being upregulated by LPS (p < 0.05). On the contrary, the RI was alleviated by DEX (p < 0.05). Our data showed that psoriasis-like inflammation damaged the renal function via the TLR/NF-κB signal pathway. Inhibiting TLR/NF-κB-related protein expression may be effective for the treatment of RI caused by psoriasis.

Attenuation of paraquat-induced inflammation by inhibitors of phosphorylation of mitogen-activated protein kinases in BV2 microglial cells

Paraquat has dopaminergic neurotoxicity and potentially contributes to Parkinson's disease (PD) as a risk factor. However, the cellular and molecular mechanisms of PQ-induced neurodegeneration have not been clearly elucidated. Studies have shown that PQ induces microglial neuroinflammation through toll-like receptor 4 (TLR4)-nuclear factor-κB pathway, resulting in neuronal cell loss. Mitogen-activated protein kinases (MAPKs) are involved in the production of pro-inflammatory cytokines in microglia, and in this study, the role of MAPKs in PQ-activated microglial inflammation was investigated. Murine BV₂ microglial cells were treated with 40 μM of PQ following pretreatment of the cells with selective inhibitor of MAPKs phosphorylation for blockage of the phosphorylation of ERK, JNK and P38, or a specific TLR4 inhibitor for blocking the activation of TLR4. The protein expression of phosphorylated ERK, JNK and p38, and the transcription expression of pro-inflammatory mediators were assessed with Western blotting and qRT-PCR technique, respectively. The results indicated that PQ significantly induced the phosphorylation of ERK, JNK and P38 in microglia, while MAPKs inhibitors suppressed PQ-induced phosphorylation of ERK, JNK and P38, and reduced the transcription level of pro-inflammatory cytokines. PQ-stimulated phosphorylation of ERK, JNK and P38 was also reduced by TLR4 inhibitor. The inhibited intensity in the level of pro-inflammatory cytokine transcription was obviously greater in TLR4 inhibitor + PQ group than in each MAPK inhibitor + PQ group. Taken together, inhibition of MAPKs phosphorylation partially attenuates PQ-induced microglial inflammation, which may become a potential intervention strategy for PQ neurotoxicity.

Toll-Like Receptor 2 (TLR2) and TLR4 Mediate the IgA Immune Response Induced by Mycoplasma hyopneumoniae

IgA plays an important role in mucosal immunity against infectious pathogens; however, the molecular mechanism of IgA secretion in response to infection remains largely unknown, particularly in Mycoplasma spp. In this study, we found that the levels of IgA in the peripheral blood serum, bronchoalveolar lavage fluid, nasal mucosa, trachea, hilar lymph nodes, and lung tissues of pigs increased significantly after infection with Mycoplasma hyopneumoniae.

IgA plays an important role in mucosal immunity against infectious pathogens; however, the molecular mechanism of IgA secretion in response to infection remains largely unknown, particularly in Mycoplasma spp. In this study, we found that the levels of IgA in the peripheral blood serum, bronchoalveolar lavage fluid, nasal mucosa, trachea, hilar lymph nodes, and lung tissues of pigs increased significantly after infection with Mycoplasma hyopneumoniae. Furthermore, IgA and CD11c were detected in the lungs and hilar lymph nodes by immunohistochemical analysis, and colocalization of these two markers indicates that CD11c⁺ cells play an important role in IgA mucosal immunity induced by M. hyopneumoniae. To investigate the regulatory mechanism of IgA, we separated mouse dendritic cells (DCs) from different tissues and mouse macrophages from the lungs and then cultured mouse B cells together with either DCs or macrophages in vitro. In the mouse lung-DC/B (LDC/B) cell coculture, IgA secretion was increased significantly after the addition of whole-cell lysates of M. hyopneumoniae. The expression of both Toll-like receptor 2 (TLR2) and TLR4 was also upregulated, as determined by mRNA and protein expression analyses, whereas no obvious change in the expression of TLR3 and TLR7 was detected. Moreover, the IgA level decreased to the same as the control group when TLR2 or TLR4 was inhibited instead of TLR8 or TLR7/9. In conclusion, M. hyopneumoniae can stimulate the response of IgA through TLR2 and TLR4 in a mouse LDC/B cell coculture model, and the coculture model is an ideal tool for studying the IgA response mechanism, particularly that with Mycoplasma spp.

Exercise and Neuroinflammation in Health and Disease

Neuroinflammation is a central pathological feature of several acute and chronic brain diseases, including Alzheimer disease (AD), Parkinson disease (PD), amyotrophic lateral sclerosis (ALS), and multiple sclerosis (MS). It induces microglia activation, mitochondrial dysfunction, the production of nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB), pro-inflammatory cytokines, and reactive oxygen species. Exercise, which plays an important role in maintaining and improving brain health, might be a highly effective intervention for preventing neuroinflammation-related diseases. Thus, since exercise can improve the neuroimmune response, we hypothesized that exercise would attenuate neuroinflammation-related diseases. In this review, we will highlight (1) the biological mechanisms that underlie AD, PD, ALS, and MS, including the neuroinflammation pathways associated with microglia activation, NF-κB, pro-inflammatory cytokines, mitochondrial dysfunction, and reactive oxygen species, and (2) the role of exercise in neuroinflammation-related neurodegenerative diseases.

Cigarette smoke triggers inflammation mediated by autophagy in BEAS-2B cells

Cigarette smoking, as an individual consumption habit, is associated with a variety of related diseases. Exposure of cigarette smoke was reported to induce autophagy and inflammation in experimental animals and humans. However, the toxicity mechanism of cigarette smoke in organisms has not been entirely investigated. In this present study, we studied the role of autophagy played in the inflammation caused by cigarette smoke in human bronchial epithelial cells (BEAS-2B), as well as the role of the phosphatidylinositol 3-kinase (PI3K) signaling pathway and the mitogen-activated protein kinase (MAPK) signaling pathways underlying autophagy and inflammation. We found that cigarette smoke induced autophagy and inflammation in BEAS-2B, and the blockage of autophagy significantly reduced the release levels of IL-1β, IL-6 and IL-8 in BEAS-2B exposed to cigarette smoke for 24 h. Cigarette smoke downregulated the activity of PI3K/Akt/mTOR pathway and elevated the activity of MAPK pathways. Pretreatment of autophagic inhibitor could inhibit autophagy and the activity of JNK and p38 pathways. These results suggested that cigarette smoke-induced autophagy triggered inflammation through the activation of JNK and p38 pathways, which might contribute to understanding the adverse outcome pathways induced by cigarette smoke exposure and provide the information about the risk assessment of tobacco products.