Chronic restraint stress decreases the repair potential from mesenchymal stem cells on liver injury by inhibiting TGF-β1 generation

Metabolomics reveals that chronic restraint stress alleviates carbon tetrachloride-induced hepatic fibrosis through the INSR/PI3K/AKT/AMPK pathway

Hepatic fibrosis (HF) could be developed into liver cirrhosis or even hepatocellular carcinoma. Stress has an important role in the occurrence and development of various considerable diseases. However, the effect of a certain degree stress on HF is still controversial. In our study, stress was simulated with regular chronic restraint stress (CRS) and HF model was induced with CCl4 in mice. We found that CRS was able to attenuate CCl4-induced liver injury and fibrosis in mice. Surprisingly, behavioral analysis showed that the mice in the HF group exhibited depression-like behavior. Further, the metabolomic analysis revealed that 119 metabolites and 20 metabolic pathways were altered in mice liver, especially the betaine metabolism pathway. Combined with the results of Ingenuity Pathway Analysis (IPA), the key proteins INSR, PI3K, AKT, and p-AMPK were identified and verified, and the results showed that CRS could upregulate the protein levels and mRNA expression of INSR, PI3K, AKT, and p-AMPK in liver tissues of HF mice. It suggested that CRS alleviated CCl4-induced liver fibrosis in mice through upregulation of the INSR/PI3K/AKT/AMPK pathway. Proper stress might be a potential therapeutic strategy for the treatment of chronic liver disease, which provided new insights into the treatment of HF. KEY MESSAGES: Chronic restraint stress mitigated CCl4-induced liver injury and hepatic fibrosis. CCl4-induced liver fibrosis could cause depression-like behavior. Chronic restraint stress altered metabolomic profiles in hepatic fibrosis mice, especially the betaine metabolism pathway. Chronic restraint stress increased betaine levels in liver tissue. Chronic restraint stress regulated the INSR/PI3K/AKT/AMPK signaling pathway in hepatic fibrosis mice.

Therapeutic potential of stem cells in regeneration of liver in chronic liver diseases: Current perspectives and future challenges

The deposition of extracellular matrix and hyperplasia of connective tissue characterizes chronic liver disease called hepatic fibrosis. Progression of hepatic fibrosis may lead to hepatocellular carcinoma. At this stage, only liver transplantation is a viable option. However, the number of possible liver donors is less than the number of patients needing transplantation. Consequently, alternative cell therapies based on non-stem cells (e.g., fibroblasts, chondrocytes, keratinocytes, and hepatocytes) therapy may be able to postpone hepatic disease, but they are often ineffective. Thus, novel stem cell-based therapeutics might be potentially important cutting-edge approaches for treating liver diseases and reducing patient' suffering. Several signaling pathways provide targets for stem cell interventions. These include pathways such as TGF-β, STAT3/BCL-2, NADPH oxidase, Raf/MEK/ERK, Notch, and Wnt/β-catenin. Moreover, mesenchymal stem cells (MSCs) stimulate interleukin (IL)-10, which inhibits T-cells and converts M1 macrophages into M2 macrophages, producing an anti-inflammatory environment. Furthermore, it inhibits the action of CD4+ and CD8+ T cells and reduces the activity of TNF-α and interferon cytokines by enhancing IL-4 synthesis. Consequently, the immunomodulatory and anti-inflammatory capabilities of MSCs make them an attractive therapeutic approach. Importantly, MSCs can inhibit the activation of hepatic stellate cells, causing their apoptosis and subsequent promotion of hepatocyte proliferation, thereby replacing dead hepatocytes and reducing liver fibrosis. This review discusses the multidimensional therapeutic role of stem cells as cell-based therapeutics in liver fibrosis.

Restraint stress promotes nonalcoholic steatohepatitis by regulating the farnesoid X receptor/NLRP3 signaling pathway

Psychological stress promotes nonalcoholic steatohepatitis (NASH) development. However, the pathogenesis of psychological stress-induced NASH remains unclear. This study aims to explore the underlying mechanism of restraint stress-induced NASH, which mimics psychological stress, and to discover potential NASH candidates. Methionine choline deficient diet- and high fat diet-induced hepatosteatotic mice are subjected to restraint stress to induce NASH. The mice are administrated with Xiaoyaosan granules, NOD-like receptor family pyrin domain containing 3 (NLRP3) inhibitors, farnesoid X receptor (FXR) agonists, or macrophage scavengers. Pathological changes and NLRP3 signaling in the liver are determined. These results demonstrate that restraint stress promotes hepatic inflammation and fibrosis in hepatosteatotic mice. Restraint stress increases the expressions of NLRP3, Caspase-1, Gasdermin D, interleukin-1β, cholesterol 7α-hydroxylase, and sterol 12α-hydroxylase and decreases the expression of FXR in NASH mice. Xiaoyaosan granules reverse hepatic inflammation and fibrosis and target FXR and NLRP3 signals. In addition, inhibition of NLRP3 reduces the NLRP3 inflammasome and liver damage in mice with restraint stress-induced NASH. Elimination of macrophages and activation of FXR also attenuate inflammation and fibrosis by inhibiting NLRP3 signaling. However, NLRP3 inhibitors or macrophage scavengers fail to affect the expression of FXR. In conclusion, restraint stress promotes NASH-related inflammation and fibrosis by regulating the FXR/NLRP3 signaling pathway. Xiaoyaosan granules, NLRP3 inhibitors, FXR agonists, and macrophage scavengers are potential candidates for the treatment of psychological stress-related NASH.

Orchestration of Mesenchymal Stem/Stromal Cells and Inflammation During Wound Healing

Wound healing is a complex process and encompasses a number of overlapping phases, during which coordinated inflammatory responses following tissue injury play dominant roles in triggering evolutionarily highly conserved principals governing tissue repair and regeneration. Among all nonimmune cells involved in the process, mesenchymal stem/stromal cells (MSCs) are most intensely investigated and have been shown to play fundamental roles in orchestrating wound healing and regeneration through interaction with the ordered inflammatory processes. Despite recent progress and encouraging results, an informed view of the scope of this evolutionarily conserved biological process requires a clear understanding of the dynamic interplay between MSCs and the immune systems in the process of wound healing. In this review, we outline current insights into the ways in which MSCs sense and modulate inflammation undergoing the process of wound healing, highlighting the central role of neutrophils, macrophages, and T cells during the interaction. We also draw attention to the specific effects of MSC-based therapy on different pathological wound healing. Finally, we discuss how ongoing scientific advances in MSCs could be efficiently translated into clinical strategies, focusing on the current limitations and gaps that remain to be overcome for achieving preferred functional tissue regeneration.

Mesenchymal stromal cells in hepatic fibrosis/cirrhosis: from pathogenesis to treatment

Hepatic fibrosis/cirrhosis is a significant health burden worldwide, resulting in liver failure or hepatocellular carcinoma (HCC) and accounting for many deaths each year. The pathogenesis of hepatic fibrosis/cirrhosis is very complex, which makes treatment challenging. Endogenous mesenchymal stromal cells (MSCs) have been shown to play pivotal roles in the pathogenesis of hepatic fibrosis. Paradoxically, exogenous MSCs have also been used in clinical trials for liver cirrhosis, and their effectiveness has been observed in most completed clinical trials. There are still many issues to be resolved to promote the use of MSCs in the clinic in the future. In this review, we will examine the controversial role of MSCs in the pathogenesis and treatment of hepatic fibrosis/cirrhosis. We also investigated the clinical trials involving MSCs in liver cirrhosis, summarized the parameters that need to be standardized, and discussed how to promote the use of MSCs from a clinical perspective.

Immunomodulatory role of mesenchymal stem cell therapy in liver fibrosis

Liver fibrosis is a fibrogenic and inflammatory process that results from hepatocyte injury and is characterized by hepatic architectural distortion and resultant loss of liver function. There is no effective treatment for advanced fibrosis other than liver transplantation, but it is limited by expensive costs, immune rejection, and postoperative complications. With the development of regenerative medicine in recent years, mesenchymal stem cell (MSCs) transplantation has become the most promising treatment for liver fibrosis. The underlying mechanisms of MSC anti-fibrotic effects include hepatocyte differentiation, paracrine, and immunomodulation, with immunomodulation playing a central role. This review discusses the immune cells involved in liver fibrosis, the immunomodulatory properties of MSCs, and the immunomodulation mechanisms of MSC-based strategies to attenuate liver fibrosis. Meanwhile, we discuss the current challenges and future directions as well.

Effect of chronic stress on tumorigenesis and development

Chronic stress activates the sympathetic nervous system (SNS) and hypothalamic-pituitary-adrenal (HPA) axis to aggravates tumorigenesis and development. Although the importance of SNS and HPA in maintaining homeostasis has already attracted much attention, there is still a lot remained unknown about the molecular mechanisms by which chronic stress influence the occurrence and development of tumor. While some researches have already concluded the mechanisms underlying the effect of chronic stress on tumor, complicated processes of tumor progression resulted in effects of chronic stress on various stages of tumor remains elusive. In this reviews we concluded recent research progresses of chronic stress and its effects on premalignancy, tumorigenesis and tumor development, we comprehensively summarized the molecular mechanisms in between. And we highlight the available treatments and potential therapies for stressed patients with tumor.

Hypoxic preconditioning promotes the immunosuppressive effects of mesenchymal stem cells in mice with colitis

Mesenchymal stem cells are promising candidates for stem cell therapy in many diseases, especially in immune-associated diseases. Inflammatory bowel disease is a chronic autoimmune disease that can lead to colorectal cancer if it is not controlled. Mesenchymal stem cells are always under a hypoxic environment in vivo, whether in bone marrow or adipose tissue, whereas researchers always culture MSCs (mesenchymal stem cells) under normoxic conditions (21%). In this study, we aimed to investigate whether hypoxia (1%) affects the therapeutic effect of MSCs. We hypothesize that hypoxia may benefit the treatment efficacy of MSCs. We used DSS to induce IBD (inflammatory bowel disease) in mice and then injected MSCs that had been preconditioned under normoxic conditions (21%) and hypoxic conditions (1%). We found that compared with normoxic-preconditioned MSCs (n-MSCs), hypoxic-preconditioned MSCs (h-MSCs) could alleviate colon inflammation to a large extent, as determined by inflammatory cytokines and CD3+ T cell activation. Mechanistic studies showed that hypoxia could promote iNOS expression in MSCs. Therefore, our data suggest that hypoxia may be more appropriate than normoxia for facilitating MSCs exertion of therapeutic functions.

Hydrocortisone Long-term Treatment Effect on Immunomodulatory Properties of Human Adipose-Derived Mesenchymal Stromal/Stem Cells

Cortisol is secreted in prolonged stress and has therapeutic effects in inflammatory diseases. Considering the immunomodulatory effects of mesenchymal stem cells, here we investigated the effect of hydrocortisone (HC) long-term treatment on immunomodulatory properties of human adipose-derived mesenchymal stromal/stem cells (ASCs). Isolated ASCs from healthy subjects were treated with different HC concentrations for 14 days. The effect of HC-treated ASCs on the proliferative response of peripheral blood mononuclear cells (PBMCs) was evaluated in ASCs/2-way mixed leukocyte reaction coculture using 2,3-bis-(2-methoxy-4-nitro-5-sulfophenyl)-2H-tetrazolium-5-carboxanilide (XTT)-assay. HC-treated ASCs were further divided into interferon gamma (IFN-γ) stimulated and unstimulated groups. Transforming growth factor beta 1 (TGF-β1) and interleukin (IL)-6 levels were measured in culture supernatants by enzyme-linked immunosorbent assay. Relative expression of cyclooxygenase-2 (COX-2), hepatocyte growth factor, indoleamine dioxygenase, and programmed death-ligand 1 genes was assessed by real-time PCR. Levels of TGF-β1 and COX-2 expression were elevated in unstimulated ASCs, while exposure to high concentration of HC significantly increased TGF-β1 levels and reduced COX-2 expression. Unstimulated HC-5-μM-treated ASCs increased PBMC proliferation ratio on day 2 of coculture compared to the control group (P = 0.05). In IFN-γ stimulated condition, pretreatment with HC-5 μM resulted in a significantly increased IL-6 and significantly decreased COX-2 expression compared to the HC untreated control group. In conclusion, our results showed various alterations of ASC immunomodulatory related features as a result of long-term exposure of different concentrations of HC. It seems that HC at low concentration pushed the balance toward extended immune response in ASCs, while this observation wasn't persistent in ASCs treated with higher concentrations of HC.

Stem Cell-based Therapy Strategy for Hepatic Fibrosis by Targeting Intrahepatic Cells

The whole liver transplantation is the most effective treatment for end-stage fibrosis. However, the lack of available donors, immune rejection and total cost of surgery remain as the key challenges in advancing liver fibrosis therapeutics. Due to the multi-differentiation and low immunogenicity of stem cells, treatment of liver fibrosis with stem cells has been considered as a valuable new therapeutic modality. The pathological progression of liver fibrosis is closely related to the changes in the activities of intrahepatic cells. Damaged hepatocytes, activated Kupffer cells and other inflammatory cells lead to hepatic stellate cells (HSCs) activation, further promoting apoptosis of damaged hepatocytes, while stem cells can work on fibrosis-related intrahepatic cells through relevant transduction pathways. Herein, this article elucidates the phenomena and the mechanisms of the crosstalk between various types of stem cells and intrahepatic cells including HSCs and hepatocytes in the treatment of liver fibrosis. Then, the important influences of chemical compositions, mechanical properties and blood flow on liver fibrosis models with stem cell treatment are emphasized. Clinical trials on stem cell-based therapy for liver fibrosis are also briefly summarized. Finally, continuing challenges and future directions of stem cell-based therapy for hepatic fibrosis are discussed. In short, stem cells play an important advantage and have a great potential in treating liver fibrosis by interacting with intrahepatic cells. Clarifying how stem cells interact with intrahepatic cells to change the progression of liver fibrosis is of great significance for a deeper understanding of liver fibrosis mechanisms and targeted therapy.

Autophagy controls mesenchymal stem cell therapy in psychological stress colitis mice

Mesenchymal stem cell transplantation (MSCT) has been applied to treat a variety of autoimmune and inflammatory diseases. Psychosocial stress can aggravate disease progression in chronic inflammatory patients. Whether psychological stress affects MSCT is largely unknown. In this study we show that psychological stress attenuates therapeutic effects of MSCT in a DSS-induced colitis mouse model by elevating the levels of exosomal Mir7k/mmu-let-7 k (microRNA 7 k) in circulation. Mechanistically, Mir7k inhibits STAT3 pathway in donor MSCs, leading to upregulated expression of BECN1 (beclin 1, autophagy related) and, thus, activation of macroautophagy/autophagy. Inhibition of autophagy by blocking Mir7k or activating STAT3 signaling can restore MSCT-mediated therapy in psychologically stressed colitis mice. Our study identifies a previously unknown role of autophagy in regulating MSCT therapy via exosomal miRNA Mir7k.Abbreviations: BafA1: bafilomycin A₁; BECN1: beclin 1, autophagy related; DAI: disease activity index; DAPI: 4',6-diamidino-2-phenylindole; DSS: dextran sulfate sodium; GFP: green fluorescent protein; HAI: histological activity index; IFNG/IFN-γ: interferon gamma; IL10: interleukin 10; IL1RN/IL-1Rra: interleukin 1 receptor antagonist; KD: knockdown; miRNA: microRNA; MSCs: mesenchymal stem cells; MSCT: mesenchymal stem cell transplantation; NTA: nanoparticle tracking analysis; PGE2: prostaglandin E2; SD: standard deviation; siRNA: small-interfering RNA; STAT3: signal transducer and activator of transcription 3; TEM: transmission electron microscopy; TGFB1/TGF-β1: transforming growth factor, beta 1; Th17 cell: T helper cell 17; TNF/TNF-α: tumor necrosis factor; TNFAIP6/TSG6: tumor necrosis factor alpha induced protein 6; Tregs: regulatory T cells.

Pathological Effects of Cortisol on Intervertebral Disc Cells and Mesenchymal Stem Cells from Lower Back Pain Patients

In western countries, lower back pain (LBP) is one of the most common disorders, experienced by more than 80% of the population. Chronic LBP due to disc degeneration has been linked to ongoing inflammatory processes in the disc and endplates. Pain effects the body in different ways, inducing a general stress response in which the body responds by releasing the stress hormone cortisol. Little is known about the impact of pain-induced stress on the progression of disc degeneration. Thus, the effects of cortisol on disc cells (DCs) and human mesenchymal stem cells (hMSCs) were explored in vitro with the objective of investigating the repercussions of cortisol on these cell types involved in de- and regenerative mechanisms of the disc. DC and hMSC pellet cultures were exposed to cortisol at two concentrations (150 and 300 ng/mL) for 28 days to simulate pain-induced stress. Cell viability, histological staining, and GAG DNA, along with apo-ptotic assays were conducted. Detection of OCT4, SOX9, IL-1R, and CXCR2 expressions was performed by immunohistochemistry. With cortisol treatment, restricted cell proliferation and less GAG production in both DCs and hMSCs were observed. Suppression of the differentiation and immunomodulatory efficacy of hMSCs was also detected. Moreover, elevated expressions of IL-1R and CXCR2 were detected in both cell types. To conclude, constant exposure to cortisol even at a physiological level enhanced pathological cellular processes in both DCs and hMSCs, which further jeopardized chondrogenesis. This suggests that cortisol resulting from pain-induced stress is a contributing component of intervertebral disc degeneration and may negatively affect regenerative attempts of the disc.

The distinct roles of mesenchymal stem cells in the initial and progressive stage of hepatocarcinoma

Increasing evidences suggest that mesenchymal stem cells (MSCs) could migrate to the tumor site and play a vital role in tumorigenesis and progression. However, it is still a lively debate whether MSCs exert a pro- or anticancer action. Cancer development and progression is a multistep process. Therefore, we investigated the effect of MSCs on hepatocarcinoma and whether the role of MSCs depends on the stage of cancer development. In our study, chronically exposing rats to N-diethylnitrosamine (DEN) was employed as hepatocarcinoma model. And to evaluate the effect of MSCs on hepatocarcinoma, the animals were divided into three groups: rats were injected with MSCs in the initial (DEN + MSC (Is) group) or progressive stage (DEN + MSC (Ps) group) of hepatocarcinoma, respectively. Rats injected with PBS were used as control (DEN group). Interestingly, we found that MSCs had a tumor-suppressive effect in the Is of hepatocarcinoma, yet a tumor-promotive effect in the Ps. In the Is, MSCs showed a protective role against drug damage, possibly through reducing DNA damage and ROS accumulation. Meanwhile, MSCs in the Is also exhibited anti-inflammatory and anti-liver fibrosis effect. Further, in the Ps, MSCs facilitated tumor formation not only by enhancing cancer cell proliferation but also through promoting stem cell-like properties and epithelial–mesenchymal transition of liver cancer cells. Taken together, MSCs have a paradoxical role in the different stages of hepatocarcinogenesis, which sheds new light on the role of MSCs in hepatocarcinoma and cautions the therapeutic application of MSCs for liver cancer.

Mesenchymal stem cells overexpressing Sirt1 inhibit prostate cancer growth by recruiting natural killer cells and macrophages

Prostate cancer (PCa) has become the second leading cause of male cancer-related mortality in the United States. Mesenchymal stem cells (MSCs) are able to migrate to tumor tissues, and are thus considered to be novel antitumor carriers. However, due to their immunosuppressive nature, the application of MSCs in PCa therapy remains limited. In this study, we investigated the effect of MSCs overexpressing an NAD-dependent deacetylase sirtuin 1 (MSCs-Sirt1) on prostate tumor growth, and we analyzed the underlying mechanisms. Our results show that MSCs accelerate prostate tumor growth, whereas MSCs-Sirt1 significantly suppresses tumor growth. Natural killer (NK) cells and macrophages are the prominent antitumor effectors of the MSCs-Sirt1-induced antitumor activity. IFN-γ and C-X-C motif chemokine ligand 10 (CXCL10) are highly expressed in MSCs-Sirt1 mice. The antitumor effect of MSCs-Sirt1 is weakened when CXCL10 and IFN-γ are inhibited. These results show that MSCs-Sirt1 can effectively inhibit prostate cancer growthrecruiting NK cells and macrophages in a tumor inflammatory microenvironment.

Bone marrow-derived mesenchymal stem cells induced by inflammatory cytokines produce angiogenetic factors and promote prostate cancer growth

Background

Prostate is susceptible to infection and pro-inflammatory agents in a man’s whole life. Chronic inflammation might play important roles in the development and progression of prostate cancer. Mesenchymal stem cells (MSCs) are often recruited to the tumor microenvironment due to local inflammation. We have asked whether stimulation of MSCs by pro-inflammatory cytokines could promote prostate tumor growth. The current study investigated the possible involvement of MSCs stimulated by pro-inflammatory cytokines in promotion and angiogenesis of prostate cancer through relative pathway in vitro and in vivo.

Methods

A syngeneic mouse model of C57 was established. The murine prostate cancer cells (RM-1) mixing with MSCs treated with tumor necrosis factor alpha (TNF-α) and interferon gamma (IFN-γ) or vehicle were subcutaneously injected into C57 mice. Tumor volume of C57 mouse model was estimated and serum level of platelet-derived growth factor (PDGF) and vascular endothelial growth factor (VEGF) was test by Enzyme-linked Immunosorbent Assay (ELISA). A hen egg test-chorioallantoic membrane (HET-CAM) assay was applied to test the effect of conditioned media of stimulated MSCs in chorioallantoic membrane angiogenesis. Short interfering RNA (siRNA) knocked down either hypoxia-inducible factor-1alpha (HIF-1α) or nuclear factor-erythroid-2-related factor 2 (NRF2) were employed. mRNA of PDGF and VEGF in MSCs, as well as NRF2 and HIF-1α was test by Real time polymerase chain reaction (PCR) analyses. Protein expression levels of PDGF and VEGF from conditioned medium, NRF2, HIF-1α, as well as PDGF and VEGF in MSCs were detected by Western blot analysis.

Results

MSCs treated with TNF-α and IFN-γ promote tumor growth in C57 syngeneic mouse model, correlating with increased serum level of PDGF, VEGF. HET-CAM assay shows the angiogenic effect of conditioned medium of MSCs pre-treated with the pro-inflammatory cytokines. mRNA and protein levels of two pro-angiogenic factors (PDGF and VEGF) and key hypoxia regulators (HIF-1α and NRF2) in MSCs were induced after MSCs’ pretreatment. siRNA knockdown either HIF-1α or NRF2 results reduction of PDGF and VEGF expression.

Conclusions

MSCs stimulated by pro-inflammatory cytokines increase the expression of PDGF and VEGF via the NRF2-HIF-1α pathway and accelerate prostate cancer growth in mice.

Electronic supplementary material

The online version of this article (10.1186/s12885-017-3879-z) contains supplementary material, which is available to authorized users.

Repetitive restraint stress changes spleen immune cell subsets through glucocorticoid receptor or β-adrenergic receptor in a stage dependent manner

Immune system is sensitive to stress. Spleen is the largest peripheral immune organ innervated with sympathetic nerves and controlled by adrenomedullary system in the body. However, the alterations and mechanism of spleen immune cell subsets caused by repetitive restraint stress (RRS) is poorly understood. In this study, we found that RRS reduced spleen index in mice, and induced an expansion of white pulp and involution of the red pulp. Meanwhile, the percentage of CD3⁺CD8⁺ T lymphocytes, CD11b⁺F4/80⁺ macrophages, CD11b⁺Ly-6G^-Ly-6C^hi monocytic myeloid derived suppressor cells (mMDSCs) and CD11b⁺Ly-6G⁺Ly-6C^int granulocytic myeloid derived suppressor cells (gMDSCs) in spleen were significantly changed by RRS. Mechanistically, we found that the expression of norepinephrine (NE) and β-adrenergic receptor (β-AR) in spleen were up-regulated after 21 days of RRS, but not 7 days. The expression of corticosterone (CORT) and glucocorticoid receptor (GR) in spleen were up-regulated after 7 days of RRS but were lower after 21 days of RRS, even though they were still higher than that in mice without stress. By treating the stressed mice with RU486 (antagonist of GR) or propranolol (antagonist of β-AR), we demonstrated that GR was responsible for the changes of spleen induced by 7 days of RRS and β-AR was for 21 days of RRS. Our data suggest that RRS changes spleen immune cell subsets through GR or β-AR in a stage dependent manner.

Histone deacetylase-2 is involved in stress-induced cognitive impairment via histone deacetylation and PI3K/AKT signaling pathway modification

Exposure to chronic stress upregulates blood glucocorticoid levels and impairs cognition via diverse epigenetic mechanisms, such as histone deacetylation. Histone deacetylation can lead to transcriptional silencing of many proteins involved in cognition and may also cause learning and memory dysfunction. Histone deacetylase-2 (HDAC2) has been demonstrated to epigenetically block cognition via a reduction in the histone acetylation level; however, it is unknown whether HDAC2 is involved in the cognitive decline induced by chronic stress. To the best of authors' knowledge, this is the first study to demonstrate that the stress hormone corticosteroid upregulate HDAC2 protein levels in neuro-2a cells and cause cell injuries. HDAC2 knockdown resulted in a significant amelioration of the pathological changes in N2a cells via the upregulation of histone acetylation and modifications in the phosphoinositide 3-kinase/protein kinase B signaling pathway. In addition, the HDAC2 protein levels were upregulated in 12-month-old female C57BL/6J mice under chronic stress in vivo. Taken together, these findings suggested that HDAC2 may be an important negative regulator involved in chronic stress-induced cognitive impairment.

Repeated exposure to far infrared ray attenuates acute restraint stress in mice via inhibition of JAK2/STAT3 signaling pathway by induction of glutathione peroxidase-1

Exposure to far-infrared ray (FIR) has been shown to exert beneficial effects on cardiovascular and emotional disorders. However, the precise underlying mechanism mediated by FIR remains undetermined. Since restraint stress induces cardiovascular and emotional disorders, the present study investigated whether exposure to FIR affects acute restraint stress (ARS) in mice. c-Fos-immunoreactivity (IR) was significantly increased in the paraventricular hypothalamic nucleus (PVN) and dorsomedial hypothalamic nucleus (DMH) in response to ARS. The increase in c-Fos-IR parallels that in oxidative burdens in the hypothalamus against ARS. Exposure to FIR significantly attenuated increases in the c-Fos-IR, oxidative burdens and corticosterone level. ARS elicited decreases in GSH/GSSG ratio, cytosolic Cu/Zn-superoxide dismutase (SOD-1), glutathione peroxidase (GPx), and glutathione reductase (GR) activities. FIR-mediated attenuation was particularly observed in ARS-induced decrease in GPx, but not in SOD-1 or GR activity. Consistently, ARS-induced decreases in GPx-1-immunoreactivity in PVN and DMH, and decreases in GPx-1 expression in the hypothalamus were significantly attenuated by FIR. ARS-induced significant increases in phosphorylation of JAK2/STAT3, and nuclear translocation and DNA-binding activity of NFκB were observed in the hypothalamus. Exposure to FIR selectively attenuated phosphorylation of JAK2/STAT3, but did not diminish nuclear translocation and DNA-binding activity of NFκB, suggesting that JAK2/STAT3 constitutes a critical target for FIR-mediated pharmacological potential. ARS-induced increase in c-Fos-IR in the PVN and DMH of non-transgenic mice was significantly attenuated by FIR exposure or JAK2/STAT3 inhibitor AG490. GPx-1 overexpressing transgenic mice significantly protected increases in the c-Fos-IR and corticosterone level induced by ARS. However, neither FIR exposure nor AG490 significantly affected attenuations by genetic overexpression of GPx-1. Moreover, AG490 did not exhibit any additional positive effects against the attenuation by genetic overexpression of GPx-1 or FIR exposure. Our results indicate that exposure to FIR significantly protects ARS-induced increases in c-Fos-IR and oxidative burdens via inhibition of JAK2/STAT3 signaling by induction of GPx-1.