Electric foot-shock stress drives TNF-alpha production in the liver of IL-6-deficient mice

Enhancing ASPP2 promotes acute liver injury via an inflammatory immunoregulatory mechanism

Background

Acute liver injury (ALI), which is a type of inflammation-mediated hepatocellular injury, is a clinical syndrome that results from hepatocellular apoptosis and hemorrhagic necrosis. Apoptosis stimulating protein of p53-2 (ASPP2) is a proapoptotic member of the p53 binding protein family. However, the role of ASPP2 in the pathogenesis of ALI and its regulatory mechanisms remain unclear.

Methods

The expression of ASPP2 were compared between liver biopsies derived from patients with CHB, patients with ALI, and normal controls. Acute liver injury was modelled in mice by administration of D-GalN/LPS. Liver injury was demonstrated by serum transaminases and histological assessment of liver sections. ASPP2-knockdown mice (ASPP2+/-) were used to determine its role in acute liver injury. Mouse bone marrow macrophages (BMMs) were isolated from wildtype and ASPP2+/- mice and stimulated with LPS, and the supernatant was collected to incubate with the primary hepatocytes. Quantitative real-time PCR and western blot were used to analyze the expression level of target.

Results

The expression of ASPP2 was significantly upregulated in the liver tissue of ALI patients and acute liver injury mice. ASPP2+/- mice significantly relieved liver injury through reducing liver inflammation and decreasing hepatocyte apoptosis. Moreover, the conditioned medium (CM) of ASPP2+/- bone marrow-derived macrophages (BMMs) protected hepatocytes against apoptosis. Mechanistically, we revealed that ASPP2 deficiency in BMMs specifically upregulated IL-6 through autophagy activation, which decreased the level of TNF-α to reduce hepatocytes apoptosis. Furthermore, up-regulation of ASPP2 sensitizes hepatocytes to TNF-α-induced apoptosis.

Conclusion

Our novel findings show the critical role of ASPP2 in inflammatory immunoregulatory mechanism of ALI and provide a rationale to target ASPP2 as a refined therapeutic strategy to ameliorate acute liver injury.

Association between increased inflammatory cytokine expression in the lateral habenular nucleus and depressive-like behavior induced by unpredictable chronic stress in rats

Depression induced by unpredictable chronic stress (UCS) has been widely studied using animal models. However, its underlying pathological mechanisms remain unclear. Increased inflammatory cytokines (ICs) in the central nervous system (CNS) are closely related to depressive disorder. UCS was used as an animal model in this study to investigate how UCS-induced changes in cytokine signaling lead to depression. We found that UCS could increase ICs in the CNS, especially in the habenular nucleus (Hb). UCS resulted in decreased expression of Menin in Hb and increased the activation of the NF-κB signaling pathway. Local administration of tumor necrosis factor-α in the lateral Hb (LHb) could induce depressive-like behavior in rats. The anti-inflammatory drug aspirin and the NF-κB inhibitor pyrrolidine dithiocarbamate could alleviate depressive-like behavior. This phenomenon was not observed for local administration in the dorsal raphe nucleus and paraventricular nucleus. These results indicate that LHb is the main central target for ICs to regulate depressive-like behaviors. We also found that LHb lesions could improve the inflammatory response in the hippocampus, reduce the activation of the NF-κB signaling pathway and the expression of ICs, and increase the expression of brain-derived neurotrophic factor and its receptor tropomyosin receptor kinase B, collectively improving the neuroinflammation caused by UCS. Moreover, LHb lesions improve not only hippocampal neurogenesis damage caused by UCS by activating the PI3K/mTOR signaling pathway but also hippocampal function by reducing the expression of apoptosis-related proteins, including phosphorylated p53, Bax, Bcl2, and cleaved-caspase3. In conclusion, our study sheds light on the pathogenesis of ICs-induced depression. Anti-inflammation in the CNS could be a new strategy in the treatment of depression.

An Herbal Formula CGplus Ameliorates Stress-Induced Hepatic Injury in a BALB/c Mouse Model

Introduction

Stress is a well-known factor for inflammation in diverse organs/tissues. Stress also leads to liver injury, which was supported by clinical observations and animal studies. We herein investigated the hepatoprotective property of an herbal formula (called as CG^plus) consisting of Artemisia gmelinii Weber ex Stechm. (syn, Artemisia iwayomogi Kitamura), Wurfbainia villosa var. xanthioides (Wall. ex Baker) Skornick. & A.D.Poulsen (syn, Amomum xanthioides Wallich), and Salvia miltiorrhiza Bunge against stress-induced hepatic damage.

Methods

Male BALB/c mice were orally administered water extract of CG^plus (0, 50, 100, or 200 mg/kg) daily for 5 days, and then subjected to immobilization stress for 6 h on the 5^th day.

Results

Acute immobilization stress elevated remarkably serum concentrations of stress hormones (corticosterone and adrenaline) and two hepatic injury parameters (ALT and AST), while these alterations were significantly attenuated by the administration of CG^plus. The increases of oxidative parameters (ROS, NO, lipid peroxidation, and protein carbonyl) and deviation of IL-1β and IL-10 in opposite directions in hepatic tissues were significantly normalized by CG^plus. Pre-treatment with CG^plus also notably ameliorated the abnormal activation of toll-like receptor 4 (TLR4), CD14, and lipopolysaccharide-binding protein (LPB) as well as infiltration of neutrophils in hepatic tissues.

Conclusion

These results suggest that an herbal formula (CG^plus) derived from traditional pharmaceutical theory has a potent protective effect against stress-induced hepatic injury via regulation of pro- (IL-1β) and anti-inflammatory (IL-10) cytokines.

Effect of Selank on Morphological Parameters of Rat Liver in Chronic Foot-Shock Stress

We studied the effects of Selank on morphological parameters of the liver in Wistar male rats subjected to chronic foot-shock stress. Selank was injected intraperitoneally in doses of 100, 300 and 1000 μg/kg 15 min before each stress session. Morphological and morphometrical analysis showed that chronic foot-shock stress induced hydropic degeneration of hepatocytes, an increase of the nucleus/cytoplasm ratio due to an increase in the area of nuclei and reduction of the cytoplasm area, the appearance of focal necroses, and lymphohistiocyte infiltration. Injection of Selank in all doses reduced the intensity of stress-induced degenerative changes. Administration of Selank in doses of 300 and 1000 μg/kg restored the nucleus/cytoplasm ratio in hepatocytes. The maximum stress-limiting effect was attained after administration of 300 μg/kg Selank.

A literature review for the mechanisms of stress-induced liver injury

INTRODUCTION

Experimental studies and clinical observations have shown that stress can damage hepatic tissue both directly and indirectly. Many studies have partially revealed the contributors of stress-induced liver injury; however, the whole process has not yet been uncovered. This review aims to summarize the mechanisms that have been proposed to be involved.

METHODS

A literature search was conducted using PubMed (http://www.ncbi.nlm.nih.gov/pubmed) in its entirety up to March 2018, and analyzed the animal-derived mechanistic studies on stress-induced liver injury.

RESULTS

The liver is the organ that meets and filters a mass of alien material, and then maintains immune tolerance under physiological conditions. Under stress conditions, however, immune tolerance is interrupted, which results in the induction of inflammation in the liver. Contributors to this process can be categorized as follows: hypoxia-reoxygenation, over-activation of Kupffer cells and oxidative stress, influx of gut-derived lipopolysaccharide and norepinephrine, and over-production of stress hormones and activation of the sympathetic nerve.

CONCLUSIONS

Psychological stress is associated with a variety of pathological conditions resulting in liver injury through multiple systems, including the sympathetic nervous and adrenocortical system. Mechanistic understanding of this phenomenon is important for the clinical practice of managing patients with hepatic disorders and should be explored further in the future.

Chronic restraint stress reduces carbon tetrachloride-induced liver fibrosis

Stress as a cofactor has been reported to affect the progression and severity of liver diseases. The present study investigated the effect of chronic restraint stress on carbon tetrachloride (CCl₄)-induced liver fibrosis. A total of 30 male BALB/c mice were randomly divided into three groups: Oil-treated control group; CCl₄-treated group; and CCl₄ + restraint-treated group. CCl₄ was administrated via intraperitoneal injection once every 3 days over a period of 42 days. In the CCl₄ + restraint-treated group, mice were immobilized using 50 ml centrifuge tubes for 0.5 h to inflict chronic restraint stress immediately after the injection of CCl₄. On day 42, blood and liver tissue samples were collected for analysis. The effect of restraint on CCl₄-induced liver fibrosis in mice was evaluated by analyzing the serum levels of alanine aminotransferase (ALT) and aspartate aminotransferase (AST). Histopathological examination of liver samples was performed using hematoxylin and eosin (HE), Masson's trichrome, 5-hydroxytryptamine 2B (5-HT2B) receptor and α-smooth muscle actin (α-SMA) immumohistochemical staining. ALT, AST, 5-HT2B receptor and α-SMA expression levels were significantly increased in mice exposed to CCl₄ in comparison with those in the oil-treated control mice (P<0.01). However, these increases were significantly reduced by exposure to restraint (P<0.05). HE and Masson's trichrome staining revealed that restraint can alleviate CCl₄-induced liver fibrosis. These results suggest that chronic restraint stress reduces the development of liver fibrosis by inhibiting the activation of hepatic stellate cells via 5-HT2B receptor. Therefore, restraint may be a useful therapeutic approach in the management of liver fibrosis.

The role of alpha-1 and alpha-2 adrenoceptors in restraint stress-induced liver injury in mice

Acute stress affects cellular integrity in many tissues including the liver, but its underlying mechanism is still unclear. The aim of the present study was to investigate the potential involvement of catecholamines and adrenoceptors in the regulation of acute restraint stress-induced liver injury. Restraint was achieved by placing mice in restraint tubes. Mice were treated with either an α-l antagonist, prazosin, an α-2 antagonist, yohimbine, a β-l antagonist, betaxolol, a β-2 antagonist, ICI 118551, or a central and peripheral catecholamine depleting agent, reserpine, and followed by restraint stress. Assessment of liver injury (serum alanine aminotransferase (ALT), aspartate aminotransferase (AST) , hepatic total GSH, GSSG and GSH/GSSG ratio) , histopathology and of apoptosis, by TUNEL (terminal deoxynucleotidyl transferase-mediated dUTP nick-end labelling) assay and western blotting, was performed. Three hours of restraint stress resulted in liver injury, as indexed by elevated serum transaminase levels, decreased hepatic total GSH levels and GSH/GSSG ratio, increased hepatic GSSG levels as well as enhanced hepatocytes apoptosis. Either reserpine or prazosin or yohimbine was found to attenuate liver injury. Furthermore, prazosin and yohimbine protected against restraint-induced hepatocytes apoptosis through attenuating the activation of caspases-9 and -3 and reducing the Bax/Bcl-2 ratio. These results suggest that α-1 and α-2 adrenoceptors mediate restraint-induced liver oxidative injury through caspase-9 and Bcl-2 family of apoptotic regulatory proteins.

Enhancement of Anxiety and Modulation of TH and pERK Expressions in Amygdala by Repeated Injections of Corticosterone

Repeated stress induces corticosterone release. However, it is not clear that stress results in further elevation of corticosterone levels, and the roles of released corticosterone to aggravate stress-related symptoms are also not clear. This study investigated whether neuronal modulation was induced in the amygdala after two kinds of stress, that is, such as electric shock and corticosterone injection. It was found that stress by electric shock decreased the expression of tyrosine hydoroxylase (TH) in the amygdala while the expression of pERK was increased. However, there is no difference in the expressions of TH and pERK in the frontal cortex compared with those of the control group. The level of corticosterone was significantly increased in the serum after stress. To determine the effect of corticosterone on the induction of anxiety and the expression of TH, the rats received corticosterone (20 mg or 40 mg/kg i.p.) for 1 day, 1 week, 2 weeks and 3 weeks, respectively. The spent time in open arms of the EPM (elevated plus maze) test was significantly decreased after 1 week, 2 weeks and 3 weeks. The time spent in open arms of the EPM test after repeated injections of corticosterone was significantly decreased in a dose-dependent manner. The expression of TH in the amygdala was reduced after following repeated corticosterone treatment for 2 weeks and 3 weeks. Collectively, this study suggests that corticosterone has a major role in the induction of anxiety and the modulation of TH expression, at least, in the amygdala.

The effects of exercise withdrawal on mood and inflammatory cytokine responses in humans

Mechanisms underlying the relationship between exercise and mood are not well understood. This study sought to investigate the role of pro- and anti-inflammatory cytokines and autonomic balance in determining the impact of exercise withdrawal on negative mood. Healthy men and women who regularly exercised (N = 26, mean age = 25.5 years, SD = 4.5 years) were randomised to exercise withdrawal or exercise maintenance for 2 weeks. Protocol adherence was monitored using accelerometers. Inflammatory markers from plasma (interleukin-6, IL-6; tumour necrosis factor-alpha; interleukin-10; and interleukin-1 receptor antagonist), heart-rate variability (HRV) and measures of mood (General Health Questionnaire-28 (GHQ) and the Profile of Mood States (POMS)) were assessed at study entry and at 2-week follow-up. Exercise withdrawal resulted in significant increases in negative mood over time on both the GHQ (p = 0.028) and the POMS (p = 0.005). Following the intervention, IL-6 concentration was lower in the exercise withdrawal than exercise maintenance condition (p = 0.05). No intervention effects were observed for other cytokines or HRV. The mood changes were significantly related to changes in IL-6 concentration (β = - 0.50, p = 0.011), indicating that reduction in IL-6 was related to increased negative mood. Our results are consistent with positive effects of exercise on mental health, but further research on inflammatory pathways is warranted.

Pyrogenic cytokines did not mediate a stress interview-induced hyperthermic response in a patient with psychogenic fever: a case report

OBJECTIVE

To investigate if pyrogenic cytokines mediated psychological stress-induced hyperthermic response in a patient with psychogenic fever. Despite many case reports on psychogenic fever, the mechanism responsible for how psychological stress increases core body temperature (Tc) in humans is not yet known.

CASE PRESENTATION

A 13-year-old girl with fever (>38 degrees C) of unknown causes was referred to our department because psychogenic fever was suspected. To determine if the fever was actually induced by psychological stress, we conducted a 60-minute stress interview. Her baseline oral temperature was 36.60 degrees C and it began to increase immediately after commencement of the interview, reaching a maximum of 37.42 degrees C 20 minutes after the end of the interview. The plasma level of prostaglandin E(2) and the serum interleukin-6 level were increased 90 minutes after the interview. Serum levels of interleukin-1alpha, interleukin-1beta, and macrophage inflammatory protein-1alpha were all less than their minimum detectable level throughout the observation period. We also measured the patient's thermal preference by immersing her hands in warm (40 degrees C) and cold (20 degrees C) water. Her preference changed from cold to warm only during the increasing phase of oral temperature.

CONCLUSIONS

This case report shows that a stress interview actually increased Tc in a patient with psychogenic fever. This study suggests that, although pyrogenic cytokines are not involved, the stress interview-induced increase in Tc was an active hyperthermia under the control of the brain, as is infection-induced fever.

Atherosclerotic plaque disruption induced by stress and lipopolysaccharide in apolipoprotein E knockout mice

To establish an animal model with disruptions of atherosclerotic plaques, 96 male apolipoprotein E knockout (apoE(-/-)) mice were randomly divided into stress, lipopolysaccharide (LPS), stress+LPS, and control groups (n = 24 each). All mice were fed a high-fat diet throughout the experiment, and carotid atherosclerotic lesions were induced by placement of a constrictive perivascular collar. Four weeks after surgery, mice in the LPS and stress+LPS groups were intraperitoneally injected with LPS (1 mg/kg twice per week for 8 wk). Eight weeks after surgery, mice in the stress and stress+LPS groups were treated with intermittent physical stress (electric foot shock and noise stimulation) for 4 wk. Morphological analysis revealed a plaque disruption rate of 16.7% in control, 34.8% in LPS, 54.2% in stress, and 60.9% in stress+LPS groups. The disruption rates in stress and stress+LPS groups were both significantly higher than those of controls (P = 0.007 and P = 0.002, respectively). Luminal thrombosis secondary to plaque disruption was observed only in the stress+LPS group. Both stress and LPS stimulation significantly decreased fibrous cap thickness and increased macrophage and lipid contents in plaques. Moreover, the combination of stress and LPS stimulation further lowered cap thickness and enhanced accumulation of macrophages and expression of inflammatory cytokines and matrix metalloproteinases. Stress activated the sympathetic nervous system, as manifested by increased blood pressure and flow velocity. Plasma fibrinogen levels were remarkably elevated in the stress and stress+LPS groups. In conclusion, stress- and LPS-costimulated apoE(-/-) mice provide a useful model for studies of plaque vulnerability and interventions.

Interleukin-1 signaling modulates stress-induced analgesia

Exposure to stressful stimuli is often accompanied by reduced pain sensitivity, termed "stress-induced analgesia" (SIA). In the present study, the hypothesis that interleukin-1 (IL-1) may play a modulatory role in SIA was examined. Two genetic mouse models impaired in IL-1-signaling and their wild-type (WT) controls were employed. Another group of C57 mice was acutely administered with IL-1 receptor antagonist (IL-1ra). Mice were exposed to 2min swim stress at one of three water temperatures: 32 degrees C (mild stress), 20-23 degrees C (moderate stress), or 15 degrees C (severe stress); and then tested for pain sensitivity using the hot-plate test. Corticosterone levels were assessed in separate groups of WT and mutant mice following exposure to the three types of stress. Mild stress induced significant analgesia in the two WT strains and saline-treated mice, but not in the mutant strains or the IL-1ra-treated mice. Similarly, mild stress induced significantly elevated corticosterone levels in WT mice, and blunted corticosterone response in mutant mice. In contrast, both WT and mutant strains, as well as IL-1ra-treated mice, displayed analgesic and corticosterone responses following moderate and severe stress. Interestingly, the analgesic response to moderate stress was markedly potentiated in the mutant strains, as compared with their WT controls. The present results support our previous findings that in the absence of IL-1, stress response to mild stress is noticeably diminished. However, the analgesic response to moderate stress is markedly potentiated in mice with impaired IL-1 signaling, corroborating the anti-analgesic role of IL-1 in several pain modulatory conditions, including SIA.

Early-life psychological stress exacerbates adult mouse asthma via the hypothalamus-pituitary-adrenal axis

RATIONALE

Despite accumulating evidence that psychological stress has a short-lasting detrimental effect on asthma, little is known about the way stress in childhood predisposes to adult asthma.

OBJECTIVES

Using a communication box, we investigated the long-lasting effect of early psychological and physical stress on adult asthma in mice.

METHODS

Male BALB/c mice were exposed to either psychological stress or physical stress three times (every other day) during their fourth week of life. The mice were sensitized to ovalbumin at 8 and 10 weeks, and an ovalbumin airway challenge was conducted at the age of 11 weeks.

RESULTS

Twenty-four hours after ovalbumin challenge, both psychological and physical stress-exposed mice exhibited a significant acceleration in the number of total mononuclear cells and eosinophils and airway hyperresponsiveness compared with control mice. No differences in serum anti-OVA-specific immunoglobulin E levels were found between stress-exposed and control animals after antigen sensitization. In the psychological stress group, but not in the physical stress group, an elevation of the serum corticosterone levels during ovalbumin challenge was significantly attenuated in comparison with the control group. Moreover, pretreatment with RU-486, a glucocorticoid receptor antagonist, before ovalbumin challenge completely inhibited a psychological stress-induced exacerbation of asthma. However, pretreatment with GR-82334, a neurokinin-1 receptor antagonist, failed to affect physical stress-induced augmentation of airway inflammation.

CONCLUSION

Early psychological and physical stresses aggravated adult asthma via hyporesponsiveness of the hypothalamic-pituitary-adrenal axis during antigen challenge and via a pathway(s) distinct from the hypothalamic-pituitary-adrenal axis or neurokinin-1 receptors.

Insights from knock-out models concerning postischemic release of TNFalpha from isolated mouse hearts

The inflammatory cytokine tumor necrosis factor alpha (TNFalpha) is controversially discussed in ischemia/reperfusion damage of the heart. Purpose of this study was to elucidate cellular sources of TNFalpha and parameters which possibly influence its release in the heart following ischemia. Isolated hearts of mice were subjected to 15 min of global ischemia and 90 min of reperfusion. We employed hearts of various mice knock-out strains (interleukin-6(-/-), matrix metalloprotease-7(-/-), mast-cell deficient WBB6F1-Kit(W)/Kit(W-v), TNF-R1(-/-)) and wildtype mice, the latter perfused without and with infusion of cycloheximide or TNFalpha-cleaving-enzyme inhibitor (TAPI-2). Normoxic control hearts showed basal release of TNFalpha during the whole experiment. Immunohistology identified cardiac mast cells, macrophages and endothelial cells as main sources. TNFalpha release was stimulated during postischemic reperfusion, occurring in a two-peak pattern: directly after ischemia (0-10 min) and again after 60-90 min. The first peak mainly reflects tissue washout of TNFalpha accumulated during ischemia. The second, protracted peak arose continuously from the basal level and was abolished by protein synthesis inhibitor cycloheximide. Both properties are characteristic for de novo synthesis of TNFalpha, e.g., in cardiac muscle cells. However, immunohistological staining for TNFalpha failed in cardiomyocytes after 90 min of reperfusion. In contrast to hearts of TNF-R1(-/-) and Kit(W/W-v)-mice, those of IL-6(-/-) and MMP-7(-/-) mice lacked the late TNFalpha peak. TAPI did not suppress release of TNFalpha. While autostimulation via TNF-R1 also does not seem obligatory and mast cell can be ignored as source of the second peak, IL-6 may support de novo synthesis of TNFalpha. Additionally, TNFalpha release may essentially involve cleavage of membrane bound TNFalpha by MMP-7.

Does stress exacerbate liver diseases?

Although anecdotal comments on detrimental effects of psychosocial stress on liver diseases can be found even in the early literature, only recently has scientific evidence been reported. The present article reviewed such evidence to demonstrate how stress exacerbates liver diseases. A search of the literature from the last two decades was performed using MEDLINE by pairing 'psychological stress' with 'liver' or 'hepatitis.' Additional research was conducted by screening the bibliographies of articles retrieved in the MEDLINE search. The search results showed that the principal effectors of the activated hypothalamic-pituitary-adrenal (HPA) axis, glucocorticoids, can exert a facilitative effect on the hepatic inflammatory response and even increase the risk of developing hepatocellular carcinoma. For certain liver diseases, defective HPA axis activation, which probably contributed to the exacerbation of the liver disease, has been reported. The efferent sympathetic/adrenomedullary system mainly contributes to the stress-induced exacerbation of liver diseases via its neurotransmitters, the catecholamines. In contrast, the efferent parasympathetic nervous system elicits an inhibitory effect on the development of hepatic inflammation. In conclusion, the pathophysiological interaction between stress and the liver appears to be regulated by the complex, dynamic networks of both the endocrine and autonomic nervous systems, which implies a further need for basic research into the involved mechanisms and for clinical evidence to apply psychosocial support to patients with chronic liver diseases.

Social disruption stress exacerbates alpha-galactosylceramide-induced hepatitis in mice

OBJECTIVE

Psychosocial stress has been suggested as a possible aggravating factor in liver diseases, however, the underlying mechanism has yet to be clarified. Recently, our research revealed that electric foot-shock stress aggravated NK1.1 Ag(+) T cell-dependent alpha-galactosylceramide (alpha-GalCer)-induced hepatitis in mice via a mechanism mediated by endogenous glucocorticoids. In this study, we examined whether or not such aggravation could be applied to a psychosocially stressful situation, e.g. social disruption stress.

METHODS

Male wild-type C57BL/6 (B6) or B6 hepatitis virus type B surface antigen transgenic (HBs-tg) mice, a hepatitis B virus carrier mouse model, were exposed 3 times in 1 week to social disruption stress in which an 8-month-old aggressive male intruder was placed into their home cage (5 mice per group) for 2 h. Twelve hours after the final exposure to the stress, the wild-type and HBs-tg mice were intravenously injected with alpha-GalCer.

RESULTS

The stress-exposed wild-type mice exhibited significantly reduced thymus weight loss compared with the control animals. Moreover, this stress regimen led to a significant increase in serum alanine aminotransferase levels in both the wild-type and the HBs-tg mice, although the increase in the HBs-tg mice was higher than that in the wild-type mice.

CONCLUSION

These findings demonstrated that, similar to electric foot-shock stress, social disruption stress exacerbated alpha-GalCer-induced hepatitis.