Cornelia Kiank

Psychological Stress-Induced, IDO1-Dependent Tryptophan Catabolism: Implications on Immunosuppression in Mice and Humans

It is increasingly recognized that psychological stress influences inflammatory responses and mood. Here, we investigated whether psychological stress (combined acoustic and restraint stress) activates the tryptophan (Trp) catabolizing enzyme indoleamine 2,3-dioxygenase 1(IDO1) and thereby alters the immune homeostasis and behavior in mice. We measured IDO1 mRNA expression and plasma levels of Trp catabolites after a single 2-h stress session and in repeatedly stressed (4.5-days stress, 2-h twice a day) naïve BALB/c mice. A role of cytokines in acute stress-induced IDO1 activation was studied after IFNγ and TNFα blockade and in IDO1−/− mice. RU486 and 1-Methyl-L-tryptophan (1-MT) were used to study role of glucocorticoids and IDO1 on Trp depletion in altering the immune and behavioral response in repeatedly stressed animals. Clinical relevance was addressed by analyzing IDO1 activity in patients expecting abdominal surgery. Acute stress increased the IDO1 mRNA expression in brain, lung, spleen and Peyers patches (max. 14.1±4.9-fold in brain 6-h after stress) and resulted in a transient depletion of Trp (−25.2±6.6%) and serotonin (−27.3±4.6%) from the plasma measured 6-h after stress while kynurenine levels increased 6-h later (11.2±9.3%). IDO1 mRNA up-regulation was blocked by anti-TNFα and anti-IFNγ treatment. Continuous IDO1 blockade by 1-MT but not RU486 treatment normalized the anti-bacterial defense and attenuated increased IL-10 inducibility in splenocytes after repeated stress as it reduced the loss of body weight and behavioral alterations. Moreover, kynurenic acid which remained increased in 1-MT treated repeatedly stressed mice was identified to reduce the TNFα inducibility of splenocytes in vitro and in vivo. Thus, psychological stress stimulates cytokine-driven IDO1 activation and Trp depletion which seems to have a central role for developing stress-induced immunosuppression and behavioral alteration. Since patients showed Trp catabolism already prior to surgery, IDO is also a possible target enzyme for humans modulating immune homeostasis and mood.

Hypermetabolic Syndrome as a Consequence of Repeated Psychological Stress in Mice

Stress is a powerful modulator of neuroendocrine, behavioral, and immunological functions. After 4.5-d repeated combined acoustic and restraint stress as a murine model of chronic psychological stress, severe metabolic dysregulations became detectable in female BALB/c mice. Stress-induced alterations of metabolic processes that were found in a hepatic mRNA expression profiling were verified by in vivo analyses. Repeatedly stressed mice developed a hypermetabolic syndrome with the severe loss of lean body mass, hyperglycemia, dyslipidemia, increased amino acid turnover, and acidosis. This was associated with hypercortisolism, hyperleptinemia, insulin resistance, and hypothyroidism. In contrast, after a single acute stress exposure, changes in expression of metabolic genes were much less pronounced and predominantly confined to gluconeogenesis, probably indicating that metabolic disturbances might be initiated already early but will only manifest in repeatedly stressed mice. Thus, in our murine model, repeated stress caused severe metabolic dysregulations, leading to a drastic reduction of the individuals energy reserves. Under such circumstances stress may further reduce the ability to cope with new stressors such as infection or cancer.

Different stress-related phenotypes of BALB/c mice from in-house or vendor: alterations of the sympathetic and HPA axis responsiveness

BackgroundLaboratory routine procedures such as handling, injection, gavage or transportation are stressful events which may influence physiological parameters of laboratory animals and may interfere with the interpretation of the experimental results. Here, we investigated if female BALB/c mice derived from in-house breeding and BALB/c mice from a vendor which were shipped during their juvenile life differ in their HPA axis activity and stress responsiveness in adulthood.ResultsWe show that already transferring the home cage to another room is a stressful event which causes an increased HPA axis activation for at least 24 hours as well as a loss of circulating lymphocytes which normalizes during a few days after transportation. However and important for the interpretation of experimental data, commercially available strain-, age- and gender-matched animals that were shipped over-night showed elevated glucocorticoid levels for up to three weeks after shipment, indicating a heightened HPA axis activation and they gained less body weight during adolescence. Four weeks after shipment, these vendor-derived mice showed increased corticosterone levels at 45-min after intraperitoneal ACTH challenge but, unexpectedly, no acute stress-induced glucocorticoid release. Surprisingly, activation of monoaminergic pathways were identified to inhibit the central nervous HPA axis activation in the vendor-derived, shipped animals since depletion of monoamines by reserpine treatment could restore the stress-induced HPA axis response during acute stress.ConclusionsIn-house bred and vendor-derived BALB/c mice show a different stress-induced HPA axis response in adulthood which seems to be associated with different central monoaminergic pathway activity. The stress of shipment itself and/or differences in raising conditions, therefore, can cause the development of different stress response phenotypes which needs to be taken into account when interpreting experimental data.

Detrimental role for CD4+ T lymphocytes in murine diffuse peritonitis due to inhibition of local bacterial elimination

Background: Abdominal sepsis due to intestinal leakage of endogenous gut bacteria is a life-threatening condition. In healthy individuals, T lymphocytes have essential functions in balancing the immune response to the commensal gut flora. Aim: To determine how T lymphocytes shape the process of diffuse faecal peritonitis. Methods: In colon ascendens stent peritonitis (CASP), a clinically relevant mouse model of diffuse peritonitis, the kinetics of systemic T cell activation were investigated by assessment of activation markers. CD4+ T cells were then depleted with monoclonal antibodies, and survival, bacterial dissemination and cytokine concentrations were measured. T cell receptor signalling was blocked with tacrolimus. Results: In diffuse peritonitis, CD4+ T cells, both Foxp3− and Foxp3+, became systemically involved within hours and upregulated CTLA-4 and other activation markers. Depletion of the CD4+ T cells enhanced local bacterial clearance from the peritoneal cavity, reduced bacterial dissemination and improved survival. This was accompanied by increased immigration of granulocytes and macrophages into the peritoneum, indicating that CD4+ T cells inhibit the local innate immune response. Blockade of T cell receptor (TCR) signalling by tacrolimus did not influence the survival in this peritonitis model, showing that the inhibitory effects of the CD4+ T lymphocytes were independent of TCR-mediated antigen recognition. Conclusion: In diffuse peritonitis caused by commensal gut bacteria the CD4+ T lymphocytes exert a net negative effect on the local anti-bacterial defence, and thereby contribute to bacterial dissemination and poor outcome.

Pneumonia as a long-term consequence of chronic psychological stress in BALB/c mice.

Recently, we have shown that female BALB/c mice are highly sensitive to chronic psychological stress. They develop systemic neuroendocrine disturbances, a hypermetabolic syndrome, behavioral alterations and severe immunosuppression with a reduced antibacterial response during experimental infection. Here, we show that chronically stressed mice spontaneously suffered from increased bacterial load in the liver and lung that sustained for up to 10 days after the termination of stress exposure. Immediately after the last chronic stress cycle, splenocytes had a reduced ability to produce IFNgamma after ex vivo stimulation with LPS while showing enhanced inducibility of IL-10. When healthy animals were treated with anti-IFNgamma antiserum the antibacterial response against the small numbers of endogenous bacteria that physiologically penetrate the intestinal barrier was reduced causing increased bacterial burden in the liver. Thus, a deficient antibacterial response to translocated commensals in chronically stressed animals can contribute to long-lasting pneumonia.

#73 Protection from severe chronic stress-induced immune depression and sickness behavior by inhibition of indoleamine-2,3-dioxygenase

depression and sickness behavior by inhibition of indoleamine-2,3-dioxygenase Cornelia Kiank , Jan-Philip Zeden , GerhardFusch ,Nam T. Nguyen , Astrid Starke , Alice Mundt , Alexandra Westerholt , Johannes-Peter Haas , Christine Schutt a a Department of Immunology, University of Greifswald b Department of Surgery, University of Greifswald c Department of Pediatrics, Division of Neonatology and Pedriatic Intensive Care, University of Greifswald

72 Chronic psychological stress severely impairs innate and adaptive immune competence and induces sickness behavior in mice

The deleterious effect of stress on antibody production has historically been attributed to acute elevations in norepinephrine (NE). However, stressor exposure also depletes splenic NE by 50 min after stressor onset. This effect persists for 2 h after stressor termination, but recovers by 4 h after stressor termination. Recent work in our laboratory revealed that the stress-induced suppression of antibody could be prevented by maintaining normal splenic NE content during stressor exposure, despite exposure to acute elevations in NE concentration. Sufficient splenic NE content may be necessary for optimal activation of B cells, and it may therefore be necessary for proper generation of antibody response. The purpose of this study was to examine the effect of a transient decrease in NE content on generation of an of antibody response to the T-cell dependent antigen keyhole limpet hemocyanin (KLH). There is basal activity of the central noradrenergic system, and consequently there is turnover of NE even under resting conditions. a-Methyl-p-tyrosine (AMPT) competitively binds tyrosine hydroxylase, preventing NE synthesis, leading to a reduction in NE content. Adult, male, Fischer 344 rats were injected with AMPT and sacrificed after 10, 50, 100, 210, or 330 min. AMPT reduced NE content of the spleen by 100 min, and NE depletion persisted through 330 min. A second group of animals was immunized with KLH 60 min after AMPT or saline injection to mimic the window of NE depletion caused by stress. Animals immunized with AMPT demonstrated a suppression in anti-KLH IgM and IgG in comparison to saline injected animals. Interestingly, also similar to stressed animals, IgG2a, but not IgG1, was suppressed after AMPT injection. These data support that splenic NE depletion is sufficient to cause a selective suppression in in vivo antibody production to a T-cell dependent antigen.

131 Acute stress is followed by enhanced tryptophan catabolism

Astrid Starke , Nam T. Nguyen , Jan-Philip Zeden , Cornelia Kiank , Georg Daeschlein , Gerhard Fusch , Alice Mundt , Johannes-Peter Haas , Alexandra Westerholt , Christine Schutt a a Department of Immunology, University of Greifswald, Germany b Department of Surgery, University of Greifswald, Germany c Department of Pediatrics, Division of Neonatology and Pedriatic Intensive Care, University of Greifswald, Germany d Institute of Hygiene and Environmental Medicine, University of Greifswald, Germany