Anti-Inflammatory effects of antidepressants through suppression of the interferon-gamma/interleukin-10 production ratio

The antidepressant venlafaxine ameliorates murine experimental autoimmune encephalomyelitis by suppression of pro-inflammatory cytokines

Antidepressants are known to impact on the immune system. In this study, we examined the immunomodulatory properties of venlafaxine, a selective serotonin/norepinephrine reuptake inhibitor (SNRI), in murine experimental autoimmune encephalomyelitis (EAE), a T-cell-mediated CNS demyelinating disease model of multiple sclerosis. EAE was induced in SJL/J mice by adoptive transfer of myelin-specific T cells. Mice received different doses of venlafaxine before induction and after onset of disease. Sustained daily oral treatment with 6, 20 and 60 mg/kg significantly ameliorated the clinical symptoms of the disease compared to vehicle during both preventive and therapeutic intervention. Venlafaxine suppressed the generation of pro-inflammatory cytokines IL-12 p40, TNF-alpha and IFN-gamma in encephalitogenic T-cell clones, splenocytes and peritoneal macrophages in vitro. It also diminished mRNA expression of a number of inflammatory genes in the inflamed CNS tissue, among them CD3, CD8, Granzyme B, IL-12 p40, IFN-gamma, TNF-alpha and the chemokines Ccl2 and RANTES, whereas the expression of brain-derived neurotrophic factor was increased. These findings demonstrate the strong immunomodulatory property of the selective SNRI venlafaxine. Further studies are warranted to clarify whether venlafaxine may exert similar effects in humans.

Immune system dysregulation in adolescent major depressive disorder

BACKGROUND

A large body of evidence suggests that immune system dysregulation is associated with Major Depressive Disorder (MDD) in adults. This study extends this work to adolescent MDD to examine the hypotheses of immune system dysregulation in adolescents with MDD, as manifested by significantly: (i) elevated plasma levels of cytokines (interferon [IFN]-gamma, tumor necrosis factor-alpha, interleukin [IL]-6, IL-1beta, and IL-4); and (ii) Th1/Th2 cytokine imbalance shifted toward Th1 as indexed by increased IFN-gamma/IL-4.

METHOD

Thirty adolescents with MDD (19 females; 13 medication-free/naïve; ages 12-19) of at least 6 weeks duration and a minimum severity score of 40 on the Children's Depression Rating Scale-Revised, and 15 healthy comparisons (8 females), group-matched for age, were enrolled. Plasma cytokines were examined using enzyme-linked immunosorbent assay. Mann-Whitney test was used to compare subjects with MDD and controls.

RESULTS

Adolescents with MDD had significantly elevated plasma IFN-gamma levels (3.38+/-11.8 pg/ml versus 0.37+/-0.64 pg/ml; p<0.003), and IFN-gamma/IL-4 ratio (16.6+/-56.5 versus 1.76+/-2.28; p=0.007). A trend for IL-6 to be elevated in the MDD group was also observed (1.52+/-2.88 pg/ml versus 0.49+/-0.90 pg/ml; p=0.09). Importantly, findings remained evident when medicated subjects were excluded.

CONCLUSIONS

Findings suggest that immune system dysregulation may be associated with adolescent MDD, with an imbalance of Th1/Th2 shifted toward Th1, as documented in adult MDD. Larger studies with medication-free adolescents should follow.

The inflammatory & neurodegenerative (I&ND) hypothesis of depression: leads for future research and new drug developments in depression

Despite extensive research, the current theories on serotonergic dysfunctions and cortisol hypersecretion do not provide sufficient explanations for the nature of depression. Rational treatments aimed at causal factors of depression are not available yet. With the currently available antidepressant drugs, which mainly target serotonin, less than two thirds of depressed patients achieve remission. There is now evidence that inflammatory and neurodegenerative (I&ND) processes play an important role in depression and that enhanced neurodegeneration in depression may-at least partly-be caused by inflammatory processes. Multiple inflammatory-cytokines, oxygen radical damage, tryptophan catabolites-and neurodegenerative biomarkers have been established in patients with depression and these findings are corroborated by animal models of depression. A number of vulnerability factors may predispose towards depression by enhancing inflammatory reactions, e.g. lower peptidase activities (dipeptidyl-peptidase IV, DPP IV), lower omega-3 polyunsaturated levels and an increased gut permeability (leaky gut). The cytokine hypothesis considers that external, e.g. psychosocial stressors, and internal stressors, e.g. organic inflammatory disorders or conditions, such as the postpartum period, may trigger depression via inflammatory processes. Most if not all antidepressants have specific anti-inflammatory effects, while restoration of decreased neurogenesis, which may be induced by inflammatory processes, may be related to the therapeutic efficacy of antidepressant treatments. Future research to disentangle the complex etiology of depression calls for a powerful paradigm shift, i.e. by means of a high throughput-high quality screening, including functional genetics and genotyping microarrays; established and novel animal and ex vivo-in vitro models for depression, such as new transgenic mouse models and endophenotype-based animal models, specific cell lines, in vivo and ex vivo electroporation, and organotypic brain slice culture models. This screening will allow to: 1) discover new I&ND biomarkers, both at the level of gene expression and the phenotype; and elucidate the underlying molecular I&ND pathways causing depression; and 2) identify new therapeutic targets in the I&ND pathways; develop new anti-I&ND drugs for these targets; select existing anti-I&ND drugs or substances that could augment the efficacy of antidepressants; and predict therapeutic response by genetic I&ND profiles.

Review series on helminths, immune modulation and the hygiene hypothesis: the broader implications of the hygiene hypothesis

Man has moved rapidly from the hunter-gatherer environment to the living conditions of the rich industrialized countries. The hygiene hypothesis suggests that the resulting changed and reduced pattern of exposure to microorganisms has led to disordered regulation of the immune system, and hence to increases in certain inflammatory disorders. The concept began with the allergic disorders, but there are now good reasons for extending it to autoimmunity, inflammatory bowel disease, neuroinflammatory disorders, atherosclerosis, depression associated with raised inflammatory cytokines, and some cancers. This review discusses these possibilities in the context of Darwinian medicine, which uses knowledge of evolution to cast light on human diseases. The Darwinian approach enables one to correctly identify some of the organisms that are important for the 'Hygiene' or 'Old Friends' hypothesis, and to point to the potential exploitation of these organisms or their components in novel types of prophylaxis with applications in several branches of medicine.

Effects of fluoxetine on mast cell morphology and protease-1 expression in gastric antrum in a rat model of depression

AIM: To investigate the effects of fluoxetine on depression-induced changes of mast cell morphology and protease-1 (rMCP-1) expression in rats.

METHODS: A Sprague-Dawley rat model of chronic stress-induced depression was established. Fifty experimental rats were randomly divided into the following groups: normal control group, fluoxetine + normal control group, depressed model group, saline + depressed model group, and fluoxetine + depressed model group. Laser scanning confocal microscopy (LSCM) immunofluorescence and RT-PCR techniques were used to investigate rMCP-1 expression in gastric antrum. Mast cell morphology was observed under transmission electron microscopy. ANOVA was used for statistical analysis among groups.

RESULTS: Morphologic observation indicated that depression induced mast cell proliferation, activation, and granule hyperplasia. Compared with the normal control group, the average immunofluorescence intensity of gastric antrum rMCP-1 significantly increased in depressed model group (37.4 ± 7.7 vs 24.5 ± 5.6, P < 0.01) or saline + depressed model group (39.9 ± 5.0 vs 24.5 ± 5.6, P < 0.01), while there was no significant difference between fluoxetine + normal control group (23.1 ± 3.4) or fluoxetine + depressed model group (26.1 ± 3.6) and normal control group. The average level of rMCP-1mRNA of gastric antrum significantly increased in depressed model group (0.759 ± 0.357 vs 0.476 ± 0.029, P < 0.01) or saline + depressed model group (0.781 ± 0.451 vs 0.476 ± 0.029, P < 0.01 ), while no significant difference was found between fluoxetine + normal control group (0.460 ± 0.027) or fluoxetine + depressed model group (0.488 ± 0.030) and normal control group. Fluoxetine showed partial inhibitive effects on mast cell ultrastructural alterations and de-regulated rMCP-1 expression in gastric antrum of the depressed rat model.

CONCLUSION: Chronic stress can induce mast cell proliferation, activation, and granule hyperplasia in gastric antrum. Fluoxetine counteracts such changes in the depressed rat model.

Do desipramine [10,11-dihydro-5-[3-(methylamino) propyl]-5H-dibenz[b,f]azepine monohydrochloride] and fluoxetine [N-methyl-3-phenyl-3-[4-(trifluoromethyl)phenoxy]-propan-1-amine] ameliorate the extent of colonic damage induced by acetic acid in rats?

The present study was designed to compare the anti-inflammatory and antioxidant effects of two antidepressant drugs, desipramine [10,11-dihydro-5-[3-(methylamino) propyl]-5H-dibenz-[b,f]azepine monohydrochloride] and fluoxetine [N-methyl-3-phenyl-3-[4-(trifluoromethyl)phenoxy]-propan-1-amine], administered with variable doses, on experimentally induced colitis in rats. Two doses for each drug (10 and 20 mg/kg/day i.p.) were injected in 48 adult male albino rats for 2 weeks after induction of colitis by intracolonic administration of 2 ml of 3% acetic acid. Several parameters, including macroscopic (ulcer score index) and biochemical such as myeloperoxidase (MPO), reduced glutathione (GSH), tumor necrosis factor (TNF)-alpha, and interleukin (IL)-1beta, were measured using standard assay procedures. The study demonstrates that both desipramine and fluoxetine significantly attenuated the extent and the severity of the macroscopic signs of cell damage. Both drugs significantly reduced tissue MPO activity in a dose-dependent manner. Both desipramine and fluoxetine, at either dose, significantly increased GSH in colonic tissue. Desipramine and fluoxetine, at either dose, significantly reduced TNF-alpha and IL-beta. Desipramine at the dose of 20 mg/kg produced more decrease in the level of TNF-alpha compared with the effect of the smaller dose, but fluoxetine at 10 mg/kg diminished more in the level of IL-1beta compared with the effect of the larger dose. The present data indicate that both desipramine and fluoxetine have anti-inflammatory and antioxidants effects in experimentally induced colitis in rats, opening the avenue to their possible protective role in patients with inflammatory bowel disease.

IL-10 modulates depressive-like behavior

The role of pro-inflammatory cytokines in psychiatric disorders has been the focus of great research attention in recent years. Paradoxically, the same is not true for anti-inflammatory cytokines. In the present study, we assessed the behavioral profile of animals with altered expression of the anti-inflammatory cytokine IL-10. We performed a battery of tests to assess anxiety, depressive-like and cognitive behaviors in mice overexpressing IL-10 (PMT10) and IL-10(-/-) animals; in the later mice we also tested the behavioral effect of IL-10 administration. In the forced-swimming test, IL-10(-/-) females displayed increased depressive-like behavior; importantly, this phenotype was reverted by the injection of IL-10. Moreover, mice overexpressing IL-10 presented a decreased depressive-like behavior. Despite the presence of a similar trend, male animals did not reach significant differences in depressive-like behavior. Assessment in the open-field showed that the absence of IL-10 decreased the percentage of time spent in the center of the arena in both male and female mice, while male animals overexpressing IL-10 revealed an opposite behavior. For both sexes, imbalance in IL-10 levels did not affect spatial reference memory. In conclusion, variations in IL-10 expression are associated with an altered depressive-like behavior, but do not influence cognitive performance. Interestingly, IL-10 imbalance produced more profound behavioral changes in females than in male animals. This is in accordance with clinical data demonstrating an increased susceptibility of women to mood disorders, suggesting an interplay between anti-inflammatory cytokines and sexual steroids.

The changing microbial environment and chronic inflammatory disorders

: There is much to be gained from examining human diseases within the expanding framework of Darwinian medicine. This is particularly true of those conditions that change in frequency as populations develop from the human "environment of evolutionary adaptedness" to the living conditions of the rich industrialized countries. This development entails major changes in lifestyle, leading to reductions in contact with environmental microorganisms and helminths that have evolved a physiologic role as drivers of immunoregulatory circuits. It is suggested that a deficit in immunoregulation in rich countries is contributing not only to increases in the incidence of allergic disorders but also to increases in other chronic inflammatory conditions that are exacerbated by a failure to terminate inappropriate inflammatory reponses. These include autoimmunity, neuroinflammatory disorders, atherosclerosis, depression associated with raised inflammatory cytokines, and some cancers.

Influence of continuous infusion of interleukin-1beta on depression-related processes in mice: corticosterone, circulating cytokines, brain monoamines, and cytokine mRNA expression

RATIONALE

Activation of the immune system typically occurs on a subchronic or chronic basis (e.g., in response to bacterial or viral insults). However, analyses of the effects of cytokine treatments have typically involved acute treatments, and limited data are available concerning the behavioral and central neurochemical impact of subchronic interleukin-1beta (IL-1beta) administration.

OBJECTIVES

Several peripheral and central effects of IL-1beta treatment were assessed following single or repeated bolus injections or after infusion of the cytokine (through Alzet minipumps) over several days.

RESULTS

The impact of an acute bolus injection of IL-1beta (1.0 microg) on plasma corticosterone and on circulating IL-1beta, IL-6, and TNF-alpha were diminished following 5-day IL-1beta treatment, although high levels of sickness were still apparent. When IL-1beta (1.0 or 2.0 mug/day) was continuously infused over 3 days, plasma corticosterone and sickness were elevated, but these effects were attenuated after 7 days (subchronic) of treatment. As well, the effects of IL-1beta treatment on diurnal variations of motor activity diminished over days. Despite the diminution of the behavioral and neuroendocrine effects of the cytokine after treatment 7 days, subchronic IL-1beta infusion altered prefrontal cortical and hippocampal serotonin and norepinephrine utilization, and within these regions, the messenger RNA (mRNA) expression of IL-1beta, IL-6, TNF-alpha, and their receptors, as well as that of 5-HT(2C), 5-HT(1B) receptors, and p11, was increased.

DISCUSSION

The findings indicate that peripheral cytokine infusion markedly influences central cytokine mRNA expression and also influences 5-HT turnover, which might contribute to behavioral changes elicited by IL-1beta.

Pro- and anti-inflammatory cytokine balance in major depression: effect of sertraline therapy

The specific associations between antidepressant treatment and alterations in the levels of cytokines remain to be elucidated. In this study, we aimed to explore the role of IL-2, IL-4, IL-12, TNF-α, TGF-β1, and MCP-1 in major depression and to investigate the effects of sertraline therapy. Cytokine and chemokine levels were measured at the time of admission and 8 weeks after sertraline treatment. Our results suggest that the proinflammatory cytokines (IL-2, IL-12, and TNF-α) and MCP-1 were significantly higher, whereas anti-inflammatory cytokines IL-4 and TGF-β1 were significantly lower in patients with major depression than those of healthy controls. It seems likely that the sertraline therapy might have exerted immunomodulatory effects through a decrease in the proinflammatory cytokine IL-12 and an increase in the anti-inflammatory cytokines IL-4 and TGF-β1. In conclusion, our results indicate that Th1-, Th2-, and Th3-type cytokines are altered in the depressed patients and some of them might have been corrected by sertraline treatment.

Effect of fluoxetine on depression-induced changes in the expression of vasoactive intestinal polypeptide and corticotrophin releasing factor in rat duodenum

AIM

To investigate changes in vasoactive intestinal polypeptide (VIP) and corticotrophin releasing factor (CRF) in the plasma and duodenum of chronic stress-induced depressed rats and the effects of fluoxetine hydrochloride (fluoxetine) treatment on depression-induced changes in VIP and CRF.

METHODS

A Sprague-Dawley rat model of chronic stress-induced depression was produced. Thirty experimental rats were randomly divided into the following groups: control group, saline-treated depressed group, and fluoxetine-treated depressed group. Open-field testing was performed to assess the rats' behavior. VIP and CRF levels in plasma were measured by ELISA. Immunofluorescence techniques combined with laser scanning confocal microscopy (LSCM) were used to investigate VIP and CRF expression in the duodenum.

RESULTS

The open-field behavior, both crossing and rearing, of depression model rats, decreased significantly compared with those of normal control rats over 5 min. Defecation times increased significantly. Compared to the control group, FITC fluorescence of duodenal CRF expression and plasma CRF levels in the depressed rats increased significantly (fluorescence intensity of duodenal CRF: 11.82 +/- 2.54 vs 25.17 +/- 4.63; plasma CRF: 11.82 +/- 2.54 ng/L vs 25.17 +/- 4.63 ng/L, P < 0.01), whereas duodenal VIP expression and plasma VIP levels decreased significantly (fluorescence intensity of duodenal VIP: 67.37 +/- 18.90 vs 44.51 +/- 16.37; plasma VIP: 67.37 +/- 18.90 ng/L vs 44.51 +/- 16.37 ng/L, P < 0.01). Fluoxetine improved depressed behavior, increased VIP expression and decreased CRF expression in plasma and the duodenal tissue of depressed rats.

CONCLUSION

Chronic stress can induce injury to the duodenum, accompanied by increasing CRF and decreasing VIP in the plasma and duodenum. Treatment with fluoxetine can ameliorate pathological changes in the duodenum of depressed rats, which suggests that antidepressants are an effective therapeutic agent for some duodenal diseases caused by chronic stress. VIP is a potential therapeutic strategy.

Psychobiology of depression/distress in congestive heart failure

Heart failure affects millions of Americans and new diagnosis rates are expected to almost triple over the next 30 years as our population ages. Affective disorders including clinical depression and anxiety are common in patients with congestive heart failure. Furthermore, the presence of these disorders significantly impacts quality of life, medical outcomes, and healthcare service utilization. In recent years, the literature has attempted to describe potential pathophysiologic mechanisms relating affective disorders and psychosocial stress to heart failure. Several potential mechanisms have been proposed including autonomic nervous system dysfunction, inflammation, cardiac arrhythmias, and altered platelet function. These mechanisms are reviewed in this article. Additional novel mechanisms such as mental stress-induced myocardial ischemia are also discussed.

Serotonin decreases HIV-1 replication in primary cultures of human macrophages through 5-HT(1A) receptors

BACKGROUND AND PURPOSE

5-HT (serotonin) is known to be involved in neuroinflammation and immunoregulation. The human immunodeficiency virus (HIV) targets cells such as monocytes/macrophages, which colocalize with 5-HT-releasing cell types, mostly platelets. In this study, we investigated the effects of 5-HT on HIV-1-infected macrophages in vitro.

EXPERIMENTAL APPROACH

Human macrophages cultured in serum-free medium were treated over 7 days with 5-HT at three concentrations (0.01, 1 and 100 microM) with or without agonists and antagonists of 5-HT(1A) and 5-HT(2) receptors. After 7 days of treatment, macrophages were infected with HIV-1/Ba-L and virus replication was monitored over 16 days and expression of proviral HIV DNA was investigated by PCR after 24 h of infection. Cell surface expression of HIV-1/Ba-L receptor (CD4) and coreceptor (CCR5) was investigated by flow cytometry. The CCR5 ligand, macrophage inflammatory protein-1alpha (MIP-1alpha), was quantified by ELISA in cell culture supernatants and MIP-1alpha mRNA expression was assessed by reverse transcriptase-PCR.

KEY RESULTS

In vitro, 5-HT downregulated the membranous expression of CCR5 and led to a decrease of HIV-1 infection, probably through its action on 5-HT(1A) receptors. 5-HT (100 microM) was also able to induce overexpression of MIP-1alpha mRNA leading to an increase of MIP-1alpha secretion by human macrophages.

CONCLUSIONS AND IMPLICATIONS

The effects of 5-HT on HIV infection could be a consequence of the increase in MIP-1alpha concentrations and/or CCR5 receptor downregulation. These results suggest that 5-HT can inhibit the replication of HIV-1 in primary culture of human macrophages through its action on 5-HT(1A) receptors.

The hygiene hypothesis and psychiatric disorders

The hygiene hypothesis proposes that several chronic inflammatory disorders (allergies, autoimmunity, inflammatory bowel disease) are increasing in prevalence in developed countries because a changing microbial environment has perturbed immunoregulatory circuits which normally terminate inflammatory responses. Some stress-related psychiatric disorders, particularly depression and anxiety, are associated with markers of ongoing inflammation, even without any accompanying inflammatory disorder. Moreover, pro-inflammatory cytokines can induce depression, which is commonly seen in patients treated with interleukin-2 or interferon-alpha. Therefore, some psychiatric disorders in developed countries might be attributable to failure of immunoregulatory circuits to terminate ongoing inflammatory responses. This is discussed in relation to the effects of the immune system on a specific group of brain serotonergic neurons involved in the pathophysiology of mood disorders.

Immune-based regulation of adult neurogenesis: implications for learning and memory

Neurogenesis, the formation of new neurons from stem/progenitor cells, occurs in the hippocampal dentate gyrus throughout life. Although the exact function of adult hippocampal neurogenesis is currently unknown, recent studies suggest that the newly formed neuronal population plays an important role in hippocampal-dependent cognitive abilities, including declarative memory. The process of adult neurogenesis is greatly influenced by the interaction between cells of the adaptive immune system and CNS-resident immune cells. Our laboratory has recently demonstrated that immune cells contribute to maintaining life-long hippocampal neurogenesis. The regulation of such immune-cell activity is crucial: too little immune activity (as in immune deficiency syndromes) or too much immune activity (as in severe inflammatory diseases) can lead to impaired hippocampal neurogenesis, which could then result in impaired hippocampal-dependent cognitive abilities. From these converging discoveries arise a mechanism that can explain one route by which our body affects our mind.

Venlafaxine exhibits an anti-inflammatory effect in an inflammatory co-culture model

Growing evidence indicates immunoregulatory effects of various antidepressants. Through the interaction of the nervous and immune systems, the norepinephrine-serotonin system was shown to modulate inflammatory CNS diseases. Thus, we examined the norepinephrine-serotonin reuptake inhibitor venlafaxine in an astroglia-microglia co-culture model which allows mimicking of an inflammatory milieu by increasing the cultured microglial fraction. Astrocytic membrane resting potential and intercellular coupling, two markers becoming severely impaired under inflammation, were assessed with the patch-clamp technique. We measured IL-6, IL-10, IFN-gamma and TGF-beta concentrations and analysed phenotypic changes of microglia. We found (i) a reversal of the inflammation-induced depolarization effect on the membrane resting potential, (ii) an augmentation of TGF-beta release with a concomitant reduction in the secretion of pro-inflammatory IL-6 and IFN-gamma, and (iii) a significant change of microglial phenotype from activated to resting morphology. Our data clearly indicate anti-inflammatory properties of venlafaxine which might be a result of monoamine-mediated immunomodulation.

The immune-mediated alteration of serotonin and glutamate: towards an integrated view of depression

Beside the well-known deficiency in serotonergic neurotransmission as pathophysiological correlate of major depression (MD), recent evidence points to a pivotal role of increased glutamate receptor activation as well. However, cause and interaction of these neurotransmitter alterations are not understood. In this review, we present a hypothesis integrating current concepts of neurotransmission and hypothalamus-pituitary-adrenal (HPA) axis dysregulation with findings on immunological alterations and alterations in brain morphology in MD. An immune activation including increased production of proinflammatory cytokines has repeatedly been described in MD. Proinflammatory cytokines such as interleukin-2, interferon-gamma, or tumor necrosis factor-alpha activate the tryptophan- and serotonin-degrading enzyme indoleamine 2,3-dioxygenase (IDO). Depressive states during inflammatory somatic disorders are also associated with increased proinflammatory cytokines and increased consumption of tryptophan via activation of IDO. An enhanced consumption of serotonin and its precursor tryptophan through IDO activation could well explain the reduced availability of serotonergic neurotransmission in MD. An increased activation of IDO and its subsequent enzyme kynurenine monooxygenase by proinflammatory cytokines, moreover, leads to an enhanced production of quinolinic acid, a strong agonist of the glutamatergic N-methyl-D-aspartate receptor. In inflammatory states of the central nervous system, IDO is mainly activated in microglial cells, which preferentially metabolize tryptophan to the NMDA receptor agonist quinolinic acid, whereas astrocytes - counteracting this metabolism due to the lack of an enzyme of this metabolism - have been observed to be reduced in MD. Therefore the type 1/type 2 immune response imbalance, associated with an astrocyte/microglia imbalance, leads to serotonergic deficiency and glutamatergic overproduction. Astrocytes are further strongly involved in re-uptake and metabolic conversion of glutamate. The reduced number of astrocytes could contribute to both, a diminished counterregulation of IDO activity in microglia and an altered glutamatergic neurotransmission. Further search for antidepressant agents should take into account anti-inflammatory drugs, for example, cyclooxygenase-2 inhibitors, might exert antidepressant effects by acting on serotonergic deficiency, glutamatergic hyperfunction and antagonizing neurotoxic effects of quinolinic acid.

Role of paroxetine in interferon-alpha-induced immune and behavioural changes in male Wistar rats

Treatment with pro-inflammatory cytokine, IFNalpha was documented to result in neuropsychiatric complications including depression and treatment with antidepressant, paroxetine could improve the depressive symptoms. Therefore, the effects of IFNalpha on behaviour and cytokine changes in the whole blood culture and in the prefrontal cortex, hypothalamus and hippocampus areas of the brain in wistar rats were investigated with emphasis on the role of paroxetine in the prevention of depressive behaviour induced by pro-inflammatory cytokines. The group of rats treated with IFNalpha (s.c. 50,000 IU/kg for 3 days/week for 5 weeks) was compared with three other groups; 1) saline control group (s.c. normal saline 0.2 ml/kg/day for 7 weeks), 2) paroxetine control group (paroxetine suspension orally 10 mg/kg/day for 7 weeks) and 3) group treated with paroxetine for 2 weeks followed by IFNalpha for 5 weeks. In open filed, the IFNalpha treated rats showed anxiety behaviour compared to the rats from the other groups. There was no significant difference in home cage emergence test, Morris water maze and object recognition test. There is no significant difference in plasma corticosterone between groups. The pro-inflammatory cytokines (TNFalpha, IL1beta and IFNgamma), were significantly higher whereas the anti-inflammatory cytokine, IL10 was lower in the stimulated whole blood culture of IFNalpha treated rats. In the brain, both pro-inflammatory cytokine IL1beta and anti-inflammatory cytokine IL10 were higher in hypothalamus of the IFNalpha treated rats; by contrast the concentration of IL10 was lowest in hippocampus region of this group compared to the other groups. The paroxetine pretreated rats did not show these cytokine changes following IFNalpha treatment. Thus it appears that paroxetine pretreatment prevents the pro-inflammatory changes in blood and brain following IFNalpha treatment in turn prevents the anxiety behaviour.

[Serotonin modulates HIV replication in primary culture of human macrophages: involvement of 5-HT(1A) sub-type receptors]

The neurotransmitter 5-hydroxytryptamine (5-HT), commonly known as serotonin, is released at peripheral sites from activated platelets. At inflammatory sites, macrophages and lymphocytes could be exposed to 5-HT concentrations up to 100 microM. Moreover, 5-HT could modulate cytokine secretion by monocytes/macrophages and immune functions through the uptake of 5-HT at these inflammatory sites from T cells and dendritic cells. HIV infection is also under the control of inflammatory processes (including T cell proliferation and cytokines secretion). On this basis, we studied explored herein the effects of 5-HT on HIV-1/Ba-L (macrophage-tropic virus) replication in primary cultures of human macrophages. This pharmacological study with isotype-selective receptor agonists and antagonist allowed us to show that the 100 microM 5-HT concentration via 5-HT(1A) subtype receptors could decrease HIV replication. This observation was associated with an increase of MIP-1alpha secretion such as an increase of MIP-1alpha mRNA production and with a decrease of HIV-coreceptor CCR5 cell surface expression. Our results point out for the first time the inhibitory effects of 5-HT on HIV replication in primary culture of human macrophages via activation of 5-HT(1A) subtype receptors.

T-helper 1/T-helper 2 cytokine imbalance and clinical phenotypes of acute-phase major depression

Several studies have discussed the relationships between T-helper 1 (Th1) or Th2 cytokines and major depression. The aim of the present study was to investigate the relationships between Th1/Th2 cytokine balance and clinical phenotypes of acute-phase major depression. A total of 82 subjects including 42 patients with major depressive disorder and 40 healthy controls were recruited. Serum cytokine levels of interleukin-1beta (IL-1beta), tumor necrosis factor-alpha (TNF-alpha) and IL-10 were examined. Using ancova with age and body mass index (BMI) adjustments, there were no significant differences in serum IL-1beta, TNF-alpha, and IL-10 levels between patients with major depressive disorder and healthy controls. However, using ANCOVA with BMI adjustment only, the results showed that patients with major depressive disorder had significantly higher TNF-alpha levels than control subjects. In addition, using ANCOVA with age and BMI adjustments, significantly higher serum IL-1beta level and IL-1beta/IL-10 ratio were noted in patients with melancholic features than patients with non-melancholic features. However, there were no significant differences in serum IL-1beta, TNF-alpha and IL-10 levels between patients with and without suicide attempt. In conclusion, serum TNF-alpha, IL-1beta level and IL-1beta/IL-10 ratio might play an important role in the psychopathology of acute-phase major depressive disorder.

Cytokine imbalance in the pathophysiology of major depressive disorder

OBJECTIVE

A substantial body of evidence indicates that dysregulation of the immune system is associated with Major Depressive Disorder (MDD). Because most cytokines have pleiotropic effects, we measured various subsets of cytokines to examine the association between immune response and MDD.

METHODS

Forty-eight hospitalized MDD patients and 63 normal controls were recruited. We measured in vitro monocytic (IL-6 and tumor necrosis factor (TNF)-alpha), Th1 (interferon (IFN)-gamma and interleukin (IL)-2), Th2 (IL-4), and Treg (transforming growth factor (TGF)-beta1) cytokine production as well as IL-2/IL-4 and IFN-gamma/IL-4 ratios for both groups. Depressive symptoms were assessed by Hamilton Depression Rating Scale. Patients were evaluated before and after 6 weeks of antidepressant treatment.

RESULTS

At admission, IL-6, TNF-alpha, TGF-beta1 production, and IFN-gamma/IL-4 ratio were significantly higher, whereas IFN-gamma, IL-2, and IL-4 were significantly lower in MDD patients. After treatment, IL-6 and TGF-beta1 production were significantly lower than before treatment.

CONCLUSION

We suggest that activation of monocytic proinflammatory cytokines, and inhibition of both Th1 and Th2 cytokines may be associated with immunological dysregulation in MDD. TGF-beta1 may be associated with the regulation of monocytic cytokines as well as Th1 and Th2 cytokines in MDD.

Antidepressants inhibit interferon-gamma-induced microglial production of IL-6 and nitric oxide

Circumstantial evidence has suggested that activated microglia may be associated with the pathogenesis of depression. Pro-inflammatory cytokines may also be involved. Therefore, we examined the effects of various types of antidepressants, as well as the mood-stabilizer lithium chloride, on interferon-gamma (IFN-gamma)-induced microglial production of the pro-inflammatory mediators interleukin-6 (IL-6) and nitric oxide (NO). Treatment of the murine microglial 6-3 cells with 100 U/ml of IFN-gamma resulted in an eightfold increase in IL-6 and a tenfold increase in NO into the culture medium. Pretreatment with the selective serotonin reuptake inhibitor fluvoxamine, the relatively selective noradrenaline reuptake inhibitor reboxetine, or the non-selective monoaminergic reuptake inhibitor imipramine, significantly inhibited IL-6 and NO production in a dose-dependent manner. These inhibitions were reversed significantly by SQ 22536, a cyclic adenosine monophosphate (cAMP) inhibitor, and, except for reboxetine, by the protein kinase A (PKA) inhibitor Rp-adenosine3',5'-cyclic monophosphorothioate triethylammonium salt (Rp-3',5'-cAMPS). Lithium chloride, which is believed to act by inhibiting the calcium-dependent release of noradrenaline, had a different spectrum of action on microglial 6-3 cells. It enhanced IFN-gamma-stimulated IL-6 production and inhibited NO production. The inhibitory effect of lithium chloride was not reversed by either SQ 22536 or Rp-3',5'-cAMPS. These results suggest that antidepressants have inhibitory effects on IFN-gamma-activated microglia and these effects are, at least partially, mediated by the cAMP-dependent PKA pathway. On the other hand, the mood stabilizer and anti-manic agent lithium chloride has mixed effects on IFN-gamma-induced microglial activation.

Desipramine Activated Bcl-2 Expression and Inhibited Lipopolysaccharide-Induced Apoptosis in Hippocampus-Derived Adult Neural Stem Cells

Desipramine (DP) is a tricyclic antidepressant used for treating depression and numerous other psychiatric disorders. Recent studies have shown that DP can promote neurogenesis and improve the survival rate of hippocampal neurons. However, whether DP induces neuroprotection or promotes the differentiation of neural stem cells (NSCs) needs to be elucidated. In this study, we cultured NSCs derived from the hippocampal tissues of adult rats as an in vitro model to evaluate the modulation effect of DP on NSCs. First, we demonstrated that the expression of Bcl-2 mRNA and nestin in 2 microM DP-treated NSCs were up-regulated and detected by real-time reverse transcriptase polymerase chain reaction (RT-PCR). The results of Western blotting and immunofluorescent study confirmed that Bcl-2 protein expression was significantly increased in Day 3 DP-treated NSCs. Using the Bcl-2 small interfering RNA (siRNA) method, our results further showed that DP protects the lipopolysaccharide (LPS)-induced apoptosis in NSCs, in part by activating the expression of Bcl-2. Furthermore, DP treatment significantly inhibited the induction of proinflammatory factor interleukin (IL)-1beta, IL-6, and tumor necrosis factor-alpha in the culture medium of LPS-treated NSCs mediated by Bcl-2 modulation. The results of high performance liquid chromatography coupled to electrochemical detection further confirmed that DP significantly increased the functional production of serotonin (26+/-3.5 microM, DP-treated 96 h) and noradrenaline (50+/-8.9 microM, DP-treated 96 h) in NSCs through activation of the MAPK/ERK pathway and partially mediated by Bcl-2. In conclusion, the present results indicate that DP can increase neuroprotection ability by inhibiting the LPS-induced inflammatory process in NSCs via the modulation of Bcl-2 expression, as confirmed by the siRNA method.

Effect of acute and repeated treatment with mirtazapine on the immunity of noradrenaline transporter knockout C57BL/6J mice

Pathological immunoactivation is thought to play an important role in the etiology of depression; however, the effect of novel antidepressant drugs on immunity has been poorly recognized. Mirtazapine, an antidepressant drug, enhances noradrenergic and serotonergic neurotransmissions, which are crucially involved in the regulation of immune system activity. In the present study we examined the effect of acute and seven-day repeated administration of mirtazapine (20 mg/kg, i.p.) on immunoreactivity in noradrenaline transporter knockout (NET-KO) and wild-type male C57BL/6J mice subjected to the forced swimming test (FST). Mirtazapine decreased immobility time in the FST after acute, but not seven-day repeated, administration to C57BL/6J mice. Lack of the antidepressant effect of mirtazapine was observed, after acute and repeated administration to NET-KO mice, although those mice showed a significantly shorter immobility time in the FST than did wild-type animals. Seven-day repeated mirtazapine administration to wild-type mice suppressed the proliferative activity of splenocytes and their ability to produce pro-inflammatory cytokines, whereas production of IL-4 was stimulated. Acute mirtazapine administration did not change immune parameters in C57BL/6J mice. In NET-KO mice, acute and seven-day repeated mirtazapine administration reduced the proliferative activity of splenocytes and their ability to produce pro-inflammatory cytokines. This study indicates that, in comparison with wild-type C57BL/6J mice, NET-KO mice show enhanced mobility, which is not further potentiated by mirtazapine treatment. Furthermore, the NET-KO mice display higher susceptibility to the immunosuppressive effects of mirtazapine than do the wild-type animals. The present paper postulates an essential role of noradrenergic system in the immunological and behavioral effects of mirtazapine.

Sympathetic nervous system and neurotransmitters: their possible role in neuroimmunomodulation of multiple sclerosis and some other autoimmune diseases

Multiple sclerosis is still a disease without a cure. Although intensive research efforts have led to the development of drugs that modify the activity of the disease, most of them have various side effects and are expensive. At the same time it is becoming apparent that some remedies usually used to treat somatic and psychic disorders also have immunomodulating properties, and may help manage multiple sclerosis and other autoimmune diseases. We describe here the role of the sympathetic nervous system in the neuro-immune interaction in multiple sclerosis and other immune diseases with increased cellular immunity as well as neurochemical disturbances that take place in these disorders.

Successful antidepressant therapy restores the disturbed interplay between TNF-alpha system and HPA axis

BACKGROUND

In depressed patients, alterations in the hypothalamo-pituitary-adrenocortical (HPA) system are the most consistent neurobiological finding. HPA axis activity and cytokines are intrinsically intertwined: inflammatory cytokines stimulate adrenocorticotropic hormone (ACTH) and cortisol secretion, while, in turn, glucocorticoids suppress the synthesis of proinflammatory cytokines.

METHODS

We examined alterations in plasma levels of tumor necrosis factor-alpha (TNF-alpha), levels of its soluble receptors p55 (sTNF-R p55) and p75 (sTNF-R p75) as well as changes in the HPA system function using the combined dexamethasone/corticotropin-releasing hormone (dex/CRH) test on admission and at discharge in 70 depressed inpatients without inflammation.

RESULTS

On admission, TNF-alpha levels were inversely associated with the ACTH response to the combined dex/CRH test. Changes in TNF-alpha, sTNF-R p55, and sTNF-R p75 plasma levels from admission to discharge were positively correlated with the dex/CRH test outcome at discharge. Subgroup analysis revealed that this association was restricted to those patients achieving remission. In this subgroup, TNF-alpha levels at discharge were also positively correlated with dex/CRH test response at discharge.

CONCLUSIONS

Our results suggest that elevated HPA axis activity in acute depression suppresses TNF-alpha system activity, while after remission, when HPA axis activity has normalized, the TNF-alpha system seems to gain influence on the HPA system.

Antidepressants suppress production of the Th1 cytokine interferon-gamma, independent of monoamine transporter blockade

In this study, antidepressants with selectivity for the noradrenaline transporter (reboxetine and desipramine), or the serotonin transporter (fluoxetine and clomipramine) were examined in terms of their ability to promote an anti-inflammatory cytokine phenotype in human blood. In addition, we examined the ability of trimipramine; a tricyclic antidepressant that is devoid of monoamine reuptake inhibitory properties on cytokine production. Lipopolysaccharide (LPS) was used to stimulate monocyte-derived pro-inflammatory (IL-1beta, TNF-alpha, IL-12) and anti-inflammatory (IL-10) cytokines, whilst concanavalin A (Con A) was used to stimulate T-cell (Th(1): IFN-gamma and Th(2/3): IL-10) cytokines. All of the antidepressants suppressed IFN-gamma production in the 10-50 microM concentration range, irrespective of their preference for serotonin or noradrenaline transporters. This suppression of IFN-gamma production was paralleled by reduced T-cell proliferation, therefore we suggest that the ability of antidepressants to suppress IFN-gamma production may be related to their anti-proliferative properties. The fact that trimipramine also suppressed IFN-gamma production and T-cell proliferation indicates that these immunomodulatory actions of antidepressants are most likely unrelated to inhibition of monoamine reuptake. Interestingly, exposure to a lower concentration (1 microM) of the antidepressants tended to increase T-cell-derived IL-10 production, with significant effects elicited by the noradrenaline reuptake inhibitors reboxetine and desipramine. In contrast to the robust actions of antidepressants on T-cell derived cytokine production, they failed to induce any consistent change in LPS-induced monocyte cytokine production. Overall, our results indicate that IFN-gamma producing T-cells (Th(1) cells) are the major target for the immunomodulatory actions of antidepressants, and provide evidence questioning the relationship between the monoaminergic reuptake properties of antidepressants and their immunomodulatory effects. The potential clinical significance of the anti-inflammatory actions of antidepressants is discussed.

The role of IL-12 and TGF-beta1 in the pathophysiology of major depressive disorder

It has been postulated that major depression may be accompanied by significant changes in cell-mediated and humoral immunity related to the pathophysiology or pathogenesis of that illness. We explored the role of 2 cytokines, IL-12 and TGF-beta1, which represent the cytokines of the Th1 and Th3 types, in the pathophysiology of major depressive disorder (MDD). Cytokine levels were measured in 30 major depressed patients at the time of admission and 6 weeks after effective antidepressant treatment; levels were measured once in 30 normal controls. At the time of admission, TGF-beta1 levels of MDD patients showed no differences from normal controls, but IL-12 was significantly higher than in normal controls. However, the IL-12/TGF-beta1 (Th1/Th3) ratios of depressed patients were not different from those of controls. In MDD patients, IL-12 values were significantly decreased after treatment, while TGF-beta1 levels were significantly increased. IL-12/TGF-beta1 ratios of patients were significantly decreased after treatment compared with before treatment. There were no significant correlations between changes in the cytokine levels and changes in scores representing the severity of depression. These findings suggest that major depression is accompanied by immune activation during the acute depressed state, and antidepressant treatments have anti-inflammatory effects.

Fluoxetine up-regulates expression of cellular FLICE-inhibitory protein and inhibits LPS-induced apoptosis in hippocampus-derived neural stem cell

Fluoxetine is a widely used antidepressant compound which inhibits the reuptake of serotonin in the central nervous system. Recent studies have shown that fluoxetine can promote neurogenesis and improve the survival rate of neurons. However, whether fluoxetine modulates the proliferation or neuroprotection effects of neural stem cells (NSCs) needs to be elucidated. In this study, we demonstrated that 20 microM fluoxetine can increase the cell proliferation of NSCs derived from the hippocampus of adult rats by MTT test. The up-regulated expression of Bcl-2, Bcl-xL and the cellular FLICE-inhibitory protein (c-FLIP) in fluoxetine-treated NSCs was detected by real-time RT-PCR. Our results further showed that fluoxetine protects the lipopolysaccharide-induced apoptosis in NSCs, in part, by activating the expression of c-FLIP. Moreover, c-FLIP induction by fluoxetine requires the activation of the c-FLIP promoter region spanning nucleotides -414 to -133, including CREB and SP1 sites. This effect appeared to involve the phosphatidylinositol-3-kinase-dependent pathway. Furthermore, fluoxetine treatment significantly inhibited the induction of proinflammatory factor IL-1beta, IL-6, and TNF-alpha in the culture medium of LPS-treated NSCs (p<0.01). The results of high performance liquid chromatography coupled to electrochemical detection further confirmed that fluoxentine increased the functional production of serotonin in NSCs. Together, these data demonstrate the specific activation of c-FLIP by fluoxetine and indicate the novel role of fluoxetine for neuroprotection in the treatment of depression.

Psychological profile in oral lichen planus

AIM

Oral lichen planus (OLP) is an oral lesion with an enigmatic etiology. To explore the possibility of psycho-somatization, we evaluated the psychological personality profiles of OLP patients.

METHODS

Twenty patients with reticular; 20 with erosive form of OLP, and 25 controls were tested with the psychological Minnesota Multiphasic Personality Inventory (MMPI)-202 test. Eight clinical scales (hypochondriasis, depression, hysteria, psychopathic deviate, paranoia, psychasthenia, schizophrenia, and hypomania) as well as cortisol level, CD3, CD4, CD8, and CD16 markers by group were compared. Psychosomatization was evaluated by the use of internalization ratio (IR) Index.

RESULTS

A characteristic MMPI profile was noted in the OLP groups with high IR index value. Significant differences among the groups were detected for cortisol, CD4, CD8, and CD16 counts. Mean values for hypochondriasis, depression, and hysteria were all significantly different with significantly higher mean scores for both reticular and erosive OLP subjects compared with controls.

CONCLUSIONS

Prolonged emotive stress in many OLP patients may lead to psychosomatization and may contribute to the initiation and clinical expression of this oral disorder.

CLINICAL SIGNIFICANCE

If additional research involving a larger and more diverse sample of patients confirms these findings, clinical trials will be needed to determine whether adjunctive psychological intervention provides a benefit in treating patients with OLP.

The negative immunoregulatory effects of fluoxetine in relation to the cAMP-dependent PKA pathway

Recently, we have shown that various types of antidepressants, including selective serotonin reuptake inhibitors (SSRIs) such as fluoxetine, have negative immunoregulatory effects. These antidepressants suppress the interferon-gamma (IFN-gamma)/interleukin-10 (IL-10) production ratio, which is of critical importance for the determination of the capacity of immunocytes to inhibit or activate monocytic/lymphocytic functions. Since cyclic adenosine monophosphate (cAMP) production is stimulated by some antidepressants, and since cAMP inhibits IFN-gamma and stimulates IL-10 production, we postulate that the negative immunoregulatory effects of antidepressants result from their effects on the cAMP-dependent protein kinase A (PKA) pathway. The aim of the present study was to determine whether the negative immunoregulatory effects of fluoxetine may be blocked by antagonists of the cAMP-dependent PKA pathway, such as, e.g., SQ 22536, an adenylate cyclase inhibitor, and Rp-8-Br-cAMPs (Rp-isomer of 8-bromo-adenosine-3',5'-monophosphorothioate), a PKA antagonist. To this end, diluted whole blood collected from 17 normal volunteers was incubated with fluoxetine (10(-6) and 10(-5) M), with or without SQ 22536 (10(-6) and 10(-4) M) and Rp-8-Br-cAMPs (10(-6) and 10(-4) M), afterwards, IFN-gamma, IL-10 and the tumor necrosis factor alpha (TNF-alpha) were determined. Fluoxetine, 10(-6) and 10(-5) M, significantly reduced the production of IFN-gamma and TNF-alpha, and significantly decreased the IFN-gamma/IL-10 production ratio. SQ 22536 and Rp-8-Br-cAMPs were unable to block the suppressant effects of fluoxetine on the IFN-gamma/IL-10 ratio. Rp-8-Br-cAMPs, 10(-4), but not 10(-6) M, normalized the fluoxetine-induced suppression of TNF-alpha production. It is concluded that the suppressant effect of fluoxetine on the IFN-gamma/IL-10 production ratio is probably not related to the induction of the cAMP-dependent PKA pathway, whereas the suppressant effect on TNF-alpha may be related to the induction of PKA. The obtained results suggest that increased activation of the PKA-dependent pathway may constitute an important molecular basis for some (suppression of TNF-alpha production), but not all (suppression of IFN-gamma production), negative immunoregulatory effects of fluoxetine.

Endotoxin- or pro-inflammatory cytokine-induced sickness behavior as an animal model of depression: focus on anhedonia

In humans, exposure to endotoxins or pro-inflammatory cytokines induces a number of neuropsychological symptoms collectively referred to as 'flu-like syndrome'. The degree of overlap between flu-like syndrome and major depressive disorder is considerable and a close linkage between these has been predicted to arise due to hypersecretion of endogenous pro-inflammatory cytokines and activation of the hypothalamic pituitary adrenal axis. In animals, exposure to pro-inflammatory cytokines or endotoxins induces a 'sickness behavior' syndrome that is analogous to flu-like symptoms observed in human patients. The goal of the current paper is to review evidence implicating endotoxin- or cytokine-induced sickness behavior as an animal model of depression, with an emphasis on reduced consumption of highly palatable substances as a defining feature.

Initial conditions of psychotropic drug response: studies of serotonin transporter long promoter region (5-HTTLPR), serotonin transporter efficiency, cytokine and kinase gene expression relevant to depression and antidepressant outcome

The Hypothesis of Initial Conditions posits that differences in psychotropic drug response result from individual differences in receptor site kinetics, and differences in the sensitivity of downstream receptor-linked responses. This work examines data consistent with the hypothesis, specific to genetic and kinetic differences of the serotonin (5-HT) transporter (SERT), as they may be linked to divergent antidepressant response (ADR). The mechanisms for divergent ADR in association with different initial SERT function are considered within the context of SERT trafficking as sensitive to various different kinase and cytokine signals, some of which are dependent on the 5-HTTLPR polymorphism of the SERT gene. Pilot data suggest that human lymphocytes show kinase changes similar to those found in rat brain with ADT. These studies additionally suggest that ADT prompts a shift in cytokine gene expression toward a greater anti-inflammatory/inflammatory ratio. These latter findings are discussed within the context of a literature suggesting increased inflammatory cytokine levels in depression, and recent observations of increased temperature associated with depression. In sum, the data suggest the opportunity to identify response dependent protein (RDP) expression patterns that may differ with dichotomous ADR, and suggest new insights into understanding the mechanisms of psychotropic drug response through an understanding of initial differences in potential for psychotropic drug target regulation during therapy.

Cytokine regulation of tryptophan metabolism in the hypothalamic-pituitary-adrenal (HPA) axis: implications for protective and toxic consequences in neuroendocrine regulation

AIM

Indoleamine 2,3-dioxygenase (IDO) catalyzation of tryptophan is the first rate-limiting step of the kynurenine pathway in the majority of tissues. The kynurenine pathway produces neurotoxic metabolites such as 3-hydroxykinurenine and quinolinic acid. IDO is inducible by the cytokine interferon-gamma (IFN-gamma) and has been proposed to mediate the sickness behavior of patients with infectious or other inflammatory diseases.To better understand the neuroendocrine component of cytokine induced sickness behavior we determined the effects of the pro-inflammatory cytokine IFN-gamma and the anti-inflammatory cytokine IL-10 on IDO expression in cells derived from the hypothalamic-pituitary-adrenal axis (HPA): GT1-7 hypothalamic, AtT-20 pituitary, and Y-1 adrenal cells.

METHODS

Reverse transcriptase polymerase chain reaction (RT-PCR) was performed to check the IDO expression from IFN-gamma and IL-10 treated cells such as GT1-7, AtT-20 and Y-1 cells.

RESULTS

We found that IFN-gamma induces IDO expression after 4 h treatment in GT1-7 and AtT-20 cells. IL-10 was also able to suppress IFN-gamma induced IDO expression in these cells. In Y-1 adrenal cells, IFN-gamma treatment had no effect on IDO expression.

CONCLUSIONS

Our results indicate that cytokines such as IFN-gamma and IL-10 are able to regulate IDO expression in cells of hypothalamic and pituitary origin. The ability of IL-10 to suppress IFN-gamma induced IDO expression implies that IL-10 has a putative neuroprotective role in the HPA axis. It can act at two levels, systemically by inhibiting sickness behavior-related Th1 cytokine synthesis and more centrally by inhibiting the kynurenine pathway.

Effect of repeated administration of paroxetine and electroconvulsive shock on the proliferative response of lymphocytes and the synthesis of nitric oxide by macrophages in rats

OBJECTIVES

We sought to determine whether chronic administration of paroxetine and electroconvulsive shock (ECS), given separately or jointly, changes the proliferative response of T and B lymphocytes stimulated by mitogens and affect the production of nitric oxide (NO) by peritoneal macrophages.

METHODS

The experiment was conducted on male Wistar rats receiving treatment once daily for 12 consecutive days. Control animals were injected intraperitoneally (ip) with sterile distilled water (2 mL/kg) and were subjected to sham ECS. Paroxetine was administered ip in a dose of 10 mg/kg of body weight. ECS (150 mA, 50 Hz, 0.5 seconds) was delivered through ear clips. For combined treatment, paroxetine was given 30 minutes before ECS. The rats were killed 24 hours after the last treatment. Then, the proliferative response of splenocytes was induced by concanavalin A (Con A), lipopolysaccharide (LPS), or pokeweed mitogen and those of thymocytes by Con A and was later assessed by a standard [H]-thymidine incorporation assay. The spontaneous or induced (with LPS) NO synthesis in peritoneal macrophages was assessed as nitrite accumulation in 24-hour culture supernatants using the Griess reaction.

RESULTS

Only chronic treatment with ECS alone significantly increased the proliferative response of splenocytes to stimulation with Con A or LPS. The response of thymocytes was not changed in any group tested. Both the spontaneous NO synthesis and that induced with LPS in macrophages were significantly decreased only in rats receiving ECS.

CONCLUSIONS

We suggest that the ECS-induced suppression of NO synthesis by macrophages, resulting from the noradrenergic component of ECS action, may be responsible for the enhanced proliferative response of lymphocytes. Our data are in line with the results of other authors indicating that paroxetine and/or ECS modulate the immune system indirectly via the neuroendocrine system. The relatively high efficacy of ECS in the therapy for depression may be attributable to the ECS-evoked long-lasting changes in the immune system, which supports the macrophage theory of depression.

Acute diclofenac treatment attenuates lipopolysaccharide-induced alterations to basic reward behavior and HPA axis activation in rats

RATIONALE

Non-steroidal anti-inflammatory drugs (NSAIDs) counteract stress hormone and pro-inflammatory cytokine activation, and are being considered as therapeutics for Alzheimer's and Parkinson's disease, and multiple sclerosis. Previous data from our laboratory revealed that repeated treatment with the NSAID diclofenac attenuated lipopolysaccharide (LPS)-induced alterations to reward behavior, implicating a role for NSAIDs in alleviating depressive-like behavior.

OBJECTIVES

To extend these findings, we sought to determine whether acute treatment with diclofenac would attenuate LPS-induced alterations to basic reward behavior, as well as neuroendocrine and neuroimmune function.

METHODS

Male, Wistar rats (n=8-9/grp) pressed a lever for sucrose pellet reward and after establishing a steady baseline were exposed to an injection of saline (1 ml/kg, SC) or diclofenac (2.5 mg/kg, SC) 30 min prior to a second injection of saline or LPS (20 microg/kg, IP).

RESULTS

In saline pre-treated rats, LPS significantly reduced rate of sucrose pellet self-administration and total reinforcers obtained, suggestive of an anhedonia response. In addition, LPS increased corticosterone release, increased plasma intereleukin (IL)-1beta release, increased IL-1beta and IL-6 mRNA in hippocampus, increased corticotropin releasing hormone (CRH) mRNA in pituitary, and decreased CRH-1 mRNA in pituitary. Importantly, the behavioral and neuroendocrine effects, but not neuroimmune effects, produced by LPS were significantly attenuated in rats pre-treated with diclofenac.

CONCLUSIONS

These new data provide a comprehensive assessment of the acute effects of diclofenac on LPS exposure in rats and confirm a role for NSAIDs in attenuating endotoxin-induced anhedonia. Of particular importance, the data reveal that the observed effects are mediated via the hypothalamic pituitary adrenal axis at the level of the pituitary or above.

Effects of serotonin and serotonergic agonists and antagonists on the production of tumor necrosis factor alpha and interleukin-6

Serotonin (5-HT) is a neurotransmitter and immune modulator. The effect of 5-HT on the production of cytokines by human macrophages and lymphocytes is poorly recognized. In the present article we examine the role of 5-HT in modulating the production of two pro-inflammatory cytokines, i.e. interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNFalpha), as well as the role of 5-HT(1A) and 5-HT(2) receptors in this process. The specific aims were to examine the effects of 5-HT, p-chlorophenylalanine (PCPA), a 5-HT depleting agent, flesinoxan, a 5-HT(1A) agonist, m-chlorophenylpiperazine (mCPP), a 5-HT(2B/2C) agonist, and ritanserin, a 5-HT(2A/2C) antagonist, on the production of the above cytokines. We found that: (1) 5-HT, 15 microg/ml, significantly decreased IL-6 and TNFalpha production; (2) pCPA, 5 microM, significantly suppressed the production of IL-6 and TNFalpha; and (3) mCPP, 2.7 microg/ml, significantly increased the production of IL-6 and TNFalpha. It is concluded that intracellular 5-HT is necessary for optimal synthesis of IL-6 and TNFalpha; 5-HT in physiological concentrations may increase IL-6 and TNFalpha production by stimulating 5-HT(2) receptors; and extracellular 5-HT concentrations above the baseline physiological levels may suppress the production of the above cytokines.

Treatment with selective serotonin reuptake inhibitors for enhancing wound healing

Selective serotonin reuptake inhibitors (SSRIs) are well-established medications for the treatment of mood disorders including major depression. These agents are also known to exhibit potent antiplatelet and endothelium protective effects effects. Additionally, SSRIs can exacerbate the development of inflammation, and modulate the interleukin and interferon production. All of the above suggest that SSRIs therapy could be considered as a potential strategy for the wound healing treatment. We summarized some body of the available data on the history of serotonin metabolism, mechanism of action of ketanserin, and hypothesize why SSRIs may be beneficial in the wound repair natural history. Different pathophysiological considerations are also reflected in this review. Finally, we suggest that the topical use of SSRIs may represent a promising avenue for future strategies affecting wound repair in high-risk patients, especially those with diabetes mellitus, venous insufficiency, obesity, and other vascular disorders.

Monocyte chemoattractant protein-1 (MCP1) promoter -2518 polymorphism may confer a susceptibility to major depressive disorder in the Korean population

We conducted a case-control association study of the monocyte chemoattractant protein-1 (MCP1) gene -2518 polymorphism in 90 patients with major depressive disorder. Genotyping was performed by polymerase chain reaction methods. We found significant differences in genotype and allele frequencies. The present study suggests that this polymorphism may confer a susceptibility to major depressive disorder in the Korean population.

Cytokine-serotonin interaction through IDO: a neurodegeneration hypothesis of depression

There are different theories and hypotheses related to the aetiology of depression. The interaction between brain 5-HT level and the activity of its autoreceptors plays a role in mood changes and depression. In major depression, activation of the inflammatory response system (IRS) and, increased concentrations of proinflammatory cytokines, prostaglandin E2 and negative immuno-regulatory cytokines in peripheral blood have been reported. Recently, pro-inflammatory cytokines have been found to have profound effects on the metabolism of brain serotonin through the enzyme indoleamine-2,3-dioxygenase (IDO) that metabolizes the tryptophan, the precursor of 5-HT to neurodegenerative quinolinate and neuroprotective kynurenate. The cytokine-serotonin interaction that leads to the challenge between quinolinate and kynurenate in the brain explains the neurodegeneration hypothesis of depression.

Chronic administration of tianeptine balances lipopolysaccharide-induced expression of cytokines in the spleen and hypothalamus of rats

The antidepressant tianeptine has been shown to protect the hippocampus against the deleterious consequences of stress and to attenuate the behavioral and neuroendocrine effects of the cytokine inducer lipopolysaccharide (LPS). Since sickness symptoms are linked to peripheral and brain production of cytokines and pro-inflammatory cytokines can promote neurotoxicity, the present study was undertaken to test the possibility that tianeptine attenuates production of pro-inflammatory cytokines. This hypothesis has been tested by studying the effects of a chronic intraperitoneal (i.p.) administration of tianeptine (10 mg/kg twice a day for 21 days) to rats on the induction by LPS (250 microg/kg, i.p.) of the production of pro- and anti-inflammatory cytokines, at the periphery (spleen, pituitary) and in the brain (hypothalamus, hippocampus). The expression of mRNAs coding for IL-1 beta, TNF-alpha, IL-6 or IL-10 (RT-PCR) and plasma levels of IL-1 beta, TNF-alpha and IL-10 (ELISA) were measured at various time intervals following LPS. Chronic tianeptine treatment attenuated LPS-induced expression of TNF-alpha in the spleen as well as plasma levels of this cytokine and altered the central balance between pro- and anti-inflammatory cytokines (IL-1 beta/IL-10). These results open new vistas in the pharmacological activity of tianeptine and provide further insights on the possible mechanisms of action involved in its neuroprotective properties.

Immune consequences of the spontaneous pro-inflammatory status in depressed elderly patients

INTRODUCTION

The aim of the study was to describe the interrelationship between senescence, depression, and immunity.

METHODS

We assessed 10 elderly patients with depression and 10 age- and sex-matched controls: before, at one and at six month intervals after the anti-influenza vaccination. Levels of TNFalpha, IL6, ACTH, and cortisol, titres of anti-hemagglutinins and anti-neuraminidases, lymphocytes secreting IFNgamma, IL2, IL4, and IL10, cytotoxicity of NK and CD3+ CD8+ IFNgamma+ cells, anti-CMV antibodies, and CD28- CD57+ lymphocytes known to be associated with the CMV carrier status were evaluated.

RESULTS

Higher levels of anti-CMV, higher percentage of the CD28- CD57+ cells, and elevated levels of TNFalpha, IL6, and cortisol concomitant with decreased levels of ACTH and insufficient production of IL10 (which increased the IFNgamma+ /IL10+ ratio) were found in the patients suffering from depression, in comparison to healthy controls. The subjects with depression revealed a low NK cytotoxicity, while a level of CD3+ CD8+ IFNgamma+ cells was comparable between the groups. Although the levels of anti-hemagglutinins and anti-neuraminidases were low in the depressed patients, they reached the protective titres. The majority of these differences disappeared when CMV titres were entered into the analyses as a covariate.

DISCUSSION

The results suggest that the elderly depressed patients were characterised by increased exposure to CMV in the past, which could have resulted in a pro-inflammatory profile demonstrated as elevated levels of TNFalpha, IL6 and deficiency of suppressive IL10+ cells. These changes negatively affect humoral and innate response in the depressed patients.

Lower activities of serum peptidases predict higher depressive and anxiety levels following interferon-alpha-based immunotherapy in patients with hepatitis C

OBJECTIVE

There is evidence that in patients with chronic hepatitis C, immunotherapy with interferon-alpha (IFN alpha) may induce depression. A lowered activity of peptidases, such as prolylendopeptidase (PEP) and dipeptidyl peptidase IV (DPP IV), occurs in depression. This study examines whether lowered serum PEP or DPP IV activity before starting IFN alpha-based immunotherapy predicts the increase in depressive symptoms during immunotherapy.

METHOD

Serum PEP and DPP IV activities are measured in patients with hepatitis C before and 2, 4 and 16 weeks after starting IFN alpha-based immunotherapy. The Montgomery Asberg Depression Rating Scale (MADRS) and the Hamilton Anxiety Rating Scale (HAM-A) are completed.

RESULTS

Patients with lower baseline PEP or DPP IV had significantly higher MADRS and HAM-A scores both at baseline and during immunotherapy. Patients with lower baseline DPP IV had significantly higher increases in the MADRS following IFN alpha treatment.

CONCLUSION

Lower baseline PEP and DPP IV predict higher depressive and anxiety ratings during IFN alpha-based immunotherapy.

Stimulatory effect of antidepressants on the production of IL-6

A body of evidence indicates that the therapeutic activity of antidepressants is connected with their modulatory effect on the inflammatory response system and cell-mediated immunity. The present study was carried out to examine the effects of antidepressant agents, such as imipramne, venlafaxine, l-5-hydroxytryptophan, fluoxetine and a combination of l-5-hydroxytryptophan and fluoxetine, on the production of the pleotrophic cytokines TNF-alpha and IL-6. Diluted whole blood from fluoxetine-treated patients with treatment-resistant depression (TRD) (mean age: 50.6+/-3.9 years), age-matched healthy controls (mean age: 51.6+/-1.7 years) and younger healthy volunteers (mean age: 35.4+/-1.7 years) was stimulated with phytohemagglutinin (PHA) and lipopolysaccharide (LPS) for 48 h with or without incubation with the antidepressants at 10(-6) and 10(-5) M. The major findings of this study are: (1). imipramine and venlafaxine (at the higher concentration), 5-HTP (at lower and higher concentrations) and a combination of 5-HTP and fluoxetine (both at the lower concentration) increased the production of IL-6; (2). all drugs used did not affect TNF-alpha production. IL-6 production was significantly higher in depressed patients than in age-matched volunteers, whereas TNF-alpha production was significantly higher in older volunteers than in younger ones. We speculate that the therapeutic activity of these antidepressants is at least partly connected with their effect on the cytokine network and IL-6 production.

Raised plasma levels of tumor necrosis factor alpha in patients with depression: normalization during electroconvulsive therapy

OBJECTIVE

To examine whether electroconvulsive therapy (ECT) could modulate tumor necrosis factor (TNF)alpha levels in patients with depressive disorders.

METHOD

Plasma levels of TNFalpha were analyzed in 23 depressed patients, mainly with severe depressive disorders, and in 15 sex- and age-matched healthy controls. Fifteen depressed patients were followed longitudinally with measurement of TNFalpha before, during, and after repeated ECT treatment. For comparison, TNFalpha levels were also analyzed longitudinally in the 8 depressed patients not receiving ECT.

RESULTS

Patients with depressive disorders had markedly raised TNFalpha levels compared with healthy controls. The clinical improvement during repeated ECT was accompanied by a gradual and significant decline in TNFalpha level, reaching levels comparable with those in healthy controls at the end of the study. Such a decline was not seen in the depressed patients not receiving ECT, who instead showed raised TNFalpha levels throughout the study period.

CONCLUSION

Our findings support an association between inflammation and TNFalpha in particular and severe depression, and suggest that ECT may down-regulate this immune activation.

The plasma levels of interleukin-12 in schizophrenia, major depression, and bipolar mania: effects of psychotropic drugs

Interleukin-12 (IL-12) plays a key role in promoting T helper 1 (Th1) responses and subsequent cell-mediated immunity. Given the role of cytokines in the pathogenesis of psychiatric disorders, the dysregulation of IL-12 in these illnesses would be expected. We measured the plasma levels of IL-12 in 102 psychiatric patients (43 schizophrenia, 34 major depression and 25 bipolar disorder) and 85 normal controls. In addition, IL-12 levels of the patients were measured after an 8-week treatment to assess whether the levels were affected by medication. The IL-12 levels of the patient group with major depression were significantly higher than that of the control group, whereas no differences were found among the other groups. IL-12 values of the three patient groups decreased significantly after 8 weeks of treatment. These findings support the hypothesis that activation of the inflammatory response system and in particular of Th-1-like cells, is involved in the pathophysiology of major depression and that repeated administration of antidepressive and antipsychotic drugs may suppress IL-12 plasma concentrations in psychiatric patients.

The non-steroidal anti-inflammatory drug diclofenac sodium attenuates IFN-alpha induced alterations to monoamine turnover in prefrontal cortex and hippocampus

Interferon-alpha (IFN-alpha) administration induces major depression in a significant number of patients undergoing treatment for viral illnesses and other chronic diseases. Non-steroidal anti-inflammatory drugs (NSAIDs) are known to counteract a number of IFN-alpha-induced side effects, including pro-inflammatory cytokine activation and stress hormone release. To investigate this possibility further, we sought to determine the effect of the NSAID diclofenac sodium on monoamine turnover in brain induced by acute IFN-alpha exposure. Eleven male, Wistar rats (8 weeks old) were pretreated with diclofenac (20 mg/kg, s.c.) or saline, followed by intracerebroventricular (i.c.v.) infusion of IFN-alpha (1000 IU in 5 microl) or vehicle. The prefrontal cortex, striatum, and hippocampus were isolated and samples were assayed for monoamines and major metabolites by high-pressure liquid chromatography with electrochemical detection. The data show that acute IFN-alpha increased serotonin turnover in prefrontal cortex and increased dopamine turnover in hippocampus, while pre-treatment with diclofenac completely prevented these neurochemical responses. Importantly, these changes were recorded in two brain areas known to be important in depression and antidepressant action. These data offer support for a novel role of NSAIDs in modulating IFN-alpha-induced neurochemical alterations, and raise the possibility of the use of NSAIDs for the prevention of IFN-alpha-induced depression.