Baseline immune activation as a risk factor for the onset of depression during interferon-alpha treatment

Brain-immune crosstalk in the treatment of major depressive disorder

A growing number of studies are pointing out the need for a conceptual shift from a brain-centered to a body-inclusive approach in mental health research. In this perspective, the link between the immune and the nervous system, which are deeply interconnected and continuously interacting, is one of the most important novel theoretical framework to investigate the biological bases of major depressive disorder and, more in general, mental illness. Indeed, depressed patients show high levels of inflammatory markers, administration of pro-inflammatory drugs triggers a depressive symptomatology and antidepressant efficacy is reduced by excessive immune system activation. A number of molecular and cellular mechanisms have been hypothesized to act as a link between the immune and brain function, thus representing potential pharmacologically targetable processes for the development of novel and effective therapeutic strategies. These include the modulation of the kynurenine pathway, the crosstalk between metabolic and inflammatory processes, the imbalance in acquired immune responses, in particular T cell responses, and the interplay between neural plasticity and immune system activation. In the personalized medicine approach, the assessment and regulation of these processes have the potential to lead, respectively, to novel diagnostic approaches for the prediction of treatment outcome according to the patient's immunological profile, and to improved efficacy of antidepressant compounds through immune modulation.

Depression-free after Interferon-α exposure indicates less incidence of depressive disorder: A longitudinal study in Taiwan

BACKGROUND

IFN-α-induced depression in patients undergoing hepatitis C virus (HCV) treatment provides powerful support for the inflammation hypothesis of depression. Most studies have focused on the occurrence of depressive symptoms, but there has been no study yet in depression-free HCV patients receiving IFN-α. We hypothesized that HCV patients who did not develop depression after IFN-α exposure might have a lower incidence of depressive disorders after the IFN-α treatment.

METHODS

We conducted a twelve-year population-based cohort study of chronic HCV patients who received IFN-α therapy. The data were obtained from the Taiwan National Health Insurance Research Database. The study cohort was patients without any depressive disorder nor antidepressant use before and during IFN-α therapy. They were matched randomly by age, sex income and urbanization at a ratio of 1:4 with the control cohort of HCV patients without IFN-α therapy. The follow-up started after the last administration of IFN-α, and the primary outcome was the incidence of depressive disorders after IFN-α therapy.

RESULTS

A total of 20,468 depression-free subjects were identified from records of HCV patients receiving IFN-α therapy. Patients without IFN-α-induced depression were associated with a significantly lower incidence (per 10,000 person-years) of new-onset depressive disorders (126.8, 95% Confidential Interval [CI] of 118.5-135.6) as compared to the control cohort (145.2, 95% CI of 140.0-150.6) (p < 0.001). After adjusting for age, sex, income, urbanization and comorbid diseases, the crude hazard ratio for the incident depressive disorder was 0.87 (95% CI, 0.80-0.87) and the adjusted hazard ratios was 0.79 (95% CI, 0.72-0.87) for IFN-α-induced depression-free subjects as compared to the controls.

DISCUSSION

Our study indicates that IFN-α treated depression-free patients have a lower risk for depressive disorders. This hypothesized mechanism might derive from an IFN-α-induced resilience factor as yet to be defined.

CONCLUSIONS

Our study might suggest a new possibility for a new pharmacological strategy against depression.

Ω-3 fatty acids-supplementary in gestation alleviates neuroinflammation and modulates neurochemistry in rats

Background

The mechanisms underlying the association between immune activation and postpartum depression remained elusive. Although Ω-3 fatty acids possess anti-inflammatory properties, there is limited evidence directly linking the modulating effects of Ω-3 fatty acids on neuroimmune and neurochemistry to the antidepressant actions.

Methods

A between-groups design was used to assess the effects of reproductive status (virgin or parous) and Ω-3 fatty acids content (control and supplementary). Serum inflammatory cytokine levels (IL-1a, IL-1β, IL-2, IL-6, IL-12, TNF-a, IFN-γ) were evaluated using the Bio-Plex Luminex System. Moreover, we also measured the protein levels of Purinergic type 2X7 receptor (P2X7R), NOD-like receptor pyrin domain containing 3 (NLRP3) and Nuclear factor-kappaB (NF-κB). Lastly, we assessed the function of various neurotransmitter systems to link the inflammatory response and neurotransmitter metabolism.

Results

Pro-inflammatory cyrokines, including IL-1a, IL-6, TNF-a and IFN-γ were markedly induced in the serum of parous rats, although no significantly depressive-like behavior was found. Meanwhile, NLRP3 and NF-κB were decreased in certain brain areas. Moreover, gestational stress significantly induced neurochemical disturbance, which is partly restored by Ω-3 fatty acids supplementation.

Conclusions

These findings strengthen the link between inflammation, neurochemistry and postpartum depression, and further provide novel insights into the antidepressant effect of Ω-3 fatty acids.

Interferon-Alpha Reduces Human Hippocampal Neurogenesis and Increases Apoptosis via Activation of Distinct STAT1-Dependent Mechanisms

BACKGROUND

In humans, interferon-α treatment for chronic viral hepatitis is a well-recognized clinical model for inflammation-induced depression, but the molecular mechanisms underlying these effects are not clear. Following peripheral administration in rodents, interferon-α induces signal transducer and activator of transcription-1 (STAT1) within the hippocampus and disrupts hippocampal neurogenesis.

METHODS

We used the human hippocampal progenitor cell line HPC0A07/03C to evaluate the effects of 2 concentrations of interferon-α, similar to those observed in human serum during its therapeutic use (500 pg/mL and 5000 pg/mL), on neurogenesis and apoptosis.

RESULTS

Both concentrations of interferon-α decreased hippocampal neurogenesis, with the high concentration also increasing apoptosis. Moreover, interferon-α increased the expression of interferon-stimulated gene 15 (ISG15), ubiquitin-specific peptidase 18 (USP18), and interleukin-6 (IL-6) via activation of STAT1. Like interferon-α, co-treatment with a combination of ISG15, USP18, and IL-6 was able to reduce neurogenesis and enhance apoptosis via further downstream activation of STAT1. Further experiments showed that ISG15 and USP18 mediated the interferon-α-induced reduction in neurogenesis (potentially through upregulation of the ISGylation-related proteins UBA7, UBE2L6, and HERC5), while IL-6 mediated the interferon-α-induced increase in apoptosis (potentially through downregulation of aquaporin 4). Using transcriptomic analyses, we showed that interferon-α regulated pathways involved in oxidative stress and immune response (e.g., Nuclear Factor (erythroid-derived 2)-like 2 [Nrf2] and interferon regulatory factor [IRF] signaling pathway), neuronal formation (e.g., CAMP response element-binding protein [CREB] signaling), and cell death regulation (e.g., tumor protein(p)53 signaling).

CONCLUSIONS

We identify novel molecular mechanisms mediating the effects of interferon-α on the human hippocampus potentially involved in inflammation-induced neuropsychiatric symptoms.

Pathogen-Host Defense in the Evolution of Depression: Insights into Epidemiology, Genetics, Bioregional Differences and Female Preponderance

Significant attention has been paid to the potential adaptive value of depression as it relates to interactions with people in the social world. However, in this review, we outline the rationale of why certain features of depression including its environmental and genetic risk factors, its association with the acute phase response and its age of onset and female preponderance appear to have evolved from human interactions with pathogens in the microbial world. Approaching the relationship between inflammation and depression from this evolutionary perspective yields a number of insights that may reveal important clues regarding the origin and epidemiology of the disorder as well as the persistence of its risk alleles in the modern human genome.

Mental disorders in HIV/HCV coinfected patients under antiviral treatment for hepatitis C

This paper aims to review the epidemiology and management of mental disorders in human immunodeficiency virus (HIV)/hepatitis C virus (HCV) coinfected patients, the need for antiviral therapy in this specific population, and current treatment strategies for HIV/HCV patients with psychiatric and/or substance use disorders. This is a narrative review. Data was sourced from electronic databases and was not limited by language or date of publication. HIV infection has become a survivable chronic illness. Prevalence of HCV infection among HIV-infected patients is high ranging from 50% to 90%. Patients with psychiatric diseases have also an increased risk for HIV/HCV coinfection. The most effective strategy to decrease HCV-related morbidity and mortality in coinfection is to achieve viral eradication. Although psychiatric symptoms often appear during antiviral treatment and may be associated with the use of interferon-alpha (IFN-α), recent evidence suggests that many patients with comorbid mental and substance use disorders can be treated safely. Recent data indicate that IFNα-induced psychiatric side effects have a similar prevalence in HIV/HCV coinfected patients than in monoinfected patients and they can be managed and even prevented successfully with psychopharmacological strategies in the frame of a multidisciplinary team. New antivirals offer INF-free therapies for this specific population.

Transcriptomics in Interferon-α-Treated Patients Identifies Inflammation-, Neuroplasticity- and Oxidative Stress-Related Signatures as Predictors and Correlates of Depression

Owing to the unique opportunity to assess individuals before and after they develop depression within a short timeframe, interferon-α (IFN-α) treatment for chronic hepatitis C virus (HCV) infection is an ideal model to identify molecular mechanisms relevant to major depression, especially in the context of enhanced inflammation. Fifty-eight patients were assessed prospectively, at baseline and monthly over 24 weeks of IFN-α treatment. New-onset cases of depression were determined using the Mini International Neuropsychiatric Interview (MINI). Whole-blood transcriptomic analyses were conducted to investigate the following: (1) baseline gene expression differences associated with future development of IFN-α-induced depression, before IFN-α, and (2) longitudinal gene expression changes from baseline to weeks 4 or 24 of IFN-α treatment, separately in those who did and did not develop depression. Transcriptomics data were analyzed using Partek Genomics Suite (1.4-fold, FDR adjusted p⩽0.05) and Ingenuity Pathway Analysis Software. Twenty patients (34%) developed IFN-α-induced depression. At baseline, 73 genes were differentially expressed in patients who later developed depression compared with those who did not. After 4 weeks of IFN-α treatment, 592 genes were modulated in the whole sample, representing primarily IFN-α-responsive genes. Substantially more genes were modulated only in patients who developed depression (n=506, compared with n=70 in patients who did not), with enrichment in inflammation-, neuroplasticity- and oxidative stress-related pathways. A similar picture was observed at week 24. Our data indicate that patients who develop IFN-α-induced depression have an increased biological sensitivity to IFN-α, as shown by larger gene expression changes, and specific signatures both as predictors and as correlates.

Co-occurring Depression, Chronic Pain and Substance Use Disorders in People with Hepatitis C

Chronic infection with Hepatitis C virus (HCV) is common and can result in serious and sometimes fatal liver complications. The impact of HCV on the liver can be further complicated by medical and psychological comorbidities. Depression, substance use, and pain syndromes are frequent co-morbid conditions in people with HCV and diminish functioning, quality of life, and treatment compliance. Understanding the underlying biological mechanisms of these comorbid conditions within the context of HCV may help elucidate factors contributing to their co-occurrence, perhaps mediatedviapro-inflammatory cytokines. The current review provides a synthesis of the literature on depression, substance use disorders and chronic pain in the presence of HCV. The review includes studies conducted with both veteran and civilian populations. The implications for assessment and antiviral treatment of HCV will be considered.

Brief mindfulness training reduces salivary IL-6 and TNF-α in young women with depressive symptomatology

OBJECTIVE

Pro-inflammatory cytokines have been implicated in the pathophysiology and maintenance of depression. This study investigated the effects of a brief mindfulness intervention on salivary pro-inflammatory correlates of depression (IL-6, TNF-α) and self-reported symptoms of depression in college women.

METHODS

Sixty-four females with a cut score of ≥16 on the Center for Epidemiological Studies for Depression Scale (CES-D) were assigned to a 4-week mindfulness-based intervention (MBI; N = 31) or a contact-control group (N = 33). For both groups, salivary cytokines and depressive symptoms were assessed at baseline and posttreatment. For the mindfulness group only, salivary cytokines were also assessed at a 3-month follow-up.

RESULTS

Both groups showed similar reductions in depression. However, MBI (vs. control) predicted greater reductions in IL-6 and TNF-α; changes in IL-6 were sustained at 3-month follow-up. Higher baseline depressive symptoms predicted greater reductions in inflammation in the mindfulness group.

CONCLUSION

MBIs may reduce inflammatory immune markers commonly implicated in depression. Individuals with greater depressive symptoms may benefit more from mindfulness training. Although reductions in salivary cytokines in the mindfulness condition were not attributable to changes in depressive symptoms, future work should examine the possibility that such reductions are protective against the development of future depressive episodes. (PsycINFO Database Record

Beneficial impact of intracerebroventricular fractalkine administration on behavioral and biochemical changes induced by prenatal stress in adult rats: Possible role of NLRP3 inflammasome pathway

Several lines of evidence indicate that adverse experience in early life may be a triggering factor for pathological inflammatory processes and lead to the development of depression. Fractalkine (CX3CL1), a chemokine, plays an important role not only in the migration, differentiation and proliferation of neuronal and glial cells but also in the regulation of neuronal-microglial signaling and the production of pro-inflammatory factors. In the present study, we examined the impact of a prenatal stress procedure on the expression of fractalkine in the hippocampus and frontal cortex of young and adult male rats. Furthermore, we measured the age-dependent effect of stress during pregnancy on the expression of pro-inflammatory factors IL-1β, IL-18, TNF-α, IL-6, and CCL2 in both brain structures. Next, to illustrate the link between fractalkine signaling and the behavioral and biochemical changes induced by prenatal stress, adult prenatally stressed offspring were injected intracerebroventricularly (icv) with exogenous fractalkine. We reported that prenatal stress leads to long-lasting deficits in fractalkine signaling and enhanced inflammatory activation. The study demonstrates that icv administration of fractalkine attenuates the behavioural changes evoked by prenatal stress procedure in adult animals. Moreover, fractalkine administration, exhibits anti-inflammatory action, mainly in the frontal cortex of adult prenatally stressed rats. The effect of fractalkine is related to inhibition of NLRP3 inflammasome. However, its action on the other members of NOD-like receptor family (NLR) cannot be excluded. These findings provide new in vivo evidence that the behavioral and inflammatory disturbances observed in adult prenatally stressed rats may be related to long-lasting malfunctions in fractalkine signaling.

Insights from interferon-α-related depression for the pathogenesis of depression associated with inflammation

Interferon-α (IFN-α) is a pleiotropic cytokine that is administered as a therapeutic in highly prevalent medical conditions such as chronic hepatitis C and B virus infection, melanoma and lymphoma. IFN-α induces, to a clinically relevant degree, concentration, memory, drive and mood disturbances in almost half of all patients. For this reason, IFN-α is increasingly being replaced by more specifically acting drugs. In the past decades, IFN-α has offered a valuable insight into the pathogenesis of major depression, particularly in settings associated with inflammation. IFN-α triggers immune responses, hypothalamo-pituitary-adrenal axis abnormalities and disturbances of brain metabolism resembling those in other depression states. IFN-α stimulates indoleamine-2,3 dioxygenase-1, activating the kynurenine pathway with reduced formation of the neurotransmitters serotonin and dopamine, excessive formation of the NMDA agonist quinolinic acid, and reduced formation of the NMDA antagonist kynurenic acid. In addition, IFN-α disturbs neurotrophic signaling and impedes neurite outgrowth, synaptic plasticity, endogenous neurogenesis and neuronal survival. Consequently, IFN-α-related depression may represent a model for the neurodegenerative changes that are noticed in late-life major depression. Indeed, the observation that brain responses in IFN-α-related depression resemble idiopathic depression is supported by the existence of common genetic signatures, among which of note, a number of neuronal survival and plasticity genes have been identified. In view of the high incidence of depressive symptoms, IFN-α-related depression is an attractive model for studying links between neuronal plasticity, neurodegeneration and depression. We predict that in the latter areas new targets for anti-depressant therapies could be identified, which may deepen our understanding of idiopathic major depression.

A phase-specific neuroimmune model of clinical depression

Immune dysfunction and pro-inflammatory states in particular have been implicated in the aetiology and pathogenesis of depression. Whilst the onset of an episode and certain symptoms of depression appear well explained by this inflammatory model, the underpinnings of the episodic and progressive nature, as well as relapse and remission status in depression require attention. In this review it is suggested that additional immune factors beyond pro- and anti-inflammatory cytokines may effectively contribute to the understanding of the neurobiology of clinical depression. Considering neurobiological effects of immunomodulatory factors such as T cells, macrophages, microglia and astrocytes relevant to depression, we suggest a neuroimmune model of depression underpinned by dynamic immunomodulatory processes. This perspective paper then outlines a neuroimmune model of clinical phases of depression in an attempt to more adequately explain depression-like behaviours in pre-clinical models and the dynamic nature of depression in clinical populations. Finally, the implications for immunomodulatory treatments of depression are considered.

Pegylated interferon pharmacokinetics and self-reported depressive symptoms during antiviral treatment for chronic hepatitis C

BACKGROUND

Pegylated interferon-2a (PegIFN-2a)+ribavirin treatment for chronic hepatitis C is often associated with depressive symptoms. Previous studies have failed to explore whether PegIFN-2a pharmacokinetic variability plays an etiologic role in PegIFN-2a-induced mood disorders. The objective of this investigation was to evaluate the association between trough PegIFN-2a concentration at treatment week 4 ("PegIFN-2a Cmin4") and an increase in depressive symptoms.

METHODS

Using data from Virahep-C, the association between PegIFN-2a Cmin4 and the following depression outcomes were evaluated using the Center for Epidemiological Studies-Depression scale (CES-D): (1) change in CES-D score from baseline to week 12; (2) greatest difference in CES-D score between baseline and weeks 4, 12, or 24; and (3) occurrence of severe depressive symptoms (CES-D greater than 23) at weeks 4, 12, or 24. One post-hoc analysis examined whether PegIFN-2a exposure during the first week of treatment was associated with change in CES-D score from baseline to week 4.

RESULTS

No significant associations between PegIFN-2a Cmin4 and the depression outcomes were observed (p>0.05). Exploratory analyses suggest a possible relationship between PegIFN-2a exposure during the first week of therapy and CES-D score change from baseline to week 4 (p=0.03).

CONCLUSIONS

PegIFN-2a concentration levels from baseline to week 4 do not predict the onset and severity of depressive symptoms during 24 weeks of antiviral therapy; however PegIFN-2a levels during the first week of treatment may predict depressive symptoms in the first 4 weeks, earlier than anticipated and warrants further exploration.

The role of the neuroendocrine and immune systems in the pathogenesis of depression

Development of depression is associated with the body's response to prolonged stress, which adversely affects the functioning of the nervous, endocrine and immune systems. Prolonged stress can lead to the development of a so-called allostatic load and reduction of concentration of brain-derived neurotrophic factor. These changes result in impairment of neurogenesis and synaptic remodeling process. This article illustrates the involvement of key mediators of allostasis such as the neuroendocrine and immune systems, in the pathogenesis of depression. The literature concerning the contribution of the neuroendocrine and immune systems to depression incidence was reviewed. Development of depression is associated with disturbance of the body's allostasis and inflammatory activation of the immune system. It leads to a chronic increase in the concentration of cortisol and proinflammatory cytokines, which results in an allostatic load. This load leads to neurodegeneration, eventually causing irreversible cognitive impairment and permanent disability. Determination of the concentration of chemokines and their receptors is an important indicator of activation of the immune and neuroendocrine systems. The activity of these systems reflects the severity of the disease and provides important information for effective antidepressant treatment.

Multi-analyte profile analysis of plasma immune proteins: altered expression of peripheral immune factors is associated with neuropsychiatric symptom severity in adults with and without chronic hepatitis C virus infection

BackgroundThe purpose of this study was to characterize hepatitis C virus (HCV)-associated differences in the expression of 47 inflammatory factors and to evaluate the potential role of peripheral immune activation in HCV-associated neuropsychiatric symptoms-depression, anxiety, fatigue, and pain. An additional objective was to evaluate the role of immune factor dysregulation in the expression of specific neuropsychiatric symptoms to identify biomarkers that may be relevant to the treatment of these neuropsychiatric symptoms in adults with or without HCV. MethodsBlood samples and neuropsychiatric symptom severity scales were collected from HCV-infected adults (HCV+, n = 39) and demographically similar noninfected controls (HCV-, n = 40). Multi-analyte profile analysis was used to evaluate plasma biomarkers. ResultsCompared with HCV- controls, HCV+ adults reported significantly (P < 0.050) greater depression, anxiety, fatigue, and pain, and they were more likely to present with an increased inflammatory profile as indicated by significantly higher plasma levels of 40% (19/47) of the factors assessed (21%, after correcting for multiple comparisons). Within the HCV+ group, but not within the HCV- group, an increased inflammatory profile (indicated by the number of immune factors > the LDC) significantly correlated with depression, anxiety, and pain. Within the total sample, neuropsychiatric symptom severity was significantly predicted by protein signatures consisting of 4-10 plasma immune factors; protein signatures significantly accounted for 19-40% of the variance in depression, anxiety, fatigue, and pain. ConclusionsOverall, the results demonstrate that altered expression of a network of plasma immune factors contributes to neuropsychiatric symptom severity. These findings offer new biomarkers to potentially facilitate pharmacotherapeutic development and to increase our understanding of the molecular pathways associated with neuropsychiatric symptoms in adults with or without HCV.

Biological phenotypes underpin the physio-somatic symptoms of somatization, depression, and chronic fatigue syndrome

OBJECTIVE

Somatization is a symptom cluster characterized by 'psychosomatic' symptoms, that is, medically unexplained symptoms, and is a common component of other conditions, including depression and myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS). This article reviews the data regarding the pathophysiological foundations of 'psychosomatic' symptoms and the implications that this has for conceptualization of what may more appropriately be termed physio-somatic symptoms.

METHOD

This narrative review used papers published in PubMed, Scopus, and Google Scholar electronic databases using the keywords: depression and chronic fatigue, depression and somatization, somatization and chronic fatigue syndrome, each combined with inflammation, inflammatory, tryptophan, and cell-mediated immune (CMI).

RESULTS

The physio-somatic symptoms of depression, ME/CFS, and somatization are associated with specific biomarkers of inflammation and CMI activation, which are correlated with, and causally linked to, changes in the tryptophan catabolite (TRYCAT) pathway. Oxidative and nitrosative stress induces damage that increases neoepitopes and autoimmunity that contribute to the immuno-inflammatory processes. These pathways are all known to cause physio-somatic symptoms, including fatigue, malaise, autonomic symptoms, hyperalgesia, intestinal hypermotility, peripheral neuropathy, etc.

CONCLUSION

Biological underpinnings, such as immune-inflammatory pathways, may explain, at least in part, the occurrence of physio-somatic symptoms in depression, somatization, or myalgic encephalomyelitis/chronic fatigue syndrome and thus the clinical overlap among these disorders.

Serotonin and interleukin-6: the role of genetic polymorphisms in IFN-induced neuropsychiatric symptoms

BACKGROUND

Cytokines and serotonin neurotransmission may play an important role on the development of psychopathological symptoms during interferon (IFN) treatment. The aim of the present study was to investigate the association between IFN-induced depression, anxiety and fatigue and functional genetic variants at the interleukin-6 gene (IL-6) and serotonin transporter gene (SERT).

METHODS

385 consecutive Caucasian outpatients with chronic hepatitis C initiating treatment with IFN-alpha and ribavirin were included. All patients were interviewed at baseline using the Structured Clinical Interview for DSM-IV (SCID-I) and those with a current major depressive disorder or anxiety disorder before starting treatment were excluded. Depression and anxiety were assessed at baseline during the treatment (at 4, 12, 24 and 48 weeks) using the Hospital Anxiety and Depression Scale and fatigue was evaluated using a visual analogue scale. The 5-HTTLPR region of SERT gene and the functional polymorphism located at the promoter region of IL-6 gene (rs1800795) were genotyped.

RESULTS

Genotypic distribution was in the Hardy-Weinberg equilibrium for SERT (p=0.41) and for IL-6 (p=0.72) polymorphisms. At baseline we found only a significant effect of IL-6 polymorphism on fatigue symptoms. During antiviral treatment we reported that subjects with CC genotype (IL-6) presented significantly lower changes from baseline in IFN-induced depression (p=0.005) and IFN-induced anxiety (p=0.004). We did not find statistically significant differences on depression (p=0.21) or anxiety (p=0.15) between SS/SL and LL genotypes of SERT.

CONCLUSIONS

Genetic variations in the IL-6 gene increase the risk of IFN-induced depression and anxiety. The IL-6 polymorphism was associated with fatigue rates in patients with chronic hepatitis C before treatment. Our study confirms the role of inflammatory mechanisms in IFN-induced psychopathological symptoms.

Central administration of murine interferon-α induces depressive-like behavioral, brain cytokine and neurochemical alterations in mice: a mini-review and original experiments

A role for pro-inflammatory cytokines and their neuroinflammatory signaling cascades in depressive pathology has increasingly gained acceptance. In this regard, several lines of evidence suggested that interleukin-1β (IL-1β) and tumor necrosis factor-α (TNF-α) can provoke neurochemical and hormonal changes akin to those associated with psychological stressors, and that these cytokines also induce sickness behaviors that resemble some of the neurovegetative features of depression. Similarly, human depressed patients often display marked changes of pro-inflammatory cytokine levels and immune cell activity. Perhaps more germane in the analysis of the cytokine-depression connection, reports of humans undergoing interferon-α (IFN-α) treatment for certain cancers or viral infections have indicated that the pro-inflammatory cytokine caused signs of major depression in a substantial subset of those treated. In the present investigation, we demonstrated that acute or repeated infusion of IFN-α into the lateral ventricles provoked depressive-like behavior and concomitant changes in serotonin (5-HT) and mRNA expression of particular 5-HT receptors and pro-inflammatory cytokines. These actions were less evident following administration directly into the prefrontal cortex and not apparent at all when administered to the dorsal raphe nucleus. The data are discussed in relation to the induction of depression elicited by IFN-α, and are presented in the context of a mini-review that highlights potential mechanisms through which the cytokine might act to promote psychomotor and affective disturbances and interact with stressors.

Depression as an evolutionary strategy for defense against infection

Recent discoveries relating depression to inflammation and immune function may help to solve an important evolutionary puzzle: If depression carries with it so many negative consequences, including notable costs to survival and reproduction, then why is it common and heritable? What countervailing force or compensatory advantage has allowed susceptibility genes for depression to persist in the population at such high rates? A priori, compensatory advantages in combating infection are a promising candidate, given that infection has been the major cause of mortality throughout human history. Emerging evidence on deeply rooted bidirectional pathways of communication between the nervous and immune systems further supports this notion. Here we present an updated review of the "infection-defense hypothesis" of depression, which proposes that moods-with their ability to orchestrate a wide array of physical and behavioral responses-have played an adaptive role throughout human history by helping individuals fight existing infections, as well as helping both individuals and their kin avoid new ones. We discuss new evidence that supports several key predictions derived from the hypothesis, and compare it with other major evolutionary theories of depression. Specifically, we discuss how the infection-defense hypothesis helps to explain emerging data on psychoimmunological features of depression, as well as depression's associations with a diverse array of conditions and illnesses-including nutritional deficiencies, seasonal changes, hormonal fluctuations, and chronic diseases-that previous evolutionary theories of depression have not accounted for. Finally, we note the potential implications of the hypothesis for the treatment and prevention of depression.

Tyrosine metabolism during interferon-alpha administration: association with fatigue and CSF dopamine concentrations

Chronic exposure to interferon (IFN)-alpha, an innate immune cytokine, produces high rates of behavioral disturbances, including depression and fatigue. These effects may be mediated by the actions of IFN-alpha on dopamine (DA) metabolism in the basal ganglia. Diminished conversion of phenylalanine (Phen) to tyrosine (Tyr), the primary amino acid precursor of DA, has been associated with inflammation, and may reflect decreased activity of the enzyme phenylalanine-hydroxylase (PAH). This study investigated the peripheral Phen/Tyr ratio in relation to cerebrospinal fluid (CSF) concentrations of DA and its metabolites in subjects treated with IFN-alpha plus ribavirin for hepatitis C and controls awaiting IFN-alpha therapy. Plasma Phen/Tyr ratios were significantly increased in IFN-alpha-treated subjects (n=25) compared to controls (n=9), and were negatively correlated with CSF DA (r=-0.59, df=15, p<0.05) and its metabolite, homovanillic acid (r=-0.67, df=15, p<0.01), and positively correlated with fatigue (r=0.44, df=23, p<.05) in IFN-alpha-treated patients but not controls. Given the role of tetrahydrobiopterin (BH4) in the PAH conversion of Phen to Tyr, CSF concentrations of BH4 and its inactive oxidized form, dihydrobiopterin (BH2), were examined along with CSF interleukin (IL)-6 in a subset of patients. BH2 concentrations were significantly increased in IFN-alpha-treated patients (n=12) compared to controls (n=7), and decreased CSF BH4 concentrations correlated with increased CSF IL-6 (r=-0.57, df=12, p<0.05). These results indicate that IFN-alpha is associated with decreased peripheral conversion of Phen to Tyr, which in turn is associated with reduced DA in the brain as well as fatigue. These alterations may be related to oxidation of BH4 secondary to IFN-alpha-induced activation of a CNS inflammatory response.

Interplay between pro-inflammatory cytokines and growth factors in depressive illnesses

The development of depressive disorders had long been attributed to monoamine variations, and pharmacological treatment strategies likewise focused on methods of altering monoamine availability. However, the limited success achieved by treatments that altered these processes spurred the search for alternative mechanisms and treatments. Here we provide a brief overview concerning a possible role for pro-inflammatory cytokines and growth factors in major depression, as well as the possibility of targeting these factors in treating this disorder. The data suggest that focusing on one or another cytokine or growth factor might be counterproductive, especially as these factors may act sequentially or in parallel in affecting depressive disorders. It is also suggested that cytokines and growth factors might be useful biomarkers for individualized treatments of depressive illnesses.

Vulnerability to somatic symptoms of depression during interferon-alpha therapy for hepatitis C: a 16-week prospective study

OBJECTIVE

This study evaluated the distinctive clinical and biological manifestations of depressive symptom subtypes (i.e., cognitive-affective and somatic) in Veterans with hepatitis C viral infection (HCV) before and during interferon-alpha (IFN) based antiviral therapy.

METHODS

Thirty-two Veterans with HCV and no prior history of IFN therapy were followed prospectively during the first 16weeks of therapy to evaluate depressive symptoms and to determine if baseline cytokine and serotonin levels predicted subsequent changes in depressive scores.

RESULTS

IFN therapy resulted in a significant increase in total depressive symptoms from baseline (week 0) to week 16, with neurovegetative and somatic symptoms of depression including loss of appetite, fatigue and irritability increasing within the first two weeks of therapy and continuing to increase throughout IFN therapy. When depressive symptoms were evaluated using a two-factor (i.e., Cognitive-Affective and Somatic) model, the Cognitive-Affective factor score did not change significantly following IFN therapy initiation, while the Somatic factor score showed a significant increase from week 0 to week 16. Veterans with the largest increases in somatic symptoms from week 0 to week 2 had significantly higher levels of tumor necrosis factor-alpha (TNF-α) and lower levels of serotonin at baseline, as compared to Veterans with minimal or no increase in somatic symptoms.

CONCLUSION

Somatic symptoms of depression can be significantly exacerbated during IFN therapy and may be predicted by higher TNF-α levels and lower serotonin levels at baseline.

Hepatitis C infection, antiviral treatment and mental health: a European expert consensus statement

Mental health problems frequently occur in chronic infection with the hepatitis C virus (HCV) and during antiviral treatment with pegylated interferon-alpha (PegIFNα) and ribavirin. Depression is one of the most important complications during antiviral treatment of chronic hepatitis C infection. However, an increased prevalence of depression, fatigue, and cognitive disturbances has also been reported in untreated HCV-positive patients. Patients with psychiatric disorders or drug addiction also have an increased risk of HCV infection. Furthermore, because of possible drug-drug interactions, new antivirals administered together with PegIFNα and ribavirin may complicate psychiatric side effect management, even if no specific psychiatric adverse events are known so far for these new drugs. The European liver patient's organization (ELPA) organised a European expert conference to review the literature and develop expert recommendations for the management of mental health problems in HCV infected patients. This paper results from the output of the 2011 EASL meeting and subsequent dialogue with patient groups and relevant experts in Europe. It summarises the current knowledge of HCV infection and the brain; prevalence, course, and neurobiology of IFN-α associated psychiatric side effects; possible risk factors for IFN-α associated depression and suicide attempts; psychiatric management of HCV infected patients before and during antiviral treatment; prevention of IFN- α associated psychiatric side effects; and psychiatric aspects of the new antivirals. The summarised current knowledge about mental health changes before and during antiviral treatment should improve interdisciplinary management of HCV infected patients.

Indoleamine 2,3-dioxygenase activation and depressive symptoms: results from the Young Finns Study

OBJECTIVE

To examine whether the activation of indoleamine 2,3-dioxygenase (IDO), an enzyme involved in serotonin production, is associated with depressive symptoms.

METHODS

The participants were 544 women and 442 men (aged 24-39 years) from the population-based Young Finns Study who participated in a medical examination in 2001 (including IDO and depression) and 2007 (follow-up assessment for depression).

RESULTS

At baseline, IDO was associated with depressive symptoms (in the total cohort: B = 0.23, p < .001; women: B = 0.20, p = .007; men: B = 0.29, p = .002; p for interaction = .19). IDO at baseline was also associated with depressive symptoms at follow-up in women (B = 0.17, p = .03), which remained significant when adjusting for any of the biologic and behavioral risk factors. Adjusting for body mass index attenuated the association by 6%. In the final model including all baseline variables, none of the risk factors (except for baseline depressive symptoms) were associated with depressive symptoms at follow-up.

CONCLUSIONS

These data suggest that IDO activity may be a risk factor for future depression especially in women. IDO-induced alterations in serotonergic function may offer one biologic explanation to the well-established associations between inflammation and depression.

Cytokine levels in CSF and neuropsychological performance in HIV patients

HIV-associated dementia and its precursors are frequently observed complications of HIV infection, even in the presence of combination antiretroviral treatment (cART). The development, surveillance and treatment of this condition are still not completely understood. Cytokines, as immunological transmitters, may be one key to gaining a deeper understanding of the disease. A total of 33 HIV-positive male patients were evaluated by neuropsychological testing, lumbar and venous puncture, neuroimaging and neurological examination. The cytokine content in the CSF (cerebrospinal fluid) was examined by a solid-phase protein array. The Digit-Symbol Test, contraction time analysis, Rey-Osterrieth Figure and Grooved-Pegboard Test showed inferior results in the presence of an inflammatory CSF environment, whereas neuroprotective or anti-inflammatory conditions were correlated to better results in contraction time analysis. Higher CSF levels of cytokines were independently correlated with the duration of HIV infection. The study showed a correlation of cytokine levels in the CSF of HIV patients with test results of their neuropsychological functioning. The effect was pronounced with regard to the more complex executive tasks. Determining CSF cytokine levels may be a useful supplement to the assessment of HIV patients and contribute helpful information to predict neurocognitive performance. Therapeutic strategies to ameliorate a negative impact of an altered cytokine milieu may aid in slowing the evolution of neurocognitive dysfunction.

Cytokine production by leukocytes of military personnel with depressive symptoms after deployment to a combat-zone: a prospective, longitudinal study

Major depressive disorder (MDD) is frequently diagnosed in military personnel returning from deployment. Literature suggests that MDD is associated with a pro-inflammatory state. To the best of our knowledge, no prospective, longitudinal studies on the association between development of depressive symptomatology and cytokine production by peripheral blood leukocytes have been published. The aim of this study was to investigate whether the presence of depressive symptomatology six months after military deployment is associated with the capacity to produce cytokines, as assessed before and after deployment. 1023 military personnel were included before deployment. Depressive symptoms and LPS- and T-cell mitogen-induced production of 16 cytokines and chemokines in whole blood cultures were measured before (T0), 1 (T1), and 6 (T2) months after return from deployment. Exploratory structural equation modeling (ESEM) was used for data reduction into cytokine patterns. Multiple group latent growth modeling was used to investigate differences in the longitudinal course of cytokine production between individuals with (n = 68) and without (n = 665) depressive symptoms at T2. Individuals with depressive symptoms after deployment showed higher T-cell cytokine production before deployment. Moreover, pre-deployment T-cell cytokine production significantly predicted the presence of depressive symptomatology 6 months after return. There was an increase in T-cell cytokine production over time, but this increase was significantly smaller in individuals developing depressive symptoms. T-cell chemokine and LPS-induced innate cytokine production decreased over time and were not associated with depressive symptoms. These results indicate that increased T-cell mitogen-induced cytokine production before deployment may be a vulnerability factor for development of depressive symptomatology in response to deployment to a combat-zone. In addition, deployment to a combat-zone affects the capacity of T-cells and monocytes to produce cytokines and chemokines until at least 6 months after return.

Is depression an inflammatory disorder?

Studies consistently report that groups of individuals with major depressive disorder (MDD) demonstrate increased levels of a variety of peripheral inflammatory biomarkers when compared with groups of nondepressed individuals. These findings are often interpreted as meaning that MDD, even in medically healthy individuals, may be an inflammatory condition. In this article, we examine evidence for and against this idea by looking more closely into what the actual patterns of inflammatory findings indicate in terms of the relationship between MDD and the immune system. Data are presented in support of the idea that inflammation only contributes to depression in a subset of patients versus the possibility that the depressogenic effect of inflammatory activation is more widespread and varies depending on the degree of vulnerability any given individual evinces in interconnected physiologic systems known to be implicated in the etiology of MDD. Finally, the treatment implications of these various possibilities are discussed.

Early activation of p38 mitogen activated protein kinase is associated with interferon-alpha-induced depression and fatigue

Cytokine-induced stimulation of p38 mitogen activated protein kinase (MAPK) has been shown to influence behaviorally-relevant pathophysiologic pathways including monoamine neurotransmission and neuroendocrine function and thus may contribute to behavioral changes that occur during chronic administration of the innate immune cytokine, interferon (IFN)-alpha. Accordingly, in the current study, phosphorylation (activation) of intracellular p38 MAPK in peripheral blood lymphocytes was analyzed by flow cytometry every 2 h for 12 h following the initial injection of IFN-alpha in eleven patients with chronic hepatitis C. Hourly assessments of plasma concentrations of adrenocorticotropic hormone, cortisol and interleukin-6 were also obtained. Symptoms of depression and fatigue were measured at baseline and after 4 and 12 weeks of IFN-alpha treatment. Acute administration of IFN-alpha significantly increased the percentage of lymphocytes staining positive for intracellular phosphorylated p38 (p-p38). IFN-alpha-induced increases in p-p38 were significantly greater in patients that developed clinically significant depressive symptoms [Montgomery-Asberg Depression Rating Scale (MADRS) score≥15] during the first 12 weeks of IFN-alpha treatment. Increases in the percentage of p-p38-positive lymphocytes following the first IFN-alpha injection also highly correlated with depression severity at weeks 4 (r=0.85, p=0.001) and 12 (r=0.70, p=0.018). Similar relationships were observed for fatigue. Examination of relationships between p-p38 induction and factors previously reported to predict IFN-alpha-induced depressive symptoms revealed strong associations of p-p38 with baseline MADRS (r=0.82, p=0.002) and cortisol responses to the initial injection of IFN-alpha (r=0.91, p=0.000). Taken together, these findings indicate that sensitivity of p38 MAPK signaling pathways to immune stimulation is associated with depressive symptoms during chronic IFN-alpha treatment.

Persistent pro-inflammatory cytokines following the initiation of pegylated IFN therapy in hepatitis C infection is associated with treatment-induced depression

Pegylated interferon (IFN), the basis for chronic hepatitis C virus (HCV) treatment, causes depression in 30-40% of patients. The potential for cytokine mRNA patterns from baseline into early treatment to associate with the onset of treatment-induced depression (TID) was examined. Depression was measured by the Beck Depression Inventory at baseline and weeks 2, 4, 8 and 12 of treatment (n = 38). At baseline and weeks 2 and 4, peripheral blood mononuclear cell (PMBC, n = 28), isolated ex vivo, were examined for tumour neurosis factor (TNF)-alpha, interleukin (IL)-1beta and IL-10 mRNA expression. In patients that developed treatment-induced depression, pro-inflammatory TNF-alpha mRNA levels from baseline into week 4 of therapy remained constant (1.1-fold increase); whereas IL-1beta transcripts decreased 3.5 fold. However, corresponding TNF-alpha (3-fold, P < 0.05) and IL-1beta (7.5-fold) transcript expression diminished to a greater extent in the absence of TID. Changes in TNF-alpha mRNA values correlated to the average change in BDI scores over the 12 weeks (r = 0.56, P < 0.05). Concomitantly, anti-inflammatory IL-10 transcript levels decreased in (TID), relative to increased expression in the absence of TID (P < 0.05). The potential influence of IL-10 was observed upon calculation of individual pro- verses anti-inflammatory mRNA ratios. Stable in the presence of depression, TNF-alpha/IL-10 and IL-1beta/IL-10 mRNA ratios declined significantly over time in its absence (P < 0.05). This study suggests that in chronic HCV infection, upon pegylated IFN administration persistent pro-inflammatory cytokine MRNA expression associates with TID. In contrast, therapeutic activation of mechanisms that decrease pro-inflammatory immunity may protect against depression during therapy.

Depression is an inflammatory disease, but cell-mediated immune activation is the key component of depression

The first findings that depression is characterized by cell-mediated immune activation and inflammation were published between 1990-1993 (Maes et al.). Recently, it was reported that--based on meta-analysis results--depression is an inflammatory disorder because the plasma levels of two cytokines are increased, i.e. interleukin-(IL)-6 and tumor necrosis factor-α (TNFα). The same meta-analysis found that plasma IL-2 and interferon-(IFN)γ levels are not altered in depression, suggesting that there is no T cell activation in that illness. The present paper reviews the body of evidence that depression is accompanied by cell-mediated immune activation. The findings include: increased serum levels of the soluble IL-2 receptor (sIL-2R) and the sCD8 molecule; increased numbers and percentages of T cells bearing T cell activation markers, such as CD2+CD25+, CD3+CD25+, and HLA-DR+; increased stimulated production of IFNγ; higher neopterin and sTNFR-1 or sTNFR-2 levels; induction of indoleamine 2,3-dioxygenase (IDO) with lowered levels of plasma tryptophan and increased levels of tryptophan catabolites along the IDO pathway (TRYCATs); and glucocorticoid resistance in immune cells. Interferon-α (IFNα)-based immunotherapy shows that baseline and IFNα-induced activation of T cells, IDO activity and TRYCAT formation are related to the development of IFNα-induced depressive symptoms. Animal models of depression show that a cell-mediated immune response is related to the development of depression-like behavior. Antidepressants and mood stabilizers suppress different aspects of cell-mediated immunity and rather specifically target IFNγ production. This review shows that inflammation and cell-mediated immune activation are key factors in depression.

Risk factors for the development of depression in patients with hepatitis C taking interferon-α

Interferon-α, currently used for the treatment of hepatitis C, is associated with a substantially elevated risk of depression. However, not everyone who takes this drug becomes depressed, so it is important to understand what particular factors may make some individuals more 'at risk' of developing depression than others. Currently there is no consensus as to why interferon-induced depression occurs and the range of putative risk factors is wide and diverse. The identification of risk factors prior to treatment may allow identification of patients who will become depressed on interferon, allowing the possibility of improved treatment support and rates of treatment adherence. Here, we consolidate and review the literature on risk factors, and we discuss the potential confounds within the research examined in order to better isolate the risk factors that may be important in the development of depression in these patients and which might help predict patients likely to become depressed on treatment. We suggest that interactions between psychobehavioral, genetic, and biological risk factors are of particular importance in the occurrence of depression in patients with hepatitis C taking interferon-α.

Association between increased tryptophan degradation and depression in cancer patients

PURPOSE OF REVIEW

A high percentage of patients with malignant disease develops mood disorders or even depression. This review provides an overview, how immune activation and tryptophan degradation might contribute to the development of depression.

RECENT FINDINGS

Neurobiochemical changes caused by immune activation are supposed to be involved in the development of mood disorders, especially depression, in cancer patients. Within Th1-type immune response the enzyme indoleamine 2,3-dioxygenase (IDO) is induced, which degrades the essential amino acid tryptophan to form kynurenine derivatives. Enhanced immune-mediated tryptophan degradation is reflected by decreased plasma tryptophan levels and increased kynurenine concentrations in parallel with elevated concentrations of Th1-type immune activation marker neopterin. IDO activation has been demonstrated in patients with various kinds of cancer, and it has also been shown to predict a worse outcome of patients. Recent data also indicate strongly, that immune-mediated tryptophan degradation is crucially involved in the development of depression: IDO activation leads to the accumulation of neurotoxic metabolites, which are supposed to induce depressive-like behaviour. Furthermore immune-mediated tryptophan deprivation might also impair serotonin synthesis, as tryptophan is the precursor of this important neurotransmitter.

SUMMARY

Immune-mediated tryptophan degradation appears to be crucially involved in the development of depression.

Safety, Tolerability, and Immunogenicity of Interferons

Interferons (IFNs) are class II cytokines that are key components of the innate immune response to virus infection. Three IFN sub-families, type I, II, and III IFNs have been identified in man, Recombinant analogues of type I IFNs, in particular IFNα2 and IFNβ1, have found wide application for the treatment of chronic viral hepatitis and remitting relapsing multiple sclerosis respectively. Type II IFN, or IFN gamma, is used principally for the treatment of chronic granulomatous disease, while the recently discovered type III IFNs, also known as IFN lambda or IL-28/29, are currently being evaluated for the treatment of chronic viral hepatitis. IFNs are in general well tolerated and the most common adverse events observed with IFNα or IFNβ therapy are “flu-like” symptoms such as fever, headache, chills, and myalgia. Prolonged treatment is associated with more serious adverse events including leucopenia, thrombocytopenia, increased hepatic transaminases, and neuropsychiatric effects. Type I IFNs bind to high-affinity cell surface receptors, composed of two transmembrane polypeptides IFNAR1 and IFNAR2, resulting in activation of the Janus kinases Jak1 and Tyk2, phosphorylation and activation of the latent cytoplasmic signal transducers and activators of transcription (STAT1) and STAT2, formation of a transcription complex together with IRF9, and activation of a specific set of genes that encode the effector molecules responsible for mediating the biological activities of type I IFNs. Systemic administration of type I IFN results in activation of IFN receptors present on essentially all types of nucleated cells, including neurons and hematopoietic stem cells, in addition to target cells. This may well explain the wide spectrum of IFN associated toxicities. Recent reports suggest that certain polymorphisms in type I IFN signaling molecules are associated with IFN-induced neutropenia and thrombocytopenia in patients with chronic hepatitis C. IFNγ binds to a cell-surface receptor composed of two transmembrane polypeptides IFGR1 and IFGR2 resulting in activation of the Janus kinases Jak1 and Jak2, phosphorylation of STAT1, formation of STAT1 homodimers, and activation of a specific set of genes that encode the effector molecules responsible for mediating its biological activity. In common with type I IFNs, IFNγ receptors are ubiquitous and a number of the genes activated by IFNγ are also activated by type I IFNs that may well account for a spectrum of toxicities similar to that associated with type I IFNs including “flu-like” symptoms, neutropenia, thrombocytopenia, and increased hepatic transaminases. Although type III IFNs share the major components of the signal transduction pathway and activate a similar set of IFN-stimulated genes (ISGs) as type I IFNs, distribution of the IFNλ receptor is restricted to certain cell types suggesting that IFNλ therapy may be associated with a reduced spectrum of toxicities relative to type I or type II IFNs. Repeated administration of recombinant IFNs can cause in a break in immune tolerance to self-antigens in some patients resulting in the production of neutralizing antibodies (NABs) to the recombinant protein homologue. Appearance of NABs is associated with reduced pharmacokinetics, pharmacodynamics, and a reduced clinical response. The lack of cross-neutralization of IFNβ by anti-IFNα NABs and vice versa, undoubtedly accounts for the apparent lack of toxicity associated with the presence of anti-IFN NABs with the exception of relatively mild infusion/injection reactions.

Major depression during interferon-alpha treatment: vulnerability and prevention

Major Depressive Disorder (MDD) during interferons (IFN-α) treatment can occur within a few months of therapy, and shares many homologies with other forms of MDD, Most patients are resilient to the side effect ofinterferon-induced depression (IFN-MDD), but 15% to 40% are vulnerable. Several studies have employed antidepressants to prevent the incidence of an IFN-MDD episode, and the results suggest that prophylactic antidepressants may be specifically useful in those with pre-existing subthreshold depressive symptoms andlor a history of prior MDD episodes. Several other potential markers of vulnerability for IFN-MDD have been implicated in assessments of nondepressed patients before they start IFN-α These include poor sleep quality, premorbid elevations in inflammatory cytokines, genetic polymorphisms in the serotonin system, personality, and social support. The interplay of these factors strongly predicts who is at risk for IFN-MDD, and indicates several potentially modifiable targets for the personalized prevention of IFN-MDD,

A review of sleep disturbance in hepatitis C

Sleep disturbances occur in up to 60% of patients with chronic hepatitis C (CHC) and is often interrelated with comorbid psychiatric disorders. Moreover, neuropsychiatric complications of interferon-alpha during CHC treatment can manifest as sleep problems. Newly diagnosed sleep disturbance occurs in up to 60% and 30% of untreated CHC patients and patients undergoing interferon-alpha therapy, respectively. However, the presentation of insomnia in patients with CHC is influenced by significant psychiatric comorbidity, such as depression, and medical conditions, such as anemia and hypothyroidism. Therefore, prompt recognition using screening tools and exclusion of comorbid conditions contributing sleep pathology can enhance treatment outcomes. Owing to the paucity of studies, treatment recommendations for sleep disorders in CHC patients are derived from recommendations from general sleep disorder treatment guidelines. Further research is needed to elucidate the efficacy of pharmacological and nonpharmacological treatments of sleep disorders in CHC patients.

Functional polymorphisms in the interleukin-6 and serotonin transporter genes, and depression and fatigue induced by interferon-alpha and ribavirin treatment

Depression and fatigue are frequent side effects of interferon-alpha (IFN-alpha) treatment, and there is compelling evidence that the inflammatory response system (including interleukin-6, IL-6) and the serotonergic system is important in the pathophysiology of such symptoms. Functional polymorphisms in the promoter region of the IL-6 gene (rs1800795) and serotonin transporter gene (5-HTTLPR) have been identified as regulating these systems. The present study aimed to determine if these polymorphisms were associated with the development of depression and fatigue during IFN-alpha and ribavirin treatment. Ninety-eight Caucasian patients receiving pegylated IFN-alpha and ribavirin treatment for chronic hepatitis C virus at King's College Hospital, London, and Emory University Hospital, Atlanta, participated in this prospective cohort study. Symptoms of depression and fatigue were measured before treatment and at weeks 4, 8, 12 and 24 during treatment. The 'low IL-6' synthesizing genotype (CC) was associated with significantly fewer symptoms of depression (effect size = 0.7 at week 24; F = 9.4, d.f. = 436, P = 0.002). The 'high transcription' serotonin transporter (5-HTT) genotype (LL) was also associated with significantly fewer symptoms of depression, but with a much smaller effect (effect size = 0.2 at week 24; F = 4.5, d.f. = 436, P = 0.03). Neither polymorphisms were associated with symptoms of fatigue (IL-6: F = 1.2, d.f. = 430, P = 0.2; 5-HTT: F = 0.5, d.f. = 430, P = 0.5). The smaller effects of the 5-HTT polymorphism on depression may be explained by an interaction between the genes (F = 5.0, d.f. = 434, P = 0.02): the 'protective' effect of the 5-HTTLPR polymorphism was evident only in the presence of the 'low IL-6' genotype (F = 5.4, d.f. = 64, P = 0.02), not in the presence of the 'high IL-6' genotype (F = 2.2, d.f. = 369, P = 0.1). The association between the IL-6 polymorphism and reduced risk of depressive symptoms confirms the role of the inflammatory response system in the pathophysiology of IFN-alpha-induced depression; in contrast, the effect of the 5-HTT gene was small and perhaps dependent on the status of the inflammatory response.

Cytokine-induced depression during IFN-alpha treatment: the role of IL-6 and sleep quality

Depressive symptoms, poor sleep quality, and systemic markers of inflammation (e.g., interleukin (IL)-6) are frequently associated. Interferon-alpha (IFN-alpha) therapy results in Major Depressive Disorder (MDD) in some people, offering the possibility to elucidate the relationship of MDD to sleep and inflammation during treatment. In particular, delineating the temporal relations among these factors could help inform their causal relationships. To this end, a cohort of 95 non-depressed hepatitis C patients was followed prospectively for four consecutive months during IFN-alpha therapy. We found that higher pre-treatment levels of circulating IL-6 predicted incidence of MDD (X(2)(1)=7.7; p<0.05). Time-lagged mixed-effect analyses supported uni-directional associations in which IL-6 predicted next month's PSQI scores (F(47,11.6)=78.4; p<0.0005), and PSQI scores predicted next month's depressive Beck Depression Inventory-II (BDI) scores (F(16,22.6)=3.4; p<0.005). In addition, on any given month of treatment, IL-6 levels predicted BDI symptoms the following month (F(16,97.5)=7.3; p<0.0005), and conversely BDI predicted next month's IL-6 (F(14,7.4)=5.2; p<0.05) - providing evidence for a positive feedback relationship between depressive symptoms and systemic inflammation. These data provide further evidence that high levels of inflammation and poor sleep quality may be risk factors for IFN-alpha induced depression. Furthermore, these findings highlight the complex temporal relationships that exist among sleep, depression, and inflammation, and support the need for further prospective investigations to elucidate the dynamics that underlie depression during IFN-alpha treatment.

Managing depression during hepatitis C treatment

OBJECTIVE

The prevalence of hepatitis C virus (HCV) infection in Canada is estimated to be 1% and expected to increase during the next decade. Mental illness, particularly depression, is common among HCV-infected patients and remains an obstacle to interferon-alpha (IFN-alpha) treatment. We summarize the risk factors for interferon-alpha-induced major depressive disorder (IFN-alpha-MDD) in HCV patients and the evidence for antidepressant prophylaxis and symptomatic antidepressant treatment of depression.

METHODS

We searched MEDLINE, EMBASE, and CINAHL for randomized controlled or quasi-experimental trials evaluating antidepressant prophylactic and symptomatic treatment approaches for depression emerging during IFN-alpha treatment. Manual searches of references listed in review articles, case series, and anecdotal reports supplemented our literature search.

RESULTS

A total of 9 trials involving prophylactic and symptomatic treatment approaches for IFN-alpha-MDD are summarized in our review. Antidepressant pretreatment is beneficial for patients with elevated baseline depressive symptoms and a preexisting history of IFN-alpha-MDD. Although limited evidence exists for several antidepressant agents, much of the evidence suggests that selective serotonin reuptake inhibitors (SSRIs) are safe and efficacious in treating depressive symptoms secondary to IFN-alpha therapy.

CONCLUSION

Both antidepressant pretreatment and symptomatic treatment are viable strategies for treating IFN-alpha-MDD. Improved treatment outcomes and early identification of depression during HCV treatment can be achieved using an integrated medical and mental health treatment approach.

Psychiatric problems in patients infected with hepatitis C before and during antiviral treatment with interferon-alpha: a review

OBJECTIVE

Neuropsychiatric symptoms are common in patients with chronic hepatitis C (CHC) and can potentially be exacerbated by interferon-alpha treatment. Such symptoms can contribute to problems with treatment adherence, which can significantly compromise epidemiological virus control. This review summarizes current knowledge about the etiology, course, and management of neuropsychiatric symptoms in patients with CHC.

METHOD

Studies were identified using computerized searches, with further references obtained from the bibliographies of the reviewed articles.

RESULTS

Psychopathological syndromes that occur during interferon-alpha treatment frequently have atypical features that may complicate their recognition using standard diagnostic criteria. In addition, prospective studies in this area often exclude patients with psychiatric disorders and have methodological disparities that make it difficult to develop guidelines for management of psychiatric side effects induced by interferon-alpha. Despite the high prevalence of chronic hepatitis C virus (HCV) infection in patients with psychiatric and substance use disorders, neuropsychiatric concerns often lead to the exclusion of such patients from interferon-alpha treatment, inappropriately depriving them of the potential benefits of this therapy.

CONCLUSION

Consultation-liaison psychiatrists should become familiar with the clinical spectrum of presentations associated with HCV infection as well as with related neuropsychiatric symptoms in order to promote the creation of multidisciplinary teams who specialize in the care of patients with HCV infections. More studies are needed to define neuropsychiatric syndromes that can be induced by interferon-alpha and to clarify best assessment and treatment procedures for these syndromes. It is also important to create and evaluate psychoeducational programs for all patients with chronic HCV infections, even those with low risk of complications, in order to promote adherence to therapy and optimize patients' quality of life.

Depressive symptomatology is associated with decreased interleukin-1 beta and increased interleukin-1 receptor antagonist levels in males

Previous studies with selected patient populations have suggested that cytokines, the immune system messengers, may play a role in the aetiology of depression. However, the data concerning the increase or decrease of the plasma cytokine levels in depression is controversial and the effects of the medications and type of depression are largely unknown. We studied the connections between plasma interleukin-1 beta (IL-1 beta) and interleukin 1 receptor antagonist (IL-1RA) levels, and depressive symptomatology measured with the Beck Depression. Inventory in a large, middle-aged population-based sample collected from Central Finland. In addition, the effects of various medications and type of depressive symptomatology on the cytokine levels were scrutinized. In the whole study population, IL-1RA levels were higher in the subgroup with depressive symptomatology. In the males with depressive symptomatology, higher IL-1RA levels and lower interleukin-1 beta levels were observed as compared with the non-depressed males. The IL-1RA/IL-1 beta ratio was significantly higher in males with depressive symptomatology. The IL-1RA levels were also higher and IL-1 beta levels lower in the depressed females, but the trend was not significant. The elevated IL-1RA-levels and IL-1RA/IL-1 beta ratio suggest a role for cytokines in the pathogenesis of depression. The higher IL-1RA levels may reflect an endogenous repairing process against depression.

Neuropsychiatric disorders related to interferon and interleukins treatment

Certain cytokines such as interferon-alpha and interleukin-2 are often used in the treatment certain cancers and chronic diseases such as melanoma, hepatitis C infection and multiple sclerosis. Several neuropsychiatric side effects such as depression, anxiety, psychosis, suicidal ideation, hypomanic mood and cognitive impairment were reported in those patients who received those medications. In certain patients with those neuropsychiatric side effects, the symptoms ceased when the medication was stopped. However, in some cases, the cognitive impairment persisted even for years after cessation of the medication. In animal studies, those cytokines could induce sickness behaviour, anxiety behaviour and social anhedonia. The increased in pro-inflammatory cytokines in certain neuropsychiatric disorders was widely reported. In addition, in animal studies, the treatment with interferon-alpha or interleukin-1 could induce depressive like behaviour. Recently, the role of certain pro-inflammatory cytokines that could enhance the activity of the enzyme, indoleamine 2-3, dioxygenase (IDO) which in turn would increase tryptophan degradation into kynurenine and decrease tryptophan availability of tryptophan in the brain to synthesize serotonin, a neurotransmitter which is necessary for the normal mood state became of interest in pathophysiology of psychiatric disorders. Furthermore, the imbalance in the further downward catabolic kynurenine pathway and their interactions with other neurotransmitters has been proposed to play an important role. The presence of such an imbalance in patients being treated with cytokines and in patients with psychiatric disorders and the possible consequence of those changes on the neuroprotective function in the brain are discussed in this review.

Activation of central nervous system inflammatory pathways by interferon-alpha: relationship to monoamines and depression

BACKGROUND

Interferon (IFN)-alpha has been used to study the effects of innate immune cytokines on the brain and behavior in humans. The degree to which peripheral administration of IFN-alpha accesses the brain and is associated with a central nervous system (CNS) inflammatory response is unknown. Moreover, the relationship among IFN-alpha-associated CNS inflammatory responses, neurotransmitter metabolism, and behavior has yet to be established.

METHODS

Twenty-four patients with hepatitis C underwent lumbar puncture and blood sampling after approximately 12 weeks of either no treatment (n = 12) or treatment with pegylated IFN-alpha 2b (n = 12). Cerebrospinal fluid (CSF) and blood samples were analyzed for proinflammatory cytokines and their receptors as well as the chemokine, monocyte chemoattractant protein-1 (MCP-1), and IFN-alpha. Cerebrospinal fluid samples were additionally analyzed for monoamine metabolites and corticotropin releasing hormone. Depressive symptoms were assessed using the Montgomery Asberg Depression Rating Scale.

RESULTS

Interferon-alpha was detected in the CSF of all IFN-alpha-treated patients and only one control subject. Despite no increases in plasma IL-6, IFN-alpha-treated patients exhibited significant elevations in CSF IL-6 and MCP-1, both of which were highly correlated with CSF IFN-alpha concentrations. Of the immunologic and neurotransmitter variables, log-transformed CSF concentrations of the serotonin metabolite, 5-hydroxyindoleacetic acid (5-HIAA), were the strongest predictor of depressive symptoms. Log-transformed CSF concentrations of IL-6, but not IFN-alpha or MCP-1, were negatively correlated with log-transformed CSF 5-HIAA (r(2) = -.25, p < .05).

CONCLUSIONS

These data indicate that a peripherally administered cytokine can activate a CNS inflammatory response in humans that interacts with monoamine (serotonin) metabolism, which is associated with depression.

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.

Depressive symptoms in patients with chronic hepatitis C are correlated with elevated plasma levels of interleukin-1beta and tumor necrosis factor-alpha

Studies suggest that cytokines have a role in the biology of depression. In this study, we evaluated depression and cytokine levels in patients with and without chronic hepatitis C (HCV) to better assess how chronic infection alters cytokines levels and may contribute to depressive symptomotology. Twenty-three adults with (n=16) and without (n=7) HCV were recruited through the Portland VA Medical Center. Research participants were excluded for current substance abuse, psychotic disorder, liver cirrhosis, or interferon (IFN) therapy. Participants completed the Beck Depression Inventory-II (BDI-II) and a blood draw to evaluate plasma cytokine levels [i.e., interleukin (IL)-1beta, IL-10 and tumor necrosis factor (TNF)-alpha]. t-Tests were performed to compare cytokine levels in patients with or without HCV. HCV patients showed higher TNF-alpha values compared to patients without HCV (group means=7.94 vs. 3.41pg/mL, respectively, p=0.047). There were no significant differences between the groups for the other cytokines assessed. In patients with HCV, TNF-alpha and IL-1beta levels (but not IL-10) were correlated with BDI-II scores [r=0.594, p=0.020 and r=0.489, p=0.055 (trend), respectively]. Taken together, these results show an association between severity of depressive symptoms and expression of pro-inflammatory cytokines in patients with HCV. Future studies should investigate how inflammatory mediators play a role in the expression of specific depressive symptoms in patients with chronic infection. Patients with HCV represent an interesting model to examine this relationship.

Neuropsychiatric manifestations of depression in multiple sclerosis: neuroinflammatory, neuroendocrine, and neurotrophic mechanisms in the pathogenesis of immune-mediated depression

Evidence suggests that depression in multiple sclerosis (MS) is largely biologically mediated by some of the same processes involved in the immunopathogenesis of this neurologic disease. In particular, the increase in proinflammatory cytokines, activation of the hypothalamic-pituitary-adrenal (HPA) axis, and reduction in neurotrophic factors that occur in MS may each account for the increased rate of depression seen in MS. The possible contributions of these neuroinflammatory, neuroendocrine, and neurotrophic mechanisms suggest a diverse array of novel treatment strategies for depression, both in the context of inflammatory conditions as well as in idiopathic depression. Furthermore, if such processes in MS play a causative role in the pathogenesis of depression, and depression in turn has affects on neurophysiological processes related to immune function, then treatment of depression might have a positive effect on MS disease progression. This makes treating MS depression a neuropsychiatric imperative.

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.

The neuropoietic cytokine family in development, plasticity, disease and injury

Neuropoietic cytokines are well known for their role in the control of neuronal, glial and immune responses to injury or disease. Since this discovery, it has emerged that several of these proteins are also involved in nervous system development, in particular in the regulation of neurogenesis and stem cell fate. Recent data indicate that these proteins have yet more functions, as key modulators of synaptic plasticity and of various behaviours. In addition, neuropoietic cytokines might be a factor in the aetiology of psychiatric disorders.