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

Potential Effect of DPP-4 Inhibitors Towards Hepatic Diseases and Associated Glucose Intolerance

Dipeptidyl-peptidase-4 (DPP-4) is an enzyme having various properties and physiological roles in lipid accumulation, resistance to anticancer agents, and immune stimulation. DPP-4 includes membrane-bound peptidases and is a kind of enzyme that cleaves alanine or proline-containing peptides such as incretins, chemokines, and appetite-suppressing hormones (neuropeptide) at their N-terminal dipeptides. DPP-4 plays a role in the final breakdown of peptides produced by other endo and exo-peptidases from nutritious proteins and their absorption in these tissues. DPP-4 enzyme activity has different modes of action on glucose metabolism, hunger regulation, gastrointestinal motility, immune system function, inflammation, and pain regulation. According to the literature survey, as DPP-4 levels increase in individuals with liver conditions, up-regulation of hepatic DPP-4 expression is likely to be the cause of glucose intolerance or insulin resistance. This review majorly focuses on the cleavage of alanine or proline-containing peptides such as incretins by the DPP-4 and its resulting conditions like glucose intolerance and cause of DPP-4 level elevation due to some liver conditions. Thus, we have discussed the various effects of DPP-4 on the liver diseases like hepatitis C, non-alcoholic fatty liver, hepatic regeneration and stem cell, hepatocellular carcinoma, and the impact of elevated DPP-4 levels in association with liver diseases as a cause of glucose intolerance and their treatment drug of choices. In addition, the effect of DPP-4 inhibitors on obesity and their negative aspects are also discussed in brief.

Changes in Gene Expression Profiles in Adult Rat Brain Structures after Neonatal Action of Dipeptidyl Peptidase-IV Inhibitors

BACKGROUND

Previous studies have shown the development of emotional and motivational disorders, such as anxiety-depression-like disorders with increased aggression in adolescent and adult Wistar rats, occurs after neonatal exposure to the dipeptidyl peptidase-IV (DPP-IV, EC 3.4.14.5) inhibitors diprotin A and sitagliptin (postnatal days 5-18).

METHODS

In this study, using real-time PCR, we evaluated changes in the gene expression of serine protease DPP-IV and prolyl endopeptidase (PREP, EC 3.4.21.26; dpp4 and prep genes), monoamine oxidase А (maoA) and B (maoB), and serotonin transporter (SERT; sert) in the brain structures from 3-month-old rats after postnatal action of DPP-IV inhibitors diprotin A and sitagliptin.

RESULTS

Dpp4, sert, and maoB gene expression increased and maoA gene expression changed with a tendency to increase in the striatum of rats with neonatal sitagliptin action. The increase of maoA gene expression was also shown in the amygdala. An increase in prep gene expression was found in the striatum of rats with the neonatal action of diprotin A, and a decrease in maoB gene expression was observed in the amygdala. We detected a significant downward trend in sert gene expression in the frontal cortex and amygdala, as well as a tendency to increase in maoA gene expression in the hypothalamus.

DISCUSSION

These findings suggest that changes in the expression of the abovementioned genes are associated with the development of anxiety and depression, with increased aggression caused by the neonatal action of diprotin A and sitagliptin.

Minocycline attenuates interferon-α-induced impairments in rat fear extinction

Background

Extinction of conditioned fear is an important brain function for animals to adapt to a new environment. Accumulating evidence suggests that innate immune cytokines are involved in the pathology of psychotic disorders. However, the involvement of cytokines in fear dysregulation remains less investigated. In the present study, we investigated how interferon (IFN)-α disrupts the extinction of conditioned fear and propose an approach to rescue IFN-α-induced neurologic impairment.

Methods

We used a rat model of auditory fear conditioning to study the effect of IFN-α on the fear memory process. IFN-α was infused directly into the amygdala of rats and examined the rats’ behavioral response (freezing) to fear-conditioned stimuli. Immunohistochemical staining was used to examine the glia activity status of glia in the amygdala. The levels of the proinflammatory cytokines interleukin (IL)-1β and tumor necrosis factor (TNF)-α in the amygdala were measured by enzyme-linked immunosorbent assay. We also administrated minocycline, a microglial activation inhibitor, before the IFN-α infusion to testify the possibility to reverse the IFN-α-induced effects.

Results

Infusing the amygdala with IFN-α impaired the extinction of conditioned fear in rats and activated microglia and astrocytes in the amygdala. Administering minocycline prevented IFN-α from impairing fear extinction. The immunohistochemical and biochemical results show that minocycline inhibited IFN-α-induced microglial activation and reduced IL-1β and TNF-α production.

Conclusions

Our findings suggest that IFN-α disrupts the extinction of auditory fear by activating glia in the amygdala and provides direction for clinical studies of novel treatments to modulate the innate immune system in patients with psychotic disorders.

Mindfulness-based stress reduction to enhance psychological functioning and improve inflammatory biomarkers in trauma-exposed women: A pilot study

This study examined the effects of a mindfulness-based stress reduction (MBSR) program on psychological functioning and inflammatory biomarkers in women with histories of interpersonal trauma. The 8-week MBSR program was conducted at a community-based health center and participants (N = 50) completed several measures of psychological functioning at study entry as well as 4 weeks, 8 weeks, and 12 weeks later. Inflammatory biomarkers were assayed from blood collected at each assessment. A series of linear mixed-model analyses were conducted to measure the effect of attendance and time on the dependent variables. Time was associated with significant decreases in perceived stress, depression, trait and state anxiety, emotion dysregulation, and posttraumatic stress symptoms, as well as increases in mindfulness. Session attendance was associated with significant decreases in interleukin (IL)-6 levels. This pilot study demonstrated the potential beneficial effects of MBSR on psychological functioning and the inflammatory biomarker IL-6 among trauma-exposed and primarily low-income women. Decreases in inflammation have implications for this population, as interpersonal trauma can instigate chronic physiological dysregulation, heightened morbidity, and premature death. This study's preliminary results support efforts to investigate biological remediation with behavioral interventions in vulnerable populations.

Identification of altered dipeptidyl-peptidase activities as potential biomarkers for unipolar depression

BACKGROUND

Changes in circulatory aminopeptidases [dipeptidyl-peptidase-IV (DPP-IV), Prolyl-oligopeptidase (POP) and Leucine aminopeptidase (LAP)] activities have been found to be associated with psychiatric illnesses and inflammatory diseases.

METHODS

The discriminatory indices of aminopeptidases activities were assessed by enzymatic assays in plasma samples from 240 unipolar depression (UD) patients and 264 matched controls. In addition the relationship between soluble and cellular DPP-IV activity was determined in plasma and blood cells from healthy subjects.

RESULTS

Greater than 95% of the plasma DPP-IV activity could be blocked by inhibitors, demonstrating the specificity of the assay. Also, DPP-IV protein and activity levels were strongly correlated. In contrast, only 50% of the membrane-bound activity in blood cells was inhibited, which suggested that other similar peptidases may be present in these cells. UD patients had decreased plasma levels of DPP-IV and POP activities compared to healthy controls with a concomitant increase in LAP activity. Finally, testing of the LAP/DPP-IV ratio resulted in good discrimination of UD patients from controls with an area under the curve-receiver operating characteristic of 0.70.

LIMITATIONS

Further biological validation studies using different cohorts are warranted.

CONCLUSIONS

The finding that plasma DPP-IV activity was decreased and LAP activity was increased in UD patients suggests the potential value for testing the levels of these enzymes for improved classification of patients. In addition, the changes in these enzymes, suggests that the proteolytic maturation of their proneuropeptide and prohormone subtrates may also be affected in UD, resulting in altered production of the associated bioactive peptides.

Effect of prolyl endopeptidase inhibitor benzyloxycarbonyl-methionyl-2(S)-cyanopyrrolidine on the course of experimental depressive syndrome in rats

The effects of noncompetitive prolyl endopeptidase inhibitor benzyloxycarbonyl-methionyl-2(S)-cyanopyrrolidine were studied in rats with the experimental dopamine deficiency-dependent depressive syndrome induced by systemic injections of a pre-neurotoxin 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridin for 14 days. The inhibitor (3.0 mg/kg, i.p., 30 min before pre-neurotoxin injection on days 8-14) alleviated depression symptoms and promoted normalization of behavioral activity after drug withdrawal. The obtained data reflected therapeutic antidepressant properties of inhibitor for prolyl endopeptidase benzyloxycarbonyl-methionyl-2(S)-cyanopyrrolidine.

Dipeptidyl peptidase-4: A key player in chronic liver disease

Dipeptidyl peptidase-4 (DPP-4) is a membrane-associated peptidase, also known as CD26. DPP-4 has widespread organ distribution throughout the body and exerts pleiotropic effects via its peptidase activity. A representative target peptide is glucagon-like peptide-1, and inactivation of glucagon-like peptide-1 results in the development of glucose intolerance/diabetes mellitus and hepatic steatosis. In addition to its peptidase activity, DPP-4 is known to be associated with immune stimulation, binding to and degradation of extracellular matrix, resistance to anti-cancer agents, and lipid accumulation. The liver expresses DPP-4 to a high degree, and recent accumulating data suggest that DPP-4 is involved in the development of various chronic liver diseases such as hepatitis C virus infection, non-alcoholic fatty liver disease, and hepatocellular carcinoma. Furthermore, DPP-4 occurs in hepatic stem cells and plays a crucial role in hepatic regeneration. In this review, we described the tissue distribution and various biological effects of DPP-4. Then, we discussed the impact of DPP-4 in chronic liver disease and the possible therapeutic effects of a DPP-4 inhibitor.

Mechanistic explanations how cell-mediated immune activation, inflammation and oxidative and nitrosative stress pathways and their sequels and concomitants play a role in the pathophysiology of unipolar depression

This paper reviews that cell-mediated-immune (CMI) activation and inflammation contribute to depressive symptoms, including anhedonia; anxiety-like behaviors; fatigue and somatic symptoms, e.g. illness behavior or malaise; and mild cognitive impairment (MCI). These effects are in part mediated by increased levels of pro-inflammatory cytokines (PICs), e.g. interleukin-1 (IL-1), IL-6 and tumor necrosis factor (TNF)α, and Th-1-derived cytokines, such as IL-2 and interferon (IFN)γ. Moreover, new pathways, i.e. concomitants and sequels of CMI activation and inflammation, were detected in depression: (1) Induction of indoleamine 2,3-dioxygenase (IDO) by IFNγ and some PICs is associated with depleted plasma tryptophan, which may interfere with brain 5-HT synthesis, and increased production of anxiogenic and depressogenic tryptophan catabolites. (2) Increased bacterial translocation may cause depression-like behaviors by activating the cytokine network, oxidative and nitrosative stress (O&NS) pathways and IDO. (3) Induction of O&NS causes damage to membrane ω3 PUFAs, functional proteins, DNA and mitochondria, and autoimmune responses directed against intracellular molecules that may cause dysfunctions in intracellular signaling. (4) Decreased levels of ω3 PUFAs and antioxidants, such as coenzyme Q10, glutathione peroxidase or zinc, are associated with an increased inflammatory potential; more oxidative damage; the onset of specific symptoms; and changes in the expression or functions of brain 5-HT and N-methyl-d-aspartate receptors. (5) All abovementioned factors cause neuroprogression, that is a combination of neurodegeneration, neuronal apoptosis, and lowered neurogenesis and neuroplasticity. It is concluded that depression may be the consequence of a complex interplay between CMI activation and inflammation and their sequels/concomitants which all together cause neuroprogression that further shapes the depression phenotype. Future research should employ high throughput technologies to collect genetic and gene expression and protein data from patients with depression and analyze these data by means of systems biology methods to define the dynamic interactions between the different cell signaling networks and O&NS pathways that cause depression.

Effect of a prolyl endopeptidase inhibitor benzyloxycarbonyl-alanyl-proline on the development of experimental depressive syndrome in rats

The effects of a competitive prolyl endopeptidase inhibitor benzyloxycarbonyl-alanyl-proline were studied in rats with experimental dopamine deficiency-dependent depressive syndrome due to systemic administration of a proneurotoxin 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine for 14 days. The inhibitor was injected intraperitoneally 30 min before treatment with 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (2nd week of the study). This substance contributed to rapid disappearance of depressive symptoms during the recovery of behavioral activity. Our results indicate that benzyloxycarbonyl-alanyl-proline has the antidepressant properties.

Plasma activity of prolyl endopeptidase in relation to psychopathology during immunotherapy with IFN-alpha in patients with renal cell carcinoma

Abnormal activity in peripheral blood of the cytosolic enzyme prolyl endopeptidase (PEP, EC 3.4.21.26, post prolyl cleaving enzyme, prolyl oligopeptidase) has been found in patients with a variety of psychiatric disorders, most consistently in mood disorders. Mood disturbance is a well-known side effect of immunotherapy with interferon-alpha (IFN-alpha). Earlier, we documented a decrease in serum PEP activity in the first 4 weeks of treatment with IFN-alpha. In 24 patients (16 men, 8 women, median age 60.5 years, range 47-72 years) with metastatic renal cell carcinoma (RCC), psychiatric assessment and blood sampling were performed before and at 4 and 8 weeks and at 6 months after initiation of treatment with IFN-alpha. No episodes of depression were observed, and the sum score and the scores on the subscales for depression and hostility of the Symptom Check List-90 (SCL-90) did not change during follow-up, whereas the anxiety scores were somewhat lower at 4 and 8 weeks compared with baseline. No change in plasma PEP activity and no relationships between change in psychiatric parameters and change in plasma PEP activity were found. As more subtle relationships between PEP activity and psychiatric status could have easily been obscured, a role for PEP in the pathophysiology of IFN-alpha-induced mood disturbance can neither be confirmed nor excluded.

Changes in mood states and biomarkers during peginterferon and ribavirin treatment of chronic hepatitis C

OBJECTIVE

Depression is a frequent side effect of interferon therapy in patients with chronic hepatitis C (CHC). The aim of this study was to identify baseline and on-treatment predictors of depression in CHC patients receiving peginterferon and ribavirin.

METHODS

In total, 201 prior nonresponders with advanced fibrosis were treated with peginterferon alfa-2a and ribavirin for 24 wk in the Hepatitis C Antiviral Long-term Treatment against Cirrhosis trial. Of these, 74 continued on antiviral therapy through week 48. Mood states were assessed with the Beck Depression Inventory II and the Composite International Diagnostic Interview. Plasma cortisol and whole blood serotonin levels were measured in 101 subjects at weeks 0, 4, 24, 48, and 72.

RESULTS

The incidence of interferon-induced depression was 23% and 42% at weeks 24 and 48, respectively. Although 22% of patients had baseline depression, the absence of a week 20 virological response was the only independent predictor of interferon-induced depression at week 24 (P = 0.0009). Plasma cortisol levels did not change during treatment nor correlate with depression. In contrast, whole blood serotonin/platelet levels significantly decreased during treatment, but did not correlate with interferon-induced depression through week 24 (P = 0.35), nor through week 48 (P = 0.51).

CONCLUSION

Depression during peginterferon and ribavirin therapy was associated with a lower antiviral response. The significant reduction in whole blood serotonin levels over time suggest that further studies of the serotonergic pathway are warranted to identify the mediators of interferon-induced depression.

Circulating levels of soluble CD26 are associated with phobic anxiety in women

Dipeptidyl peptidase IV (DPPIV or CD26) is an ubiquitously expressed protease that could play a role in the pathogenesis of anxiety in view of its capacity to cleave several behaviourally active neuropeptides. Hereto we sought to determine the relationship between phobic anxiety, as measured by the Crown-Crisp index, and circulating levels of soluble CD26 (sCD26) in a large cohort of 1017 Italian women participating in a general health survey. The association between sCD26 levels and phobic anxiety was tested using simple correlation analysis, linear regression and multivariate logistic regression analysis. A highly significant inverse association was found between sCD26 concentrations and anxiety scores both in simple correlation and linear regression analysis. Compared with subjects in the first tertile of sCD26 levels, the age-adjusted odds ratio for scoring >/=6 compared to scoring 0 or 1 was 0.31 (95% CI: 0.18-0.74) for the second and 0.47 (95% CI: 0.34-0.63) for the third tertile. Altogether, our data suggest that reduced plasma sCD26 concentrations could be a marker of high levels of phobic anxiety in women.

Interferon-induced depression in chronic hepatitis C: a review of its prevalence, risk factors, biology, and treatment approaches

Hepatitis C viral infection is a global health problem that affects approximately 4 million people in the United States. Combination treatment with pegylated interferon (IFN)-alpha plus ribavirin has been shown to be most effective in treating patients with chronic hepatitis C (CHC). Despite its efficacy, one of the most common side effects of this regimen is depression. Whereas IFN-alpha has been found to induce depression in chronic myelogenous leukemia, melanoma, and renal cell carcinoma, CHC patients may be especially prone to develop IFN-induced depression. This review includes a summary of differences between IFN-alpha and IFN-beta and addresses whether pegylation of IFN (versus nonpegylated IFN) gives rise to a treatment with reduced potential to induce depressive symptoms. Consideration is also given to evidence showing that treatment with ribavirin may contribute to IFN-induced depression. Thyroid disorders and anemia (as well as other medical conditions) have also been associated with IFN exposure and may account for some incidences of depression in CHC patients. Evidence is reviewed indicating that prior psychiatric and mood disorders (especially previous episodes of major depressive disorder), just prior to IFN treatment, contribute to the propensity to develop depression during treatment. In addition, a brief description is provided of potential biological mechanisms of IFN-induced depression (ie, monoamines, hypothalamic-pituitary-adrenocortical [HPA] axis, proinflammatory cytokines, peptidases, intercellular adhesion molecule-1, and nitric oxide). Finally, a discussion is provided on the use of antidepressants as a preventative versus restorative treatment, including a commentary on risks of using antidepressants in this patient population.

The pathogenesis of clinical depression: stressor- and cytokine-induced alterations of neuroplasticity

Stressful events promote neurochemical changes that may be involved in the provocation of depressive disorder. In addition to neuroendocrine substrates (e.g. corticotropin releasing hormone, and corticoids) and central neurotransmitters (serotonin and GABA), alterations of neuronal plasticity or even neuronal survival may play a role in depression. Indeed, depression and chronic stressor exposure typically reduce levels of growth factors, including brain-derived neurotrophic factor and anti-apoptotic factors (e.g. bcl-2), as well as impair processes of neuronal branching and neurogenesis. Although such effects may result from elevated corticoids, they may also stem from activation of the inflammatory immune system, particularly the immune signaling cytokines. In fact, several proinflammatory cytokines, such as interleukin-1, tumor necrosis factor-alpha and interferon-gamma, influence neuronal functioning through processes involving apoptosis, excitotoxicity, oxidative stress and metabolic derangement. Support for the involvement of cytokines in depression comes from studies showing their elevation in severe depressive illness and following stressor exposure, and that cytokine immunotherapy (e.g. interferon-alpha) elicited depressive symptoms that were amenable to antidepressant treatment. It is suggested that stressors and cytokines share a common ability to impair neuronal plasticity and at the same time altering neurotransmission, ultimately contributing to depression. Thus, depressive illness may be considered a disorder of neuroplasticity as well as one of neurochemical imbalances, and cytokines may act as mediators of both aspects of this illness.

A cognitive therapy conceptualization of panic disorder exacerbated by interferon treatment

This case conference presents a patient with von Willebrand disease, receiving year-long interferon treatment for hepatitis C. She was referred to C-L Psychiatry following a severe exacerbation of panic disorder. Our guest interviewer is Dr. Craig White, a Scottish cognitive therapist. The subsequent discussion outlines the treatment challenges of panic disorder that occurs when a patient is receiving interferon. A literature review evaluates psychological effects of interferon and biological mechanisms by which interferon may exacerbate anxiety and depression. A cognitive therapy conceptualization of interferon-induced exacerbation of panic disorder is proposed.

Prevention of interferon-alpha associated depression in psychiatric risk patients with chronic hepatitis C

BACKGROUND/AIMS

Interferon-alpha (IFN-alpha) induced depression is a major limitation for the treatment of chronic hepatitis C, especially for patients with psychiatric disorders. We prospectively studied the efficacy of a pre-emptive treatment with the antidepressant citalopram to prevent depression during hepatitis C treatment with pegylated IFN-alpha-2b plus ribavirin.

METHODS

14 HCV infected patients with psychiatric disorders received a prophylactic medication with citalopram (20mg/day) before and during therapy with IFN-alpha. The incidence of major depression was compared with 22 HCV infected patients with psychiatric disorders (group B; n=11) and without psychiatric risk factors (group C; n=11), who underwent IFN-alpha treatment without a pre-emptive antidepressant therapy. Depression was diagnosed by DSM-IV criteria.

RESULTS

Pre-treatment of psychiatric patients with citalopram significantly reduced the incidence of major depression during the first 6 months of antiviral treatment as compared to the two control groups (group A 14% vs. 64% and 55% in group B and C; log-rank 6.89; df=2; P=0.032). Patients who developed symptoms of major depression during IFN therapy could also be improved by antidepressive treatment.

CONCLUSIONS

Our open label pilot study, though small, clearly indicates that IFN alpha induced depression in psychiatric risk patients can be ameliorated by both the use of antidepressants as well as by intensive psychiatric care. However, larger, double blind placebo controlled trials in other patient populations are required to confirm these preliminary findings.