Involvement of the IL-6 Signaling Pathway in the Anti-Anhedonic Effect of the Antidepressant Agomelatine in the Chronic Mild Stress Model of Depression.

Neuroinflammation has emerged as an important factor in the molecular underpinnings of major depressive disorder (MDD) pathophysiology and in the mechanism of action of antidepressants. Among the inflammatory mediators dysregulated in depressed patients, interleukin (IL)-6 has recently been proposed to play a crucial role. IL-6 activates a signaling pathway comprising the JAK/STAT proteins and characterized by a specific negative feedback loop exerted by the cytoplasmic protein suppressor of cytokine signalling-3 (SOCS3). On these bases, here, we explored the potential involvement of IL-6 signaling in the ability of the antidepressant drug agomelatine to normalize the anhedonic-like phenotype induced in the rat by chronic stress exposure. To this aim, adult male Wistar rats were subjected to the chronic mild stress (CMS) paradigm and chronically treated with vehicle or agomelatine. The behavioral evaluation was assessed by the sucrose consumption test, whereas molecular analyses were performed in the prefrontal cortex. We found that CMS was able to stimulate IL-6 production and signaling, including SOCS3 gene and protein expression, but the SOCS3-mediated feedback-loop inhibition failed to suppress the IL-6 cascade in stressed animals. Conversely, agomelatine treatment normalized the stress-induced decrease in sucrose consumption and restored the negative modulation of the IL-6 signaling via SOCS3 expression and activity. Our results provide additional information about the pleiotropic mechanisms that contribute to agomelatine's therapeutic effects.

Oncogene-induced maladaptive activation of trained immunity in the pathogenesis and treatment of Erdheim-Chester disease.

Trained immunity (TI) is a proinflammatory program induced in monocyte/macrophages upon sensing of specific pathogens and is characterized by immunometabolic and epigenetic changes that enhance cytokine production. Maladaptive activation of TI (ie, in the absence of infection) may result in detrimental inflammation and development of disease; however, the exact role and extent of inappropriate activation of TI in the pathogenesis of human diseases is undetermined. In this study, we uncovered the oncogene-induced, maladaptive induction of TI in the pathogenesis of a human inflammatory myeloid neoplasm (Erdheim-Chester disease, [ECD]), characterized by the BRAFV600E oncogenic mutation in monocyte/macrophages and excess cytokine production. Mechanistically, myeloid cells expressing BRAFV600E exhibit all molecular features of TI: activation of the AKT/mammalian target of rapamycin signaling axis; increased glycolysis, glutaminolysis, and cholesterol synthesis; epigenetic changes on promoters of genes encoding cytokines; and enhanced cytokine production leading to hyperinflammatory responses. In patients with ECD, effective therapeutic strategies combat this maladaptive TI phenotype; in addition, pharmacologic inhibition of immunometabolic changes underlying TI (ie, glycolysis) effectively dampens cytokine production by myeloid cells. This study revealed the deleterious potential of inappropriate activation of TI in the pathogenesis of human inflammatory myeloid neoplasms and the opportunity for inhibition of TI in conditions characterized by maladaptive myeloid-driven inflammation.

Prokineticin 2 promotes and sustains neuroinflammation in vincristine treated mice: Focus on pain and emotional like behavior.

Vincristine (VCR) treatment is often associated to painful neuropathy. Its development is independent from antitumoral mechanism and involves neuroinflammation. We investigated the role of the chemokine prokineticin (PK)2 in a mouse model of VCR induced neuropathy using a PK-receptors (PK-R) antagonist to counteract its development. We also evaluated emotional like deficits in VCR mice. VCR (0,1 mg/kg) was i.p. injected in C57BL/6J male mice once a day for 14 consecutive days. Pain, anxiety and depressive like behaviors were assessed in animals. PK2, PK-Rs, cytokines, neuroinflammatory markers (CD68, CD11b, GFAP, TLR4) and ATF3 were evaluated in DRG, spinal cord, prefrontal cortex and hippocampus. The PK-Rs antagonist PC1, was s.c. injected (150 µg/kg) twice a day from day 7 (hypersensitivity state) until day 14. Its effect on pain and neuroinflammation was evaluated. VCR mice developed neuropathic pain but not mood alterations. After 7 days of VCR treatment we observed a neuroinflammatory condition in DRG with high levels of PK-Rs, TLR4, CD68, ATF3 and IL-1ß without relevant alterations in spinal cord. At day 14, an upregulation of PK system and a marked neuroinflammation was evident also in spinal cord. Moreover, at the same time, we observed initial alterations in supraspinal brain areas. PC1 treatment significantly counteracted neuropathic pain and blunted neuroinflammation.

Chronic Stress Exposure Reduces Parvalbumin Expression in the Rat Hippocampus through an Imbalance of Redox Mechanisms: Restorative Effect of the Antipsychotic Lurasidone.

Background: Psychiatric disorders are associated with altered function of inhibitory neurotransmission within the limbic system, which may be due to the vulnerability of selective neuronal subtypes to challenging environmental conditions, such as stress. In this context, parvalbumin-positive GABAergic interneurons, which are critically involved in processing complex cognitive tasks, are particularly vulnerable to stress exposure, an effect that may be the consequence of dysregulated redox mechanisms. Methods: Adult Male Wistar rats were subjected to the chronic mild stress procedure for 7 weeks. After 2 weeks, both control and stress groups were further divided into matched subgroups to receive chronic administration of vehicle or lurasidone (3 mg/kg/d) for the subsequent 5 weeks. Using real-time RT-PCR and western blot, we investigated the expression of GABAergic interneuron markers and the levels of key mediators of the oxidative balance in the dorsal and ventral hippocampus. Results: Chronic mild stress induced a specific decrease of parvalbumin expression in the dorsal hippocampus, an effect normalized by lurasidone treatment. Interestingly, the regulation of parvalbumin levels was correlated to the modulation of the antioxidant master regulator NRF2 and its chaperon protein KEAP1, which were also modulated by pharmacological intervention. Conclusions: Our findings suggest that the susceptibility of parvalbumin neurons to stress may represent a key mechanism contributing to functional and structural impairments in specific brain regions relevant for psychiatric disorders. Moreover, we provide new insights on the mechanism of action of lurasidone, demonstrating that its chronic treatment normalizes chronic mild stress-induced parvalbumin alterations, possibly by potentiating antioxidant mechanisms, which may ameliorate specific functions that are deteriorated in psychiatric patients.

Stress-induced anhedonia is associated with the activation of the inflammatory system in the rat brain: Restorative effect of pharmacological intervention.

Major depression is a complex disease that originates from the interaction between a genetic background of susceptibility and environmental factors such as stress. At molecular level, it is characterized by dysfunctions of multiple systems including neurotransmitters, hormones, signalling pathways, neurotrophic and neuroplastic molecules and - more recently - inflammatory mediators. Accordingly, in the present study we used the chronic mild stress (CMS) paradigm in the rat to elucidate to what extent brain inflammation may contribute to the development and/or the maintenance of an anhedonic phenotype and how pharmacological intervention may interfere with such behavioral and molecular stress-induced alterations. To this aim, adult male rats were exposed to CMS for 2 weeks and the cerebral expression of several mediators of the inflammatory system was evaluated in the hippocampus and prefrontal cortex of both stressed and control animals in parallel with the sucrose intake. Next, the animals that showed a decreased sucrose consumption were exposed to five further weeks of CMS and treated with the antidepressants imipramine or agomelatine, or the antipsychotic lurasidone. Our results demonstrate that only the stressed animals that were characterized by a deficit in sucrose intake showed increased expression of the pro-inflammatory cytokines IL-1ß, IL-6 and up-regulation of markers and mediators of microglia activation such as CD11b, CX3CL1 and its receptor CX3CR1 in comparison with stress-resilient animals. Some of these molecular alterations persisted also after longer stress exposure and were modulated, similarly to the behavioral effects of CMS, by chronic pharmacological treatment. These data suggest that neuroinflammation may have a key role in the pathological consequences of stress exposure, thus contributing to the subject's vulnerability for depression.

Olive oil-enriched diet reduces brain oxidative damages and ameliorates neurotrophic factor gene expression in different life stages of rats.

Our aim was to assess the influence of maternal diet rich in monounsaturated fatty acids on oxidative and molecular parameters in brains of mouse pups as well as their body weight during their lifetime. Female rats received a diet containing 20% of olive oil-enriched diet (OOED) and a standard diet control diet (CD) in different periods: pregnancy, lactation and after weaning until pups' adulthood. On the last prenatal day (Group 1), embryos from OOED group showed smaller body weight, brain weight and lower levels of sulphydryl groups glutathione reduced (GSH) in the brain. On postnatal delay-21 (PND21) (Group 2), pups from OOED group showed higher body weight and brain weight, reduced brain weight/body weight ratio and lower brain lipid peroxidation (LP). On PND70 (Group 3), pups from OOED group showed lower brain LP and higher levels of GSH in prefrontal cortex and lower brain levels of reactive species in the hippocampus. Interestingly, the group of animals whose diet was modified from OOED to CD on PND21 showed greater weight gain compared to the group that remained in the same original diet (OOED) until adulthood. Furthermore, OOED consumption during pregnancy and lactation significantly increased BDNF only, as well as its main transcripts exon IV and VI mRNA levels in the prefrontal cortex. In addition, OOED significantly up-regulated FGF-2 mRNA levels in the prefrontal cortex. These findings open a pioneering line of investigation about dietary adjunctive therapeutic strategies and the potential of healthy dietary habits to prevent neonatal conditions and their influence on adulthood.

Modulation of the inflammatory response in rats chronically treated with the antidepressant agomelatine.

Growing evidence suggests that the activation of the inflammatory/immune system contributes to depression pathogenesis, a hypothesis that might hold strong clinical implication. Indeed more than 30% of depressed patients fail to achieve remission, which poses the necessity to identify systems that may represent novel targets for medications. Accordingly, goal of this study was to evaluate the ability of the antidepressant agomelatine to modulate specific components of the immune response in the rat brain following an inflammatory challenge with lipopolysaccharide (LPS). To this aim, adult male rats were chronically treated with agomelatine before being acutely challenged with LPS 16 h after the last drug administration. Rats were sacrificed 2, 6, or 24h after the challenge and several components of the inflammatory response have been investigated by using real-time PCR or ELISA. We found that agomelatine significantly reduced the LPS-induced up-regulation of the pro-inflammatory cytokines interleukin-1ß and interleukin-6 in the rat brain as well as at peripheral level. At central level, these effects are associated to the inhibition of NF-κB translocation as well as to alterations of mechanisms responsible for microglia activation. In addition, we found that agomelatine was also able to alter the expression of enzymes related to the kynurenine pathway that are thought to represent important mediators to inflammation-related depression. These data disclose novel properties that may contribute to the therapeutic effect of agomelatine providing evidence for a crucial role of specific components of the immune/inflammatory system in the antidepressant response and thereby in depression etiopathology.

Inhibitor of NF-kappa B kinases alpha and beta are both essential for high mobility group box 1-mediated chemotaxis [corrected].

Inhibitor of NF-kappaB kinases beta (IKKbeta) and alpha (IKKalpha) activate distinct NF-kappaB signaling modules. The IKKbeta/canonical NF-kappaB pathway rapidly responds to stress-like conditions, whereas the IKKalpha/noncanonical pathway controls adaptive immunity. Moreover, IKKalpha can attenuate IKKbeta-initiated inflammatory responses. High mobility group box 1 (HMGB1), a chromatin protein, is an extracellular signal of tissue damage-attracting cells in inflammation, tissue regeneration, and scar formation. We show that IKKalpha and IKKbeta are each critically important for HMGB1-elicited chemotaxis of fibroblasts, macrophages, and neutrophils in vitro and neutrophils in vivo. By time-lapse microscopy we dissected different parameters of the HMGB1 migration response and found that IKKalpha and IKKbeta are each essential to polarize cells toward HMGB1 and that each kinase also differentially affects cellular velocity in a time-dependent manner. In addition, HMGB1 modestly induces noncanonical IKKalpha-dependent p52 nuclear translocation and p52/RelB target gene expression. Akin to IKKalpha and IKKbeta, p52 and RelB are also required for HMGB1 chemotaxis, and p52 is essential for cellular orientation toward an HMGB1 gradient. RAGE, a ubiquitously expressed HMGB1 receptor, is required for HMGB1 chemotaxis. Moreover, IKKbeta, but not IKKalpha, is required for HMGB1 to induce RAGE mRNA, suggesting that RAGE is at least one IKKbeta target involved in HMGB1 migration responses, and in accord with these results enforced RAGE expression rescues the HMGB1 migration defect of IKKbeta, but not IKKalpha, null cells. Thus, proinflammatory HMGB1 chemotactic responses mechanistically require the differential collaboration of both IKK-dependent NF-kappaB signaling pathways.

The GIT-PIX complexes regulate the chemotactic response of rat basophilic leukaemia cells.

BACKGROUND INFORMATION: Cell motility entails the reorganization of the cytoskeleton and membrane trafficking for effective protrusion. The GIT-PIX protein complexes are involved in the regulation of cell motility and adhesion and in the endocytic traffic of members of the family of G-protein-coupled receptors. We have investigated the function of the endogenous GIT complexes in the regulation of cell motility stimulated by fMLP (formyl-Met-Leu-Phe) peptide, in a rat basophilic leukaemia RBL-2H3 cell line stably expressing an HA (haemagglutinin)-tagged receptor for the fMLP peptide. RESULTS: Our analysis shows that RBL cells stably transfected with the chemoattractant receptor expressed both GIT1-PIX and GIT2-PIX endogenous complexes. We have used silencing of the different members of the complex by small interfering RNAs to study the effects on a number of events linked to agonist-induced cell migration. We found that cell adhesion was not affected by depletion of any of the proteins of the GIT complex, whereas agonist-enhanced cell spreading was inhibited. Analysis of agonist-stimulated haptotactic cell migration indicated a specific positive effect of GIT1 depletion on trans-well migration. The internalization of the formyl-peptide receptor was also inhibited by depletion of GIT1 and GIT2. The effects of the GIT complexes on trafficking of the receptors was confirmed by an antibody-enhanced agonist-induced internalization assay, showing that depletion of PIX, GIT1 or GIT2 protein caused decreased perinuclear accumulation of internalized receptors. CONCLUSIONS: Our results show that endogenous GIT complexes are involved in the regulation of chemoattractant-induced cell motility and receptor trafficking, and support previous findings indicating an important function of the GIT complexes in the regulation of different G-protein-coupled receptors. Our results also indicate that endogenous GIT1 and GIT2 regulate distinct subsets of agonist-induced responses and suggest a possible functional link between the control of receptor trafficking and the regulation of cell motility by GIT proteins.

Antipsychotic drug actions on gene modulation and signaling mechanisms.

Schizophrenia is a debilitating chronic mental disorder characterized by significant lifetime risk and high social costs. Although its etiology remains unknown, many of its symptoms may be mitigated by treatment with antipsychotic drugs (APDs). These compounds, generally classified as first- or second-generation antipsychotics, have complex receptor profiles that may account for short-term clinical response and normalization of acute manifestation of the disease. However, APDs have additional therapeutic properties that may not be directly related to receptor mechanisms, but rather involve neuroadaptive changes in selected brain regions. Indeed the neurodevelopmental origin of schizophrenia suggests that the disease is characterized by neuroanatomical and pathophysiological impairments that, at molecular level, may reflect compromised neuroplasticity; the process by which the brain adapts to changes in a specific environment. Accordingly, it is possible that the long-term clinical efficacy of APDs might result from their ability in modulating systems crucially involved in neuroplasticity and cellular resilience. We have reviewed and discussed the results of several studies investigating the post-receptor mechanisms in the action of APDs. We specifically focused on intracellular signaling cascades (PKA, DARPP-32, MAPK, Akt/GSK-3, beta arrestin-2), neurotrophic factors and the glutamatergic system as important mediators for antipsychotic drug induced-neuroplasticity. Altogether, these data highlight the possibility that post-receptor mechanisms will eventually be promising targets for the development of novel drugs that, through their impact on neuroplasticity, may contribute to the improved treatment of patients diagnosed with schizophrenia.

Beta-arrestin 2 is required for the induction and strengthening of integrin-mediated leukocyte adhesion during CXCR2-driven extravasation.

Leukocyte extravasation involves interdependent signaling pathways underlying the complex dynamics of firm adhesion, crawling, and diapedesis. While signal transduction by agonist-bound chemokine receptors plays a central role in the above responses, it is unclear how it contributes to the sustained and concurrent nature of such responses, given the rapid kinetics of chemokine-induced trimeric G protein coupling and homologous desensitization. Our findings unveil a novel role of beta-arrestins in regulating the activation of signaling pathways underlying discrete integrin-mediated steps in CXCR2-driven leukocyte extravasation. By combining in vivo approaches in beta-arrestin knockout mice with in vitro studies in engineered cellular models, we show that membrane-recruited beta-arrestin 2 is required for the onset and maintenance of shear stress-resistant leukocyte adhesion mediated by both beta(1) and beta(2) integrins. While both beta-arrestin isoforms are required for rapid keratinocyte-derived chemokine (KC)-induced arrest onto limiting amounts of vascular cell adhesion molecule-1 (VCAM-1), adhesion strengthening under shear is selectively dependent on beta-arrestin 2. The latter synergizes with phospholipase C in promoting activation of Rap1A and B, both of which co-operatively control subsecond adhesion as well as postarrest adhesion stabilization. Thus, receptor-induced Galpha(i) and beta-arrestins act sequentially and in spatially distinct compartments to promote optimal KC-induced integrin-dependent adhesion during leukocyte extravasation.

Quetiapine regulates FGF-2 and BDNF expression in the hippocampus of animals treated with MK-801.

Fibroblast growth factor-2 (FGF-2) and brain-derived neurotrophic factor (BDNF) are trophic factors, widely distributed in the adult brain, whose expression can be modulated by psychoactive drugs. Administration of the atypical antipsychotic quetiapine resulted in a marked elevation of FGF-2 and BDNF mRNA levels in the rat hippocampus, but only under conditions of reduced NMDA receptor activity. These effects were drug-specific, given that they were not observed with the conventional antipsychotic haloperidol; and anatomically defined, since no similar effect was observed in striatum, prefrontal or frontal cortex. These results suggest that quetiapine may promote neuroplasticity via the up-regulation of neurotrophic factors when NMDA-mediated transmission is perturbed.

Voluntary exercise increases axonal regeneration from sensory neurons.

Recent advances in understanding the role of neurotrophins on activity-dependent plasticity have provided insight into how behavior can affect specific aspects of neuronal biology. We present evidence that voluntary exercise can prime adult dorsal root ganglion neurons for increased axonal regeneration through a neurotrophin-dependent mechanism. Dorsal root ganglion neurons showed an increase in neurite outgrowth when cultured from animals that had undergone 3 or 7 days of exercise compared with sedentary animals. Neurite length over 18-22 h in culture correlated directly with the distance that animals ran. The exercise-conditioned animals also showed enhanced regrowth of axons after an in vivo nerve crush injury. Sensory ganglia from the 3- and 7-day-exercised animals contained higher brain-derived neurotrophic factor, neurotrophin 3, synapsin I, and GAP43 mRNA levels than those from sedentary animals. Consistent with the rise in brain-derived neurotrophic factor and neurotrophin 3 during exercise, the increased growth potential of the exercise-conditioned animals required activation of the neurotrophin signaling in vivo during the exercise period but did not require new mRNA synthesis in culture.