The effect of newer serotonin-noradrenalin antidepressants on cytokine production: a review of the current literature

Cytokines may influence brain activities especially during stressful conditions, and elevated levels of IL-6 and C-reactive protein have been pointed out in subjects with Major Depression. If pro-inflammatory cytokines play a causative role in major depressive disorders, one would expect that antidepressants may down-regulate these cytokines or interfere with their actions, leading to improvement of depressive symptoms. Accumulating evidence has been published that antidepressants modulate cytokine production and this is particularly true for Tricyclics and Selective serotonin reuptake inhibitors (SSRIs), but the influence of newer antidepressants acting on both serotonin (5-HT) and norepinephrine (NE) such as venlafaxine, duloxetine and mirtazapine on cytokine levels has not been extensively studied. However, both pre-clinical and clinical studies examined in this review have demonstrated that newer serotonin-noradrenalin antidepressants can inhibit the production and/or release of pro-inflammatory cytokines and stimulate the production of anti-inflammatory cytokines, suggesting that reductions in inflammation might contribute to treatment response. Moreover, the results of the present review support the notion that the serotonin-noradrenalin antidepressants venlafaxine and mirtazapine may influence cytokine secretion in patients affected by MD, restoring the equilibrium between their physiological and pathological levels and leading to recovery. To date, no studies have evaluated the effect of duloxetine, the newest serotonin-noradrenalin antidepressant, on cytokine levels and therefore this should be evaluated in future studies.

Inflammatory Compounds: Neuropeptide Substance Pand Cytokines

Inflammatory diseases represent one of the major causes of morbidity and mortality throughout the world and they affect the functions of several tissues. The pathophysiology of these diseases involves release of many pro-inflammatory mediators such as cytokines/chemokines, histamine, C3a, C5a (complement components), bradykinin, leukotrienes (LTC4, LTD4, LTE4), PAF, and substance P, in addition to anti-inflammatory molecules. Recently, it has been demonstrated that neuroimmune interactions are important in the initiation and progress of inflammatory processes. Substance P is an 11-amino acid neuropeptide that is released from nerve endings in many tissues. It acts via membrane-bound NK1 receptors (NK1R). Inflammatory and neuropeptides such as substance P stimulate the release of chemokines, in particular IL-8, a potent neutrophil chemoattractant. Expression of IL-8 is regulated mainly by the transcription factors NF-kappaB, activating protein-1. Substance P plays an important role in immunological and inflammatory states, and it is a mediator of tissue injury, asthma, arthritis, allergy and autoimmune diseases. In this article, our studies revisited the interrelationship between these two powerful inflammatory compounds: substance P and cytokines. These observations suggest that these inflammatory molecules may represent a potential therapeutic target to treat several inflammatory states.

Alexithymia and its relationships with C-reactive protein and serum lipid levels among drug naïve adult outpatients with major depression

Several studies have investigated the relationship between C-reactive protein (CRP) and serum lipid levels in Major Depression (MD), but no study has, to date, evaluated the impact of alexithymia on these parameters. Therefore, the aim of the present cross-sectional study was to evaluate the relationship between alexithymia, suicide risk, C-reactive protein (CRP) and serum lipid levels in adult outpatients suffering from moderate to severe MD. CRP and serum lipid levels data were analyzed in 145 drug-naïve adult outpatients (69 men, 76 women) with a DSM-IV diagnosis of MD. Alexithymia was measured with the 20-item Toronto Alexithymia Scale (TAS-20), depression severity was evaluated with the 17-item Hamilton Depression Rating Scale (HAM-D) and suicide risk was determined using the Scale of Suicide Ideation (SSI). Alexithymics showed altered serum lipid levels and higher CRP than non-alexithymics. In the linear regression models, lower total cholesterol levels and "Difficulty in Identifying Feelings" dimension of TAS-20 were significantly associated with depression severity, whereas lower high-density lipoprotein levels and "Difficulty in Identifying and Describing Feelings" dimensions of TAS-20 were associated with higher suicide risk. Authors discuss study limitations and future research needs.