ASC provides a potential link between depression and inflammatory disorders: A clinical study of depressed Iranian medical students

The Emerging Role of Toll-Like Receptor-Mediated Neuroinflammatory Signals in Psychiatric Disorders and Acquired Epilepsy

The new and evolving paradigms of psychiatric disorders pathogenesis are deeply inclined toward chronic inflammation that leads to disturbances in the neuronal networks of patients. A strong association has been established between the inflammation and neurobiology of depression which is mediated by different toll-like receptors (TLRs). TLRs and associated signalling pathways are identified as key immune regulators to stress and infections in neurobiology. They are a special class of transmembrane proteins, which are one of the broadly studied members of the Pattern Recognition Patterns family. This review focuses on summarizing the important findings on the role of TLRs associated with psychotic disorders and acquired epilepsy. This review also shows the promising potential of TLRs in immune response mediated through antidepressant therapies and TLRs polymorphism associated with various psychotic disorders. Moreover, this also sheds light on future directions to further target TLRs as a therapeutic approach for psychiatric disorders.

Cellular and immunometabolic mechanisms of inflammation in depression: Preliminary findings from single cell RNA sequencing and a tribute to Bruce McEwen

Inflammation is associated with symptoms of anhedonia, a core feature of major depression (MD). We have shown that MD patients with high inflammation as measured by plasma C-reactive protein (CRP) and anhedonia display gene signatures of metabolic reprograming (e.g., shift to glycolysis) necessary to sustain cellular immune activation. To gain preliminary insight into the immune cell subsets and transcriptomic signatures that underlie increased inflammation and its relationship with behavior in MD at the single-cell (sc) level, herein we conducted scRNA-Seq on peripheral blood mononuclear cells from a subset of medically-stable, unmedicated MD outpatients. Three MD patients with high CRP (>3 mg/L) before and two weeks after anti-inflammatory challenge with the tumor necrosis factor antagonist infliximab and three patients with low CRP (≤3 mg/L) were studied. Cell clusters were identified using a Single Cell Wizard pipeline, followed by pathway analysis. CD14⁺ and CD16⁺ monocytes were more abundant in MD patients with high CRP and were reduced by 29% and 55% respectively after infliximab treatment. Within CD14⁺ and CD16⁺ monocytes, genes upregulated in high CRP patients were enriched for inflammatory (phagocytosis, complement, leukocyte migration) and immunometabolic (hypoxia-inducible factor [HIF]-1, aerobic glycolysis) pathways. Shifts in CD4⁺ T cell subsets included ∼30% and ∼10% lower abundance of CD4⁺ central memory (T_CM) and naïve cells and ∼50% increase in effector memory-like (T_EM-like) cells in high versus low CRP patients. T_CM cells of high CRP patients displayed downregulation of the oxidative phosphorylation (OXPHOS) pathway, a main energy source in this cell type. Following infliximab, changes in the number of CD14⁺ monocytes and CD4⁺ T_EM-like cells predicted improvements in anhedonia scores (r = 1.0, p < 0.001). In sum, monocytes and CD4⁺ T cells from MD patients with increased inflammation exhibited immunometabolic reprograming in association with symptoms of anhedonia. These findings are the first step toward determining the cellular and molecular immune pathways associated with inflammatory phenotypes in MD, which may lead to novel immunomodulatory treatments of psychiatric illnesses with increased inflammation.

Characterizing the NLRP3 Inflammasome in Mood Disorders: Overview, Technical Development, and Measures of Peripheral Activation in Adolescent Patients

The NOD-, LRR-, and pyrin-domain-containing protein 3 (NLRP3) inflammasome is a node of intracellular stress pathways and a druggable target which integrates mitochondrial stress and inflammatory cascades. While a body of evidence suggests the involvement of the NLRP3 inflammasome in numerous diseases, a lack of reliable measurement techniques highlights the need for a robust assay using small quantities of biological samples. We present a literature overview on peripheral activation of the NLRP3 inflammasome in mood disorders, then outline a process to develop and validate a robust assay to measure baseline and activated intracellular levels of “apoptosis-associated speck-like protein containing a CARD” (ASC) as a key component of an inflammatory profile in peripheral blood mononuclear cells (PBMC). A consistent association between high NLRP3 mRNA levels and relevant cytokines was seen in the literature. Using our method to measure ASC, stimulation of PBMC with lipopolysaccharide and nigericin or adenosine triphosphate resulted in microscopic identification of intracellular ASC specks, as well as interleukin 1 (IL-1) beta and caspase-1 p10 in the periphery. This was abolished by dose-dependent pre-treatment with 100 nM MCC950. We also report the use of this technique in a small pilot sample from patients with bipolar disorder and depressive disorders. The results show that levels of intracellular ASC and IL-1 beta are sensitive to change upon activation and maintained over time, which may be used to improve the detection of NLRP3 activation and guide personalized therapeutic strategy in the treatment of patients.

Chemotherapy: a double-edged sword in cancer treatment

Chemotherapy is a well-known and effective treatment for different cancers; unfortunately, it has not been as efficient in the eradication of all cancer cells as been expected. The mechanism of this failure was not fully clarified, yet. Meanwhile, alterations in the physiologic conditions of the tumor microenvironment (TME) were suggested as one of the underlying possibilities. Chemotherapy drugs can activate multiple signaling pathways and augment the secretion of inflammatory mediators. Inflammation may show two opposite roles in the TME. On the one hand, inflammation, as an innate immune response, tries to suppress tumor growth but on the other hand, it might be not powerful enough to eradicate the cancer cells and even it can provide appropriate conditions for cancer promotion and relapse as well. Therefore, the administration of mild anti-inflammatory drugs during chemotherapy might result in more successful clinical results. Here, we will review and discuss this hypothesis. Most chemotherapy agents are triggers of inflammation in the tumor microenvironment through inducing the production of senescence-associated secretory phenotype (SASP) molecules. Some chemotherapy agents can induce systematic inflammation by provoking TLR4 signaling or triggering IL-1B secretion through the inflammasome pathway. NF-kB and MAPK are key signaling pathways of inflammation and could be activated by several chemotherapy drugs. Furthermore, inflammation can play a key role in cancer development, metastasis and exacerbation.

Gene expression studies in Depression development and treatment: an overview of the underlying molecular mechanisms and biological processes to identify biomarkers

A combination of different risk factors, such as genetic, environmental and psychological factors, together with immune system, stress response, brain neuroplasticity and the regulation of neurotransmitters, is thought to lead to the development of major depressive disorder (MDD). A growing number of studies have tried to investigate the underlying mechanisms of MDD by analysing the expression levels of genes involved in such biological processes. These studies have shown that MDD is not just a brain disorder, but also a body disorder, and this is mainly due to the interplay between the periphery and the Central Nervous System (CNS). To this purpose, most of the studies conducted so far have mainly dedicated to the analysis of the gene expression levels using postmortem brain tissue as well as peripheral blood samples of MDD patients. In this paper, we reviewed the current literature on candidate gene expression alterations and the few existing transcriptomics studies in MDD focusing on inflammation, neuroplasticity, neurotransmitters and stress-related genes. Moreover, we focused our attention on studies, which have investigated mRNA levels as biomarkers to predict therapy outcomes. This is important as many patients do not respond to antidepressant medication or could experience adverse side effects, leading to the interruption of treatment. Unfortunately, the right choice of antidepressant for each individual still remains largely a matter of taking an educated guess.

Up-regulation of AIM2 and TLR4 and down-regulation of NLRC4 are associated with septicemia

PURPOSE

Innate immunity receptors play key roles in recognition of bacterial associated molecular patterns. Inflammasomes and toll like receptors (TLRs) are the important innate immunity receptors. In this project transcription levels of TLR4, a TLR member, absent in melanoma 2 (AIM2) and NLR family CARD domain-containing protein 4 (NLRC4), as inflammasomes, in the patients suffering from septicemia.

METHODS

AIM2, NLRC4 and TLR4 mRNA levels were evaluated in the 40 patients suffering from septicemia and 40 healthy controls using Real-Time PCR technique.

RESULTS

Data analysis revealed that, although NLRC4 expression decreased, TLR4 and AIM2 levels significantly increased in the patients suffering from septicemia. Gender and infection with various bacteria did not affect expression of AIM2, NLRC4 and TLR4.

CONCLUSIONS

It appears that septicemia can be limited by immune responses in AIM2 and TLR4 dependent manner. The potential roles played by bacteria to down-regulation of NLRC4 need to be evaluated by further investigations.

Melatonin Attenuates LPS-Induced Acute Depressive-Like Behaviors and Microglial NLRP3 Inflammasome Activation Through the SIRT1/Nrf2 Pathway

Inflammation is a crucial component of various stress-induced responses that contributes to the pathogenesis of major depressive disorder (MDD). Depressive-like behavior (DLB) is characterized by decreased mobility and depressive behavior that occurs in systemic infection induced by Lipopolysaccharide (LPS) in experimental animals and is considered as a model of exacerbation of MDD. We assessed the effects of melatonin on behavioral changes and inflammatory cytokine expression in hippocampus of mice in LPS-induced DLB, as well as its effects on NLR Family Pyrin Domain Containing 3 (NLRP3) inflammasome activation, oxidative stress and pyroptotic cell death in murine microglia in vitro. Intraperitoneal 5 mg/kg dose of LPS was used to mimic depressive-like behaviors and melatonin was given at a dose of 500 mg/kg for 4 times with 6 h intervals, starting at 2 h before LPS administration. Behavioral assessment was carried out at 24 h post-LPS injection by tail suspension and forced swimming tests. Additionally, hippocampal cytokine and NLRP3 protein levels were estimated. Melatonin increased mobility time of LPS-induced DLB mice and suppressed NLRP3 expression and interleukin-1β (IL-1β) cleavage in the hippocampus. Immunofluorescence staining of hippocampal tissue showed that NLRP3 is mainly expressed in ionized calcium-binding adapter molecule 1 (Iba1) -positive microglia. Our results show that melatonin prevents LPS and Adenosine triphosphate (ATP) induced NLRP3 inflammasome activation in murine microglia in vitro, evidenced by inhibition of NLRP3 expression, Apoptosis-associated speck-like protein containing a CARD (ASC) speck formation, caspase-1 cleavage and interleukin-1β (IL-1β) maturation and secretion. Additionally, melatonin inhibits pyroptosis, production of mitochondrial and cytosolic reactive oxygen species (ROS) and nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) signaling. The beneficial effects of melatonin on NLRP3 inflammasome activation were associated with nuclear factor erythroid 2–related factor 2 (Nrf2) and Silent information regulator 2 homolog 1 (SIRT1) activation, which were reversed by Nrf2 siRNA and SIRT1 inhibitor treatment.

Inflammasomes and their roles in the pathogenesis of viral hepatitis and their related complications: An updated systematic review

Inflammasomes are a set of innate receptors which are the responsible molecules for activation of pro-interleukin (IL)-1β and IL-18 and induction of inflammation. Due to the key roles of the inflammasomes in the induction of inflammation, it has been hypothesized that the molecules may be the main parts of immune responses against viral infections and the tissue damage. Because some cases of viral hepatitis infections, including hepatitis B and C, are diagnosed as chronic and may be associated with various complications such as liver cirrhosis and hepatocellular carcinoma (HCC), several studies focused on the roles played by the inflammation on the pathogenesis of viral hepatitis. Based on the roles played by inflammasomes in induction of inflammation, it has been hypothesized that inflammasomes may be the main parts of the puzzle of the viral hepatitis complications. This article reviews the roles of the inflammasomes in the pathogenesis of hepatitis B and C viral infections and their complications, liver cirrhosis, and HCC.

Prevalência da Depressão nos Acadêmicos da Área de Saúde

Resumo Os transtornos psiquiátricos possuem grande morbidade entre estudantes universitários da área da saúde. A depressão e ansiedade são os mais frequentes. O artigo se propõe a analisar os diferentes graus da depressão nos cursos da área de saúde e correlacionar esse transtorno ao gênero e à idade. O trabalho foi qualiquantitativo, desenvolvido com os acadêmicos de medicina, enfermagem e odontologia submetidos ao Inventário de Depressão de Beck (BDI). Fizeram parte da amostra 383 acadêmicos; a quantidade de alunos matriculados em medicina foi de 44 (11,62%), odontologia, 94 (24,50%) e enfermagem, 245 (63,87%). Desses, 273 (71,3%) eram mulheres e 110 (28,70%) homens com um intervalo na faixa etária de 26 a 33 anos. Identificou-se que não houve associação entre a variável depressão e gênero; a depressão grave foi constatada em 5,40% dos estudantes de odontologia, 8,60% dos de enfermagem e a depressão moderada a grave em 3,60% dos de medicina. Nota-se pelo BDI que os sintomas depressivos entre estudantes da área da saúde têm-se mostrado superior a outras populações de idade correspondente. A depressão é um fator de risco para a sociedade sendo importante a formulação de políticas de saúde mental, adotando-se medidas de apoio emocional, reestruturação da grade curricular e implementação de atividades psicológicas de autocontrole com criação de grupos de assistência psicológica ao aluno visando a prevenção de transtornos psíquicos nesses futuros profissionais da saúde.

Body composition does not affect serum levels of cathelicidin LL-37 in elderly women with unipolar depression

OBJECTIVES

Antimicrobial peptides are components of the innate immune system. Cathelicidin LL-37 plays an important role in antimicrobial defense, exerts proinflammatory effect and strongly affects the immune system functioning. Our recent study revealed that serum concentration of LL-37 is increased in elderly women with depression. The aim of this study is to evaluate serum LL-37 levels in elderly women with depression and to compare them with non-depressed elderly women, matched for anthropometric and body composition parameters.

METHODS

Forty women with unipolar depression and 23 non-depressed women (age ≥60 years) were included into the study. Anthropometric measurements and biochemical analyzes were performed. Concentration of LL-37 in serum was assessed using ELISA method. Body composition was measured using two methods: bioimpedance analysis (BIA) and dual-energy X-ray absorptiometry (DXA).

RESULTS

There was a statistically significant difference (p =.038) in serum LL-37 level between patients with depression (3.55 ± 6.57 ng/mL) and control subjects (2.01 ± 3.88 ng/mL). Apart from visceral adipose tissue mass (%) in the depression group, we found no associations between serum LL-37 and analyzed anthropometric or body composition parameters.

CONCLUSIONS

Results of this study indicate that with the exception of visceral adipose tissue, LL-37 serum levels are not affected by anthropometric or body composition parameters. The association between visceral adipose tissue and LL-37 may indicate that visceral fat could be responsible for the increased LL-37 production.

Gene deficiency and pharmacological inhibition of caspase-1 confers resilience to chronic social defeat stress via regulating the stability of surface AMPARs

Both inflammatory processes and glutamatergic systems have been implicated in the pathophysiology of mood-related disorders. However, the role of caspase-1, a classic inflammatory caspase, in behavioral responses to chronic stress remains largely unknown. To address this issue, we examined the effects and underlying mechanisms of caspase-1 on preclinical murine models of depression. We found that loss of caspase-1 expression in Caspase-1^-/- knockout mice alleviated chronic stress-induced depression-like behaviors, whereas overexpression of caspase-1 in the hippocampus of wild-type (WT) mice was sufficient to induce depression- and anxiety-like behaviors. Furthermore, chronic stress reduced glutamatergic neurotransmission and decreased surface expression of glutamate receptors in hippocampal pyramidal neurons of WT mice, but not Caspase-1^-/- mice. Importantly, pharmacological inhibition of caspase-1-interleukin-1β (IL-1β) signaling pathway prevented the depression-like behaviors and the decrease in surface expression of α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptors (AMPARs) in stressed WT mice. Finally, the effects of chronic stress on both depression- and anxiety-like behaviors can be mimicked by exogenous intracerebroventricular (i.c.v.) administration of IL-1β in both WT and Caspase-1^-/- mice. Taken together, our findings demonstrate that an increase in the caspase-1/IL-1β axis facilitates AMPAR internalization in the hippocampus, which dysregulates glutamatergic synaptic transmission, eventually resulting in depression-like behaviors. These results may represent an endophenotype for chronic stress-induced depression.

Inflammasomes in neurological diseases: emerging pathogenic and therapeutic concepts

Inflammasome activation in the central nervous system occurs in both health and disease. Inflammasomes are cytosolic protein complexes that sense specific infectious or host stimuli and initiate inflammatory responses through caspase activation. Assembly of inflammasomes results in caspase-1-mediated proteolytic cleavage and release of the pro-inflammatory cytokines, interleukin-1β and interleukin-18, with initiation of pyroptosis, an inflammatory programmed cell death. Recent developments in the inflammasome field have uncovered novel molecular mechanisms that contribute to a broad range of neurological disorders including those associated with specific mutations in inflammasome genes as well as diseases modulated by inflammasome activation. This update focuses on recent developments in the field of inflammasome biology highlighting different inflammasome activators and pathways discovered in the nervous system. We also discuss targeted therapies that regulate inflammasomes and improve neurological outcomes.

IL6-174G > C genetic polymorphism influences antidepressant treatment outcome

BACKGROUND

Major depressive disorder is a condition associated with dysregulated cytokine levels; among these, IL6. Furthermore, genetic variations within cytokine genes have been proposed to predict antidepressant treatment outcome.

OBJECTIVES

This study aims to evaluate the role of IL6-174G > C and IL6R D358A A > C functional polymorphisms in antidepressant treatment phenotypes, specifically remission, relapse, and treatment resistant depression (TRD).

METHODS

The referred polymorphisms were genotyped in 80 MDD patients followed at Hospital Magalhães Lemos, Portugal, within a period of 27 months.

RESULTS

It was found that patients carrying IL6-174 GC genotype present a protection towards the development of TRD (OR = 0.242; 95% CI = 0.068-0.869; p = .038), when compared with GG genotype. Additionally, carriers of IL6-174 CC genotype remit earlier than patients with IL6-174 GG/GC genotypes, with a median time to remission of 6 weeks for CC carriers and 15 weeks for GG or GC carriers (p = .030, Log-rank test). No association was found between IL6R D358A genetic polymorphism and any of the treatment phenotypes evaluated.

CONCLUSIONS

The IL6-174G > C polymorphism influences antidepressant treatment outcome in this sub-set of MDD patients, providing a putative mechanistic link for the dysregulated IL-6 levels described in the literature in patients with TRD.

Anxiety leads to up-regulation of CD36 on the monocytes of chronic hepatitis B-infected patients

Introduction It has been hypothesized that mental disorders including depression and anxiety can affect immune responses. The study was done to evaluate the relation between depression and anxiety and expression levels of CD36, CD68, and CD9 on peripheral blood monocytes of chronic hepatitis B (CHB) patients. Methods Sixty CHB patients were selected with various ranges of depression and anxiety. Depression and anxiety were evaluated using a standard questionnaire by an expert psychiatrist according to BECK's Depression Inventory II and Hamilton Anxiety Rating Scale, respectively. The levels of CD36, CD68, and CD9 on the peripheral blood monocytes have been performed using flow cytometry technique. Results The results demonstrated that levels of CD36 were significantly increased on the peripheral blood monocytes of CHB patients when compared with CHB patients with no anxiety. Expression levels of CD68 and CD9 were not significantly altered on the CHB patients with various ranges of anxiety. Expression levels of CD36, CD68, and CD9 were also not significantly altered on the CHB patients with various ranges of depression. Discussion It seems that anxiety induces inflammation in the CHB patients by induction of alteration in several molecules including up-regulation of CD36. CD36 plays important roles in the induction of tissue damage; hence, it may be hypothesized that anxiety may participate in the induction of some hepatitis B complications.