The antidepressant effects of GM-CSF are mediated by the reduction of TLR4/NF-ĸB-induced IDO expression

Along the microbiota-gut-brain axis: Use of plant polysaccharides to improve mental disorders

With the development of gut microbiota-specific interventions for mental disorders, the interactions between plant polysaccharides and microbiota in the intestinal and their consequent effects are becoming increasingly important. In this review, we discussed the role of plant polysaccharides in improving various mental disorders via the microbiota-gut-brain axis. The chemical and structural characteristics and metabolites of these plant polysaccharides were summarised. Plant polysaccharides and their metabolites have great potential for reshaping gut microbiota profiles through gut microbiota-dependent fermentation. Along the microbiota-gut-brain axis, the consequent pharmacological processes that lead to the elimination of the symptoms of mental disorders include 1) regulation of the central monoamine neurotransmitters, amino acid transmitters and cholinergic signalling system; 2) alleviation of central and peripheral inflammation mainly through the NLRP3/NF-κB-related signalling pathway; 3) inhibition of neuronal apoptosis; and 4) enhancement of antioxidant activities. According to this review, monosaccharide glucose and structure -4-α-Glcp-(1→ are the most potent compositions of the most reported plant polysaccharides. However, the causal structure-activity relationship remains to be extensively explored. Moreover, mechanistic elucidation, safety verification, and additional rigorous human studies are expected to advance plant polysaccharide-based product development targeting the microbiota-gut-brain axis for people with mental disorders.

Rehmannia alcohol extract inhibits neuropeptide secretion and alleviates osteoarthritis pain through cartilage protection

Osteoarthritis (OA) is a common joint disease characterized by chronic pain, and the perception of pain is closely associated with brain function and neuropeptide regulation. Rehmannia is common plant herb with anti-inflammatory and analgesic properties that is used to treat OA. However, it is unclear whether Rehmannia alleviates OA-related pain via regulation of neuropeptides and brain function. We examined the pain relief regulatory pathway in OA after treatment with Rehmannia by verifying the therapeutic effect of Rehmannia alcohol extract in vivo and vitro and exploring of the potential mechanism underlying the analgesic effect of Rahmanian using functional magnetic resonance imaging and measuring neuropeptide secretion. Our results showed that Rehmannia alcohol extract and the related active ingredient, Rehmannioside D, can delay cartilage degradation and alleviate inflammation in OA rats. The Rehmannia alcohol extract can also relieve OA pain, reduce the secretion of calcitonin gene-related peptide (CGRP) and substance P (SP), and reverse the pathological changes in the cerebral cortex and hippocampus. Our research results demonstrate that Rehmannia alleviates OA pain by protecting cartilage, preventing the stimulation of inflammatory factors on neuropeptide secretion, and influencing the relevant functional areas of the brain.

Bifidobacterium breve Bif11 supplementation improves depression-related neurobehavioural and neuroinflammatory changes in the mouse

Gut dysbiosis has been closely linked to the onset and progression of several brain-related disorders such as depression. The administration of microbiota-based formulations such as probiotics helps restore healthy gut flora and plays a role in preventing and treating depression-like behavior. Therefore, we evaluated the efficacy of probiotic supplementation using our recently isolated putative probiotic Bifidobacterium breve Bif11 in ameliorating lipopolysaccharide (LPS)-induced depression-like behavior in male Swiss albino mice. Mice were fed orally with B. breve Bif11 (1 × 10¹⁰ CFU and 2 × 10¹⁰ CFU) for 21 days before being challenged with a single intraperitoneal LPS injection (0.83 mg/kg). Behavioral, biochemical, histological and molecular analysis were done with an emphasis on inflammatory pathways linked to depression-like behavior. Daily supplementation with B. breve Bif11 for 21 days prevented the onset of depression-like behavior induced by LPS injection, besides reducing the levels of inflammatory cytokines such as matrix metalloproteinase-2, c-reactive protein, interleukin-6, tumor necrosis factor-alpha and nuclear factor kappa-light-chain-enhancer of activated B cells. It also prevented the decrease of the brain-derived neurotrophic factor levels and neuronal cell viability in the prefrontal cortex of LPS-treated mice. Furthermore, we observed that gut permeability was reduced, there was an improved short-chain fatty acid profile and reduced gut dysbiosis in the LPS mice fed with B. breve Bif11. Similarly, we observed a decrease in behavioural deficits and restoration of gut permeability in chronic mild stress. Together, these results would help in deciphering the role of probiotics in the management of neurological disorders where depression, anxiety and inflammation are prominent clinical features.

IDO/Kynurenine; novel insight for treatment of inflammatory diseases

Inflammation and oxidative stress play pivotal roles in pathogenesis of many diseases including cancer, type 2 diabetes, cardiovascular disease, atherosclerosis, neurological diseases, and inflammatory diseases such as inflammatory bowel disease (IBD). Inflammatory mediators such as interleukins (ILs), interferons (INF-s), and tumor necrosis factor (TNF)-α are related to an extended chance of inflammatory diseases initiation or progression due to the over expression of the nuclear factor Kappa B (NF-κB), signal transducer of activators of transcription (STAT), nod-like receptor family protein 3 (NLRP), toll-like receptors (TLR), mitogen-activated protein kinase (MAPK), and mammalian target of rapamycin (mTOR) pathways. These pathways are completely interconnected. Theindoleamine 2,3 dioxygenase (IDO) subset of the kynurenine (KYN) (IDO/KYN), is a metabolic inflammatory pathway involved in production of nicotinamide adenine dinucleotide (NAD + ). It has been shown that IDO/KYN actively participates in inflammatory processes and can increase the secretion of cytokines that provoke inflammatory diseases. Data were extracted from clinical and animal studies published in English between 1990-April 2022, which were collected from PubMed, Google Scholar, Scopus, and Cochrane library. IDO/KYN is completely associated with inflammatory-related pathways, thus leading to the production of cytokines such as TNF-α, IL-1β, and IL-6, and ultimately development and progression of various inflammatory disorders. Inhibition of the IDO/KYN pathway might be a novel therapeutic option for inflammatory diseases. Herein, we gathered data on probable interactions of the IDO/KYN pathway with induction of some inflammatory diseases.

Blockade of Indoleamine 2,3-Dioxygenase attenuates lipopolysaccharide-induced kidney injury by inhibiting TLR4/NF-κB signaling

Blockade of indoleamine 2,3-dioxygenase (IDO) has been shown to alleviate lipopolysaccharide (LPS)-induced endotoxic shock and reduce sepsis mortality, but its effect on LPS-induced kidney damage has not been reported. Herein, we established a mouse kidney injury model by intraperitoneal injection of 10 mg/kg LPS and established an in vitro renal tubular epithelial cell injury model by stimulating TCMK-1 cells with 10 mg/L LPS. We found that pretreatment with 1-methyl tryptophan (1-MT), an IDO inhibitor, significantly improved LPS-induced mouse survival, and IDO knockout (KO) mice also had higher survival rates after LPS exposure than wild-type mice. At the same time, IDO KO or pretreatment with 1-MT not only reduced serum creatinine, blood urea nitrogen, renal tubular injury pathological score, but also inflammatory factors and oxidative stress status in serum or kidney of LPS-exposed mice. In vitro, blockade of IDO with 1-MT significantly inhibited LPS-induced apoptosis, inflammation and oxidative stress in TCMK-1 cells. In addition, blockade of IDO significantly inhibited LPS-activated TLR4/NF-κB signaling pathway in kidney of mice or in TCMK-1 cells. In conclusion, our results suggested that blockade of IDO attenuated kidney inflammation, apoptosis and oxidative stress to protect against LPS-induced septic kidney injury via inhibiting the TLR4/NF-κB signaling pathway.

Blueberry Extract Modulates Brain Enzymes Activities and Reduces Neuroinflammation: Promising Effect on Lipopolysaccharide-Induced Depressive-Like Behavior

Major depressive disorder (MDD) is one of the most common neuropsychiatric disorders with high rates of prevalence and mortality. MDD is pathophysiologically complex, and treatment options are limited. Blueberries are rich in polyphenols and have neuroprotective potential. The aim of this study was to investigate the effects of blueberry extract on neuroinflammatory and neuroplasticity parameters, as well as Na⁺/K⁺-ATPase, monoamine oxidase-A (MAO-A), and acetylcholinesterase (AChE) activities in the cerebral cortex and hippocampus of mice subject to lipopolysaccharide (LPS)-induced depressive-like behavior. We also analyzed the interaction between anthocyanins and indoleamine 2 3-dioxygenase (IDO). Male Swiss mice (60-day-old) received vehicle, fluoxetine (20 mg/kg), or blueberry extract (100 or 200 mg/kg) intragastrically for 7 days before intraperitoneal LPS (0.83 mg/kg) injection. Twenty-four hours after LPS administration, the mice were subjected to behavioral tests. Both fluoxetine and blueberry extract (200 mg/kg) decreased the immobility time in the forced swim test, without affecting locomotor activity. Fluoxetine attenuated the decrease of Na⁺/K⁺-ATPase in the cerebral cortex, while blueberry extract promoted this same effect in the hippocampus. Additionally, fluoxetine and blueberry extract attenuated the decrease in the activity of MAO-A in the hippocampus. Blueberry extract (200 mg/kg) also prevented LPS-induced increase in AChE activity in the hippocampus as well as LPS upregulation of relative mRNA expression of tumor necrosis factor alpha, interleukin (IL)-1β, and IL-10 in the cerebral cortex. Molecular docking analysis revealed binding sites for malvidin 3-galactoside (- 7.8 kcal/mol) and malvidin 3-glucoside (- 7.9 kcal/mol) residues with IDO. Taken together, these results indicate that blueberry extract improved depression-like behavior and attenuated the neurochemical and molecular changes in the brains of mice challenged with LPS.

ANKRD22 is a potential novel target for reversing the immunosuppressive effects of PMN-MDSCs in ovarian cancer

BACKGROUND

Ovarian cancer is the deadliest type of malignant gynecological tumor. Polymorphonuclear myeloid-derived suppressor cells (PMN-MDSCs) are involved ovarian cancer and are closely related to adverse outcomes. However, the immunosuppressive mechanism of PMN-MDSCs remains elusive.

METHODS

The types and numbers of ANKRD22-expressing cells were investigated by bioinformatics analysis and immunohistochemical staining. Ankrd22^-/- C57BL/6 mice were constructed with CRISPR-Cas9 technology. Mouse PMN-MDSCs were obtained from bone marrow (BM)-derived CD11b⁺Ly6G⁺Ly6C^low cells sorted by fluorescence-activated cell sorting with treatment of GM-CSF and IL-6, and the immunosuppressive activity of PMN-MDSCs was evaluated by flow cytometry (FCM) and ELISA. The expression level of CCR2 and the exogenous glucose uptake capacity were determined by FCM. RT-qPCR was used to detect ANKRD22 expression in CD11b⁺HLA-DR^-CD14^-CD15⁺ cells from human ovarian cancer tissues, and the correlations of ANKRD22 expression with the clinical characteristics and prognosis of patients were evaluated by the χ² test.

RESULTS

We identified a novel protein involved in regulating the immunosuppressive ability of PMN-MDSCs, ANKRD22. Ankrd22 expression was high in mouse CD11b⁺Ly6G⁺Ly6C^low cells and could be significantly downregulated after exposure to a simulated microenvironmental stimulus. Knockout of Ankrd22 increased the expression level of CCR2 of CD11b⁺Ly6G⁺Ly6C^low cells and the immunosuppressive activity of PMN-MDSCs. BM-derived CD11b⁺Ly6G⁺Ly6C^low cells of Ankrd22^-/- mice significantly promoted the proliferation of ovarian cancer cells in tumor xenograft mouse models. Mechanistically, RNA sequencing showed that Wdfy1 expression was obviously increased in Ankrd22-knockout BM-derived CD11b⁺Ly6G⁺ Ly6C^low cells and that ectopic expression of Wdfy1 increased the levels of Arg1, Inos, Ido and Pdl1 in Ankrd22^+/+ PMN-MDSCs derived from BM-derived CD11b⁺Ly6G⁺Ly6C^low cells. Surprisingly, an ANKRD22-activating candidate small-molecule compound attenuated the immunosuppressive activity of Ankrd22^+/+ PMN-MDSCs. Finally, we found that low ANKRD22 levels in CD11b⁺HLA-DR^-CD14^-CD15⁺ cells derived from primary ovarian tissues were associated with a more advanced International Federation of Gynecology and Obstetrics stage, a higher recurrence rate, and a higher neutrophil-to-lymphocyte ratio.

CONCLUSIONS

These results suggest that ANKRD22 is a potential novel target for reversing the immunosuppressive effects of PMN-MDSCs.

Role of 5-HT1A-mediated upregulation of brain indoleamine 2,3 dioxygenase 1 in the reduced antidepressant and antihyperalgesic effects of fluoxetine during maintenance treatment

The reduced antidepressant and antihyperalgesic effects of selective serotonin reuptake inhibitors (SSRIs) such as fluoxetine during maintenance treatment has been reported, but little is known about the molecular mechanism of this phenomenon. In three comorbid pain and depression animal models (genetic predisposition, chronic social stress, arthritis), we showed that the fluoxetine's antidepressant and antihyperalgesic effects were reduced during the maintenance treatment. Fluoxetine exposure induced upregulation of the 5-hydroxytryptamine 1A (5-HT1A) auto-receptor and indoleamine 2,3 dioxygenase 1 (IDO1, a rate-limiting enzyme of tryptophan metabolism) in the brainstem dorsal raphe nucleus (DRN), which shifted the tryptophan metabolism away from the 5-HT biosynthesis. Mechanistically, IDO1 upregulation was downstream to fluoxetine-induced 5-HT1A receptor expression because 1) antagonism of the 5-HT1A receptor with WAY100635 or 5-HT1A receptor knockout blocked the IDO1 upregulation, and 2) inhibition of IDO1 activity did not block the 5-HT1A receptor upregulation following fluoxetine exposure. Importantly, inhibition of either the 5-HT1A receptor or IDO1 activity sustained the fluoxetine's antidepressant and antihyperalgesic effects, indicating that 5-HT1A-mediated IDO1 upregulation in the brainstem DRN contributed to the reduced antidepressant and antihyperalgesic effects of fluoxetine. These results suggest a new strategy to improving the therapeutic efficacy of SSRI during maintenance treatment.

Selective serotonin reuptake inhibitors and preeclampsia: A quality assessment and meta-analysis

Serotonin modulates vascular, immune, and neurophysiology and is dysregulated in preeclampsia. Despite biological plausibility that selective serotonin reuptake inhibitors (SSRIs) prevent preeclampsia pathophysiology, observational studies have indicated increased risk and providers may be hesitant. The objective of this meta-analysis and quality assessment was to evaluate the evidence linking SSRI use in pregnancy to preeclampsia/gestational hypertension. PubMed was searched through June 5, 2020 manually and using combinations of terms: "preeclampsia", "serotonin", and "SSRI". This review followed MOOSE guidelines. Inclusion criteria were: 1) Observational cohort or population study, 2) exposure defined as SSRI use during pregnancy, 3) cases defined as preeclampsia or gestational hypertension, and 4) human participants. Studies were selected that addressed the hypothesis that gestational SSRI use modulates preeclampsia and/or gestational hypertension risk. Review Manager Web was used to synthesize study findings. Articles were read and scored (Newcastle-Ottawa Quality Assessment Scale) for quality by two independent reviewers. Publication bias was assessed using a funnel plot and the Egger test. Of 179 screened studies, nine were included. The pooled risk ratio (random effects model) was 1.43 (95 % CI: 1.15-1.78, P < 0.001; range 0.96-4.86). Two studies were rated as moderate quality (both with total score of 6); others were high quality. Heterogeneity was high (I2 = 88 %) and funnel asymmetry was significant (p < 0.00001). Despite evidence for increased preeclampsia risk with SSRIs, shared risk factors and other variables are poorly controlled. Depression treatment should not be withheld due to perceived gestational hypertension risk. Mechanistic evidence for serotonin modulation in preeclampsia demonstrates a need for future research.

Polysaccharides from Polygonatum cyrtonema Hua Reduce Depression-Like Behavior in Mice by Inhibiting Oxidative Stress-Calpain-1-NLRP3 Signaling Axis

Polysaccharides from Polygonatum cyrtonema Hua (PSP) exert antioxidant, anti-inflammatory, and antidepressant effects. Production of reactive oxygen species (ROS) and activation of the calpain system and the NOD-like receptor protein 3 (NLRP3) inflammasome are closely related to the pathogenesis of depression. However, the relationships among those pathways and the protective effects of PSP have not been characterized. In this study, lipopolysaccharide (LPS) and chronic unpredictable mild stress- (CUMS-) induced depression models were used to evaluate the protective mechanisms of PSP against depression. ROS levels were measured in HT-22 cells using flow cytometry. Brain tissues were collected to determine the levels of oxidation-related indicators and inflammatory cytokines. The protein levels of calpain-1, calpain-2, calpastatin, phosphatase and Tensin Homolog deleted on Chromosome 10 (PTEN), suprachiasmatic nucleus circadian oscillatory protein (SCOP), nuclear factor-erythroid factor 2-related factor 2 (Nrf2), heme oxygenase-1 (HO-1), NLRP3, apoptosis-associated speck-like protein (ASC), caspase-1, cleaved-caspase-1, ionized calcium binding adapter molecule 1 (Iba1), phosphorylation of extracellular signal-regulated kinase (p-ERK), nuclear factor-kappa B (NF-κB), interleukin-1β (IL-1β), and glial fibrillary acidic protein (GFAP) were measured using western blotting or immunofluorescence. In cellular experiments, we showed that PSP attenuated LPS-induced production of ROS in HT-22 cells. In animal experiments, we found that LPS increased the expression of calpain-1, NLRP3, ASC, caspase-1, cleaved-caspase-1, Iba1, p-ERK, NF-κB, and GFAP and reduced the expression of calpastatin, PTEN, SCOP, and Nrf2. Administration of PSP reversed these changes. N-Acetyl-L-cysteine (NAC) administration also inhibited oxidative stress and activation of the calpain system and the NLRP3 inflammasome. Furthermore, PSP, calpeptin, MCC950 (a selective NLRP3 inflammasome inhibitor), and NAC reduced LPS-induced proinflammatory cytokine release. We also showed that PSP prevented CUMS-induced changes in the calpain system and the Nrf2 and NLRP3 signaling pathways and reduced depression-like behavior. These results indicate that PSP exerts antidepressant effects through regulation of the oxidative stress-calpain-1-NLRP3 signaling axis.

Colony stimulating factors in the nervous system

Although traditionally seen as regulators of hematopoiesis, colony-stimulating factors (CSFs) have emerged as important players in the nervous system, both in health and disease. This review summarizes the cellular sources, patterns of expression and physiological roles of the macrophage (CSF-1, IL-34), granulocyte-macrophage (GM-CSF) and granulocyte (G-CSF) colony stimulating factors within the nervous system, with a particular focus on their actions on microglia. CSF-1 and IL-34, via the CSF-1R, are required for the development, proliferation and maintenance of essentially all CNS microglia in a temporal and regional specific manner. In contrast, in steady state, GM-CSF and G-CSF are mainly involved in regulation of microglial function. The alterations in expression of these growth factors and their receptors, that have been reported in several neurological diseases, are described and the outcomes of their therapeutic targeting in mouse models and humans are discussed.

RGFP966 is protective against lipopolysaccharide-induced depressive-like behaviors in mice by inhibiting neuroinflammation and microglial activation

Depression is a prevalent mental disorder. However, its pathophysiological mechanism has still remained elusive, and a limited number of effective treatments have been presented. Recent studies have shown that neuroinflammation and microglial activation are involved in the pathogenesis of depression. Histone deacetylase 3 (HDAC3) has neurotoxic effects on several neuropathological conditions. The inhibition of HDAC3 has been reported to induce anti-inflammatory and antioxidant effects. RGFP966 is a highly selective inhibitor of HDAC3. This study aimed to investigate the antidepressant effect of RGFP966 on lipopolysaccharide (LPS)-induced depressive-like behaviors in mice and to explore its possible mechanism. Adult male C57BL/6J mice were utilized in this study. The LPS and RGFP966 were injected intraperitoneally daily for 5 days. The behavior tests were performed to elucidate the depression-like behaviors. Western blot, ELISA and immunofluorescence staining were used to study the HDAC3/TLR4/NLRP3 pathway-related proteins. The results of behavioral tests showed that RGFP966 could improve the LPS-induced depressive-like behaviors in mice. The results of Western blotting showed that RGFP966 treatment downregulated the expression levels of toll-like receptor 4 (TLR4), nucleotide-binding oligomerization domain-like receptor pyrin domain-containing-3 (NLRP3), caspase-1, and interleukin-1β (IL-1β) (P < 0.05). Furthermore, the results of immunofluorescence staining showed that RGFP966 treatment inhibited microglial activation in the hippocampus of mice (P < 0.01). These findings suggested that RGFP966 could effectively ameliorate LPS-induced depressive-like behaviors in mice by inhibiting neuroinflammation and microglial activation. The anti-inflammatory mechanism of RGFP966 might be related to the inhibition of the HDAC3/TLR4/NLRP3 signaling pathway. Therefore, inhibition of HDAC3 using RGFP966 could serve as a potential treatment strategy for depression.

Polygonatum sibiricum polysaccharide prevents depression-like behaviors by reducing oxidative stress, inflammation, and cellular and synaptic damage

ETHNOPHARMACOLOGICAL RELEVANCE

According to traditional Chinese medicine (TCM) theory (Yi Xue Zheng Zhuan), the main factors associated with the pathogenesis of depression are deficiencies relating to five zang organs, Qi, and blood. Polygonatum sibiricum F. Delaroche (PS), which may avert these pathological changes, has been used in a variety of formulas to treat depression. However, the effects and mechanism of action of PS, alone, and especially those of its main active component PS polysaccharide (PSP), on depression remain unexplored.

AIM OF THE STUDY

To determine the effects of PSP on depression-like behaviors and to elucidate its mechanism of action.

METHODS

PSP was isolated from dried PS rhizomes and qualified using transmission electron microscopy and Fourier transform infrared spectroscopy. Lipopolysaccharide (LPS) and chronic unpredictable mild stress (CUMS)-induced depression models were used to evaluate the antidepressive effects of PSP. Veinal blood and brain tissue were collected to determine the levels of hippocampal 5-HT, serum cortisol (CORT), brain and serum cytokines, and hippocampal oxidation-related indicators. The protein expression levels of phosphorylated extracellular signal-regulated kinase (p-ERK1/2), nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB), glial fibrillary acidic protein (GFAP), phosphorylated protein kinase B (p-Akt), phosphorylation of the mammalian target of rapamycin (mTOR), caspase-3, GluA1 and GluA2, and GluN2A and GluN2B were determined using western blotting and immunofluorescence. Nissl staining was performed to detect histopathological changes in brain tissues.

RESULTS

Injection of LPS (i.p.) induced depression-like behaviors, reduced the level of hippocampal 5-HT, increased the serum CORT level and hippocampal oxidative stress (ROS), and prompted the activation of ERK1/2, NF-κB, and GFAP and an inflammatory response. Conversely, PSP administration reduced these changes and prevented depression-like behaviors. PSP administration also promoted hippocampal expression of p-Akt, p-mTOR, GluA1, and GluA2; reduced the expression of caspase-3, GluN2A, and GluN2B; and prohibited the loss of granular cells in the DG region.

CONCLUSION

These results indicate that PSP prevents depression-like behaviors, and synaptic and neuronal damage probably by reducing ROS/HPA axis hyperfunction and the inflammatory response.

Neuroinflammation and the Kynurenine Pathway in CNS Disease: Molecular Mechanisms and Therapeutic Implications

Diseases of the central nervous system (CNS) remain a significant health, social and economic problem around the globe. The development of therapeutic strategies for CNS conditions has suffered due to a poor understanding of the underlying pathologies that manifest them. Understanding common etiological origins at the cellular and molecular level is essential to enhance the development of efficacious and targeted treatment options. Over the years, neuroinflammation has been posited as a common link between multiple neurological, neurodegenerative and neuropsychiatric disorders. Processes that precipitate neuroinflammatory conditions including genetics, infections, physical injury and psychosocial factors, like stress and trauma, closely link dysregulation in kynurenine pathway (KP) of tryptophan metabolism as a possible pathophysiological factor that 'fuel the fire' in CNS diseases. In this study, we aim to review emerging evidence that provide mechanistic insights between different CNS disorders, neuroinflammation and the KP. We provide a thorough overview of the different branches of the KP pertinent to CNS disease pathology that have therapeutic implications for the development of selected and efficacious treatment strategies.

Neuroinflammation decreased hippocampal microtubule dynamics in the acute behavioral deficits induced by intracerebroventricular injection of lipopolysaccharide in male adult rats

Neuroinflammation plays a vital role in the pathology of depression. Microtubule dynamics produces an immediate response to stress, but the effect of microtubule dynamics in the rats with acute behavioral deficits following a central immune challenge remains elusive. Adult male Sprague-Dawley rats were subjected to the intracerebroventricular (icv) injection of lipopolysaccharide (. Behavioral tests, including bodyweight, sucrose preference test (SPT), forced swimming test (FST) and open field test (OFT), were performed to evaluate anxiety-like and depressive-like phenotypes at 24 h after injection, and some neuroinflammation biomarkers and microtubule dynamics in the hippocampus were detected. Lipopolysaccharide decreased the bodyweight, sucrose preference in SPT (depressive-like behavior), spontaneous activity in OFT (anxiety-like behavior) and increased the immobility time in FST (depressive-like behavior). Besides, lipopolysaccharide increased the mRNA levels of hippocampal CD11b and ionized calcium binding adaptor molecule (Iba1), which suggest microglial activation, and also upregulated hippocampal NLR Family Pyrin Domain Containing 3 inflammasome/interleukin-18/nuclear factor kappa-B mRNA. Lipopolysaccharide injection(icv) reduced the ratio of Tyr-/Acet-tubulin, an important marker of microtubule dynamics, in the acute behavioral deficit rats. Specifically, a decrease in Tyr-tubulin and an increase in the expression of Acet-tubulin were observed, indicating weakened microtubule dynamics. Pearson correlation analysis further showed that there was a significant negative correlation between hippocampal microtubule dynamics and neuroinflammatory activity. This study confirmed that hippocampal microtubule dynamics was decreased in the rats with acute behavioral deficits following a central immune challenge.

Dendritic Cells: Neglected Modulators of Peripheral Immune Responses and Neuroinflammation in Mood Disorders?

Affective disorders (AD) including major depressive disorder (MDD) and bipolar disorder (BD) are common mood disorders associated with increased disability and poor health outcomes. Altered immune responses characterized by increased serum levels of pro-inflammatory cytokines and neuroinflammation are common findings in patients with AD and in corresponding animal models. Dendritic cells (DCs) represent a heterogeneous population of myeloid cells that orchestrate innate and adaptive immune responses and self-tolerance. Upon sensing exogenous and endogenous danger signals, mature DCs secrete proinflammatory factors, acquire migratory and antigen presenting capacities and thus contribute to neuroinflammation in trauma, autoimmunity, and neurodegenerative diseases. However, little is known about the involvement of DCs in the pathogenesis of AD. In this review, we summarize the current knowledge on DCs in peripheral immune responses and neuroinflammation in MDD and BD. In addition, we consider the impact of DCs on neuroinflammation and behavior in animal models of AD. Finally, we will discuss therapeutic perspectives targeting DCs and their effector molecules in mood disorders.

Forecasting sensitive targets of the kynurenine pathway in pancreatic adenocarcinoma using mathematical modeling

In this study, a new mathematical model was established and validated to forecast and define sensitive targets in the kynurenine pathway (Kynp) in pancreatic adenocarcinoma (PDAC). Using the Panc-1 cell line, genetic profiles of Kynp molecules were tested. qPCR data were implemented in the algorithm programming (fmincon and lsqnonlin function) to estimate 35 parameters of Kynp variables by Matlab 2017b. All tested parameters were defined as non-negative and bounded. Then, based on experimental data, the function of the fmincon equation was employed to estimate the approximate range of each parameter. These calculations were confirmed by qPCR and Western blot. The correlation coefficient (R) between model simulation and experimental data (72 hours, in intervals of 6 hours) of every variable was >0.988. The analysis of reliability and predictive accuracy depending on qPCR and Western blot data showed high predictive accuracy of the model; R was >0.988. Using the model calculations, kynurenine (x3, a6), GPR35 (x4, a8), NF-kβp105 (x7, a16), and NF-kβp65 (x8, a18) were recognized as sensitive targets in the Kynp. These predicted targets were confirmed by testing gene and protein expression responses. Therefore, this study provides new interdisciplinary evidence for Kynp-sensitive targets in the treatment of PDAC.

Relationship Between Blood Cytokine Levels, Psychological Comorbidity, and Widespreadness of Pain in Chronic Pelvic Pain

Background: Low-grade inflammation has been implicated in the etiology of depression, long-term fatigue and chronic pain. TNFα and IL-6 are perhaps the most studied pro-inflammatory cytokines in the field of psychoneuroimmunology. The purpose of our study was to further investigate these relationships in patients with chronic pelvic pain specifically. Using plasma samples from a large, well-described cohort of patients with pelvic pain and healthy controls via the Multidisciplinary Approach to the Study of Chronic Pelvic Pain (MAPP) Research Network, we examined the relationship between TNFα and IL-6 and comorbid psychological symptoms. We also investigated the relationship between IL-8 and GM-CSF, and widespreadness of pain. Methods: We included baseline blood samples in the analyses, 261 patients (148 women) and 110 healthy controls (74 women). Fourteen pro- and anti-inflammatory or regulatory cytokines were analyzed in a Luminex^® xMAP^® high-sensitivity assay. We used regression models that accounted for known factors associated with the outcome variables to determine the relationship between cytokine levels and clinical measures. Results: There were no statistical differences in cytokine levels between patients and healthy controls when controlling for age. In patients, TNFα was significantly associated with levels of fatigue (p = 0.026), but not with pain intensity or depression. IL-6 was not significantly related to any of the outcome variables. Women with pelvic pain showed a negative relationship between IL-8 and widespreadness of pain, while men did not (p = 0.003). For both sexes, GM-CSF was positively related to widespreadness of pain (p = 0.039). Conclusion: Our results do not suggest low-grade systemic inflammation in chronic pelvic pain. Higher TNFα blood levels were related to higher fatigue ratings, while higher systemic GM-CSF levels predicted more widespread pain. Our study further suggests a potentially protective role of IL-8 with regard to with regard to the widepreadness of pain in the body, at least for women.

Trained Innate Immunity by Repeated Low-Dose Lipopolysaccharide Injections Displays Long-Term Neuroprotective Effects

Disrupted immune response is an important feature of many neurodegenerative conditions, including sepsis-associated cognitive impairment. Accumulating evidence has demonstrated that immune memory occurs in microglia, which has a significant impact on pathological hallmarks of neurological diseases. However, it remains unclear whether immune memory can cause subsequent alterations in the brain immune response and affect neurobehavioral outcomes in sepsis survivors. In the present study, mice received daily intraperitoneal injection of low-dose lipopolysaccharide (LPS, 0.1 mg/kg) for three consecutive days to induce immune memory (immune tolerance) and then were subjected to sham operation or cecal ligation and puncture (CLP) 9 months later, followed by a battery of neurobehavioral and biochemical studies. Here, we showed that repeated low-dose LPS injection-induced immune memory protected mice from sepsis-induced cognitive and affective impairments, which were accompanied by significantly decreased brain proinflammatory cytokines and immune response. In conclusion, our study suggests that modulation of brain immune responses by repeated LPS injections confers neuroprotective effects by preventing overactivated immune response in response to subsequent septic insult.

The antidepressant effects of asperosaponin VI are mediated by the suppression of microglial activation and reduction of TLR4/NF-κB-induced IDO expression

AIM

Indoleamine 2,3-dioxygenase 1 (IDO) is responsible for the progression of the kynurenine pathway, which has been implicated in the pathophysiology of inflammation-induced depression. It has been reported that asperosaponin VI (ASA VI) could play a neuroprotective role through anti-inflammatory and antioxidant. In this study, we examined the antidepressant effect of ASA VI in lipopolysaccharide (LPS)-treated mice and further explored its molecular mechanism by looking into the microglial kynurenine pathway.

METHODS

To generate the model, LPS (0.83 mg/kg) was administered intraperitoneally to mice. The mice received ASA VI (10 mg/kg, 20 mg/kg, 40 mg/kg, and 80 mg/kg, i.p.) 30 min before LPS injection. Depressive-like behaviors were evaluated based on the duration of immobility in the forced swim test. Microglial activation and inflammatory cytokines were detected by immunohistochemistry, real-time PCR, and ELISA. The TLR4/NF-κB signaling pathway and the expression of IDO, GluA2, and CamKIIβ were also measured by western blotting.

RESULTS

ASA VI exhibited significant antidepressant activity in the presence of LPS on immobility and latency times in the forced swim test. The LPS-induced activation of microglia and inflammatory response were inhibited by ASA VI, which showed a dose-dependent pattern. TLR4/NF-κB signaling pathway also was suppressed by ASA VI in the hippocampus and prefrontal cortex of LPS-treated mice. Furthermore, ASA VI inhibited the increase in IDO protein expression and normalized the aberrant glutamate transmission in the hippocampus and prefrontal cortex caused by LPS administration.

CONCLUSION

Our results propose a promising antidepressant effect for ASA VI possibly through the downregulation of IDO expression and normalization of the aberrant glutamate transmission. This remedying effect of ASA VI could be attributed to suppress microglia-mediated neuroinflammatory response via inhibiting the TLR4/NF-κB signaling pathway.

Antidepressants of different classes cause distinct behavioral and brain pro- and anti-inflammatory changes in mice submitted to an inflammatory model of depression

BACKGROUND

Depressed patients present increased plasma levels of lipopolysaccharide (LPS) and neuroinflammatory alterations. Here, we determined the neuroimmune effects of different classes of ADs by using the LPS inflammatory model of depression.

METHODS

Male rats received amitriptyline (AMI) a tricyclic, S-citalopram (ESC) a selective serotonin reuptake inhibitor, tranylcypromine (TCP) a monoamine oxidase inhibitor, vortioxetine (VORT) a multimodal AD or saline for ten days. One-hour after the last AD administration, rats were exposed to LPS 0.83 mg/kg or saline and 24 h later were tested for depressive-like behavior. Plasma corticosterone, brain levels of nitrite, pro- and anti-inflammatory cytokines, phospho-cAMP Response Element-Binding Protein (CREB) and nuclear factor (NF)-kB p 65 were determined.

RESULTS

LPS induced despair-like, impaired motivation/self-care behavior and caused anhedonia. All ADs prevented LPS-induced despair-like behavior, but only VORT rescued impaired self-care behavior. All ADs prevented LPS-induced increase in brain pro-inflammatory cytokines [interleukin (IL)-1β and IL-6] and T-helper 1 cytokines [tumor necrosis factor (TNF)-α and interferon-γ]. VORT increased striatal and hypothalamic IL-4 levels. All ADs prevented LPS-induced neuroendocrine alterations represented by increased levels of hypothalamic nitrite and plasma corticosterone response. VORT and ESC prevented LPS-induced increase in NF-kBp65 hippocampal expression, while ESC, TCP and VORT, but not IMI, prevented the alterations in phospho-CREB expression.

LIMITATIONS

LPS model helps to understand depression in a subset of depressed patients with immune activation. The levels of neurotransmitters were not determined.

CONCLUSION

This study provides new evidence for the immunomodulatory effects of ADs, and shows a possible superior anti-inflammatory profile of TCP and VORT.

Inflammation-induced behavioral changes is driven by alterations in Nrf2-dependent apoptosis and autophagy in mouse hippocampus: Role of fluoxetine

Inflammation has been associated with the progression of many neurological diseases. Peripheral inflammation has also been vaguely linked to depression-like symptoms in animal models, but the underlying pathways that orchestrate inflammation-induced behavioral or molecular changes in the brain are still elusive. We have recently shown that intraperitoneal injections of lipopolysaccharide (LPS) to Swiss albino mice triggers systemic inflammation, leading to an activated immune response along with changes in monoamine levels in the brain. Herein we pinpoint the fundamental pathways linking peripheral inflammation and depression-like behavior in a mouse model, thereby identifying suitable targets of intervention to combat the situation. We show that LPS-induced peripheral inflammation provoked a depression-like behavior in mice and a distinct pro-inflammatory bias in the hippocampus, as evident from increased microglial activation and elevated levels of pro-inflammatory cytokines IL-6 and TNF-α, and activation of NFκB-p65 pathway. Significant alterations in Nrf2-dependent cellular redox status, coupled with altered autophagy and increased apoptosis were noticed in the hippocampus of LPS-exposed mice. We and others have previously shown that, fluoxetine (an anti-depressant) has effective anti-inflammatory and antioxidant properties by virtue of its abilities to regulate NFκB and Nrf2 signaling. We observed that treatment with fluoxetine or the Nrf2 activator tBHQ (tert-butyl hydroquinone), could reverse depression-like-symptoms and mitigate alterations in autophagy and cell death pathways in the hippocampus by activating Nrf2-dependent gene expressions. Taken together, the data suggests that systemic inflammation potentiates Nrf2-dependent changes in cell death and autophagy pathway in the hippocampus, eventually leading to major pathologic sequelae associated with depression. Therefore, targeting Nrf2 could be a novel approach in combatting depression and ameliorating its associated pathogenesis.

Antidepressant effects of a polysaccharide from okra (Abelmoschus esculentus (L) Moench) by anti-inflammation and rebalancing the gut microbiota

The present study aimed to evaluate the antidepressant-like effect of a polysaccharide (OP), which is isolated from okra (Abelmoschus esculentus (L) Moench), in CUMS-induced mice and its possible mechanisms. OPT, FST and TST were employed to examine the anxiety and depressive behavior in CUMS-induced mice and fecal microbiota transplantation (FMT) CUMS-induced mice, while proinflammatory cytokines, TLR4/NF-κB pathway and MAPKs signaling were detected in both CUMS-induced mice and LPS-induced BV2 cells. The results showed that anxiety- and depressive-like behaviors, gut microbiota dysbiosis and changes of SCFAs, and activation of inflammatory reactions in the colon, serum, and hippocampus of CUMS-induced mice, as well as activation of inflammatory reactions in BV2 cells, could be alleviated by the treatment of OP. The mice that were colonized by OP microbiota showed improved anxiety and depressive behaviors and lower inflammatory response. Furthermore, OP inhibited the expression of TLR4, the nuclear translocation of NF-κB and high levels of proinflammatory cytokines, and enhanced the MAPKs signaling, these effects of OP also observed in LPS-induced BV2 cells. Above all, suggested that the potential mechanism of the antidepressant-like effects of OP was closely correlated with the bidirectional communication of microbiota-gut-brain axis via regulation of inflammation response.