Cytokines and related receptor-mediated signaling pathways

Cytokines represent a multi-diverse family of polypeptide regulators; they are of relatively low molecular weight, pharmacologically active proteins that are secreted by one cell for the purpose of altering either its own functions (autocrine effect) or those of adjacent cells (paracrine effect). Cytokines are small, non-enzymatic glycoproteins whose actions are both diverse and overlapping (specificity/redundancy) and may affect diverse and overlapping target cell populations. In many instances, individual cytokines have multiple biological activities. Different cytokines can also have the same activity, which provides for functional redundancy within the inflammatory and immune systems. As biological cofactors that are released by specific cells, cytokines have specific effects on cell-cell interaction, communication, and behavior of other cells. As a result, it is infrequent that loss or neutralization of one cytokine will markedly interfere with either of these systems. The biological effect of one cytokine is often modified or augmented by another. Because an inter-digitating, redundant network of cytokines is involved in the production of most biological effects, both under physiologic and pathologic conditions, it usually requires more than a single defect in the network to alter drastically the outcome of the process. This fact therefore may have crucial significance in the development of therapeutic strategies for bio-pharmacologic intervention in cytokine-mediated inflammatory processes and infections.     

Melanin-concentrating hormone and immune function

To date, melanin-concentrating hormone (MCH) has been generally considered as peptide acting almost exclusively in the central nervous system. In the present paper, we revise the experimental evidence, demonstrating that MCH and its receptors are expressed by cells of the immune system and directly influence the response of these cells in some circumstances. This therefore supports the idea that, as with other peptides, MCH could be considered as a modulator of the immune system. Moreover, we suggest that this could have important implications in several immune-mediated disorders and affirm that there is a clear need for further investigation.     

Increased concentrations of IL-18 and uric acid in sickle cell anemia: contribution of hemolysis, endothelial activation and the inflammasome

Sickle cell anemia (SCA) is a common, severe monogenetic disorder characterized by chronic hemolysis, frequent infections, a chronic inflammatory state and recurrent occlusions of the microcirculation, resulting in painful crises, organ damage and premature death. This study evaluated associations between serum levels of IL-18, uric acid, hemolytic markers, and inflammatory molecules in SCA patients. A cross-sectional study was performed including 45 SCA patients (median age of 20.5 years) without general symptoms and who had not undergone blood transfusions. Inclusion criteria for the steady-state SCA patients were the absence of hospitalization and the absence of infections. Interleukin-18 and uric acid levels were correlated closely with markers of hemolysis, endothelial dysfunction and others cytokines levels. These findings suggest probable influences of IL-18 and uric acid in the pathophysiology of vascular occlusion in SCA. Additional studies should be performed to characterize similar prognosis markers and possible therapeutic targets.     

Molecular mechanisms of developmental pathways in neurological disorders: a pharmacological and therapeutic review

Developmental signalling pathways such as Wnt/β-catenin, Notch and Sonic hedgehog play a central role in nearly all the stages of neuronal development. The term ‘embryonic’ might appear to be a misnomer to several people because these pathways are functional during the early stages of embryonic development and adulthood, albeit to a certain degree. Therefore, any aberration in these pathways or their associated components may contribute towards a detrimental outcome in the form of neurological disorders such as Alzheimer''s disease, Parkinson''s disease, amyotrophic lateral sclerosis and stroke. In the last decade, researchers have extensively studied these pathways to decipher disease-related interactions, which can be used as therapeutic targets to improve outcomes in patients with neurological abnormalities. However, a lot remains to be understood in this domain. Nevertheless, there is strong evidence supporting the fact that embryonic signalling is indeed a crucial mechanism as is manifested by its role in driving memory loss, motor impairments and many other processes after brain trauma. In this review, we explore the key roles of three embryonic pathways in modulating a range of homeostatic processes such as maintaining blood–brain barrier integrity, mitochondrial dynamics and neuroinflammation. In addition, we extensively investigated the effect of these pathways in driving the pathophysiology of a range of disorders such as Alzheimer''s, Parkinson''s and diabetic neuropathy. The concluding section of the review is dedicated to neurotherapeutics, wherein we identify and list a range of biological molecules and compounds that have shown enormous potential in improving prognosis in patients with these disorders.     

神经肽Y 对炎症及低氧环境下不同癌细胞活力的影响

目的:研究神经肽Y对炎症反应及其对在低氧培养条件下的不同癌细胞活力的影响,探讨应激影响癌症发展的机制.方法:不同浓度神经肽Y(0,10-12M,10-10M,10-8M)与100 ng/ml LPS共孵育巨噬细胞24h后检测NO的浓度及iNOS表达的变化;不同浓度神经肽Y(0,10-9M,10-8M)刺激低氧培养条件下的肝癌细胞株HepG2与乳腺癌细胞株MCF-7 36h,采用cck-8检测细胞活力变化;不同浓度神经肽Y(0,10-9M,10-8)与LPS共孵育巨噬细胞24 h后取上清液离心,采用上清液培养两种癌细胞,并置于低氧条件下36h,cck-8检测细胞活力.结果:实验结果显示,神经肽Y可以抑制巨噬细胞NO的释放(P＜0.05),并降低iNOS的表达(P＜0.05);单独的神经肽Y对低氧培养条件下两种癌细胞的活力没有明显影响(P＞0.05);但在低氧培养条件中,相比于LPS组的条件培养基,LPS加神经肽Y组的条件培养基可明显增强MCF-7的活力(P＜0.05,P＜0.01),而HepG 2的活力则没有统计学差异.结论:神经肽Y可能通过抑制炎症反应,从而增强乳腺癌细胞MCF-7在低氧环境下的活力.     

Neuropeptide Y,enkephalin and noradrenaline coexist in sympathetic neurons innervating the bovine spleen

Summary The subcellular distribution of noradrenaline (NA), neuropeptide Y (NPY), Met and Leu-enkephalin (ENK), substance P (SP), somatostatin (SOM), and vasoactive intestinal polypeptide (VIP) was investigated in homogenates of bovine splenic nerve. The distribution of noradrenergic peptide-containing nerves in the bovine celiac ganglion, splenic nerve and terminal areas in spleen was studied by indirect immunofluorescence histochemistry using antisera to tyrosine hydroxylase (TH), dopamine--hydroxylase (DBH), NPY, enkephalin peptides, SP, SOM, VIP and peptide HI (PHI).After density gradient centrifugation, high levels of NPY and ENK-like immunoreactivity (LI) were found in high-density gradient fractions, coinciding with the main NA peak. SP, SOM and VIP were found in fractions with a lower density, VIP being also enriched in a heavy fraction; the latter three peptides were present in low concentrations.Immunohistochemistry revealed that staining for NPYLI and ENK-LI partly overlapped that for TH and DBH in celiac ganglia, splenic nerve axons and terminal areas of spleen. Almost all principal ganglion cells were TH- and DBH-immunoreactive. Many were also NPY-immunoreactive, whereas a smaller number were ENK-positive. In the celiac ganglion patches of dense SP-positive networks and some VIP/PHI- and ENK-immunoreactive fibers were seen around cell bodies.The results indicate that NPY and ENK are stored with NA in large dense-cored vesicles in unmyelinated axons of bovine splenic nerve. SP, SOM and VIP appear in different organelles in axon populations separate from sympathetic noradrenergic nerves.     

Two mechanisms involving the autophagic and proteasomal pathways process the metastasis suppressor protein,N-myc downstream regulated gene 1

N-myc downstream regulated gene 1 (NDRG1) is an intriguing metastasis suppressor protein, which plays an important role in suppressing multiple oncogenic signaling pathways. Interestingly, multiple isoforms of NDRG1 have been identified, although the molecular mechanisms involved in their generation remains elusive. Herein, we demonstrate the role of two mechanisms involving autophagic and proteasomal machinery as part of an intricate system to generate different NDRG1 isoforms. Examining multiple pancreatic cancer cell-types using immunoblotting demonstrated three major isoforms of NDRG1 at approximately 41-, 46- and 47-kDa. The top NDRG1 band at 47-kDa was shown to be processed by the proteasome, followed by autophagic metabolism of the middle NDRG1 band at 46-kDa. The role of the proteasomal and autophagic pathways in NDRG1 processing was further confirmed by co-localization analysis of confocal images using PSMD9 and LC3 as classical markers of these respective pathways. All NDRG1 isoforms were demonstrated to be, at least in part, phosphorylated forms of the protein. Inhibition of two well-characterized upstream kinases of NDRG1, namely GSK3β and SGK1, resulted in decreased levels of the top NDRG1 band. Studies demonstrated that inhibition of GSK3β decreased levels of the top 47-kDa NDRG1 band, independent of its kinase activity, and this effect was not mediated via the proteasomal pathway. In contrast, the decrease in the top NDRG1 band at 47-kDa after SGK1 inhibition, was due to suppression of its kinase activity. Overall, these studies elucidated the complex and intricate regulatory pathways involving both proteasomal and autophagic processing of the metastasis suppressor protein, NDRG1.     

Bisphenol A (BPA) and cell signaling pathways

Bisphenol A (BPA; 4,4′-isopropylidenediphenol) is an endocrine disruptor that is used as a material for the production of phenol resins, polyacrylates, polyesters, epoxy resins, and polycarbonate plastics. Endocrine-disruptive or toxic effects of BPA on living organisms through a number of cell signaling pathways have been reported. BPA induces carcinogenesis, reproductive toxicity, abnormal inflammatory or immune response, and developmental disorders of brain or nervous system through various cell signaling pathways. This review considers the literature concerning BPA and its association with cancer-related cell signaling pathways, reproductive toxicity-related cell signaling pathways, inflammatory or immune response-related cell signaling pathways, and brain and nervous system-related cell signaling pathways.     

Aph-1 contributes to the stabilization and trafficking of the gamma-secretase complex through mechanisms involving intermolecular and intramolecular interactions

Gamma-secretase cleaves type I transmembrane proteins, including beta-amyloid precursor protein and Notch, and requires the formation of a protein complex comprised of presenilin, nicastrin, Aph-1, and Pen-2 for its activity. Aph-1 is implicated in the stabilization of this complex, although its precise mechanistic role remains unknown. Substitution of the first glycine within the transmembrane GXXXG motif of Aph-1 causes a loss-of-function phenotype in Caenorhabditis elegans. Here, using an untranslated region-targeted RNA interference/rescue strategy in Drosophila Schneider 2 cells, we show that Aph-1 contributes to the assembly of the gamma-secretase complex by multiple mechanisms involving intermolecular and intramolecular interactions depending on or independent of the conserved glycines. Aph-1 binds to nicastrin forming an early subcomplex independent of the conserved glycines within the endoplasmic reticulum. Certain mutations in the conserved GXXXG motif affect the interaction of the Aph-1.nicastrin subcomplex with presenilin that mediates trafficking of the presenilin.Aph-1.nicastrin tripartite complex to the Golgi. The same mutations decrease the stability of Aph-1 polypeptides themselves, possibly by affecting intramolecular associations through the transmembrane domains. Our data suggest that the proper assembly of the Aph-1.nicastrin subcomplex with presenilin is the prerequisite for the trafficking as well as the enzymatic activity of the gamma-secretase complex and that Aph-1 functions as a stabilizing scaffold in the assembly of this complex.     

Optimization of photosynthesis by multiple metabolic pathways involving interorganelle interactions: resource sharing and ROS maintenance as the bases

The bioenergetic processes of photosynthesis and respiration are mutually beneficial. Their interaction extends to photorespiration, which is linked to optimize photosynthesis. The interplay of these three pathways is facilitated by two major phenomena: sharing of energy/metabolite resources and maintenance of optimal levels of reactive oxygen species (ROS). The resource sharing among different compartments of plant cells is based on the production/utilization of reducing equivalents (NADPH, NADH) and ATP as well as on the metabolite exchange. The responsibility of generating the cellular requirements of ATP and NAD(P)H is mostly by the chloroplasts and mitochondria. In turn, besides the chloroplasts, the mitochondria, cytosol and peroxisomes are common sinks for reduced equivalents. Transporters located in membranes ensure the coordinated movement of metabolites across the cellular compartments. The present review emphasizes the beneficial interactions among photosynthesis, dark respiration and photorespiration, in relation to metabolism of C, N and S. Since the bioenergetic reactions tend to generate ROS, the cells modulate chloroplast and mitochondrial reactions, so as to ensure that the ROS levels do not rise to toxic levels. The patterns of minimization of ROS production and scavenging of excess ROS in intracellular compartments are highlighted. Some of the emerging developments are pointed out, such as model plants, orientation/movement of organelles and metabolomics.     

Adenosine in the central nervous system: release mechanisms and extracellular concentrations

Adenosine has several functions within the CNS that involve an inhibitory tone of neurotransmission and neuroprotective actions in pathological conditions. The understanding of adenosine production and release in the brain is therefore of fundamental importance and has been extensively studied. Conflicting results are often obtained regarding the cellular source of adenosine, the stimulus that induces release and the mechanism for release, in relation to different experimental approaches used to study adenosine production and release. A neuronal origin of adenosine has been demonstrated through electrophysiological approaches showing that neurones can release significant quantities of adenosine, sufficient to activate adenosine receptors and to modulate synaptic functions. Specific actions of adenosine are mediated by different receptor subtypes (A(1), A(2A), A(2B) and A(3)), which are activated by various ranges of adenosine concentrations. Another important issue is the measurement of adenosine concentrations in the extracellular fluid under different conditions in order to know the degree of receptor stimulation and understand adenosine central actions. For this purpose, several experimental approaches have been used both in vivo and in vitro, which provide an estimation of basal adenosine levels in the range of 50-200 nM. The purpose of this review is to describe pathways of adenosine production and metabolism, and to summarize characteristics of adenosine release in the brain in response to different stimuli. Finally, studies performed to evaluate adenosine concentrations under physiological and hypoxic/ischemic conditions will be described to evaluate the degree of adenosine receptor activation.     

白细胞介素-17对体外培养髓核细胞增殖和代谢的影响

目的:探究白细胞介素-17(interleukin-17,IL-17)对体外培养髓核细胞增殖和细胞代谢的影响。方法:髓核细胞取自经核磁共振影像确认需手术的退变椎间盘组织,建立体外培养体系。用2、5、10、15、20 ng/mL IL-17刺激髓核细胞72 h后,MTS法检测细胞增殖情况。用适当浓度IL-17刺激细胞48 h或96 h后,采用实时定量-PCR和免疫印迹方法检测基质和组织代谢相关基因的mRNA和蛋白表达。结果:IL-17刺激可以抑制体外培养髓核细胞的增殖,且15 ng/mL浓度的抑制作用最强。15 ng/mL IL-17刺激髓核细胞后,聚集蛋白聚糖(aggrecan,ACAN)和I型胶原(type I collagen,COL1A1)mRNA表达水平显著下降(P0.05),基质金属蛋白酶(matrix metalloproteinase-3,MMP3)、金属蛋白酶3组织抑制剂(tissue inhibitor of metalloproteinase-3,TIMP3)的mRNA表达水平显著上升(P0.05)。COL2A1 mRNA的表达下降,MMP13、含Ⅰ型血小板结合蛋白基序的结聚蛋白样金属蛋白酶(a disintegrin like and metalloproteinase with thrombospondin typeⅠ motifs-4,ADAMTS4)、ADAMTS5、TIMP1 mRNA的表达上升,但差异均不显著(P0.05)。IL-17刺激48 h时,COL1A1的蛋白水平明显下降(P=0.010),而ADAMTS5的蛋白水平显著上升(P=0.005)。但刺激96h时,COL1A1的蛋白表达下降,ADAMTS5的蛋白表达上升,但无显著差异(P0.05);COL2A1的蛋白表达水平显著下降(P=0.037)。结论:IL-17可抑制体外培养髓核细胞的增殖及代谢,在椎间盘的退变过程中可能发挥了重要的促进作用。     

Cerebral responses to exercise and the influence of heat stress in human fatigue

There are a number of mechanisms thought to be responsible for the onset of fatigue during exercise-induced hyperthermia. A greater understanding of the way in which fatigue develops during exercise could be gleaned from the studies which have examined the maintenance of cerebral blood flow through the process of cerebral autoregulation. Given that cerebral blood flow is a measure of the cerebral haemodynamics, and might reflect a level of brain activation, it is useful to understand the implications of this response during exercise and in the development of fatigue. It is known that cerebral blood flow is significantly altered under certain conditions such as altitude and exacerbated during exercise induced – hyperthermia. In this brief review we consider the processes of cerebral autoregulation predominantly through the measurement of cerebral blood flow and contrast these responses between exercise undertaken in normothermic versus heat stress conditions in order to draw some conclusions about the role cerebral blood flow might play in determining fatigue.     

Thioredoxin and glutaredoxin system proteins—immunolocalization in the rat central nervous system

Background

The oxidoreductases of the thioredoxin (Trx) family of proteins play a major role in the cellular response to oxidative stress. Redox imbalance is a major feature of brain damage. For instance, neuronal damage and glial reaction induced by a hypoxic–ischemic episode is highly related to glutamate excitotoxicity, oxidative stress and mitochondrial dysfunction. Most animal models of hypoxia–ischemia in the central nervous system (CNS) use rats to study the mechanisms involved in neuronal cell death, however, no comprehensive study on the localization of the redox proteins in the rat CNS was available.

Methods

The aim of this work was to study the distribution of the following proteins of the thioredoxin and glutathione/glutaredoxin (Grx) systems in the rat CNS by immunohistochemistry: Trx1, Trx2, TrxR1, TrxR2, Txnip, Grx1, Grx2, Grx3, Grx5, and γ-GCS, peroxiredoxin 1 (Prx1), Prx2, Prx3, Prx4, Prx5, and Prx6. We have focused on areas most sensitive to a hypoxia–ischemic insult: Cerebellum, striatum, hippocampus, spinal cord, substantia nigra, cortex and retina.

Results and conclusions

Previous studies implied that these redox proteins may be distributed in most cell types and regions of the CNS. Here, we have observed several remarkable differences in both abundance and regional distribution that point to a complex interplay and crosstalk between the proteins of this family.

General significance

We think that these data might be helpful to reveal new insights into the role of thiol redox pathways in the pathogenesis of hypoxia–ischemia insults and other disorders of the CNS.This article is part of a Special Issue entitled Human and Murine Redox Protein Atlases.     

Proteomic analysis of cerebrospinal fluid discriminates malignant and nonmalignant disease of the central nervous system and identifies specific protein markers

CNS diseases are often accompanied by changes in the protein composition of cerebrospinal fluid (CSF). SELDI-TOF-MS provides an approach for identifying specific protein markers of disease in biological fluids. We compared the CSF proteomes from patients with neoplastic and reactive/inflammatory CNS diseases to identify potential biomarkers. SELDI-TOF-MS was performed on CSF derived from lumbar puncture of 32 patients, including 10 with CNS malignancies, 12 with inflammatory or reactive conditions, and 10 with unknown CNS disease. Using the SAX-2 (strong anionic exchange) chip, we uncovered three conserved protein peak ranges within each disease category. For neoplastic diseases, we identified conserved peaks at 7.5-8.0 kDa (9/10 samples), 15.1-15.9 kDa (8/10 samples), and 30.0-32.0 kDa (5/10 samples). In reactive/inflammatory diseases, conserved peaks were found at 6.7-7.1 kDa (10/12 samples), 11.5-11.9 kDa (12/12 samples), and 13.3-13.7 kDa (9/12 samples). A protein from the 30.0 to 32.0 kDa peak range found in neoplastic CSF was identified by MALDI analysis as carbonic anhydrase, a protein overexpressed in many malignancies including high-grade gliomas. Similarly, cystatin C was identified in the 13.3-13.7 kDa peak range in non-neoplastic CSF and was most prominent in inflammatory conditions. Our approach provides a rational basis for identifying biomarkers that could be used for detection, diagnosis, and monitoring of CNS diseases.     

Anion channels as central mechanisms for signal transduction in guard cells and putative functions in roots for plant-soil interactions

In higher plants anion channels have recently been suggested to play key roles in controlling cellular functions, including turgor- and osmoregulation, stomatal movements, anion transport, signal transduction and possibly also signal propagation. In guard cells and roots, physiological functions of anion channels have been proposed which will be discussed here. In initial investigations it was proposed that anion channels in the plasma membrane of guard cells provide a prominent control mechanism for stomatal closing. The proposed model suggests that anion channel activation and the resulting anion efflux from guard cells cause membrane depolarization, thereby driving K⁺ efflux through outward-rectifying K⁺ channels required for stomatal closing. This article provides a brief review of new and recent insights into the molecular properties and cell biological functions of anion channels in guard cells. Furthermore, recently implicated putative functions of anion channels in roots during salt stress, xylem loading and Al³⁺ tolerance are addressed.     

Construction and characterization of the HMGB1 mutant as a competitive antagonist to HMGB1 induced cytokines release

Recent studies indicate that the High Mobility Group Box-1 protein (HMGB1) acts as a potent proinflammatory cytokine that contributes to the pathogenesis of diverse inflammatory and infectious disorders. The proinflammatory cytokine activity of HMGB1 has become a therapeutic target. In this study, we cloned the cDNA encoding human HMGB1 and constructed HMGB1 mutants using a one-step opposite direction PCR. The binding of the HMGB1 mutants to THP-1 cell and the cytokine activities of these HMGB1 mutants were observed. Results showed that the HMGB1 Mut (102-105), one of the HMGB1 mutants, in which amino acids 102-105 (FFLF) were replaced with two Glys, significantly decreased the full-length HMGB1 protein induced TNF-α release in human monocyte cultures. The results indicate that we have developed a novel recombinant HMGB1 mutant that competitively antagonizes the proinflammatory activity of HMGB1. This may be of significant importance in providing a new anti-inflammatory strategy for the treatment of severe sepsis and other inflammatory disorders.     

Characterization of the inflammatory and fibrotic response in a mouse model of cardiac pressure overload

Myocardial fibrosis is an integral component of most cardiac pathologic conditions and contributes to the development of both systolic and diastolic dysfunction. Because of the availability of genetically manipulated animals, mouse models are essential for understanding the mechanisms involved in the pathogenesis of cardiac fibrosis. Accordingly, we characterized the inflammatory and fibrotic response in a mouse model of cardiac pressure overload due to transverse aortic constriction (TAC). Following TAC, mouse hearts exhibited induction of chemokines and proinflammatory cytokines, associated with macrophage, but not neutrophil, infiltration. Induction of inflammatory cytokines was followed by a late upregulation of transforming growth factor (TGF)-β isoforms, activation of the Smad2/3 and Smad1/5 pathways, induction of matricellular proteins, and deposition of collagen. Inflammatory activity decreased after 28 days of TAC; at this timepoint established fibrosis was noted, accompanied by ventricular dilation and systolic dysfunction. Late induction of inhibitory mediators, such as TGF-β, may play an essential role in the transition from inflammation to fibrosis by suppressing inflammatory gene synthesis while inducing matrix deposition. Our findings identify molecular mediators and pathways with a potential role in cardiac fibrosis laying the foundations for studies exploring the pathogenesis of fibrotic cardiac remodeling using genetically targeted mice.