Expression profiling and Ingenuity biological function analyses of interleukin-6- versus nerve growth factor-stimulated PC12 cells

A systematic review of the neuroprotective role and biomarker potential of GDF15 in neurodegeneration

Neurodegeneration is characteristically multifaceted, with limited therapeutic options. One of the chief pathophysiological mechanisms driving these conditions is neuroinflammation, prompting increasing clinical interest in immunomodulatory agents. Growth differentiation factor 15 (GDF15; previously also called macrophage inhibitory cytokine-1 or MIC-1), an anti-inflammatory cytokine with established neurotrophic properties, has emerged as a promising therapeutic agent in recent decades. However, methodological challenges and the delayed identification of its specific receptor GFRAL have hindered research progress. This review systematically examines literature about GDF15 in neurodegenerative diseases and neurotrauma. The evidence collated in this review indicates that GDF15 expression is upregulated in response to neurodegenerative pathophysiology and increasing its levels in preclinical models typically improves outcomes. Key knowledge gaps are addressed for future investigations to foster a more comprehensive understanding of the neuroprotective effects elicited by GDF15.

Genetic association of GJA8 with long-segment Hirschsprung's disease in southern Chinese children

Background

Hirschsprung's disease (HSCR) is a complex congenital neurodevelopmental disorder affecting colons caused by both genetic and environmental factors. Although several genes have been identified as contributing factors in HSCR, the pathogenesis is still largely unclear, especially for the low prevalent long-segment HSCR (L-HSCR). Gap junction protein alpha 8 (GJA8) is involved in several physiological processes and has been implicated in several diseases. However, the relationship between GJA8 single nucleotide polymorphism (SNP) rs17160783 and HSCR in the southern Chinese population remains unknown. The study aimed to explore the association of genetic variants in GJA8 and HSCR susceptibility in southern Chinese.

Methods

SNP rs17160783 A>G in GJA8 was genotyped by TaqMan SNP Genotyping Assay in all samples, which included 1,329 HSCR children (cases) and 1,473 healthy children (controls). Odds ratio (OR) and 95% confidence interval (CI) were used to evaluate the association of GJA8 polymorphisms with HSCR susceptibility. The GTEx database and transcription factor binding site (TFBS) prediction were used to analyze the potential regulatory function of rs17160783.

Results

Genetic association analysis illustrated that rs17160783 could increase the risk of L-HSCR (Padj=0.04, ORadj =1.48, 95% CI: 1.02-2.14). We also found that GJA8 expression was increased in HSCR and neurodevelopmentally impaired animal models. External epigenetic data revealed that GJA8 rs17160783 may have the potential to regulate the expression of the GJA8, possibly by altering the binding of transcription factors for GJA8, and consequently impacting the PI3K-Akt signaling pathway during the enteric nervous system (ENS) development.

Conclusions

Our results suggested that rs17160783 might play a regulatory role in GJA8 expression and increase the susceptibility of L-HSCR in children from southern China.

Transplantation of autologous bone marrow-derived mononuclear cells into cerebrospinal fluid in a canine model of spinal cord injury

Introduction

Spinal cord injury (SCI) is associated with severe dysfunction of nervous tissue, and repair via the transplantation of bone marrow-derived mononuclear cells (BM-MNCs) into cerebrospinal fluid yields promising results. It is essential to understand the underlying mechanisms; therefore, this study aimed to evaluate the regenerative potential of autologous BM-MNC transplantation in a canine model of acute SCI.

Methods

Six dogs were included in this study, and SCI was induced using an epidural balloon catheter between L2 and L3, particularly in the area of the anterior longitudinal ligament. BM-MNC transplantation was performed, and T2-weighted magnetic resonance imaging (MRI) was conducted at specific time points (i.e., immediately after inducing SCI and at 1, 2, and 4 weeks after inducing SCI); moreover, the expression of growth-associated protein 43 (GAP-43) was evaluated.

Results

MRI revealed that the signal intensity reduced over time in both BM-MNC-treated and control groups. However, the BM-MNC-treated group exhibited a significantly faster reduction than the control group during the early stages of SCI induction (BM-MNC-treated group: 4.82 ± 0.135 cm [day 0], 1.71 ± 0.134 cm [1 week], 1.37 ± 0.036 cm [2 weeks], 1.21 cm [4 weeks]; control group: 4.96 ± 0.211 cm [day 0], 2.49 ± 0.570 cm [1 week], 1.56 ± 0.045 cm [2 weeks], 1.32 cm [4 weeks]). During the early stages of treatment, GAP-43 was significantly expressed at the proximal end of the injured spinal cord in the BM-MSC-treated group, whereas it was scarcely expressed in the control group.

Conclusions

In SCI, transplanted BM-MNCs can activate the expression of GAP-43, which is involved in axonal elongation (an important process in spinal cord regeneration). Thus, cell therapy with BM-MNCs can provide favorable outcomes in terms of better regenerative capabilities compared with other therapies.

Glucocorticoids attenuate interleukin-6-induced c-Fos and Egr1 expression and impair neuritogenesis in PC12 cells

Interleukin-6 (IL-6) is a cytokine primarily known for immune regulation. There is also growing evidence that IL-6 triggers neurogenesis and impacts neural development, both life-long occurring processes that can be impaired by early-life and adult stress. Stress induces the release of glucocorticoids by activation of the hypothalamic-pituitary-adrenal (HPA) axis. On the cellular level, glucocorticoids act via the ubiquitously expressed glucocorticoid receptor. Thus, we aimed to elucidate whether glucocorticoids affect IL-6-induced neural development. Here, we show that IL-6 signalling induces neurite outgrowth in adrenal pheochromocytoma PC12 cells in a mitogen-activated protein kinase (MAPK) pathway-dependent manner, since neurite outgrowth was diminished upon Mek-inhibitor treatment. Using quantitative biochemical approaches, such as qRT-PCR analysis of Hyper-IL-6 treated PC12 cells, we show that neurite outgrowth induced by IL-6 signalling is accompanied by early and transient MAPK-dependent mRNA expression of immediate early genes coding for proteins such as early growth response protein 1 (Egr1) and c-Fos. This correlates with reduced proliferation and prolonged G0/G1 cell cycle arrest as determined by monitoring the cellular DNA content using flow cytometry. These results indicate for IL-6 signalling-induced neural differentiation. Interestingly, the glucocorticoid Dexamethasone impairs early IL-6 signalling-induced mRNA expression of c-Fos and Egr1 and restrains neurite outgrowth. Impaired Egr1 and c-Fos expression in neural development is implicated in the aetiology of neuropathologies. Thus, it appears likely that stress-induced release of glucocorticoids, as well as therapeutically administered glucocorticoids, contribute to the development of neuropathologies by reducing the expression of Egr1 and c-Fos, and by restraining IL-6-dependent neural differentiation.

Bottom up proteomics identifies neuronal differentiation pathway networks activated by cathepsin inhibition treatment in neuroblastoma cells that are enhanced by concurrent 13-cis retinoic acid treatment

Neuroblastoma is the second most common pediatric cancer involving the peripheral nervous system in which stage IVS metastatic tumors regress due to spontaneous differentiation. 13-cis retinoic acid (13-cis RA) is currently used in the clinic for its differentiation effects and although it improves outcomes, relapse is seen in half of high-risk patients. Combinatorial therapies have been shown to be more effective in oncotherapy and since cathepsin inhibition reduces tumor growth, we explored the potential of coupling 13-cis RA with a cathepsin inhibitor (K777) to enhance therapeutic efficacy against neuroblastoma. Shotgun proteomics was used to identify proteins affected by K777 and dual (13-cis RA/K777) treatment in neuroblastoma SK-N-SH cells. Cathepsin inhibition was more effective in increasing proteins involved in neuronal differentiation and neurite outgrowth than 13-cis RA alone, but the combination of both treatments enhanced the neuronal differentiation effect. SIGNIFICANCE: As neuroblastoma can spontaneously differentiate, determining which proteins are involved in differentiation can guide development of more accurate diagnostic markers and more effective treatments. In this study, we established a differentiation proteomic map of SK-N-SH cells treated with a cathepsin inhibitor (K777) and K777/13-cis RA (dual). Bioinformatic analysis revealed these treatments enhanced neuronal differentiation and axonogenesis pathways. The most affected proteins in these pathways may become valuable biomarkers of efficacy of drugs designed to enhance differentiation of neuroblastoma [1].

Pretreatment Cancer-Related Cognitive Impairment-Mechanisms and Outlook

Cognitive changes are common in patients with active cancer and during its remission. This has largely been blamed on therapy-related toxicities and diagnosis-related stress, with little attention paid to the biological impact of cancer itself. A plethora of clinical studies demonstrates that cancer patients experience cognitive impairment during and after treatment. However, recent studies show that a significant portion of patients with non-central nervous system (CNS) tumors experience cognitive decline prior to treatment, suggesting a role for tumor-derived factors in modulating cognition and behavior. Cancer-related cognitive impairment (CRCI) negatively impacts a patient’s quality of life, reduces occupational and social functioning, and increases morbidity and mortality. Furthermore, patients with cancer cachexia frequently experience a stark neurocognitive decline, suggesting peripheral tumors exert an enduring toll on the brain during this chronic paraneoplastic syndrome. However, the scarcity of research on cognitive impairment in non-CNS cancers makes it difficult to isolate psychosocial, genetic, behavioral, and pathophysiological factors in CRCI. Furthermore, clinical models of CRCI are frequently confounded by complicated drug regimens that inherently affect neurocognitive processes. The severity of CRCI varies considerably amongst patients and highlights its multifactorial nature. Untangling the biological aspects of CRCI from genetic, psychosocial, and behavioral factors is non-trivial, yet vital in understanding the pathogenesis of CRCI and discovering means for therapeutic intervention. Recent evidence demonstrating the ability of peripheral tumors to alter CNS pathways in murine models is compelling, and it allows researchers to isolate the underlying biological mechanisms from the confounding psychosocial stressors found in the clinic. This review summarizes the state of the science of CRCI independent of treatment and focuses on biological mechanisms in which peripheral cancers modulate the CNS.

Activation of TRKA receptor elicits mastocytosis in mice and is involved in the development of resistance to KIT-targeted therapy

The neurotrophins (NTs) play a key role in neuronal survival and maintenance. The TRK (tropomyosin-related kinase) tyrosine kinase receptors (TRKA, TRKB, TRKC) are high affinity receptors for NTs. There is increasing data demonstrating an important role of the TRK family in cancer initiation and progression. NTs have been known for many years to promote chemotaxis, maturation, and survival of mast cells. However, the role of NT signaling in the pathogenesis of mastocytosis is not well understood. In this study, we demonstrate that activation of TRKA by its ligand nerve growth factor (NGF) is potent to trigger a disease in mice with striking similarities to human systemic mastocytosis (SM). Moreover, activation of TRKA by NGF strongly rescues KIT inhibition-induced cell death of mast cell lines and primary mast cells from patients with SM, and this rescue effect can be efficiently blocked by entrectinib (a new pan TRK specific inhibitor). HMC-1 mast cell leukemia cells that are resistant to KIT inhibition induced by TRKA activation show reactivation of MAPK/ERK (extracellular signal-regulated kinase) and strong upregulation of early growth response 3 (EGR3), suggesting an important role of MAPK-EGR3 axis in the development of resistance to KIT inhibition. Targeting both TRK and KIT significantly prolongs survival of mice xenotransplanted with HMC-1 cells compared with targeting KIT alone. Thus, these data strongly suggest that TRKA signaling can improve neoplastic mast cell fitness. This might explain at least in part why treatment with KIT inhibitors alone so far has been disappointing in most published clinical trials for mastocytosis. Our data suggest that targeting both KIT and TRKs might improve efficacy of molecular therapy in SM with KIT mutations.

Low-Dose Pulsatile Interleukin-6 As a Treatment Option for Diabetic Peripheral Neuropathy

Diabetic peripheral neuropathy (DPN) remains one of the most common and serious complications of diabetes. Currently, pharmacological agents are limited to treating the pain associated with DPN, and do not address the underlying pathological mechanisms driving nerve damage, thus leaving a significant unmet medical need. Interestingly, research conducted using exercise as a treatment for DPN has revealed interleukin-6 (IL-6) signaling to be associated with many positive benefits such as enhanced blood flow and lipid metabolism, decreased chronic inflammation, and peripheral nerve fiber regeneration. IL-6, once known solely as a pro-inflammatory cytokine, is now understood to signal as a multifunctional cytokine, capable of eliciting both pro- and anti-inflammatory responses in a context-dependent fashion. IL-6 released from muscle in response to exercise signals as a myokine and as such has a unique kinetic profile, whereby levels are transiently elevated up to 100-fold and return to baseline levels within 4 h. Importantly, this kinetic profile is in stark contrast to long-term IL-6 elevation that is associated with pro-inflammatory states. Given exercise induces IL-6 myokine signaling, and exercise has been shown to elicit numerous beneficial effects for the treatment of DPN, a causal link has been suggested. Here, we discuss both the clinical and preclinical literature related to the application of IL-6 as a treatment strategy for DPN. In addition, we discuss how IL-6 may directly modulate Schwann and nerve cells to explore a mechanistic understanding of how this treatment elicits a neuroprotective and/or regenerative response. Collectively, studies suggest that IL-6, when administered in a low-dose pulsatile strategy to mimic the body's natural response to exercise, may prove to be an effective treatment for the protection and/or restoration of peripheral nerve function in DPN. This review highlights the studies supporting this assertion and provides rationale for continued investigation of IL-6 for the treatment of DPN.

Topical fentanyl stimulates healing of ischemic wounds in diabetic rats

BACKGROUND

Topically applied opioids promote angiogenesis and healing of ischemic wounds in rats. We examined if topical fentanyl stimulates wound healing in diabetic rats by stimulating growth-promoting signaling, angiogenesis, lymphangiogenesis and nerve regeneration.

METHODS

We used Zucker diabetic fatty rats that develop obesity and diabetes on a high fat diet due to a mutation in the Leptin receptor. Fentanyl blended with hydrocream was applied topically on ischemic wounds twice daily, and wound closure was analyzed regularly. Wound histology was analyzed by hematoxylin and eosin staining. Angiogenesis, lymphangiogenesis, nerve fibers and phospho-platelet derived growth factor receptor-β (PDGFR-β) were visualized by CD31-, lymphatic vessel endothelium-1, protein gene product 9.5- and anti-phospho PDGFR-β-immunoreactivity, respectively. Nitric oxide synthase (NOS) and PDGFR-β signaling were analyzed using Western immunoblotting.

RESULTS

Fentanyl significantly promoted wound closure as compared to phosphate-buffered saline (PBS). Histology scores were significantly higher in fentanyl-treated wounds, indicative of increased granulation tissue formation, reduced edema and inflammation, and increased matrix deposition. Fentanyl treatment resulted in increased wound angiogenesis, lymphatic vasculature, nerve fibers, nitric oxide, NOS and PDGFR-β signaling as compared to PBS. Phospho-PDGFR-β co-localized with CD31 co-staining for vasculature.

CONCLUSIONS

Topically applied fentanyl promotes closure of ischemic wounds in diabetic rats. Increased angiogenesis, lymphangiogenesis, peripheral nerve regeneration, NO and PDGFR-β signaling are associated with fentanyl-induced tissue remodeling and wound healing.

Isoform-specific and protein kinase C-mediated regulation of CTP:phosphoethanolamine cytidylyltransferase phosphorylation

CTP:phosphoethanolamine cytidylyltransferase (Pcyt2) is the main regulatory enzyme for de novo biosynthesis of phosphatidylethanolamine by the CDP-ethanolamine pathway. There are two isoforms of Pcyt2, -α and -β; however, very little is known about their specific roles in this important metabolic pathway. We previously demonstrated increased phosphatidylethanolamine biosynthesis subsequent to elevated activity and phosphorylation of Pcyt2α and -β in MCF-7 breast cancer cells grown under conditions of serum deficiency. Mass spectroscopy analyses of Pcyt2 provided evidence for isoform-specific as well as shared phosphorylations. Pcyt2β was specifically phosphorylated at the end of the first cytidylyltransferase domain. Pcyt2α was phosphorylated within the α-specific motif that is spliced out in Pcyt2β and on two PKC consensus serine residues, Ser-215 and Ser-223. Single and double mutations of PKC consensus sites reduced Pcyt2α phosphorylation, activity, and phosphatidylethanolamine synthesis by 50-90%. The phosphorylation and activity of endogenous Pcyt2 were dramatically increased with phorbol esters and reduced by specific PKC inhibitors. In vitro translated Pcyt2α was phosphorylated by PKCα, PKCβI, and PKCβII. Pcyt2α Ser-215 was also directly phosphorylated with PKCα. Mapping of the Pcyt2α- and -β-phosphorylated sites to the solved structure of a human Pcyt2β showed that they clustered within and flanking the central linker region that connects the two catalytic domains and is a novel regulatory segment not present in other cytidylyltransferases. This study is the first to demonstrate differences in phosphorylation between Pcyt2 isoforms and to uncover the role of the PKC-regulated phosphorylation.

Brain-derived neurotrophic factor serum levels and genotype: association with depression during interferon-α treatment

Depression has been associated with inflammation, and inflammation may both influence and interact with growth factors such as brain-derived neurotrophic factor (BDNF). Both the functional Val66Met BDNF polymorphism (rs6265) and BDNF levels have been associated with depression. It is thus plausible that decreased BDNF could mediate and/or moderate cytokine-induced depression. We therefore prospectively employed the Beck Depression Inventory-II (BDI-II), the Hospital Anxiety and Depression Scale (HADS), and the Montgomery-Asberg Depression Rating Scale (MADRS) in 124 initially euthymic patients during treatment with interferon-alpha (IFN-α), assessing serum BDNF and rs6265. Using mixed-effect repeated measures, lower pretreatment BDNF was associated with higher depression symptoms during IFN-α treatment (F144,17.2=6.8; P<0.0001). However, although the Met allele was associated with lower BDNF levels (F1,83.0=5.0; P=0.03), it was only associated with increased MADRS scores (F4,8.9=20.3; P<0.001), and not the BDI-II or HADS. An exploratory comparison of individual BDI-II items indicated that the Met allele was associated with suicidal ideation, sadness, and worthlessness, but not neurovegetative symptoms. Conversely, the serotonin transporter promoter polymorphism (5-HTTLPR) short allele was associated with neurovegetative symptoms such as insomnia, poor appetite and fatigue, but not sadness, worthlessness, or suicidal ideation. IFN-α therapy further lowered BDNF serum levels (F4,37.7=5.0; P=0.003), but this decrease occurred regardless of depression development. The findings thus do not support the hypothesis that decreasing BDNF is the primary pathway by which IFN-α worsens depression. Nonetheless, the results support the hypothesis that BDNF levels influence resiliency against developing inflammatory cytokine-associated depression, and specifically to a subset of symptoms distinct from those influenced by 5-HTTLPR.

An autocrine neuronal interleukin-6 loop mediates chloride accumulation and NKCC1 phosphorylation in axotomized sensory neurons

The cation-chloride cotransporter NKCC1 plays a fundamental role in the central and peripheral nervous systems by setting the value of intracellular chloride concentration. Following peripheral nerve injury, NKCC1 phosphorylation-induced chloride accumulation contributes to neurite regrowth of sensory neurons. However, the molecules and signaling pathways that regulate NKCC1 activity remain to be identified. Functional analysis of cotransporter activity revealed that inhibition of endogenously produced cytokine interleukin-6 (IL-6), with anti-mouse IL-6 antibody or in IL-6⁻/⁻ mice, prevented chloride accumulation in a subset of axotomized neurons. Nerve injury upregulated the transcript and protein levels of IL-6 receptor in myelinated, TrkB-positive sensory neurons of murine lumbar dorsal root ganglia. Expression of phospho-NKCC1 was observed mainly in sensory neurons expressing IL-6 receptor and was absent from IL-6⁻/⁻ dorsal root ganglia. The use of IL-6 receptor blocking-function antibody or soluble IL-6 receptor, together with pharmacological inhibition of Janus kinase, confirmed the role of neuronal IL-6 signaling in chloride accumulation and neurite growth of a subset of axotomized sensory neurons. Cell-specific expression of interleukin-6 receptor under pathophysiological conditions is therefore a cellular response by which IL-6 contributes to nerve regeneration through neuronal NKCC1 phosphorylation and chloride accumulation.

Expression of pancreatitis-associated protein after traumatic brain injury: a mechanism potentially contributing to neuroprotection in human brain

Neuronal cell death after severe traumatic brain injury (TBI) is caused by a complex interplay of pathological mechanisms including excitotoxicity, oxidative stress, mitochondrial dysfunction, extensive neuroinflammation, and ischemia-reperfusion injury. Pancreatitis-associated protein I (PAP I/reg2) was reported to be a survival factor for peripheral neurons, particularly sensory and motor neurons. In rat brains, by experimental TBI as well as by kainic acid induced brain seizure, PAP I and PAP III were found to be up-regulated in central neurons. In this study, we performed immunohistochemical staining in postmortem human brain from patients who died after severe TBI to demonstrate PAP expression on protein level in cerebellar Purkinje cells, pyramidal and granular neurons in cerebral cortex, and cortical neurons in the fore- and mid-brain. In primary cultures of rat brain cortical, hippocampal, and cerebellar neurons, we found neuroprotective effects for PAP I on H(2)O(2)-induced oxidative stress. Moreover, serum K(+)-deprivation induces apoptotic cell death in 55% of cerebellar granule neurons (CGN), whereas upon treatment with PAP I only 32% of CGN are apoptotic. Using Western blot analyses, we compared protein phosphorylation in neuronal signaling pathways activated by PAP I versus Interleukin-6 (IL-6). We found a rapid activation of Akt-kinase phosphorylation by PAP I with a peak at 15 min, whereas IL-6 induces Akt-phosphorylation lasting longer than 30 min. Phosphorylation of MAP-42/44 kinases is stimulated in a comparable fashion. Both, IL-6 and PAP I increase phosphorylation of NFκB for activation of gene transcription, whereas only IL-6 recruits STAT3 phosphorylation, indicating that STAT3 is not a target of PAP I transcription activation in brain neurons. Application of the Akt-inhibitor Wortmanin reveals only a partial inhibition of PAP I-dependent protection of CGN from H(2)O(2)-induced oxidative stress. Based on our findings, we suggest that PAP I is a long lasting neurotrophic signal for central neurons. The neuroprotective effects parallel those that have been described for effects of PAP I in ciliary neurotrophic factor (CNTF)-mediated survival of sensory and motor neurons. PAP I may act in autocrine and/or paracrine fashion and thus may contribute to endogenous protective mechanisms relevant under harmful conditions like oxidative stress, brain injury, or neurodegeneration.

Identification of novel target genes of nerve growth factor (NGF) in human mastocytoma cell line (HMC-1 (V560G c-Kit)) by transcriptome analysis

Background

Nerve growth factor (NGF) is a potent growth factor that plays a key role in neuronal cell differentiation and may also play a role in hematopoietic differentiation. It has been shown that NGF induced synergistic action for the colony formation of CD34 positive hematopoietic progenitor cells treated with macrophage-colony stimulating factor (M-CSF or CSF-1), or stem cell factor (SCF). However, the exact role of NGF in hematopoietic system is unclear. It is also not clear whether NGF mediated signals in hematopoietic cells are identical to those in neuronal cells.

Results

To study the signal transduction pathways induced by NGF treatment in hematopoietic cells, we utilized the mastocytoma cell line HMC-1(V560G c-Kit) which expresses the NGF receptor, tropomyosin-receptor-kinase (Trk)A, as well as the constitutively activated SCF receptor, V560G c-Kit, which can be inhibited completely by treatment with the potent tyrosine kinase inhibitor imatinib mesylate (imatinib). NGF rescues HMC-1(V560G c-Kit) cells from imatinib mediated cell death and promotes proliferation. To examine the NGF mediated proliferation and survival in these cells, we compared the NGF mediated upregulated genes (30 and 120 min after stimulation) to the downregulated genes by imatinib treatment (downregulation of c-Kit activity for 4 h) by transcriptome analysis. The following conclusions can be drawn from the microarray data: Firstly, gene expression profiling reveals 50% overlap of genes induced by NGF-TrkA with genes expressed downstream of V560G c-Kit. Secondly, NGF treatment does not enhance expression of genes involved in immune related functions that were down regulated by imatinib treatment. Thirdly, more than 55% of common upregulated genes are involved in cell proliferation and survival. Fourthly, we found Kruppel-like factor (KLF) 2 and Smad family member 7 (SMAD7) as the NGF mediated novel downstream genes in hematopoietic cells. Finally, the downregulation of KLF2 gene enhanced imatinib induced apoptosis.

Conclusion

NGF does not induce genes which are involved in immune related functions, but induces proliferation and survival signals in HMC-1(V560G c-Kit) cells. Furthermore, the current data provide novel candidate genes, KLF2 and SMAD7 which are induced by NGF/TrkA activation in hematopoietic cells. Since the depletion of KLF2 causes enhanced apoptosis of HMC-1(V560G c-Kit), KLF2 may play a role in the NGF mediated survival signal.

Interleukin-6, a mental cytokine

Almost a quarter of a century ago, interleukin-6 (IL-6) was discovered as an inflammatory cytokine involved in B cell differentiation. Today, IL-6 is recognized to be a highly versatile cytokine, with pleiotropic actions not only in immune cells, but also in other cell types, such as cells of the central nervous system (CNS). The first evidence implicating IL-6 in brain-related processes originated from its dysregulated expression in several neurological disorders such as multiple sclerosis, Alzheimer's disease and Parkinson's disease. In addition, IL-6 was shown to be involved in multiple physiological CNS processes such as neuron homeostasis, astrogliogenesis and neuronal differentiation. The molecular mechanisms underlying IL-6 functions in the brain have only recently started to emerge. In this review, an overview of the latest discoveries concerning the actions of IL-6 in the nervous system is provided. The central position of IL-6 in the neuroinflammatory reaction pattern, and more specifically, the role of IL-6 in specific neurodegenerative processes, which accompany Alzheimer's disease, multiple sclerosis and excitotoxicity, are discussed. It is evident that IL-6 has a dichotomic action in the CNS, displaying neurotrophic properties on the one hand, and detrimental actions on the other. This is in agreement with its central role in neuroinflammation, which evolved as a beneficial process, aimed at maintaining tissue homeostasis, but which can become malignant when exaggerated. In this perspective, it is not surprising that 'well-meant' actions of IL-6 are often causing harm instead of leading to recovery.

Pancreatitis-associated protein-I and pancreatitis-associated protein-III expression in a rat model of kainic acid-induced seizure

The pancreatitis-associated protein (PAP) family (also known as the regenerating gene (Reg) family) is a group of 16 kDa secretory proteins structurally classified as the calcium dependent-type lectin superfamily. Some PAP family members are expressed in neurons following peripheral nerve injury and traumatic brain injury. To determine whether PAP family members are expressed in non-traumatic brain injury, expressions were analyzed following kainic acid (KA)-induced seizure. PAP-I (also known as Reg2 in rat and RegIII-beta in mouse) and pancreatitis associated protein-III (PAP-III; RegIII-gamma in mouse) messenger ribonucleic acid (mRNA) was transiently expressed in some restricted areas, such as the hippocampus and parahippocampal area; expression was observed immediately at a maximal level 1 day after seizure. Expression disappeared within 3 days after seizure. In situ hybridization (ISH) and immunohistochemistry revealed neuronal PAP-I and PAP-III expression in the hippocampal dentate gyrus, perirhinal and entorhinal cortices, and the posterior cortical nucleus of the amygdala. The number of PAP-III mRNA-positive neurons was significantly greater than PAP-I mRNA-positive neurons. The majority of positive neurons co-localized with c-Jun, but not with glutamic acid decarboxylase (GAD). These results may suggest that PAP-I and PAP-III induction in non-GABAergic neurons would protect neurons against damage following seizure.

Cytokine interactions with adrenal medullary chromaffin cells

It is generally accepted that a bi-directional or reciprocal interaction occurs between the immune and neuroendocrine systems, and that this relationship is important for the appropriate physiological functioning of both systems. Similarly, an imbalance in this relationship may contribute to a number of pathologies, most notably those relating to stress. The aim of this article is to consider the interaction of cytokines with the adrenal medulla, a potentially important player in this relationship. The chromaffin cells of the adrenal medulla release catecholamines and a range of biologically active peptides in response to a wide variety of stress-related signals. A growing body of evidence indicates that this stress response is influenced by, and in turn has influence upon, immune signalling. This brief review will focus primarily on the best-described adrenal medullary active cytokines, namely interferon-α, interleukin-6, interleukin-1α/β and tumour necrosis factor-α. In each case, three key issues will be addressed: the physiologically relevant source of the cytokine; the intracellular signalling events arising from activation of its receptor and finally the cellular consequences of such activation in terms of modulation of gene expression and the secretory output of the chromaffin cells.

Enhancement of ATRA-induced differentiation of neuroblastoma cells with LOX/COX inhibitors: an expression profiling study

BACKGROUND

We performed expression profiling of two neuroblastoma cell lines, SK-N-BE(2) and SH-SY5Y, after combined treatment with all-trans retinoic acid (ATRA) and inhibitors of lipoxygenases (LOX) and cyclooxygenases (COX). This study is a continuation of our previous work confirming the possibility of enhancing ATRA-induced cell differentiation in these cell lines by the application of LOX/COX inhibitors and brings more detailed information concerning the mechanisms of the enhancement of ATRA-induced differentiation of neuroblastoma cells.

METHODS

Caffeic acid, as an inhibitor of 5-lipoxygenase, and celecoxib, as an inhibitor on cyclooxygenase-2, were used in this study. Expression profiling was performed using Human Cancer Oligo GEArray membranes that cover 440 cancer-related genes.

RESULTS

Cluster analyses of the changes in gene expression showed the concentration-dependent increase in genes known to be involved in the process of retinoid-induced neuronal differentiation, especially in cytoskeleton remodeling. These changes were detected in both cell lines, and they were independent of the type of specific inhibitors, suggesting a common mechanism of ATRA-induced differentiation enhancement. Furthermore, we also found overexpression of some genes in the same cell line (SK-N-BE(2) or SH-SY5Y) after combined treatment with both ATRA and CA, or ATRA and CX. Finally, we also detected that gene expression was changed after treatment with the same inhibitor (CA or CX) in combination with ATRA in both cell lines.

CONCLUSIONS

Obtained results confirmed our initial hypothesis of the common mechanism of enhancement in ATRA-induced cell differentiation via inhibition of arachidonic acid metabolic pathway.