Neuropoietic cytokines and activin A differentially regulate the phenotype of cultured sympathetic neurons

Analgesic Effect of Human Placenta Hydrolysate on CFA-Induced Inflammatory Pain in Mice

To evaluate the efficacy of human placenta hydrolysate (HPH) in a mice model of CFA-induced inflammatory pain. TNF-α, IL-1β, and IL-6 are key pro-inflammatory cytokine factors for relieving inflammatory pain. Therefore, this study investigates whether HPH suppresses CFA-induced pain and attenuates the inflammatory process by regulating cytokines. In addition, the relationship between neuropathic pain and HPH was established by staining GFAP and Iba-1 in mice spinal cord tissues. This study was conducted for a total of day 28, and inflammatory pain was induced in mice by injecting CFA into the right paw at day 0 and day 14, respectively. 100 μL of 20% glucose and polydeoxyribonucleotide (PDRN) and 100, 200, and 300 μL of HPH were administered intraperitoneally twice a week. In the CFA-induced group, cold and mechanical allodynia and pro-inflammatory cytokine factors in the spinal cord and plantar tissue were significantly increased. The five groups of drugs evenly reduced pain and gene expression of inflammatory factors, and particularly excellent effects were confirmed in the HPH 200 and 300 groups. Meanwhile, the expression of GFAP and Iba-1 in the spinal cord was increased by CFA administration but decreased by HPH administration, which was confirmed to suppress damage to peripheral ganglia. The present study suggests that HPH attenuates CFA-induced inflammatory pain through inhibition of pro-inflammatory cytokine factors and protection of peripheral nerves.

[Traumatic brain injury as risk factor of Alzheimer's disease and possibilities of pathogenetic therapy]

The article examines the potential role of brain mechanical damage as a trigger for the development of neurodegenerative changes. Attention is paid to dysfunction of the neurovascular unit, and disruption of the functional and compensatory capabilities of blood flow. The importance of microhemorrhages that occur in the acute period of injury and the formation of first focal and then diffuse neuroinflammation is emphasized. The importance of mitochondrial dysfunction was separately determined as a significant factor in increasing the risk of developing Alzheimer's disease (AD) in patients after traumatic brain injury (TBI). In TBI, there is a decrease in the expression of tight junction (TC) proteins of endothelial cells, such as occludin, claudin, JP, which leads to increased permeability of the blood-brain barrier. TBI, provoking endothelial dysfunction, contributes to the development of metabolic disorders of β-amyloid and tau protein, which in turn leads to worsening vascular damage, resulting in a vicious circle that can ultimately lead to the development of AD and dementia. Age-related changes in cerebral arteries, which impair perivascular transport of interstitial fluid, are currently considered as an important part of the «amyloid cascade», especially against the background of genetically mediated disorders of glial membranes associated with defective aquaporin-4 (encoded by the APOE4). Studies in animal models of TBI have revealed an increase in tau protein immunoreactivity and its phosphorylation, which correlates with the severity of injury. A comprehensive analysis of research results shows that the cascade of reactions triggered by TBI includes all the main elements of the pathogenesis of AD: disorders of energy metabolism, microcirculation and clearance of cerebral metabolic products. This leads to a disruption in the metabolism of amyloid protein and its accumulation in brain tissue with the subsequent development of tauopathy. Cerebrolysin, by modulating the permeability of the blood-brain barrier, blocks the development of neuroinflammation, reduces the accumulation of pathological forms of proteins and may be slow down the progression of neurodegeneration.

A review of cytokine-based pathophysiology of Long COVID symptoms

The Long COVID/Post Acute Sequelae of COVID-19 (PASC) group includes patients with initial mild-to-moderate symptoms during the acute phase of the illness, in whom recovery is prolonged, or new symptoms are developed over months. Here, we propose a description of the pathophysiology of the Long COVID presentation based on inflammatory cytokine cascades and the p38 MAP kinase signaling pathways that regulate cytokine production. In this model, the SARS-CoV-2 viral infection is hypothesized to trigger a dysregulated peripheral immune system activation with subsequent cytokine release. Chronic low-grade inflammation leads to dysregulated brain microglia with an exaggerated release of central cytokines, producing neuroinflammation. Immunothrombosis linked to chronic inflammation with microclot formation leads to decreased tissue perfusion and ischemia. Intermittent fatigue, Post Exertional Malaise (PEM), CNS symptoms with "brain fog," arthralgias, paresthesias, dysautonomia, and GI and ophthalmic problems can consequently arise as result of the elevated peripheral and central cytokines. There are abundant similarities between symptoms in Long COVID and myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS). DNA polymorphisms and viral-induced epigenetic changes to cytokine gene expression may lead to chronic inflammation in Long COVID patients, predisposing some to develop autoimmunity, which may be the gateway to ME/CFS.

Associations of Serum Cytokines, Growth Factors, and High-Sensitivity C-Reactive Protein Levels in Patients with Major Depression with and without Type 2 Diabetes Mellitus: An Explanatory Investigation

PURPOSE

We investigated the serum levels of cytokines, including interleukin 1β (IL-β), IL-6, IL-8, IL-10, tumor necrosis factor-alpha (TNF-α), and growth factors, including brain-derived neurotrophic factor, vascular endothelial growth factor, and insulin-like growth factor 1, and their association with major depression in patients with and without type 2 diabetes mellitus. We also investigated the response to antidepressant treatment in both groups.

PATIENTS AND METHODS

Forty-one patients with major depression were recruited at the University Hospital of Occupational and Environmental Health. All patients were diagnosed with major depression using the Diagnostic and Statistical Manual for Mental Disorders, Fifth Edition. Type 2 diabetes mellitus was diagnosed according to the criteria of the Japan Diabetes Society. Six healthy controls with no history of psychiatric or physical diseases were also enrolled. Serum levels of several cytokines, growth factors, and high-sensitivity C-reactive protein (hs-CRP) were measured. The clinical symptoms of patients with major depression were assessed using the Montgomery-Asberg Depression Rating Scale.

RESULTS

Significant differences in cytokines, growth factors, and hs-CRP were observed between the major depression and healthy control groups. Serum TNF-α levels were significantly higher in patients with major depression and type 2 diabetes mellitus than in those without type 2 diabetes mellitus. In the major depression group, serum IL-6 and hs-CRP levels tended to be higher in patients with type 2 diabetes mellitus than in those without. Several correlations among cytokines, growth factors, and hs-CRP were observed in patients with major depression with and without type 2 diabetes mellitus. Responses to pharmacological interventions for major depression did not differ between patients with and without type 2 diabetes mellitus.

CONCLUSION

Serum levels of TNF-α, hs-CRP, and IL-6 were different between patients with major depression with and without type 2 diabetes mellitus. Also, correlations were found between serum levels of cytokines, growth factors, and hs-CRP in patients with major depression. Inflammatory factors, which may be associated with growth factors, may be involved in the pathophysiology of major depression, particularly among patients with comorbid type 2 diabetes mellitus.

Mesenchymal stem cells as a potential therapeutic tool to cure cognitive impairment caused by neuroinflammation

An established contribution of neuroinflammation to multiple brain pathologies has raised the requirement for therapeutic strategies to overcome it in order to prevent age- and disease-dependent cognitive decline. Mesenchymal stem cells (MSCs) produce multiple growth and neurotrophic factors and seem to evade immune rejection due to low expression of major histocompatibility complex class I molecules. Therefore, MSCs are widely used in experiments and clinical trials of regenerative medicine. This review summarizes recent data concerning the optimization of MSC use for therapeutic purposes with the emphasis on the achievements of the last 2 years. Specific attention is paid to extracellular vesicles secreted by MSCs and to the role of α7 nicotinic acetylcholine receptors. The reviewed data demonstrate that MSCs have a significant therapeutic potential in treating neuroinflammation-related cognitive disfunctions including age-related neurodegenerative diseases. The novel data demonstrate that maximal therapeutic effect is being achieved when MSCs penetrate the brain and produce their stimulating factors in situ. Consequently, therapeutic application using MSCs should include measures to facilitate their homing to the brain, support the survival in the brain microenvironment, and stimulate the production of neurotrophic and anti-inflammatory factors. These measures include but are not limited to genetic modification of MSCs and pre-conditioning before transplantation.

Role of IL-6 in the regulation of neuronal development, survival and function

The pleiotropic cytokine interleukin-6 (IL-6) is emerging as a molecule with both beneficial and destructive potentials. It can exert opposing actions triggering either neuron survival after injury or causing neurodegeneration and cell death in neurodegenerative or neuropathic disorders. Importantly, neurons respond differently to IL-6 and this critically depends on their environment and whether they are located in the peripheral or the central nervous system. In addition to its hub regulator role in inflammation, IL-6 is recently emerging as an important regulator of neuron function in health and disease, offering exciting possibilities for more mechanistic insight into the pathogenesis of mental, neurodegenerative and pain disorders and for developing novel therapies for diseases with neuroimmune and neurogenic pathogenic components.

Different Effects of Nicotine and N-Stearoyl-ethanolamine on Episodic Memory and Brain Mitochondria of α7 Nicotinic Acetylcholine Receptor Knockout Mice

Nicotinic acetylcholine receptors of α7 subtype (α7 nAChRs) are involved in regulating neuroinflammation and cognitive functions. Correspondingly, α7-/- mice demonstrate pro-inflammatory phenotype and impaired episodic memory. In addition, nAChRs expressed in mitochondria regulate the release of pro-apoptotic factors like cytochrome c. Here we studied whether the cognitive deficiency of α7-/- mice can be cured by oral consumption of either nicotine or N-stearoylethanolamine (NSE), a lipid possessing anti-inflammatory, cannabimimetic and membrane-stabilizing activity. Mice were examined in Novel Object Recognition behavioral test, their blood, brains and brain mitochondria were tested for the levels of interleukin-6, various nAChR subtypes and cytochrome c released by ELISA. The data presented demonstrate that both substances stimulated the raise of interleukin-6 in the blood and improved episodic memory of α7-/- mice. However, NSE improved, while nicotine worsened the brain mitochondria sustainability to apoptogenic stimuli, as shown by either decreased or increased amounts of cytochrome c released. Both nicotine and NSE up-regulated α4β2 nAChRs in the brain; NSE up-regulated, while nicotine down-regulated α9-containing nAChRs in the brain mitochondria. It is concluded that the level of alternative nAChR subtypes in the brain is critically important for memory and mitochondria sustainability in the absence of α7 nAChRs.

Downstream mRNA Target Analysis in Neonatal Hypoxic-Ischaemic Encephalopathy Identifies Novel Marker of Severe Injury: a Proof of Concept Paper

Human microRNA miR-374a is downregulated in the umbilical cord blood (UCB) of infants with hypoxic-ischaemic encephalopathy (HIE). The downstream targets of this microRNA (miRNA) are unclear, but one putative target is the activin-A receptor type IIb (ACVR2B). ACVR2B is required for activin-A function and previous reports have shown alterations of activin-A levels in neonatal HIE. Our aim was to investigate the expression of the potential downstream targets of miR-374a, activin-A and ACVR2B, at birth in a cohort of full-term infants with perinatal asphyxia (PA) only, and those with PA who developed clinical and electrographic HIE. UCB was drawn and processed immediately after delivery. Levels of serum activin-A were measured using ELISA. mRNA levels of ACVR2B in whole blood were quantified using qRT-PCR. Outcome was assessed at 3 years of age using standardised developmental assessment. In total, 171 infants were enrolled: 88 healthy controls, 56 PA and 27 HIE. A statistically significant elevation of median (IQR) ACVR2B was detected in infants with severe HIE compared to moderate/mild HIE, PA and control groups (3.3 (2.94-3.67) vs. 0.91 (0.55-1.21) vs. 0.88 (0.57-1.38) vs. 0.84 (0.74-1.24), p values = 0.04, 0.027 and 0.025, respectively). Although serum activin-A levels were elevated in infants with severe HIE, this elevation did not reach significance. ACVR2B may be a potential novel marker of HIE severity. This is the first study to examine the relationship between activin-A, its receptor AVCR2B and potentially upstream miRNA miR-374a in a cohort of carefully categorised and phenotyped infants. We have shown that miRNA analysis, combined with downstream target exploration, may yield novel biomarkers for the prediction of HIE severity.

Interleukin-1β and interleukin-6 affect electrophysiological properties of thalamic relay cells

By acknowledging the relation between brain and body in health and disease, inflammatory processes may play a key role in this reciprocal relation. Pro-inflammatory cytokines such as interleukin-1β (IL-1β) and interleukin-6 (IL-6) are some of the agents involved in those processes. What exactly is their role in the CNS however is not that clear so far. To address the question of how pro-inflammatory cytokines may affect information processing at the cellular and molecular levels, relay neurons in the thalamic dorsal lateral geniculate nucleus in mouse brain slices were exposed to those cytokines and studied with the patch-clamp technique. IL-1β promoted hyperpolarization of the resting membrane potential (Vrest), decrease of input resistance (Rin), decrease of Ih rectification, decrease in action potential (AP) threshold and decrease in the number of APs in low threshold calcium spike (LTS) bursts, while IL-6 promoted decrease of Rin and decrease in the number of APs in LTS bursts. Computer simulations provided candidates for ionic conductance affected by those cytokines. Collectively, these findings demonstrate that IL-1β and IL-6 have modulatory effects on electrophysiological properties of thalamic neurons, implying that the thalamic functions may be affected by systemic disorders that present with high levels of those cytokines.

Interleukin-6, a major cytokine in the central nervous system

Interleukin-6 (IL-6) is a cytokine originally identified almost 30 years ago as a B-cell differentiation factor, capable of inducing the maturation of B cells into antibody-producing cells. As with many other cytokines, it was soon realized that IL-6 was not a factor only involved in the immune response, but with many critical roles in major physiological systems including the nervous system. IL-6 is now known to participate in neurogenesis (influencing both neurons and glial cells), and in the response of mature neurons and glial cells in normal conditions and following a wide arrange of injury models. In many respects, IL-6 behaves in a neurotrophin-like fashion, and seemingly makes understandable why the cytokine family that it belongs to is known as neuropoietins. Its expression is affected in several of the main brain diseases, and animal models strongly suggest that IL-6 could have a role in the observed neuropathology and that therefore it is a clear target of strategic therapies.

Regulation of neurokine receptor signaling and trafficking

Leukemia inhibitory factor (LIF) and ciliary neurotrophic factor (CNTF) are neurally active cytokines, or neurokines. LIF signals through a receptor consisting of gp130 and the low affinity LIF receptor (LIFR), while the CNTF receptor consists of gp130, LIFR, and the low affinity CNTF receptor (CNTFR). Ser1044 of the LIFR is phosphorylated by Erk1/2 MAP kinase. Stimulation of neural cells with growth factors which strongly activate Erk1/2 decreases LIF-mediated signal transduction due to increased degradation of the LIFR as a consequence of Erk1/2-dependent phosphorylation of the receptor at Ser1044. The gp130 receptor subunit is phosphorylated, at least in part by calmodulin-dependent protein kinase II, at Ser782, which is adjacent to a dileucine internalization motif. Ser782 appears to negatively regulate cytokine receptor expression, as mutagenesis of Ser782 results in increased gp130 expression and cytokine-induced neuropeptide gene transcription. The LIFR and gp130 are transmembrane proteins, while CNTFR is a peripheral membrane protein attached to the cell surface via a glycosylphosphatidylinositol tail. In unstimulated cells, CNTFR but not LIFR and gp130 is localized to detergent-resistant lipid rafts. Stimulation of cells with CNTFR causes translocation of LIFR and gp130 into the lipid rafts, while stimulation with LIF does not induce receptor translocation, raising the possibility that CNTF could induce different patterns of signaling and/or receptor trafficking than caused by LIF. We used a compartmentalized culture system to examine the mechanisms for retrograde signaling by LIF and CNTF from distal neurites to the cell bodies of mouse sympathetic neurons. Stimulation with neurokines of the distal neurites of sympathetic neurons grown in a compartmentalized culture system resulted in the activation and nuclear translocation of the transcription factor Stat3. Retrograde signaling required Jak kinase activity in the cell body but not the distal neurites, and could be blocked by inhibitors of microtubule but not microfilament function. The results are consistent with a signaling endosomes model in which the ctyokine/receptor complex is transported back to the cell body where Stat3 is activated. While both LIF and CNTF mediate retrograde activation of Stat3, the kinetics for retrograde signaling differ for the two neurokines.

p38α and p38β mitogen-activated protein kinases determine cholinergic transdifferentiation of sympathetic neurons

Although the p38 mitogen-activated protein kinases are active in many neuronal populations in the peripheral and central nervous systems, little is known about the physiological functions of p38 in postmitotic neurons. We report that p38 activity determines in vitro and in vivo the switch from noradrenergic to cholinergic neurotransmission that occurs in sympathetic neurons on exposure to the neuropoietic cytokines CNTF and LIF. This transdifferentiation serves as a model for the plastic mechanisms that enable mature neurons to change some of their central functions without passing through the cell cycle. We demonstrate that in postmitotic neurons, p38 and STAT pathways are concurrently activated by neuropoietic cytokine treatment for at least 12 h overlapping with changes in neurotransmitter marker gene expression. Inhibition of p38 blocks the upregulation of the nuclear matrix protein Satb2 and of cholinergic markers by CNTF without affecting STAT3 phosphorylation. Conversely, overexpression of p38α or β in the absence of cytokines stimulates cholinergic marker expression. The neurotransmitter switch in vitro is impaired in neurons isolated from p38β(-/-) mice. Consistent with these in vitro results, a substantial loss of cells expressing cholinergic properties is observed in vivo in the stellate ganglion of mature mice deficient in the p38β isoform.

Segregation of the classical transmitters norepinephrine and acetylcholine and the neuropeptide Y in sympathetic neurons: modulation by ciliary neurotrophic factor or prolonged growth in culture

Recent evidence has demonstrated that cotransmission from mammalian neurons is not uniquely achieved by costorage and corelease of transmitters and cotransmitters from single varicosities, but also by the concurrent release of mediators segregated in separate synapses of individual neurons. An important question to be addressed is whether neurons show defined patterns of segregation or whether this is a plastic feature. We addressed this question by exploring the segregation pattern of the classical sympathetic transmitters norepinephrine (NE) and acetylcholine (ACh) and the cotransmitter neuropeptide Y (NPY) in sympathetic ganglionic neurons cocultured with cardiac myocytes. Using antibodies against NPY and the vesicular NE and ACh transporters VMAT2 and vesicular acetylcholine transporter (VAChT), we investigated the effect of ciliary neurotrophic factor (CNTF) or long (three weeks) culture periods on the segregation of VMAT2, VAChT, and NPY to separate varicosities. We found that although ganglionic neurons showed cell body coexpression of all the markers examined after three days, VMAT2 was segregated from VAChT in 43% of the VAChT-positive varicosities. In contrast, VMAT2 was only segregated from NPY in 16.3% of the NPY-positive varicosities. Cotransmitter segregation and VAChT expression was potentiated by both CNTF and longer times in culture. We also found two types of varicosities: one was smaller and located further from neuronal somata, and the other was larger, proximal to neuronal somata and had a higher level of segregation. These data demonstrate segregation of classical transmitters in sympathetic neurons and plasticity of neurotransmitter segregation. Finally, we discuss a possible functional correlate of segregation in sympathetic neurons.

The sympathetic neurotransmitter switch depends on the nuclear matrix protein Satb2

Sympathetic neurons can switch their neurotransmitter phenotype from noradrenergic to cholinergic on exposure to neuropoietic cytokines in vitro and in vivo. Here, we provide evidence that this transspecification is regulated by the chromatin architecture protein Satb2. Treatment with the neuropoietic cytokines ciliary neurotrophic factor (CNTF) and leukemia inhibitory factor rapidly and strongly increases Satb2 transcript and protein levels in cultures of rat superior cervical ganglia neurons. Knockdown of endogenous Satb2 by short interfering RNA prevents the upregulation of choline acetyltransferase (Chat) and vesicular acetylcholine transporter (Vacht) by CNTF as well as the loss of norepinephrine transporter (Net). Conversely, overexpression of Satb2 in the noradrenergic sympathetic phenotype results in a marked increase of Chat and Vacht expression and reduced Net mRNA levels in the absence of neuropoietic cytokines. Chromatin immunoprecipitation analysis in primary sympathetic neurons reveals that Satb2 binds to matrix attachment regions (MARs) within the Chat locus. In vivo, in the rat stellate ganglion, Satb2 is expressed exclusively in sudomotor cholinergic neurons innervating the sweat glands and only after establishment of contact between neurons and target. These findings demonstrate a function of the MAR-binding protein Satb2 in growth factor-dependent neurotransmitter plasticity in postmitotic neurons.

Generating diversity: Mechanisms regulating the differentiation of autonomic neuron phenotypes

Sympathetic and parasympathetic postganglionic neurons innervate a wide range of target tissues. The subpopulation of neurons innervating each target tissue can express unique combinations of neurotransmitters, neuropeptides, ion channels and receptors, which together comprise the chemical phenotype of the neurons. The target-specific chemical phenotype shown by autonomic postganglionic neurons arises during development. In this review, we examine the different mechanisms that generate such a diversity of neuronal phenotypes from the pool of apparently homogenous neural crest progenitor cells that form the sympathetic ganglia. There is evidence that the final chemical phenotype of autonomic postganglionic neurons is generated by both signals at the level of the cell body that trigger cell-autonomous programs, as well as signals from the target tissues they innervate.

Measurement of human interleukin 11

This unit describes an ELISA and a cell proliferation assay that can be used, respectively, to measure the protein level or biologic activity of human and murine interleukin 11 (IL-11). The bioassay is based on the ability of IL-11 to support growth of the B9-11 cell line, a subline of B9 that has traditionally been used to measure levels of IL-6. B9-11 is substantially more responsive to IL-11 than the T10 line used in older protocols. This new bioassay therefore provides improved sensitivity, with a detection limit of 20 pg/ml. An alternate procedure is provided that employs neutralizing antibodies in the cell proliferation bioassay to use to ensure that the activity of the desired molecule (IL-11) is being measured in samples containing multiple cytokines. A describes maintenance of B9-11 cells.

The neuroprotective effect of Activin A and B: implication for neurodegenerative diseases

Activin is a member of the transforming growth factor-beta superfamily which comprises a growing list of multifunctional proteins that function as modulators of cell proliferation, differentiation, hormone secretion and neuronal survival. This study examined the neuroprotective effect of both Activin A and B in serum withdrawal and oxidative stress apoptotic cellular models and investigated the expression of pro- and anti-apoptotic proteins, which may account for the mechanism of Activin-induced neuroprotection. Here, we report that recombinant Activin A and B are neuroprotective against serum deprivation- and toxin- [either the parkinsonism-inducing neurotoxin, 6-hydroxydopamine (6-OHDA) or the peroxynitrite donor, 3-(4-morpholinyl) sydnonimine hydrochloride (SIN-1)] induced neuronal death in human SH-SY5Y neuroblastoma cells. Furthermore, we demonstrate for the first time that transient transfection with Activin betaA or betaB significantly protect SH-SY5Y and rat pheochromocytoma PC12 cells against serum withdrawal-induced apoptosis. This survival effect is mediated by the Bcl-2 family members and involves inhibition of caspase-3 activation; reduction of cleaved poly-ADP ribose polymerase and phosphorylated H2A.X protein levels and elevation of tyrosine hydroxylase expression. These results indicate that both Activin-A and -B share the potential to induce neuroprotective activity and thus may have positive impact on aging and neurodegenerative diseases to retard the accelerated rate of neuronal degeneration.

Neurotransmitter phenotype-specific expression changes in developing sympathetic neurons

During late developmental phases individual sympathetic neurons undergo a switch from noradrenergic to cholinergic neurotransmission. This phenomenon of plasticity depends on target-derived signals in vivo and is triggered by neurotrophic factors in neuronal cultures. To analyze genome-wide expression differences between the two transmitter phenotypes we employed DNA microarrays. RNA expression profiles were obtained from chick paravertebral sympathetic ganglia, treated with neurotrophin 3, glial cell line-derived neurotrophic factor or ciliary neurotrophic factor, all of which stimulate cholinergic differentiation. Results were compared with the effect of nerve growth factor, which functions as a pro-noradrenergic stimulus. The gene set common to all three comparisons defined the noradrenergic and cholinergic synexpression groups. Several functional categories, such as signal transduction, G-protein-coupled signaling, cation transport, neurogenesis and synaptic transmission, were enriched in these groups. Experiments based on the prediction that some of the identified genes play a role in the neurotransmitter switch identified bone morphogenetic protein signaling as an inhibitor of cholinergic differentiation.

Molecular cloning, sequencing and phylogenetic analysis of inflammatory cytokines of swamp type buffalo contrasting with other bubaline breeds

The current research concerned in the cloning, sequencing and phylogenetic analysis of inflammatory cytokine (IL-1alpha, IL-1beta, IL-6 and TNF-alpha) genes from swamp buffalo and two bubaline breeds, CB (cross between swamp and riverine type buffalo) and the Bulgarian Murrah buffalo. Multiple sequence comparison showed a high homology between the bubaline breeds, which ranged from 99.3% to 100.0% similarity, whereas from 98.6% to 99.0% compared to cattle. The phylogenetic analysis had confirmed and justified the degree of relationship between these bubaline species and their distinctness to each other by the bootstrap value (%) generated. These findings were discussed with particular attention to the diversity of the inflammatory cytokine proteins within closely related species. The result of this study concluded that a small difference in the cytokine structures might be the reason behind or has a contributory factor on the previous reports about the existence of disease resistance. However, in-depth study is necessary to further qualify these findings.

Activin A In Brain Injury

Activin A is a growth factor composed of two betaA subunits belonging to the transforming growth factor beta (TGF-beta) superfamily of dimeric proteins. The biological activity of activin A is mediated by two different types of receptors, the type I (ARI and ARIB) and the type II receptors (ARII and ARIIB), and by two activin-binding proteins, follistatin and follistatin-related gene. These factors bind to activin A and thereby inhibit its biological effects. Activin A, its receptors, and binding proteins are widely distributed throughout the brain. Studies employing models of acute brain injury strongly implicate enhanced activin A expression as a common response to acute neuronal damage of various origins. Hypoxic/ischemic injury, mechanical irritation, and chemical damage of brain evoke a strong upregulation of activin A. Subsequent experimental studies have shown that activin A has a beneficial role to neuronal recovery and that, by activating different pathways, activin A has robust neuroprotective activities. Because activin A induction occurs early after brain injury, its measurement may provide a potential biochemical index of the presence, location, and extent of brain injury. This approach may also facilitate the diagnosis of subclinical lesions at stages when monitoring procedures are unable to detect brain lesion and furthermore establish a prognosis.

Cysteinyl leukotriene upregulates IL-11 expression in allergic airway disease of mice

BACKGROUND

Chronic airway inflammation and airway remodeling are important features of bronchial asthma. IL-11 is one of the important mediators involved in the process of airway inflammation and remodeling. Cysteinyl leukotrienes (cysLTs) play roles in recruitment of inflammatory cells, airway smooth muscle contraction, vascular leakage, increased mucus secretion, decreased mucociliary clearance, and airway fibrosis.

OBJECTIVE

An aim of the present study was to determine the effect of the cysLTs on the regulation of IL-11 expression.

METHODS

We used a C57BL/6 mouse model of allergic airway disease and murine tracheal epithelial cells to examine the effects of cysLTs on the regulation of IL-11 expression.

RESULTS

Our present study with an ovalbumin-induced murine model of allergic airway disease revealed that levels of leukotriene C(4) (LTC(4)) in bronchoalveolar lavage fluids were increased and that administration of montelukast or pranlukast reduced the increased levels of LTC(4); the increased expression of IL-11 protein and mRNA in lung tissues; airway inflammation, bronchial hyperresponsiveness; the increased levels of TGF-beta(1), IL-4, and IL-13 in bronchoalveolar lavage fluids and lung tissues; and airway fibrosis. In addition, LTC(4) stimulates epithelial cells to produce IL-11. Our results also showed that cysLT type 1 receptor antagonists downregulated the activity of a transcription factor, nuclear factor kappaB, and BAY 11-7085 substantially reduced the increased levels of IL-11 after ovalbumin inhalation.

CONCLUSION

These results suggest that cysLTs regulate the IL-11 expression in allergic airway disease.

CLINICAL IMPLICATIONS

These findings provide one of the molecular mechanisms for the effects of cysLTs on airway inflammation and fibrosis in allergic airway diseases.

Leukemia inhibitory factor is a key regulator of astrocytic, microglial and neuronal responses in a low-dose pilocarpine injury model

Insult to the central nervous system (CNS) induces many changes, including altered neurotransmitter expression, activation of astrocytes and microglia, neurogenesis and cell death. Cytokines and growth factors are candidates to be involved in astrocyte and microglial activation, and the up-regulation of glial fibrillary acidic protein (GFAP) is associated with brain damage. One of these candidates is leukemia inhibitory factor (LIF), a pro-inflammatory cytokine that is induced in astrocytes by brain damage or seizure. LIF also regulates expression of both neuropeptide Y (NPY) and galanin following peripheral nerve injury. To test the hypothesis that LIF regulates astrocyte, microglial and neuropeptide responses to a mild insult, we used a low-dose pilocarpine model to induce a brief seizure in LIF knock-out (KO) mice. Compared to wild type mice, the LIF KO mouse displays reduced astrocyte and microglial activation in the hippocampus. In addition, LIF KO mice display dramatically altered NPY, but not galanin, expression in response to injury. Thus, LIF is required for normal glial responses to brain damage, and, as in the periphery, LIF regulates NPY expression in the CNS.

Cocaine- and amphetamine-related transcript peptide and somatostatin in rat intracardiac ganglia

The distribution of somatostatin and cocaine and amphetamine-regulated transcript (CART) was investigated in rat intracardiac ganglia. Somatostatin immunoreactivity was only present in nerve terminals, always colocalised with choline acetyltransferase immunoreactivity, surrounding approximately 10% of intracardiac neurons. Somatostatin-immunoreactive terminals particularly targeted intrinsic cardiac neurons that were immunoreactive for calbindin. Somatostatin was also present in sympathetic cholinergic neurons in the stellate ganglia, but could not be detected in neurons of the nucleus ambiguus and dorsal motor nucleus of the vagus in the brainstem. CART immunoreactivity was present in 46% of intracardiac neuronal somata, including those that expressed either NOS or calbindin immunoreactivity but was never present in terminals forming pericellular baskets around intracardiac neurons. CART immunoreactivity was absent from sympathetic cell bodies in the stellate ganglia, but was present in nerve terminals around sympathetic neurons. Based on the results of this study, additional chemical diversity was identified among elements of the rat cardiac nervous system that may define neural pathways of different function.

Growth and survival signals controlling sympathetic nervous system development

The precise coordination of the many events in nervous system development is absolutely critical for the correct establishment of functional circuits. The postganglionic sympathetic neuron has been an amenable model for studying peripheral nervous system formation. Factors that control several developmental events, including multiple stages of axon extension, neuron survival and death, dendritogenesis, synaptogenesis, and establishment of functional diversity, have been identified in this neuron type. This knowledge allows us to integrate the various intricate processes involved in the formation of a functional sympathetic nervous system and thereby create a paradigm for understanding neuronal development in general.

Activin mRNA induced during amygdala kindling shows a spatiotemporal progression that tracks the spread of seizures

The progressive development of seizures in rats by amygdala kindling, which models temporal lobe epilepsy, allows the study of molecular regulators of enduring synaptic changes. Neurotrophins play important roles in synaptic plasticity and neuroprotection. Activin, a member of the transforming growth factor-beta superfamily of growth and differentiation factors, has recently been added to the list of candidate synaptic regulators. We mapped the induction of activin betaA mRNA in amygdala and cortex at several stages of seizure development. Strong induction, measured 2 hours after the first stage 2 (partial) seizure, appeared in neurons of the ipsilateral amygdala (confined to the lateral, basal, and posterior cortical nuclei) and insular, piriform, orbital, and infralimbic cortices. Activin betaA mRNA induction, after the first stage 5 (generalized) seizure, had spread to the contralateral amygdala (same nuclear distribution) and cortex, and the induced labeling covered much of the convexity of neocortex as well as piriform, perirhinal, and entorhinal cortices in a nearly bilaterally symmetrical pattern. This pattern had filled in by the sixth stage 5 seizure. Induced labeling in cortical neurons was confined mainly to layer II. A similar temporal and spatial pattern of increased mRNA expression of brain-derived neurotrophic factor (BDNF) was found in the amygdala and cortex. Activin betaA and BDNF expression patterns were similar at 1, 2, and 6 hours after the last seizure, subsiding at 24 hours; in contrast, c-fos mRNA induction appeared only at 1 hour throughout cortex and then subsided. In double-label studies, activin betaA mRNA-positive neurons were also BDNF mRNA positive, and they did not colocalize with GAD67 mRNA (a marker of gamma-aminobutyric acidergic neurons). The data suggest that activin and BDNF transcriptional activities accurately mark excitatory neurons participating in seizure-induced synaptic alterations and may contribute to the enduring changes that underlie the kindled state.

Role of immediate early gene expression in cortical morphogenesis and plasticity

During the development of the central nervous system, there is a fundamental requirement for synaptic activity in transforming immature neuronal connections into organized functional circuits (Katz 1996). The molecular mechanisms underlying activity-dependent adaptive changes in neurons are believed to involve regulated cascades of gene expression. Immediate early genes (IEGs) comprise the initial cascade of gene expression responsible for initiating the process of stimulus-induced adaptive change, and were identified initially as transcription factors that were regulated in brain by excitatory synaptic activity. More recently, a class of neuronal immediate early genes has been identified that encodes growth factors, signaling molecules, extracellular matrix and adhesion proteins, and cytoskeletal proteins that are rapidly and transiently expressed in response to glutamatergic neurotransmission. This review focuses on the neuronal immediate early gene (nIEG) response, in particular, the class of "effector" immediate early gene proteins that may directly modify neuronal and synaptic function.

Leukemia inhibitory factor is a key signal for injury-induced neurogenesis in the adult mouse olfactory epithelium

The mammalian olfactory epithelium (OE) is composed of primary olfactory sensory neurons (OSNs) that are renewed throughout adulthood by local, restricted neuronal progenitor cells. The molecular signals that control this neurogenesis in vivo are unknown. Using olfactory bulb ablation (OBX) in adult mice to trigger synchronous mitotic stimulation of neuronal progenitors in the OE, we show the in vivo involvement of a cytokine in the cellular events leading to the regeneration of the OE. We find that, of many potential mitogenic signals, only leukemia inhibitory factor (LIF) is induced before the onset of neuronal progenitor proliferation. The rise in LIF mRNA expression peaks at 8 hr after OBX, and in situ RT-PCR and immunocytochemistry indicate that LIF is upregulated, in part, in the injured neurons themselves. This rise in LIF is necessary for injury-induced neurogenesis, as OBX in the LIF knock-out mouse fails to stimulate cell proliferation in the OE. Moreover, delivery of exogenous LIF to the intact adult OE using an adenoviral vector stimulates BrdU labeling in the apical OE. Taken together, these results suggest that injured OSNs release LIF as a stimulus to initiate their own replacement.

Leukemia inhibitory factor is a key signal for injury-induced neurogenesis in the adult mouse olfactory epithelium

The mammalian olfactory epithelium (OE) is composed of primary olfactory sensory neurons (OSNs) that are renewed throughout adulthood by local, restricted neuronal progenitor cells. The molecular signals that control this neurogenesis in vivo are unknown. Using olfactory bulb ablation (OBX) in adult mice to trigger synchronous mitotic stimulation of neuronal progenitors in the OE, we show the in vivo involvement of a cytokine in the cellular events leading to the regeneration of the OE. We find that, of many potential mitogenic signals, only leukemia inhibitory factor (LIF) is induced before the onset of neuronal progenitor proliferation. The rise in LIF mRNA expression peaks at 8 hr after OBX, and in situ RT-PCR and immunocytochemistry indicate that LIF is upregulated, in part, in the injured neurons themselves. This rise in LIF is necessary for injury-induced neurogenesis, as OBX in the LIF knock-out mouse fails to stimulate cell proliferation in the OE. Moreover, delivery of exogenous LIF to the intact adult OE using an adenoviral vector stimulates BrdU labeling in the apical OE. Taken together, these results suggest that injured OSNs release LIF as a stimulus to initiate their own replacement.

Involvement of activin and inhibin in the regulation of food and water intake in the rat

The expression of activin and inhibin has been demonstrated in the hypothalamus, but their physiological roles in the brain remain to be elucidated. In the present study, involvement of activin and inhibin in the regulation of food and water intake was examined. Male rats were deprived of food or water for 12 and 60 hr, and mRNA levels of activin/inhibin alpha, betaA and betaB subunits in the hypothalamus were estimated by RT-PCR. Gene expression of alpha subunit transiently decreased at 12 hr of food deprivation, while it did not change during water deprivation. Food and water deprivation for 60 hr increased mRNA levels of betaA and betaB subunits, respectively. These results indicated that gene expression of each subunit was independently regulated. Injection of activin A (0.5 and 4.0 microg) into the third ventricle decreased food intake. Water intake was suppressed by 4.0 microg, but not 0.5 microg, of activin A. Intracerebroventricular injection of inhibin A (0.5 and 4.0 microg) decreased water intake in a dose dependent manner without affecting food intake, suggesting that inhibin could act independently of activin. Taken together, it is suggested that activin and inhibin take part in the central regulation of nutrient and fluid balance, though further study is needed to determine precise molecular species involved.

Independent roles of SOCS-3 and SHP-2 in the regulation of neuronal gene expression by leukemia inhibitory factor

The neurokine leukemia inhibitory factor (LIF) initiates signaling through heterodimerization of the low affinity LIF receptor (LIFR) and gp130. Tyrosine 759 of gp130 is required for the negative regulation of LIF-mediated signaling by both the protein tyrosine phosphatase SHP-2 and the suppressor of cytokine signaling-3 (SOCS-3). We find that SOCS-3 is expressed in the neuronal cell lines SN56 and IMR32 and negatively regulates LIF-stimulated neuronal gene expression. Studies using antisense oligonucleotides targeted to SHP-2 or SOCS-3 indicate that either protein can negatively regulate LIF-stimulated neuronal gene expression independently of the other. Mutagenesis of the cytoplasmic domain of gp130 demonstrates that the four signal transducer and activators of transcription (STAT) binding sites within gp130 are necessary for the induction of vasoactive intestinal peptide (VIP) and choline acetyltransferase (ChAT) reporter genes, with the sites surrounding tyrosines 905 and 915 (Y905 and Y915) being most important in gp130-mediated reporter gene expression. While there are four STAT binding sites within gp130, only those surrounding Y905 and Y915 can mediate STAT1 activation; these results indicate that STAT1 may be essential for normal gp130-stimulated VIP and ChAT expression. Additionally, the negative regulation of signaling mediated by Y759 of gp130 is dependent upon intact STAT sites within the receptor. This indicates that STAT signaling is necessary for LIF- and CNTF-stimulated VIP and ChAT expression and Y759 of gp130 mediates the activities of SHP-2 and SOCS-3, which act to negatively regulate STAT activity.

Differential response of neuronal cells to a fusion protein of ciliary neurotrophic factor/soluble CNTF-receptor and leukemia inhibitory factor

Ciliary neurotrophic factor (CNTF) displays neurotrophic activities on motor neurons and neural cell populations both in vivo and in vitro. On target cells lacking intrinsic expression of specific receptor alpha subunits cytokines of the IL-6 family only act in the presence of their specific agonistic soluble receptors. Here, we report the construction and expression of a CNTF/soluble CNTF-receptor (sCNTF-R) fusion protein (Hyper-CNTF) with enhanced biological activity on cells expressing gp130 and leukemia inhibitory factor receptor (LIF-R), but not membrane-bound CNTF-R. At the cDNA level, the C-terminus of the extracellular domain of human CNTF-R (amino acids 1-346) was linked via a single glycine residue to the N-terminus of human CNTF (amino acids 1-186). Recombinant Hyper-CNTF protein was expressed in COS-7 cells. Hyper-CNTF efficiently induced dose-dependent STAT3 phosphorylation and proliferation of BAF-3 cells stably transfected with gp130 and LIF-R cDNAs. While on BAF3/gp130/LIF-R cells, Hyper-CNTF and LIF exhibited similar biological responses, the activity of Hyper-CNTF on pheochromocytoma cells (PC12 cells) was quite distinct from that of LIF. In contrast to LIF, Hyper-CNTF stimulated neurite outgrowth of PC12 cells in a time- and dose-dependent manner correlating with the ability to phosphorylate MAP kinases. These data indicate that although LIF and Hyper-CNTF use the same heterodimeric receptor complex of gp130 and LIFR, only Hyper-CNTF induces neuronal differentiation. The therapeutic potential of Hyper-CNTF as a superagonistic neurotrophin is discussed.

CNTF is specifically expressed in developing rat pineal gland and eyes

Ciliary neurotrophic factor (CNTF) attracts considerable attention because it supports survival and differentiation of various types of neurons and glial cells in vitro. Although CNTF functions as a moderate neurotrophic factor in mature motor neurons, its role in embryonic development remains unknown. Here, we found a specific CNTF expression in the rat pineal gland and eyes during embryonic development. In vitro, neonatal rat pineal extract including CNTF supported the survival of neonatal sympathetic neurons, which innervate pineal glands immediately after birth.

Upregulation of acetylcholine synthesis by bone morphogenetic protein 9 in a murine septal cell line

Previous studies showed that bone morphogenetic protein 9 (BMP-9) induces the expression of choline acetyltransferase and the vesicular acetylcholine (ACh) transporter, and upregulates ACh synthesis in cultured primary neurons from embryonic mouse septum [I. López-Coviella, B. Berse, R. Krauss, R.S. Thies, J.K. Blusztajn, Induction and maintenance of the neuronal cholinergic phenotype in the central nervous system by BMP-9. Science 289 (2000) 313-316]. In the present studies we investigated the effects of BMP-9 on ACh synthesis in the cholinergic mouse SN56T17 septal cell line. BMP-9 increased ACh synthesis in these cells up to 2.5-fold in a time- and dose-dependent, saturable manner. The maximal effect of BMP-9 was observed after a 3-day treatment and the median effective concentration of BMP-9 was 0.5 ng/ml. These data show that SN56T17 cells are a useful model for studies of the effects of BMPs on the cholinergic phenotype.

Cerebrospinal fluid contains biologically active bone morphogenetic protein-7

Bone morphogenetic proteins (BMPs) regulate the development and function of many types of neurons. However, little is known of the actual concentrations of BMPs in the various parts of the brain. In this study, we considered the possibility that BMPs might be present in cerebrospinal fluid (CSF). Western blot analysis of normal adult bovine CSF revealed the presence of dimeric and monomeric forms of BMP-7, and the concentration of this molecule was found to be approximately 12 ng/ml in a radioimmunoassay. Since BMP-7 is known to induce dendritic growth in rat sympathetic neurons, this was used as a bioassay to examine the biological activity of the BMP-7 present in CSF. Addition of normal bovine CSF to cultures of sympathetic neurons produced a dose-dependent increase in dendritic growth and the magnitude of this response approximated that obtained with maximally effective concentrations of exogenous BMP-7. Moreover, CSF-induced dendritic growth was inhibited by follistatin, a protein that can sequester BMPs, and by either of two monoclonal antibodies that react with BMP-7. These results show that, unlike most other neurotrophic factors, BMP-7 is a constituent of normal CSF and is present at concentrations sufficient to elicit a near maximal biological response.

Neurotrophic factors and gene therapy in spinal cord injury

Although it was once thought that the central nervous system (CNS) of mammals was incapable of substantial recovery from injury, it is now clear that the adult CNS remains responsive to various substances that can promote cell survival and stimulate axonal growth. Among these substances are growth factors, including the neurotrophins and cytokines, and growth-supportive cells such as Schwann cells, olfactory ensheathing glia, and stem cells. We review the effects of these substances on promoting axonal growth after spinal cord injury, placing particular emphasis on the genetic delivery of nervous system growth factors to specific sites of injury as a means of promoting axonal growth and, in limited instances, functional recovery.

Inhibin, activin, and follistatin in human fetal pituitary and gonadal physiology

BACKGROUND

Activin has been previously demonstrated to directly stimulate the synthesis of gonadotropin-releasing hormone (GnRH) receptors and to increase follicle-stimulating hormone (FSH) secretion in nonhuman pituitary cell cultures (PCCs). Currently, knowledge of the physiological role of these peptides in primates is still far from complete. Moreover, several results in macaque monkeys failed to support an unequivocal role for inhibin in FSH suppression. Whereas the bioactivity of inhibin and activin has been demonstrated in rat PCCs, no data exist on human pituitary response to these peptides either in vivo or in vitro.

METHODS

We studied the secretion of FSH and luteinizing hormone (LH) by dispersed human fetal pituitary cells from midtrimester abortions in response to recombinant human (rh-) activin-A, inhibin-A, and other secretagogues. After mechanical and enzymatic dispersion, the human fetal pituitary cells were cultured on an extracellular matrixlike-material-coated 24-well plate. After 3 days' incubation in serum-containing medium, the PCCs were washed and preincubated for 90 min in serum-free medium and incubated with activin-A, inhibin-A, TGF-beta, follistatin, sex steroids, and GnRH, in quadruplicate.

RESULTS

Activin-A was a potent secretagogue for FSH secretion. GnRH (20 ng/ml) was more potent than rh-activin-A for LH secretion. Nevertheless, a significant increase in LH secretion into the medium was brought about by rh-activin-A. Inhibin decreased FSH and LH secretion, but the LH response to inhibin was less prominent than that of FSH. GnRH opposed the inhibitory effect of inhibin on LH secretion. In dynamic, short-term, repetitive exposure of fetal pituitary fragments to rh-activin-A (superfusion), we could not receive a similar increase in LH and FSH as in static incubations, as opposed to a short GnRH exposure. In addition to their endocrine, paracrine, and autocrine effects, and in addition to their role as possible markers, the TGF-beta superfamily members may affect embryogenesis and possibly immunomodulation of the embryo and fetus. The role of activin and inhibin as intragonadal regulators is hypothesized. The pro-alphaC inhibin precursor may act as an FSH receptor antagonist.

CONCLUSIONS

Human fetal PCCs express the previously reported physiologic responses to activin and inhibin generated in nonhuman experiments on gonadotropin secretion in vitro and may serve as a physiologic model for studying human gonadotrope responses to the TGF-beta family of peptides.

Induction of cholinergic function in cultured sympathetic neurons by periosteal cells: cellular mechanisms

Periosteum, the connective tissue surrounding bone, alters the transmitter properties of its sympathetic innervation during development in vivo and after transplantation. Initial noradrenergic properties are downregulated and the innervation acquires cholinergic and peptidergic properties. To elucidate the cellular mechanisms responsible, sympathetic neurons were cultured with primary periosteal cells or osteoblast cell lines. Both primary cells and an immature osteoblast cell line, MC3T3-E1, induced choline acetyltransferase (ChAT) activity. In contrast, lines representing marrow stromal cells or mature osteoblasts did not increase ChAT. Growth of periosteal cells with sympathetic neurons in transwell cultures that prevent direct contact between the neurons and periosteal cells or addition of periosteal cell-conditioned medium to neuron cultures induced ChAT, indicating that periosteal cells release a soluble cholinergic inducing factor. Antibodies against LIFRbeta, a receptor subunit shared by neuropoietic cytokines, prevented ChAT induction in periosteal cell/neuron cocultures, suggesting that a member of this family is responsible. ChAT activity was increased in neurons grown with periosteal cells or conditioned medium from mice lacking either leukemia inhibitory factor (LIF) or LIF and ciliary neurotrophic factor (CNTF). These results provide evidence that periosteal cells influence sympathetic neuron phenotype by releasing a soluble cholinergic factor that is neither LIF nor CNTF but signals via LIFRbeta.

The PTPmu protein-tyrosine phosphatase binds and recruits the scaffolding protein RACK1 to cell-cell contacts

PTPmu, an Ig superfamily receptor protein-tyrosine phosphatase, promotes cell-cell adhesion and interacts with the cadherin-catenin complex. The signaling pathway downstream of PTPmu is unknown; therefore, we used a yeast two-hybrid screen to identify additional PTPmu interacting proteins. The membrane-proximal catalytic domain of PTPmu was used as bait. Sequencing of two positive clones identified the scaffolding protein RACK1 (receptor for activated protein C kinase) as a PTPmu interacting protein. We demonstrate that RACK1 interacts with PTPmu when co-expressed in a recombinant baculovirus expression system. RACK1 is known to bind to the src protein-tyrosine kinase. This study demonstrates that PTPmu association with RACK1 is disrupted by the presence of constituitively active src. RACK1 is thought to be a scaffolding protein that recruits proteins to the plasma membrane via an unknown mechanism. We have shown that the association of endogenous PTPmu and RACK1 in a lung cell line is increased at high cell density. We also demonstrate that the recruitment of RACK1 to both the plasma membrane and cell-cell contact sites is dependent upon the presence of the PTP mu protein in these cells. Therefore, PTPmu may be one of the proteins that recruits RACK1 to points of cell-cell contact, which may be important for PTPmu-dependent signaling in response to cell-cell adhesion.

Activin type II receptors in embryonic dorsal root ganglion neurons of the chicken

Activin induces neuropeptide expression in chicken ciliary ganglion neurons. To determine if activin might also influence neuropeptide expression in developing sensory neurons, we examined whether type II activin receptors are expressed during embryonic development of the chicken dorsal root ganglia (DRG), and also examined the effects of activin on neuropeptide expression in cultured DRG neurons. Using reverse transcription polymerase chain reaction (rtPCR), we detected mRNAs for both the activin receptors type IIA (ActRIIA) and type IIB (ActRIIB) in DRG from embryonic day 7 through posthatch day 1. With in situ hybridization, we found that morphologically identifiable neurons express mRNAs for both ActRIIA and ActRIIB. With developmental age, a subset of neurons that hybridizes more intensely with riboprobes to these receptor mRNAs becomes evident. A similar pattern of expression is observed with immunocytochemical staining using antisera against activin type II receptors. To examine whether embryonic DRG cells respond to activin we treated dissociated cultures of DRG with activin A and assessed the expression of vasoactive intestinal peptide (VIP) and calcitonin gene related peptide (CGRP) mRNAs using semiquantitative rtPCR. Activin treatment results in an increase in VIP mRNA, but does not affect CGRP mRNA levels. These observations indicate that neurons in the embryonic chicken DRG can respond to activin and suggest that activin has the potential to play a role in the development and function of DRG sensory neurons.

Effect of recombinant human interleukin-11 on motilin and substance P release in normal and inflamed rabbits

Recombinant human interleukin-11 (rhIL-11) normalizes depressed smooth muscle tension generation towards motilin and substance P (SP) in rabbits with colitis. The aim of this paper was to evaluate the effect of rhIL-11 treatment on motilin and SP release which could have an effect on the contractility changes. Rabbits received 4, 40, 72 or 720 microg/kg rhIL-11 s.c. or saline, 1 h later a continuous s.c. administration of rhIL-11 was started with or without the induction of colitis (135 mg/kg TNBS) for 5 days. Motilin and SP levels were measured by RIA, motilin mRNA expression by RT-PCR. TNBS-colitis did not affect plasma motilin levels but increased the motilin content of the duodenal mucosa 1.7-fold. rhIL-11 treatment dose-dependently increased plasma motilin levels (720 microg/kg day: 3.5-fold) and the motilin content of the duodenal mucosa (720 microg/kg day: 3.0-fold). The effects of rhIL-11 were similar in normal rabbits and were accompanied by an increased motilin mRNA expression. TNBS-colitis decreased plasma SP levels 2.7-fold and the SP content in the colonic muscle layer 7.1-fold. The decrease in the muscle layer, but not in the plasma, was normalized by rhIL-11 treatment. In normal rabbits, rhIL-11 caused a decrease in plasma SP levels, but had no effect on the tissue content of SP. In conclusion, treatment of inflamed or normal rabbits with rhIL-11 increases plasma and tissue levels of motilin in the duodenal mucosa via an increased expression of motilin in the endocrine cells and induces the release of SP from extrinsic neurons. These changes do not explain the beneficial effect of rhIL-11 on the lowered contractility in inflamed rabbits although a change in balance of neuropeptides may influence gastro-intestinal inflammation.

Recognition sequences and structural elements contribute to shedding susceptibility of membrane proteins

Although regulated ectodomain shedding affects a large panel of structurally and functionally unrelated proteins, little is known about the mechanisms controlling this process. Despite a lack of sequence similarities around cleavage sites, most proteins are shed in response to the stimulation of protein kinase C by phorbol esters. The signal-transducing receptor subunit gp130 is not a substrate of the regulated shedding machinery. We generated several chimaeric proteins of gp130 and the proteins tumour necrosis factor alpha (TNF-alpha), transforming growth factor alpha (TGF-alpha) and interleukin 6 receptor (IL-6R), which are known to be subject to shedding. By exchanging small peptide sequences of gp130 for cleavage-site peptides of TNF-alpha, TGF-alpha and IL-6R we showed that these short sequences conferred susceptibility to spontaneous and phorbol-ester-induced shedding of gp130. Importantly, these chimaeric gp130 proteins were functional, as shown by the phosphorylation of gp130 and the activation of signal transduction and activators of transcription 3 ('STAT3') on stimulation with cytokine. To investigate minimal requirements for shedding, truncated cleavage-site peptides of IL-6R were inserted into gp130. The resulting chimaeras were susceptible to shedding and showed the same cleavage pattern as observed in the chimaeras containing the complete IL-6R cleavage site. Surprisingly, we could also generate cleavable chimaeras by exchanging the juxtamembrane sequence of gp130 for the corresponding region of leukaemia inhibitory factor ('LIF') receptor, a protein that like gp130 is not subject to regulated or spontaneous shedding. Thus it seems that there is no minimal consensus shedding sequence. We speculate that structural changes allow the access of the protease to a membrane-proximal region, leading to shedding of the protein.

Temporal expression of mRNAs for neuropoietic cytokines, interleukin-11 (IL-11), oncostatin M (OSM), cardiotrophin-1 (CT-1) and their receptors (IL-11Ralpha and OSMRbeta) in peripheral nerve injury

The mRNA expression pattern of the neuropoietic cytokines, interleukin-11 (IL-11), oncostatin M (OSM) and cardiotrophin-1 (CT-1), and their receptor components (IL-11Ralpha and OSMRbeta) was examined in peripheral nerves on two different types of injury, crush and transection. The IL-11 mRNA increased after nerve damage and immediately returned to control levels. The OSM mRNA expression increased rapidly after nerve injury and relatively high expressions were maintained for at least 14 days. The CT-1 mRNA was not expressed in any time before and after the injury. Interestingly, IL-11Ralpha was expressed in the intact nerve and decreased after injury. The expression of OSMRbeta increased slightly after the injury. Moreover, temporal mRNA expression pattern of these neuropoietic cytokines and receptors was similar between the crushed and transected models. Each neuropoietic cytokine of IL-11, OSM and CT-1 has its own specific temporal mRNA expression pattern, which is also different from those of ciliary neuro-trophic factor (CNTF), leukemia inhibitory factor (LIF) and interleukin-6 (IL-6). These results suggest that all neuropoietic cytokines have distinctive functions in nerve degeneration and repair process in response to peripheral nerve injury.