IL-6 regulates MCP-1, ICAM-1 and IL-6 expression in human myoblasts

The inflammatory reaction in autoimmune polymyositis and rejection of transplanted myoblasts is characterized by mononuclear cell infiltration. In other settings monocytes are locally recruited by an IL-6-induced IL-8-to-MCP-1 switch. IL-6, upon binding to soluble gp80 (sIL-6R), can interact with membrane-bound ubiquitously expressed gp130 and activate virtually all cells (transsignaling). We found that human myoblasts could use transsignaling to produce IL-6, MCP-1 and ICAM-1; the addition of sIL-6R, binding to IL-1beta-induced IL-6, greatly increases IL-6 production. These in vitro data support the hypothesis that locally secreted IL-6 can target monocyte chemotaxis and leukocytes trafficking through an IL-6, MCP-1 and ICAM-1 modulation.     

Positive affective style covaries with stimulated IL-6 and IL-10 production in a middle-aged community sample

An emerging literature indicates that dispositional positive affect (PA) may play a protective role in health and render individuals less susceptible to inflammatory diseases. In this regard, it has been suggested that PA is associated with diminished activation of innate immune pathways. To explore this possibility, we examined relationships between trait positive emotional style, as assessed by the Positive and Negative Affect Schedule, and monocyte-derived lipopolysaccharide-induced production of the pro- and anti-inflammatory cytokines, interleukin (IL)-6, IL-1beta, TNF-alpha, and IL-10, among 146 healthy adults aged 30-54. After controlling for demographic factors and other covariates (age, gender, race, body mass index and white blood cell count), hierarchical regression analyses revealed an inverse association between trait PA and stimulated production of IL-6 (DeltaR(2)=.03, b=-.18, p <.04) and IL-10 (DeltaR(2)=.09; b =-.32, p <.01), with the latter association obtained only in men. No association was observed between trait PA and stimulated IL-1beta or TNF-alpha. Additionally, trait negative affect was unrelated to any of the stimulated cytokine levels. These initial findings suggest that individuals higher in trait positive emotional style show decreased in vitro production of the early inflammatory mediators IL-6 and IL-10 in response to stimulation with endotoxin which may confer protection against the emergence and progression of inflammatory diseases. Further exploration of this potential psychophysiological pathway is warranted.     

白细胞介素-6与脑胶质瘤关系的研究

目的:通过观察人脑胶质瘤细胞是否可以自发分泌白细胞介素-6(interleukin-6,IL-6),为进一步探讨IL-6在脑胶质瘤发生、发展中的可能作用提供线索。方法:对4例脑胶质瘤病人的手术标本进行原代细胞培养,分不同时相收获上清,并对其上清进行IL-6活性检测。结果:各组上清中均有IL-6活性,IL-6生物活性以D_(0～6)上清活性最高(1.131U/L),D_(0～6)上清活性最低(0.18U/L)。人脑胶质瘤细胞受细菌脂多糖刺激后,分泌IL-6的能力略有增强。IL-6单克隆抗体可中和脑胶质瘤上清对B9.9细胞的增殖作用。结论:原代培养的人脑胶质瘤细胞可自发分泌IL-6。     

Visualization of beta-amyloid peptide (Abeta) phagocytosis by human mononuclear phagocytes: dependency on Abeta aggregate size

Previous studies from this laboratory have shown that human monocytes exposed to beta-amyloid peptide (Abeta) exert a graded neurotoxic response in an organotypic brain culture paradigm. Moreover, this toxicity can be reduced by compounds that inhibit cell motility and phagocytosis, suggesting that internalization of Abeta may be a requirement for neurotoxic action. To confirm that Abeta is indeed phagocytosed by monocytes and to further lay the groundwork for resolving the possible linkage between this process and neurotoxicity, we examined Abeta:monocyte interactions using immunocytochemistry and fluorescence histochemistry followed by confocal microscopy and three-dimensional image reconstruction. Internalization of Abeta was detected by 24 hr following exposure of monocytes to the purified peptide, and the relative efficacy of this process appeared to be influenced by the size of the Abeta aggregates. Specifically, smaller aggregates were observed to be more efficiently internalized, while larger Abeta masses tended to reside only on the monocyte surface, apparently bound to several monocytes at once. Both colchicine and cytochalasin D, cytoskeletal perturbants that block phagocytosis, caused Abeta to accumulate in deep pits within monocytes and inhibited complete envelopment by monocyte cytoplasm. These results suggest that monocytes can indeed phagocytose aggregates of Abeta and that this process may be critical in activating these cells to a neurocytopathic state. Accordingly, interference of Abeta phagocytosis by monocytes or monocyte-derived cells may be a novel target for therapeutic action.     

人脑胶质瘤细胞白细胞介素-6的基因表达及自分泌环路的验证

目的 验证新鲜人脑胶质瘤细胞是否能自发分泌和表达白细胞介素－６（ｉｎｔｅｒｌｅｕｋｉｎ－６,ＩＬ－６）并进一步明确ＩＬ－６在脑脑胶质瘤发生及发展中的作用。方法 采用手术中直接获得的人脑胶质瘤组织,进行胶质瘤细胞的原代培养,对瘤细胞培养上清进行ＩＬ－６生物活性检测,然后采用逆转录聚合酶链反应（ｒｅｖｅｒｓｅ ｔｒａｎｓｃｒｉｐｔｉｏｎ－ｐｏｌｙｍｅｒａｓｅ ｃｈａｉｎ ｒｅａｃｔｉｏｎ,ＲＴ－ＰＣＲ     

IL-3、IL-6和IL-8在人脑膜瘤中的表达和作用

目的：探讨白细胞介素（IL）－3、IL－6和IL－8在脑膜瘤细胞中的表达和作用，以及体外针对这种生长调节环路抑制脑膜瘤细胞增殖的可行性。方法：原代培养起21例脑膜瘤细胞。采用ABC免疫细胞化学法明确IL－3、IL－6和IL－8在脑膜瘤细胞中的表达，并选用四唑盐（MTT）比色法观察上述细胞因子及IL－3单抗对脑膜瘤细胞增殖的调控作用。结果：脑膜瘤细胞可分泌IL－3、IL－6和IL－8。IL－3和IL－8皆以剂量依赖关系刺激培养脑膜瘤细胞增殖，而IL－8仅在10ng/ml时对脑膜瘤细胞增殖的刺激效应有统计学差异。IL－3单抗以剂量依赖关系分别抑制正常脑膜瘤细胞及50％V／V脑膜瘤培养是取液刺激的脑膜瘤细胞增殖。结论：IL－3、IL－6和IL－8为脑膜瘤自泌细胞因子；IL－3和IL－6刺激体外培养脑膜瘤细胞增殖；IL－3单抗抑制体外培养脑膜瘤细胞增殖，为脑膜瘤的生物治疗提供新 的理论基础。     

Association of plasma IL-6 and soluble IL-6 receptor levels with the Asp358Ala polymorphism of the IL-6 receptor gene in schizophrenic patients

Recent studies indicate a role of excessive interleukin-6 (IL-6) signaling in the pathogenesis of schizophrenia. A previous study reported a significant association of schizophrenia with the IL-6 receptor (IL-6R) gene Asp358Ala polymorphism, which is known to regulate circulating IL-6 and soluble IL-6R (sIL-6R) levels in healthy subjects. To further examine the influence of the polymorphism in schizophrenic patients, we compared the plasma levels of IL-6 and sIL-6R between schizophrenic patients and healthy controls for each genotype of the Asp358Ala polymorphism. Asp358Ala genotyping and plasma IL-6 level measurements were performed in 104 patients with schizophrenia and 112 healthy controls. Of these participants, 53 schizophrenic patients and 49 controls were selected for the measurement of plasma sIL-6R levels. A two-way factorial analysis of covariance was performed with the transformed plasma levels as the dependent variable, diagnosis and genotype as independent variables, and sex and age as covariates. No significant diagnosis × genotype interaction was observed for IL-6 and sIL-6R levels. The Ala allele of Asp358Ala was significantly associated with higher levels of both IL-6 and sIL-6R. IL-6 levels were significantly elevated in schizophrenic patients compared to those in controls, whereas no significant difference in sIL-6R levels was observed between schizophrenic patients and controls. Our findings suggest that the presence of schizophrenia is associated with elevated IL-6 levels, whereas sIL-6R levels are mainly predetermined by the Asp358Ala genotype and are not associated with the disease status. Increased IL-6 levels without alterations in sIL-6R levels may result in excessive IL-6 signaling in schizophrenia.     

The relevance of the Lewy body to the pathogenesis of idiopathic Parkinson''s disease.

The Lewy body is a distinctive neuronal inclusion that is always found in the substantia nigra and other specific brain regions in Parkinson's disease. It is mainly composed of structurally altered neurofilament, and occurs wherever there is excessive loss of neurons. It occurs in some elderly individuals and rarely in other degenerative diseases of the central nervous system. In 273 brains of patients dying from disorders other than Parkinson's disease, the age-specific prevalence of Lewy bodies increased from 3.8% to 12.8% between the sixth and ninth decades. Associated pathological findings suggest that these cases of incidental Lewy body disease are presymptomatic cases of Parkinson's disease, and confirm the importance of age (time) in the evolution of the disease. In view of the common and widespread occurrence of this disorder we propose that endogenous mechanisms operating in early life may be more important than environmental agents in the pathogenesis of Lewy bodies and Parkinson's disease.     

Mitochondrial permeability in neuronal death: possible relevance to the pathogenesis of Parkinson's disease

1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) causes catecholaminergic nerve cell loss and a syndrome similar to Parkinson's disease (PD). The metabolite of MPTP, MPP⁺ (1-methyl-4-phenylpyridinium), decreases mitochondrial complex I activity similar to that in the PD nigra. Opening of a multi-protein, mitochondrial membrane pore constitutes a critical decisional event in some forms of apoptosis. We review recent findings showing that the permeability transition pore (PTP) opening caused by a decrease in the mitochondrial membrane potential (ΔΨ_M) contributes to MPP⁺-induced apoptosis. The reduction in ΔΨ_M appears to result from decreased proton pumping at complex I and therefore decreased complex I activity may also contribute to apoptosis in PD.     

Homocysteic acid induces intraneuronal accumulation of neurotoxic Abeta42: implications for the pathogenesis of Alzheimer's disease

The causes of neuronal dysfunction and degeneration in Alzheimer's disease (AD) are not fully understood, but increased production of neurotoxic forms of amyloid beta-peptide-42 (Abeta42) seems of major importance. Large extracellular deposits of aggregated Abeta42 (plaques) is a diagnostic feature of AD, but Abeta42 may be particularly cytotoxic when it accumulates inside neurons. The factors that may promote the intracellular accumulation of Abeta42 in AD are unknown, but recent findings suggest that individuals with elevated homocysteine levels are at increased risk for AD. We show that homocysteic acid (HA), an oxidized metabolite of homocysteine, induces intraneuronal accumulation of a Abeta42 that is associated with cytotoxicity. The neurotoxicity of HA can be attenuated by an inhibitor of gamma-secretase, the enzyme activity that generates Abeta42, suggesting a key role for intracellular Abeta42 accumulation in the neurotoxic action of HA. Concentrations of HA in cerebrospinal fluid (CSF) were similar in AD and control subjects. CSF homocysteine levels were elevated significantly in AD patients, however, and homocysteine exacerbated HA-induced neurotoxicity, suggesting a role for HA in the pathogenic action of elevated homocysteine levels in AD. These findings suggest that the intracellular accumulation of Abeta42 plays a role in the neurotoxic action of HA, and suggest a potential therapeutic benefit of agents that modify the production and neurotoxic actions of HA and homocysteine.     

Tryptase activates peripheral blood mononuclear cells causing the synthesis and release of TNF-alpha,IL-6 and IL-1 beta: possible relevance to multiple sclerosis

Presence of mast cells and an increase in the concentration of their products has been reported in multiple sclerosis (MS) plaques. The most abundant secretory mediator of the human mast cell is the tetrameric protease tryptase. We demonstrate that tryptase can activate peripheral mononuclear cells (PBMCs), isolated from healthy donors as well as MS patients for the release of tumor necrosis factor-alpha (TNF-alpha), interleukin (IL)-6 and IL-1beta. Cytokine secretion was significantly higher in secondary progressive (SP) MS patients and healthy control (HC) individuals than in relapsing-remitting (RR) patients. Our findings suggest that tryptase is, most probably, an important mediator of inflammation in MS.     

Adjuvant-induced arthritis: IL-1 beta, IL-6 and TNF-alpha are up-regulated in the spinal cord.

Adjuvant-induced arthritis (AIA) is a widely used animal model of human rheumatoid arthritis (RA). We have previously shown that increased neuropeptide expression is observed in the spinal cord of AIA rats. To study the potential role of cytokines in the spinal cord of AIA, we wanted to determine whether there are changes of glial and cytokine expression (IL-1 beta, IL-6, TNF-alpha and IFN-gamma) in the spinal cord of AIA rats. Our data indicated that macroglia and MHC class II immunostaining were enhanced, astrocytes expressing GFAP were increased in number and immunostaining intensity. Using in situ hybridization and immunohistochemical methods, both mRNA and protein levels of IL-1 beta, IL-6 and TNF-alpha were significantly increased in the spinal cord of arthritic rats. Increased cytokine expression was presented in the reactive astrocytes and microglia.     

An imbalance in the production of IL-1beta and IL-6 by monocytes of bipolar patients: restoration by lithium treatment

OBJECTIVES: To study the ex vivo interleukin (IL)-1beta and IL-6 production of monocytes in bipolar disorder (BD) patients in the absence/presence of lithium. METHODS: Monocytes of outpatients with DSM-IV BD (n=80, of whom 64 were lithium-treated) and of healthy control subjects (n=59) were cultured in vitro and exposed (24 h) or not exposed to lipopolysaccharide (LPS) and/or graded concentrations of lithium chloride (LiCl). IL-1beta and IL-6 production was assessed by enzyme-linked immunosorbent assay (ELISA) (supernatants). RESULTS: Monocytes stimulated by LPS from non-lithium-treated bipolar patients were characterized by an abnormal IL-1beta/IL-6 production ratio, i.e., low IL-1beta and high IL-6 production. Lithium treatment increased IL-1beta and decreased IL-6 production and thus restored the aberrant ratio. In vitro exposure of monocytes to LiCl did not have the same effects as lithium treatment: the procedure decreased IL-1beta production and had minimal effects on IL-6 production. CONCLUSIONS: Blood monocytes have an altered proinflammatory status in BD. Lithium treatment restores this altered status. Short-term in vitro exposure of monocytes to lithium has other effects than lithium treatment.     

IL-2 and IL-6 secretion in dementia: correlation with type and severity of disease

The production of interleukin-2 (IL-2) and interleukin-6 (IL-6) by peripheral blood mononuclear cells (MNC) was assessed in patients with Alzheimer's disease (AD) who were subdivided into two groups — mild and moderately-severe — according to the severity of the disease, probable vascular dementia (VaD) patients and elderly control subjects. No differences in IL-2 secretion were found between mild AD patients and controls. However, there was a significant increase in IL-2 production both in the moderately-severe AD group and in the VaD group. IL-6 levels in AD patients of both groups were similar and significantly higher than those of VaD and controls. Our results suggest that increased levels of IL-2-production correlate with severity of the dementia, whereas increased levels of IL-6 production seem to be related to AD and thus may play a role in AD pathogenesis.     

Novel activity of an anti-inflammatory cytokine: IL-10 prevents TNFalpha-induced resistance to IGF-I in myoblasts

IL-10 is an anti-inflammatory cytokine that suppresses synthesis of proinflammatory cytokines and their receptors. Here we tested the possibility that TNFalpha-induced hormone resistance in myoblasts might be overcome by IL-10. We found that IL-10 restores myogenesis by suppressing the ability of exogenous TNFalpha to inhibit IGF-I-induced myogenin. This protection occurs without decreasing global activity of TNF receptors since IL-10 does not impair TNFalpha-induced IL-6 synthesis or ERK1/2 phosphorylation. Instead, IL-10 acts to prevent TNFalpha-induced phosphorylation of JNK. These findings demonstrate that IL-10 serves a previously unrecognized protective role in muscle progenitors by overcoming TNFalpha-induced resistance to IGF-I.     

Expression of BRI2 mRNA and protein in normal human brain and familial British dementia: its relevance to the pathogenesis of disease

Introduction: Two different disease‐specific mutations in the BRI2 gene, situated on chromosome 13, have been identified as giving rise to familial British dementia (FBD) and familial Danish dementia (FDD). Each mutation results in extension of the open reading frame generating the disease‐specific precursor proteins which are cleaved by furin‐like proteolysis releasing the amyloidogenic C‐terminal peptides ABri and ADan in FBD and FDD, respectively. Material and methods: To understand the mechanism of the formation of amyloid lesions in FBD, we studied the origin of the precursor proteins and furin in the human brain. We used control brains, cases of sporadic Alzheimer's disease (AD), variant AD with cotton wool plaques and FBD to study BRI2 mRNA expression using in situ hybridization. Furin and BRI2 protein expression was investigated using Western blotting and immunohistochemistry. Results: BRI2 mRNA and BRI2 protein are widely expressed primarily by neurones and glia and are deposited in the amyloid lesions in FBD. They were, however, not expressed by cerebrovascular components. Furin expression showed a similar pattern except that it was also present in cerebrovascular smooth muscle cells. Conclusions: These findings suggest that neurones and glia and are a major source of BRI2 protein and that in FBD, the mutated precursor protein may undergo furin cleavage within neurones to produce the amyloid peptide ABri. The failure to demonstrate BRI2 in blood vessels under the conditions tested suggests that vascular amyloid peptide production does not contribute significantly to cerebral amyloid angiopathy (CAA) in FBD and FDD, lending indirect support to the drainage hypothesis of CAA.