Prostaglandin E2 induces interleukin-6 synthesis in human astrocytoma cells

Prostaglandins (PGs) and cytokines, such as interleukin-1 (IL-1) and interleukin-6 (IL-6), have been implicated in the etiopathology of various inflammatory and degenerative disorders, including Alzheimer's disease (AD) and prion diseases. Nonsteroidal antiinflammatory drugs (NSAIDs), potent inhibitors of PG synthesis, appear to be beneficial in the treatment of AD. To assess whether PGs are able to induce IL-6 synthesis in cells of the CNS, IL-6 mRNA and protein syntheses were measured in a human astrocytoma cell line after stimulation with different PGs. PGE1 and PGE2, but not PGD2 and PGF2 alpha, led to a rapid and transient induction of IL-6 mRNA, followed by IL-6 protein synthesis. Furthermore, PGE2 potentiated IL-1 beta-induced IL-6 mRNA synthesis. These results are discussed with respect to the participation of PGs in neurodegenerative diseases (and its inhibition by NSAIDs) by affecting cytokine expression.     

Human herpesvirus type 8 interleukin-6 homologue is functionally active on human myeloma cells

Seroepidemiology and polymerase chain reaction studies have strongly suggested that human herpesvirus type 8 (HHV-8) is associated with Kaposi's sarcoma, Castleman's disease, and body cavity-based lymphoma. The genome of HHV-8 harbors a viral analogue of the interleukin-6 (IL-6) gene. The amino acid sequence of the viral IL-6 (vIL-6) protein is 24.7% identical to human IL-6 (hIL-6). IL-6 as a B-cell growth and differentiation factor is known to play an essential role in the pathophysiology of B-cell tumors. Thus, it seems possible that virus-encoded IL-6 contributes to malignant growth of HHV-8-positive B-cell lymphatic tumors. We have tested a preparation of HHV-8-derived IL-6 for the ability to promote the proliferation of the human myeloma cell line INA-6, which is strictly dependent on exogenous IL-6 for growth and survival. Viral IL-6 significantly induced DNA synthesis of INA-6 cells, but required much more protein on a weight basis when compared with hIL-6 for maximal proliferation. The proliferative effect of vIL-6 was almost completely inhibited by a combination of anti-IL-6 receptor (IL-6R) and anti-gp130 antibodies or IL-6R superantagonist Sant7 and anti-gp130 antibodies. This report demonstrates that vIL-6 has proliferative activity on human cells and that the IL-6R and gp130 are involved in vIL-6 signaling in the myeloma cell line INA-6.     

Primary human herpesvirus 7 infection: a comparison of human herpesvirus 7 and human herpesvirus 6 infections in children

Atrial fibrillation is an important and independent risk factor for cerebrovascular disease and vascular dementia. There is increasing evidence that atrial fibrillation is associated with an increased risk of asymptomatic or silent cerebral infarction and as a result may confer an increased risk of progressive cognitive impairment on a person. In this study we sought to determine whether this hypothesis could be explored in a prospective case controlled design. Twenty seven patients with non-valvular atrial fibrillation (NVAF) and no history of stroke, transient ischaemic attack, dementia, and thyrotoxicosis were compared with 54 age and sex matched controls in sinus rhythm. All cases underwent clinical examination, ECG, and psychological assessment using a battery of nine neuropsychological tests. Between group analysis and a comparison of mean test scores of paired controls with cases were undertaken. The presence of atrial fibrillation was consistently associated with poorer performances on all the subtests of the neuropsychological battery. There was no association between duration of atrial fibrillation and performance. These results provide evidence to justify further examination of the hypothesis in a larger prospective study to determine whether antithrombotic therapy may protect against cognitive decline in patients at maximal risk of silent cerebral ischaemia and associated cognitive decline.     

Integration of human herpesvirus 6 in a Burkitt's lymphoma cell line

Human herpesvirus 6 (HHV-6) genome has been found in several human lymphoid malignancies, but configuration of the HHV-6 genome has not been well delineated. We established the HHV-6-positive, Epstein-Barr virus-negative Burkitt's lymphoma cell line Katata. In this study we investigated the status of the HHV-6 genome in Katata cells. Neither linear nor circular HHV-6 DNA was detected by Gardella gel analysis. The fluorescence in situ hybridization technique enabled us to directly visualize the integrated HHV-6 DNA at the single-cell level. Only one integrated site of viral DNA was detected in metaphase chromosomes and it was preferentially located at the long arm of chromosome 22 (22q13). Treatment of the cells with 12-O-tetradecanoyl-phorbol-13-acetate (TPA) or with calcium ionophore A23187 led to induction of the HHV-6 immediate-early gene as well as the late gene. Sodium n-butyrate also gave rise to expression of the HHV-6 genes. The TPA inducibility was synergistically enhanced when combined with A23187 or n-butyrate. Our study provides, for the first time, an in vitro model system of latent HHV-6 infection whose genome is integrated into host DNA of lymphoma cells.     

Expression of interleukin-6 and its effect on the cell growth of gastric carcinoma cell lines

The expression and the effect of IL-6 were examined in human gastric carcinoma cell lines to determine whether IL-6 serves as a growth stimulator. The expression of IL-6 mRNA was detected in three (TMK-1, MKN-1, MKN-7) of 8 gastric carcinoma cell lines. All three cell lines secreted IL-6 into the culture fluid, in large amounts in the cases of MKN-1 and MKN-7 cells. Scatchard plot analysis of IL-6 binding revealed that MKN-1 and MKN-7 cells had both high- and low-affinity receptors. Cell growth of MKN-1 and MKN-7 cells was stimulated by IL-6, while anti-IL-6 antibody inhibited growth. The expression of IL-1 alpha mRNA by these three cell lines was induced by IL-6. IL-1 alpha increased the expression of mRNA for IL-6 by TMK-1 cells. These findings indicate that IL-6 induced by IL-1 alpha is an autocrine growth factor for some gastric carcinomas.     

Proliferation of human non-small-cell lung cancer cell lines: role of interleukin-6

PURPOSE: The aim of this study was to describe the dysmorphogenetic process leading to esophageal atresia and tracheoesophageal fistula (EA + TEF) in the recently developed Adriamycin model of the malformation. METHODS:Time-mated pregnant rats were given either Adriamycin (1.75 mg/kg intraperitoneally) or saline on days 6 to 9 of gestation, and their embryos recovered on days 12, 12.5, and 13 were serially sectioned in the transversal plane and studied microscopically after H&E and PAS staining. The findings were compared with those of age-matched untreated embryos. RESULTS: All untreated and saline embryos were normal, whereas 49% of Adriamycin embryos had foregut malformations. Tracheoesophageal separation was complete on day 12 in control embryos, whereas 9 of 10 Adriamycin-exposed embryos had a common esophagotrachea with low emergence of the bronchi at that stage. This pattern had evolved into that of a regular EA + TEF in all nine malformed embryos by day 13. On day 12.5, esophagotrachea was found in 6 of 13 and EA + TEF in 5 of 13 embryos. Two had less well-defined malformations. CONCLUSIONS: Esophagotrachea equivalent to complete tracheoesophageal cleft is the first step leading to EA + TEF in this model. The full-blown malformation is finally acquired by partial loss of the posterior wall of the foregut, which tapers-off in the mediastinal mesenchyme and respiratory differentiation of the anterior wall down to the level of bronchial bifurcation, where it constitutes the fistula and the distal esophagus.     

Thymic stroma-derived T-cell inhibitory factor (TSTIF). 2: TSTIF acts on the antigen-presenting cell to inhibit antigen-stimulated T-cell proliferation

Culture supernatant (SN) was obtained from the monolayer of the MRL104.8a thymic stromal cell clone. This SN alone induced proliferation of helper T-cell (Th) clones because it contained IL-7. However, addition of the SN to cultures of Th stimulated with antigen plus antigen-presenting cells (APC) resulted in potent inhibition of their proliferation. This suppression was ascribed to a factor (designated thymic stroma-derived T-cell inhibitory factor, TSTIF) that is contained in the MRL104.8a SN and distinct from IL-7. TSTIF affected antigen-stimulated proliferation of both type 1 helper (Th1) and type 2 helper (Th2) T-cell clones. The TSTIF effect was also observed by the presence of the MRL104.8a SN only in the initial 24 hr pre-culture during the entire course (48-72 hr) of antigenic stimulation. Pre-exposure of Th cells to the SN in the absence of Ag/APC induced their proliferation upon stimulation with Ag/APC in the next 48 hr cultures. However, pre-cultures of Th cells with the SN in the presence of APC alone (without antigen) resulted in potent inhibition of the subsequent Ag/APC-stimulated proliferation. Interaction of TSTIF with APC but not with responding Th cells was further demonstrated in the following experiment: APC alone were exposed to the MRL104.8a SN and used for stimulation of Th that had not been exposed to the SN. Such an APC population exhibited a remarkably reduced capacity to induce antigen-stimulated Th proliferation when compared to that induced by freshly prepared APC or APC cultured in the absence of the MRL104.8a SN. These results indicate that TSTIF exerts its inhibitory effect on the antigen-stimulated T-cell proliferation by acting on APC.     

Acute effects of recombinant human interleukin-6 on endocrine and central nervous sleep functions in healthy men

Interleukin-6 (IL-6) is a proinflammatory cytokine that has been shown to mediate, in addition to immune reactions, various endocrine and central nervous components of the acute phase response. In this context, the present study aimed to specify the contributions of IL-6 to the regulation of pituitary-adrenal secretory activity and GH and TSH secretion, as well as to the regulation of central nervous sleep and mood in healthy men. Effects of a low dose of IL-6 (0.5 microgram/kg body weight) were assessed, inducing plasma IL-6 concentrations closely comparable with those typically observed after infectious challenge. Each of the 16 male subjects participated in two 14-h sessions (between 1800 and 0800 h), receiving either placebo or human recombinant IL-6 sc at 1900 h. Blood was collected repeatedly to determine plasma hormone levels, serum concentrations of cytokines, and C-reactive protein. Moreover, mood was assessed, and sleep recordings were obtained between 2300 and 0700 h. The cytokine induced a prolonged increased in plasma concentrations of ACTH and cortisol (P < 0.001), but led to a decrease in TSH concentrations (P < 0.01). In response to IL-6, subjects reported fatigue and felt more inactive and less capable of concentrating than after placebo. Sleep architecture was altered significantly by the cytokine. Slow-wave sleep was decreased during the first half and increased during the second half of sleep. Rapid eye movement sleep during the entire nocturnal sleep time was significantly decreased. After IL-6, body temperature rose slightly. C-reactive protein concentrations were dramatically increased 12.5 h after substance administration (P < 0.001). IL-6 did not affect serum concentrations of IL-2, IL-8, interferon-alpha, and interferon-gamma. The results underscore the importance of IL-6 in the cascade of cytokines for the neuroendocrine response during the acute phase reaction. In addition, IL-6 appears to be involved in changes of sleep and behavior accompanying infection and inflammatory disorders.     

The interleukin-2 receptor: a target for monoclonal antibody treatment of human T-cell lymphotrophic virus I-induced adult T-cell leukemia

Adult T-cell leukemia (ATL) is a malignancy of mature lymphocytes caused by the retrovirus human T-cell lymphotrophic virus-I (HTLV-I). It is an aggressive leukemia with an overall mortality rate of 50% within 5 months; no conventional chemotherapy regimen appears successful in inducing long-term disease-free survival in ATL patients. However, ATL cells constitutively express high-affinity interleukin-2 receptors (IL-2Rs) identified by the anti-Tac monoclonal antibody, whereas normal resting cells do not. To exploit this difference in receptor expression, we administered anti-Tac intravenously (IV) to 19 patients with ATL. In general the patients did not suffer untoward reactions, and in 18 of 19 cases did not have a reduction in normal formed elements of the blood. Seven patients developed remissions that were mixed (1 patient), partial (4 patients), or complete (2 patients), with partial and complete remissions lasting from 9 weeks to more than 3 years as assessed by routine hematologic tests, immunofluorescence analysis, and molecular genetic analysis of T-cell receptor gene rearrangements and of HTLV-I proviral integration. Furthermore, remission was associated with a return to normal serum calcium levels and an improvement of liver function tests. Remission was also associated in some cases with an amelioration of the profound immunodeficiency state that characterizes ATL. Thus the use of a monoclonal antibody that blocks the interaction of IL-2 with its receptor expressed on ATL cells provides a rational approach for treatment of this aggressive malignancy.     

Expression of interleukin-6 and interleukin-6 receptors in human granulosa lutein cells

Prolonged isolated thrombocytopenia, defined as recovery of other cell counts with continuous dependence on platelet transfusions for greater than 90 days after hematopoietic stem cell transplantation (HSCT), develops in approximately 5% of patients who undergo HSCT. Although the clinical conditions associated with prolonged isolated thrombocytopenia have been studied, a systematic review of bone marrow biopsies has not been performed and the pathophysiologic basis has not been defined. We reviewed all HSCT at one center from 1990 to 1995 (n = 454) and found 12 cases that met criteria for prolonged isolated thrombocytopenia (incidence = 12/454 or 3%). Bone marrow core biopsies from 12 patients with prolonged isolated thrombocytopenia were reviewed to determine cellularity, numbers of megakaryocytes, the presence of atypical forms, and clusters of megakaryocytes. These marrow megakaryocyte counts were compared to age and disease matched controls, and 11 normal donors. Patients (aged 1-56 years, mean 32 years) who underwent HSCT (four sibling HLA-identical, five autologous bone marrow, three autologous peripheral stem cell) with prolonged isolated thrombocytopenia had a statistically significant lower absolute megakaryocyte count in bone marrow biopsies performed before transplantation and more than 30 days after transplantation compared to control patients (aged 4 months to 50 years, mean 31 years) who underwent HSCT (four sibling HLA-identical, four autologous bone marrow, four autologous peripheral stem cell) for similar conditions. No apparent differences were seen in size of megakaryocytes, nuclear-cytoplasmic ratios, or clustering of megakaryocytes. Overall marrow cellularities were similar in the three groups. These findings suggest that decreased differentiation of megakaryocytes from stem cells, rather than ineffective platelet production or peripheral destruction of platelets, causes prolonged isolated thrombocytopenia in HSCT patients. Low megakaryocyte counts prior to HSCT may be a useful prognostic indicator, as this feature was associated with the development of prolonged isolated thrombocytopenia.     

Activation of antigen-induced lymphocyte proliferation by interleukin-15 without the mitogenic effect of interleukin-2 that may induce human immunodeficiency virus-1 expression

The newly identified cytokine, IL-15 enhanced antigen-induced proliferation of PBMC obtained from HIV-1-seropositive subjects. When compared to IL-2 which enhanced both spontaneous and antigen-induced lymphocyte proliferative responses, IL-15 rarely increased spontaneous lymphocyte proliferation. Additionally, in cultures of lymphocytes obtained from 15 HIV-1-infected patients with < 300 circulating CD4- lymphocytes/microliter IL-15 induced significant HIV-1 expression (46, 21, and 71 pg/ml) in only 3 of 15 experiments and IL-2 induced significant HIV-1 expression (range 16- > 5000 pg/ml) in 11 of 15 experiments (P < 0.01, Fischer's exact test). Simultaneous assays of cytokine-induced spontaneous lymphocyte proliferation and HIV-1 expression revealed similar dose-response relationships for induction of HIV-1 and lymphocyte proliferation by IL-2. Thus, IL-15 helps to correct the impaired proliferative response of CD4+ lymphocytes from HIV-1-infected persons without the mitogenic effect of IL-2 that also may induce HIV-1 expression.     

Two distinct pathways of interleukin-5 synthesis in allergen-specific human T-cell clones are suppressed by glucocorticoids

Glucocorticoids (GC) have long been used as the most effective agents for the treatment of allergic diseases accompanied by eosinophilia such as chronic asthma and atopic dermatitis. The development of chronic eosinophilic inflammation is dependent on interleukin-5 (IL-5), a selective eosinophil-activating factor, produced by helper T cells. To delineate the regulatory mechanisms of human IL-5 synthesis, we established allergen-specific CD4+ T-cell clones from asthmatic patients. GC efficiently suppressed IL-5 synthesis of T-cell clones activated via either T-cell receptor (TCR) or IL-2 receptor (IL-2R). Induction of IL-5 mRNA upon TCR and IL-2R stimulation was totally inhibited by dexamethasone. Human IL-5 promoter/enhancer-luciferase gene construct transfected to T-cell clones was transcribed on either TCR or IL-2R stimulation and was clearly downregulated by dexamethasone, indicating that the approximately 500-bp human IL-5 gene segment located 5' upstream of the coding region contains activation-inducible enhancer elements responsible for the regulation by GC. Electrophoretic mobility shift assay analysis suggested that AP-1 and NF-kappaB are among the possible targets of GC actions on TCR-stimulated T cells. NF-AT and NF-kappaB were not significantly induced by IL-2 stimulation. Our results showing that GC suppressed IL-5 production by human CD4+ T cells activated by two distinct stimuli, TCR and IL-2R stimulation, underscore the efficacy of GC in the treatment of allergic diseases via suppression of T-cell IL-5 synthesis.     

Suppressive effect of hepatitis B virus on the induction of interleukin-1 beta and interleukin-6 gene expression in the THP-1 human monocytic cell line

The major target organ for Hepatitis B Virus (HBV) is the liver, but extrahepatic sites including monocytes express receptors for HBV and may become infected. Therefore, we investigated the effect of HBV on the in vitro expression of interleukin-beta (IL-1 beta) and interleukin-6 (IL-6) by the monocytoid cell line THP-1, exposed to various stimuli (LPS, PMA or both). Nonstimulated THP-1 cells did not synthesize IL-1 beta and IL-6, even after in vitro exposure to HBV. LPS stimulation alone induced moderate secretion of both IL-1 beta and IL-6 (300 pg/ml). After induction of macrophage differentiation by PMA, THP-1 cells acquired adherence and expressed a higher level of IL-1 beta (up to 2 ng/ml) but did not synthesize IL-6. Treatment of THP-1 cells with PMA and LPS caused the highest production of both IL-1 beta and IL-6 (> 5ng/ml). In vitro exposure of PMA + LPS-stimulated THP-1 cells to HBV resulted in secretion of both HBsAg and preS2Ag which was maintained over 10 days of culture. Southern blot technique was used to study the state of HBV DNA in the cells. Hybridization of non-digested cellular DNA showed only high molecular weight HBV DNA forms. The HindIII restriction pattern revealed bands corresponding to large DNA fragments and the presence of bands at the 3.2 kb position. Under these conditions (PMA + LPS), HBV inhibited the production of IL-1 beta and IL-6 proteins and completely suppressed the IL-1 beta and IL-6 mRNA. Thus, our findings (i) strongly support a relationship between the state of cell differentiation and susceptibility of cells to HBV infection, and (ii) demonstrate that HBV exerts an inhibitory effect on the induction of IL-1 beta and IL-6 genes expression in monocytic THP-1 cells. These results suggest that HBV leads to a fall of pro-inflammatory cytokine production by monocytes/macrophages, which may contribute to impaired host immune response during infection.     

Enhancing effect of interleukin-2 on production of parathyroid hormone-related protein by adult T-cell leukemia cells

Leukemic cells from patients with adult T-cell leukemia (ATL) can produce a calcium-regulating protein, parathyroid hormone-related protein (PTHrP). Moreover, it has been reported that ATL cells produce some cytokines besides PTHrP and that these cells respond to the T-cell growth factors, interleukin-2 (IL-2) and interleukin-4 (IL-4). To elucidate whether PTHrP produced by ATL cells is regulated by IL-2 or IL-4, we investigated the in vitro effects of IL-2 and IL-4 on the release of PTHrP. IL-2 increased the release of PTHrP into the conditioned medium from leukemic cells in some, but not all, ATL patients; however, IL-4 did not affect the PTHrP release. PTHrP messenger RNA (mRNA) levels were increased in ATL cells cultured in the presence of IL-2. These data suggest that IL-2 plays a role in the regulation of hypercalcemia by enhancing the production of PTHrP in ATL patients.     

Prospective study of human herpesvirus 6, human herpesvirus 7, and cytomegalovirus infections in human immunodeficiency virus-positive patients

Blood samples from human immunodeficiency virus (HIV)-positive patients were monitored for cytomegalovirus (CMV), human herpesvirus 6 (HHV-6), and HHV-7 by PCR. We detected CMV in 17% of the patients, HHV-6 in 6%, and HHV-7 in 3%. The viral loads of CMV were significantly higher than those of HHV-6 (P = 0.007) or HHV-7 (P = 0.01). Detection of CMV and HHV-6 was associated with low and high CD4 counts, respectively.     

Electronmicroscopic study of human herpesvirus 6-infected human T cell lines superinfected with human immunodeficiency virus type 1

Melatonin release by chick cultured pineal cells increases during the dark periods and decreases during the light periods under light-dark cycles, and this rhythmic secretion is maintained under constant conditions with a period of almost 24 hr. The mechanisms by which the circadian oscillator drives the melatonin rhythm under constant conditions have not been elucidated enough. We examined the possibility that cyclic AMP-dependent protein kinase A is involved in the subjective nocturnal increase in melatonin release by chick pineal cells cultured under constant darkness. The subjective nocturnal increase of melatonin release was suppressed dose dependently by H8 (protein kinase inhibitor) and H89 (specific protein kinase A inhibitor), but not by calphostin C (specific protein kinase C inhibitor) in static cell cultures. In a cell perfusion experiment, 9 hr pulses of H8 and H89 starting at ZT 9 (CT 11.2) hr suppressed the subjective nocturnal increase in melatonin rhythm in dose-dependent manner without causing a phase shift. An intracellular Ca2+ chelator, O,O'-bis(2-aminophenoxy)ethyleneglycol-N,N,N',N'-tetraacetic acid tetraacetoxymethyl ester (BAPTA-AM), and extracellular Ca2+ chelators, O,O'-bis(2-aminophenoxy)ethyleneglycol-N,N,N',N'-tetraacetic acid tetrapotassium salt hydrate (BAPTA) and ethyleneglycol-bis(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid (EGTA), suppressed both the subjective nocturnal increases in melatonin release and cAMP levels dose dependently. This direct evidence strongly supports the hypothesis that cAMP-dependent protein kinase A may be involved in the subjective nocturnal increase in melatonin release by chick pineal cells and that intracellular Ca2+ plays an important role in pineal adenylate cyclase activation.     

Differential effects of interleukin-7 and interleukin-2 on T-cell receptor gamma delta-expressing cells within CD4-CD8- postnatal human thymocytes

The purpose of this study was to evaluate pulp reactions to cavities treated with Scotchbond Dual Cure, Gluma and Tenure dentine bonding agents in four adult dogs, at intervals of 7, 30 and 90 days. The reactions were compared with the results from a control group in which the cavities were treated with zinc oxide/eugenol cement. The results indicated that Scotchbond Dual Cure dentine bonding agent caused less pulp reaction than Gluma and Tenure dentine bonding agents. However, long-term (90 days) specimens showed that none of these three bonding agents caused any severe reaction. The recovery of the pulp and a thick layer of reparative dentine formation were found quite significant.