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Biomedical subjects

H Link

Publications and source records attributed to H Link.

At least 55 records · Page 3Linked to original sources
PubMed2001

Multiple sclerosis: deficient in vitro responses of blood mononuclear cells to IFN-beta.

IFN-beta may modify the clinical course of multiple sclerosis (MS) but is not curative, and there are also patients whose disease does not respond to IFN-beta as currently administered. Tests are warranted with a capacity to early discriminate responders from non-responders, thereby altering treatment option for the individual patient. In vitro effects of IFN-beta on expression of activation-associated cell surface markers and cytokine production need to be explored in this context. Here we report on the influence in vitro of IFN-beta on blood mononuclear cells (MNC) prepared from MS patients and healthy controls. MNC were subjected to short-term culture in the presence of IFN-beta at concentrations of 100 U/ml and 1000 U/ml. Expression of cell surface molecules CD40, CD69, CD80, CD86, CD95 and HLA-DR was measured by flow cytometry. IL-10 and IL-12 p40 production in culture supernatants was measured by ELISA. MNC exposed to IFN-beta in vitro enhanced expression of the co-stimulatory CD80, CD86, the early activation antigen CD69 and the cell death receptor CD95. Expression of CD40 and HLA-DR was not influenced. IFN-beta increased IL-10 but suppressed IL-12 p40 production. In vitro effects of IFN-beta on MNC were similar in MS patients and in healthy subjects, except that IFN-beta-induced augmentation of CD86 and CD69 expression was less pronounced in MS, in particular in untreated MS patients. Individual MS patients clearly responded differently to IFN-beta in vitro in comparison with the majority of patients in this cross-sectional study. In conclusion, anti-inflammatory effects of IFN-beta on blood MNC include augmentation of IL-10 production and suppression of IL-12 p40 production, which are accompanied by enhancement of CD69, CD80, CD86 and CD95 expression. The less pronounced IFN-beta-induced effects on CD86 and CD69 expression in MS vs controls might reflect a defect in immunoregulation in MS. Larger groups should be evaluated, and follow-up studies performed in MS patients before/during IFN-beta treatment in relation to clinical outcome measures to evaluate the usefulness of these markers for possible differentiation between responders and non-responders to IFN-beta treatment.

Adult↗
PubMed2001

Rat models as tool to develop new immunotherapies.

Rat models (experimental autoimmune encephalomyelitis, EAE; myasthenia gravis, EAMG) have been developed that mimic certain aspects of the pathophysiology of multiple sclerosis (MS) and myasthenia gravis (MG) in humans. Rat EAE and EAMG are, therefore, widely used to evaluate immunotherapeutic strategies. Mucosal tolerance induced by oral or nasal administration of autoantigen effectively suppresses rat EAE and EAMG. Nasal administration of the cytokines interleukin (IL)-4, IL-10 or transforming growth factor (TGF)-beta1 also ameliorates clinical signs of rat EAE. However, neither mucosal tolerance nor cytokines affect clinical disease if administered during ongoing rat EAE or EAMG. Dendritic cells (DC) pulsed in vitro with autoantigen can mediate peripheral tolerance against rat EAE and EAMG, but do not affect ongoing EAE or EAMG. DC from healthy rats, modified in vitro by exposure to IFN-gamma or TGF-beta1, effectively suppress ongoing EAE and EAMG when given by the subcutaneous route. Most importantly, DC from EAMG rats, after being modified in vitro with IL-10, also inhibit ongoing rat EAMG. These results demonstrate that different strategies influencing T- and/or B-cell responses in rat EAE or EAMG are available, but that DC-based immunotherapies are the most promising, in order to ameliorate ongoing organ-specific autoaggressive immunity Based on these observations, autologous DC, after being modified in vitro with cytokines, constitute a basis for new immunotherapeutic strategies in MS, MG and other diseases with autoimmune background.

Animals↗
PubMed2001

Altered phenotype and function of blood dendritic cells in multiple sclerosis are modulated by IFN-beta and IL-10.

Multiple sclerosis (MS) is assumed to result from autoaggressive T cell-mediated immune responses, in which T helper type 1 (Th1) cells producing cytokines, e.g. IFN-gamma and lymphotoxin promote damage of oligodendrocyte-myelin units. Dendritic cells (DCs) as potent antigen presenting cells initiate and orchestrate immune responses. Whether phenotype and function of DCs with respect to Th1 cell promotion are altered in MS, are not known. This study revealed that blood-derived DCs from MS patients expressed low levels of the costimulatory molecule CD86. In addition, production of IFN-gamma by blood mononuclear cells (MNCs) was strongly enhanced by DCs derived from MS patients. IFN-beta and IL-10 inhibited the costimulatory capacity of DCs in mixed lymphocyte reaction (MLR) and showed additive effects on suppression of IL-12 production by DCs. Correspondingly, DCs pretreated with IFN-beta and IL-10 significantly suppressed IFN-gamma production by MNCs. IFN-beta in vitro also upregulated CD80 and, in particular, CD86 expression on DCs. In vitro, anti-CD80 antibody remarkably increased, while anti-CD86 antibody inhibited DC-induced IL-4 production in MLR. We conclude that DC phenotype and function are altered in MS, implying Th1-biased responses with enhanced capacity to induce Th1 cytokine production. In vitro modification of MS patients' DCs by IFN-beta and IL-10 could represent a novel way of immunomodulation and of possible usefulness for future immunotherapy of MS.

Adult↗
PubMed2001

Bone marrow-derived dendritic cells from experimental allergic encephalomyelitis induce immune tolerance to EAE in Lewis rats.

We have previously shown that dendritic cells (DC), upon being pulsed in vitro with encephalitogenic myelin basic protein peptide 68-86 (MBP 68-86) and injected subcutaneously (s.c.) back to healthy Lewis rats, transfer immune tolerance to experimental allergic encephalomyelitis (EAE) induced by immunization with MBP 68-86 and Freund's complete adjuvant (FCA). We here assumed that DC become pulsed in EAE rats, and that expansion in vitro of such 'in vivo pulsed EAE-DC' might also have the capacity to induce immune tolerance to EAE, thereby eliminating the need for in vitro pulsing of DC with autoantigens which are still unknown in many autoimmune diseases in the human. In the present study, EAE-DC were generated from bone marrow of Lewis rats, with EAE induced with MBP 68-86 + FCA, and expanded in vitro by culture with GM-CSF and IL-4. In comparison with DC from normal rats, EAE-DC exhibited higher viability in the absence of growth factors, and presented specific antigen to naïve T cells in vitro. The DC derived from both EAE and healthy rats stimulated strong proliferation in an antigen-independent manner, lasting for 4 weeks after DC were s.c. injected into healthy rats. During this time, injection of EAE-DC did not induce clinical EAE. However, when these rats were immunized with MBP 68-86 + FCA, subsequent EAE was dramatically suppressed, and was associated with increased IFN-gamma expression, nitric oxide production, gradually reduced proliferation and cell apoptosis, compared with PBS-injected control EAE rats. LPS-treated DC did not induce tolerance, suggesting that the tolerance is mediated by an immature stage of DC. These observations support the hypothesis that EAE-DC can transfer immune tolerance to EAE, thereby omitting the step of characterizing specific autoantigen. Omitting the step of loading DC with antigen not only eliminates the extremely complex procedure of defining pathogenically-relevant autoantigens, but also avoids the risk of inducing immunogenicity of DC in the treatment of autoimmune diseases.

Adoptive Transfer↗
PubMed2001

Reduced levels of insulin-like growth factor-1 receptor (IGF-1R) suppress cellular signaling in experimental autoimmune sialadenitis (EAS).

The nonobese diabetic mouse (NOD) develops destruction and functional impairment of salivary and lachrymal glands, experimental autoimmune sialadenitis (EAS), resembling and representing a model for Sjogren's syndrome (SS). To investigate the mechanisms of tissue destruction in EAS, we analyzed a cell survival promoter insulin-like growth factor-1 receptor (IGF-1R) in the submandibular glands of NOD mice with this disease. We also evaluated the expression of a downstream effector of IGF-1R, BAD. Receptor-binding autoradiography revealed that the IGF-1R levels in submandibular glands from young NOD mice were lower than those in adult NOD mice. Immunofluorescence staining demonstrated that BAD expression in the epithelial cells of the submandibular gland was consistently enhanced throughout the course of EAS in NOD mice. These findings suggest that a reduction in the levels of IGF-1R induces a defective glandular homeostasis in the submandibular gland epithelial cells and triggers EAS.

Animals↗
PubMed2001

Two subsets of dendritic cells are present in human cerebrospinal fluid.

Little is known about the presence of dendritic cells in the human CNS. To investigate the occurrence of dendritic cells in the CSF, paired blood/CSF samples from patients with multiple sclerosis, acute optic neuritis, Lyme neuroborreliosis, other inflammatory neurological diseases and non-inflammatory neurological diseases were examined using flow cytometry. Almost all CSF samples contained myeloid (lin-CD11c+HLA-DR++CD123(dim)) and plasmacytoid (lin-CD11c-HLA-DR+CD123(high)) dendritic cells. In non-inflammatory neurological diseases, dendritic cells of either subset only constituted up to 1% of CSF mononuclear cells. Myeloid CSF dendritic cells were elevated in optic neuritis, neuroborreliosis and other inflammatory neurological disorders, while plasmacytoid dendritic cells were elevated in all neuroinflammatory conditions studied, with especially high numbers in neuroborreliosis. Numbers of CSF dendritic cells correlated with the common parameters of CNS inflammation. The myeloid dendritic cells in CSF expressed higher levels of HLA-DR, CD86, CD80 and CD40 than those in blood, whereas expression of these molecules by plasmacytoid dendritic cells was equal in blood and CSF. Both CSF and blood dendritic cells expressed the chemokine receptor CCR5. This is the first demonstration that dendritic cells are present in human CSF and that plasmacytoid dendritic cells are present in a non-lymphoid compartment. Myeloid and plasmacytoid dendritic cells in CSF may contribute to orchestration of the local immune responses.

Adult↗
PubMed2001

Innovative mentoring programs to promote gender equity in academic medicine.

The authors describe the history, characteristics, and goals of four innovative programs, each in a medical school, that were established in 1998 to help faculty members of both sexes obtain mentors and thereby facilitate their career advancement. The programs were established as the result of an initiative by the Office on Women's Health (OWH) within the U.S. Department of Health and Human Services. Specifically, the OWH convened the National Task Force on Mentoring for Health Professionals, which determined that two principles are paramount to the success of any mentoring relationship or program: institutional commitment and institutional rewards and recognition to mentors. In accordance with the task force findings, the OWH created the National Centers of Leadership in Academic Medicine, one at each of four medical schools: MCP Hahnemann School of Medicine; the University of California, San Diego, School of Medicine; East Carolina University School of Medicine; and Meharry Medical College School of Medicine. The authors give highlights of each program's goals and progress, and note that, ideally, these programs will eventually serve as models for similar programs at other schools. Programs such as these foster the advancement of a diverse faculty, a more supportive academic environment, and the education of providers who are sensitive to the needs of all their patients, staff, and colleagues.

Faculty, Medical↗
PubMed2001

Enzyme-linked immunospot assays provide a sensitive tool for detection of cytokine secretion by monocytes.

Blood monocytes as well as tissue-differentiated macrophages play a pivotal role in controlling immune reactions. Monocytes regulate the extent, nature, and duration of immune responses by secretion of cytokines. Interleukin 6 (IL-6), tumor necrosis factor alpha (TNF-alpha), IL-10, and IL-12 are of particular interest, since IL-12 shifts the immune response towards a Th1 type, facilitating the production of, e.g., TNF-alpha and IL-6, while IL-10 counteracts Th1 responses and promotes the production of Th2-related cytokines such as IL-4. A tight regulation of these four cytokines keeps the balance and decides whether Th1 or Th2 will predominate in immune reactions. Enzyme-linked immunospot (ELISPOT) assays are among the most-sensitive and -specific methods available for cytokine research. They permit ex vivo identification of individual cells actively secreting cytokines. In the present study we prepared monocytes from healthy subjects' blood and adapted ELISPOT assays to define optimal conditions to detect and enumerate monocytes secreting IL-6, TNF-alpha, IL-10, and IL-12. The optimal time for monocyte incubation was 24 h, and optimal monocyte numbers (in cells per well) were 2,000 for IL-6, 1,000 for TNF-alpha, 50,000 for IL-10, and 100,000 for enumeration of IL-12 secreting monocytes. Among healthy subjects, 10% +/- 5% of the monocytes secreted IL-6, 12% +/- 12% secreted TNF-alpha, 0.1% +/- 0.1% secreted IL-10, and 0.2% +/- 0.3% secreted IL-12 (values are means +/- standard deviations). In conclusion, ELISPOT assays constitute a valuable tool to enumerate monocytes secreting IL-6, TNF-alpha, IL-10, and IL-12 and probably to enumerate monocytes secreting other cytokines and proteins.

Adult↗
PubMed2001

Dendritic cells derived from patients with multiple sclerosis show high CD1a and low CD86 expression.

Dendritic cells (DC) are important antigen presenting cells (APC) and play a major role in initiating and orchestrating immune responses by priming T cells. Little is known about involvement of DC in multiple sclerosis (MS), where auto-aggressive T cells against myelin autoantigens are considered to contribute to inflammation and demyelination in the central nervous system. In this study, we compared phenotype and cytokine secretion of DC from patients with MS, other neurological diseases (OND) and healthy subjects. DC were generated from blood adherent mononuclear cells (MNC) by culture for 7 days with granulocyte-macrophage colony-stimulating factor (GM-CSF) and interleukin-4 (IL-4). The yield and morphology of DC were similar in MS patients and controls. In both, the DC phenotype was that of immature myeloid lineage, comprising CD1a+ and CD11c+. The proportion of CD1a+ DC, being important for presentation of lipid antigens to T cells, was higher in MS patients compared to controls. The proportion of CD86+ DC, a co-stimulatory molecule that is assumed to promote Th2 differentiation, was low in MS. Low proportions of CD86+ DC were only observed in untreated MS patients but not in patients treated with IFN-beta. Production of IL-10 and IL-12 p40 by DC did not differ in MS patients and controls. These findings indicate that alterations of functionally important surface molecules on DC are associated with MS.

Adult↗
PubMed2000

Seasonal patterns in optic neuritis and multiple sclerosis: a meta-analysis.

To quantify and characterize seasonal variation in monosymptomatic optic neuritis (MON) onsets, multiple sclerosis (MS) onsets and MS exacerbations (MSE), a meta-analysis was performed, using established methods and pooling weighted information obtained from nine reports on MON, six reports on MS onsets and nine reports on MSE, which fulfilled specific criteria for report quality and data homogeneity. The results suggested that MON, MS onsets and MSE in the Northern hemisphere present a similar pattern with highest frequencies in spring and lowest in winter. These differences were highest for MS onsets, 45% with 95% CI 36-55%, and lowest for MSE, 10% with 95% CI 7-13%, statistically significant and robust, insensitive to an alternative seasonal definition, not unduly influenced by any single primary study, and supported by fail-safe N calculations. Random variation, misclassification and publication bias were less likely to account for the reported generalized seasonal patterns.

Data Interpretation, Statistical↗
PubMed2000

Multiple sclerosis: pro- and anti-inflammatory cytokines and metalloproteinases are affected differentially by treatment with IFN-beta.

Interferon-beta (IFN-beta) has a beneficial influence on the course of multiple sclerosis (MS) and has become standard treatment of this disease, though its mechanisms of action are incompletely understood. This study examines the effect of IFN-beta treatment on the cytokines IL-6, TNF-alpha, IFN-gamma and IL-10; the metalloproteinases MMP-3, -7 and -9 and the tissue inhibitor of metalloproteinase-1 (TIMP-1). IFN-beta treatment resulted in decreased numbers of mononuclear cells (MNC) secreting IL-6 and TNF-alpha and expressing mRNA of MMP-3 and MMP-9 compared to pretreatment levels. On the contrary, numbers of IL-10 secreting MNC and TIMP-1 mRNA expressing were augmented during IFN-beta therapy. Whether the down-regulatory effects on pro-inflammatory and upregulatory effects on anti-inflammatory molecules are a direct result of IFN-beta on the immune system or secondary to clinical stabilization of MS pathology induced by IFN-beta remains to be evaluated.

Cells, Cultured↗
PubMed2000

Double minutes and c-MYC amplification in acute myelogenous leukemia: Are they prognostic factors?

A case of acute myelogenous leukemia (AML) with double minutes (dmin) and X chromosome loss is presented. Using comparative genomic hybridization (CGH), a region of high-level DNA amplification was detected at 8q24, the locus of the c-MYC proto-oncogene. Fluorescence in situ hybridization (FISH) with a DNA probe specific for the human c-MYC gene confirmed the extrachromosomal amplification of this proto-oncogene in the dmin of the leukemic cells. During the course of the disease, three relapses occurred; two complete remissions could be achieved by treatment with various chemotherapy regimens. The patient's survival time of 25 months was considerably longer than in most reported cases of AML with extrachromosomal c-MYC amplification. Therefore, the present case challenges the view that the occurrence of dmin in AML is generally an indication of poor prognosis.

Adult↗
PubMed2000

An alternative pathway of nitric oxide production by rat astrocytes requires specific antigen and T cell contact.

In the present study, we observed an alternative pathway in which nitric oxide (NO) production by rat astrocytes requires specific antigen and cell-cell contact. NO production by astrocytes was significantly inhibited by antibodies against CD40L, B7-1 or B7-2. Astrocyte-derived NO inhibited T cell proliferation and induced T cell apoptosis. In contrast, augmented astrocyte proliferation was correlated to the levels of NO production by astrocytes, implicating a role of NO in regulating local immune responses in the central nervous system. These results suggest that T cell-astrocyte interactions may regulate local immune responses via the NO pathway and influence the fate of infiltrating T cells.

Animals↗
PubMed2000

Limitation of nitric oxide production: cells from lymph node and spleen exhibit distinct difference in nitric oxide production.

Many types of cells in the immune system have been found to produce nitric oxide (NO), which performs multiplex functions. However, in myelin basic protein peptide 68-86 (MBP 68-86)-induced experimental autoimmune encephalomyelitis (EAE) in Lewis rats, we found that elevated NO production was generated from spleen cells (SC), not from lymph node cells (LNC). LNC expressed lower NO synthase 2 (NOS2) and produced lower levels of NO than SC upon MBP 68-86 stimulation. Expression of B7-1(CD80) and B7-2(CD86) molecules was much lower on LNC than on SC. Blocking of B7-1 or B7-2 ligation resulted in reduced NO production by SC. Unlike SC, LNC were resistant to interferon-gamma- or lipopolysaccharide-induced NO production. NO derived from SC suppressed cell proliferation and induced apoptosis in vitro. Addition of N(omega)-nitrol-L-arginine methylester (L-NAME) into cell cultures promoted cell expansion and reduced apoptosis. These results indicate that NO production originates from SC, but not from LNC. Low expression of co-stimulatory molecules and NOS2 of LNC limits NO induction. The high levels of NO derived from SC are involved in the self-limiting mechanisms of autoimmune responses by inhibiting cell expansion and promoting cell apoptosis.

Amino Acid Sequence↗
PubMed2000

Altered expression of costimulatory molecules in myasthenia gravis.

To characterize the involvement of costimulatory pathways in the pathogenesis of myasthenia gravis (MG), a multiparameter flow cytometry assay was adopted to enumerate blood mononuclear cells (MNC) expressing CD28, CD80, CD86, CD40, and CD40L molecules in patients with MG and healthy subjects. Patients with MG had lower percentages of CD8(+)CD28(+) cells, augmented percentages of CD4(+)CD80(+), CD4(+)CD86(+), CD8(+)CD80(+), CD8(+)CD86(+), CD14(+)CD80(+), and CD14(+)CD86(+) cells, and similar levels of cells expressing CD40 and CD40L and of B cells expressing CD80 and CD86 compared to the controls. Patients with early onset of MG (<40 years) had lower percentages of CD3(+)CD86(+), CD4(+)CD86(+), CD8(+)CD86(+) T cells and CD20(+)CD86(+) B cells compared to those with late onset (>40 years). There was a positive correlation between the patients' age and percentages of CD86(+) cells. The data indicate that the CD28/CD80-CD86 costimulatory pathway is involved in MG. The high percentages of CD80 and CD86 positive T cells and monocytes may reflect persistent activation of T and B cells, whereas the low CD28 expression may be the result of chronic exposure to CD80 and CD86. These molecules could be the focus for new and improved immunomodulating therapies of MG.

Adult↗
PubMed2000

Regression analysis of metabolite concentrations estimated from localized proton MR spectra of active and chronic multiple sclerosis lesions.

Localized short echo time magnetic resonance (MR) spectra were obtained from patients with multiple sclerosis of relapsing-remitting or secondary chronic-progressive course and from healthy controls. Automated analysis using model spectra, sensitivity correction, and subtraction of partial ventricular volume yielded tissue concentrations of metabolites that were in line with findings of previous studies. Additional findings were increased creatine in chronic lesions and increased myo-inositol in normal-appearing white matter. Regression analysis was performed to reveal concomitant changes of metabolite concentrations. Differences in the correlations between cholines and myo-inositol suggest increased expression of myo-inositol in chronic lesions or of cholines in active, contrast-enhanced lesions. A correlation between N-acetyl-aspartate and creatine, which is probably due to extracellular edema, was observed in active but not in chronic lesions. Creatine and cholines correlated in chronic lesions, which may be the result of gliosis. The consequences of these findings for the interpretation of absolute concentrations and creatine ratios are discussed.

Acute Disease↗
PubMed2000

The complexicity of cytokine treatment in ongoing EAE induced with MBP peptide 68-86 in Lewis rats.

IL-10 and TGF-beta1 are important immunoregulatory cytokines associated with clinical remissions in multiple sclerosis and amelioration of experimental allergic encephalomyelitis (EAE). IL-10 and TGF-beta1 have previously been shown to prevent the development of EAE. Here, we study effects of IL-10 and TGF-beta1 in ongoing EAE. When IL-10 or TGF-beta1 was administered by the nasal route from day 0 to day 7 postimmunization (pi), both IL-10 and TGF-beta1 prevented the development of acute EAE in Lewis rats. When IL-10 or TGF-beta1 was administered by the nasal route from day 5 to day 12 pi, both IL-10 and TGF-beta1 failed to influence clinical EAE. The inhibition of clinical EAE severity in IL-10-prevented rats was associated with reduced proliferation, IFN-gamma mRNA expression, and IFN-gamma secretion, while proliferation as well as IFN-gamma mRNA expression and secretion were augmented in TGF-beta1-prevented rats. TGF-beta1-prevented rats exhibited high levels of NO production by DC, which may mediate apoptosis of CD4+ T cells and of the DC themselves. For prevention, both IL-10 and TGF-beta1 inhibited infiltration of CD4+ T cells within the CNS, but neither IL-10 nor TGF-beta1 induced immune deviation from Th1 to Th2. Expression of IL-4 mRNA was not altered in IL-10- and TGF-beta1-prevented rats. These results demonstrate that IL-10 and TGF-beta administration by the nasal route can prevent the development of acute EAE, but by different mechanisms. The findings in rats with ongoing EAE have implications for the clinical application of cytokine treatment in autoimmune diseases.

Animals↗