Ganglioside biosynthetic gene expression in experimental mouse brain tumors.

The genes for cytidine monophospho-N-acetylneuraminic acid hydroxylase (NeuAc-H) and beta-1,4-N-acetylgalactosaminyl transferase (GalNAc-T) were examined using reverse transcription-PCR in two experimental mouse brain tumors, EPEN and CT-2A. NeuAc-H is required for the synthesis of gangliosides containing N-glycolylneuraminic acid, whereas GalNAc-T is required for the synthesis of ganglioside GM2. The genes were analyzed in solid tumors grown in vivo and in tumor cells grown in vitro. NeuGc-containing gangliosides are abundant in cells of the mouse immune system, including macrophages, but are undetectable in normal mouse brain. GM2 is expressed in both neural and nonneural mouse cells and tissues. The EPEN tumor cells synthesize only ganglioside GM3, whereas the CT-2A tumor cells synthesize GM3, GM2, GM1, and GD1a. NeuAc-H gene expression was detected in both solid tumors grown in vivo but was undetectable in either tumor cell line. The presence or absence of NeuAc-H gene expression in the tumor tissues and cells correlates with the presence or absence, respectively, of NeuGc-containing gangliosides. Differences in GalNAc-T gene expression between the solid tumors and the cultured tumor cells correlate with the expression of ganglioside GM2. The findings suggest that the differences in ganglioside biosynthetic gene expression between brain tumors grown in vivo and in vitro are associated with the presence or absence, respectively, of tumor-infiltrating host cells.

Gangliosides influence angiogenesis in an experimental mouse brain tumor.

Gangliosides are sialated glycosphingolipids present on the plasma membranes of all vertebrate cells. Tumors shed gangliosides into the extracellular microenvironment, which may influence tumor-host cell interactions. We have investigated the role of gangliosides on the growth and angiogenesis of the EPEN experimental mouse brain tumor. EPEN cells express only ganglioside G(M3), and the solid tumors formed in vivo are sparsely vascularized with extensive necrosis. We stably transfected the EPEN cells with the cDNA for N-acetylgalactosaminyl transferase, a key enzyme for the synthesis of complex gangliosides. In addition to G(M3), the transfected cell line (EPEN-GNT) expressed complex gangliosides G(M2), G(M1), and G(D1a). The EPEN-GNT tumor was more densely vascularized with less necrosis and grew more rapidly than the nontransfected EPEN or mock-transfected (EPEN-V) control tumors. Also, VEGF gene expression was higher in the EPEN-GNT tumor than in the control tumors. The synthesis of complex gangliosides in the EPEN-GNT tumor cells also stimulated vascularization in an in vivo Matrigel assay for angiogenesis. These results indicate that the ratio of G(M3) to complex gangliosides can influence the growth and angiogenic properties of the EPEN experimental brain tumor and are consistent with previous findings in other systems. We conclude that gangliosides may be important modulators of brain tumor angiogenesis.

Cytokine antagonists in aged subjects and their relation with cellular immunity.

Host responses to infectious and inflammatory stimuli are altered with aging. Because cytokines and their antagonists are significant factors in these host responses, the present research on aged subjects was designed to investigate plasma concentrations of the cytokines interleukin 1 beta (IL-1 beta) and tumor necrosis factor alpha (TNF alpha) and those of their antagonists IL-1 receptor antagonist (IL-1ra) and soluble TNF receptor (sTNFr). For this research, 122 apparently healthy aged subjects (79.6 +/- 5.8 yr), 39 aged individuals with documented urinary tract infections (UTIs) (81.6 +/- 6.3 yr), and 100 young controls (39.32 +/- 11.2 yr) were included. Plasma IL-1 beta, TNF alpha, IL-1ra, sTNFr (55 kDa), and neopterin were measured using enzyme-linked immunosorbent assay techniques. In subsets of normal aged subjects and UTI patients, we investigated relations between plasma concentrations of cytokine antagonists and IL-2 production by phytohemagglutinin-stimulated peripheral blood mononuclear cells. The results show that plasma concentrations of both IL-1ra and sTNFr were greater in healthy aged subjects than in young controls. Plasma neopterin, a product of activated monocytes/macrophages, was likewise elevated in the aged. IL-1 and TNF were not detectable in the majority of plasma samples. There was a positive correlation between neopterin concentration and both IL-1ra and sTNFr. There was a significant negative correlation between plasma IL-1ra and IL-2 production by phytohemagglutinin-stimulated peripheral blood mononuclear cell in healthy aged subjects. IL-1ra and sTNFr concentrations were significantly greater in patients with UTI than in the healthy aged subjects. In UTI patients IL-2 production in vitro was lower than in healthy subjects, but there was no significant correlation with IL-1ra in plasma. Therefore, plasma concentrations of cytokine antagonists are increased in plasma of apparently healthy aged subjects. Elevated concentrations of neopterin suggest that this increase can be traced to monocyte activation. The negative correlation between plasma IL-1ra and IL-2 production in vitro suggests that enhancement of this cytokine antagonist can contribute to immunodepression of aging. We propose that unapparent infections in aged subjects cause monocyte activation and release of cytokine antagonists. These cytokine antagonists reduce IL-2 production and the capability of T cells to proliferate, thereby inhibiting responses in the elderly.

Scintigraphic study of extra-adrenal ganglioneuroma in a patient with overlap between multiple endocrine neoplasia types 1 and 2.

A 27-year-old woman was diagnosed with a pituitary prolactinoma. Seven years later, when she was 34, an abdominal mass was incidentally discovered and ascribed to the right adrenal gland on the basis of evidence from ultrasonography, computed tomography, and arteriography. Adrenal scintigraphy with Se-75 selenomethylcholesterol imaged both adrenal glands, but the right gland was distorted, suggesting external compression. I-131 MIBG was not taken up by the mass. At surgery, an extra-adrenal ganglioneuroma was found and excised. This case represents an overlap between multiple endocrine neoplasia types 1 and 2. The failure of the ganglioneuroma to concentrate MIBG was likely caused by secretory inactivity of a biologically mature tumor.

Resistance of beta-endorphin to dexamethasone inhibition in Parkinson's and Alzheimer's diseases.

The response of plasma beta-endorphin (beta-EP) to dexamethasone suppression was studied in 14 patients with Alzheimer's disease (AD), 14 patients with Parkinson's disease (PD), and 13 age-matched controls in order to evaluate whether an impairment of the opiate system is present in these neurodegenerative disorders. Basal circulating beta-EP was in normal range in all subjects, although the mean concentration was slightly reduced in the patients compared to controls. After 1 mg dexamethasone given at 11:00 p.m. the night before, plasma beta-EP concentration measured at 08:00 a.m. and 04:00 p.m. was not inhibited in AD and PD patients while it was significantly reduced in controls. Circulating ACTH and cortisol were similar in patients and controls and a normal inhibition of plasma cortisol after dexamethasone was observed in 13/14 AD and 12/14 PD patients. The resistance of beta-EP to dexamethasone inhibition is consistent with previous clinical and experimental data indicating a disorder of the opiate system in brain degenerative diseases.

Inhibitory effect of somatostatin on abnormal GH response to TRH in primary hypothyroidism.

Thyrotropin releasing hormone (TRH) does not promote GH secretion in normal subjects but it stimulates GH in a proportion of hypothyroid patients. In this study the response of GH to thyrotropin releasing hormone (TRH) was evaluated in 21 patients with primary hypothyroidism of different origin: 12 with autoimmune thyroiditis, 3 idiopathic, 3 congenital, 3 iatrogenic. 11 of these patients had never been treated, the others were tested after a drug-free period of at least two weeks. Basal plasma concentration of GH was normal in all patients; after TRH administration, a significant increase in plasma GH was observed in 4 patients. In these responsive patients, somatostatin infusion inhibited the abnormal GH response to TRH. It is suggested that the abnormal GH response to TRH in primary hypothyroidism might be caused by a relative deficiency of somatostatinergic control, which is corrected by exogenous somatostatin administration.

Endogenous cytokine antagonists during myocardial ischemia and thrombolytic therapy.

We tested the idea that cytokine antagonists are released during acute myocardial ischemia to counteract proinflammatory effects of cytokines. We investigated changes in plasma concentrations of the anticytokine molecules alpha-melanocyte-stimulating hormone (alpha-MSH), interleukin-1 receptor antagonist (IL-1ra), and soluble tumor necrosis factor receptor (sTNFr) in patients with acute myocardial infarction (AMI) or unstable angina (UA). Blood samples were collected at presentation in the coronary care unit, at 3-hour intervals for 24 hours, and daily for 4 days thereafter. There were no significant differences in the concentrations of cytokine antagonists in patients with AMI or UA. However, whereas concentrations of alpha-MSH were increased in early samples of patients with AMI or UA who were treated with a thrombolytic agent, they were consistently low in untreated patients. IL-1ra concentrations likewise were greater 3 and 6 hours after treatment in patients who underwent thrombolysis, whereas there was no significant difference in plasma sTNFr between the two groups. We suggest that during myocardial ischemia and thrombolysis anticytokine molecules released from the injured myocardium become available to reduce inflammation caused by cytokines and other mediators of inflammation.

The anticytokine neuropeptide alpha-melanocyte-stimulating hormone in synovial fluid of patients with rheumatic diseases: comparisons with other anticytokine molecules.

The aim of this study was to determine if the anticytokine neuropeptide alpha-melanocyte-stimulating hormone (alpha-MSH) occurs, along with interleukin 1 receptor antagonist (IL-1ra) and soluble tumor necrosis factor receptor (sTNFr), in synovial fluid of patients with rheumatoid arthritis (RA), juvenile chronic arthritis (JCA), or osteoarthritis. The data show that alpha-MSH does occur in the synovial fluid and its concentrations are greater in patients with RA than in those with osteoarthritis. Synovial fluid concentrations of IL-1ra and sTNFr were likewise greater in RA. Further, concentrations of alpha-MSH, IL-1-ra, and sTNFr were greater in patients with polyarticular/systemic-onset JCA than in those with pauciarticular disease, that is in patients with greater joint inflammation. Concentrations of alpha-MSH were greater in synovial fluid than in plasma in a substantial proportion of patients, suggesting local production of the peptide; this is the first indication that the anticytokine molecule alpha-MSH is produced within a site of inflammation. Further, it appears that local production of alpha-MSH is induced particularly in those arthritic joints that have more intense inflammatory reactions. This finding, combined with previous evidence of the marked anti-inflammatory activity of alpha-MSH, suggests that the peptide acts locally to modulate proinflammatory influences in rheumatic diseases.

ACTH and cortisol secretion in patients with Alzheimer's disease.

The "glucocorticoid cascade hypothesis" for pathological ageing of the brain is supported by strong experimental data, but the clinical correlates are far less clear. The basal ACTH and cortisol secretion have been studied before and after the dexamethasone suppression test in patients in the early stages of clinically probable Alzheimer's disease and in controls, and the results were all normal. These findings do not support the hypothesis that the pathological brain ageing of Alzheimer's type is caused by hyperactivity of the pituitary-adrenal axis.

N -butyldeoxynojirimycin reduces growth and ganglioside content of experimental mouse brain tumours.

Abnormalities in glycosphingolipid (GSL) biosynthesis have been implicated in the oncogenesis and malignancy of brain tumours. GSLs comprise the gangliosides and the neutral GSLs and are major components of the cell surface glycocalyx. N -butyldeoxynojirimycin (N B-DNJ) is an imino sugar that inhibits the glucosyltransferase catalysing the first step in GSL biosynthesis. The influence of N B-DNJ was studied on the growth and ganglioside composition of two 20-methylcholanthrene-induced experimental mouse brain tumours, EPEN and CT-2A, which were grown in vitro and in vivo. N B-DNJ (200 microM) inhibited the proliferation of the EPEN and CT-2A cells by 50%, but did not reduce cell viability. The drug, administered in the diet (2400 mg kg(-1)) to adult syngeneic C57BL/6 mice, reduced the growth and ganglioside content of subcutaneous and intracerebral EPEN and CT-2A tumours by at least 50% compared to the untreated controls. N B-DNJ treatment also shifted the relative distribution of tumour gangliosides in accordance with the depletion of metabolic substrates. Side effects of N B-DNJ treatment were generally mild and included reductions in body and spleen weights and intestinal distension. We conclude that N B-DNJ may inhibit tumour growth through an effect on ganglioside biosynthesis and may be useful as a new chemotherapy for brain tumours.

Proopiomelanocortin-derived peptides and cytokines: relations in patients with acquired immunodeficiency syndrome.

alpha-Melanocyte-stimulating hormone (alpha-MSH), adrenocorticotrophic hormone (ACTH), beta-endorphin, cortisol, and the cytokines interleukin 1 beta (IL-1 beta), interleukin 6 (IL-6), and tumor necrosis factor alpha (TNF alpha) were measured in 80 AIDS patients (group IV CDC) and in healthy hospital personnel. The average plasma alpha-MSH was significantly greater in AIDS patients than in control subjects; no significant differences between groups were observed in the average concentrations of ACTH, cortisol, and beta-endorphin; plasma cytokines were likewise similar in the two groups. Plasma concentrations of alpha-MSH and ACTH were inversely related in AIDS patients and a similar inverse relation between alpha-MSH and IL-6 was also observed in these patients. There were positive relations among elevated circulating ACTH, cortisol, IL-6, and high fever in AIDS patients with severe concomitant disease. Plasma alpha-MSH concentrations within a specific range correlated positively with 6 month survival. Because cytokines can stimulate HIV expression in certain cell types and they are believed to have a role in disease progression in HIV-infected patients, it may be that a potent endogenous modulator of cytokine action such as alpha-MSH is crucial to survival in these patients.

Plasma concentration of cytokine antagonists in patients with HIV infection.

There is increasing evidence that cytokines contribute to the immunopathogenesis of human immunodeficiency virus (HIV) infection. It may be, therefore, that compensatory rises in circulating cytokine antagonists also occur in HIV infection and that such changes mark disease progression. To test this idea, plasma concentrations of the cytokine antagonists alpha-melanocyte-stimulating hormone (alpha-MSH), interleukin-1 receptor antagonist (IL-1ra), and soluble tumor necrosis factor receptor (sTNFr) were measured in patients of different Centers for Disease Control (CDC) categories of HIV infection and in seronegative controls. Plasma levels of all these cytokine antagonists were higher in HIV-infected patients. IL-1ra and sTNFr concentrations were correlated with indicators of disease activity: positively with plasma neopterin and negatively with CD4+ T lymphocyte counts. alpha-MSH and sTNF r were greater in CDC groups III and IV, whereas IL-1ra was elevated only in the latter group. Because cytokines activate the hypothalamic-pituitary-adrenal axis and adrenal steroids inhibit cytokine production, we measured circulating adrenocorticotropic hormone (ACTH) and cortisol in HIV-infected patients and investigated relations among these hormones, cytokine antagonists, and markers of disease progression. It appears that these physiological modulators of cytokine activity are not closely linked to sTNFr, IL-1ra and alpha-MSH: there were no significant correlations between plasma concentrations of ACTH or cortisol and those of cytokine antagonists, nor were there correlations between hormones and markers of disease progression such as neopterin or CD4+ T cell counts. It is notable that severe adrenal insufficiency was extremely rare (3%) in HIV-infected patients; it was confined to the AIDS group and was consistently secondary to ACTH deficiency.(ABSTRACT TRUNCATED AT 250 WORDS)