Induced myeloperoxidase activity and related superoxide inhibition during hormone replacement therapy

OBJECTIVE

To test whether the menopause entails any changes in the myeloperoxidase activity of neutrophil granulocytes. The effects of hormone replacement therapy on myeloperoxidase activity and related changes in free radical production were also investigated.

DESIGN

Laboratory investigation of the effect of oestrogen on intracellular myeloperoxidase activity and release from human neutrophil granulocytes. Analysis of related changes in superoxide anion generation.

SETTING

2nd Department of Medicine and 1st Department of Obstetrics and Gynaecology, Semmelweis University, Budapest.

SAMPLES

Intracellular myeloperoxidase activity (mean peroxidase index) was measured automatically in blood samples obtained for general laboratory work-up from 135 randomly selected patients in our department. Blood samples from 11 postmenopausal women were analysed before and during hormone replacement therapy. Blood samples from 20 healthy volunteers were obtained and neutrophil granulocytes separated for in vitro measurement of superoxide anion production after adding myeloperoxidase to the incubation media.

METHODS

The mean peroxidase index was measured using a Technicon H-3 instrument. myeloperoxidase release from neutrophils was quantified by ELISA technique. Superoxide production of isolated neutrophil granulocytes was measured by photometry.

MAIN OUTCOME MEASURES

Intracellular activity of myeloperoxidase, concentration of myeloperoxidase-protein in supernatant of neutrophils, release of superoxide anion from neutrophil granulocytes.

RESULTS

1. Intracellular myeloperoxidase activity in neutrophils was lower in postmenopausal women, than in females with regular cycles (-1.84 +/- 3.06 versus 1.59 +/- 3.55, P < 0,001). 2. In postmenopausal women intracellular myeloperoxidase activity and myeloperoxidase release increased during hormone replacement therapy (-5.54 +/- 6.63 versus -0.2 +/- 6.05; P < 0.001 and 52.74 mU/ml +/- 25.73 versus 251.4 +/-234.1 mU/ml; P < 0.05). 3. Adding myeloperoxidase to neutrophil granulocyte suspensions, the production of superoxide anion fell (e.g. adding 280 ng/ml myeloperoxidase: 77.9 +/- 14.04 % of control production, P < 0.001).

CONCLUSION

Hormone replacement restores the reduced myeloperoxidase activity in menopausal women. Adding myeloperoxidase to neutrophil granulocytes, the production of free radicals decreases.

Effect of transforming growth factor-beta1 on microglial MHC-class II expression

In the present report, the effects of IFN-gamma and transforming growth factor beta1 (TGF-beta1) on major histocompatibility complex class II (MHC-II) gene expression in isolated mouse brain microglial cells, in the MH-S macrophage cell line and in the primary mouse macrophage cultures were examined. IFN-gamma is a potent inducer of MHC-II gene and this induction was further elevated in microglia by TGF-beta1, while TGF-beta1 inhibited IFN-gamma, induction in macrophages. The enhancing effect of TGF-beta1 was also detected in microglia at the protein level. Transient transfection of microglia with 5' deletional mutants of the MHC-II IAalpha promoter linked to the chloramphenicol acetyltransferase reporter gene demonstrated that TGF-beta1 acts at the transcriptional level to enhance the MHC-II expression induced by IFN-gamma.

Differential regulation of major histocompatibility complex class II expression and nitric oxide release by beta-amyloid in rat astrocyte and microglia

Astrocytes and microglial cells were examined for expression of two immunologically important molecules, major histocompatibility complex class II (MHC-II) and nitric oxide (NO) following treatment with IFN-gamma and beta-amyloid (betaA) peptides, betaA(1-42) and betaA(25-35). IFN-gamma is a potent inducer of both MHC-II gene expression and NO production. The induction of MHC-II was inhibited by both betaA peptides in astrocytes but they had little or no effect in microglia. betaA peptides had no effect on NO release in astrocytes but on microglia betaA(1-42) synergistically induced NO release with IFN-gamma. Transient transfection of astrocytes with 5' deletional mutants of MHC-II IAalpha promoter linked to the chloramphenicol acetyl transferase reporter gene (IAalpha-CAT), demonstrated that betaA acts at the transcriptional level to downregulate IFN-gamma induced MHC-II gene expression in astrocytes. In previous studies, the induction of MHC-II on glial cells were suggested to be involved in the pathogenesis of neurodegenerative diseases and MHC-II(+) microglial cells were observed at much higher frequency than astrocytes. This study provides information on the regulation of the MHC-II gene expression in astrocytes and in microglial cells by betaA and this pathway may be critically involved in the immune/inflammatory regulation within the central nervous system.

Repression of MHC class II gene transcription in trophoblast cells by novel single-stranded DNA binding proteins

The maintenance of the fetus during pregnancy has been attributed to the absence of major histocompatibility complex (MHC) class II antigens on fetal trophoblastic cells that make contact with the maternal immune system. However, the mechanism(s) by which class II genes are regulated in trophoblast cells is unclear. We have identified a negative regulatory element (IA alpha NRE) in the promoter of the mouse class II gene IA alpha that represses IA alpha transcription in trophoblast cells. IA alpha NRE, located from-839 to -828, binds transacting factors from rat, mouse and human trophoblast cells, but not from 18 other cell lines tested. These results indicate that IA alpha NRE binding proteins (IA alpha NRE BPs) are conserved in species with hemochordial placentas, and suggest that IA alpha NRE binding activity is restricted primarily to trophoblast cells. Interestingly, the IA alpha NRE BPs bind to the IA alpha NRE antisense strand in a sequence-specific manner. IA alpha NRE represses transcription from the IA alpha promoter in a position-dependent manner, and has a minor down-regulatory effect on the activity of the SV40 promoter/enhancer. Our results demonstrate that MHC class II gene transcription is repressed in fetal trophoblast cells by sequence-specific, single-stranded DNA binding proteins, and suggest a possible mechanism by which the conceptus is protected from immune rejection during pregnancy.

Activation of multiple transcription factors and fos and jun gene family expression in cells exposed to a single electric pulse

We report that exposure of cells to a single electric pulse (250-1250 V/cm) results in the rapid and persistent activation of the DNA binding activities of a number of transcription factors, including AP-1, SP1, AP-2, and NF-kappa B, and the transient expression of select members of the fos and jun gene families. Induction of gene expression occurs primarily at the level of transcription, although c-jun expression also appears to be regulated posttranscriptionally. Interestingly, maximal induction of gene expression is detected at electrical field strengths that do not result in pore formation in the plasma membrane and that do not significantly affect cell viability. Exposure of cells to electric pulses does not result in the activation of HSF1 DNA binding activity, or the induction of hsp70 or p53 protein synthesis, indicating that the induction of fos and jun gene expression is not coincident with protein or DNA damage. The results of these studies suggest that electrical pulses may represent a novel mechanism for inducing the activities of multiple transcription factors and the expression of select members of the fos and jun gene families.

No evidence for human T-cell leukemia virus type I or human T-cell leukemia virus type II infection in patients with multiple sclerosis

The involvement of human T-cell leukemia viruses (HTLVs) in the pathogenesis of 18 Hungarian patients with multiple sclerosis was investigated. No antibody to HTLVs could be detected in any of the patients. Furthermore, using polymerase chain reaction under highly sensitive conditions, neither HTLV-I DNA nor HTLV-II DNA could be noted in peripheral blood lymphocytes of the patients. Our data do not support a causal association of HTLV-I or HTLV-II with multiple sclerosis.