Immunosuppressive activity of 13-cis-retinoic acid and prevention of experimental autoimmune encephalomyelitis in rats.

Some activities of retinoids on cellular and humoral immunity have been described, but the available data are conflicting or obtained at concentrations that are toxic in vivo. In this study, we demonstrate that 13-cis-retinoic acid (13-cRA), a retinoid well tolerated in human therapy, can suppress T cell-mediated immunity in rats. Treatment with pharmacological concentrations of 13-cRA prevented active as well as passive transfer experimental autoimmune encephalomyelitis (EAE) and suppressed lymphocyte responsiveness to T cell mitogens, suggesting that the drug activity included suppression of an effector T cell response. In addition, mitogen- and antigen-induced lymphocyte proliferation was inhibited in vitro in the presence of concentrations of 13-cRA equivalent to or less than those achieved in vivo, further suggesting that the prevention of EAE was due to a suppressive activity on T cell-mediated immunity. The immunosuppressive activity of 13-cRA included suppression of interleukin 2, whose production was inhibited in splenocytes. These data indicate that, in an in vivo mammalian system, 13-cRA exerts a suppressive activity on T cell-mediated immunity intensive enough to suppress an ongoing immune response, and that this effect can be achieved at nontoxic concentrations that may also be attained in human therapy.

Presence of activated T-cells with a T8+ M1+ Leu 7+ surface phenotype in invaded lymph nodes from patients with solid tumors.

The lymphocyte surface phenotype of lymph nodes from patients with larynx or urinary bladder carcinoma was investigated by using a panel of monoclonal antibodies. The phenotype pattern of lymphocytes from lymph nodes invaded by malignant cells (as assessed by histopathology) was different from that of the cells from noninvaded or normal control nodes. Although the proportion of natural killer cells or macrophages was similar in the 3 groups of lymph nodes, invaded lymph nodes contained a higher proportion of T-cells and a lower B-cell percentage. Furthermore, cells from invaded nodes comprised 15-20% of T3+ T8+ cells that coexpressed the M1 marker and, to some extent, also the Leu 7 marker. A large proportion of cells with multiple markers were activated, as shown by the expression of Tac and HLA-DR antigens. In 2 patients activated T8+ cells expressing also M1 and Leu 7 markers infiltrated the tumor site. The presence of these activated cells both in involved nodes and tumor mass may indicate that they originate in response to cancer.

Molecular models of small phosphorylated chromatin peptides. Structure-function relationship and regulatory activity on in vitro transcription and on cell growth and differentiation.

We previously reported the isolation of low molecular weight phosphorylated peptides from the chromatin of several tissues. The chromatin peptides show a regulatory activity on DNA in vitro transcription and on cell growth and differentiation. In this paper, we report a molecular model of the native peptides designed according to the structural information obtained by means of biochemical and mass spectrometry analysis: pyroGlu-Ala-Gly-Glu-Asp-Ser(P)-Asp-Glu-Glu-Asn. This or very similar sequences are present in many transcription factors; on the basis of the structural model we presented and of related protein sequences, we have synthesized the peptide pyroGlu-Asp-Asp-Ser-Asp-Glu-Glu-Asn. This peptide affects transcription rate in reconstituted systems in vitro and in isolated nuclei; moreover, it inhibits the growth of HL60 cells with a parallel stimulus of differentiation.

Circadian oscillations of DNA synthesis in rat brain.

The possibility that the synthesis of brain DNA undergoes a circadian fluctuation was examined in male adult Wistar rats, kept under natural lighting conditions or born and raised under artificial lighting conditions. Groups of rats were taken every 4 h during the 24 h, injected subcutaneously with [methyl-3H]thymidine and killed 4 h later. By cosinor analysis, the DNA specific activity of cerebral hemispheres and brainstem was found to show a significant 24 h rhythm with the peak at the beginning of the dark period (waking period). By contrast, in kidney, the peak of the circadian rhythm of DNA specific activity occurred during the light period (sleep period), in agreement with literature data. On the other hand, in 4-week-old rats, born and raised in artificial lighting conditions, brain DNA specific activity followed a 12 h rhythm, in agreement with the lack of a significant diurnal oscillation of the sleep--waking structure. It is concluded that brain DNA synthesis undergoes a circadian fluctuation in association with the circadian rhythm of waking.

Paradoxical sleep deprivation of the mother enhances DNA synthesis in fetal rat brain: autoradiographic and biochemical evidence.

Pregnant rats were deprived of paradoxical sleep for 3 days starting on the 18th gestational day. The condition of PS-D was imposed by confinement on a small platform surrounded by water or by daily injections of clomipramine. Four hours before the killing rats received a s.c. injection of [3H]-thymidine. The amount of radioactive DNA determined by autoradiography in several regions of fetal brain was found to be markedly increased under both experimental conditions in comparison with the control fetal brain. Considerably more limited effects were observed in kidney. Comparable changes of lower magnitude were obtained by comparing the specific radioactivity of DNA samples purified by chlorophorm extraction and digestion with RNase and proteinase K. The results fully confirm our previous data obtained under similar experimental conditions but based on the analysis of an acid-washed DNA fraction.

Activation of phosphatidylserine synthesis: a possible mechanism of regulation of the base-exchange enzymic system.

The possible relationship between phosphatidyl serine synthesis by base-exchange and nervous activity has been investigated in the rat caudate nucleus. The rate of incorporation of L-serine into the phosphatidyl serine of slices from caudate nucleus is not affected by dopamine nor is it affected by the addition to dopamine of a cyclic phosphodiesterase inhibitor which would increase the endogenous cyclic-AMP levels. However, imidazole, a phosphodiesterase activator, clearly stimulates by more than 100% the phosphatidyl serine synthesis in the slices. The activation is not due to interaction at the catalytic site(s) of the base-exchange system, since it is neither observed in homogenates of caudate nucleus nor in cerebral microsomes at various pH values.

Changes in enzyme levels in human skeletal muscle during obstructive arteriopathy of the lower limbs.

Some enzymatic activities have been assayed in the gastrocnemius muscle of patients with obstructive arteriopathy of the lower limbs. The specific activities of all the examined glycolytic enzymes, of malate dehydrogenase and of glycerol-3-phosphate dehydrogenase are significantly decreased while the specific activities of two lysosomal enzymes, beta-glucuronidase and cathepsin A, are significantly higher than in the controls. Therefore it may be inferred that the metabolic capacity of glycolysis and of Krebs cycle are lowered. On the other hand the increased specific activity of lysosomal enzymes suggests the hypothesis that the above mentioned modifications and the morphologic alterations of the muscle and of the small blood vessels might be ascribed, at least partly, to a release of lysosomal hydrolases in active form.

Small acidic peptides from wheat germ chromatin. II. Regulatory activity in specific transcription systems reconstituted in vitro.

A variety of evidence suggests that a family of chromatin peptides (CPs), characterized by 1000D molecular weight, a pH dependent association to DNA and a prevailing presence of acidic amino acids in their structure, is involved in the regulation of genes expression. Nevertheless their action mechanism is still unknown. In our in vitro specific RNA transcription systems the CPs affect the initiation and not the elongation. Furthermore they inhibit the RNA transcription by interaction with the DNA rather than with the enzyme. The phagic in vitro specific RNA transcription is less affected by CPs than the eubacteric system, suggesting a kind of selectivity for target DNA sequences involved in the initiation of transcription.

Small acidic peptides from wheat germ chromatin. I. Isolation and biochemical characterization.

RNA synthesis in cell and cell-free systems is inhibited by a family of acidic, low molecular weight chromatin peptides (CPs). These peptides were extracted from deproteinized DNA of prokaryotic and eukaryotic cells, but the low yield of purified material by this procedure hinders efforts aimed at understanding their action mechanism in gene regulation. In this report we describe two purification methods of CPs from an easily available source, wheat germ. A comparison is made between the method starting from deproteinized DNA and the method from purified chromatin. The biological effects (inhibition of L1210 cell growth and DNA in vitro transcription) of CPs from wheat germ together with their chemical characteristics (molecular weight, amino acid composition and presence of phosphoserine) show strong homology with those of CPs from other sources. These results suggest a possible role of these chromatin peptides in controlling gene expression.

[Lysosomal lesions during a course of acute experimental muscular ischemia. Protective effect of a polypetitide proteinase inhibitor]. / Lesione lisosomiale in corso di ischemia muscolare acuta sperimentale. Effetto protettivo di un polipeptide inibitore delle proteinasi

Three groups of rabbits were used: a) with acute ischaemia in a rear limb; b) with acute ischaemia in a rear limb and treated with i.v. 100,000 KIU of a proteinase-inhibitor polypeptide extracted from ox lung; c) normal controls. Acute ischaemia was obtained by ligature of the ipsilateral common iliac, external iliac, inferior epigastric and femoral arteries. Soluble and total activity of 3 lysosomal enzymes (cathepsin, acid phosphatase and N-acetyl-glucosaminidase) were determined in gastrocnemius muscle from all 3 groups. The mean ratio between bound and soluble activity for all 3 enzymes in normal gastrocnemius muscle was higher than in ischaemic muscle, but not significantly different from that in ischemic muscle of animals treated with the polypeptide. Furthermore, this ratio in ischemic muscle was significantly lower than that of ischemic muscle of the rabbits treated with the polypeptide. These data suggest that the polypeptide offers protection against lysosomal lesion in the course of experimental ischaemia of the skeletal muscle.

[Preliminary data on the behavior of the enzyme of metabolism of phospholipid bases in human tumor preparations]. / Dati preliminari sul comportamento dell'enzima dello scambio delle basi fosfolipidiche in preparati di tumore umano.

The A.A. have investigated the phospholipids base-exchange enzyme system in the solid tumours in order to state if a correlation between this activity and the variation of the cellular ciclic nucleotides amount was possible considering that these compounds have been reported to undergo a variation in tumour compared with normal tissues. They report some previous results in a lung tumour and in an endometrial carcinoma, were they have found a big increase in the PhS synthesis. Such increase was possible to be seen in the endometrial carcinoma only after a stimulation by 17-beta-estradiol and it was reversed in this case by doxorubicine. These results suggest that an alteration of the PhS synthesis should be one of numerous peculiarity of the neoplastic cell.

[Changes in phosphatidylserine synthesis in human rectal tumors]. / Alterazioni nella sintesi di fosfatidilserina su alcuni tumori umani del retto.

We have investigated the phosphatidylserine metabolism in human adenocarcinoma. This phospholipid is involved in the regulation of several enzymic activities of plasma membranes; therefore it could be useful to state if some alteration of tumour membranes propriety depend on variation of phosphatidylserine synthesis. Our results make evident that in such human tumours the phosphatidylserine synthesis is greatly augmented.

The effect of silybin on liver phospholipid synthesis in the rat in vivo.

Female Wistar rats have been injected intravenously for seven days with various different doses of silybin, the main component of the drug silymarin, and the in vitro synthesis of phosphatidylethanolamine and phosphatidylcholine from their respective precursors, CDP-ethanolamine and CDP-choline has been examined in liver microsomal membranes. Appreciable inhibition of the incorporation rates of precursors into lipids has been noticed at dosage of 15-20 mg/100 g body wt., daily. No evident effect is exerted by similar silybin treatment on choline and ethanolamine incorporation respectively into liver phosphatidylcholine and phosphatidylethanolamine in vivo.

Novel immune deficiencies: defective transcription of lymphokine genes.

A 4-year-old female with severe combined immunodeficiency (SCID) had normal numbers of T cells in circulation and normal T cell subsets. However, her T cells proliferated poorly to mitogens and did not proliferate to antigens or to anti-CD3 mAb. Interleukin-2 (IL-2) receptor expression was normal but IL-2 synthesis was undetectable. The addition of recombinant IL-2 to a mitogen-stimulated culture resulted in normalization of the proliferative response. Northern blot analysis of total RNA derived from the patient's T cells revealed a weak or absent expression of mRNA coding for IL-2, IL-3, IL-4, and IL-5. In contrast, there were normal amounts of mRNA coding for granulocyte-macrophage colony-stimulating factor (GM-CSF). Tumor necrosis factor and IL-6 production was also normal. Nuclear run on transcriptional assays revealed markedly decreased levels of newly initiated nuclear transcripts coding for IL-2, IL-3, IL-4, and IL-5 and normal levels of GM-CSF transcripts in patient relative to control lymphocytes. These results indicate that the patient's T cells suffered from a defect affecting the transcription of multiple T cell lymphokines and suggest that abnormalities affecting the production of T cell lymphokines may underlie some of the primary immunodeficiency diseases.

Competition between citrate and heptapeptide DDSDEEN binding to DNA in presence of divalent cations.

The binding of citrate and acidic peptide DDSDEEN with DNA in the presence of divalent cations is compared. Citric acid shows a higher number of binding sites on the DNA compared to the peptide; this is probably due to the bigger sitric hindrance of the peptide compared to the citric acid for the binding in the DNA grooves. Moreover. DNA preincubated with saturating amounts of citric acid is not available for the binding with successively added peptide. Therefore the peptide and citrate binding sites to some extent overlap.

Severe combined immunodeficiency with selective T-cell cytokine genes.

A 4-y-old female with severe combined immunodeficiency disease had normal numbers of T cells in her circulation and normal T-cell subsets. However, her T cells proliferated poorly to mitogens and did not proliferate to antigens or to anti-CD3 MAb. IL-2 receptor expression was normal, but IL-2 synthesis was undetectable. The addition of recombinant IL-2 to a mitogen-stimulated culture resulted in normalization of the proliferative response. Northern blot analysis of total RNA derived from the patient's T cells revealed a weak or absent expression of mRNA coding for IL-2, IL-3, IL-4, and IL-5. In contrast, there were normal amounts of mRNA coding for granulocyte-macrophage colony-stimulating factor. Tumor necrosis factor and IL-6 production were also normal. Nuclear run-on transcriptional assays revealed markedly decreased levels of newly initiated nuclear transcripts coding for IL-2, IL-3, IL-4, and IL-5 and normal levels of granulocyte-macrophage colony-stimulating factor transcripts in the patient relative to control lymphocytes. Gel retardation assays suggest that the NFAT-1 nuclear transcription complex is abnormal in this patient. These results indicate that the patient suffers from a defect that affects the transcription of multiple T-cell lymphokines and suggest that abnormalities affecting the production of T-cell lymphokines may underlie some of the primary immunodeficiency diseases.

A protein of the AP-1 family is a component of nuclear factor of activated T cells.

Nuclear factor of activated T cells (NF-AT) is a transcriptional activator involved in the induction of IL-2 gene expression. The response element for NF-AT is a sequence localized between -285/-254 in the IL-2 regulatory region. The composition of NF-AT protein is still not fully elucidated. We demonstrate that, in normal human T cells, an AP-1 protein is a component of the NF-AT protein complex. This was evidenced by the ability of the AP-1 site to compete with the NF-AT site for binding to NF-AT and by the capacity of immobilized anti-Jun and anti-Fos antibodies to deplete NF-AT-binding activity from nuclear extracts of activated T cells. There was no detectable binding of in vitro translated Jun/Fos heterodimer (AP-1) to the NF-AT sequence, and the NF-AT sequence was unable to inhibit the binding of Jun/Fos to the AP-1 sequence. The presence of an AP-1 protein in the NF-AT protein complex may regulate NF-AT-binding activity through protein-protein interaction.

[Preliminary data on activation of the enzyme of the metabolism of phospholipid bases in various areas of the brain]. / Dati preliminari sull'attivazione dell'enzima dello scambio delle basi fosfolipidiche in varie aree cerebrali.

The scope of this work was to study the effect of imydazole on base-exchange enzymic system in selected cerebral areas. We have previously demonstrated that imydazole was an activator of phosphatidylserine synthesis in slices of caudate nucleus. This effect lacked in the omogenate we had supposed that this activation by imydazole was not directed on base-exchange enzymic system, but was induced by decrease of cellular cyclic nucleotides amount. Therefore we have investigated the effect of dibutirril-AMPciclic in selected cerebral areas. In addition it was useful to state if activation by imydazole was area-specific or not.

Possible specific activation of RNA synthesis in PC-12 cell isolated nuclei by small acidic peptides.

Three synthetic peptides, pyro-Glu-Ala-Gly-Glu-Ser-Glu-Asp (Pep A), pyro-Glu-Ala-Gly-Glu-Glu-Glu-Ser-Asn (Pep B), and pyro-Glu-Asp-Asp-Ser-Asp-Glu-Glu-Asn (Pep C), bear sequences possibly belonging to components of a naturally occurring family of strongly related small acidic chromatin peptides involved in regulation of gene expression. In a crude nuclear fraction and in purified nuclei from PC-12 cells, Pep A and Pep B activate RNA synthesis, specifically acting on the RNA polymerase II transcription system. On the other hand, Pep C shows an inhibitory effect on RNA synthesis in purified nuclei but an activation in the crude nuclear fraction. Control experiments show that the serum thymic factor does not affect RNA synthesis in the crude nuclear fraction or in purified nuclei. A possible regulation by peptide phosphorylation via casein kinase II (more active in purified nuclei than in the crude nuclear fraction) is discussed.