Ovarian steroid production in rats treated with gonadotropin-releasing hormone during early pregnancy

In the pregnant rat, luteinizing hormone (LH) stimulates the ovarian production of testosterone (T) which is aromatized to estradiol (E2). E2 promotes progesterone (P) synthesis by the ovary. To determine if the administration of gonadotropin-releasing hormone (GnRH) disrupts pregnancy by suppressing ovarian steroid production, rats were treated on days 7-12 of pregnancy with 25, 50 or 100 micrograms/day of GnRH or 0.2, 1 or 5 micrograms/day of a GnRH agonist (GnRH-Ag). The higher two doses of GnRH or GnRH-Ag within 24 h suppressed peripheral levels of plasma P and terminated pregnancy within 48 h. By day 12, P levels in the ovarian vein in rats treated with GnRH or GnRH-Ag in respective doses were 2098 +/- 261, 732 +/- 437, 110 +/- 15, and 2575 +/- 463, 49 +/- 9, 43 +/- 8 compared to 1833 +/- 433 ng/ml in controls. Daily treatment of P (4 mg) and E2 (0.5 microgram) simultaneously with GnRH-Ag at its maximum dose reversed the abortifacient effect of GnRH-Ag and maintained pregnancy. Peripheral levels of Plasma LH in all groups were higher than controls on days 10 and 12. Ovarian vein levels of T on days 10 or 12 of pregnancy were either not significantly different from controls (at 2703 +/- 607 or 3249 +/- 690 pg/ml, respectively) or increased dramatically to 9547 +/- 1769 on day 10 and to 5985 +/- 1426 pg/ml on day 12 in rats treated with 0.2 microgram of GnRH-Ag. Similarly, ovarian vein levels of E2 on days 10 or 12 were either not significantly different from controls (at 2022 +/- 227 or 2793 +/- 184 pg/ml, respectively) or increased dramatically to 2980 +/- 58 pg/ml on day 10 in rats treated with 25 micrograms of GnRH or to 3296 +/- 241 on day 10 and to 3420 +/- 325 pg/ml on day 12 in rats treated with 0.2 microgram of GnRH-Ag. These results indicate that the abortifacient effect of GnRH administration in rats is not due to its effect on the uterus, but to its suppressive effects on ovarian P secretion. There was no evidence to show that a GnRH-induced fall in ovarian secretion of either T or E2 were involved in this process.     

Gonadotropin-releasing hormone-agonist inhibits synthesis of nitric oxide and steroidogenesis by luteal cells in the pregnant rat

We have demonstrated that continuous administration of a gonadotropin-releasing hormone agonist (GnRH-Ag) in vivo suppressed progesterone production and induced apoptosis in the corpus luteum (CL) of the pregnant rat. To investigate the mechanism(s) by which progesterone secretion is suppressed and apoptosis is induced in the luteal cells, we studied nitric oxide (NO) as a messenger molecule for GnRH action. Rats were treated individually on Day 8 of pregnancy with 5 microg/day of GnRH-Ag for 4, 8, and 24 h. GnRH-Ag decreased the production of progesterone and pregnenolone 8 and 24 h after the administration. Corresponding with the reduction in these steroid hormones, luteal NO concentrations decreased at 8 and 24 h. Western blotting and immunohistochemical studies of endothelial nitric oxide synthase (eNOS), inducible nitric oxide synthase (iNOS), and neuronal nitric oxide synthase (nNOS) in the CL demonstrated that administration of GnRH-Ag was associated with a marked decrease in eNOS and iNOS compared with sham controls at 4 and 8 h, but nNOS did not change throughout the experimental period. We demonstrated, for the first time, the presence of nNOS protein in the CL of the pregnant rat. To determine if this suppressive action of GnRH-Ag is directly on the CL, luteal cells were treated with GnRH-Ag for 4, 8, 12, and 24 h in vitro. Progesterone and NO concentrations in the media decreased at 8 and 12 h after the treatment and recovered at 24 h. Western blots revealed that eNOS and iNOS decreased in luteal cells treated with GnRH-Ag compared with controls at 4 and 8 h. These results demonstrate that suppression of luteal NO synthesis by GnRH-Ag is direct and leads to a decrease in the luteal production and release of progesterone and pregnenolone and thus suggest that GnRH could induce luteolysis in pregnant rats via NO.     

Effects of gonadotropin-releasing hormone treatment on ovarian steroid production during midpregnancy

During the second half of pregnancy, ovarian testosterone (T) through its conversion to estradiol (E) promotes progesterone (P) synthesis by the ovary which maintains the pregnancy. To determine if the administration of gonadotropin-releasing hormone (GnRH) disrupts pregnancy by suppressing ovarian production of T or its conversion to E, rats were treated from Day 11 through Day 18 of pregnancy with 50 or 100 micrograms/day of GnRH or 1, 5, or 10 micrograms/day of a GnRH agonist (GnRH-Ag; WY-40972) using an osmotic minipump. Rats were bled daily from the jugular vein under light ether anesthesia and on Days 14 or 18 of pregnancy both jugular and ovarian blood samples were obtained. While the GnRH-Ag treatment at the dose of 5 or 10 micrograms/day terminated pregnancy within 48 hr as indicated by vaginal bleeding, 1 microgram/day terminated pregnancy more slowly. Neither dose of GnRH was effective in terminating pregnancy through Day 18. By Day 14, peripheral levels of plasma P in rats treated with 0, 1, 5, or 10 micrograms of GnRH-Ag were 97 +/- 9, 24 +/- 1, 13 +/- 3, and 8 +/- 1, respectively. In the same groups, levels in the ovarian vein were 3205 +/- 633, 1317 +/- 273, 360 +/- 113, and 228 +/- 73 ng/ml. By Day 18, serum P levels in the peripheral circulation and in the ovarian vein were declining even more dramatically. Daily administration of P (4 mg) and E (0.5 micrograms) simultaneously with GnRH-Ag at the dose of 5 micrograms/day from Days 11 through 14 reversed the abortifacient effect of GnRH-Ag and maintained pregnancy indicating that the GnRH-Ag effect is not directly on the uterus. Ovarian vein levels of T on Days 14 or 18 of pregnancy were either not different from controls at 1407 +/- 163 or 1476 +/- 122 pg/ml, respectively, or increased dramatically in certain groups. Ovarian vein levels of E were either not different from controls at 292 +/- 13 pg/ml on Day 14 or increased significantly in rats treated at the dose of 1 microgram/day of GnRH-Ag. However by Day 18, treatment with GnRH-Ag at all doses suppressed ovarian secretion of E. These results suggest that while the GnRH-Ag induces abortion in rats by suppressing ovarian production of P, this abortifacient effect is not due to a fall in ovarian T levels nor to its aromatization to E in the ovary.     

Role of hormone-controlled T-cell cytokines in the maintenance of pregnancy

Human CD4 T helper lymphocytes can be subdivided into at least three distinct functional subsets on the basis of their cytokine secretion profiles. One type of CD4+ lymphocyte, T helper 1 (Th1), produces interferon (IFN)-gamma and tumour necrosis factor beta, a second type (Th2) produces interleukin (IL)-4 and IL-5 and a third type (Th0) produces both Th1 and Th2 cytokines. The apparent paradox that embryos are not rejected by the maternal immune system despite the presence of paternal MHC histocompatibility antigens has been explained in mice by a Th2 switch at the level of the materno-fetal interface. We showed that some hormones enhanced during pregnancy can affect the development of Th1 and Th2 responses. Indeed, we found that progesterone promotes the production of IL-4 and IL-5, whereas relaxin promotes the production of IFN-gamma by T-cells. In addition, we showed that leukaemia inhibitory factor (LIF), which is essential for embryo implantation, associates with Th2 cells and is upregulated by IL-4 and progesterone. We also showed that LIF is down-regulated by Th1 inducers [IL-12, IFN-gamma and IFN-alpha]. Furthermore, we found a decreased production of LIF, IL-4 and IL-10 by decidual T-cells in women with unexplained recurrent abortions in comparison with women with normal gestation at the moment of voluntary abortion. The decreased production of LIF, IL-4 and IL-10 was not found in peripheral-blood T-cells. These results suggest that the local production of LIF and/or Th2 cytokines may contribute to the maintenance of pregnancy.     

Replacement of progesterone restores the nocturnal surge of prolactin following suppression with a gonadotropin-releasing hormone agonist during early pregnancy in the rat

Continuous administration of a GnRH agonist (GnRH-Ag) at a dose of 5 micrograms/day, commencing on day 7 of pregnancy resulted in the suppression of daily nocturnal surges of prolactin (PRL) on day 8, and serum progesterone (P4) levels with subsequent termination of pregnancy. Replacement with dydrogesterone, a synthetic analog of P4 at a dose of 4 mg/day s.c. restored the magnitude of nocturnal PRL surges. These data suggest that GnRH-Ag may act either at the level of the brain to suppress the nocturnal PRL surge, resulting in a fall in serum P4 levels or at the level of the corpus luteum itself or at both sites simultaneously to terminate pregnancy.     

Characterization of protective immunity induced against Schistosoma mansoni via DNA priming with the large subunit of calpain (Sm-p80) in the presence of genetic adjuvants

Despite advances in control via snail eradication and large-scale chemotherapy using praziquental, schistosomiasis continues to spread to new geographic areas particularly in sub-Saharan Africa. Presently, there is no vaccine for controlling this disease. We have concentrated on a functionally important schistosome antigen Sm-p80 as a possible vaccine candidate for schistosomiasis. Here we report the proliferation of spleen cells in response to the recombinant Sm-p80 protein and cytokine (IFN-gamma and IL-4) production by the splenocytes. These spleen cells were obtained from groups of mice that were vaccinated with a DNA vaccine formulation containing Sm-p80 and one of the Th-1 (IL-2 or IL-12) or Th-2 (GM-CSF, IL-4) enhancer cytokines. The splenocytes from the groups of mice vaccinated with Sm-p80 DNA in the presence of Th-2 enhancer cytokines showed moderate but detectable proliferation. The splenocytes obtained from mice vaccinated with Sm-p80 DNA with Th-1 enhancer cytokines IL-2 and IL-12 provided the highest proliferation. The IFN-gamma production by splenocytes was found to follow the similar pattern [(Sm-p80) < (Sm-p80 + IL-4) < (Sm-p80 + GMCSF) < (Sm-p80 + IL-12) < (Sm-p80 + IL-2)], as has been observed for the proliferation and protection data. However, the elevated IL-4 production was inversely correlated to Sm-p80-induced splenocyte proliferation or the protection. These results show again that protective immune response induced by Sm-p80 is of Th-1 type.     

Changes in rat luteal ultrastructure and P450scc mRNA and protein content after in vivo treatment with a gonadotropin-releasing hormone agonist

Previous studies have demonstrated that plasma progesterone levels decrease in pregnant rats treated in vivo with a gonadotropin-releasing hormone agonist (GnRH-Ag), without changes in testosterone or estradiol levels in ovarian vein plasma. The objective of this study was to determine the loci of GnRH-Ag disruption of progesterone synthesis by examining luteal mitochondria, lipid droplets, cellular composition, and P450 side-chain cleavage (P450scc) enzyme and mRNA content in the pregnant rat. On Day 7 or 11 of pregnancy, osmotic minipumps containing GnRH-Ag were implanted into 5-7 rats. Sham operations were performed on 5-6 controls at each time period. Five micrograms per day of GnRH-Ag were released for about 24 h, after which corpora lutea and jugular vein plasma were collected. The corpora lutea were prepared for microscopy or analyzed for P450scc enzyme and mRNA content. Plasma progesterone levels were measured by RIA. In those rats treated with GnRH-Ag, progesterone levels had decreased, and within the luteal cells, there was an increase in the number of lipid droplets and a decrease in the number of tubular cristae within the mitochondria. Concomitantly, P450scc enzyme and mRNA content decreased on both Day 8 and Day 12 of pregnancy. Also, GnRH-Ag treatment decreased the ratio of large to small steroidogenic luteal cells on Day 8 of pregnancy, but did not alter cellular ratios on Day 12 of pregnancy. These observations suggest that treatment with GnRH-Ag inhibits progesterone synthesis by decreasing the amount of P450scc mRNA and enzyme content, which may alter the mitochondrial cristae structure on Day 8 and Day 12 of pregnancy. The reduction in tubular cristae and P450scc enzyme in the mitochondria may account for the increase in lipid droplets, as less cholesterol is converted to pregnenolone. An additional mechanism of inhibition may be the reduction in the number of large steroidogenic luteal cells, which appear to be the major source of progesterone in the rat corpus luteum on Day 8 of pregnancy.     

Effects of six different cytokines on lymphocyte adherence to microvascular endothelium and in vivo lymphocyte migration in the rat

The first step in the migration of lymphocytes out of the blood is adherence of lymphocytes to endothelial cells (EC) in the postcapillary venule. It is thought that in inflammatory reactions cytokines activate the endothelium to promote lymphocyte adherence and migration into the inflammatory site. Injection of IFN-gamma, IFN-alpha/beta, and TNF-alpha into the skin of rats stimulated the migration of small peritoneal exudate lymphocytes (sPEL) into the injection site, and these cytokines mediated lymphocyte recruitment to delayed-type hypersensitivity, sites of virus injection, and in part to LPS. The effect of cytokines on lymphocyte adherence to rat microvascular EC was examined. IFN-gamma, IFN-alpha/beta, IL-1, TNF-alpha, and TNF-beta increased the binding of small peritoneal exudate lymphocyte (sPEL) to EC. IFN-gamma was more effective and stimulated adherence at much lower concentrations than the other cytokines. IL-2 did not increase lymphocyte adherence. LPS strongly stimulated lymphocyte binding. Treatment of EC, but not sPEL, enhanced adhesion, and 24 h of treatment with IFN-gamma and IL-1 induced near maximal adhesion. Lymph node lymphocytes, which migrate poorly to inflammatory sites, adhered poorly to unstimulated and stimulated EC, whereas sPEL demonstrated significant spontaneous adhesion which was markedly increased by IFN-gamma, IL-1, and LPS. Spleen lymphocytes showed an intermediate pattern of adherence. Combinations of IFN-gamma and TNF-alpha were additive in stimulating sPEL-EC adhesion. Depletion of sPEL and spleen T cells by adherence to IFN-gamma stimulated EC decreased the in vivo migration of the lymphocytes to skin sites injected with IFN-gamma, IFN-alpha/beta, TNF-alpha, poly I:C, LPS, and to delayed-type hypersensitivity reactions by 50%, and significantly increased the migration of these cells to normal lymph nodes, as compared to unfractionated lymphocytes. Thus the cytokines and lymphocytes involved in migration to cutaneous inflammation in the rat stimulate lymphocyte adhesion to rat EC in vitro, and IFN-gamma stimulated EC appear to promote the selective adhesion of inflammatory site-seeking lymphocytes.     

Cytokine kinetics in the plasma of monkeys infected with pathogenic and nonpathogenic simian and human immunodeficiency chimeric viruses at an early stage of infection

To evaluate the pattern of cytokines as a result of pathogenic and nonpathogenic SHIV infections in monkeys, we analyzed the cytokines interleukin (IL)-2, IL-4, IL-10, IL-12, and interferon (IFN)-gamma in the plasma of 8 monkeys infected with either pathogenic 89.6P or nonpathogenic NM-3rN chimeric viruses. The cytokine kinetics in the 89.6P-infected monkeys was characterized by increases of IL-2, IL-10, and to some extent IFN-gamma and a decrease of IL-12. Although that of NM-3rN-infected monkeys was characterized by an increase of IFN-gamma, and a transient decrease of IL-12. IL-4 was not detected in any of the monkeys. The results, therefore, showed a mixture of Th-1 and Th-2 cytokine profiles implying these cytokines are not clear enough to use as an index of the pathogenicity of the viruses at an early stage of infection.     

GnRH action on luteal steroidogenesis during pregnancy.

The results of our study presented here establishes that gonadotropin-releasing hormone (GnRH) acts directly on the corpus luteum, leading to suppressed production and release of progesterone and thus disrupting pregnancy. A GnRH-agonist (GnRH-Ag) treatment suppressed the luteal and serum progesterone levels. This suppression is neither mediated by a fall in ovarian testosterone production nor its conversion to estradiol. Although the treatment suppressed the nuclear estradiol-receptor content and binding sites for LH in the corpus luteum, it had no effect on the luteal binding sites for GnRH and prolactin within 24 h. GnRH-Ag augmented the plasma levels of luteinizing hormone, decreased the magnitude of nocturnal surges of prolactin, and had no effect on luteal cyclic adenosine 5'-monotriphosphate levels. Yet, the treatment had no effect on the luteal content of free cholesterol. We have also demonstrated, for the first time, the presence of steroidogenic acute regulatory protein and peripheral benzodiazepine receptor in the rat corpus luteum, and the suppression of these proteins by GnRH-Ag leads to reduced steroidogenesis by the corpus luteum. Concomitantly, P450 side-chain cleavage enzyme, its activity, and its mRNA content and 3beta-hydroxy-steroid dehydrogenase content in the corpus luteum decreased. The treatment suppressed the plasma levels of pregnenolone and 20alpha-dihydroprogesterone. These data suggest that the suppression of luteal steroidogenesis by GnRH-Ag may be due to its inhibitory effect on the cholesterol transport and/or on the enzymes involved in the steroidogenic pathway. Furthermore, based on other observations made in our laboratory, we propose a hypothesis that an endogenous GnRH is present in the corpus luteum/ovary during pregnancy in the rat and that this GnRH may play a physiological role in the regulation, maintenance, and/or termination of pregnancy.     

IL-10 is excluded from the functional cytokine memory of human CD4+ memory T lymphocytes

Epigenetic modifications, including DNA methylation, profoundly influence gene expression of CD4(+) Th-specific cells thereby shaping memory Th cell function. We demonstrate here a correlation between a lacking fixed potential of human memory Th cells to re-express the immunoregulatory cytokine gene IL10 and its DNA methylation status. Memory Th cells secreting IL-10 or IFN-gamma were directly isolated ex vivo from peripheral blood of healthy volunteers, and the DNA methylation status of IL10 and IFNG was assessed. Limited difference in methylation was found for the IL10 gene locus in IL-10-secreting Th cells, as compared with Th cells not secreting IL-10 isolated directly ex vivo or from in vitro-established human Th1 and Th2 clones. In contrast, in IFN-gamma(+) memory Th cells the promoter of the IFNG gene was hypomethylated, as compared with IFN-gamma-nonsecreting memory Th cells. In accordance with the lack of epigenetic memory, almost 90% of ex vivo-isolated IL-10-secreting Th cells lacked a functional memory for IL-10 re-expression after restimulation. Our data indicate that IL10 does not become epigenetically marked in human memory Th cells unlike effector cytokine genes such as IFNG. The exclusion of IL-10, but not effector cytokines, from the functional memory of human CD4(+) T lymphocytes ex vivo may reflect the need for appropriate regulation of IL-10 secretion, due to its potent immunoregulatory potential.     

The flavonoid,quercetin, differentially regulates Th-1 (IFNgamma) and Th-2 (IL4) cytokine gene expression by normal peripheral blood mononuclear cells

Flavonoids are plant metabolites that are dietary antioxidants and exert significant anti-tumor, anti-allergic, anti-inflammatory and anti-viral effects. It is generally accepted that Th-1 derived cytokines such as IL-2, IFNgamma and IL-12 promote cellular immunity while Th-2 derived cytokines such as IL-4, IL-5, IL-6 exert negative immunoregulatory effects on cellular immunity while upregulating humoral immunity. The molecular mechanisms underlying the biological activities of flavonoids have not been elucidated. We hypothesize that the flavonoid, quercetin, exert significant anti-viral and anti-tumor effects possibly by modulating the production of Th-1 and Th-2 derived cytokines. Peripheral blood mononuclear cells (PBMC, 1 x 10(6) cells/ml) from normal subjects were cultured with different concentrations of quercetin (0.5-50 microM) for 24-72 h and supernates were quantitated for IFN-gamma and IL-4 by ELISA and antiviral activity of IFNgamma by bioassay. FACS analysis was done to determine the number of IFN-gamma and IL-4 positive cells and RT-PCR was done to quantitate gene expression. Quercetin significantly induces the gene expression as well as the production of Th-1 derived IFNgamma and the downregulates Th-2 derived IL-4 by normal PBMC. Further, quercetin treatment increased the phenotypic expression of IFNgamma cells and decreased IL-4 positive cells by FACS analysis, which corroborate with protein secretion and gene expression studies. These results suggest that the beneficial immuno-stimulatory effects of quercetin may be mediated through the induction of Th-1 derived cytokine, IFNgamma, and inhibition of Th-2 derived cytokine, IL-4.     

Control of LMP7 expression in human endothelial cells by cytokines regulating cellular and humoral immunity

Formation of antigenic peptides by the multicatalytic proteinase complex (MPC, proteasome) is facilitated by incorporation of three subunits (LMP2, LMP7 and LMP10) that are inducible by IFN-gamma and TNF-alpha. These cytokines, or their functional homologues (e.g. TNF-beta), are released from many cells including Th(1)lymphocytes. To learn more about the relationship between control of cellular immunity and expression of LMP subunits, we measured LMP7 levels in human umbilical vein endothelial cells of cytokines promoting cellular immunity (IL-12, IFN-gamma, TNF-alpha) or humoral immunity (IL-10, IL-6). Little or no effect was seen when cells were exposed to IL-6, IL-10 or IL-12 alone. IFN-gamma upregulated LMP7 levels, as did TNF-alpha to a lesser extent. IL-10 downregulated IFN-gamma-induced increases in LMP7 levels, as did IL-12. The findings indicate that regulation of levels of LMP7 is similar to and may be coupled with that of other molecules required for MHC class I-dependent immunity, and depends primarily on cytokines released by Th(1)helper lymphocytes.     

Depletion of CD8+ cells abolishes the pregnancy protective effect of progesterone substitution with dydrogesterone in mice by altering the Th1/Th2 cytokine profile

One of the most remarkable immunological regulations is the maternal immune tolerance toward the fetal semiallograft during pregnancy, which has been referred to as immunity's pregnant pause. Rejection of the semiallogeneic trophoblast cells must be selectively inhibited and pathways presumably include Th2 cytokines unopposed by Th1 cytokines. Steroid hormones, including progesterone, have similar effects. Low levels of progesterone and Th2 cytokines and high levels of Th1 cytokines are attributable for increased abortions in mammalians, which may be triggered by psychoemotional stress. Thus, the aim of the present study was to provide experimental evidence for the mechanism involved in the mediation of immune responses by endocrine signals during pregnancy and stress-triggered pregnancy failure. DBA/2J-mated CBA/J female mice were randomized in three groups: 1) control females, 2) mice exposed to stress on gestation day 5.5, and 3) mice exposed to stress and substituted with dydrogesterone, a progestogen with a binding profile highly selective for the progesterone receptor on gestation day 5.5. On gestation days 7.5, 9.5, and 10.5, mice of each group were sacrificed, and the frequency of CD8(+) cells and cytokine expression (IL-4, IL-12, TNF-alpha, IFN-gamma) in blood and uterus cells was evaluated by flow cytometry. Additionally, some mice were depleted of CD8 cells by injection of mAb. We observed that progesterone substitution abrogated the abortogenic effects of stress exposure by decreasing the frequency of abortogenic cytokines. This pathway was exceedingly CD8-dependent, because depletion of CD8 led to a termination of the pregnancy protective effect of progesterone substitution.     

CD4+ subset regulation in viral infection. Preferential activation of Th2 cells during progression of retrovirus-induced immunodeficiency in mice.

Progressive lymphoproliferation and increasingly severe immunodeficiency are prominent features of a syndrome, designated mouse AIDS, which develops in susceptible strains of mice infected with the mixture of murine leukemia viruses, termed LP-BM5. Development of splenomegaly and lymphadenopathy, caused primarily by increases in B cell immunoblasts, requires the presence of CD4+ T cells and is assumed to be mediated by lymphokines produced by these cells inasmuch as progression of disease is markedly inhibited by treatment of infected mice with cyclosporin A. Studies of spleen cells from infected mice revealed spontaneous production of cytokines (IFN-gamma, IL-2, IL-4, IL-5, and IL-10) characteristic of Th0 (or a mixture of Th1 and Th2) T helper cells at 1 wk after infection. At later times, IFN-gamma and IL-2, characteristic products of Th1 helper clones, were expressed poorly, either spontaneously or after stimulation of cells with Con A. In contrast, IL-4, IL-5, IL-6, and IL-10, cytokines typically synthesized by Th2 cells, were produced in response to Con A or spontaneously through 18 wk post-infection. Increased serum IgE levels and enhanced IL-10 mRNA expression were consistent with expression of Th2 cytokines at biologically significant levels in vivo. Selective depletion of T cell subsets before stimulation with Con A showed that CD4+ T cells were the primary source of IL-2, IL-4, IL-10, and, to a lesser extent, IFN-gamma in spleens and lymph nodes of normal or infected mice. These results suggest that persistent activation of CD4+ T cells with the lymphokine profile of Th2 helper clones is responsible for chronic B cell stimulation, down-regulation of Th1 cytokines, and impaired CD8+ T cell function in mouse AIDS. This provides the first demonstration that, like many parasitic infections, viruses encoding potent antigenic stimuli can markedly affect the balance of Th subset expression.     

Cytokine secretion by decidual lymphocytes in transient hypertension of pregnancy and pre-eclampsia

BACKGROUND: Transient hypertension (TH) and preeclampsia (PE) are believed to have different pathophysiology. However, 15-25% of pregnant women initially diagnosed as having TH develop PE. To clarify the immuno-pathogenetical connections between the two syndromes, we studied the pattern of T helper cell (Th)1/Th2 cytokine balance disturbances existing inside maternal decidua in normal pregnancy (NP) and pregnancies complicated with TH and PE. METHODS: Third-trimester decidual tissue was obtained by curettage of uterine cavity during elective caesarean sections in NP (n = 11), TH (n = 17) and PE (n = 21) patients. Cell suspensions were prepared by an electromechanical dispersal method and centrifugated using a standard gradient sedimentation technique. Isolated lymphocytes were placed in medium (RPMI 1640, 10% fetal calf serum, L-glutamine, penicillin, streptomycin) and cultured for 72 h with or without mitogen phytohaemaglutinine (PHA). The enzyme-linked immunosorbent assay method was used for estimation of interleukin (IL)-2, IL-4, IL-6, IL-10, IL-12 and interferon-gamma (IFN-gamma) in culture supernatant. STATISTICAL ANALYSIS: The Kruskal-Wallis and the Mann-Whitney U tests were used (p < 0.05). RESULTS: Both spontaneous and PHA-stimulated secretion of Th2-type cytokines IL-6 and IL-10 was decreased in PE patients compared with TH and NP patients. The concentration of Th1-type cytokine IFN-gamma was increased in patients suffering both from TH and PE. CONCLUSION: On the base of decidual cytokine secretion, both PE and TH are syndromes of local Th1/Th2 cytokine balance disturbances as compared with NP, and TH seems to be an intermediate step to PE.     

Role of T-cells in diabetic pregnancy and macrosomia

A number of studies have recently addressed the correlationship between diabetic pregnancy/macrosomia and differentiation of T-cells into Th1 and Th2 subsets. Diabetic pregnancy has been found to be associated with a decreased Th1 phenotype and IL-4 mRNA expression. In macrosomic offspring, high expression of IL-2 and IFN-gamma mRNA, but not of Th2 cytokines is observed, indicating that the Th1 phenotype is upregulated during macrosomia. T-cells of gestational diabetic rats and their macrosomic offspring seem to present a defect in signal transduction. Indeed, the recruitment of free intracellular calcium concentrations from intracellular pool in T-cells of these animals is altered. The phenotype of regulatory T-cells (T-Reg) is upregulated in diabetic pregnancy and their infants. T-cells in diabetic pregnancy and macrosomic obese offspring are in vivo activated. Adipokines and peroxisome proliferator-activated receptor-alpha (PPARalpha) also seem to modulate the pro-inflammatory cytokines in these pathologies. Hence, activation of the immune system might be considered as one of the regulatory pathways including metabolic abnormalities in these two pathologies.