Reduced severity of liver ischemia/reperfusion injury following hepatic resection in humans is associated with enhanced intrahepatic expression of Th2 cytokines.

BACKGROUND: Based on previous studies in experimental models, pro-inflammatory Th1 cytokines (i.e. TNF-alpha and IFN-gamma) are thought to play a pathogenic role in hepatic ischemia/reperfusion injury, while anti-inflammatory Th2 cytokines (i.e. IL-4 and IL-10) have been associated with reduced liver disease severity. To test the relevance of these concepts in humans, cytokine expression profiles were characterized in liver biopsies from patients undergoing hepatic resection following intermittent portal clamping. METHODS: Twelve patients were analyzed for the intrahepatic expression of TNF-alpha, IFN-gamma, IL-4 and IL-10 before and about 90min after the last reperfusion. In addition, parameters of liver damage including sALT and serum levels of TNF-alpha were analyzed at 2, 24 and 48h after surgery. RESULTS: When compared with pre-reperfusion liver specimens, all post-reperfusion biopsies showed significantly increased levels of TNF-alpha and IFN-gamma mRNAs. Conversely IL-4 and IL-10 mRNA levels were significantly increased in only seven patients. A negative correlation was observed between Th2 cytokines (IL-4, IL-10) and ALT and serum levels of TNF-alpha. Furthermore, the presence of hepatic steatosis was significantly associated with lower intrahepatic contents of IL-4 and IL-10. CONCLUSIONS: The results suggest that the local early expression of Th2 cytokines may contribute to attenuate liver injury following ischemia reperfusion in humans. The early imbalance between pro- and anti-inflammatory cytokines seen in steatotic liver subjected to I/R could explain, at least partially, the decreased tolerance of steatotic livers to I/R injury.     

Short communication: decreasing soluble CD30 and increasing IFN-gamma plasma levels are indicators of effective highly active antiretroviral therapy

It was previously reported that without highly active antiretroviral therapy (HAART), secretion of Th1 cytokines and antiviral IFN-gamma in HIV-infected patients is decreased, whereas the production of Th2 cytokines, proinflammatory cytokines, and TNF-alpha is increased. We studied the effect of HAART on Th1-, Th2-, and monocyte-derived cytokines, and on the Th2-type immune response marker soluble (s)CD30 in HIV-1-infected hemophilia patients. Viral Load (VL), CD4+ lymphocyte counts, and plasma levels of sIL-1RA, IL-2, sIL-2R, IL-3, IL-4, IL-6, sIL-6R, IL-7, IL-10, TNF-alpha, TGF-beta2, IFN-gamma, and sCD30 were measured in 18 patients who received HAART. Nine patients were initially treatment-naive and were monitored after the initiation of HAART. sCD30 median levels were significantly higher in treatment-naive patients than in patients who were on HAART (77 vs. 30 U/ml, p = 0.005). A strong association was observed between sCD30 and VL (r = 0.85, p = 0.004). After the initiation of HAART, sCD30 levels decreased and remained low (at 1 year, 38; at 2 years, 41 U/ml; p = 0.012 and p = 0.021, respectively, as compared to baseline level) and this was accompanied by a decrease in VL and monocyte-derived IL-6 and an increase in CD4+ lymphocyte counts and Th1-derived IFN-gamma. One year after the initiation of HAART a strong inverse correlation was observed between IFN-gamma and VL (r = -0.83, p = 0.006). In contrast to sCD30 and IFN-gamma, CD4 counts and plasma IL-6 did not correlate with VL at any time. Our data suggest that decreasing sCD30 and increasing IFN-gamma plasma levels are indicators of effective HAART treatment and CD4 Th1 cell recovery in HIV-infected patients.     

Prokineticin1 and pregnancy

Prokineticin 1 (PROK1), also called EG-VEGF, is a peptide of 86 amino acids with multiple biological functions. PROK1 acts via two G-protein coupled receptors: PROKR1 PROKR2. PROK1 is highly expressed in the placenta. This article reports the expression and the role of PROK1 during normal and pathological pregnancies: (i) during early pregnancy, PROK1 exhibits a peak of placental expression shortly before the establishment of the feto-maternal circulation; (ii) its receptors, PROKR1 PROKR2 are highly expressed in human placenta; (iii) its expression is increased by hypoxia; (iv) PROK1 inhibits extravillous trophoblasts migration and invasion and increases their proliferation and survival; (v) PROK1 is also a pro-angiogenic placental factor that increases microvascular placental endothelial cells proliferation, migration, invasion, and permeability. Circulating PROK1 levels are five times higher in pregnant women during the first trimester compared to the second and third trimesters. Also, its serum levels are higher in patients with preeclampsia (PE) and in patients with isolated intra-uterine growth restriction (IUGR). In mice, maintaining high level of PROK1 beyond its normal period of production (> 10.5 dpc) reproduces symptoms of PE. To date, our results demonstrated that PROK1 is a central factor of human placentation with direct roles both in the control of trophoblast invasion and villous growth. Thus, a failure in the expression of PROK1 and/or its receptor during pregnancy may contribute to the development of PE and/or IUGR. Besides theses original findings, we also report a direct role of this factor in parturition.     

Dysregulation of placental endothelial lipase and lipoprotein lipase in intrauterine growth-restricted pregnancies

CONTEXT: Fetal supply of maternally derived fatty acids requires lipase-mediated hydrolysis of lipoprotein-borne triglycerides and phospholipids at the placental surface. OBJECTIVE: The objective of the study was to test the hypothesis that members of the triglyceride lipase gene (TLG) family are expressed in the human placenta at the maternoplacental (syncytiotrophoblast) and fetoplacental (endothelial cells) interface and that their expression is altered in pregnancy pathologies. DESIGN AND SETTING: Expression of TLG family members in primary placental cells (trophoblast and endothelial cells) and tissues of first-trimester and term human placenta was analyzed by microarrays, RT-PCR, Western blotting, and immunohistochemistry. Their expression was compared between normal pregnancies and those complicated with intrauterine growth restriction (IUGR). PARTICIPANTS: Participants included women with uncomplicated pregnancies and pregnancies complicated by IUGR. RESULTS: Endothelial lipase (EL) and lipoprotein lipase (LPL) were the only lipases among the TLG family expressed in key cells of the human placenta. In first trimester, EL and LPL were expressed in trophoblasts. At term, EL was detected in trophoblasts and endothelial cells, whereas LPL was absent in these cells. Both lipases were found at placental blood vessels, EL in vascular endothelial cells and LPL in the surrounding smooth muscle cells. In total placental tissue EL expression prevails in first trimester and at term. Compared with normal placentas, EL mRNA was decreased (30%; P < 0.02), whereas LPL mRNA expression was increased (2.4-fold; P < 0.015) in IUGR. CONCLUSION: EL is the predominant TLG family member in the human placenta present at both interfaces. EL and LPL are dysregulated in IUGR.     

Placental iodothyronine deiodinase expression in normal and growth-restricted human pregnancies

We have described the expression of specific iodothyronine deiodinase mRNAs (using quantitative RT-PCR) and activities in normal human placentas throughout gestation and compared our findings to those in placentas from pregnancies affected by intrauterine growth restriction (IUGR). The predominant deiodinase expressed in placenta was type III (D3); type II (D2) was also present. In general terms, the activities of the enzymes D2 and D3 (and mRNAs encoding these enzymes) were higher earlier in gestation (<28 wk) than at term and displayed an inverse relationship with the duration of gestation (P < 0.05). Comparison of the relative expressions of mRNAs encoding D2 and D3 as well as their activities in placentas associated with IUGR (early and late gestational groups) with findings from normal placentas of similar gestational ages revealed no significant differences. Immunolocalization of D2 and D3 in syncytiotrophoblast (including syncytial sprouts) and cytotrophoblast of human placentas was demonstrated at both early and late gestation. Treatment of primary cultures of term cytotrophoblast cells in vitro with increasing doses of T(3) (1, 10, and 100 nM) resulted in increased expression of mRNAs encoding both D2 and D3 at 100-nM concentrations (P < 0.01) compared with control. Experiments with JEG-3 choriocarcinoma cells demonstrated a similar effect on D3 mRNA at 10 and 100 nM T(3) (P < 0.01). The demonstrated changes in iodothyronine deiodinase expression in the placenta across pregnancy are likely to contribute to regulation of the thyroid hormone supply to the developing fetus. The lack of difference in deiodinase expression in normal placentas and those found in IUGR argues against placental deiodinases being responsible for the hypothyroxemia in circulating fetal thyroid hormones observed in this condition.     

Oxygen regulation of placental 11 beta-hydroxysteroid dehydrogenase 2: physiological and pathological implications

Preeclampsia (PE) is a major cause of maternal and perinatal morbidity and mortality. The genesis of PE is related to deficient trophoblast invasion of maternal spiral arteries, which might result in a reduction of placental (PL) oxygen (O(2)). An absence of increased O(2) that normally occurs around the 10-12th wk of gestation results in aberrant expression of genes that might contribute to the pathophysiology of PE. We examined the expression and regulation of PL 11 beta-hydroxysteroid dehydrogenase 2 (11 beta-HSD) in normal pregnancies and in PE. Two types of 11 beta-HSD exist in the placenta, 11 beta-HSD1 and 11 beta-HSD2. 11 beta-HSD2 is thought to protect the fetus from cortisol excess. In PE, both the expression and activity of PL 11 beta-HSD2 were reduced significantly compared with those in age-matched controls. As PE is associated with a reduction of PL O(2), we next investigated whether in normal pregnancy 11 beta-HSD2 expression changes at the time of the increase in O(2). 11 beta-HSD2 was detected as early as 5 wk, with expression limited to the syncytiotrophoblast (ST). At 10-12 wk, this expression increased and was also found in the cytotrophoblast and extravillous trophoblast. These results were substantiated by Western blot. The ability of O(2) to regulate 11 beta-HSD2 was determined both in cultures of villous explant from early gestation and in term trophoblast cells after incubation under 3% or 20% O(2). Villous explants cultured under 20% O(2) showed higher enzyme activity and expression compared with 3% O(2). Term trophoblast cells also exhibited higher enzyme activity at 20% vs. 3% O(2). No change in 11 beta-HSD1 expression was observed in early pregnancy or in PE. This is the first report to suggest that 11 beta-HSD2 is O(2) dependent in first and third trimester placenta during human gestation.     

Cytokine gene expression in autoimmune thyroiditis in BioBreeding/Worcester rats.

The intrathyroidal cytokine gene expression in human autoimmune thyroid disease is difficult to interpret because surgical specimens mostly reflect the autoimmune disease at a late stage. Because it is not possible to investigate early stages of thyroiditis in humans, the Bio Breeding/Worcester (BB/W) rat was used as a model. To characterize the lymphocytic thyroiditis (LT) of BB/W rats further and to evaluate early increases of cytokine gene expression in LT, we investigated the interleukin (IL)-2, -4, -6, -10, -12p40, interferon-gamma (IFN-gamma) and tumor necrosis factor-alpha (TNF-alpha) gene expression in the thyroids, spleens, and livers of BB/W rats with and without histological evidence for thyroiditis. The gene expression of these cytokines was determined by Genescan (PE Applied Biosystems, Foster City, CA) fragment analysis using reverse polymerase chain reaction (RT-PCR). Serum thyroglobulin (Tg) antibody concentrations were measured and the extent of lymphocytic infiltration of one thyroid lobe was histologically graded. Cytokine gene expression in rats with and without LT was compared in three groups of rats: 55-day-old rats after 24 days of iodine administration, 75-day-old rats after 45 days of iodine administration, and 101-day-old rats. In the thyroids of the BB/W rats no expression of IL-4 or IL-10 was detectable. The number of rats with detectable TNF-alpha, IFN-gamma, IL-2, IL-12p40 gene expression was significantly higher in rats with LT. Rats with LT had significantly higher IL-12p40 mRNA levels. There were no significant differences in the IL-6 gene expression between rats with and without LT. A correlation between the level of lymphocytic infiltration and the TNF-alpha (r = 0.56, p < 0.0065) and TG antibody concentration (r = 0.62, p < 0.0065) was found. Therefore, the early cytokine gene expression in the BB/W rat is characterized by Th1-related cytokines like IL-2 and IFN-gamma. Whether the detected IL-12p40 (10 rats) and IFN-gamma (5 rats) gene expression in animals without LT is an early indicator for the development of LT remains to be determined.     

Probiotic Leuconostoc mesenteroides ssp. cremoris and Streptococcus thermophilus induce IL-12 and IFN-γ production

AIM： To investigate the capacity of potentially probiotic strains from six bacterial genera to induce cytokine production alone or in combinations in order to identify potential enhancing or synergistic effects in order to select probiotic bacteria for in vivo purposes.
METHODS： Cytokine production in human peripheral blood mononuclear cells （PBMC） in response to stimulation with eleven different potentially probiotic bacterial strains from Streptococcus, Lactobacillus, Bifidobacterium, Lactococcus, L euconostoc a n d Propionibacterium genera was analysed. Production and mRNA expression of TNF-α, IL-12, IFN-y and IL-10 were determined by ELISA and Northern blotting, respectively.
RESULTS： All tested bacteria induced TNF-α production. The best inducers of Thl type cytokines IL-12 and IFN-y were Streptococcus and Leuconostoc strains. All BiHdobacterium and Propionibacterium strains induced higher IL-IO production than other studied bacteria. Stimulation of PBMC with any bacterial combinations did not result in enhanced cytokine production suggesting that different bacteria whether gram-positive or gram- negative compete with each other during host cell interactions.
CONCLUSION： The probiotic S. thermophilus and Leuconostoc strains are more potent inducers of Thl type cytokines IL-12 and IFN-γ than the probiotic Lactobacillus strains. Bacterial combinations did not result in enhanced cytokine production.     

Adrenomedullin is decreased in preeclampsia because of failed response to epidermal growth factor and impaired syncytialization

To explore the mechanisms of adrenomedullin (ADM) regulation in normal and preeclamptic (PE) states, we determined placental production of ADM and ADM regulation by cytokines. Isolated, purified cytotrophoblast cultures from normal (n=8) and PE (n=10) placentas were cultured for 3 days in the absence or presence of 10 ng/mL epidermal growth factor (EGF), 1 ng/mL transforming growth factor (TGF)-beta1, 10 ng/mL tumor necrosis factor (TNF)-alpha, or 100 U/mL interferon (IFN)-gamma. Cells were also cultured for 3 days in 10% fetal bovine serum for determination of syncytial formation by desmoplakin staining. Pieces of normal and PE placentas were snap-frozen for ADM mRNA measurement. Results showed that basal ADM production into culture medium by radioimmunoassay was significantly lower in PE placental cells. EGF significantly stimulated ADM production in normal trophoblasts but did not in PE placentas. None of the factors TNF-alpha, TGF-beta1, or IFN-gamma altered ADM secretion in either normal or PE placentas. ADM expression by Northern blot analysis demonstrated a 34.3+/-8.3% reduction in mRNA expression in PE placentas. Syncytialization, as assessed by desmoplakin-outlined syncytial units, was decreased in PE placentas (day 3: normal, 16.7+/-1.3%; PE, 5.5+/-2.0%; P<0.01, ANOVA). However, there was a normal increment in syncytialization in response to EGF in normal and PE trophoblast preparations (EGF day 3: normal, 43.8+/-5.6%; PE, 46.1+/-12.3%). We conclude that spontaneous placental syncytialization is impaired in PE and that ADM production is markedly reduced in PE, possibly owing to an impaired EGF response. These abnormalities indicate poor placental production of ADM as the likely cause of a failed compensatory increase in maternal serum ADM levels in PE.     

Longitudinal study of serum placental GH in 455 normal pregnancies: correlation to gestational age,fetal gender,and weight

Placental GH is thought to be responsible for the rise in maternal IGF-I during pregnancy and is considered to be important for fetal growth. In this prospective longitudinal study of healthy pregnant women, we investigated determinants of placental GH in maternal serum. Serum was obtained from 455 women with normal singleton pregnancies at approximately 19 and 28 wk gestation. Serum placental GH concentrations were measured by a highly specific immunoradiometric assay, and fetal size was measured by ultrasound. Data on birth weight, gender, prepregnancy body mass index (BMI), parity, and smoking habits were obtained from medical records. Serum placental GH concentrations were detectable in serum from all women as early as 14 wk gestation and increased during pregnancy in all individuals (P < 0.001). Placental GH levels at second examination were found to be higher in women carrying female fetuses [median, 9.0 ng/ml; 95% confidence interval (CI), 4.7-23.0] compared with women carrying male fetuses (median, 8.2 ng/ml; 95% CI, 3.96-19.4; P = 0.004). Similarly, the increase in placental GH between 19 and 28 wk gestation was significantly larger in female fetus bearers than in male fetus bearers (P = 0.002). Placental GH at second examination was positively correlated with gestational age (P = 0.002) and negatively correlated with prepregnancy BMI (P = 0.039). Placental GH correlated with fetal weight at approximately 28 wk gestation (P = 0.002) but did not predict birth weight at term. Our study supports the role of maternal placental GH in the regulation of fetal growth. In conclusion, we found that 1) placental GH levels correlated significantly with fetal size at 28 wk gestation; 2) GH levels were measurable in serum from all women as early as 14 wk gestation; 3) maternal prepregnancy BMI and smoking were determinants of placental GH levels, although their specific effects on the serum maternal levels of placental GH remain to be seen; and 4) women carrying female fetuses have significantly higher placental GH levels compared with women carrying male fetuses at 28 wk gestation.     

Plasmodium falciparum induces a Th1/Th2 disequilibrium, favoring the Th1-type pathway, in the human placenta

During pregnancy, a local and systemic Th2 bias of maternal immunity favors Th1-dependent infections such as malaria. This study measured cytokines secreted in cultures of chorionic villi, placental blood cells (PBC), and serum in term placentas from 88 malaria-infected and -noninfected Cameroon women. Interleukin (IL)--2 and --4 were consistently low; IL-1 beta, IL-6, granulocyte-macrophage colony-stimulating factor, and transforming growth factor (TGF)--beta 2 were highest in villi cultures. Tumor necrosis factor (TNF)--alpha, interferon (IFN)--gamma, and IL-10 were highest in PBC cultures. Malaria placental infection increased Th1-type cytokines, whereas Th2-type cytokines and TGF-beta 2 were unchanged. Addition of lipopolysaccharide or infected erythrocytes to cultures increased TNF-alpha, IL-1 beta, IL-6, and IL-10 secretions but not those of IFN-gamma and IL-4. Overall, Plasmodium falciparum induced a placental immune response involving both Th1- and Th2-type cell activation. Although the Th1 pathway was favored, IL-10 secretion was also increased, and this increase should be effective in protecting the placenta by controlling the negative effects of Th1 cytokines on pregnancy.     

A longitudinal study of intrauterine growth and the placental growth hormone (GH)-insulin-like growth factor I axis in maternal circulation: association between placental GH and fetal growth

The aim of the study was 1) to evaluate the association of maternal serum levels of placental GH and IGF-I with fetal growth, and 2) to establish reference data for placental GH, IGF-I, and IGF-binding protein-3 (IGFBP-3) in normal pregnancies based on longitudinal measurements. A prospective longitudinal study of 89 normal pregnant women was conducted. The women had, on the average, seven blood samples taken and three ultrasound examinations performed. All had normal umbilical artery pulsatility indexes during pregnancy and gave birth to singletons between 37 and 42 wk gestation with birth weights above -2 SD. Placental GH levels were detectable in all samples from as early as 5 wk gestation and increased significantly throughout pregnancy to approximately 37 wk when peak levels of 22 ng/ml (range, 4.64-69.22 ng/ml) were reached. Subsequently, placental GH levels decreased until birth. The change in placental GH during 24.5-37.5 wk gestation was positively associated with fetal growth rate (P = 0.027) and birth weight (P = 0.027). Gestational age at peak placental GH values (P = 0.007) was associated with pregnancy length. A positive association between the change in placental GH and the change in IGF-I levels throughout gestation was found in a multivariate analysis (r(2) = 0.42; P < 0.001). There was no association between placental GH and IGFBP-3 levels. The change in IGF-I throughout gestation (P = 0.039), but not placental GH, was significantly positively associated with placental weight at birth. We found a significant association between placental GH and fetal growth. In addition, we found a highly significant association between the increase in placental GH and the increase in IGF-I. The gestational age at peak placental GH levels was associated with pregnancy length.     

T cell cytokine imbalance towards production of IFN-gamma and IL-10 in NZB/W F1 lupus-prone mice is associated with autoantibody levels and nephritis

OBJECTIVE: The role of T cell-derived cytokine production in lupus is poorly understood. We analysed the cytokine production of CD4(+) T cells in the NZB/W F1 mouse strain, the mouse model probably most closely resembling human systemic lupus erythematosus (SLE), and assessed whether a possible shift in the cytokines expressed is associated with age or disease activity. METHODS: We used intracellular cytokine staining and flow cytometry to determine the cytokine expression of splenic CD4(+) T cells for interferon-gamma (IFN-gamma), tumour necrosis factor-alpha (TNF-alpha), interleukin-4 (IL-4) and IL-10. NZB/W F1 mice at different ages spanning 5 to 36 weeks were analysed, healthy Balb/cxNZW F1 (CWF1) mice were used as controls. Serum anti-double-stranded DNA (anti-dsDNA) antibody levels were determined by enzyme-linked immunosorbent assay (ELISA), and proteinuria and plasma creatinine were estimated using commercial test kits. RESULTS: The cytokine profile of CD4(+) T cells was shifted towards T-helper 1 (Th1) cells and the frequencies of Th cells expressing IFN-gamma(+) correlated with age, anti-dsDNA-immunoglobulin G (IgG) titre and proteinuria. An increased percentage of IL-10 producers correlated positively with anti-dsDNA-IgG and proteinuria, and a small gain in IL-4 producers correlated with plasma creatinine. Neither the percentage of IL-10 producers nor IL-4 producers showed a significant correlation with age. There was no significant change observed in the frequency of TNF-alpha T cells. The IFN-gamma/IL-4 ratio demonstrated an increasing shift towards a Th1-type response during disease development that was not present in healthy mouse strains. CONCLUSION: The association between the frequencies of T cells expressing IFN-gamma and IL-10 and clinical findings suggests a key role for these cells in the pathogenesis of lupus.     

Maternal serum-soluble vascular endothelial growth factor receptor-1 in early pregnancy ending in preeclampsia or intrauterine growth retardation

CONTEXT: Vascular endothelial growth factor (VEGF) promotes placental vascularization, which is inadequate in preeclampsia and intrauterine growth retardation (IUGR). The soluble receptor of VEGF (sVEGFR-1), also known as soluble fms-like tyrosine kinase-1, is produced in the placenta and reduces VEGF activity. Therefore, elevated sVEGFR-1 could contribute to the development of preeclampsia and IUGR. OBJECTIVE: The objective of this study was to study maternal serum sVEGFR-1 concentration in early pregnancy ending in preeclampsia and IUGR. DESIGN: This was a case-control study. SETTING: This study was conducted at Helsinki University Central Hospital (Helsinki, Finland), a tertiary referral center. PATIENTS: Patients included 124 pregnant women, of whom 49 developed preeclampsia, 16 gave birth to IUGR infants without preeclampsia, and 59 remained normotensive and gave birth to normal-sized infants. Serum samples were collected at 12-15 and 16-20 gestational weeks. MAIN OUTCOME MEASURES: Serum sVEGFR-1 concentrations were determined by ELISA. RESULTS: Women with subsequent preeclampsia had higher [median; interquartile range (IQR)] concentrations of sVEGFR-1 at 16-20 wk gestation (436 and 282-699 ng/liter; P = 0.005) than the controls (296 and 184-508 ng/liter). The conclusion was the same if women with mild (340 and 285-750 ng/liter; P = 0.043) or severe (497 and 235-699 ng/liter; P = 0.022) preeclampsia were analyzed separately. An elevated sVEGFR-1 concentration at 16-20 wk gestation is associated with an increased risk of preeclampsia but not of isolated IUGR. Soluble VEGFR-1 concentration decreased by 15% from the first to the second sampling in the controls but not in women with preeclampsia or IUGR. CONCLUSION: Elevated sVEGFR-1 concentrations at 16-20 wk gestation precede the clinical manifestations of preeclampsia. By neutralizing VEGF, sVEGFR-1 may contribute to inadequate placental vascularization.     

Changes in proliferative potential, apoptosis and Bcl-2 protein expression in cytotrophoblasts and syncytiotrophoblast in human placenta over the course of pregnancy

In order to evaluate placental trophoblast proliferation and apoptosis during pregnancy, we investigated proliferating cell nuclear antigen (PCNA) expression, apoptosis and Bcl-2 protein expression in the human placenta using avidin/biotin immunoperoxidase method to examine PCNA and Bcl-2 protein expression, and TUNEL method to assess apoptosis. The appearance of apoptotic cells in very early term placental trophoblasts was also examined by transmission electron microscopy. PCNA was immunolocalized in the nuclei of cytotrophoblasts (C-cells). Determination of the mean percentage of PCNA-positive nuclei of C-cells revealed that PCNA expression in C-cells was highest in very early term (4th to 5th wk) placentas and significantly decreased with the advance of pregnancy. Bcl-2 protein was immunolocalized in the cytoplasm of syncytiotrophoblast (S-cell), being least abundant in very early term placentas, less abundant in early term and midterm placentas, and most abundant in term placentas. On the basis of TUNEL method, apoptosis was apparent in the nuclei of both C-cells and S-cell. The apoptosis positive rate of C-cell nuclei was highest in very early term 4th to 5th wk placentas, and significantly decreased in early term 7th to 9th wk and midterm placentas, but somewhat increased in term placentas compared to that in midterm placentas. On the other hand, apoptosis positive rate of S-cell nuclei was remarkably higher only in very early term 4th to 5th wk placentas compared to that in early term, midterm and term placentas. Transmission electron microscopy revealed the appearance of apoptotic nucleus in very early term placental trophoblasts. These results demonstrate for the first time that apoptosis in the human normal placenta predominates in both C-cells and S-cell in very early term 4th to 5th wk pregnancy and drastically diminished after 7th wk of pregnancy. An apparent increase in apoptosis in C-cells in term placentas compared to that in midterm placentas may reflect aging of the placenta or parturition-associated biological change. The abundant expression of Bcl-2 protein in S-cell in term placentas may be responsible for the diminished occurrence of apoptosis in S-cell in term placentas.     

CD1d and invariant NKT cells at the human maternal-fetal interface

Invariant CD1d-restricted natural killer T (iNKT) cells comprise a small, but significant, immunoregulatory T cell subset. Here, the presence of these cells and their CD1d ligand at the human maternal-fetal interface was investigated. Immunohistochemical staining of human decidua revealed the expression of CD1d on both villous and extravillous trophoblasts, the fetal cells that invade the maternal decidua. Decidual iNKT cells comprised 0.48% of the decidual CD3+ T cell population, a frequency 10 times greater than that seen in peripheral blood. Interestingly, decidual CD4+ iNKT cells exhibited a striking Th1-like bias (IFN-gamma production), whereas peripheral blood CD4+ iNKT clones exhibited a Th2-like bias (IL-4 production). Moreover, compared to their peripheral blood counterparts, decidual iNKT clones were strongly polarized toward granulocyte/macrophage colony-stimulating factor production. The demonstration of CD1d expression on fetal trophoblasts together with the differential pattern of cytokine expression by decidual iNKT cells suggests that maternal iNKT cell interactions with CD1d expressed on invading fetal cells may play an immunoregulatory role at the maternal-fetal interface.