X-linked inhibitor of apoptosis (XIAP) confers human trophoblast cell resistance to Fas-mediated apoptosis

Apoptosis occurs in the placenta throughout gestation, with a greater frequency near term in comparison to the first trimester. The Fas/FasL system represents one of the main apoptotic pathways controlling placental apoptosis. Although first trimester trophoblast cells express both Fas and FasL, they are resistant to Fas-induced apoptosis. Therefore, trophoblast resistance to Fas-mediated apoptosis may be due to the inhibition of the pathway downstream of Fas stimulation. Expression levels of X-linked inhibitor of apoptosis (XIAP) were recently shown to decrease in third trimester placentas, correlating with an increase in placental apoptosis. As a potent caspase inhibitor, XIAP prevents the activation of caspase-9 through its BIR3 domain and caspase-3 activation via the linker-BIR2 domain. In the present study, high levels of the active form of XIAP were detected in first trimester trophoblast cells, whereas term placental tissue samples predominantly expressed the inactive form of XIAP. Using a XIAP inhibitor, phenoxodiol, we demonstrate that XIAP inactivation sensitizes trophoblast cells to Fas stimulation, as evidenced by the anti-Fas mAb-induced decrease in trophoblast cell viability and increase in caspase-8, caspase-9 and caspase-3 activation. This suggests a functional role for XIAP in the regulation of the Fas apoptotic cascade in trophoblast cells during pregnancy.     

Expression of Thrombospondin-1 Gene mRNA and Protein in the Placenta in Gestosis

The expression of TSP-1 gene mRNA and TSP-1 protein in the placental tissue was studied during normal pregnancy and in gestosis. The formation of placental tissue in normal gestation was associated with expression of TSP-1 gene mRNA and of TSP-1 protein. Gestosis was associated with infl ammatory reaction in the placenta characterized by increased counts of lymphocytes and macrophages in the villous stroma and involution degenerative changes in tissue. Disorders in placental villi maturation and branching in gestosis were paralleled by hyperexpression of TSP-1 gene mRNA by placental cells and hyperexpression of TSP-1 protein predominating in the stromal elements of terminal villi and near villous vessels.     

宫内暴露尼古丁对生后小鼠大脑皮层神经细胞凋亡的影响

目的研究宫内暴露尼古丁对生后小鼠大脑皮层神经细胞凋亡的影响。方法建立妊娠期宫内暴露尼古丁小鼠动物模型,观察生后21天小鼠大脑皮层组织结构变化,免疫组织化学方法和W estern b lot方法检测宫内暴露尼古丁模型大脑皮层caspase-3的表达。结果尼古丁组小鼠大脑皮层脑回厚度较对照组变薄(P<0.05),免疫组织化学法检测到大脑皮层caspase-3阳性反应物的平均光密度值在尼古丁组高于对照组(P<0.05),W estern b lot方法检测到大脑皮层caspase-3酶原(32KD)形式及活性片段形式(17KD、20KD)的相对表达量高于对照组(P<0.01)。结论孕期宫内暴露尼古丁激活生后小鼠大脑皮层神经细胞caspase-3的过表达,参与大脑皮层神经细胞凋亡。     

Expression of phosphorylated caspase-9 in gastric carcinomas

Alterations of caspases, the main executioners of apoptosis, have been described in human cancers. Caspase-9 plays a crucial role in the initiation phase of the intrinsic apoptosis pathway. Caspase-9 is phosphorylated at Thr125 through the mitogen-activated protein kinase (MAPK) pathway, and this phosphorylation is associated with inhibition of caspase-9 activation. The aim of this study was to explore whether phosphorylated caspase-9 (p-caspase-9) expression could be a characteristic of gastric carcinomas. We analyzed expression of p-caspase-9 protein in 60 gastric adenocarcinomas by immunohistochemistry using a tissue microarray approach. p-caspase-9 was detected in 33 of the 60 carcinomas (55%). Both early and advanced gastric carcinomas expressed p-caspase-9. There was no significant association of p-caspase-9 expression with clinocopathological characteristics, including invasion, metastasis and stage. In contrast to gastric cancer cells, epithelial cells in normal gastric mucosa showed no or only weak expression of p-caspase-9. Taken together, these results indicate that caspase-9 is frequently phosphorylated in gastric carcinomas, and that the phosphorylation of caspase-9 might be an inhibitory mechanism of caspase-9-mediated apoptosis in gastric carcinomas. Increased expression of p-caspase-9 in malignant gastric epithelial cells compared to normal mucosal epithelial cells suggests that p-caspase-9 expression might play a role in gastric carcinoma development.     

1139939111TLR6 protects first trimester trophoblast cells from TLR2/TLR1 mediated apoptosis

Introduction:  Increased trophoblast apoptosis has been observed in pregnancy complications such as preeclampsia. The factors promoting this cell death are unknown. Trophoblasts express Toll-like receptors (TLR), enabling them to recognize microorganisms. In response to the TLR2 ligand peptidoglycan (PDG), trophoblasts undergo apoptosis suggesting that gram-positive bacteria may promote trophoblast apoptosis. The objective of this study was to characterize the cellular mechanism by which TLR2 induces apoptosis. We report the role of TLR6 in the regulation of TLR2 mediated apoptosis following ligation by PDG.
Methods:  First trimester trophoblast cell lines express TLR1 and TLR2 but lack TLR6 and are sensitive to PDG-mediated apoptosis. Three stable transfectants were made to express either a TLR1 dominant negative (TLR1-DN), a TLR2 dominant negative (TLR2-DN) or full length TLR6. Cells were treated with PDG (40 μg/mL) after which cell viability, caspase-3 activity and cytokine production were evaluated.
Results:  Trophoblasts expressing the TLR2-DN showed a 57.4 ± 1.2% inhibition in PDG-induced caspase-3 activity compared with wildtype cells, while the TLR1-DN inhibited PDG-induced caspase-3 activity by 61.6 ± 1.1%. Expression of TLR6 by trophoblasts, reversed PDG-mediated apoptosis as shown by reduced caspase-3 activity (77.6 ± 1.2%) and increased cytokine production.
Conclusion:  These results suggest that a gram-positive bacterial infection during pregnancy may promote trophoblast apoptosis via TLR2/TLR1 heterodimers. Expression of TLR6, however, may protect the trophoblast from PDG-induced apoptosis and instead promote an inflammatory response. These findings shed new light on the mechanisms by which infection may affect placental function and pregnancy outcome.     

Caspase-3、survivin与胚胎停育的关系研究

目的 观察胚胎停育妇女绒毛织组中caspase-3和survivin的表达,探讨过度凋亡与胚胎停育的关系。方法 选取2018年5月1日~12月31日在天津市第一中心医院妇科计划生育门诊确诊胚胎停育患者30例作为观察组,另选取同期在我院计划生育门诊正常妊娠要求人工流产的患者30例作为对照组,采用SP法检测两组患者绒毛组织中caspase-3和survivin的表达。结果 对照组光镜下见绒毛组织大小一致,绒毛间可见正常结构的间充质细胞。观察组光镜下见绒毛组织发生不同程度的退行性改变,间充质变性,结构模糊,同时伴炎性反应;观察组绒毛组织细胞及对照组绒毛组织细胞皆有caspase-3蛋白的表达,观察组绒毛组织caspase-3表达量高于对照组,观察组阳性率为96.66%,高于对照组的86.66%,差异有统计学意义（P＜0.05）;观察组绒毛组织细胞及对照组绒毛组织细胞皆有survivin蛋白的表达,观察组绒毛组织survivin表达量低于对照组,观察组阳性率为73.33%,低于对照组的96.66%,差异有统计学意义（P＜0.05）。结论 胚胎停育可能与绒毛组织中caspase-3高表达、survivin低表达导致的细胞凋亡过度有关。     

IFN-gamma promotes apoptosis of the uterus and placenta in pregnant rat and human cytotrophoblast cells.

Growth and development of placentas in all pregnancy periods and that of fetuses in late pregnancy were inhibited after administration of interferon-gamma (IFN-gamma). Apoptosis can be detected by TUNEL at the maternal-fetal interface during normal rat pregnancy. Apoptosis locations at the maternal-fetal interface changed according to the period of pregnancy. The results of immunohistochemistry and the DNA ladder assay showed that IFN-gamma could promote the apoptosis levels during the entire pregnancy, but it did not change the apoptosis locations. IFN regulatory factor-1 (IRF-1), FasL, and p53 expressions were modulated by IFN-gamma during the entire pregnancy. In vitro cell proliferation assay indicated that IFN-gamma could inhibit proliferation of human cytotrophoblast cells, and flow assay showed that this effect was mainly due to apoptosis induction. TUNEL and Hoechst staining also showed that IFN-gamma could induce apoptosis of human cytotrophoblast cells. Expression of IRF-1 was induced and expression of active caspase-3 was promoted by IFN-gamma treatment, but IFN-gamma did not affect the expression of IFNGR and p53.     

Hypoxic switch in mitochondrial myeloid cell leukemia factor-1/Mtd apoptotic rheostat contributes to human trophoblast cell death in preeclampsia

Preeclampsia, a disorder of pregnancy, is characterized by increased trophoblast cell death and altered trophoblast-mediated remodeling of myometrial spiral arteries resulting in reduced uteroplacental perfusion. Mitochondria-associated Bcl-2 family members are important regulators of programed cell death. The mechanism whereby hypoxia alters the mitochondrial apoptotic rheostat is essential to our understanding of placental disease. Herein, myeloid cell leukemia factor-1 (Mcl-1) isoform expression was examined in physiological/pathological models of placental hypoxia. Preeclamptic placentae were characterized by caspase-dependent cleavage of death-suppressing Mcl-1L and switch toward cell death-inducing Mcl-1S. In vitro, Mcl-1L cleavage was induced by hypoxia-reoxygenation in villous explants, whereas Mcl-1L overexpression under hypoxia-reoxygenation rescued trophoblast cells from undergoing apoptosis. Cleavage was mediated by caspase-3/-7 because pharmacological caspase inhibition prevented this process. Altitude-induced chronic hypoxia was characterized by expression of Mcl-1L; resulting in a reduction of apoptotic markers (cleaved caspase-3/-8 and p85 poly-ADP-ribose polymerase). Moreover, in both physiological (explants and high altitude) and pathological (preeclampsia) placental hypoxia, decreased trophoblast syncytin expression was observed. Hence, although both pathological and physiological placental hypoxia are associated with slowed trophoblast differentiation, trophoblast apoptosis is only up-regulated in preeclampsia, because of a hypoxia-reoxygenation-induced switch in generation of proapoptotic Mcl-1 isoforms.     

The Role of Macrophages in Utero-placental Interactions During Normal and Pathological Pregnancy

The intimate association between maternal and placental tissues elicits an interesting immunological paradox. Placental tissue contains paternal antigens, but under normal circumstances the semi-allogeneic fetus and placenta are not attacked by the maternal immune system. Interestingly, this tolerance to fetal antigens occurs in the presence of a large number of maternal leukocytes, almost all of which are members of the innate immune system. Macrophages are one of the most abundant leukocytes in the decidua and their numbers remain constant throughout gestation. They are recruited to the decidua by both stromal cells and trophoblast cells, where they adopt a specialized phenotype that may assist in various aspects of decidual homeostasis, placental development, and tolerance to the semi-allogeneic trophoblast. Aberrant behavior of these macrophages can affect trophoblast function and placental development, potentially leading to a spectrum of adverse pregnancy outcomes ranging from pre-eclampsia to fetal growth restriction or demise. This review will focus on the phenotype and putative functions of decidual macrophages in normal pregnancy, and how abnormal activation of these cells can affect various aspects of placental development.     

Caspase cascade of Fas-mediated apoptosis in human normal endometrium and endometrial carcinoma cells

Human endometrial epithelial cells undergo apoptosis immediately before the menstrual period. Apoptotic signalling was analysed using human endometrial tissue and a human endometrial carcinoma cell line (HHUA). Activity levels of caspase-3, -8, and -9 were elevated in human endometrium during the late secretory phase and in HHUA cells incubated with an anti-Fas monoclonal antibody (mAb). Fas-mediated apoptosis of HHUA cells was blocked by prior exposure to inhibitors of caspase-9, -8 and -3. In HHUA cells treated with anti-Fas mAb, a release of cytochrome c was detected in the cytosolic fraction, in addition a full-length Bid was degraded. Full-length FLIP(L) (p55) was degraded during apoptosis, and p29 (regarded as the product of p55 cleavage) appeared instead of FLIP(L). In normal human endometrial tissue, Bid degradation was also observed in a cyclic manner with a peak during the early secretory phase of the menstrual cycle. Furthermore, the release of cytochrome c was seen in the early secretory phase. However, expression of FLIP(S) was only observed during the menstrual cycle in normal endometrial tissue. We concluded that the main apoptotic signalling in both normal human endometrial tissue and HHUA cells exposed to anti-Fas mAb is the mitochondrial pathway via Bid degradation. Although the function of FLIP is still unknown on normal endometrial tissue, it may be regulated by FLIP(L) expression on HHUA cells derived from human endometrial carcinoma.     

Toll‐like Receptor‐2 and Toll‐like Receptor‐4 Expression on Maternal Neutrophils During Pregnancy

Nitsche JF, Jiang S‐W, Brost BC. Toll‐like receptor‐2 and toll‐like receptor‐4 expression on maternal neutrophils during pregnancy. Am J Reprod Immunol 2010; 64: 427–434 Problem Toll‐like receptors (TLR) are an important part of the innate immune system and are present in a variety of human tissues. Work investigating the role of the TLR in pregnancy has thus far focused on placental tissue; however, minimal data is currently available concerning TLR expression in other tissues. Unlike placental tissue, neutrophils are easily retrievable during pregnancy and thus allow assessment of TLR’s prior to delivery. Method of study Using real time quantitative PCR this study investigated whether TLR‐2 and TLR‐4 expression on maternal neutrophils is altered throughout gestation or at the time of labor. A group of 12 non‐pregnant women and two groups of ten pregnant patients were enrolled and followed longitudinally, one group throughout gestation and one group throughout the third trimester. Results Although increased in the placenta, TLR2 and TLR4 expression on maternal neutrophils changes minimally throughout gestation. Conclusion There appears to be very little regulation of TLR2 and TLR4 at the mRNA level during normal pregnancy and labor. However, now that the normal values of TLR expression on maternal neutrophils have been determined it will be possible to compare them to those from pregnancies complicated by such conditions as preeclampsia, preterm labor, or preterm premature rupture of membranes.     

细胞命运决定因子numb在先兆子痫胎盘组织中的表达及作用

目的探讨先兆子痫胎盘组织中细胞命运决定因子numbs表达情况及意义。方法获取正常妊娠胎盘组织以及先兆子痫胎盘组织,分别运用实时荧光定量PCR法、免疫印迹法、免疫组织化学法检测numbmRNA、蛋白分布及其表达水平。结果numb在以上两种胎盘组织中均有表达,且主要集中在细胞膜上表达。numb在先兆子痫组（实验组）的表达水平明显高于正常胎盘组（对照组）（P〈0．05）。结论numb参与的滋养细胞凋亡失调可能是先兆子痫的发病机制之一。     

No evidence for apoptosis of decidual leucocytes in normal and molar pregnancy: implications for immune privilege

Complete hydatidiform moles are totally paternally derived and represent complete allografts that might be expected to provoke maternal immune rejection. Our previous and other studies have shown expression of Fas by increased numbers of activated decidual CD4(+) T cells in both complete and partial molar pregnancy as well as increased FasL(+) expression by molar trophoblasts compared with trophoblasts in normal pregnancies. As the Fas/FasL system represents a major apoptotic pathway that can play a role in immune privilege, the aim of this study was to investigate whether apoptosis of decidual immune cells, particularly T cells, could be responsible for maternal immune tolerance in molar pregnancy. Using terminal deoxynucleotidyl transferase (TdT)-mediated nick end-labelling (TUNEL), a significant increase in TUNEL(+) cells was demonstrated in decidua associated with partial (P = 0.0052) and complete (P = 0.0096) hydatidiform mole compared with normal early pregnancy. Co-labelling immunoperoxidase studies showed that the TUNEL(+) cells in both normal and molar pregnancies were not activated CD45RO(+) immune cells, CD3(+) T cells, CD56(+) uterine natural killer (NK) cells or CD14(+) CD68(+) macrophages. Double immunohistochemical labelling with antiactive caspase-3 and leucocyte markers confirmed the lack of leucocyte apoptosis. Double immunostaining with anticytokeratin to detect trophoblast and M30 CytoDeath, which detects a neoepitope of cytokeratin 18 revealed after caspase-mediated cleavage, revealed apoptotic extravillous trophoblast cells within decidual tissue. We conclude that there is no evidence that apoptosis of decidual leucocytes plays a role in maintaining maternal tolerance in either normal or molar pregnancy.     

PD-1 Regulates T Cell Proliferation in a Tissue and Subset-Specific Manner During Normal Mouse Pregnancy

The regulation of T cell homeostasis during pregnancy has important implications for maternal tolerance and immunity. Evidence suggests that Programmed Death-1 (PD-1) participates in regulation of T cell homeostasis and peripheral tolerance. To examine the contribution of PD-1 signaling on T cell homeostasis during normal mouse pregnancy, we examined T cell number or proportion, PD-1 expression, proliferation, and apoptosis by flow cytometry, BrdU incorporation, and TUNEL assay in pregnant mice given anti-PD-1 blocking antibody or control on days 10, 12, and 14 of gestation. We observed tissue, treatment, and T cell-specific differences in PD-1 expression. Both pregnancy and PD-1 blockade increased T cell proliferation in the spleen, yet this effect was limited to CD4 T cells in the uterine- draining nodes. In the uterus, PD-1 blockade markedly altered the composition of the T cell pool. These studies support the idea that pregnancy is a state of dynamic T cell homeostasis and suggest that this state is partially supported by PD-1 signaling.     

Updating on the Pathogenic Mechanisms 5 of the Antiphospholipid Antibodies-Associated Pregnancy Loss

Anti-phospholipid antibodies (aPL) are risk factor for recurrent pregnancy loss and obstetrical complications. The mechanisms of aPL-mediated pregnancy failure are still a matter of research. Although aPL are associated with thrombosis, thrombotic events cannot explain all the miscarriages. There is evidence for a direct in vitro aPL effect on the trophoblast as shown by their binding; reduction of proliferation, human chorionic gonadotrophin release, in vitro invasiveness, adhesion molecule expression; and increased apoptosis. Such a direct reactivity is supported by the expression of beta2 glycoprotein (beta 2GP) I on trophoblast cell membranes. aPL/anti-beta 2GPI antibodies also bind to human decidual/endometrial cells in vitro and induce a pro-inflammatory phenotype. APL-mediated inflammatory processes at the placental level are apparently responsible for fetal loss at least in animal models. Both complement activation and pro-inflammatory cytokine/chemokine secretion have been shown to play a role. More recently, complement-induced tissue factor expression on infiltrating neutrophils was described as an additional pathogenic mechanisms mediated by aPL. As a whole, these findings do suggest that aPL may induce a defective placentation by acting at different levels without involving necessarily thrombotic events.     

Simvastatin has deleterious effects on human first trimester placental explants

BACKGROUND: Statins inhibit 3-hydroxy-3-methylglutaryl coenzyme-A reductase (HMG-CoA reductase), the rate-limiting enzyme of the mevalonate pathway, and have been used successfully in the treatment of hypercholesterolaemia. Animal models have provided evidence for the teratogenic effects of statins on pregnancy outcome. Thus statins are contraindicated during pregnancy. However, conflicting data are available from inadvertent use of statins in human pregnancy. Therefore we decided to explore the effects of simvastatin on the placenta in an in vitro human placental model. METHODS: Human first trimester placental explants that were grown on matrigel were exposed to medium supplemented with simvastatin. Migration of extravillous trophoblast cells was assessed by visual observation. Proliferative and apoptotic events of the trophoblast cells were assesed by immunohistochemical examination using anti-Ki67 and anti-activated caspase-3 antibodies respectively. Hormone levels were measured. RESULTS: Simvastatin sharply inhibited migration of extravillous trophoblast cells from the villi to the matrigel (P < 0.05). Moreover, simvastatin inhibited half of the proliferative events in the villi (P < 0.05) and increased apoptosis of cytotrophoblast cells compared to control. Moreover, simvastatin significantly decreased secretion of progesterone from the placental explants (P < 0.01). CONCLUSION: Simvastatin adversely affects human first trimester trophoblast.     

Secretory characteristics and viability of human term placental tissue after overnight cold preservation

Collection of human term placentae for research purposes is generally limited during working hours. Preserving placental tissue overnight might help to postpone experiments and, by extent, to increase material availability. In this study, fragments from normal placentae were incubated at 37 degrees C either immediately after delivery or after preservation at 4 degrees C in a HEPES-buffered solution or in a Roswell Park Memorial Institute (RPMI) 1640 culture medium. Protein, human chorionic gonadotrophin (HCG), human placental lactogen (HPL) and lactate dehydrogenase (LDH) contents within preserved explants were similar to those within freshly delivered ones. In contrast, HCG and HPL amounts released during incubation of preserved tissue were lower than with freshly delivered tissue. Differences were significant only during the first 3 h of incubation. Hormone releases were similarly Ca(2+)-stimulated, and Co(2+)- and low temperature-inhibited in preserved and freshly delivered tissues. After preservation, LDH leakage was also reduced. Furthermore, before and after 37 degrees C incubation during 6 h, preserved tissue was morphologically indistinguishable from freshly delivered tissue and showed neither higher incidence of DNA fragmentation, nor elevated caspase-3 activity, both of which are markers of apoptosis. This study validates an original, useful and rapid method to preserve placental tissue. Consequently, this preservation model may facilitate the study of physiological processes regulating placental hormone secretion in normal and pathological conditions.     

Placental Interleukin‐15 Expression in Recurrent Miscarriage

Citation Toth B, Haufe T, Scholz C, Kuhn C, Friese K, Karamouti M, Makrigiannakis A, Jeschke U. Placental Interleukin‐15 expression in recurrent miscarriage. Am J Reprod Immunol 2010; 64: 402–410 Problem Cytokines play a fundamental role at the feto–maternal interface. A dysregulation of the cytokine profile could be linked with fetal rejection. This study investigated differences in the expression of the Th1 cytokine interleukin‐15 (IL‐15) of normal and disturbed pregnancy. Method of study Analysis of IL‐15 expression by immunohistochemistry and real‐time RT‐PCR in placental tissue from normal pregnancies, spontaneous miscarriage and recurrent miscarriage (RM) was performed. Results Expression of IL‐15 was upregulated on mRNA and protein level in the placenta of miscarriage patients, especially in patients with RM. Immunohistochemistry and immunofluorescence double staining revealed extravillous trophoblast cells (EVT) as IL‐15‐expressing cells. Staining results were confirmed by real‐time PCR (TaqMan). Conclusion Increased expression of IL‐15 in the decidua of patients with RM may be linked to disturbed implantation and vascularization with consecutive placental and fetal rejection.     

正常足月胎盘和胎儿宫内生长迟缓胎盘中滋养细胞的凋亡及相关基因表达

目的 比较正常足月胎盘与胎儿宫内生长迟缓胎盘（IUGR）中的滋养细胞凋亡指数,以及bcl-2和fas的表达,以探讨滋养细胞的凋亡与bcl-2和fas表达的关系。方法 取正常足月胎盘组织和I－UGR胎盘组织各5例,固定、石蜡包埋、切片,每组分别TUNEL法以及ABC法抗bcl－2和抗fas免疫组织化学染色。镜下计数滋养细胞的凋亡指数,并对bcl-2和fas的表达量进行显微图像分析。结果 与正常足月胎盘相比,IUGR胎盘的凋亡指数显著增多（P＜0．01）,bcl－2表达量显著减低（P＜0．01）,而fas表达量无显著差异（P＞0．05）。结论 IUGR胎盘滋养细胞的凋亡指数明显增多可能与细胞bcl-2表达量减少有关,而不受fas表达量的影响。     

Apoptosis in acute shigellosis is associated with increased production of Fas/Fas ligand,perforin, caspase-1, and caspase-3 but reduced production of Bcl-2 and interleukin-2

Shigella dysenteriae type 1-induced apoptotic cell death in rectal tissues from patients infected with Shigella dysenteriae type 1 was studied by the terminal deoxynucleotidyltransferase-mediated dUTP-biotin nick end labeling (TUNEL) technique and annexin V staining. Expression of proteins and cytokines participating in the apoptotic process (caspase-1, caspase-3, Fas [CD95], Fas ligand [Fas-L], perforin, granzyme A, Bax, WAF-1, Bcl-2, interleukin-2 [IL-2], IL-18, and granulocyte-macrophage colony-stimulating factor) in tissue in the acute and convalescent stages of dysentery was quantified at the single-cell level by in situ immunostaining. Apoptotic cell death in the lamina propria was markedly up-regulated at the acute stage (P < 0.05), where an increased number of necrotic cells were also seen. Phenotypic analysis of apoptotic cells revealed that 43% of T cells (CD3), 10% of granulocytes (CD15), and 5% of macrophages (CD56) underwent apoptosis. Increased activity of caspase-1 persisted in the rectum up to 1 month after onset. More-extensive expression of Fas, Fas-L, perforin, caspase-3, and IL-18, but not IL-2, at the acute stage than at the convalescent stage was observed. Increased expression of caspase-3 and IL-18 in tissues with severe inflammation compared to expression in those with mild inflammation was evident, implying a possible role in the perpetuation of inflammation. Significantly reduced cell death during convalescence was associated with a significant up-regulation of Bcl-2, Bax, and WAF-1 expression in the rectum compared to that in the acute phase of infection. Thus, induction of apoptosis at the local site in the early phase of S. dysenteriae type 1 infection was associated with a significant up-regulation of Fas/Fas-L and perforin and granzyme A expression and a down-regulation of Bcl-2 and IL-2, which promote cell survival.