Yasuyuki Negishi

Disruption of maternal immune balance maintained by innate DC subsets results in spontaneous pregnancy loss in mice.

Dendritic cells (DCs) play an important role in providing an appropriate fetal/maternal balance between Th1 and Th2 during pregnancy. The Th1/Th2 balance seems to be regulated mainly by two distinct DC subsets, DEC-205(+) DCs having the capacity to establish Th1 polarization and 33D1(+) DCs to induce Th2 dominance. Pregnancy is established and maintained by maternal hormones, such as progesterone and estrogen, and the balance of DC subtypes was affected mainly by progesterone, which induced a dose-dependent reduction of the DEC-205/33D1 ratio together with/without a stable amount of estrogen. The DEC-205/33D1 ratio decreased gradually with the progress of pregnancy and rapid augmentation of the ratio was seen around delivery in vivo. Here, we demonstrate that depletion of 33D1(+) DCs during the perinatal period caused substantial fetal loss probably mediated through Th1 up-regulation via transient IL-12 secretion, and pre-administration of progesterone could rescue the fetal loss. Similar miscarriages were also observed when pregnant mice were intraperitoneally (i.p.) injected twice with IL-12 on Gd 9.5 and 10.5. Moreover, prior inoculation of progesterone suppressed the enhanced serum IL-12 production in mice treated with 33D1 antibody, indicating that progesterone might inhibit temporal IL-12 secretion around Gd 10.5 and miscarriage was avoided. These findings suggest the importance of balancing DC subsets during pregnancy and reveal that we can avoid miscarriage by manipulating the activity of the DC subpopulation of pregnant individuals with maternal hormones.

Effects of extracellular pH and hypoxia on the function and development of antigen-specific cytotoxic T lymphocytes.

The major effector cells for cellular adaptive immunity are CD8(+) cytotoxic T lymphocytes (CTLs), which can recognize and kill virus-infected cells and tumor cells. Although CTLs exhibit strong cytolytic activity against target cells in vitro, a number of studies have demonstrated that their function is often impaired within tumors. Nevertheless, CTLs can regain their cytotoxic ability after escaping from the tumor environment, suggesting that the milieu created by tumors may affect the function of CTLs. As for the tumor environment, the patho-physiological situation present in vivo has been shown to differ from in vitro experimental conditions. In particular, low pH and hypoxia are the most important microenvironmental factors within growing tumors. In the present study, to determine the effect of these factors on CTL function in vivo, we examined the cytolytic activity of CTLs against their targets using murine CTL lines and the induction of these cells from memory cells under low pH or hypoxic conditions using antigen-primed spleen cells. The results indicated that both cytotoxic activity and the induction of functional CTLs were markedly inhibited under low pH. In contrast, in hypoxic conditions, although cytotoxic activity was almost unchanged, the induction of CTLs in vitro showed a slight enhancement, which was completely abrogated in low pH conditions. Therefore, antigen-specific CTL functions may be more vulnerable to low pH than to the oxygen concentration in vivo. The findings shown here provide new therapeutic approaches for controlling tumor growth by retaining CTL cytotoxicity through the maintenance of higher pH conditions.

Prophylactic intratubal injection of methotrexate after linear salpingostomy for prevention of persistent ectopic pregnancy

Aim:  To examine the efficacy of local methotrexate (MTX) administration following linear salpingostomy for tubal pregnancy in the prevention of persistent ectopic pregnancy (PEP).

α-Galactosylceramide-activated murine NK1.1(+) invariant-NKT cells in the myometrium induce miscarriages in mice.

Innate immunity, which is unable to discriminate self from allo‐antigens, is thought to be important players in the induction of miscarriages. Here, we show that the administration of IL‐12 to syngeneic‐mated C57BL/6 mice on gestation day 7.5 (Gd 7.5), drives significant miscarriages in pregnant females. Furthermore, the administration on Gd 7.5 of α‐galactosylceramide (α‐GalCer), which is known to activate invariant natural killer T (iNKT) cells, induced miscarriages in both syngeneic‐mated C57BL/6 mice and allogeneic‐mated mice (C57BL/6 (♀) × BALB/c (♂)). Surprisingly, the percentages of both DEC‐205+ DCs and CD1d‐restricted NK1.1+ iNKT cells were higher in the myometrium of pregnant mice treated i.p. with α‐GalCer than in the decidua. IL‐12 secreted from α‐GalCer‐activated DEC‐205+ DCs stimulated the secretion of cytokines, including IL‐2, IL‐4, IFN‐γ, TNF‐α, perforin, and granzyme B, from the NK1.1+ iNKT cells in the myometrium, leading to fetal loss in pregnant mice. Finally, the i.p. administration of IL‐12 and/or α‐GalCer in iNKT‐deficient Jα18(‐/‐) (Jα18 KO) mice did not induce miscarriages. This study provides a new perspective on the importance of the myometrium, rather than the decidua, in regulating pregnancy and a mechanism of miscarriage mediated by activated DEC‐205+ DCs and NK1.1+ iNKT cells in the myometrium of pregnant mice.

Distribution of invariant natural killer T cells and dendritic cells in late pre-term birth without acute chorioamnionitis

Acute chorioamnionitis (aCAM) is an important cause of pre‐term birth. However, little is known about the pathogenesis of late pre‐term birth without aCAM that was the most common category of pre‐term birth. Here we analyze the kinetics of immune cells obtained from the decidua of women with late pre‐term births with and without aCAM.

Effect of sera on the adhesion of natural killer cells to the endothelium in severe pre‐eclampsia

Objective:  To investigate the effect of serum on the interaction between natural killer (NK) cells and endothelial cells in pre‐eclampsia.

Paraneoplastic cerebellar degeneration caused by ovarian clear-cell carcinoma

Paraneoplastic cerebellar degeneration is a paraneoplastic neurological syndrome caused by the remote effect of certain systemic cancers and is characterized by subacute cerebellar symptoms. A 62‐year‐old woman suffering from unidentified cerebellar symptoms was admitted to our hospital. Paraneoplastic cerebellar degeneration was suspected and ovarian cancer was detected after the systemic examination for malignancy. The symptoms of vertigo and dysarthria were improved a little after surgical operation and treatments of γ‐globulin, steroid pulse and tacrolimus hydrate. The cerebellar symptoms of paraneoplastic cerebellar degeneration are often evident prior to detection of malignancy. It is important to perform systemic examination for malignancy in case of unidentified cerebellar symptoms.

Effects of Dendritic Cell Subset Manipulation on Airway Allergy in a Mouse Model.

Background: Two major distinct subsets of dendritic cells (DCs) are arranged to regulate immune responses: DEC-205+ DCs drive Th1 polarization and 33D1+ DCs establish Th2 dominancy. Th1 polarization can be achieved either by depletion of 33D1+ DCs with a 33D1-specific monoclonal antibody (mAb) or by activation of DEC-205+ DCs via intraperitoneal injection of α-galactosylceramide (α-GalCer). We studied the effect of 33D1+ DC depletion or DEC-205+ DC activation in vivo using an established mouse model of allergic rhinitis (AR). Methods: Mice were injected intraperitoneally with OVA plus alum and challenged 4 times with daily intranasal administration of OVA. Immediately after the last challenge, allergic symptoms such as sneezing and nasal rubbing as well as the number of cells in the bronchoalveolar lavage fluid (BALF) and nasal lavage fluid (NALF) were counted. The levels of serum OVA-specific IgG1, IgG2a, and IgE were also determined by ELISA. Results: The allergic symptom scores were significantly decreased in 33D1+ DC-depleted or DEC-205+ DC-activated AR mice. The levels of OVA-specific IgG1, IgG2a, and IgE, and the number of NALF cells, but not BALF cells, were reduced in 33D1+ DC-depleted but not in DEC-205+ DC-activated AR mice. Moreover, the activated DEC-205+ DCs suppressed histamine release from IgE-sensitized mast cells, probably through IL-12 secretion. Conclusions: The manipulation of innate DC subsets may provide a new therapeutic strategy for controlling various allergic diseases by reducing histamine release from IgE-sensitized mast cells by driving the immune response towards Th1 dominancy via activation of DEC-205+ DCs in vivo.

Suppression of murine tumour growth through CD8+ cytotoxic T lymphocytes via activated DEC-205+ dendritic cells by sequential administration of α-galactosylceramide in vivo

Cancer immunity is mediated through the effective priming and activation of tumour‐specific class I MHC molecule‐restricted CD8+ cytotoxic T lymphocytes (CTLs). DEC‐205+ dendritic cells (DCs) can cross‐present the epitope(s) of captured tumour antigens associated with class I MHC molecules alongside co‐stimulatory molecules to prime and activate tumour‐specific CD8+ CTLs. Immunosuppressive tolerogenic DCs with reduced co‐stimulatory molecules may be a cause of impaired CTL induction. Hepa1‐6‐1 cells were established from the mouse hepatoma cell line Hepa1‐6; these cells grow continuously after subcutaneous implantation into syngeneic C57BL/6 (B6) mice and do not prime CD8+ CTLs. In this study, we show that the growth of ongoing tumours was suppressed by activated CD8+ CTLs with tumour‐specific cytotoxicity through the administration of the glycolipid α‐galactosylceramide (α‐GalCer), which is a compound known to stimulate invariant natural killer T (iNKT) cells and selectively activate DEC‐205+ DCs. Moreover, we demonstrated that sequential repetitive intraperitoneal inoculation with α‐GalCer every 48 hr appeared to convert tolerogenic DEC‐205+ DCs into immunogenic DCs with a higher expression of co‐stimulatory molecules and a stronger cross‐presentation capacity, which primed CTL precursors and induced tumour‐specific CD8+ CTLs within the tumour environment without activating iNKT cells. These findings provide a new basis for cancer immunotherapy to convert tolerogenic DEC‐205+ DCs within tumours into immunogenic DCs through the sequential administration of an immuno‐potent lipid/glycolipid, and then activated immunogenic DCs with sufficient expression of co‐stimulatory molecules prime and activate tumour‐specific CD8+ CTLs within the tumour to control tumour growth.

Relevance of declines in serum human chorionic gonadotropin levels to the management of persistent ectopic pregnancy

Aim:  To evaluate postoperative declines in serum human chorionic gonadotropin (hCG) levels (percentages of preoperative hCG levels) to rule out persistent ectopic pregnancy (PEP).