Decidua-associated suppressor cells in abortion-prone DBA/2-mated CBA/J mice that release bioactive transforming growth factor beta2-related immunosuppressive molecules express a bone marrow-derived natural suppressor cell marker and gamma delta T-cell receptor.

The decidua of allopregnant mice contains a novel population of Thy1 Lyt1 CD4 CD8 asialoGM1- non-B small lymphocytic suppressor cells that release transforming growth factor (TGF) SS2-related suppressor molecules. The "null" phenotype of this cell population is similar to some bone marrow-derived natural suppressor cell (NSC) populations, and the latter may release TGF(beta)s. We now report that the TGF beta2-producing suppressor cells in the uterine decidua of DBA/2-mated CBA/J female mice-linked to prevention of abortions-are inactivated effectively by 1E5/B5.1 but not by 2C1.1 rat monoclonal antibodies to murine pregnancy-associated splenic NSC in the presence of complement. Immunostaining of a subpopulation of cells in decidua with 1E5/B5.1 but not with 2C1.1 was shown by flow cytometry. Release of suppressor factor was also abrogated by 1E5/B5.1 + complement but not by 2C1.1 + complement, and the suppressor factor was specifically neutralized by anti-TGF beta2 and not by anti-TGF beta3. Splenic pregnancy NSC are susceptible to 2C1.1, produce TGF beta1, and express CD3 and alpha beta T-cell receptor (TcR) chains. Release of suppressor factor by the decidual NSC was abrogated by treatment with anti-CD3 (145 2C11) and anti-TcR gamma delta (GL4) monoclonal antibodies + complement, but not by anti-TcR alpha beta (H57) + complement; and cells sorted using anti-TcR gamma delta (GL3) released suppressive activity in vitro. Slightly more suppressive activity was released by implantation-site decidua where there was no epithelium than from epithelialized inter-implantation-site decidua; no significant activity was released from placental tissue, but combining implantation-site tissue with placental tissue led to release of enhanced levels of immunosuppressive activity. There appear to be subtypes of bone marrow-derived TcR+ NSC with different phenotypes and tissue localization patterns in pregnancy. The previously reported dependence of decidual NSC activity on the presence of soluble signals from fetal trophoblast may be explainable by the ability of cells bearing TcR gamma delta to recognize and react to placental trophoblast cell antigen.

Psycho-neuro-cytokine/endocrine pathways in immunoregulation during pregnancy.

PROBLEM: Some mammalian pregnancy failure is thought to occur by immunological or immunologically modifiable mechanisms. The original model wherein spontaneous abortion was proposed to represent rejection of the conceptus as an allograft has been supplanted by a model of maternal paraimmunological natural effector cell toxicity to fetal trophoblast more closely related to tumor rejection. The problem is to integrate current information concerning the role of immunological, paraimmunological, endocrinological, and stress-triggered neural factors that determine whether or not abortion will occur. METHODS: Review of existing data. RESULTS: An integrated model is proposed. CONCLUSION: Immunological factors play an important role in abortion processes and prevention of abortions. The existence of abortogenic mechanisms and their regulation appears to be based upon optimizing survival of the species. Two new conceptual models provide a useful framework for further investigation of human pregnancy failure and its treatment.

Transforming growth factor-beta 2-related-decidual suppressor factor is not related to TJ6 protein.

Transforming growth factor (TGF)-beta 2-related-decidual suppressor factor (DSF) and TJ6 protein are both immunosuppressive molecules present in murine and human pregnancy. Treatment of mice with either anti-TJ6 or anti-TGF-beta 2 neutralizing antibodies results in increased fetal loss. Western blots of supernatants from pregnant mouse decidua probed with anti-TJ6 (soluble form) showed a doublet at a similar molecular size as when the blot was probed with anti-TGF-beta 2 antibody. The problem is to determine whether TJ6 and DSF are the same protein. In order to determine if TJ6 and DSF are the same or different proteins, we used affinity column purified TGF-beta 2-DSF and stained Western blots with anti-TJ6. The TGF-beta 2-monoclonal antibody affinity column-purified DSF that stained with anti TGF-beta 2 was not reactive with anti-TJ6 antibody. TJ6 has only a 30% gene sequence homology and a 13% amino acid homology to TGF-beta 2. TJ6 and TGF-beta 2-related DSF appear to be different immunosuppressive proteins in decidua.

Stress-induced murine abortion associated with substance P-dependent alteration in cytokines in maternal uterine decidua.

Stress is known to induce abortions, but underlying mechanisms are unknown. Both alloimmunization and injection of antibody to the asialoGM1 determinant of natural killer cells have been shown to prevent stress-triggered abortion in mice. DBA/2J-mated CBA/J female mice were used to investigate the influence of stress during early gestation on systemic hormone levels and on cytokines in the decidua that are thought to be relevant to abortion in nonstress-related murine abortion. Lowered levels of progesterone did not occur as a result of stress. In stressed mice, increased levels of the abortogenic cytokine tumor necrosis factor alpha (TNF alpha) were associated with decreased levels of pregnancy-protective transforming growth factor beta 2-related suppressive activity in uterine decidua. In the alloimmunized animals where stress failed to boost the abortion rate, these effects were abrogated. Production of TNF alpha may be stimulated by the neurotransmitter substance P (SP); after injection of an SP receptor antagonist or SP-antibody, stress failed to increase the abortion rate above the background level. The increased levels of TNF alpha we observed in the stressed animals were completely abrogated in the animals that had received the SP receptor antagonist; stress also failed to decrease the pregnancy-protective suppressive activity in the decidua of these animals. The data indicate that stress may inhibit protective suppressor mechanisms and promote secretion of abortogenic cytokines such as TNF alpha via neurotransmitter SP.

Stress-triggered abortion: inhibition of protective suppression and promotion of tumor necrosis factor-alpha (TNF-alpha) release as a mechanism triggering resorptions in mice.

PROBLEM: Stress adversely affects pregnancy outcome and has been implicated as an abortogen in both animals and humans. However, the mechanisms whereby stress aborts are largely unknown. Alloimmunization can prevent stress-triggered abortion, and immunization is known to increase transforming growth factor-beta 2 (TGF-beta 2)-related suppressive activity. METHOD: To investigate these mechanisms, DBA/2J males were mated to CBA/J or C3H/HeJ females, and the pregnant females were exposed to ultrasonic sound stress for a period of 24 h between day 4.5 to 8.5 of pregnancy. RESULTS: Ultrasonic stress significantly elevated the resorption rate with a peak effect on day 5.5 in the CBA/J females and on day 4.5 in the LPS-resistant C3H/HeJ females. The tumor necrosis factor-alpha (TNF-alpha) release from the decidua was also elevated and the TGF-beta 2-mediated suppressive activity was significantly decreased. The resorption rate only increased when the TNF-alpha/TGF-beta 2 ratio was increased compared to the control. CONCLUSION: These data suggest that stress may inhibit protective suppressor mechanisms and promote secretion of abortogenic cytokines such as TNF-alpha. Possible mechanisms are discussed.