Protective Effect of Chlorpromazine Against Endotoxin-Induced Abortion

An Experimental Model for Peri-conceptual COVID-19 Pregnancy Loss and Proposed Interventions to Optimize Outcomes

Reports appear to give reassurance that vertical transmission near term is unlikely, but risks of incidental SARS-CoV-2 infection during fertility treatments, at embryo implantation, or in the first trimester remain unknown. If early pregnancy sequela in the current COVID-19 pandemic are modeled from the 2004 Coronavirus outbreak data, then SARS-CoV-2 infection proximate to blastocyst nidation is likely to cause implantation failure or spontaneous abortion. Our model explains why this outcome is less attributable to virus-associated maternal pulmonary distress and instead derives from systemic inflammation and interference with trophectoderm-endometrium molecular signaling required for implantation. COVID-19 is often accompanied by high levels of IL-6, IL-8, TNF-alpha and other cytokines, a process implicated in pulmonary collapse and systemic organ failure. Yet when regarded in an early reproductive context, this "cytokine storm" of COVID-19 triggers a pro-coagulative state hostile to normal in utero blastocyst/fetal development. Evidence from obstetrics is accumulating to show that mothers with SARS-CoV-2 deliver placentas with abnormal interstitial villi fibrin deposits, diffuse infarcts, and hemangiomatous changes. This model classifies such lesions as permissive at term but catastrophic near embryo implantation or early first trimester pregnancy. Clinical experience with recurrent pregnancy loss offers workable interventions to address this challenge, but success will depend on prompt and accurate SARS-CoV-2 diagnosis. Although no professional guidelines currently exist for SARS-CoV-2 in early pregnancy, this model would warrant a high-risk designation for such cases; these patients should receive priority access to screening and treatment resources.

Neuropharmacological agents modifying endotoxin-induced changes in mice

A variety of neuropharmacological agents were tested to elucidate how chlorpromazine influenced an endotoxin-induced reaction. The results obtained, particularly with beta-adrenergic blocking agents, reserpine and fusaric acid, suggested that the primary locus of chlorpromazine's action was mediated by peripheral beta-adrenergic receptor blockade. Such a locus is compatible with the low doses of propranolol which suppress the reaction, and with successful treatment of shock with dopamine.

Disrupted PI3K p110δ Signaling Dysregulates Maternal Immune Cells and Increases Fetal Mortality In Mice

Maternal immune cells are an integral part of reproduction, but how they might cause pregnancy complications remains elusive. Macrophages and their dual function in inflammation and tissue repair are thought to play key yet undefined roles. Altered perinatal growth underpins adult morbidity, and natural killer (NK) cells may sustain fetal growth by establishing the placental blood supply. Using a mouse model of genetic inactivation of PI3K p110δ, a key intracellular signaling molecule in leukocytes, we show that p110δ regulates macrophage dynamics and NK-cell-mediated arterial remodeling. The uterus of dams with inactive p110δ had decreased IFN-γ and MHC class II^low macrophages but enhanced IL-6. Poor vascular remodeling and a pro-inflammatory uterine milieu resulted in fetal death or growth retardation. Our results provide one mechanism that explains how imbalanced adaptations of maternal innate immune cells to gestation affect offspring well-being with consequence perinatally and possibly into adulthood.

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Genetic inactivation of p110δ in pregnant mice perturbs maternal immune cells

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Uterine NK cells produce less cytokines, resulting in fetal growth restriction

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Inflammatory macrophages are overrepresented, resulting in increased fetal loss

Soluble BAFF-R produced by decidual stromal cells plays an inhibitory role in monocytes and macrophages

A sophisticated immunological regulation between decidual stromal cells (DSC) and monocytes and macrophages is essential for the successful symbiosis of the mother and her fetus, but the mechanisms remain incompletely understood. The mRNA and proteins of B lymphocyte stimulator (BAFF, also known as BLys) and its receptor, BAFF-R (also known as BR3, CD268 or TNFRSF17), have been detected in both first-trimester and term placentas, but whether BAFF or BAFF-R participates in the cross-talk between DSC and monocytes and macrophages in the first-trimester pregnancy has not been described. This study found that purified DSC extensively shed BAFF-R and that polyinosinic:polycytidylic acid (poly(I:C); a synthetic toll-like receptor (TLR) 3 agonist) dramatically up-regulated BAFF-R secretion, suggesting that release of these soluble proteins was an inherent property of DSC and its induction might have relevance to TLR-3-mediated signal transduction. When monocytes were cultured with the supernatants of resting DSC or poly(I:C)-treated DSC, the proliferation of CD14(+)HLA-DR(+) monocytes (P=0.025 and 0.045) and the secretion levels of tumour necrosis factor α (P=0.035 and 0.031) and interleukin 6 (P=0.021 and 0.035) were significantly increased after the BAFF-R was blocked. Soluble BAFF-R may play inhibitory roles in monocytes and macrophages.

Lipopolysaccharide (LPS)-induced Interferon (IFN)-gamma production by decidual mononuclear cells (DMNC) is interleukin (IL)-2 and IL-12 dependent

PROBLEM

Th1-shifted immune response is believed to be harmful for successful pregnancy because of activation of maternal cytotoxic T lymphocytes and natural killer cells. However, its effects on Toll-like receptor (TLR)-mediated innate immune response are so far unknown and this study has been undertaken to address the issue.

METHOD OF STUDY

decidual tissues were obtained from 16 pregnant women undergoing elective termination during the first trimester pregnancy for socioeconomic reasons. Decidual Mononuclear Cells (DMNC) were stimulated with suboptimal doses of IL-2 and IL-12 with/without LPS, considered to be a TLR4 ligand, for 48 hr. Productions of IFN-γ and tumor necrosis factor (TNF)-α in culture supernatant were measured with ELISA.

RESULTS

(i) IFN-γ production was induced with LPS alone which was strongly up-regulated in the presence of IL-2 and IL-12. (ii) TNF-α was also induced by LPS but was not affected by the presence of IL-2 and IL-12.

CONCLUSION

IL-2 and IL-12 up-regulated the production of IFN-γ in DMNC through increasing their susceptibility to LPS. TNF-α production is independent of such a mechanism.

Spontaneous pregnancy loss mediated by abnormal maternal inflammation in rats is linked to deficient uteroplacental perfusion

Abnormal maternal inflammation during pregnancy is associated with spontaneous pregnancy loss and intrauterine fetal growth restriction. However, the mechanisms responsible for these pregnancy outcomes are not well understood. In this study, we used a rat model to demonstrate that pregnancy loss resulting from aberrant maternal inflammation is closely linked to deficient placental perfusion. Administration of LPS to pregnant Wistar rats on gestational day 14.5, to induce maternal inflammation, caused fetal loss in a dose-dependent manner 3-4 h later, and surviving fetuses were significantly growth restricted. Pregnancy loss was associated with coagulopathy, structural abnormalities in the uteroplacental vasculature, decreased placental blood flow, and placental and fetal hypoxia within 3 h of LPS administration. This impairment in uteroplacental hemodynamics in LPS-treated rats was linked to increased uterine artery resistance and reduced spiral arteriole flow velocity. Pregnancy loss induced by LPS was prevented by maternal administration of the immunoregulatory cytokine IL-10 or by blocking TNF-α activity after treatment with etanercept (Enbrel). These results indicate that alterations in placental perfusion are responsible for fetal morbidities associated with aberrant maternal inflammation and support a rationale for investigating a potential use of immunomodulatory agents in the prevention of spontaneous pregnancy loss.

Cytokines: Important for implantation?

PROBLEM

Cytokines are obviously very important in an established pregnancy, but what about human embryo implantation?

METHODS

Literature review.

RESULTS

We first discuss the necessity and limits of animal models, and then review the few cytokines which have been demonstrated by knock-out methods to be absolutely necessary for embryo implantation using in animal models. We then review what is known or discussed about the role of other cytokines as deduced from quantitative and/or qualitative dysregulation in animals and in humans.

CONCLUSIONS

Cytokines are indeed involved in implantation as they are in ongoing pregnancy and delivery. Relevance to infertility and recurrent pregnancy loss is discussed.

MD-1 is a critical part of the mechanism causing Th1-cytokine-triggered murine fetal loss syndrome

PROBLEM

Fetal loss syndrome (abortion/resorption) occurring on or after gestation day (gd) 9.5 in CBA/JxDBA/2 matings is dependent upon presence of TNF-alpha + IFN-gamma, which act by increasing expression of fg12 prothrombinase at the feto-maternal interface. The magnitude by which the abortion rate can be boosted by an injection of these cytokines on gd 7.5 depends on endogenous rate of loss, and appears to depend on microbial flora. Is cytokine-triggered abortion dependent upon a third signaling pathway that senses 'danger'?

METHODS

Female CBA/J were mated to DBA/2 males and, C57B1/6 and C57B1/6 TNFalphaR1-/-Mak were mated to C57B1/6 control or TNFalphaR1-/-Mak males. LPS from Escherichia coli and Salmonella enteritidis, or the combination of TNF-alpha + IFN-gamma, was injected to stimulate abortions. The effect of anti-MD-1, which interferes with expression of CD14 and, hence, with signaling by LPS via the CD14-tlr4 complex, on TNF-alpha + IFN-gamma was tested. The presence of MD-1 in the uterus was evaluated by in situ hybridization, and effect of lipopolysaccharide (LPS) on mice lacking TNF-alphaR1 was tested.

RESULTS

Anti-MD-1 completely abrogated TNF-alpha + IFN-gamma-induced abortions. MD-1 was expressed on trophoblast and in deciduas on gd 8.5 but LPS could not abort mice that lacked the type 1 receptor for TNF-alpha. Pregnant CBA/J females had classical resorptions (abortions) countable on gd 13.5-14.5 in response to LPS from E. coli or S. enteritidis, but C57B1/6 strain mice resorbed only in response to the latter, and E. coli LPS appeared to induce 'occult' losses. 'Occult' loss did not require TNF-alphaR1.

CONCLUSIONS

TNF-alpha + IFN-gamma could not induce murine abortions without co-presence of a 'danger' signal such as LPS acting via CD14 on toll receptors, and LPS could not act without co-signaling by TNF-alpha. Classical resorptions/abortions and 'occult' losses have a different mechanism in these models as reflected in type of endotoxin and requirement for TNF-alphaR1 signaling.

Role of the maternal acute phase response and tumor necrosis factor alpha in the developmental toxicity of lipopolysaccharide in the CD-1 mouse

The acute phase response (APR) functions to reset metabolic homeostasis following infectious, toxic, or traumatic insult. TNF-alpha, a putative mediator of the APR, has been associated with fetal death in rodents and preterm labor and delivery in humans. We hypothesized that physiologic changes associated with the maternal APR may play a role in adverse embryo/fetal outcome. Pregnant CD-1 mice injected i.p. with lipopolysaccharide (LPS), a model inducer of the APR, on gestation day (gd) 9 showed a dose-related increase in embryo death on gd 10. Histology indicated placental infarct and necrosis. Maternal serum TNF-alpha levels, measured by ELISA following administration of 0.05 mg/kg LPS on gd 9, were found to increase significantly and peak within 1 to 1.5 h. Pretreatment with 0.01 mg/kg LPS on gd 8 ameliorated embryotoxicity of the 0.05 mg/kg LPS treatment on gd 9 and also eliminated the increase in serum TNF-alpha. Direct LPS exposure in whole embryo culture was nontoxic. These data support a maternally mediated mechanism of LPS embryolethality, and suggest that TNF-alpha may be an important mediator of this developmental toxicity.

A brief review of recent data on some cytokine expressions at the materno-foetal interface which might challenge the classical Th1/Th2 dichotomy

Focussing attention on cytokines at the materno-foetal interface represents one of the major advances made in the field. This owes much to the visionary views of Tom Wegmann, and to the changes brought about in the field by immunotrophism and Th1/Th2 paradigms. We review these briefly and also point out some emerging problems.However, a certain number of newly discovered cytokines do not fit into the classical Th1/Th2 dichotomy. Yet, by their capacity to activate or downregulate NK cells, by their action on adhesion molecules, and by their regulatory effects on the vascularisation process, they are of possible interest within the materno-foetal relationship. Therefore, as a first step, we have undertaken a systematic study of the expression of IL-11, IL-12, IL-13, IL-15, IL-16, IL-17 and IL-18 in the uterus, the peri-implantation embryo, and later on decidual and placental tissues throughout pregnancy. These cytokines were detected in every case, with, in each case, a precise localisation, which will be detailed, and which indeed suggests important regulatory functions, especially during implantation. In some cases, as will be shown in the peri-implantation uterus, those cells are perfectly expressed by uterine GMG-NK-like cells. Comparative ELISAs and quantitative RT-PCR have been or are being conducted, but already the expression patterns that are observed, and the very precise window of appearance that is observed for some of the GMG NK-like cells, either around or in the implanting embryo, as well as the complexity of the respective distributions, strongly suggest that, as useful as it certainly was for a while, the Th1/Th2 paradigm must now be considered as an over-simplification. Rather, the existing data point to sequential windows and are suggestive of a system where an extreme complexity is allied to very precise timing and tuning. They also suggest that the materno-foetal relationship is not simply maternal tolerance of a foreign tissue, but a series of intricate mutual cytokine interactions governing selective immune regulation and also control of the adhesion and vascularisation processes during this dialogue.

Lipopolysaccharide (LPS)-induced intra-uterine fetal death (IUFD) in mice is principally due to maternal cause but not fetal sensitivity to LPS

The present study deals with whether lipopolysaccharide (LPS)-induced intra-uterine fetal death (IUFD) is related to LPS-susceptibility of either mother or fetus and how LPS or LPS-induced TNF causes IUFD. LPS-susceptible C3H/HeN or -hypo-susceptible C3H/HeJ pregnant mice and the mice mated reciprocally with these mice were used on days 14 to 16 of gestation for experiments. All of fetuses in pregnant C3H/HeN mice mated with either C3H/HeN males [HeN(HeN)] or C3H/HeJ males [HeN(HeJ)] were killed within 24 hr when injected intravenously (i.v.) with 50 or 100 microg of LPS. On the other hand, the majority of fetuses in C3H/HeJ females mated with either C3H/HeJ males [HeJ(HeJ)] or C3H/HeN males [HeJ(HeN)] survived when injected i.v. with even 400 microg of LPS. These findings indicate that LPS-induced IUFD depends on the maternal LPS-responsiveness. LPS injected into mothers could pass through placenta to fetuses, since an injection with 125I-labeled LPS or IgG into pregnant mice resulted in considerable levels of radioactivity in fetuses as well as placenta. Cultured peritoneal macrophages derived from F1 mice of HeJ(HeN) or HeN(HeJ) mice, produced nitric oxide (NO) and tumor necrosis factor (TNF) in response to LPS, although the levels of NO and TNF were lower in comparison with those of C3H/HeN macrophage cultures, suggesting a possibility that the fetus as well as F1 cells might be responsible to LPS. LPS-induced IUFD was not blocked by treatment with anti-TNF antibody which inhibited LPS-induced TNF production in pregnant females, although an injection of recombinant TNFalpha instead of LPS could induce IUFD, suggesting that the cause of IUFD cannot be attributed to mother-derived TNF alone. The roles of LPS passed through placenta and LPS-induced mediators on IUFD were discussed.

Onapristone (ZK299) blocks the suppressive effect of progesterone, but not that of dexamethasone, on inducible nitric oxide synthase gene expression and nitric oxide production in murine macrophages

Suppressive effects of progesterone on inducible nitric oxide synthase (iNOS) protein expression and nitric oxide (NO) production in murine peritoneal macrophages in response to bacterial lipopolysaccharide (LPS) and the inhibition of the suppressive activity of progesterone by onapristone (ZK299), a synthetic progesterone inhibitor, were studied. Progesterone suppressed dose-dependently LPS-induced NO production by macrophages, and scarcely detectable expression of iNOS was seen in the macrophages. ZK299 liberated the macrophages from the inhibitory effect of progesterone. Although dexamethasone, a synthetic glucocorticoid, can potently suppress LPS-induced NO production by macrophages, ZK299 did not liberate the suppression by dexamethasone, suggesting that these two corticosteroids induce suppression through independent mechanisms. RT-PCR analysis showed that murine macrophages expressed no progesterone-receptor. These findings indicate that the inhibitory effect of progesterone occurs at least on the level of iNOS protein expression in the signaling pathway after the LPS-stimulus. Furthermore, our present data may suggest the existence of a yet unknown type of progesterone-receptor in murine macrophages, the binding to which is responsible for the inhibitory effect of progesterone, or that progesterone may act non-specifically on the macrophages without involvement of any receptor.

Immunoactive products of placenta. VI. Induction of transient murine T cell anergy by a low-molecular-weight compound obtained from supernatants of human placental cultures

A low-molecular-weight material present in human placental supernatant (lymphocyte proliferation inhibiting factor, LPIF, or filtrate) can induce tolerance/hyporesponsiveness in vivo. We already knew from previous experiments that this material acted only on preactivated or malignant T cells, and even the malignant cells could be rescued from its action if cells were washed quickly after contact. To understand the mechanisms of its action, we have set up systems of specific stimulation. The material inhibits anti-Vbeta-specific stimulation. In a mixed lymphocyte reaction if responder cell populations from a first MLR performed in the presence of LPIF are harvested, extensively washed to discard suppressor molecules, and restimulated by related or third-party lymphocytes in an H2-incompatible combination, the response to a third-party stimulator (a primary one) is unaffected by prior exposure to the material, which nevertheless renders the population unresponsive to restimulation by the original MHC-stimulating haplotype. Cells triggered by anti-Vbeta6 antibodies in the presence of LPIF are unable to undergo restimulation by the very same anti-Vbeta6 MoAb, while they conserve their capacity to proliferate in a primary fashion in response to the unrelated anti-Vbeta8 MoAb. When analyzed by FACS using anti-Vbeta FITC-conjugated MoAbs, cells that are unresponsive or blocked in their proliferation by the action of the filtrate after anti-Vbeta stimulation are still live and unexpectedly transiently hyperexpress the TcR. These findings confirm the requirement for T cell stimulation for suppression to be enacted and demonstrate that such is exerted by anergy rather than by clonal deletion, at least in vitro.

Biological activities of endotoxins detoxified by alkylation

It has been previously observed that lipopolysaccharides can be detoxified by alkylation and yet retain their adjuvant activity. Our present findings confirm these results and show, moreover, that these derivatives did not lose their capacity to protect mice against lethal irradiation and lost only partially their ability to interrupt pregnancy or to induce blast transformation of murine B-lymphocytes. However, in contrast with lipopolysaccharides, these alkylated preparations did not enhance the nonspecific resistance of mice to a bacterial infection. The various bilogical functions of endotoxins can therefore be separated and are not uniformly related to their toxicity.