Ricarda Joachim

Depletion of CD8+ cells abolishes the pregnancy protective effect of progesterone substitution with dydrogesterone in mice by altering the Th1/Th2 cytokine profile

One of the most remarkable immunological regulations is the maternal immune tolerance toward the fetal semiallograft during pregnancy, which has been referred to as immunity’s pregnant pause. Rejection of the semiallogeneic trophoblast cells must be selectively inhibited and pathways presumably include Th2 cytokines unopposed by Th1 cytokines. Steroid hormones, including progesterone, have similar effects. Low levels of progesterone and Th2 cytokines and high levels of Th1 cytokines are attributable for increased abortions in mammalians, which may be triggered by psychoemotional stress. Thus, the aim of the present study was to provide experimental evidence for the mechanism involved in the mediation of immune responses by endocrine signals during pregnancy and stress-triggered pregnancy failure. DBA/2J-mated CBA/J female mice were randomized in three groups: 1) control females, 2) mice exposed to stress on gestation day 5.5, and 3) mice exposed to stress and substituted with dydrogesterone, a progestogen with a binding profile highly selective for the progesterone receptor on gestation day 5.5. On gestation days 7.5, 9.5, and 10.5, mice of each group were sacrificed, and the frequency of CD8+ cells and cytokine expression (IL-4, IL-12, TNF-α, IFN-γ) in blood and uterus cells was evaluated by flow cytometry. Additionally, some mice were depleted of CD8 cells by injection of mAb. We observed that progesterone substitution abrogated the abortogenic effects of stress exposure by decreasing the frequency of abortogenic cytokines. This pathway was exceedingly CD8-dependent, because depletion of CD8 led to a termination of the pregnancy protective effect of progesterone substitution.

Prenatal Stress Enhances Susceptibility of Murine Adult Offspring toward Airway Inflammation

Allergic asthma is one of the most prevalent and continuously increasing diseases in developed countries. Its clinical features include airway hyperresponsiveness and inflammation upon allergen contact. Furthermore, an emerging area of research subsumed as fetal programming evaluates the impact of environmental insults in utero on the incidence of diseases in later life. The aim of this study was to identify whether prenatal exposure to stress, which constitutes a severe environmental insult, perpetuates airway inflammation in later life. Our experiments were performed in mice and revealed that prenatally stressed adult offspring indeed show an increased vulnerability toward airway hyperresponsiveness and inflammation. Furthermore, we provide persuasive insights on dysregulated pathways of the cellular and humoral immune response upon Ag challenge in prenatally stressed adult offspring, reflected by a Th2 greater Th1 adaptive immune response and increased CCR3 and IgE levels in vivo. Additionally, APCs derived from prenatally stressed offspring trigger clonal expansion of Th2 cells in vitro. We also deliver experimental evidence for a reduced corticotrophin-releasing hormone expression in the paraventricular nucleus of adult offspring in response to prenatal stress. Furthermore, behavioral analyses indicate an increase in anxiety in these mice. In conclusion, our data will facilitate future research aiming to identify the individual impact, hierarchy, and redundancy of multiple key protagonists in airway inflammation in an interdisciplinary context. This will foster the substantiation of disease-prevention strategies, such as asthma, during the prenatal period.

The progesterone derivative dydrogesterone abrogates murine stress-triggered abortion by inducing a Th2 biased local immune response

Stress is known to induce abortions in mice and humans, putatively via increased levels of abortogenic Th1 cytokines and a decrease of progesterone. Adequate levels of progesterone exert an antiabortive response through binding to the progesterone-receptor, which induces the release of progesterone-induced blocking factor (PIBF) from lymphocytes. PIBF is highly pregnancy-protective by induction of a Th2 biased immune activity. The aim of this study was to investigate the effect of the progesterone derivative dydrogesterone (6-dehydro-retroprogesterone) in stress-triggered murine abortion. DBA/2J-mated CBA/J female mice were randomized in different groups: two groups were treated with different dydrogesterone dosages in a single injection before exposure to sound stress on Day 5 of pregnancy, one group was exposed to stress without dydrogesterone treatment, the fourth group received no stress and no dydrogesterone. On gestation Day 13, a highly elevated abortion rate was detected in stressed mice compared to control mice. Stressed animals presented lower levels of progesterone and PIBF in plasma and a reduced staining intensity of progesterone receptor at the feto-maternal interface. Injection of dydrogesterone abrogated the effect of stress on the abortion rate. Further, dydrogesterone increased levels of plasma PIBF in stressed mice, but did not affect progesterone levels. Interestingly, dydrogesterone dramatically increased the percentage of IL-4 positive decidual immune cells in stressed mice. Our data suggest that dydrogesterone abrogates stress-triggered abortion by inducing a Th2 biased local immune response.

Indications for a ‘brain–hair follicle axis (BHA)’: inhibition of keratinocyte proliferation and up-regulation of keratinocyte apoptosis in telogen hair follicles by stress and substance P

It has long been suspected that stress can cause hair loss, although convincing evidence of this has been unavailable. Here, we show that in mice sonic stress significantly increased the number of hair follicles containing apoptotic cells and inhibited intrafollicular keratinocyte proliferation in situ. Sonic stress also significantly increased the number of activated perifollicular macrophage clusters and the number of degranulated mast cells, whereas it down‐regulated the number of intraepithelial γδ T lymphocytes. These stress‐induced immune changes could be mimicked by injection of the neuropeptide substance P in nonstressed mice and were abrogated by a selective substance P receptor antagonist in stressed mice. We conclude that stress can indeed inhibit hair growth in vivo, probably via a substance P‐dependent activation of macrophages and/or mast cells in the context of a brain‐hair follicle axis.

Stress enhances airway reactivity and airway inflammation in an animal model of allergic bronchial asthma.

Objective Despite the long-standing clinical assumption that stress and asthma morbidity are associated, convincing experimental evidence on mechanisms has been unavailable. A wide range of immunological, endocrinological, and neuronal pathways are known to mediate and modulate a systemic stress response. Interestingly, most of these mediators play a crucial role in initiating and perpetuating symptoms associated with bronchial asthma. To explore potential mechanisms linking stress to asthma exacerbation we developed an animal model that combines allergic airway inflammation and exposure to stress. Methods CBA/J mice were sensitized by intraperitoneal injection of ovalbumin (OVA) and challenged with OVA aerosol via the airways. Additionally, some mice were stressed by exposure to an ultrasonic stressor. Airway hyperreactivity (AHR) was measured in vitro by electric field stimulation (EFS) of tracheal smooth muscle elements. Bronchoalveolar lavage fluid (BAL) was obtained and cell numbers determined. Cytokine levels of IL-4, IL-5, and IFN-&ggr; in BAL were determined by ELISA. Results Our findings demonstrate that exogenously applied stress dramatically enhances airway reactivity in OVA-sensitized and challenged mice. Further, stress significantly increases allergen-induced airway inflammation identified by increased leukocyte (ie, eosinophil) numbers in bronchoalveolar lavage fluids. Conclusions We found further evidence that stress can indeed exacerbate airway hyperreactivity and airway inflammation in an animal model of allergic bronchial asthma and now introduce a novel murine model to identify stress-triggered pathways, including mediators as neurohormones, neuropeptides, and markers of inflammation.

Introducing a mouse model for pre-eclampsia: adoptive transfer of activated Th1 cells leads to pre-eclampsia-like symptoms exclusively in pregnant mice

Pre‐eclampsia (PE) is the most severe pregnancy‐related disease, leading to high maternal and fetal morbidity/mortality. Immunological imbalances associated with endothelial cell dysfunction have been hypothesized as a cause for the onset and perpetuation of PE. Valid and reliable animal models are urgently required to test this hypothesis and to better understand the mechanisms underlying PE. We developed a novel PE‐model by adoptively transferring activated BALB/c Th1‐like splenocytes into allogeneically pregnant BALB/c female mice during late gestation; the model mimicked the symptoms of PE, i.e. increased blood pressure and glomerulonephritis accompanied by proteinuria. Interestingly, these PE‐like symptoms were not detectable in non‐pregnant recipients of activated Th1‐like cells. Adoptive cell transfer adversely affected the outcome of pregnancy by increasing fetal rejection, with uterine immune cells showing an inflammatory profile. In conclusion, we have established a valid and reliable PE mouse model, which opens vast opportunities for therapeutic interventions.

Questioning the Th1/Th2 Paradigm in Reproduction: Peripheral Levels of IL-12 are Down-Regulated in Miscarriage Patients

Zenclussen AC, Fest S, Busse P, Joachim R, Klapp BF, Arck PC. Questioning the Th1/Th2 paradigm in reproduction: peripheral levels of IL‐12 are down‐regulated in miscarriage patients. AJRI 2002; 48:245–251

Murine stress-triggered abortion is mediated by increase of CD8+ TNF-α+ decidual cells via substance P

PROBLEM: Stress is known to induce abortions in mice and humans. Increased levels of abortogenic type 1 helper T‐cell cytokines and decreased levels of pregnancy protective cytokines could be linked to stress‐triggered embryonic loss. Stress promotes neurotransmitter substance P (SP) release in tissues. SP increases the production of decidual tumor necrosis factor (TNF)‐α, whereby the phenotype of these TNF‐α‐producing cells is hypothetical. The objective of the present study was to identify decidual TNF‐α‐producing cell populations that are involved in stress‐induced murine abortion. 
 METHOD: DBA/2J‐mated CBA/J female mice were exposed to ultrasonic sound stress on day 5.5 of pregnancy. The mice were randomized and half were treated with the SP NK1‐receptor antagonist (SP‐RA) RP 67580 (200 μg/mouse). Frequency and cytokine profile of CD8+ cells were evaluated by immunohistochemistry and flow cytometry. Degranulation of uterine mast cells was examined histologically.
 RESULTS: On day 13.5 of pregnancy, the uteri were removed and the resorption rate was calculated. A mean resorption rate of 38.4% was detected in stressed mice (n=10) compared to 13.1% in non‐stressed control mice (n=11, P<0.01). Injection of SP‐RA decreased the abortion rate to 18.4% in stressed mice (n=19, P<0.01). Flow cytometry revealed a stress‐related increase of TNF‐α+/CD8+ decidual T cells, which could be abrogated by SP‐RA (P<0.05). No significant differences could be observed in numbers of mast cells and total CD8+ cells in situ.
 CONCLUSION: Our data suggest that stress‐triggered abortion is mediated by SP, and SP receptor blockade abrogates stress‐triggered abortion via reduced production of TNF‐α by CD8+ T cells.

Resiquimod, a new immune response modifier from the family of imidazoquinolinamines, inhibits allergen-induced Th2 responses, airway inflammation and airway hyper-reactivity in mice.

Background Allergen‐induced sensitization and airway disease are the results of adverse immune reactions against environmental antigens that may be prevented or inhibited by immune modifying strategies.

Nerve growth factor‐induced substance P in capsaicin‐insensitive vagal neurons innervating the lower mouse airway

Background Nerve growth factor (NGF) is elevated in allergic diseases such as bronchial asthma and can lead to an induction of substance P (SP) and related neuropeptides in guinea‐pigs large‐diameter, neurofilament‐positive airway neurons.