Differential expression and regulation of Ido2 in the mouse uterus during peri-implantation period

The mechanism of action of oxytocin antagonist nolasiban in ART in healthy female volunteers

RESEARCH QUESTION

What are the effects of the oxytocin receptor (OTR) antagonist nolasiban on uterine contractions, endometrial perfusion and endometrial mRNA expression?

DESIGN

Randomized, double-blind, parallel-group, mechanism-of-action study with nolasiban. Forty-five healthy, pre-menopausal women were treated with placebo, 900 mg or 1800 mg nolasiban on the day corresponding to blastocyst transfer. Ultrasonographic uterine contraction frequency and endometrial perfusion were assessed, and endometrial biopsies analysed by next-generation sequencing.

RESULTS

Both doses of nolasiban showed decreased contraction frequency and increased endometrial perfusion depending on the time point assessed. At 1800 mg, 10 endometrial genes (DPP4, CNTNAP3, CNTN4, CXCL12, TNXB, CTSE, OLFM4, KRT5, KRT6A, IDO2) were significantly differentially expressed (adjusted P < 0.05). Of these, OLFM4, DPP4 and CXCL12 were regulated in the same direction as genes involved in implantation during the window of implantation. In addition, three genes (DPP4, CXCL12 and IDO2) were associated with decidualization and endometrial receptivity.

CONCLUSIONS

These data expand our knowledge of the mechanism of action of nolasiban in increasing pregnancy rates after embryo transfer. The results suggest more marked effects of nolasiban 1800 mg compared with the 900 mg dose, supporting testing at higher doses in IVF patients.

Sexual dimorphism and the role of estrogen in the immune microenvironment of liver metastases

Liver metastases (LM) remain a major cause of cancer-associated death and a clinical challenge. Here we explore a sexual dimorphism observed in the regulation of the tumor immune microenvironment (TIME) of LM, wherein the accumulation of myeloid-derived suppressor cells (MDSC) and regulatory T cells in colon and lung carcinoma LM is TNFR2-dependent in female, but not in male mice. In ovariectomized mice, a marked reduction is observed in colorectal, lung and pancreatic carcinoma LM that is reversible by estradiol reconstitution. This is associated with reduced liver MDSC accumulation, increased interferon-gamma (IFN-γ) and granzyme B production in CD8+ T cells and reduced TNFR2, IDO2, TDO and Serpin B9 expression levels. Treatment with tamoxifen increases liver cytotoxic T cell accumulation and reduces colon cancer LM. The results identify estrogen as a regulator of a pro-metastatic immune microenvironment in the liver and a potential target in the management of liver metastatic disease.

Body image dissatisfaction in pregnant and non-pregnant females is strongly predicted by immune activation and mucosa-derived activation of the tryptophan catabolite (TRYCAT) pathway

OBJECTIVES

The aim of the present study is to delineate the associations between body image dissatisfaction in pregnant women and immune-inflammatory biomarkers, i.e., C-reactive protein (CRP), zinc and IgA/IgM responses to tryptophan and tryptophan catabolites (TRYCATs).

METHODS

We assessed 49 pregnant and 24 non-pregnant females and assessed Body Image Satisfaction (BIS) scores at the end of term (T1), and 2-4 days (T2) and 4-6 weeks (T3) after delivery. Subjects were divided in those with a lowered BIS score (≤ 3) versus those with a higher score.

RESULTS

Logistic regression analysis showed that a lowered T1 BIS score was predicted by CRP levels and IgA responses to tryptophan (negative) and TRYCATs (positive), perinatal depression, body mass index (BMI) and age. The sum of quinolinic acid, kynurenine, 3-OH-kynurenine and 3-OH-anthranilic acid (reflecting brain quinolinic acid contents) was the single best predictor. In addition, a large part of the variance in the T1, T2 and T3 BIS scores was explained by IgA responses to tryptophan and TRYCATs, especially quinolinic acid.

CONCLUSIONS

Body image dissatisfaction is strongly associated with inflammation and mucosa-derived IDO activation independently from depression, pregnancy, BMI and age. IgA responses to peripheral TRYCATs, which determine brain quinolinic acid concentrations, also predict body image dissatisfaction.

Investigation of the Tissue Distribution and Physiological Roles of Indoleamine 2,3-Dioxygenase-2

Indoleamine 2,3-dioxygenase-2 (IDO2) is 1 of the 3 enzymes that can catalyze the first step in the kynurenine pathway of tryptophan metabolism. Of the 2 other enzymes, tryptophan 2,3-dioxygenase is highly expressed in the liver and has a role in tryptophan homeostasis, whereas indoleamine 2,3-dioxygenase-1 (IDO1) expression is induced by inflammatory stimuli. Indoleamine 2,3-dioxygenase-2 is reportedly expressed comparatively narrow, including in liver, kidney, brain, and in certain immune cell types, and it does not appear to contribute significantly to systemic tryptophan catabolism under normal physiological conditions. Here, we report the identification of an alternative splicing pattern, including the use of an alternative first exon, that is conserved in the mouse Ido1 and Ido2 genes. These findings prompted us to assess IDO2 protein expression and enzymatic activity in tissues. Our analysis, undertaken in Ido2^+/+ and Ido2^−/− mice using immunohistochemistry and measurement of tryptophan and kynurenine levels, suggested an even more restricted pattern of tissue expression than previously reported. We found IDO2 protein to be expressed in the liver with a perinuclear/nuclear, rather than cytoplasmic, distribution. Consistent with earlier reports, we found Ido2 ^−/− mice to be phenotypically similar to their Ido2^+/+ counterparts regarding levels of tryptophan and kynurenine in the plasma and liver. Our findings suggest a specialized function or regulatory role for IDO2 associated with its particular subcellular localization.

IgA/IgM responses to tryptophan and tryptophan catabolites (TRYCATs) are differently associated with prenatal depression, physio-somatic symptoms at the end of term and premenstrual syndrome

There is some evidence that lowered tryptophan and an activated tryptophan catabolite (TRYCAT) pathway play a role in depression, somatoform disorder, and postpartum blues. The aim of this study is to delineate the associations between the TRYCAT pathway and premenstrual syndrome (PMS) and perinatal depressive and physio-somatic symptoms. We examine the associations between end of term serum IgM and IgA responses to tryptophan and 9 TRYCATs in relation to zinc, C-reactive protein (CRP), and haptoglobin and prenatal physio-somatic (previously known as psychosomatic) symptoms (fatigue, back pain, muscle pain, dyspepsia, obstipation) and prenatal and postnatal depression and anxiety symptoms as measured using the Edinburgh Postnatal Depression Scale (EPDS), Hamilton Depression Rating Scale (HAMD), and Spielberger's State Anxiety Inventory (STAI). We included pregnant females with (n = 24) and without depression (n = 25) and 24 non-pregnant females. There were no significant associations between the IgA/IgM responses to tryptophan and TRYCATs and prenatal and postnatal depression/anxiety symptoms, except for lowered IgA responses to anthranilic acid in prenatal depression. A large part of the variance in IgA responses to most TRYCATs was explained by PMS and haptoglobin (positively) and CRP (inversely) levels. The IgA responses to TRYCATs were significantly increased in PMS, in particular picolinic, anthranilic, xanthurenic and kynurenic acid, and 3OH-kynurenine. Variance (62.5%) in physio-somatic symptoms at the end of term was explained by PMS, previous depressions, zinc (inversely), CRP and haptoglobin (both positively), and the IgM responses to quinolinic acid (positively), anthranilic acid, and tryptophan (both negatively). The results suggest that mucosa-derived TRYCAT pathway activation is significantly associated with PMS, but not with perinatal depression/anxiety symptoms. Physio-somatic symptoms in pregnancy have an immune-inflammatory pathophysiology. Induction of the TRYCAT pathway appears to be more related to physio-somatic than to depression symptoms.