Effects of autoimmune abnormalities on fertility and placental morphology in mice

Autoimmune diseases (AIDs) alter the placental immune environment leading to fetal loss. This study investigated the effects of AIDs on pregnancy and the placenta in AID-prone MRL/MpJ-Faslpr/lpr mice and wild-type MRL/MpJ, which were mated with male MRL/MpJ and MRL/MpJ-Faslpr/lpr at five months and defined as moLpr and moMpJ, respectively. AID indices (spleen weight and serum autoantibody levels) and fertility status (number and size of fetuses, morphology, and comprehensive gene expression of placentas) were evaluated on gestational day 15.5. Both strains showed equivalent fertility, but moLpr showed lighter placentas and fetuses than moMpJ, and decreased fertility with AID severity. moLpr placentas had a higher number of T cells, higher expression of genes associated with T helper 2 and T follicular helper functions, and altered expression of genes (Krt15, Slc7a3, Sprr2a3) that significantly regulate pregnancy or immunity. The gene expression of T cell migration-associated chemokines (Ccl5, Cxcl9) was significantly increased in moLpr placentas, and CCL5 and CXCL9 were detected in moLpr placentas, particularly in T cells and placenta-component cells, respectively. Thus, AID altered placental morphofunction and fertility in mice; however, fertility was maintained at the examined time points. This study enhances our understanding of placental alterations and gestational risk due to AIDs.

Aberrant CD8+T cells drive reproductive dysfunction in female mice with elevated IFN-γ levels

Introduction

Interferon-gamma (IFN-γ) is pivotal in orchestrating immune responses during healthy pregnancy. However, its dysregulation, often due to autoimmunity, infections, or chronic inflammatory conditions, is implicated in adverse reproductive outcomes such as pregnancy failure or infertility. Additionally, the underlying immunological mechanisms remain elusive.

Methods

Here, we explore the impact of systemic IFN-γ elevation on cytotoxic T cell responses in female reproduction utilizing a systemic lupus-prone mouse model with impaired IFN-γ degradation.

Results

Our findings reveal that heightened IFN-γ levels triggered the infiltration of CD8+T cells in the pituitary gland and female reproductive tract (FRT), resulting in prolactin deficiency and subsequent infertility. Furthermore, we demonstrate that chronic IFN-γ elevation increases effector memory CD8+T cells in the murine ovary and uterus.

Discussion

These insights broaden our understanding of the role of elevated IFN-γ in female reproductive dysfunction and suggest CD8+T cells as potential immunotherapeutic targets in female reproductive disorders associated with chronic systemic IFN-γ elevation.

Oocyte cumulus complex quality and oviduct transportation velocity in systemic autoimmune disease model mice

Oocyte transportation by the oviduct involves the interaction between ciliated epithelial cells and cumulus cells. To determine whether the quality of cumulus-oocyte complexes (COCs) changes the transportation property of COCs, we compared the transportation velocity of COCs (TVC) by the infundibulum ex vivo with various combinations of infundibula and COCs collected from different mice. We used young and aged C57BL/6N and MRL/MpJ, and MRL/MpJ-Faslpr/lpr mice as the strains with intact female reproductive function and the systemic autoimmune disease model exhibiting oocyte pick-up dysfunction owing to the morphofunctional abnormality of ciliated epithelium, respectively. The TVC of aged MRL strains was less than that of aged C57BL/6N mice, suggesting that aging affects the transportation of COCs in MRL strains. The TVC of aged MRL/MpJ-Faslpr/lpr mice was the least among all examined combinations, whereas the TVC accelerated when the infundibulum or COCs were collected from other strains. These results indicate that the transportation property of COCs is determined not only by the ciliary function in the infundibulum but also by the properties of COCs.

Oviduct Histopathology of Internal Laying and Egg-Bound Syndrome in Laying Hens

In the egg industry, common reproductive disorders, such as internal laying and egg-bound syndrome, not only reduce egg productivity but also cause deaths in severe cases. In this study, we focused on the oviduct histology of the pathogenesis of internal laying and egg-bound syndrome. We divided the aged laying hens into four groups according to the observation of the abdominal cavity and oviductal lumen: healthy, internal laying, egg-bound, and intercurrent. The percentages of healthy, internal laying, egg-bound, and intercurrent groups were 55%, 17.5%, 15%, and 12.5%, respectively. In all parts of the oviduct (i.e., infundibulum, magnum, isthmus, and uterus), the oviductal epithelium was composed of ciliated epithelial cells and secretory cells. The epithelial region lacking cilia was larger in the entire oviduct of the internal laying, and intercurrent groups than in the healthy group. In the internal laying, egg-bound, and intercurrent groups, significant T-cell infiltration was observed in the lamina propria of the entire oviduct. The morphological alteration of ciliated epithelial cells in the oviducts caused by inflammation may be the underlying cause of the pathogenesis of internal laying and egg-bound syndrome.

Expression of Indian hedgehog signaling in murine oviductal infundibulum and its relationship with epithelial homeostasis

Homeostasis of the oviductal infundibulum epithelium is continuously regulated by signaling pathways under physiological and pathological conditions. Herein, we investigated the expression of hedgehog (Hh) signaling-related components in the murine oviductal infundibulum, which is known to maintain homeostasis in the adult epithelium. Additionally, using autoimmune disease-prone MRL/MpJ-Fas^lpr/lpr (MRL/lpr) mice showing abnormal morphofunction of the ciliated epithelium of the infundibulum related to the oviductal inflammation, we examined the relationship between Hh signaling and pathology of the infundibulum. The expression and localization of Pax8, a marker for progenitor cells in the oviductal epithelium, and Foxj1, a marker for ciliogenesis, were examined in the infundibulum. The results showed that Pax8 was downregulated and Foxj1 was upregulated with aging, suggesting that homeostasis of the infundibulum epithelium of MRL/lpr mice was disturbed at 6 months of age. In all mice, the motile cilia of ciliated epithelial cells in the infundibulum harbored Hh signaling pathway-related molecules: patched (Ptch), smoothened (Smo), and epithelial cells harbor Gli. In contrast, Ptch, Smo, and Gli2 were significantly downregulated in the infundibulum of MRL/lpr mice at 6 months of age. The expression levels of Pax8 and Foxj1 were significantly positively correlated with those of Ptch1, Smo, and Gli2. Hh signaling is thought to be involved in homeostasis of the ciliated epithelium in the infundibulum. In MRL/lpr mice, which show exacerbated severe systemic autoimmune abnormalities, molecular alterations in Hh signaling-related components are considered to interact with local inflammation in the infundibulum, leading to disturbances in epithelial homeostasis and reproductive function.

The histopathological features of the surgical endometriosis model using systemic autoimmune disease-prone mice

Endometriosis is a common gynecological disease that affects women of reproductive age in which the uterine endometrium grows outside the uterus. Origin of the ectopic endometrium is thought to be the retrograde endometrium through the oviducts. However, factors that determine the adherence and proliferation of the ectopic endometrium have not been revealed. Importantly, systemic autoimmune diseases are considered a key factor in the endometriosis onset. Herein, we established a surgical endometriosis rodent model using autoimmune disease-prone MRL/MpJ-Faslpr/lpr (MRL/lpr) and MRL/+ mice to provide basic evidence of the relationship between autoimmune disease and endometriosis. Endometriosis lesions were successfully induced in two regions after transplanting uterine tissues from donor mice into the peritoneal cavity of recipient mice: the peritoneum or adipose tissue around the transplantation point (proximal lesions) and the gastrosplenic ligament or intestinal mesentery far from the transplantation site (distal lesions). Distal lesions were observed only in MRL/lpr mice, whereas endometriosis lesions showed no genotype- or region-related differences in the histology and distribution of sex hormone receptors and T cells. In contrast, transplanted uterine tissues in donor MRL/lpr mice exhibited a large infiltration of T cells in the lamina propria. Splenomegaly was more common in recipient than that in donor MRL/lpr mice. These results suggest that the infiltration of endogenous T cells in the endometrium alters the growth features of ectopic endometrium, possibly affecting the severity of endometriosis in patients with systemic autoimmune diseases.

Modified foreign body reaction to silicone imbedded in subcutaneous tissues by different mouse systemic immune conditions

Foreign body reaction (FBR) causes unexpected adverse effects due to implanted materials in humans and animals. Inflammation and subsequent fibrosis during FBR seems to be affected by recipient immunity, such as the balance of T helper (Th) response that has the potential to regulate FBR-related macrophage function. Here, the immunological effects of FBR on subcutaneously imbedded silicone tubes (ST) at 8 weeks were investigated histologically by comparing Th1-biased C57BL/6N, Th2-biased MRL/MpJ, and autoimmune disease-prone MRL/MpJ-Fas^lpr/lpr . Tissue surrounding ST (TSS) was analyzed at day (D) 7 and 14 (reaction phase) or D35 (stability phase) after surgery. In all strains, the TSS was composed of a thin layer (TL) containing fibrous tissues and loose connective tissues formed outside the TL. Few lymphocytes and mast cells, several neutrophils, and numerous macrophages infiltrated the TSS. Active vascularization was observed at D14 in all strains. For the examined indices, M1-type macrophage density in the TSS of C57BL/6N mice was significantly higher at D14 compared to other strains. No significant strain difference relating to M2-type macrophages was detected, suggesting the effects of Th1-biased immunity on FBR-related inflammation. Collagen fibers in the TSS increased in density and became stable with age in all strains. In particular, MRL/MpJ-Fas^lpr/lpr showed progressive fibrotic features. Serum autoantibody levels in MRL/MpJ-Fas^lpr/lpr mice were inversely correlated with M1-type macrophage density. These data from MRL/MpJ-Fas^lpr/lpr mice suggested modifications of FBR-related inflammation and fibrosis by autoimmune abnormalities. The results provide crucial insights into the pathological modification of FBR by recipient immunity and emphasize its clinicopathological importance in humans and animals.

Anatomy and histology of the foramen of ovarian bursa opening to the peritoneal cavity and its changes in autoimmune disease-prone mice

The ovarian bursa is a small peritoneal cavity enclosed by the mesovarium and mesosalpinx, which surrounds the ovaries and oviductal infundibulum in mammals. The ovarian bursa is considered as the structure facilitating the transport of ovulated oocytes into the oviduct. Our previous study revealed reduced oocyte pick-up function in the oviduct of lupus-prone MRL/MpJ-Faslpr/lpr mouse, suggesting the possibility of an escape of ovulated oocytes into the peritoneal cavity, despite the presence of an almost complete ovarian bursa in the mouse. In this study, we revealed anatomical and histological characteristics of the ovarian bursa in C57BL/6 N, MRL/MpJ, and MRL/MpJ-Faslpr/lpr mice. All strains had the foramen of ovarian bursa (FOB), with a size of approximately 0.04 to 0.12 cm2 , surrounded by the ligament of ovarian bursa (LOB), which is part of the mesosalpinx. The LOB was partially lined with the cuboidal mesothelial cells and consisted of a thick smooth muscle layer in all strains. In 6-month-old MRL/MpJ-Faslpr/lpr mice, in which the systemic autoimmune abnormality deteriorated and oocyte pick-up function was impaired, the size of the FOB tended to be larger than that of other strains. Additionally, in MRL/MpJ-Faslpr/lpr mice at 6 months of age, there was infiltration by numerous immune cells in the mesosalpinx suspending the isthmus; however, the LOB prevented severe inflammation and showed deposition of collagen fibers. These results not only indicate that the FOB is a common structure within mice, but also imply the physiological function of the LOB and its role in maintaining the microenvironment around the ovary, as well as regulating healthy reproduction.

MRL/MpJ mice produce more oocytes and exhibit impaired fertilisation and accelerated luteinisation after superovulation treatment

MRL/MpJ mice exhibit distinct phenotypes in several biological processes, including wound healing. Herein we report two unique phenotypes in the female reproductive system of MRL/MpJ mice that affect ovulation and luteinisation. We found that superovulation treatment resulted in the production of significantly more oocytes in MRL/MpJ than C57BL/6 mice (71.0±13.4 vs 26.8±2.8 respectively). However, no exon mutations were detected in genes coding for female reproductive hormones or their receptors in MRL/MpJ mice. In addition, the fertilisation rate was lower for ovulated oocytes from MRL/MpJ than C57BL/6 mice, with most of the fertilised oocytes showing abnormal morphology, characterised by deformation and cytolysis. Histological tracing of luteinisation showed that MRL/MpJ mice formed corpora lutea within 36h after ovulation, whereas C57BL/6 mice were still at the corpora haemorrhagica formation stage after 36h. The balance between the expression of matrix metalloproteinases and their tissue inhibitors shifted towards the former earlier after ovulation in MRL/MpJ than C57BL/6 mice. This result indicates a possible link between accelerated extracellular matrix remodelling in the ovulated or ruptured follicles and luteinisation in MRL/MpJ mice. Together, these findings reveal novel phenotypes in MRL/MpJ mice that provide novel insights into reproductive biology.

Ovarian mast cells migrate toward ovary-fimbria connection in neonatal MRL/MpJ mice

MRL/MpJ mice have abundant ovarian mast cells (MCs) as compared with other strains at postnatal day 0 (P0); however, they sharply decrease after birth. These ovarian MCs, particularly beneath the ovarian surface epithelium (SE), which express mucosal MC (MMC) marker, might participate in early follicular development. This study investigated the changes in spatiotemporal distribution of MCs in the perinatal MRL/MpJ mouse ovaries. At P0 to P7, the MCs were densely localized to the ovary, especially their caudomedial region around the ovary-fimbria connection. The neonatal ovarian MCs showed intermediate characteristics of MMC and connective tissue MC (CTMC), and the latter phenotype became evident with aging. However, the expression ratio of the MMC to CTMC marker increased from P0 to P4 in the MRL/MpJ mouse ovary. Similarly, the ratio of MCs facing SE to total MC number increased with aging, although the number of ovarian MCs decreased, indicating the relative increase in MMC phenotypes in the early neonatal ovary. Neither proliferating nor apoptotic MCs were found in the MRL/MpJ mouse ovaries. The parenchymal cells surrounding MCs at ovary-fimbria connection showed similar molecular expression patterns (E-cadherin⁺/Foxl2^-/Gata4⁺) as that of the ovarian surface epithelial cells. At P2, around the ovary-fimbria connection, c-kit^- immature oocytes formed clusters called nests, and some MCs localized adjacent to c-kit^- oocytes within the nests. These results indicated that in postnatal MRL/MpJ mice, ovarian MCs changed their distribution by migrating toward the parenchymal cells composing ovary-fimbria connection, which possessed similar characteristics to the ovarian surface epithelium. Thus, we elucidated the spatiotemporal alterations of the ovarian MCs in MRL/MpJ mice, and suggested their importance during the early follicular development by migrating toward the ovary-fimbria connection. MRL/MpJ mice would be useful to elucidate the relationship between neonatal immunity and reproductive systems.