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Maternal immune activation (MIA) in midpregnancy is a risk factor for neurodevelopmental disorders. Improper brain development may cause malformations of the brain; maldevelopment induced by MIA may lead to a pathology-related phenotype. In this study, a single intraperitoneal injection of 20 mg/kg polyriboinosinic–polyribocytidylic acid [poly(I:C)] was administered to C57BL/6J mice on embryonic day (E) 12.5 to mimic maternal viral infection. Histopathological analysis of neurogenesis was performed using markers for Pax6, Tbr2, and Tbr1. In these fetuses, significant increases were observed in the proportion of Pax6-positive neural progenitor cells and Pax6/Tbr2 double-positive cells 24 h after poly(I:C) injection. There were no differences in the proportion of Tbr1-positive postmitotic neurons 48 h after poly(I:C) injection. At E18.5, there were more Pax6-positive and Tbr2-positive neural progenitor cells in the poly(I:C)-injected group than in the saline-injected group. Gene ontology enrichment analysis of poly(I:C)-induced differentially expressed genes in the fetal brain at E12.5 demonstrated that these genes were enriched in terms including response to cytokine, response to decreased oxygen levels in the category of biological process. At E13.5, activating transcription factor 4 (Atf4), which is an effector of integrated stress response, was significantly upregulated in the fetal brain. Our results show that poly(I:C)-induced MIA at E12.5 leads to dysregulated neurogenesis and upregulates Atf4 in the fetal brain. These findings provide a new insight in the mechanism of MIA causing improper brain development and subsequent neurodevelopmental disorders., Highlights • MIA increases Pax6-positive and Tbr2-positive neural progenitor cells. • MIA impaired the process of neurogenesis from as early as the acute stage. • MIA upregulated Atf4, an effector of integrated stress response, in the fetal brain.

Yo Shimizu,1 Tsuyoshi Tsukada,2 Hiromi Sakata-Haga,2 Daisuke Sakai,3 Hiroki Shoji,3 Yutaka Saikawa,1 Toshihisa Hatta2 1Department of Pediatrics, Kanazawa Medical University, Uchinada, Ishikawa, Japan; 2Department of Anatomy, Kanazawa Medical University, Uchinada, Ishikawa, Japan; 3Department of Biology, Kanazawa Medical University, Uchinada, Ishikawa, JapanCorrespondence: Toshihisa HattaDepartment of Anatomy, Kanazawa Medical University, Uchinada, Ishikawa, JapanTel +81-76-281-8113Fax +81-76-218-8189Email thatta@kanazawa-med.ac.jpBackground: A number of childhood diseases have been identified, such as severe infection or autoinflammatory disease, in which immune overreaction against inflammation is a possible underlying mechanism. Previous reports have demonstrated that fetal cells exposed to maternal immune activation (MIA) induced by polyriboinosinic-polyribocytidylic acid [poly(I:C)] exhibited hypersensitivity to inflammation in vitro. However, the details of this mechanism remain unclear. Therefore, this study aimed to reveal the reaction to inflammation in offspring exposed to MIA in the prenatal period, as well as its molecular mechanism, using a viral infection mouse model.Materials and Methods: Pregnant mice at 12.5, 14.5, and 16.5 days post coitum were injected intraperitoneally with poly(I:C) 20 mg/kg body weight (BW) or saline. Offspring aged 3– 4 weeks received the second injection of 20 mg/kg BW or 4 mg/kg BW poly(I:C) or saline. Serum and tissues were collected at 2, 24, 48, and 72 h after the postnatal injection. The cytokine profile, histopathology of organs, and unfolded protein response (UPR) in offspring were examined.Results: The serum levels of interleukin (IL)-6, IL-17, and interferon-γ were significantly higher in the MIA group, and acute liver necrosis was detected. Moreover, failure in UPR was observed in the MIA group compared with that in the control group.Conclusion: Overall, MIA exposure in utero caused failure in UPR as well as immune overreaction to the second attack of inflammation in offspring. Our results suggested that prenatal exposure to MIA might contribute to the congenital inflammatory constitution after birth.Keywords: maternal immune activation, liver necrosis, immune overreaction, unfolded protein response defects

MC5R is known for its role in the exocrine function of sebaceous glands, but other functions in the epidermis remain unclear. This study focused on the relationship between MC5R and homeostasis in the epidermis and examined the role of MC5R in mice whose skin was irradiated with UVB waves. UVB irradiation-induced skin ulcers and severe inflammation at lower doses in homozygotes of MC5R-deficient (i.e., MC5R−/−) mice (150 mJ/cm2) than the doses in wild-type mice (500 mJ/cm2). Transepidermal water loss was increased (approximately 10-fold) in adult MC5R−/− mice compared with that in wild-type mice. In neonates, a dye exclusion assay showed no remarkable difference between MC5R−/− and wild-type mice. After UVB irradiation, compared with wild-type mice, MC5R−/− mice showed increased inflammatory cell infiltration in the dermis of the ulcerative region, significantly increased thickness of the epidermis in the nonulcerative region, significantly more prickle cells in the nonulcerative region, and increased serum IL-6 levels but decreased IL-10 levels. Transmission electron microscopy revealed fewer lamellar granules, less lipid secretion, and an expansion of the trans-Golgi network in the epidermis in MC5R−/− mice. This study elucidated the increased sensitivity to UVB irradiation and decreased barrier function in MC5R−/−mice., Graphical abstract

We previously showed that maternal leukemia inhibitory factor (LIF) induces placental production of adrenocorticotropic hormone (ACTH), which stimulates fetal nucleated red blood cells to further secrete LIF and promote neurogenesis in rodent brains. However, the underlying mechanism of LIF-dependent ACTH induction remains unclear. Recently, we found that LIF induces corticotropin-releasing hormone (CRH) in mouse trophoblast stem cells. This finding supports the results of a previous study that CRH, which is produced by the placenta, induces placental ACTH production. In this study, we examined whether the effects of LIF are mediated by the induction of Pomc via CRH upregulation in mouse trophoblast. In vivo, protein levels of LIF and CRH peak in mouse placenta at 13.5 days post coitum. In mouse placenta, Crh mRNA and protein levels significantly increased 3 h after intraperitoneal injection of LIF (5 μg/kg body weight) into dams at 13.5 days post coitum. We also examined the effect of LIF-induced CRH on the expression of Pomc induced by LIF in mouse trophoblast stem cells in vitro. After LIF supplementation for 3 days, we found that the increased expression of Crh-induced by new supplementation of LIF was earlier than that of Pomc. Furthermore, LIF-induced upregulation of Pomc in mouse trophoblast stem cells was attenuated by inhibition of the CRH/CRHR1 pathway, whereas LIF-induced secretion of ACTH was attenuated by inhibition of the JAK/STAT3 pathway. Therefore, LIF indirectly increases placental Pomc expression through the CRH/CRHR1 pathway, and placental ACTH secretion is induced directly by LIF via the JAK/STAT3 pathway.

We developed a non-destructive and rapid whole-mount bone staining method for small fish, Xenopus laevis, and rodent fetuses (RAP-B). RAP-B does not require skin or soft tissue removal. However, RAP-B requires hair removal from hairy animals, such as adult mice and rats. In the present study, we investigated hair removal chemical treatments that did not result in soft tissue destruction. The hair removal effectiveness was investigated using a calcium mercaptoacetate or sodium mercaptoacetate solution on skin fragments obtained from the back of adult mice. A mixture of 2% sodium mercaptoacetate in 3% potassium hydroxide was found to be the most effective in complete hair removal from the skin. Using this hair removal treatment as a pretreatment for RAP-B, the preparation of fast-acting artifact-free whole-mount bone staining was possible without skin and soft tissue removal (RAP-B/HR). We performed a seamless observation from a low magnification wide-view to a high magnification without artifactacting artifacts using fluorescence zoom microscopy. Therefore, the combination of RAP-B/HR and fluorescent zoom microscopy is a novel platform for three-dimensional, wide-field, high-resolution pathological anatomical analysis.

Previous studies have shown that some inflammatory cytokines promote the expression of corticotropin-releasing hormone (CRH) in trophoblasts during pregnancy and that placental CRH could induce the production of adrenocorticotropic hormone (ACTH) in humans. However, whether the same is true in rodent placenta remains unclear. In this study, we examined the effect of pro-inflammatory cytokine LIF on the induction of CRH in mouse trophoblast stem cells (mTSCs). During differentiation, the CRH levels in mTSCs gradually increased. On days 3 and 5 after LIF supplementation, Crh expression in the differentiated mTSCs was significantly increased with LIF treatment than those without LIF treatment. Moreover, the CRH concentration in the culture media increased. Thereafter, we examined the contribution of the downstream pathways of LIF to CRH induction in differentiated mTSCs. The LIF-induced upregulation of CRH was attenuated by inhibition of PI3K/AKT and MAPK phosphorylation but not by inhibition of JAK/STAT3. Therefore, in mTSCs, LIF increased Crh expression through activation of the PI3K/AKT and MAPK pathways but not by the JAK/STAT3 pathway. The present study suggests that mTSC is an ideal in vitro model for studying regulation and function of placental CRH.

Why a catheter can be correctly placed in the ventricle by inserting perpendicular to the frontal bone on the ventricular drainage? We performed a study on the accuracy of a path perpendicular to the skull surface into the anterior horn using computed tomography (CT), and a clinical study. Twenty patients were studied on CT images. Using the curved multi-planar reconstruction method, the curved frontal skull and brain were reconstructed to flat structures, and perpendicular lines were drawn from the flat surface to the foramen of Monro on the reconstructed images. In clinical practice, we made a device which guided a catheter inserting perpendicular to the frontal skull surface, and used it in the ventricular drainage surgery for 148 hydrocephalic patients (158 surgeries). We discovered that the curved surface of the frontal bone around Kocher’s point represents the surface of a globe (mean radius, 75.9 ± 4.3 mm) centering on the foramen of Monro. The distribution of points ranged from 13.5–43.5 mm (mean, 43.5 ± 6.1 mm) to the midline, with points appearing more laterally as ventricular size increased. A catheter was placed in the ventricle in 148 surgeries (99.4%), and the catheter reached the ventricle with correct orientation toward the foramen of Monro in 128 (81.0%). The reason why the ventricular insertion perpendicular to the frontal bone surface can provide a consistent path toward the foramen of Monro is that the curved surface of the frontal bone around Kocher’s point represents the surface of a globe centered on the foramen of Monro.

Here we propose a new protocol for whole-mount bone staining, which allows the rapid preparation of highly cleared and nondestructive specimens. It only takes 3 days to complete whole procedure for small vertebrates, such as medaka, zebrafish, and Xenopus frogs. In this procedure, we used a newly developed fixative containing formalin, Triton X-100, and potassium hydroxide, which allows the fixation, decolorization, and transparentization of specimens at the same time. A bone staining solution containing alizarin red S with ethylene glycol and a clearing solution containing Tween 20 and potassium hydroxide also contributed the specificity and swiftness of this new system. As expected, although details of the skeletal system could be observed in specimens with high transparency, it was noteworthy that high-resolution fluorescence images acquired using zoom microscopes clearly delineated the shape of each bone. This new procedure would be expected to be widely used as a standard procedure for bone staining in the testing the developmental toxicity of chemicals and in the screening test of knockout or mutant animals.

The rapid rise in the prevalence of autism spectrum disorders (ASD) and other psychiatric disorders displaying similar traits has increased the need to elucidate their molecular mechanisms. Epidemiological studies have shown that maternal infection during mid-pregnancy is associated with increased risk of neurodevelopmental disorders such as ASD in offspring. Using maternal infection models, researchers have gathered evidence relevant to such disorders. A comprehensive summary of the changes in the brain structure, function, and behavior in offspring induced by maternal immune activation (MIA) has been reported. However, the molecular mechanisms underlying the association between MIA and improper brain development, which ultimately lead to neurodevelopmental disorders, have not been fully reviewed. This paper summarizes the currently known molecular mechanisms associated with the MIA model, with a special focus on the role of the placenta in fetal brain development.