Kento Miura

Placental enlargement in somatic cell nuclear transfer–derived mice is attributed to biallelic expression of noncanonical (H3K27me3-dependent) imprinted genes owing to loss of imprinting (LOI). Here, we investigated whether a similar mechanism underlies placental enlargement in intersubspecific hybrids between BDF1 (Mus musculus domesticus) and HMI (M. m. castaneus) mice. Quantitative and allelic expression analyses revealed gene-specific LOI in (BDF1 × HMI)F1 placentas: Jade1 (Phf17) and Slc38a4 showed LOI in all placentas regardless of expression levels, whereas Gab1 and Sfmbt2 exhibited LOI only when expression levels were elevated. Notably, Jade1 and Slc38a4 also showed biallelic expression at lower levels in normal-sized (BDF1 × JF1 [M. m. molossinus])F1 placentas. Maternal knockout of Jade1, Slc38a4, Sfmbt2, or the Sfmbt2 miRNA cluster restored monoallelic expression and significantly reduced the weight of (BDF1 × HMI)F1 placentas, indicating that these genes were collectively responsible for placental enlargement in intersubspecific hybrid placentas. Transcriptomic analysis revealed that LOI of noncanonical imprinted genes occurred after implantation. These findings suggest that placental enlargement in (BDF1 × HMI)F1 hybrids is driven by overexpression of multiple noncanonical imprinted genes, resulting from LOI after implantation and additional hybrid-specific, yet unidentified, upregulation mechanisms.

In vitro fertilization (IVF) and intracytoplasmic sperm injection (ICSI) are 2 major assisted reproductive techniques (ARTs) used widely to treat infertility. Recently, spermatogonial transplantation emerged as a new ART to restore fertility to young patients with cancer after cancer therapy. To examine the influence of germ cell manipulation on behavior of offspring, we produced F₁ offspring by a combination of two ARTs, spermatogonial transplantation and ICSI. When these animals were compared with F₁ offspring produced by ICSI using fresh wild-type sperm, not only spermatogonial transplantation–ICSI mice but also ICSI-only control mice exhibited behavioral abnormalities, which persisted in the F₂ generation. Furthermore, although these F₁ offspring appeared normal, F₂ offspring produced by IVF using F₁ sperm and wild-type oocytes showed various types of congenital abnormalities, including anophthalmia, hydrocephalus, and missing limbs. Therefore, ARTs can induce morphological and functional defects in mice, some of which become evident only after germline transmission.

Th17 cells are implicated in allergic inflammatory diseases, including allergic rhinitis (AR), though the effect of steroids on Th17 cell-dependent nasal responses is unclear. Herein, we investigated a nasal inflammation model elicited by allergen provocation in mice infused with Th17 cells and its responsiveness against steroid treatment. We transferred BALB/c mice with Th17 cells, which were differentiated in vitro and showed a specific reaction to ovalbumin (OVA). We challenged the transferred mice by intranasal injection of OVA and to some of them, administered dexamethasone (Dex) subcutaneously in advance. Then, we assessed immediate nasal response (INR), nasal hyperresponsiveness (NHR), and inflammatory cell infiltration into the nasal mucosa. The significant nasal inflammatory responses with massive neutrophil accumulation, INR, and NHR were induced upon allergen challenge. Allergen-induced INR and NHR were significantly suppressed by Dex treatment. This study suggested the effectiveness of steroids on Th17 cell-mediated nasal responses in AR.

A contribution of the cholinergic system to immune cell function has been suggested, though the role of nicotine and its receptors in T cells, especially regulatory T (Treg) cells, is unclear. We herein investigated the expression and function of nicotinic acetylcholine receptors (nAChRs) in murine-induced Treg (iTreg) cells. Upon differentiation of naive BALB/c T cells into iTreg cells and other T-cell subsets, the effect of nicotine on cytokine production and proliferation of iTreg cells was examined. The expression of nAChRs and its regulatory mechanisms were comparatively analyzed among T-cell subsets. Stimulation-induced transforming growth factor-β1 (TGF-β1) production of iTreg cells was suppressed by nicotine, whereas interleukin (IL)-10 production and proliferation was not affected. α2-, α5-, α9-, and β2-nAChRs were differentially expressed in naive, Th1, Th2, Th9, Th17, and iTreg cells. Among these cell types, the α9-nAChR was particularly upregulated in iTreg cells via its gene promoter, but not through tri-methylation at the 4th lysine residue of the histone H3-dependent mechanisms. We conclude that the immunoregulatory role of Treg cells is modified by the cholinergic system, probably through the characteristic expression of nAChRs.

Background: The activation of Th2 cells that play a pivotal role in the development of allergic eosinophilic inflammation is regulated by an L-type amino acid transporter (LAT) 1. However, the contribution of LAT1 to the pathogenesis of Th2 cell-mediated airway inflammation has not been investigated. Objective: In this study, we investigated the effect of a LAT1 inhibitor, JPH203, on Th2 cell-mediated airway eosinophilic inflammation. Methods: BALB/c mice were transferred with ovalbumin (OVA)-specific Th2 cell and challenged by corresponding allergen with or without administration of JPH203. Then, the infiltration of inflammatory cells including eosinophils and allergen-specific Th2 cells in the lungs and bronchial hyperresponsiveness (BHR) was assessed. Results: Inflammatory responses in the lungs with massive accumulation of eosinophils and BHR were induced in Th2 cell-transferred mice upon challenge with OVA. The treatment with JPH203 significantly suppressed the allergen-induced BHR but not eosinophil infiltration. The infused Th2 cells were also accumulated in the lungs upon allergen challenge, though the response was not affected by JPH203 treatment. Conclusion: JPH203 suppressed Th2 cell-mediated BHR through the mechanisms independently of the lung accumulation of eosinophils and Th2 cells.

Koyama T, et al. Asia Pac Allergy. 2021 Jul;11(3):e25. https://doi.org/10.5415/apallergy.2021.11.e25

The essential contribution of CD4⁺ T cells in allergic airway diseases has been demonstrated, especially by using various murine models of antigen-induced airway inflammation. In addition to antigen-immunized mouse models employing mast cell-deficient mice and CD4⁺ T cell-depleting procedure, antigen-specific CD4⁺ T cell transfer models have revealed the possible development of allergic inflammation solely dependent on CD4⁺ T cells. Regardless of the classical Th1/Th2 theory, various helper T cell subsets have the potential to induce different types of allergic inflammation. T cell receptor (TCR)-transgenic (Tg) mice have been used for investigating T cell-mediated immune responses. Besides, we have recently generated cloned mice from antigen-specific CD4⁺ T cells through somatic cell nuclear transfer. In contrast to TCR-Tg mice that express artificially introduced TCR, the cloned mice express endogenously regulated antigen-specific TCR. Upon antigen exposure, the mite antigen-reactive T cell-cloned mice displayed strong airway inflammation accompanied by bronchial hyperresponsiveness in a short time period. Antigen-specific CD4⁺ T cell-cloned mice are expected to be useful for investigating the detailed role of CD4⁺ T cells in various allergic diseases and for evaluating novel anti-allergic drugs.

In most of mammalian embryos, gonadal sex differentiation occurs inside the maternal uterus before birth. In several fetal ovarian grafting experiments using male host mice, an experimental switch from the maternal intrauterine to male-host environment gradually induces partial masculinization of the grafted ovaries even under the wild-type genotype. However, either host-derived factors causing or molecular basis underlying this masculinization of the fetal ovaries are not clear. Here, we demonstrate that ectopic appearance of SOX9-positive Sertoli cell-like cells in grafted ovaries was mediated by the testosterone derived from the male host. Neither Sox8 nor Amh activity in the ovarian tissues is essential for such ectopic appearance of SOX9-positive cells. The transcriptome analyses of the grafted ovaries during this masculinization process showed early downregulation of pro-ovarian genes such as Irx3, Nr0b1/Dax1, Emx2, and Fez1/Lzts1 by days 7–10 post-transplantation, and subsequent upregulation of several pro-testis genes, such as Bhlhe40, Egr1/2, Nr4a2, and Zc3h12c by day 20, leading to a partial sex reversal with altered expression profiles in one-third of the total numbers of the sex-dimorphic pre-granulosa and Sertoli cell-specific genes at 12.5 dpc. Our data imply that the paternal testosterone exposure is partially responsible for the sex-reversal expression profiles of certain pro-ovarian and pro-testis genes in the fetal ovaries in a temporally dependent manner.