Expression of Toll-Like Receptors in the Lung Tissue of Mouse Fetuses Generated by in vitro Embryo Culture and Embryo Transfer

Göksel Doğan; Nedim Karagenç; Kerem Esmen; Bengi Çınar Kul; Hasan Yeşilkaya; Şakir Akgün; Mehmet Nurullah Orman; Mustafa Sandıkçı; Ülker Eren; Hümeyra Ünsal; Levent Karagenç

doi:10.1159/000529974

Expression of Toll-Like Receptors in the Lung Tissue of Mouse Fetuses Generated by in vitro Embryo Culture and Embryo Transfer

Cells Tissues Organs. 2023 Apr 27:1-22. doi: 10.1159/000529974. Online ahead of print.

Authors

Affiliations

¹ Department of Histology-Embryology, Faculty of Veterinary Medicine, Adnan Menderes University, Aydın, Turkey.
² Department of Medical Genetics, Faculty of Medicine, Pamukkale University, Denizli, Turkey.
³ Department of Medical, Faculty of Medicine, Dokuz Eylül University, İzmir, Turkey.
⁴ Department of Genetics, Faculty of Veterinary Medicine, Ankara University, Ankara, Turkey.
⁵ Department of Respiratory Sciences, University of Leicester, Leicester, UK.
⁶ Department of Medical Biology, Faculty of Medicine, Kafkas University, Kars, Turkey.
⁷ Department of Biostatistics and Medical Informatics, Faculty of Medicine, Ege University, İzmir, Turkey.
⁸ Department of Physiology, Faculty of Veterinary Medicine, Adnan Menderes University, Aydın, Turkey.

PMID: 37105136
DOI: 10.1159/000529974

Abstract

Mouse fetuses generated by in vitro embryo culture and embryo transfer exhibit impaired lung development, altered composition of pulmonary epithelial cells associated with downregulation of several genes involved in lung development and toll-like receptor (TLR) signaling pathway. The aims of the present study were to determine the expression of all TLRs and to examine if the expression of TLRs, along with genes involved in TLR signaling pathway, is altered in the lung tissue of mouse fetuses generated through embryo culture and embryo transfer. Two experimental (EGs) and one control (CG) group were included in the study. Embryos cultured at 5% CO2-95% air for 95 h or less than 24 h were transferred to pseudo-pregnant females to obtain fetuses comprising EGin vitro (n = 18) and EGin vivo (n = 18), respectively. Fetuses obtained from naturally ovulating females on day 18 of pregnancy served as the CG (n = 18). Western blot and immunohistochemistry were used to determine the expression of TLR proteins. The expression of transcripts encoding TLRs, and the genes involved in TLR signaling pathway (Lbp, Pik3r1, Pik3cb, Nfkbia, and Fos), was determined using qRT-PCR. While all TLRs were expressed by cells lining the bronchial/bronchiolar epithelium of lung tissues in all groups, some of the TLRs were expressed in a specific pattern. When compared to CG, the expression of transcripts encoding TLR-2, -3, -4, -5, -7, -8, -9, -12, -13, Lbp, Pik3r1, Pik3cb, Nfkbia, and Fos was significantly downregulated in both EGs. It appears that stress imposed on embryos at preimplantation stages of development is associated with downregulation of TLRs, along with some of the genes involved in TLR signaling pathway, in the lung tissue during the perinatal period. It remains to be determined if downregulation of TLRs, along with the genes involved in TLR signaling pathway, has any functional consequences in the adult lung tissue.

Keywords: Assisted reproduction; In vitro embryo culture; Lung development; Toll-like receptor signaling pathway; Toll-like receptors.