Lumen Of Mice Research Articles

LEFTY2 inhibits endometrial receptivity by downregulating Orai1 expression and store-operated Ca2+ entry

Early embryo development and endometrial differentiation are initially independent processes, and synchronization, imposed by a limited window of implantation, is critical for reproductive success. A putative negative regulator of endometrial receptivity is LEFTY2, a member of the transforming growth factor (TGF)-β family. LEFTY2 is highly expressed in decidualizing human endometrial stromal cells (HESCs) during the late luteal phase of the menstrual cycle, coinciding with the closure of the window of implantation. Here, we show that flushing of the uterine lumen in mice with recombinant LEFTY2 inhibits the expression of key receptivity genes, including Cox2, Bmp2, and Wnt4, and blocks embryo implantation. In Ishikawa cells, a human endometrial epithelial cell line, LEFTY2 downregulated the expression of calcium release-activated calcium channel protein 1, encoded by ORAI1, and inhibited store-operated Ca2+ entry (SOCE). Furthermore, LEFTY2 and the Orai1 blockers 2-APB, MRS-1845, as well as YM-58483, inhibited, whereas the Ca2+ ionophore, ionomycin, strongly upregulated COX2, BMP2 and WNT4 expression in decidualizing HESCs. These findings suggest that LEFTY2 closes the implantation window, at least in part, by downregulating Orai1, which in turn limits SOCE and antagonizes expression of Ca2+-sensitive receptivity genes.Key messages•Endometrial receptivity is negatively regulated by LEFTY2.•LEFTY2 inhibits the expression of key murine receptivity genes, including Cox2, Bmp2and Wnt4, and blocks embryo implantation.•LEFTY2 downregulates the expression of Orai1 and inhibits SOCE.•LEFTY2 and the Orai1 blockers 2-APB, MRS-1845, and YM-58483 inhibit COX2, BMP2, and WNT4 expression in endometrial cells.•Targeting LEFTY2 and Orai1 may represent a novel approach for treating unexplained infertility.

Exposure to cigarette smoke during pregnancy causes redox imbalance and histological damage in lung tissue of neonatal mice

Smoking during pregnancy is directly associated with numerous serious conditions, such as premature birth, low birth weight, and perinatal mortality. We quantitatively evaluated histological inflammatory alterations, oxidative damage by lipid peroxidation, the activity of the antioxidant enzymes superoxide dismutase (SOD) and catalase (CAT) in the lungs of mice exposed to cigarette smoke during pregnancy. Eight female and four male mice were mated for five days. Pregnant female mice were randomly allocated to the control group or to the cigarette smoke group (n = 8) in which they were exposed to 12 cigarettes per day in an exposure chamber, three times a day for 21 days. The control group (CG; n = 8) was kept in the exposure chamber for the same duration, but without exposure to cigarette smoke. Six newborn mice from both groups were weighed 24 hours after birth and then euthanized. Lung tissue was collected and subjected to histomorphometric and biochemical analyses. The cigarette smoke group showed a significant reduction in snout-vent length compared to the control group. Histomorphometric analysis indicated increased alveolar septal thickness and a larger alveolar lumen in mice exposed to cigarette smoke than in mice in the control group. We observed increased alveolar inflammatory infiltrate, decreased SOD activity, and significantly higher oxidative damage in the cigarette smoke group. Our data indicate that cigarette smoke exposure during pregnancy decreases body length at birth, changes lung tissue, and causes redox imbalance and histological damage in newborn mice.

Loss of Claudins 2 and 15 From Mice Causes Defects in Paracellular Na+ Flow and Nutrient Transport in Gut and Leads to Death from Malnutrition

The intestinal symport system moves nutrients across membranes via transporters, and is required for absorption of major nutrients such as glucose, amino acids, and bile acids (which are required for fat absorption). Most of these transporters are regulated by Na(+), but the standard diet does not provide sufficient levels of this ion to the intestinal lumen to support this system. Claudins form paracellular barriers between epithelial cells, and claudin-2 and -15 regulate paracellular ion flow in the intestine. We investigated how cell adherence, tight junction barriers, and claudins regulate the supply of Na(+) to the intestinal lumen in mice. We created Cldn2(-/-)Cldn15(-/-) (double-knockout) mice and analyzed intestinal tissues by reverse-transcription polymerase chain reaction, immunoblot, immunofluorescence, electron microscopy, and H&E analyses. We also measured paracellular Na(+) flow, luminal Na(+) concentration, and absorption of glucose, amino acids, and fats, which were administered orally to the mice. Paracellular flow of Na(+) from the intestinal submucosa to the lumen, and therefore the concentration of Na(+) in the lumen, was greatly reduced in intestines of Cldn2(-/-)Cldn15(-/-) mice. Absorption of glucose, amino acids, and fats also decreased in the mice, which died by postnatal day 25 from malnutrition. The paracellular flow of Na(+) from the intestinal submucosa is regulated by tight junctions that contain claudin-2 and -15. This system is required for the absorption of glucose, amino acids, and fats; disruption of this system in mice leads to infant death as a result of malabsorption.

The antibody response in serum, intestinal wall and intestinal lumen of NMRI mice infected with Echinostoma caproni

Groups of mice (NMRI) were infected with 0, 6 and 25 metacercariae of the intestinal trematode Echinostoma caproni. An enzyme linked immunosorbent assay (ELISA) was developed for measuring the specific IgM, IgG and IgA antibody responses in serum, small intestinal tissue and small intestinal lumen of the mice, by using a crude adult E. caproni antigen. In infected mice, significant levels of IgM were measured in the sera from day 14 after infection and of IgG and IgA from day 28 after infection. Early in the infection, the mean level of serum IgM was higher in 6-worm infections than in 25-worm infections. Late in the infection, higher mean levels of IgA were reached in the serum of mice with high than in those with low dose infections. The onset of appearance of antibodies in the tissue of the small intestine reflected the picture seen in the serum. For IgM, and to a lesser degree for IgG, the highest mean antibody levels appeared in the posterior sections of the small intestinal wall, where also the parasites were located. The mean level of IgA, however, was uniform throughout the length of the small intestinal tissue. High levels of specific IgA were detected in the lumen of the small intestine on day 28 after infection, especially in the anterior sections, where only few parasites were located. No specific IgM or IgG could be detected in the intestinal lumen on this day. The results are related to the intestinal location and the pattern of expulsion of E. caproni in the mouse host.