Differential expression of HIF-1α and its hypoxia-related inducers in the spleens of plateau yaks and plain yellow cattle.

The present study aims to investigate the distribution and expression characteristics of HIF-1α, VEGF, VEGFR-2, VCAM-1, and IL-4 in the spleen of plateau yaks and plain yellow cattle and to speculate the possible regulatory role of HIF-1α and its related hypoxia-inducible factors in the adaptation of the yak spleen to the plateau hypoxic environment. Histological features were observed using H&E and PAS stains. Immunohistochemical staining and optical density analysis were applied to investigate the distribution and differences in the expression of HIF-1α, VEGF, VEGFR-2, VCAM-1, and IL-4 in the spleen of yaks and cattle. The results showed that the area of splenic trabeculae and splenic nodules was significantly larger in the yak than in yellow cattle (P<0.05). Glycogen was mainly distributed in splenic arterial endothelial cells, vascular smooth muscle cells, splenic blood sinusoidal endothelial cells, and fibroblasts, and the distribution was significantly higher in the spleen of yaks than in cattle (P<0.05). HIF-1α, VEGF, VEGFR-2, VCAM-1, and IL-4 were mainly expressed in lymphocytes, arterial endothelial cells, vascular smooth muscle cells, splenic blood sinusoidal endothelial cells, and fibroblast cytoplasm, with higher expression in yak spleen (P<0.05). In conclusion, combining the differences in spleen tissue structure, glycogen distribution, and expression distribution of several hypoxia-related factors between yaks and cattle, we suggest that HIF-1α, VEGF, VEGFR-2, VCAM-1, and IL-4 may be important factors in the adaptation of yak spleen to the plateau environment, which provides a theoretical basis for further exploring the adaptation mechanism of plateau hypoxia in yaks.

Core fucosylation of maternal milk N-glycans imparts early-life immune tolerance through gut microbiota-dependent regulation in RORγt+ Treg cells.

Milk glycans play key roles in shaping and maintaining a healthy infant gut microbiota. Core fucosylation catalyzed by fucosyltransferase (Fut8) is the major glycosylation pattern on human milk N-glycan, which was crucial for promoting the colonization and dominant growth of Bifidobacterium and Lactobacillus spp. in neonates. However, the influence of core-fucose in breast milk on the establishment of early-life immune tolerance remains poorly characterized. In this study, we found that the deficiency of core-fucose in the milk of maternal mice caused by Fut8 gene heterozygosity (Fut8+/-) resulted in poor immune tolerance towards the ovalbumin (OVA) challenge, accompanied by a reduced proportion of intestinal RORγt+ Treg cells and the abundance of Lactobacillus spp., especially L. reuteri and L. johnsonii, in their breast-fed neonates. The administration of the L. reuteri and L. johnsonii mixture to neonatal mice compromised the OVA-induced allergy and up-regulated the intestinal RORγt+ Treg cell proportions. However, Lactobacillus mixture supplementation did not alleviate allergic responses in RORγt+ Treg cell-deficient mice caused by Rorc gene heterozygosity (Rorc+/-) post OVA challenge, indicating that the intervention effects depend on the RORγt+ Treg cells. Interestingly, instead of L. reuteri and L. johnsonii, we found that the relative abundance of another Lactobacillus spp., L. murinus, in the gut of the offspring mice was significantly promoted by intervention, which showed enhancing effects on the proliferation of splenic and intestinal RORγt+ Treg cells in in vitro studies. The above results indicate that core fucosylation of breast milk N-glycans is beneficial for the establishment of RORγt+ Treg cell mediated early-life immune tolerance through the manipulation of symbiotic bacteria in mice.

Study of Transcriptomic Analysis of Yak (Bos grunniens) and Cattle (Bos taurus) Pulmonary Artery Smooth Muscle Cells under Oxygen Concentration Gradients and Differences in Their Lung Histology and Expression of Pyruvate Dehydrogenase Kinase 1-Related Factors.

The aim of this study was to investigate the molecular mechanisms by which hypoxia affects the biological behavior of yak PASMCs, the changes in the histological structure of yak and cattle lungs, and the relationships and regulatory roles that exist regarding the differences in the distribution and expression of PDK1 and its hypoxia-associated factors screened for their role in the adaptation of yak lungs to the plateau hypoxic environment. The results showed that, at the level of transcriptome sequencing, the molecular regulatory mechanisms of the HIF-1 signaling pathway, glucose metabolism pathway, and related factors (HK2/PGK1/ENO1/ENO3/ALDOC/ALDOA) may be closely related to the adaptation of yaks to the hypoxic environment of the plateau; at the tissue level, the presence of filled alveoli and semi-filled alveoli, thicker alveolar septa and basement membranes, a large number of erythrocytes, capillary distribution, and collagen fibers accounted for all levels of fine bronchioles in the lungs of yaks as compared to cattle. A higher percentage of goblet cells was found in the fine bronchioles of yaks, and PDK1, HIF-1α, and VEGF were predominantly distributed and expressed in the monolayers of ciliated columnar epithelium in the branches of the terminal fine bronchioles of yak and cattle lungs, with a small amount of it distributed in the alveolar septa; at the molecular level, the differences in PDK1 mRNA relative expression in the lungs of adult yaks and cattle were not significant (p > 0.05), the differences in HIF-1α and VEGF mRNA relative expression were significant (p < 0.05), and the expression of PDK1 and HIF-1α proteins in adult yaks was stronger than that in adult cattle. PDK1 and HIF-1α proteins were more strongly expressed in adult yaks than in adult cattle, and the difference was highly significant (p < 0.01); the relative expression of VEGF proteins was not significantly different between adult yaks and cattle (p > 0.05). The possible regulatory relationship between the above results and the adaptation of yak lungs to the plateau hypoxic environment paves the way for the regulatory mechanisms of PDK1, HIF-1α, and VEGF, and provides basic information for studying the mechanism of hypoxic adaptation of yaks in the plateau. At the same time, it provides a reference for human hypoxia adaptation and a target for the prevention and treatment of plateau diseases in humans and plateau animals.

Analysis of age-related differences in hypoxia-related factors in yak brain tissue.

The brain is an important part of the mammalian nervous system, is highly sensitive to hypoxia, and plays an important role in the adaptation of the body to hypoxic environments. This study was conducted to study the distribution and expression of hypoxia-related factors (hypoxia-inducible factor 1α, HIF-1α; erythropoietin, EPO; vascular endothelial growth factor, VEGF; vascular cell adhesion molecule, VCAM) in the cerebellum, cerebrum, medulla oblongata, and corpora quadrigemina in yaks of different ages (4d, 6-months-old and adult). Paraffin sections were obtained from the cerebellum, cerebrum, medulla oblongata, and corpora quadrigemina of healthy yak for 4-day-old, 6-months-old and adult yaks. Histological characteristics were assessed by haematoxylin staining. Immunohistochemical staining was performed to detect the distribution and expression of HIF-1α, EPO, VEGF and VCAM proteins. Immunohistochemical results showed that HIF-1α, EPO, VEGF, and VCAM were expressed in the pyramidal cell layer of the yak cerebrum, and distributed in the cerebellum granulose cell layer, Purkinje cell layer and medulla layer, and were mainly positive in Purkinje cells and medulla. It is expressed in the cell bodies of the medulla oblongata and the quadrimatous neurons. The expression level in the medulla oblongata was higher, indicating may play a crucial role in functional cohesion. The expression of HIF-1α in 4 d cerebellar tissues was higher than that in other age groups, and the expression of HIF-1α in the medulla oblongata increased with age. In addition, the expression levels of EPO and VEGF in the 6-month-old group were slightly higher than those in the other age groups. It is speculated that EPO and VEGF have obvious protective effects on brain tissue in the 6-month-old age group; VCAM showed no significant differences in the cerebrum, cerebellum, medulla oblongata, or corpora quadrigemina of the yaks. This study provides basic data for further exploration of the adaptive mechanism of plateau yak brain tissue.

Expression of EPO and related factors in the liver and kidney of plain and Tibetan sheep.

Erythropoietin (EPO), hypoxia-inducible factor-1α (HIF-1α), hypoxia-inducible factor-2α (HIF-2α), and vascular endothelial growth factor (VEGF) are key factors in the regulation of hypoxia, and can transcriptionally activate multiple genes under hypoxic conditions, thereby initiating large hypoxic stress in the network. The liver and kidneys are important metabolic organs of the body. We assessed the expression of EPO, HIF-1α, HIF-2α, and VEGF in liver and kidney tissues of plain and Tibetan sheep using hematoxylin and eosin staining, immunohistochemistry, and RT-qPCR. The results showed that EPO, HIF-1α, HIF-2α, and VEGF were expressed in tubular epithelial cells, collecting duct epithelial cells, mural epithelial cells, and the glomerular cytoplasm of Tibetan sheep, and their expression was significantly higher in Tibetan sheep than in plain sheep (P<0.05). EPO, HIF-1α, HIF-2α, and VEGF are expressed in hepatocytes, interlobular venous endothelial cells, and interlobular bile duct epithelial cells. In plain sheep, positive signals for EPO, HIF-1α, HIF-2α, and VEGF were localized mainly in interlobular venous endothelial cells, whereas VEGF and HIF-2α were negatively expressed in interlobular bile duct epithelial cells and positively expressed in EPO and HIF-1α. The differences in EPO, HIF-1α, and HIF-2α in Tibetan sheep were significantly higher than those in plain sheep (P<0.001). In the liver and kidney tissues of Tibetan sheep, EPO was associated with HIF-1α, HIF-2α, and VEGF (P<0.05). RT-qPCR results showed that EPO was not expressed, and HIF-1α, HIF-2α, and VEGF were expressed (P<0.05). The results showed that the expression of EPO, HIF-1α, HIF-2α, and VEGF in the kidney and liver of Tibetan sheep was higher than that in of plain sheep. Therefore, EPO, HIF-1α, HIF-2α, and VEGF may be involved in the adaptive response of plateau animals, which provides theoretical clarity to further explore the adaptive mechanism of plateau hypoxia in Tibetan sheep.

Combined transcriptome and proteome analysis of yak PASMCs under hypoxic and normoxic conditions.

Background: Yaks are animals that have lived in plateau environments for generations. Yaks can adapt to the hypoxic plateau environment and also pass this adaptability on to the next generation. The lungs are the most important respiratory organs for mammals to adapt to their environment. Pulmonary artery smooth muscle cells play an important role in vascular remodeling under hypoxia, but the genetic mechanism underpinning the yak's ability to adapt to challenging plateau conditions is still unknown. Methods: A tandem mass tag (TMT) proteomics study together with an RNA-seq transcriptome analysis were carried out on pulmonary artery smooth muscle cells (PASMCs) that had been grown for 72 hours in both normoxic (20% O2) and hypoxic (1% O2) environments. RNA and TP (total protein) were collected from the hypoxic and normoxic groups for RNA-seq transcriptome sequencing and TMT marker protein quantification, and RT-qPCR validation was performed. Results: A total of 17,711 genes and 6,859 proteins were identified. Further, 5,969 differentially expressed genes (DEGs) and 531 differentially expressed proteins (DEPs) were identified in the comparison group, including 2,924 and 186 upregulated genes and proteins and 3,045 and 345 down-regulated genes and proteins, respectively. The transcriptomic and proteomic analyses revealed that 109 DEGs and DEPs were highly positively correlated, with 77 genes showing the same expression trend. Nine overlapping genes were identified in the HIF-1 signaling pathway, glycolysis / gluconeogenesis, central carbon metabolism in cancer, PPAR signaling pathway, AMPK signaling pathway, and cholesterol metabolism (PGAM1, PGK1, TPI1, HMOX1, IGF1R, OLR1, SCD, FABP4 and LDLR), suggesting that these differentially expressed genes and protein functional classifications are related to the hypoxia-adaptive pathways. Overall, our study offers abundant data for further analysis of the molecular mechanisms in yak PASMCs and their adaptability to different oxygen concentrations.