Effects of oxygen tension and IGF-I on HIF-1α protein expression in mouse blastocysts

IL-17A Orchestrates Reactive Oxygen Species/HIF1α-Mediated Metabolic Reprogramming in Psoriasis

Immune cell-derived IL-17A is one of the key pathogenic cytokines in psoriasis, an immunometabolic disorder. Although IL-17A is an established regulator of cutaneous immune cell biology, its functional and metabolic effects on nonimmune cells of the skin, particularly keratinocytes, have not been comprehensively explored. Using multiomics profiling and systems biology-based approaches, we systematically uncover significant roles for IL-17A in the metabolic reprogramming of human primary keratinocytes (HPKs). High-throughput liquid chromatography-tandem mass spectrometry and nuclear magnetic resonance spectroscopy revealed IL-17A-dependent regulation of multiple HPK proteins and metabolites of carbohydrate and lipid metabolism. Systems-level MitoCore modeling using flux-balance analysis identified IL-17A-mediated increases in HPK glycolysis, glutaminolysis, and lipid uptake, which were validated using biochemical cell-based assays and stable isotope-resolved metabolomics. IL-17A treatment triggered downstream mitochondrial reactive oxygen species and HIF1α expression and resultant HPK proliferation, consistent with the observed elevation of these downstream effectors in the epidermis of patients with psoriasis. Pharmacological inhibition of HIF1α or reactive oxygen species reversed IL-17A-mediated glycolysis, glutaminolysis, lipid uptake, and HPK hyperproliferation. These results identify keratinocytes as important target cells of IL-17A and reveal its involvement in multiple downstream metabolic reprogramming pathways in human skin.

Regulation of hypoxia-inducible factor 1α by optimal oxygen concentration enhances oocyte maturation and early embryonic development in buffalo

Despite significant progress in vitro maturation (IVM) and in vitro culture (IVC) of oocytes and embryos, their developmental competence remains low. To address this issue, we used buffalo oocytes as a model system to investigate the effects and mechanisms of oxygen concentration on IVM and IVC. Our findings demonstrated that culturing buffalo oocytes with 5% oxygen significantly enhanced the efficiency of IVM and developmental competence of early embryos. Immunofluorescence results suggested that HIF1α played a critical role in these progresses. RT-qPCR results showed that maintaining a stable expression of HIF1α in cumulus cells with 5% oxygen concentration enhanced glycolysis, expansion, and proliferation abilities, up-regulated the expression of development-related genes, and suppressed apoptosis level. Consequently, it improved the maturation efficiency and quality of oocytes, leading to improve developmental capacity of buffalo early embryos. Similar outcomes were also observed when embryos were cultured with 5% oxygen. Collectively, our study provided insights into the role of oxygen regulation during oocytes maturation and early embryo development, and could potentially improve the efficiency of human assisted-reproduction technology.

Supplementation of culture medium with quercetin improves mouse blastocyst quality and increases the expression of HIF-1α protein

Regarding the low number of embryos that reach the blastocyst stage when cultured in vitro, this study aimed to evaluate the effects of quercetin on pre-implantation mouse (Mus musculus) embryos obtained using in vitro fertilization, especially during the passage from morula to blastocyst. Furthermore, we studied whether quercetin also affected the expression of hypoxia-inducible factor 1α (HIF-1α). The culture medium for the embryos was supplemented with quercetin, for long or short periods of time, and then the development potential, total cell number, apoptosis rates and expression of HIF-1α were studied to determine the effect of quercetin. Embryos failed to develop when cultured for long periods of time with quercetin, implying the possible toxic effects of this, alternatively antioxidant, compound. However, a short culture from morula to blastocyst significantly improved the development potential of in vitro produced embryos, increasing the final total cell number and reducing the apoptosis rate, observing similar results to those embryos cultured in low-oxygen concentrations or developed in utero. Furthermore, in embryos treated with quercetin for 2 or 4 h we found an increase in HIF-1α compared with untreated embryos. This work could imply a way to use quercetin in fertility clinics to improve the production of healthy blastocysts and, consequently, increase the success rates in assisted reproduction techniques.

Effect of the addition of 4OHE2 and quercetin in culture media on ROS levels and gene expression in mouse blastocysts

AIMS

The main objective of this work is to elucidate whether Quercetin (Qc) and 4-Hidroxistradiol (4OHE2 ) decrease the level of reactive oxygen species (ROS) in in vitro obtained embryos and to analyse which genes are activated under the treatments that could explain this improvement.

METHODS

Oxidative stress was induced during embryo culture by H2 O2 treatment and ROS production was measured and compared with embryos treated with Qc or 4OHE2 . Gene expression was analysed by Q-PCR in control embryos obtained in utero (IU) or by IVF and compared with the levels found in embryos cultured with Qc or 4OHE2 to determine the effect of these compounds.

KEY RESULTS

Qc strongly reduces ROS levels in embryos after a treatment of 4h. On the contrary, 4OHE2 had no effect in reducing ROS levels in embryos. The addition of these molecules to the culture media upregulate several hypoxia-related genes when Qc is added to the culture media, and implantation-related genes when 4OHE2 is used.

CONCLUSIONS

Qc is a very strong antioxidant molecule that when used for short periods of time during culture can reduce ROS levels and improve embryo quality by activating antioxidant enzymes. 4OHE2 supplementation, despite having no effects in reducing ROS levels, acts directly in the molecular signalling implicated in the implantation process and could be also considered as a supplement for embryo culture during IVF.

IMPLICATIONS

Proper supplementation of the culture media could greatly improve the quality of embryos cultured in vitro , resulting in better results in IVF clinics.

Impact of heat stress on embryonic development during first 16 days of gestation in dairy cows

Objective was to elucidate the effects of heat stress (HS) on embryo development during first 16 gestational days (GD) and circulating hormone concentrations on GD-16 in lactating Holstein cows. Cows in HS and control (CON) groups were exposed to temperature humidity index (THI) of ≥ 73 and < 73, respectively, for 3 weeks before the experiment. GD-7 (67 vs 49%) and GD-16 (52 vs. 31%) conception rates following single insemination were greater (P < 0.01) for CON compared with HS cows. Control cows produced more GD-7 transferrable embryos following superovulation compared with HS cows (84.8 vs 53.1%; P < 0.001). Mean (± SEM) length (45.2 ± 10.6 vs. 59.2 ± 9.1 mm) and weight (31.4 ± 4.3 vs. 42.4 ± 6.2 mg) of GD-16 conceptus were greater for CON compared with HS cows (P < 0.05). Control cows yielded more filamentous conceptus (≥ 25 mm) compared with HS cows (71 vs 45%; P < 0.05). Progesterone (2.09-fold) was higher, and cortisol (1.86-fold), prolactin (1.60-fold), substance-P (1.55-fold), Isoprostane-8 (1.34-fold) and prostaglandin F metabolites (1.97-fold) were lower in CON compared with HS cows (P < 0.05). Progesterone positively, and substance-P, isoprostane-8 and the THI negatively were associated with GD-16 conceptus length (P < 0.05). In conclusion, altered hormones concentrations in heat-stressed cows plausibly resulted in lower GD-7 and GD-16 conception rates, fewer GD-7 transferable embryos, and stunted GD-16 conceptus elongation.

The expression of hypoxia-inducible factor-1 alpha in primary reproductive organs of the female yak (Bos grunniens) at different reproductive stages

The yak (Bos grunniens) is the most important livestock animal in high-altitude regions owing to its prominent adaptability to cold conditions, nutritional deficiencies and hypoxia. The reproductive organs exhibit different histological appearances and physiological processes at different reproductive stages. Hypoxia-inducible factor-1 alpha (HIF-1α) is the regulatory subunit of HIF-1 that crucially regulates the response to hypoxia in mammalian organisms. The goal of our study was to investigate the expression and distribution of HIF-1α in the primary yak reproductive organs at different reproductive stages. Samples of the ovary, oviduct and uterus of 15 adult female yaks were collected and used in the experiment. The expression and localization of HIF-1α proteins and mRNA were investigated using quantitative real-time polymerase chain reaction (qRT-PCR), Western blot (WB) and immunohistochemistry (IHC). The results indicated that the expression of HIF-1α protein in the ovary was higher during the luteal phase than during the follicular phase and gestation period (p < .05). In the oviduct, HIF-1α protein was also more highly expressed during the luteal phase than during the follicular phase and gestation period (p < .01). However, in the uterus, the HIF-1α protein had stronger expression during the gestation period than during the follicular phase (p < .01) and luteal phase (p < .05). The expression of HIF-1α mRNA was similar to that of its protein. Immunohistochemical analysis revealed intense immunostaining of HIF-1α proteins in the follicular granulosa cells, granular luteal cells, villous epithelial cells of the oviduct, endometrial glandular epithelium and luminal epithelium, foetal villous trophoblast, and epithelia of caruncular crypts. This study showed that the expression of HIF-1α in the ovary, oviduct and uterus varies according to the stage of the reproductive cycle. This implies that HIF-1α plays an important role in regulating the stage-specific physiological function of yak reproductive organs under hypoxic environments.

Exogenous growth factors do not affect the development of individually cultured murine embryos

PURPOSE

The objective of this study was to evaluate the effects of multiple growth factors on the development of individually cultured murine embryos.

METHODS

Embryos produced by in vitro fertilization using in vitro (IVM) or in vivo (IVO) matured oocytes from three strains of mice (CF1, Swiss Webster, B6D2F1) were cultured individually (10 μl) in the absence (control) or presence of growth factors (paf, epidermal growth factor [EGF], insulin-like growth factor 1 [IGF-1], and granulocyte-macrophage colony-stimulating factor [GM-CSF]). Blastocyst formation, hatching, and blastocyst cell numbers (trophectoderm, inner cell mass, and total) were evaluated on days 4 and 5 of culture. Post-hatching development of CF1 IVO embryos was also evaluated in vitro and in vivo.

RESULTS

The presence of growth factors did not improve the proportion of embryos forming blastocysts or initiating hatching for any of the types of embryos tested. The only significant (P < 0.05) effect of growth factors was a decrease in the proportion of embryos that formed blastocysts by day 5 in CF1 IVM embryos. The presence of growth factors also did not affect blastocyst cell numbers. For CF1 IVO embryos, the presence of growth factors during culture did not affect the proportion of embryos that attached to fibronectin-coated dishes, the size of the resulting outgrowths, or in vivo development following transfer.

CONCLUSION

Combinations of paf, EGF, GM-CSF, and IGF-1 did not improve development of murine embryos cultured individually in a sequential medium containing a defined protein source.

Low oxygen tension increases mitochondrial membrane potential and enhances expression of antioxidant genes and implantation protein of mouse blastocyst cultured in vitro

BACKGROUND

In human IVF, embryos cultured with a lower O2 tension (5%) can give rise to higher success rates when compared with normoxic conditions (20%). However, the mechanisms behind the beneficial effects of reduced oxygen tension in embryogenesis remain unclear. The aim of this study was to evaluate the expression of oxygen related and antioxidant genes and mitochondrial function in mouse embryo cultured under hypoxic and normoxic conditions, to investigate the beneficial effect of low oxygen tension in preimplantation embryogenesis.

METHODS

Two-cell ICR mouse embryos were cultured to blastocysts under different oxygen tension (3% and 20%). The gene expression of oxygen-related proteins (hypoxia-inducible factor, HIF), HIF targets (vascular endothelial growth factor, VEGF; glucose transporter 3, GLUT-3) and antioxidants (manganese superoxide dismutase, MnSOD; peroxiredoxin 5, PRDX5) were assessed using quantitative RT-PCR and implantation-related protein (Leukemia Inhibitory Factor Receptor, LIFR) was validated by immunofluorescence. Apoptosis, mitochondrial membrane potential (MtMP) and ROS levels were measured by TUNEL, JC-1 and DCFDA assays, respectively.

RESULTS

Blastocyst development rate (92.3% vs. 79.4%) and hatch rate (80% vs. 70.4%) were both higher in embryos cultured in 3% O2 than in 20% O2. The transcription levels of MnSOD, PRDX5, VEGF and GLUT-3 also significantly increased in 3% O2 compared with 20% O2 (P < 0.05). Immunofluorescence showed that the intensity of staining for HIF-2α, MnSOD and LIFR were higher in 3% O2. Blastocysts cultured under 3% O2 exhibited significantly higher MtMP compared with 20% O2. ROS and Apoptosis levels were significantly higher in the 20% O2 group than in the 3% O2 group (P < 0.05).

CONCLUSIONS

Low O2 tension may improve embryo viability by increasing expression of antioxidant enzymes and glucose transporter activities. It provides an environment conducive to viability by upregulation of LIFR/VEGF and increased MtMP which could enhance implantation potential and reduce apoptosis in mouse blastocyst. These effects may be initiated and regulated by HIF-2α, a key mediator in a hypoxic environment.

Preimplantation maternal stress impairs embryo development by inducing oviductal apoptosis with activation of the Fas system

STUDY QUESTION

What are the mechanisms by which the preimplantation restraint stress (PIRS) impairs embryo development and pregnancy outcome?

SUMMARY ANSWER

PIRS impairs embryo development by triggering apoptosis in mouse oviducts and embryos,and this involves activation of the Fas system.

WHAT IS KNOWN ALREADY

Although it is known that the early stages of pregnancy are more vulnerable than later stages to prenatalstress, studies on the effect of preimplantation stress on embryo developmentare limited. Furthermore, the mechanisms by which psychological stress impairs embryo development are largely unknown. These issues are worth exploring using the mouse PIRS models because restraint of mice is an efficient experimental procedure developed for studies of psychogenic stress.

STUDY DESIGN, SIZE AND DURATION

Mice of Kunming strain, the generalized lymphoproliferative disorder (gld) mice with a germline mutation F273L in FasL in a C57BL/6J genomic background and the wild-type C57BL/6J mice were used. Female and male mice were used 8-10 weeks and 10-12 weeks after birth, respectively. Female mice showing vaginal plugs were paired by weight and randomly assigned to restraint treatments or as controls. For restraint treatment, an individual mouse was put in a micro-cage with food and water available. Control mice remained in their cages with food and water during the time treated females were stressed.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Female mice were exposed to PIRS for 48 h starting from 16:00 on the day of vaginal plug detection. At the end of PIRS, levels of glucorticoids (GC), corticotropin-releasing hormone (CRH)and redox potential were measured in serum, while levels of GC, GC receptor (GR), CRH, CRH receptor (CRHR), Fas and Fas ligand (FasL) protein, mRNAs for brain derived neurotrophic factor (BDNF) and insulin-like growth factor-1 (IGF-1), oxidative stress (OS) and apoptosis were examined in oviducts. Preimplantation development and levels of GR, Fas, redox potential and apoptosis were observed in embryos recovered at different times after the initiation of PIRS. The gld mice were used to confirm a role for the Fas system in triggering apoptosis of embryos and oviducts.

MAIN RESULTS AND THE ROLE OF CHANCE

Compared to those in control mice, while the number of blastocysts/mouse (5.0 ± 0.7 versus 11.1 ± 0.5), cell number/blastocyst (49.1 ± 1.3 versus 61.5 ± 0.9), percentages of term pregnancy (37.5% versus 90.9%) and litter size (3.7 ± 0.1versus 9.6 ± 0.6) decreased, blood CRH (560 ± 23 versus 455 ± 37 pg/ml), cortisol (27.3 ± 3.4 versus 5 ± 0.5 ng/ml) and OS index (OSI: 2.8 versus 1.7) increased significantly (all P < 0.05) following PIRS. In the oviduct, while levels of CRH (1175 ± 85 versus 881 ± 33 pg/100 mg), cortisol (28.9 ± 1.7 versus14 ± 4 ng/g), CRHR (2.3 ± 0.3 versus 1.0 ± 0.0), FasL (1.31 ± 0.06 versus 1.08 ± 0.05 ng/g), Fas (1.42 ± 0.13 versus 1.0 ± 0.0) and apoptotic cells (19.1 ± 0.5% versus 8.4 ± 0.4%) increased, levels of GR proteins (0.67 ± 0.14 versus 1.0 ± 0.0) and Igf-1 (0.6 ± 0.09 versus 1.0 ± 0.0) and Bdnf (0.73 ± 0.03 versus 1.0 ± 0.0) mRNAs decreased significantly (all P < 0.05 versus control) after PIRS. Mouse embryos expressed GR and Fas at all stages of preimplantation development and embryo OS (GSH/GSSG ratio: 0.88 ± 0.03 versus 1.19 ± 0.13) and annexin-positive cells (blastocysts: 31.4 ± 3.8% versus 10.96 ± 3.4%) increased significantly (P < 0.05) following PIRS. Furthermore, the detrimental effects of PIRS on embryo development and oviductal apoptosis were much reduced in gld mice. Thus, PIRS triggered apoptosis in oviductal cells with activation of the Fas/FasL system. The apoptotic oviductal cells promoted embryo apoptosis with reduced production of IGF-1 and BDNF and increased production of FasL.

LIMITATIONS, REASONS FOR CAUTION

Although important, the conclusions were drawn from limited results obtained using a single model in one species and thus they need further verification using other models and/or in other species. Furthermore, as differences in stressed samples were modest and sometimes not significant between gld and wild-type mice whereas differences between control and stressed samples were always present within gld mice, it is deduced that signaling pathways other than the Fas/FasL system might be involved as well in the PIRS-triggered apoptosis of oviducts and embryos.

WIDER IMPLICATIONS OF THE FINDINGS

The data are important for studies on the mechanisms by which psychological stress affects female reproduction, as FasL expression has been observed in human oviduct epithelium.

LARGE SCALE DATA

Not applicable.

STUDY FUNDING AND COMPETING INTERESTS

This study was supported by grants from the National Basic Research Program of China (Nos. 2014CB138503 and 2012CB944403), the China National Natural Science Foundation (Nos. 31272444 and 30972096) and the Animal breeding improvement program of Shandong Province. All authors declare that their participation in the study did not involve factual or potential conflicts of interests.