Quercetin prophylaxis protects the kidneys by modulating the renin-angiotensin-aldosterone axis under acute hypobaric hypoxic stress.

The study presented here aims at assessing the effects of hypobaric hypoxia on RAAS pathway and its components along with mitigation of anomalies with quercetin prophylaxis. One hour prior to hypobaric hypoxia exposure, male SD rats were orally supplemented with quercetin (50 mg/kg BW) and acetazolamide (50 mg/kg BW) and exposed them to 25,000 ft. (7,620 m) in a simulated environmental chamber for 12 h at 25 ± 2 °C. Different biochemical parameters like renin activity, aldosterone, angiotensin I, ACE 2 were determined in plasma. As a conventional response to low oxygen conditions, oxidative stress parameters (ROS and MDA) were elevated along with suppressed antioxidant system (GPx and catalase) in plasma of rats. Quercetin prophylaxis significantly down regulated the hypoxia induced oxidative stress by reducing plasma ROS & MDA levels with efficient enhancement of antioxidants (GPx and Catalase). Further, hypoxia mediated regulation of renin and ACE 2 proves the outstanding efficacy of quercetin in repudiating altercations in RAAS cascade due to hypobaric hypoxia. Furthermore, differential protein expression of HIF-1α, NFκB, IL-18 and endothelin-1 analyzed by western blotting approves the biochemical outcomes and showed that quercetin significantly aids in the reduction of inflammation under hypoxia. Studies conducted with Surface Plasmon Resonance demonstrated a binding among quercetin and ACE 2 that indicates that this flavonoid might regulate RAAS pathway via ACE 2. Henceforth, the study promotes the prophylaxis of quercetin for the better adaptability under hypobaric hypoxic conditions via modulating the RAAS pathway.

Sanshimao formula inhibits the hypoxia-induced pro-angiogenesis of hepatocellular carcinoma cells partly through regulating MKK6/p38 signaling pathway.

OBJECTIVES: Sanshimao (SSM) is a traditional Chinese medicine formula for advanced hepatocellular carcinoma (HCC). This study was designed to investigate the effect of SSM on HCC-induced angiogenesis and to explore the potential mechanism. METHODS: The endothelial cells were cultured with HCC cells conditioned medium in the 1% oxygen atmosphere to imitate tumor hypoxia microenvironment. EA.hy926 cells migration and tubulogenesis were detected by tube formation and scratch-wound assay. The protein microarray was employed to explore SSM-targeted proteins in Huh7 cells. We also established an animal model to observe the effects of SSM on angiogenesis in vivo. RESULTS: The data indicated that SSM reduced HCC-induced migration and tube formation of EA.hy926 cells at low dose under hypoxic conditions. These effects might be partly owing to suppression of HIF-1α-induced vascular endothelial growth factorα expression in Huh7 cells. Moreover, this inhibition was in an MKK6/P38-dependent way. Besides, Huh7 subcutaneous tumor models in nude mice further demonstrated the inhibition of SSM on tumor weight might be exerted partly by reduction of angiogenesis via blocking MKK6/P38 signaling pathways. CONCLUSION: SSM inhibits HCC-induced pro-angiogenesis under hypoxic conditions via suppression of MKK6/P38 signaling pathways, which is favorable for HCC tumor growth.

L-Borneol promotes skin flap survival by regulating HIF-1α/NF-κB pathway.

ETHNOPHARMACOLOGICAL RELEVANCE: The clinical application of skin flaps in surgical reconstruction is frequently impeded by the occurrence of distant necrosis. L-Borneol exhibits myogenic properties in traditional Chinese medicine and is used in clinical settings to promote wound healing and conditions such as stroke. Nevertheless, the precise mechanism by which borneol exerts its protective effects on skin flap survival remains unclear. AIM OF THE STUDY: To explore the potential of L-borneol to promote skin flap survival and elucidate the underlying mechanisms. MATERIALS AND METHODS: Thirty-six male Sprague-Dawley rats were randomly divided into three groups: a high-dose (200 mg/kg L-borneol per day), a low-dose (50 mg/kg/day), and control group (same volume of solvent). In each rat, a modified rectangular McFarlane flap model measuring 3 × 9 cm was constructed. Daily intragastric administration of L-borneol or solvent was performed. The flap was divided into three square sections of equal size, namely Zone I (the proximal zone), Zone II (the intermediate zone), and Zone III (the distal zone). The survival rate was quantified, and the histological state of each flap was evaluated on the seventh day following the surgical procedure. The assessment of angiogenesis was conducted using lead oxide/gelatin angiography, whereas the evaluation of blood flow in the free flap was performed using laser Doppler flow imaging. Superoxide dismutase activity was detected using the water-soluble tetrazolium salt-8 method. The quantities of vascular endothelial growth factor, interleukin (IL)-1ß, IL-6, and tumour necrosis factor-α were determined using immunohistochemistry. The levels of nuclear transcription factor-κB, hypoxia-inducible factor-1, B-cell lymphoma-2 (BCL-2), and BCL-2-associated X (BAX) were determined by Western blotting technique. RESULTS: Flap survival rate significantly improved and neutrophil recruitment and release were enhanced after treatment with the compound. Angiogenesis was promoted. L-borneol protected against oxidative stress by increasing superoxide dismutase activity and decreasing malondialdehyde content. It downregulated the hypoxia-inducible factor nuclear transcription factor-κB pathway, leading to the inhibition of several inflammatory factors. Simultaneously, it facilitated the expression of vascular endothelial growth factor and BCL-2. CONCLUSION: The study shows that L-borneol may promote skin flap survival by inhibiting HIF-1α/NF-κB pathway.

Insulin-induced gene 2 protects against hepatic ischemia-reperfusion injury via metabolic remodeling.

BACKGROUND: Hepatic ischemia-reperfusion (IR) injury is the primary reason for complications following hepatectomy and liver transplantation (LT). Insulin-induced gene 2 (Insig2) is one of several proteins that anchor the reticulum in the cytoplasm and is essential for metabolism and inflammatory responses. However, its function in IR injury remains ambiguous. METHODS: Insig2 global knock-out (KO) mice and mice with adeno-associated-virus8 (AAV8)-delivered Insig2 hepatocyte-specific overexpression were subjected to a 70% hepatic IR model. Liver injury was assessed by monitoring hepatic histology, inflammatory responses, and apoptosis. Hypoxia/reoxygenation stimulation (H/R) of primary hepatocytes and hypoxia model induced by cobalt chloride (CoCl2) were used for in vitro experiments. Multi-omics analysis of transcriptomics, proteomics, and metabolomics was used to investigate the molecular mechanisms underlying Insig2. RESULTS: Hepatic Insig2 expression was significantly reduced in clinical samples undergoing LT and the mouse IR model. Our findings showed that Insig2 depletion significantly aggravated IR-induced hepatic inflammation, cell death and injury, whereas Insig2 overexpression caused the opposite phenotypes. The results of in vitro H/R experiments were consistent with those in vivo. Mechanistically, multi-omics analysis revealed that Insig2 is associated with increased antioxidant pentose phosphate pathway (PPP) activity. The inhibition of glucose-6-phosphate-dehydrogenase (G6PD), a rate-limiting enzyme of PPP, rescued the protective effect of Insig2 overexpression, exacerbating liver injury. Finally, our findings indicated that mouse IR injury could be attenuated by developing a nanoparticle delivery system that enables liver-targeted delivery of substrate of PPP (glucose 6-phosphate). CONCLUSIONS: Insig2 has a protective function in liver IR by upregulating the PPP activity and remodeling glucose metabolism. The supplementary glucose 6-phosphate (G6P) salt may serve as a viable therapeutic target for alleviating hepatic IR.

A Comparative Biochemical Study Between L-Carnosine and ß-Alanine in Amelioration of Hypobaric Hypoxia-Induced Skeletal Muscle Protein Loss.

Rathor, Richa, Sukanya Srivastava, and Geetha Suryakumar. A comparative biochemical study between L-carnosine and ß-alanine in amelioration of hypobaric hypoxia-induced skeletal muscle protein loss. High Alt Med Biol. 24:302-311, 2023. Background: Carnosine (CAR; ß-alanyl-L-histidine), a biologically active dipeptide is known for its unique pH-buffering capacity, metal chelating activity, and antioxidant and antiglycation property. ß-Alanine (ALA) is a nonessential amino acid and used to enhance performance and cognitive functions. Hypobaric hypoxia (HH)-induced muscle protein loss is regulated by multifaceted signaling pathways. The present study investigated the beneficial effects of CAR and ALA against HH-associated muscle loss. Methodology: Simulated HH exposure was performed in an animal decompression chamber. Gastric oral administration of CAR (50 mg·kg-1) and ALA (450 mg·kg-1) were given daily for 3 days and at the end of the treatment, hindlimb skeletal muscle tissue was excised for western blot and biochemical assays. Results: Cosupplementation of CAR and ALA alone was able to ameliorate the hypoxia-induced inflammation, oxidative stress (FOXO), ER stress (GRP-78), and atrophic signaling (MuRF-1) in the skeletal muscles. Creatinine phospho kinase activity and apoptosis were also decreased in CAR- and ALA-supplemented rats. However, CAR showed enhanced protection in HH-induced muscle loss as CAR supplementation was able to enhance protein concentration, body weight, and decreased the protein oxidation and ALA administration was not able to restore the same. Conclusions: Hence, the present comprehensive study supports the fact that CAR (50 mg·kg-1) is more beneficial as compared with ALA (450 mg·kg-1) in ameliorating the hypoxia-induced skeletal muscle loss.

Viability of HepG2 and MCF-7 cells is not correlated with mitochondrial bioenergetics.

Alterations in metabolism are a hallmark of cancer. It is unclear if oxidative phosphorylation (OXPHOS) is necessary for tumour cell survival. In this study, we investigated the effects of severe hypoxia, site-specific inhibition of respiratory chain (RC) components, and uncouplers on necrotic and apoptotic markers in 2D-cultured HepG2 and MCF-7 tumour cells. Comparable respiratory complex activities were observed in both cell lines. However, HepG2 cells exhibited significantly higher oxygen consumption rates (OCR) and respiratory capacity than MCF-7 cells. Significant non-mitochondrial OCR was observed in MCF-7 cells, which was insensitive to acute combined inhibition of complexes I and III. Pre-treatment of either cell line with RC inhibitors for 24-72 h resulted in the complete abolition of respective complex activities and OCRs. This was accompanied by a time-dependent decrease in citrate synthase activity, suggesting mitophagy. High-content automated microscopy recordings revealed that the viability of HepG2 cells was mostly unaffected by any pharmacological treatment or severe hypoxia. In contrast, the viability of MCF-7 cells was strongly affected by inhibition of complex IV (CIV) or complex V (CV), severe hypoxia, and uncoupling. However, it was only moderately affected by inhibition of complexes I, II, and III. Cell death in MCF-7 cells induced by inhibition of complexes II, III, and IV was partially abrogated by aspartate. These findings indicate that OXPHOS activity and viability are not correlated in these cell lines, suggesting that the connection between OXPHOS and cancer cell survival is dependent on the specific cell type and conditions.

A comprehensive review of natural products with anti-hypoxic activity.

Natural products exhibit substantial impacts in the field of anti-hypoxic traetment. Hypoxia can cause altitude sickness and other negative effect on the body. Headache, coma, exhaustion, vomiting and, in severe cases, death are some of the clinical signs. Currently, hypoxia is no longer just a concern in plateau regions; it is also one of the issues that can not be ignored by urban residents. This review covered polysaccharides, alkaloids, saponins, flavonoids, peptides and traditional Chinese compound prescriptions as natural products to protect against hypoxia. The active ingredients, effectiveness and mechanisms were discussed. The related anti-hypoxic mechanisms involve increasing the hemoglobin (HB) content, glycogen content and adenosine triphosphate (ATP) content, removing excessive reactive oxygen species (ROS), reducing lipid peroxidation, regulating the levels of related enzymes in cells, protecting the structural and functional integrity of the mitochondria and regulating the expression of apoptosis-related genes. These comprehensive summaries are beneficial to anti-hypoxic research and provide useful information for the development of anti-hypoxic products.

Effects of Zinc on the Right Cardiovascular Circuit in Long-Term Hypobaric Hypoxia in Wistar Rats.

Hypobaric hypoxia under chromic conditions triggers hypoxic pulmonary vasoconstriction (HPV) and right ventricular hypertrophy (RVH). The role of zinc (Zn) under hypoxia is controversial and remains unclear. We evaluated the effect of Zn supplementation in prolonged hypobaric hypoxia on HIF2α/MTF-1/MT/ZIP12/PKCε pathway in the lung and RVH. Wistar rats were exposed to hypobaric hypoxia for 30 days and randomly allocated into three groups: chronic hypoxia (CH); intermittent hypoxia (2 days hypoxia/2 days normoxia; CIH); and normoxia (sea level control; NX). Each group was subdivided (n = 8) to receive either 1% Zn sulfate solution (z) or saline (s) intraperitoneally. Body weight, hemoglobin, and RVH were measured. Zn levels were evaluated in plasma and lung tissue. Additionally, the lipid peroxidation levels, HIF2α/MTF-1/MT/ZIP12/PKCε protein expression and pulmonary artery remodeling were measured in the lung. The CIH and CH groups showed decreased plasma Zn and body weight and increased hemoglobin, RVH, and vascular remodeling; the CH group also showed increased lipid peroxidation. Zn administration under hypobaric hypoxia upregulated the HIF2α/MTF-1/MT/ZIP12/PKCε pathway and increased RVH in the intermittent zinc group. Under intermittent hypobaric hypoxia, Zn dysregulation could participate in RVH development through alterations in the pulmonary HIF2α/MTF1/MT/ZIP12/PKCε pathway.

Biomarkers of lung alveolarization and microvascular maturation in response to intermittent hypoxia and/or early antioxidant/fish oil supplementation in neonatal rats.

OBJECTIVE: Extremely preterm infants experience frequent intermittent hypoxia (IH) episodes during oxygen therapy which causes significant damage to the lungs and curtails important signaling pathways that regulate normal lung alveolarization and microvascular maturation. We tested the hypothesis that early supplementation with fish oil and/or antioxidants in rats exposed to neonatal IH improves expression of lung biomarkers of alveolarization and microvascular maturation, and reduces IH-induced lung injury. STUDY DESIGN/METHODS: From birth (P0) to P14, rat pups were exposed to room air (RA) or neonatal IH during which they received daily oral supplementation with either: (1) olive oil (OO) (control); (2) Coenzyme Q10 (CoQ10) in OO; (3) fish oil; (4) glutathione nanoparticles (nGSH); or (5) fish oil +CoQ10. At P14 pups were placed in RA until P21 with no further treatment. RA controls were similarly treated. Lung growth and alveolarization, histopathology, apoptosis, oxidative stress and biomarkers of alveolarization and microvascular maturation were determined. RESULTS: Neonatal IH was associated with reduced lung weights and severe histopathological outcomes. These effects were curtailed with fish oil and nGSH. nGSH was also protective against apoptosis, while CoQ10 prevented IH-induced ROS production. Of all treatments, nGSH and CoQ10 + fish oil-induced vascular endothelial growth factor165 and CD31 (Platelet endothelial cell adhesion molecule-1), which are associated with angiogenesis. CoQ10 + fish oil improved alveolarization in RA and IH despite evidence of hemorrhage. CONCLUSIONS: The benefits of nGSH and CoQ10 + fish oil suggest an antioxidant effect which may be required to curtail IH-induced lung injury. Further clinical assessment of the effectiveness of nGSH is warranted.

Vascular protection afforded by zinc supplementation in human coronary artery smooth muscle cells mediated by NRF2 signaling under hypoxia/reoxygenation.

Zinc (Zn) has antioxidant, anti-inflammatory and anti-proliferative actions, with Zn dysregulation associated with coronary ischemia/reperfusion injury and smooth muscle cell dysfunction. As the majority of studies concerning Zn have been conducted under non-physiological hyperoxic conditions, we compare the effects of Zn chelation or supplementation on total intracellular Zn content, antioxidant NRF2 targeted gene transcription and hypoxia/reoxygenation-induced reactive oxygen species generation in human coronary artery smooth muscle cells (HCASMC) pre-adapted to hyperoxia (18 kPa O2) or normoxia (5 kPa O2). Expression of the smooth muscle marker SM22-α was unaffected by lowering pericellular O2, whereas calponin-1 was significantly upregulated in cells under 5 kPa O2, indicating a more physiological contractile phenotype under 5 kPa O2. Inductively coupled plasma mass spectrometry established that Zn supplementation (10 µM ZnCl2 + 0.5 µM pyrithione) significantly increased total Zn content in HCASMC under 18 but not 5 kPa O2. Zn supplementation increased metallothionein mRNA expression and NRF2 nuclear accumulation in cells under 18 or 5 kPa O2. Notably, NRF2 regulated HO-1 and NQO1 mRNA expression in response to Zn supplementation was only upregulated in cells under 18 but not 5 kPa. Furthermore, whilst hypoxia increased intracellular glutathione (GSH) in cells pre-adapted to 18 but not 5 kPa O2, reoxygenation had negligible effects on GSH or total Zn content. Reoxygenation-induced superoxide generation in cells under 18 kPa O2 was abrogated by PEG-superoxide dismutase but not by PEG-catalase, and Zn supplementation, but not Zn chelation, attenuated reoxygenation-induced superoxide generation in cells under 18 but not 5kPaO2, consistent with a lower redox stress under physiological normoxia. Our findings highlight that culture of HCASMC under physiological normoxia recapitulates an in vivo contractile phenotype and that effects of Zn on NRF2 signaling are altered by oxygen tension.

Uncovering the Ediacaran phosphorus cycle.

Phosphorus is a limiting nutrient that is thought to control oceanic oxygen levels to a large extent1-3. A possible increase in marine phosphorus concentrations during the Ediacaran Period (about 635-539 million years ago) has been proposed as a driver for increasing oxygen levels4-6. However, little is known about the nature and evolution of phosphorus cycling during this time4. Here we use carbonate-associated phosphate (CAP) from six globally distributed sections to reconstruct oceanic phosphorus concentrations during a large negative carbon-isotope excursion-the Shuram excursion (SE)-which co-occurred with global oceanic oxygenation7-9. Our data suggest pulsed increases in oceanic phosphorus concentrations during the falling and rising limbs of the SE. Using a quantitative biogeochemical model, we propose that this observation could be explained by carbon dioxide and phosphorus release from marine organic-matter oxidation primarily by sulfate, with further phosphorus release from carbon-dioxide-driven weathering on land. Collectively, this may have resulted in elevated organic-pyrite burial and ocean oxygenation. Our CAP data also seem to suggest equivalent oceanic phosphorus concentrations under maximum and minimum extents of ocean anoxia across the SE. This observation may reflect decoupled phosphorus and ocean anoxia cycles, as opposed to their coupled nature in the modern ocean. Our findings point to external stimuli such as sulfate weathering rather than internal oceanic phosphorus-oxygen cycling alone as a possible control on oceanic oxygenation in the Ediacaran. In turn, this may help explain the prolonged rise of atmospheric oxygen levels.

[Effect of moxibustion on the expressions of hypoxia inducible factor-1α and vascular endothelial growth factor in ankle synovial tissue of rats with adjuvant arthritis].

OBJECTIVE: To observe the effect of moxibustion on the expressions of hypoxia inducible factor-1α (HIF-1α) and vascular endothelial growth factor (VEGF) in ankle synovial tissue of rats with adjuvant arthritis(AA), so as to explore the mechanism of moxibustion in inhibiting synovial angiogenesis and improving joint symptoms of rheumatoid arthritis. METHODS: Sixty healthy male SD rats were randomly divided into normal group, model group, moxibustion group and medication group, with 15 rats in each group. AA rat model was established by subcutaneous injection of Freund's complete adjuvant into the right hind paw. Rats in the moxibustion group were treated with "Zusanli" (ST36), "Guanyuan" (CV4) and "Ashi" point moxibustion, 20 min each time, once a day, for consecutive 3 weeks. Rats in the medication group were given methotrexate (0.35 mg/kg) intragastric administration, twice a week, for consecutive 3 weeks. Foot plantar volume of rats was measured by toe volume mea-suring instrument. HE staining was used to observe the histopathology of ankle synovium. The protein expressions of HIF-1α and VEGF in ankle synovial tissue were detected by immunohistochemistry and Western blot. RESULTS: Compared with the normal group, the foot plantar volume and the protein expressions of HIF-1α and VEGF in synovial tissue of ankle joint were significantly increased (P<0.01) in the model group, the synovial tissue showed obvious hyperplasia and a large number of neovasculogenesis. Following the interventions, the foot plantar volume and the protein expressions of HIF-1α and VEGF in synovial tissue of ankle joint were significantly decreased (P<0.05, P<0.01) in both moxibustion and medication groups in contrast to the model group, and there was no obvious proliferation of synovial tissue, and only a few neovascularization was observed. Compared with the medication group, the foot plantar volume was decreased (P<0.05) in the moxibustion group. CONCLUSION: Moxibustion can improve joint swelling and inhibit synovial angiogenesis in AA rats, and its mechanism may be related to down-regulating of HIF-1α and VEGF protein expressions.

The Effectiveness of L-arginine in Clinical Conditions Associated with Hypoxia.

The review summarises the data of the last 50 years on the effectiveness of the amino acid L-arginine in therapeutic practice in conditions accompanied by different-origin hypoxia. The aim of this review was to analyse the literature and our research data on the role of nitric oxide in the modulation of individual physiological reactivity to hypoxia. The review considers the possibility of eliminating methodological conflicts in the case of L-arginine, which can be solved by taking into account individual physiological reactivity (or the hypoxia resistance factor). Considerable attention is paid to genetic and epigenetic mechanisms of adaptation to hypoxia and conditions of adaptation in different models. The article presents data on the clinical effectiveness of L-arginine in cardiovascular system diseases (hypertension, atherosclerosis, coronary heart disease, etc.) and stress disorders associated with these diseases. The review presents a generalised analysis of techniques, data on L-arginine use by athletes, and the ambiguous role of NO in the physiology and pathology of hypoxic states shown via nitric oxide synthesis. Data on the protective effects of adaptation in the formation of individual high reactivity in sportsmen are demonstrated. The review demonstrates a favourable effect of supplementation with L-arginine and its application depending on mitochondrial oxidative phosphorylation processes and biochemical indices in groups of individuals with low and high capacity of adaptation to hypoxia. In individuals with high initial anti-hypoxic reserves, these favourable effects are achieved by the blockade of NO-dependent biosynthesis pathways. Therefore, the methodological tasks of physiological experiments and the therapeutic consequences of treatment should include a component depending on the basic level of physiological reactivity.

YY1 lactylation in microglia promotes angiogenesis through transcription activation-mediated upregulation of FGF2.

BACKGROUND: Ocular neovascularization is a leading cause of blindness. Retinal microglia have been implicated in hypoxia-induced angiogenesis and vasculopathy, but the underlying mechanisms are not entirely clear. Lactylation is a novel lactate-derived posttranslational modification that plays key roles in multiple cellular processes. Since hypoxia in ischemic retinopathy is a precipitating factor for retinal neovascularization, lactylation is very likely to be involved in this process. The present study aimed to explore the role of lactylation in retinal neovascularization and identify new therapeutic targets for retinal neovascular diseases. RESULTS: Microglial depletion by the colony-stimulating factor 1 receptor (CSF1R) inhibitor PLX3397 suppresses retinal neovascularization in oxygen-induced retinopathy. Hypoxia increased lactylation in microglia and accelerates FGF2 expression, promoting retinal neovascularization. We identify 77 sites of 67 proteins with increased lactylation in the context of increased lactate under hypoxia. Our results show that the nonhistone protein Yin Yang-1 (YY1), a transcription factor, is lactylated at lysine 183 (K183), which is regulated by p300. Hyperlactylated YY1 directly enhances FGF2 transcription and promotes angiogenesis. YY1 mutation at K183 eliminates these effects. Overexpression of p300 increases YY1 lactylation and enhances angiogenesis in vitro and administration of the p300 inhibitor A485 greatly suppresses vascularization in vivo and in vitro. CONCLUSIONS: Our results suggest that YY1 lactylation in microglia plays an important role in retinal neovascularization by upregulating FGF2 expression. Targeting the lactate/p300/YY1 lactylation/FGF2 axis may provide new therapeutic targets for proliferative retinopathies.

Kaempferol ameliorates pulmonary vascular remodeling in chronic hypoxia-induced pulmonary hypertension rats via regulating Akt-GSK3ß-cyclin axis.

Excessive proliferation of pulmonary artery smooth muscle cells (PASMCs) is considered a major contributor to elevated pulmonary vascular resistance and a key mechanism of vascular remodeling in hypoxia-induced pulmonary hypertension (HPH). Kaempferol is a natural flavonoid compound and can be derived from numerous common medicinal herbs and vegetables, which exhibit antiproliferative and proapoptotic properties, however, the effects of kaempferol on vascular remodeling in HPH remain unexplored. In this study, SD rats were placed in a hypobaric hypoxia chamber for four weeks to establish a pulmonary hypertension model and given either kaempferol or sildenafil (an inhibitor of PDE-5) during days 1-28, after which the hemodynamic parameter and pulmonary vascular morphometry were assessed. Furthermore, primary rat PASMCs were exposed to hypoxic conditions to generate a cell proliferation model, then incubated with either kaempferol or LY294002 (an inhibitor of PI3K). Immunoblotting and real-time quantitative PCR assessed the protein and mRNA expression levels in HPH rat lungs and PASMCs. We found that kaempferol reduced pulmonary artery pressure and pulmonary vascular remodeling, and alleviated right ventricular hypertrophy in HPH rats. The mechanistic analysis demonstrated that kaempferol reduced the protein levels of phosphorylation of Akt and GSK3ß, leading to decreased expression of pro-proliferation (CDK2, CDK4, Cyclin D1, and PCNA) and anti-apoptotic related proteins (Bcl-2) and increased expression of pro-apoptosis proteins (Bax and cleaved caspase 3). These results collectively demonstrate that kaempferol ameliorates HPH in rats by inhibiting PASMC proliferation and pro-apoptosis via modulation of the Akt/GSK3ß/CyclinD axis.

Shen Shuai II Recipe inhibits hypoxia-induced glycolysis by preserving mitochondrial dynamics to attenuate kidney fibrosis.

ETHNOPHARMACOLOGICAL RELEVANCE: Shen Shuai II Recipe (SSR) is a traditional Chinese medicine prescription with significant clinical efficacy in chronic kidney disease (CKD) by invigorating Qi and resolving blood stasis, clearing away heat and dampness. Our previous studies demonstrated that SSR attenuated renal interstitial fibrosis (RIF) by improving hypoxia and mitochondrial dysfunction. AIM OF THE STUDY: The aim of this study was to investigate the potential mechanisms of SSR against RIF. MATERIALS AND METHODS: The CKD was established by 5/6 ablation/infarction (A/I) operation. After 4 weeks, rats were gavaged with SSR or Fenofibrate for 8 weeks. Hypoxia-treated NRK-52 E cells were treated with SSR and (or) glycolysis inhibitors, including GSK2837808 A (GSK) and 2-Deoxy-D-glucose (2-DG). In addition, Drp1-deficient or MFP-M1-treated NRK-52 E cells were treated with SSR under hypoxic conditions. The effects of SSR on fibrotic phenotype, glycolysis, mitochondrial dynamics and membrane potential in hypoxia-exposed NRK-52 E cells were examined by immunoblotting, colorimetric, and fluorometric methods. Furthermore, we constructed a lactic acid-induced activation model of NRK-49 F cells and a co-culture system. The activation of NRK-49 F cells was evaluated by immunoblotting method. RESULTS: Our findings indicated that SSR significantly attenuated abnormal glycolysis in vivo and in vitro, which was correlated with its renoprotective effect. Further studies revealed that improvement of mitochondrial dynamics could be one of the mechanisms by which SSR inhibits glycolysis to achieve anti-renal fibrosis. Furthermore, treatment with SSR significantly inhibited the lactic acid-induced activation of NRK-49 F cells. The co-culture results further highlighted that SSR inhibited activation of renal fibroblasts and deposition of extracellular matrix by reducing glycolysis in renal tubular cells. CONCLUSIONS: SSR alleviates RIF by inhibiting hypoxia-induced glycolysis through improvement of mitochondrial dynamics.

Kazinol B protects H9c2 cardiomyocytes from hypoxia/reoxygenation-induced cardiac injury by modulating the AKT/AMPK/Nrf2 signalling pathway.

CONTEXT: Kazinol B (KB), an isoprenylated flavan derived from Broussonetia kazinoki Sieb. (Moraceae) root, has long been used in folk medicine. OBJECTIVE: This study examines the protective effects of KB and its underlying mechanisms in hypoxia and reoxygenation (H/R)-induced cardiac injury in H9c2 rat cardiac myoblasts. MATERIALS AND METHODS: H9c2 cells were incubated with various concentrations of KB (0, 0.3, 1, 3, 10 and 30 µM) for 2 h and then subjected to H/R insults. The protective effects of KB and its underlying mechanisms were explored. RESULTS: KB significantly elevated cell viability (1 µM, 1.21-fold; 3 µM, 1.36-fold, and 10 µM, 1.47-fold) and suppressed LDH release (1 µM, 0.77-fold; 3 µM, 0.68-fold, and 10 µM, 0.59-fold) in H/R-induced H9c2 cells. Further, 10 µM KB blocked apoptotic cascades, as shown by the Annexin-V/PI (0.41-fold), DNA fragmentation (0.51-fold), caspase-3 (0.52-fold), PARP activation (0.27-fold) and Bax/Bcl-2 expression (0.28-fold) assays. KB (10 µM) downregulated reactive oxygen species production (0.51-fold) and lipid peroxidation (0.48-fold); it upregulated the activities of GSH-Px (2.08-fold) and SOD (1.72-fold). KB (10 µM) induced Nrf2 nuclear accumulation (1.94-fold) and increased ARE promoter activity (2.15-fold), HO-1 expression (3.07-fold), AKT (3.07-fold) and AMPK (3.07-fold) phosphorylation. Nrf2 knockdown via using Nrf2 siRNA abrogated KB-mediated protective effects against H/R insults. Moreover, pharmacological inhibitors of AKT and AMPK also abrogated KB-induced Nrf2 activation and its protective function. DISCUSSION AND CONCLUSIONS: KB prevented H/R-induced cardiomyocyte injury via modulating the AKT and AMPK-mediated Nrf2 induction. KB might be a promising drug candidate for managing ischemic cardiac disorders.

Tumour suppressor PTEN activity is differentially inducible by myo-inositol phosphates.

Tumour evolution and efficacy of treatments are controlled by the microenvironment, the composition of which is primarily dependent on the angiogenic reaction to hypoxic stress. Tumour angiogenesis normalization is a challenge for adjuvant therapy strategies to chemo-, radio- and immunotherapeutics. Myo-inositol trispyrophosphate (ITPP) appears to provide the means to alleviate hypoxia in the tumour site by a double molecular mechanism. First, it modifies the properties of red blood cells (RBC) to release oxygen (O2 ) in the hypoxic sites more easily, leading to a rapid and stable increase in the partial pressure of oxygen (pO2 ). And second, it activates the endothelial phosphatase and tensin homologue deleted on Chromosome 10 (PTEN). The hypothesis that stable normalization of the vascular system is due to the PTEN, a tumour suppressor and phosphatase which controls the proper angiogenic reaction was ascertained. Here, by direct biochemical measurements of PTEN competitive activity in relation to PIP2 production, we show that the kinetics are complex in terms of the activation/inhibition effects of ITPP with an inverted consequence towards the kinase PI3K. The use of the surface plasmon resonance (SPR) technique allowed us to demonstrate that PTEN binds inositol derivatives differently but weakly. This method permitted us to reveal that PTEN is highly sensitive to the local concentration conditions, especially that ITPP increases the PTEN activity towards PIP3, and importantly, that PTEN affinity for ITPP is considerably increased by the presence of PIP3, as occurs in vivo. Our approach demonstrates the validity of using ITPP to activate PTEN for stable vessel normalization strategies.

A Concerted Redox- and Light-Activated Agent for Controlled Multimodal Therapy against Hypoxic Cancer Cells.

Hypoxia represents a remarkably exploitable target for cancer therapy, is encountered only in solid human tumors, and is highly associated with cancer resistance and recurrence. Here, a hypoxia-activated mitochondria-accumulated Ru(II) polypyridyl prodrug functionalized with conjugated azo (Az) and nitrogen mustard (NM) functionalities, RuAzNM, is reported. This prodrug has multimodal theranostic properties toward hypoxic cancer cells. Reduction of the azo group in hypoxic cell microenvironments gives rise to the generation of two primary amine products, a free aniline mustard, and the polypyridyl RuNH2 complex. Thus, the aniline mustard triggers generation of reactive oxygen species (ROS) and mtDNA crosslinking. Meanwhile, the resultant biologically benign phosphorescent RuNH2 gives rise to a diagnostic signal and signals activation of the phototherapy. This multimodal therapeutic effect eventually elevates ROS levels, depletes reduced nicotinamide adenine dinucleotide (NADH) and adenosine triphosphate (ATP), and induces mitochondrial membrane damage, mtDNA damage, and ultimately cell apoptosis. This unique strategy allows controlled multimodal theranostics to be realized in hypoxic cells and multicellular spheroids, making RuAzNM a highly selective and effective cancer-cell-selective theranostic agent (IC50  = 2.3 µm for hypoxic HepG2 cancer cells vs 58.2 µm for normoxic THL-3 normal cells). This is the first report of a metal-based compound developed as a multimodal theranostic agent for hypoxia.

Hypobaric hypoxia induced renal injury in rats: Prophylactic amelioration by quercetin supplementation.

The present study aims at assessing the effect of hypobaric hypoxia induced renal damage and associated renal functions in male SD rats. Further, this study was extended to explore the protective efficacy of quercetin in ameliorating the functional impairment in kidneys of rats under hypobaric hypoxia. Rats were exposed to 7620m (25000 ft.) at 25°C ±2 in a simulated hypobaric hypoxia chamber for different time durations (0h,1h, 3h, 6h, 12h, 24h and 48h) in order to optimize the time at which maximum renal damage would occur. The rats were exposed to hypoxia for 12h duration was considered as the optimum time, due to significant increase in oxidative stress (ROS, MDA) and renal metabolites (creatinine, BUN and uric acid) with remarkable reduction (p<0.001) in antioxidants (GSH) in plasma, as compared to other tested durations. Moreover, these findings were in support with the histopathology analysis of renal tissues. For optimum quercetin dose selection, the rats were administered with different doses of quercetin (25mg, 50mg, 100mg and 200mg/Kg BW) for 12h at 7620 m, 25°C ±2, 1h prior to hypoxia exposure. Quercetin 50mg/kg BW was considered as the optimum dose at which significant (p<0.001) reduction in oxidative stress levels followed by reduction in creatinine and BUN levels were obtained in plasma of the rats compared to hypoxia control rats. Quercetin prophylaxis (50mg/kg BW) stabilized the HIF-1α protein expression followed by reduced VEGF protein expression along with reduced levels of LDH (p<0.001) in the kidneys of rats compared to hypoxia control. Histopathological observations further substantiated these findings in reducing the renal tissue injury. The study findings revealed that, quercetin prophylaxis abrogates the possibility of hypobaric hypoxia induced renal injury by reducing the oxidative stress in rats.