Exposure to High-Altitude Environment is Associated with Drug Transporters Change: miR-873-5p-Mediated Alteration of Function and Expression Levels of Drug Transporters under Hypoxia

Intertwined regulators: hypoxia pathway proteins, microRNAs, and phosphodiesterases in the control of steroidogenesis

Oxygen sensing is of paramount importance for maintaining cellular and systemic homeostasis. In response to diminished oxygen levels, the hypoxia-inducible factors (HIFs) orchestrate various biological processes. These pivotal transcription factors have been identified as key regulators of several biological events. Notably, extensive research from our group and others has demonstrated that HIF1α exerts an inverse regulatory effect on steroidogenesis, leading to the suppression of crucial steroidogenic enzyme expression and a subsequent decrease in steroid levels. These steroid hormones occupy pivotal roles in governing a myriad of physiological processes. Substantial or prolonged fluctuations in steroid levels carry detrimental consequences across multiple organ systems and underlie various pathological conditions, including metabolic and immune disorders. MicroRNAs serve as potent mediators of multifaceted gene regulatory mechanisms, acting as influential epigenetic regulators that modulate a broad spectrum of gene expressions. Concomitantly, phosphodiesterases (PDEs) play a crucial role in governing signal transduction. PDEs meticulously manage intracellular levels of both cAMP and cGMP, along with their respective signaling pathways and downstream targets. Intriguingly, an intricate interplay seems to exist between hypoxia signaling, microRNAs, and PDEs in the regulation of steroidogenesis. This review highlights recent advances in our understanding of the role of microRNAs during hypoxia-driven processes, including steroidogenesis, as well as the possibilities that exist in the application of HIF prolyl hydroxylase (PHD) inhibitors for the modulation of steroidogenesis.

High-altitude-induced alterations in intestinal microbiota

In high-altitude environments characterized by low pressure and oxygen levels, the intestinal microbiota undergoes significant alterations. Whether individuals are subjected to prolonged exposure or acute altitude changes, these conditions lead to shifts in both the diversity and abundance of intestinal microbiota and changes in their composition. While these alterations represent adaptations to high-altitude conditions, they may also pose health risks through certain mechanisms. Changes in the intestinal microbiota induced by high altitudes can compromise the integrity of the intestinal mucosal barrier, resulting in gastrointestinal dysfunction and an increased susceptibility to acute mountain sickness (AMS). Moreover, alterations in the intestinal microbiota have been implicated in the induction or exacerbation of chronic heart failure. Targeted modulation of the intestinal microbiota holds promise in mitigating high-altitude-related cardiac damage. Dietary interventions, such as adopting a high-carbohydrate, high-fiber, low-protein, and low-fat diet, can help regulate the effects of intestinal microbiota and their metabolic byproducts on intestinal health. Additionally, supplementation with probiotics, either through dietary sources or medications, offers a means of modulating the composition of the intestinal microbiota. These interventions may offer beneficial effects in preventing and alleviating AMS following acute exposure to high altitudes.

Exploring tisotumab vedotin in recurrent cervical cancer: A case series including an HPV-independent gastric type adenocarcinoma

Metastatic and recurrent cervical cancer is difficult to treat with limited options following platinum-based chemotherapy. Tisotumab vedotin (TV) is an antibody drug conjugate (ADC) targeted at a tissue factor (TF), which is a cell surface protein that is upregulated in the majority of cervical cancers. Prior clinical trials have demonstrated efficacy of TV in metastatic and recurrent cervical cancer with an objective response rate of 24-26 % with an 8.3 month duration of response. In this case series, we present 3 patients with recurrent or progressive cervical cancer of three different histologies (squamous cell, adenocarcinoma, and human papillomavirus (HPV)-independent gastric type carcinomas). We demonstrate a 100 % complete response rate with average time of complete response of 4.33 months. The duration of response was not reached as none of our patients had a confirmed progression at the time of writing this manuscript, but the mean time since the initiation of treatment was 6.1 months. In concordance with the clinical trials, our patients tolerated TV well although the grade 3 ocular toxicities were higher in our patients compared to prior data. This case series presents data confirming the efficacy and tolerability of TV in patients with recurrent cervical cancer, including an HPV-independent gastric type cervical cancer.

Decoding contextual crosstalk: revealing distinct interactions between non-coding RNAs and unfolded protein response in breast cancer

Breast cancer is significantly influenced by endoplasmic reticulum (ER) stress, impacting both its initiation and progression. When cells experience an accumulation of misfolded or unfolded proteins, they activate the unfolded protein response (UPR) to restore cellular balance. In breast cancer, the UPR is frequently triggered due to challenging conditions within tumors. The UPR has a dual impact on breast cancer. On one hand, it can contribute to tumor growth by enhancing cell survival and resistance to programmed cell death in unfavorable environments. On the other hand, prolonged and severe ER stress can trigger cell death mechanisms, limiting tumor progression. Furthermore, ER stress has been linked to the regulation of non-coding RNAs (ncRNAs) in breast cancer cells. These ncRNAs, including microRNAs (miRNAs) and long non-coding RNAs (lncRNAs), play essential roles in cancer development by influencing gene expression and cellular processes. An improved understanding of how ER stress and ncRNAs interact in breast cancer can potentially lead to new treatment approaches. Modifying specific ncRNAs involved in the ER stress response might interfere with cancer cell survival and induce cell death. Additionally, focusing on UPR-associated proteins that interact with ncRNAs could offer novel therapeutic possibilities. Therefore, this review provides a concise overview of the interconnection between ER stress and ncRNAs in breast cancer, elucidating the nuanced effects of the UPR on cell fate and emphasizing the regulatory roles of ncRNAs in breast cancer progression.

Escherichia coli resistance mechanism AcrAB-TolC efflux pump interactions with commonly used antibiotics: a molecular dynamics study

While antibiotic resistance poses a threat from both Gram-positive bacteria (GPB) and Gram-negative bacteria (GNB), GNB pose a more imminent public health hazard globally. GNB are a threat to growing antibiotic resistance because of the complex makeup of the membrane. The AcrAB-TolC efflux pump is a known resistance mechanism of Escherichia coli (E. coli) cells. This study utilized molecular dynamics modeling to visualize some of the changes occurring at a molecular level when airborne bacteria are exposed to stress and antibiotics. This study was conducted to build upon previous experimental research showing that there is an increase in antibiotic resistance and efflux pump activity when exposed to aerosolization. AcrB and AcrAB-TolC proteins were simulated under standard and increased pressure to compare the effect of aerosolization on the binding to the three different antibiotics (puromycin (PUY), ampicillin (AMP) and sulfamethoxazole-trimethoprim (SXT)) to the AcrB binding site. Analysis such as root-mean-square deviation of atomic positions and root-mean-square fluctuation, the opening of TolC, and the significant molecular mechanics with generalized Born and surface area solvation (MM-GBSA) scores associated with specific ligands were recorded. Resistance in experimental data indicated a relationship between the docking scores and some ligand-protein interactions. Results showed that there was more flexibility in the proteins within simulations conducted under standard pressure for the AcrB protein and the full tripartite complex AcrAB-TolC, showing that increased pressure causes more rigidity. MM-GBSA scores, used to calculate the free energy of ligand-protein binding, did not show a significant change, but interestingly, the strongest MM-GBSA scores were for ligands that moved to another binding pocket and did not result in resistance or opening of the efflux pump. However, the ligand moved from the binding site and did not cause the opening of TolC to increase significantly, whereas PUY and AMP were bound to the binding site for the duration of all simulations. AMP ligands under increased pressure showed the largest change in opening of the TolC efflux pump and aligns with experimental data showing E. coli cells had the most resistance to AMP after aerosolization. These results, in addition to other real-time changes such as OM proteins and mutations of targets within the cell, could be used to delineate and mitigate antibiotic resistance mechanisms.

Altitude effect on Propofol Pharmacokinetics in Rats

BACKGROUND

Propofol is an intravenous agent for clinical anesthesia. As the influence of the hypobaric-hypoxic environment (Qinghai-Tibetan region, altitude: 2800-4300 m, PaO2: 15.1-12.4 kPa) on the metabolism of Propofol is complex, the research results on the metabolic characteristics of Propofol in high-altitude areas remain unclear. This study aimed to investigate the pharmacokinetic characteristics of Propofol in a high-altitude hypoxic environment using animal experiments.

METHODS

Rats were randomly divided into three groups: high-altitude, medium-altitude, and plain groups. The time of disappearance and recovery of the rat righting reflex was recorded as the time of anesthesia induction and awakening, respectively. The plasma concentration of Propofol was determined by gas chromatography-mass spectrometry. A pharmacokinetic analysis software was used to analyze the blood-drug concentrations and obtain the pharmacokinetic parameters.

RESULTS

We observed that when Propofol anesthetizes rats, the anesthesia induction time was shortened, and the recovery time was prolonged with increased altitude. Compared with the plain group, the clearance of Propofol decreased, whereas the half-life, area under the concentration-time curve, peak plasma concentration, and average residence time extension increased.

CONCLUSION

The pharmacokinetic characteristics of Propofol are significantly altered in high-altitude hypoxic environments.

New strategy for rational use of antihypertensive drugs in clinical practice in high-altitude hypoxic environments

High-altitude hypoxic environments have critical implications on cardiovascular system function as well as blood pressure regulation. Such environments place patients with hypertension at risk by activating the sympathetic nervous system, which leads to an increase in blood pressure. In addition, the high-altitude hypoxic environment alters the in vivo metabolism and antihypertensive effects of antihypertensive drugs, which changes the activity and expression of drug-metabolizing enzymes and drug transporters. The present study reviewed the pharmacodynamics and pharmacokinetics of antihypertensive drugs and its effects on patients with hypertension in a high-altitude hypoxic environment. It also proposes a new strategy for the rational use of antihypertensive drugs in clinical practice in high-altitude hypoxic environments. The increase in blood pressure on exposure to a high-altitude hypoxic environment was mainly dependent on increased sympathetic nervous system activity. Blood pressure also increased proportionally to altitude, whilst ambulatory blood pressure increased more than conventional blood pressure, especially at night. High-altitude hypoxia can reduce the activities and expression of drug-metabolizing enzymes, such as CYP1A1, CYP1A2, CYP3A1, and CYP2E1, while increasing those of CYP2D1, CYP2D6, and CYP3A6. Drug transporter changes were related to tissue type, hypoxic degree, and hypoxic exposure time. Furthermore, the effects of high-altitude hypoxia on drug-metabolism enzymes and transporters altered drug pharmacokinetics, causing changes in pharmacodynamic responses. These findings suggest that high-altitude hypoxic environments affect the blood pressure, pharmacokinetics, and pharmacodynamics of antihypertensive drugs. The optimal hypertension treatment plan and safe and effective medication strategy should be formulated considering high-altitude hypoxic environments.

Hypoxia-driven ncRNAs in breast cancer

Low oxygen tension, or hypoxia is the driving force behind tumor aggressiveness, leading to therapy resistance, metastasis, and stemness in solid cancers including breast cancer, which now stands as the leading cause of cancer-related mortality in women. With the great advancements in exploring the regulatory roles of the non-coding genome in recent years, the wide spectrum of hypoxia-responsive genome is not limited to just protein-coding genes but also includes multiple types of non-coding RNAs, such as micro RNAs, long non-coding RNAs, and circular RNAs. Over the years, these hypoxia-responsive non-coding molecules have been greatly implicated in breast cancer. Hypoxia drives the expression of these non-coding RNAs as upstream modulators and downstream effectors of hypoxia inducible factor signaling in the favor of breast cancer through a myriad of molecular mechanisms. These non-coding RNAs then contribute in orchestrating aggressive hypoxic tumor environment and regulate cancer associated cellular processes such as proliferation, evasion of apoptotic death, extracellular matrix remodeling, angiogenesis, migration, invasion, epithelial-to-mesenchymal transition, metastasis, therapy resistance, stemness, and evasion of the immune system in breast cancer. In addition, the interplay between hypoxia-driven non-coding RNAs as well as feedback and feedforward loops between these ncRNAs and HIFs further contribute to breast cancer progression. Although the current clinical implications of hypoxia-driven non-coding RNAs are limited to prognostics and diagnostics in breast cancer, extensive explorations have established some of these hypoxia-driven non-coding RNAs as promising targets to treat aggressive breast cancers, and future scientific endeavors hold great promise in targeting hypoxia-driven ncRNAs at clinics to treat breast cancer and limit global cancer burden.

Relationship between blood-brain barrier changes and drug metabolism under high-altitude hypoxia: obstacle or opportunity for drug transport?

The blood-brain barrier is essential for maintaining the stability of the central nervous system and is also crucial for regulating drug metabolism, changes of blood-brain barrier's structure and function can influence how drugs are delivered to the brain. In high-altitude hypoxia, the central nervous system's function is drastically altered, which can cause disease and modify the metabolism of drugs in vivo. Changes in the structure and function of the blood-brain barrier and the transport of the drug across the blood-brain barrier under high-altitude hypoxia, are regulated by changes in brain microvascular endothelial cells, astrocytes, and pericytes, either regulated by drug metabolism factors such as drug transporters and drug-metabolizing enzymes. This article aims to review the effects of high-altitude hypoxia on the structure and function of the blood-brain barrier as well as the effects of changes in the blood-brain barrier on drug metabolism. We also hypothesized and explore the regulation and potential mechanisms of the blood-brain barrier and associated pathways, such as transcription factors, inflammatory factors, and nuclear receptors, in regulating drug transport under high-altitude hypoxia.

Changes in the Gut Microbiota of Rats in High-Altitude Hypoxic Environments

This study was conducted to investigate the effects of high-altitude hypoxic environments on the gut microbiota. Male Sprague-Dawley rats were randomly divided into three groups, namely, the plain, moderate-altitude hypoxic, and high-altitude hypoxic groups. On the 3rd, 7th, 15th, and 30th days of exposure, fecal samples were collected and analyzed via 16S rRNA gene sequencing technology. Fecal microbiota transplantation (FMT) experiments were also performed. The results showed significant differences between the gut microbiota structure and diversity of rats in the high-altitude hypoxic group and those of rats in the other groups. Further, compared with that of rats in the plain group, the gut microbiota of rats in the two hypoxic groups showed the most significant changes on day 7. Furthermore, the gut microbiota of the rats in the FMT groups exhibited changes and became increasingly similar to those of the rats in the hypoxic groups. We also identified the phylum Firmicutes, genus Akkermansia, and genus Lactobacillus as the core microbiota under hypoxic conditions. Phenotypic analysis indicated a decrease in the proportion of aerobic bacteria and an increase in that of anaerobic bacteria, possibly owing to the high-altitude hypoxic environment. Additionally, functional analysis showed significant differences between the different groups with respect to different metabolic pathways, including carbohydrate metabolism, energy metabolism, glycan biosynthesis, and metabolism. These findings indicated significant changes in gut microbiota structure and diversity under high-altitude hypoxia, establishing a foundation for further research on the pathogenesis and development of diseases, as well as drug metabolism, under high-altitude hypoxia. IMPORTANCE In this study, we investigated the effects of high-altitude hypoxic environments with low oxygen levels on the gut microbiota characteristics of rats. We observed that high-altitude hypoxia is an important environmental factor that can affect gut microbiota structure and diversity, thereby affecting homeostasis in the host intestinal environment. These findings provide a basis for further studies on disease initiation and development, as well as drug metabolism, in high-altitude hypoxic environments.

High-altitude Hypoxia Influences the Activities of the Drug-Metabolizing Enzyme CYP3A1 and the Pharmacokinetics of Four Cardiovascular System Drugs

(1) Background: High-altitude hypoxia has been shown to affect the pharmacokinetic properties of drugs. Although there is a high incidence of cardiovascular disease among individuals living in high-altitude areas, studies on the effect of high-altitude hypoxia on the pharmacokinetic properties of cardiovascular drugs are limited. (2) Methods: The aim of this study was to evaluate the pharmacokinetics of nifedipine, bosentan, simvastatin, sildenafil, and their respective main metabolites, dehydronifedipine, hydroxybosentan, simvastatin hydroxy acid, and N-desmethyl sildenafil, in rats exposed to high-altitude hypoxia. Additionally, the protein and mRNA expression of cytochrome P450 3A1 (CYP3A1), a drug-metabolizing enzyme, were examined. (3) Results: There were significant changes in the pharmacokinetic properties of the drugs in rats exposed to high-altitude hypoxia, as evidenced by an increase in the area under the curve (AUC) and the half-life (t_1/2z) and a decrease in total plasma clearance (CL_z/F). However, most of these changes were reversed when the rats returned to a normoxic environment. Additionally, there was a significant decrease in CYP3A1 expression in rats exposed to high-altitude hypoxia at both the protein and mRNA levels. (4) Conclusions: High-altitude hypoxia suppressed the metabolism of the drugs, indicating that the pharmacokinetics of the drugs should be re-examined, and the optimal dose should be reassessed in patients living in high-altitude areas.

Indole-3-propionic Acid Attenuates HI-Related Blood-Brain Barrier Injury in Neonatal Rats by Modulating the PXR Signaling Pathway

The blood-brain barrier (BBB) is an important physiological barrier of the human body contributing to maintaining brain homeostasis and normal function. Hypoxic-ischemic (HI)-related brain injury is one of the main causes of neonatal acute morbidity and chronic disability. The previous research of our group confirmed that there was serious BBB destruction during HI brain injury. However, at present, the protection strategy of BBB is very limited, and further research on the protection mechanism is warranted. Indole-3-propionic acid (IPA) is a bacterial metabolism with anti-inflammatory and antioxidant properties, having neuroprotective effects and protective effects on the mucosal barrier. However, the role of IPA in BBB is not clear. In this research, we demonstrated the protective effect of IPA on BBB disruption from HI brain injury and hypothesized that it involves the amelioration of inflammation, oxidative stress, and MMP activation, thereby inhibiting apoptosis of rat brain microvascular endothelial cells (rBMECs). We demonstrated that expression levels of several inflammatory markers, including iNOS, TNF-α, IL-6, and IL-1β, were significantly increased from HI damage or OGD injury. However, IPA treatment inhibited the increase significantly. Moreover, we demonstrated that IPA reduced intracellular ROS levels and MMP activation in rBMECs from OGD injury. Further research on the underlying detailed molecular mechanisms suggested that IPA attenuates inflammation by inhibiting NF-κB signaling. Finally, we investigated the mechanism of the relationship between PXR activation and NF-κB inhibition. The results suggested overexpression of PXR in rBMECs could significantly counteract the decrease of junction proteins and downregulate the increased p-IκB-α and p-NF-κB from OGD injury. However, the protective effects of IPA were reversed by antagonists of the PXR. Taken together, IPA might mitigate HI-induced damage of the BBB and the protective effect may be exerted through modulating the PXR signaling pathway.

Regulation of CYP450 and drug transporter mediated by gut microbiota under high-altitude hypoxia

Hypoxia, an essential feature of high-altitude environments, has a significant effect on drug metabolism. The hypoxia–gut microbiota–CYP450/drug transporter axis is emerging as a vital factor in drug metabolism. However, the mechanisms through which the gut microbiota mediates the regulation of CYP450/drug transporters under high-altitude hypoxia have not been well defined. In this study, we investigated the mechanisms underlying gut microbial changes in response to hypoxia. We compared 16S ribosomal RNA gene sequences of the gut microbiota from plain and hypoxic rats. As a result, we observed an altered gut microbial diversity and composition in rats under hypoxia. Our findings show that dysregulated gut microbiota changes CYP3A1 and MDR1 expressions in high-altitude hypoxic environments. Thus, our study reveals a novel mechanism underlying the functioning of the hypoxia–gut microbiota–CYP450/drug transporter axis.