RESUMO
Adaptation to hypoxia of the plateau environment has been a focus of scientific research in decades. The geographical distributions of such living environment include the Qinghai-Tibet Plateau, Andean Plateau in South America and Ethiopian Plateau. Over the past century, the unique features of physiological adaptation to high-altitude chronic hypoxia have been documented scientifically. The genetic studies of hypoxic adaptation in the past decade have revealed genetic bases of human high-altitude adaptation, with a close relationship to the hypoxia inducible factor (HIF) pathway and hypoxia response elements (HREs). Interestingly, the genetic pattern of adaptation to hypoxia is not the same among the three plateau populations. Tibetan has developed the best high-altitude adaptation, with modification of the HIF pathway as the key genetic element. Due to the wide range of HIF pathways, HIFs could regulate hundreds of downstream genes and are closely related to various diseases such as cancer, inflammation, ischemia, acute organ damage and infection, etc. The treatment researches of these diseases through HIFs-related regulations have led to the development of stabilizers and inhibitors of HIF pathway. We review here the adaptive responses of the three plateau populations to the hypoxic environment, and the genetic mechanism of HIF and HREs in the different ethnic high-altitude populations. Classes of HIF inhibitors, such as PI3K and/or mammalian target of rapamycin (mTOR) inhibitors, DNA-binding inhibitors, histone deacetylase inhibitors, heat-shock protein 90 inhibitors, cardiac glycosides, transcription inhibitors, topoisomerase inhibitors, and HIF activators including 2-OG mimics, Fe2+ chelators, prolyl hydroxylase (PHD) active-site blockers and CUL2 deneddylators have been presented with the drug examples. In addition, the top 3 chemical-disease and chemical-gene (protein) co-occurrences have been presented from the Pubmed literature search. The review could serve as references for research of hypoxia adaptation and HIF-related diseases.
RESUMO
INTRODUCTION: Anaemia is one of the hallmarks of advanced chronic kidney disease (CKD); it correlates with a lower quality of life and increased cardiovascular risk. Currently its management is based on iron and erythropoiesis-stimulating agents (ESAs) therapy. Given safety issues on ESA therapy and excessive iron use, anaemia management is still suboptimal. Areas covered: The inhibitors of the prolyl-hydroxylases domain (PHD) are oral drugs which activate the hypoxia-inducible factors (HIF) and stimulate the production of endogenous erythropoietin. Roxadustat (FG-4592) is a second-generation PHD inhibitor; it is undergoing now phase-III clinical development. Expert opinion: Phase-II clinical trials have shown that roxadustat is effective and save in the short term in either non-dialysis or dialysis CKD patients. Roxadustat is a chemical drug and thus has the potential of being cheaper than traditional ESAs. Given that the peaks of endogenous EPO are much lower than those observed with traditional ESA, it is possible to speculate the roxadustat (and more in general PHD inhibitors) will be safer than ESA on cardiovascular safety end-points. Considering that HIFs are involved in different pathways, with possible promotion of relevant side effects, their safety must be proven in long-term studies.
