Hypoxia-Driven Gene Switches Emerge as Drug Targets to Shield the Injured Heart

When a coronary artery is suddenly blocked, the heart muscle downstream is starved of oxygen, and the therapeutic irony of modern cardiology begins: restoring blood flow, the only definitive treatment for a heart attack, can itself inflict further damage. This phenomenon, known as myocardial ischaemia–reperfusion injury, arises because the abrupt reintroduction of oxygen to oxygen-deprived tissue triggers a redox imbalance, surges of mitochondrial reactive oxygen species, and a cascade of inflammatory and cell-death programmes. A comprehensive review published in Nature Reviews Cardiology by Cong Luo, Tao Li, Jihoon Tak, Matthew DeBerge, Kuang-Lei Tsai, Holger K. Eltzschig and colleagues now synthesizes three decades of evidence showing that hypoxia-inducible factors, or HIFs, sit at the centre of the heart’s adaptive response to this double insult, and that these transcription factors represent an unusually actionable drug target for cardioprotection.

The molecular logic of the HIF pathway is elegant. Under normal oxygen tensions, the alpha subunits of HIF, chiefly HIF1α and HIF2α, are continuously marked for destruction by prolyl hydroxylase domain enzymes, EGLN1 and EGLN2, which require molecular oxygen to hydroxylate specific proline residues. Once hydroxylated, the alpha subunits are captured by the von Hippel–Lindau ubiquitin ligase complex and rapidly degraded by the proteasome. When oxygen falls during ischaemia, hydroxylation stalls, HIFα accumulates within minutes, translocates to the nucleus, dimerizes with the constitutive ARNT subunit, and binds hypoxia response elements to switch on hundreds of hypoxia-responsive genes. Importantly, the review highlights that during reperfusion HIFs can remain stabilized even after oxygen returns, because ischaemic accumulation of Krebs cycle metabolites such as succinate inhibits prolyl hydroxylase activity, providing oxygen-independent stabilization that prolongs the transcriptional response precisely when injury is peaking.

Among the best-characterized HIF-dependent programmes is metabolic reprogramming. HIF1α induces pyruvate dehydrogenase kinase, which shunts pyruvate away from oxygen-hungry mitochondrial oxidation and towards glycolysis, a metabolic switch that allows cardiomyocytes to generate ATP with far less oxygen consumption. Experimental work shows that HIF1α also targets the mitochondrial permeability transition pore, a critical gatekeeper of reperfusion-induced cell death, thereby blunting the lethal calcium and reactive-oxygen-driven opening of this pore when blood flow resumes. More recently, glycolytic flux has been linked to epigenetic regulation through histone lactylation, in which lactate-derived modification of histones activates reparative gene programmes after infarction, suggesting that the metabolic shift driven by HIFs does more than produce energy; it rewires the gene-expression landscape of the injured heart toward survival and repair.

A second major axis of HIF-mediated cardioprotection involves extracellular adenosine signalling. Hypoxia-inducible factors upregulate ecto-5′-nucleotidase, or CD73, the enzyme that converts released AMP into adenosine, while simultaneously repressing adenosine kinase and equilibrative nucleoside transporters, thereby boosting extracellular adenosine concentrations at the very moment the heart needs them. Adenosine acting through A2A and A2B receptors on immune cells, endothelium and cardiomyocytes dampens inflammation, preserves microvascular barrier integrity and promotes tolerance to ischaemic stress. The review also details HIF2α-dependent induction of amphiregulin, a ligand that engages epidermal growth factor receptor pathways to reduce myocardial injury, and transcription-independent induction of ERBB1, illustrating that HIFs protect the heart through both classical gene transcription and rapid non-genomic mechanisms.

The two major HIF alpha isoforms are not interchangeable. HIF1α predominantly drives core hypoxic metabolism genes and is the dominant isoform in cardiomyocytes during acute ischaemia, whereas HIF2α has more restricted cell-type expression, prominent in endothelial cells, macrophages and stromal populations, and controls a partly distinct transcriptional portfolio involving growth factor signalling, angiogenesis, macrophage polarization and microRNA induction. Gene-targeting studies show that deleting HIF1α in cardiomyocytes abolishes preconditioning-induced protection, while HIF2α deletion in myeloid or endothelial compartments separately compromises repair and barrier function. The review emphasizes that this isoform specificity carries a cautionary message for drug development: blanket HIF activation may simultaneously trigger beneficial and detrimental programmes depending on which cell types and which isoforms are engaged, and precise tuning of prolyl hydroxylase inhibition may be key to maximizing benefit.

Perhaps the most compelling clinical framing of the HIF story comes from ischaemic preconditioning and its clinically translatable cousin, remote ischaemic conditioning. The landmark discovery that brief, repeated episodes of ischaemia dramatically protect the heart against subsequent prolonged ischaemia established that the myocardium possesses an endogenous survival programme waiting to be triggered. Multiple studies now demonstrate that HIF1 is required for this protection: mice with partial HIF1α deficiency lose preconditioning-induced cardioprotection entirely, and HIF1 is also indispensable for remote preconditioning, in which transient limb ischaemia protects the heart through circulating humoral and neural signals. Mechanistically, remote conditioning engages EGLN1 inhibition and metabolite rerouting, and downstream protection involves adenosine signalling, interleukin-10 induction and HIF-dependent metabolic adaptation, providing a molecular explanation for one of cardiology’s most studied protective interventions.

The review also weaves in a surprising temporal dimension: the circadian clock. Clinical observations spanning decades show that the incidence and severity of myocardial infarction vary by time of day, and recent work demonstrates that the clock component BMAL1 can partner with HIF2α to form a functional heterodimer that modulates circadian variation in myocardial injury susceptibility. The PER2 protein, stabilized through adenosine A2B receptor signalling, promotes a HIF-dependent metabolic switch crucial for myocardial adaptation to ischaemia, while rhythmic oxygen fluctuations themselves reset circadian clocks through HIF1α. This reciprocal crosstalk between hypoxia sensing and circadian biology suggests that the timing of a heart attack, of cardiac surgery, or even of drug administration could meaningfully influence how much myocardium survives, opening the emerging field of circadian cardioprotective medicine.

What elevates this basic science into immediate translational territory is the fact that pharmacological HIF stabilizers already exist and are in clinical use. Oral inhibitors of HIF prolyl hydroxylases, including roxadustat, vadadustat, daprodustat, molidustat and enarodustat, have been approved or evaluated extensively for treating renal anaemia, because stabilizing HIF stimulates erythropoietin production and iron utilization. The review argues that this existing clinical infrastructure provides a ready-made pathway for evaluating HIF activation as a cardioprotective strategy in myocardial infarction, cardiac surgery and myocardial injury after non-cardiac surgery, the latter being a common and under-recognized cause of perioperative morbidity. Preclinical studies support this optimism: roxadustat markedly reduces myocardial ischaemia–reperfusion injury in mouse models, attenuates adverse remodelling after infarction, and protects diabetic myocardium by upregulating HIF1α-dependent antioxidant programmes.

The authors are careful to note the caveats. Chronic HIF activation carries risks, including pro-angiogenic effects relevant to cancer biology, erythrocytosis, and context-dependent inflammatory consequences, as illustrated by HIF2α gain-of-function syndromes and by the oncology use of the HIF2 antagonist belzutifan. Cardiovascular safety signals from the anaemia trials have been scrutinized, and the review stresses that acute, time-limited, precisely dosed HIF activation around the window of ischaemia and reperfusion is the cardioprotective concept, distinct from indefinite chronic therapy. Nevertheless, the convergence of mechanistic depth, isoform and cell-type knowledge, clinically validated small molecules and proven preconditioning paradigms positions HIF biology as one of the most plausible near-term routes to a therapy that has eluded cardiology for decades: reliably limiting the damage that both the blockage and the rescue inflict on the human heart.

The epidemiological backdrop gives this translational urgency its weight. Ischaemic heart disease remains the leading cause of death worldwide, and analyses from the Global Burden of Disease project document its continued expansion as populations age, while economic studies in the European Union attribute tens of billions of euros in annual costs to cardiovascular disease. Within surgical practice, elevated high-sensitivity troponin after non-cardiac surgery is associated with increased thirty-day mortality, making perioperative myocardial injury a target population in which a short-acting cardioprotective drug could be deployed prophylactically, before the ischaemic insult even occurs.

Historically, the field owes much to the foundational work of Gregg Semenza and colleagues, who in the early 1990s demonstrated cell-type-specific, hypoxia-inducible expression of the erythropoietin gene and subsequently purified hypoxia-inducible factor 1 as an oxygen-regulated heterodimer. The mechanistic resolution came in 2001, when parallel studies showed that oxygen sensing is achieved through prolyl hydroxylation of HIFα and its recognition by the von Hippel–Lindau ubiquitin ligase machinery, a discovery recognized with the 2019 Nobel Prize in Physiology or Medicine shared by Semenza and Peter Ratcliffe, alongside William Kaelin. That oxygen-sensing pathway is precisely what today’s oral prolyl hydroxylase inhibitors exploit.

The preconditioning literature adds an instructive dose of realism. Despite decades of robust animal data, attempts to translate conditioning paradigms into routine clinical practice have yielded mixed results, often attributed to species differences, comorbidities such as diabetes that blunt endogenous protective signalling, and concomitant medications including statins and opioids that engage overlapping pathways. The HIF framework offers a potential remedy: rather than relying on the body’s variable endogenous trigger, pharmacological stabilization of HIF could impose the protective programme directly, and preclinical work in diabetic models suggests that HIF1α-dependent antioxidant induction may restore protection where conditioning fails.

For clinicians watching this space, the near-term research agenda is discernible. The review points toward carefully designed trials of acute, time-limited HIF activation in the peri-infarct and perioperative windows, with attention to dosing, timing relative to reperfusion, and isoform-selective engagement. Whether the anaemia drugs can be repurposed at cardioprotective doses without erythrocytosis or vascular risks will determine if this long-sought therapy finally reaches the bedside.

Subject of Research: The role of hypoxia-inducible factors in myocardial ischaemia–reperfusion injury and cardioprotection

Article Title: The role of hypoxia-inducible factors in myocardial ischaemia–reperfusion injury and cardioprotection

Article References: Luo, C., Li, T., Tak, J., DeBerge, M., Tsai, K.-L., & Eltzschig, H. K. (2026). The role of hypoxia-inducible factors in myocardial ischaemia–reperfusion injury and cardioprotection. Nature Reviews Cardiology. https://doi.org/10.1038/s41569-026-01339-y

Image Credits: AI Generated

DOI: 10.1038/s41569-026-01339-y

Keywords: hypoxia-inducible factors, myocardial ischaemia-reperfusion injury, cardioprotection, HIF1α, HIF2α, prolyl hydroxylase inhibitors, ischemic preconditioning, adenosine signaling, glycolytic metabolism, circadian rhythm, roxadustat, heart attack