Myeloid Nrf2 loss speeds atherosclerosis by boosting inflammation and hindering cell clearance

Atherosclerosis, the slow silent narrowing of the arteries that underlies most heart attacks and strokes, has long been understood as a disease of too much cholesterol and too much inflammation. Now, a new study published in the Journal of Advanced Research adds a surprising twist to that picture, implicating one of the body’s most celebrated antioxidant defense systems in making the disease worse — not by fueling inflammation directly, but by crippling the cellular garbage disposal that keeps dying cells from piling up inside artery walls.

The research, led by Xiaoge Xu, Cuijie Liu, and colleagues under the senior authorship of Huihui Wang and Jingbo Pi, zeroes in on NRF2, a transcription factor formally known as nuclear factor erythroid 2-related factor 2. For decades, NRF2 has been viewed as a molecular guardian: when cells are stressed by oxidants or toxins, NRF2 escapes its cytoplasmic holding protein, migrates into the nucleus, binds to antioxidant response elements in DNA, and switches on a coordinated battery of genes that detoxify electrophiles and neutralize reactive oxygen species. Drug companies have pursued NRF2 activators for everything from neurodegeneration to kidney disease. But the new findings suggest that in macrophages — the immune cells that populate atherosclerotic plaques — keeping NRF2 switched on may be a double-edged sword, and that pharmacologically silencing it in these cells could actually shrink plaques.

The logic of the study begins with a paradox that has nagged the field for years. Global knockout of Nrf2 in atherosclerosis-prone ApoE-deficient mice had been shown to reduce atherosclerotic burden, which seems counterintuitive for a so-called antioxidant factor. Yet when researchers selectively deleted Nrf2 in vascular endothelial cells, or transplanted Nrf2-deficient bone marrow into recipient mice, atherosclerosis got worse, not better. The obvious interpretation was that NRF2 acts in a cell-type-specific fashion — protective in some compartments of the plaque, harmful in others. What remained elusive was the role of NRF2 in macrophages specifically, the cells that constitute the bulk of the lesion and that orchestrate much of its inflammatory chemistry.

To answer that question, the team first combed through single-cell RNA-sequencing datasets from human carotid artery plaques obtained during endarterectomy surgery and from mouse aortas. Across both species, they found that NRF2 and its canonical downstream target genes were upregulated in lesional macrophages, suggesting the pathway is not a bystander but an active participant in plaque biology. They then generated mice lacking Nrf2 specifically in myeloid cells — the lineage that gives rise to monocytes and macrophages — and crossed them onto atherosclerosis-prone backgrounds. The result was unambiguous: loss of Nrf2 in macrophages accelerated plaque development, producing larger lesions with more necrotic cores and a heavier inflammatory fingerprint.

But the mechanism turned out to be something few would have predicted. The dominant hypothesis going in might have centered on oxidative stress: without NRF2, macrophages would accumulate reactive oxygen species, become more inflammatory, and thereby aggravate the lesion. Oxidative stress certainly played a role, but the more striking defect lay elsewhere — in a process called efferocytosis, the specialized phagocytosis by which macrophages recognize, engulf, and digest apoptotic cells. In a healthy artery wall, macrophages are continuously clearing out the cellular debris generated by lipid overload and inflammatory injury. When that clearance fails, apoptotic cells accumulate, rupture into necrotic cores, and spill their contents, amplifying inflammation and destabilizing the plaque. Efferocytosis, in other words, is the plaque’s sanitation department, and its failure is one of the most reliable predictors of dangerous lesion progression.

Efferocytosis is mechanically demanding. To engulf a dying cell, a macrophage must reorganize its actin cytoskeleton, extending membrane ruffles around the corpse and internalizing it in a process that depends on the small GTPases RAC1 and CDC42 and the dynamic remodeling of filamentous actin. When the researchers measured efferocytosis in Nrf2-deficient macrophages, they found it was substantially impaired — the cells could find and bind apoptotic targets, but they fumbled the internalization step. Correspondingly, phosphorylation and activation of RAC1/CDC42 were reduced, and the actin architecture of the cells was disorganized.

The molecular culprit linking NRF2 to this machinery emerged from an integrated analysis combining RNA sequencing, quantitative proteomics, and chromatin immunoprecipitation. That culprit was Myh9, the gene encoding non-muscle myosin heavy chain IIA — the motor protein that, together with actin, generates the contractile force required for a macrophage to physically swallow another cell. The data revealed that NRF2 directly binds to and transcriptionally represses the Myh9 promoter, keeping myosin IIA levels in check. When Nrf2 was deleted, the brakes came off Myh9, myosin IIA accumulated, and — counterintuitively — efferocytosis improved. Restoring the Nrf2–Myh9 axis, or manipulating myosin IIA levels directly, rescued or reproduced the efferocytosis defect, establishing a clear causal chain: NRF2 represses Myh9, myosin IIA enables actin-driven internalization, and internalization capacity determines how efficiently macrophages clear apoptotic debris.

In other words, the famous antioxidant factor was behaving as a brake on a mechanical process, not a chemical one. Macrophages burdened with excess NRF2 were simultaneously more inflammatory and less capable of taking out the cellular trash, a combination that proved particularly toxic inside the plaque microenvironment.

The therapeutic implications crystallized around 4-octyl itaconate, a cell-permeable derivative of itaconate, the metabolite made in large quantities by activated macrophages and known to covalently modify proteins and influence inflammatory signaling. In the study, treatment with 4-octyl itaconate activated NRF2 signaling in macrophages — and consistent with the newly described axis, this activated the Nrf2–Myh9 pathway in a way the authors frame as harnessable therapeutically. The team’s reanalysis of bulk RNA-sequencing data from itaconate-treated macrophages further supported the idea that itaconate derivatives reprogram macrophage dynamics relevant to clearance and inflammation. Positioning macrophage NRF2 activation via 4-octyl itaconate as a candidate strategy, the authors argue that the Nrf2–Myh9–efferocytosis axis represents both a previously unrecognized mechanism of atherogenesis and a druggable node for intervention.

The nuance here matters, and the authors are careful about it. NRF2’s role in atherosclerosis is not simply good or bad; it is compartmentalized. In endothelial cells, where Nrf2 deficiency enhances inflammation and lipid peroxidation, NRF2 is clearly protective. In myeloid cells, the picture the new study paints is of a factor whose activation reshapes macrophage mechanics in ways that can impair efferocytosis, even as the same factor suppresses classical oxidative damage. Any attempt to drug the pathway with systemic NRF2 activators would therefore need to reckon with these divergent, cell-type-specific effects — a caution that echoes a growing theme in precision medicine, where the same transcription factor can be friend in one tissue and foe in another.

What makes the study technically notable is its methodology. The team triangulated across human and murine single-cell transcriptomics, bulk datasets deposited in public repositories, proteomics, and chromatin-binding assays to move from correlation to mechanism. The identification of NRF2’s direct binding at the Myh9 locus, confirmed by ChIP-PCR, and the demonstration that myosin IIA abundance tracks with efferocytosis efficiency, provide the kind of mechanistic granularity that can guide medicinal chemistry. The internalization stage of efferocytosis — long considered the most tractable therapeutic target, since interventions at the earlier “find-me” and “eat-me” stages have been dogged by side effects such as broad inflammation suppression and inappropriate red blood cell engulfment — now has a defined molecular handle.

For the broader field, the work reframes efferocytosis as not merely an immunological phenomenon but a biomechanical one, dependent on the cytoskeletal engine that NRF2, unexpectedly, helps govern. It also adds to mounting evidence that metabolic and antioxidant pathways are deeply entangled with the physical mechanics of immune cells — from actin remodeling to phagocytic capacity — in ways that classical antioxidant-versus-oxidant framing fails to capture. Whether 4-octyl itaconate or related NRF2-modulating compounds can be delivered selectively to plaque macrophages, at doses that tilt the Nrf2–Myh9 balance toward improved clearance without compromising NRF2’s protective roles elsewhere, is the question that will determine whether this axis moves from mouse models to the cardiology clinic. For now, the study offers something the atherosclerosis field has few of: a genuinely new lever, pulled from an old and familiar machine.