The investigation began with an unusually direct experimental design. The team collected twenty-one esophageal cancer samples from patients who had either received anti-PD-1 treatment or had not, and subjected them to single-cell RNA sequencing, a technique that profiles gene expression in individual cells rather than in bulk tissue. This allowed the researchers to see, cell by cell, what changed inside tumors when PD-1 blockade was applied. What emerged was striking: after anti-PD-1 therapy, the tumor cells showed a marked decrease in their intrinsic expression of SIRPα. The finding suggested that SIRPα-high tumor cells might be the ones being eliminated by successful immunotherapy, while cells that retained or re-established the protein could survive and dominate the tumor after treatment.

To test whether SIRPα levels actually matter for patients, the researchers assembled a much larger clinical cohort: 322 esophageal cancer samples and 161 adjacent paracancerous tissue samples. Across this collection, high SIRPα expression correlated with poor prognosis and worse outcomes from therapy. In other words, tumors rich in SIRPα were not only more aggressive but also less responsive to the immunotherapies designed to defeat them. This epidemiological signal, combined with the single-cell data, positioned SIRPα as a candidate mediator of anti-PD-1 resistance rather than a mere bystander protein whose expression happens to change during treatment.

Having established the correlation, the team turned to the machinery behind it. Using chromatin immunoprecipitation followed by quantitative polymerase chain reaction, dual luciferase reporter assays, co-immunoprecipitation, western blotting, and mass spectrometry, they traced the regulatory circuitry that controls SIRPα in esophageal cancer cells. Their experiments identified the transcription factor Yin-Yang 1, known as YY1, as a direct activator of SIRPα expression. YY1 binds to the SIRPα gene and switches it on, placing SIRPα under the control of a transcriptional program that the tumor itself orchestrates. This was a critical clarification, because SIRPα had previously been studied mainly as an immune checkpoint protein on macrophages, where it recognizes the don’t-eat-me signal CD47 and prevents phagocytosis of cancer cells. The new work shifts attention to SIRPα as a molecule the tumor cells manufacture for their own benefit.

The first mechanism of resistance that the researchers uncovered concerns tumor growth. Through what they describe as the YY1–SIRPα–PI3K/AKT pathway, SIRPα regulates the level of caspase, the family of enzymes that executes programmed cell death. By modulating caspase signaling, SIRPα inhibits apoptosis, the suicide program that damaged or stressed cells are supposed to activate. The consequence is that SIRPα-high tumor cells survive where they should die, continue dividing, and gradually form dominant clones that take over the tumor. When anti-PD-1 therapy arrives, it faces a tumor already organized around a population of hard-to-kill, rapidly proliferating cells. Genetic experiments in which the researchers knocked down SIRPα confirmed the point: lowering SIRPα levels prevented tumor proliferation and reduced recurrence, demonstrating that the protein is not merely associated with aggressive disease but functionally drives it.

The second mechanism is immunological, and it is perhaps the more surprising of the two. The researchers showed that SIRPα present on the surface of tumor cells directly inhibits the killing activity of T cells and drives them into a state of exhaustion, in which the immune cells lose their ability to mount an effective attack. Exhausted T cells express inhibitory receptors, produce less interferon-gamma, and generally behave as if they have been worn down by chronic stimulation. Crucially, the team found that this T-cell suppression operates through a CD47-independent pathway. That distinction matters enormously for drug development, because most existing efforts to target the CD47–SIRPα axis, such as antibodies that block CD47 to unleash macrophages, assume that SIRPα’s effects depend on its interaction with CD47. A CD47-independent mechanism means that simply blocking CD47 would not neutralize what SIRPα is doing to T cells, and that SIRPα itself must be targeted directly.

To test these mechanisms in a living system, the researchers turned to NCG mice, an immunodeficient strain that can be humanized to carry a functional human immune system. Using an adeno-associated virus of serotype 9, or AAV9, carrying a short hairpin RNA against SIRPα, they delivered a gene-silencing therapy to established esophageal tumors and then combined it with pembrolizumab, a clinically approved anti-PD-1 antibody. The results were decisive. Coadministration of the SIRPα-targeted therapy and anti-PD-1 treatment produced a significantly greater antitumor effect than either monotherapy alone. The combination essentially removed the two legs on which resistance stands: suppressing SIRPα weakened the tumor’s proliferative dominance and relieved T-cell exhaustion, allowing the PD-1 blockade to work on a reinvigorated immune response rather than against a wall of suppression.

The technical breadth of the study deserves emphasis, because each method answered a different question. Single-cell RNA sequencing revealed which cells expressed SIRPα and how expression shifted after therapy. The large clinical cohort connected expression to patient outcomes. ChIP-qPCR and reporter assays established YY1 as the upstream transcriptional driver. Co-immunoprecipitation and mass spectrometry mapped the protein interactions downstream of SIRPα. Co-culture experiments, flow cytometry, and tumor-killing assays demonstrated the functional impact of SIRPα on T-cell behavior, measuring how effectively immune cells destroyed tumor cells when SIRPα was present or removed. Finally, the humanized mouse experiments provided the translational proof of concept, showing that a targeted intervention against SIRPα could be delivered in vivo and could convert a nonresponsive tumor into one that responds to checkpoint blockade.

The implications for patients with esophageal cancer are considerable, but the authors are careful to frame them as a starting point rather than a finished therapy. As they note in their conclusions, while the findings suggest SIRPα as a potential therapeutic target, the clinical relevance and safety of intervening against it require rigorous evaluation in future human trials. Several questions remain open. It is not yet known which patients would benefit most from SIRPα-directed treatment, whether SIRPα levels in tumor biopsies could serve as a predictive biomarker for anti-PD-1 response, or what side effects might arise from interfering with a protein that also functions on immune cells. The AAV9 delivery approach used in mice would also need substantial development before it could be applied in humans. Nevertheless, the study provides something that has been missing in esophageal oncology: a coherent, mechanistically grounded account of why PD-1 blockade so often fails, and a concrete strategy, pairing SIRPα suppression with existing immunotherapy, for overcoming that failure. If the findings translate to the clinic, the YY1–SIRPα axis could become a focal point for the next generation of combinatorial immunotherapy in one of the world’s most lethal cancers.

Subject of Research: Tumor-intrinsic SIRPα-mediated resistance to anti-PD-1 immunotherapy in esophageal cancer

Article Title: Tumor-intrinsic SIRPα drives anti-PD-1 resistance in esophageal cancer by coordinating proliferative dominance and T-cell exhaustion: A target for combinatorial immunotherapy

Article References: Tang, X.-Y., Pan, J.-Y., Zhang, X.-X., Du, W.-G., Zhao, X.-J., Dong, H., Zhou, Y.-L., Li, M.-C., Zhang, R.-Z., Shu, C., Shen, Y., Feng, Z.-B., Xu, X.-L., Gao, Y., Yan, X.-L., Yan, B., Ma, N., & Zhao, J.-B. (2026). Tumor-intrinsic SIRPα drives anti-PD-1 resistance in esophageal cancer by coordinating proliferative dominance and T-cell exhaustion: A target for combinatorial immunotherapy. BMC Medicine. https://doi.org/10.1186/s12916-026-05213-z

Image Credits: AI Generated

DOI: 10.1186/s12916-026-05213-z

Keywords: esophageal cancer, SIRPα, anti-PD-1 resistance, immunotherapy, T-cell exhaustion, YY1, PI3K/AKT, CD47-independent pathway, pembrolizumab, tumor microenvironment, single-cell RNA sequencing, combinatorial therapy

Efferocytosis unfolds in coordinated stages. Dying cells first release find-me signals, soluble messengers such as nucleotides and lipids that lure phagocytes toward the site of death. Once in contact, the phagocyte probes the surface of the apoptotic cell for eat-me signals, most prominently phosphatidylserine, a phospholipid that flips from the inner leaflet to the outer leaflet of the membrane as a cell dies. Receptors on the macrophage surface engage these markers and trigger cytoskeletal remodeling, engulfment and degradation of the corpse inside a phagolysosome. Crucially, efferocytosis is immunologically silent or even anti-inflammatory: it drives the production of anti-inflammatory mediators such as interleukin-10 and transforming growth factor-beta, and it promotes the resolution phase that follows any inflammatory insult. When the process falters, apoptotic cells progress to secondary necrosis, spilling their contents and sustaining a chronic inflammatory fire that damages surrounding tissue.

CD47 sits at the heart of the regulatory machinery that decides whether engulfment proceeds. This widely expressed cell-surface glycoprotein binds to signal regulatory protein alpha, SIRPα, on macrophages and delivers what immunologists call the classic don’t eat me signal. When CD47 engages SIRPα, the receptor’s cytoplasmic tail recruits tyrosine phosphatases SHP-1 and SHP-2, which dephosphorylate the signaling intermediates needed for phagocytic cup formation. In effect, the macrophage’s engulfment machinery is switched off before it can engage. The system evolved as a self-preservation mechanism: healthy cells display abundant CD47 and are spared from accidental destruction. The landmark work of Oldenborg and colleagues showed that CD47 acts as a marker of self on red blood cells, and that erythrocytes lacking the protein are rapidly cleared from circulation. In this sense, CD47 functions as a passport presented at the macrophage checkpoint.

The trouble begins when pathological cells hijack the passport. Under disease conditions, abnormally high CD47 expression allows abnormal cells to evade immune clearance, and the CD47/SIRPα axis has consequently emerged as a major immune checkpoint in the regulation of efferocytosis. In tumors, the evidence is striking. Majeti and colleagues demonstrated in 2009 that CD47 is upregulated on acute myeloid leukemia stem cells and serves as an adverse prognostic factor, allowing malignant cells to slip past macrophage surveillance. Subsequent studies have traced the mechanisms of this overexpression in remarkable detail. The oncogene MYC directly regulates CD47 transcription alongside PD-L1, coupling proliferative drive with immune evasion. In breast cancer, a CD47-associated super-enhancer links pro-inflammatory signaling to CD47 upregulation, while NF-kappaB signaling drives CD47 overexpression in radioresistant HER2-positive cells. In glioblastoma, EGFR-induced phosphorylation of CD47 blocks its ubiquitination and degradation, stabilizing the protein on the tumor cell surface.

Therapeutically, the don’t eat me signal has become one of the most actively pursued targets in cancer immunology. Anti-CD47 antibodies such as magrolimab and evorpacept block the CD47-SIRPα interaction, releasing the brakes on macrophage phagocytosis and enabling tumor cell engulfment. Clinical studies in hematologic malignancies have combined CD47 blockade with azacitidine and venetoclax in acute myeloid leukemia, and with rituximab and lenalidomide in non-Hodgkin lymphoma, with phase 1 trials reporting encouraging activity. In solid tumors, the strategy is more nuanced. Glioblastoma research showed that microglia, the resident macrophages of the brain, act as effector cells when the CD47-SIRPα axis is disrupted, and that irradiation or temozolomide chemotherapy can sensitize tumors to anti-CD47 treatment. Recent work has explored dual checkpoint blockade, oncolytic viruses that downregulate CD47, HDAC inhibitors that enhance phagocytosis, and histone demethylase inhibitors that suppress CD47 expression in breast cancer, all aimed at amplifying the macrophage attack on malignant cells.

Yet the same pathway that protects tumors also drives cardiovascular disease, and here the therapeutic logic inverts. In atherosclerosis, efferocytosis is essential for clearing apoptotic foam cells within arterial plaques. When macrophages fail to engulf these dying cells, the corpses undergo secondary necrosis and form the necrotic cores that destabilize plaques and precipitate heart attacks. CD47 is upregulated in advanced lesions, partly through noncoding RNA circuits such as the lncRNA MIAT sponge that sequesters miR-149-5p and lifts CD47 expression. Kojima and colleagues reported in Nature that CD47-blocking antibodies restore phagocytosis and prevent atherosclerosis progression in mice, and subsequent studies showed that smooth muscle cell-specific CD47 deletion suppresses the disease. Age-related impairments in efferocytosis and autophagy further hinder plaque regression, and recent preclinical work suggests CD47 blockade can reprogram the monocyte-macrophage axis to promote inflammation resolution in atherosclerotic vessels.

Researchers are now engineering delivery systems to exploit this biology with precision. Biomimetic nanoparticles that boost efferocytosis through dual-pathway regulation are being developed for atherosclerosis therapy and imaging, while ROS-responsive liposomes combine CD47 blockade with lipid metabolism regulation to target inflamed plaques. Similar nanotechnology strategies are being applied to the heart: after myocardial infarction, enhanced efferocytosis of dying cardiomyocytes is linked to tissue repair, and acute CD47 blockade during ischemic reperfusion has been shown to enhance phagocytosis-associated cardiac repair in experimental models. Biomimetic nano-degraders targeting the CD47-SIRPα checkpoint and cardiac-homing nanoparticles that suppress SHP-1 are being tested as ways to promote efferocytosis and dampen the inflammation that otherwise remodels and weakens the infarcted heart.

In the nervous system, the story becomes more complicated, because CD47 plays opposing roles depending on context. Microglia, the brain’s phagocytes, must clear myelin debris, dead neurons and protein aggregates, and CD47 on myelin interacts with SIRPα to downregulate this phagocytosis, potentially impeding repair in multiple sclerosis. In experimental autoimmune encephalomyelitis, a model of multiple sclerosis, CD47 antibody blockade suppressed microglia-dependent phagocytosis and impaired recovery, illustrating the pathway’s Janus-like character in autoimmune brain inflammation. In intracerebral hemorrhage, however, CD47-blocking antibodies accelerated hematoma clearance and alleviated brain injury, including in aged animals with intraventricular hemorrhage. Emerging studies also link CD47 to microglial phagocytosis defects in autism models and to synaptic pruning in Alzheimer’s disease, where microglial clearance of amyloid deposits is a central therapeutic goal, and compounds such as luteolin have been reported to promote phagocytosis by inhibiting CD47 pyroglutamation.

The review by Wang and colleagues makes clear that CD47-mediated efferocytosis is not a simple on-off switch but a finely balanced checkpoint whose manipulation must be tailored to each disease. Blocking CD47 unleashes macrophages against tumors and atherosclerotic debris, yet the same intervention can complicate recovery in some autoimmune neuroinflammatory settings, and anemia caused by CD47’s role on red blood cells remains a safety consideration in clinical trials. The next generation of approaches, including engineered antibodies, nanoparticle delivery, combination regimens with chemotherapy, radiotherapy and other immunotherapies, and drugs that modulate CD47 expression epigenetically, aims to sharpen this therapeutic window. As the molecular circuitry of the don’t eat me signal continues to be mapped, the prospect of deliberately tuning cell clearance to resolve inflammation, dissolve plaques and expose tumors to immune destruction is moving steadily from the laboratory toward the clinic.

Subject of Research: CD47-mediated regulation of efferocytosis and its role in cancer, atherosclerosis and neurological disease

Article Title: CD47-mediated efferocytosis in diseases: A comprehensive review

Article References: Wang, C., Yu, S., Kang, J., Yang, S., Pan, Z., Zhao, Y., Li, C., & Zhu, W. (2026). CD47-mediated efferocytosis in diseases: A comprehensive review. Molecular Biology Reports, 53(1), Article 1656. https://doi.org/10.1007/s11033-026-12854-z

Image Credits: AI Generated

DOI: 10.1007/s11033-026-12854-z

Keywords: CD47, efferocytosis, SIRPα, macrophages, cancer immunotherapy, atherosclerosis, phagocytosis, immune checkpoint, neurodegeneration, glioblastoma, myocardial infarction, inflammation resolution

The significance of the finding lies in how it connects two previously separate threads of biology. CD47 has long been studied in oncology and immunology because it broadcasts a so-called “don’t eat me” signal. When CD47 on a cell’s surface engages its receptor, signal regulatory protein alpha (SIRPα), on macrophages and other myeloid cells, it triggers inhibitory pathways that suppress phagocytosis and efferocytosis, the orderly clearance of dead and dying cells. Cancer cells exploit this signal to evade immune surveillance, which is why anti-CD47 antibodies are being developed as cancer therapeutics. Separately, CD47 also binds thrombospondin-1 and integrins, pathways that regulate nitric oxide signaling, vascular tone, oxidative stress, and cell survival. Prior work has linked CD47 upregulation to cardiac hypertrophy, fibrosis, ischemia-reperfusion injury, and atherosclerosis, while CD47 inhibition has been shown to protect cardiac function in several models.

What remained unknown was whether CD47 participates in cardiac aging itself, particularly the accelerated aging induced by chemotherapy. Clues had been accumulating. In skeletal muscle stem cells, CD47 levels rise with age, and as senescence markers such as beta-galactosidase activity increase, the density of CD47 on the cell surface climbs in parallel, forming what researchers have described as a molecular signature of aging. Aberrant CD47 expression has also been documented in aged fibroblasts, epithelial cells, and red blood cells. Because doxorubicin inflicts a characteristic cascade of injuries on the myocardium, including DNA intercalation, interference with topoisomerase-II-dependent DNA repair, chromatin disruption through nucleosome destabilization and histone eviction, mitochondrial dysfunction, oxidative stress, impaired autophagy, and inflammatory activation, the Chinese team hypothesized that CD47 might serve as the underexplored link between these upstream insults and persistent, age-like cardiac remodeling.

To test this, the researchers first turned to public transcriptomic databases. They analyzed two independent cardiac aging datasets from the Gene Expression Omnibus: a rat dataset (GSE173360) comparing six-month-old adult males with 24-month-old aged animals, and a mouse dataset (GSE225576) comparing young and aged hearts. In both species, CD47 expression was significantly elevated in aged heart tissue, and functional enrichment analysis of the differentially expressed genes revealed alterations in metabolic and myocardial contraction-related pathways. The consistency across two mammalian species suggested that CD47 upregulation is a conserved feature of cardiac aging rather than a quirk of one model system.

The team then built a doxorubicin-induced cardiac aging model in six-month-old male C57BL/6J mice. Animals received weekly intraperitoneal injections of doxorubicin at 2.5 milligrams per kilogram for six consecutive weeks, a regimen designed to mimic the cumulative cardiac stress seen in chemotherapy patients. Molecular analysis confirmed that the model worked: mRNA levels of canonical aging markers, including p53, p16, p21, and the proliferation marker KI67, were markedly elevated in the hearts of doxorubicin-treated mice. Crucially, both the mRNA and protein levels of CD47 were significantly increased in these aged hearts, as demonstrated by quantitative PCR, western blotting, and immunofluorescent staining of cardiac tissue sections.

With the model established, the researchers introduced their therapeutic intervention: ligufalimab, also known as AK117, a humanized IgG4 monoclonal antibody that targets CD47 and blocks its interaction with SIRPα without altering CD47 expression itself. Mice receiving doxorubicin plus weekly ligufalimab at 1 milligram per kilogram showed a striking molecular shift. Expression of the senescence effectors p21 and p16 declined significantly in the heart, indicating that CD47 blockade was not merely improving hemodynamics but was actually dampening the senescence-associated signaling that underlies age-like cardiac remodeling. Echocardiographic assessment, performed after the final dose under pentobarbital anesthesia, told a parallel story. Left ventricular fractional shortening and ejection fraction, the standard functional measures of cardiac pumping performance, dropped sharply in doxorubicin-treated mice compared with saline controls, but ligufalimab co-treatment significantly improved both parameters.

To probe whether the effect was conserved in human cells, the team turned to AC16 cardiomyocytes, a human cardiac cell line derived from a male donor. Cells treated with 0.1 micromolar doxorubicin for 48 hours developed a clear senescence-like phenotype, with p16 and p21 mRNA rising steeply and CD47 mRNA and protein increasing in parallel. When ligufalimab at 0.1 micrograms per milliliter was added alongside the chemotherapy, p21 fell at both the mRNA and protein levels, p16 declined at the mRNA level, and senescence-associated beta-galactosidase staining revealed a notable reduction in cellular aging. The convergence of results from living mouse hearts and cultured human cardiomyocytes strengthens the argument that the protective effect is not species-specific or model-dependent, and it points toward genuine translational relevance.

Mechanistically, the authors propose a compelling explanation centered on the CD47-SIRPα axis. During doxorubicin-induced cardiac injury, upregulated CD47 on stressed or senescent cardiomyocytes may shield those cells from macrophage-mediated clearance, allowing damaged cells to linger and continue broadcasting inflammatory and profibrotic signals throughout the myocardium. By blocking CD47, ligufalimab may restore the removal of injured and senescent cells, limit chronic inflammatory amplification, and thereby interrupt the self-reinforcing loop that converts acute chemotherapy injury into persistent age-like remodeling. The observed reduction in p53, p16, and p21 after CD47 blockade is consistent with this interpretation, suggesting that the antibody attenuates senescence-associated signaling itself rather than simply propping up contractile performance. The finding also reframes CD47 as more than an immune checkpoint molecule: it appears to function as a stress-responsive regulator that integrates cellular damage, immune clearance, and cardiovascular remodeling.

The authors are careful to note that important questions remain before this science can reach the clinic. The downstream mechanisms are not yet fully defined; future work should directly assess SIRPα-dependent efferocytosis, thrombospondin-1/CD47 signaling, mitochondrial function, reactive oxygen species production, inflammatory cytokines, and senescence-associated secretory factors. It is also unclear whether the benefits of anti-CD47 therapy are immune-mediated, intrinsic to cardiac cells, or both, and cell-specific genetic models, macrophage-depletion experiments, and efferocytosis assays will be needed to disentangle these contributions. Because CD47 is broadly expressed and plays essential roles in immune surveillance and red blood cell clearance, clinical translation will demand careful optimization of treatment timing, dose, tissue specificity, and safety. The researchers suggest that transient or cardiac-targeted CD47 inhibition might retain cardioprotective effects while minimizing systemic adverse effects. They also acknowledge that the study focused on male mice and on the heart alone, leaving open whether CD47 regulates aging in other organs and in female animals. Even so, the study marks a notable step: it identifies CD47 as both a potential biomarker of cardiac aging and a druggable contributor to chemotherapy-induced cardiac decline, raising the prospect that oncologists might one day protect the aging heart while still unleashing doxorubicin’s full anticancer power.

Subject of Research: The role of CD47 in doxorubicin-induced cardiac aging and its blockade as a cardioprotective strategy in male mice

Article Title: CD47 is a regulator in doxorubicin‐induced cardiac aging in male mice

Article References: Yan, A., Mai, R., Cao, T., Duan, C., Liu, S., & Wang, X. (2026). CD47 is a regulator in doxorubicin‐induced cardiac aging in male mice. Physiological Reports, 14(18), Article e71111. https://doi.org/10.14814/phy2.71111

Image Credits: AI Generated

DOI: 10.14814/phy2.71111

Keywords: CD47, doxorubicin, cardiac aging, cardiotoxicity, senescence, ligufalimab, SIRPα, efferocytosis, cardiomyocytes, echocardiography, chemotherapy, heart failure