The study, led by Marxa L. Figueiredo of Purdue University, integrated publicly available single-cell RNA sequencing datasets spanning multiple preclinical mouse models of inflammatory arthritis, together with 12 healthy controls and 15 rheumatoid arthritis samples. The models were chosen deliberately to capture complementary facets of the disease: collagen-induced arthritis replicates the chronic, autoimmune, T-cell and B-cell-dependent phases of systemic joint destruction; serum transfer-induced arthritis bypasses adaptive priming to mimic the acute, antibody- and innate immune-mediated effector phase; antigen-induced arthritis models localized, antigen-specific, T-cell-driven joint inflammation; and the glucose-6-phosphate isomerase model represents metabolic-immune crosstalk with rapid systemic pathology. By converging on the programs shared across these diverse etiologies, the team sought a conserved landscape of synovial remodeling rather than a model-specific snapshot.

The bioinformatic pipeline was substantial. Count matrices were processed through Trailmaker and ICARUS v3, with background noise removed using transcripts-per-cell thresholds, dead cells filtered by mitochondrial content, doublets excluded with scDblFinder, and batches corrected using Harmony. Unsupervised Leiden clustering with UMAP visualization resolved the integrated mouse synovium into 25 distinct clusters, which the researchers organized into functional niches: a structural and fibroproliferative compartment, a vascular and endothelial compartment, a myeloid immune compartment, a lymphoid and mast compartment, and even a peripheral glial niche containing Schwann cells. Within the structural niche alone, profiling distinguished universal Pi16-positive sublining progenitors, specialized Calb1-positive stromal cells, mechanosensitive Dkk3-positive fibroblasts, fibrogenic Postn-positive fibroblasts, activated fibroblast-like synoviocytes, myofibroblasts, inflammatory progenitors, and joint-destructive Prg4/Il6-positive lining fibroblasts, alongside osteoblast and chondrocyte lineages.

Differential expression analysis comparing inflamed and healthy joints revealed a pronounced transcriptional imbalance. Upregulated genes in arthritic synovium were strongly enriched for innate immune cascades, including neutrophil degranulation and platelet activation and aggregation, as well as extracellular matrix organization, supramolecular fiber organization, focal adhesion, regulation of proteolysis, IL-17A signaling, and TNF production. Protein-protein interaction network analysis identified interconnected modules centered on collagen formation, ECM organization, and actin filament regulation. Conversely, downregulated genes represented a loss of homeostatic programs: tissue development, blood vessel development, glial cell fate specification, biomineral tissue development, and fatty acid metabolism. The picture that emerges is a joint shifting away from protective, regenerative maintenance toward aggressive immune activation and pathological matrix remodeling, a dual failure that helps explain why suppressing inflammation alone often cannot stop structural damage.

The study’s most striking mechanistic finding came from cell-cell communication modeling with CellChat, which inferred ligand-receptor interactions across the diseased synovium. Vascular mural cells, sublining progenitors, fibrogenic sublining fibroblasts, and lining fibroblasts emerged as strongly upregulated signaling hubs. Within the Notch family, the highest-strength disease-state links were autocrine Jag1-Notch3 signaling within vascular mural cells and endothelial-to-mural Dll4-Notch3 communication from activated endothelial cells. Beyond this structural feedback loop, mural Jag1-Notch2 and endothelial Dll4-Notch2 signaling maintained strong communication with infiltrating inflammatory monocytes and sublining macrophages, with an additional Dll4-Notch1 interaction targeting monocytes. This positions the vascular-mural unit as an actionable upstream trigger that simultaneously drives structural remodeling and macrophage activation in the inflamed joint.

Downstream of this perivascular trigger, regulatory network inference with SCENIC revealed a synchronized, stress-induced transcriptional program. Vascular mural cells, chondrocytes, inflammatory progenitors, specialized sublining subsets, and macrophage populations all displayed coordinated activity of the Atf3 and Fos regulons, transcription factors of the AP-1 family that govern inflammatory stress responses, clustering with the immediate-early gene Egr1 and Krüppel-like factors Klf4 and Klf10. The researchers suggest this shared module may function as a unified regulatory hub coordinating myofibroblast differentiation and the aggressive fibrotic response characteristic of chronic joint disease. Replicate-aware pseudobulk DESeq2 modeling confirmed that these cluster-specific patterns mirror the global trends, supporting the findings under a statistically rigorous framework with a Benjamini-Hochberg adjusted threshold.

Crucially, the mouse findings translated to human disease. The team analyzed a high-resolution human rheumatoid arthritis synovial dataset generated with 10x Genomics Visium HD spatial transcriptomics, processed through the VST-DAVis pipeline. A single sample yielded 474,081 tissue-associated 8-micrometer bins with a mean of 197.2 UMIs per bin, allowing unsupervised clustering of spatially resolved tissue domains. Human vascular mural lineages separated into NOTCH3, ACTA2, and TAGLN-enriched mural cells and MYH11-expressing perivascular fibroblasts, mirroring the mouse compartments. Weighted gene co-expression network analysis returned a single dominant module, SM01, a stress and matrix-remodeling hub containing VIM, FN1, MMP2, CTSB, PLA2G2A, CD74, COL6A2, SELENOP, and COL3A1. This module was selectively and highly enriched in human activated FLS and lining FLS, the functional homologs of the mouse sublining fibroblast and mural hubs, suggesting the Atf3/Fos stress-response pathway and its downstream matrix-remodeling program are conserved drivers of the inflammatory stromal phenotype in human RA.

The spatial data then did what conventional single-cell sequencing cannot: it placed these circuits in physical context. Activated FLS emerged as a central spatial coordinator, acting as the primary source of outgoing Collagen, FN1 (fibronectin), Tenascin, and THBS (thrombospondin) ligands while remaining highly receptive to incoming NOTCH, THBS, and FN1 signaling. Spatial chord diagrams confirmed perivascular fibroblasts presenting JAG1 to NOTCH3 on vascular mural cells, alongside a multicellular structural network mediated by THBS2, THBS4, and COMP linking lining and activated FLS to SDC1 and CD47 receptors on plasma cells and activated FLS. Most tellingly, spatial overlay maps showed that FN1 and THBS signaling networks co-localize at high density within a distinct inflammatory niche restricted to the synovial tissue’s edge, heavily populated by activated FLS, lining FLS, and perivascular mural cells. The disease, in other words, has an address.

The authors are careful to note the limitations. The spatial transcriptomics dataset, while high-resolution and derived from untreated RA tissue, comes from a single human donor and serves as a proof-of-concept bridge that will benefit from broader validation. CellChat infers potential microenvironmental signaling rather than confirming direct physical cell-cell contact in vivo, so functional assays will be needed to validate the predicted pathways. Even so, the model that emerges is coherent and therapeutically provocative: vascular-derived Jag1 and Dll4 activate Notch3 and Notch2 on adjacent stromal and immune cells, initiating an Atf3/Fos transcriptional cascade that drives both myeloid activation and a matrix-remodeling program within a localized, self-amplifying spatial niche at the tissue’s edge.

That model points toward a stroma- and vascular-directed therapeutic paradigm that differs fundamentally from conventional immunomodulatory biologics. Rather than broadly suppressing systemic immunity, selective blockade of Notch3/2 activation or endothelial ligand presentation could specifically uncouple vascular-to-stromal and vascular-to-immune crosstalk, preventing both pathogenic fibroblast activation and immune infiltrate recruitment. Disrupting this structural trigger could also destabilize the self-amplifying niche at the tissue’s edge. The authors propose that combining perivascular Notch pathway inhibition with downstream targeted therapies against matrix-remodeling networks such as THBS or FN1, or against AP-1 transcription factors like Atf3 and Fos, may represent a synergistic strategy to simultaneously halt chronic inflammation and structural joint destruction. For the many patients whose disease resists today’s immune-targeted drugs, that multi-tier approach, aimed at the joint’s own cellular architecture rather than only its inflammatory guests, offers a genuinely new map of where to intervene.

Subject of Research: Conserved stromal remodeling and Notch/AP-1 signaling pathways in inflammatory arthritis identified through cross-species single-cell and spatial transcriptomics

Article Title: Cross-species single-cell and spatial transcriptomics map the conserved stromal remodeling landscape of inflammatory arthritis

Article References: Figueiredo, M. L. (2026). Cross-species single-cell and spatial transcriptomics map the conserved stromal remodeling landscape of inflammatory arthritis. Frontiers in Molecular Medicine, 6, 1951540. https://doi.org/10.3389/fmmed.2026.1951540

Image Credits: AI Generated

DOI: 10.3389/fmmed.2026.1951540

Keywords: rheumatoid arthritis, single-cell RNA sequencing, spatial transcriptomics, synovial fibroblasts, Notch signaling, AP-1 transcription factors, vascular mural cells, extracellular matrix remodeling, fibroblast-like synoviocytes, CellChat, Visium HD, mouse models

The study began with a practical problem: researchers have lacked good tools to study the behavior of hepatitis B virus-specific T cells in a physiologically relevant setting. The team used a humanized mouse model carrying the human HLA-A11 molecule to identify a T cell receptor that recognizes HBc141-151, an epitope from the hepatitis B core antigen that is clinically relevant in human patients. This receptor, which the authors call HB-I, allowed them to generate transgenic mice whose entire CD8+ T cell population is specific for a single, human-relevant HBV epitope, providing a tractable platform for dissecting why these cells fail during chronic infection.

With that platform in hand, the researchers turned to an unbiased discovery strategy. Using a whole-genome CRISPR-Cas9 knockout library delivered into HBV-specific T cells, followed by screening under chronic antigen stimulation, they asked which genes, when deleted, would help T cells resist the dysfunctional state that normally develops. The screen converged on Ankrd11, a gene previously known as a chromatin regulator implicated in neural development and in Kabuki-like syndromes, but never before linked to T cell exhaustion. Loss of Ankrd11 consistently produced T cells that proliferated more vigorously and retained stronger effector characteristics.

The mechanistic picture that emerges from the paper is epigenetic. ANKRD11 appears to restrain the accessibility and acetylation of key effector genes. Using ATAC-seq, bulk RNA-seq and CUT&Tag profiling of the histone mark H3K27ac, the team showed that Ankrd11-deficient CD8+ T cells display increased chromatin openness and enhancer acetylation at loci encoding AP-1 family transcription factors, notably Fos and Fosb. Elevated AP-1 activity, in turn, drives a program of effector differentiation: the cells produce more granzyme B and interferon-gamma, resist the immunosuppressive conditions that normally silence them, and maintain function even when interleukin-2, a survival factor, is limiting.

Functionally, the consequences of losing this brake were striking. In mice carrying a replicating HBV plasmid or infected with recombinant HBV vectors, Ankrd11-deficient HBV-specific T cells expanded more robustly, infiltrated the liver more effectively, and drastically reduced serum levels of hepatitis B surface antigen, viral DNA and markers of liver damage. Parallel experiments using a second chronic infection model, lymphocytic choriomeningitis virus clone 13, confirmed the generality of the effect: adoptively transferred Ankrd11-deficient virus-specific P14 T cells showed enhanced granzyme expression, proliferation and viral control in the spleen and blood.

Perhaps the most conceptually interesting finding concerns the differentiation paths that exhausted T cells normally follow. In chronic infection and cancer, antigen-specific CD8+ T cells split into progenitor exhausted T cells, which express the transcription factor TCF-1 and serve as a self-renewing reservoir, and terminally exhausted T cells, which lose TCF-1 and are irreversibly dysfunctional. The authors found that Ankrd11 deficiency accelerates the conversion of progenitor exhausted cells into effector-like exhausted cells, but importantly, the resulting cells are cytotoxic and functional rather than inert. This suggests ANKRD11 does not simply maintain progenitor pools but actively gates how far exhausted cells differentiate toward effector competence.

The study also revealed a distinct route of reprogramming specific to chronic hepatitis B. A large fraction of HBV-specific CD8+ T cells in tolerant mice carries a PD-1-negative, TOX-negative phenotype that has resisted conventional checkpoint-based rescue strategies. When ANKRD11-mediated repression was relieved, these tolerant cells differentiated into PD-1-positive, KLRG1-positive effector cells armed with high granzyme levels, providing an explanation for the improved viral clearance. In other words, ANKRD11 deficiency unlocks an otherwise dormant pool of virus-specific cells that immune checkpoint blockade alone cannot reach.

The antitumor implications were tested directly in cancer models. Ankrd11-deficient CD8+ T cells promoted rejection of implanted tumors, enhanced intratumoral T cell activity, and acted synergistically with immune checkpoint blockade, potentiating the effect of PD-1 pathway inhibition. Given that the exhaustion of tumor-infiltrating lymphocytes is a central cause of immunotherapy failure, a single gene whose deletion reprograms effector differentiation under immunosuppressive conditions is an attractive candidate for therapeutic engineering, for example in chimeric antigen receptor or T cell receptor-engineered cell products. A provisional patent application has been filed based on the findings, underscoring the translational interest.

Caveats remain before ANKRD11 targeting reaches the clinic. ANKRD11 is a broad chromatin regulator with established roles in neural and cardiac development, so systemic inhibition is unlikely to be safe; the therapeutic window will probably lie in ex vivo engineering of T cells or in carefully targeted delivery. It will also be important to determine whether accelerated terminal differentiation comes at the cost of long-term memory formation. Nevertheless, the study delivers a clear conceptual advance: T cell dysfunction in chronic infection and cancer is not merely the product of inhibitory receptor signaling, but is epigenetically authored, and specific chromatin factors such as ANKRD11 can be removed to rewrite that script. For the hundreds of millions of people living with chronic hepatitis B, and for cancer patients whose T cells have gone quiet, that insight opens a new direction for immunotherapy design.

The concept of T cell exhaustion has shaped immunology for two decades. Since the landmark demonstration that chronically stimulated CD8+ T cells can regain function when inhibitory pathways are interrupted, researchers have catalogued a molecular signature of the dysfunctional state, and later work established the transcription factor TOX as a master architect of the exhaustion program, acting at both transcriptional and epigenetic levels. What has remained less clear is whether exhaustion is a fixed fate or a tunable state whose chromatin underpinnings can be deliberately rewritten. The new study adds weight to the second view by identifying a specific chromatin-associated protein whose removal shifts the balance of differentiation toward cytotoxic competence.

The methodological route to this finding is worth noting. Genome-wide CRISPR-Cas9 knockout screens have become a powerful way to uncover genes that constrain or enable T cell behavior, and previous efforts using this approach identified regulators such as REGNASE-1 and Roquin as suppressors of effector expansion and antitumor immunity. The present screen extends this logic into the setting of chronic hepatitis B virus infection, a context in which suppressive cues differ from those in tumors and in which conventional checkpoint blockade has shown only modest clinical benefit. That an unbiased screen converged on a gene with no prior immunological pedigree illustrates how phenotype-first discovery can bypass assumptions rooted in known pathways.

ANKRD11 itself carries an interesting dual history. It was first characterized as a chromatin regulator essential for neural development, and subsequent work showed it controls cardiac neural crest-mediated remodeling of the outflow tract. Its association with a Kabuki-like syndrome in humans reflects the pleiotropic consequences of disturbing a factor that operates broadly across tissues. This background both explains why the protein had escaped attention in immunology and reinforces the caution that any therapeutic interference must be confined to engineered cells rather than delivered systemically.

The AP-1 connection provides a mechanistic bridge to earlier T cell biology. AP-1 family transcription factors, built from Fos and Jun proteins, have long been recognized as immediate-early responders to T cell receptor signaling, and their activity is known to cooperate with other factors to specify effector genes. By showing that ANKRD11 restrains chromatin accessibility and H3K27 acetylation at AP-1 loci, the study suggests a route by which a chromatin regulator can gate a transcriptional program that is otherwise primed and waiting in naive and exhausted cells alike.

The authors have deposited the datasets underlying these conclusions in public repositories: bulk RNA-seq data under accession GSE299520, ATAC-seq data under GSE299519, and CUT&Tag data under GSE299521, with source data provided alongside the paper. No original code was generated. This transparency should allow groups working on T cell engineering to interrogate the chromatin changes directly and to test whether similar ANKRD11-sensitive programs operate in human tumor-infiltrating lymphocytes, a necessary step before the findings can inform next-generation cell therapy design.

Subject of Research: Epigenetic regulation of CD8+ T cell dysfunction in chronic viral infection and cancer

Article Title: ANKRD11 deficiency reprograms CD8+ T cell differentiation to enhance immunity in chronic infection and cancer

Article References: Xu, W., Guo, J., Cao, X., Li, L., Xiao, P., Zhang, X., Jin, Q., Zhang, F., Hou, B., Li, M., & Zhou, X. (2026). ANKRD11 deficiency reprograms CD8+ T cell differentiation to enhance immunity in chronic infection and cancer. Nature Immunology. https://doi.org/10.1038/s41590-026-02652-x

Image Credits: AI Generated

DOI: 10.1038/s41590-026-02652-x

Keywords: ANKRD11, CD8+ T cells, T cell exhaustion, chronic hepatitis B, epigenetics, immunotherapy, CRISPR screen, AP-1 transcription factors, granzyme B, immune checkpoint blockade, tumor immunity, T cell receptor