The research team, led by investigators at Nanfang Hospital and Southern Medical University in Guangzhou, China, combined bulk RNA sequencing, time-series transcriptomics, single-cell RNA sequencing, and spatial transcriptomics to profile the immune landscape as it evolves from acute colitis to full-blown cancer. Working in wild-type and ApcMin/+ mouse models of dextran sulfate sodium-induced colitis and azoxymethane/DSS-driven carcinogenesis, the researchers tracked transcriptomic kinetics and cellular heterogeneity across disease stages, validating their findings with IL6 knockout mice, colonoscopy, histology, and immune infiltration analyses.

What emerged from the single-cell data was a coordinated remodeling of the immune ecosystem as carcinogenesis progressed. Macrophages within the inflamed colon progressively polarized toward an M2-like, immunosuppressive state, while regulatory T cell and regulatory B cell subsets expanded in parallel. This shift is not merely a byproduct of chronic inflammation; it represents a fundamental rewiring of the mucosal immune environment from one that, at least initially, protects tissue toward one that actively tolerates and nurtures emerging malignancy.

Perhaps the most striking finding is the stage-dependent duality of interleukin-6 itself. During acute colitis, IL6 is essential for mucosal protection, helping the intestinal lining survive the inflammatory assault. But when the disease becomes chronic, sustained IL6 expression from M2-polarized macrophages and stromal cells drives persistent activation of the JAK/STAT3 signaling axis, a canonical pathway that promotes cell survival, proliferation, and immune evasion. The same molecule that heals in the short term becomes an architect of cancer in the long term.

Spatial transcriptomics provided the crucial geographic dimension to this story. The technology, which preserves the physical locations of gene expression within tissue, revealed a distinct myeloid-enriched niche co-localized with proliferative epithelium. In other words, the very cells churning out IL6 are physically positioned next to the compartments where tumor initiation occurs, creating a microenvironment in which immunosuppressive signaling and proliferative drive are spatially coupled rather than diffusely distributed.

Functional validation through IL6 ablation produced one of the study’s most paradoxical results. Mice lacking IL6 experienced exacerbated acute colitis, confirming the cytokine’s protective role during inflammatory flares. Yet those same mice showed attenuated tumor development in the colitis-associated carcinogenesis model, demonstrating that sustained IL6 signaling is pathogenic in the transition from inflammation to cancer. This dissociation between IL6’s acute protective function and its chronic tumor-promoting function has profound implications for therapeutic timing.

The JAK/STAT3 pathway, which relays IL6 signals from the cell surface to the nucleus where STAT3 activates transcription of survival and proliferation genes, has been implicated in inflammation-associated cancers before. But this study is among the first to systematically define the cellular sources of IL6, the spatial organization of its signaling niche, and the functional dynamics of the axis across the full arc of colitis-associated carcinogenesis, from initial injury through malignant transformation.

Colitis-associated colorectal cancer represents one of the most serious complications of inflammatory bowel disease, affecting patients with ulcerative colitis and Crohn’s disease who face elevated cancer risk proportional to the duration and severity of their inflammation. Current surveillance strategies rely on repeated colonoscopy, and prevention options remain limited. A mechanistic target that specifically disrupts the immunosuppressive niche without abolishing IL6’s acute protective role could fundamentally change how clinicians approach cancer prevention in this vulnerable population.

The findings establish the myeloid-derived IL6/JAK/STAT3 axis as a major regulator that orchestrates an immunosuppressive microenvironment and fuels the transition from colitis to colorectal cancer. Whether therapeutic strategies can be designed to exploit the stage-dependent nature of this signaling, protecting the mucosa during flares while blocking the chronic niche that seeds malignancy, remains the critical next question. But the spatial map now exists, and it points directly at a targetable axis.

The methodological design of the study deserves closer attention, because the conclusions rest on an unusually comprehensive sequencing strategy. Bulk RNA sequencing with five samples per group provided a population-level view of transcriptional change, while the time-series design, sampling three animals per time point per group, allowed the investigators to watch molecular events unfold in sequence rather than inferring them from endpoint comparisons. Single-cell RNA sequencing at three animals per group resolved the cellular heterogeneity that bulk methods average away, and spatial transcriptomics, performed on one sample per group, anchored those cell identities back onto intact tissue architecture. Each layer of the multi-omics stack compensates for a weakness in the others: bulk data offer statistical power, time-series data offer temporal ordering, single-cell data offer resolution, and spatial data offer geography. It is this final layer that distinguishes the work, since the co-localization of the myeloid niche with proliferative epithelium could not have been demonstrated by dissociated-cell sequencing alone.

The choice of mouse models also matters for interpreting the results. The dextran sulfate sodium model induces epithelial injury and innate immune activation that recapitulates key features of acute colitis, while the azoxymethane/DSS protocol couples a genotoxic insult with repeated inflammatory cycles to drive tumor formation in the colon, closely mirroring the inflammation-to-cancer sequence seen in patients with long-standing inflammatory bowel disease. The inclusion of ApcMin/+ mice, which carry a mutation in a gene frequently altered in human colorectal cancer, adds a second context in which the IL6-dependent niche could be tested. Convergence of findings across these models strengthens the argument that the myeloid-derived signaling axis is a general feature of colitis-associated carcinogenesis rather than an artifact of any single experimental system.

The paradoxical outcome of IL6 ablation, worse acute colitis but fewer tumors, fits within a broader biological principle that has emerged from decades of cytokine research: molecules that resolve injury in the short term can become engines of pathology when their expression persists. Interleukin-6 signals through the JAK family of kinases, which phosphorylate STAT3, a transcription factor that then accumulates in the nucleus and regulates hundreds of target genes governing proliferation, survival, angiogenesis, and immune tolerance. When STAT3 activation is transient, it supports epithelial repair and barrier integrity. When it is sustained, as the study shows it is during the chronic phase through continuous production from M2-polarized macrophages and stromal cells, the same pathway suppresses antitumor immunity, expands regulatory T and B cell populations, and permits transformed epithelial clones to expand. The stage-dependent duality is therefore not a contradiction but a consequence of signal duration and cellular context.

The spatial organization of the immunosuppressive niche carries particular significance for how such cancers develop. Tumor immunology has increasingly recognized that immune suppression is not distributed uniformly across a tumor but concentrated in anatomically defined microenvironments where immune effector cells are kept at a distance from malignant cells. The demonstration that IL6-producing myeloid cells form a niche physically adjacent to proliferative epithelium provides a concrete anatomical substrate for this principle in colitis-associated cancer. It suggests that the transition from inflammation to malignancy may depend less on the total amount of cytokine in the tissue than on where that cytokine is produced and which cells it reaches, a distinction that bulk measurements of circulating or even tissue-level IL6 would entirely miss.

For patients with ulcerative colitis and Crohn’s disease, the findings arrive amid an evolving therapeutic landscape in which interleukin-6 blockade and JAK inhibitors are already in clinical use for inflammatory conditions. The study’s results suggest that such agents, if deployed in patients with chronic, established inflammation, might do more than control symptoms; they could potentially disrupt the niche that seeds malignant transformation. At the same time, the exacerbation of acute colitis in IL6-deficient mice serves as a caution that indiscriminate blockade during active flares could worsen mucosal injury. The therapeutic window implied by these data is narrow and stage-specific, and translating it into clinical practice will require biomarkers capable of distinguishing the protective, acute phase of IL6 signaling from its pathogenic, chronic phase in individual patients.

The identification of stromal cells as a second source of sustained IL6 alongside M2-polarized macrophages adds another dimension to the niche concept. Fibroblasts and other stromal populations in the inflamed and neoplastic gut are increasingly appreciated as active participants in immune regulation rather than passive structural scaffolding. Their contribution to persistent STAT3 activation implies that effective disruption of the axis may require targeting multiple cellular sources simultaneously, or alternatively, intervening at the level of the signaling pathway itself, where contributions from different producer cells converge. The open-access publication of the study, with its supplementary datasets, positions other laboratories to interrogate these questions using the same multi-omics framework across different models and, eventually, human tissue specimens.

Subject of Research: Cancer Immunology

Article Title: Myeloid-derived IL6/JAK/STAT3 signaling establishes a spatially organized immunosuppressive niche to fuel colitis-associated carcinogenesis

Article References: Chen, Y., Wang, S., Mou, T., Luo, J., Cheng, M., Zhao, B., Li, W., Li, K., Diao, S., Lyu, G., Zhou, W., Ma, W., & Shi, Z. (2026). Myeloid-derived IL6/JAK/STAT3 signaling establishes a spatially organized immunosuppressive niche to fuel colitis-associated carcinogenesis. Journal of Translational Medicine. https://doi.org/10.1186/s12967-026-09050-9

Image Credits: AI Generated

DOI: 10.1186/s12967-026-09050-9

Keywords: colitis-associated cancer, IL6, JAK/STAT3, immunosuppressive niche, spatial transcriptomics, macrophages, inflammatory bowel disease, colorectal cancer, Myeloid-derived, STAT3, signaling, establishes