Writing in Nature, the group describes a myeloid-selective interleukin-10 receptor agonist, or msIL-10R agonist, a tetravalent nanobody-based molecule that reproduces IL-10’s potent suppression of inflammatory myeloid cells while leaving T cells untouched. The key insight came from a careful dissection of how different immune cells transmit the IL-10 signal. IL-10 normally binds IL-10Rα and IL-10Rβ to form a tetrameric receptor complex constitutively associated with the Janus kinases JAK1 and TYK2. When the cytokine engages the receptor, JAK1 must be activated through transphosphorylation, and the team found that cells can accomplish this through two parallel routes: TYK2-to-JAK1 or JAK1-to-JAK1. Crucially, the relative reliance on these routes differs dramatically between cell types.

To map these routes, the researchers used a selective allosteric JAK1 inhibitor called VVD-118313, which blocks JAK1 transphosphorylation without touching the kinase’s active site, alongside the TYK2 inhibitor zasocitinib and CRISPR-based gene knockout. In mouse bone-marrow-derived macrophages, blocking JAK1-to-JAK1 transphosphorylation only partially reduced IL-10-induced STAT3 phosphorylation and did not abolish the cytokine’s functional suppression of tumour necrosis factor. Only when TYK2 was also removed did signalling collapse completely, showing that at least one transphosphorylation route must remain intact. Human monocytes behaved similarly: TYK2 inhibition or knockout dented STAT3 phosphorylation but left the suppression of LPS-induced TNF and IL-6 fully intact.

T cells told a strikingly different story. In CD8-positive T cells, both pharmacological TYK2 inhibition and CRISPR knockout diminished IL-10-induced STAT3 phosphorylation and completely eliminated the cytokine’s augmentation of granzyme B and interferon-gamma production. T cells, in other words, depend strictly on TYK2 and on maximal pathway activation, whereas myeloid cells tolerate a substantially attenuated signal. The team confirmed this threshold logic with an engineered IL-10 monomer that engages only a single IL-10Rα–IL-10Rβ heterodimer, restricting signalling to one TYK2–JAK1 route. The monomer drove roughly half of maximal STAT3 phosphorylation in monocytes yet retained meaningful TNF suppression, while failing entirely to activate STAT3 or cytotoxic effector programs in T cells. Attenuation, it seemed, could be a feature rather than a bug.

Attenuated cytokines alone, however, make poor drugs. Previous IL-10 monomers and affinity-tuned muteins suffered from short half-lives, thermal instability, residual T and B cell activation and vulnerability to naturally occurring anti-IL-10 autoantibodies, which are common in inflammatory bowel disease. The team instead turned to single-domain antibodies. Alpacas were immunized with the extracellular domains of human IL-10Rα and IL-10Rβ, and phage-display libraries built from their B cells yielded diverse families of receptor-binding VHH domains. These were assembled into dimeric and tetravalent constructs pairing anti-IL-10Rα with anti-IL-10Rβ nanobodies, and screened in STAT3 reporter cells and primary human cells. Of 882 combinations tested, 182 showed reporter activity and 21 achieved more than 90 percent inhibition of TNF and more than 85 percent inhibition of IL-6 in LPS-stimulated blood cells.

Most of those hits, however, still recapitulated IL-10’s unwanted T cell stimulation. One construct stood apart. Designated the msIL-10R agonist, it pairs an anti-IL-10Rα nanobody called E07 with an anti-IL-10Rβ nanobody called A05 in each arm of an Fc scaffold, creating a tetravalent molecule with picomolar potency. It inhibited LPS-induced TNF with a half-maximal inhibitory concentration of 2.1 picomolar and IL-6 at 6.9 picomolar in human blood cells, while eliciting less than 10 percent of maximal STAT3 phosphorylation in CD4 and CD8 T cells, no induction of interferon-gamma or granzyme B, and no B cell proliferation or plasmablast differentiation. RNA sequencing confirmed that the molecule reproduced IL-10’s anti-inflammatory transcriptional program in resting and LPS-stimulated blood cells, including suppression of CSF3, IL6 and PTGES, yet induced no significantly differentially expressed genes in activated T cells.

Cryo-electron microscopy revealed why geometry matters so much. Using a fiducial Fab to enlarge the small receptor–nanobody complex, the team resolved the IL-10Rα–IL-10Rβ–E07-A05 assembly at 3.14 angstroms and a second IL-10Rα–E07 complex at 2.40 angstroms. The nanobody A05 binds an epitope on IL-10Rβ that partially overlaps the cytokine-binding surface but induces a local rearrangement of the Asn138–Trp143 loop, while E07 recognizes a broad surface spanning the junction of IL-10Rα’s two fibronectin type III domains, on the opposite side of the receptor from the IL-10 binding site. Notably, disease-associated IL10RA mutations such as Y64C and R117C, which cripple native IL-10 signalling and underlie very-early-onset inflammatory bowel disease, left the msIL-10R agonist’s activity fully intact, because the molecule engages epitopes spatially distinct from the cytokine interface.

Functional dissection showed that the tetravalent architecture is not negotiable. Disrupting either receptor-binding arm abolished STAT3 phosphorylation and cytokine suppression, maximal activity required simultaneous cross-linking of two IL-10Rα molecules with one or two IL-10Rβ molecules, and even subtle geometric changes were consequential. Shortening or lengthening the glycine-serine linker between E07 and A05 reduced activity, inverting the tandem nanobody order to A05-E07 abolished signalling entirely, and a symmetric A05-A05/E07-E07 arrangement boosted myeloid potency but restored roughly 20 percent of native IL-10’s interferon-gamma response in T cells. Signalling output, the authors conclude, is governed not simply by receptor occupancy but by the precise topology of receptor cross-linking, which forces the complex into a geometry that permits only TYK2-to-JAK1 transphosphorylation.

That strict TYK2 dependence, combined with receptor abundance, explains the selectivity. Myeloid cells express two- to eighteen-fold more surface IL-10Rα and IL-10Rβ than T, B or natural killer cells, providing the avidity needed to cluster the tetravalent agonist, whereas lymphocytes fall below the threshold. When the researchers forced T cells to overexpress IL-10Rα, and especially both receptor chains, STAT3 phosphorylation and granzyme B production returned, confirming receptor copy number as the critical determinant. The logic even proved portable: bispecific nanobodies pairing IL-10Rα with the lymphocyte-enriched IL-2Rγ chain redirected signalling toward T and NK cells, producing T/NK-selective agonists with minimal monocyte activity, again exquisitely dependent on geometry.

In vivo, the molecule delivered. In humanized IL10RA/IL10RB knock-in mice, it suppressed systemic TNF, IL-6 and IL-12 after LPS challenge as effectively as IL-10-Fc, reduced ear swelling and lymph node neutrophil infiltration in a delayed-type hypersensitivity model, and improved colon weight-to-length ratios, splenic neutrophil expansion and inflammatory gene expression in DSS-induced colitis. In cynomolgus monkeys, a humanized version showed dose-proportional exposure, sustained monocyte receptor occupancy and a terminal half-life of roughly eight days, with durable TNF suppression for more than three weeks after a single dose. Unlike IL-10-Fc, which elevated IL-18 and caused anaemia and thrombocytopaenia, the agonist produced no IL-18 elevation or haematological abnormalities at doses up to 100 milligrams per kilogram. The work establishes a geometry-based strategy for cell-type-selective cytokine engineering and positions the msIL-10R agonist as a promising candidate for inflammatory bowel disease and other myeloid-driven conditions, while offering a generalizable blueprint for precision cytokine therapeutics across immunology and oncology.

Subject of Research: Engineering a myeloid-selective IL-10 receptor agonist through TYK2-dependent signalling and receptor geometry

Article Title: Engineered TYK2 dependence enables myeloid-selective IL-10 receptor agonism

Article References: Canaria, D. A., Nguyen, T. T. T., Huang, H., Xu, H., Yue, L., Fu, Y., Truong, H., Patel, K., Xing, W., Ravichandar, J. D., Xing, C., Martin, A. L., Delidakis, G., Wong, S., Pae, A., Yu, Y., Macdonald, R., Huang, Z., Main, M. C., … Yi, T. (2026). Engineered TYK2 dependence enables myeloid-selective IL-10 receptor agonism. Nature. https://doi.org/10.1038/s41586-026-11176-1

Image Credits: AI Generated

DOI: 10.1038/s41586-026-11176-1

Keywords: interleukin-10, IL-10 receptor, TYK2, JAK1, nanobody, myeloid cells, T cells, STAT3, cryo-electron microscopy, inflammatory bowel disease, cytokine agonism, immunotherapy

The research, led by Xin Gao and Xiaofeng Guo of Shanxi Provincial People’s Hospital together with Shaopeng Yang of Zhejiang Cancer Hospital and corresponding author Qi Zhang of Shandong Cancer Hospital and Institute, describes a protein-prioritised, colocalisation-informed framework for generating target-outcome safety hypotheses. Rather than waiting for post-marketing surveillance to reveal unexpected adverse events, the team asked whether human genetics could flag plausible safety concerns for eighteen genes that represent established or emerging inflammatory bowel disease therapeutic targets. The logic is elegant: if genetically lowered levels or expression of a drug’s target protein are associated with increased risk of a particular disease outcome in population data, then pharmacologically inhibiting that same target deserves closer scrutiny for a similar effect.

The technical architecture of the study is where much of its novelty lies. The authors assembled twenty-five sets of genetic instruments, drawn either from cis-protein quantitative trait loci, which are variants that alter circulating protein levels, or from cis-expression quantitative trait loci, which are variants that alter gene expression in blood. These proxies covered the eighteen therapeutic genes and were tested against seventy-six prespecified safety outcomes drawn from the FinnGen R13 biobank release, a Finnish resource combining genetic data with national health registry records covering conditions from autoimmune disease to venous thromboembolism. In total, 1,900 tasks were planned, of which 1,824 proved analysable, generating a matrix of target-outcome hypotheses that could be evaluated in a statistically disciplined way.

A key methodological challenge was sparsity. Stringent selection of cis-acting variants, which are preferred because they are less prone to confounding by distant genetic effects, often leaves only one or a handful of usable instruments per gene. Conventional Mendelian randomisation methods that require many variants are therefore poorly suited to this setting. The workflow adapted by combining single-variant or few-variant Wald ratios with inverse-variance-weighted estimates where multiple variants were available, and then applying rigorous false-discovery-rate control. A global Benjamini-Hochberg correction across all 1,824 estimates served as the primary filter, with secondary corrections applied within forty narrower outcome domains. This two-tier approach balanced statistical conservatism against the risk of missing genuine signals buried in the multiple-testing burden.

The criteria for advancing a hypothesis were deliberately strict. An estimate had to pass the global false-discovery threshold, point in a risk-increasing direction under simulated target lowering, and lie outside the major histocompatibility complex, a densely variable genomic region notorious for producing misleading associations because of its extreme linkage disequilibrium. Signals meeting these conditions entered an objective follow-up phase involving sensitivity analyses, instrument-centred colocalisation and variant-level annotation. Colocalisation is the critical step: it asks whether the genetic variant associated with the molecular proxy, such as a protein level, and the variant associated with the disease outcome are in fact the same causal variant, rather than two nearby variants inherited together. The team used Bayesian colocalisation methods in windows of plus or minus 250 kilobases centred on each instrument, requiring a posterior probability of a shared causal variant above 0.5.

From the initial screen, one hundred estimates passed global false-discovery control and twenty more met only the narrow-domain threshold, producing fifteen tasks representing thirteen distinct target-outcome pairs for follow-up. The final classification stratified hypotheses by molecular layer, distinguishing protein-level P1 and P2 categories from expression-level E1 and E2 categories depending on whether colocalisation support exceeded the threshold. This stratification matters because a hypothesis supported at the protein level, where the drug will actually act, carries different translational weight than one supported only at the messenger RNA level, where the relationship between expression and protein abundance is often imperfect.

Two protein-level P1 hypotheses emerged as the strongest safety signals. The first linked lower ITGB7, the integrin targeted by vedolizumab, a widely used gut-selective biologic, with increased risk of multiple sclerosis and demyelinating disease, showing an odds ratio of 2.35 with a global q-value of 0.003 and colocalisation support of 0.935. The second connected TNFRSF1A, a tumour necrosis factor receptor, with myocardial infarction, an association replicated across two independent proteomic resources, the UK Biobank Pharma Proteomics Project and deCODE, with odds ratios of 1.56 and 1.37 respectively, both driven by the same variant, rs4149584, which encodes the R92Q amino-acid substitution. The convergence of two independent protein datasets on the same variant and the same outcome lends considerable credibility to the signal.

At the expression level, two E1 hypotheses stood out, both involving psoriasis, an outcome of particular interest because psoriasis shares inflammatory pathways with inflammatory bowel disease and is itself a comorbidity of the condition. Reduced IL23A expression was associated with dramatically increased psoriasis risk, with an odds ratio of 4.13 and an exceptionally strong q-value of 7.47 times ten to the minus nine, while reduced TYK2 expression showed an odds ratio of 1.53 with a q-value of 1.10 times ten to the minus eleven and near-perfect colocalisation support of 0.984. These findings are biologically coherent: IL-23 and TYK2 are the molecular foundations of some of the most successful recent therapies in both psoriasis and inflammatory bowel disease, and the genetic data suggest that their pathways are deeply intertwined with psoriasis susceptibility in ways that clinicians managing patients with both conditions should note.

Not every candidate signal survived scrutiny, and the framework’s treatment of these failures is as informative as its successes. IL12B-psoriasis and TNFSF15-lower-extremity deep-vein thrombosis were classified as P2 hypotheses because colocalisation posterior probabilities fell below the 0.5 threshold, meaning the apparent associations could not be confidently attributed to a shared causal variant. This is precisely the kind of auditable, transparent triage that distinguishes a disciplined hypothesis-generation framework from a fishing expedition. Every step, from the 1,900 planned tasks through the 2,584 SNP-level rows, heterogeneity analyses, weighted-median estimates and leave-one-out sensitivity checks, is documented in supplementary workbooks, allowing independent researchers to audit the provenance of each conclusion.

The broader significance of this work lies in its positioning within the drug development pipeline. Safety signals that emerge from human genetics are not deterministic predictions; they are prioritised hypotheses that can direct mechanistic validation in experimental systems and targeted evaluation in clinical safety datasets before large populations are exposed. By stratifying evidence by molecular proxy type, enforcing locus specificity through colocalisation, and excluding the confounded major histocompatibility complex region, the framework produces a short, defensible list of target-outcome pairs that merit attention. For a therapeutic area where biologics have transformed patient outcomes but questions remain about long-term risks such as demyelination, infection and cardiovascular events, the ability to generate such lists computationally, using only publicly available summary-level data, represents a meaningful step toward safer and faster drug development. The authors’ emphasis on auditability and reproducibility suggests the framework could be extended to other disease areas, turning the human genome into a routine preclinical screening tool for pharmacovigilance.

Subject of Research: Genetic prediction of safety outcomes for inflammatory bowel disease therapeutic targets using Mendelian randomisation and colocalisation

Article Title: A protein-prioritised, colocalisation-informed genetic framework for safety hypothesis generation across inflammatory bowel disease therapeutic pathways

Article References: Gao, X., Guo, X., Yang, S., & Zhang, Q. (2026). A protein-prioritised, colocalisation-informed genetic framework for safety hypothesis generation across inflammatory bowel disease therapeutic pathways. Journal of Translational Medicine. https://doi.org/10.1186/s12967-026-09068-z

Image Credits: AI Generated

DOI: 10.1186/s12967-026-09068-z

Keywords: inflammatory bowel disease, Mendelian randomisation, colocalisation, pQTL, eQTL, drug safety, FinnGen, ITGB7, TNFRSF1A, TYK2, IL23A, pharmacovigilance