Inverse correlation between metastatic load and immune infiltration

Number of resident and migratory cDCs is unchanged in the tumor-draining lymph nodes of metastases-bearing TYK2-/- host mice

Immunophenotyping of established metastases by flow cytometry in TYK2-/- and TYK2Δhem host mice

Colorectal cancer liver metastasis (CRLM) is a major clinical problem. The regulators of immunosurveillance of CRLM could hold potential for developing therapeutic strategies to prevent or treat metastasis. In this study, using a murine colorectal cancer organoid-based transplantation model, we identified TYK2 as a key factor controlling CRLM. Evaluation of the effects of Tyk2 deletion in different subsets of immune cells and in colorectal cancer cells demonstrated that TYK2 was not required in cancer cells, macrophages, NK cells, T cells, or Kupffer cells. Instead, TYK2 controlled CRLM via a dendritic cell-dependent mechanism that relied on MHC-I-mediated cross-presentation of antigens to CD8+ T cells. Analysis of single-cell RNA sequencing data from primary colorectal cancer and CRLM revealed that TYK2 was predominantly expressed in a dendritic cell population destined to present antigens in tumor-draining lymph nodes. Treatment with the TYK2 inhibitor deucravacitinib, which is approved by the FDA for treating plaque psoriasis and is under clinical investigation for other autoimmune diseases, promoted CRLM. Together, these data demonstrate that TYK2 controls CRLM immunosurveillance, which should be carefully considered when treating patients with TYK2 inhibitors.Significance: TYK2 restricts the metastasis of colorectal tumors to the liver by supporting dendritic cell-dependent induction of antitumor CD8+ T cells, which could impact the use of TYK2 inhibitors in patients.

mRNA expression of cytokines, chemokines, costimulatory molecules and immune checkpoints in healthy and metastases-bearing livers of TYK2flox/flox and TYK2Δhem host mice

Interferon-γ (IFNγ) is a key cytokine that activates macrophages and is essential for the defence against intracellular pathogens. Beyond its immediate effects, IFNγ also shapes macrophages for subsequent encounters with pathogen-associated molecules by multiple mechanisms, including chromatin remodelling. Here, we employed integrated epigenomic and transcriptomic approaches utilizing primary macrophages from gene-modified mice to explore the role of STAT1 and its naturally occurring isoforms in these processes. Using ChIP-seq for histone modifications (H3K27ac and H3K4me1) and RNA-seq, we demonstrate that STAT1 isoforms differentially modulate macrophage responses to lipopolysaccharide (LPS) following IFNγ conditioning. We provide genetic evidence that STAT1 isoforms exhibit distinct capacities to mediated IFNγ-induced changes in H3K27 acetylation at promoter and enhancer regions, thereby shaping transcriptional responses to LPS. We show that the STAT1β isoform, which lacks the C-terminal transactivation domain (TAD), is unable to mediate the repressive effect of IFNγ on transcriptional regulation by LPS but retains significant collaborative activity. Furthermore, we show that IFNγ attenuates the induction of a subset of antiviral genes and represses LPS-induced negative feedback loops, thereby amplifying the inflammatory response to pathogens. These effects are dependent on the presence of the STAT1 C-terminal TAD, highlighting its importance in fine-tuning the balance between inflammatory and antiviral responses. Our findings uncover isoform-specific roles of STAT1 in IFNγ-driven epigenetic regulation and macrophage conditioning, providing new insights into the control of inflammation and innate immunity.

Altered immunophenotype of micrometastatic lesions in TYK2Δhem host mice

Azole antifungals are essential for controlling fungal diseases in medicine, veterinary care and agriculture. However, extensive cross-sector use has accelerated the emergence of resistant fungal pathogens, threatening human health, food security and ecosystem stability. This Review examines the dual role of azoles as life-saving therapeutics and drivers of antifungal resistance. We outline their development, mechanisms of action and applications across sectors, and highlight environmental and evolutionary pressures shaping resistance. Integrating perspectives from microbiology, agriculture and public health, we argue that coordinated One Health stewardship and sustainable antifungal strategies are urgently needed to preserve the efficacy of these critical compounds.

Expression of TYK2 in human CRC-derived LAMP3+ CCR7+ cDCs

Tyk2 deletion in AKP organoids has no effect on CRLM

Innate lymphoid cells (ILCs) are crucial regulators of tissue immunity. Here, we demonstrate that pulmonary ILCs can sense fungal components, leading to their activation. Mechanistically, we identify Syk/p38-dependent signaling as one of the key drivers of ILC activation following fungal challenges. Aspergillus fumigatus infection reshaped this response in vivo, creating a cytokine milieu that promoted ILC3 induction. We identified interleukin (IL)-23, IL-1β, and TGF-β as drivers of ILC2 conversion and IL-23 and IL-1β as triggers for ILC1s obtaining an ILC3 phenotype in vitro. Moreover, adoptive ILC transfer into Rag2-/-Il2rg-/- mice restrained excessive inflammation, while ILCs lacking the intracellular non-receptor tyrosine kinase Tec showed enhanced ILC1 proliferation and reduced fungal burden. Consequently, transfer of Tec-deficient ILCs leads to better survival by enhancing antifungal immunity. These findings uncover hitherto unrecognized roles for ILCs as early modulators of antifungal immunity. Hence, targeting Tec signaling in ILCs may offer a therapeutic strategy to enhance antifungal immunity.

TYK2 deficiency in host mice promotes liver metastasis of AKP organoids seeded via the portal vein

Evaluation of TYK2 deletion in conditional mouse models

Tyrosine kinase 2 (TYK2) deficiency and loss or inhibition of kinase activity in men and mice leads to similar immune compromised phenotypes, predominantly through impairment of interferon (IFN) and interleukin 12 family responses. Here we relate the transcriptome changes to phenotypical changes observed in TYK2-deficient (Tyk2−/−) and TYK2 kinase-inactive (Tyk2K923E) mice in naïve splenic immune cells and upon ex vivo IFN treatment or in vivo tumor transplant infiltration. The TYK2 activities under homeostatic and both challenged conditions are highly cell-type-specific with respect to quantity and quality of transcriptionally dependent genes. The major impact of loss of TYK2 protein or kinase activity in splenic homeostatic macrophages, NK and CD8+ T cells and tumor-derived cytolytic cells is on IFN responses. While reportedly TYK2 deficiency leads to partial impairment of IFN-I responses, we identified cell-type-specific IFN-I-repressed gene sets completely dependent on TYK2 kinase activity. Reported kinase-inactive functions of TYK2 relate to signaling crosstalk, metabolic functions and cell differentiation or maturation. None of these phenotypes relates to respective enriched gene sets in the TYK2 kinase-inactive cell types. Nonetheless, the scaffolding functions of TYK2 are capable to change transcriptional activities at single gene levels and chromatin accessibility at promoter-distal regions upon cytokine treatment most prominently in CD8+ T cells. The cell-type-specific transcriptomic and epigenetic effects of TYK2 shed new light on the biology of this JAK family member and are relevant for current and future treatment of autoimmune and inflammatory diseases with TYK2 inhibitors.

Abstract Background Prostate cancer develops through malignant transformation of the prostate epithelium in a stepwise, mutation-driven process. Although activator protein-1 transcription factors such as JUN have been implicated as potential oncogenic drivers, the molecular programs contributing to prostate cancer progression are not fully understood. Methods We analyzed JUN expression in clinical prostate cancer samples across different stages and investigated its functional role in a Pten-deficient mouse model. We performed histopathological examinations, transcriptomic analyses and explored the senescence-associated secretory phenotype in the tumor microenvironment. Results Elevated JUN levels characterized early-stage prostate cancer and predicted improved survival in human and murine samples. Immune-phenotyping of Pten-deficient prostates revealed high accumulation of tumor-infiltrating leukocytes, particularly innate immune cells, neutrophils and macrophages as well as high levels of STAT3 activation and IL-1β production. Jun depletion in a Pten-deficient background prevented immune cell attraction which was accompanied by significant reduction of active STAT3 and IL-1β and accelerated prostate tumor growth. Comparative transcriptome profiling of prostate epithelial cells revealed a senescence-associated gene signature, upregulation of pro-inflammatory processes involved in immune cell attraction and of chemokines such as IL-1β, TNF-α, CCL3 and CCL8 in Pten-deficient prostates. Strikingly, JUN depletion reversed both the senescence-associated secretory phenotype and senescence-associated immune cell infiltration but had no impact on cell cycle arrest. As a result, JUN depletion in Pten-deficient prostates interfered with the senescence-associated immune clearance and accelerated tumor growth. Conclusions Our results suggest that JUN acts as tumor-suppressor and decelerates the progression of prostate cancer by transcriptional regulation of senescence- and inflammation-associated genes. This study opens avenues for novel treatment strategies that could impede disease progression and improve patient outcomes. Graphical Abstract

Abstract Candida albicans is the most common human fungal pathogen, causing diseases ranging from local to life-threating systemic infections. Tyrosine kinase 2 (TYK2), a crucial mediator in several cytokine signaling pathways, has been associated with protective functions in various microbial infections. However, its specific contribution in the immune response to fungal infections has remained elusive. In this study, we show that mice lacking TYK2 or its enzymatic activity exhibit enhanced resistance to C. albicans skin infections, limiting fungal spread and accelerating wound healing. Impaired TYK2-signaling prompted the formation of a distinctive layer of necrotic neutrophils around the fungal pathogens. Transcriptomic analysis revealed TYK2’s pivotal role in regulating interferon-inducible genes in neutrophils, thereby impacting their antifungal capacity during infection. Furthermore, we show that TYK2-dependent interferon-gamma (IFNγ) production contributes to fungal dissemination from the skin to the kidneys. Our study uncovers a hitherto unrecognized detrimental role of TYK2 in cutaneous C. albicans infections.