TYK2 signaling promotes the development of autoreactive CD8+ cytotoxic T lymphocytes and type 1 diabetes

Tyrosine kinase 2 (TYK2), a member of the JAK family, has attracted attention as a potential therapeutic target for autoimmune diseases. However, the role of TYK2 in CD8+ T cells and autoimmune type 1 diabetes (T1D) is poorly understood. In this study, we generate Tyk2 gene knockout non-obese diabetes (NOD) mice and demonstrate that the loss of Tyk2 inhibits the development of autoreactive CD8+ T-BET+ cytotoxic T lymphocytes (CTLs) by impairing IL-12 signaling in CD8+ T cells and the CD8+ resident dendritic cell-driven cross-priming of CTLs in the pancreatic lymph node (PLN). Tyk2-deficient CTLs display reduced cytotoxicity. Increased inflammatory responses in β-cells with aging are dampened by Tyk2 deficiency. Furthermore, treatment with BMS-986165, a selective TYK2 inhibitor, inhibits the expansion of T-BET+ CTLs, inflammation in β-cells and the onset of autoimmune T1D in NOD mice. Thus, our study reveals the diverse roles of TYK2 in driving the pathogenesis of T1D.

The mechanism of Tyk2 deficiency-induced immunosuppression in mice involves robust IL-10 production in macrophages

Macrophages are highly plastic in their pro-inflammatory/anti-inflammatory roles. Type I and II interferons (IFNs) are known to modulate macrophage activation. Tyrosine kinase 2 (Tyk2) has an intimate relationship with type I and II IFN signaling. Animal studies have shown that Tyk2 knock-out (KO) in mice is associated with reduced inflammatory responses in various mouse models of diseases. To investigate the role of Tyk2 in inflammation in more detail, we intraperitoneally injected heat-killed Propionibacterium acnes (P. acnes) to Tyk2 KO mice. P. acnes-induced acute peritoneal inflammation, assessed by neutrophil infiltration, was reduced in Tyk2 KO mice. The reduction was accompanied with diminished productions of inflammatory cytokines and an enhanced production of anti-inflammatory IL-10. Unexpectedly, pre-treatment of wild-type mice with the neutralizing antibodies for IFNs did not affect P. acnes-induced neutrophil infiltration. A neutralizing antibody for the IL-10 receptor in Tyk2 KO mice restored P. acnes-induced peritoneal inflammation. Enhanced production of IL-10 from Tyk2 KO peritoneal cells was suppressed by either the cyclooxygenase inhibitor diclofenac or protein kinase A inhibitor H-89. The level of prostaglandin E2 (PGE2) in the steady-state peritoneal cavity in Tyk2 KO mice was higher than that in wild-type mice. Tyk2 KO macrophages showed an enhanced CREB phosphorylation induced by P. acnes plus PGE2. Taken together, these results showed that Tyk2 deficiency potentiates the PGE2-protein kinase A-IL-10 pathway in macrophages, and thereby contributes to potentiation of the immunosuppressive phenotype.

TYK2 in Tumor Immunosurveillance

We review the history of the tyrosine kinase 2 (TYK2) as the founding member of the Janus kinase (JAK) family and outline its structure-function relation. Gene-targeted mice and hereditary defects of TYK2 in men have established the biological and pathological functions of TYK2 in innate and adaptive immune responses to infection and cancer and in (auto-)inflammation. We describe the architecture of the main cytokine receptor families associated with TYK2, which activate signal transducers and activators of transcription (STATs). We summarize the cytokine receptor activities with well characterized dependency on TYK2, the types of cells that respond to cytokines and TYK2 signaling-induced cytokine production. TYK2 may drive beneficial or detrimental activities, which we explain based on the concepts of tumor immunoediting and the cancer-immunity cycle in the tumor microenvironment. Finally, we summarize current knowledge of TYK2 functions in mouse models of tumor surveillance. The biology and biochemistry of JAKs, TYK2-dependent cytokines and cytokine signaling in tumor surveillance are well covered in recent reviews and the oncogenic properties of TYK2 are reviewed in the recent Special Issue ‘Targeting STAT3 and STAT5 in Cancer’ of Cancers.

Metastatic Thymoma Harboring a Deleterious BRCA2 Mutation Derives Durable Clinical Benefit from Olaparib

Thymomas comprise a group of rare epithelial neoplasms of the anterior mediastinum. Whereas localized disease carries a favorable prognosis, the majority of patients with metastatic thymomas experience progression or recurrence over a 10-year period. Although targeted therapies have become standard of care in many malignancies, no clinically actionable mutations have consistently been identified in metastatic thymomas. Here, we describe a patient with an aggressive thymoma complicated by extensive pleural metastases. Over a 16-year period, she progressed on multiple treatment regimens. To identify additional treatment options, tissue from a pleural metastasis was sent for next-generation sequencing, revealing mutations in BRCA2, tyrosine kinase 2, and SET domain containing 2. Based on supporting evidence for poly (ADP-ribose) polymerase (PARP) inhibition in other BRCA-mutated tumors, the patient was started on the PARP inhibitor olaparib. She derived significant clinical benefit from treatment, with imaging showing overall stabilization of her disease. Here, we review the genotyping results of her tumor and discuss the functional and clinical significance of the mutations in her cancer as well as implications for managing patients with advanced BRCA-mutant thymomas. KEY POINTS: Targeted therapy has yet to enter the standard clinical management of metastatic thymomas. Patients with BRCA2-mutant thymomas may benefit from poly (ADP-ribose) polymerase inhibition.

NK Cells Require Cell-Extrinsic and -Intrinsic TYK2 for Full Functionality in Tumor Surveillance and Antibacterial Immunity

Tyrosine kinase 2 (TYK2) is a widely expressed receptor-associated kinase that is involved in signaling by a variety of cytokines with important immune regulatory activities. Absence of TYK2 in mice results in impaired NK cell maturation and antitumor activity, although underlying mechanisms are largely unknown. Using conditional ablation of TYK2 in NK cells we show that TYK2 is required for IFN-γ production by NK cells in response to IL-12 and for an efficient immune defense against Listeria monocytogenes Deletion of TYK2 in NK cells did not impact NK cell maturation and IFN-γ production upon NK cell activating receptor (actR) stimulation. Similarly, NK cell-mediated tumor surveillance was unimpaired upon deletion of TYK2 in NK cells only. In line with the previously reported maturation-associated Ifng promoter demethylation, the less mature phenotype of Tyk2^-/- NK cells correlated with an increased CpG methylation at the Ifng locus. Treatment with the DNA hypomethylating agent 5-aza-2-deoxycytidine restored the ability of Tyk2^-/- NK cells to produce IFN-γ upon actR but not upon IL-12 stimulation. NK cell maturation was dependent on the presence of TYK2 in dendritic cells and could be rescued in Tyk2-deficient mice by treatment with exogenous IL-15/IL-15Rα complexes. IL-15 treatment also rescued the in vitro cytotoxicity defect and the impaired actR-induced IFN-γ production of Tyk2^-/- NK cells. Collectively, our findings provide the first evidence, to our knowledge, for a key role of TYK2 in the host environment in promoting NK cell maturation and antitumor activity.

Subtyping of Type 1 Diabetes as Classified by Anti-GAD Antibody, IgE Levels, and Tyrosine kinase 2 (TYK2) Promoter Variant in the Japanese

Objective

Type 1 diabetes (T1D) is known to be caused by Th1 cell-dependent autoimmunity. Recently, we reported that TYK2 promoter variant serves as a putative virus-induced diabetes susceptibility gene associated with deteriorated interferon-dependent antiviral response. TYK2 is also related to HIES, that is, Th2 cell-dependent. Therefore, TYK2 promoter variant may be also associated with the pathogenesis of T1D, modulating Th1/Th2 balance.

Research Design and Methods

We assessed the association between anti- GAD Ab, IgE levels, and TYK2 promoter variant among 313 T1D patients, 184 T2D patients, and 264 YH controls in the Japanese.

Results

T1D patients had elevated IgE (median, 56.7 U/ml; p < 0.0001) compared with T2D patients (22.5 U/ml) and controls (43.3 U/ml). Contrary to our expectations, there was no correlation between TYK2 promoter variant and IgE levels. We found that T1D could be subtyped as four groups based on anti-GAD Ab and IgE profile: Subtype 1, anti-GAD Ab positive and non-elevated IgE (47.0%); Subtype 2, anti-GAD Ab negative and non-elevated IgE (35.1%); Subtype 3, anti-GAD Ab positive and elevated IgE (10.9%); and Subtype 4, anti-GAD Ab negative and elevated IgE (7.0%). In Subtype 2, a significantly higher incidence was observed in T1D cases carrying the TYK2 promoter variant (OR, 2.60; 95%CI, 1.03–6.97; p = 0.032), and also showing a flu-like syndrome at diabetes onset (OR, 2.34; 95%CI, 1.27–4.35; p = 0.003).

Interpretation

Anti-GAD Ab and IgE profiling helps classifying T1D into four groups that recognize variable pathogenic bases of T1D.

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T1D can be subtyped into 4 groups based on anti-GAD Ab, IgE levels and TYK2 promoter variant.

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Only one subtype, without anti-GAD Ab or elevated IgE, was associated with TYK2 promoter variant and flu-like syndrome.

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Profiling of T1D by anti-GAD Ab and IgE levels is useful to realize the variable immuno-pathogenesis of T1D.

Since TYK2 gene is associated with T1D and HIES, we assessed the association between anti-GAD Ab, IgE levels, and TYK2 promoter variant in patients with T1D. Consequently, T1D can be subtyped into 4 distinct groups based on these clinical laboratory and genetic markers. Only those patients without anti-GAD Ab or elevated IgE were associated with TYK2 promoter variant and with flu-like syndrome at the diabetes onset, suggestive of association with virus-induced diabetes. This study describes the usefulness of subtyping of T1D with variable immunological bases and provides a clue to delineate the pathogenesis of T1D.

Transcriptomic Analysis on Responses of Murine Lungs to Pasteurella multocida Infection

Pasteurella multocida infection in cattle causes serious epidemic diseases and leads to great economic losses in livestock industry; however, little is known about the interaction between host and P. multocida in the lungs. To explore a fully insight into the host responses in the lungs during P. multocida infection, a mouse model of Pasteurella pneumonia was established by intraperitoneal infection, and then transcriptomic analysis of infected lungs was performed. P. multocida localized and grew in murine lungs, and induced inflammation in the lungs, as well as mice death. With transcriptomic analysis, approximately 10⁷ clean reads were acquired. 4236 differently expressed genes (DEGs) were detected during P. multocida infection, of which 1924 DEGs were up-regulated. By gene ontology (GO) and Kyoto encyclopedia of genes and genomes (KEGG) enrichments, 5,303 GO enrichments and 116 KEGG pathways were significantly enriched in the context of P. multocida infection. Interestingly, genes related to immune responses, such as pattern recognition receptors (PRRs), chemokines and inflammatory cytokines, were significantly up-regulated, suggesting the key roles of these genes in P. multocida infection. Transcriptomic data showed that IFN-γ/IL-17-related genes were increased, which were validated by qRT-PCR, ELISA, and immunoblotting. Our study characterized the transcriptomic profile of the lungs in mice upon Pasteurella infection, and our findings could provide valuable information with respect to better understanding the responses in mice during P. multocida infection.

Long-term in vitro and in vivo effects of γ-irradiated BCG on innate and adaptive immunity

BCG vaccination is associated with a reduced mortality from nonmycobacterial infections. This is likely to be mediated by a combination of innate-immune memory ("trained immunity") and heterologous effects on adaptive immunity. As such, BCG could be used to boost host immunity but not in immunocompromised hosts, as it is a live, attenuated vaccine. Therefore, we assessed whether killed γBCG has similar potentiating effects. In an in vitro model of trained immunity, human monocytes were incubated with γBCG for 24 h and restimulated after 6 d. Cytokine production and the role of pattern recognition receptors and histone methylation markers were assessed. The in vivo effects of γBCG vaccination were studied in a proof-of-principle trial in 15 healthy volunteers. γBCG induced trained immunity in vitro via the NOD2 receptor pathway and up-regulation of H3K4me3 histone methylation. However, these effects were less strong than those induced by live BCG. γBCG vaccination in volunteers had only minimal effects on innate immunity, whereas a significant increase in heterologous Th1/Th17 immunity was observed. Our results indicate that γBCG induces long-term training of innate immunity in vitro. In vivo, γBCG induces mainly heterologous effects on the adaptive-immune system, whereas effects on innate cytokine production are limited.

Dynamic tuning of lymphocytes: physiological basis, mechanisms, and function

Dynamic tuning of cellular responsiveness as a result of repeated stimuli improves the ability of cells to distinguish physiologically meaningful signals from each other and from noise. In particular, lymphocyte activation thresholds are subject to tuning, which contributes to maintaining tolerance to self-antigens and persisting foreign antigens, averting autoimmunity and immune pathogenesis, but allowing responses to strong, structured perturbations that are typically associated with acute infection. Such tuning is also implicated in conferring flexibility to positive selection in the thymus, in controlling the magnitude of the immune response, and in generating memory cells. Additional functional properties are dynamically and differentially tuned in parallel via subthreshold contact interactions between developing or mature lymphocytes and self-antigen-presenting cells. These interactions facilitate and regulate lymphocyte viability, maintain their functional integrity, and influence their responses to foreign antigens and accessory signals, qualitatively and quantitatively. Bidirectional tuning of T cells and antigen-presenting cells leads to the definition of homeostatic set points, thus maximizing clonal diversity.