The kinase TBK1 functions in dendritic cells to regulate T cell homeostasis, autoimmunity, and antitumor immunity

TANK-Binding Kinase 1 in the Pathogenesis and Treatment of Inflammation-Related Diseases

TANK-binding kinase 1 (TBK1) is a key signaling kinase involved in innate immune and inflammatory responses. TBK1 drives immune cells to participate in the inflammatory response by activating the NF-κB and interferon regulatory factor signaling pathways in immune cells, promoting the expression of pro-inflammatory genes, and regulating immune cell function. Thus, it plays a crucial role in initiating a signaling cascade that establishes an inflammatory environment. In inflammation-related diseases, TBK1 acts as a bridge linking inflammation to immunity, metabolism, or tumorigenesis, playing an important role in the pathogenesis of immune-mediated inflammatory diseases, metabolic, inflammatory syndromes, and inflammation-associated cancers by regulating the activation of inflammatory pathways and the production of inflammatory cytokines in cells. In this review, we focused on the mechanisms of TBK1 in immune cells and inflammatory-related diseases, providing new insights for further studies targeting TBK1 as a potential treatment for inflammation-related diseases. Thus, optimizing and investigating highly selective cell-specific TBK1 inhibitors is important for their application in these diseases.

TBK1 Targeting Is Identified as a Therapeutic Strategy to Enhance CAR T-Cell Efficacy Using Patient-Derived Organotypic Tumor Spheroids

Novel therapeutic strategies are needed to improve the efficacy of chimeric antigen receptor (CAR) T cells as a treatment of solid tumors. Multiple tumor microenvironmental factors are thought to contribute to resistance to CAR T-cell therapy in solid tumors, and appropriate model systems to identify and examine these factors using clinically relevant biospecimens are limited. In this study, we examined the activity of B7-H3-directed CAR T cells (B7-H3.CAR-T) using 3D microfluidic cultures of patient-derived organotypic tumor spheroids (PDOTS) and then confirmed the activity of B7-H3.CAR T cells in PDOTS. Although B7-H3 expression in PDOTS was associated with B7-H3.CAR-T sensitivity, mechanistic studies revealed dynamic upregulation of co-inhibitory receptors on CAR T-cells following target cell encounter that led to CAR T-cell dysfunction and limited efficacy against B7-H3-expressing tumors. PD-1 blockade restored CAR T-cell activity in monotypic and organotypic tumor spheroids with improved tumor control and upregulation of effector cytokines. Given the emerging role of TANK-binding kinase 1 (TBK1) as an immune evasion gene, we examined the effect of TBK1 inhibition on CAR T-cell efficacy. Similar to PD-1 blockade, TBK1 inhibition restored CAR T-cell activity in monotypic and organotypic tumor spheroids, prevented CAR T-cell dysfunction, and enhanced CAR T-cell proliferation. Inhibition or deletion of TBK1 also enhanced the sensitivity of cancer cells to immune-mediated killing. Taken together, our results demonstrate the feasibility and utility of ex vivo profiling of CAR T cells using PDOTS and suggest that targeting TBK1 could be used to enhance CAR T-cell efficacy by overcoming tumor-intrinsic and -extrinsic resistance mechanisms.

Amlexanox targeted inhibition of TBK1 regulates immune cell function to exacerbate DSS-induced inflammatory bowel disease

Amlexanox (ALX) is a small-molecule drug for the treatment of inflammatory, autoimmune, metabolic, and tumor diseases. At present, there are no studies on whether ALX has a therapeutic effect on inflammatory bowel disease (IBD). In this study, we used a mouse model of dextran sulfate sodium-induced colitis to investigate the effect of ALX-targeted inhibition of TBK1 on colitis. We found that the severity of colitis in mice was correlated with TBK1 expression. Notably, although ALX inhibited the activation of the TBK1-NF-κB/TBK1-IRF3 pro-inflammatory signaling pathway, it exacerbated colitis and reduced survival in mice. The results of drug safety experiments ruled out a relationship between this exacerbating effect and drug toxicity. In addition, ELISA results showed that ALX promoted the secretion of IL-1β and IFN-α, and inhibited the production of cytokines IL-6, TNF-α, IL-10, TGF-β, and secretory IgA. Flow cytometry results further showed that ALX promoted T-cell proliferation, activation, and differentiation, and thus played a pro-inflammatory role; also, ALX inhibited the generation of dendritic cells and the polarization of macrophages to M1 type, thus exerting anti-inflammatory effect. These data suggest that the regulation of ALX on the function of different immune cells is different, so the effect on the inflammatory response is bidirectional. In conclusion, our study demonstrates that simply inhibiting TBK1 in all immune cells is not effective for the treatment of colitis. Further investigation of the anti-inflammatory mechanism of ALX on dendritic cells and macrophages may provide a new strategy for the treatment of IBD.

Neuroglia in neurodegeneration: Amyotrophic lateral sclerosis and frontotemporal dementia

Amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD) are devastating neurodegenerative diseases sharing significant pathologic and genetic overlap, leading to consider these diseases as a continuum in the spectrum of their pathologic features. Although FTD compromises only specific brain districts, while ALS involves both the nervous system and the skeletal muscles, several neurocentric mechanisms are in common between ALS and FTD. Also, recent research has revealed the significant involvement of nonneuronal cells, particularly glial cells such as astrocytes, oligodendrocytes, microglia, and peripheral immune cells, in disease pathology. This chapter aims to provide an extensive overview of the current understanding of the role of glia in the onset and advancement of ALS and FTD, highlighting the recent implications in terms of prognosis and future treatment options.

Crosstalk and Prospects of TBK1 in Inflammation

BACKGROUND

TANK-binding kinase 1 (TBK1) is a pivotal mediator of innate immunity, activated by receptors such as mitochondrial antiviral signaling protein (MAVS), stimulator of interferon genes (STING), and TIR-domain-containing adaptor inducing interferon-β (TRIF). It modulates immune responses by exerting influence on the type I interferons (IFN-Is) signaling and the nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) pathways, Over the past few years, TBK1 multifaceted role in both immune and inflammatory responses is increasingly recognized.

METHODS AND RESULTS

This review aims to scrutinize how TBK1 operates within the NF-κB pathway and the interferon regulatory transcription factor 3 (IRF3)-dependent IFN-I pathways, highlighting the kinases and other molecules involved in these processes. This analysis reveals the distinctive characteristics of TBK1's involvement in these pathways. Furthermore, it has been observed that the role of TBK1 in exerting anti-inflammatory or pro-inflammatory effects is contingent upon varying pathological conditions, indicating a multifaceted role in immune regulation.

DISCUSSION

TBK1's evolving role in various diseases and the potential of TBK1 inhibitors as therapeutic agents are explored. Targeting TBK1 may provide new strategies for treating inflammatory disorders and autoimmune diseases associated with IFN-Is, warranting further investigation.

TBK1-Zyxin signaling controls tumor-associated macrophage recruitment to mitigate antitumor immunity

Mechanical control is fundamental for cellular localization within a tissue, including for tumor-associated macrophages (TAMs). While the innate immune sensing pathways cGAS-STING and RLR-MAVS impact the pathogenesis and therapeutics of malignant diseases, their effects on cell residency and motility remain incompletely understood. Here, we uncovered that TBK1 kinase, activated by cGAS-STING or RLR-MAVS signaling in macrophages, directly phosphorylates and mobilizes Zyxin, a key regulator of actin dynamics. Under pathological conditions and in STING or MAVS signalosomes, TBK1-mediated Zyxin phosphorylation at S143 facilitates rapid recruitment of phospho-Zyxin to focal adhesions, leading to subsequent F-actin reorganization and reduced macrophage migration. Intratumoral STING-TBK1-Zyxin signaling was evident in TAMs and critical in antitumor immunity. Furthermore, myeloid-specific or global disruption of this signaling decreased the population of CD11b+ F4/80+ TAMs and promoted PD-1-mediated antitumor immunotherapy. Thus, our findings identify a new biological function of innate immune sensing pathways by regulating macrophage tissue localization, thus providing insights into context-dependent mitigation of antitumor immunity.

TBK1 is involved in M-CSF-induced macrophage polarization through mediating the IRF5/IRF4 axis

TANK binding kinase 1 (TBK1) is an important kinase that is involved in innate immunity and tumor development. Macrophage colony-stimulating factor (M-CSF) regulates the differentiation and function of macrophages towards the immunosuppressive M2 phenotype in the glioblastoma multiforme microenvironment. The role of TBK1 in macrophages, especially in regulating macrophage polarization in response to M-CSF stimulation, remains unclear. Here, we found high TBK1 expression in human glioma-infiltrating myeloid cells and that phosphorylated TBK1 was highly expressed in M-CSF-stimulated macrophages but not in granulocyte-macrophage CSF-induced macrophages (granulocyte-macrophage-CSF is involved in the polarization of M1 macrophages). Conditional deletion of TBK1 in myeloid cells induced M-CSF-stimulated bone marrow-derived macrophages to exhibit a proinflammatory M1-like phenotype with increased protein expression of CD86, interleukin-1β and tumor necrosis factor-α, as well as decreased expression of arginase 1. Mechanistically, TBK1 deletion or inhibition by amlexanox or GSK8612 reduced the expression of the transcription factor interferon-regulatory factor (IRF)4 and increased the level of IRF5 activation in macrophages stimulated with M-CSF, leading to an M1-like profile with highly proinflammatory factors. IRF5 deletion reversed the effect of TBK1 inhibition on M-CSF-mediated macrophage polarization. Our findings suggest that TBK1 contributes to the regulation of macrophage polarization in response to M-CSF stimulation partly through the IRF5/IRF4 axis.

Mechanism of TBK1 activation in cancer cells

TANK-binding kinase 1 (TBK1) is a serine/threonine kinase with well-established roles as a central player in innate immune signaling. Dysregulation of TBK1 activity has been implicated in a variety of pathophysiologic conditions, including cancer. Generally, TBK1 acts as an oncogene and increased TBK1 activity, indicated by increased phosphorylation at the Ser172 residue, can be observed in multiple human cancers. TBK1 can be activated either by autophosphorylation of Ser172 or transphosphorylation at this site by upstream kinases. Serving as a hub for integrating numerous extracellular and intracellular signals, TBK1 can be activated through multiple signaling pathways. However, the direct upstream kinase responsible for TBK1 activation remains elusive, which limits our comprehensive understanding of its activation mechanism and potential therapeutic application targeting TBK1-related signaling especially in cancer. In this review, we summarize the findings on mechanisms of TBK1 activation in cancer cells and recent discoveries that shed light on the direct upstream kinases promoting TBK1 activation.

MARCH1 negatively regulates TBK1-mTOR signaling pathway by ubiquitinating TBK1

BACKGROUND

TBK1 positively regulates the growth factor-mediated mTOR signaling pathway by phosphorylating mTOR. However, it remains unclear how the TBK1-mTOR signaling pathway is regulated. Considering that STING not only interacts with TBK1 but also with MARCH1, we speculated that MARCH1 might regulate the mTOR signaling pathway by targeting TBK1. The aim of this study was to determine whether MARCH1 regulates the mTOR signaling pathway by targeting TBK1.

METHODS

The co-immunoprecipitation (Co-IP) assay was used to verify the interaction between MARCH1 with STING or TBK1. The ubiquitination of STING or TBK1 was analyzed using denatured co-immunoprecipitation. The level of proteins detected in the co-immunoprecipitation or denatured co-immunoprecipitation samples were determined by Western blotting. Stable knocked-down cells were constructed by infecting lentivirus bearing the related shRNA sequences. Scratch wound healing and clonogenic cell survival assays were used to detect the migration and proliferation of breast cancer cells.

RESULTS

We showed that MARCH1 played an important role in growth factor-induced the TBK1- mTOR signaling pathway. MARCH1 overexpression attenuated the growth factor-induced activation of mTOR signaling pathway, whereas its deficiency resulted in the opposite effect. Mechanistically, MARCH1 interacted with and promoted the K63-linked ubiquitination of TBK1. This ubiquitination of TBK1 then attenuated its interaction with mTOR, thereby inhibiting the growth factor-induced mTOR signaling pathway. Importantly, faster proliferation induced by MARCH1 deficiency was weakened by mTOR, STING, or TBK1 inhibition.

CONCLUSION

MARCH1 suppressed growth factors mediated the mTOR signaling pathway by targeting the STING-TBK1-mTOR axis.

PIKfyve controls dendritic cell function and tumor immunity

The modern armamentarium for cancer treatment includes immunotherapy and targeted therapy, such as protein kinase inhibitors. However, the mechanisms that allow cancer-targeting drugs to effectively mobilize dendritic cells (DCs) and affect immunotherapy are poorly understood. Here, we report that among shared gene targets of clinically relevant protein kinase inhibitors, high PIKFYVE expression was least predictive of complete response in patients who received immune checkpoint blockade (ICB). In immune cells, high PIKFYVE expression in DCs was associated with worse response to ICB. Genetic and pharmacological studies demonstrated that PIKfyve ablation enhanced DC function via selectively altering the alternate/non-canonical NF-κB pathway. Both loss of Pikfyve in DCs and treatment with apilimod, a potent and specific PIKfyve inhibitor, restrained tumor growth, enhanced DC-dependent T cell immunity, and potentiated ICB efficacy in tumor-bearing mouse models. Furthermore, the combination of a vaccine adjuvant and apilimod reduced tumor progression in vivo. Thus, PIKfyve negatively controls DCs, and PIKfyve inhibition has promise for cancer immunotherapy and vaccine treatment strategies.

IRF11 synergizes with STAT1 and STAT2 to promote type I IFN production

Interferon regulatory factor 11 (IRF11), a fish specific member of IRF family, is a transcription factor known for its positive role in teleost antiviral defense by regulating IFN expression. Despite its recognized function, the precise mechanism of IRF11 in type I IFNs production remains largely unknown. In this study, we identified IRF11 in Japanese eel, Anguilla japonica, (AjIRF11) and determined its involvement in the later phase of fish IFN production. Our results demonstrate that IRF11-induced IFN production operates through ISRE binding. Mutations in each ISRE site within the promoter of AjIFN2 or AjIFN4 abolished IRF11-mediated activation of IFN promoters. In addition, the overexpression of AjIRF11 does not significantly impact the activation of AjIFN promoters induced by RLR-related signaling pathway proteins. Furthermore, IRF11-knockdown in ZFLs (zebrafish liver cells) has no effect on the RLRs-induced expression of zebrafish IFN-φ1 and IFN-φ3, indicating that IRF11 is not involved in the RLR-mediated IFN production. However, AjIRF11 can form transcription complexes with AjSTAT1 or AjSTAT2, or form homo- or heterodimers with AjIRF1 to stimulate the transcription of type I IFNs. Overall, it is shown in this study that IRF11 can act synergistically with STAT1 and/or STAT2 for the induction of IFN.

PIKfyve, expressed by CD11c-positive cells, controls tumor immunity

Cancer treatment continues to shift from utilizing traditional therapies to targeted ones, such as protein kinase inhibitors and immunotherapy. Mobilizing dendritic cells (DC) and other myeloid cells with antigen presenting and cancer cell killing capacities is an attractive but not fully exploited approach. Here, we show that PIKFYVE is a shared gene target of clinically relevant protein kinase inhibitors and high expression of this gene in DCs is associated with poor patient response to immune checkpoint blockade (ICB) therapy. Genetic and pharmacological studies demonstrate that PIKfyve ablation enhances the function of CD11c+ cells (predominantly dendritic cells) via selectively altering the non-canonical NF-κB pathway. Both loss of Pikfyve in CD11c+ cells and treatment with apilimod, a potent and specific PIKfyve inhibitor, restrained tumor growth, enhanced DC-dependent T cell immunity, and potentiated ICB efficacy in tumor-bearing mouse models. Furthermore, the combination of a vaccine adjuvant and apilimod reduced tumor progression in vivo. Thus, PIKfyve negatively regulates the function of CD11c+ cells, and PIKfyve inhibition has promise for cancer immunotherapy and vaccine treatment strategies.

Emerging roles of TBK1 in cancer immunobiology

TANK-binding kinase 1 (TBK1) is a versatile serine/threonine protein kinase with established roles in innate immunity, metabolism, autophagy, cell death, and inflammation. While best known for its role in regulating innate immunity, TBK1 has emerged as a cancer cell-intrinsic immune evasion gene by virtue of its role in modulating cellular responses to inflammatory signals emanating from the immune system. Beyond its effect on cancer cells, TBK1 appears to regulate lymphoid and myeloid cells in the tumor immune microenvironment. In this review, we detail recent advances in our understanding of the tumor-intrinsic and -extrinsic roles and regulation of TBK1 in tumor immunity.

Identification of TBK1 inhibitors against breast cancer using a computational approach supported by machine learning

Introduction: The cytosolic Ser/Thr kinase TBK1 is of utmost importance in facilitating signals that facilitate tumor migration and growth. TBK1-related signaling plays important role in tumor progression, and there is need to work on new methods and workflows to identify new molecules for potential treatments for TBK1-affecting oncologies such as breast cancer. Methods: Here, we propose the machine learning assisted computational drug discovery approach to identify TBK1 inhibitors. Through our computational ML-integrated approach, we identified four novel inhibitors that could be used as new hit molecules for TBK1 inhibition. Results and Discussion: All these four molecules displayed solvent based free energy values of -48.78, -47.56, -46.78 and -45.47 Kcal/mol and glide docking score of -10.4, -9.84, -10.03, -10.06 Kcal/mol respectively. The molecules displayed highly stable RMSD plots, hydrogen bond patterns and MMPBSA score close to or higher than BX795 molecule. In future, all these compounds can be further refined or validated by in vitro as well as in vivo activity. Also, we have found two novel groups that have the potential to be utilized in a fragment-based design strategy for the discovery and development of novel inhibitors targeting TBK1. Our method for identifying small molecule inhibitors can be used to make fundamental advances in drug design methods for the TBK1 protein which will further help to reduce breast cancer incidence.

Role of TBK1 Inhibition in Targeted Therapy of Cancer

TANK-binding kinase 1 (TBK1) is a serine/threonine protein that plays a crucial role in various biological processes like immunity, autophagy, cell survival, and proliferation. The level and kinase activity of the TBK1 protein is regulated through post-translational modifications (PTMs). TBK1 mainly mediates the activation of IRF3/7 and NF-κB signaling pathways while also participating in the regulation of cellular activities such as autophagy, mitochondrial metabolism, and cell proliferation. TBK1 regulates immune, metabolic, inflammatory, and tumor occurrence and development within the body through these cellular activities. TBK1 kinase has emerged as a promising therapeutic target for tumor immunity. However, its molecular mechanism of action remains largely unknown. The identification of selective TBK1 small molecule inhibitors can serve as valuable tools for investigating the biological function of TBK1 protein and also as potential drug candidates for tumor immunotherapy. The current research progress indicates that some TBK1 inhibitors (compounds 15,16 and 21) exhibit certain antitumor effects in vitro culture systems. Here, we summarize the mechanism of action of TBK1 in tumors in recent years and the progress of small molecule inhibitors of TBK1.

Role of Ubiquitin Signaling in Modulating Dendritic Cell Function

As a professional antigen-presenting cell, dendritic cell (DC) plays an essential role in the connection of innate and adaptive immune responses. Ubiquitination is a post-translational mechanism of protein modification that plays a pivotal role in regulating DC maturation and function. To date, considerable progress has been made in understanding the underlying mechanisms of ubiquitination in modulating the function of DC in various diseases. Recent studies have emphasized that ubiquitin signaling in DCs plays crucial roles in regulating immune tolerance and functions, which can be promising targets for DC-based immunotherapy. In this chapter, we will focus on discussing the recent progress regarding the molecular mechanisms and functions of ubiquitination in DC-mediated immune homeostasis and responses.

Studies of Genetic and Proteomic Risk Factors of Amyotrophic Lateral Sclerosis Inspire Biomarker Development and Gene Therapy

Amyotrophic lateral sclerosis (ALS) is an incurable neurodegenerative disease affecting the upper and lower motor neurons, leading to muscle weakness, motor impairments, disabilities and death. Approximately 5-10% of ALS cases are associated with positive family history (familial ALS or fALS), whilst the remainder are sporadic (sporadic ALS, sALS). At least 50 genes have been identified as causative or risk factors for ALS. Established pathogenic variants include superoxide dismutase type 1 (SOD1), chromosome 9 open reading frame 72 (c9orf72), TAR DNA Binding Protein (TARDBP), and Fused In Sarcoma (FUS); additional ALS-related genes including Charged Multivesicular Body Protein 2B (CHMP2B), Senataxin (SETX), Sequestosome 1 (SQSTM1), TANK Binding Kinase 1 (TBK1) and NIMA Related Kinase 1 (NEK1), have been identified. Mutations in these genes could impair different mechanisms, including vesicle transport, autophagy, and cytoskeletal or mitochondrial functions. So far, there is no effective therapy against ALS. Thus, early diagnosis and disease risk predictions remain one of the best options against ALS symptomologies. Proteomic biomarkers, microRNAs, and extracellular vehicles (EVs) serve as promising tools for disease diagnosis or progression assessment. These markers are relatively easy to obtain from blood or cerebrospinal fluids and can be used to identify potential genetic causative and risk factors even in the preclinical stage before symptoms appear. In addition, antisense oligonucleotides and RNA gene therapies have successfully been employed against other diseases, such as childhood-onset spinal muscular atrophy (SMA), which could also give hope to ALS patients. Therefore, an effective gene and biomarker panel should be generated for potentially "at risk" individuals to provide timely interventions and better treatment outcomes for ALS patients as soon as possible.

Phosphatase Ssu72 Is Essential for Homeostatic Balance Between CD4+ T Cell Lineages

Ssu72, a dual-specificity protein phosphatase, not only participates in transcription biogenesis, but also affects pathophysiological functions in a tissue-specific manner. Recently, it has been shown that Ssu72 is required for T cell differentiation and function by controlling multiple immune receptor-mediated signals, including TCR and several cytokine receptor signaling pathways. Ssu72 deficiency in T cells is associated with impaired fine-tuning of receptor-mediated signaling and a defect in CD4+ T cell homeostasis, resulting in immune-mediated diseases. However, the mechanism by which Ssu72 in T cells integrates the pathophysiology of multiple immune-mediated diseases is still poorly elucidated. In this review, we will focus on the immunoregulatory mechanism of Ssu72 phosphatase in CD4+ T cell differentiation, activation, and phenotypic function. We will also discuss the current understanding of the correlation between Ssu72 in T cells and pathological functions which suggests that Ssu72 might be a therapeutic target in autoimmune disorders and other diseases.

Targeting TBK1 to overcome resistance to cancer immunotherapy

Despite the success of PD-1 blockade in melanoma and other cancers, effective treatment strategies to overcome resistance to cancer immunotherapy are lacking1,2. Here we identify the innate immune kinase TANK-binding kinase 1 (TBK1)3 as a candidate immune-evasion gene in a pooled genetic screen4. Using a suite of genetic and pharmacological tools across multiple experimental model systems, we confirm a role for TBK1 as an immune-evasion gene. Targeting TBK1 enhances responses to PD-1 blockade by decreasing the cytotoxicity threshold to effector cytokines (TNF and IFNγ). TBK1 inhibition in combination with PD-1 blockade also demonstrated efficacy using patient-derived tumour models, with concordant findings in matched patient-derived organotypic tumour spheroids and matched patient-derived organoids. Tumour cells lacking TBK1 are primed to undergo RIPK- and caspase-dependent cell death in response to TNF and IFNγ in a JAK-STAT-dependent manner. Taken together, our results demonstrate that targeting TBK1 is an effective strategy to overcome resistance to cancer immunotherapy.

Targeting TBK1 attenuates ocular inflammation in uveitis by antagonizing NF-κB signaling

Uveitis with complex pathogenesis is a kind of eye emergency involving refractory and blinding inflammation. Dysregulation of TANK binding kinase 1 (TBK1), which plays an important role in innate immunity, often leads to inflammatory diseases in various organs. However, the role of TBK1 in uveitis remains elusive. In this study, we identified that the mRNA expression level of TBK1 and its phosphorylation level were significantly increased in peripheral blood mononuclear cells (PBMCs) of patients with uveitis. Consistent with this, the expression of Tbk1 was elevated in the ocular tissues of uveitis rats and primary peritoneal macrophages while its phosphorylation levels, which present activation forms, were upregulated as well, accompanied by an increase in the level of nuclear factor-κB (NF-κB) and proinflammatory cytokines. In addition, inhibition of TBK1 may effectively reduce the inflammatory response of uveitis rats by blocking NF-κB entry into the nucleus and impeding the initiation of NLRP3 inflammasome- and caspase-1-mediated pyroptosis pathways.

Targeting micro-environmental pathways by PROTACs as a therapeutic strategy

Tumor microenvironment (TME) composes of multiple cell types and non-cellular components, which supports the proliferation, metastasis and immune surveillance evasion of tumor cells, as well as accounts for the resistance to therapies. Therefore, therapeutic strategies using small molecule inhibitors (SMIs) and antibodies to block potential targets in TME are practical for cancer treatment. Targeted protein degradation using PROteolysis-TArgeting Chimera (PROTAC) technic has several advantages over traditional SMIs and antibodies, including overcoming drug resistance. Thus many PROTACs are currently under development for cancer treatment. In this review, we summarize the recent progress of PROTAC development that target TME pathways and propose the potential direction of future PROTAC technique to advance as novel cancer treatment options.

Endothelial deletion of TBK1 contributes to BRB dysfunction via CXCR4 phosphorylation suppression

Blood-retinal barrier (BRB) dysfunction has been recognized as an early pathological feature in common eye diseases that cause blindness. The breakdown of endothelial cell-to-cell junctions is the main reason for BRB dysfunction, yet our understanding of junctional modulation remains limited. Here, we demonstrated that endothelial-specific deletion of TBK1 (Tbk1^ΔEC) disrupted retinal vascular development, and induced vascular leakage. LC-MS/MS proteomic analysis was used to identify candidate substrates of TBK1. We found that TBK1 interacted with CXCR4, and the phosphorylation level of CXCR4-Serine 355 (Ser355) was decreased in Tbk1^ΔEC retina samples. Furthermore, TBK1-mediated phosphorylation of CXCR4 at Ser355 played an indispensable role in maintaining endothelial junctions. Interestingly, we also detected an increased expression of TBK1 in diabetic retinopathy samples, which suggested an association between TBK1 and the disease. Taken together, these results provided insight into the mechanisms involved in the regulation of endothelial cell-to-cell junctions via TBK1-dependent CXCR4 phosphorylation.

Emerging Role of Dendritic Cell Intervention in the Treatment of Inflammatory Bowel Disease

Dendritic cells (DCs) are the most important antigen-presenting cells and are pivotal in initiating effective adaptive immune responses to induce immune tolerance and maintain immune homeostasis. Inflammatory bowel disease (IBD), including Crohn’s disease and ulcerative colitis, is chronic, intestinal inflammatory and autoimmune disorder. DCs participate in IBD pathogenesis. This review is aimed at briefly discussing the role of DCs in IBD and the relationship between them and highlighting the prominent role of these cells in the treatment of these disorders.

Ezh2 competes with p53 to license lncRNA Neat1 transcription for inflammasome activation

Inflammasome contributes to the pathogenesis of various inflammatory diseases, but the epigenetic mechanism controlling its activation remains elusive. Here, we found that the histone methyltransferase Ezh2 mediates the activation of multiple types of inflammasomes in macrophages/microglia independent of its methyltransferase activity and thus promotes inflammasome-related pathologies. Mechanistically, Ezh2 functions through its SANT2 domain to maintain the enrichment of H3K27 acetylation in the promoter region of the long noncoding RNA (lncRNA) Neat1, thereby promoting chromatin accessibility and facilitating p65-mediated transcription of Neat1, which is a critical mediator of inflammasome assembly and activation. In addition, the tumour suppressor protein p53 competes with Ezh2 for the same binding region in the Neat1 promoter and thus antagonises Ezh2-induced Neat1 transcription and inflammasome activation. Therefore, loss of Ezh2 strongly promotes the binding of p53, which recruits the deacetylase SIRT1 for H3K27 deacetylation of the Neat1 promoter and thus suppresses Neat1 transcription and inflammasome activation. Overall, our study demonstrates an epigenetic mechanism involved in modulating inflammasome activation through an Ezh2/p53 competition model and highlights a novel function of Ezh2 in maintaining H3K27 acetylation to support lncRNA Neat1 transcription.

Direct and indirect effects of IFN-α2b in malignancy treatment: not only an archer but also an arrow

Interferon-α2b (IFN-α2b) is a highly active cytokine that belongs to the interferon-α (IFN-α) family. IFN-α2b has beneficial antiviral, antitumour, antiparasitic and immunomodulatory activities. Direct and indirect antiproliferative effects of IFN-α2b have been found to occur via multiple pathways, mainly the JAK-STAT pathway, in certain cancers. This article reviews mechanistic studies and clinical trials on IFN-α2b. Potential regulators of the function of IFN-α2b were also reviewed, which could be utilized to relieve the poor response to IFN-α2b. IFN-α2b can function not only by enhancing the systematic immune response but also by directly killing tumour cells. Different parts of JAK-STAT pathway activated by IFN-α2b, such as interferon alpha and beta receptors (IFNARs), Janus kinases (JAKs) and IFN‐stimulated gene factor 3 (ISGF3), might serve as potential target for enhancing the pharmacological action of IFN-α2b. Despite some issues that remain to be solved, based on current evidence, IFN-α2b can inhibit disease progression and improve the survival of patients with certain types of malignant tumours. More efforts should be made to address potential adverse effects and complications.

TBK1 Is Required for Host Defense Functions Distinct from Type I IFN Expression and Myeloid Cell Recruitment in Murine Streptococcus pneumoniae Pneumonia

Bacterial pneumonia induces the rapid recruitment and activation of neutrophils and macrophages into the lung, and these cells contribute to bacterial clearance and other defense functions. TBK1 (TANK-binding kinase 1) performs many functions, including activation of the type I IFN pathway and regulation of autophagy and mitophagy, but its contribution to antibacterial defenses in the lung is unclear. We previously showed that lung neutrophils upregulate mRNAs for TBK1 and its accessory proteins during Streptococcus pneumoniae pneumonia, despite low or absent expression of type I IFN in these cells. We hypothesized that TBK1 performs key antibacterial functions in pneumonia apart from type I IFN expression. Using TBK1 null mice, we show that TBK1 contributes to antibacterial defenses and promotes bacterial clearance and survival. TBK1 null mice express lower concentrations of many cytokines in the infected lung. Conditional deletion of TBK1 with LysMCre results in TBK1 deletion from macrophages but not neutrophils. LysMCre TBK1 mice have no defect in cytokine expression, implicating a nonmacrophage cell type as a key TBK1-dependent cell. TBK1 null neutrophils have no defect in recruitment to the infected lung but show impaired activation of p65/NF-κB and STAT1 and lower expression of reactive oxygen species, IFNγ, and IL12p40. TLR1/2 and 4 agonists each induce phosphorylation of TBK1 in neutrophils. Surprisingly, neutrophil TBK1 activation in vivo does not require the adaptor STING. Thus, TBK1 is a critical component of STING-independent antibacterial responses in the lung, and TBK1 is necessary for multiple neutrophil functions.

Clonally expanded CD8 T cells characterize amyotrophic lateral sclerosis-4

Amyotrophic lateral sclerosis (ALS) is a heterogenous neurodegenerative disorder that affects motor neurons and voluntary muscle control1. ALS heterogeneity includes the age of manifestation, the rate of progression and the anatomical sites of symptom onset. Disease-causing mutations in specific genes have been identified and define different subtypes of ALS1. Although several ALS-associated genes have been shown to affect immune functions2, whether specific immune features account for ALS heterogeneity is poorly understood. Amyotrophic lateral sclerosis-4 (ALS4) is characterized by juvenile onset and slow progression3. Patients with ALS4 show motor difficulties by the time that they are in their thirties, and most of them require devices to assist with walking by their fifties. ALS4 is caused by mutations in the senataxin gene (SETX). Here, using Setx knock-in mice that carry the ALS4-causative L389S mutation, we describe an immunological signature that consists of clonally expanded, terminally differentiated effector memory (TEMRA) CD8 T cells in the central nervous system and the blood of knock-in mice. Increased frequencies of antigen-specific CD8 T cells in knock-in mice mirror the progression of motor neuron disease and correlate with anti-glioma immunity. Furthermore, bone marrow transplantation experiments indicate that the immune system has a key role in ALS4 neurodegeneration. In patients with ALS4, clonally expanded TEMRA CD8 T cells circulate in the peripheral blood. Our results provide evidence of an antigen-specific CD8 T cell response in ALS4, which could be used to unravel disease mechanisms and as a potential biomarker of disease state.

Therapeutic targeting of TANK-binding kinase signaling towards anticancer drug development: Challenges and opportunities

TANK-binding kinase 1 (TBK1) plays a fundamental role in regulating the cellular responses and controlling several signaling cascades. It regulates inflammatory, interferon, NF-κB, autophagy, and Akt pathways. Post-translational modifications (PTM) of TBK1 control its action and subsequent cellular signaling. The dysregulation of the TBK1 pathway is correlated to many pathophysiological conditions, including cancer, that implicates the promising therapeutic advantage for targeting TBK1. The present study summarizes current updates on the molecular mechanisms and cancer-inducing roles of TBK1. Designed inhibitors of TBK1 are considered a potential therapeutic agent for several diseases, including cancer. Data from pre-clinical tumor models recommend that the targeting of TBK1 could be an attractive strategy for anti-tumor therapy. This review further highlighted the therapeutic potential of potent and selective TBK1 inhibitors, including Amlexanox, Compound II, BX795, MRT67307, SR8185 AZ13102909, CYT387, GSK8612, BAY985, and Domainex. These inhibitors may be implicated to facilitate therapeutic management of cancer and TBK1-associated diseases in the future.

Contribution of IL-38 in Lung Immunity during Pseudomonas Aeruginosa-induced Pneumonia

OBJECTIVE

Interleukin-38 (IL-38), a new type of cytokine, is involved in processes such as tissue repair, inflammatory response, and immune response. However, its function in pneumonia caused by Pseudomonas aeruginosa (P. aeruginosa) is still unclear.

METHODS

In this study, we detected circulating IL-38 and cytokines such as IL-1β, IL-6, IL-17A, TNF-α, IL-8, and IL-10 in adults affected by early stage pneumonia caused by P. aeruginosa. Collected clinical data of these patients, such as the APACHE II score, levels of PCT, and oxygenation index when they entering the ICU. Using P. aeruginosa-induced pneumonia WT murine model to evaluate the effect of IL-38 on Treg differentiation, cell apoptosis, survival, tissue damage, inflammation, and bacterial removal.

RESULTS

In clinical research, although IL-38 is significantly increased during the early stages of clinical P. aeruginosa pneumonia, the concentration of IL-38 in the serum of patients who died with P. aeruginosa pneumonia was relatively lower than that of surviving patients. It reveals IL-38 may insufficiently secreted in patients who died with P. aeruginosa pneumonia. Besides, the serum IL-38 level of patients with P. aeruginosa pneumonia on the day of admission to the ICU showed significantly positive correlations with IL-10 and the PaO2/FiO2 ratio but negative correlations with IL-1β, IL-6, IL-8, IL-17, TNF-α, APACHE II score, and PCT In summary, IL-38 might be a molecule for adjuvant therapy in P. aeruginosa pneumonia. In experimental animal models, first recombinant IL-38 improved survival, whereas anti-IL-38 antibody reduced survival in the experimental pneumonia murine model. Secondly, IL-38 exposure reduced the inflammatory response, as suggested by the lung injury, and reduced cytokine levels (IL-1β, IL-6, IL- 17A, TNF-α, and IL-8, but not IL-10). It also increased bacterial clearance and reduced cell apoptosis in the lungs. Furthermore, IL-38 was shown to reduce TBK1 expression in vitro when naive CD4+ T lymphocytes were differentiated to Tregs and played a protective role in P. aeruginosa pneumonia.

CONCLUSIONS

To summarize, the above findings provide additional insights into the mechanism of IL-38 in the treatment of P. aeruginosa pneumonia.

The role of TBK1 in cancer pathogenesis and anticancer immunity

The TANK-binding kinase 1 (TBK1) is a serine/threonine kinase belonging to the non-canonical inhibitor of nuclear factor-κB (IκB) kinase (IKK) family. TBK1 can be activated by pathogen-associated molecular patterns (PAMPs), inflammatory cytokines, and oncogenic kinases, including activated K-RAS/N-RAS mutants. TBK1 primarily mediates IRF3/7 activation and NF-κB signaling to regulate inflammatory cytokine production and the activation of innate immunity. TBK1 is also involved in the regulation of several other cellular activities, including autophagy, mitochondrial metabolism, and cellular proliferation. Although TBK1 mutations have not been reported in human cancers, aberrant TBK1 activation has been implicated in the oncogenesis of several types of cancer, including leukemia and solid tumors with KRAS-activating mutations. As such, TBK1 has been proposed to be a feasible target for pharmacological treatment of these types of cancer. Studies suggest that TBK1 inhibition suppresses cancer development not only by directly suppressing the proliferation and survival of cancer cells but also by activating antitumor T-cell immunity. Several small molecule inhibitors of TBK1 have been identified and interrogated. However, to this point, only momelotinib (MMB)/CYT387 has been evaluated as a cancer therapy in clinical trials, while amlexanox (AMX) has been evaluated clinically for treatment of type II diabetes, nonalcoholic fatty liver disease, and obesity. In this review, we summarize advances in research into TBK1 signaling pathways and regulation, as well as recent studies on TBK1 in cancer pathogenesis. We also discuss the potential molecular mechanisms of targeting TBK1 for cancer treatment. We hope that our effort can help to stimulate the development of novel strategies for targeting TBK1 signaling in future approaches to cancer therapy.

B cell-intrinsic TBK1 is essential for germinal center formation during infection and vaccination in mice

The germinal center (GC) is a site where somatic hypermutation and clonal selection are coupled for antibody affinity maturation against infections. However, how GCs are formed and regulated is incompletely understood. Here, we identified an unexpected role of Tank-binding kinase-1 (TBK1) as a crucial B cell-intrinsic factor for GC formation. Using immunization and malaria infection models, we show that TBK1-deficient B cells failed to form GC despite normal Tfh cell differentiation, although some malaria-infected B cell-specific TBK1-deficient mice could survive by GC-independent mechanisms. Mechanistically, TBK1 phosphorylation elevates in B cells during GC differentiation and regulates the balance of IRF4/BCL6 expression by limiting CD40 and BCR activation through noncanonical NF-κB and AKTT308 signaling. In the absence of TBK1, CD40 and BCR signaling synergistically enhanced IRF4 expression in Pre-GC, leading to BCL6 suppression, and therefore failed to form GCs. As a result, memory B cells generated from TBK1-deficient B cells fail to confer sterile immunity upon reinfection, suggesting that TBK1 determines B cell fate to promote long-lasting humoral immunity.

Myeloid cell TBK1 restricts inflammatory responses

Proinflammatory cytokine production by innate immune cells plays a crucial role in inflammatory diseases, but the molecular mechanisms controlling the inflammatory responses are poorly understood. Here, we show that TANK-binding kinase 1 (TBK1) serves as a vital regulator of proinflammatory macrophage function and protects against tissue inflammation. Myeloid cell-conditional Tbk1 knockout (MKO) mice spontaneously developed adipose hypertrophy and metabolic disorders at old ages, associated with increased adipose tissue M1 macrophage infiltration and proinflammatory cytokine expression. When fed with a high-fat diet, the Tbk1-MKO mice also displayed exacerbated hepatic inflammation and insulin resistance, developing symptoms of nonalcoholic steatohepatitis. Furthermore, myeloid cell-specific TBK1 ablation exacerbates inflammation in experimental colitis. Mechanistically, TBK1 functions in macrophages to suppress the NF-κB and MAP kinase signaling pathways and thus attenuate induction of proinflammatory cytokines, particularly IL-1β. Ablation of IL-1 receptor 1 (IL-1R1) eliminates the inflammatory symptoms of Tbk1-MKO mice. These results establish TBK1 as a pivotal anti-inflammatory mediator that restricts inflammation in different disease models.

Development and validation of a survival model for esophageal adenocarcinoma based on autophagy-associated genes

Autophagy is a highly conserved catabolic process which has been implicated in esophageal adenocarcinoma (EAC). We sought to investigate the biological functions and prognostic value of autophagy-related genes (ARGs) in EAC. A total of 21 differentially expressed ARGs were identified between EAC and normal samples. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis were then applied for the differentially expressed ARGs in EAC, and the protein-protein interaction (PPI) network was established. Cox survival analysis and Lasso regression analysis were performed to establish a prognostic prediction model based on nine overall survival (OS)-related ARGs (CAPN1, GOPC, TBK1, SIRT1, ARSA, BNIP1, ERBB2, NRG2, PINK1). The 9-gene prognostic signature significantly stratified patient outcomes in The Cancer Genome of Atlas (TCGA)-EAC cohort and was considered as an independently prognostic predictor for EAC patients. Moreover, Gene set enrichment analysis (GSEA) analyses revealed several important cellular processes and signaling pathways correlated with the high-risk group in EAC. This prognostic prediction model was confirmed in an independent validation cohort (GSE13898) from The Gene Expression Omnibus (GEO) database. We also developed a nomogram with a concordance index of 0.78 to predict the survival possibility of EAC patients by integrating the risk signature and clinicopathological features. The calibration curves substantiated favorable concordance between actual observation and nomogram prediction. Last but not least, Erb-B2 Receptor Tyrosine Kinase 2 (ERBB2), a member of the prognostic gene signature, was identified as a potential therapeutic target for EAC patients. To sum up, we established and verified a novel prognostic prediction model based on ARGs which could optimize the individualized survival prediction in EAC.

Human TBK1 deficiency leads to autoinflammation driven by TNF-induced cell death

TANK binding kinase 1 (TBK1) regulates IFN-I, NF-κB, and TNF-induced RIPK1-dependent cell death (RCD). In mice, biallelic loss of TBK1 is embryonically lethal. We discovered four humans, ages 32, 26, 7, and 8 from three unrelated consanguineous families with homozygous loss-of-function mutations in TBK1. All four patients suffer from chronic and systemic autoinflammation, but not severe viral infections. We demonstrate that TBK1 loss results in hypomorphic but sufficient IFN-I induction via RIG-I/MDA5, while the system retains near intact IL-6 induction through NF-κB. Autoinflammation is driven by TNF-induced RCD as patient-derived fibroblasts experienced higher rates of necroptosis in vitro, and CC3 was elevated in peripheral blood ex vivo. Treatment with anti-TNF dampened the baseline circulating inflammatory profile and ameliorated the clinical condition in vivo. These findings highlight the plasticity of the IFN-I response and underscore a cardinal role for TBK1 in the regulation of RCD.

Induction of antigen-specific Treg cells in treating autoimmune uveitis via bystander suppressive pathways without compromising anti-tumor immunity

BACKGROUND

Induction of autoantigen-specific Treg cells that suppress tissue-specific autoimmunity without compromising beneficial immune responses is the holy-grail for immunotherapy to autoimmune diseases.

METHODS

In a model of experimental autoimmune uveitis (EAU) that mimics human uveitis, ocular inflammation was induced by immunization with retinal antigen interphotoreceptor retinoid-binding protein (IRBP). Mice were given intraperitoneal injection of αCD4 antibody (Ab) after the onset of disease, followed by administration of IRBP. EAU was evaluated clinically and functionally. Splenocytes, CD4⁺CD25^- and CD4⁺CD25⁺ T cells were sorted and cultured with IRBP or αCD3 Ab. T cell proliferation and cytokine production were assessed.

FINDINGS

The experimental approach resulted in remission of ocular inflammation and rescue of visual function in mice with established EAU. Mechanistically, the therapeutic effect was mediated by induction of antigen-specific Treg cells that inhibited IRBP-driven Th17 response in TGF-β and IL-10 dependent fashion. Importantly, the Ab-mediated immune tolerance could be achieved in EAU mice by administration of retinal autoantigens, arrestin but not limited to IRBP only, in an antigen-nonspecific bystander manner. Further, these EAU-suppressed tolerized mice did not compromise their anti-tumor T immunity in melanoma model.

INTERPRETATION

We successfully addressed a specific immunotherapy of EAU by in vivo induction of autoantigen-specific Treg cells without compromising host overall T cell immunity, which should have potential implication for patients with autoimmune uveitis.

FUNDING

This study was supported by the Natural Science Foundation of Guangdong Province and the Fundamental Research Fund of the State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center.

Amlexanox enhances the antitumor effect of anti-PD-1 antibody

Cancer immunotherapy, especially treatment with monoclonal antibodies (mAbs) that block programmed cell death-1 (PD-1)/programmed cell death-ligand 1 (PD-L1) signaling, has attracted attention as a new therapeutic option for cancer. However, only a limited number of patients have responded to this treatment approach. In this study, we searched for compounds that enhance the efficacy of anti-PD-1 mAb using mixed lymphocyte reaction (MLR), which is a mixed culture system of the two key cells (dendritic and T cells) involved in tumor immunity. We found that amlexanox enhanced production of interferon (IFN)-γ, an indicator of T cell activation, by anti-PD-1 mAb. Amlexanox also induced PD-L1 expression in dendritic cells in MLR, whereas it did not stimulate interleukin-2 production by Jurkat T cells. These results suggest that amlexanox acts on dendritic cells, not T cells, in MLR. Furthermore, it enhanced the antitumor effect of the anti-PD-1 mAb in vivo in a mouse tumor-bearing model. The combination of amlexanox and anti-PD-1 mAb increased the expression of Ifng encoding IFN-γ, IFN-γ-related genes, Cd274 encoding PD-L1, and cytotoxic T cell-related genes in tumors. In conclusion, amlexanox stimulates the antitumor effect of anti-PD-1 mAb by acting on dendritic cells, which in turn activates cytotoxic T cells in tumors.

A review on the role of TANK-binding kinase 1 signaling in cancer

TANK-binding kinase 1 (TBK1) regulates various biological processes including, NF-κB signaling, immune response, autophagy, cell division, Ras-mediated oncogenesis, and AKT pro-survival signaling. Enhanced TBK1 activity is associated with autoimmune diseases and cancer, suggesting its role in therapeutic targeting of interferonopathies. In addition, dysregulation of TBK1 activity promotes several inflammatory disorders and oncogenesis. Structural and biochemical study reports provide the molecular process of TBK1 activation and recap the substrate selection about TBK1. This review summarizes recent findings on the molecular mechanisms by which TBK1 is involved in cancer signaling. The IKK-ε and TBK1 are together associated with inflammatory diseases by inducing type I IFNs. Furthermore, TBK1 signaling regulates radiation-induced epithelial-mesenchymal transition by controlling phosphorylation of GSK-3β and expression of Zinc finger E-box-binding homeobox 1, suggesting, TBK1 could be targeted for radiotherapy-induced metastasis therapy. Despite a considerable increase in the list of TBK1 inhibitors, only a few has potential to control cancer. Among them, a compound BX795 is considered a potent and selective inhibitor of TBK1. We discussed the therapeutic potential of small-molecule inhibitors of TBK1, particularly those with high selectivity, which will enable further exploration in the therapeutic management of cancer and inflammatory diseases.

TANK-binding kinase 1 (TBK1): An emerging therapeutic target for drug discovery

Dysregulation of TANK-binding kinase 1 (TBK1) homeostasis leads to the occurrence and progression of many diseases, such as inflammation, autoimmune diseases, metabolic diseases, and cancer. Therefore, there is a need to develop TBK1 inhibitors as therapeutic agents. In this review, we highlight the diverse biological functions of TBK1 and summarize the promising small-molecule inhibitors of TBK1 that have the potential to be developed as therapeutic candidates.

SENP3 senses oxidative stress to facilitate STING-dependent dendritic cell antitumor function

STING-dependent cytosolic DNA sensing in dendritic cells (DCs) initiates antitumor immune responses, but how STING signaling is metabolically regulated in the tumor microenvironment remains unknown. Here, we show that oxidative stress is required for STING-induced DC antitumor function through a process that directs SUMO-specific protease 3 (SENP3) activity. DC-specific deletion of Senp3 drives tumor progression by blunting STING-dependent type-I interferon (IFN) signaling in DCs and dampening antitumor immune responses. DC-derived reactive oxygen species (ROS) trigger SENP3 accumulation and the SENP3-IFI204 interaction, thereby catalyzing IFI204 deSUMOylation and boosting STING signaling activation in mice. Consistently, SENP3 senses ROS to facilitate STING-dependent DC activity in tissue samples from colorectal cancer patients. Our results reveal that oxidative stress as a metabolic regulator promotes STING-mediated DC antitumor immune responses and highlights SENP3 as an overflow valve for STING signaling induction in the metabolically abnormal tumor microenvironment.

TBK1/IKKε Negatively Regulate LPS-Induced Neutrophil Necroptosis and Lung Inflammation

ABSTRACT

Cell necroptosis, a form of regulated inflammatory cell death, is one of the mechanisms that controls cell release of inflammatory mediators from innate immune cells, such as polymorphonuclear neutrophils (PMNs), and critically regulates the progress of inflammation. Cell necroptosis features receptor-interacting protein (RIPK) 1 activation and necroptosome formation. This leads to loss of plasma membrane integrity, the release of cell contents into the extracellular space, and subsequent increased inflammation. Here, we report an intra-PMN mechanism of negative regulation of necroptosis mediated through TBK1/IKKε. Using an in vivo mouse model of intratracheal injection (i.t.) of LPS and in vitro LPS stimulation of mouse PMN, we found that LPS-TLR4 signaling in PMNs activates and phosphorylates TBK1 and IKKε, which in turn suppress LPS-induced formation of the RIPK1-RIPK3-MLKL (necrosome) complex. TBK1 dysfunction by knockdown or inhibitor significantly increases the phosphorylation of RIPK1 (∼67%), RIPK3 (∼68%), and MLKL (∼50%) and promotes RIPK1-RIPK3 and RIPK3-MLKL interactions and increases PMN necroptosis (∼83%) in response to LPS, with subsequent augmented lung inflammation. These findings suggest that the LPS-TLR4-TBK1 axis serves as a negative regulator for PMN necroptosis and might be a therapeutic target for modulating PMN death and inflammation.

Expanding the View of IKK: New Substrates and New Biology

The inhibitor of kappa B kinase (IKK) family consists of IKKα, IKKβ, and the IKK-related kinases TBK1 and IKKε. These kinases are considered master regulators of inflammation and innate immunity via their control of the transcription factors NF-κB, IRF3, and IRF7. Novel phosphorylated substrates have been attributed to these kinases, a subset of which is not directly related to either inflammation or innate immunity. These findings have greatly expanded the perspectives on the biological activities of these kinases. In this review we highlight some of the novel substrates for this kinase family and discuss the biological implications of these phosphorylation events.

TANK-Binding Kinase 1 (TBK1) Serves as a Potential Target for Hepatocellular Carcinoma by Enhancing Tumor Immune Infiltration

BACKGROUND

Numerous cancer types present the aberrant TANK-binding kinase 1 (TBK1) expression, which plays an important role in driving inflammation and innate immunity. However, the prognostic role of TBK1 and its relationship with immune cell infiltration in hepatocellular carcinoma (HCC) remain unclear.

METHODS

The expression and prognostic value of TBK1 was analyzed by Tumor Immune Estimation Resource (TIMER), Kaplan-Meier plotter and Gene Expression Profiling Interactive Analysis (GEPIA), Clinical Proteomic Tumor Analysis Consortium (CPTAC) and further confirmed in the present cohort of patients with HCC. The association between TBK1 and HCC immune infiltrates, and its potential mechanism were investigated via analyses of the Tumor Immune Estimation Resource, tumor-immune system interactions database (TISIDB), CIBERSORT, STRING, and Metascape. The effect of TBK1 on immune infiltrates and the therapeutic value of targeting TBK1 were further investigated in a HCC mouse model by treatment with a TBK1 antagonist.

RESULTS

The level of TBK1 expression in HCC was higher than that measured in normal tissues, and associated with poorer overall survival (GEPIA: hazard ratio [HR]=1.80, P=0.038; Kaplan-Meier plotter: HR=1.87, P<0.001; CPTAC: HR=2.23, P=0.007; Our cohort: HR=2.92, P=0.002). In addition, high TBK1 expression was found in HCC with advanced TNM stage and identified as an independent poor prognostic factor for overall survival among patients with HCC. In terms of immune infiltration, tumor tissues from HCC patients with high TBK1 expression had a low proportion of CD8+ T cells, and TBK1 expression did not show prognostic value in HCC patients with enriched CD8+ T cells. Furthermore, TBK1 expression was positively correlated with the markers of T cell exhaustion and immunosuppressive cells in the HCC microenvironment. Mechanistically, the promotion of HCC immunosuppression by TBK1 was involved in the regulation of inflammatory cytokines. In vivo experiments revealed that treatment with a TBK1 antagonist delayed HCC growth by increasing the number of tumor-infiltrating CD8+ T cells.

CONCLUSIONS

The up-regulated expression of TBK1 may be useful in predicting poor prognosis of patients with HCC. In addition, TBK1, which promotes the HCC immunosuppressive microenvironment, may be a potential immunotherapeutic target for patients with HCC.

Dendritic cells transduced with TIPE-2 recombinant adenovirus induces T cells suppression

INTRODUCTION

TIPE-2 has been identified as a negative regulator of both innate and adaptive immunity and is involved in several inflammatory diseases. However, the role of immune suppression of dendritic cells (DCs) transduced with TIPE-2 has not been well studied.

METHODS

In this study, DCs were transduced with TIPE-2 recombinant adenovirus, and then were cocultured with allogeneic CD4+ or CD8 + T cells. The proliferation, cytokine production and activation marker levels of CD4+ or CD8 + T cell were detected.

RESULTS

The data demonstrated that T cell proliferation, cytokine production and activation marker levels were attenuated after treated with TIPE-2 transduced DCs.

CONCLUSIONS

These results suggested that TIPE-2 transduced DCs are capable of inducing allogeneic CD4+ or CD8 + T cell immune suppression, which provide a promising way for the therapeutical strategies of transplantation or autoimmune diseases.

Development and validation of an autophagy-related prognostic signature in esophageal cancer

Background

Autophagy has a dual function in cancer, and its role in carcinogenesis of the esophagus remains poorly understood. In the present study, we explored the prognostic value of autophagy in esophageal cancer (ESCA), one of the leading causes of cancer-related deaths worldwide.

Methods

Using ESCA RNA-sequencing (RNA-Seq) data from 158 primary patients with ESCA, including esophageal adenocarcinoma and esophageal squamous cell carcinoma, were downloaded from The Cancer Genome Atlas (TCGA) for this study. We obtained differentially expressed autophagy-related genes (ARGs) by the “limma” package of R. The Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genome (KEGG) analyses unveiled several fundamental signaling pathways associated with the differentially expressed ARGs in ESCA. Univariate Cox regression analyses were used to estimate associations between ARGs and overall survival (OS) in the TCGA ESCA cohort. A Cox proportional hazards model (iteration =1,000) with a lasso penalty was used to create the optimal multiple-gene prognostic signature utilizing an R package called “glmnet”.

Results

A prognostic signature was constructed with four ARGs (DNAJB1, BNIP1, VAMP7 and TBK1) in the training set, which significantly divided ESCA patients into high- and low-risk groups in terms of OS [hazard ratio (HR) =1.508, 95% confidence interval (CI): 1.201–1.894, P<0.001]. In the testing set, the risk score remained an independent prognostic factor in the multivariate analyses (HR =1.572, 95% CI: 1.096–2.257, P=0.014). The area under the curve (AUC) of the receiver operating characteristic (ROC) predicting 1-year survival showed a better predictive power for the prediction model. The AUC in training and testing cohorts were 0.746 and 0.691, respectively. Therefore, the prognostic signature of the four ARGs was successfully validated in the independent cohort.

Conclusions

The prognostic signature may be an independent predictor of survival for ESCA patients. The prognostic nomogram may improve the prediction of individualized outcome. This study also highlights the importance of autophagy in the outcomes of patients with ESCA.

TBK1 regulates the induction of innate immune response against GCRV by phosphorylating IRF3 in rare minnow (Gobiocypris rarus)

Rare minnow (Gobiocypris rarus), a small cyprinid species that is highly sensitive to the grass carp reovirus (GCRV), is regarded as an ideal model to study the mechanisms of innate immunity in fish. In the present study, a TBK1 homologue from rare minnow (GrTBK1) was identified and its roles in defence against viral infection were investigated. Sequence analysis showed that GrTBK1 encoded a 727-amino acid peptide which shared 98% and 72% identity to the black carp (Mylopharyngodon piceus) and human (Homo sapiens) orthologues, respectively. The amino acid sequence analysis demonstrated that GrTBK1 contains a conserved Serine/Threonine protein kinases catalytic domain (S_TKc) at the N-terminus. Furthermore, cellular distribution proved that GrTBK1 was located in the cytoplasm region. Quantitative real-time PCR analysis revealed that GrTBK1 was ubiquitously expressed in all examined organs, but especially highly in liver. Temporal expression analysis in vivo showed that the expression levels of GrTBK1 were obviously up-regulated in response to GCRV infection. Meanwhile, qRT-PCR assay revealed that the levels of S7 RNA, an important segment of GCRV genome, were higher in the liver than in other tissues. This indicates that GrTBK1 might play a crucial role in responses to GCRV infection in fish. In addition, GrTBK1 activated several type I interferon (IFN) promoters and induced the expression of downstream type I IFN-stimulated genes (ISGs). Furthermore, GrTBK1 obviously phosphorylated the interferon regulatory factor 3 (IRF3). Furthermore, overexpression of GrTBK1 remarkably decreased the GCRV proliferation. In summary, we systematically characterized GrTBK1 and illustrated its role in the innate immune response to GCRV infections.

The multifaceted role of kinases in amyotrophic lateral sclerosis: genetic, pathological and therapeutic implications

Amyotrophic lateral sclerosis is the most common degenerative disorder of motor neurons in adults. As there is no cure, thousands of individuals who are alive at present will succumb to the disease. In recent years, numerous causative genes and risk factors for amyotrophic lateral sclerosis have been identified. Several of the recently identified genes encode kinases. In addition, the hypothesis that (de)phosphorylation processes drive the disease process resulting in selective motor neuron degeneration in different disease variants has been postulated. We re-evaluate the evidence for this hypothesis based on recent findings and discuss the multiple roles of kinases in amyotrophic lateral sclerosis pathogenesis. We propose that kinases could represent promising therapeutic targets. Mainly due to the comprehensive regulation of kinases, however, a better understanding of the disturbances in the kinome network in amyotrophic lateral sclerosis is needed to properly target specific kinases in the clinic.

Myeloid TBK1 Deficiency Induces Motor Deficits and Axon Degeneration Through Inflammatory Cell Infiltration

BACKGROUND

TANK-binding kinase1 (TBK1) haploinsufficiency has been shown to cause both amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD); however, the mechanism is unclear.

METHODS

Myeloid Tbk1 knockout mice (Tbk1-LKO mice) were established and motor function and pathological analyses were also performed. The level of p-TBK1 was analyzed in the ALS animal model and in patient samples using flow cytometry. The expression of inflammatory proteins and mRNAs was analyzed via western blotting and RT-PCR, respectively.

RESULTS

The latency to fall in seven-month-old Tbk1-LKO mice was significantly reduced in evaluations conducted on two consecutive days. Overall, 25.6% of Tbk1-LKO mice presented paralysis symptoms and signs, along with a loosened myelin sheath and axon degeneration at 14-16 months of age. Furthermore, the Tbk1 deficiency in myeloid cells induced inflammatory cell infiltration and dysbacteriosis in the digestive tract. Additionally, p-TBK1 levels were reduced by 29.5% and 14.8% in monocytes of patients with definite ALS and probable ALS and decreased by 27.6% and 45.5% in monocytes and microglia of ALS animals, respectively. The use of PEI-mannose-TBK1 or PEI-mannose-SaCas9-sgRNA to delete mutant SOD1 in macrophages significantly delayed disease onset and prolonged survival in the mouse model of ALS.

CONCLUSIONS

Based on these data, inflammatory monocyte and macrophage infiltration and impaired innate immune defenses contribute to ALS and FTD.

Targeting ubiquitin signaling for cancer immunotherapy

Cancer immunotherapy has become an attractive approach of cancer treatment with tremendous success in treating various advanced malignancies. The development and clinical application of immune checkpoint inhibitors represent one of the most extraordinary accomplishments in cancer immunotherapy. In addition, considerable progress is being made in understanding the mechanism of antitumor immunity and characterizing novel targets for developing additional therapeutic approaches. One active area of investigation is protein ubiquitination, a post-translational mechanism of protein modification that regulates the function of diverse immune cells in antitumor immunity. Accumulating studies suggest that E3 ubiquitin ligases and deubiquitinases form a family of potential targets to be exploited for enhancing antitumor immunity in cancer immunotherapy.

ALS Genetics: Gains, Losses, and Implications for Future Therapies

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disorder caused by the loss of motor neurons from the brain and spinal cord. The ALS community has made remarkable strides over three decades by identifying novel familial mutations, generating animal models, elucidating molecular mechanisms, and ultimately developing promising new therapeutic approaches. Some of these approaches reduce the expression of mutant genes and are in human clinical trials, highlighting the need to carefully consider the normal functions of these genes and potential contribution of gene loss-of-function to ALS. Here, we highlight known loss-of-function mechanisms underlying ALS, potential consequences of lowering levels of gene products, and the need to consider both gain and loss of function to develop safe and effective therapeutic strategies.