TAK1 regulates the tumor microenvironment through inflammatory, angiogenetic and apoptotic signaling cascades

Clonal hematopoiesis-related mutant ASXL1 promotes atherosclerosis in mice via dysregulated innate immunity

Certain somatic mutations provide a fitness advantage to hematopoietic stem cells and lead to clonal expansion of mutant blood cells, known as clonal hematopoiesis (CH). Among the most common CH mutations, ASXL1 mutations pose the highest risk for cardiovascular diseases (CVDs), yet the mechanisms by which they contribute to CVDs are unclear. Here we show that hematopoietic cells harboring C-terminally truncated ASXL1 mutant (ASXL1-MT) accelerate the development of atherosclerosis in Ldlr-/- mice. Transcriptome analyses of plaque cells showed that monocytes and macrophages expressing ASXL1-MT exhibit inflammatory signatures. Mechanistically, we demonstrate that wild-type ASXL1 has an unexpected non-epigenetic role by suppressing innate immune signaling through the inhibition of IRAK1-TAK1 interaction in the cytoplasm. This regulatory function is lost in ASXL1-MT, resulting in NF-κB activation. Inhibition of IRAK1/4 alleviated atherosclerosis driven by ASXL1-MT and decreased inflammatory monocytes. The present work provides a mechanistic and cellular explanation linking ASXL1 mutations, CH and CVDs.

TGF-β signaling: critical nexus of fibrogenesis and cancer

The transforming growth factor-beta (TGF-β) signaling pathway is a vital regulator of cell proliferation, differentiation, apoptosis, and extracellular matrix production. It functions through canonical SMAD-mediated processes and noncanonical pathways involving MAPK cascades, PI3K/AKT, Rho-like GTPases, and NF-κB signaling. This intricate signaling system is finely tuned by interactions between canonical and noncanonical pathways and plays key roles in both physiologic and pathologic conditions including tissue homeostasis, fibrosis, and cancer progression. TGF-β signaling is known to have paradoxical actions. Under normal physiologic conditions, TGF-β signaling promotes cell quiescence and apoptosis, acting as a tumor suppressor. In contrast, in pathological states such as inflammation and cancer, it triggers processes that facilitate cancer progression and tissue remodeling, thus promoting tumor development and fibrosis. Here, we detail the role that TGF-β plays in cancer and fibrosis and highlight the potential for future theranostics targeting this pathway.

Transforming Growth Factor-β-Activated Kinase 1 (TAK1) Mediates Chronic Pain and Cytokine Production in Mouse Models of Inflammatory, Neuropathic, and Primary Pain

The origin of chronic pain is linked to inflammation, characterized by increased levels of proinflammatory cytokines in local tissues and systemic circulation. Transforming growth factor beta-activated kinase 1 (TAK1) is a key regulator of proinflammatory cytokine signaling that has been well characterized in the context of cancer and autoimmune disorders, yet its role in chronic pain is less clear. Here, we evaluated the ability of our TAK1 small-molecule inhibitor, takinib, to attenuate pain and inflammation in preclinical models of inflammatory, neuropathic, and primary pain. Inflammatory, neuropathic, and primary pain was modeled using intraplantar complete Freund's adjuvant (CFA), chronic constriction injury (CCI), and systemic delivery of the catechol-O-methyltransferase (COMT) inhibitor OR486, respectively. Behavioral responses evoked by mechanical and thermal stimuli were evaluated in separate groups of mice receiving takinib or vehicle prior to pain induction (baseline) and over 12 days following CFA injection, 4 weeks following CCI surgery, and 6 hours following OR486 delivery. Hindpaw edema was also measured prior to and 3 days following CFA injection. Upon termination of behavioral experiments, dorsal root ganglia (DRG) were collected to measure cytokines. We also evaluated the ability of takinib to modulate nociceptor activity via in vitro calcium imaging of neurons isolated from the DRG of Gcamp3 mice. In all 3 models, TAK1 inhibition significantly reduced hypersensitivity to mechanical and thermal stimuli and expression of proinflammatory cytokines in DRG. Furthermore, TAK1 inhibition significantly reduced the activity of tumor necrosis factor (TNF)-primed/capsaicin-evoked DRG nociceptive neurons. Overall, our results support the therapeutic potential of TAK1 as a novel drug target for the treatment of chronic pain syndromes with different etiologies. PERSPECTIVE: This article reports the therapeutic potential of TAK1 inhibitors for the treatment of chronic pain. This new treatment has the potential to provide a greater therapeutic offering to physicians and patients suffering from chronic pain as well as reduce the dependency on opioid-based pain treatments.

Delineation of the distinct inflammatory signaling roles of TAK1 and JAK1/3 in the CIA model of rheumatoid arthritis

Rheumatoid arthritis (RA) is a complex autoimmune disease characterized by hyperactive immune cells within the joints, which leads to inflammation, bone degeneration, and chronic pain. For several decades, frontline immunomodulators such as the anti-tumor necrosis factor (TNF) biologics adalimumab (Humira), etanercept (Enbrel), and infliximab (Remicade) have successfully managed disease progression for many patients. However, over time, patients become refractory to these treatments requiring chronic disease to be managed with conventional and more problematic disease modifying antirheumatic drugs such as methotrexate and hydroxychloroquine, and corticosteroids. Due to the large proportion of patients who continue to fail on frontline biologic therapies, there remains an unmet need to derive novel alternative targets with improved efficacy and safety profiles to treat RA. Recent advances in the field have defined novel targets that play important roles in RA pathology, including the Janus activated kinase (JAK) and transforming growth factor beta activated kinase-1 (TAK1). Although three inhibitors of the JAK signaling pathway have been approved for the treatment of moderately to severely active RA in patients who failed on one or more anti-TNFs, at present, no FDA approved TAK1 treatments exist. Our recent discovery of a highly potent and selective, orally bioavailable TAK1 inhibitor has provided insight into the therapeutic potential of this protein kinase as a novel target for RA. Here, we show the distinct cytokine signaling of tofacitnib (Xeljanz; JAK1/3 inhibitor) compared to HS-276 (TAK1 inhibitor) in lipopolysaccharide (LPS) challenged THP-1 cells. Furthermore, in the collagen induced arthritis pre-clinical mouse model of RA, both tofacintib and HS-276 attenuated disease activity score and inflammatory cytokines in the serum. Overall, our results delineate the distinct cytokine signaling of JAK1/3 and TAK1 targeted therapies in vitro and in vivo and suggest that selective TAK1 inhibitors may provide superior therapeutic relief in RA with fewer adverse events.

TAK1 inhibition increases proliferation and differentiation of chick retinal cells

The factors necessary for the differentiation of cell types within the retina are incompletely understood. The transforming growth factor beta (TGF-β) superfamily, including TGF-β1 and 2, the bone morphogenetic proteins, and the activins have all been implicated in differentiation; however, the mechanisms by which these factors affect differentiation are only partially understood. The studies herein focus on a potential role for transforming growth factor β-activated kinase 1 (TAK1), a hub kinase that lies at the intersection of multiple signaling pathways, in the differentiation of cell types within the chick retina. Previous studies have focused predominantly on the role this kinase plays in the inflammation process and axonal growth. TAK1 is downstream of multiple signaling pathways that are critical to development of the central nervous system, including transforming growth factor β (TGFβ), bone morphogenetic proteins (BMPs), and activins. The present study indicates that activated TAK1 is found throughout the developing retina; however, it is localized at higher levels in dividing and differentiating cells. Further, ex ovo retinal studies using TAK1 inhibitor 5Z-7-oxozeaenol increased both progenitor and differentiating cell populations, accompanied by a substantial increase in proliferation and a smaller increase in cell death. These results indicate a unique role for TAK1 in differentiating and proliferating retinal cells.

Development and Efficacy of an Orally Bioavailable Selective TAK1 Inhibitor for the Treatment of Inflammatory Arthritis

Selective targeting of TNF in inflammatory diseases such as rheumatoid arthritis (RA) has provided great therapeutic benefit to many patients with chronic RA. Although these therapies show initially high response rates, their therapeutic benefit is limited over the lifetime of the patient due to the development of antidrug antibodies that preclude proper therapeutic benefits. As a result, patients often return to more problematic therapies such as methotrexate or hydroxychloroquine, which carry long-term side effects. Thus, there is an unmet medical need to develop alternative treatments enabling patients to regain the benefits of selectively targeting TNF functions in vivo. The protein kinase TAK1 is a critical signaling node in TNF-mediated intracellular signaling, regulating downstream NF-κβ activation, leading to the transcription of inflammatory cytokines. TAK1 inhibitors have been developed but have been limited in their clinical advancement due to the lack of selectivity within the human kinome and, most importantly, lack of oral bioavailability. Using a directed medicinal chemistry approach, driven by the cocrystal structure of the TAK1 inhibitor takinib, we developed HS-276, a potent (K_i = 2.5 nM) and highly selective orally bioavailable TAK1 inhibitor. Following oral administration in normal mice, HS-276 is well tolerated (MTD >100 mg/Kg), displaying >95% bioavailability with μM plasma levels. The in vitro and in vivo efficacy of HS-276 showed significant inhibition of TNF-mediated cytokine profiles, correlating with significant attenuation of arthritic-like symptoms in the CIA mouse model of inflammatory RA. Our studies reinforce the hypothesis that TAK1 can be safely targeted pharmacologically to provide an effective alternative to frontline biologic-based RA therapeutics.

Promise of the NLRP3 Inflammasome Inhibitors in In Vivo Disease Models

Nucleotide-binding oligomerization domain NOD-like receptors (NLRs) are conserved cytosolic pattern recognition receptors (PRRs) that track the intracellular milieu for the existence of infection, disease-causing microbes, as well as metabolic distresses. The NLRP3 inflammasome agglomerates are consequent to sensing a wide spectrum of pathogen-associated molecular patterns (PAMPs) and danger-associated molecular patterns (DAMPs). Certain members of the NLR family have been documented to lump into multimolecular conglomerates called inflammasomes, which are inherently linked to stimulation of the cysteine protease caspase-1. Following activation, caspase-1 severs the proinflammatory cytokines interleukin (IL)-1β and IL-18 to their biologically active forms, with consequent commencement of caspase-1-associated pyroptosis. This type of cell death by pyroptosis epitomizes a leading pathway of inflammation. Accumulating scientific documentation has recorded overstimulation of NLRP3 (NOD-like receptor protein 3) inflammasome involvement in a wide array of inflammatory conditions. IL-1β is an archetypic inflammatory cytokine implicated in multiple types of inflammatory maladies. Approaches to impede IL-1β's actions are possible, and their therapeutic effects have been clinically demonstrated; nevertheless, such strategies are associated with certain constraints. For instance, treatments that focus on systemically negating IL-1β (i.e., anakinra, rilonacept, and canakinumab) have been reported to result in an escalated peril of infections. Therefore, given the therapeutic promise of an NLRP3 inhibitor, the concerted escalated venture of the scientific sorority in the advancement of small molecules focusing on direct NLRP3 inflammasome inhibition is quite predictable.

TAK1: a potent tumour necrosis factor inhibitor for the treatment of inflammatory diseases

Aberrant tumour necrosis factor (TNF) signalling is a hallmark of many inflammatory diseases including rheumatoid arthritis (RA), irritable bowel disease and lupus. Maladaptive TNF signalling can lead to hyper active downstream nuclear factor (NF)-κβ signalling in turn amplifying a cell's inflammatory response and exacerbating disease. Within the TNF intracellular inflammatory signalling cascade, transforming growth factor-β-activated kinase 1 (TAK1) has been shown to play a critical role in mediating signal transduction and downstream NF-κβ activation. Owing to its role in TNF inflammatory signalling, TAK1 has become a potential therapeutic target for the treatment of inflammatory diseases such as RA. This review highlights the current development of targeting the TNF-TAK1 signalling axis as a novel therapeutic strategy for the treatment of inflammatory diseases.