Therapeutic Targeting of MLL Degradation Pathways in MLL-Rearranged Leukemia.

Chromosomal translocations of the mixed-lineage leukemia (MLL) gene with various partner genes result in aggressive leukemia with dismal outcomes. Despite similar expression at the mRNA level from the wild-type and chimeric MLL alleles, the chimeric protein is more stable. We report that UBE2O functions in regulating the stability of wild-type MLL in response to interleukin-1 signaling. Targeting wild-type MLL degradation impedes MLL leukemia cell proliferation, and it downregulates a specific group of target genes of the MLL chimeras and their oncogenic cofactor, the super elongation complex. Pharmacologically inhibiting this pathway substantially delays progression, and it improves survival of murine leukemia through stabilizing wild-type MLL protein, which displaces the MLL chimera from some of its target genes and, therefore, relieves the cellular oncogenic addiction to MLL chimeras. Stabilization of MLL provides us with a paradigm in the development of therapies for aggressive MLL leukemia and perhaps for other cancers caused by translocations.

Construction of IRAK4 inhibitor activity prediction model based on machine learning.

Interleukin-1 receptor-associated kinase 4 (IRAK4) is a crucial serine/threonine protein kinase that belongs to the IRAK family and plays a pivotal role in Toll-like receptor (TLR) and Interleukin-1 receptor (IL-1R) signaling pathways. Due to IRAK4's significant role in immunity, inflammation, and malignancies, it has become an intriguing target for discovering and developing potent small-molecule inhibitors. Consequently, there is a pressing need for rapid and accurate prediction of IRAK4 inhibitor activity. Leveraging a comprehensive dataset encompassing activity data for 1628 IRAK4 inhibitors, we constructed a prediction model using the LightGBM algorithm and molecular fingerprints. This model achieved an R2 of 0.829, an MAE of 0.317, and an RMSE of 0.460 in independent testing. To further validate the model's generalization ability, we tested it on 90 IRAK4 inhibitors collected in 2023. Subsequently, we applied the model to predict the activity of 13,268 compounds with docking scores less than - 9.503 kcal/mol. These compounds were initially screened from a pool of 1.6 million molecules in the chemdiv database through high-throughput molecular docking. Among these, 259 compounds with predicted pIC50 values greater than or equal to 8.00 were identified. We then performed ADMET predictions on these selected compounds. Finally, through a rigorous screening process, we identified 34 compounds that adhere to the four complementary drug-likeness rules, making them promising candidates for further investigation. Additionally, molecular dynamics simulations confirmed the stable binding of the screened compounds to the IRAK4 protein. Overall, this work presents a machine learning model for accurate prediction of IRAK4 inhibitor activity and offers new insights for subsequent structure-guided design of novel IRAK4 inhibitors.

Recent Advances in IRAK1: Pharmacological and Therapeutic Aspects.

Interleukin receptor-associated kinase (IRAK) proteins are pivotal in interleukin-1 and Toll-like receptor-mediated signaling pathways. They play essential roles in innate immunity and inflammation. This review analyzes and discusses the physiological functions of IRAK1 and its associated diseases. IRAK1 is involved in a wide range of diseases such as dry eye, which highlights its potential as a therapeutic target under various conditions. Various IRAK1 inhibitors, including Pacritinib and Rosoxacin, show therapeutic potential against malignancies and inflammatory diseases. The covalent IRAK1 inhibitor JH-X-119-01 shows promise in B-cell lymphomas, emphasizing the significance of covalent bonds in its activity. Additionally, the emergence of selective IRAK1 degraders, such as JNJ-101, provides a novel strategy by targeting the scaffolding function of IRAK1. Thus, the evolving landscape of IRAK1-targeted approaches provides promising avenues for increasingly safe and effective therapeutic interventions for various diseases.

A Novel IRAK4 Inhibitor DW18134 Ameliorates Peritonitis and Inflammatory Bowel Disease.

IRAK4 is a critical mediator in NF-κB-regulated inflammatory signaling and has emerged as a promising therapeutic target for the treatment of autoimmune diseases; however, none of its inhibitors have received FDA approval. In this study, we identified a novel small-molecule IRAK4 kinase inhibitor, DW18134, with an IC50 value of 11.2 nM. DW18134 dose-dependently inhibited the phosphorylation of IRAK4 and IKK in primary peritoneal macrophages and RAW264.7 cells, inhibiting the secretion of TNF-α and IL-6 in both cell lines. The in vivo study demonstrated the efficacy of DW18134, significantly attenuating behavioral scores in an LPS-induced peritonitis model. Mechanistically, DW18134 reduced serum TNF-α and IL-6 levels and attenuated inflammatory tissue injury. By directly blocking IRAK4 activation, DW18134 diminished liver macrophage infiltration and the expression of related inflammatory cytokines in peritonitis mice. Additionally, in the DSS-induced colitis model, DW18134 significantly reduced the disease activity index (DAI) and normalized food and water intake and body weight. Furthermore, DW18134 restored intestinal damage and reduced inflammatory cytokine expression in mice by blocking the IRAK4 signaling pathway. Notably, DW18134 protected DSS-threatened intestinal barrier function by upregulating tight junction gene expression. In conclusion, our findings reported a novel IRAK4 inhibitor, DW18134, as a promising candidate for treating inflammatory diseases, including peritonitis and IBD.

Pharmacological inhibition of IRAK1 and IRAK4 prevents endothelial inflammation and atherosclerosis in ApoE-/- mice.

Inflammation associated endothelial dysfunction represents a pivotal contributor to atherosclerosis. Increasingly, evidence has demonstrated that interleukin 1 receptor (IL1-R) / toll-like receptor (TLR) signaling participates in the development of atherosclerosis. Recent large-scale clinical trials have supported the therapeutic potential of anti-inflammatory therapies targeting IL-1ß and IL-6 in reducing atherosclerosis. The present study examined the pharmacological effects of IL-1R-associated kinase 1 and 4 inhibitors (IRAK1/4i) in regulating inflammation of the endothelium and atherosclerosis. We demonstrate that dual pharmacological inhibition of IRAK1 and IRAK4 by an IRAK1/4i is more effective against LPS induced endothelial inflammation, compared with IRAK1 inhibitor or IRAK4 inhibitor monotherapy. IRAK1/4i showed little endothelial cell toxicity at concentrations from 1 µM up to 10 µM. Inhibition of IRAK1/4 reduced endothelial activation induced by LPS in vitro as evidenced by attenuated monocyte adhesion to the endothelium. Mechanistically, blockade of IRAK1/4 ameliorated the transcriptional activity of NF-κB. To assess the pharmacological effects of IRAK1/4i on atherosclerosis in vivo, ApoE-/- mice were orally administered IRAK1/4i (20 mg/kg/d) for 8 weeks. We show that IRAK1/4i reduced atherosclerotic lesion size in the aortic sinus and increased hepatic LDLR protein levels as well as lowered LDL-C level, without affecting other lipid parameters or glucose tolerance. Taken together, our findings demonstrate that dual pharmacological inhibition of IRAK1 and IRAK4 attenuates endothelial inflammation, lowers LDL-C levels and reduces atherosclerosis. Our study reinforces the evolving standing of anti-inflammatory approaches in cardiovascular therapeutics.

Inhibition of IRAK1 Is an Effective Therapy for Autoimmune Hypophysitis in Mice.

Autoimmune hypophysitis (AH) is an autoimmune disease of the pituitary for which the pathogenesis is incompletely known. AH is often treated with corticosteroids; however, steroids may lead to considerable side effects. Using a mouse model of AH (experimental autoimmune hypophysitis, EAH), we show that interleukin-1 receptor-associated kinase 1 (IRAK1) is upregulated in the pituitaries of mice that developed EAH. We identified rosoxacin as a specific inhibitor for IRAK1 and found it could treat EAH. Rosoxacin treatment at an early stage (day 0-13) slightly reduced disease severity, whereas treatment at a later stage (day 14-27) significantly suppressed EAH. Further investigation indicated rosoxacin reduced production of autoantigen-specific antibodies. Rosoxacin downregulated production of cytokines and chemokines that may dampen T cell differentiation or recruitment to the pituitary. Finally, rosoxacin downregulated class II major histocompatibility complex expression on antigen-presenting cells that may lead to impaired activation of autoantigen-specific T cells. These data suggest that IRAK1 may play a pathogenic role in AH and that rosoxacin may be an effective drug for AH and other inflammatory diseases involving IRAK1 dysregulation.

A highly selective inhibitor of interleukin-1 receptor-associated kinases 1/4 (IRAK-1/4) delineates the distinct signaling roles of IRAK-1/4 and the TAK1 kinase.

Interleukin-1 receptor-associated kinase-1 (IRAK-1) and IRAK-4, as well as transforming growth factor ß-activated kinase 1 (TAK1), are protein kinases essential for transducing inflammatory signals from interleukin receptors. IRAK family proteins and TAK1 have high sequence identity within the ATP-binding pocket, limiting the development of highly selective IRAK-1/4 or TAK1 inhibitors. Beyond kinase activity, IRAKs and TAK1 act as molecular scaffolds along with other signaling proteins, complicating the interpretation of experiments involving knockin or knockout approaches. In contrast, pharmacological manipulation offers the promise of targeting catalysis-mediated signaling without grossly disrupting the cellular architecture. Recently, we reported the discovery of takinib, a potent and highly selective TAK1 inhibitor that has only marginal activity against IRAK-4. On the basis of the TAK1-takinib complex structure and the structure of IRAK-1/4, here we defined critical contact sites of the takinib scaffold within the nucleotide-binding sites of each respective kinase. Kinase activity testing of takinib analogs against IRAK-4 identified a highly potent IRAK-4 inhibitor (HS-243). In a kinome-wide screen of 468 protein kinases, HS-243 had exquisite selectivity toward both IRAK-1 (IC50 = 24 nm) and IRAK-4 (IC50 = 20 nm), with only minimal TAK1-inhibiting activity (IC50 = 0.5 µm). Using HS-243 and takinib, we evaluated the consequences of cytokine/chemokine responses after selective inhibition of IRAK-1/4 or TAK1 in response to lipopolysaccharide challenge in human rheumatoid arthritis fibroblast-like synoviocytes. Our results indicate that HS-243 specifically inhibits intracellular IRAKs without TAK1 inhibition and that these kinases have distinct, nonredundant signaling roles.

Inhibition of IRAK1/4 enhances the antitumor effect of lenvatinib in anaplastic thyroid cancer cells.

Anaplastic thyroid cancer (ATC) is an extremely aggressive tumor associated with poor prognosis due to a lack of efficient therapies. In Japan, lenvatinib is the only drug approved for patients with ATC; however, its efficacy is limited. Therefore, novel therapeutic strategies are urgently required for patients with ATC. The present study aimed to identify compounds that enhance the antiproliferative effects of lenvatinib in ATC cells using a compound library. IRAK1/4 Inhibitor I was identified as a candidate compound. Combined treatment with lenvatinib and IRAK1/4 Inhibitor I showed synergistic antiproliferative effects via the induction of cell cycle arrest at G2/M phase in the ATC cell lines 8305C, HTC/C3, ACT-1, and 8505C. Furthermore, IRAK1/4 Inhibitor I enhanced the inhibition of ERK phosphorylation by lenvatinib in 8305C, HTC/C3, and 8505C cells. In an HTC/C3 xenograft mouse model, tumor volume was lower in the combined IRAK1/4 Inhibitor I and lenvatinib group compared with that in the vehicle control, IRAK1/4 Inhibitor I, and lenvatinib groups. IRAK1/4 Inhibitor I was identified as a promising compound that enhances the antiproliferative and antitumor effects of lenvatinib in ATC.

Discovery and optimization of a potent and selective indazolamine series of IRAK4 inhibitors.

IRAK4 is a key mediator of innate immunity. There is a high interest in identifying novel IRAK4 inhibitors for the treatment of inflammatory autoimmune diseases. We describe here a highly potent and selective IRAK4 inhibitor (HS271) that exhibited superior enzymatic and cellular activities, as well as excellent pharmacokinetic properties. HS271 displayed robust in vivo anti-inflammatory efficacy as evaluated in rat models of LPS induced TNFα production and collagen-induced arthritis.

Pharmacological inhibition of IRAK1 attenuates colitis-induced tumorigenesis in mice by inhibiting the inflammatory response and epithelial-mesenchymal transition.

Colorectal cancer (CRC) is the third most common type of cancer. Here, we studied the inhibitory effect of IRAK1 and IRAK4 as a preventive strategy using a colitis-induced tumorigenesis mouse model. CRC clinical data were obtained from the Gene Expression Omnibus (GEO). An experimental inflammation-dependent CRC model was induced by treatment with azoxymethane (AOM) and then dextran sodium sulfate (DSS) in C57BL/6 mice. Mice were administered an IRAK1/4 inhibitor by intraperitoneal injection at 3 mg/kg twice each week for 9 weeks. The IRAK1/4 inhibitor attenuated histological changes and prevented tumor growth. Tumor-associated proteins, including p65 and Ki-67, were downregulated by the IRAK1/4 inhibitor in AOM/DSS-treated mice. Additionally, IRAK1/4 inhibitor administration effectively decreased the expression of inflammatory cytokines. Furthermore, we observed that IRAK1/4 inhibitor treatment attenuated colitis-induced tumorigenesis by inhibiting epithelial-mesenchymal transition. These observations indicate that inhibition of IRAK1 and IRAK4 may suppress experimental colitis-induced tumorigenesis by inhibiting inflammatory responses and epithelial-mesenchymal transition.

Sauropus brevipes ethanol extract negatively regulates inflammatory responses in vivo and in vitro by targeting Src, Syk and IRAK1.

CONTEXT: Sauropus brevipes Müll. Arg. (Phyllanthaceae) has been used as an effective ingredient in a decoction for the treatment of diarrhoea. However, there was no report on its modulatory role in inflammation. OBJECTIVE: This study investigates anti-inflammatory effect of S. brevipes in various inflammation models. MATERIALS AND METHODS: The aerial part of S. brevipes was extracted with 95% ethanol to produce Sb-EE. RAW264.7 cells pre-treated with Sb-EE were stimulated by lipopolysaccharide (LPS), and Griess assay and PCR were performed. High-performance liquid chromatography (HPLC) analysis, luciferase assay, Western blotting and kinase assay were employed. C57BL/6 mice (10 mice/group) were orally administered with Sb-EE (200 mg/kg) once a day for five days, and peritonitis was induced by an intraperitoneal injection of LPS (10 mg/kg). ICR mice (four mice/group) were orally administered with Sb-EE (20 or 200 mg/kg) or ranitidine (positive control) twice a day for two days, and EtOH/HCl was orally injected to induce gastritis. RESULTS: Sb-EE suppressed nitric oxide (NO) release (IC50=34 µg/mL) without cytotoxicity and contained flavonoids (quercetin, luteolin and kaempferol). Sb-EE (200 µg/mL) reduced the mRNA expression of inducible NO synthase (iNOS). Sb-EE blocked the activities of Syk and Src, while inhibiting interleukin-1 receptor associated kinases (IRAK1) by 68%. Similarly, orally administered Sb-EE (200 mg/kg) suppressed NO production by 78% and phosphorylation of Src and Syk in peritonitis mice. Sb-EE also decreased inflammatory lesions in gastritis mice. DISCUSSION AND CONCLUSIONS: This study demonstrates the inhibitory effect of Sb-EE on the inflammatory response, suggesting that Sb-EE can be developed as a potential anti-inflammatory agent.

MicroRNA-146a negatively regulates IL-33 in activated group 2 innate lymphoid cells by inhibiting IRAK1 and TRAF6.

Type II innate lymphoid cells (ILC2) play a very important role in the pathogenesis of allergic asthma. This study aims to investigate whether miR-146a inhibition of asthma is related with interleukin (IL)-33 signaling path way in ILC2 and the underlying mechanisms. Asthma mice model was induced by ovalbumin. miRNA146a mimics was administrated to asthma mice or transfected to activated ILC2 purified from asthma mice lung. RT-PCR was used to detect miRNA146a level in lung tissue and ILC2. IL-5 and IL-13 levels in culture supernatant were detected by flow cytometry. Interleukin-1 receptor-associated kinase 1 (IRAK1), TNF receptor-associated factor 6 (TRAF6), signal transducer and activator of transcription 1 (STAT1) protein expression levels were detected by western blot. miR-146a directly inhibited ILC2 function and suppressed ILC2 proliferation both in vivo and in vitro. During stimulation of ILC2, miR-146a expression gradually increased with a decrease of cell proliferation. Modulation of ILC2 function by miR-146a may depend on IL-33/interleukin 1 receptor-like 1 (IL1RL1 or ST2) signaling through inhibiting IRAK1 and TRAF6.miR-146a can inhibit IRAK1 and TRAF6, downstream molecules of ST2 signal pathway, thereby negatively regulate IL-33/ST2-activated ILC2 to inhibit asthma. Targeting miR-146 maybe a novel strategy for the treatment of allergic asthma.

Inhibition of IRAK4 kinase activity improves ethanol-induced liver injury in mice.

BACKGROUNDS & AIMS: Alcohol-related liver disease (ALD) is a major cause of chronic liver disease worldwide with limited therapeutic options. Interleukin-1 receptor associated kinase 4 (IRAK4), the master kinase of Toll-like receptor (TLR)/IL-1R-mediated signalling activation, is considered a novel therapeutic target in inflammatory diseases, but has not been investigated in the context of ALD. METHODS: IRAK4 phosphorylation and IRAK1 protein were analysed in liver from alcohol-related hepatitis patients and healthy controls. IRAK4 kinase activity-inactive knock-in (Irak4 KI) mice and bone marrow chimeric mice were exposed to chronic ethanol-induced liver injury. IL-1ß-induced IRAK4-mediated signalling and acute phase response were investigated in cultured hepatocytes. IRAK1/4 inhibitor was used to test the therapeutic potential for ethanol-induced liver injury in mice. RESULTS: Increased IRAK4 phosphorylation and reduced IRAK1 protein were found in livers of patients with alcoholic hepatitis. In the chronic ethanol-induced liver injury mouse model, hepatic inflammation and hepatocellular damage were attenuated in Irak4 KI mice. IRAK4 kinase activity promotes expression of acute phase proteins in response to ethanol exposure, including C-reactive protein and serum amyloid A1 (SAA1). SAA1 and IL-1ß synergistically exacerbate ethanol-induced cell death ex vivo. Pharmacological blockage of IRAK4 kinase abrogated ethanol-induced liver injury, inflammation, steatosis, as well as acute phase gene expression and protein production in mice. CONCLUSIONS: Our data elucidate the critical role of IRAK4 kinase activity in the pathogenesis of ethanol-induced liver injury in mice and provide preclinical validation for use of an IRAK1/4 inhibitor as a new potential therapeutic strategy for the treatment of ALD. LAY SUMMARY: Herein, we have identified the role of IRAK4 kinase activity in the development of alcohol-induced liver injury in mice. Hepatocyte-specific IRAK4 is associated with an acute phase response and release of proinflammatory cytokines/chemokines, which synergistically exacerbate alcohol-induced hepatocyte cell death ex vivo. Pharmacological inhibition of IRAK4 kinase activity effectively attenuates alcohol-induced liver injury in mice and could have therapeutic implications.

Phosphatase SHP-1 promotes TLR- and RIG-I-activated production of type I interferon by inhibiting the kinase IRAK1.

Unbalanced production of proinflammatory cytokines and type I interferons in immune responses may lead to immunopathology; thus, the mechanisms that ensure the beneficial production of proinflammatory cytokines and type I interferons are of particular importance. Here we demonstrate that the phosphatase SHP-1 negatively regulated Toll-like receptor-mediated production of proinflammatory cytokines by inhibiting activation of the transcription factor NF-kappaB and mitogen-activated protein kinase. Simultaneously, SHP-1 increased the production of type I interferon mediated by Toll-like receptors and the helicase RIG-I by directly binding to and inhibiting activation of the kinase IRAK1. Our data demonstrate that SHP-1 contributes to immune homeostasis by balancing the production of proinflammatory cytokines and type I interferons in the innate immune response.

Improving metabolic stability and removing aldehyde oxidase liability in a 5-azaquinazoline series of IRAK4 inhibitors.

In this article, we report our efforts towards improving in vitro human clearance in a series of 5-azaquinazolines through a series of C4 truncations and C2 expansions. Extensive DMPK studies enabled us to tackle high Aldehyde Oxidase (AO) metabolism and unexpected discrepancies in human hepatocyte and liver microsomal intrinsic clearance. Our efforts culminated with the discovery of 5-azaquinazoline 35, which also displayed exquisite selectivity for IRAK4, and showed synergistic in vitro activity against MyD88/CD79 double mutant ABC-DLBCL in combination with the covalent BTK inhibitor acalabrutinib.

Crystal structure of human IRAK1.

Interleukin 1 (IL-1) receptor-associated kinases (IRAKs) are serine/threonine kinases that play critical roles in initiating innate immune responses against foreign pathogens and other types of dangers through their role in Toll-like receptor (TLR) and interleukin 1 receptor (IL-1R) mediated signaling pathways. Upon ligand binding, TLRs and IL-1Rs recruit adaptor proteins, such as myeloid differentiation primary response gene 88 (MyD88), to the membrane, which in turn recruit IRAKs via the death domains in these proteins to form the Myddosome complex, leading to IRAK kinase activation. Despite their biological and clinical significance, only the IRAK4 kinase domain structure has been determined among the four IRAK family members. Here, we report the crystal structure of the human IRAK1 kinase domain in complex with a small molecule inhibitor. The structure reveals both similarities and differences between IRAK1 and IRAK4 and is suggestive of approaches to develop IRAK1- or IRAK4-specific inhibitors for potential therapeutic applications. While the IRAK4 kinase domain is capable of homodimerization in the unphosphorylated state, we found that the IRAK1 kinase domain is constitutively monomeric regardless of its phosphorylation state. Additionally, the IRAK1 kinase domain forms heterodimers with the phosphorylated, but not unphosphorylated, IRAK4 kinase domain. Collectively, these data indicate a two-step kinase activation process in which the IRAK4 kinase domain first homodimerizes in the Myddosome, leading to its trans-autophosphorylation and activation. The phosphorylated IRAK4 kinase domain then forms heterodimers with the IRAK1 kinase domain within the Myddosome, leading to its subsequent phosphorylation and activation.

MiR-146a promotes oligodendrocyte progenitor cell differentiation and enhances remyelination in a model of experimental autoimmune encephalomyelitis.

The death of mature oligodendrocytes (OLs) leads to demyelination in the central nervous system (CNS) and subsequently to functional deficits. Remyelination requires the differentiation of oligodendrocyte progenitor cells (OPCs) into myelinating OLs, which in the CNS with neurodegenerative diseases such as multiple sclerosis (MS), is often inhibited. Among the inhibitors of OPC differentiation are toll-like receptor 2 (TLR2) and interleukin-1 receptor-associated kinase 1 (IRAK1) signaling, and both are negatively regulated by microRNA-146a (miR-146a). Therefore, we hypothesized that increase of miR-146a level in the CNS would foster OPC differentiation and remyelination by inhibiting the TLR2/IRAK1 signaling pathway. Here, we tested this hypothesis using exogenous miR-146a mimics and a mouse model of MS, experimental autoimmune encephalomyelitis (EAE) induced by immunization with myelin proteolipid protein peptide (PLP139-151). EAE mice were treated by miR-146a mimics or miR-146a mimic negative controls, respectively, which initiated at day 14 post immunization, once a week for 6 consecutive weeks. Neurological function was monitored daily. Immunofluorescent staining, qRT-PCR and Western blot were used to measure the differentiation of OPCs and myelination, and to investigate the underlying mechanisms of action of miR-146a. Using a fluorescence tracing approach, we found that miR-146a mimics crossed the blood brain barrier and targeted OPCs and microglia/macrophages after systemic administration. MiR-146a mimic treatment substantially improved neurological functional outcome, increased the number of newly generated OLs which may facilitate remyelination in the CNS. The cell number, cytokine level and protein levels of M2 phonotype of microglia/macrophages significantly increased, while cytokine and protein levels of the M1 phenotype significantly decreased after miR-146a mimic treatment. Increased OPC differentiation and remyelination were associated with reduction of TLR2/IRAK1 signaling pathway activity by miR-146a mimic treatment. This study provides insight into the cellular and molecular bases for the therapeutic effects of miR-146a on OPC differentiation and remyelination, and suggests the potential of enhancing miR-146a as a treatment of demyelinating disorders.

MYD88 L265P mutations identify a prognostic gene expression signature and a pathway for targeted inhibition in CLL.

The L265P somatic mutation in the Myeloid Differentiation Primary Response 88 (MYD88) gene is a recurrent mutation in chronic lymphocytic leukaemia (CLL). This mutation has functional effects in various haematological malignancies but its role in CLL remains to be fully elucidated. Here, we report that MYD88 L265P mutations are associated with mutated immunoglobulin heavy-chain gene (IGHV-M) status and that among IGHV-M patients, the presence of MYD88 L265P is associated with younger age at diagnosis. Using microarray and RNA-Seq gene expression analysis, we further observe that the MYD88 L265P mutation is associated with a distinctive gene expression signature that predicts both failure-free survival and overall survival. This association was validated in an independent cohort of patients. To determine whether MYD88 L265P mutations can be therapeutically exploited in CLL, we treated primary cells with an inhibitor of interleukin 1 receptor-associated kinase 4 (IRAK4), a critical effector of the MYD88 pathway. IRAK4 inhibition decreased downstream nuclear factor-κB signalling and cell viability in CLL cells, indicating the potential of the MYD88 pathway as a therapeutic target in CLL.

Selective IRAK4 Inhibition Attenuates Disease in Murine Lupus Models and Demonstrates Steroid Sparing Activity.

The serine/threonine kinase IL-1R-associated kinase (IRAK)4 is a critical regulator of innate immunity. We have identified BMS-986126, a potent, highly selective inhibitor of IRAK4 kinase activity that demonstrates equipotent activity against multiple MyD88-dependent responses both in vitro and in vivo. BMS-986126 failed to inhibit assays downstream of MyD88-independent receptors, including the TNF receptor and TLR3. Very little activity was seen downstream of TLR4, which can also activate an MyD88-independent pathway. In mice, the compound inhibited cytokine production induced by injection of several different TLR agonists, including those for TLR2, TLR7, and TLR9. The compound also significantly suppressed skin inflammation induced by topical administration of the TLR7 agonist imiquimod. BMS-986126 demonstrated robust activity in the MRL/lpr and NZB/NZW models of lupus, inhibiting multiple pathogenic responses. In the MRL/lpr model, robust activity was observed with the combination of suboptimal doses of BMS-986126 and prednisolone, suggesting the potential for steroid sparing activity. BMS-986126 also demonstrated synergy with prednisolone in assays of TLR7- and TLR9-induced IFN target gene expression using human PBMCs. Lastly, BMS-986126 inhibited TLR7- and TLR9-dependent responses using cells derived from lupus patients, suggesting that inhibition of IRAK4 has the potential for therapeutic benefit in treating lupus.

Interleukin-1ß Activates a MYC-Dependent Metabolic Switch in Kidney Stromal Cells Necessary for Progressive Tubulointerstitial Fibrosis.

Background Kidney injury is characterized by persisting inflammation and fibrosis, yet mechanisms by which inflammatory signals drive fibrogenesis remain poorly defined.Methods RNA sequencing of fibrotic kidneys from patients with CKD identified a metabolic gene signature comprising loss of mitochondrial and oxidative phosphorylation gene expression with a concomitant increase in regulators and enzymes of glycolysis under the control of PGC1α and MYC transcription factors, respectively. We modeled this metabolic switch in vivo, in experimental murine models of kidney injury, and in vitro in human kidney stromal cells (SCs) and human kidney organoids.Results In mice, MYC and the target genes thereof became activated in resident SCs early after kidney injury, suggesting that acute innate immune signals regulate this transcriptional switch. In vitro, stimulation of purified human kidney SCs and human kidney organoids with IL-1ß recapitulated the molecular events observed in vivo, inducing functional metabolic derangement characterized by increased MYC-dependent glycolysis, the latter proving necessary to drive proliferation and matrix production. MYC interacted directly with sequestosome 1/p62, which is involved in proteasomal degradation, and modulation of p62 expression caused inverse effects on MYC expression. IL-1ß stimulated autophagy flux, causing degradation of p62 and accumulation of MYC. Inhibition of the IL-1R signal transducer kinase IRAK4 in vivo or inhibition of MYC in vivo as well as in human kidney organoids in vitro abrogated fibrosis and reduced tubular injury.Conclusions Our findings define a connection between IL-1ß and metabolic switch in fibrosis initiation and progression and highlight IL-1ß and MYC as potential therapeutic targets in tubulointerstitial diseases.