The SYK tyrosine kinase: a crucial player in diverse biological functions

Neuronal guidance signaling in neurodegenerative diseases: Key regulators that function at neuron-glia and neuroimmune interfaces

The nervous system processes a vast amount of information, performing computations that underlie perception, cognition, and behavior. During development, neuronal guidance genes, which encode extracellular cues, their receptors, and downstream signal transducers, organize neural wiring to generate the complex architecture of the nervous system. It is now evident that many of these neuroguidance cues and their receptors are active during development and are also expressed in the adult nervous system. This suggests that neuronal guidance pathways are critical not only for neural wiring but also for ongoing function and maintenance of the mature nervous system. Supporting this view, these pathways continue to regulate synaptic connectivity, plasticity, and remodeling, and overall brain homeostasis throughout adulthood. Genetic and transcriptomic analyses have further revealed many neuronal guidance genes to be associated with a wide range of neurodegenerative and neuropsychiatric disorders. Although the precise mechanisms by which aberrant neuronal guidance signaling drives the pathogenesis of these diseases remain to be clarified, emerging evidence points to several common themes, including dysfunction in neurons, microglia, astrocytes, and endothelial cells, along with dysregulation of neuron-microglia-astrocyte, neuroimmune, and neurovascular interactions. In this review, we explore recent advances in understanding the molecular and cellular mechanisms by which aberrant neuronal guidance signaling contributes to disease pathogenesis through altered cell-cell interactions. For instance, recent studies have unveiled two distinct semaphorin-plexin signaling pathways that affect microglial activation and neuroinflammation. We discuss the challenges ahead, along with the therapeutic potentials of targeting neuronal guidance pathways for treating neurodegenerative diseases. Particular focus is placed on how neuronal guidance mechanisms control neuron-glia and neuroimmune interactions and modulate microglial function under physiological and pathological conditions. Specifically, we examine the crosstalk between neuronal guidance signaling and TREM2, a master regulator of microglial function, in the context of pathogenic protein aggregates. It is well-established that age is a major risk factor for neurodegeneration. Future research should address how aging and neuronal guidance signaling interact to influence an individual's susceptibility to various late-onset neurological diseases and how the progression of these diseases could be therapeutically blocked by targeting neuronal guidance pathways.

An electrostatic network with strong connectivity is a phospho-sensor for regulating affinity of Syk-receptor association

Spleen tyrosine kinase (Syk) mediates early signaling events in immunity by coupling membrane receptors to immune responses. Syk comprises a tandem SH2 (tSH2) regulatory module-two SH2 domains connected by a structured linker-and a kinase domain. The association of tSH2 with a doubly tyrosine-phosphorylated motif (dpITAM) on membrane immunoreceptors is central to controlling Syk's signaling activity. tSH2-dpITAM association is regulated by Y131-phosphorylation on linker A, distant from the Syk-immunoreceptor binding sites. A unique thermodynamic signature was reported to control this protein-protein interaction by phosphorylation, yet the molecular mechanism for the phosphorylation effect is unknown. Molecular dynamics (MD) simulation affords the detail needed to fill this knowledge deficiency. Long MD simulations revealed a highly correlated interdomain electrostatic network (distance correlation coefficients > 0.75) that is lost upon Y131-phosphorylation. Some of the strongly correlated interdomain pairs carry the same charge or are separated by distances greater than a salt-bridge pair. The strong interdomain connectivity accounts for the single, narrow free energy basin in the domain-structure conformational landscape for unphosphorylated tSH2. Linker phosphorylation disrupts this network and yields a broader free energy landscape with multiple networks formed by the same group of residues adopting alternative interdomain conformations. A salt dependence of NMR rotational tumbling times substantiates the electrostatic nature of tSH2 domain-domain coupling. Syk tandem SH2 is thus a sensor whose conformational plasticity is sensitive to Y131 phosphorylation. This phospho-sensing response provides the basis for an entropically driven regulatory mechanism that is so-far unique to Syk-immunoreceptor protein-protein association.

The role of SYK phosphorylation in LPS-induced immunoglobulin responses of B cells in large yellow croaker (Larimichthys crocea)

Spleen tyrosine kinase (SYK), a non-receptor protein tyrosine kinase, is a key component of B cell receptor signaling and can regulate multiple physiological functions of B cells in mammals. In this study, a SYK gene was cloned and characterized from large yellow croaker (Larimichthys crocea) (LcSYK), whose open reading frame consists of 1851 base pairs and encodes 616 amino acid residues. The predicted LcSYK protein contains two N-terminal tandem Src homology 2 domains and a C-terminal tyrosine kinase catalytic domain, and shares a high amino acid sequence identity with SYK sequences in other vertebrate species. LcSYK was mainly expressed in immune tissues, such as head kidney, trunk kidney, spleen, and gill. The mRNA expression of LcSYK in primary head kidney leukocytes was not changed at 12, 24, and 48 h after lipopolysaccharide (LPS) stimulation. LPS stimulation upregulated the mRNA expression and protein production of IgM in IgM+ B cells, accompanied by an increase in the phosphorylation level, but not the total protein level, of LcSYK. Moreover, when we used PRT062607 HCl to inhibit the phosphorylation of LcSYK, both mRNA expression and protein production of IgM in IgM+ B cells were significantly suppressed. These results suggest that SYK phosphorylation may play a role in LPS-induced IgM production by IgM+ B cells, improving our understanding of the role of SYK in immunoglobulin responses of B cells in fish.

Gpr109A in TAMs promoted hepatocellular carcinoma via increasing PKA/PPARγ/MerTK/IL-10/TGFβ induced M2c polarization

To delineate Gpr109A's role and mechanisms in modulating the immune microenvironment of hepatocellular carcinoma. Employing Gpr109A-knockout mice and in vitro co-cultures of hepatocellular carcinoma cells with macrophages, this study utilized a suite of techniques, including lentiviral vectors for stable cell line establishment, Western blotting, cell scratch, CCK-8, transwell assays, flow cytometry, immunohistochemistry and phagocytosis assay to assess various cellular behaviors and interactions. Gpr109A deletion markedly reduced the oncogenic potential of H22 cells, both in vivo and when co-cultured with knockout macrophages, impairing their growth, invasion, and migration. In Gpr109A-knockout macrophages, an upregulation of MerTK and a reduction in immunosuppressive cytokine release were observed, indicating a shift towards an M2c macrophage phenotype. This shift is linked to Gpr109A's role in promoting protease overexpression and inhibiting SHP2 phosphorylation, crucial for enhancing cancer cell proliferation and invasiveness. Gpr109A significantly influences macrophage polarization to the M2c type, augmenting hepatocellular carcinoma cell aggressiveness.

Ticagrelor inhibits the growth of lung adenocarcinoma by downregulating SYK expression and modulating the PI3K/AKT pathway

Lung cancer is one of the malignant tumors with the highest morbidity and mortality in China. Despite the use of some targeted therapies in lung cancer treatment, the prognosis remains suboptimal, highlighting the urgent need for new, effective drugs to enhance outcomes. Ticagrelor, a marketed anti-platelet drug, has been reported to have anti-tumor effects. This study primarily investigates the inhibitory effect of Ticagrelor on lung adenocarcinoma in both in vivo and in vitro models, as well as its molecular mechanisms. Firstly, the effects of ticagrelor on the proliferation (CCK-8 and Edu staining), migration (scratch test), and invasion (Transwell chamber) of lung adenocarcinoma cells were evaluated using a variety of lung adenocarcinoma cell models. Secondly, the efficacy of ticagrelor on lung adenocarcinoma in vivo was evaluated by A549, H1975 tumor-bearing mouse models. Finally, transcriptomic sequencing (RNA-Seq) and immunohistochemistry were used to explore the molecular mechanism of the intervention effect of ticagrelor on lung cancer. Ticagrelor significantly inhibits the proliferation, migration and invasion of various lung cancer cells in vitro, and markedly suppressed tumor growth in A549 and NCI-H1975 CDX model in vivo. The pathological results showed that the number of tumor cells in the intervention group was significantly reduced, with large area necrosis, and the expression of Ki-67 in the intervention group was significantly decreased by immunohistochemistry. RNA-seq sequencing results from NCI-H1975 xenograft showed that several integrin-related pathways were down-regulated in the Ticagrelor treatment group, along with a significant reduction in spleen tyrosine kinase (SYK), a pivotal protein related to integrin signaling. Furthermore, we demonstrated that ticagrelor inhibits lung adenocarcinoma by down-regulating SYK and regulating PI3K/AKT pathway using WB. Ticagrelor has obvious inhibitory effect on a variety of lung adenocarcinoma cell lines and cell line transplanted tumors, and its antitumor effect may be related to the inhibition of SYK signaling pathway and PI3K/AKT pathway.

SYK identified by bioinformatics analysis promotes the proliferation of multiple myeloma

BACKGROUND

Despite recent advancements, the pathogenesis of multiple myeloma (MM) remains incompletely elucidated, with relapse and therapy resistance persisting as major clinical challenges, underscoring the imperative to identify novel therapeutic targets.

RESEARCH DESIGN AND METHODS

Differentially expressed genes were initially screened from the GSE6477 and GSE6691 datasets. Subsequent functional annotation and pathway enrichment analyses were conducted utilizing the DAVID bioinformatics platform. A protein-protein interaction network was constructed via the STRING database, followed by module analysis and hub genes identification through CytoHubba plugin. The biological significance of candidate genes was ultimately validated through ex vivo cellular functional assays and in vivo xenograft tumorigenesis experiments in murine models.

RESULTS

Bioinformatics analysis identified spleen tyrosine kinase (SYK) as the most prognostically significant candidate gene (p = 0.027). The SYK-specific inhibitor BAY61-3606 demonstrated time- (p < 0.05) and dose- (p < 0.01) dependent inhibition of MM cell viability, concomitant induction of G2/M phase cell cycle arrest (p < 0.001), and significant promotion of apoptosis (p < 0.05). In vivo experiments utilizing MM xenograft models demonstrated that BAY61-3606 administration significantly attenuated tumor growth kinetics (p < 0.05).

CONCLUSIONS

Our findings establish SYK as a therapeutic target in MM, thereby facilitating the development of innovative treatment strategies.

Inhibition of Dectin-1 alleviates inflammation in early diabetic retinopathy by regulating microglia phenotype

BACKGROUND

Diabetic retinopathy (DR) is a major factor in vision loss in diabetic patients, triggering a series of pathological changes. At present, the treatment methods for diabetic retinopathy are limited. There is an urgent need to further explore its mechanism to bring more treatment options to patients.There is increasing evidence that microglia activation plays a crucial role in inflammatory DR. The C type lectin receptor Dectin-1 is known to play an important role in the inflammatory regulation of microglia, however, its role and mechanism in DR remains unclear. This study aims to elucidate the possible mechanisms through which Dectin-1 influences the inflammatory response in high glucose(HG) stimulated microglia and its impact on retinal inflammation during the early stages of DR.

METHODS

Human microglial cells (HMC3) were stimulated with HG (25 mmol/L), and a streptozotocin (STZ)induced C57BL/6J mouse model was established to simulate DR. To investigate the role of Dectin-1 in HMC3 cells and its underlying molecular mechanisms, we employed western blotting, quantitative realtime PCR (qRT-PCR), hematoxylineosin (H&E) staining, and immunofluorescence analysis.

RESULTS

Our findings revealed that Dectin-1 levels were elevated in microglia stimulated by HG, playing a pivotal role in cell polarization and the induction of inflammatory factors in vitro. In vivo experiments conducted on STZ induced diabetic mice demonstrated an increased expression of Dectin-1 in retinal tissues. This elevation further promoted the expression of pro inflammatory factors, such as TNF-α, IL-1β, and iNOS, triggering an inflammatory response and causing damage to the retina. Notably, inhibiting Dectin-1 reversed these detrimental effects, ultimately contributing to the delay in the progression of DR. Our investigation also uncovered a significant interaction between Dectin-1 and the downstream pro-inflammatory pathway NF-κB. This interaction occurred through the activation of spleen tyrosine kinase (Syk), both in vitro and in vivo.

CONCLUSIONS

In summary, our research strongly suggests that Dectin-1 plays a crucial pro-inflammatory role in early DR. This mechanismis, at least in part, mediated through the Syk/NF-κB pathway. Consequently, inhibition of Dectin-1 is expected to become a potential therapeutic target for delaying DR.

KDM6A Deficiency Induces Myeloid Bias and Promotes CMML-Like Disease Through JAK/STAT3 Activation by Repressing SOCS3

Chronic myelomonocytic leukemia (CMML) is a hematologic malignancy with a poor prognosis and limited targeted therapies. Lysine demethylase 6A (KDM6A), a H3K27 demethylase and key component of the COMPASS complex, is frequently mutated in hematologic malignancies, but its roles in embryonic hematopoiesis and tumor suppression in CMML remain unclear. Using zebrafish models with kdm6a mutants and integrative multi-omics analysis (ATAC-seq, RNA-seq, ChIP), we find that Kdm6a is a critical positive regulator of hematopoietic stem and progenitor cell (HSPC) emergence via Syk-related inflammatory signaling in a H3K27me3-dependent manner. We further find that Kdm6a haploinsufficiency in zebrafish leads to myeloid-biased hematopoiesis and a CMML-like disease, similar to CMML patients with reduced KDM6A expression. This KDM6A haploinsufficiency also significantly alters the chromatin landscape of genes associated with aging and cellular homeostasis in HSPCs. Mechanistically, KAM6A haploinsufficiency represses SOCS3 expression, thereby activating JAK/STAT3 signaling in HSPCs. Importantly, inhibitors targeting JAK or STAT3 phosphorylation alleviate myeloid expansion, providing a rationale for JAK/STAT pathway inhibition in CMML therapy. These findings enhance our understanding of CMML pathogenesis and propose new therapeutic avenues.

CD300ld promotes neutrophil bacterial phagocytosis in sepsis

Sepsis is a life-threatening condition caused by a dysregulated immune response to infection. Neutrophils act as first line of defense against infection, but their function can become impaired in sepsis. CD300 antigen-like family member d (CD300ld), predominantly expressed on neutrophils, associates with Fc receptor common gamma-chain (FcRγ chain), a component vital for phagocytosis. In this study, we investigated the role of CD300ld in neutrophil phagocytosis. Our results demonstrate a marked decrease in CD300ld expression on neutrophils isolated from both septic mice and patients. CD300ld was positively correlated with bacterial phagocytosis in neutrophils. The transcriptomic analysis of CD300ld knock-out neutrophils revealed a downregulation of genes related to defense response to bacteria, suggesting that CD300ld is a key modulator of bacterial clearance. Stimulation of CD300ld with an agonist antibody in neutrophils led to the activation of Rac2, a key regulator of actin polymerization, facilitating the enhanced phagocytosis. Furthermore, CD300ld activation significantly enhanced the in vitro phagocytosis of Escherichia coli and Staphylococcus aureus by neutrophils. Septic mice adoptively transferred with CD300ld-activated neutrophils exhibited markedly reduced bacterial loads in the blood and peritoneum, decreased inflammatory cytokine levels, and alleviated organ injury. These findings highlight the critical role of CD300ld signaling in neutrophil-mediated bacterial clearance in sepsis and provide a solid foundation for future research aimed at developing novel immunotherapies against this deadly disease condition.

Choroidal Neovascularization Is Suppressed With Activation of TREM2 in Mononuclear Phagocytes-Brief Report

BACKGROUND

Mononuclear phagocytes contribute to pathological angiogenesis in age-related macular degeneration, a leading worldwide cause of visual impairment. However, the mechanisms that orchestrate the functions of mononuclear phagocytes remain poorly understood. TREM2 (triggering receptor on myeloid cells 2) has been shown to be crucial for the activation of mononuclear phagocytes in atherosclerosis, fatty liver disease, and Alzheimer disease. The objective of this study was to investigate the role of TREM2 in pathological angiogenesis in age-related macular degeneration.

METHODS

C57BL/6J and Trem2 knockout mice were subjected to laser-induced choroidal neovascularization, a model of choroidal neovascular age-related macular degeneration. Purified bovine sulfatide and agonist anti-TREM2 antibody was used to activate TREM2 signaling. The expression of TREM2 or downstream signals were assessed with immunohistochemistry or real-time quantitative PCR. In vitro murine macrophage RAW264.7 cells were used to investigate the direct impact of sulfatide on inflammatory and phagocytic responses.

RESULTS

We found that pharmacological activation of TREM2 suppressed laser-induced choroidal neovessel formation. The activation of TREM2 in mononuclear phagocytes suppressed TNF (tumor necrosis factor) and subsequently promoted phagocytosis.

CONCLUSIONS

These findings demonstrate that activation of TREM2 in mononuclear phagocytes suppresses the proinflammatory response, promotes phagocytosis, and impedes choroidal neovessel formation. Our study provides insight into the critical role of TREM2 in pathological angiogenesis.

Multi-phased Kinetics and Interaction of Protein Kinase Signaling in Glycoprotein VI-Induced Platelet αIIbβ3 Integrin Activation and Degranulation

Platelet glycoprotein VI (GPVI) stimulation activates the tyrosine kinases Syk and Btk, and the effector proteins phospholipase Cγ 2 (PLCγ2) and protein kinase C (PKC). Here, the activation sequence, crosstalk, and downstream effects of this Syk-Btk-PKC signalosome in human platelets were analyzed.Using immunoblotting, we quantified 14 regulated phospho-sites in platelets stimulated by convulxin with and without inhibition of Syk, Btk, or PKC. Convulxin induced fast, reversible tyrosine phosphorylation (pY) of Syk, Btk, LAT, and PLCγ2, followed by reversible serine/threonine phosphorylation (pS/T) of Syk, Btk, and downstream kinases MEK1/2, Erk1/2, p38, and Akt. Syk inhibition by PRT-060318 abolished all phosphorylations, except Syk pY352. Btk inhibition by acalabrutinib strongly decreased Btk pY223/pS180, Syk pS297, PLCγ2 pY759/Y1217, MEK1/2 pS217/221, Erk1/2 pT202/Y204, p38 pT180/Y182, and Akt pT308/S473. PKC inhibition by GF109203X abolished most pS/T phosphorylations except p38 pT180/Y182 and Akt pT308, but enhanced most Y-phosphorylations. Acalabrutinib, but not GF109203X, suppressed convulxin-induced intracellular Ca2+ mobilization, whereas all three protein kinase inhibitors abolished degranulation and αIIbβ3 integrin activation assessed by flow cytometry. Inhibition of autocrine ADP effects by AR-C669931 partly diminished convulxin-triggered degranulation.Kinetic analysis of GPVI-initiated multisite protein phosphorylation in human platelets demonstrates multiple phases and interactions of tyrosine and serine/threonine kinases with activation-altering feedforward and feedback loops partly involving PKC. The protein kinase inhibitor effects on multisite protein phosphorylation and functional readouts reveal that the signaling network of Syk, Btk, and PKC controls platelet granule exocytosis and αIIbβ3 integrin activation.

Rosmarinic acid suppresses the progression of COPD via Syk by modulating airway inflammation and epithelial apoptosis in vivo and in vitro

Rosmarinic acid (RosA), a hydrophilic phenolic compound found in various plants, has several biological effects such as anti-inflammatory and anti-apoptosis activities. However, its potential impact on chronic obstructive pulmonary disease (COPD) and its underlying mechanism has not been investigated. In this study, we explored the potential therapeutic effects and mechanism of RosA on COPD airway inflammation and alveolar epithelial apoptosis in vivo and in vitro. Our data suggested that RosA may be a therapeutic candidate for COPD with low toxicity. The corresponding mechanism lies in its anti-inflammatory effect on macrophage and bronchial epithelial cells, as well as protective effect on lung epithelial apoptosis via the jointly cross-target spleen tyrosine kinase (Syk).

B Cell Lineage in the Human Endometrium: Physiological and Pathological Implications

Immunocompetent cells of B lineage function in the humoral immunity system in the adaptive immune responses. B cells differentiate into plasmacytes upon antigen-induced activation and produce different subclasses of immunoglobulins/antibodies. Secreted immunoglobulins not only interact with pathogens to inactivate and neutralize them, but also involve the complement system to exert antibacterial activities and trigger opsonization. Endometrium is a mucosal tissue that lines the mammalian uterus and is indispensable for the establishment of a successful pregnancy. The lymphocytes of B cell lineage are a minority in the human cycling endometrium. Human endometrial B cells have therefore been understudied so far. However, the disorders of the female reproductive tract, including chronic endometritis and endometriosis, have highlighted the importance of further research on the endometrial B cell lineage. This review aims to revisit lymphopoiesis, maturation, commitment, and survival of B cells, shedding light on their physiological and pathological implications in the human endometrium.

The multifunctional regulatory post-proline protease dipeptidyl peptidase 9 and its inhibitors: new opportunities for therapeutics

Dipeptidyl Peptidase 9 (DPP9) is a prolyl amino dipeptidylpeptidase that can cut a post-proline peptide bond at the penultimate position at the N-terminus. By removing N-terminal prolines, this intracellular peptidase acts as an upstream regulator of the N-degron pathway. DPP9 has crucial roles in inflammatory regulation, DNA repair, cellular homeostasis, and cellular proliferation, while its deregulation is linked to cancer and immunological disorders. Currently, there is no fully selective chemical inhibitor and the DPP9 knockout transgenic mouse model is conditional. Mice and humans in which DPP9 catalytic activity is absent die neonatally. DPP9 inhibition for manipulating DPP9 activity in vivo has potential uses and there is rapid progress towards DPP9 selectivity, with 170x selectivity achieved. This review discusses roles of DPP9 in biology and diseases and potential applications of compounds that inhibit DPP9 and its related proteases.

Platelet spleen tyrosine kinase is a key regulator of anti-PF4 antibody-induced immunothrombosis

ABSTRACT

Vaccine-induced immune thrombotic thrombocytopenia (VITT) is a rare but serious prothrombotic adverse event after vaccination with adenovector-based COVID-19 vaccines. Laboratory findings indicate that anti-platelet factor 4 (PF4) immunoglobulin G antibodies are the causing factor for the onset of thromboembolic events in VITT. However, molecular mechanisms of cellular interactions, signaling pathways and involvement of different cell types in VITT antibody-mediated thrombosis are not fully understood. Moreover, uncertainty exists regarding current treatment protocols because the sole anticoagulation was shown to be inefficient to prevent thrombosis progression in severe VITT cases. In this study, we demonstrate that platelet spleen tyrosine kinase (SYK) modulates anti-PF4 VITT-mediated thrombus formation in an ex vivo model of immunothrombosis. Our study showed that the selective inhibition of SYK can abrogate VITT antibody-driven procoagulant platelet formation, activation of plasmatic coagulation as well as platelet-leukocyte interplay. Most importantly, the specific inhibition of SYK in platelets but not in neutrophils prevented VITT antibody-induced multicellular thrombus formation, without perturbing the platelet function. Our findings indicate that the specific targeting of platelet SYK might be a promising therapeutic approach to prevent thrombotic complications in patients with antibody-mediated immunothrombosis.

Merocytophagy is an integrin-stabilized macrophage response to microbes reliant on Syk signaling

Macrophages and dendritic cells acquire bacteria and cytosolic content from other cells without killing the donor cell through a trogocytosis-associated process termed merocytophagy. While characteristics of this behavior have been partially identified, the mechanism and potential contribution to the response to infection are unclear. Here, we reveal that a wide range of distinct species of bacteria stimulate enhanced merocytophagy in macrophages through pattern recognition receptor (PRR). Further, we found that cell-to-cell transfer in response to Francisella tularensis infection occurs in a predominantly MyD88-independent manner, relying on spleen tyrosine kinase (Syk) activity. Syk signaling during this response also results in increased surface expression of cell-to-cell adhesion proteins integrin α4, integrin β1, ICAM-1 and CD44 at the site of merocytophagy transfer, and depleting these surface molecules impairs merocytophagic cell-to-cell transfer. Altogether, our data demonstrate that merocytophagy is a host response to infection facilitated by tight cell-to-cell binding which molecularly resembles an immunological synapse between macrophages.

Integrating QSAR modelling with reinforcement learning for Syk inhibitor discovery

Spleen tyrosine kinase (Syk) is a crucial mediator of inflammatory processes and a promising therapeutic target for the management of autoimmune disorders, such as immune thrombocytopenia. While several Syk inhibitors are known to date, their efficacy and safety profiles remain suboptimal, necessitating the exploration of novel compounds. The study introduces a novel deep reinforcement learning strategy for drug discovery, specifically designed to identify new Syk inhibitors. The approach integrates quantitative structure-activity relationship (QSAR) predictions with generative modelling, employing a stacking-ensemble model that achieves a correlation coefficient of 0.78. From over 78,000 molecules generated by this methodology, we identified 139 promising candidates with high predicted potency, binding affinity and optimal drug-likeness properties, demonstrating structural novelty while maintaining essential Syk inhibitor characteristics. Our approach establishes a versatile framework for accelerated drug discovery, which is particularly valuable for the development of rare disease therapeutics.Scientific contributionThe study presents the first application of QSAR-guided reinforcement learning for Syk inhibitor discovery, yielding structurally novel candidates with predicted high potency. The presented methodology can be adapted for other therapeutic targets, potentially accelerating the drug development process.

Tumor-Derived CD109 Orchestrates Reprogramming of Tumor-Associated Macrophages to Dampen Immune Response

BACKGROUND & AIMS

Despite remarkable advancements in immunotherapy, poor responsiveness in intrahepatic cholangiocarcinoma (iCCA) remains a persistent challenge. Here, we explored the immunosuppressive-related secreted proteins derived from iCCA and the underlying regulatory mechanisms in tumor immune microenvironment (TIME) remodeling, with the aim of developing new targets to inhibit tumor growth and improve the efficacy of immunotherapy.

METHODS

Proteomic analysis, single-cell transcriptomics, CyTOF, RNA sequencing, and mass spectrometry were conducted to identify the key secreted protein involved in immune suppression and elucidate the underlying biological mechanisms.

RESULTS

We revealed that tumor-derived soluble CD109 (sCD109) is associated with the immunosuppressive TIME, where elevated sCD109 promotes the enrichment of CD73+ TAMs, hindering T cell immune response. Mechanistically, sCD109 upregulates CD73 mRNA transcription by activating the FcγRI/SYK/NFκB signaling pathway. Meanwhile, sCD109 is internalized into the cytoplasm of macrophages and inhibit the degradation of CD73 protein by binding to the E3 ligase TRIM21, competing with CD73 for its binding site. Dual blockade of CD109 and PD-L1 can improve the infiltration and function of lymphocyte, significantly prolonging the anti-tumor response.

CONCLUSIONS

Our findings reveal sCD109 as a 'secreted immune checkpoint' that reprograms the TIME and suggest that CD109 inhibition is a valuable strategy to sensitize the effectiveness of iCCA immunotherapy.

IMPACT AND IMPLICATIONS

Poor response to tumor immunotherapy in patients with intrahepatic cholangiocarcinoma (iCCA) has long been a challenge for clinicians. In this study, we used multiomics approaches to elucidate that tumor cells secrete soluble CD109, which reprograms macrophages, leading to the accumulation of CD73+ macrophages in the tumor immune microenvironment (TIME). This effect significantly inhibits T cell proliferation and the immune response of CD8+ T cells, thereby impairing the efficacy of immunotherapy. In preclinical studies, we demonstrated that targeting CD109 in mice can markedly improve the immunosuppressive TIME, sensitizing iCCA cells to anti-PD-L1 immunotherapy. These findings represent a crucial step toward developing more effective therapies for iCCA and have significant implications for clinicians, scientists, and drug developers in the field.

SARS-CoV-2 Immune Complex-Mediated Neutrophil Activation

Understanding disease pathogenesis is essential to developing therapies in patients with infections that cause critical illness. Herein, we show that SARS-CoV-2-specific antibody levels and markers of neutrophil activation are associated with disease severity in patients hospitalized with COVID-19. We also provide a link between the adaptive and innate immune response by demonstrating an association between antibody levels and multiple markers of neutrophil degranulation and NETosis. We further demonstrate through a series of in vitro assays that SARS-CoV-2 antigen-antibody immune complexes can stimulate NETosis. Last, we discuss how this NETosis is more strongly associated with IgA immune complexes than IgG and can be ameliorated with spleen tyrosine kinase inhibition.

Unbiased high-throughput screening of drug-repurposing libraries identifies small-molecule inhibitors of clot retraction

ABSTRACT

Platelet clot retraction, the ultimate phase of platelet thrombus formation, is critical for clot stabilization. It requires functional αIIbβ3 receptors, fibrin, and the integrated actions of the actin-myosin contractile and cytoskeletal systems. Disturbances in clot retraction have been associated with both bleeding and thrombosis. We recently demonstrated that platelets treated with the αIIbβ3 antagonist peptide Arg-Gly-Asp-Trp, which eliminates fibrinogen-mediated platelet aggregation, are still able to retract clots. We have exploited this observation to develop an unbiased, functional high-throughput assay to identify small-molecule inhibitors of fibrin-mediated clot retraction adapted for a 384-well plate format. We tested 9710 compounds from drug-repurposing libraries (DRLs). These libraries contain compounds that are either US Food and Drug Administration approved or have undergone preclinical/clinical development. We identified 27 compounds from the Library of Pharmacologically Active Compounds library as inhibitors of clot retraction, of which 14 are known inhibitors of platelet function. From the DRLs, we identified 135 compounds (1.6% hit rate). After extensive curation, these compounds were categorized based on the activity of their reported target. Multiple kinase and phosphodiesterase inhibitors with known antiplatelet effects were identified, along with multiple deubiquitination and receptor inhibitors, as well as compounds that have not previously been reported to have antiplatelet activity. Studies of 1 of the deubiquitination inhibitors (degrasyn) suggest that its effects are downstream of thrombin-induced platelet-fibrinogen interactions and thus may permit the separation of platelet thrombin-induced aggregation-mediated events from clot retraction. Additional studies of the identified compounds may lead to novel mechanisms of inhibiting thrombosis.

SYK negatively regulates ITAM-mediated human NK cell signaling and CD19-CAR NK cell efficacy

Natural killer (NK) cells express activating receptors that signal through ITAM (immunoreceptor tyrosine-based activation motif)-bearing adapter proteins. The phosphorylation of each ITAM creates binding sites for SYK and ZAP70 protein tyrosine kinases to propagate downstream signaling including the induction of Ca2+ influx. While all immature and mature human NK cells coexpress SYK and ZAP70, clonally driven memory or adaptive NK cells can methylate SYK genes, and signaling is mediated exclusively using ZAP70. Here, we examined the role of SYK and ZAP70 in a clonal human NK cell line KHYG1 by CRISPR-based deletion using a combination of experiments and mechanistic computational modeling. Elimination of SYK resulted in more robust Ca2+ influx after crosslinking of the CD16 and NKp30 receptors and enhanced phosphorylation of downstream proteins, whereas ZAP70 deletion diminished these responses. By contrast, ZAP70 depletion increased proliferation of the NK cells. As immature T cells express both SYK and ZAP70 and mature T cells often express only ZAP70, we transduced the human Jurkat cell line with SYK and found that expression of SYK increased proliferation but diminished T cell receptor-induced Ca2+ flux and activation. We performed transcriptional analysis of the matched sets of variant Jurkat and KHYG1 cells and observed profound alterations caused by SYK expression. As depletion of SYK in NK cells increased their activation, primary human NK cells were transduced with a CD19-targeting chimeric antigen receptor and were CRISPR edited to ablate SYK or ZAP70. Deletion of SYK resulted in more robust cytotoxic activity and cytokine production, providing a new therapeutic strategy of NK cell engineering for cancer immunotherapy.

Inhibitory immunoreceptors CD300a and CD300lf cooperate to regulate mast cell activation

Mast cells (MCs) play a central role in allergic immune responses. MC activation is regulated by several inhibitory immunoreceptors. The CD300 family members CD300a and CD300lf recognize phospholipid ligands and inhibit the FcεRI-mediated activating signal in MCs. While CD300a binds to phosphatidylserine (PS) to inhibit MCs activation, CD300lf function is less clear due to its ability to bind with ceramide and PS. Moreover, it also remains blurring whether CD300a and CD300lf function independently, cooperatively, or by interfering with each other in regulating MC activation. Using imaging and flow cytometric analyses of bone marrow-derived cultured MCs (BMMCs) from wild-type (WT), Cd300a-/-, Cd300lf-/-, and Cd300a-/-Cd300lf-/- mice, we show that CD300lf and CD300a colocalized with PS externalized to the outer leaflet of the plasma membrane with a polar formation upon activation, and CD300lf cooperates with CD300a to inhibit BMMCs activation. CD300lf also colocalized with extracellular ceramide in addition to the internal PS on the cell surface, which results in stronger inhibition of MC activation than CD300lf binding to PS alone. Similarly, although both Cd300a-/- and Cd300lf-/- mice showed decreased rectal temperatures compared with WT mice in the model of passive systemic anaphylaxis, Cd300a-/-Cd300lf-/- mice showed lower rectal temperature than either Cd300a-/- or Cd300lf-/- mice. Our results demonstrate the cooperativity of multiple inhibitory receptors expressed on MCs and their regulatory functions upon binding to respective ligands.

Gene Expression Profiling in Acute Myeloid Leukemia Patient Subgroups With High and Low Sensitivity Toward SYK Inhibitors

Acute myeloid leukemia (AML) is a heterogeneous malignancy characterized by the uncontrolled proliferation of myeloid cells, and despite recent treatment advances, patient outcomes remain suboptimal. The cytoplasmic spleen tyrosine kinase (SYK) has emerged as a promising therapeutic target in AML due to its role in promoting leukemic cell survival, proliferation, and chemoresistance. This study investigates in vitro antiproliferative effects of SYK inhibitors on leukemia cells by analyzing 48 primary AML samples treated with five SYK inhibitors: fostamatinib, entospletinib, cerdulatinib, TAK-659, and RO9021. Our findings revealed significant heterogeneity among patients, leading to the identification of two distinct patient sample groups that were identified as having either high or low sensitivity toward SYK inhibitors. Furthermore, gene expression profiling through RNA sequencing of AML patient samples uncovered 97 significantly differentially expressed genes (DEGs) between the two patient groups with high or low in vitro sensitivity toward SYK inhibitors. Pathway enrichment analyses revealed that the high-sensitivity group was enriched in biological processes related to positive gene regulation and significant pathways included cell adhesion molecules and proteoglycans. In contrast, the low-sensitivity group showed enrichment in pathways related to PI3K-Akt signaling and JAK-STAT signaling. Gene set enrichment analysis further highlighted that high-sensitivity patient samples were upregulated in pathways associated with oxidative phosphorylation and MYC targets, whereas low-sensitivity patient samples showed enrichment in TGF beta signaling and IL6 JAK STAT3 signaling. These results identify gene expression profile signatures that may predict sensitivity to SYK inhibition and underscore the potential for personalized therapeutic strategies in AML.

Spleen tyrosine kinase aggravates intestinal inflammation through regulating inflammatory responses of macrophage in ulcerative colitis

BACKGROUND

Ulcerative colitis (UC) is a persistent chronic, non-specific inflammatory disease, and macrophages play a crucial role in its pathogenesis. Spleen tyrosine kinase (Syk) is strongly associated with the pathogenesis of several inflammatory diseases. However, the role of Syk in the pathogenesis of UC is still obscure.

METHODS

Syk expression was analyzed in peripheral blood mononuclear cells (PBMCs) and colonic tissues of UC patients using quantitative reverse transcription-polymerase chain reaction (qRT-PCR) and immunofluorescence. A public database was used to analyze the expression of selected signature genes of interest in UC patients with different expressions of Syk. R788, a small molecule inhibitor of Syk, was used to treat macrophages from mice. The functions of macrophages were assessed using qRT-PCR, flow cytometry, and fluorescence microscopy. Dextran sodium sulfate (DSS)-induced colitis mice model was established to determine the role of Syk in UC.

RESULTS

The Syk levels were markedly increased in PBMCs, colonic tissues, and colonic mucosa lamina propria macrophages from UC patients, and positively related to disease activity. Inhibition of Syk with R788 decreased pro-inflammatory genes expression and increased anti-inflammatory genes expression in peritoneal macrophages and bone marrow macrophages. Blockade of Syk enhanced phagocytosis and bactericidal ability of macrophages. Syk promoted the production of reactive oxygen species of macrophages and M1-type macrophage polarization. Furthermore, inhibition of Syk alleviated intestinal mucosal inflammation in DSS-induced colitis model.

CONCLUSIONS

Syk plays a vital role in intestinal inflammation by regulating inflammatory responses of macrophages in UC. Targeting Syk may be a promising therapeutic approach for UC.

Syk inhibitor attenuates lupus in FcγRIIb-/- mice through the Inhibition of DNA extracellular traps from macrophages and neutrophils via p38MAPK-dependent pathway

Spleen tyrosine kinase (Syk), an important hub of immune signaling, is activated by several signalings in active lupus which could be interfered by Syk inhibitor but is still not completely evaluated in innate immune cells associated with lupus activity. Hence, a Syk inhibitor (fostamatinib; R788) was tested in vivo using Fc gamma receptor-deficient (FcγRIIb-/-) lupus mice and in vitro (macrophages and neutrophils). After 4 weeks of oral Syk inhibitor, 40 week-old FcγRIIb-/- mice (a full-blown lupus model) demonstrated less prominent lupus parameters (serum anti-dsDNA, proteinuria, and glomerulonephritis), systemic inflammation, as evaluated by serum TNFa, IL-6, and citrullinated histone H3 (CitH3), gut permeability defect, as indicated by serum FITC dextran assay, serum lipopolysaccharide (LPS), and serum (1 → 3)-β-D-glucan (BG), extracellular traps (ETs) and immune complex deposition in spleens and kidneys (immunofluorescent staining of CitH3 and immunoglobulin G) than FcγRIIb-/- mice with placebo. Due to the spontaneous elevation of LPS and BG in serum, LPS plus BG (LPS + BG) was used to activate macrophages and neutrophils. After LPS + BG stimulation, FcγRIIb-/- macrophages and neutrophils demonstrated predominant abundance of phosphorylated Syk (Western blotting), and the pro-inflammatory responses (CD86 flow cytometry analysis, supernatant cytokines, ETs immunofluorescent, and flow cytometry-based apoptosis). With RNA sequencing analysis and western blotting, the Syk-p38MAPK-dependent pathway was suggested as downregulating several inflammatory pathways in LPS + BG-activated FcγRIIb-/- macrophages and neutrophils. Although both inhibitors against Syk and p38MAPK attenuated macrophage and neutrophil inflammatory responses against LPS + WGP, the apoptosis inhibition by p38MAPK inhibitor was not observed. These results suggested that Syk inhibitor (fostamatinib) improved the severity of lupus caused by FcγRIIb defect partly through Syk-p38MAPK anti-inflammation that inhibited both ET formation and cytokine production from innate immune cells.

TREM1 interferes with macrophage mitophagy via the E2F1-mediated TOMM40 transcription axis in rheumatoid arthritis

Elevated synovial expression of the triggering receptor expressed on myeloid cells 1 (TREM1) has been identified as a significant biomarker for assessing disease activity in rheumatoid arthritis (RA). The upregulated expression of TREM1, induced by inflammatory mediators in infiltrating macrophages, plays a critical role in synovitis and joint destruction in RA. Our previous sequencing data linked TREM1 activation to aberrant mitophagy. Thus, we explored the efficacy of targeting TREM1 in treating experimental arthritis and its regulatory effect on mitophagy. TREM1 signalling activation was assessed via TREM1, DAP12, and p-SYK levels, and mitophagy was measured through PINK1, PARKIN, and LC3A/B levels. In vitro, TREM1-overexpressing RAW264.7 cells were generated, and the differences in expression and pathways were analyzed via RNA-seq. Changes in the number and morphology of mitochondria and mitophagy in TREM1-overexpressing RAW264.7 cells and normal control were observed via transmission electron microscopy, MitoTracker confocal microscopy and mitochondrial membrane potential analysis. The promotion of TOMM40 gene transcription by TREM1-activated E2F1 was determined via ChIP-PCR and E2F1 siRNA. We found that TREM1 was highly expressed and activated in the synovial tissues of CIA mice concomitant with abnormal mitophagy. The mitochondrial outer membrane transporter TOMM40 was upregulated in experimental arthritis, and the protein levels of PINK1 and LC3B were decreased. RNA-seq analysis indicated that mitophagy-related proteins were extensively downregulated and that the transcription factor E2F1 and the mitochondrial outer membrane transporter TOMM40 were significantly upregulated in TREM1-overexpressing cells. ChIP-PCR revealed that TREM1 overexpression significantly promoted the interaction between E2F1 and TOMM40 gene in RAW264.7 cells. E2F1 knockdown markedly reversed TOMM40 upregulation, mitophagy injury and ROS production in TREM1-overexpressing macrophages but not in control cells. Our study provides preliminary evidence that E2F1 regulates TOMM40 transcription and disrupts mitophagy flux in TREM1-activated macrophages. Inhibiting TREM1 effectively mitigated experimental arthritis by restoring macrophage mitophagy and reducing intracellular ROS levels.

Isoniazid and nicotinic hydrazide hybrids mitigate trehalose-6,6'-dimycolate-induced inflammatory responses and pulmonary granulomas via Syk/PI3K pathways: A promising host-directed therapy for tuberculosis

Granulomas, dense clusters of immune cells and bacteria, are critical barriers in tuberculosis (TB) treatment. Recent advancements in TB management have highlighted granuloma control as a potential host-directed therapy (HDT) strategy. Although isoniazid (INH) is the first-line drug for TB therapy, its efficacy is limited to non-replicating Mycobacterium tuberculosis (Mtb) under granulomatous conditions, necessitating the development of more effective derivatives. In this study, hybrid compounds of isoniazid, designated as INH-D1 and INH-D2, were synthesized and evaluated for their effects on controlling inflammatory responses and pulmonary granuloma lesions induced by trehalose-6,6'-dimycolate (TDM), a glycolipid of Mtb. Both INH-D1 and INH-D2 demonstrated stronger inhibitory effects on inflammatory mediators (TNF-α, interleukin-6, co-stimulatory molecules, and MHC class I) in TDM-stimulated macrophages compared to original INH. These anti-inflammatory effects were mediated by the inhibition of Syk, p38, PI3K, and NF-κB transcription. INH-D1 and INH-D2 exhibited stronger binding energies to Syk and PI3Kα/β than INH, which are known as proximal kinases and key mediator in TDM-mediated inflammatory responses. Oral administration of INH-D2 successfully relieved TDM-induced pulmonary granuloma pathology by reducing innate immune cell infiltration, hypoxic conditions in the lungs, and systemic inflammation by decreasing serum cytokines and chemokines. In contrast, original INH and INH-D1 did not effectively alleviate pulmonary granuloma pathology. These findings demonstrate that the novel molecule INH-D2 is effective in treating pulmonary granulomas owing to its strong anti-inflammatory effects, highlighting it as a promising HDT candidate for the management of pulmonary tuberculosis, thereby providing a strategic alternative to standard anti-TB antibiotics.

Circulatory age-associated B cells: Their distinct transcriptomic characteristics and clinical significance in drug-naïve patients with rheumatoid arthritis

Age-associated B cells (ABCs) have been implicated in the pathogenesis of autoimmune diseases. However, the global gene expression and clinical significance of circulatory ABCs in rheumatoid arthritis (RA) remain poorly understood. Here, single-cell RNA sequencing identified nine B cell subsets in peripheral blood of RA patients, including ABCs. Increased phagocytosis and antigen presentation were functionally enriched by the genes expressed differentially in ABCs. Network analysis and in vitro experiments demonstrated SYK as a key regulator defining the myeloid-like phenotypes in ABCs. Flow cytometry showed that the proportion of ABCs correlated with RA activity and serum tumor necrosis factor-alpha level. Notably, ABCs above a cutoff threshold specifically distinguished RA from healthy controls and indicated higher disease activity. This study highlights the myeloid characteristics of circulatory ABCs regulated by SYK in RA. Increased ABCs may reflect disease activity and could serve as a potential biomarker in RA.

Neutrophil heterogeneity and plasticity: unveiling the multifaceted roles in health and disease

Neutrophils, the most abundant circulating leukocytes, have long been recognized as key players in innate immunity and inflammation. However, recent discoveries unveil their remarkable heterogeneity and plasticity, challenging the traditional view of neutrophils as a homogeneous population with a limited functional repertoire. Advances in single-cell technologies and functional assays have revealed distinct neutrophil subsets with diverse phenotypes and functions and their ability to adapt to microenvironmental cues. This review provides a comprehensive overview of the multidimensional landscape of neutrophil heterogeneity, discussing the various axes along which diversity manifests, including maturation state, density, surface marker expression, and functional polarization. We highlight the molecular mechanisms underpinning neutrophil plasticity, focusing on the complex interplay of signaling pathways, transcriptional regulators, and epigenetic modifications that shape neutrophil responses. Furthermore, we explore the implications of neutrophil heterogeneity and plasticity in physiological processes and pathological conditions, including host defense, inflammation, tissue repair, and cancer. By integrating insights from cutting-edge research, this review aims to provide a framework for understanding the multifaceted roles of neutrophils and their potential as therapeutic targets in a wide range of diseases.

Variability of daily feed intake as an indicator of resilience in Pietrain pigs

There is a growing need to produce more resilient livestock that can cope with extreme environments and their associated impacts. Daily feed intake (DFI) is a promising metric for the development of resilience indicators (RIs), as reduced feed consumption is widely recognised as a clinical sign of disease. However, there is no consensus on which DFI-based RIs are the most informative. The objectives of this study were: (i) to evaluate the most common DFI-based RIs and their relationships with feed efficiency traits (FETs), (ii) to investigate the relationship between these indicators and progeny mortality rates on commercial farms, and (iii) to gain insight into their biological mechanisms. A total of 111 121 DFI records of 1 634 healthy purebred Pietrain boars were used, ranging from 47 to 90 days, with an average of 69 DFI records per boar. Three RIs were calculated: residual variance, RMSE and logarithm of the variance of the deviations from an expected pattern (LnVar). A classical animal model was used to estimate the variance components of each RI, and a bivariate model was implemented to estimate the genetic correlation between RIs and the FET. Furthermore, a preliminary mortality study was carried out using data from 6 889 progeny of 55 boars on farms catalogued as virulent for porcine reproductive and respiratory syndrome. Progeny mortality was calculated for each contemporary group (farm and batch) of the offspring, and sires were classified into three levels of resilience. A Bayesian linear model was used to determine whether the differences in progeny mortality rate between the levels of resilience were relevant. On the other hand, a weighted single-step genome-wide association study was performed for each RI and the FET, using a total of 1 216 genotypes. RIs showed moderate heritability (h2 = 0.27-0.49) and moderate to strong genetic correlation with FET. Progeny of resilient sires had an 80% probability of at least a 2.5% higher survival rate. Overlapping genomic regions were found for RIs and feed conversion ratio, highlighting DOCK1, SYK and SPTLC1 genes for their potential roles in modulating immune responses and/or metabolism. The LnVar of deviations from the population mean was the most promising indicators (LnVar-Pop) for disease resilience, as it was the RI that better captured differences in progeny mortality. Furthermore, these results suggest a common biological basis for RIs and FET of interest to breeding programmes. Further studies are needed to validate them.

Towards a unifying model for B-cell receptor triggering

Antibodies are exceptionally versatile molecules with remarkable flexibility in their binding properties. Their natural targets range from small-molecule toxins, across viruses of different sizes, to bacteria and large multicellular parasites. The molecular determinants bound by antibodies include proteins, peptides, carbohydrates, nucleic acids, lipids and even synthetic molecules that have never existed in nature. Membrane-anchored antibodies also serve as receptors on the surface of the B cells that produce them. Despite recent structural insights, there is still no unifying molecular mechanism to explain how antibody targets (antigens) trigger the activation of these B-cell receptors (BCRs). After cognate antigen encounter, somatic hypermutation and class-switch recombination allow BCR affinity maturation and immunoglobulin class-specific responses, respectively. This raises the fundamental question of how one receptor activation mechanism can accommodate a plethora of variant receptors and ligands, and how it can ensure that individual B cells remain responsive to antigen after somatic hypermutation and class switching. There is still no definite answer. Here we give a brief historical account of the different models proposed to explain BCR triggering and discuss their merit in the context of the current knowledge of the structure of BCRs, their dynamic membrane distribution, and recent biochemical and cell biological insights.

Bioinformatics approach reveals the critical role of inflammation-related genes in age-related hearing loss

Age-related hearing loss (ARHL) is the most prevalent sensory impairment in the elderly. However, the pathogenesis of ARHL remains unclear. This study was aimed to explore the potential inflammation-related genes of ARHL and suggest novel therapeutic targets for this condition. Initially, a total of 105 Inflammatory related differentially expressed genes (IRDEGs) were obtained by overlapping the differentially expressed genes from the GSE49522 and GSE49543 datasets with Inflammatory related genes. The IRDEGs were mainly enriched in MAPK, PI3K-Akt, Hippo and JAK-STAT pathways by analysis of Gene Ontology and Kyoto Encyclopedia of Genes and Genomes. We then identified 10 key IRDEGs including Alox5ap, Chil1, Clec7a, Dysf, Fcgr3, etc. using Least absolute shrinkage and selection operator regression analysis and converted them into human genes. The ROC curve indicated that Alox5ap expression presented a high accuracy in distinguishing between different groups. By CIBERSORT algorithm, 8 humanized key IRDEGs were correlated with the infiltration abundance of 3 immune cells. Finally, it showed that the Alox5ap expression was significantly more effective compared to other variables in the diagnostic model of ARHL. This study suggests that inflammation might play a role in the development of ARHL, providing a deeper understanding of the underlying causes of this disease.

ArfGAP with the SH3 Domain, Ankyrin Repeat and PH Domain 1 Inversely Regulates Programmed Death-Ligand 1 Through Negative Feedback of Phosphorylated Epithelial Growth Factor Receptor and Activation of Nuclear Factor-Kappa B in Non-Small Cell Lung Cancer

Background

Signaling pathways centered on the G-protein ADP-ribosylation factor 6 (Arf6) and its downstream effector ArfGAP with the SH3 Domain, Ankyrin Repeat and PH Domain 1 (AMAP1) drive cancer invasion, metastasis, and therapy resistance. The Arf6-AMAP1 pathway has been reported to promote receptor recycling leading to programmed cell death-ligand 1 (PD-L1) overexpression in pancreatic ductal carcinoma. Moreover, AMAP1 regulates of nuclear factor-kappa B (NF-κB), which is an important molecule in inflammation and immune activation, including tumor immune interaction through PD-L1 regulation. In this study, we investigated the function of AMAP1 on PD-L1 expression using lung cancer cells.

Methods

We used two non-small cell lung cancer cell lines. Protein expression was evaluated by Western blotting. AMAP1 and NF-kB expression were reduced by conventional siRNA methods, and osimertinib was used as an epithelial growth factor receptor (EGFR) inhibitor. Multiple analysis of receptor tyrosine kinases (RTKs) was conducted using a semi-comprehensive RTKs assay.

Results

We found that AMAP1 inversely regulated PD-L1 expression. Based on these results, we examined the activation levels of RTKs associated with both AMAP1 and PD-L1. Following a semi-comprehensive phosphorylated RTK assay, we observed the upregulation of phosphorylated EGFR (pEGFR) led by the downregulation of AMAP1. The inhibition of pEGFR by osimertinib downregulates PD-L1 expression. We investigated the relationships between AMAP1, NF-κB, and PD-L1 expression. AMAP1 knockdown upregulated the expression of both NF-κB and PD-L1. Subsequently, NF-κB knockdown downregulated PD-L1 levels, while double knockdown of AMAP1 and NF-κB, restored PD-L1 expression.

Conclusion

AMAP1 may inversely regulate PD-L1 through negative feedback of pEGFR and activation of NF-κB in NSCLC cell lines.

Microglial lipid phosphatase SHIP1 limits complement-mediated synaptic pruning in the healthy developing hippocampus

The gene inositol polyphosphate-5-phosphatase D (INPP5D), which encodes the lipid phosphatase SH2-containing inositol polyphosphate 5-phosphatase 1 (SHIP1), is associated with the risk of Alzheimer's disease (AD). How it influences microglial function and brain physiology is unclear. Here, we showed that SHIP1 was enriched in early stages of healthy brain development. By combining in vivo loss-of-function approaches and proteomics, we discovered that mice conditionally lacking microglial SHIP1 displayed increased complement and synapse loss in the early postnatal brain. SHIP1-deficient microglia showed altered transcriptional signatures and abnormal synaptic pruning that was dependent on the complement system. Mice exhibited cognitive defects in adulthood only when microglial SHIP1 was depleted early postnatally but not at later stages. Induced pluripotent stem cell (iPSC)-derived microglia lacking SHIP1 also showed increased engulfment of synaptic structures. These findings suggest that SHIP1 is essential for proper microglia-mediated synapse remodeling in the healthy developing brain. Disrupting this process has lasting behavioral effects and may be linked to vulnerability to neurodegeneration.

Robust collection and processing for label-free single voxel proteomics

With advanced mass spectrometry (MS)-based proteomics, genome-scale proteome coverage can be achieved from bulk tissues. However, such bulk measurement lacks spatial resolution and obscures tissue heterogeneity, precluding proteome mapping of tissue microenvironment. Here we report an integrated wet collection of single microscale tissue voxels and Surfactant-assisted One-Pot voxel processing method termed wcSOP for robust label-free single voxel proteomics. wcSOP capitalizes on buffer droplet-assisted wet collection of single voxels dissected by LCM to the tube cap and SOP voxel processing in the same collection cap. This method enables reproducible, label-free quantification of approximately 900 and 4600 proteins for single voxels at 20 µm × 20 µm × 10 µm (~1 cell region) and 200 µm × 200 µm × 10 µm (~100 cell region) from fresh frozen human spleen tissue, respectively. It can reveal spatially resolved protein signatures and region-specific signaling pathways. Furthermore, wcSOP-MS is demonstrated to be broadly applicable for OCT-embedded and FFPE human archived tissues as well as for small-scale 2D proteome mapping of tissues at high spatial resolutions. wcSOP-MS may pave the way for routine robust single voxel proteomics and spatial proteomics.

Exploring the comorbidity mechanisms between atherosclerosis and hashimoto's thyroiditis based on microarray and single-cell sequencing analysis

Atherosclerosis (AS) is a chronic vascular disease characterized by inflammation of the arterial wall and the formation of cholesterol plaques. Hashimoto's thyroiditis (HT) is an autoimmune disorder marked by chronic inflammation and destruction of thyroid tissue. Although previous studies have identified common risk factors between AS and HT, the specific etiology and pathogenic mechanisms underlying these associations remain unclear. We obtained relevant datasets for AS and HT from the Gene Expression Omnibus (GEO). By employing the Limma package, we pinpointed common differentially expressed genes (DEGs) and discerned co-expression modules linked to AS and HT via Weighted Gene Co-expression Network Analysis (WGCNA). We elucidated gene functions and regulatory networks across various biological scenarios through enrichment and pathway analysis using Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG). Core genes were identified using Cytoscape software and further validated with external datasets. We also conducted immune infiltration analysis on these core genes utilizing the CIBERSORT method. Lastly, Single-cell analysis was instrumental in uncovering common diagnostic markers. Based on differential analysis and WGCNA, we identified 119 candidate genes within the cohorts for AS and HT. KEGG and GO enrichment analyses indicate that these genes are significantly involved in antigen processing and presentation, along with various immune-inflammatory pathways. Two pivotal genes, PTPRC and TYROBP, were identified using five algorithms from the cytoHubba plugin. Validation through external datasets confirmed their substantial diagnostic value for AS and HT. Moreover, the results of Gene Set Enrichment Analysis (GSEA) indicated that these core genes are significantly enriched in various receptor interactions and signaling pathways. Immune infiltration analysis revealed a strong association of lymphocytes and macrophages with the pathogenesis of AS and HT. Single-cell analysis demonstrated predominant expression of the core genes in macrophages, monocytes, T cells and Common Myeloid Progenitor (CMP). This study proposes that an aberrant immune response might represent a shared pathogenic mechanism in AS and HT. The genes PTPRC and TYROBP are identified as critical potential biomarkers and therapeutic targets for these comorbid conditions. Furthermore, the core genes and their interactions with immune cells could serve as promising targets for future diagnostic and therapeutic strategies.

Infiltrating plasma cells maintain glioblastoma stem cells through IgG-Tumor binding

Glioblastoma is a highly aggressive primary brain tumor with glioblastoma stem cells (GSCs) enforcing the intra-tumoral hierarchy. Plasma cells (PCs) are critical effectors of the B-lineage immune system, but their roles in glioblastoma remain largely unexplored. Here, we leverage single-cell RNA and B cell receptor sequencing of tumor-infiltrating B-lineage cells and reveal that PCs are aberrantly enriched in the glioblastoma-infiltrating B-lineage population, experience low level of somatic hypermutation, and are associated with poor prognosis. PCs secrete immunoglobulin G (IgG), which stimulates GSC proliferation via the IgG-FcγRIIA-AKT-mTOR axis. Disruption of IgG-FcγRIIA paracrine communication inhibits GSC proliferation and self-renewal. Glioblastoma-infiltrating PCs are recruited to GSC niches via CCL2-CCR2 chemokine program. GSCs further derive pro-proliferative signals from broadly utilized monoclonal antibody-based immune checkpoint inhibitors via FcγRIIA signaling. Our data generate an atlas of B-lineage cells in glioblastoma with a framework for combinatorial targeting of both tumor cell-intrinsic and microenvironmental dependencies.

Engineering synthetic phosphorylation signaling networks in human cells

Protein phosphorylation signaling networks have a central role in how cells sense and respond to their environment. We engineered artificial phosphorylation networks in which reversible enzymatic phosphorylation cycles were assembled from modular protein domain parts and wired together to create synthetic phosphorylation circuits in human cells. Our design scheme enabled model-guided tuning of circuit function and the ability to make diverse network connections; synthetic phosphorylation circuits can be coupled to upstream cell surface receptors to enable fast-timescale sensing of extracellular ligands, and downstream connections can regulate gene expression. We engineered cell-based cytokine controllers that dynamically sense and suppress activated T cells. Our work introduces a generalizable approach that allows the design of signaling circuits that enable user-defined sense-and-respond function for diverse biosensing and therapeutic applications.

Targeting spleen tyrosine kinase (SYK): structure, mechanisms and drug discovery

Spleen tyrosine kinase (SYK) is a crucial non-receptor tyrosine kinase involved in signaling pathways that regulate various cellular processes. It is primarily expressed in hematopoietic cells and myeloid cells, which are crucial for B-cell development, maturation and antibody production, and it is a key therapeutic target for autoimmune and allergic diseases. Overexpression of SYK is also associated with cancer and cardiovascular, cerebrovascular and neurodegenerative diseases, contributing to their initiation and progression. SYK is a promising target for drug development, and several inhibitors have already been reported. This review covers the structure and regulatory pathways of SYK, as well as its links to various diseases. It also highlights key small-molecule SYK inhibitors, their design strategies and their potential therapeutic benefits, aiming to enhance our understanding and aid in the discovery of more-effective SYK inhibitors.

TREM2 bridges microglia and extracellular microenvironment: Mechanistic landscape and therapeutical prospects on Alzheimer's disease

Neuroinflammation is closely related to the pathogenesis of Alzheimer's disease (AD). One of its prominent cellular components, microglia, is a potent coordinator of neuroinflammation in interplay with the characteristic AD pathological alterations including Aβ, tau, and neuronal defects, which constitute the AD-unique extracellular microenvironment. Mounting evidence implicates Triggering Receptors Expressed on Myeloid Cells 2 (TREM2) in the center of microglial activation, a vital event in the pathogenesis of AD. TREM2 is a pivotal microglial receptor that interacts with specific elements present in the AD microenvironment and induces microglial intracellular signallings contributing to phagocytosis, migration, cytokine production, metabolism, and survival, which shapes the microglial activation profile. It follows that TREM2 builds up a bridge between microglia and the extracellular microenvironment. This review illustrates how TREM2 modulates microglia to affect AD pathogenesis. Mainly presented facets in the review are i. the development of AD-specific microglial phenotypes (disease-associated microglia, DAM), ii. microglial interactions with major AD pathologies, and iii. the underlying intracellular signallings of microglial activation. Also, outstanding controversies regarding the nature of neuroinflammation are discussed. Through our illustration, we attempt to establish a TREM2-centered network of AD pathogenesis, in the hope as well to provide insights into the potential therapeutic strategies based on the underlying mechanisms.

Macrophage autophagy protects against acute kidney injury by inhibiting renal inflammation through the degradation of TARM1

Macroautophagy/autophagy activation in renal tubular epithelial cells protects against acute kidney injury (AKI). However, the role of immune cell autophagy, such as that involving macrophages, in AKI remains unclear. In this study, we discovered that macrophage autophagy was an adaptive response during AKI as mice with macrophage-specific autophagy deficiency (atg5-/-) exhibited higher serum creatinine, more severe renal tubule injury, increased infiltration of ADGRE1/F4/80+ macrophages, and elevated expression of inflammatory factors compared to WT mice during AKI induced by either LPS or unilateral ischemia-reperfusion. This was further supported by adoptive transfer of atg5-/- macrophages, but not WT macrophages, to cause more severe AKI in clodronate liposomes-induced macrophage depletion mice. Similar results were also obtained in vitro that bone marrow-derived macrophages (BMDMs) lacking Atg5 largely increased pro-inflammatory cytokine expression in response to LPS and IFNG. Mechanistically, we uncovered that atg5 deletion significantly upregulated the protein expression of TARM1 (T cell-interacting, activating receptor on myeloid cells 1), whereas inhibition of TARM1 suppressed LPS- and IFNG-induced inflammatory responses in atg5-/- RAW 264.7 macrophages. The E3 ubiquitin ligases MARCHF1 and MARCHF8 ubiquitinated TARM1 and promoted its degradation in an autophagy-dependent manner, whereas silencing or mutation of the functional domains of MARCHF1 and MARCHF8 abolished TARM1 degradation. Furthermore, we found that ubiquitinated TARM1 was internalized from plasma membrane into endosomes, and then recruited by the ubiquitin-binding autophagy receptors TAX1BP1 and SQSTM1 into the autophagy-lysosome pathway for degradation. In conclusion, macrophage autophagy protects against AKI by inhibiting renal inflammation through the MARCHF1- and MARCHF8-mediated degradation of TARM1.Abbreviations: AKI, acute kidney injury; ATG, autophagy related; Baf, bafilomycin A1; BMDMs, bone marrow-derived macrophages; CCL2/MCP-1, C-C motif chemokine ligand 2; CHX, cycloheximide; CQ, chloroquine; IFNG, interferon gamma; IL, interleukin; IR, ischemia-reperfusion; MAP1LC3/LC3, microtubule-associated protein 1 light chain 3; LPS, lipopolysaccharide; MARCHF, membrane associated ring-CH-type finger; NC, negative control; NFKB, nuclear factor of kappa light polypeptide gene enhancer in B cells; NLRP3, NLR family, pyrin domain containing 3; NOS2, nitric oxide synthase 2, inducible; Rap, rapamycin; Wort, wortmannin; RT-qPCR, real-time quantitative polymerase chain reaction; Scr, serum creatinine; SEM, standard error of mean; siRNA, small interfering RNA; SYK, spleen tyrosine kinase; TARM1, T cell-interacting, activating receptor on myeloid cells 1; TAX1BP1, Tax1 (human T cell leukemia virus type I) binding protein 1; TECs, tubule epithelial cells; TNF, tumor necrosis factor; WT, wild type.

The ethanolic extract of Rhaphidophora peepla prevents inflammation by inhibiting the activation of Syk/AKT/NF-κB and TAK1/MAPK/AP-1

BACKGROUND

Inflammation is the body's innate reaction to foreign pathogens and serves as a self-regulating mechanism. However, the immune system can mistakenly target the body's own tissues, triggering unnecessary inflammation. For millennia, medicinal plants have been employed for the treatment of diseases. One such plant, Rhaphidophora peepla, has demonstrated potential anti-inflammatory properties. However, the precise mechanism underlying its anti-inflammatory effects remains elusive.

STUDY DESIGN

For this study, validation of target molecules by different experimental approaches and employing two different in vivo experiments were tried to improve the immunopharmacological value of Rhaphidophora peepla.

PURPOSE

Our goal is to elucidate the mechanism through which the ethanol extract of Rhaphidophora peepla (Rp-EE) demonstrates anti-inflammatory properties, both in vivo and in vitro.

METHOD

Rp-EE was phytochemically analyzed with gas chromatography-mass spectrometry (GC-MS) and high-performance liquid chromatography (HPLC). Bioinformatic analysis with protein-protein interaction (PPI) networks and Kyoto Encyclopedia of Genes and Genomes (KEGG), nitric oxide (NO) assay, MTT assay, RT-PCR, ELISA, luciferase assay, CETSA, hematoxylin and eosin (H&E) staining, and Western blotting analysis were used to evaluate anti-inflammatory activity of Rp-EE and its mechanism.

RESULTS

Rp-EE significantly reduced inflammatory responses including nitric oxide (NO) release induced by lipopolysaccharide (LPS) at the non-cytotoxic concentrations in vitro, and HCl/EtOH-induced gastritis and LPS-induced acute lung injury models in vivo. Mechanistically, it was revealed that Rp-EE can specifically target spleen tyrosine kinase (Syk) and transforming growth factor β-activated kinase 1 (TAK1) to suppress the phosphorylation levels of nuclear factor (NF)-κB subunits (p65 and p50) and activator protein (AP)-1 subunits (c-Jun and c-Fos).

CONCLUSION

Rp-EE can inhibit inflammatory reactions managed by Syk and TAK1, resulting in suppressing the Syk/AKT/NF-κB and TAK1/MAPK/AP-1 signaling pathways. These findings lead us to a possibility that Rp-EE can be developed as a promising anti-gastric ulcer and anti-lung injury remedy.

The survival grip-how cell adhesion promotes tumor maintenance within the microenvironment

Cell adhesion is warranted by proteins that are crucial for the maintenance of tissue integrity and homeostasis. Most of these proteins behave as receptors to link adhesion to the control of cell survival and their expression or regulation are often altered in cancers. B-cell malignancies do not evade this principle as they are sustained in relapsed niches by interacting with the microenvironment that includes cells and their secreted factors. Focusing on chronic lymphocytic leukemia and mantle cell lymphoma, this Review delves with the molecules involved in the dialog between the adhesion platforms and signaling pathways known to regulate both cell adhesion and survival. Current therapeutic strategies disrupt adhesive structures and compromise the microenvironment support to tumor cells, rendering them sensitive to immune recognition. The development of organ-on-chip and 3D culture systems, such as spheroids, have revealed the importance of mechanical cues in regulating signaling pathways to organize cell adhesion and survival. All these elements contribute to the elaboration of the crosstalk of lymphoma cells with the microenvironment and the education processes that allow the establishment of the supportive niche.

Balancing immune response: SHP1 controls neutrophil activation in inflamed lungs

Following respiratory infection or injury, neutrophil hyperactivation can damage surrounding lung tissue by releasing harmful compounds. In this issue of the JCI, Moussavi-Harami and colleagues identified tyrosine phosphatase SHP1 as a key negative regulator of neutrophil activation in acute respiratory distress syndrome (ARDS). Neutrophil-specific Shp1 disruption leads to hyperinflammation, pulmonary hemorrhage, and increased mortality in both sterile and pathogen-induced acute lung injury (ALI). Large intravascular neutrophil clusters and excessive PAD4-independent neutrophil extracellular traps (NETs) were identified as key features of lung injury. Mechanistically, Shp1 deficiency resulted in uncontrolled SYK kinase activation, driving chaotic neutrophil hyperactivation and inflammation.

The mechanism of allosteric activation of SYK kinase derived from multiple phospho-ITAM-bound structures

Spleen tyrosine kinase (SYK) is central to adaptive and innate immune signaling. It features a regulatory region containing tandem SH2 (tSH2) domains separated by a helical "hinge" segment keeping SYK inactive by associating with the kinase domain. SYK activation is triggered when the tSH2 domains bind to a phosphorylated immunoreceptor tyrosine-based activation motif (ITAM) found on receptor tails. Past mutational studies have indicated that ITAM binding disrupts the hinge-kinase interaction, leading to SYK phosphorylation and activation. However, the mechanism of this process is unclear, as the ITAM interaction occurs far from the hinge region. We have determined crystal structures of three phospho-ITAMs in complex with the tSH2 domains, revealing a highly conserved binding mechanism. These structures, together with mutational studies and biophysical analyses, reveal that phospho-ITAM binding restricts SH2 domain movement and causes allosteric changes in the hinge region. These changes are not compatible with the association of the kinase domain, leading to kinase activation.

Recurrent CLTC::SYK fusions and CSF1R mutations in juvenile xanthogranuloma of soft tissue

ABSTRACT

Juvenile xanthogranuloma (JXG) is a histiocytic neoplasm that usually presents in the skin. Rarely, extracutaneous localizations occur; the genetic drivers of this clinical variant of JXG remain incompletely characterized. We present detailed clinicopathologic and molecular data of 16 children with extracutaneous JXG and 5 adults with xanthogranulomas confined to the central nervous system (CNS) or soft tissue. Tissue samples were obtained through the Dutch Nationwide Pathology Databank and analyzed with an innovative sequencing technique capable of detecting both small genomic variants and gene rearrangements. Targetable kinase alterations were detected in 16 of 16 children and 1 of 5 adults. Alterations included CLTC::SYK fusions in 6 children and CSF1R mutations in 7 others; all below 2 years of age with soft tissue tumors. One child had a CSF1R mutation and MRC1::PDGFRB fusion. Most were treated surgically, although spontaneous regression occurred in 1 of 6 with CLTC::SYK and 2 of 7 with CSF1R mutations, underscoring that treatment is not always necessary. Tumors with CLTC::SYK fusions generally lacked Touton giant cells but exhibited many other histologic features of JXG and concordant methylation profiles. Using multispectral immunofluorescence, phosphorylated-spleen tyrosine kinase expression was localized to CD163+ histiocytes; tumors with CLTC::SYK fusions also demonstrated mTOR activation, cyclin D1 expression, and variable phosphorylated-extracellular signal-regulated kinase expression. BRAFV600E was detected in 1 child and 1 adult with CNS-xanthogranulomas; both responded to BRAF inhibition. Finally, a TPM3::NTRK1 fusion or MAP2K1 deletion was detected in 2 children with systemic JXG who experienced spontaneous disease regression. This study advances the molecular understanding of histiocytic neoplasms and may guide diagnostics and clinical management.

Metformin attenuates central sensitization by regulating neuroinflammation through the TREM2-SYK signaling pathway in a mouse model of chronic migraine

BACKGROUND

Chronic migraine (CM) is a serious neurological disorder. Central sensitization is one of the important pathophysiological mechanisms underlying CM, and microglia-induced neuroinflammation conduces to central sensitization. Triggering receptor expressed on myeloid cells 2 (TREM2) is presented solely in microglia residing within the central nervous system and plays a key role in neuroinflammation. Metformin has been shown to regulate inflammatory responses and exert analgesic effects, but its relationship with CM remains unclear. In the study, we investigated whether metformin modulates TREM2 to improve central sensitization of CM and clarified the potential molecular mechanisms.

METHODS

A CM mouse model was induced by administration of nitroglycerin (NTG). Behavioral evaluations were conducted using von Frey filaments and hot plate experiments. Western blot and immunofluorescence techniques were employed to investigate the molecular mechanisms. Metformin and the SYK inhibitor R406 were administered to mice to assess their regulatory effects on neuroinflammation and central sensitization. To explore the role of TREM2-SYK in regulating neuroinflammation with metformin, a lentivirus encoding TREM2 was injected into the trigeminal nucleus caudalis (TNC). In vitro experiments were conducted to evaluate the regulation of TREM2-SYK by metformin, involving interventions with LPS, metformin, R406, siTREM2, and TREM2 plasmids.

RESULTS

Metformin and R406 pretreatment can effectively improve hyperalgesia in CM mice. Both metformin and R406 significantly inhibit c-fos and CGRP expression in CM mice, effectively suppressing the activation of microglia and NLRP3 inflammasome induced by NTG. With the administration of NTG, TREM2 expression gradually increased in TNC microglia. Additionally, we observed that metformin significantly inhibits TREM2 and SYK expression in CM mice. Lv-TREM2 attenuated metformin-mediated anti-inflammatory responses. In vitro experiments, knockdown of TREM2 inhibited LPS-induced SYK pathway activation and alleviated inflammatory responses. After the sole overexpression of TREM2, the SYK signaling pathway is activated, resulting in the activation of the NLRP3 inflammasome and an increased expression of pro-inflammatory cytokines; nevertheless, this consequence can be reversed by R406. The overexpression of TREM2 attenuates the inhibition of SYK activity mediated by metformin, and this effect can be reversed by R406.

CONCLUSIONS

Our findings suggest that metformin attenuates central sensitization in CM by regulating the activation of microglia and NLRP3 inflammasome through the TREM2-SYK pathway.

PHGDH/SYK: a hub integrating anti-fungal immunity and serine metabolism

Immune cells modify their metabolic pathways in response to fungal infections. Nevertheless, the biochemical underpinnings need to be better understood. This study reports that fungal infection drives a switch from glycolysis to the serine synthesis pathway (SSP) and one-carbon metabolism by inducing the interaction of spleen tyrosine kinase (SYK) and phosphoglycerate dehydrogenase (PHGDH). As a result, PHGDH promotes SYK phosphorylation, leading to the recruitment of SYK to C-type lectin receptors (CLRs). The CLR/SYK complex initiates signaling cascades that lead to transcription factor activation and pro-inflammatory cytokine production. SYK activates SSP and one-carbon metabolism by inducing PHGDH activity. Then, one-carbon metabolism supports S-adenosylmethionine and histone H3 lysine 36 trimethylation to drive the production of pro-inflammatory cytokines and chemokines. These findings reveal the crosstalk between amino acid metabolism, epigenetic modification, and CLR signaling during fungal infection.

Genetic regulation of B cell receptor signaling pathway: Insights from expression quantitative trait locus analysis using a mixed model

The B cell receptor (BCR) signaling pathway regulates non-immune cellular response through various pathways like MAPK, NF-kB, and PI3K-Akt. This study aimed to identify expression quantitative trait loci (eQTL) and their regulatory functions on BCR signaling pathway genes. A mixed model was employed to analyze eQTL using RNA expression levels in lymphoblastoid from 376 Europeans in the GEUVADIS dataset. In total, 266 SNPs, including 115 cis-acting SNPs, were found for association with transcription of 13 genes (P < 5 × 10-8), revealing 19 independent signals for five genes through linkage disequilibrium analysis. Functional analysis, aligning them with DNase sensitive sites, transcription factor binding sites, histone modification, promoters/enhancers, CpG islands, and ChIA-PET, identified regulatory variants targeting SYK, VAV2, and PLCG2. Notably, rs2562397 was validated as a SYK promoter variant, and rs694505, rs636667, and rs4889409 were confirmed as enhancer variants for VAV2 and PLCG2. Their allelic differences in gene expression were also confirmed using ENCODE ChIP-seq and Sei neural network prediction. Persistent differential expression of these genes by alleles might impact the adaptive immune system, vascular development, and/or relevant diseases that have been previously associated with other variants of the genes. Comprehensive genetic architecture studies of the BCR signaling pathway, along with experiments demonstrating related mechanisms, will greatly contribute to understanding the underlying mechanisms of relevant disease development and implementing precision medicine.

A novel small molecule phagocytosis inhibitor, KB-208, ameliorates ITP in mouse models with similar efficacy as IVIG

BACKGROUND

The characteristic feature of immune cytopenias involves the process of extravascular phagocytosis, wherein macrophages in the spleen and/or liver engage in the destruction of blood cells that have been opsonized by auto- or alloantibodies. Therefore, new treatments that prevent phagocytosis will be advantageous, especially for short-term usage along with alternative options.

STUDY DESIGN AND METHODS

KB-208, a small molecule drug, previously shown to be efficacious for the in vitro inhibition of phagocytosis was synthesized. A passive antibody mouse model of immune thrombocytopenia (ITP) was used. Three different mouse strains (BALB/c, C57BL/6, CD1) were used to determine the efficacy of KB-208 compared with IVIG to ameliorate the ITP. Toxicity was investigated after 60-day chronic administration of KB-208 by a biochemistry panel, gross necroscopy and histopathology.

RESULTS

KB-208 showed similar efficacy to ameliorate the thrombocytopenia compared with IVIG in all three mouse strains. This small molecule drug was effective at 1 mg/kg in ameliorating ITP, in comparison with IVIG at 1000-2500 mg/kg. KB-208 did not affect other blood parameters or elevate serum biochemistry markers of toxicity nor were any abnormal histopathological findings found.

CONCLUSION

KB-208 is similar to IVIG for the amelioration of ITP in multiple mouse strains. Chronic administration of KB-208 for 60 days did not demonstrate in vivo toxicity. These findings indicate that KB-208 is efficacious, without significant in vivo toxicities in mice, and is a potential small molecule candidate for further evaluation to be used in the treatment of ITP and possibly all immune cytopenias where phagocytosis is responsible for the pathophysiology.