An Insertion Within SIRPß1 Shows a Dual Effect Over Alzheimer's Disease Cognitive Decline Altering the Microglial Response.

Background: Microglial dysfunction plays a causative role in Alzheimer's disease (AD) pathogenesis. Here we focus on a germline insertion/deletion variant mapping SIRPß1, a surface receptor that triggers amyloid-ß(Aß) phagocytosis via TYROBP. Objective: To analyze the impact of this copy-number variant in SIRPß1 expression and how it affects AD molecular etiology. Methods: Copy-number variant proxy rs2209313 was evaluated in GERALD and GR@ACE longitudinal series. Hippocampal specimens of genotyped AD patients were also examined. SIRPß1 isoform-specific phagocytosis assays were performed in HEK393T cells. Results: The insertion alters the SIRPß1 protein isoform landscape compromising its ability to bind oligomeric Aß and its affinity for TYROBP. SIRPß1 Dup/Dup patients with mild cognitive impairment show an increased cerebrospinal fluid t-Tau/Aß ratio (p = 0.018) and a higher risk to develop AD (OR = 1.678, p = 0.018). MRIs showed that Dup/Dup patients exhibited a worse initial response to AD. At the moment of diagnosis, all patients showed equivalent Mini-Mental State Examination scores. However, AD patients with the duplication had less hippocampal degeneration (p < 0.001) and fewer white matter hyperintensities. In contrast, longitudinal studies indicate that patients bearing the duplication allele show a slower cognitive decline (p = 0.013). Transcriptional analysis also shows that the SIRPß1 duplication allele correlates with higher TREM2 expression and an increased microglial activation. Conclusions: The SIRPß1 internal duplication has opposite effects over MCI-to-Dementia conversion risk and AD progression, affecting microglial response to Aß. Given the pharmacological approaches focused on the TREM2-TYROBP axis, we believe that SIRPß1 structural variant might be considered as a potential modulator of this causative pathway.

TREM1/DAP12 based novel multiple chain CAR-T cells targeting DLL3 show robust anti-tumour efficacy for small cell lung cancer.

Small cell lung cancer (SCLC), recognized as the most aggressive subtype of lung cancer, presents an extremely poor prognosis. Currently, patients with small cell lung cancer face a significant dearth of effective alternative treatment options once they experience recurrence and progression after first-line therapy. Despite the promising efficacy of immunotherapy, particularly immune checkpoint inhibitors in non-small cell lung cancer (NSCLC) and various other tumours, its impact on significantly enhancing the prognosis of SCLC patients remains elusive. DLL3 has emerged as a compelling target for targeted therapy in SCLC due to its high expression on the membranes of SCLC and other neuroendocrine carcinoma cells, with minimal to no expression in normal cells. Our previous work led to the development of a novel multiple chain chimeric antigen receptor (CAR) leveraging the TREM1 receptor and DAP12, which efficiently activated T cells and conferred potent cell cytotoxicity. In this study, we have developed a DLL3-TREM1/DAP12 CAR-T (DLL3-DT CAR-T) therapy, demonstrating comparable anti-tumour efficacy against SCLC cells in vitro. In murine xenograft and patient-derived xenograft models, DLL3-DT CAR-T cells exhibited a more robust tumour eradication efficiency than second-generation DLL3-BBZ CAR-T cells. Furthermore, we observed elevated memory phenotypes, induced durable responses, and activation under antigen-presenting cells in DLL3-DT CAR-T cells. Collectively, these findings suggest that DLL3-DT CAR-T cells may offer a novel and potentially effective therapeutic strategy for treating DLL3-expressing SCLC and other solid tumours.

FcγRIIb Exacerbates LPS-Induced Neuroinflammation by Binding with the Bridging Protein DAP12 and Promoting the Activation of PI3K/AKT Signaling Pathway in Microglia.

Introduction: This paper focuses on the expression and role of FcγRIIb in neuroinflammation, exploring the molecular mechanisms by which FcγRIIb interacts with the bridging protein DAP12 to regulate the PI3K-AKT signaling pathway that promote neuroinflammation and aggravate neuronal injury. Methods: LPS-induced neuroinflammation models in vivo and in vitro were constructed to explore the role and mechanism of FcγRIIb in CNS inflammation. Subsequently, FcγRIIb was knocked down or overexpressed to observe the activation of BV2 cell and the effect on PI3K-AKT pathway. Then the PI3K-AKT pathway was blocked to observe its effect on cell activation and FcγRIIb expression. We analyzed the interaction between FcγRIIb and DAP12 by Immunoprecipitation technique. Then FcγRIIb was overexpressed while knocking down DAP12 to observe its effect on PI3K-AKT pathway. Finally, BV2 cell culture supernatant was co-cultured with neuronal cell HT22 to observe its effect on neuronal apoptosis and cell activity. Results: In vivo and in vitro, we found that FcγRIIb expression was significantly increased and activated the PI3K-AKT pathway. Contrary to the results of overexpression of FcγRIIb, knockdown of FcγRIIb resulted in a significant low level of relevant inflammatory factors and suppressed the PI3K-AKT pathway. Furthermore, LPS stimulation induced an interaction between FcγRIIb and DAP12. Knockdown of DAP12 suppressed inflammation and activation of the PI3K-AKT pathway in BV2 cells, and meantime overexpression of FcγRIIb suppressed the level of FcγRIIb-induced AKT phosphorylation. Additionally, knockdown of FcγRIIb inhibited microglia activation, which induced neuronal apoptosis. Discussion: Altogether, our experiments indicate that FcγRIIb interacts with DAP12 to promote microglia activation by activating the PI3K-AKT pathway while leading to neuronal apoptosis and exacerbating brain tissue injury, which may provide a new target for the treatment of inflammatory diseases in the central nervous system.

Study on the anti-tumor effect of CD30 CAR-T cells based on multi-chain structure / 安徽医科大学学报

Objective @#To develop a CD30-targeted CAR-T cell drug based on the multi-chain chimeric antigen re- ceptor T cells (CAR-T) of the bridging protein DAP12 , and to study the in vitro and in vivo preclinical efficacy of CD30 CAR-T on Hodgkin lymphoma tumor cells .@*Methods @#Through gene synthesis and molecular cloning tech- niques , a CAR plasmid targeting CD30 was designed and constructed , and the obtained lentivirus was packaged . The T cells were transfected with the lentivirus , where the multi-chain CAR-T targeting CD30 was the CD30 - KIRS2/Dap12-BB group , the single-chain second-generation CAR-T was the CD30-41BBζgroup , and the T cells without virus infection were the NTD group . The positive rate of CAR was detected by flow cytometry , the cytotoxic- ity of the cells was detected by lactate dehydrogenase (LDH) release assay , the secretion level of the cytokine in- terferon γ(IFN-γ) was detected by enzyme-linked immunosorbent assay ( ELISA) , and the antitumor activity of CD30 CAR-T in mice was further detected by a mouse xenograft tumor model . @*Results @#A comparison was made between the multi-chain CAR-T targeting CD30 and the single-chain second-generation CAR-T. It was found that the antitumor effect of the multi-chain CAR-T was similar to that of the single-chain CAR-T. However , it was worth noting that the IFN-γsecretion level of the multi-chain CAR-T was higher (P < 0 . 001) . More importantly , in the mouse tumor model experiment , the multi-chain CAR-T achieved complete tumor regression . @*Conclusion @#The multi-chain CAR-T targeting CD30 is superior to the traditional single-chain CAR-T in terms of antitumor activity .

[Novel CD19-KIRS2/Dap12-BB CAR-T Treatment for 3 Patients with Relapsed and Refractory B-Cell Tumors].

OBJECTIVE: To investigate the safety and efficacy of novel CD19-KIRS2/Dap12-BB chimeric antigen receptor T cells (CAR-T cells) in the treatment of relapsed/refractory B-cell malignancy (R/R BCM). METHODS: Three patients with R/R BCM treated with novel CD19-KIRS2/Dap12-BB CAR-T cells from June 2020 to November 2020 were enrolled, including 1 case of B-cell acute lymphoblastic leukaemia (B-ALL) and 2 cases of non-Hodgkin's lymphoma (NHL), and the efficacy and adverse reactions were observed. RESULTS: After CAR-T cells infusion, patient with B-ALL achieved complete remission (CR) and minimal residual disease (MRD) turned negative, and 2 patients with NHL achieved partial remission (PR). Grade 2 cytokine release syndrome (CRS) occurred in B-ALL patient, grade 1 CRS occurred in 2 NHL patients, and grade II to IV hematologic adverse reactions occurred in 3 patients, all of which were controllable and reversible. The progression-free survival (PFS) of the 3 patients was 143, 199, and 91 days, and overall survival (OS) was 282, 430, and 338 days, respectively. CONCLUSION: The novel CD19-KIRS2/Dap12-BB CAR-T cells in treatment of 3 patients with R/R BCM have significant short-term efficacy and controllable adverse reactions, but the long-term efficacy needs to be further improved.

A novel TREM1/DAP12-based multiple chain CAR-T cell targets PTK7 in ovarian cancer therapy.

While CAR-T cell therapy has shown success against hematological tumors, its effectiveness for solid tumors, including ovarian cancer, remains unsatisfactory. This study aimed to develop and evaluate the efficacy of novel chimeric antigen receptor T (CAR-T) cells targeting PTK7 through TREM1/DAP12 signaling against ovarian cancer. The expression of PTK7 in ovarian cancer tissues and cells was evaluated using immunohistochemical staining and flow cytometric analysis. The anti-tumor effects of PTK7 CAR-T cells were assessed in vitro using real-time cell analysis and enzyme-linked immunosorbent assay, and in vivo using a xenograft tumor model. PTK7 was significantly expressed in ovarian cancer tissues and cells. PTK7-targeting CAR-T cells based on TREM1/DAP12 signaling exhibited potent cytotoxicity against ovarian cancer cells expressing PTK7 in vitro, and effectively eradicated tumors in vivo. Our findings suggest that TREM1/DAP12-based PTK7 CAR-T cells have potential as a treatment strategy for ovarian cancer. Further studies are needed to evaluate the safety and efficacy of this approach in clinical trials.

In-Silico CLEC5A mRNA expression analysis to predict Dengue susceptibility in cancer patients.

Dengue fever is the fastest-growing infectious disease in the world. It is the leading vector-borne viral neglected tropical disease. The most acute immune response to dengue virus infection is dengue shock syndrome and hemorrhagic fever, which is due to the activation of CLEC5A C-type lectin domain family 5, member A (CLEC5A). It is a cell surface receptor, and its well-known ligand is the dengue virus. It gets activated by the attachment of dengue virion, which, as a result, phosphorylates its adaptor protein DAP12 leading to the induction of various pro-inflammatory cytokines. Clinical data suggested that the kidneys and lungs are among the major hit organs in the case of severe dengue infection. Here we predict kidney and lung cancer patients are vulnerable to dengue virus infection as CLEC5A mRNA expression in tumor samples using publicly available software such as TIMER and GEPIA database. We also identified the immunomodulatory role CLEC5A gene therefore targeting it could be a vital tool to cure dengue.

Huang-Lian-Jie-Du decoction alleviates depressive-like behaviors in dextran sulfate sodium-induced colitis mice via Trem2/Dap12 pathway.

ETHNOPHARMACOLOGICAL RELEVANCE: Huang-Lian-Jie-Du decoction (HLJD), a traditional Chinese medicine prescription, has been implicated as effective in treating colitis, depression and inflammation-related diseases. Whether HLJD decoction could ameliorate colitis-induced depression was still unknown and the underlying mechanism was needed to be clarified. AIM OF THE STUDY: Our study aimed to explore the effect and the underlying mechanism of HLJD treatment on colitis-induced depression and the involvement of the inflammatory factors and microglial-activated related genes. MATERIALS AND METHODS: The chronic colitis model was established by treating male mice with 1% dextran sulfate sodium (DSS) for 8 weeks. One week after DSS-treated, HLJD decoction was administered orally with 2 and 4 g/kg daily for 7 weeks. Behavior tests (Open field/Elevated plus maze/Novel object recognition) and TUNEL staining were then assessed. The expression of inflammatory-related genes and microglial dysregulation were measured by RT-PCR and the expression of Trem2, Danp12 and Iba1 were assessed by immunofluorescence methods. RESULTS: Depressive-like behaviors were observed in mice treated with DSS, which suffered colitis. Compared to normal control (NC-V) mice, the density of TUNEL + cells in the habenula (Hb), hippocampus (HIP), and cortex were significantly higher in colitis (DSS-V) mice, especially in Hb. Compared to NC-V and several brain regions, the expression levels of the Il-1ß, Il-10 and Dap12 mRNA were significantly increased in the lateral habenula (LHb) of colitis mice. Moreover, the expression of Trem2, Dap12 and Iba1 were increased in LHb of DSS-V mice. HLJD treatment could alleviate depressive-like behaviors, reduce the density of TUNEL + cells in Hb and the expression of Il-6, Il-10 and Dap12 mRNA in LHb of DSS-V mice. The overexpression of Trem2, Dap12 and Iba1 in LHb of DSS-V mice were reversed after HLJD treatment. CONCLUSION: These results reveal LHb is an important brain region during the process of colitis-induced depression. HLJD treatment could alleviates depressive-like behaviors in colitis mice via inhibiting the Trem2/Dap12 pathway in microglia of LHb, which would contribute to the precise treatment. It provides a potential mechanistic explanation for the effectiveness of HLJD treatment in colitis patients with depression.

Untangling the Role of TREM2 in Conjugation with Microglia in Neuronal Dysfunction: A Hypothesis on a Novel Pathway in the Pathophysiology of Alzheimer's Disease.

Alzheimer's disease (AD) is a complex neurodegenerative disorder involving heterogenous pathophysiological characteristics, which has become a challenge to therapeutics. The major pathophysiology of AD comprises amyloid-ß (Aß), tau, oxidative stress, and apoptosis. Recent studies indicate the significance of Triggering receptor expressed on myeloid cells 2 (TREM2) and its mutant variants in AD. TREM2 are the transmembrane receptors of microglial cells that performs a broad range of physiological cell processes. Phagocytosis of Aß is one of the physiological roles of TREM2, which plays a pivotal role in AD progression. R47H, a mutant variant of TREM2, increases the risk of AD by impairing TREM2-Aß binding. Inconclusive evidence regarding the TREM2 signaling cascade mechanism of Aß phagocytosis motivates the current review to propose a new hypothesis. The review systematically assesses the cross talk between TREM2 and other AD pathological domains and the influence of TREM2 on amyloid and tau seeding. Disease associated microglia (DAM), a novel state of microglia with unique transcriptional and functional signatures reported in neurodegenerative conditions, also depend on the TREM2 pathway for its differentiation. DAM is suggested to have a neuroprotective role. We hypothesize that TREM2, along with its signaling adaptors and endogenous proteins, play a key role in ameliorating Aß clearance. We indicate that TREM2 has the potential to ameliorate the Aß burden, though with differential clearance ability and may act as a potential therapeutic target.

Novel CD19-KIRS2/Dap12-BB CAR-T Treatment for 3 Patients with Relapsed and Refractory B-Cell Tumors / 中国实验血液学杂志

OBJECTIVE@#To investigate the safety and efficacy of novel CD19-KIRS2/Dap12-BB chimeric antigen receptor T cells (CAR-T cells) in the treatment of relapsed/refractory B-cell malignancy (R/R BCM).@*METHODS@#Three patients with R/R BCM treated with novel CD19-KIRS2/Dap12-BB CAR-T cells from June 2020 to November 2020 were enrolled, including 1 case of B-cell acute lymphoblastic leukaemia (B-ALL) and 2 cases of non-Hodgkin's lymphoma (NHL), and the efficacy and adverse reactions were observed.@*RESULTS@#After CAR-T cells infusion, patient with B-ALL achieved complete remission (CR) and minimal residual disease (MRD) turned negative, and 2 patients with NHL achieved partial remission (PR). Grade 2 cytokine release syndrome (CRS) occurred in B-ALL patient, grade 1 CRS occurred in 2 NHL patients, and grade II to IV hematologic adverse reactions occurred in 3 patients, all of which were controllable and reversible. The progression-free survival (PFS) of the 3 patients was 143, 199, and 91 days, and overall survival (OS) was 282, 430, and 338 days, respectively.@*CONCLUSION@#The novel CD19-KIRS2/Dap12-BB CAR-T cells in treatment of 3 patients with R/R BCM have significant short-term efficacy and controllable adverse reactions, but the long-term efficacy needs to be further improved.

From structure to function - Ligand recognition by myeloid C-type lectin receptors.

The relevance of protein-glycan interactions in immunity has long been underestimated. Yet, the immune system possesses numerous classes of glycan-binding proteins, so-called lectins. Of specific interest is the group of myeloid C-type lectin receptors (CLRs) as they are mainly expressed by myeloid cells and play an important role in the initiation of an immune response. Myeloid CLRs represent a major group amongst pattern recognition receptors (PRRs), placing them at the center of the rapidly growing field of glycoimmunology. CLRs have evolved to encompass a wide range of structures and functions and to recognize a large number of glycans and many other ligands from different classes of biopolymers. This review aims at providing the reader with an overview of myeloid CLRs and selected ligands, while highlighting recent insights into CLR-ligand interactions. Subsequently, methodological approaches in CLR-ligand research will be presented. Finally, this review will discuss how CLR-ligand interactions culminate in immunological functions, how glycan mimicry favors immune escape by pathogens, and in which way immune responses can be affected by CLR-ligand interactions in the long term.

Microglial TYROBP/DAP12 in Alzheimer's disease: Transduction of physiological and pathological signals across TREM2.

TYROBP (also known as DAP12 or KARAP) is a transmembrane adaptor protein initially described as a receptor-activating subunit component of natural killer (NK) cells. TYROBP is expressed in numerous cell types, including peripheral blood monocytes, macrophages, dendritic cells, and osteoclasts, but a key point of recent interest is related to the critical role played by TYROBP in the function of many receptors expressed on the plasma membrane of microglia. TYROBP is the downstream adaptor and putative signaling partner for several receptors implicated in Alzheimer's disease (AD), including SIRP1ß, CD33, CR3, and TREM2. TYROBP has received much of its current notoriety because of its importance in brain homeostasis by signal transduction across those receptors. In this review, we provide an overview of evidence indicating that the biology of TYROBP extends beyond its interaction with these four ligand-binding ectodomain-intramembranous domain molecules. In addition to reviewing the structure and localization of TYROBP, we discuss our recent progress using mouse models of either cerebral amyloidosis or tauopathy that were engineered to be TYROBP-deficient or TYROBP-overexpressing. Remarkably, constitutively TYROBP-deficient mice provided a model of genetic resilience to either of the defining proteinopathies of AD. Learning behavior and synaptic electrophysiological function were preserved at normal physiological levels even in the face of robust cerebral amyloidosis (in APP/PSEN1;Tyrobp-/- mice) or tauopathy (in MAPTP301S;Tyrobp-/- mice). A fundamental underpinning of the functional synaptic dysfunction associated with each proteotype was an accumulation of complement C1q. TYROBP deficiency prevented C1q accumulation associated with either proteinopathy. Based on these data, we speculate that TYROBP plays a key role in the microglial sensome and the emergence of the disease-associated microglia (DAM) phenotype. TYROBP may also play a key role in the loss of markers of synaptic integrity (e.g., synaptophysin-like immunoreactivity) that has long been held to be the feature of human AD molecular neuropathology that most closely correlates with concurrent clinical cognitive function.

CSTA plays a role in osteoclast formation and bone resorption by mediating the DAP12/TREM2 pathway.

Cystatin A (CSTA) is a cysteine protease inhibitor that is expressed highly during osteoporosis. However, the exact role of CSTA in osteoporosis remains unknown. In this study, we examined the role of CSTA in the formation, differentiation, and bone resorption of osteoclasts. We extracted bone marrow cells from 8-week-old wildtype mice to obtain RANKL and M-CSF-induced osteoclasts. We performed CSTA overexpression and knockdown experiments in the cells. We analyzed the role of CSTA in the process of osteoclasts by trap staining. In addition, we studied the contribution of CSTA to osteogenesis through the DAP12/TREM2 (DNAX-activating protein of 12 kDa/Triggering receptor expressed on myeloid cells-2) complex. We analyzed the role of CSTA in postmenopausal osteoporosis using OVX mouse models. We found that the silencing of CSTA inhibited the differentiation and formation of osteoclasts. The loss of CSTA weakened the expression of osteoclast marker genes. In contrast, overexpression of CSTA significantly increased differentiation and formation of osteoclasts and enhanced bone resorption. Immunofluorescence staining indicated that CSTA and DAP12 are co-expressed in osteoclasts, and the loss of either DAP12 or TREM2 inhibited osteoclast differentiation and bone resorption. Suppression of CSTA decreased DAP12 and TREM2 expression, whereas overexpression of CSTA rescued the loss of TREM2 expression caused by DAP12 knockdown. Co-immunoprecipitation and co-localization experiments indicated that CSTA interacted with DAP12. In addition, we found that injection of si-CSTA into OVX mice significantly improved bone parameters. Our research indicates that CSTA interacts with the DAP12/TREM2 complex and could be a potential targeted therapy for osteoporosis management.

Artesunate Therapy Alleviates Fracture-Associated Chronic Pain After Orthopedic Surgery by Suppressing CCL21-Dependent TREM2/DAP12 Inflammatory Signaling in Mice.

Chronic pain after bone fracture and orthopedic surgery is often refractory to most analgesics currently in use, thus emphasizing the urgent need for improved therapeutic medications. Chemokine-dependent neuroinflammation is critical for excitatory synaptic plasticity and central nociception sensitization. Recent studies have focused on the inhibition of inflammatory responses by artesunate, the first anti-malaria drug extracted from artemisinin. The present study investigated the analgesic effects and potential targets of artesunate in a mouse model of chronic pain induced by tibial fracture and orthopedic surgery. Three injections of artesunate were intrathecally administered on a daily basis from days 4 to 6 after fracture. We reported that repetitive exposure to artesunate (10 and 100 µg but not 1 µg) dose-dependently prevented fracture-induced mechanical and cold allodynia. Moreover, single intrathecal injection of artesunate (100 µg) alleviated the established chronic pain on day 14 after fracture surgery. Intraperitoneal artesunate (10 and 50 mg kg-1) therapy was effective against chronic fracture pain. Intriguingly, artesunate inhibited the upregulation of spinal chemokine CCL21, triggering receptor expressed on myeloid cells 2 (TREM2) and DNAX-activating protein of 12 kDa (DAP12) expressions and microglia activation in fracture mice. Furthermore, spinal CCL21 neutralization attenuated the severity of fracture-associated post-surgical pain. Exogenous CCL21-induced acute inflammatory pain was impaired by artesunate therapy. Additionally, the pharmacological blockage of TREM2 reduced recombinant CCL21-elicited behavioral hypernociception. The present findings demonstrate that artesunate therapy reduces the initiation and maintenance of fracture-associated chronic postoperative pain by inhibiting CCL21-dependent TREM2/DAP12 inflammatory signaling and microglia activation, thus suggesting that artesunate could emerge as a therapeutic strategy for fracture pain management.

The role of triggering receptor expressed on myeloid cells 2 in Parkinson's disease and other neurodegenerative disorders.

Parkinson's disease (PD) is a progressive neurological disorder marked by cardinal clinical symptoms such as rigor, tremor, and akinesia. Albeit a loss of dopaminergic neurons from the substantia nigra pars compacta is causative for the movement impairments found in patients, molecular reasoning for this loss is still incomplete. In recent years, triggering factor expressed on myeloid cells (TREM2) gained attention in the field of neurodegeneration as it could be associated with different neurodegenerative disorders. Primarily identified as a risk factor in Alzheimer's disease, variants in TREM2 were linked to PD and multiple sclerosis, too. Expressed on phagocytic cells, such as macrophages and microglia, TREM2 puts the focus on inflammation associated conditions in PD and provides a molecular target that could at least partly explain the role of immune cells in PD. Here, we summarize expression patterns and molecular functions of TREM2, recapitulate on its role in inflammation, phagocytosis and cell survival, before turning to neurodegenerative disorders with an emphasis on PD.

Novel two-chain structure utilizing KIRS2/DAP12 domain improves the safety and efficacy of CAR-T cells in adults with r/r B-ALL.

Engineered T cells that express chimeric antigen receptors (CARs) have been a promising therapy for hematologic malignancies. The optimization of CAR structure using different signaling domains can alter a wide range of CAR-T cell properties, including anti-tumor activity, long-term persistence, and safety. In this study, we developed a novel CAR structure based on KIRS2/Dap12 for B cell acute lymphoblastic leukemia (B-ALL) antigen CD19 and compared the anti-tumor efficacy and safety of this construct in transduced T cells with standard second-generation CAR-T cells targeting CD19 for B-ALL in vitro and in vivo and in adult relapsed/refractory (r/r) B-ALL patients. We discovered that KIRS2/Dap12 receptor infused with 4-1BB co-stimulation domain could enhance anti-tumor efficacy by remarkably increasing the production of pro-inflammatory interleukin-2 (IL-2), especially when co-cultured with antigen-positive tumor cells. In addition, CD19-KIRS2/Dap12-BB CAR-T cells showed the inspiring outcome that complete responses were seen in 4 of 4 (100%) patients without neurotoxicity and a high rate of severe cytokine release syndrome (CRS) after CAR-T infusion in a phase I clinical trial. Given these encouraging findings, CD19-KIRS2/Dap12-BB CAR-T cells are safe and can lead to clinical responses in adult patients with r/r B-ALL, indicating that further assessment of this therapy is warranted.

CR3 ruffles FcγR's claim over phagocytic cups.

Phagocytosis plays diverse roles in biology, but our understanding of the purpose, interplay, and cell signaling mechanisms associated with different modes of phagocytosis is limited, without being able to capture and visualize each step in this rapid process from the beginning to end. A new study by Walbaum et al. uses stunning time-lapse 3D imaging of the engulfment of erythrocytes by macrophages via sinking, ruffling, and cup formation, unequivocally confirming a visionary 44-year-old theory derived from still electron microscopy photos that phagocytosis mediated by complement receptor CR3 occurs via a sinking mechanism and antibody-mediated phagocytosis occurs via phagocytic cup formation. The article also challenges the dogma, showing that phagocytic cup formation is not unique to antibody receptor phagocytosis, rather CR3 plays a complex role in different modes of phagocytosis. For example, inhibition of antibody-mediated phagocytosis leads to a compensatory upregulation of CR3-mediated sinking phagocytosis. These findings animate, in vivid colors, processes previously only captured as stills, exposing interactions between different phagocytic mechanisms and altering our basic understanding of this important process.

Rhesus Macaque Activating Killer Immunoglobulin-Like Receptors Associate With Fc Receptor Gamma (FCER1G) and Not With DAP12 Adaptor Proteins Resulting in Stabilized Expression and Enabling Signal Transduction.

Activating killer cell immunoglobulin-like receptors (KIR) in macaques are thought to be derived by genetic recombination of the region encoding the transmembrane and intracellular part of KIR2DL4 and a KIR3D gene. As a result, all macaque activating KIR possess a positively charged arginine residue in the transmembrane region. As human KIR2DL4 associates with the FCER1G (also called Fc receptor-gamma, FcRγ) adaptor, we hypothesized that in contrast to human and great ape the activating KIRs of macaques associate with FcRγ instead of DAP12. By applying co-immunoprecipitation of transfected as well as primary cells, we demonstrate that rhesus macaque KIR3DS05 indeed associates with FcRγ and not with DAP12. This association with FcRγ results in increased and substantially stabilized surface expression of KIR3DS05. In addition, we demonstrate that binding of specific ligands of KIR3DS05, Mamu-A1*001 and A1*011, resulted in signal transduction in the presence of FcRγ in contrast to DAP12.

Constitutively Activated DAP12 Induces Functional Anti-Tumor Activation and Maturation of Human Monocyte-Derived DC.

Dendritic cells (DCs) are professional antigen presenting cells with a great capacity for cross-presentation of exogenous antigens from which robust anti-tumor immune responses ensue. However, this function is not always available and requires DCs to first be primed to induce their maturation. In particular, in the field of DC vaccine design, currently available methodologies have been limited in eliciting a sustained anti-tumor immune response. Mechanistically, part of the maturation response is influenced by the presence of stimulatory receptors relying on ITAM-containing activating adaptor molecules like DAP12, that modulates their function. We hypothesize that activating DAP12 in DC could force their maturation and enhance their potential anti-tumor activity for therapeutic intervention. For this purpose, we developed constitutively active DAP12 mutants that can promote activation of monocyte-derived DC. Here we demonstrate its ability to induce the maturation and activation of monocyte-derived DCs which enhances migration, and T cell stimulation in vitro using primary human cells. Moreover, constitutively active DAP12 stimulates a strong immune response in a murine melanoma model leading to a reduction of tumor burden. This provides proof-of-concept for investigating the pre-activation of antigen presenting cells to enhance the effectiveness of anti-tumor immunotherapies.

Novel ligands and modulators of triggering receptor expressed on myeloid cells receptor family: 2015-2020 updates.

Introduction: Triggering receptors expressed on myeloid cells (TREMs) are inflammatory amplifiers with defined pathophysiological role in various infectious diseases, acute and chronic aseptic inflammations, and a variety of cancers, depicting TREMs as prominent therapeutic targets.Areas covered: Herein, updates from 2015 to 2020 are discussed to divulge the TREM ligands, as well as their peptide blockers, claimed to modulate their expression. The article also presents different strategies employed during the last five years to block interactions between TREMs and their ligands to treat various disease conditions by modulating their expression and activity.Expert opinion: There has been significant progress in the discovery of novel ligands and modulators of TREMs in the last five years that mainly revolved around the function of TREM molecules. A few peptides showed encouraging results to modulate the expression and activity of TREMs in preclinical studies, and these peptides are currently under clinical investigation. Based on the findings so far in several careful studies, we expect novel therapeutics in the near future which could have the ability to treat various disease conditions associated with TREM expression.