Prohibitin1 facilitates viral replication by impairing the RIG-I-like receptor signaling pathway.

IMPORTANCE: Type I interferon (IFN-I), produced by the innate immune system, plays an essential role in host antiviral responses. Proper regulation of IFN-I production is required for the host to balance immune responses and prevent superfluous inflammation. IFN regulatory factor 3 (IRF3) and subsequent sensors are activated by RNA virus infection to induce IFN-I production. Therefore, proper regulation of IRF3 serves as an important way to control innate immunity and viral replication. Here, we first identified Prohibitin1 (PHB1) as a negative regulator of host IFN-I innate immune responses. Mechanistically, PHB1 inhibited the nucleus import of IRF3 by impairing its binding with importin subunit alpha-1 and importin subunit alpha-5. Our study demonstrates the mechanism by which PHB1 facilitates the replication of multiple RNA viruses and provides insights into the negative regulation of host immune responses.

TIGIT inhibition and lenalidomide synergistically promote antimyeloma immune responses after stem cell transplantation in mice.

Autologous stem cell transplantation (ASCT) with subsequent lenalidomide maintenance is standard consolidation therapy for multiple myeloma, and a subset of patients achieve durable progression-free survival that is suggestive of long-term immune control. Nonetheless, most patients ultimately relapse, suggesting immune escape. TIGIT appears to be a potent inhibitor of myeloma-specific immunity and represents a promising new checkpoint target. Here we demonstrate high expression of TIGIT on activated CD8+ T cells in mobilized peripheral blood stem cell grafts from patients with myeloma. To guide clinical application of TIGIT inhibition, we evaluated identical anti-TIGIT antibodies that do or do not engage FcγR and demonstrated that anti-TIGIT activity is dependent on FcγR binding. We subsequently used CRBN mice to investigate the efficacy of anti-TIGIT in combination with lenalidomide maintenance after transplantation. Notably, the combination of anti-TIGIT with lenalidomide provided synergistic, CD8+ T cell-dependent, antimyeloma efficacy. Analysis of bone marrow (BM) CD8+ T cells demonstrated that combination therapy suppressed T cell exhaustion, enhanced effector function, and expanded central memory subsets. Importantly, these immune phenotypes were specific to the BM tumor microenvironment. Collectively, these data provide a logical rationale for combining TIGIT inhibition with immunomodulatory drugs to prevent myeloma progression after ASCT.

Trial of Anti-BDCA2 Antibody Litifilimab for Cutaneous Lupus Erythematosus.

BACKGROUND: Blood dendritic cell antigen 2 (BDCA2) is a receptor that is exclusively expressed on plasmacytoid dendritic cells, which are implicated in the pathogenesis of lupus erythematosus. Whether treatment with litifilimab, a humanized monoclonal antibody against BDCA2, would be efficacious in reducing disease activity in patients with cutaneous lupus erythematosus has not been extensively studied. METHODS: In this phase 2 trial, we randomly assigned adults with histologically confirmed cutaneous lupus erythematosus with or without systemic manifestations in a 1:1:1:1 ratio to receive subcutaneous litifilimab (at a dose of 50, 150, or 450 mg) or placebo at weeks 0, 2, 4, 8, and 12. We used a dose-response model to assess whether there was a response across the four groups on the basis of the primary end point, which was the percent change from baseline to 16 weeks in the Cutaneous Lupus Erythematosus Disease Area and Severity Index-Activity score (CLASI-A; scores range from 0 to 70, with higher scores indicating more widespread or severe skin involvement). Safety was also assessed. RESULTS: A total of 132 participants were enrolled; 26 were assigned to the 50-mg litifilimab group, 25 to the 150-mg litifilimab group, 48 to the 450-mg litifilimab group, and 33 to the placebo group. Mean CLASI-A scores for the groups at baseline were 15.2, 18.4, 16.5, and 16.5, respectively. The difference from placebo in the change from baseline in CLASI-A score at week 16 was -24.3 percentage points (95% confidence interval [CI] -43.7 to -4.9) in the 50-mg litifilimab group, -33.4 percentage points (95% CI, -52.7 to -14.1) in the 150-mg group, and -28.0 percentage points (95% CI, -44.6 to -11.4) in the 450-mg group. The least squares mean changes were used in the primary analysis of a best-fitting dose-response model across the three drug-dose levels and placebo, which showed a significant effect. Most of the secondary end points did not support the results of the primary analysis. Litifilimab was associated with three cases each of hypersensitivity and oral herpes infection and one case of herpes zoster infection. One case of herpes zoster meningitis occurred 4 months after the participant received the last dose of litifilimab. CONCLUSIONS: In a phase 2 trial involving participants with cutaneous lupus erythematosus, treatment with litifilimab was superior to placebo with regard to a measure of skin disease activity over a period of 16 weeks. Larger and longer trials are needed to determine the effect and safety of litifilimab for the treatment of cutaneous lupus erythematosus. (Funded by Biogen; LILAC ClinicalTrials.gov number, NCT02847598.).

Inhibition of TREM-2 Markedly Suppresses Joint Inflammation and Damage in Experimental Arthritis.

The triggering receptors expressed on myeloid cells (TREMs) are a family of activating immune receptors that regulate the inflammatory response. TREM-1, which is expressed on monocytes and/or macrophages and neutrophils, functions as an inflammation amplifier and plays a role in the pathogenesis of rheumatoid arthritis (RA). Unlike TREM-1, the role in RA of TREM-2, which is expressed on macrophages, immature monocyte-derived dendritic cells, osteoclasts, and microglia, remains unclear and controversial. TREM-2 ligands are still unknown, adding further uncertainty to our understanding of TREM-2 function. Previously, we demonstrated that TREM-1 blockade, using a ligand-independent TREM-1 inhibitory peptide sequence GF9 rationally designed by our signaling chain homooligomerization (SCHOOL) model of cell signaling, ameliorates collagen-induced arthritis (CIA) severity in mice. Here, we designed a TREM-2 inhibitory peptide sequence IA9 and tested it in the therapeutic CIA model, either as a free 9-mer peptide IA9, or as a part of a 31-mer peptide IA31 incorporated into lipopeptide complexes (IA31-LPC), for targeted delivery. We demonstrated that administration of IA9, but not a control peptide, after induction of arthritis diminished release of proinflammatory cytokines and dramatically suppressed joint inflammation and damage, suggesting that targeting TREM-2 may be a promising approach for the treatment of RA.

Tiragolumab Results Cast Shadow on TIGIT Pipeline.

Genentech's TIGIT-targeted antibody tiragolumab missed its endpoints in two late-stage lung cancer trials, raising doubts about one of the most widely studied next-generation checkpoint targets in immuno-oncology. But numerical signs of benefit among certain patients with metastatic non-small cell lung cancer suggest that TIGIT blockade still has potential-if drug developers can successfully identify the best indications, drug combinations, or patient populations.

Role of prostaglandin D2 receptors in the pathogenesis of abdominal aortic aneurysm formation.

Prostaglandin D2 (PGD2) released from immune cells or other cell types activates its receptors, D prostanoid receptor (DP)1 and 2 (DP1 and DP2), to promote inflammatory responses in allergic and lung diseases. Prostaglandin-mediated inflammation may also contribute to vascular diseases such as abdominal aortic aneurysm (AAA). However, the role of DP receptors in the pathogenesis of AAA has not been systematically investigated. In the present study, DP1-deficient mice and pharmacological inhibitors of either DP1 or DP2 were tested in two distinct mouse models of AAA formation: angiotensin II (AngII) infusion and calcium chloride (CaCl2) application. DP1-deficient mice [both heterozygous (DP1+/-) and homozygous (DP1-/-)] were protected against CaCl2-induced AAA formation, in conjunction with decreased matrix metallopeptidase (MMP) activity and adventitial inflammatory cell infiltration. In the AngII infusion model, DP1+/- mice, but not DP1-/- mice, exhibited reduced AAA formation. Interestingly, compensatory up-regulation of the DP2 receptor was detected in DP1-/- mice in response to AngII infusion, suggesting a potential role for DP2 receptors in AAA. Treatment with selective antagonists of DP1 (laropiprant) or DP2 (fevipiprant) protected against AAA formation, in conjunction with reduced elastin degradation and aortic inflammatory responses. In conclusion, PGD2 signaling contributes to AAA formation in mice, suggesting that antagonists of DP receptors, which have been extensively tested in allergic and lung diseases, may be promising candidates to ameliorate AAA.

Structural and functional characterization of a monoclonal antibody blocking TIGIT.

TIGIT is an immune checkpoint receptor that is expressed on subsets of activated T cells and natural killer (NK) cells. Several ligands for TIGIT, including poliovirus receptor (PVR), are expressed on cancer cells and mediate inhibitory signaling to suppress antitumor activities of the immune cells. Many studies support that the TIGIT signaling is a potential target for cancer immunotherapy. We developed an IgG4-type monoclonal antibody against human TIGIT, designated as MG1131, using a phage display library of single-chain variable fragments (scFvs). MG1131 interacts with TIGIT much more tightly than PVR does. The crystal structure of a scFv version of MG1131 bound to TIGIT was determined, showing that MG1131 could block the PVR-TIGIT interaction and thus the immunosuppressive signaling of TIGIT. Consistently, MG1131 is bound to TIGIT-expressing cells and interferes with PVR binding to these cells. Moreover, MG1131 increased NK cell-mediated tumor killing activities, inhibited immunosuppressive activity of regulatory T (Treg) cells from healthy donors, and restored interferon-γ secretion from peripheral blood mononuclear cells derived from multiple myeloma patients. MG1131 also increased T cell infiltration to the tumor site and inhibited tumor growth in mice. Collectively, these data indicate that MG1131 modulates the effector functions of T cells and NK cells positively and Treg cells negatively.

Platinum(IV) complexes as inhibitors of CD47-SIRPα axis for chemoimmunotherapy of cancer.

Phagocytosis of cancer cells by antigen presenting cells (APCs) is critical to activate the host's immune responses. However, the targeting ability of APCs to cancer cells is limited by the upregulation of transmembrane protein CD47 on the cancer cell surface. Blocking CD47 can affect the macrophage-mediated phagocytosis. Two platinum-based immunomodulators MUP and DMUP were synthesized to enhance the phagocytic activity of macrophages by blocking the CD47-SIRPα axis. These PtIV complexes not only showed high antiproliferative activity against a panel of human cancer cell lines, but also cooperated with human peripheral blood mononuclear cells (PBMCs) to suppress cancer cells. They acted as immune checkpoint inhibitors to modulate the immune responses of both cancer and immune cells. In particular, DMUP decreased the expression of CD47 in tumor tissues and promoted the polarization of macrophages from M2 to M1 phenotype in a mouse model of non-small cell lung cancer, thereby enhancing the anticancer effect. By interfering with DNA synthesis and stimulating immune system, DMUP takes the advantage of chemotherapy and immunotherapy to inhibit cancer cells. The dual efficacy of DMUP makes it a potential chemoimmunotherapeutic agent in cancer therapy.

TREM2 is thyroid hormone regulated making the TREM2 pathway druggable with ligands for thyroid hormone receptor.

Triggering receptor expressed on myeloid cells-2 (TREM2) is a cell surface receptor on macrophages and microglia that senses and responds to disease-associated signals to regulate the phenotype of these innate immune cells. The TREM2 signaling pathway has been implicated in a variety of diseases ranging from neurodegeneration in the central nervous system to metabolic disease in the periphery. Here, we report that TREM2 is a thyroid hormone-regulated gene and its expression in macrophages and microglia is stimulated by thyroid hormone and synthetic thyroid hormone agonists (thyromimetics). Our findings report the endocrine regulation of TREM2 by thyroid hormone, and provide a unique opportunity to drug the TREM2 signaling pathway with orally active small-molecule therapeutic agents.

Combined Blockade of TIGIT and CD39 or A2AR Enhances NK-92 Cell-Mediated Cytotoxicity in AML.

This study aimed to characterize different natural killer (NK) cell phenotypes on bone marrow and peripheral blood cells from acute myeloid leukemia (AML) patients and healthy donors (HDs). Our data show that CD56dimCD16- and CD56brightCD16- NK cells represent the predominant NK cell subpopulations in AML, while the CD56dimCD16+ NK cells are significantly reduced compared to HDs. Moreover, TIGIT+ and PVRIG+ cells cluster on the CD56dimCD16+ subset whereas CD39+ and CD38+ cells do so on CD56brightCD16- NK cells in AML. Furthermore, functional effects of (co-)blockade of TIGIT and CD39 or A2AR on NK cell functionality were analyzed. These experiments revealed that the single blockade of the TIGIT receptor results in an increased NK-92 cell-mediated killing of AML cells in vitro. Combined targeting of CD39 or A2AR significantly augments the anti-TIGIT-mediated lysis of AML cells. Our data indicate that distinct NK cell subsets in AML exhibit different immunosuppressive patterns (via the TIGIT/PVRIG receptors and the purinergic pathway). In summary, we conclude that TIGIT, CD39, and A2AR constitute relevant inhibitory checkpoints of NK cells in AML patients. A combinatorial blockade synergistically strengthens NK-92 cell-mediated cytotoxicity. As inhibitors of TIGIT, CD39, and A2AR are clinically available, studies on their combined use could be conducted in the near future.

An engineered IL-21 with half-life extension enhances anti-tumor immunity as a monotherapy or in combination with PD-1 or TIGIT blockade.

Interleukin-21 (IL-21) has exhibited anti-tumor activity in preclinical and clinical studies; however, its modest efficacy and short half-time has limited its therapeutic utility as a monotherapy. Therefore, we engineered a fusion protein (IL-21-αHSA) in which a nanobody targeting human serum albumin (HSA) was fused to the C-terminus of rhIL-21. The αHSA nanobody displayed broad species cross-reactivity and bound to a HSA epitope that does not overlap with the FcRn binding site, thus providing a strategic design for half-life extension. The IL-21-αHSA fusion protein showed increased stability compared to rhIL-21, while retaining its bioactivity in a liquid solution for at least 6 months. Moreover, IL-21-αHSA showed a dramatically extended half-life and prolonged exposure in cynomolgus monkeys, with the t1/2 and AUC nearly 10 and 50 times greater than that of rhIL-21, respectively. Furthermore, IL-21-αHSA displayed enhanced anti-tumor efficacy in two syngeneic mouse models. Notably, IL-21-αHSA increased the anti-tumor effect of programmed cell death protein 1 (PD-1) and T cell immunoglobulin and ITIM domain (TIGIT) blockades when used in combination, with a protection against tumor rechallenge, suggesting the formation of long-term anti-tumor memory response. KEGG analysis identified significantly enriched pathways associated with anti-tumor immune response, with increased expression of genes associated with CD8+ T and NK cell cytotoxicity. Overall, these data support further clinical evaluation of IL-21-αHSA as a monotherapy or in combination with immune checkpoint blockades.

Discovery of Active Ingredients Targeted TREM2 by SPR Biosensor-UPLC/MS Recognition System, and Investigating the Mechanism of Anti-Neuroinflammatory Activity on the Lignin-Amides from Datura metel Seeds.

As a new target protein for Alzheimer's disease (AD), the triggering receptor expressed on myeloid Cells 2 (TREM2) was expressed on the surface of microglia, which was shown to regulate neuroinflammation, be associated with a variety of neuropathologic, and regarded as a potential indicator for monitoring AD. In this study, a novel recognition system based on surface plasmon resonance (SPR) for the TREM2 target spot was established coupled with quadrupole time-of-flight tandem mass spectrometry (UPLC-MS), in order to screen the active ingredients targeting TREM2 from Datura metel seeds. The results showed that four lignan-amides were discovered as candidate compounds by SPR biosensor-UPLC/MS recognition analysis. According to the guidance of the active ingredients discovered by the system, the lignin-amides from Datura metel seeds (LDS) were preliminarily identified as containing 27 lignan-amides, which were enriched compositions by the HP-20 of Datura metel seeds. Meanwhile, the anti-inflammatory activity of LDS was evaluated in BV2 microglia induced by LPS. Our experimental results demonstrated that LDS could reduce NO release in LPS-treated BV2 microglia cells and significantly reduce the expression of the proteins of inducible Nitric Oxide Synthase (iNOS), cyclooxygenase 2 (COX-2), microtubule-associated protein tau (Tau), and ionized calcium-binding adapter molecule 1 (IBA-1). Accordingly, LDS might increase the expression of TREM2/DNAX-activating protein of 12 kDa (DAP12) and suppress the Toll-like receptor SX4 (TLR4) pathway and Recombinant NLR Family, Pyrin Domain Containing Protein 3 (NLRP3)/cysteinyl aspartate specific proteinase-1 (Caspase-1) inflammasome expression by LDS in LPS-induced BV2 microglial cells. Then, the inhibitory release of inflammatory factors Interleukin 1 beta (IL-1ß), Interleukin 6 (IL-6), and Tumor necrosis factor-alpha (TNFα) inflammatory cytokines were detected to inhibit neuroinflammatory responses. The present results propose that LDS has potential as an anti-neuroinflammatory agent against microglia-mediated neuroinflammatory disorders.

Therapeutic melanoma inhibition by local micelle-mediated cyclic nucleotide repression.

The acidic tumor microenvironment in melanoma drives immune evasion by up-regulating cyclic adenosine monophosphate (cAMP) in tumor-infiltrating monocytes. Here we show that the release of non-toxic concentrations of an adenylate cyclase (AC) inhibitor from poly(sarcosine)-block-poly(L-glutamic acid γ-benzyl ester) (polypept(o)id) copolymer micelles restores antitumor immunity. In combination with selective, non-therapeutic regulatory T cell depletion, AC inhibitor micelles achieve a complete remission of established B16-F10-OVA tumors. Single-cell sequencing of melanoma-infiltrating immune cells shows that AC inhibitor micelles reduce the number of anti-inflammatory myeloid cells and checkpoint receptor expression on T cells. AC inhibitor micelles thus represent an immunotherapeutic measure to counteract melanoma immune escape.

Targeting TREM2 on tumor-associated macrophages enhances immunotherapy.

Converting checkpoint inhibitor (CPI)-resistant individuals to being responsive requires identifying suppressive mechanisms. We identify TREM2+ tumor-associated macrophages (TAMs) as being correlated with exhausted CD8+ tumor-infiltrating lymphocytes (TILs) in mouse syngeneic tumor models and human solid tumors of multiple histological types. Fc domain-enhanced anti-TREM2 monoclonal antibody (mAb) therapy promotes anti-tumor immunity by elimination and modulation of TAM populations, which leads to enhanced CD8+ TIL infiltration and effector function. TREM2+ TAMs are most enriched in individuals with ovarian cancer, where TREM2 expression corresponds to disease grade accompanied by worse recurrence-free survival. In an aggressive orthotopic ovarian cancer model, anti-TREM2 mAb therapy drives potent anti-tumor immunity. These results highlight TREM2 as a highly attractive target for immunotherapy modulation in individuals who are refractory to CPI therapy and likely have a TAM-rich tumor microenvironment.

TIGIT Induces (CD3+) T Cell Dysfunction in Colorectal Cancer by Inhibiting Glucose Metabolism.

T-cell immunoglobulin and immunoreceptor tyrosine-based inhibitory motif domain (TIGIT) is an immunosuppressive receptor expressed on the surface of immune cells, suppressing immune responses by activating the intracellular negative regulatory signals. TIGIT plays an important role in the pathogenesis of various tumors, but its immune escape in colorectal cancer remains unclear. We found that the proportion of CD3+TIGIT+ T cells was increased in peripheral blood and cancer tissue in colorectal cancer patients when compared with the healthy donors. These cells exhibited functional defects, low proliferative activity, impaired cytokine production and reduced glucose metabolism. A strong association was also observed between the elevated TIGIT expression and poor prognosis in this cohort. In the in vitro co-culture assays of T cells and tumor cells, the suppressed glucose metabolic activity of T cells was reversed by TIGIT blockade. In addition, this blockade induced the apoptosis and reduced G2/M transit in tumor cells. The antitumor efficacy of TIGIT Ab therapy was further demonstrated in a human colorectal xenograft mice model while co-blockers of TIGIT and PD-1 exhibited synergistic suppressing effects on tumor growth. These results suggest that while TIGIT induces CD3+ T cell dysfunction in colorectal cancer, co-targeting TIGIT and PD-1 can lead to an effective antitumor response and may serve as a novel therapeutic strategy for colorectal patients.

Simultaneous blockade of TIGIT and HIF-1α induces synergistic anti-tumor effect and decreases the growth and development of cancer cells.

PURPOSE: T-cell immunoglobulin and ITIM domain (TIGIT) is an immune checkpoint that is overexpressed on both immune cells and some cancer cells. TIGIT can alter the anti-tumor responses inside the tumor microenvironment. Hypoxia-inducible factor 1-alpha (HIF-1α) plays a significant role in the TME and involves suppressing the anti-tumor responses. Under hypoxic conditions, HIF-1α can enhance the expression of different immune checkpoints. Accordingly, hypoxic TME and TIGIT overexpression cause cancer development. Thus, we decided to inhibit tumor cell expansion by inhibiting TIGIT and HIF-1α molecules and discovering the relationship between TIGIT and HIF-1α. METHODS: In this research, we utilized superparamagnetic iron oxide-based NPs (SPIONs) combined with chitosan lactate (CL) and folic acid (FA) nanoparticles (NPs) loaded with TIGIT-siRNA and HIF-1α- siRNA for suppressing TIGIT and HIF-1α in tumor cells and evaluated the consequences of this treatment strategy on tumor growth, apoptosis, and metastasis. RESULTS: The results showed that cancer cells treated with TIGIT and HIF-1α siRNA-loaded SPIONs-CL-FA NPs, strongly suppressed the TIGIT and HIF-1α expression, colony formation ability, angiogenesis, and the growth rate of cancer cells. CONCLUSIONS: Present data suggest the combination treatment of TIGIT and HIF-1α as a novel treatment strategy against colorectal and breast cancer, but more researches are required to realize the complete role of TIGIT and HIF-1α inside the TME.

Deregulated Expression of Immune Checkpoints on Circulating CD4 T Cells May Complicate Clinical Outcome and Response to Treatment with Checkpoint Inhibitors in Multiple Myeloma Patients.

Unlike solid-tumor patients, a disappointingly small subset of multiple myeloma (MM) patients treated with checkpoint inhibitors derive clinical benefits, suggesting differential participation of inhibitory receptors involved in the development of T-cell-mediated immunosuppression. In fact, T cells in MM patients have recently been shown to display features of immunosenescence and exhaustion involved in immune response inhibition. Therefore, we aimed to identify the dominant inhibitory pathway in MM patients to achieve its effective control by therapeutic interventions. By flow cytometry, we examined peripheral blood (PB) CD4 T cell characteristics assigned to senescence or exhaustion, considering PD-1, CTLA-4, and BTLA checkpoint expression, as well as secretory effector function, i.e., capacity for IFN-γ and IL-17 secretion. Analyses were performed in a total of 40 active myeloma patients (newly diagnosed and treated) and 20 healthy controls. At the single-cell level, we found a loss of studied checkpoints' expression on MM CD4 T cells (both effector (Teff) and regulatory (Treg) cells) primarily at diagnosis; the checkpoint deficit in MM relapse was not significant. Nonetheless, PD-1 was the only checkpoint distributed on an increased proportion of T cells in all MM patients irrespective of disease phase, and its expression on CD4 Teff cells correlated with adverse clinical courses. Among patients, the relative defect in secretory effector function of CD4 T cells was more pronounced at myeloma relapse (as seen in declined Th1/Treg and Th17/Treg cell rates). Although the contribution of PD-1 to MM clinical outcomes is suggestive, our study clearly indicated that the inappropriate expression of immune checkpoints (associated with dysfunctionality of CD4 T cells and disease clinical phase) might be responsible for the sub-optimal clinical response to therapeutic checkpoint inhibitors in MM.

Hypoxia/ischemia impairs CD33 (Siglec-3)/TREM2 signaling: Potential role in Alzheimer's pathogenesis.

Recent genetic and molecular studies have indicated that the innate immune system, especially microglia, have a crucial role in the accumulation of ß-amyloid plaques in Alzheimer's disease (AD). In particular, the CD33 receptor, also called Siglec-3, inhibits the TREM2 receptor-induced phagocytic activity of microglia. CD33 receptors recognize the α2,3 and α2,6-linked sialic groups in tissue glycocalyx, especially sialylated gangliosides in human brain. The CD33 receptor triggers cell-type specific responses, e.g., in microglia, CD33 inhibits phagocytosis, whereas in natural killer cells, it inhibits the cytotoxic activity of the NKG2D receptor. Nonetheless, the regulation of the activity of CD33 receptor needs to be clarified. For example, it seems that hypoxia/ischemia, a potential cause of AD pathology, increases the expression of CD33 and its downstream target SHP-1, a tyrosine phosphatase which suppresses the phagocytosis driven by TREM2. Moreover, hypoxia/ischemia increases the deposition of sialylated gangliosides, e.g., GM1, GM2, GM3, and GD1, which are ligands for inhibitory CD33/Siglec-3 receptors. In addition, ß-amyloid peptides bind to the sialylated gangliosides in raft-like clusters and subsequently these gangliosides act as seeds for the formation of ß-amyloid plaques in AD pathology. It is known that senile plaques contain sialylated GM1, GM2, and GM3 gangliosides, i.e., the same species induced by hypoxia/ischemia treatment. Sialylated gangliosides in plaques might stimulate the CD33/Siglec-3 receptors of microglia and thus impede TREM2-driven phagocytosis. We propose that hypoxia/ischemia, e.g., via the accumulation of sialylated gangliosides, prevents the phagocytosis of ß-amyloid deposits by inhibiting CD33/TREM2 signaling.

The Landscape of Immunotherapy in Advanced NSCLC: Driving Beyond PD-1/PD-L1 Inhibitors (CTLA-4, LAG3, IDO, OX40, TIGIT, Vaccines).

PURPOSE OF REVIEW: In this review, we analyzed the current landscape of non-PD-(L)1 targeting immunotherapy. RECENT FINDINGS: The advent of immunotherapy has completely changed the standard approach toward advanced NSCLC. Inhibitors of the PD-1/PD-L1 axis have quickly taken place as first-line treatment for NSCLC patients without targetable "driver" mutations. However, a non-negligible portion of patients derive modest benefit from immune-checkpoint inhibitors, and valid second-line alternatives are lacking, pushing researchers to analyze other molecules and pathways as potentially viable targets in the struggle against NSCLC. Starting from the better characterized CTLA-4 inhibitors, we then critically collected the actual knowledge on NSCLC vaccines as well as on other emerging molecules, many of them in their early phase of testing, to provide to the reader a comprehensive overview of the state of the art of immunotherapy in NSCLC beyond PD-1/PD-L1 inhibitors.

Rapid, sensitive and cost-effective determination of immune checkpoint inhibitor activity using a magnetic bead-based binding assay.

Immune checkpoint Inhibitors (ICIs) are effective immunno-therapeutic agents for cancer. Rapid and sensitive determination of the blocking activity of ICIs is important for ICIs development and immunological research. Among various immune checkpoint (IC) binding assays, cell-based binding assays are widely regarded, and the functional ELISA is a convenient alternative. However, these methodologies are limited by time-consuming preparation of cell lines stably expressing IC molecules, or long turnaround time with high cost. In this study, two magnetic bead based binding assays were developed to evaluate activity of ICIs, which was determined by a soluble ligand/bead immobilized receptor based binding assay (sL/bR binding assay) that assessed efficacy to block binding of one soluble IC ligand on its cognate receptor immobilized beads, or by a soluble receptor/bead immobilized ligand based binding assay (sR/bL binding assay) that assessed efficacy to block binding of soluble IC receptor on its cognate ligand immobilized beads. Half maximal inhibitory concentration (IC50) values of ICIs were calculated to determine ICIs activity. The sL/bR binding assay accurately determined the activity of two TIGIT blocking antibodies, since the relative blocking activity of two TIGIT antibodies determined by the sL/bR binding assay established in this study and that by the cell based binding assay were almost identical. In contrast, the sR/bL binding assay showed significantly improved sensitivity to determine activity of two PD-1 blocking antibodies than the sL/bR binding assay that was tested in this study and previous reports. Moreover, both amount of the used recombinant protein of ICI receptor/ligand and turnaround time of the two binding assays were more than 10 times less than those of the functional ELISA. These data indicate that the two magnetic bead based binding assays are sensitive, rapid and cost-effective methods to determine blocking activity of ICIs.