Immunomodulatory Receptors Research Articles

Experimental and genetic evidence for the impact of CD5 and CD6 expression and variation in inflammatory bowel disease

Crohn’s disease (CD) and ulcerative colitis (UC) are inflammatory bowel diseases (IBD) resulting from the interaction of multiple environmental, genetic and immunological factors. CD5 and CD6 are paralogs encoding lymphocyte co-receptors involved in fine-tuning intracellular signals delivered upon antigen-specific recognition, microbial pattern recognition and cell adhesion. While CD5 and CD6 expression and variation is known to influence some immune-mediated inflammatory disorders, their role in IBD remains unclear. To this end, Cd5- and Cd6-deficient mice were subjected to dextran sulfate sodium (DSS)-induced colitis, the most widely used experimental animal model of IBD. The two mouse lines showed opposite results regarding body weight loss and disease activity index (DAI) changes following DSS-induced colitis, thus supporting Cd5 and Cd6 expression involvement in the pathophysiology of this experimental IBD model. Furthermore, DNA samples from IBD patients of the ENEIDA registry were used to test association of CD5 (rs2241002 and rs2229177) and CD6 (rs17824933, rs11230563, and rs12360861) single nucleotide polymorphisms with susceptibility and clinical parameters of CD (n=1352) and UC (n=1013). Generalized linear regression analyses showed association of CD5 variation with CD ileal location (rs2241002CC) and requirement of biological therapies (rs2241002C-rs2229177T haplotype), and with poor UC prognosis (rs2241002T-rs2229177T haplotype). Regarding CD6, association was observed with CD ileal location (rs17824933G) and poor prognosis (rs12360861G), and with left-sided or extensive UC, and absence of ankylosing spondylitis in IBD (rs17824933G). The present experimental and genetic evidence support a role for CD5 and CD6 expression and variation in IBD’s clinical manifestations and therapeutic requirements, providing insight into its pathophysiology and broadening the relevance of both immunomodulatory receptors in immune-mediated disorders.

969TiP Randomized, phase III study of MK-7684A plus concurrent chemoradiotherapy (cCRT) followed by MK-7684A vs cCRT followed by durvalumab for unresectable, locally advanced, stage III non-small cell lung cancer (NSCLC): KEYVIBE-006

Pembrolizumab (pembro; anti‒PD-1) + cCRT demonstrated robust antitumor activity and manageable safety in the KEYNOTE-799 study in previously untreated, locally advanced, stage III NSCLC. The combination of vibostolimab (MK-7684; monoclonal antibody that inhibits T-cell immunoglobulin and ITIM domain [TIGIT] immunomodulatory receptor) + pembro with/without chemotherapy (chemo) has shown promising antitumor activity with manageable safety in patients (pts) with advanced NSCLC in the KEYVIBE-001 study. The KEYVIBE-006 study (NCT05298423) is evaluating MK-7684A (co-formulation of vibostolimab + pembro) + cCRT followed by MK-7684A vs cCRT followed by durvalumab (anti‒PD-L1) in unresectable, locally advanced, stage III NSCLC. In this phase 3, open-label, randomized study, ∼784 eligible adults with previously untreated, unresectable, pathologically confirmed stage IIIA‒C NSCLC; measurable disease by RECIST v1.1; and ECOG PS of 0/1 will be randomized 1:1. In arm A, pts receive intravenous (IV) MK-7684A (vibostolimab 200 mg + pembro 200 mg) Q3W + 3 cycles of chemo (one of: cisplatin 75 mg/m2 + pemetrexed 500 mg/m2 [nonsquamous only]; cisplatin 50 mg/m2 + etoposide 50 mg/m2; or carboplatin AUC 6 mg/mL/min [cycle 1] and AUC 2 mg/mL/min [cycles 2/3] + paclitaxel 200 mg/m2 [cycle 1] and 45 mg/m2 [cycles 2/3]) + standard thoracic radiotherapy (TRT; 60 Gy in 2-Gy fractions; cycles 2/3) followed by vibostolimab 200 mg + pembro 200 mg for up to 17 cycles. Pts in arm B receive 3 cycles of chemo + TRT (as above) followed by durvalumab 10 mg/kg IV Q2W for up to 26 cycles. Treatment continues until treatment completion, PD, unacceptable toxicity, or investigator decision. Randomization is stratified by histology (squamous vs nonsquamous), stage (IIIA vs IIIB/IIIC), PD-L1 TPS (<1% vs ≥1%), and region (East Asia vs North America/Western Europe/Australia vs rest of world). Dual primary endpoints are PFS per RECIST v1.1 by blinded independent central review (BICR) and OS. Secondary endpoints include ORR and DOR per RECIST v1.1 by BICR, safety, and patient-reported outcomes. Enrollment began in May 2022. NCT05298423 Medical writing support was provided by Christabel Wilson, MSc, of ICON plc (Blue Bell, PA, USA). Merck Sharp & Dohme LLC, a subsidiary of Merck & Co., Inc., Rahway, NJ, USA.

Interleukin-1 receptor antagonist enhances the therapeutic efficacy of a low dose of rhBMP-2 in a weight-bearing rat femoral defect model

In the clinical treatment of fractures, rhBMP-2 administration is associated with a well-established profile of side-effects, including osteolysis and ectopic bone formation, which are driven by pro-inflammatory processes triggered by the use of high doses. Immunomodulatory strategies could minimize the incidence of side-effects by enabling the use of lower, and safer, rhBMP-2 doses. This study investigated whether interleukin-1 receptor antagonist (IL-1Ra) can enhance the therapeutic efficacy of a low dose of rhBMP-2 in a weight-bearing femoral fracture healing model. Exogenous IL-1Ra, in combination with rhBMP-2, was delivered using a collagen-hydroxyapatite scaffold (CHA) to attenuate IL-1β produced in response to fracture. Femoral defects were treated with CHA scaffolds alone, or loaded with IL-1Ra (2.5 µg), rhBMP-2 (1 µg), IL-1Ra (2.5 µg) in combination with rhBMP-2 (1 µg). Bone healing was assessed over 14 weeks in comparison to control groups, empty defect, and a higher dose of rhBMP-2 (5 µg), which were recently demonstrated to lead to non-union, and successful bridging of the defect, respectively. The combination of IL-1Ra and rhBMP-2 led to significantly faster early bone formation, at both week 4 and 6, compared to a low dose of rhBMP-2 alone. By 14 weeks, the combination of IL-1Ra and a rhBMP-2 promoted full bridging of femurs, which were 3-fold more mechanically reliable compared to the femurs treated with a low dose of rhBMP-2 alone. Taken together, this study demonstrates that IL-1Ra can significantly enhance femoral bone healing when used in combination with a low dose of rhBMP-2. Statement of significanceEnabling the use of lower and safer doses of rhBMP-2, a potent inducer of bone formation, is of clinical relevance in orthopaedic medicine. In this study, the immunomodulatory interleukin-1 receptor antagonist (IL-1Ra) was investigated for its capacity to enhance the therapeutic efficacy of rhBMP-2 when used at lower doses in a weight-bearing femoral fracture healing model. The combination of IL-1Ra and rhBMP-2 led to significantly faster early bone formation, and resulted in more mechanically reliable healed femurs, compared to a low dose of rhBMP-2 alone. This demonstrates for the first time in a rat long bone healing model that IL-1Ra can significantly enhance bone healing when used in combination with a low dose of rhBMP-2.

Amniotic fluid biomarkers predict the severity of congenital cytomegalovirus infection.

BACKGROUNDCytomegalovirus (CMV) is the most common intrauterine infection, leading to infant brain damage. Prognostic assessment of CMV-infected fetuses has remained an ongoing challenge in prenatal care, in the absence of established prenatal biomarkers of congenital CMV (cCMV) infection severity. We aimed to identify prognostic biomarkers of cCMV-related fetal brain injury.METHODSWe performed global proteome analysis of mid-gestation amniotic fluid samples, comparing amniotic fluid of fetuses with severe cCMV with that of asymptomatic CMV-infected fetuses. The levels of selected differentially excreted proteins were further determined by specific immunoassays.RESULTSUsing unbiased proteome analysis in a discovery cohort, we identified amniotic fluid proteins related to inflammation and neurological disease pathways, which demonstrated distinct abundance in fetuses with severe cCMV. Amniotic fluid levels of 2 of these proteins — the immunomodulatory proteins retinoic acid receptor responder 2 (chemerin) and galectin-3–binding protein (Gal-3BP) — were highly predictive of the severity of cCMV in an independent validation cohort, differentiating between fetuses with severe (n = 17) and asymptomatic (n = 26) cCMV, with 100%–93.8% positive predictive value, and 92.9%–92.6% negative predictive value (for chemerin and Gal-3BP, respectively). CONCLUSIONAnalysis of chemerin and Gal-3BP levels in mid-gestation amniotic fluids could be used in the clinical setting to profoundly improve the prognostic assessment of CMV-infected fetuses.FUNDINGIsrael Science Foundation (530/18 and IPMP 3432/19); Research Fund – Hadassah Medical Organization.

Identify the Prognostic and Immune Profile of VSIR in the Tumor Microenvironment: A Pan-Cancer Analysis.

VSIR is a critical immunomodulatory receptor that inhibits T cell effector function and maintains peripheral tolerance. However, the mechanism by which VSIR participates in tumor immunity in the pan-cancer tumor microenvironment remains unclear. This study systematically explored the prognostic and immune profile of VSIR in the tumor microenvironment of 33 cancers. We compared the expression patterns and molecular features of VSIR in the normal and cancer samples both from the public databases and tumor chips. VSIR level was significantly related to patients’ prognosis and could be a promising predictor in many tumor types, such as GBM, KIRC, SKCM, READ, and PRAD. Elevated VSIR was closely correlated with infiltrated inflammatory cells, neoantigens expression, MSI, TMB, and classical immune checkpoints in the tumor microenvironment. Enrichment signaling pathways analysis indicated VSIR was involved in several immune-related pathways such as activation, proliferation, and migration of fibroblast, T cell, mast cell, macrophages, and foam cell. In addition, VSIR was found to widely express on cancer cells, fibroblasts, macrophages, and T cells in many tumor types based on the single-cell sequencing analysis and co-express with M2 macrophage markers CD68, CD163 based on the immunofluorescence staining. Finally, we predicted the sensitive drugs targeting VSIR and the immunotherapeutic value of VSIR. In sum, VSIR levels strongly correlated with the clinical outcome and tumor immunity in multiple cancer types. Therefore, therapeutic strategies targeting VSIR in the tumor microenvironment may be valuable tools for cancer immunotherapy.

Transgenic mouse models to study the physiological and pathophysiological roles of human Siglecs.

Sialic acid-binding immunoglobulin-like lectins (Siglecs) are important immunomodulatory receptors. Due to differences between human and mouse Siglecs, defining the in vivo roles for human Siglecs (hSiglecs) can be challenging. One solution is the development and use of hSiglec transgenic mice to assess the physiological roles of hSiglecs in health and disease. These transgenic mice can also serve as important models for the pre-clinical testing of immunomodulatory approaches that are based on targeting hSiglecs. Four general methods have been used to create hSiglec-expressing transgenic mice, each with associated advantages and disadvantages. To date, transgenic mouse models expressing hSiglec-2 (CD22), -3 (CD33), -7, -8, -9, -11, and -16 have been created. This review focuses on both the generation of these hSiglec transgenic mice, along with the important findings that have been made through their study. Cumulatively, hSiglec transgenic mouse models are providing a deeper understanding of the differences between human and mice orthologs/paralogs, mechanisms by which Siglecs regulate immune cell signaling, physiological roles of Siglecs in disease, and different paradigms where targeting Siglecs may be therapeutically advantageous.

Spatial proteomics finds CD155 and Endophilin-A1 as mediators of growth and invasion in medulloblastoma.

The composition of the plasma membrane (PM)-associated proteome of tumor cells determines cell-cell and cell-matrix interactions and the response to environmental cues. Whether the PM-associated proteome impacts the phenotype of Medulloblastoma (MB) tumor cells and how it adapts in response to growth factor cues is poorly understood. Using a spatial proteomics approach, we observed that hepatocyte growth factor (HGF)-induced activation of the receptor tyrosine kinase c-MET in MB cells changes the abundance of transmembrane and membrane-associated proteins. The depletion of MAP4K4, a pro-migratory effector kinase downstream of c-MET, leads to a specific decrease of the adhesion and immunomodulatory receptor CD155 and of components of the fast-endophilin-mediated endocytosis (FEME) machinery in the PM-associated proteome of HGF-activated MB cells. The decreased surface expression of CD155 or of the fast-endophilin-mediated endocytosis effector endophilin-A1 reduces growth and invasiveness of MB tumor cells in the tissue context. These data thus describe a novel function of MAP4K4 in the control of the PM-associated proteome of tumor cells and identified two downstream effector mechanisms controlling proliferation and invasiveness of MB cells.

Development and characterization of anti-galectin-9 antibodies that protect T cells from galectin-9-induced cell death

Antibodies that target immune checkpoint proteins such as programmed cell death protein 1, programmed death ligand 1, and cytotoxic T-lymphocyte–associated antigen 4 in human cancers have achieved impressive clinical success; however, a significant proportion of patients fail to respond to these treatments. Galectin-9 (Gal-9), a β-galactoside-binding protein, has been shown to induce T-cell death and facilitate immunosuppression in the tumor microenvironment by binding to immunomodulatory receptors such as T-cell immunoglobulin and mucin domain–containing molecule 3 and the innate immune receptor dectin-1, suggesting that it may have potential as a target for cancer immunotherapy. Here, we report the development of two novel Gal-9-neutralizing antibodies that specifically react with the N-carbohydrate-recognition domain of human Gal-9 with high affinity. We also show using cell-based functional assays that these antibodies efficiently protected human T cells from Gal-9-induced cell death. Notably, in a T-cell/tumor cell coculture assay of cytotoxicity, these antibodies significantly promoted T cell-mediated killing of tumor cells. Taken together, our findings demonstrate potent inhibition of human Gal-9 by neutralizing antibodies, which may open new avenues for cancer immunotherapy.

The Ecto-5'nucleotidase/CD73 Mediates Leishmania amazonensis Survival in Macrophages.

Endogenous nucleotides produced by various group of cells under inflammatory conditions act as potential danger signals in vivo. Extracellularly released nucleotides such as ATP are rapidly hydrolyzed to adenosine by the coordinated ectonucleotidase activities of CD39 and CD73. Leishmania is an obligate intracellular parasite of macrophages and capable of modulating host immune response in order to survive and multiply within host cells. In this study, the activity of CD73 induced by Leishmania amazonensis in infected macrophages has been investigated and correlated with parasite survival and infection in vitro. For this, the expression of CD39 and CD73, by flow cytometry, in murine peritoneal macrophages infected with metacyclic promastigotes of L. amazonensis has been analyzed. Our results showed that L. amazonensis-infected macrophages, unlike LPS-treated macrophages, increased CD73 expression. It was also noted that when CD73 enzymatic activity was blocked by α, β-methyleneadenosine 5′-diphosphate sodium salt (APCP), macrophage parasitism was significantly decreased. Interestingly, these effects were not associated with the production of TNF-α, IL-10, or nitric oxide (NO). Together, these data demonstrate that L. amazonensis induces a regulatory phenotype in macrophages, which by activating the CD39/CD73 pathway allows parasite survival through the action of immunomodulatory adenosine receptors.

Differential Expression of Genes Involved in Metabolism and Immune Response in Diffuse and Intestinal Gastric Cancers, a Pilot Ptudy

Gastric cancer (GC) is one of the major causes of cancer-related mortality worldwide. The vast majority of GC cases are adenocarcinomas including intestinal and diffuse GC. The incidence of diffuse GCs, often associated with poor overall survival, has constantly increased in USA and Europe The molecular basis of diffuse GC aggressivity remains unclear. Using mRNA from diffuse and intestinal GC tumor samples of a Western cohort, this study reports the expression level of the immunomodulatory aryl-hydrocarbon receptor (AhR), and genes involved in immune suppression (PD1, PD-L1, PD-L2) and the early steps of tryptophan metabolism (IDO1, IDO2, TDO2). Strongly increased expression of IDO1 (p < 0.001) and PD1 (p < 0.003) was observed in the intestinal sub-type. The highest expression of IDO1 and PDL1 correlated with early clinical stage and absence of lymphatic invasion (×25 p = 0.004, ×3 p = 0.04, respectively). Our results suggest that kynurenine, produced by tryptophan catabolism, and AhR activation play a central role in creating an immunosuppressive environment. Correspondingly, as compared to intestinal GCs, expression levels of IDO1-TDO2 and PD-L1 were less prominent in diffuse GCs which also had less infiltration of immune cells, suggesting an inactive immune response in the advanced diffuse GC. Confirmation of these patterns of gene expression will require a larger cohort of early and advanced stages of diffuse GC samples.

A triple-negative breast cancer surrogate subtype classification that correlates with gene expression subtypes.

This study developed a triple-negative breast cancer (TNBC) surrogate subtype classification that represents TNBC subtypes based on the Vanderbilt subtype classification. Patients who underwent primary curative surgery for TNBC were included. Representative FFPE blocks were used for gene expression analysis and tissue microarray construction for immunohistochemical (IHC) staining. The Vanderbilt subtypes were re-classified into four groups: basal-like (BL), mesenchymal-like (M), immunomodulatory (IM) and luminal androgen receptor (LAR) subtype. Classification and regression tree (CART) modeling was applied to develop a surrogate subtype classification. A total of 145 patients were included. The study cohort was allocated to the Vanderbilt 4 subtypes as LAR (n = 22, 15.2%), IM (n = 32, 22.1%), M (n = 38, 26.2%), BL (n = 25, 17.2%) and unclassified (n = 28, 19.3%). After excluding nine (6.2%) patients due to poor IHC staining quality, CART modeling was performed. TNBC surrogate subtypes were defined as follows: LAR subtype, androgen receptor Allred score 8; IM subtype, LAR-negative with a tumor-infiltrating lymphocyte (TIL) score > 70%; M subtype, LAR-negative with a TIL score < 20%; BL subtype, LAR-negative with a TIL score 20-70% and diffuse, strong p16 staining. The study cohort was classified by the surrogate subtypes as LAR (n = 26, 17.9%), IM (n = 21, 14.5%), M (n = 44, 30.3%), BL1 (n = 27, 18.6%) and unclassified (n = 18, 12.4%). Surrogate subtypes predicted TNBC Vanderbilt 4 subtypes with an accuracy of 0.708. We have developed a TNBC surrogate subtype classification that correlates with the Vanderbilt subtype. It is a practical and accessible diagnostic test that can be easily applied in clinical practice.

Sugar-decorated carbon dots: a novel tool for targeting immunomodulatory receptors.

Interactions between sialic acid (Sia) and sialic acid-binding immunoglobulin-like lectins (siglecs) regulate the immune system, with aberrations contributing to pathologies such as autoimmunity, infectious disease and cancer. Over the last decade, several multivalent Sia ligands have been synthesized to modulate the Sia-binding affinity of proteins/lectins. Here, we report a novel class of multivalent siglec probes through the decoration of α(2,6)-sialyllactose ligands on inherently fluorescent carbon dots (CD). We show that the preference of α(2,3)-linked Sia for siglec-1 can be altered by increasing the multivalence of Sia ligands present on the CD, and that a locally high glycan concentration can have a direct effect on linkage specificity. Additionally, micromolar (IC50 ∼ 70 μM) interaction of α(2,6)-sialyllactose-CD (6-CD) with siglec-2 (CD22) revealed it was capable of generating a significant cytotoxic effect on Burkitt's Lymphoma (BL) Daudi B cells. This phenonomen was attributed to 6-CD's ability to form trans interactions with CD22 on masked BL Daudi cells as a direct result of clustering of the Sia moiety on the CD surface. Overall, our glycoengineered carbon dots represent a novel high affinity molecular probe with multiple applications in sialoglycoscience and medicine.

Association of Tumor Site With the Prognosis and Immunogenomic Landscape of Human Papillomavirus–Related Head and Neck and Cervical Cancers

Human papillomavirus (HPV)-positive status in patients with oropharyngeal squamous cell carcinoma (OPSCC) is associated with improved survival compared with HPV-negative status. However, it remains controversial whether HPV is associated with improved survival among patients with nonoropharyngeal and cervical squamous cell tumors. To investigate differences in the immunogenomic landscapes of HPV-associated tumors across anatomical sites (the head and neck and the cervix) and their association with survival. This cohort study used genomic and transcriptomic data from the Cancer Genome Atlas (TCGA) for 79 patients with OPSCC, 435 with nonoropharyngeal head and neck squamous cell carcinoma (non-OP HNSCC), and 254 with cervical squamous cell carcinoma and/or endocervical adenocarcinoma (CESC) along with matched clinical data from TCGA. The data were analyzed from November 2020 to March 2021. Positivity for HPV was classified by RNA-sequencing reads aligned with the HPV reference genome. Gene expression profiles, immune cell phenotypes, cytolytic activity scores, and overall survival were compared by HPV tumor status across multiple anatomical sites. The study comprised 768 patients, including 514 (66.9%) with HNSCC (380 male [73.9%]; mean [SD] age, 59.5 [10.8] years) and 254 (33.1%) with CESC (mean [SD] age, 48.7 [14.1] years). Human papillomavirus positivity was associated with a statistically significant improvement in overall survival for patients with OPSCC (adjusted hazard ratio [aHR], 0.06; 95% CI, 0.02-0.17; P < .001) but not for those with non-OP HNSCC (aHR, 0.64; 95% CI, 0.31-1.27; P = .20) or CESC (aHR, 0.50; 95% CI, 0.15-1.67; P = .30). The HPV-positive OPSCCs had increased tumor immune infiltration and immunomodulatory receptor expression compared with HPV-negative OPSCCs. Compared with HPV-positive non-OP HNSCCs, HPV-positive OPSCCs showed greater expression of immune-related metrics including B cells, T cells, CD8+ T cells, T-cell receptor diversity, B-cell receptor diversity, and cytolytic activity scores, independent of tumor variant burden. The immune-related metrics were similar when comparing HPV-positive non-OP HNSCCs and HPV-positive CESCs with their HPV-negative counterparts. The 2-year overall survival rate was significantly higher for patients with HPV-positive OPSCC compared with patients with HPV-negative OPSCC (92.0% [95% CI, 84.8%-99.9%] vs 45.8% [95% CI, 28.3%-74.1%]; HR, 0.10 [95% CI, 0.03-0.30]; P = .009). In this cohort study, tumor site was associated with the immune landscape and survival among patients with HPV-related tumors despite presumed similar biologic characteristics. These tumor site-related findings provide insight on possible outcomes of HPV positivity for tumors in oropharyngeal and nonoropharyngeal sites and a rationale for the stratification of HPV-associated tumors by site and the subsequent development of strategies targeting immune exclusion in HPV-positive nonoropharyngeal cancer.

Immunomodulatory receptor VSIG4 is released during spontaneous bacterial peritonitis and predicts short-term mortality

Background & AimsV-set Ig-domain-containing 4 (VSIG4) is an immunomodulatory macrophage complement receptor modulating innate and adaptive immunity and affecting the resolution of bacterial infections. Given its expression on peritoneal macrophages (PMs), we hypothesised a prognostic role of peritoneal VSIG4 concentrations in patients with spontaneous bacterial peritonitis (SBP).MethodsWe isolated PMs from patients with cirrhosis and analysed VSIG4 expression and release by flow cytometry, quantitative real-time PCR, ELISA, and confocal microscopy. We measured soluble VSIG4 concentrations in ascites from 120 patients with SBP and 40 patients without SBP and investigated the association of soluble VSIG4 in ascites with 90-day survival after SBP using Kaplan–Meier statistics, Cox regression, and competing-risks regression analysis.ResultsVSIG4 expression was high on resting, large PMs, which co-expressed CD206, CD163, and tyrosine-protein kinase Mer (MERTK). VSIG4 gene expression in PMs decreased in patients with SBP and normalised after resolution. During SBP, VSIG4hi PMs were depleted (25% vs. 57%; p <0.001) and soluble VSIG4 in ascites were higher in patients with SBP than in patients without (0.73 vs. 0.35 μg/ml; p <0.0001). PM activation by Toll-like receptor (TLR) agonists or infection with live bacteria in vitro resulted in a loss of surface VSIG4 and the release of soluble VSIG4. Mechanistically, shedding of VSIG4 from PMs was protease-dependent and susceptible to microtubule transport inhibition. Soluble VSIG4 in ascites exceeded serum concentrations and correlated with serum creatinine, model for end-stage liver disease score and C-reactive protein during SBP. Concentrations of 1.0206 μg/ml or higher indicated increased 90-day mortality (hazard ratio 1.70; 95% CI 1.01–2.86; p = 0.046).ConclusionsVSIG4 is released from activated PMs into ascites during SBP. Higher peritoneal VSIG4 levels indicate patients with organ failure and poor prognosis.Lay summaryPatients with liver cirrhosis who develop ascites have an increased risk of infection and mortality. Our study shows that in patients with infected ascites, the complement receptor VSIG4 is released by resident macrophages into the abdominal fluid where it can be measured. Patients with elevated levels of this protein in ascites are at high risk of dying within 90 days.

SARS-CoV-2 Exposed Mesenchymal Stromal Cell from Congenital Pulmonary Airway Malformations: Transcriptomic Analysis and the Expression of Immunomodulatory Genes.

The inflammatory response plays a central role in the complications of congenital pulmonary airway malformations (CPAM) and severe coronavirus disease 2019 (COVID-19). The aim of this study was to evaluate the transcriptional changes induced by SARS-CoV-2 exposure in pediatric MSCs derived from pediatric lung (MSCs-lung) and CPAM tissues (MSCs-CPAM) in order to elucidate potential pathways involved in SARS-CoV-2 infection in a condition of exacerbated inflammatory response. MSCs-lung and MSCs-CPAM do not express angiotensin-converting enzyme 2 (ACE2) and transmembrane serine protease 2 (TRMPSS2). SARS-CoV-2 appears to be unable to replicate in MSCs-CPAM and MSCs-lung. MSCs-lung and MSCs-CPAM maintained the expression of stemness markers MSCs-lung show an inflammatory response (IL6, IL1B, CXCL8, and CXCL10), and the activation of Notch3 non-canonical pathway; this route appears silent in MSCs-CPAM, and cytokine genes expression is reduced. Decreased value of p21 in MSCs-lung suggested no cell cycle block, and cells did not undergo apoptosis. MSCs-lung appears to increase genes associated with immunomodulatory function but could contribute to inflammation, while MSCs-CPAM keeps stable or reduce the immunomodulatory receptors expression, but they also reduce their cytokines expression. These data indicated that, independently from their perilesional or cystic origin, the MSCs populations already present in a patient affected with CPAM are not permissive for SARS-CoV-2 entry, and they will not spread the disease in case of infection. Moreover, these MSCs will not undergo apoptosis when they come in contact with SARS-CoV-2; on the contrary, they maintain their staminality profile.

Increasing phagocytosis of microglia by targeting CD33 with liposomes displaying glycan ligands

CD33 is an immunomodulatory receptor expressed by microglia and genetically linked to Alzheimer's disease (AD) susceptibility. While antibodies targeting CD33 have entered clinical trials to treat neurodegeneration, it is unknown whether the glycan-binding properties of CD33 can be exploited to modulate microglia. Here, we use liposomes that multivalently display glycan ligands of CD33 (CD33L liposomes) to engage CD33. We find that CD33L liposomes increase phagocytosis of cultured monocytic cells and microglia in a CD33-dependent manner. Enhanced phagocytosis strongly correlates with loss of CD33 from the cell surface and internalization of liposomes. Increased phagocytosis by treatment with CD33L liposomes is dependent on a key intracellular signaling motif on CD33 as well as the glycan-binding ability of CD33. These effects are specific to trans engagement of CD33 by CD33L liposomes, as cis engagement through insertion of lipid-linked CD33L into cells produces the opposite effect on phagocytosis. Moreover, intracerebroventricular injection of CD33L liposomes into transgenic mice expressing human CD33 in the microglial cell lineage enhances phagocytosis of microglia in a CD33-dependent manner. These results demonstrate that multivalent engagement of CD33 with glycan ligands can modulate microglial cell function.

Installation of high-affinity Siglec-1 ligand on tumor surface for macrophage-engaged tumor suppression

Siglecs that binds cell surface sialoglycans are a family of immunomodulatory receptors, of which, Siglec-7 expressed on natural killer (NK) cells promotes tumor immunoevation while the role of Siglec-1 expressed on macrophages on tumor development remains largely unexplored. Herein, we selectively introduced high affinity sialoside ligands of Siglec-1 and Siglec-7 to tumor cell surface via in vivo Strain-promoted Azide-Alkyne cyclization of TCCSiaα2,3-Lactose or FITCSiaα2,6-Lactose with 9-azido sialic acid (AzSia) metabolically installed on tumor cell surface. We found that TCCSiaα2,3-Lactose conjugated on tumor surface moderately inhibited tumor growth while FITCSiaα2,6-Lactose promote tumor growth. These results suggest high-affinity ligand of Siglec-1 dispalyed on tumors surface provide a new perspective for tumor immunotherapy.

COVID-19 and immunothrombosis: emerging understanding and clinical management.

The COVID-19 pandemic has been the most significant health crisis in recent global history. Early studies from Wuhan highlighted COVID-19-associated coagulopathy and a significant association with mortality was soon recognised. As research continues across the world, more evidence is emerging of the cross-talk between the innate immune system, coagulation activation and inflammation. Immunothrombosis has been demonstrated to play a key role in the pathophysiology of severe COVID-19, with extracellular histones and neutrophil extracellular traps detected in the plasma and cardiopulmonary tissues of critically ill patients. Targeting the components of immunothrombosis is becoming an important factor in the treatment of patients with COVID-19 infection. Recent studies report outcomes of intermediate and therapeutic anticoagulation in hospitalised patients with varying severities of COVID-19 disease, including optimal dosing and associated bleeding risks. Immunomodulatory therapies, including corticosteroids and IL-6 receptor antagonists, have been demonstrated to significantly reduce mortality in COVID-19 patients. As the pandemic continues, more studies are required to understand the driving factors and upstream mechanisms for coagulopathy and immunothrombosis in COVID-19, and thus potentially develop more targeted therapies for SARS-CoV-2 infection, both in the acute phase and in those who develop longer-term symptom burden.

Itolizumab-induced antigenic modulation of CD6 inhibits T cell activity

Abstract CD6 is an immunomodulatory receptor on T cells that promotes immune synapse formation, T-cell activation, and cell migration into tissues by binding activated leukocyte cell adhesion molecule (ALCAM). Excessive activation through the CD6-ALCAM pathway has been implicated in the pathogenesis of multiple autoimmune and inflammatory diseases. Hence, the ability to modulate the level of activation is beneficial to disease resolution. Itolizumab is a humanized anti-CD6 monoclonal antibody that is specific for the membrane distal domain 1 of CD6. Previously, itolizumab was believed to sterically hinder the CD6-ALCAM interaction, thereby blocking T-cell co-stimulation. Here we describe antigenic modulation as an additional mechanism whereby binding of itolizumab to CD6 induces proteolytic cleavage of the extracellular portion of CD6. Upon treatment with itolizumab, surface levels of CD6 decreased in a dose- and time-dependent manner, as monitored by flow cytometry using a noncompetitive anti-CD6 monoclonal antibody. This loss was inhibited in the presence of protease inhibitors and the decrease in surface levels of CD6 was accompanied by an increase in levels of soluble CD6 in the supernatant. Furthermore, we assessed the effect of surface levels of CD6 on the response of cells to T cell stimulation in the presence of ALCAM. CD6low cells showed reduced T-cell activity compared to CD6highcells as measured by cell surface activation makers, including CD25, CD69 and PD-1, and cytokine production. These findings demonstrate that CD6 is an important regulator of T-cell activity and that modulating surface levels of CD6 is an effective method for fine-tuning the activity of T-cells.

Gut-inhabiting Clostridia build human GPCR ligands by conjugating neurotransmitters with diet- and human-derived fatty acids.

Human physiology is regulated by endogenous signalling compounds, including fatty acid amides (FAAs), chemical mimics of which are made by bacteria. The molecules produced by human-associated microbes are difficult to identify because they may only be made in a local niche or they require a substrate sourced from the host, diet or other microbes. We identified a set of uncharacterized gene clusters in metagenomics data from the human gut microbiome. These clusters were discovered to make FAAs by fusing exogenous fatty acids with amines. Using an in vitro assay, we tested their ability to incorporate 25 fatty acids and 53 amines known to be present in the human gut, from which the production of six FAAs was deduced (oleoyl dopamine, oleoyl tyramine, lauroyl tryptamine, oleoyl aminovaleric acid, α-linolenoyl phenylethylamine and caproyl tryptamine). These molecules were screened against panels of human G-protein-coupled receptors to deduce their putative human targets. Lauroyl tryptamine is found to be an antagonist to the immunomodulatory receptor EBI2 against its native oxysterol ligand (0.98 μM half-maximal inhibitory concentration), is produced in culture by Eubacterium rectale and is present in human faecal samples. FAAs produced by Clostridia may serve as a mechanism to modulate their host by mimicking human signalling molecules.