Monocyte Activation Research Articles

Abstract 4603: Single-cell and spatial dissection of the effect of combined PD-L1 and TGFb blockade by bintrafusp alfa from the ICING window-of-opportunity trial in resectable locally advanced HNSCC patients

Abstract Despite high tumor mutational burden, immune checkpoint blockade has shown limited efficacy in head and neck squamous cell carcinoma (HNSCC), highlighting the need for additional therapeutic targets. TGFb signaling has been associated with an immunosuppressive tumor microenvironment as well as a lack of response to anti-PD(L)1 therapy, which led to the development of combined therapeutic approaches. ICING is a prospective (NCT04428047) open label, multicenter, phase II, window-of-opportunity preoperative, single-agent trial. The primary objective was to evaluate the efficacy and biological activity of pre-operative combined PD-L1 and TGFb blockade by bintrafusp alfa in patients with untreated resectable stage III/IV locally advanced HNSCC and its effect on the tumor microenvironment (TME). Tumor samples were harvested at baseline prior to immunotherapy and at surgery after two doses (1200mg; D1 and D15) for pre- and post-treatment comparison. Treatment efficacy was assessed using the pathological response (PathR) with a 10% threshold for response as primary endpoint. Changes in the TME were determined by single-cell RNA sequencing (scRNAseq) and multiplexed imaging. Seven patients were included and six received the full treatment scheme (5 oral cavity and 2 oropharyngeal, all HPV-negative; median age = 61y, range 34y-74y). Four patients had a PathR exceeding 10%, including one with a major PathR above 50%. The TME pre-treatment of this major responder did not differ from the other samples, but this sample was set apart by the presence of proliferative, p16+, HPV-negative tumor cells with mildly higher genomic alterations whilst still classified as low tumor mutational burden. Regardless of treatment response, we report several changes in post-treatment samples: (i) the remodeling of the stromal architecture concomitant with a phenotypic shift in cancer-associated fibroblasts (CAF) with a reduction in activated LRRC15+ CAF and an increase in CD10+IL24+ CAF; (ii) a reduction of TGFb-induced genes in both stromal and cancer cells; (iii) a reduction in both conventional and regulatory CD4+ T cells; (iv) an increase in CD8+ T cell infiltration in previously excluded tumors; (v) an interferon gamma-mediated activation of monocytes, macrophages and dendritic cells expressing CXCL9 and CXCL10. Collectively, our study deciphers the effects of bintrafusp alfa both molecularly and spatially at unprecedented granularity, which is of major importance for the many combined PD(L)1 and TGFb blockade therapeutic approaches currently under clinical development. Citation Format: Caroline Hoffmann, Jan-Timon Werle, Jocelyn Gal, Philemon Sirven, Jerzy Klijanienko, Jeremy Mesple, Benjamin Demaille, Wail Zeitouni, Olivier Choussy, Gregoire Marret, Nathalie Badois, Antoine Dubray-Vautrin, Gilles Dolivet, Lionnel Geoffrois, Maud Kamal, Ivan Bieche, Laure Monard, Clotilde Simon, Christophe Le Tourneau, Helene Salmon. Single-cell and spatial dissection of the effect of combined PD-L1 and TGFb blockade by bintrafusp alfa from the ICING window-of-opportunity trial in resectable locally advanced HNSCC patients [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 4603.

InPACT: a computational method for accurate characterization of intronic polyadenylation from RNA sequencing data

Alternative polyadenylation can occur in introns, termed intronic polyadenylation (IPA), has been implicated in diverse biological processes and diseases, as it can produce noncoding transcripts or transcripts with truncated coding regions. However, a reliable method is required to accurately characterize IPA. Here, we propose a computational method called InPACT, which allows for the precise characterization of IPA from conventional RNA-seq data. InPACT successfully identifies numerous previously unannotated IPA transcripts in human cells, many of which are translated, as evidenced by ribosome profiling data. We have demonstrated that InPACT outperforms other methods in terms of IPA identification and quantification. Moreover, InPACT applied to monocyte activation reveals temporally coordinated IPA events. Further application on single-cell RNA-seq data of human fetal bone marrow reveals the expression of several IPA isoforms in a context-specific manner. Therefore, InPACT represents a powerful tool for the accurate characterization of IPA from RNA-seq data.

Abstract 2696: Tumor organoid and immune cells co-cultures to study myeloid cells-targeting immunotherapy

Abstract Cancer immunotherapy is one of the main pillars of oncology treatment due to the clinical success of approaches that enhance anti-tumoral T cell responses. Nonetheless, many patients do not benefit from these approaches, highlighting the need to develop novel immunomodulatory strategies. Exploiting the anti-tumor capacity of innate immune cells is a promising approach that can overcome specific limitations of T cell-targeting therapies and complement existing immunotherapies. Still, promising therapeutic developments face hurdles in translating preclinical findings into treatment since conventional 2D cancer models hold low clinical predictive value. HUB developed an innovative alternative, building on the discovery that adult stem cells proliferate and organize into three-dimensional organotypic structures. Patient-specific organoids are generated from healthy and disease tissues and recapitulate complex characteristics of the original parental tissue, including molecular heterogeneity and morphological and functional traits. To assess the efficacy of therapies that engage innate immune cells, we developed an assay in which organoids derived from colorectal (CRC) or breast cancer patients are co-cultured with PBMC-derived macrophages or monocytes to evaluate the cytotoxic potential of exogenously activated myeloid cells. We tested the ability of macrophages to phagocyte human CRC organoid cells in response to anti-CD47 antibody. The pro-phagocytic function of anti-CD47 was detected by several methods (i.e., flow cytometry, imaging), indicating the platform's suitability to evaluate ADCP-modulating compounds. Moreover, to assess whether our PBMC-organoids co-culture platform is suited to detect monocyte-mediated effects, Lipopolysaccharide (LPS) plus IFN-γ were used to activate monocytes in the co-culture assays. We observed an increase in cytokines secretion (i.e., CXCL10), immune cell activation and organoid killing, indicating that our assay allows the detection of monocyte activation through different types of readouts. In summary, our organoid-immune cell co-culture platform allows to study the response of tumor organoids to innate immune cells, holding significant value for the preclinical development of immunotherapies based on innate immune cells. Citation Format: Lorenzo Spagnuolo, Francisco Morales-Rodriguez, Alessandra Merenda, Cesar Oyarce, Farzin Pourfarzad, Robert G. Vries, Sylvia F. Boj. Tumor organoid and immune cells co-cultures to study myeloid cells-targeting immunotherapy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 2696.

The rheology of interactions between leukocytes, platelets and the vessel wall in thrombo-inflammation.

Leukocytes and platelets must adhere to the wall of blood vessels to carry out their protective functions in inflammation and haemostasis. Recruitment is critically dependent on rheological variables (wall shear rate and stress, red cell aggregation and haematocrit) which affect delivery to the vessel wall as well as velocities and forces experienced there. Leukocyte recruitment is efficient only up to wall shear rates of about 300s-1 and usually restricted to low-shear post-capillary venules in inflammation. Being smaller, platelets experience lower velocities and shear forces adjacent to the wall and can adhere at much higher shear rates for haemostasis in arteries. In addition, we found quite different effects of variations in haematocrit or red cell aggregation on attachment of neutrophils or platelets, which also assist their separate recruitment in venules or arteries. However, it has become increasingly evident that inflammatory and thrombotic responses may occur together, with platelets promoting the adhesion and activation of neutrophils and monocytes. Indeed, it is 30 years since we demonstrated that platelets could cause neutrophils to aggregate in suspension and, when attached to a surface, could support selectin-mediated rolling of all leukocytes. Thrombin-activated platelets could further induce neutrophil activation and immobilisation. In some conditions, platelets could bind to intact endothelial monolayers and capture neutrophils or monocytes. Subsequently, we found that extracellular vesicles released by activated platelets (PEV) fulfilled similar functions when deposited on surfaces or bound to endothelial cells. In murine models, platelets or PEV could act as bridges for monocytes in inflamed vessels. Thus, leukocytes and platelets are rheologically adapted for their separate functions, while novel thrombo-inflammatory pathways using platelets or PEV may underlie pathogenic leukocyte recruitment.

Changes in the innate immune response to SARS-CoV-2 with advancing age in humans

BackgroundAdvancing age is a major risk factor for respiratory viral infections. The infections are often prolonged and difficult to resolve resulting hospitalizations and mortality. The recent COVID-19 pandemic has highlighted this as elderly subjects have emerged as vulnerable populations that display increased susceptibility and severity to SARS-CoV-2. There is an urgent need to identify the probable mechanisms underlying this to protect against future outbreaks of such nature. Innate immunity is the first line of defense against viruses and its decline impacts downstream immune responses. This is because dendritic cells (DCs) and macrophages are key cellular elements of the innate immune system that can sense and respond to viruses by producing inflammatory mediators and priming CD4 and CD8 T-cell responses.ResultsWe investigated the changes in innate immune responses to SARS-CoV-2 as a function of age. Our results using human PBMCs from aged, middle-aged, and young subjects indicate that the activation of DCs and monocytes in response to SARS-CoV-2 is compromised with age. The impairment is most apparent in pDCs where both aged and middle-aged display reduced responses. The secretion of IL-29 that confers protection against respiratory viruses is also decreased in both aged and middle-aged subjects. In contrast, inflammatory mediators associated with severe COVID-19 including CXCL-8, TREM-1 are increased with age. This is also apparent in the gene expression data where pathways related host defense display an age dependent decrease with a concomitant increase in inflammatory pathways. Not only are the inflammatory pathways and mediators increased after stimulation with SARS-CoV-2 but also at homeostasis. In keeping with reduced DC activation, the induction of cytotoxic CD8 T cells is also impaired in aged subjects. However, the CD8 T cells from aged subjects display increased baseline activation in accordance with the enhanced baseline inflammation.ConclusionsOur results demonstrate a decline in protective anti-viral immune responses and increase in damaging inflammatory responses with age indicating that dysregulated innate immune responses play a significant role in the increased susceptibility of aged subjects to COVID-19. Furthermore, the dysregulation in immune responses develops early on as middle-aged demonstrate several of these changes.Graphical abstract

The association of TNF-alpha secretion and mtDNA copy number in CD14+ monocytes of patients with obesity and CHD.

Mitochondrial dysfunction may be one of the causes of inflammatory activation of monocytes and macrophages, which leads to excessive secretion of inflammatory mediators and the development of chronic inflammation. The study was aimed to evaluate the secretion of inflammatory cytokine tumor necrosis factor-α (TNF-α) in the primary culture of monocytes, and to analyze its relationship with the number of mitochondrial DNA (mtDNA) copies in the blood of patients with coronary heart disease (CHD) and obesity. 108 patients with obesity and concomitant CHD and a control group of 25 participants were included in the study. CD14+ monocytes were isolated by a standard method in a ficoll-urographin gradient, followed by separation using magnetic particles. The number of mtDNA copies was estimated using qPCR. It was demonstrated that the number of mtDNA copies was significantly increased in groups of patients with CHD and obesity + CHD in comparison with control group. mtDNA copy number positively correlated with basal and LPS-stimulated TNF-α secretion, the most significant correlation was found in the group of patients with CHD and obesity. Thus, the change in mtDNA copy number in CD14+ monocytes which indicates the presence of mitochondrial dysfunction, confirm the direct involvement of mitochondria in the violation of the inflammatory response of monocytes revealed in this study as an increased secretion of inflammatory cytokine TNF-α.

Effect of moringa extract on parasitemia, monocyte activation and organomegaly among Mus musculus infected by Plasmodium berghei ANKA.

In Indonesia, malaria remains a problem, with 94,610 active cases in 2021 and its current therapy includes chloroquine and artemisinin; however, resistance has been commonly reported. To overcome this problem, studies about potential medicinal plants that can be used as antimalaria, such as moringa (Moringa oleifera) started to receive more attention. The aim of this study was to investigate the effects of moringa in parasitemia, monocyte activation, and organomegaly on animal model malaria. This experimental study used male Mus musculus, infected by Plasmodium berghei ANKA, as an animal malaria model. The extract was made by maceration of dry moringa leaves, which were then divided into three concentrations: 25%, 50%, and 75%. Dihydroartemisinin-piperazine was used as a positive control treatment, and distilled water as a negative control treatment. The animals were observed for six days to assess the parasitemia count and the number of monocyte activation. On day 7, the animals were terminated, and the liver, spleen, and kidney were weighed. The results showed that the effective concentrations in reducing parasitemia and inducing monocyte activation were 50% and 25% of moringa leaf extract, respectively. The smallest liver and spleen enlargement was observed among animals within the group treated with a 50% concentration of M. oleifera extract. In contrast, the smallest kidney enlargement was observed in the group treated with 25% of M. oleifera extract. Further analysis is recommended to isolate compounds with antimalarial properties in moringa leaves.

Investigating the causal relationship between immune cell and Alzheimer's disease: a mendelian randomization analysis.

Complex interactions between the immune system and the brain may affect neural development, survival, and function, with etiological and therapeutic implications for neurodegenerative diseases. However, previous studies investigating the association between immune inflammation and Alzheimer's disease (AD) have yielded inconsistent results. We applied Mendelian randomization (MR) to examine the causal relationship between immune cell traits and AD risk using genetic variants as instrumental variables. MR is an epidemiological study design based on genetic information that reduces the effects of confounding and reverse causation. We analyzed the causal associations between 731 immune cell traits and AD risk based on publicly available genetic data. We observed that 5 immune cell traits conferred protection against AD, while 7 immune cell traits increased the risk of AD. These immune cell traits mainly involved T cell regulation, monocyte activation and B cell differentiation. Our findings suggest that immune regulation may influence the development of AD and provide new insights into potential targets for AD prevention and treatment. We also conducted various sensitivity analyses to test the validity and robustness of our results, which revealed no evidence of pleiotropy or heterogeneity. Our research shows that immune regulation is important for AD and provides new information on potential targets for AD prevention and treatment. However, this study has limitations, including the possibility of reverse causality, lack of validation in independent cohorts, and potential confounding by population stratification. Further research is needed to validate and amplify these results and to elucidate the potential mechanisms of the immune cell-AD association.

Unleashed monocytic engagement in Sézary syndrome during the combination of anti-CCR4 antibody with type I interferon

AbstractSézary syndrome (SS) is an aggressive leukemic expansion of skin-derived malignant CD4+ T cells. Drug monotherapy often results in disease relapse because of the heterogenous nature of malignant CD4+ T cells, but how therapies can be optimally combined remains unclear because of limitations in understanding the disease pathogenesis. We identified immunologic transitions that interlink mycosis fungoides with SS using single-cell transcriptome analysis in parallel with high-throughput T-cell receptor sequencing. Nascent peripheral CD4+ T cells acquired a distinct profile of transcription factors and trafficking receptors that gave rise to antigenically mature Sézary cells. The emergence of malignant CD4+ T cells coincided with the accumulation of dysfunctional monocytes with impaired fragment crystallizable γ-dependent phagocytosis, decreased responsiveness to cytokine stimulation, and limited repertoire of intercellular interactions with Sézary cells. Type I interferon supplementation when combined with a monoclonal antibody targeting the chemokine receptor type 4 (CCR4), unleashed monocyte induced phagocytosis and eradication of Sézary cells in vitro. In turn, coadministration of interferon-α with the US Food and Drug Administration–approved anti-CCR4 antibody, mogamulizumab, in patients with SS induced marked depletion of peripheral malignant CD4+ T cells. Importantly, residual CD4+ T cells after Sézary cell ablation lacked any immunologic shifts. These findings collectively unveil an auxiliary role for augmenting monocytic activity during mogamulizumab therapy in the treatment of SS and underscore the importance of targeted combination therapy in this disease.

Biorefining of legume and grass biomasses: Technological properties and bioactivities of the green juice

Five legume species (fodder galega, green pea, faba bean, red clover, and white clover) and one grass (timothy) grown under field conditions were investigated as potential future foods. Technological characteristics, such as emulsifying and foaming properties and nitrogen solubility indices, were determined from the green juices pressed from the whole plants. Secondly, the juices were evaluated for their antioxidative, antibacterial and anti-inflammatory properties. Faba bean green juice showed the highest emulsion stability and capacity, 66.0 ± 3.3 % and 18.0 ± 2.7 g/mg respectively, and second highest emulsion activity (58.4 ± 0.92 %). Considering the foaming properties, the highest activity was shown by white clover (433 ± 0.0 %) and green pea juices (411 ± 19.2 %). At the same time, the foam stability was remarkable for green pea juice (1078 ± 181.9 min) when compared to the other juices studied. The juices showed nitrogen solubility indices of about 50 % at pH 8, which were rather similar to those shown for the seeds of the same species in the literature. The antioxidant activities correlated with the total phenolic content. The highest antioxidant activity was shown by faba bean green juice both in the oxygen radical absorbance capacity (ORAC) and the ferric reducing antioxidant power (FRAP) method. In addition, a weak positive correlation was observed between the total phenolic content and the antibacterial properties using Escherichia coli and Staphylococcus aureus strains, although mainly in the case of the latter strain, high inhibition readings were observed for all other plants than white clover. All juices showed some anti-inflammatory activity on human monocyte activation: the faba bean and red clover were the most efficient materials (IC50 concentrations 49 ± 41 and 206 ± 68 mg/L, respectively).- These results suggest that the green juices tested may provide novel health-promoting food and feed ingredients in the future.

Immune profiles of pre-frail people living with HIV-1: a prospective longitudinal study

BackgroundPeople living with HIV (PLWH) are at risk of frailty, which is predictive for death. As an overactivity of the immune system is thought to fuel frailty, we characterized the immune activation profiles linked to frailty.MethodsWe quantified twenty-seven activation markers in forty-six virological responders (four females and forty-two males; median age, 74 years; median duration of infection, 24 years; median duration of undetectability, 13 years), whose frailty was determined according to the Fried criteria. T cell and NK cell activation was evaluated by flow cytometry, using a panel of cell surface markers. Soluble markers of inflammation, and monocyte activation and endothelial activation were measured by ELISA. The participants’ immune activation was profiled by an unsupervised double hierarchical clustering analysis. We used ANOVA p-values to rank immunomarkers most related to Fried score. A Linear Discriminant Analysis (LDA) was performed to link immune activation markers to frailty.Results41% of the participants were pre-frail, including 24% with a Fried score of 1, and 17% with a Fried score of 2. ANOVA identified the 14 markers of T cell, monocyte, NK cell, endothelial activation, and inflammation the most linked to Fried 3 classes. The LDA performed with these 14 markers was capable of discriminating volunteers according to their Fried score. Two out of the 5 immune activation profiles revealed by the hierarchical clustering were linked to and predictive of pre-frailty. These two profiles were characterized by a low percentage of CD4 T cells and a high percentage of CD8 T cells, activated CD4 T cells, CD8 T cells, and NK cells, and inflammation.ConclusionsWe identified a particular immune activation profile associated with pre-frailty in PLWH. Profiling participants at risk of developing frailty might help to tailor the screening and prevention of medical complications fueled by loss of robustness. Further studies will indicate whether this frailty signature is specific or not of HIV infection, and whether it also precedes frailty in the general population.

Platelet and Monocyte Microvesicles as Potential Biomarkers of COVID-19 Severity: A Cross-Sectional Analysis.

Coronavirus disease (COVID-19) induces inflammation, coagulopathy following platelet and monocyte activation, and fibrinolysis, resulting in elevated D-dimer levels. Activated platelets and monocytes produce microvesicles (MVs). We analyzed the differences in platelet and monocyte MV counts in mild, moderate, and severe COVID-19, as well as their correlation with D-dimer levels. In this cross-sectional study, blood specimens were collected from 90 COVID-19 patients and analyzed for D-dimers using SYSMEX CS-2500. Platelet MVs (PMVs; PMVCD42b+ and PMVCD41a+), monocyte MVs (MMVs; MMVCD14+), and phosphatidylserine-binding annexin V (PS, AnnV+) were analyzed using a BD FACSCalibur instrument. PMV and MMV counts were significantly increased in COVID-19 patients. AnnV+ PMVCD42b+ and AnnV+ PMVCD41a+ cell counts were higher in patients with severe COVID-19 than in those with moderate clinical symptoms. The median (range) of AnnV+ PMVCD42b+ (MV/μL) in mild, moderate, and severe COVID-19 was 1,118.3 (328.1-1,910.5), 937.4 (311.4-2,909.5), and 1,298.8 (458.2-9,703.5), respectively (P =0.009). The median (range) for AnnV+ PMVCD41a+ (MV/μL) in mild, moderate, and severe disease was 885.5 (346.3-1,682.7), 663.5 (233.8-2,081.5), and 1,146.3 (333.3-10,296.6), respectively (P =0.007). D-dimer levels (ng/mL) weak correlated with AnnV+ PMVCD41a+ (P =0.047, r=0.258). PMV PMVCD42b+ and PMVCD41a+ counts were significantly increased in patients with severe clinical symptoms, and PMVCD41a+ counts correlated with D-dimer levels. Therefore, MV counts can be used as a potential biomarker of COVID-19 severity.

Characterization of differences in immune responses during bolus and continuous infusion endotoxin challenges using mathematical modelling.

Endotoxin administration is commonly used to study the inflammatory response, and though traditionally given as a bolus injection, it can be administered as a continuous infusion over multiple hours. Several studies hypothesize that the latter better represents the prolonged and pronounced inflammation observed in conditions like sepsis. Yet very few experimental studies have administered endotoxin using both strategies, leaving significant gaps in determining the underlying mechanisms responsible for their differing immune responses. We used mathematical modelling to analyse cytokine data from two studies administering a 2ngkg-1 dose of endotoxin, one as a bolus and the other as a continuous infusion over 4 h. Using our model, we simulated the dynamics of mean and subject-specific cytokine responses as well as the response to long-term endotoxin administration. Cytokine measurements revealed that the bolus injection led to significantly higher peaks for interleukin (IL)-8, while IL-10 reaches higher peaks during continuous administration. Moreover, the peak timing of all measured cytokines occurred later with continuous infusion. We identified three model parameters that significantly differed between the two administration methods. Monocyte activation of IL-10 was greater during the continuous infusion, while tumour necrosis factor and IL-8 recovery rates were faster for the bolus injection. This suggests that a continuous infusion elicits a stronger, longer-lasting systemic reaction through increased stimulation of monocyte anti-inflammatory mediator production and decreased recovery of pro-inflammatory catalysts. Furthermore, the continuous infusion model exhibited prolonged inflammation with recurrent peaks resolving within 2days during long-term (20-32h) endotoxin administration.

NFκB and NLRP3/NLRC4 inflammasomes regulate differentiation, activation and functional properties of monocytes in response to distinct SARS-CoV-2 proteins

Increased recruitment of transitional and non-classical monocytes in the lung during SARS-CoV-2 infection is associated with COVID-19 severity. However, whether specific innate sensors mediate the activation or differentiation of monocytes in response to different SARS-CoV-2 proteins remain poorly characterized. Here, we show that SARS-CoV-2 Spike 1 but not nucleoprotein induce differentiation of monocytes into transitional or non-classical subsets from both peripheral blood and COVID-19 bronchoalveolar lavage samples in a NFκB-dependent manner, but this process does not require inflammasome activation. However, NLRP3 and NLRC4 differentially regulated CD86 expression in monocytes in response to Spike 1 and Nucleoprotein, respectively. Moreover, monocytes exposed to Spike 1 induce significantly higher proportions of Th1 and Th17 CD4 + T cells. In contrast, monocytes exposed to Nucleoprotein reduce the degranulation of CD8 + T cells from severe COVID-19 patients. Our study provides insights in the differential impact of innate sensors in regulating monocytes in response to different SARS-CoV-2 proteins, which might be useful to better understand COVID-19 immunopathology and identify therapeutic targets.

Discovery of a Highly Potent Oxysterol Receptor GPR183 Antagonist Bearing the Benzo[d]thiazole Structural Motif for the Treatment of Inflammatory Bowel Disease (IBD).

Accumulating evidence has demonstrated a critical pathological role of oxysterol receptor GPR183 in various inflammatory and autoimmune diseases, including inflammatory bowel disease (IBD). However, the currently reported GPR183 antagonists are very limited and not qualified for in vivo studies due to their inferior druglike properties. Herein, we conducted a structural elaboration focusing on improving its PK and safety profile based on a reference antagonist NIBR189. Of note, compound 33, bearing an aminobenzothiazole motif, exhibited reduced hERG inhibition, improved PK properties, and robust antagonistic activity (IC50 = 0.82 nM) with high selectivity against GPR183. Moreover, compound 33 displayed strong in vitro antimigration and anti-inflammatory activity in monocytes. Oral administration of compound 33 effectively improved the pathological symptoms of DSS-induced experimental colitis. All of these findings demonstrate that compound 33 is a novel and promising GPR183 antagonist suitable for further investigation to treat IBD.

Inhibition of Toll-like Receptor 4 Using Small Molecule, TAK-242, Protects Islets from Innate Immune Responses.

Islet transplantation is a therapeutic option to replace β-cell mass lost during type 1 or type 3c diabetes. Innate immune responses, particularly the instant blood-mediated inflammatory reaction and activation of monocytes, play a major role in the loss of transplanted islet tissue. In this study, we aimed to investigate the inhibition of toll-like receptor 4 (TLR4) on innate inflammatory responses. We first demonstrate a significant loss of graft function shortly after transplant through the assessment of miR-375 and miR-200c in plasma as biomarkers. Using in vitro models, we investigate how targeting TLR4 mitigates islet damage and immune cell activation during the peritransplant period. The results of this study support the application of TAK-242 as a therapeutic agent to reduce inflammatory and innate immune responses to islets immediately following transplantation into the hepatic portal vein. Therefore, TLR4 may serve as a target to improve islet transplant outcomes in the future.

Reduced Monocyte and Neutrophil Infiltration and Activation by P-Selectin/CD62P Inhibition Enhances Thrombus Resolution in Mice.

Venous thromboembolism is a major health problem. After thrombus formation, its resolution is essential to re-establish blood flow, which is crucially mediated by infiltrating neutrophils and monocytes in concert with activated platelets and endothelial cells. Thus, we aimed to modulate leukocyte function during thrombus resolution post-thrombus formation by blocking P-selectin/CD62P-mediated cell interactions. Thrombosis was induced by inferior vena cava stenosis through ligation in mice. After 1 day, a P-selectin-blocking antibody or isotype control was administered and thrombus composition and resolution were analyzed. Localizing neutrophils and macrophages in thrombotic lesions of wild-type mice revealed that these cells enter the thrombus and vessel wall from the caudal end. Neutrophils were predominantly present 1 day and monocytes/macrophages 3 days after vessel ligation. Blocking P-selectin reduced circulating platelet-neutrophil and platelet-Ly6Chigh monocyte aggregates near the thrombus, and diminished neutrophils and Ly6Chigh macrophages in the cranial thrombus part compared with isotype-treated controls. Depletion of neutrophils 1 day after thrombus initiation did not phenocopy P-selectin inhibition but led to larger thrombi compared with untreated controls. In vitro, P-selectin enhanced human leukocyte function as P-selectin-coated beads increased reactive oxygen species production by neutrophils and tissue factor expression of classical monocytes. Accordingly, P-selectin inhibition reduced oxidative burst in the thrombus and tissue factor expression in the adjacent vessel wall. Moreover, blocking P-selectin reduced thrombus density determined by scanning electron microscopy and increased urokinase-type plasminogen activator levels in the thrombus, which accelerated caudal fibrin degradation from day 3 to day 14. This accelerated thrombus resolution as thrombus volume declined more rapidly after blocking P-selectin. Inhibition of P-selectin-dependent activation of monocytes and neutrophils accelerates venous thrombosis resolution due to reduced infiltration and activation of innate immune cells at the site of thrombus formation, which prevents early thrombus stabilization and facilitates fibrinolysis.

Quantitative Multiplexed Analysis of Indoleamine 2,3-Dioxygenase (IDO) and Arginase-1 (ARG1) Expression and Myeloid Cell Infiltration in Colorectal Cancer

Indoleamine 2,3-dioxygenase (IDO) and arginase-1 (ARG1) are amino acid–metabolizing enzymes, frequently highly expressed in cancer. Their expression may deplete essential amino acids, lead to immunosuppression, and promote cancer growth. Still, their expression patterns, prognostic significance, and spatial localization in the colorectal cancer microenvironment are incompletely understood. Using a custom 10-plex immunohistochemistry assay and supervised machine learning–based digital image analysis, we characterized IDO and ARG1 expression in monocytic cells, granulocytes, mast cells, and tumor cells in 833 colorectal cancer patients. We evaluated the prognostic value and spatial arrangement of IDO- and ARG1-expressing myeloid and tumor cells. IDO was mainly expressed not only by monocytic cells but also by some tumor cells, whereas ARG1 was predominantly expressed by granulocytes. Higher density of IDO+ monocytic cells was an independent prognostic factor for improved cancer-specific survival both in the tumor center (Ptrend = .0002; hazard ratio [HR] for the highest ordinal category Q4 [vs Q1], 0.51; 95% CI, 0.33-0.79) and the invasive margin (Ptrend = .0015). Higher density of granulocytes was associated with prolonged cancer-specific survival in univariable models, and higher FCGR3+ARG1+ neutrophil density in the tumor center also in multivariable analysis (Ptrend = .0020). Granulocytes were, on average, located closer to tumor cells than monocytic cells. Furthermore, IDO+ monocytic cells and ARG1− granulocytes were closer than IDO− monocytic cells and ARG1+ granulocytes, respectively. The mRNA expression of the IDO1 gene was assessed in myeloid and tumor cells using publicly available single-cell RNA sequencing data for 62 colorectal cancers. IDO1 was mainly expressed in monocytes and dendritic cells, and high IDO1 activity in monocytes was associated with enriched immunostimulatory pathways. Our findings provided in-depth information about the infiltration patterns and prognostic value of cells expressing IDO and/or ARG1 in the colorectal cancer microenvironment, highlighting the significance of host immune response in tumor progression.

Association of Lipoprotein(a) with peri-coronary inflammation in persons with and without HIV infection

Persons with human immunodeficiency virus (HIV) (PWH) have an increased risk of developing cardiovascular disease (CVD) compared to persons without HIV (PWoH). Lipoprotein(a) [Lp(a)] is a known atherosclerotic risk factor in PWoH, but there are no studies investigating Lp(a) and peri-coronary inflammation. To investigate whether Lp(a) is associated with peri-coronary inflammation as assessed by the fat attenuation index (FAI) and activated monocytes and T lymphocytes in PWH and PWoH. We measured plasma levels of Lp(a) at study entry in 58 PWH and 21 PWoH without CVD and who had FAI measurements. Associations of Lp(a) with FAI values of the right coronary artery (RCA) and left anterior descending artery were evaluated using multivariable regression models adjusted for potential confounders. Correlations between Lp(a) levels and systemic inflammatory markers and immune cell subsets were examined. Lp(a) was associated with greater peri-coronary inflammation among PWH compared to PWoH (β=1.73, P=0.019) in the RCA, in adjusted models. Significant correlations were observed with certain inflammatory markers (tumor necrosis factor receptor [TNFR]-I, b=0.295, P<0.001; TNFR-II, b=0.270, P=0.002; high-sensitivity C-reactive protein, b=0.195, P=0.028). Significant correlations were found between Lp(a) levels and several markers of monocyte activation: CD16 -CD163+ (b= -0.199, P=0.024), and CD16 -DR+ MFI (b= -0.179, P=0.042) and T cell subset CD38+CD4+ TEMRA (b= 0.177, P= 0.044). Lp(a) was associated with greater peri-coronary inflammation in the RCA in PWH compared to PWoH, as well as with select systemic inflammatory markers and specific subsets of immune cells in peripheral circulation.

Temperature impacts the bovine ex vivo immune response towards Mycoplasmopsis bovis

Although cattle are the mammalian species with most global biomass associated with a huge impact on our planet, their immune system remains poorly understood. Notably, the bovine immune system has peculiarities such as an overrepresentation of γδ T cells that requires particular attention, specifically in an infectious context. In line of 3R principles, we developed an ex vivo platform to dissect host–pathogen interactions. The experimental design was based on two independent complementary readouts: firstly, a novel 12–14 color multiparameter flow cytometry assay measuring maturation (modulation of cell surface marker expression) and activation (intracellular cytokine detection) of monocytes, conventional and plasmacytoid dendritic cells, natural killer cells, γδ T cells, B and T cells; secondly, a multiplex immunoassay monitoring bovine chemokine and cytokine secretion levels. The experiments were conducted on fresh primary bovine blood cells exposed to Mycoplasmopsis bovis (M. bovis), a major bovine respiratory pathogen. Besides reaffirming the tight cooperation of the different primary blood cells, we also identified novel key players such as strong IFN-γ secreting NK cells, whose role was so far largely overlooked. Additionally, we compared the host–pathogen interactions at different temperatures, including commonly used 37 °C, ruminant body temperature (38–38.5 °C) and fever (≥ 39.5 °C). Strikingly, working under ruminant physiological temperature influenced the capacity of most immune cell subsets to respond to M. bovis compared to 37 °C. Under fever-like temperature conditions the immune response was impaired compared to physiological temperature. Our experimental approach, phenotypically delineating the bovine immune system provided a thorough vision of the immune response towards M. bovis and the influence of temperature towards that immune response.