Monocyte Markers Research Articles

42 EXPLORING THE IMPACT OF AGE AND FRAILTY STATUS ON THE IMMUNE RESPONSE TO COVID-19 ILLNESS USING DETAILED IMMUNO-PHENOTYPING

BackgroundWhilst age and frailty are independently associated with mortality in COVID-19 illness, the underlying immunological mechanisms explaining this remain unexplored. We aimed to explore the impact of age and frailty on the acute immune response to COVID-19 illness.MethodsWe recruited older (aged 65+; n = 33) and younger (aged 20–50; n = 43) participants with acute COVID-19 illness for clinical assessment and detailed immunophenotyping for T-cell, neutrophil, monocyte and inflammatory markers using flow cytometry. We additionally assessed circulating levels of several important pro-inflammatory cytokines. Wilxocon rank-sum, chi-square tests and linear regression were used to examine the impact of age and frailty (Clinical Frailty Score 3–9) on the immune response in COVID-19 illness. Results were compared to age-matched pre-pandemic controls (n = 40).ResultsCOVID-19 illness was associated with a marked pro-inflammatory response (raised CRP, IL-6, IL-2R), lymphopenia and emergency myelopoesis (an expansion of non-classical/intermediate monocytes and immature neutrophils) in both age groups (all P < 0.001). In comparison to younger participants (35.7 ± 8.6 years), older adults (76.7 ± 7.8 years) had a more marked reduction in naïve CD4+ and CD8+ cells and a more marked expansion of activated CD4+, CD8+ and effector CD8+ T-cells (all P < 0.001). These findings were independent of illness severity (all P < 0.001). In comparison to their younger counterparts, older adults had a reduced number of CD10+ neutrophils/non-classical monocytes and greater CRP, IL-6 and IL-2R (P < 0.05), although results were attenuated on adjusting for COVID-19 severity. Frailty was not associated with any significant difference in immune cell population or pro-inflammatory response in acute COVID-19 illness.ConclusionIncreasing age, but not frailty status, was associated with reduced naïve T-cells and a more marked expansion of activated/effector T-cells in acute COVID-19 illness. These findings have important implications for understanding impact of age on anti-viral and pro-inflammatory immune responses.

Abstract 11296: Short-Term Low-Saturated Fat Diet Compared to High-Saturated Fat Diet in Patients with Hypertriglyceridemia: Lipids and Lipoproteins Associated with Monocyte Phenotypic Changes

Background: Monocyte phenotypic changes play a pivotal role in atherogenesis and can be induced by plasma lipids. We analyzed associations of monocyte phenotypes with lipid profiles and the potential of predicting monocyte phenotypes by lipid variables in subjects with hypertriglyceridemia (HTG) after short-term intake of low-saturated fat diet (LSFD) and high-saturated fat diet (HSFD). Method: Subjects with HTG (n=19, 10 men and 9 women, aged 53.9±13.7 years) received isocaloric LSFD (~25% of calories from fat, 5% from saturated fat) and HSFD (~52% of calories from fat, 25% from saturated fat) in randomized order for 4 days (days 1-4) and a test meal on day 5, separated by a 4- to 6-week washout period. Blood was taken on day 1 fasting before the diets and on day 5 fasting and 4 and 6 hours after the test meal to examine lipoprotein profile by enzymatic assay, fatty acids by nuclear magnetic resonance spectroscopy, and monocyte phenotypes by flow cytometry. Least absolute shrinkage and selection operator (LASSO) regression models were built to identify influential lipid variables for key monocyte markers that responded differently to the two diets. Results: LSFD, compared to HSFD, induced lower plasma levels of postprandial total triglyceride (TG), VLDL-TG, and LDL-TG and fasting and postprandial total cholesterol and LDL-cholesterol and altered fatty acid composition, with reduced saturated fatty acids (SFAs) but increased polyunsaturated fatty acids (PUFAs). Compared to HSFD, LSFD reduced monocyte lipid accumulation and levels of several surface markers involved in monocyte adhesion and migration including CD11c, a β2 integrin, on intermediate monocytes. Using the LASSO regression models, we identified that total cholesterol, LDL-TG, and apoB were positively correlated and n-3 PUFAs negatively correlated with lipid accumulation in intermediate monocytes and that total TG, LDL-TG, and apoCIII were positively correlated with CD11c levels on intermediate monocytes. Conclusions: In subjects with HTG, short-term LSFD compared to HSFD improves lipid profiles and monocyte phenotypes. We also identified specific plasma lipid parameters that may be reliable predictors for and contribute to specific monocyte phenotypic changes in HTG.

DNMT3A R882 Mutation in Human Haematopoietic Stem Cells Alters Differentiation Towards Neutrophils and Monocytes

Age related clonal haematopoiesis (ARCH) is defined as the clonal expansion of hematopoietic stem cells (HSCs), driven by recurrent mutations. Many of these are also commonly seen in haematological malignancies, hence termed pre-leukemic mutations (pLM). ARCH carries an increased risk of haematological malignancies and cardiometabolic disease. Further understanding of the role of pLMs in HSC function is necessary to predict and possibly prevent leukemia. DNMT3A R882 is the most common pLM observed in ARCH and is associated with poor outcomes in acute myeloid leukemia (AML). It is acquired early in life and is positively selected in HSCs. HSCs of Dnmt3a knock-out or knock-in mouse models have increased self-renewal capacity and can differentiate towards all lineages. DNMT3A R882 mutation is observed in all mature blood lineages in ARCH individuals, indicating their multipotential differentiation capacity, but the dynamics of differentiation are not known. We hypothesise that DNMT3A R882 mutation affects the differentiation dynamics of HSCs, potentially contributing to disease risk.We characterised the functional changes in HSC differentiation driven by DNMT3A R882 at single cell resolution. Single phenotypic HSCs (CD33-/CD34+/CD45dim/CD38-/CD45RA-) from 9 individuals (Table 1) were cultured in media supporting differentiation into all major blood lineages. To assess changes in differentiation capacity between DNMT3A R882 and wild-type (WT) HSCs within each individual, each single-cell colony was genotyped by targeted DNA sequencing and scored by high-throughput flow cytometry. Flow cytometry data was analysed using a novel unbiased analytical pipeline, which we have named ‘FlowPAC’, allowing generation of a two-dimensional representation of the global output of HSC differentiation by identifying clusters based on fluorochrome intensity. Four samples were underpowered for either DNMT3A R882 or WT colonies and were excluded from this analysis.We did not observe any difference in erythroid versus myeloid or lymphoid (NK) differentiation capacity between DNMT3A R882 and WT HSC. DNMT3A R882 and WT HSCs also produced similar proportions of monocytic and neutrophil colonies. However, FlowPAC analysis identified differences in their level of maturity. CD15 (neutrophil marker) expression was significantly increased in myeloid clusters of DNMT3A R882 colonies compared to WT (p=0.0043), whereas CD14 (monocyte marker) expression was decreased compared to WT (p=0.0645). We further analysed mature neutrophil differentiation using CD66b expression. Consistent with promotion of neutrophil differentiation, CD66b median fluorescence intensity was significantly increased in the CD15+ population of DNMT3A R882 colonies compared to WT. To further investigate monocyte differentiation, we performed RNAseq on colonies containing only monocytes from 1 ARCH sample. Analysis of transcriptional profiles confirmed less mature monocytes in DNMT3A R882 colonies compared to WT. Overall, our data indicate that DNMT3A R882 mutation in HSCs alters neutrophil and monocyte production.Additionally, we observed that in contrast to samples with high LSC content leading to leukemic engraftment in mice, in samples where DNMT3A R882 HSCs were able to reconstitute normal blood production, the expression of the cell surface marker CD49f, a marker of the most potent HSCs, was significantly increased in DNMT3A R882 HSCs compared to WT at the time of sorting. This may suggest unequal distribution of this pLM within the preserved normal HSC pool prior to leukemic transformation.In conclusion, DNMT3A R882 alters the dynamics of human HSC myeloid differentiation. The propensity of DNMT3A R882 derived monocytes to retain an immature phenotype relative to WT cells could represent an early change later facilitating the complete differentiation block seen in AML, driven by the acquisition of additional mutations such as NPM1. DNMT3A R882 also promoted neutrophil maturation. Altered neutrophil differentiation has been observed in patients with germline DNMT3A mutation. As altered neutrophil function plays a key role in cardiovascular disease, future studies are required to investigate whether the effect of DNMT3A R882 on neutrophil differentiation may contribute to the increased cardiovascular disease risk associated with this mutation. [Display omitted] DisclosuresNo relevant conflicts of interest to declare.

ASXL1 Mutation Cooperating with RUNX1 Mutation Further Perturbs the Differentiation of Neutrophils

Acute myeloid leukemia(AML) is characterized by an accumulation of myeloid progenitors. This disease can be caused by various germline mutations, including runx1 and asxl1. Recently several reports showed that mutations of ASXL1 and RUNX1 tend to coexist in AML patients. However, the impact on hematopoiesis remained uncertain. Thus far, lack of an animal model was the main limitation to study the function of the double mutations. In this work, we studied the combination role of runx1 and asxl1 by establishing a novel in vivo zebrafish model. First, we identified the characterization of 6646 patients with myeloid maliganacies in the cbioprotal database. Second, we generated a zebrafish model with double mutations by crossing the ENU-induced runx1 mutant and the CRISPR-CAS9 edited asxl1 mutant. Our results showed that truncation was the most frequent mutation type in RUNX1-mutated patients(56.3%) and ASXL1-mutated patients(87.8%). Besides, the median survival time of patients carrying double mutations was shorter than those with single RUNX1 mutation(9.61 months vs. 16.06 months ) or single ASXL1 mutation(9.61 months vs. 14.47 months). In zebrafish models, we found that the pu.1(myeloid precursor marker) positive cells increased while the gata1(proerythrocyte marker) didn't change in double mutants . Furthermore, mpo and lyz (neutrophil marker) positive cells further reduced while mpeg1 and mfap4(monocyte marker) positive cells didn't show significant difference in double mutants.Overall, we demonstrated that ASXL1 mutation cooperating with RUNX1 mutation further impeded the differentiation of the myeloid progenitors into mature neutrophils and it possibly explained the cause for a worse prognosis of patients with double mutations. [Display omitted] DisclosuresNo relevant conflicts of interest to declare.

Deep Immune Profiling in Multiple Myeloma at Diagnosis and Under Lenalidomide Maintenance Therapy

IntroductionHere we report the results of one of the secondary endpoints of the Finnish Myeloma Group-MM02 study; composition of bone marrow (BM) immune cell subsets at treatment start and during lenalidomide (Len) maintenance focusing on 2 different response groups: good responders (GRs) and poor responders (PRs) at pre- and post-treatment stages. We evaluated the BM immune profile with CyTOF (cytometry by time-of-flight). Our hypothesis was that there would be distinct differences in immune cell profiles between patients with good and poor response, especially in the T and NK cell subsets.Patients and methodsTwenty-two patients were included in this CyTOF study. Eighteen were NDMM patients from FMG-MM02 study who received 3 RVD cycles followed by ASCT. Len started 3 months after ASCT 10 mg/day in 21/28-day cycles until progression or toxicity. BM samples were collected to the Finnish Hematology Registry Clinical Biobank (FHRB Biobank) at several timepoints; from 18 patients at diagnosis, from 11 patients 1 st sample at good response during Len and 2 nd sample if this good response was maintained and from 5 patients at relapse during Len. The patients in the good response cohort (n=11) had progression-free survival (PFS) > 5 years. For comparison, we included 4 BM samples from the FHRB Biobank, taken at a good response after ASCT from MM patients without exposure to Len.ResultsWith a median follow-up of 81 months (13-97) the median PFS was not reached in the good response (GR) cohort and was 18 months in the poor response (PR) cohort. The 1 st GR samples were collected after a median of 21 (6-46) months of Len. The 2 nd samples in GR cohort were collected after a median of 56 (45-67) months of Len. The PR samples were taken after a median of 6 (2-23) months of Len.CyTOF analysis revealed distinct good and poor responder's immune signatures at baseline level. GR, baseline group has shifted phenotype of T cells toward the CD8 T cells, expressing markers, attributed to the cytotoxicity (CD45RA, CD57), as well as having slightly higher abundance of CD8 TE and lower abundance of CD8 naïve T cells. Total T cells amounts were significantly higher in GR. Increased expression of CD56, CD57, and CD16 were also seen on NK cells in GR at the baseline, indicating both maturation and cytotoxic potential of NKs. In contrast, a significant decrease of CD56 and CD16 expression suggesting reduced cytotoxic potential and increase of CD57 were seen on NKs in PR, baseline indicating senescence status a phenotype associated with exhaustion.By using viSNE we discovered two novel populations - MAC1, and MAC2, - associated with disease pathogenesis. We further investigated the composition of these populations, and it appears that MAC1 expressed CD38+CD56+CD45-CD19- presumably malignant plasma cells and MAC2 expressed CD45- CD14+CD38+CD56+TCRgd+CCR7+CCR6+CXCR4+ CXCR3+CXCR5+CD294+, which might be the novel populations, having the features of myeloid suppressor cells. These two immune cells were higher in PR (9.2% and 8.2%, respectively) at baseline as compared to the GR (2.3% and 1.7%).NKs, T cells, and B cells showed a high expression of monocytic marker CD14 and chemokine receptors (CCR7, CCR6, CXCR4, CXCR3, and CXCR5) in PR both at baseline and relapse. This might be attributed to either biological features of MM environment, or the high level of interaction between these populations and monocytes, which left traces of their membranes on the non-monocytic populations.ConclusionsPatients, responded to the treatment, have higher abundances of effector/cytotoxic cells, expressing higher levels of CD57 and/or CD45RA for T cells, and CD57, CD16, and CD56 for NK cells indicating proper differentiation and maturation of T, and NK cells to effector and cytotoxic subsets. Additionally, those patients have less degree of tumor burden as well as decreased expression of chemokine receptors. During the therapy administration, good responders show the increase in effector memory CD4 and CD8 subsets of T cells abundance, indicating even the higher cytotoxic effect of immune system. DisclosuresSilvennoinen: Amgen: Consultancy, Honoraria, Research Funding; Celgene/BMS: Consultancy, Honoraria, Research Funding; Janssen: Consultancy, Honoraria; Sanofi: Consultancy, Honoraria; Takeda: Consultancy, Honoraria, Research Funding. Luoma: Amgen: Honoraria; Janssen: Honoraria; Incyte: Honoraria. Anttila: Amgen: Honoraria; Celgene: Honoraria; Janssen: Honoraria; Takeda: Honoraria. Säily: Takeda: Honoraria; Janssen: Honoraria; Sanofi: Honoraria; Celgene: Honoraria. Partanen: Takeda: Honoraria; Abbvie: Honoraria; Behring: Honoraria. Heckman: Novartis: Research Funding; Orion Pharma: Research Funding; Celgene/BMS: Research Funding; Oncopeptides: Consultancy, Research Funding; Kronos Bio, Inc.: Research Funding.

Histone Hypoacetylation-Driven CD9 Repression Arrests Differentiation and Evades Immunosurveillance in Pediatric Acute Myeloid Leukemia

Acute myeloid leukemia (AML) is a genetically heterogeneous hematologic malignancy characterized by uncontrolled proliferation of myeloid progenitor cells accompanied by impaired terminal differentiation. Despite intensive treatment regimes, the clinical outcomes remain poor, underscoring the need to decipher the underlying pathology and implement therapeutic interventions. Emerging evidence suggest myeloblasts could evolve machineries to evade T cell patrol and hinder immunotherapies. Here, we present a new mechanism driving immune escape in the context of pediatric AML, based on our discoveries of CD9 in hematopoietic stem cells (HSC; Leung et al, Blood, 2011) and acute lymphoblastic leukemia (ALL; Leung et al, Leukemia, 2020).We first examined CD9 expression and its prognostic impact in patient cohorts of childhood leukemia. The expression of cell surface CD9 on blasts of pediatric AML patients (13.2%, n=81) was significantly lower than that of pediatric ALL patients (90.4%, n=181, P<0.001) or that on CD34+ HSC of normal bone marrow donors (48.4%, n=22, P=0.014). Among pediatric AML cases, the blasts of 32 patients (39.5%) were CD9+. The 5-year RFS rate of CD9- patients was significantly lower than CD9+ patients (34.1% vs. 61.2%, P=0.018).Enforced CD9 expression in MV4-11 cells significantly suppressed proliferation (P<0.01), Ki-67 expression (P=0.041) and colony formation (P=0.002). NOD/SCID mice transplanted with CD9+ cells exhibited a drastic reduction of leukemic load in the bone marrow, spleen, blood and liver by 70.7-91.8% (P<0.05), a significantly prolonged survival duration (P<0.001), and a marked regression of extramedullary myeloid sarcoma when compared with animals transplanted with CD9- MV4-11 cells.A marked decrease of H3K9/27Ac occupancy in the CD9 locus was observed in AML than in ALL cells (4.8-14.2-fold, P<0.05), and strongly correlated with CD9 repression (r=0.585-0.719, P<0.01). Exposure of CD9- AML cell lines (n=8) and samples (n=9) with a histone deacetylase inhibitor panobinostat significantly elevated CD9 mRNA and protein expression (3.1-32.2-fold, P<0.05), restored activating histone acetylation marks (4.1-41.6-fold, P<0.05) and suppressed myeloblast proliferation ex vivo (median IC50: 21.4 nM).Mechanistically, global transcriptome profiling of pediatric AML (n=31) revealed decreased stemness (NES: -1.7, P=0.01) and increased monocyte (NES: 1.8, P=0.034) gene signatures in CD9+ patient samples. Moreover, single-cell transcriptomic analyses of total bone marrow cells from MV4-11-tranplanted mice detected a significant enrichment of differentially regulated genes functioning in the antigen processing and presentation pathway. Concordantly, we observed a profound up-regulation of CD9 (9.4-51.1-fold, P<0.001) in PMA-mediated monocyte/macrophage-like AML differentiation cultures preceding the appearance of lineage markers CD14, CD36 and iCD68 as well as the antigen presentation molecule MHC-I. In the overexpression system, CD9 not only elevated the expression of monocytic markers, but also promoted basal and IFNγ-induced MHC-I/II expression (P<0.01) through the JAK/STAT axis. Inter-patient comparisons of bone marrow samples (n=27) revealed a higher MHC-I expression in CD9+ than CD9- AML (MFI: 61820 vs. 18601, P<0.001). Interestingly, tetraspanin CD9 physically bound to MHC-I/II and formed an immune complex as revealed by co-immunoprecipitation. In NSG mice, co-transplantation of human PBMCs mounted an effective immunity against CD9+ but not CD9- AML (MV4-11 and MOLM-13), concomitant with a robust bone marrow infiltration of cytotoxic T cells. Syngeneic transplantation in immunocompetent mice, AML/T cell co-cultures, antigen-specific assays and panobinostat priming/T cell adoptive transfer are currently underway to fully dissect the role of CD9 in leukemia immunity.Taken together, our data provided molecular, cellular and clinical evidence showing the plausible function of CD9 as a key driver intertwining differentiation and immunosurveillance in pediatric AML, and inspired a new combinatorial epigenetic/immunotherapy for this rare but aggressive malignancy. DisclosuresNo relevant conflicts of interest to declare.

Mechanical Checkpoint Regulates Monocyte Differentiation in Fibrotic Matrix

Myelofibrosis (MF) is a progressive, myeloid malignancy characterized by deposition of collagen and reticulin fibers in the bone marrow (BM). Previous studies have shown that monocytosis is associated with poor prognosis in MF, highlighting a potential pathogenic role for monocytes in MF. Although many studies have addressed the role of cell-intrinsic and soluble extracellular factors in MF development, it is currently unknown if mechanical properties of fibrotic BM contribute to aberrant differentiation of myeloid cells and of monocytes in particular.We first defined the stiffness and viscoelastic properties of healthy and fibrotic BM. Stiffness is defined as the resistance of a matrix to deformation, while viscoelasticity is the rate of dissipation of an applied stress over time. Independent of stiffness, an applied stress relaxes rapidly in a more viscous, liquid-like matrix, whereas in a more elastic, solid-like material, stress relaxes slowly.We next generated a cohort of fibrotic and non-fibrotic mice by transplanting retrovirally transduced JAK2V617F or empty vector (EV) control hematopoietic stem and progenitor cells (HSPCs) into lethally irradiated recipients. Femurs from these mice were harvested seven months post-transplant, as well as from age- and sex-matched healthy primary mice. Nanoindentation was performed to measure BM stiffness and viscoelasticity. Fibrotic BM showed higher stiffness, as well as trending higher elastic, solid-like properties, compared to BM of control mice.We then aimed to study the effect of matrix stiffness and viscoelasticity on monocytes. Human BM-derived monocytes were encapsulated in stiff, viscous or stiff, elastic hydrogels and cultured in the presence of GM-CSF, IL-4, and PGE2 for 3 days, followed by nanoString and flow cytometry analyses. Cells in elastic gels upregulated gene sets associated with co-stimulatory molecules and cytokine receptor signaling, MHC class II antigen presentation, and regulation of extracellular matrix (ECM), compared to cells in viscous gels of the same stiffness. The fraction of dendritic cells (DCs) was significantly upregulated, as indicated by double-positive CD11c+CD1c+ (40.9% viscous vs 69.5% elastic of CD11b+HLA-DR+ cells) and CD80+ cells (20.9% viscous vs 62.7% elastic of CD11b+HLA-DR+ cells), and surface expression of HLA-DR (gMFI 2587 viscous vs 6334 elastic). Consistent with these findings, the fraction of pro-fibrotic SLAMF7+ cells (4.2% viscous vs 17.3% elastic) were also significantly higher in elastic gels. Together, these data suggest that stiff, elastic ECM drives pro-inflammatory polarization and differentiation of monocytes into antigen-presenting cells.Next, we examined the role of the cytoskeleton on human monocyte differentiation. Cortical F-actin was significantly upregulated in cells in stiff, elastic gels compared to viscous gels. Cells were exposed to a highly selective small molecular inhibitor of the γ-isoform of PI3K. Treatment with the PI3Ky inhibitor significantly reduced F-actin staining of cells in elastic gels, upregulated immature monocyte markers, reduced surface expression of HLA-DR, and downregulated the cytokines IL6, IL8, CCL4, which have previously been associated with disease progression in myelofibrosis.In line with the above human ex vivo data, BM isolated from fibrotic mice (described above) showed skewing towards Ly6G-Ly6C+ monocytes (a population enriched for inflammatory monocytes) within the CD11b myeloid compartment compared to control transplanted mice or to non-fibrotic mice that were transplanted with endogenously expressing Jak2V617F cells. Additionally, the percentage of conventional DCs (cDCs) was increased in fibrotic Jak2V617F mice compared to control mice. Importantly, 16 day in vivo treatment with the PI3Ky inhibitor significantly reduced the fraction of Ly6G-Ly6C+ monocytes within the CD11b compartment as well as the fraction of cDCs, compared to vehicle-treated Jak2V617F mice.In summary, fibrotic BM is stiffer and more elastic than normal BM. Our studies show that a stiff, elastic BM environment drives monocytes towards a more pro-inflammatory state which can in part be suppressed by PI3K-γ inhibition. Our results have relevance for human MF by demonstrating that a fibrotic BM niche is not just a consequence of chronic inflammation but is also inflammation-promoting.KHV and AEM contributed equally to this work. DisclosuresPozdnyakova: Scopio Labs: Consultancy. Mullally: Janssen, PharmaEssentia, Constellation and Relay Therapeutics: Consultancy. Wucherpfennig: Novartis: Research Funding; Nextechinvest: Membership on an entity's Board of Directors or advisory committees; Immunitas Therapeutics: Current holder of individual stocks in a privately-held company; TScan Therapeutics: Membership on an entity's Board of Directors or advisory committees; TCR2 Therapeutics: Membership on an entity's Board of Directors or advisory committees; SQZ Biotech: Membership on an entity's Board of Directors or advisory committees. Mooney: Novartis: Patents & Royalties: Licensed IP, Research Funding; Sirenex: Patents & Royalties: Licensed IP; Samyang Corp: Membership on an entity's Board of Directors or advisory committees; IVIVA: Membership on an entity's Board of Directors or advisory committees; Attivare: Current holder of individual stocks in a privately-held company, Membership on an entity's Board of Directors or advisory committees; Revela: Membership on an entity's Board of Directors or advisory committees; Amend Surgical: Patents & Royalties: Licensed IP; Lyell: Current equity holder in publicly-traded company, Patents & Royalties.

Cordycerebroside A suppresses VCAM-dependent monocyte adhesion in osteoarthritis synovial fibroblasts by inhibiting MEK/ERK/AP-1 signaling

• VCAM1 and CD11b higher levels express in OA compared with healthy controls. • Cordycerebroside A suppressed VCAM-1 mediated-monocyte adhesion in human OASF. • The MEK/ERK/AP-1 signaling regulated cordycerebroside A effects. Osteoarthritis (OA) is characterized by the infiltration and adhesion of monocyte into the joint synovium. Vascular cell adhesion molecule 1 (VCAM-1) is a critical cell adhesion molecule that controls monocyte motility during OA progression. Cordycerebroside A, a cerebroside compound isolated from Cordyceps militaris , inhibits the production of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) in synovial macrophages, but has not yet been investigated in OA. Gene Expression Omnibus (GEO) dataset analysis revealed higher levels of VCAM-1 and CD11b (a monocyte marker) in OA synovial tissue compared with normal healthy tissue. The same results were observed in anterior cruciate ligament transaction (ACLT)-induced OA in rats compared with normal healthy controls. Cordycerebroside A markedly suppressed VCAM-1 expression and monocyte adhesion in human OA synovial fibroblasts. The MEK, ERK and AP-1 signaling cascades regulated cordycerebroside A-induced inhibition of VCAM-1 production. Thus, cordycerebroside A is a promising agent for the treatment of OA.

A Short Corticosteroid Course Reduces Symptoms and Immunological Alterations Underlying Long-COVID.

Despite the growing number of patients with persistent symptoms after acute SARS-CoV-2 infection, the pathophysiology underlying long-COVID is not yet well characterized, and there is no established therapy. We performed a deep immune profiling in nine patients with persistent symptoms (PSP), before and after a 4-day prednisone course, and five post-COVID-19 patients without persistent symptoms (NSP). PSP showed a perturbed distribution of circulating mononuclear cell populations. Symptoms in PSP were accompanied by a pro-inflammatory phenotype characterized by increased conventional dendritic cells and augmented expression of antigen presentation, co-stimulation, migration, and activation markers in monocytes. The adaptive immunity compartment in PSP showed a Th1-predominance, decreased naïve and regulatory T cells, and augmentation of the PD-1 exhaustion marker. These immune alterations reverted after the corticosteroid treatment and were maintained during the 4-month follow-up, and their normalization correlated with clinical amelioration. The current work highlights an immunopathogenic basis together with a possible role for steroids in the treatment for long-COVID.

Antileukemic Natural Product Induced Both Apoptotic and Pyroptotic Programmed Cell Death and Differentiation Effect.

Acute myeloid leukemia (AML) is one of the most common forms of leukemia. Despite advances in the management of such malignancies and the progress of novel therapies, unmet medical needs still exist in AML because of several factors, including poor response to chemotherapy and high relapse rates. Ardisianone, a plant-derived natural component with an alkyl benzoquinone structure, induced apoptosis in leukemic HL-60 cells. The determination of dozens of apoptosis-related proteins showed that ardisianone upregulated death receptors and downregulated the inhibitor of apoptosis protein (IAPs). Western blotting showed that ardisianone induced a dramatic increase in tumor necrosis factor receptor 2 (TNFR2) protein expression. Ardisianone also induced downstream signaling by activating caspase-8 and -3 and degradation in Bid, a caspase-8 substrate. Furthermore, ardisianone induced degradation in DNA fragmentation factor 45 kDa (DFF45), a subunit of inhibitors of caspase-activated DNase (ICAD). Q-VD-OPh (a broad-spectrum caspase inhibitor) significantly diminished ardisianone-induced apoptosis, confirming the involvement of caspase-dependent apoptosis. Moreover, ardisianone induced pyroptosis. Using transmission electron microscopic examination and Western blot analysis, key markers including gasdermin D, high mobility group box1 (HMGB1), and caspase-1 and -5 were detected. Notably, ardisianone induced the differentiation of the remaining survival cells, which were characterized by an increase in the expression of CD11b and CD68, two markers of macrophages and monocytes. Wright–Giemsa staining also showed the differentiation of cells into monocyte and macrophage morphology. In conclusion, the data suggested that ardisianone induced the apoptosis and pyroptosis of leukemic cells through downregulation of IAPs and activation of caspase pathways that caused gasdermin D cleavage and DNA double-stranded breaks and ultimately led to programmed cell death. Ardisianone also induced the differentiation of leukemic cells into monocyte-like and macrophage-like cells. The data suggested the potential of ardisianone for further antileukemic development.

Tracking distinct microglia subpopulations with photoconvertible Dendra2 in vivo

BackgroundThe ability to track individual immune cells within the central nervous system has revolutionized our understanding of the roles that microglia and monocytes play in synaptic maintenance, plasticity, and neurodegenerative diseases. However, distinguishing between similar subpopulations of mobile immune cells over time during episodes of neuronal death and tissue remodeling has proven to be challenging.MethodsWe recombineered a photoconvertible fluorescent protein (Dendra2; D2) downstream of the Cx3cr1 promoter commonly used to drive expression of fluorescent markers in microglia and monocytes. Like the popular Cx3cr1–GFP line (Cx3cr1+/GFP), naïve microglia in Cx3cr1–Dendra2 mice (Cx3cr1+/D2) fluoresce green and can be noninvasively imaged in vivo throughout the CNS. In addition, individual D2-expressing cells can be photoconverted, resulting in red fluorescence, and tracked unambiguously within a field of green non-photoconverted cells for several days in vivo.ResultsDendra2-expressing retinal microglia were noninvasively photoconverted in both ex vivo and in vivo conditions. Local in vivo D2 photoconversion was sufficiently robust to quantify cell subpopulations by flow cytometry, and the protein was stable enough to survive tissue processing for immunohistochemistry. Simultaneous in vivo fluorescence imaging of Dendra2 and light scattering measurements (Optical Coherence Tomography, OCT) were used to assess responses of individual microglial cells to localized neuronal damage and to identify the infiltration of monocytes from the vasculature in response to large scale neurodegeneration.ConclusionsThe ability to noninvasively and unambiguously track D2-expressing microglia and monocytes in vivo through space and time makes the Cx3cr1–Dendra2 mouse model a powerful new tool for disentangling the roles of distinct immune cell subpopulations in neuroinflammation.

Circulating microparticles are increased amongst people presenting with HIV and advanced immune suppression in Malawi and correlate closely with arterial stiffness: a nested case control study

Background: We aimed to investigate whether circulating microparticle (CMPs) subsets were raised amongst people presenting with human immunodeficiency virus (HIV) and advanced immune suppression in Malawi, and whether they associated with arterial stiffness. Methods: Antiretroviral therapy (ART)-naïve adults with a new HIV diagnosis and CD4 <100 cells/µL had microparticle characterisation and carotid femoral Pulse Wave Velocity (cfPWV) at 2 weeks post ART initiation. HIV uninfected controls were matched on age, systolic blood pressure (BP) and diastolic BP in a 1:1 ratio. Circulating microparticles were identified from platelet poor plasma and stained for endothelial, leucocyte, monocyte and platelet markers. Results: The median (IQ) total CMP count for 71 participants was 1 log higher in HIV compared to those without (p<0.0001) and was associated with arterial stiffness (spearman rho 0.47, p<0.001). In adjusted analysis, every log increase in circulating particles showed a 20% increase in cfPWV (95% confidence interval [CI] 4 - 40%, p=0.02). In terms of subsets, endothelial and platelet derived microparticles were most strongly associated with HIV. Endothelial derived E-selectin+ CMPs were 1.3log-fold higher and platelet derived CD42a+ CMPs were 1.4log-fold higher (both p<0.0001). Endothelial and platelet derived CMPs also correlated most closely with arterial stiffness (spearman rho: E-selectin+ 0.57 and CD42a 0.56, both p<0.0001). Conclusions: Circulating microparticles associate strongly with arterial stiffness among people living with HIV in Malawi. Endothelial damage and platelet microparticles are the predominant cell origin types and future translational studies could consider prioritising these pathways.

Prognostic and Immunological Role of Key Genes of Ferroptosis in Pan-Cancer.

Solute carrier family 7 member 11 (SLC7A11), glutathione peroxidase 4 (GPX4), and apoptosis inducing factor mitochondria associated 2 (AIFM2) are the key regulators in ferroptosis. However, the expression patterns and prognostic roles of these genes in pan-cancer are still largely unclear. The expression patterns and prognostic roles of SLC7A11, GPX4, and AIFM2 and the relationships between the expression levels of these genes and immune infiltration levels in pan-cancer were analyzed by using TIMER, gene expression profiling interactive analysis (GEPIA), Oncomine, and Kaplan–Meier databases. Our results showed that both SLC7A11 and GPX4 were overexpressed in colorectal cancer, and SLC7A11 was overexpressed in lung cancer. High levels of SLC7A11 and AIFM2 were significantly linked with the shortened disease-free survival and overall survival (OS) in adrenocortical carcinoma (ACC), respectively. And high expression of SLC7A11, GPX4, and AIFM2 were significantly correlated with the shortened OS of acute myeloid leukemia patients. In esophageal carcinoma (ESCA), GPX4 expression was significantly associated with the infiltration of macrophage and myeloid dendritic cell, and AIFM2 expression was significantly associated with the infiltration of CD4+ T cell. Importantly, GPX4 expression was positively correlated with the expression levels of monocyte markers (CD14 and CD115) and M2 macrophage markers (VSIG4 and MS4A4A) both in ESCA and in head and neck squamous cell carcinoma (HNSC). In summary, SLC7A11, GPX4, and AIFM2 are dysregulated in many types of cancers, and are candidate prognostic biomarkers for many types of cancers, and can be used to evaluate the infiltration of immune cells in tumor tissues.

Interferon-γ Produced by EBV-Positive Neoplastic NK-Cells Induces Differentiation into Macrophages and Procoagulant Activity of Monocytes, Which Leads to HLH.

Simple SummaryEpstein–Barr virus (EBV), a common virus all over the world, infects not only B-cells but also T- and NK-cells. Once infected with EBV, human beings remain infected for life, and EBV renders infected B-cells immortal. EBV-positive NK-cell neoplasms, such as extranodal NK/T-cell lymphoma of nasal type, aggressive NK-cell leukemia, and chronic active EBV infection, are relatively rare but lethal disorders. They show systemic inflammation and progress to hemophagocytic lymphohistiocytosis (HLH), a life-threatening state of immune hyperactivation. The suppression and prevention of HLH are important to treat the neoplasms. Revealing the mechanism will pave a new path for treatment. We show herein that IFN-γ produced by EBV-positive neoplastic NK-cell is responsible for inducing the differentiation and the activation of M1-like macrophages. Suppressing IFN-γ may regulate HLH in EBV-positive NK-cell neoplasms.Epstein–Barr virus (EBV)-positive T- or NK-cell neoplasms show progressive systemic inflammation and abnormal blood coagulation causing hemophagocytic lymphohistiocytosis (HLH). It was reported that inflammatory cytokines were produced and secreted by EBV-positive neoplastic T- or NK-cells. These cytokines can induce the differentiation of monocytes into macrophages leading to HLH. To clarify which products of EBV-positive neoplastic T- or NK-cells have effects on monocytes, we performed a co-culture assay of monocytes with the supernatants of EBV-positive T- or NK-cell lines. The expression of differentiation markers, the phagocytosis ability, and the mRNA expression of the inflammatory cytokines of THP-1, a monocytic cell line, clearly increased after culturing with the supernatants from EBV-NK-cell lines. Co-culturing with the supernatants promoted the expression of CD80 and CD206 as well as M1 and M2 macrophage markers in human monocytes. Co-culturing with the supernatants of EBV-NK-cell lines significantly enhanced the procoagulant activity and the tissue factor expression of monocytes. Interferon (IFN)-γ was elevated extremely not only in the supernatant of EBV-NK-cell lines but also in the plasma of EBV-positive NK-cell neoplasms patients accompanying HLH. Finally, we confirmed that IFN-γ directly enhanced the differentiation into M1-like macrophages and the procoagulant activity of monocytes. Our findings suggest that IFN-γ may potentially serve as a therapeutic target to regulate HLH in EBV-positive NK-cell neoplasms.

DISTINCTION BETWEEN ACUTE MYELOID LEUKAEMIA WITH MYELODYSPLASIA-RELATED CHANGES AND MIXED-PHENOTYPE ACUTE LEUKAEMIA: A DIAGNOSTIC CHALLENGE

The revised 4 th edition of the World Health Organization (WHO) classification of tumours of haematopoietic and lymphoid tissues is based on clinical, morphological, immunophenotypic and genetic features. A case of acute myeloid leukaemia with myelodysplasia-related changes (AML-MRC) in which there was a mixed phenotype of blasts (B-cell/myeloid) has been previously described. We hereby also report an acute leukaemia case that had conflicting morphological and immunophenotypic findings, regarding the revised WHO classification. Patient was a 77 year-old female investigating anaemia for the past few months. Complete blood count (CBC) showed macrocytic anaemia (haemoglobin: 8.3 g/l; MCV: 102 fl) and thrombocytopenia (116 x 10 9 /l), with a normal leukocyte count. Bone marrow assessment was performed when the patient CBC showed circulating blasts. Bone marrow flow cytometry immunophenotyping (FCI) revealed two blast cell populations: one population (about 26% of events) had an immature B-cell phenotype with expression of cytCD22, cytCD79a, CD19, CD22, CD34, CD45(dim), CD58, CD81(dim), CD200, HLA-DR, nuTdT, and an aberrant CD13 and CD123 coexpression; while the other population (about 23% of events) had an immature myeloid phenotype with expression of CD4(dim), CD13, CD25, CD33, CD34, CD58, CD81, CD117, CD123, CD200 and HLA-DR. Neither population expressed cytCD3, cytMPO, CD2, CD3, CD7, CD10, CD11b, CD11c, CD18, CD20, CD36, CD56, CD64 or CD138. If classified isolated, the myeloid population would correspond to an acute myeloid leukaemia (AML) with minimal differentiation and the B-cell population, to a B-lymphoblastic leukaemia/lymphoma (B-ALL). In addition to the FCI data, bone marrow morphological evaluation revealed hypercellularity with severe multilineage dysplasia and two types of blasts with different sizes and morphology, blast cells accounted for 58% of cellularity. Cytogenetic studies showed a karyotype with 45,Xc, t(3;21)(q26;q22). FCI diagnosis considering the EGIL scoring system would be of a biphenotypic acute leukaemia, however to fit into the WHO classification of a mixed-phenotype acute leukaemia (MPAL), the myeloid population would need to express MPO or two monocytic markers, which was not what we observed. Nevertheless, bone marrow morphological findings were suggestive of AML-MRC. There are overlapping features between MPAL and genetically defined AML-MRC. A case series of MPAL identified complex karyotype as the most common genetic abnormality and the WHO classification specifies that AML with complex karyotypes should be classified as AML-MRC. It is recommended that karyotype findings should not be the sole deciding factor to distinguish MPAL from AML-MRC and other factors such as clinical history, morphological findings, immunophenotype and presence of somatic mutations associated with other neoplasms should be considered when leukemic blasts meet criteria for MPAL and the karyotype analysis has myelodysplasia-related abnormalities. Since we did not have access to karyotype results at diagnosis, a descriptive report of FCI and morphological findings was provided. In conclusion, FCI diagnosis of MPAL in the presence of myelodysplasia-related morphological alterations remains a challenge and should take into consideration other laboratory and clinical data.

Celiac Disease Defined by Over-Sensitivity to Gliadin Activation and Superior Antigen Presentation of Dendritic Cells

The autoimmune condition, Celiac Disease (CeD), displays broad clinical symptoms due to gluten exposure. Its genetic association with DQ variants in the human leukocyte antigen (HLA) system has been recognised. Monocyte-derived mature dendritic cells (MoDCs) present gluten peptides through HLA-DQ and co-stimulatory molecules to T lymphocytes, eliciting a cytokine-rich microenvironment. Having access to CeD associated families prevalent in the Czech Republic, this study utilised an in vitro model to investigate their differential monocyte profile. The higher monocyte yields isolated from PBMCs of CeD patients versus control individuals also reflected the greater proportion of dendritic cells derived from these sources following lipopolysaccharide (LPS)/ peptic-tryptic-gliadin (PTG) fragment stimulation. Cell surface markers of CeD monocytes and MoDCs were subsequently profiled. This foremost study identified a novel bio-profile characterised by elevated CD64 and reduced CD33 levels, unique to CD14++ monocytes of CeD patients. Normalisation to LPS stimulation revealed the increased sensitivity of CeD-MoDCs to PTG, as shown by CD86 and HLA-DQ flow cytometric readouts. Enhanced CD86 and HLA-DQ expression in CeD-MoDCs were revealed by confocal microscopy. Analysis highlighted their dominance at the CeD-MoDC membrane in comparison to controls, reflective of superior antigen presentation ability. In conclusion, this investigative study deciphered the monocytes and MoDCs of CeD patients with the identification of a novel bio-profile marker of potential diagnostic value for clinical interpretation. Herein, the characterisation of CD86 and HLA-DQ as activators to stimulants, along with robust membrane assembly reflective of efficient antigen presentation, offers CeD targeted therapeutic avenues worth further exploration.

Collagen Type III and VI Remodeling Biomarkers Are Associated with Kidney Fibrosis in Lupus Nephritis.

Lupus nephritis (LN) occurs in <40% of patients with SLE. Reliable biomarkers of kidney damage are needed to identify patients with SLE at risk of developing LN to improve screening, treat the disease earlier, and halt progression to kidney failure. Novel biomarkers of extracellular matrix remodeling were evaluated as markers of kidney fibrosis and disease activity in patients with LN. Biomarkers of the interstitial collagen type III (PRO-C3) and type VI (PRO-C6) formation and of collagen type III (C3M) degradation were evaluated in the serum and urine of 40 patients with LN, 20 patients with SLE but without LN, 20 healthy controls, and ten biopsy controls (histologic kidney inflammation/damage without SLE). Their association with histologic markers of interstitial fibrosis and tubular atrophy, with inflammatory cell infiltration and with disease activity and chronicity in the patients with LN was assessed. Despite PRO-C3 (serum) and PRO-C6 (serum and urine) being significantly elevated in patients with LN compared with healthy controls, the markers did not differentiate patients with LN from those with SLE. C3M (urine) levels were not different in LN compared with the other groups. C3M (urine) strongly correlated and PRO-C6 (serum and urine) inversely correlated with kidney function (eGFR). The biomarkers of interstitial collagen turnover PRO-C6 (serum) and C3M (urine) correlated with histologic markers of interstitial fibrosis, tubular atrophy, and monocyte infiltration. Noninvasive collagen turnover biomarkers are promising tools to identify patients with SLE with kidney histologic modifications.

Abstract 11: Single Cell Eccite-seq Analysis Reveal An Important Role Of Monocyte-specific Nlrp3 Inflammasome For Salt-sensitivity Of Hypertension In Humans

Salt sensitivity of blood pressure is an independent predictor of death due to cardiovascular events. Diagnosis of salt-sensitivity is not feasible in the clinic, making it difficult to investigate therapeutic strategies. We hypothesized that NLRP3-inflammasome and IL-1β production in monocytes plays a role in salt-sensitive hypertension. We phenotyped salt-sensitivity of blood pressure using an acute inpatient Weinberger protocol of an isocaloric high salt diet and rapid intravenous salt-loading, followed by low salt diet and furosemide-induced salt-depletion. Ambulatory blood pressure was continuously monitored and averaged for the days of salt-loading and salt-depletion. Blood samples were obtained at baseline, salt-loading, and after salt-depletion. Median age was 54 years (44-55), 3 of the 5 subjects were female, screening systolic blood pressure was 140 mmHg (134-148), diastolic blood pressure was 88 mmHg (84-99), and BMI was 35 kg/m 2 (30-39). Using cell hashing and ECCITE-seq analysis, we profiled transcriptomes in multiple immune cell types using antibody-derived tags (ADTs). UMAP clustering of different cell types were identified by ADTs including monocyte markers CD14 and CD16. Interestingly, UMAP visualization of CD14+ and CD16+ clusters indicated a greater decrease in CD14+ clusters after salt-depletion in the salt-resistant subjects than the salt-sensitive; however the salt-sensitive subjects had a greater decrease in CD16+ clusters than the salt-resistant group after both salt-loading and salt-depletion. These data were confirmed using flow cytometry. Unlike in salt-resistant participants, we found that within monocyte clusters, salt-sensitivity was associated with down regulation of the inflammasome components NLRP3 (0.386 ± 1.18 vs. 0.197 ± 0.778) and IL-1β (0.858 ± 2.32 vs. 0.159 ± 0.925) following salt-depletion. Using flow cytometry, we found Δ% isoLG+ CD14+/CD16+ monocytes correlated with salt-sensitivity of blood pressure (r=0.88, 95% CI, p=0.05). These results suggest that the inflammasome and monocyte activation are dynamically regulated by dietary salt in vivo and can serve as a potential diagnostic biomarker for salt-sensitivity of blood pressure.

Maternal Neutrophil Depletion Fails to Avert Systemic Lipopolysaccharide-Induced Early Pregnancy Defects in Mice.

Maternal infection-induced early pregnancy complications arise from perturbation of the immune environment at the uterine early blastocyst implantation site (EBIS), yet the underlying mechanisms remain unclear. Here, we demonstrated in a mouse model that the progression of normal pregnancy from days 4 to 6 induced steady migration of leukocytes away from the uterine decidual stromal zone (DSZ) that surrounds the implanted blastocyst. Uterine macrophages were found to be CD206+ M2-polarized. While monocytes were nearly absent in the DSZ, DSZ cells were found to express monocyte marker protein Ly6C. Systemic endotoxic lipopolysaccharide (LPS) exposure on day 5 of pregnancy led to: (1) rapid (at 2 h) induction of neutrophil chemoattractants that promoted huge neutrophil infiltrations at the EBISs by 24 h; (2) rapid (at 2 h) elevation of mRNA levels of MyD88, but not Trif, modulated cytokines at the EBISs; and (3) dose-dependent EBIS defects by day 7 of pregnancy. Yet, elimination of maternal neutrophils using anti-Ly6G antibody prior to LPS exposure failed to avert LPS-induced EBIS defects allowing us to suggest that activation of Tlr4-MyD88 dependent inflammatory pathway is involved in LPS-induced defects at EBISs. Thus, blocking the activation of the Tlr4-MyD88 signaling pathway may be an interesting approach to prevent infection-induced pathology at EBISs.

Desiccation Induced Conjunctival Monocyte Recruitment and Activation - Implications for Keratoconjunctivitis

BackgroundLacrimal gland secretory dysfunction in Sjögren syndrome (SS) causes ocular surface desiccation that is associated with increased cytokine expression and number of antigen-presenting cells (APCs) in the conjunctiva. This study evaluated the hypothesis that desiccating stress (DS) alters the percentage and gene expression of myeloid cell populations in the conjunctiva.MethodsDS was induced by pharmacologic suppression of tear secretion and exposure to drafty low humidity environment. Bone marrow chimeras and adoptive transfer of CD45.1+ bone marrow cells to CD45.2+ C-C chemokine receptor 2 knockout (CCR2-/-) mice were used to track DS-induced myeloid cell recruitment to the conjunctiva. Flow cytometry evaluated myeloid cell populations in conjunctivae obtained from non-stressed eyes and those exposed to DS for 5 days. CD11b+ myeloid lineage cells were gated on monocyte (Ly6C), macrophage (CD64, MHCII) and DC (CD11c, MHCII) lineage markers. NanoString immune arrays were performed on sorted MHCII+ and MHCII- monocyte/macrophage cell populations.ResultsDS significantly increased the recruitment of adoptively transferred MHCII positive and negative myeloid cells to the conjunctiva in a CCR2 dependent fashion. The percentage of resident conjunctival monocytes (Ly6C+CD64-) significantly decreased while CD64+MHCII+ macrophages increased over 5 days of DS (P<0.05 for both). Comparison of gene expression between the MHCII- monocyte and MHCII+ populations in non-stressed conjunctiva revealed a ≥ 2 log2 fold increase in 95 genes and decrease in 46 genes. Upregulated genes are associated with antigen presentation, cytokine/chemokine, M1 macrophage and NLRP3 inflammasome pathways. DS increased innate inflammatory genes in monocytes and MHCII+ cells and increased M1 macrophage (Trem1, Ido1, Il12b, Stat5b) and decreased homeostasis (Mertk) and M2 macrophage (Arg1) genes in MHCII+ cells.ConclusionsThere are myeloid cell populations in the conjunctiva with distinct phenotype and gene expression patterns. DS recruits myeloid cells from the blood and significantly changes their phenotype in the conjunctiva. DS also alters expression of an array of innate inflammatory genes. Immature monocytes in the unstressed conjunctiva appear to cascade to MHCII+ macrophages during DS, suggesting that DS promotes maturation of monocytes to antigen presenting cells with increased expression of inflammatory genes that may contribute to the pathogenesis of SS keratoconjunctivitis sicca.