Elevated Calprotectin and Abnormal Myeloid Cell Subsets Discriminate Severe from Mild COVID-19.

Blood myeloid cells are known to be dysregulated in coronavirus disease 2019 (COVID-19), caused by SARS-CoV-2. It is unknown whether the innate myeloid response differs with disease severity and whether markers of innate immunity discriminate high-risk patients. Thus, we performed high-dimensional flow cytometry and single-cell RNA sequencing of COVID-19 patient peripheral blood cells and detected disappearance of non-classical CD14LowCD16High monocytes, accumulation of HLA-DRLow classical monocytes (Human Leukocyte Antigen - DR isotype), and release of massive amounts of calprotectin (S100A8/S100A9) in severe cases. Immature CD10LowCD101-CXCR4+/- neutrophils with an immunosuppressive profile accumulated in the blood and lungs, suggesting emergency myelopoiesis. Finally, we show that calprotectin plasma level and a routine flow cytometry assay detecting decreased frequencies of non-classical monocytes could discriminate patients who develop a severe form of COVID-19, suggesting a predictive value that deserves prospective evaluation.

Partial recovery of peripheral blood monocyte subsets in head and neck squamous cell carcinoma patients upon radio(chemo)therapy is associated with decreased plasma CXCL11.

BACKGROUND: Head and neck squamous cell carcinoma (HNSCC) represents a common and heterogeneous malignancy of the oral cavity, pharynx and larynx. Surgery and radio(chemo)therapy are the standard treatment options and also have great influence on the composition of the tumor microenvironment and immune cell functions. However, the impact of radio(chemo)therapy on the distribution and characteristics of circulating monocyte subsets in HNSCC are not fully understood. METHODS: Expression patterns of adhesion molecules and chemokine receptors CD11a (integrin-α L; LFA-1), CD11b (integrin-α M; Mac-1), CD11c (integrin-α X), CX3CR1 (CX3CL1 receptor) and checkpoint molecule PD-L1 (programmed cell death ligand-1) were investigated upon radio(chemo)therapeutic treatment using flow cytometry. Furthermore, comprehensive analysis of plasma cytokines was performed before and after treatment using ELISA measurements. RESULTS: Our data reveal a partial recovery of circulating monocytes in HNSCC patients upon radio(chemo)therapeutic treatment, with differential effects of the individual therapy regimen. PD-L1 expression on non-classical monocytes significantly correlates with the individual plasma levels of chemokine CXCL11 (C-X-C motif chemokine 11). CONCLUSIONS: Further comprehensive investigations on larger patient cohorts are required to elucidate the meaningfulness of peripheral blood monocyte subsets and chemokine CXCL11 as potential bioliquid indicators in HNSCC with regard to therapy response and the individual immunological situation.

Improved levels of checkpoint molecule PD-L1 on peripheral blood monocyte subsets in obstructive sleep apnea syndrome patients upon hypoglossal nerve stimulation.

Oxidative stress in patients suffering from obstructive sleep apnea syndrome (OSAS) is associated with a low-grade systemic inflammation, immune disturbance, and increased invasion of monocytes into the endothelium. Besides continuous positive airway pressure (PAP), hypoglossal nerve stimulation (HNS) has become a promising treatment option for patients with OSAS. We aimed to analyse the influence of HNS therapy on the cellular characteristics relevant for adhesion and immune regulation of circulating CD14/CD16 monocyte subsets. Whole blood flow cytometric measurements were performed to analyse the expression levels of different adhesion molecules and checkpoint molecule PD-L1 (programmed death-ligand 1) in connection with pro-inflammatory plasma cytokine IL-8 and the clinical values of BMI (body mass index), AHI (apnea-hypopnea index), ODI (oxygen desaturation index), and ESS (Epworth sleepiness scale) upon HNS treatment. Hypoglossal nerve stimulation treatment significantly improved the expression of adhesion molecule CD162 (P-selectin receptor) on non-classical monocytes and significantly downregulated the expression of PD-L1 on all three monocyte subsets. We conclude that the holistic improvement of different parameters such as the oxygenation of the peripheral blood, a reduced systemic inflammation, and the individual sleeping situation upon HNS respiratory support, leads to an improved immunologic situation.

Monocyte alteration in elderly hip fracture healing: monocyte promising role in bone regeneration.

Individual aged with various change in cell and cellular microenvironments and the skeletal system undergoes physiological changes that affect the process of bone fracture healing. These changes are accompanied by alterations in regulating critical genes involved in this healing process. Unfortunately, the elderly are particularly susceptible to hip bone fractures, which pose a significant burden associated with higher morbidity and mortality rates. A notable change in older adults is the increased expression of activation, adhesion, and migration markers in circulating monocytes. However, there is a decrease in the expression of co-inhibitory molecules. Recently, research evidence has shown that the migration of specific monocyte subsets to the site of hip fracture plays a crucial role in bone resorption and remodeling, especially concerning age-related factors. In this review, we summarize the current knowledge about uniqueness characteristics of monocytes, and their potential regulation and moderation to enhance the healing process of hip fractures. This breakthrough could significantly contribute to the comprehension of aging process at a fundamental aging mechanism through this initiative would represent a crucial stride for diagnosing and treating age related hip fracture.

Alterations of blood monocyte subset distribution and surface phenotype are linked to infection severity in COVID-19 inpatients.

Severe coronavirus disease 19 (COVID-19) manifests with systemic immediate proinflammatory innate immune activation and altered iron turnover. Iron homeostasis, differentiation, and function of myeloid leukocytes are interconnected. Therefore, we characterized the cellularity, surface marker expression, and iron transporter phenotype of neutrophils and monocyte subsets in COVID-19 patients within 72 h from hospital admission, and analyzed how these parameters relate to infection severity. Between March and November 2020, blood leukocyte samples from hospitalized COVID-19 patients (n = 48) and healthy individuals (n = 7) were analyzed by flow cytometry enabling comparative analysis of 40 features. Inflammation-driven neutrophil expansion, depletion of CD16+ nonclassical monocytes, and changes in surface expression of neutrophil and monocyte CD64 and CD86 were associated with COVID-19 severity. By unsupervised self-organizing map clustering, four patterns of innate myeloid response were identified and linked to varying levels of systemic inflammation, altered cellular iron trafficking and the severity of disease. These alterations of the myeloid leukocyte compartment during acute COVID-19 may be hallmarks of inefficient viral control and immune hyperactivation and may help at risk prediction and treatment optimization.

Variation in the Dopamine-4-Receptor Gene in Patients with Type 1 Diabetes.

INTRODUCTION: Because dopaminergic signaling pathways are one of the regulators of autoimmunity, we hypothesize that the -521C>T DRD4 gene polymorphism may associate with the risk of diabetes mellitus type 1 (DM1) and its comorbidities. METHODS: In this case-control study, we have examined 300 patients with DM1 in comparison to 300 healthy age-matched controls. Utilizing the amplification refractory mutation system-polymerase chain reaction method, we have analyzed the -521C>T polymorphism of dopamine D4 receptor-encoding gene. Obtained results have been evaluated according to diabetes comorbidities, inflammatory markers, CD14++CD16-, and CD14+CD16+ monocyte subsets as well as lipid profile. RESULTS: The key results of our study are as follows: (1) CC genotype and C allele are associated with a reduced risk of DM1 development (OR = 0.593, p = 0.005 and OR = 0.725, p = 0.003, respectively), whereas TT genotype and T allele are associated with a higher risk of DM1 (OR = 1.408, p = 0.04 and OR = 1.380, p = 0.003, respectively); (2) CC genotype is associated with an increased risk of dyslipidemia and retinopathy in diabetic patients (OR = 2.376, p = 0.001 and OR = 2.111, p = 0.01, respectively); (3) CC genotype and C allele carriers had the highest frequency of pro-inflammatory CD16+ monocytes (p = 2*10-4 and 0.04, respectively); (4) the DRD4 -521C>T polymorphism modifies the inflammatory status as well as lipid profile in DM1 patients. CONCLUSION: Our data imply that the dopaminergic signaling pathways may play an important role in the etiology of DM1 as well as its comorbidities and will provide a new insight into the DM1 risk management. The -521C>T DRD4 gene polymorphism could be considered a genetic marker to predict susceptibility to DM1 as well as retinopathy and dyslipidemia progress in patients with already established disease.

Comparative analyses of monocyte memory dynamics from mice to humans.

BACKGROUND: Innate monocytes can adopt dynamic "memory" states ranging from low-grade inflammation to pathogenic exhaustion, dependent upon signal strength and history of challenges. Low-grade inflammatory monocytes facilitate the pathogenesis of chronic inflammatory diseases, while exhausted monocytes drive the pathogenesis of severe sepsis. Although clinical and basic studies suggest the conservation of key features of exhausted monocytes from human and murine sepsis, systems analyses of monocyte exhaustion among human and murine monocytes are lacking. METHODS: We performed cross examination of septic monocytes scRNAseq data recently collected from human sepsis patients as well as experimental septic mice, in reference to monocytes experimentally exhausted in vitro. Furthermore, we performed pseudo-time analyses of in vitro programmed monocytes following prolonged challenges causing either low-grade inflammation or exhaustion. Additional comparative analyses of low-grade inflammatory monocytes were performed with scRNAseq data from selected human patients with chronic low-grade inflammatory diseases. RESULTS: Our systems analyses reveal key features of monocyte exhaustion including reduced differentiation, pathogenic inflammation and immune suppression that are highly conserved in human and murine septic monocytes, and captured by in vitro experimental exhaustion. Pseudo-time analyses reveal that monocytes initially transition into a less-differentiated state with proliferative potential. The expansion of proliferative monocytes can be observed not only in experimentally challenged monocytes, but also in tissues of murine sepsis and human septic blood. We observed that monocytes similarly transition into the less-differentiated state when challenged with a subclinical dose endotoxin under chronic inflammatory conditions. Instead of being exhausted, monocytes with prolonged challenges with super-low dose endotoxin bifurcate into the low-grade inflammatory immune-enhancing or the chemotactic/adhesive state, often see in atherosclerosis or auto-immune diseases. CONCLUSIONS: Key features of monocyte memory dynamics are identified and conserved in human and murine monocytes, which can be captured by prolonged challenges of innate signals with varying signal strength.

Transcriptional characteristics and functional validation of three monocyte subsets during aging.

BACKGROUND: Age-associated changes in immunity are inextricably linked to chronic inflammation and age-related diseases, the impact of aging on monocyte subsets is poorly understood. METHODS: Flow cytometry was applied to distinguish three monocyte subsets between 120 young and 103 aged individuals. We then analyzed the expression profiles of three monocyte subsets from 9 young and 9 older donors and CD14+ monocytes from 1202 individuals between 44 and 83 years old. Flow cytometry was used to measure ß-galactosidase activities, ROS levels, mitochondrial contents, mitochondrial membrane potentials (MMPs) and intracellular IL-6 levels in three monocyte subsets of young and elderly individuals, and plasma IL-6 levels were detected by electrochemiluminescence immunoassay. Mitochondrial stress and glycolytic rate of CD14+ monocytes from young and aged individuals were measured by Seahorse XFe24 Analyzer. RESULTS: Compared with young individuals, the percentage of classical subset in aged persons significantly decreased, while the proportion of nonclassical subset increased. Age-related differential genes were obviously enriched in cellular senescence, ROS, oxidative phosphorylation, mitochondrial respiratory chain, IL-6 and ribosome-related pathways. Compared with young individuals, the ß-galactosidase activities, ROS contents, intracellular IL-6 levels of three monocyte subsets, and plasma IL-6 levels in aged individuals were significantly elevated, while the MMPs apparently declined with age and the mitochondrial contents were only increased in intermediate and nonclassical subsets. CD14+ monocytes from elderly adults had conspicuously lower basal and spare respiratory capacity and higher basal glycolysis than those from young individuals. CONCLUSIONS: During aging, monocytes exhibited senescence-associated secretory phenotype, mitochondrial dysfunction, decreased oxidative phosphorylation and increased glycolysis and the nonclassical subset displayed the clearest features of aging. Our study comprehensively investigated age-related transcriptional alterations of three monocyte subsets and identified the pivotal pathways of monocyte senescence, which may have significant implications for tactics to alleviate age-related conditions.

Genetic landscape and autoimmunity of monocytes in developing Vogt-Koyanagi-Harada disease.

Vogt-Koyanagi-Harada (VKH) disease is a systemic autoimmune disorder affecting multiple organs, including eyes, skin, and central nervous system. It is known that monocytes significantly contribute to the development of autoimmune disease. However, the subset heterogeneity with unique functions and signatures in human circulating monocytes and the identity of disease-specific monocytic populations remain largely unknown. Here, we employed an advanced single-cell RNA sequencing technology to systematically analyze 11,259 human circulating monocytes and genetically defined their subpopulations. We constructed a precise atlas of human blood monocytes, identified six subpopulations-including S100A12, HLA, CD16, proinflammatory, megakaryocyte-like, and NK-like monocyte subsets-and uncovered two previously unidentified subsets: HLA and megakaryocyte-like monocyte subsets. Relative to healthy individuals, cellular composition, gene expression signatures, and activation states were markedly alternated in VKH patients utilizing cell type-specific programs, especially the CD16 and proinflammatory monocyte subpopulations. Notably, we discovered a disease-relevant subgroup, proinflammatory monocytes, which showed a discriminative gene expression signature indicative of inflammation, antiviral activity, and pathologic activation, and converted into a pathologic activation state implicating the active inflammation during VKH disease. Additionally, we found the cell type-specific transcriptional signature of proinflammatory monocytes, ISG15, whose production might reflect the treatment response. Taken together, in this study, we present discoveries on accurate classification, molecular markers, and signaling pathways for VKH disease-associated monocytes. Therapeutically targeting this proinflammatory monocyte subpopulation would provide an attractive approach for treating VKH, as well as other autoimmune diseases.

Peripheral blood monocyte status is a predictor for judging occurrence and development on sepsis in older adult population: a case control study.

BACKGROUND: Peripheral blood monocytes are important immune modulatory cells that change during aging. Previous studies on sepsis and monocytes did not distinguish between age groups, especially in the older adult population. The mechanisms of monocyte subsets and function are not well-understood in the aging context with sepsis. METHODS: Monocyte subsets were measured using flow cytometry in 80 sepsis patients and 40 healthy controls. Plasma cytokine levels were measured using cytokine antibody arrays. RESULTS: The percentage of MO3 (CD14 + CD16 + +)/monocytes was higher in sepsis patients than in controls (P = 0.011), whereas the percentage of MO1 (CD14 + + CD16 -)/monocytes was higher in septic shock patients and 28-day death group than in those without shock and 28-day survival group (P = 0.034, 0.038). Logistic regression analysis showed that the percentage of MO3/monocytes (OR = 1.120, P = 0.046) and plasma level of monocyte chemoattractant protein (MCP)-1 (OR = 1.006, P = 0.023) were independently associated with the occurrence of sepsis, whereas the percentage of MO1/monocytes (OR = 1.255, P = 0.048) was independently associated with septic shock. The receiver operating characteristic (ROC) curve showed that the area under the curve (AUC) of MO3/monocyte percentage in combination with MCP-1 plasma level (AUC = 0.799) for predicting sepsis was higher than that of each parameter alone (P < 0.001). The AUC of MO1/monocyte percentage with the value 0.706 (P = 0.003) was lower than the AUC of SOFA (sequential organ failure assessment) score with the value 0.966 (P < 0.001) for predicting septic shock, but the value of the two AUCs were similar for predicting 28-day mortality (AUC = 0.705, 0.827; P = 0.020, P < 0.001). The AUC of MO1/monocytes percentage in combination with SOFA score for predicting 28-day mortality was higher than that of each parameter alone (AUC = 0.867, P < 0.001). Using a cut-off of 58.5% (for MO1/monocytes determined by ROC) could discriminate between survivors and non-survivors on Kaplan-Meier curves for 28-day mortality with a positive predictive value of 77.4%. CONCLUSION: The MO3/monocyte percentage and plasma MCP-1 level were independent predictors of sepsis occurrence, whereas the percentage of MO1/monocytes was an independent predictor of prognosis in the Chinese Han older adult population. TRIAL REGISTRATION: Registration number: ChiCTR2200061490, date of registration: 2022-6-26 (retrospectively registered).

Monocyte Differentiation and Heterogeneity: Inter-Subset and Interindividual Differences.

The three subsets of human monocytes, classical, intermediate, and nonclassical, show phenotypic heterogeneity, particularly in their expression of CD14 and CD16. This has enabled researchers to delve into the functions of each subset in the steady state as well as in disease. Studies have revealed that monocyte heterogeneity is multi-dimensional. In addition, that their phenotype and function differ between subsets is well established. However, it is becoming evident that heterogeneity also exists within each subset, between health and disease (current or past) states, and even between individuals. This realisation casts long shadows, impacting how we identify and classify the subsets, the functions we assign to them, and how they are examined for alterations in disease. Perhaps the most fascinating is evidence that, even in relative health, interindividual differences in monocyte subsets exist. It is proposed that the individual's microenvironment could cause long-lasting or irreversible changes to monocyte precursors that echo to monocytes and through to their derived macrophages. Here, we will discuss the types of heterogeneity recognised in monocytes, the implications of these for monocyte research, and most importantly, the relevance of this heterogeneity for health and disease.

Imbalanced Inflammatory Responses in Preterm and Term Cord Blood Monocytes and Expansion of the CD14+CD16+ Subset upon Toll-like Receptor Stimulation.

Developmentally regulated features of innate immunity are thought to place preterm and term infants at risk of infection and inflammation-related morbidity. Underlying mechanisms are incompletely understood. Differences in monocyte function including toll-like receptor (TLR) expression and signaling have been discussed. Some studies point to generally impaired TLR signaling, others to differences in individual pathways. In the present study, we assessed mRNA and protein expression of pro- and anti-inflammatory cytokines in preterm and term cord blood (CB) monocytes compared with adult controls stimulated ex vivo with Pam3CSK4, zymosan, polyinosinic:polycytidylic acid, lipopolysaccharide, flagellin, and CpG oligonucleotide, which activate the TLR1/2, TLR2/6, TLR3, TLR4, TLR5, and TLR9 pathways, respectively. In parallel, frequencies of monocyte subsets, stimulus-driven TLR expression, and phosphorylation of TLR-associated signaling molecules were analyzed. Independent of stimulus, pro-inflammatory responses of term CB monocytes equaled adult controls. The same held true for preterm CB monocytes-except for lower IL-1ß levels. In contrast, CB monocytes released lower amounts of anti-inflammatory IL-10 and IL-1ra, resulting in higher ratios of pro-inflammatory to anti-inflammatory cytokines. Phosphorylation of p65, p38, and ERK1/2 correlated with adult controls. However, stimulated CB samples stood out with higher frequencies of intermediate monocytes (CD14+CD16+). Both pro-inflammatory net effect and expansion of the intermediate subset were most pronounced upon stimulation with Pam3CSK4 (TLR1/2), zymosan (TR2/6), and lipopolysaccharide (TLR4). Our data demonstrate robust pro-inflammatory and yet attenuated anti-inflammatory responses in preterm and term CB monocytes, along with imbalanced cytokine ratios. Intermediate monocytes, a subset ascribed pro-inflammatory features, might participate in this inflammatory state.

Monocytes in central nervous system remyelination.

Remyelination failure with aging and progression of neurodegenerative disorders contributes to axonal dysfunction, highlighting the importance of understanding the mechanisms underpinning this process to develop regenerative therapies. Central nervous system (CNS) macrophages, encompassing both resident microglia and blood monocyte-derived cells, play a crucial role in driving successful remyelination. Although there has been a focus on the critical roles of microglia in remyelination, the specific contribution of monocyte-derived macrophages is still not fully understood. Until recently, the lack of tools enabling distinction between CNS macrophage populations has hindered our understanding of monocyte influence on remyelination. Recent advances have allowed for identification and characterization of monocyte populations in health, aging and in neurodegenerative conditions like multiple sclerosis, indicating heterogeneity of monocyte subsets impacted by both intrinsic and extrinsic factors. Here, we discuss the new tools enabling distinction between macrophage populations and advancements in understanding the importance of monocytes in remyelination, and reflect on the potential for therapeutic targeting of monocytes to promote remyelination.

The CD14++CD16+ monocyte subset is expanded and controls Th1 cell development in Graves' disease.

Three different subsets of circulating human monocytes, CD14++CD16- (classical), CD14++CD16+ (intermediate), and CD14+CD16+ (non-classical) monocytes, have been recently identified. New evidence suggests that levels of intermediate monocytes or CD16+ (intermediate and non-classical) monocytes are increased in autoimmune diseases. However, studies regarding the role of each monocyte subset in the pathogenesis of Graves' disease (GD) are lacking. We aimed to investigate the clinical implications of these subsets and their potential role in GD pathogenesis. CD14++CD16+ monocytes showed a more activated state in GD patients than other monocyte subpopulations. An increased proportion of circulating CD14++CD16+ monocytes and a decreased proportion of circulating CD14++CD16- monocytes in GD patients were detected, and CD14++CD16+ monocyte frequencies were positively correlated with GD clinical parameters. Additionally, a follow-up analysis indicated that the CD14++CD16- monocyte percentage increased and the CD14++CD16+ monocyte percentage decreased post-treatment. We found that CD14++CD16+ GD monocytes promoted the expansion of IFN-γ+CD4+ cells. The Th1-polarizing cytokine IL-12, secreted after direct contact with patient CD14++CD16+ monocytes and CD4+ T cells, was responsible for IFN-γ+CD4+ cell development. Our results suggest that CD14++CD16+ monocytes are involved in GD pathogenesis and the critical role of CD14++CD16+ monocytes in the generation of potentially pathogenic Th responses in GD.

Quantitative and Functional Assessment of the Influence of Routinely Used Cryopreservation Media on Mononuclear Leukocytes for Medical Research.

Quantitative and functional analysis of mononuclear leukocyte populations is an invaluable tool to understand the role of the immune system in the pathogenesis of a disease. Cryopreservation of mononuclear cells (MNCs) is routinely used to guarantee similar experimental conditions. Immune cells react differently to cryopreservation, and populations and functions of immune cells change during the process of freeze-thawing. To allow for a setup that preserves cell number and function optimally, we tested four different cryopreservation media. MNCs from 15 human individuals were analyzed. Before freezing and after thawing, the distribution of leukocytes was quantified by flow cytometry. Cultured cells were stimulated using lipopolysaccharide, and their immune response was quantified by flow cytometry, quantitative polymerase chain reaction (qPCR), and enzyme-linked immunosorbent assay (ELISA). Ultimately, the performance of the cryopreservation media was ranked. Cell recovery and viability were different between the media. Cryopreservation led to changes in the relative number of monocytes, T cells, B cells, and their subsets. The inflammatory response of MNCs was altered by cryopreservation, enhancing the basal production of inflammatory cytokines. Different cryopreservation media induce biases, which needs to be considered when designing a study relying on cryopreservation. Here, we provide an overview of four different cryopreservation media for choosing the optimal medium for a specific task.

Circulating Monocyte Subsets and Transcatheter Aortic Valve Replacement.

Transcatheter aortic valve replacement (TAVR), as an alternative to open heart surgery, has revolutionized the treatment of severe aortic valve stenosis (AVS), the most common valvular disorder in the elderly. AVS is now considered a form of atherosclerosis and, like the latter, partly of inflammatory origin. Patients with high-grade AVS have a highly disturbed blood flow associated with high levels of shear stress. The immediate reopening of the valve during TAVR leads to a sudden restoration of a normal blood flow hemodynamic. Despite its good prognosis for patients, TAVR remains associated with bleeding or thrombotic postprocedural complications, involving mechanisms that are still poorly understood. Many studies report the close link between blood coagulation and inflammation, termed thromboinflammation, including monocytes as a major actor. The TAVR procedure represents a unique opportunity to study the influence of shear stress on human monocytes, key mediators of inflammation and hemostasis processes. The purpose of this study was to conduct a review of the literature to provide a comprehensive overview of the impact of TAVR on monocyte phenotype and subset repartition and the association of these parameters with the clinical outcomes of patients with severe AVS who underwent TAVR.

Aberrant monocyte subsets in patients with Behçet's disease.

Monocytes are a versatile and dynamic population, but its implication in Behçet's Disease (BD) remains elusive. We investigated the proportion, phenotypical and functional alterations in classical monocytes (CM), intermediate monocytes (IM) and non-classical monocytes (NCM) subsets in BD. A higher IM and lower NCM population in BD patients were noted, closely correlated with disease activity, and rescued after treatment. CD11b and CD64 expression on CM, IM and NCM in BD were enhanced. BD CM promoted TNF-a and IL-6 production and facilitated Th1 differentiation. BD IM promoted IL-6 production. We further demonstrated a higher level of phosphorylated p65 (p-p65) in BD CM and increased p-p65 and p-p38 in BD IM. Our data highlighted the aberrant populations of IM and CM in BD, potentially implicated in BD' pathogenesis.

Immunological features of circulating monocyte subsets in patients with squamous cell carcinoma of the head and neck.

BACKGROUND: Circulating monocytes are classified into three subsets according to their CD14 and CD16 expressions. Here we investigated all three subsets in patients with squamous cell carcinoma of the head and neck (SCCHN). METHODS: Peripheral blood from 54 patients with SCCHN and 24 healthy donors (HDs) was tested for flowcytometry. Immunohistochemical staining of the primary tumor was performed. SCCHN cells were co-cultured with human monocytes in vitro. RESULTS: The level of intermediate monocytes was significantly lower in SCCHN than in HDs. The expression levels of HLA-G, PD-L1, and CD51 on intermediate monocytes was evidently greater in patients with SCCHN. In vitro co-culturing of SCCHN cells with monocytes revealed a significant increase in CD51 expression levels on monocytes. The decrease in expression levels of the maturation markers CX3CR1 and CD68 was significantly correlated to poor clinical outcomes. CONCLUSION: The level of intermediate monocytes was decreased in cancer patients in favor of immature and expressed immunosuppressive molecules.

Glucocorticoid treatment in patients with newly diagnosed immune thrombocytopenia switches CD14++ CD16+ intermediate monocytes from a pro-inflammatory to an anti-inflammatory phenotype.

Immune thrombocytopenia (ITP) is thought to result from an aberrant adaptive autoimmune response, involving autoantibodies, B and T lymphocytes, directed at platelets and megakaryocytes. Previous reports have demonstrated skewed CD4+ T-helper subset distribution and enhanced production of pro-inflammatory cytokines such as interleukin 17A and interferon gamma. The role of monocytes (MCs) in ITP is less widely described, but innate immune cells have a role in shaping CD4+ T-cell phenotypes. Glucocorticoids (GCs) are commonly used for first-line ITP treatment and modulate a broad range of immune cells including T cells and MCs. Using multiparameter flow cytometry analysis, we demonstrate the expansion of intermediate MCs (CD14++ CD16+ ) in untreated patients with newly diagnosed ITP, with these cells displaying a pro-inflammatory phenotype, characterised by enhanced expression of CD64 and CD80. After 2 weeks of prednisolone treatment (1 mg/kg daily), the proportion of intermediate MCs reduced, with enhanced expression of the anti-inflammatory markers CD206 and CD163. Healthy control MCs were distinctly different than MCs from patients with ITP before and after GC treatment. Furthermore, the GC-induced phenotype was not observed in patients with chronic ITP receiving thrombopoietin receptor agonists. These data suggest a role of MCs in ITP pathogenesis and clinical response to GC therapy.

Bacterial species-specific modulatory effects on phenotype and function of camel blood leukocytes.

BACKGROUND: Recent studies have reported pathogen-species-specific modulating effects on the innate immune system. Escherichia coli, Staphylococcus aureus, and Streptococcus agalactiae are important pathogenic bacteria responsible for different infectious diseases in several animal species. In the present study, a whole blood culture with S. aureus, E. coli, or S. agalactiae and flow cytometry were used to investigate, whether stimulation with different bacterial species induces different immunomodulation patterns in camel leukocytes. The expression of different cell surface myeloid markers and cell adhesion molecules on monocytes and neutrophils was investigated. In addition, the capacity of monocytes and neutrophils to produce reactive oxygen species (ROS) was analyzed. RESULTS: Stimulation with either of the bacterial species resulted in the expansion of the camel CD14highMHCIIhigh monocyte subset with a reduced fraction of CD14highMHCIIlow monocytes. For the CD14lowMHCIIhigh monocytes, however, only stimulation with S. aureus or S. agalactiae increased their fractions in blood. Although all bacterial species elicited the upregulation of cell surface MHC class II molecules on granulocytes, the increase was, however, highest on cells stimulated with S. aureus. The expression levels of the two adhesion molecules, CD11a and CD18, on neutrophils and monocytes were differently affected by bacterial stimulation. Functionally, E. coli failed to stimulate ROS production in monocytes, while induced a strong ROS production response in granulocytes. S. agalactiae elicited a week ROS production in granulocytes when compared to the other two pathogens. CONCLUSIONS: The different responsiveness of monocytes and granulocytes toward different bacterial species indicates different host-pathogen interaction mechanisms for the two cell populations. In addition, the phenotypic and functional differences between cells stimulated with E. coli, S. aureus, or S. agalactiae suggests pathogen-species-specific modulating effects of the bacterial pathogens on the camel innate myeloid cells.