Peripheral Blood Monocyte Populations Research Articles

Diagnostic and Prognostic Value of Monocyte Distribution Width in Sepsis.

Monocyte distribution width (MDW) is a blood monocyte morphological parameter that can be easily detected by an automated hemocyte analyzer and can provide clinicians with important information about cell volume variability in peripheral blood monocyte populations. The United States’ Food and Drug Administration and Conformite Europeenne have both been cleared for their clinical application in the detection of sepsis and developing sepsis in adult patients in the emergency department (ED). Recently, MDW has been found to have an early diagnosis and predictive value for sepsis in neonates and COVID-19 patients. Here, we summarize the findings of the studies investigating the clinical application of MDW in sepsis. Under different stimuli, especially in infectious diseases, the activation of innate immunity is the host’s first defense mechanism, and the change in monocyte volume is considered an early indicator reflecting the state of activation of innate immunity. Pivotal study data from a large multicenter patient cohort showed that abnormal MDW at presentation increases the odds of sepsis, considering the combination of MDW and White Blood Cell Count (WBC) as part of a standard sepsis assessment protocol for ED, which may increase the sensitivity and specificity of sepsis diagnosis. Meanwhile, MDW shares a diagnostic performance comparable to that of conventional biomarkers (C-reactive protein and procalcitonin) in sepsis. In addition, some evidence suggests that increased MDW, both in adults and neonates, may be associated with unfavorable short- and long-term outcomes, which indicates its prognostic value in sepsis. Taken together, MDW is a parameter of increased morphological variability of monocytes in response to infection, and numerous studies have shown that MDW could be used as a valuable diagnostic and prognostic index in patients with sepsis or suspected sepsis.

Impact of high-fat overfeeding on white adipose tissue and systemic metabolic and inflammatory responses

AbstractWhite adipose tissue (WAT) inflammation is linked to the development of cardiometabolic disease. A high intake of saturated fatty acids (SFA) may promote a more pro-inflammatory WAT gene expression profile, compared to monounsaturated fatty acids(1,2). This is concerning as the UK adult population currently exceeds the SFA intake target of < 10% total energy (TE), at 11.9%TE(3). However, further research is needed to understand how SFA ingestion impacts the protein content and phosphorylation of key targets involved in WAT inflammatory signalling. Therefore, this study investigated the effect of short-term, high-fat overfeeding on WAT and systemic metabolic and inflammatory responses in healthy, non-obese individuals.Fifteen (9 men, 6 women) apparently healthy participants (mean (SE) age; 26.6 (1.2) y, BMI; 24.4 (0.6) kg/m2) consumed a high-fat (dietary target: 65.0%TE total fat; 32.5%TE SFA), high-calorie (+ 50% estimated energy requirements) diet for 7 days. Fasted venous blood and WAT samples were collected pre- and post-intervention.Body mass increased following the intervention (pre-intervention vs. post-intervention: 75.2 (2.9) kg vs. 76.4 (2.9) kg; P < 0.0001). The intervention also led to increases in glucose (4.4 (0.1) vs. 4.6 (0.1) mmol/L; P = 0.022) and lipopolysaccharide-binding protein (12.9 (1.3) vs. 17.7 (3.0) μg/mL; P = 0.038), and a decrease in triacylglycerol (0.91 (0.08) vs. 0.72 (0.05) mmol/L; P = 0.007). Insulin, IL-6 and soluble CD14 concentrations remained unchanged (all P > 0.05). At the WAT level, total protein (TLR4; NF-κB; IKβα; P38; MCP-1) and phosphorylation (p) of proteins (p-NF-κB; p-IKβα; p-P38) involved in inflammatory signalling were unchanged following the intervention (all P > 0.05).In conclusion, although short-term, high-fat overfeeding led to an increase in body mass as well as systemic metabolic alterations, the content and phosphorylation of proteins involved in WAT inflammatory signalling were unaltered in healthy, non-obese individuals. Further analysis will reveal the impact of high-fat overfeeding on peripheral blood monocyte populations, which are involved in mediating pro- and anti-inflammatory responses.This research was supported by a Society for Endocrinology Early Career Grant.

Increased CD14+ and decreased CD14- populations of monocytes 48h after zolendronic acid infusion in breast cancer patients.

The aim of this study is to examine the effect of zolendronic acid administration in the peripheral blood white cell population, seeking a plausible pathophysiological link between bisphosphonates and osteonecrosis of the jaw. Twenty-four breast cancer patients, under zolendronic acid treatment for bone metastasis, were included. Peripheral blood samples were obtained prior to and 48h following zolendronic acid administration. Flow cytometry gated at leukocyte, monocyte, and the granulocyte populations for the CD4/CD8/CD3, CD3/CD16+56/CD45/CD19, CD14/CD123, and CD14/23 stainings were performed. We were able to record a number of changes in the white cell populations after 48h of zolendronic acid administration. Most importantly, in the monocyte populations, we were able to detect statistically significant increased populations of CD14+/CD23+ (p=0.038), CD14+/CD23- (p=0.028), CD14+/CD123+ (p=0.070, trend), and CD14+/CD123- (p=0.043). In contrast, statistically significant decreased populations of CD14-/CD23+ (p=0.037) and CD14-/CD123+ (p=0.003) were detected. Our results provide evidence supporting the hypothesis that bisphosphonate administration modifies the monocyte-mediated immune response. An increase of CD14+ peripheral blood monocyte (PBMC) populations along with a decrease of CD14- PBMC populations has been recorded. The latter finding is in accordance with limited-currently existing-evidence and warrants further elucidation.

QUANTIFICATION AND PHENOTYPIC CHARACTERIZATION OF MONOCYTES SUBSETS IN HUMAN ATHEROSCLEROSIS

QUANTIFICATION AND PHENOTYPIC CHARACTERIZATION OF MONOCYTES SUBSETS IN HUMAN ATHEROSCLEROSIS

Diversity of Denizens of the Atherosclerotic Plaque

The atherosclerotic plaque typically harbors cells of several lineages whose conversations, mediated by extracellular or cell surface–associated messengers, influence decisively the biology and clinical consequences of the lesion. Early vascular biology studies defined the resting state of the endothelium, characterized by the elaboration of antithrombotic and vasodilatory mediators. The activated endothelium recruits inflammatory leukocytes, favors clot accumulation, participates in angiogenesis, and can influence the behavior of subjacent smooth muscle cells in ways that favor atherogenesis and vasoconstriction (Figure). More recently, we have come to appreciate that the endothelial cell not only can exhibit a spectrum of functions, but that some may arise postnatally from bone marrow–derived precursors.1 Thus, the heterogeneity of endothelial cells depends not only on the mutability of their function but also on their origin. The diversity of endothelium depends not only on lineage but also location, with increasingly well-understood differences between arterial, microvascular, and venous endothelial cells. Figure. Heterogeneity of major cell types in atherosclerotic plaques. Vascular biologists have long recognized heterogeneity of endothelial cells and smooth muscle cells, now understood to result from local mediator milieu, biomechanical stimuli, and different embryological origins. Indeed, recent data suggest that both of these intrinsic vascular cell types can arise in postnatal life from bone marrow–derived precursors. Immunological dogma recognizes several T-cell populations, exemplified here by the Th1 and Th2 subsets, which on the balance exert opposing influences on atherogenesis. New data now establish the relevance to atherosclerosis and hyperlipidemia of monocyte heterogeneity. Monocytes that bear high levels of the markers Ly6c/Gr-1 and P-selectin glycoprotein ligand exhibit more proinflammatory functions than their …

Monocyte accumulation in mouse atherogenesis is progressive and proportional to extent of disease

Monocytes participate importantly in the pathogenesis of atherosclerosis, but their spatial and temporal recruitment from circulation remains uncertain. This study tests the hypothesis that monocyte accumulation in atheroma correlates with the extent of disease by using a sensitive and simple quantitative assay that allows tracking of highly enriched populations of blood monocytes. A two-step isolation method yielded viable and functionally intact highly enriched peripheral blood monocyte populations (>90%). Recipient mice received syngeneic monocytes labeled in two ways: by transgenically expressing EGFP or with a radioactive tracer [(111)In]oxine. After 5 days, more labeled cells accumulated in the aorta, principally the aortic root and ascending aorta, of 10-wk-old ApoE(-/-) compared with 10-wk-old C57BL/6 mice (223 +/- 3 vs. 87 +/- 22 cells per aorta). Considerably more monocytes accumulated in 20-wk-old ApoE(-/-) mice on either chow (314 +/- 41 cells) or high-cholesterol diet (395 +/- 53 cells). Fifty-week-old ApoE(-/-) mice accumulated even more monocytes in the aortic root, ascending aorta, and thoracic aorta after both chow (503 +/- 67 cells) or high-cholesterol diet (648 +/- 81 cells). Labeled monocyte content in the aorta consistently correlated with lesion surface area. These data indicate that monocytes accumulate continuously during atheroma formation, accumulation increases in proportion to lesion size, and recruitment is augmented with hypercholesterolemia. These results provide insights into mechanisms of atherogenesis and have implications for the duration of therapies directed at leukocyte recruitment.

Identification of a novel surface molecule, RM3/1, that contributes to the adhesion of glucocorticoid-induced human monocytes to endothelial cells.

The functions of different populations of peripheral blood monocytes in the course of an inflammatory reaction are presently not fully understood. In particular, the mechanisms for their specific recruitment to an inflammatory site are not yet known. We investigated a dexamethasone (Dex)-inducible monocyte subtype and its adhesion to either unstimulated or lipopolysaccharide (LPS)- or interferon (IFN)-gamma-stimulated human umbilical vein endothelial cells (HUVEC). The Dex-induced monocytes were characterized by the expression of the surface glycoprotein RM3/1. It was found that pretreatment of monocytes with Dex increased their adhesion to unstimulated and stimulated HUVEC. This increase in adhesion was paralleled by the expression of the RM3/1 surface molecule. Treatment with cyclosporin A (CsA) caused a down-regulation of the RM3/1 density per cell by 67% and also decreased adhesion to HUVEC. In contrast, the expression of other adhesion molecules remained unaffected by Dex or CsA treatment. Treatment of Dex-induced monocytes with antibodies against RM3/1, CD11a, CD11b, CD11c, CD14 and CD18 resulted in suppression of adhesion to stimulated HUVEC by 46%, 18%, 17%, 12%, 25% and 15%, respectively. Antibodies to the known adhesion molecules on endothelial cells (vascular cell adhesion molecule-1, E-selectin) did not block adhesion of Dex-induced monocytes. However, the combination of antibodies to RM3/1 and CD14 inhibited adhesion to LPS-stimulated HUVEC by 74%. These effects were also seen on IFN-gamma-stimulated HUVEC, where adhesion of Dex-induced monocytes was blocked with antibodies to RM3/1 + CD14 by 63%. From this, it is concluded that the RM3/1-molecule is a novel surface molecule that contributes to the adhesion of cortisone-induced monocytes to LPS or cytokine-stimulated endothelial cells.

Heterogeneity of peripheral blood monocyte populations in human immunodeficiency virus-1 seropositive patients.

Monocytes from human immunodeficiency virus (HIV) patients have an increased heterogeneity of phenotype and function. In a study of 120 HIV patients we have demonstrated that they have normal monocyte differential counts but that with progression of the disease an increasing proportion of monocytes show phenotypic and functional evidence for activation or maturation. A proportion of the monocytes are larger, with increased expression of CD11b, HLA-DR, CD45 and CD16. Concomitantly there was increased expression of TNF-alpha, high constitutive synthesis of PGE2 and high plasma IL-6 levels. This suggested that there exists a more dynamic situation of recruitment, activation and maturation of peripheral blood monocytes driven by HIV infection which results in a broader phenotypic profile.

Heterogeneity of peripheral blood monocyte populations in human immunodeficiency virus-1 seropositive patients

Monocytes from human immunodeficiency virus (HIV) patients have an increased heterogeneity of phenotype and function. In a study of 120 HIV patients we have demonstrated that they have normal monocyte differential counts but that with progression of the disease an increasing proportion of monocytes show phenotypic and functional evidence for activation or maturation. A proportion of the monocytes are larger, with increased expression of CD11b, HLA-DR, CD45 and CD16. Concomitantly there was increased expression of TNF-α, high constitutive synthesis of PGE2 and high plasma IL-6 levels. This suggested that there exist a more dynamic situation of recuitment, activation and maturation of peripheral blood monocytes driven by HIV infection which results in a broader phenotypic profile.

Production of Tumor Necrosis Factor-α by Blood and Lung Mononuclear Phagocytes from Patients with Human Immunodeficiency Virus-related Lung Disease

Tumor necrosis factor-alpha (TNF) is a cytokine involved in the pathogenesis of shock and in granuloma formation, tissue necrosis, and fibrosis, in many organ systems, including the lung. It has been suggested that cells from patients infected by the human immunodeficiency virus (HIV + ve) are primed for TNF release. We postulated that TNF release from the alveolar macrophages (AM) of such patients with lung disease might lead to their observed pulmonary dysfunction. We present data confirming that peripheral blood monocytes (PBM) and demonstrating that AM from HIV + ve patients with pulmonary manifestations show significantly greater TNF production than those from HIV-negative (HIV - ve) subjects. In addition, we found sequentially significant increases in TNF production from AM and PBM of HIV + ve patients with no pathogens detected at bronchoscopy (NB), bacterial pneumonia (BP), and those with Pneumocystis carinii pneumonia (PCP). The overall TNF levels were greater from AM than PBM in all groups other than spontaneous production from HIV - ve subjects. Adherent populations of PBM and AM were incubated for 4 h with lipopolysaccharide (10 micrograms/ml) or control medium alone. Cell-free supernatants were examined for the presence of TNF using an immunoassay. The TNF levels (mean +/- SD) in IU/ml from stimulated PBM of the PCP, BP, NB, and control groups, respectively, were 186 +/- 36, 140 +/- 30, 95 +/- 18, and 55 +/- 10 and the spontaneous levels were 123 +/- 25, 100 +/- 22, 75 +/- 24, and 11 +/- 5.(ABSTRACT TRUNCATED AT 250 WORDS)

Differential Regulation of Tumor Necrosis Factor-alpha in Human Alveolar Macrophages and Peripheral Blood Monocytes: A Cellular and Molecular Analysis

Human tumor necrosis factor-alpha (TNF), a mononuclear phagocyte (MO)-derived peptide, is increasingly being recognized for its pleomorphic immunologic effects. A number of studies have demonstrated that LPS can induce TNF synthesis, but data examining the production and regulation of TNF in human MO populations are lacking. In this study, we present data demonstrating that alveolar macrophages (AMO) and peripheral blood monocytes (PBM) obtained from 10 normal volunteers display a significant difference in both the production of TNF and their susceptibility to TNF regulation by prostaglandin E2 (PGE2) and dexamethasone (Dex). Adherent populations of PBM and AMO were incubated for 18 h in the presence of either LPS (10 micrograms/ml) alone, PGE2 for 1 h prior to LPS challenge, Dex for 1 h prior to LPS challenge, or control media alone. Cell-free supernatants were examined for TNF bioactivity and cellular TNF mRNA was assessed via in situ hybridization and Northern blot analysis. PGE2 and Dex treatment of PBM suppressed LPS-induced TNF production by 78% and 72%, respectively, while AMO-TNF production was suppressed by only 22% and 33%. The accumulation of TNF mRNA in PBM was reduced 63% by PGE2 and 45% by Dex, as assessed by laser densitometry. Similar studies demonstrated that TNF mRNA accumulation in AMO was reduced 12% and 13% by PGE2 and Dex, respectively. A 1,000-fold increase in PGE2 levels was necessary to induce 50% suppression of the maximal response to AMO as compared to PBM. These data support the notion that human MO derived from different compartments or stages of differentiation exhibit differential responsiveness to immunomodulators.

Suppression of blood monocyte and neutrophil chemotaxis in acute human malaria.

The host response to Plasmodia includes the production of enlarged populations of peripheral blood monocytes and tissue macrophages in the spleen and the liver. Since the hyperplasia of the mononuclear phagocyte system is believed to arise as a consequence of an enhanced blood monocyte influx, we tested monocyte chemotactic responsiveness in 19 patients with acute primary attack malaria. In addition, the neutrophil chemotaxis was measured in 12 patients. Before the initiation of antimalarial treatment a significant depression of monocyte chemotaxis was observed in approximately half of the patients when compared with healthy control subjects. The depression was found in Plasmodium falciparum malaria as well as in P. vivax or P. ovale malaria patients. The defective responsiveness was not receptor specific, since the responses towards casein and zymosan activated serum proved to be equally suppressed. The monocyte chemotaxis was followed in 14 of the patients, during treatment and after complete recovery. After 3 days of treatment the response had improved in most of the patients, and after 7 days all patients had a normal monocyte chemotaxis, which remained normal after one month. No significant differences between P. falciparum and P. vivax/ovale malaria was observed with respect to blood monocyte chemotactic responsiveness. Neutrophil chemotaxis in patients with P. falciparum infections was similarly suppressed before treatment (54% of controls), was still defective after 3 days of treatment, and nearly normalized after 7 days (87% of controls). Furthermore, monocyte phagocytic and candidacidal activities were assessed in the same patients on admission and during the follow-up. In contrast to chemotaxis, these functions were normal in all of the patients whenever measured. In conclusion, not all cell functions were altered in concert, and the previously unreported suppression of chemotactic migration might reflect a change in blood leucocyte subpopulations, deactivation in vivo or a direct suppressive effect of plasmodia induced products.

Purification of human monocytes: Isolation and collection of large numbers of peripheral blood monocytes

Monocytes from human peripheral blood were purified by elutriation centrifugation. Up to 1.5 × 10 9 peripheral blood mononuclear cells could be separated in isotonic media to yield 6–8 × 10 8 lymphocytes with 95% purity and 1.5–2.5 × 10 8 monocytes with greater than 90% purity. The temperature at which elutriation was performed determined the purity of the monocyte fraction. Both the lymphocyte and monocyte fractions were characterized by cell sizing and histochemical staining. Most of the myeloperoxidase positive mononuclear cells (monocytes) has a modal volume of 378 μm 3 while 10% were within the modal volume of the lymphocytes, 131 μm 3. Thus, there are two populations of cells with histochemical properties of monocytes which are separable by size. The collection and isolation of human peripheral blood monocyte populations in large numbers will facilitate studies of their functional characteristics.