About 25 per cent of the monocytes were labeled within 1 day and 82 per cent in 8 days. Both labeled and unlabeled monocytes disappeared from the circulation in accordance with an exponential function with a half-time of about 3 days. Mean grain counts increased asymptotically toward a limit reached in 4 or 5 days. The monocyte turnover rate in the rat is in the neighbourhood of 3. It is concluded that monocytes leave the circulation at random and not as a consequence of senescence.
It is probable that they are the product of a cell lineage consisting of about 3 generations from the primitive precursor to the mature form, and that the average generation time is about 24 hours. Because of the rapid appearance of large numbers of labeled cells, it is unlikely that they are derived from lymphocytes which acquire label much more slowly. Sign In or Create an Account. Sign In. Skip Nav Destination Content Menu. Close Abstract. Article Navigation. We then observed early integration of deuterium in classical monocytes, reaching a peak 3 d after labeling Fig.
At these early time points, intermediate monocytes were also labeled with deuterium but at a much lower level than classical monocytes.
No label was observed in nonclassical monocytes until day 7. This chronological acquisition of deuterium by circulating monocyte subsets is most likely to be explained by a sequential ontogeny scenario in which deuterium is incorporated into precursors that differentiate into classical monocytes in bone marrow; these classical monocytes are released into the circulation, where they undergo one of two fates: they either differentiate into intermediate monocytes or disappear by death or migration.
Similarly, intermediate monocytes either leave the blood by death or migration or differentiate into nonclassical monocytes. This model is summarized in Fig. The alternative parallel ontogeny scenario was also considered; in this model, the three subsets arise from separate linages, each with its own distinct postmitotic kinetics.
This model could certainly be made to fit the data mathematically, as it has so many free parameters, but was deemed unlikely on biological grounds. First, it predicts the presence of intermediate and nonclassical monocytes in the bone marrow, contrary to our observations where only classical monocytes were detected following bone marrow biopsy Fig.
In the sequential model used here Fig. Results from fitting the model to the experimental data are shown in Table 1 and Fig. We found that classical monocytes have a very short circulating lifespan mean 1. Most cells leave the circulation or die, whereas the remaining cells transition to intermediate monocytes.
Intermediate monocytes have a longer lifespan mean 4. Nonclassical monocytes in turn have the longest lifespan in blood mean 7. Pool sizes were determined by flow cytometric analysis and were an input variable in the model. Other studies have found evidence for a delay between intermediate monocytes and nonclassical monocytes Tak, T.
Poster P The goodness of the fits ssr were very similar with or without a delay. Our data are consistent with earlier murine studies, which provided evidence that the lifespan of each monocyte subpopulation varies; classical Ly6C hi monocytes have shorter circulating half-lives 20 h than nonclassical Ly6C lo monocytes 2.
The difference in circulating half-life between monocyte subsets is likely to correlate with their functional attributes. Classical monocytes replenish the large resident monocyte-derived population of the gut Bain et al. More recently, these cells have been shown to enter tissues under steady state and transport antigen to lymph nodes without differentiating Jakubzick et al.
Less is known regarding the fate of nonclassical monocytes, but it is well documented that mouse and human nonclassical monocytes patrol the endothelium Auffray et al. We next investigated the response of monocytes to major systemic inflammation using the human experimental endotoxemia model Fig. A single i.
Corresponding in vitro studies have reported functional differences in the response to LPS between monocyte subpopulations Cros et al. Sequential reappearance of monocytes subsets after endotoxin challenge.
Classical monocytes were then sorted from whole blood, DNA extracted, and deuterium enrichment quantified by gas chromatography mass spectrometry over the ensuing 8 d.
Strikingly, repopulation of the blood monocyte pool began very rapidly. Classical monocytes were the first subset to repopulate the circulation and appeared as early as 4 h after endotoxin; intermediate and nonclassical monocytes remained absent from the circulation until 24 h Fig. By day 7, monocyte numbers had returned to steady-state values Fig. These data are consistent with previous studies in rodents, in which there is an expansion in circulating classical Ly6C hi monocytes following both peripheral and systemic inflammation Shi et al.
Interestingly, the recovery surge of monocyte subsets following systemic inflammation recapitulates the order in which deuterium labeling appeared in monocyte subsets in healthy homeostasis Fig. To address this question, volunteers were pulsed with deuterium-labeled glucose 20 h before endotoxin challenge. We deliberately chose this time point preendotoxin, as we knew from the healthy labeling data that at this time point after labeling, no circulating monocytes would normally be labeled Fig.
Hence, unlabeled cells reappearing from margination could be readily distinguished from highly labeled cells released early from bone marrow. We observed very high levels of deuterium labeling in classical monocytes at 8 h following endotoxin challenge Fig. Although it cannot be confirmed that all classical monocytes were released from the bone marrow, due to the limitations of human experimentation, the fraction labeled were very similar to those seen 72 h after labeling in healthy homeostasis and are consistent with the proposal that most, if not all, circulating monocytes in the early recovery phase are bone marrow derived, rather than monocytes returning from a marginated pool.
Certainly, it is clear that the transition time from bone marrow to the circulation is reduced dramatically in comparison to steady state as a result of the emergency release of classical monocytes. Given the sequential maturation of monocyte subsets during healthy homeostasis and, reappearance of monocytes following endotoxin challenge, we investigated the developmental relationship between human monocytes subsets in a humanized animal model.
Recipient mice were sacrificed at various time points following transfer, and peripheral blood was subjected to flow cytometry analysis. Collectively, this establishes for the first time that human classical monocytes have the potential to become intermediate monocytes before finally differentiating into nonclassical monocytes in vivo. These studies are reminiscent of previous rodent experiments, where classical Ly6C hi monocytes were shown to convert into nonclassical cells over time Varol et al.
Although the conversion times differed from those seen in the in vivo deuterium-labeling studies, this is most likely due to grafted cells already being mature classical monocytes. Due to the challenging nature of ex vivo monocyte culture, this has not been demonstrated in human cells, but hopefully, future advances in cell culture will enable us to fully comprehend the mechanisms involved in human monocyte conversion.
Development of intermediate and nonclassical human monocytes from classical monocytes. Grafted cells could be readily identified by expression of the human isoform of CD45 compared with recipient leukocytes expressing mouse CD Results are representative of three analyzed mice per time point.
As a result of this delay, a reserve population of newly generated classical monocytes is retained in bone marrow. Following acute systemic inflammation, this reserve population is rapidly released to replace lost circulating cells. A small proportion of classical monocytes further mature into intermediate monocytes in the circulation; most of these cells finally convert to nonclassical monocytes before leaving the circulation. Clearly, this is a very tightly controlled process, with remarkably consistent results between individuals.
Establishing the regulatory mechanisms that control these processes will be the next step in exploring human monocyte biology regulation. Understanding the fundamental regulation of monocyte subset generation, differentiation, and function will dictate future therapeutic avenues, depleting them when they are detrimental and boosting them when they are beneficial.
Subjects were healthy volunteers 20 males and 5 females. Human bone marrow samples were obtained from hematopoietic stem cell donors or femoral heads following total hip replacement.
For a positive control, the human monocyte cell line Mono Mac 6 was used Ziegler-Heitbrock et al. For bone marrow isolation, cells from hip arthroplasty specimens and bone fragments were excavated from femoral heads. Mononuclear cells were prepared from the resulting cell suspension or bone marrow aspirate from hematopoietic stem cells healthy donors by density centrifugation as described for PBMCs.
Deuterium labeling followed a shortened version of published protocols Macallan et al. Subjects received 20 g deuterium-labeled glucose 6,6- 2 H 2 -glucose; Cambridge Isotopes as an oral solution in half-hourly aliquots over 3 h, following a priming dose equivalent to 1. Blood glucose enrichment was monitored at baseline, during and after labeling.
At selected time points after labeling, mononuclear phagocytes subsets were stained and sorted by FACS Aria II BD , DNA extracted, and deuterium enrichment measured by gas chromatography mass spectrometry, as previously described Busch et al. A schematic of the model is shown in Fig. We denote N as the number of monocytes in the bone marrow, B 1 the number of classical monocytes in the blood, B 2 the number of intermediate monocytes in the blood, and B 3 the number of nonclassical monocytes in the blood.
The dynamics between these four compartments can then described by the following equations:. We assume that all the compartments are in steady state.
The relative sizes of B 1 , B 2 , and B 3 were taken from flow cytometry data for each individual Table 1. Here, U t is the precursor enrichment plasma glucose at time t, described empirically as a plateau function with exponential decay. We used the R packages modFit and dede to fit the model to the observed values of deuterium enrichment F x in the equations above. The fitting algorithm sought to minimize the sum of squared residuals between the modeled curves and observed values. At selected time points, blood samples were taken and analyzed by flow cytometry.
Three subjects received deuterium-labeled glucose 20 h before endotoxin administration and monocyte labeling kinetics analyzed as above Fig.
Mice were maintained under specific pathogen—free conditions and handled under protocols approved by the Yale Institutional Animal Care and Use Committee. Peripheral blood was collected by cardiac puncture under terminal anesthesia; erythrocytes were lysed by ACK Lonza. The leukocyte fraction was stained and analyzed by flow cytometry. S1 quantifies human blood monocyte subset membrane marker expression and cell cycle analysis. S2 shows modeling curves generated with and without a delay between intermediate and nonclassical monocytes.
Table S1 shows model data fit with and without a delay. Table S2 shows lifespans, proliferation rates, and delays for the model with a delay. We would like to thank the all the volunteers who participated in this study, Jamie Evans UCL for his assistance with the cell sorting, and Jonathan Alderman Yale University for coordinating phlebotomy and logistics. We thank our colleagues for useful discussions, especially Dr. Mildner and Dr. Cellular differentiation of human monocytes is regulated by time-dependent interleukin-4 signaling and the transcriptional regulator NCOR2.
The MHC class II antigen presentation pathway in human monocytes differs by subset and is regulated by cytokines. Exp Hematol. Infect Immun. Scand J Immunol. BMC Genom. Transcription and enhancer profiling in human monocyte subsets. Monocyte subsets coregulate inflammatory responses by integrated signaling through TNF and IL-6 at the endothelial cell interface.
Phenotype, function, and differentiation potential of human monocyte subsets. Trained immunity: a program of innate immune memory in health and disease. BCG vaccination protects against experimental viral infection in humans through the induction of cytokines associated with trained immunity.
Cell Host Microbe. Netea MG, van Crevel R. BCG-induced protection: effects on innate immune memory. Semin Immunol. Current evidence on healthy eating. Annu Rev Public Health. Health effects of dietary risks in countries, — a systematic analysis for the Global Burden of Disease Study Can physical activity ameliorate immunosenescence and thereby reduce age-related multi-morbidity? Obesity epidemiology worldwide. Gastroenterol Clin North Am. Inflammatory links between obesity and metabolic disease find the latest version : review series inflammatory links between obesity and metabolic disease.
J Clin Invest. Obesity, inflammation, and cardiovascular risk. Clin Pharmacol Ther. Russo L, Lumeng CN. Properties and functions of adipose tissue macrophages in obesity. Profiling of the three circulating monocyte subpopulations in human obesity.
Lipid-associated macrophages control metabolic homeostasis in a trem2-dependent manner. Effects of a Low-calorie, low-carbohydrate soy containing diet on systemic inflammation among patients with nonalcoholic fatty liver disease: a parallel randomized clinical trial. Horm Metab Res. Sci Transl Med. Dietary intake regulates the circulating inflammatory monocyte pool. Nat Med. Rothhammer V, Quintana FJ.
The aryl hydrocarbon receptor: an environmental sensor integrating immune responses in health and disease. Aryl Hydrocarbon receptor controls monocyte differentiation into dendritic cells versus macrophages. The short chain fatty acid butyrate imprints an antimicrobial program in macrophages. Remembering pathogen dose: long-term adaptation in innate immunity. Trends Immunol. Oxidized low-density lipoprotein induces long-term proinflammatory cytokine production and foam cell formation via epigenetic reprogramming of monocytes.
Western diet triggers NLRP3-dependent innate immune reprogramming. Low-density lipoproteins cause atherosclerotic cardiovascular disease. Evidence from genetic, epidemiologic, and clinical studies.
Eur Heart J. Brown M, Goldstein J. A receptor-mediated pathway for cholesterol homeostasis. Global Health Estimates Google Scholar. Chemokines in vascular pathology review. Int J Mol Med. Chemokines and atherosclerosis. J Mol Med. Minimally modified low density lipoprotein induces monocyte chemotactic protein 1 in human endothelial cells and smooth muscle cells.
Expression of monocyte subsets and angiogenic markers in relation to carotid plaque neovascularization in patients with pre-existing coronary artery disease and carotid stenosis.
Ann Med. Associations between macrophage colony-stimulating factor and monocyte chemotactic protein 1 in plasma and first-time coronary events: a nested case-control study.
J Am Heart Assoc. Inflammation and its resolution in atherosclerosis: mediators and therapeutic opportunities. Nat Rev Cardiol. Weber C, Noels H. Atherosclerosis : current pathogenesis and therapeutic options. Contribution of monocyte-derived macrophages and smooth muscle cells to arterial foam cell formation. Cardiovasc Res. NLRP3 inflammasomes are required for atherogenesis and activated by cholesterol crystals.
Oxidized phospholipids on Lipoprotein a elicit arterial wall inflammation and an inflammatory monocyte response in humans. Oxidized phospholipids are proinflammatory and proatherogenic in hypercholesterolaemic mice.
Monocyte and macrophage immunometabolism in atherosclerosis. Semin Immunopathol. Innate immune cell activation and epigenetic remodeling in symptomatic and asymptomatic atherosclerosis in humans in vivo. Blood monocyte transcriptome and epigenome analyses reveal loci associated with human atherosclerosis. Nat Commun. J Am Coll Cardiol. Association of monocyte subsets with vulnerability characteristics of coronary plaques as assessed by slice multidetector computed tomography in patients with stable angina pectoris.
Shift of monocyte subsets along their continuum predicts cardiovascular outcomes. IJC Hear Vasc. Prognostic signi fi cance of circulating leukocyte subtype counts in patients with coronary artery disease. Comparison of circulating dendritic cell and monocyte subsets at different stages of atherosclerosis : insights from optical coherence tomography.
BMC Cardiovasc Disord. Nephrol Dial Transplant. Association of blood monocyte and platelet markers with carotid artery characteristics: the atherosclerosis risk in communities carotid MRI study. Cerebrovasc Dis. J Mol Cell Cardiol. Hypercholesterolemia and reduced HDL-C promote hematopoietic stem cell proliferation and monocytosis: studies in mice and FH children. Circ Cardiovasc Genet. Association of monocyte subset counts with coronary fibrous cap thickness in patients with unstable angina pectoris.
Association of toll-like receptor 4 on human monocyte subsets and vulnerability characteristics of coronary plaque as assessed by slice multidetector computed tomography. Circ J. Nonclassical monocytes in health and disease.
Annu Rev Immunol. Nr4a1-dependent Ly6Clow monocytes monitor endothelial cells and orchestrate their disposal. Atlas of the immune cell repertoire in mouse atherosclerosis defined by single-cell RNA-sequencing and mass cytometry. Circ Res. Single-cell analysis of fate-mapped macrophages reveals heterogeneity, including stem-like properties, during atherosclerosis progression and regression.
JCI Insight. Transcriptome analysis reveals nonfoamy rather than foamy plaque macrophages are proinflammatory in atherosclerotic murine models. Transdifferentiation of vascular smooth muscle cells. KLF4-dependent phenotypic modulation of smooth muscle cells has a key role in atherosclerotic plaque pathogenesis. Coronary heart disease contribution of intimal smooth muscle cells to cholesterol accumulation and macrophage-like cells in human atherosclerosis.
Myocardin axis to convert aortic smooth muscle cells to a dysfunctional macrophage-like phenotype. Single-cell RNA-seq reveals the transcriptional landscape and heterogeneity of aortic macrophages in murine atherosclerosis.
Role of smooth muscle cells in vascular calcification: implications in atherosclerosis and arterial stiffness. Osteogenic monocytes within the coronary circulation and their association with plaque vulnerability in patients with early atherosclerosis.
Flow cytometric analysis of mononuclear phagocytes in nondiseased human lung and lung-draining lymph nodes. Flow cytometric analysis of myeloid cells in human blood, bronchoalveolar lavage, and lung tissues. Flow cytometry reveals similarities between lung macrophages in humans and mice. Dendritic cells and monocytes with distinct inflammatory responses reside in lung mucosa of healthy humans. Idiopathic pulmonary fibrosis. N Engl J Med.
Boucher RC. Muco-obstructive lung diseases. Activation and polarization of circulating monocytes in severe chronic obstructive pulmonary disease. BMC Pulm Med. Increased monocyte count as a cellular biomarker for poor outcomes in fibrotic diseases: a retrospective, multicentre cohort study. Lancet Respir Med. Inflammatory leukocyte phenotypes correlate with disease progression in idiopathic pulmonary fibrosis.
Front Med. Monocyte-derived alveolar macrophages drive lung fibrosis and persist in the lung over the life span.
0コメント