Levels Of Circulating Monocytes Research Articles

CD4+ Th1 and Th17 responses and multifunctional CD8 T lymphocytes associated with cure or disease worsening in human visceral leishmaniasis.

In VL, a proinflammatory phenotype is typically associated with enhanced phagocytosis and a Th1 mediated immune response resulting in infection control. In contrast, an anti-inflammatory phenotype, associated with a predominant regulatory response, typically enables intracellular multiplication of Leishmania parasites and disease progression. To investigate the impact of chemotherapy on Th2 and Th17 immune responses in patients with visceral leishmaniasis (VL), we assessed all combinations of intracellular expression of IFN-γ, IL-10, IL-4 and IL-17 in the CD4+ and CD8+ T cell populations of peripheral blood mononuclear cell (PBMC) samples from patients, after antigenic stimulation with Leishmania lysate, throughout treatment and follow-up. As increases in spleen and liver sizes and decreases in hematocrit, hemogloblin, erythrocytes, monocytes, leukocytes and platelets levels are strongly related to the disease, we studied the correlations between the frequencies of T cells producing the afore mentioned cytokines, individually and in combination, and these variables, as markers of disease or cure. We found that the frequency of IFN-γ-producingCD4+ T cells increased until the end of chemotherapy with Glucantime® or AmBisome ®, while IL-10, IL-4 and IL-17-producing CD4+ T cells peaked on day 7 following the start of treatment. Although the frequency of CD4+IL-17+ cells decreased during treatment an increase was observed after clinical cure. The frequency of CD4+ T cells producing only IFN-γ or IL-17 correlated with blood monocytes levels. Frequencies of double-producers of IFN-γ and IL-10 or IL-4 correlated positively with eosinophils and platelets levels. Together, this suggest that IFN-γ drives the immune response towards Th1 at cure. In contrast, and associated with disease or Th2 response, the frequency of CD4+ IL-10+ cells correlated positively with spleen sizes and negatively with circulating monocyte levels, while the frequency of CD4+ producing both IL-4 and IL-10 correlated negatively with platelets levels. The frequency of CD8+ single-producers of IFN-γ increased from day 21 to 90 while that of single-producers of IL-10 peaked on day 7, of IL-4 on day 30 and of IL-17, on day 180. IFN-γ expression in CD8+ single- and double-producers of cytokines was indicative of an immune response associated with cure. In contrast, frequencies of CD8+ double-producers of IL-4 and IL-10, IL-4 and IL-17 and IL-10 and IL-17 and producers of three and four cytokines, were associated with disease and were low after the cure. Frequencies of CD8+ T cells producing IFN-γ alone or with IL-17 were positively correlated with platelets levels. In contrast, as markers of disease: 1) frequencies of single producers of IL-10 correlated negatively with leukocytes levels, 2) frequencies of double producers of IL-4 and IL-10 correlated negatively with platelet, leukocyte, lymphocyte and circulating monocyte levels, 3) frequencies of triple-producers of IFN-γ, IL-4 and IL-10 correlated negatively with platelet, leukocyte and neutrophil levels and 4) frequencies of producers of IFN-γ, IL-4, IL-10 and IL-17 simultaneously correlated positively with spleen size, and negatively with leukocyte and neutrophil levels. Our results confirmed that the clinical improvement of VL patients correlates with the decrease of an IL-4 and IL-10 CD4+Th2 response, the recovery of CD4+ Th1 and Th17 responses and the frequency of CD8+ single-producers of IFN-γ and double producers of IFN-γ and IL-17.

Systemic bone loss following myocardial infarction in mice.

Myocardial infarction (MI) and osteoporotic fracture are leading causes of morbidity and mortality, and epidemiological evidence linking their incidence suggests possible crosstalk. MI can exacerbate atherosclerosis through the sympathetic nervous system (SNS) activation and β3 adrenoreceptor-mediated release of hematopoietic stem cells, leading to monocytosis. We hypothesized that this same pathway initiates systemic bone loss following MI,since osteoclasts differentiate from monocytes. In this study, MI was created with left anterior descendingartery ligation in 12-week-old male mice (n = 24) randomized to β3 -adrenergic receptor (AR) antagonist (SR 59230A) treatment or no treatment for 10 days postoperatively. Additional mice (n = 21, treated and untreated) served as unoperated controls. Bone mineral density (BMD), bone mineral content (BMC), and body composition were quantified at baseline and 10 days post-MI using dual-energy x-ray absorptiometry; circulating monocyte levels were quantified and the L5 vertebral body and femur were analyzed with microcomputed tomography 10 days post-MI. We found that MI led to circulating monocyte levels increases, BMD and BMC decreases at the femur and lumbar spine in MI mice (-6.9% femur BMD, -3.5% lumbar BMD), and trabecular bone volume decreases in MI mice compared with control mice. β3 -AR antagonist treatment appeared to diminish the bone loss response (-5.3% femur BMD, -1.2% lumbar BMD), though these results were somewhat inconsistent. Clinical significance:These results suggest that MI leads to systemic bone loss, but that the SNS may not be a primary modulator of this response; bone loss and increased fracture risk may be important clinical comorbidities following MI or other ischemic injuries.

Differential expression of glycoprotein IV on monocyte subsets following high-fat diet feeding and the impact of short-term low-dose aspirin treatment

ObjectiveTo assess the levels of glycoprotein GPIV (CD36) expression on peripheral blood monocyte subsets, in a mouse model of glucose intolerance. Moreover, to determine the effect of; low-dose aspirin (LDA) alone, LDA combined with metformin, or clopidogrel alone, on the expression of CD36 on subsets of circulating monocytes. MethodThe study consisted of two experimental phases. In experiment one, the mice (n = 14) were randomised to receive a low-fat diet (LFD) or a high-fat diet (HFD) for eight weeks. Whereas the secondary phase of the experiment, comprised of twenty-four HFD-fed mice treated with LDA alone (3 mg/kg), or in combination with metformin (150 mg/kg), or clopidogrel alone (10 mg/kg) for six weeks. The surface expression of CD36 on monocytes was measured using flow cytometry. ResultThe levels of CD36 expression on monocytes were upregulated in the HFD-fed compared to LFD-fed group (p < 0.05). In addition, HFD group showed; no significant changes in body weight (p = 0.3848), however, blood glucose (p = 0.0002) and insulin (p = 0.0360) levels were markedly increased following HFD-feeding. Interestingly, all treatments reduced the expression of CD36 on monocytes, decreased fasting blood glucose levels (p = 0.0024) and increased circulating monocyte levels (p = 0.0217) when compared to the untreated HFD group. Moreover, treatment with LDA alone increased basophils levels (p = 0.0272), while when combined with metformin showed an improved effect in enhancing eosinophil levels (p = 0.0302). ConclusionHFD-feeding increased the expression of CD36 on monocyte subsets. LDA as a monotherapy or combined with metformin was as effective as clopidogrel monotherapy, in downregulating the expression of CD36 on monocyte subsets. These treatments may be of relevance in preventing cardiovascular complications associated with impaired glucose tolerance.

Abstract 796: Dysfunctional Immune Cell Clock Contributes to Heart Failure Progression

Objective: Inappropriately sustained activation of monocytes/macrophages contributes to heart failure (HF) progression. Time-of-day greatly influences cardiovascular and immune systems, in part through cell autonomous circadian clocks. Here, we propose that disruption of monocyte/macrophage circadian clocks contributes to pathologic inflammation and HF progression following myocardial infarction (MI). Methods: MI-induced HF was achieved by permanent ligation of coronary artery in myeloid-specific Bmal1 knockout (MBK) mice and wild-type (WT) mice. Left ventricular (LV) function was assessed echocardiography. Flow cytometry was utilized for immune cell profiling. RNAseq and qRT-PCR was utilized for gene-expression studies. Tissue fibrosis was quantified using Masson-trichrome staining. Results: WT (C57Bl/6) HF mice exhibited altered Ly6C hi monocyte circadian clock gene expression as compared with sham-operated mice, with significantly reduced expression of the key clock effector Bmal1 . Genetic disruption of the monocyte clock in MBK mice had no effect on macrophage inflammatory markers during unstressed, baseline conditions. However, MBK-HF mice (4 w post-MI) exhibited increased infiltrating CCR2 + heart macrophages (2642±803 vs. 937±190 per heart, p&lt;0.05), augmented cardiac fibrosis (22±1 vs. 14±3 %, p&lt;0.05), greater LV dysfunction [ejection fraction 19.7±2 vs. 28.4±4 %, p&lt;0.05), increased LV end-diastolic and end-systolic volume (EDV 140.4±10 vs. 100±8 μl, p&lt;0.01; ESV 115±10 vs. 74±9 μl, p&lt;0.01) and cardiac hypertrophy (heart weight/tibia length 12.1±0.6 vs. 10.5±0.4 mg/mm, p&lt;0.05) as compared with WT HF littermate control mice. Moreover, circulating monocyte levels in MBK-HF mice were significantly increased at zeitgeber time 6 versus WT HF littermate controls (296±58 vs. 131±17 cells/μl, p&lt;0.05). Conclusion/Broader Impact: Monocyte/macrophage circadian gene dysregulation resulting from Bmal1 loss-of-function exacerbates pathological LV remodeling, systemic and cardiac inflammation, and tissue fibrosis in chronic ischemic HF. Restoration of circadian clock function in innate immune cells may represent a potential therapeutic approach to immunomodulation in chronic HF.

Monocyte Modulation by Liposomal Alendronate Improves Cardiac Healing in a Rat Model of Myocardial Infarction

The ischemic injury in acute myocardial infarction (AMI) activates the innate immunity response in two consecutive phases. Classical monocytes (CM) accumulate in the inflammatory phase (first 3 days), and non-classical monocytes (NCM) accumulate in the reparatory phase (4–7 days). We hypothesized that inhibition of monocytes at the second phase post-AMI will lead to better healing by reducing myocardial damage and consequently improve heart function. We examined the effect of monocyte modulation on cardiac healing following MI injury in rats by nano-sized alendronate liposomes (LipAln) treatment. Rats were treated with intravenous (IV) LipAln, on days 5, 7, and 9 after ligation of the left anterior descending artery (LAD). Circulating monocyte levels were reduced after the first LipAln injection, and two peripheral blood monocyte subsets, CM and NCM, were sequentially mobilized after MI. Two weeks after MI, a reduction in infarct size was observed and cardiac function was improved in LipAln-treated rats (fractional shortening of 32.2% ± 1.9% and 26.0% ± 1.3%, for LipAln and saline treated rats, respectively, p < 0.05). This improvement was further corroborated by increased cardiac anti-inflammatory cytokine expression and reduced levels of pro-inflammatory cytokines. In conclusion, LipAln treatment during the second phase after MI improves cardiac healing. Myocardial infarction (MI) occurs when coronary blood flow decreases, causing damage to the heart muscle. Consequently, the body sends cells called monocytes/macrophages as part of a reparatory-inflammatory response. We hypothesized that altering a specific step in the inflammatory process, which the heart utilizes to heal itself, could result in improved heart function. Using a unique drug delivery system of nano-sized particles called liposomes, in which a molecule (bisphosphonate) that is toxic to monocytes is embedded, we successfully altered the inflammatory process, in a rat model of MI. resulting in improved heart function. The novel technology reported in this issue celebrating Robert Langer’s birthday is directly linked to my previous work with Bob. As Bob’s postdoc at MIT (1984–1986), our group developed heart valve anti-calcification implantable drug delivery systems, which contain a bisphosphonate. His guidance and mentorship then, and to this day, are of great importance. I am forever grateful for his continued contribution.

B cell lymphoma progression promotes the accumulation of circulating Ly6Clo monocytes with immunosuppressive activity

ABSTRACT Monocytosis is considered a poor prognostic factor for many cancers, including B cell lymphomas. The mechanisms by which different monocyte subsets support the growth of lymphoma is poorly understood. Using a pre-clinical mouse model of B cell non-Hodgkin's lymphoma (B-NHL), we investigated the impact of tumor progression on circulating monocyte levels, subset distribution and their activity, with a focus on immune suppression. B-NHL development corresponded with significant expansion initially of classical (Ly6Chi) and non-classical (Ly6Clo) monocytes, with accumulation and eventual predominance of Ly6Clo cells. The lymphoma environment promoted the conversion, preferential survival and immune suppressive activity of Ly6Clo monocytes. Ly6Clo monocytes expressed higher levels of immunosuppressive genes including PD-L1/2, Arg1, IDO1 and CD163, compared to Ly6Chi monocytes. Both monocyte subsets suppressed CD8 T cell proliferation and IFN-γ production in vitro, but via different mechanisms. Ly6Chi monocyte suppression was contact dependent, while Ly6Clo monocytes suppressed via soluble mediators, including IDO and arginase. Ly6Clo monocytes could be selectively depleted in tumor-bearing hosts by liposomal doxorubicin treatment, further enhanced by co-administration of anti-4-1BB monoclonal antibody. This treatment led to a reduction in tumor growth, but failed to improve overall survival. Analogous immunosuppressive monocytes were observed in peripheral blood of diffuse large B cell lymphoma patients and actively suppressed human CD8 T cell proliferation. This study highlights a potential immune evasion strategy deployed by B cell lymphoma involving accumulation of circulating non-classical monocytes with immunosuppressive activity.

CD8+ T Cells Regulate Monopoiesis and Circulating Ly6C-high Monocyte Levels in Atherosclerosis in Mice.

Proinflammatory adaptive immune responses are recognized as major drivers of atherosclerotic lesion formation. Although CD8(+) T cells have recently been proposed as a proatherogenic cell subset, their full scope of actions remains to be elucidated. We here addressed the contribution of CD8(+) T cells to monocyte trafficking in atherosclerosis. We observed that CD8(+) T cells express proinflammatory cytokines (interferon-γ, tumor necrosis factor-α, and interleukin-12) within atherosclerotic lesions and spleens of high-fat diet-fed low-density lipoprotein receptor-deficient (Ldlr(-/-)) mice. Antibody-mediated CD8(+) T-cell depletion in high-fat diet-fed Ldlr(-/-) mice decreased atherosclerotic plaque formation, associated with decreased macrophage accumulation within lesions. Despite a reduction in vascular chemokine (CC-motif) ligand 2 and chemokine (CXC-motif) ligand 1 expression, CD8(+) T-cell depletion did not directly affect monocyte recruitment to inflamed vessels. However, CD8(+) T-cell depletion decreased chemokine (CC-motif) ligand serum concentrations and circulating Ly6C(high) monocyte counts. We further evidenced that CD8(+) T-cell depletion decreased levels of mature monocytes and myeloid granulocyte-monocyte progenitors in the bone marrow and spleen of hypercholesterolemic mice, effects that were partially reproduced by interferon-γ neutralization, showing a role for interferon-γ. These data suggest that CD8(+) T cells promote atherosclerosis by controlling monopoiesis and circulating monocyte levels, which ultimately contributes to plaque macrophage burden without affecting direct monocyte recruitment, identifying this cell subset as a critical regulator of proatherogenic innate immune cell responses in atherosclerosis.

Targeted anti-inflammatory systemic therapy for restenosis: The Biorest Liposomal Alendronate with Stenting sTudy (BLAST)—a double blind, randomized clinical trial

Activation of systemic innate immunity is critical in the chain of events leading to restenosis. LABR-312 is a novel compound that transiently modulates circulating monocytes, reducing accumulation of these cells at vascular injury sites and around stent struts. The purpose of the study was to examine the safety and efficacy of a single intravenous bolus of LABR-312 in reducing restenosis in patients treated for coronary narrowing. Patient response was examined in light of differential inflammatory states as evidenced by baseline circulating monocyte levels, diabetes mellitus, and acute coronary syndrome. BLAST is a Phase II prospective, randomized, multicenter, double-blind, placebo-controlled trial that assessed the safety and efficacy of LABR-312. Patients were randomized to receive LABR-312 at 2 dose levels or placebo as an intravenous infusion during percutaneous coronary intervention and bare metal stent implantation. The primary end point was mean angiographic in-stent late loss at 6 months. Patients (N = 225) were enrolled at 12 centers. There were no safety concerns associated with the study drug. For the overall cohort, there were no differences between the groups in the primary efficacy end point (in-stent late loss of 0.86 ± 0.60 mm, 0.83 ± 0.57 mm, and 0.81 ± 0.68 mm for the placebo, low-dose, and high-dose group, respectively; P = not significant for all comparisons). In the prespecified subgroups of patients with a baseline proinflammatory state, patients with diabetes mellitus, and patients with high baseline monocyte count, there was a significant treatment effect. Intravenous administration of LABR-312 to patients undergoing percutaneous coronary intervention is safe and effectively modulates monocyte behavior. The average late loss did not differ between the treatment and placebo groups. However, in the inflammatory patient group with baseline monocyte count higher than the median value, there was a significant reduction in late loss with LABR-312.

An orally active chemokine receptor CCR2 antagonist prevents glomerulosclerosis and renal failure in type 2 diabetes

The progression of diabetic nephropathy is associated with an infiltration of macrophages expressing different phenotypes. As classically activated chemokine receptor CCR2+ macrophages are thought to drive tissue inflammation and remodeling, we tested whether blocking CCR2 could reduce intrarenal inflammation and prevent glomerulosclerosis in type 2 diabetes. This was achieved with RO5234444, an orally active small-molecule CCR2 antagonist that blocks ligand binding, its internalization, and monocyte chemotaxis. Male type 2 diabetic db/db mice were uninephrectomized to increase glomerular hyperfiltration to accelerate the development of glomerulosclerosis. From 16 weeks until killing at 24 weeks of age, mice were chow fed with or without admixed antagonist to achieve a trough plasma concentration above IC50 for binding in the mouse. CCR2 blockade reduced circulating monocyte levels, but did not affect total leukocyte or neutrophil numbers, and was associated with a reduction in the number of macrophages and apoptotic podocytes in the glomerulus. This treatment resulted in a higher total number of podocytes, less glomerulosclerosis, reduced albuminuria, and a significantly improved glomerular filtration rate. This successful pre-clinical trial suggests that this antagonist may now be ready for testing in humans with the nephropathy of diabetes mellitus.

Antibody blockade of c-fms suppresses the progression of inflammation and injury in early diabetic nephropathy in obese db/db mice

Macrophage-mediated renal injury plays an important role in the development of diabetic nephropathy. Colony-stimulating factor (CSF)-1 is a cytokine that is produced in diabetic kidneys and promotes macrophage accumulation, activation and survival. CSF-1 acts exclusively through the c-fms receptor, which is only expressed on cells of the monocyte-macrophage lineage. Therefore, we used c-fms blockade as a strategy to selectively target macrophage-mediated injury during the progression of diabetic nephropathy. Obese, type 2 diabetic db/db BL/KS mice with established albuminuria were treated with a neutralising anti-c-fms monoclonal antibody (AFS98) or isotype matched control IgG from 12 to 18 weeks of age and examined for renal injury. Treatment with AFS98 did not affect obesity, hyperglycaemia, circulating monocyte levels or established albuminuria in db/db mice. However, AFS98 did prevent glomerular hyperfiltration and suppressed variables of inflammation in the diabetic kidney, including kidney macrophages (accumulation, activation and proliferation), chemokine CC motif ligand 2 levels (mRNA and urine protein), kidney activation of proinflammatory pathways (c-Jun amino-terminal kinase and activating transcription factor 2) and Tnf-alpha (also known as Tnf) mRNA levels. In addition, AFS98 decreased the tissue damage caused by macrophages including tubular injury (apoptosis and hypertrophy), interstitial damage (cell proliferation and myofibroblast accrual) and renal fibrosis (Tgf-beta1 [also known as Tgfb1] and Col4a1 mRNA). Blockade of c-fms can suppress the progression of established diabetic nephropathy in db/db mice by targeting macrophage-mediated injury.

Antileukocyte activity I. Systemic inhibition of cellular emigration following local inflammation.

Inflammation in progress at one site decreases edema formation at a second and separate inflammatory focus. This clinically important phenomenon is known as counter-irritation. Since its effect on leukocyte responses has not been defined, we investigated in rats the systemic anti-inflammatory effect of local irritant injection on cellular emigration, particularly monocytes. Macrophage accumulation at a subcutaneous inflammatory site was severely depressed by prior intraperitoneal irritant injection despite continued macrophage accumulation in the peritoneal cavity and normal circulating monocyte levels. The phenomenon also existed in the peritoneal cavity to subcutaneously administered irritants and involved PMNs as readily as macrophages. Anti-inflammation occurred only when the counter-irritant was injected before or simultaneously with the measured inflammatory response while the degree and duration of inhibition depended upon the nature and amount of counter-irritant injected. These studies demonstrate that local inflammation inhibits leukocyte reactivity. Transplantation of syngeneic tumor but not normal cells also produced a depression in macrophage inflammatory responses. This inhibition differed from counter-irritation by not affecting granulocytes and by being transient despite tumor persistence.

Generalized monocyte deficiency in leukaemic reticuloendotheliosis.

Examination of the blood of 40 patients with leukaemic reticuloendotheliosis (LRE) revealed a drastic reduction in monocyte numbers (mean 74/microliter) when compared to a normal group of 33 (mean 442/microliter). Repeated blood studies in 8 LRE patients were made over periods of 2 months to 5 years and monocytopenia was observed to be a persistent phenomenon. Similarly, tissues from 29 patients showed an overall decrease in numbers of monocytes/ histiocytes when compared with those of 73 control subjects. Skin window examinations in all 11 patients so studied showed marked reduction or absence of monocyte response to inflammation. 2 exceptional cases to this trend are noted. In one, circulating monocyte levels remained normal over a 14-month period while examinations of blood and marrow in this case showed few hairy cells. In another case, severe and persistent monocyte deficiency was noted during a 2-year period of unsuccessful treatment. When he eventually responded to low dose chlorambucil and his Hb rose from 40-140 g/l and WBC became normal, the number of circulating monocytes also became normal.