Role In Activation Of Monocytes Research Articles

Analyzing Inter-Leukocyte Communication and Migration In Vitro: Neutrophils Play an Essential Role in Monocyte Activation During Swarming.

Neutrophils are known to be the first responders to infection or injury. However, as inflammation progresses, other leukocytes become increasingly important in inflammation propagation, tissue reconstruction, and inflammation resolution. In recent years, there has been an increase in publications that analyze neutrophil behavior in vitro, but there remains a gap in the literature for in vitro technologies that enable quantitatively measuring interactions between different types of human leukocytes. Here, we used an in vitro platform that mimics inflammation by inducing neutrophil swarming to analyze the behavior of various leukocytes in a swarming setting. Using human peripheral blood leukocytes isolated directly from whole blood, we found that myeloid cells and lymphoid cells had different migratory behaviors. Myeloid cells, which are predominately neutrophils, exhibited swarming behavior. This behavior was not seen with lymphoid cells. We perturbed the peripheral blood leukocyte system by adding exogenous leukotriene B4 (LTB4) to the medium. Notably, only the myeloid cell compartment was significantly changed by the addition of LTB4. Additionally, LTB4 had no significant impact on myeloid cell migration during the recruitment phase of swarming. To further investigate the myeloid cell compartment, we isolated neutrophils and monocytes to analyze their interaction on the platform. We found that neutrophils increase monocyte migration toward the bioparticle clusters, as measured through speed, chemotactic index, track straightness, and swarm size. These results were confirmed with in vivo mouse experiments, where monocyte accumulation only occurred when neutrophils were present. Additionally, we found that both neutrophils and monocytes release the monocyte chemoattractant proteins CCL2 and CCL3 in the presence of Staphylococcus aureus bioparticles. Furthermore, extracellular vesicles from swarming neutrophils caused monocyte activation. These findings suggest that neutrophils play an essential role in the onset of inflammation not only by sealing off the site of infection or injury, but also by recruiting additional leukocytes to the site.

Progesterone and vitamin D downregulate the activation of the NLRP1/NLRP3 inflammasomes and TLR4-MyD88-NF-κB pathway in monocytes from pregnant women with preeclampsia

This study evaluated the in vitro modulatory effect of progesterone (PG) and vitamin D (VD) on NLRP1/NLRP3 inflammasomes and TLR4/NF-κB pathway in monocytes from pregnant women with preeclampsia (PE). Monocytes from 20 preeclamptic and 20 normotensive (NT) pregnant women, and THP-1 cells were cultured with/without hyaluronan (HA), PG, or VD to determine gene and protein expression of TLR4 receptor, phosphorylated NF-κB, IκBα, TLR4, MYD88, NF-κB, NLRP1, NLRP3, caspase-1, IL-1β, IL-18, TNF-α, and IL-10. Higher endogenous activation of inflammatory genes and higher protein expression of TLR4 and NF-κB was detected in monocytes of PE group and decreased after PG or VD treatment. Monocyte from PE stimulated with HA increased while treatment with PG or VD decreased the expression of genes and proteins related to the inflammasomes. THP-1 cells showed a similar immune response profile as monocytes from PE. These results demonstrate that PG and VD play an immunomodulatory role in monocyte activation.

Extracellular tyrosyl‐tRNA synthetase cleaved by plasma proteinases and stored in platelet α‐granules: Potential role in monocyte activation

BackgroundTyrosyl‐tRNA synthetase (YRS) belongs to the family of enzymes that catalyzes the tRNA aminoacylation reaction for protein synthesis, and it has been recently shown to exert noncanonical functions. Although database results indicate extremely low levels of YRS mRNA in platelets, YRS protein is abundantly present. The source of YRS in platelets, as well as the physiological role of platelet‐stored YRS, remains largely unknown. ObjectivesTo clarify how YRS accumulates in platelets and determine the potential role of platelet‐stored YRS. MethodsRecombinant YRS proteins with epitope tags were prepared and tested in vitro for proteolytic cleavage in human plasma. Fluorescent‐labeled YRS was examined for uptake by platelets, as demonstrated by western blotting and confocal microscopy analysis. Using RAW‐Dual reporter cells, Toll‐like receptor and type I interferon activation pathways were analyzed after treatment with YRS. ResultsFull‐length YRS was cleaved by both elastase and matrix metalloproteinases in the plasma. The cleaved, N‐terminal YRS fragment corresponds to the endogenous YRS detected in platelet lysate by western blotting. Both full‐length and cleaved forms of YRS were taken up by platelets in vitro and stored in the α‐granules. The N‐terminal YRS fragment generated by proteolytic cleavage had monocyte activation comparable to that of the constitutive‐active mutant YRS (YRSY341A) previously reported. ConclusionPlatelets take up both full‐length YRS and the active form of cleaved YRS fragment from the plasma. The cleaved, N‐terminal YRS fragment stored in α‐granules may have potential to activate monocytes.

Anemia Severity in β-Thalassemia Correlates with Elevated Levels of microRNA-125b in Activated Phagocytic Monocytes

β-Thalassemia (β-thal), is an inherited blood disorder caused by reduced or absent synthesis of β-globin chains leading to imbalance of globin chain synthesis. The clearance of β-thalassemic abnormal red blood cells (RBCs) that result from excessive unbound α-globin is mainly achieved by activated monocytes. The phagocytic activity of β-thal monocytes significantly increases when co-cultured with normal and β-thal RBC individuals compare to that of normal monocytes co-cultured with normal RBCs. The present study indicates that microRNA (miR) plays a role in monocyte activation. In this study, we identified the higher miR-125b expression in CD14 marker-positive monocytic cells of β-thal patients. Moreover, miR-125b expression levels positively correlate with the phagocytic activity of monocytes. Remarkably, miR-125b expression levels are negatively correlated with RBC count, hemoglobin (Hb) and hematocrit [or packed cell volume (PCV)], which are the indices for the severity of anemia. From these findings, our future studies will be to prove the hypothesis that miR-125b expression in activated monocytes may be a genetic modifier related to the severity of anemia in β-thal patients.

Hemozoin-induced activation of human monocytes toward M2-like phenotype is partially reversed by antimalarial drugs-chloroquine and artemisinin.

Plasmodium falciparum malaria is the most severe form of malaria with several complications. The malaria pigment‐hemozoin (Hz) is associated with severe anemia, cytokine dysfunction, and immunosuppression, thus making it an interesting target for developing new strategies for antimalarial therapy. Monocytes (MO) in circulation actively ingest Hz released by Plasmodium parasites and secrete pro‐ and anti‐inflammatory cytokines. M1 and M2 types represent the two major forms of MO/macrophages (MQ) with distinct phenotypes and opposing functions. Imbalance in the polarization of these types is reported in many infectious diseases. Though the association of Hz with immunosuppression is well documented, its role in activation of MO in context of M1/M2 phenotypes remains to be addressed. We report here that natural Hz drives human MO toward M2‐like phenotype as evidenced by the expression of M2 signature markers. Hz‐fed MO showed elevated transcript and secreted level of IL‐10, CCL17, CCL1, expression of mannose‐binding lectin receptor (CD206), and arginase activity. Hz attenuated HLA‐DR expression, nitric oxide, and reactive oxygen species production, which are the features of M1 phenotype. Our data also implicate the involvement of p38 MAPK, PI3K/AKT, and NF‐κB signaling pathways in skewing of Hz‐fed MO toward M2‐like type and suppression of mitogen‐stimulated lymphocyte proliferation. Importantly, antimalarial drugs—chloroquine and artemisinin—partially reversed activation of Hz‐induced MO toward M2‐like phenotype. Considering the limitations in the current therapeutic options for malaria, we propose that these drugs may be re‐examined for their potential as immunomodulators and candidates for adjunctive treatment in malaria.

MiR-155 enhances phagocytic activity of β-thalassemia/HbE monocytes via targeting of BACH1.

Abnormal red blood cell (RBC) clearance in β-thalassemia is triggered by activated monocytes. Recent reports indicate that miRNA (miR-) plays a role in monocyte activation. To study phagocytic function, we co-cultured monocytes of normal, non-splenectomized and splenectomized β-thalassemia/HbE individuals with RBCs obtained from normal, non-splenectomized and splenectomized β-thalassemia/HbE individuals. The phagocytic activity of β-thalassemia/HbE monocytes co-cultured with β-thalassemia/HbE RBCs was significantly higher than that of normal monocytes co-cultured with normal RBCs. Upregulation of monocyte miR-155 was observed in β-thalassemia/HbE patients. Increased miR-155 was associated with reductions in BTB and CNC Homology1 (BACH1) target gene expression and increased phagocytic activity of β-thalassemia/HbE monocytes. Taken together, these findings suggested that increased miR-155 expression in activated monocytes leads to enhanced phagocytic activity via BACH-1 regulation in β-thalassemia/HbE. This provides novel insights into the phagocytic clearance of abnormal RBCs in β-thalassemia/HbE.

IL-7δ5 protein is expressed in human tissues and induces expression of the oxidized low density lipoprotein receptor 1 (OLR1) in CD14+ monocytes

ObjectivesThe 6-exon-spanning ‘canonical’ Interleukin-7 (IL-7c) is a non-redundant cytokine in human T-cell homeostasis that undergoes extensive alternative pre-mRNA splicing. The IL-7 gene variant lacking, exon 5 (IL-7δ5), exhibits agonistic effects as compared to IL-7c. We studied in this report for the first time the protein expression of IL-7δ5 variant in tissues and its role in monocyte activation. MethodsWe visualized the expression of IL-7δ5 protein by immunohistochemistry in both healthy and malignant (human) tissues and investigated the impact of IL-7δ5 stimulation on CD14+ monocytes using gene expression analysis and flow cytometry. ResultsIL-7δ5 is largely expressed by human epithelial cells, yet also by stromal cells in malignant lesions. Gene expression analysis in CD14+ monocytes, induced by the 6-exon spanning IL-7 or IL-7δ5 showed similar changes resulting in a pro-inflammatory phenotype and increased expression of genes involved in lipid metabolism. IL7δ5 was superior in inducing upregulation of the oxidised low density lipoprotein receptor (OLR), measured by flow cytometry, in CD14+ cells. ConclusionIL-7δ5, produced from non-transformed and transformed cells, may contribute to chronic inflammatory responses and development of ‘foamy’ cells by increased OLR1 expression that mediates increased oxLDL uptake.

58: IL-27 inhibits HIV-1 infection in human macrophages by down-regulating host factor SPTBN1 during monocyte to macrophage differentiation

Macrophages represent a major target and viral reservoir of HIV-1 infection. The susceptibility of macrophages to HIV-1 infection is modulated during monocyte differentiation. IL-27 is an antiviral cytokine which also plays a role in monocyte activation. Here, we present new evidence that IL-27 promotes monocyte differentiation into macrophages that are non-permissive for HIV-1 infection. While IL-27 treatment does not affect expression of macrophage differentiation markers or macrophage biological functions, it confers HIV resistance by down-regulating SPTBN1, a required host factor for HIV-1 infection. IL-27 down-regulates SPTBN1 during monocyte differentiation through a TAK-1-mediated MAPK signaling pathway. Knockdown of SPTBN1 strongly inhibits HIV-1 infection of macrophages; conversely, overexpression of SPTBN1 markedly increases HIV susceptibility of IL-27 treated macrophages. Moreover, we demonstrate that SPTBN1 associates with HIV-1 gag proteins. Collectively, our results underscore the ability of IL-27 to protect macrophages from HIV-1 infection by down-regulating SPTBN1 during monocyte to macrophage differentiation without altering other macrophage biological functions, thus indicating IL-27 as a potential immunotherapeutic reagent to prevent HIV-1 infection.

TLR4 Signaling Augments Monocyte Chemotaxis by Regulating G Protein–Coupled Receptor Kinase 2 Translocation

Monocytes are critical effector cells of the innate immune system that protect the host by migrating to inflammatory sites, differentiating to macrophages and dendritic cells, eliciting immune responses, and killing pathogenic microbes. MCP-1, also known as CCL2, plays an important role in monocyte activation and migration. The chemotactic function of MCP-1 is mediated by binding to the CCR2 receptor, a member of the G protein-coupled receptor (GPCR) family. Desensitization of GPCR chemokine receptors is an important regulator of the intensity and duration of chemokine stimulation. GPCR kinases (GRKs) induce GPCR phosphorylation, and this leads to GPCR desensitization. Regulation of subcellular localization of GRKs is considered an important early regulatory mechanism of GRK function and subsequent GPCR desensitization. Chemokines and LPS are both present during Gram-negative bacterial infection, and LPS often synergistically exaggerates leukocyte migration in response to chemokines. In this study, we investigated the role and mechanism of LPS-TLR4 signaling on the regulation of monocyte chemotaxis. We demonstrate that LPS augments MCP-1-induced monocyte migration. We also show that LPS, through p38 MAPK signaling, induces phosphorylation of GRK2 at serine 670, which, in turn, suppresses GRK2 translocation to the membrane, thereby preventing GRK2-initiated internalization and desensitization of CCR2 in response to MCP-1. This results in enhanced monocyte migration. These findings reveal a novel function for TLR4 signaling in promoting innate immune cell migration.

Differential Effect of Telmisartan and Amlodipine on Monocyte Chemoattractant Protein-1 and Peroxisome Proliferator-Activated Receptor-Gamma Gene Expression in Peripheral Monocytes in Patients With Essential Hypertension

Monocyte chemoattractant protein-1 (MCP-1) and peroxisome proliferator-activated receptor-γ (PPAR-γ) play a significant role in monocyte activation, vascular inflammation, and atherogenesis. Angiotensin receptor blockers and calcium channel blockers are antihypertensive drugs with established efficacy and a favorable safety profile. We investigated the effect of telmisartan--an angiotensin receptor blocker with PPAR-γ agonist activity--and amlodipine on the activation state of peripheral blood monocytes with respect to MCP-1 and PPAR-γ gene expression in hypertensives. We recruited 31 previously untreated patients with essential hypertension who were randomly assigned to receive treatment with telmisartan (n = 16) or amlodipine (n = 15). Blood samples were taken before and 3 months after therapy initiation. Mononuclear cells were isolated and mRNAs of MCP-1 and PPAR-γ were estimated by real-time quantitative reverse transcription-polymerase chain reaction each time. The 2 treatments decreased all blood pressure components significantly (p <0.001). In contrast, in the amlodipine group, MCP-1 gene expression was significantly downregulated after treatment with telmisartan (from 21.4 ± 20.5 to 8.1 ± 6.5, p = 0.009), whereas the amlodipine group did not show any significant change (12.5 ± 8.5 vs 17.6 ± 16.4, p = NS). In addition, PPAR-γ mRNA levels showed a significant increase in telmisartan-treated patients (from 20 ± 18.5 to 42.6 ± 36, p = 0.006) and no significant alterations in the amlodipine group (from 29.6 ± 42.5 to 24.2 ± 27.7, p = NS). In conclusion, treatment with telmisartan results in a significant attenuation of MCP-1 gene expression and an increase of PPAR-γ gene expression in peripheral monocytes in patients with essential hypertension. Our findings may provide new insights into the cardiovascular protection of telmisartan in hypertensives.

Innate immunity to Legionella and toll-like receptors — review

Legionella is a parasite of eukaryotic cells, able to survive and replicate in a wide range of protozoan hosts. It can also infect humans as an opportunistic pathogen, primarily by interaction with alveolar macrophages. These bacteria can cause life-threatening pneumonia, especially in immunocompromised individuals. However, most infections triggered by Legionella are cleared by an efficient host immune system. The protective immune responses against Legionella are complex and multifaceted, involving many components of the immune system. Recognition of such components as LPS, flagellum, and peptidoglycan of L. pneumophila by the TLRs, which orchestrates the innate immune responses to Legionella, lays an important role in activation of monocytes and alveolar macrophages and, thus, in inhibition of intracellular proliferation of bacteria. MyD88-dependent signaling pathways are important for host protection against Legionella.

Sickle RBCs Stimulate Human Monocyte Cytokine Expression.

Sickle red cells (SS RBCs) express numerous adhesion molecules, including LW, CD44, CD47, and Lutheran (LU) proteins, as well as phosphatidylserine. Proadhesive SS RBCs bind to endothelial cells, leading to their activation. Sickle monocytes have also been shown to express increased surface CD11b, as well as the cytokines tumor necrosis factor α (TNF-α) and interleukin 1β (IL-1β), indicating their activated state. Chronic inflammation and high plasma levels of IL-1β can stimulate leukocyte proliferation and leukocytosis. An association between leukocytosis and increased morbidity and mortality of sickle cell disease (SCD) has been observed. However, the mechanism of monocyte activation in SCD is still unknown. We therefore sought to determine if SS RBCs played a role in monocyte activation. Blood samples were obtained from six normal adult volunteers, and SS RBCs were obtained from 12 adult patients homozygous for hemoglobin S. Plasma and buffy coat were removed, and 6 μl of SS RBCs were washed with sterile phosphate-buffered saline. After incubation with one million cells of the human promonocytic cell line U937 for 2 hours at 37°C, RBCs were lysed and total U937 RNA was isolated. Following reverse transcription, real-time PCR was performed using 200 nM primers for IL-1β, IL-6 or TNF-α, 50 ng cDNA and 12.5 μl of SYBR green 2× Super Mix in a 25 μl reaction volume. The amplification reaction was carried out over 40 cycles (10 min at 95°C, followed by a two-step cycling program of 15s at 95°C and 30s at 60°C). GAPDH was analyzed in parallel as an internal control. IL-1β, IL-6 and TNF-α U937 mRNA was significantly up-regulated after incubation with SS RBCs vs incubation with normal RBCs (relative to control without RBCs, relative mRNA levels: IL-1β: 2.77 ± 1.79 vs 0.82 ± 0.19, p=0.012; IL-6: 2.17 ± 0.94 vs 0.74 ± 0.34, p=0.003; and TNF-α: 3.01 ± 1.30 vs 1.09 ± 0.17, p=0.003). To identify the adhesion molecules involved in the interaction between SS RBCs and monocytes, 10 μg/ml soluble recombinant Lutheran (srLU) was incubated with U937 cells at 37°C for 2h. After incubation, total RNA was isolated from untreated and treated U937 cells. Real time PCR results showed that srLU treatment activated U937 cell TNF-α expression, (relative mRNA level 1.63 ± 0.02 vs 1.00 ± 0.01, p<0.0001, n=3) but not IL-1β or IL-6 expression (relative mRNA levels sLU treated vs untreated control, n=3-IL-1β: 1.24 ± 0.09 vs 1.00 ± 0.02, p=0.07; IL-6: 1.35 ± 0.30 vs 1.00 ± 0.01, p = 0.31). Neither soluble LW nor soluble CD44 had a similar effect. To verify that LU was involved in the interaction between SS RBCs and monocytes, inhibition assays were also performed. SS RBCs were incubated with anti-LU Ab for 1 h at 4°C to block RBC surface LU before incubation with U937 cells. Data from five paired treated and untreated samples showed decreased TNF-α mRNA expression after anti-LU antibody treatment (1.16 ± 0.14 vs 1.40 ± 0.12, p=0.005). Overall, these data suggest that monocytes can be activated by cell-cell interactions with SS RBCs to express the cytokines IL-1β, IL-6 and TNF-α. This activation is at least partially mediated through SS RBC Lutheran protein, which is over-expressed by these cells and is known to bind to leukocyte α4β1 integrin. These studies thus reveal that intact SS RBCs likely play a direct role in monocyte activation in SCD patients.

Iron chelation abrogates excessive formation of hydroxyl radicals and lipid peroxidation products in monocytes of patients with Eales' disease: Direct evidence using electron spin resonance spectroscopy

Purpose. Eales' disease (ED) is an idiopathic retinal vasculitis condition, which affects the retina of young adult males. Retinal changes include perivasculitis, non-perfusion and neovascularization. Disruption of blood-retinal barrier (BRB) is the common feature in intra-ocular inflammatory diseases. Disruption of BRB results in vascular hyper permeability and infiltration of circulating leukocytes into the retinal parenchyma. Monocyte (MC) activation results in oxidant thrust and subsequent tissue damage. This has been reported in various intra-ocular inflammatory diseases such as uveitis and Behcet's disease. However, there are no such reports available in ED. Hence in the present study we have investigated the role of MC activation and hydroxyl radicals (•OH) production and its possible involvement in promoting the development of retinal vasculitis in patients with ED. Methods. Twelve patients with ED and twelve healthy volunteers were recruited for the study. MC was separated from their peripheral blood. MC from patients with ED and control subjects was stimulated with phorbol-12-myristate - acetate (PMA) and •OH generated was analyzed using an electron spin resonance spectrometer (ESR). Superoxide dismutase (SOD), thiobarbituric acid reactive substances (TBARS), and iron content was determined in MC to assess the oxidant thrust and antioxidant defense. Results.•OH generation was elevated in MC from patients with ED, which coincided with diminished SOD activity and elevated levels of iron and TBARS, when compared with healthy control subjects. •OH generation was abrogated when MC from ED were co-incubated with PMA and iron chelators such as diethylenetriaminepentacetic acid (DTPA) and desferrioxamine. Iron chelation also inhibited TBARS accumulation restored SOD activity in MC of patients with ED. Conclusions. For the first time we have demonstrated the production of •OH generation in MC of patients with ED using ESR. Further we have shown the beneficial effect of iron chelation in mitigating free radical mediated changes in cellular metabolism. Based on our findings, we provide further evidence for the role of oxidant thrust in promoting retinal tissue damage in patients with ED.

Comparative Analysis of CD137 and LPS Effects on Monocyte Activation, Survival, and Proliferation

CD137 (ILA/4-1BB), a member of the TNF receptor family, regulates activation, survival and proliferation of primary human monocytes. Here we compare the activities of lipopolysaccharide (LPS), a classical and potent monocyte activator to that of CD137. LPS is a more potent activator of monocytes, as evidenced by a stronger induction of the proinflammatory cytokine IL-8. However, CD137 could further increase maximal cytokine induction by LPS, which points to separate signaling pathways for LPS and CD137. Also, expression of myc was only induced by the combination of CD137 and LPS. Expression of macrophage colony-stimulating factor is induced more potently by CD137, but an additive effect is obtained by the combination of CD137 and LPS. Monocyte/macrophage survival and proliferation is only induced by CD137. LPS counteracts both activities of CD137 via activation induced cell death. While LPS has a role in activation of monocytes in innate immunity, the CD137 receptor/ligand system seems to deliver an activating signal to monocyte in acquired immunity.

Activation of STAT5 by Lipopolysaccharide Through Granulocyte-Macrophage Colony-Stimulating Factor Production in Human Monocytes

LPS is a potent stimulator of monocytes, inducing many of their functions. Although the details of how LPS exerts such functions remain largely unknown, transcription factors such as nuclear factor-kappaB, nuclear factor-IL-6, and activator protein-1 have been shown to be involved in this process. However, to date it has been thought that no known STAT molecule plays a role in the activation of monocytes by LPS. In this study we examined whether some known STAT molecule is stimulated by LPS, based on the finding that a GAS motif sequence is conserved in the promoter regions of human, mouse, and rat cyclo-oxygenase-2 (COX-2) genes. Consequently, LPS induced activation of STAT5 in human monocytes, and this STAT5 activation occurred in an indirect way via granulocyte-macrophage CSF (GM-CSF) secreted by LPS-stimulated monocytes. Expression of COX-2 protein was partially reduced by treatment of anti-human GM-CSF Ab. Activation of STAT5 was inhibited by either IL-10 or dexamethasone (Dex), but not by aspirin. IL-10 blocked activation of STAT5 indirectly by suppressing GM-CSF production, while Dex inhibited this activation both directly and indirectly. Taken together, these results suggest that in addition to other transcription factors, STAT5 plays an important role in activation of monocytes by LPS, and that STAT5 is another target for IL-10 and Dex to inhibit COX-2 expression in activated monocytes.

Low bone mineral density and peripheral blood monocyte activation profile in calcium stone formers with idiopathic hypercalciuria.

Calcium stone formers (CaSF) with idiopathic hypercalciuria (IH) have been shown to have decreased bone mineral density (BMD). The mechanism of their bone loss remains obscure. Monokines like interleukin-1 beta (IL-1 beta), IL-6, tumor necrosis factor-alpha (TNF-alpha), and granulocyte macrophage stimulating factor (GM-CSF) are involved in bone remodeling, but only IL-1 excess has been incriminated in the bone loss of CaSF with IH. Therefore, to more precisely delineate the role of monocyte activation in the pathogenesis of bone loss in these patients, we studied the production of IL-1 beta, IL-6, TNF-alpha, and GM-CSF by unstimulated or lipopolysaccharide (LPS)-stimulated cultured peripheral blood monocytes in 15 CaSF with IH, in 10 CaSF with dietary calcium-dependent hypercalciuria (DH), and in 10 healthy controls (C). Cytokines were measured in the culture medium by sensitive enzyme-linked immunosorbent assay and vertebral BMD by single energy computed tomography. The decrease of vertebral BMD in IH compared with DH, was confirmed (Z score: -1.2 +/- 0.2 vs. -0.5 +/- 0.2; P = 0.04; Mann-Whitney). In the supernatant of unstimulated peripheral blood monocytes, IL-1 beta and TNF-alpha levels were higher in IH than in C (respectively, 40 +/- 21 vs. 7 +/- 1 pg/mL, P = 0.008 and 236 +/- 136 vs. 39 +/- 23 pg/mL, P = 0.03); those of GM-CSF were greater in IH than in DH and C (respectively, 52 +/- 27 vs. 6 +/- 2, P = 0.04 and 6 +/- 2 pg/mL, P = 0.01) and those of IL-6 were not significantly different among the groups. After in vitro stimulation by LPS (10 micrograms/mL), the levels of the various monokines were not significantly different. In IH patients, the post-LPS levels of IL-6 were negatively correlated to vertebral BMD (n = 15, Z = -1.97, P = 0.04; Spearman), whereas those of GM-CSF were positively related to vertebral BMD (n = 15, Z = 2.01, P = 0.04). In this study, calcium stone formers with IH have bone mineral decrease and a particular profile of peripheral blood monocytes activation. This latter is characterized by a spontaneously increased synthesis of IL-1 beta, TNF-alpha, and GM-CSF. Furthermore, post-LPS levels of IL-6 and GM-CSF are correlated with vertebral BMD. These results suggest that monocyte activation may be involved in the bone loss of calcium stone formers with IH.

CD23 and IgE expression during the human immune response to cutaneous leishmaniasis : Possible role in monocyte activation

Leishmania brasiliensis causes cutaneous leishmaniasis (CL) in humans. During this infection, a variety of inflammatory mediators are produced by T cells and monocytes/macrophages. In the present study, we analysed serum IgE levels and their correlation with in situ expression of the low affinity receptor for IgE (Fc epsilon RII/CD23) in patients infected with L. brasiliensis before and following therapy. These analyses were compared to in situ expression of tumour necrosis factor-alpha (TNF alpha), interleukin 3 (IL3), interferon-gamma (IFN gamma) and IL4. Disease-free individuals from the same endemic area sensitized with L. brasiliensis antigens were also included in this work. Our data indicate that during infection, serum levels of IgE and TNF alpha increased and correlated with elevated in situ expression of CD23, IL4 and TNF alpha mRNA. This expression disappeared following successful treatment, but persisted in patients resistant to anti-leishmania therapy. Patients resistant to therapy differed from other cases by a dramatic decrease in their in vivo expression of IFN gamma protein. Analysis of CD23 function in purified human monocytes indicated that this antigen mediates IgE/anti-IgE-dependent TNF alpha production. These data suggest a possible in vivo role of CD23 in acute immune responses in human CL.