Immunological Regulation Research Articles

The Osteoclast-Associated Receptor (OSCAR) Is a Novel Receptor Regulated by Oxidized Low-Density Lipoprotein in Human Endothelial Cells

Cross talks between the vascular and immune system play a critical role in vascular diseases, in particular in atherosclerosis. The osteoclast-associated receptor (OSCAR) is a regulator of osteoclast differentiation and dendritic cell maturation. Whether OSCAR plays a role in vascular biology and has an impact on atherogenic processes provoked by proinflammatory stimuli is yet unknown. We identified OSCAR on the surface of human primary endothelial cells. Stimulation of endothelial cells with oxidized low-density lipoprotein (oxLDL) caused a time- and dose-dependent induction of OSCAR, which was lectin-like oxidized LDL receptor 1 and Ca(2+) dependent. OSCAR was transcriptionally regulated by oxLDL as shown by OSCAR promoter analysis. Specific inhibition of the nuclear factor of activated T cells (NFAT) pathway prevented the oxLDL-mediated increase of endothelial OSCAR expression. As assessed by EMSA, oxLDL induced binding of NFATc1 to the OSCAR promoter. Notably, in vivo-modified LDL from patients with diabetes mellitus stimulated OSCAR mRNA expression in human endothelial cells. Furthermore, apolipoprotein E knockout mice fed a high-fat diet showed an enhanced aortic OSCAR expression associated with increased expression of NFATc1. In summary, OSCAR is expressed in vascular endothelial cells and is regulated by oxLDL involving NFATc1. Our data suggest that OSCAR, originally described in bone as immunological mediator and regulator of osteoclast differentiation, may be involved in cell activation and inflammation during atherosclerosis.

Linkage of Some Trace Elements, Peripheral Blood Lymphocytes, Inflammation, and Oxidative Stress in Patients Undergoing Either Hemodialysis or Peritoneal Dialysis

Changes in essential trace elements may affect the inflammatory and immunological state of patients on hemodialysis (HD) or peritoneal dialysis (PD). Therefore, we aimed to determine trace element content and markers of oxidative stress, inflammation, and immune status in HD and PD patients and to assess the relationships among these parameters. Patients on either HD (n = 20) or PD (n = 20) and age-, sex-, body mass index-matched healthy individuals (n = 20) were enrolled in the study. The trace elements zinc, copper, selenium, and iron; markers of oxidative stress thiobarbituric acid reactive substances (TBARS) and protein carbonyl levels; activities of antioxidant enzymes superoxide dismutase (SOD), glutathione peroxidase (GPx), and catalase; percentages of CD3 T lymphocytes and the subsets CD4 and CD8; the CD4/CD8 ratio; and C-reactive protein (CRP) were measured. All dialysis patients had low levels of albumin and hemoglobin. Significantly decreased percentages of CD3 and CD4 T lymphocytes and increased levels of CRP, TBARS, and carbonyl compounds were observed in HD patients. HD patients also had elevated erythrocyte SOD, lower GPx and catalase activities, and decreased levels of Se, Zn, and Fe in comparison to PD patients and healthy subjects. In addition, CRP was positively associated with TBARS and carbonyl levels, but was significantly inversely associated with Zn and Se levels. Positive correlations were found between T lymphocyte CD3 and CD4 percentages and Zn, Se, and Fe levels. There were significant decreases in T lymphocyte-related immunological regulation and increased inflammation and oxidative stress in dialysis patients. Essential trace element status was independently related to immune status, inflammation, and oxidative damage.

Matrix metalloproteinase-9 was involved in the immuno-modulatory defect of mesenchymal stem cell from chronic myeloid leukemia patients.

Overwhelming evidences on chronic myeloid leukemia (CML) indicate that patients harbor quiescent CML stem cells that are responsible for blast crisis. While the hematopoietic stem cell (HSC) origin of CML was first suggested over 30 years ago, recently CML-initiating cells beyond HSCs are also being investigated. We have previously isolated fetal liver kinase-1-positive (Flk1(+)) cells carrying the BCR/ABL fusion gene from the bone marrow of Ph(+) patients with hemangioblast property. In this study, we isolated CML patient-derived Flk1(+)CD31(-)CD34(-) mesenchymal stem cells (MSCs) and detected their biological characteristics and immunological regulation using fluorescence in situ hybridization (FISH) analysis, fluorescence activated cell sorting (FACS), enzyme-linked immunoadsorbent assay, mixed lymphocyte reaction assays; then we compared these characters with those of the healthy donors. CML patient-derived Flk1(+)CD31(-)CD34(-) MSCs had normal morphology, phenotype and karyotype while appeared impaired in immuno-modulatory function. The capacity of patient Flk1(+)CD31(-)CD34(-) MSCs to inhibit T lymphocyte activation and proliferation was impaired in vitro. CML patient-derived MSCs have impaired immuno-modulatory functions, suggesting that the dysregulation of hematopoiesis and immune response may originate from MSCs rather than hematopoietic stem cells (HSCs). MSCs might be a potential target for developing efficacious treatment for CML.

Orai1/CRACM1 overexpression suppresses cell proliferation via attenuation of the store-operated calcium influx-mediated signalling pathway in A549 lung cancer cells

Background Orai1/CRACM1 is a principal component of the store-operated calcium channels. Store-operated calcium influx is highly correlated with inflammatory reactions, immunological regulation, and cell proliferation. Epidermal growth factor (EGF), which plays an important role in the regulation of cell proliferation, can activate store-operated calcium channels. However, the consequences of Orai1/CRACM1 overexpression in EGF-mediated lung cancer cells growth are not known. Methods To investigate the role of Orai1/CRACM1 in EGF-mediated lung cancer cell proliferation, Orai1/CRACM1 plasmids were transfected into cells by lipofection. A cell proliferation assay, immunofluorescence staining, flow cytometry, and real-time polymerase chain reaction were employed to monitor cell proliferation. The calcium influx signals were investigated using a fluorescent-based calcium assay. Results Transfection of Orai1/CRACM1 plasmids resulted in the inhibition of EGF-mediated cell proliferation. ERK1/2 and Akt phosphorylation were inhibited by Orai1/CRACM1 overexpression. Expression of the cell cycle modulator p21 was induced in the Orai1/CRACM1-overexpressing cells, whereas the expression of cyclin D3 was reduced. Flow cytometry revealed that overexpression of Orai1/CRACM1 resulted in G0/G1 cell cycle arrest. Importantly, Orai1/CRACM1 overexpression significantly attenuated EGF-mediated store-operated calcium influx. In addition, application of 2-APB, a store-operated calcium channel inhibitor, resulted in the inhibition of EGF-mediated cancer cell proliferation. Conclusions We conclude that Orai1/CRACM1 overexpression attenuates store-operated Ca 2+ influx that in turn blocks EGF-mediated proliferative signaling and drives cell cycle arrest.

Does the classical M1/M2 dichotomy reflect the functional phenotypes of human decidual macrophages?

Evaluation of: Houser BL, Tilburgs T, Hill J, Nicotra ML, Strominger JL. Two unique human decidual macrophage populations. J. Immunol. 186(4), 2633–2642 (2011).Constituents of the mononuclear phagocyte system, including macrophages (Mφs), display a remarkable potential to acquire variable phenotypes that rely on cell-to-cell contact and exposure to soluble factors in the tissue microenvironment. Mφs are a major subpopulation of the immunocompetent cells residing in the uterine endometrium during pregnancy. Although the activities of Mφs at the human feto–maternal interface are thought to be critical for tissue remodeling and immunological regulation, the phenotypic differentiation and molecular mechanisms underlying their activities have not been fully elucidated. A recent publication by Houser and colleagues provides novel insights into the biology of decidual Mφs (dMφs). The authors report that dMφs can be subcategorized by their cell surface expression of CD11c (CD11cHI and CD11cLO). Gene-expression ar...

The effects of benzene and toluene on leukotactin-1-induced migration of EoL-1 cells

Benzene and toluene are volatile organic compounds (VOCs) that are produced from various building materials and may lead to sick building syndrome. In addition, these materials exert cytotoxic and carcinogenic effects in immune cells. To understand the effects of VOCs on immunological regulation, we investigated the effects of VOCs on cell migration in response to CC chemokines such as leukotactin-1 (Lkn-1), monocyte chemoattractant protein-1 (MCP-1), eotaxin, MIP-1α and RANTES in human eosinophilic leukemia EoL-1 cells. VOCs exerted no cytotoxicity against EoL-1 cells at concentrations ranging from 0.1 μM to 50 μM. A chemotaxis assay was conducted to evaluate the cell movement. The assay revealed that benzene and toluene differentially increased the migration of EoL-1 cells in response to Lkn-1, but not MCP-1, eotaxin, MIP-1α or RANTES. The expression of CCR1 and CCR3 binding to Lkn-1 were not altered by benzene and toluene. Additionally, the increased cell migration due to benzene and toluene was inhibited by PD98059, SB202190 and SP600125. Benzene and toluene also induced the phosphorylation of ERK, p38 mitogen-activated protein kinase (p38 MAPK) and JNK in a time-dependent manner. Overall, benzene and toluene influenced Lkn-1-induced migration of human eosinophilic cells via activation of MAPKs. These results suggest that benzene and toluene play a role as risk factors in the regulation of immune response. Furthermore, these findings provide a role for VOCs in the immunological processes involved in indoor air pollution-induced diseases.

Immunological regulation of trophoblast invasion

In investigating the immunological regulation of trophoblast invasion, emphasis is frequently placed on the constitution of the implantation site and its specific characteristics. However trophoblast cells are able of invading into not only the uterine tissue, but in the case of ectopic pregnancies also invade into other tissues, where they are actively involved in the creation of a beneficial local environment by expressing a range of membrane bound and soluble factors. The similarities and differences in trophoblast invasion in uterine and tubal pregnancies concerning trophoblast cells and maternal leukocytes and their interaction with each other are discussed in this review.

Leprosy Susceptibility: Genetic Variations Regulate Innate and Adaptive Immunity, and Disease Outcome

The past few years have been very productive concerning the identification of genes associated with leprosy. Candidate gene strategies using both case-control and family-based designs, as well as large-scale approaches such as linkage and gene-expression genomic scans and, more recently, genome-wide association studies, have refined and enriched the list of genes highlighting the most important innate and adaptive immune pathways associated with leprosy susceptibility or resistance. During the early events of host-pathogen interaction identified genes are involved in pattern recognition receptors, and mycobacterial uptake (TLRs, NOD2 and MRC1), which modulate autophagy. Another gene, LTA4H, which regulates the levels of lipoxin A4 and possibly interacts with lipid droplet-related events, also plays a role in the early immune responses to Mycobacterium leprae. Together, the activation of these pathways regulates cellular metabolism upon infection, activating cytokine production through NF-κB and vitamin D-vitamin D receptor pathways, while PARK2 and LRRK2 participate in the regulation of host-cell apoptosis. Concomitantly, genes triggered to form and maintain granulomas (TNF, LTA and IFNG) and genes involved in activating and differentiating T-helper cells (HLA, IL10, as well as the TNF/LTA axis and the IFNG/IL12 axis) bridge immunological regulation towards adaptive immunity. Subtle variations in these genes, mostly single nucleotide polymorphisms, alter the risk of developing the disease or the severity of leprosy. Knowing these genes and their role will ultimately lead to better strategies for leprosy prevention, treatment and early diagnosis. Finally, the same genes associated with leprosy were also associated with autoimmune (Crohn's disease, rheumathoid arthritis, psoriasis) or neurodegenerative diseases (Parkinson's and Alzheimer's). Thus, information retrieved using leprosy as a model could be valuable to understanding the pathogenesis of other complex diseases.

Spontaneous tolerance in kidney transplantation - an instructive, but very rare paradigm*

Recognition and induction of donor-specific immune tolerance have been a major focus of interest in transplantation immunology even before immunosuppressive treatment became available [1]. Several decades of research resulted in reliable protocols for induction of donor-specific tolerance in rodents, but translation of those to nonhuman primates and to patients was extremely challenging [2]. So far only the mixed chimerism approach, which is based on a combined transplantation of bone marrow and kidney from the same living donor, was successful in the clinical setting [3,4]. However, also in these protocols a long and intense conditioning including myelosuppressive treatment limits its routine clinical application. Despite the difficulty in inducing tolerance in humans, anecdotal cases of patients, who have removed themselves from immunosuppression without experiencing graft rejection, have been repeatedly described in the literature. Whether these cases are associated with a state of microchimerism remains a matter of debate [5,6]. Nonetheless, spontaneously tolerant patients represent a unique opportunity to the transplant community: on one hand a better characterization of these patients may provide fundamental knowledge about the immunological regulation of tolerance in humans, on the other hand it might help us to optimize immunosuppressive therapy after transplantation. For these reasons, a large international collaboration was initiated aiming at characterization of this rare group of patients. It was possible to identify a ‘tolerance footprint’ based on gene expression profiles in peripheral blood of spontaneously tolerant kidney and liver recipients [7,8]. However, it is currently unknown how frequently this situation occurs and how such patients should be managed. Obviously, nowadays most spontaneously tolerant patients undergo unnecessary immunosuppressive therapy with potentially deleterious side effects but no benefit, and they could profit from immunosuppression weaning. In this issue of Transplant International, Brouard et al. [9] present their results of the next logical step toward clinical application of tolerance profiling with the intention of identifying patients for an immunosuppression weaning protocol. A particular cohort of long-term stable kidney allograft recipients under cyclosporine-based Transplant International ISSN 0934-0874

Azithromycin acts as an immunomodulatory agent to suppress the expression of TREM-1 in Bacillus pyocyaneus-induced sepsis

Triggering receptor expressed on myeloid cells-1 (TREM-1) is highly expressed in inflammatory lesions caused by infectious agents such as bacteria and fungi but not in normal tissues or non-infectious lesions. There is evidence that macrolide antibiotics can act as immunomodulatory agents. The purpose of the current study was to determine whether azithromycin, a type of macrolide antibiotic, could reduce the expression of TREM-1 in Bacillus pyocyaneus-induced sepsis in vitro and in vivo. We treated THP-1 cells with LPS, LPS+TREM-1/Fc, and LPS+azithromycin for in vitro study. A B. pyocyaneus pyemia animal model was developed for in vivo study. RT-PCR, western blotting, and flow cytometry (FCM) were employed to determine the expression of TREM-1. ELISA analysis was utilized to examine the concentration of cytokines. Our results showed that azithromycin treatment did not reduce the level of LPS-induced TREM-1 mRNA in THP-1 cells. However, treatment with TREM-1/Fc fusion protein or azithromycin reduced the effect of LPS-stimulated TREM-1 protein expression. The expression of inflammatory factors (TNF-α, IL-6, and IL-1β) in cell culture supernatant and mouse serum of the TREM-1/Fc fusion protein-treated and azithromycin-treated groups were lower than that of the control group (p<0.05). The results from the animal sepsis model experiments demonstrated that the TREM-1 Fc/fusion protein and azithromycin treatment groups’ survival rates were significantly higher than in the control group. Analysis of serum inflammatory factors in septic mice revealed that the concentration of these factors was significantly lower than in the control group. Our results furthered the understanding of azithromycin function in immunological regulation and provided reliable data for new clinical applications.

The effect of Nasal Healing Spraying Agent on red cell immune function in mice

Objective To study the immunological regulation of Nasal Healing Spraying Agent (NHSA). Methods Test models were setup by irradiation. The models were administrated with NHSA by lavage and immune adherence of red cells was tested by chaplet experiment with blank and positive control. Results NHSA could increase Red Blood Cell-C3b Receptor Rosette (RBC-C3bRR) and reduce Red Blood Cell-Immune Complex Rosette (RBC-ICR) in mice. Compared with blank control group, the results in the high dose group and middle dose group were statistically significant (P<0.01). The result also showed that NHSA could elevate the quantity and activity of Red Blood Cell-C3b Receptor (RBC-C3bR) and reduce the Immune Complex (IC) to enhance the red cell immune function in mice effectively. Conclusion NHSA could elevate the RBC immunity function in mice and increase immunoregulatory function. Key words: Nasal Healing Spraying Agent (NHSA) ; Test for red blood cellular immunity in mice; Immunoregulatory function

A study on immunologic function in children with bronchial asthma

Objective To investigate the immune function of children with asthma for offering scientific evidence of immunological regulation in treatment children with asthma,. Methods Total-Ig, IgG,IgA, IgM, IgE, CD3, CD4, CD8, CD4/CD8 were detected in 77 cases with asthma. The results were compared with normal value of children of the same age in our hospital. The correlations were analyzed between CD3,CD4, CD8, CD4/CD8 with IgG, IgA, IgE. Results Total-Ig, IgC, IgA, CD4, CD4/CD8 were significantly lower in children with asthma than that of normal value(P＜0.01, respectively), CD3, CD8 were lower in children with asthma than normal value(P＜0.05, respectively), IgE was significantly higher in children with asthma than normal value(P＜0.01), IgM had no significant difference ( P＞0.05). There were positive correlation between CD3 with Total-Ig, IgG, IgA(P＜0.05). There were significant positive correlation between CD4, CD4/CD8 with Total - Ig, IgG, IgA(P＜0.01). There were significant negative correlation between CD8, CD4/CD8 with IgE (P＜ 0.01). Conclusion There were cellular immune functional defect and humoral immune functional disorder in children with asthma. Adjusting the immune function should be emphasized in treatment to children with asthma. Key words: Asthma; Children; T lymphocyte subsets; Immunoglobulin

Transduction of binding affinity by B lymphocytes: A new dimension in immunological regulation

To date, immunologists have operated with two primary paradigms governing the antibody response: (1) that affinity maturation is primarily dependent upon antigen-driven selection of both the germline and somatically amended repertoires, and (2) that antibody effector function is isotypically determined. The teleost model now suggests that these classical paradigms should be broadened to incorporate the ability of the B cell to transduce the strength of antigen recognition (affinity) into structural modifications of its antibody product, which, in turn, modulates the antibody's effector function. Although this relationship, thus far, has only been examined and demonstrated in the teleost, we find a number of the individual elements of this structural/functional relationship have been reported for mammalian IgM, which prompts future investigations into its universality. In sum, these findings suggest a heretofore unrecognized feature of B lymphocyte affinity discrimination, which transduces the affinity of antigen recognition into functionally modified antibodies.

Regulation of acute graft-versus-host disease by human umbilical cord blood derived stromal cells in haploidentical stem cell transplantation in mice through very late activation antigen-4

Human umbilical cord blood derived stromal cells (hUCBDSCs), a novel resource isolated by our laboratory, have been shown to exert an immunologic regulation. Very late activation antigen-4 (VLA-4) has been associated with graft-versus-host disease (GVHD). This study aimed to investigate the possible mechanism by in vitro co-cultured splenocytes of donor mice with hUCBDSCs and in haploidentical stem cell transplantation in mice with acute GVHD. Both hUCBDSCs and human bone marrow stromal cells (hBMSCs) elicited decreased lymphocyte expression of VLA-4, but this decrease was stronger with hUCBDSCs than with hBMSCs (p<0.05). Cotransplantation of bone marrow with hUCBDSCs significantly decreased the expression of VLA-4 compared with control mice (p<0.05). A significant reduction of VLA-4 labeling in the target organs of GVHD was evident in haploidentical mice cotransplanted with hUCBDSCs. Our study shows that hUCBDSCs may protect mouse recipients of haploidentical stem cell transplantation from aGVHD via downregulating the expression of VLA-4.

Immunological regulation of Chinese herb Guizhi Fuling Capsule on rat endometriosis model

To investigate the immunological regulation of Guizhi Fuling Capsule (GZFLC) on rat endometriosis. Twenty-seven rats, in which endometriotic implants were induced by transplanting autologous uterine tissue to the peritoneum, were randomly divided into three groups equally: (1) the GZFLC group of low dose (480 mg/kg/day); (2) the GZFLC group of high dose (1,920 mg/kg/day); and (3) the model group(saline solution). Another 10 rats were treated as sham operation group. After rats were treated for four weeks, we examined the alterations of implants volume, the percentage of CD4(+) T lympholeukocyte, the activity of NK cell and the expression of cytokines (MCP-1 and ICAM-1) on each group. Statistical analysis showed that posttreatment volumes were significantly reduced compared with pretreatment in GZFLC groups, whereas there was no significant change in the model group. The percentage of CD4(+) T lympholeukocyte and the activity of NK cell in GZFLC groups significantly increased to the level of the sham group compared with the model. RT-PCR and immunohistochemistry showed that the endometria of the sham operation and treatment groups were similar on expression level of MCP-1 and ICAM-1. GZFLC plays an important role in the regression of endometriotic implants by immunological regulation in the rat model.

Interleukin-19 Is a Negative Regulator of Innate Immunity and Critical for Colonic Protection

The cytokine, interleukin (IL)-19, is a member of the IL-10 family that includes IL-20, IL-22, IL-24, and IL-26. Recent studies have shown that IL-19 is produced by keratinocytes, epithelial cells, macrophages, and B-cells. Little is known about the exact biological role of IL-19 in immunological regulation, although there is an increasing body of data demonstrating that IL-19 is associated with the development of Th2 responses and the pathogenesis of psoriasis. In this review, I shall attempt to discuss current knowledge about the role of IL-19 on macrophages and the potential role in inflammatory bowel disease.

982 Hypouricemia in the Course of Neoplastic Disease of Children

Urate can be an antioxidant and might provide immunological regulation. Hyperuricemia is regarded as the most important risk factor for the development of gout. Nevertheless, hypouricemia has rarely received attention from researchers. We previously studied 104 patients who were undergoing chemotherapy for neoplastic disease in our hospital during 2002-2006 and detected hypouricemia in 62 of them (59.6%), particularly in patients with a solid tumor showing high mortality (42nd Japanese Pediatric Nephrology Congress Meeting 2007). No report describes effects of hypouricemia on the condition of the patients. Therefore, we studied the relation between clinical symptoms and hypouricemia during chemotherapy for neoplastic diseases in childhood.We found 52 patients who had hypouricemia (< 2.0 mg/dl) during hospitalization in our institute during February 2008 - October 2009. Of the 52 patients, 38 had neoplastic disease, 7 had neurologic diseases, 5 were newborns, and 2 were metabolic diseases. No patient had renal disease. Among the 38 patients with neoplastic disease were 21 reporting episodes of infectious diseases, and 17 patients who complained of digestive symptoms. They tended to have such episodes when the level of serum uric acid was low. It is noteworthy that eight patients died.Patients with neoplastic diseases frequently have hypouricemia because of undernutrition and/or renal tubular damage attributable to treatment with antineoplastic agents. Hypouricemia might influence prognoses because of a lack of antioxidant or immunological regulation activities.

Immunologic regulation of trophoblast invasion

New theories on the regeneration of ischemic vasculature have emerged indicating a pivotal role of adult stem cells. The aim of this study was to investigate homing and hemodynamic effects of circulating bone marrow-derived mesenchymal stem cells (MSCs) in a critically ischemic murine skin flap model.Bone marrow-derived mesenchymal stem cells (Lin−CD105+) were harvested from GFP+-donor mice and transferred to wildtype C57BL/6 mice. Animals receiving GFP+-fibroblasts served as a control group. Laser scanning confocal microscopy and intravital fluorescence microscopy were used for morphological analysis, monitoring and quantitative assessment of the stem cell homing and microhemodynamics over two weeks. Immunohistochemical staining was performed for GFP, eNOS, iNOS, VEGF. Tissue viability was analyzed by TUNEL-assay.We were able to visualize perivascular homing of MSCs in vivo. After 4 days, MSCs aligned along the vascular wall without undergoing endothelial or smooth muscle cell differentiation during the observation period. The gradual increase in arterial vascular resistance observed in the control group was abolished after MSC administration (P < 0.01). At capillary level, a strong angiogenic response was found from day 7 onwards. Functional capillary density was raised in the MSC group to 197% compared to 132% in the control group (P < 0.01). Paracrine expression of VEGF and iNOS, but not eNOS could be shown in the MSC group but not in the controls.In conclusion, we demonstrated that circulating bone marrow-derived MSCs home to perivascular sites in critically ischemic tissue, exhibits paracrine function and augment microhemodynamics. These effects were mediated through arteriogenesis and angiogenesis, which contributed to vascular regeneration.

The pro-apoptotic effect of hydroquinone in human neutrophils and eosinophils

Hydroquinone (HQ) is a benzene metabolite that is involved in hematopoiesis via its accumulation into bone marrow. HQ also acts as a toxic agent that influences various immune responses. Both neutrophils and eosinophils function as important leukocytes in immunological regulation and immune diseases. In this study, we examined the toxic effects of HQ on the apoptosis of human neutrophils and eosinophils isolated from the blood of healthy donors. HQ markedly increased the apoptosis of neutrophils and eosinophils in a concentration- and a time-dependent manner. The pro-apoptotic effect is involved in activation of caspase 9 and caspase 3. Reactive oxygen species (ROS) production was enhanced after HQ treatment in a dose-dependent manner. In addition, HQ upregulated the release of IL-8 and MCP-1 from neutrophils and eosinophils, respectively. Taken together, the results of this study demonstrated that HQ strongly induces the apoptosis of neutrophils and eosinophils through the caspase 9/3-dependent pathway and the increased ROS production. HQ exerts a cytotoxic effect in human neutrophils and eosinophils and may impair the regulation of immune responses.

Activation of the Transcription Factor FosB/Activating Protein-1 (AP-1) Is a Prominent Downstream Signal of the Extracellular Nucleotide Receptor P2RX7 in Monocytic and Osteoblastic Cells*

Activation of the ionotropic P2RX7 nucleotide receptor by extracellular ATP has been implicated in modulating inflammatory disease progression. Continuous exposure of P2RX7 to ligand can result in apoptosis in many cell types, including monocytic cells, whereas transient activation of P2RX7 is linked to inflammatory mediator production and the promotion of cell growth. Given the rapid hydrolysis of ATP in the circulation and interstitial space, transient activation of P2RX7 appears critically important for its action, yet its effects on gene expression are unclear. The present study demonstrates that short-term stimulation of human and mouse monocytic cells as well as mouse osteoblasts with P2RX7 agonists substantially induces the expression of several activating protein-1 (AP-1) members, particularly FosB. The potent activation of FosB after P2RX7 stimulation is especially noteworthy considering that little is known concerning the role of FosB in immunological regulation. Interestingly, the magnitude of FosB activation induced by P2RX7 stimulation appears greater than that observed with other known inducers of FosB expression. In addition, we have identified a previously unrecognized role for FosB in osteoblasts with respect to nucleotide-induced expression of cyclooxygenase-2 (COX-2), which is the rate-limiting enzyme in prostaglandin biosynthesis from arachidonic acid and is critical for osteoblastic differentiation and immune behavior. The present studies are the first to link P2RX7 action to FosB/AP-1 regulation in multiple cell types, including a role in nucleotide-induced COX-2 expression, and support a role for FosB in the control of immune and osteogenic function by P2RX7.