[show abstract][hide abstract] ABSTRACT: γδ T cells have been shown to stimulate the recruitment and activation of neutrophils through the release of a range of cytokines and chemokines. Here, we investigated the reverse relationship, showing that human neutrophils suppress the function of human blood γδ T cells. We show that the upregulation of CD25 and CD69 expression, the production of IFN-γ, and the proliferation of γδ T cells induced by HMBPP are inhibited by neutrophils. Spontaneous activation of γδ T cells in culture is also suppressed by neutrophils. We show that inhibitors of prostaglandin E2 and arginase I do not exert any effect, although in contrast, catalase prevents the suppression of γδ T cells induced by neutrophils, suggesting the participation of neutrophil-derived ROS. We also show that the ROS-generating system xanthine/xanthine oxidase suppresses γδ T cells in a similar fashion to neutrophils, while neutrophils from chronic granulomatous disease patients only weakly inhibit γδ T cells. Our results reveal a bidirectional cross-talk between γδ T cells and neutrophils: while γδ T cells promote the recruitment and the activation of neutrophils to fight invading pathogens, neutrophils in turn suppress the activation of γδ T cells to contribute to the resolution of inflammation. This article is protected by copyright. All rights reserved.
European Journal of Immunology 11/2013; · 4.97 Impact Factor
[show abstract][hide abstract] ABSTRACT: Asthma PostersSESSION TYPE: Original Investigation PosterPRESENTED ON: Wednesday, October 30, 2013 at 01:30 PM - 02:30 PMPURPOSE: The aim of this study was to compare the levels of IL-8 and IL17-A in sputum samples from patients admitted for an asthma exacerbation classified in two different categories based on WHO criteria: a) Difficult to treat severe asthma (DTTSA) due to non-adherence or accessibility issues and b) Treatment resistant severe asthma (TRSA), in order to understand the role of these molecules in the pathogenesis of the diverse presentations of the disease. The third category, Untreated severe asthma was not found between our patients.METHODS: Cross sectional prospective observational study of admissions to a respiratory hospital. DTTSA and TRSA were diagnosed according to WHO criteria; FeNO and spirometry were first measured, followed by assisted sputum. Samples were processed with dithiotreitol, cytospined and stained. Supernatants were stored at -80°C. IL-8 and IL17-A were measured by ELISA. Data were expressed as the mean ± SEM and were analyzed using a non-parametric Mann Whitney test.RESULTS: We recruited 12 patients with TRSA (9 of them never smoked and 2 were past-smokers); and 38 with DTTSA (24 of them never smoked, 6 were past-smokers and 7 were active smokers). No significant differences were found between initial FEV1or FeNO between both groups: 775.5±86.L/S and 37.7±10.8 ppb in TRSA vs 911.4±60.4 L/S and 39.4±5.2 ppb in DTTSA patients. A significant increase of neutrophils in sputum samples from patients with TRSA vs DTTSA (32.5±7.5% vs 14.8±2.0%, p<0.05) was found. Moreover, 25% of TRSA but only 2.6% of DTTSA were neutrophilics. Sputum levels of IL-8 were higher in TRSA compared with DTTSA patients (724.8±47.1pg/ml vs 419.5±80.1pg/ml, p<0.05). No differences were found when the levels of IL17-A were analyzed (13.6±4.6pg/ml vs 14.1±3.3pg/ml respectively).CONCLUSIONS: Consistent with previous data, we did not find differences in FeNO and FEV-1 between TRSA and DTTSA patients. A significant increase of IL-8, but not IL-17A, was found in the sputum of TRSA vs DTTSA patients.CLINICAL IMPLICATIONS: This work contributes to understand the role of IL-8 in the pathogenesis of TRSA.DISCLOSURE: The following authors have nothing to disclose: Glenda Ernst, Auteri Santiago, Fabian Caro, Daniel Colodenco, Ricardo Del Olmo, Martin Fernandez, Jorge Geffner, Dora Lombardi, Guillermo Menga, Jose Luis Morero, Hugo Neffen, Santiago Rossi, Eduardo SchiaviNo Product/Research Disclosure Information.
[show abstract][hide abstract] ABSTRACT: Neutrophils are essential players in acute inflammatory responses. Upon stimulation, neutrophils activate NADPH oxidase, generating an array of reactive oxygen species (ROS). Interleukin-1β (IL-1β) is a major pro-inflammatory cytokine synthesized as a precursor which has to be proteolytically processed to become biologically active. The role of ROS in IL-1β processing is still controversial and has not been previously studied in neutrophils. We report here that IL-1β processing in human neutrophils is dependent on caspase-1 and on the serine-proteases elastase and/or proteinase-3. NADPH oxidase-deficient neutrophils activated caspase-1 and did not exhibit differences in NALP3 expression, indicating that ROS are neither required for inflammasome activation nor for its priming, as has been reported for macrophages. Strikingly, ROS exerted opposite effects on the processing and secretion of IL-1β; whereas ROS negatively controlled caspase-1 activity, as reported in mononuclear phagocytes, ROS were found to be necessary for the exportation of mature IL-1β out of the cell, a role never previously described. The complex ROS-mediated regulation of neutrophil IL-1β secretion might constitute a physiological mechanism to control IL-1β-dependent inflammatory processes where neutrophils play a crucial role. This article is protected by copyright. All rights reserved.
European Journal of Immunology 08/2013; · 4.97 Impact Factor
[show abstract][hide abstract] ABSTRACT: Neutrophils not only play a critical role as a first line of defense against bacteria and fungi infections but also contribute to tissue injury associated with autoimmune and inflammatory diseases. Neutrophils are rapidly and massively recruited from the circulation into injured tissues displaying an impressive arsenal of toxic weapons. Although effective in their ability to kill pathogens, these weapons were equally effective to induce tissue damage. Therefore, the inflammatory activity of neutrophils must be regulated with exquisite precision and timing, a task mainly achieved through a complex network of mechanisms, which regulate neutrophil survival. Neutrophils have the shortest lifespan among leukocytes and usually die via apoptosis although new forms of cell death have been characterized over the last few years. The lifespan of neutrophils can be dramatically modulated by a large variety of agents such as cytokines, pathogens, danger-associated molecular patterns as well as by pharmacological manipulation. Recent findings shed light about the complex mechanisms responsible for the regulation of neutrophil survival in different physiological, pathological, and pharmacological scenarios. Here, we provide an updated review on the current knowledge and new findings in this field and discuss novel strategies that could be used to drive the resolution of neutrophil-mediated inflammatory diseases.
Seminars in Immunopathology 02/2013; · 5.38 Impact Factor
[show abstract][hide abstract] ABSTRACT: Macrophages are one of the most important HIV-1 target cells. Unlike CD4(+) T cells, macrophages are resistant to the cytophatic effect of HIV-1. They are able to produce and harbor the virus for long periods acting as a viral reservoir. Candida albicans (CA) is a commensal fungus that colonizes the portals of HIV-1 entry, such as the vagina and the rectum, and becomes an aggressive pathogen in AIDS patients. In this study, we analyzed the ability of CA to modulate the course of HIV-1 infection in human monocyte-derived macrophages. We found that CA abrogated HIV-1 replication in macrophages when it was evaluated 7 days after virus inoculation. A similar inhibitory effect was observed in monocyte-derived dendritic cells. The analysis of the mechanisms responsible for the inhibition of HIV-1 production in macrophages revealed that CA efficiently sequesters HIV-1 particles avoiding its infectivity. Moreover, by acting on macrophages themselves, CA diminishes their permissibility to HIV-1 infection by reducing the expression of CD4, enhancing the production of the CCR5-interacting chemokines CCL3/MIP-1α, CCL4/MIP-1β, and CCL5/RANTES, and stimulating the production of interferon-α and the restriction factors APOBEC3G, APOBEC3F, and tetherin. Interestingly, abrogation of HIV-1 replication was overcome when the infection of macrophages was evaluated 2-3 weeks after virus inoculation. However, this reactivation of HIV-1 infection could be silenced by CA when added periodically to HIV-1-challenged macrophages. The induction of a silent HIV-1 infection in macrophages at the periphery, where cells are continuously confronted with CA, might help HIV-1 to evade the immune response and to promote resistance to antiretroviral therapy.
PLoS ONE 01/2013; 8(8):e72814. · 3.73 Impact Factor
[show abstract][hide abstract] ABSTRACT: Bacterial superantigens (SAgs) are exotoxins produced mainly by Staphylococcus aureus and Streptococcus pyogenes that can cause toxic shock syndrome (TSS). According to current paradigm, SAgs interact directly and simultaneously with T cell receptor (TCR) on the T cell and MHC class II (MHC-II) on the antigen-presenting cell (APC), thereby circumventing intracellular processing to trigger T cell activation. Dendritic cells (DCs) are professional APCs that coat nearly all body surfaces and are the most probable candidate to interact with SAgs. We demonstrate that SAgs are taken up by mouse DCs without triggering DC maturation. SAgs were found in intracellular acidic compartment of DCs as biologically active molecules. Moreover, SAgs co-localized with EEA1, RAB-7 and LAMP-2, at different times, and were then recycled to the cell membrane. DCs loaded with SAgs are capable of triggering in vitro lymphocyte proliferation and, injected into mice, stimulate T cells bearing the proper TCR in draining lymph nodes. Transportation and trafficking of SAgs in DCs might increase the local concentration of these exotoxins where they will produce the highest effect by promoting their encounter with both MHC-II and TCR in lymph nodes, and may explain how just a few SAg molecules can induce the severe pathology associated with TSS.
PLoS ONE 01/2013; 8(6):e66244. · 3.73 Impact Factor
[show abstract][hide abstract] ABSTRACT: Seminal plasma is not just a carrier for spermatozoa. It contains high concentrations of cytokines, chemokines, and other biological compounds that are able to exert potent effects on the immune system of the receptive partner. Previous studies have shown that semen induces an acute inflammatory response at the female genital mucosa after coitus. Moreover, it induces regulatory mechanisms that allow the fetus (a semiallograft) to grow and develop in the uterus. The mechanisms underlying these regulatory mechanisms, however, are poorly understood. In this study, we show that seminal plasma redirects the differentiation of human dendritic cells (DCs) toward a regulatory profile. DCs differentiated from human monocytes in the presence of high dilutions of seminal plasma did not express CD1a but showed high levels of CD14. They were unable to develop a fully mature phenotype in response to LPS, TNF-α, CD40L, Pam2CSK4 (TLR2/6 agonist), or Pam3CSK4 (TLR1/2 agonist). Upon activation, they produced low amounts of the inflammatory cytokines IL-12p70, IL-1β, TNF-α, and IL-6, but expressed a high ability to produce IL-10 and TGF-β. Inhibition of the PG receptors E-prostanoid receptors 2 and 4 prevented the tolerogenic effect induced by seminal plasma on the phenotype and function of DCs, suggesting that E-series PGs play a major role. By promoting a tolerogenic profile in DCs, seminal plasma might favor fertility, but might also compromise the capacity of the receptive partner to mount an effective immune response against sexually transmitted pathogens.
The Journal of Immunology 10/2012; · 5.52 Impact Factor
[show abstract][hide abstract] ABSTRACT: SESSION TYPE: ILD - Bench to BedsidePRESENTED ON: Wednesday, October 24, 2012 at 02:45 PM - 04:15 PMPURPOSE: Interstitial lung diseases (ILD) are a heterogeneous group of illnesses characterized by variable degrees of fibrosis and an imbalance of pro-inflammatory cytokines. Hyaluronan (HA) is a glycosaminoglycan which plays an important role in certain inflammatory diseases. We previously reported a significant increase in HA levels in bronchoalveolar lavage (BAL) from ILD patients compared with healthy subjects. In vitro studies have shown that HA induces the expression of pro-inflammatory genes in alveolar macrophages. In the present study we quantified HA and cytokine levels in BAL and evaluated lung function parameters in ILD patients and control subjects.METHODS: Patient population: idiopathic pulmonary fibrosis/usual interstitial pneumonia (IPF/UIP: n=6); non-specific interstitial pneumonia (NSIP: n=4); sarcoidosis (n= 6); hypersensitivity pneumonitis (HP: n=12) and pulmonary Langerhans cell histiocytosis (Hx: n=3). Controls were individuals with healthy lungs (n=13). Cytokine and HA levels in BAL samples were determined by enzyme immunoassay. Pulmonary function tests included lung diffusing capacity for carbon monoxide (DLCO) and alveolar volume (VA).RESULTS: We found a significant increase of HA levels in BAL from patients with NSIP (2.057,00 ± 419,90 ng/mL, p<0,01); HP (1.975,00 ± 199,30 ng/mL, p<0,001); Sarcoidosis (1.839,00 ± 47,90 ng/mL, p<0,01) and Hx (1.918,00 ± 404,20 ng/mL; p<0,05) compared with controls (623,50±48,10 ng/mL). However, there were not differences between IPF/UIP (961,90 ± 118,79 ng/mL) and the control group. When we analyzed the levels of proinflammatory cytokines (IL-1β, IL-6, TNF-α and IL-8) in BAL we observed no significant differences between ILD patients and control subjects. However, there was a correlation between IL-6 and HA levels in BAL (Spearman r = 0,57 and p<0,01). Moreover, we observed an inverse correlation between the concentrations of HA and lung functional parameters: patients with higher concentrations of HA had lower values of DLCO/VA (Spearman r = -0,28).CONCLUSIONS: Our results show a relationship between BAL HA levels and the severity of ILD.CLINICAL IMPLICATIONS: HA could be a marker of ILD progression.DISCLOSURE: The following authors have nothing to disclose: Glenda Ernst, Pedro Grynblat, Carolina Jancic, Auteri Santiago, Fernando Galíndez, Juan Carlos Moncalvo, Jorge Geffner, Silvia HajosNo Product/Research Disclosure InformationMaría Ferrer Hospital, Buenos Aires, Argentina.
[show abstract][hide abstract] ABSTRACT: SESSION TYPE: ILD PostersPRESENTED ON: Wednesday, October 24, 2012 at 01:30 PM - 02:30 PMPURPOSE: Idiopathic Pulmonary Alveolar Proteinosis (PAP) is a rare illness characterized by the accumulation of phospholipids, surfactants and a high cellularity in the alveolar space as well as by the presence of antibodies anti-GM-CSF in the patient serum. The aim of this study was to determine the levels of IL-8 in bronchoalveolar lavage fluid (BALF) from patients with PAP, patients with other Interstitial Lung Diseases (ILDs), and healthy subjects.METHODS: PAP was confirmed by lung biopsies. In 3 patients we detected by ELISA the presence of antibodies anti-GM-CSF working with serum samples diluted 1:750. IL-8 was determined by ELISA in BALF from 13 healthy subjects (to whom bronchoscopy was performed as follow up for post-intubation tracheal stenosis surgery), BALF from 31 patients with ILDs with histopathology confirmation (idiopathic pulmonary fibrosis/usual interstitial pneumonia (IPF/UIP: n=6); non-specific interstitial pneumonia (NSIP: n; =4); hypersensitivity pneumonitis (HP: n=12), sarcoidosis (n= 6); pulmonary Langerhans cell histiocytosis (Hx: n=3), and BALF from 4 patients with PAP.RESULTS: We found a significant increase in IL-8 levels in BALF from patients with PAP compared with either healthy subjects (769.9 ± 133.2 vs 64.9 ± 28.5 pg/mL; p<0.05), or ILD patients (UIP/FPI: 111.0 ± 33.0 pg/mL; NSIP: 68.6 ± 23.3 pg/mL; HP: 59.3 ± 20.8 pg/mL; sarcoidosis: 112.6 ± 77.65 pg/mL and Hx: 93.7 ± 48.3 pg/mL, p<0.05). By contrast, we found no differences among the different groups in the BALF levels of the proinflammatory cytokines IL-1β, IL-6 and TNF-α.CONCLUSIONS: We found that IL-8 levels in BALF from patients with PAP are significantly increased compared with healthy subjects and patients with others ILD.CLINICAL IMPLICATIONS: The presence of elevated levels of IL-8 may contribute to the recruitment of inflammatory cells observed in PAP.DISCLOSURE: The following authors have nothing to disclose: Glenda Ernst, Carolina Jancic, Fabían Caro, Patricia Vujacich, Gabriela Tabaj, Artemio Garcia, Silvia Hajos, Jorge Geffner, Pedro GrynblatNo Product/Research Disclosure InformationMaría Ferrer Hospital, Buenos Aires, Argentina.
[show abstract][hide abstract] ABSTRACT: SESSION TYPE: ILD PostersPRESENTED ON: Wednesday, October 24, 2012 at 01:30 PM - 02:30 PMPURPOSE: Recruitment of macrophages in BAL is associated to the development of inflammatory processes during the course of Interstitial Lung Diseases (ILD). However, the mechanisms responsible for macrophage recruitment are poorly defined. Hyaluronan (HA) is a glycosaminoglycan found at high concentrations in BAL from ILD patients. Hyaluronan can regulate different cell functions by interacting with different receptors, among them, CD44 and RHAAM. In the present study we analyzed whether HA was able to induce the chemotaxis of BAL macrophages from ILD patients and the involvement of CD44 and RHAAM in this response.METHODS: Alveolar macrophages were purified from BAL recovered from ILD patients (n=31) by adherence on plastic tissue culture dishes. Migration was measured using a transwell system, in which macrophages were seeded on the upper compartment chamber, and RPMI (diluent), HA (2 μg/mL) or BAL from ILD patients were added into the lower compartment chamber, either in the presence or absence of hialuronidase (5U/mL). To evaluate the role of CD44 and RHAAM in cell migration, macrophages were preincubated with saturating concentrations of specific blocking monoclonal antibodies, before the onset of the migration assay. The results were expressed as a migration index: migration of macrophages in response to HA or BAL/migration of macrophages toward culture medium.RESULTS: We found that both HA and BAL from ILD patients induced the migration of macrophages: migration index = 2.39 ± 0.12 and 2.64 ± 0.43, respectively (p<0.05). Of note, the presence of hialuronidase abrogated the migration response induced by BAL from ILD patients: % inhibition >95, n=4. Treatment of macrophages with antibodies directed to CD44, markedly decreased the migratory response induced by HA: 1,24 ± 0.08 vs 2.40 ± 0.12 for anti-CD44-treated vs untreated macrophages, respectively, p<0.05). Anti-RHAAM antibodies did not mediate any effect.CONCLUSIONS: BAL from patients with ILD induces the migration of macrophages through a mechanism strongly dependent on the presence of HA.CLINICAL IMPLICATIONS: CD44 could be a novel therapeutic target involved in the recruitment of inflammatory cells in the lung of ILD patientsDISCLOSURE: The following authors have nothing to disclose: Glenda Ernst, Carolina Jancic, Auteri Santiago, Fabían Caro, Fernando Galíndez, Jorge Geffner, Silvia Hajos, Pedro GrynblatNo Product/Research Disclosure InformationMaría Ferrer Hospital, Buenos Aires, Argentina.
[show abstract][hide abstract] ABSTRACT: Dendritic cells (DCs), which are biased toward a tolerogenic profile, play a pivotal role in tissue-remodeling processes and angiogenesis at the maternal-fetal interface. Here, we analyzed the effect of trophoblast cells on the functional profile of DCs to gain insight on the tolerogenic mechanisms underlying the human placental-maternal dialog at early stages of gestation.
DCs were differentiated from peripheral blood monocytes obtained from fertile women (n = 21), in the presence of interleukin (IL)-4 and granulocyte-macrophage colony-stimulating factor during 5 days in culture. Then, DCs were cultured with trophoblast cells (Swan-71 cell line obtained from normal cytotrophoblast, at 7 weeks) for 24 h and for an additional 24 h in the absence or presence of lipopolysaccharide (LPS) from Escherichia coli. DCs were recovered and used for flow cytometry, enzyme-linked immunosorbent assay, RT-PCR and suppression and migration assays.
Trophoblast cells significantly prevented the increase in CD83 expression induced by LPS without affecting the expression of CD86, CD40 and human leukocyte antigen-DR (P < 0.05). Trophoblast cells significantly decreased the production of IL-12p70 and tumor necrosis factor-α, while it increased the production of IL-10 (P < 0.05). No changes were observed in the production of IL-6 and monocyte chemotactic protein-1. The culture of DCs with trophoblast cells, also suppressed the stimulation of the allogeneic response triggered by LPS (P < 0.05). Conditioned DCs were able to increase the frequency of CD4 + CD25 + Foxp3 cells and this effect was accompanied by an increase in indoleamine 2, 3-dioxygenase expression in DCs (P < 0.05).
The interaction of DCs with trophoblast cells promotes the differentiation of DCs into cells with a predominantly tolerogenic profile that could contribute to a tolerogenic microenvironment at the maternal-fetal interface.
Human Reproduction 06/2012; 27(9):2598-606. · 4.67 Impact Factor
[show abstract][hide abstract] ABSTRACT: Angiotensin II (AngII), the main effector peptide of the renin-angiotensin system (RAS), participates in multiple biological processes, including cell growth, apoptosis, and tissue remodeling. Since AngII activates, in different cell types, signal transducing pathways that are critical for mammary gland postlactational regression, we investigated the role of the RAS during this process. We found that exogenous administration of AngII in mammary glands of lactating Balb/c mice induced epithelium apoptosis [2.9±0.5% (control) vs. 9.6±1.1% (AngII); P < 0.001] and activation of the proapoptotic factor STAT3, an effect inhibited by irbesartan, an AT(1) receptor blocker. Subsequently, we studied the expression kinetics of RAS components during involution. We found that angiotensin-converting enzyme (ACE) mRNA expression peaked 6 h after weaning (5.7-fold; P<0.01), while induction of angiotensinogen and AT(1) and AT(2) receptors expression was detected 96 h after weaning (6.2-, 10-, and 6.2-fold increase, respectively; P<0.01). To assess the role of endogenously generated AngII, mice were treated with losartan, an AT(1) receptor blocker, during mammary involution. Mammary glands from losartan-treated mice showed activation of the survival factors AKT and BCL-(XL), significantly lower LIF and TNF-α mRNA expression (P<0.05), reduced apoptosis [12.1±2.1% (control) vs. 4.8±0.7% (losartan); P<0.001] and shedding of epithelial cells, inhibition of MMP-9 activity in a dose-dependent manner (80%; P<0.05; with losartan IC(50) value of 6.9 mg/kg/d] and lower collagen deposition and adipocyte invasion causing a delayed involution compared to vehicle-treated mice. Furthermore, mammary glands of forced weaned AT(1A)- and/or AT(1B)-deficient mice exhibited retarded apoptosis of epithelial cells [6.3±0.95% (WT) vs. 3.3±0.56% (AT(1A)/AT(1B) DKO); P<0.05] with remarkable delayed postlactational regression compared to wild-type animals. Taken together, these results strongly suggest that AngII, via the AT(1) receptor, plays a major role in mouse mammary gland involution identifying a novel role for the RAS. angiotensin system.
The FASEB Journal 01/2012; 26(5):1982-94. · 5.70 Impact Factor
[show abstract][hide abstract] ABSTRACT: Recently, it was shown that peripheral blood FOXP3+CD4+ T cells are composed of three phenotypic and functionally distinct subpopulations. Two of them having in vitro suppressive effects were characterized as resting Treg cells (rTregs) and activated Treg cells (aTregs). A third subset, identified as FOXP3+ non-Tregs, does not display any suppressor activity and produce high levels of Th1 and Th17 cytokines upon stimulation. In the present study we focus on the characteristics of these three subsets of FOXP3+CD4+ T cells in untreated HIV-1-infected patients. We found that the absolute counts of rTregs, aTregs and FOXP3+ non-Tregs were reduced in HIV-1 patients compared with healthy donors. The relative frequency of rTregs and aTregs was similar in HIV-1 patients and healthy donors, while the frequency of FOXP3+ non-Tregs was significantly higher in HIV-1 patients, reaching a maximum in those patients with the lower values of CD4 counts. Contrasting with the observations made in FOXP3- CD4+ T cells, we did not find a negative correlation between the number of rTregs, aTregs or FOXP3+ non-Tregs and virus load. Studies performed with either whole PBMCs or sorted aTregs and FOXP3+ non-Tregs cells showed that these two populations of FOXP3+ T cells were highly permissive to HIV-1 infection. Upon infection, FOXP3+ non-Tregs markedly down-regulates its capacity to produce Th1 and Th17 cytokines, however, they retain the ability to produce substantial amounts of Th2 cytokines. This suggests that FOXP3+ non-Tregs might contribute to the polarization of CD4+ T cells into a Th2 profile, predictive of a poor outcome of HIV-1-infected patients.
PLoS ONE 01/2012; 7(12):e52580. · 3.73 Impact Factor
[show abstract][hide abstract] ABSTRACT: The development of acidic environments is a hallmark of inflammatory processes of different etiology. We have previously shown that transient exposure to acidic conditions, similar to those encountered in vivo, induces the activation of neutrophils and the phenotypic maturation of dendritic cells. We here report that extracellular acidosis (pH 6.5) selectively stimulates the production and the secretion of IL-1β by human monocytes without affecting the production of TNF-α, IL-6 and the expression of CD40, CD80, CD86, and HLA-DR. Stimulation of IL-1β production by pH 6.5-treated monocytes was shown to be dependent on caspase-1 activity, and it was also observed using peripheral blood mononuclear cells instead of isolated monocytes. Contrasting with the results in monocytes, we found that pH 6.5 did not stimulate any production of IL-1β by macrophages. Changes in intracellular pH seem to be involved in the stimulation of IL-1β production. In fact, monocytes cultured at pH 6.5 undergo a fall in the values of intracellular pH while the inhibitor of the Na+/H+ exchanger, 5-(N-ethyl-N-isopropyl)amiloride induced both, a decrease in the values of intracellular pH and the stimulation of IL-1β production. Real time quantitative PCR assays indicated that monocytes cultured either at pH 6.5 or in the presence of 5-(N-ethyl-N-isopropyl)amiloride expressed higher levels of pro-IL-1β mRNA suggesting that low values of intracellular pH enhance the production of IL-1β, at least in part, by stimulating the synthesis of its precursor.
[show abstract][hide abstract] ABSTRACT: The C-type lectin receptor dendritic cell-specific ICAM-3-grabbing nonintegrin (DC-SIGN) is an important player in the recognition of pathogens by dendritic cells. A plethora of pathogens including viruses, bacteria, parasites, and fungi are recognized by DC-SIGN through both mannose and fucose-containing glycans expressed on the pathogen surface. In this study, we identified semen clusterin as a novel DC-SIGN ligand. Semen clusterin, but not serum clusterin, expresses an extreme abundance of fucose-containing blood-type Ags such as Le(x) and Le(y), which are both excellent DC-SIGN ligands. These motifs enable semen clusterin to bind DC-SIGN with very high affinity (K(d) 76 nM) and abrogate the binding of HIV-1 to DC-SIGN. Depletion of clusterin from semen samples, however, did not completely prevent the ability of semen to inhibit the capture of HIV-1 by DC-SIGN, supporting that besides clusterin, semen contains other DC-SIGN ligands. Further studies are needed to characterize these ligands and define their contribution to the DC-SIGN-blocking activity mediated by semen. Clusterin is an enigmatic protein involved in a variety of physiologic and pathologic processes including inflammation, atherosclerosis, and cancer. Our results uncover an unexpected heterogeneity in the glycosylation pattern of clusterin and suggest that the expression of high concentrations of fucose-containing glycans enables semen clusterin to display a unique set of biological functions that might affect the early course of sexually transmitted infectious diseases.
The Journal of Immunology 11/2011; 187(10):5299-309. · 5.52 Impact Factor
[show abstract][hide abstract] ABSTRACT: Unprotected sexual intercourse between discordant couples is by far the most frequent mode of HIV-1 (human immunodeficiency virus type 1) transmission being semen the main vector for HIV-1 dissemination worldwide. Semen is usually considered merely as a vehicle for HIV-1 transmission. In this review we discuss recent observations suggesting that beyond being a carrier for virus particles semen markedly influences the early events involved in sexual transmission of HIV through the mucosal barriers.
Microbes and Infection 07/2011; 13(12-13):977-82. · 2.92 Impact Factor
[show abstract][hide abstract] ABSTRACT: Dendritic cells (DCs) are highly specialized antigen-presenting cells with a unique ability to activate resting T lymphocytes. Acetylcholine (ACh) is the primary parasympathetic neurotransmitter and also a non-neural paracrine factor produced by different cells. Here, we analyzed the expression of the cholinergic system in DCs. We found that DCs express the muscarinic receptors M(3), M(4) and M(5), as well as the enzymes responsible for the synthesis and degradation of ACh, choline acetyltransferase (ChAT) and acetylcholinesterase (AChE), respectively. Differentiation of DCs in the presence of the cholinergic agonist carbachol, the synthetic analog of ACh, resulted in an increased expression of HLA-DR and CD86 and the stimulation of TNF-α and IL-8 production. All these effects were prevented by atropine, a muscarinic ACh receptor (mAChR) antagonist. Carbachol, was also able to modulate the function of DCs when added after the differentiation is accomplished; it increased the expression of HLA-DR, improved the T cell priming ability of DCs, and stimulated the production of TNF-α but not IL-12 or IL-10. By contrast, carbachol significantly inhibited the stimulation of HLA-DR expression and the enhancement in the T cell priming ability of DCs triggered by LPS. Interestingly, the TNF-α antagonist etanercept completely prevented the increased expression of HLA-DR induced by carbachol, suggesting that it promotes the phenotypic maturation of DCs by stimulating the production of TNF-α. ACh induced similar effects than carbachol; it stimulated the expression of HLA-DR and the production of TNF-α, while inhibiting the stimulation of HLA-DR expression and IL-12 production triggered by LPS. Similarly, neostigmine, an inhibitor of AChE, also stimulated the expression of HLA-DR and the production of TNF-α by DCs while inhibiting the production of TNF-α and IL-12 triggered by LPS. These results support the existence of an autocrine/paracrine loop through which ACh modulates the function of DCs.
Journal of neuroimmunology 06/2011; 236(1-2):47-56. · 2.84 Impact Factor
[show abstract][hide abstract] ABSTRACT: Plasmacytoid dendritic cells (pDCs) play a major role in anti-viral immunity by virtue of their ability to produce high amounts of type I interferons (IFNs) and a variety of inflammatory cytokines and chemokines in response to viral infections. Since recent studies have established that pDCs accumulate at the site of virus entry in the mucosa, here we analyzed whether epithelial cells were able to modulate the function of pDCs. We found that the epithelial cell lines HT-29 and Caco-2, as well as a primary culture of human renal tubular epithelial cells (HRTEC), induced the phenotypic maturation of pDCs stimulating the production of inflammatory cytokines. By contrast, epithelial cells did not induce any change in the phenotype of conventional or myeloid DCs (cDCs) while significantly stimulated the production of the anti-inflammatory cytokine IL-10. Activation of pDCs by epithelial cells was prevented by Bafilomycin A1, an inhibitor of endosomal acidification as well as by the addition of RNase to the culture medium, suggesting the participation of endosomal TLRs. Interestingly, the cross-talk between both cell populations was shown to be associated to an increased expression of TLR7 and TLR9 by pDCs and the production of LL37 by epithelial cells, an antimicrobial peptide able to bind and transport extracellular nucleic acids into the endosomal compartments. Interestingly, epithelium-activated pDCs impaired the establishment of a productive HIV infection in two susceptible target cells through the stimulation of the production of type I IFNs, highlighting the anti-viral efficiency of this novel activation pathway.
PLoS ONE 01/2011; 6(12):e28709. · 3.73 Impact Factor
[show abstract][hide abstract] ABSTRACT: Histamine is an important mediator in the development of allergic reactions. The biological effects of histamine are mediated through four histaminergic receptors. In recent years, an important role has been assigned to the proinflammatory functions of histamine regarding the H4 receptor. Previously, we have demonstrated that injection of immature dendritic cells treated with histamine into allergic mice promotes an increase in CD8(+) Tc2 lymphocytes, which are involved in the worsening of allergy symptoms during the chronic phase of the disease. The aim of this study was to evaluate the role of the H3/H4 receptor antagonist, thioperamide, in allergy.
Ovalbumin-allergized mice and nonallergized mice were injected with phosphate-buffered saline, dendritic cells, or thioperamide-treated dendritic cells. After treatment, the lungs of the mice were obtained and analyzed for changes in the populations of dendritic cells and T lymphocytes, as well as the expression of H and H4 receptors in mononuclear lung cells.
We found an increase in regulatory T cells in the lungs of allergic mice intratracheally injected with dendritic cells which had their H3/H4 receptors blocked with thioperamide. We also found an increase in the production of interleukin-10 by dendritic cells of the lung. Finally, we observed a decrease in serum levels of specific anti-IgE and a reduction of eosinophils in bronchoalveolar lavage from allergic mice.
Thioperamide induces a significant improvement in symptoms of allergic reaction perhaps via induction of regulatory T lymphocytes. These findings may become relevant in the understanding of type 1 hypersensivity reactions.