Substrate-dependent regulation of human arylamine N-acetyltransferase-1 in cultured cells

Arylamine N-acetyltransferase-1 (NAT1) is a polymorphically expressed enzyme that is widely distributed throughout the body. In the present study, we provide evidence for substrate-dependent regulation of this enzyme. Human peripheral blood mononuclear cells cultured in medium supplemented with p-aminobenzoic acid (PABA; 6 mu M) for 24 h showed a significant decrease (50-80%) in NAT1 activity. The loss of activity was concentration-dependent (EC50 similar to 2 mu M) and selective because PABA had no effect on the activity of constitutively expressed lactate dehydrogenase or aspartate aminotransferase. PABA also induced down-regulation of NAT1 activity in several human cell lines grown at confluence. Substrate-dependent downregulation was not restricted to PABA. Addition of other NAT1 substrates, such as p-aminosalicylic acid, ethyl-p-aminobenzoate, or p-aminophenol to peripheral blood mononuclear cells in culture also resulted in significant (P < .05) decreases in NAT1 activity. However, addition of the NAT2-selective substrates sulfamethazine, dapsone, or procainamide did not alter NAT1 activity. Western blot analysis using a NAT1-specific antibody showed that the loss of NAT1 activity was associated with a parallel reduction in the amount of NAT1 protein (r(2) = 0.95). Arylamines that did not decrease NAT1 activity did not alter NAT1 protein levels. Semiquantitative reverse transcriptase polymerase chain reaction of mRNA isolated from treated and untreated cells revealed no effect of PABA on NAT1 mRNA levels. We conclude that NAT1 can be down-regulated by arylamines that are themselves NAT1 substrates. Because NAT1 is involved in the detoxification/activation of various drugs and carcinogens, substrate-dependent regulation may have important consequences with regard to drug toxicity and cancer risk.

Systemic lupus erythematosus exhibits a dynamic and continuum spectrum of effector/regulatory T cells

Objective: The identification of regulatory T cells (Treg cells) as CD4(+)CD25(high) cells may be upset by the increased frequency of activated effector T cells (Teff cells) in inflammatory diseases such as systemic lupus erythematosus (SLE). This study aimed to evaluate the frequency of T-cell subsets according to the expression of CD25 and CD127 in active (A-SLE) and inactive SLE (I-SLE). Methods: Peripheral blood mononuclear cells (PBMCs) from 26 A-SLE patients (SLE Disease Activity Index (SLEDAI) = 10.17 +/- 3.7), 31 I-SLE patients (SLEDAI = 0), and 26 healthy controls (HC) were analysed by multicolour flow. cytometry. Results: CD25(high) cell frequency was increased in A-SLE (5.2 +/- 5.7%) compared to I-SLE (3.4 +/- 3.4%) and HC (1.73 +/- 0.8%) (p < 0.01). However, the percentage of FoxP3(+) cells in the CD25(high) subset was decreased in A-SLE (24.6 +/- 16.4%) compared to I-SLE (33.7 +/- 16) and HC (45 +/- 25.1%) (p < 0.01). This was partly due to the increased frequency of Teff cells (CD25(high)CD127(+)FoxP3(empty set)) in A-SLE (10.7 +/- 7.3%) compared to I-SLE (8.5 +/- 6.5) and HC (6.1 +/- 1.8%) (p = 0.02). Hence the frequency of Treg cells (CD25(+/high)CD127(low/empty set)FoxP3(+)) was equivalent in A-SLE (1.4 +/- 0.8%), I-SLE (1.37 +/- 1.0%), and HC (1.13 +/- 0.59%) (p = 0.42). A-SLE presented an increased frequency of CD25(+)CD127(+)FoxP3(+) and CD25(empty set)FoxP3(+)CD127(low/empty set) T cells, which may represent intermediate phenotypes between Treg and Teff cells. Conclusions: The present study has provided data supporting normal Treg cell frequency in A-SLE and I-SLE as well as increased frequency of Teff cells in A-SLE. This scenario reflects a Treg/Teff ratio imbalance that may favour the inflammatory phenotype of the disease. In addition, the increased frequency of T cells with putative intermediate phenotypes may be compatible with a highly dynamic immune system in SLE.

Differential monocyte STAT6 activation and CD4(+)CD25(+)Foxp3(+) T cells in kidney operational tolerance transplanted individuals

In organ transplantation, the immunosuppression withdrawal leads, in most cases, to rejection. Nonetheless, a special group of patients maintain stable graft function after complete withdrawal of immunosuppression, achieving a state called ""operational tolerance."" The study of such patients may be important to understand the mechanisms involved in human transplantation tolerance. We compared the profile of CD4(+)CD25(+)Foxp3(+) T cells and the signaling pathways IL-6/STAT3 (signal transducers and activators of transcription) and IL-4/STAT6 in peripheral blood mononuclear cells of four kidney transplant groups: (i) operational tolerance (OT), (ii) chronic allograft nephropathy (CR), (iii) stable graft function under standard immunosuppression (Sta), (iv) stable graft function under low immunosuppression, and (v) healthy individuals. Both CR and Sta displayed lower numbers and percentages of CD4(+)CD25(+)Foxp3(+) T cells compared with all other groups (p < 0.05). The OT patients displayed a reduced activation of the IL-4/STAT6 pathway in monocytes, compared with all other groups (p < 0.05). The lower numbers of CD4(+)CD25(+)Foxp3(+) T cells observed in CR individuals may be a feature of chronic allograft nephropathy. The differential OT signaling profile, with reduced phosphorylation of STAT6, in monocytes` region, suggests that some altered function of STAT6 signaling may be important for the operational tolerance state. Crown copyright (C) 2010 Published by Elsevier Inc. on behalf of American Society for Histocompatibility and Immunogenetics. All rights reserved.

Lower cytokine secretion ex vivo by natural killer T cells in HIV-infected individuals is associated with higher CD161 expression

Objective: Natural killer T (NKT) cells are efficiently targeted by HIV and severely reduced in numbers in the circulation of infected individuals. The functional capacity of the remaining NKT cells in HIV-infected individuals is poorly characterized. This study measured NKT cell cytokine production directly ex vivo and compared these responses with both the disease status and NKT subset distribution of individual patients. Methods: NKT cell frequencies, subsets, and ex-vivo effector functions were measured in the peripheral blood mononuclear cells of HIV-infected patients and healthy controls by flow cytometry. We measured cytokines from NKT cells after stimulation with either a-galactosyl ceramide-loaded CD1d dimers (DimerX-alpha GalCer) or phorbol myristate acetate and ionomycin. Results: The frequencies of NKT cells secreting interferon-gamma and tumor necrosis factor-alpha were significantly lower in HIV-infected patients than healthy controls after DimerX-alpha GalCer treatment, but responses were similar after treatment with phorbol myristate acetate and ionomycin. The magnitude of the interferon-gamma response to DimerX-alpha GalCer correlated inversely with the number of years of infection. Both interferon-gamma and tumor necrosis factor-alpha production in response to DimerX-alpha GalCer correlated inversely with CD161 expression. Conclusion: The ex-vivo Th1 responses of circulating NKT cells to CD1d-glycolipid complexes are impaired in HIV-infected patients. NKT cell functions may be progressively lost over time in HIV infection, and CD161 is implicated in the regulation of NKT cell responsiveness. (C) 2009 Wolters Kluwer Health vertical bar Lippincott Williams & Wilkins

Toll-like receptor activity in Recurrent Aphthous Ulceration

Toll-like receptors (TLR) are membrane proteins that recognize conserved molecules derived from bacterial, virus, fungal or host tissues. Activation of TLRs causes the production of cytokines that mediate inflammatory responses and drive T helper (Th) 1 and 2 cell development. As an exaggerated Th1 immune response is supposed to be involved in pathogenesis of Recurrent Aphthous Ulceration (RAU), we suggest that RAU patients may have an imbalance in TLR pathways. To study the function of TLR activation ex vivo, peripheral blood mononuclear cells (PBMCs) from RAU patients (n = 17) and controls (n = 17) were exposed to TLR2 [lipoteichoic acid (LTA), heat-killed Listeria monocytogenes (HKLM) and PamC3CSK4], TLR3 [Poly(I:C)], TLR4 [lipopolysaccharide (LPS)], TLR5 (flagellin) and TLR7 (imiquimod) ligands, and the time course of supernatant tumor necrosis factor-alpha (TNF-alpha) levels was quantified by enzyme-linked immunosorbent assay. In addition, serological and salivary TNF-alpha and soluble CD14 levels were quantified. The TNF-alpha produced by PBMCs in contact with each TLR ligand and autologous serum or saliva at the same time was also investigated. The data were analyzed by statistical multivariate tests. The control group had a higher response to LTA, whereas RAU had a higher response to HKLM. LTA and LPS interfered with the salivary stimulation of the RAU PBMC and HKLM with the stimulation of the control. Autologous serum was capable of inhibiting TLR2 responsiveness to LTA and enhancing LPS stimulation. Salivary and serological levels of sCD14 and TNF-alpha were not significantly different. Recurrent Aphthous Ulceration patients have an anomalous activity of the TLR2 pathway that probably influences the stimulation of an abnormal Th1 immune response.

Interferon and Alternative Activation of Monocyte/Macrophages in Systemic Sclerosis-Associated Pulmonary Arterial Hypertension

Objective. To explore the relationship between biomarkers of pulmonary arterial hypertension (PAH), interferon (IFN)-regulated gene expression, and the alternative activation pathway in systemic sclerosis (SSc). Methods. Peripheral blood mononuclear cells (PBMCs) were purified from healthy controls, patients with idiopathic PAH, and SSc patients (classified as having diffuse cutaneous SSc, limited cutaneous SSc [lcSSc] without PAH, and lcSSc with PAH). IFN-regulated and ""PAH biomarker"" genes were compared after supervised hierarchical clustering. Messenger RNA levels of selected IFN-regulated genes (Siglec1 and MX1), biomarker genes (IL13RA1, CCR1, and JAK2), and the alternative activation marker gene (MRC1) were analyzed on PBMCs and on CD14- and CD14+ cell populations. Interleukin-13 (IL-13) and IL-4 concentrations were measured in plasma by immunoassay. CD14, MRC1, and IL13RA1 surface expression was analyzed by flow cytometry. Results. Increased PBMC expression of both IFN-regulated and biomarker genes distinguished SSc patients from healthy controls. Expression of genes in the biomarker cluster, but not in the IFN-regulated cluster, distinguished lcSSc with PAH from lcSSc without PAH. The genes CCR1 (P < 0.001) and JAK2 (P < 0.001) were expressed more highly in lcSSc patients with PAH compared with controls and mainly by CD14+ cells. MRC1 expression was increased exclusively in lcSSc patients with PAH (P < 0.001) and correlated strongly with pulmonary artery pressure (r = 0.52, P = 0.03) and higher mortality (P = 0.02). MRC1 expression was higher in CD14+ cells and was greatly increased by stimulation with IL-13. IL-13 concentrations in plasma were most highly increased in lcSSc patients with PAH (P < 0.001). Conclusion. IFN-regulated and biomarker genes represent distinct, although related, clusters in lcSSc patients with PAH. MRC1, a marker for the effect of IL-13 on alternative monocyte/macrophage activation, is associated with this severe complication and is related to mortality.

Effect of BCG stimulus on proinflammatory cytokine production in laryngeal cancer

Background Evaluate the production of TNF and IL-6 in the supernatant of peripheral blood mononuclear cell (PBMC) cultures of patients with supraglottic laryngeal cancer before and after surgical treatment. Materials and methods Adherent cell cultures were stimulated with LPS and BCG. Fourteen patients with advanced supraglottic laryngeal cancer were studied. Cytokine concentration was determined by ELISA in supernatants of mononuclear cell cultures. Results In non-stimulated cultures, lower TNF cytokine levels were detected during the late postoperative (LP) period compared to control (P = 0.02). LP TNF and IL-6 levels were high in cultures stimulated with LPS compared with the preoperative period (PREOP) (P = 0.007; P = 0.008, respectively). Stimulation with BCG led to increased levels of TNF and IL-6 during the LP period compared to control (P = 0.001; P = 0.04, respectively). Conclusions BCG is able to modulate the immune response of patients with advanced supraglottic laryngeal cancer in vitro, increasing the secretion of TNF and IL-6 by macrophages during the postoperative period.

Monitoring and isolation of blood dendritic cells from apheresis products in healthy individuals: a platform for cancer immunotherapy

The fundamental role of dendritic cells (DC in initiating and directing the primary immune response is well established. Furthermore, it is now accepted that DC may be useful in new vaccination strategies for preventing certain malignant and infectious diseases. As blood DC (BDC physiology differs from that of the DC homologues generated in vitro from monocyte precursors, it is becoming more relevant to consider BDC for therapeutic interventions. Until recently, protocols for the isolation of BDC were laborious and inefficient; therefore, their use for investigative cancer immunotherapy is not widespread. In this study, we carefully documented BDC counts, yields and subsets during apheresis (Cobe Spectra), the initial and essential procedure in creating a BDC isolation platform for cancer immunotherapy. We established that an automated software package (Version 6,0 AutoPBPC) provides an operator-independent reliable source of motionuclear cells (MNC for BDC preparation. Further, we observed that BDC might be recovered in high yields, often greater than 100% relative to the number of circulating BDC predicted by blood volume. An average of 66 million (range, 17-179) BDC per 10-1 procedure were obtained, largely satisfying the needs for immunization. Higher yields were possible on total processed blood volumes of 151. BDC were not activated by the isolation procedure and, more importantly, both BDC subsets (CD11c(+)CD123(low) and CD11c(-)CD123(high)) were equally represented. Finally, we established that the apheresis product could be used for antibody-based BDC immunoselection and demonstrated that fully functional BDC can be obtained by this procedure. (C) 2002 Published by Elsevier Science B.V.

Immunity to malaria after administration of ultra-low doses of red cells infected with Plasmodium falciparum

Background The ability of T cells, acting independently of antibodies, to control malaria parasite growth in people has not been defined. If such cell-mediated immunity was shown to be effective, an additional vaccine strategy could be pursued. Our aim was to ascertain whether or not development of cell-mediated immunity to Plasmodium falciparum blood-stage infection could be induced in human beings by exposure to malaria parasites in very low density. Methods We enrolled five volunteers from the staff at our research institute who had never had malaria. We used a cryopreserved inoculum of red cells infected with P falciparum strain 3D7 to give them repeated subclinical infections of malaria that we then cured early with drugs, to induce cell-mediated immune responses. We tested for development of immunity by measurement of parasite concentrations in the blood of volunteers by PCR of the multicopy gene STEVOR and by following up the volunteers clinically, and by measuring antibody and cellular immune responses to the parasite. Findings After challenge and a extended period without drug cure, volunteers were protected against malaria as indicated by absence of parasites or parasite DNA in the blood, and absence of clinical symptoms. Immunity was characterised by absence of detectable antibodies that bind the parasite or infected red cells, but by the presence of a proliferative T-cell response, involving CD4+ and CD8+ T cells, a cytokine response, consisting of interferon gamma but not interleukin 4 or interleukin 10, induction of high concentrations of nitric oxide synthase activity in peripheral blood mononuclear cells, and a drop in the number of peripheral natural killer T cells. Interpretation People can be protected against the erythrocytic stage of malaria by a strong cell-mediated immune response, in the absence of detectable parasite-specific antibodies, suggesting an additional strategy for development of a malaria vaccine.

DETECTION OF HTLV-I ANTIBODIES AND DNA IN BLOOD SAMPLE OF A PATIENT WITH MYELOPATHY IN NIGERIA

We describe a case of human T-lymphotropic virus type I associated myelopathy in a 50-year old woman in Nigeria. The patient presented with progressive loss of tone to the two lower limbs and later inability to walk. The HTLV-I antibody presence in the plasma collected from the patient was repeatedly detected by enzyme immunoassays (Abbott HTLV-I EIA and Coulter SELECT-HTLV I/II) and confirmed by Western blot technique. In addition, HTLV-I DNA was amplified from the genomic DNA isolated from the peripheral blood mononuclear cells of the patient by the polymerase chain reaction technique. This finding is significant being the first report of association of HTLV-I with myelopathy in Nigeria.

Establishing a cell biology platform: isolation and preservation of human blood products

Dissertação para obtenção do Grau de Mestre em Genética Molecular e Biomedicina

Oral coinfection can stress peripheral lymphocyte to inflammatory activity in leprosy

INTRODUCTION: This study evaluated the intracellular profile of interleukin-2 (IL-2), interleukin-4 (IL-4), interleukin-10 (IL-10) and interferon-γ (IFN-γ) in peripheral blood mononuclear cells (PBMCs) from leprosy patients based on oral infections presence to determine whether these coinfections could be associated with pro-inflammatory activity in leprosy. METHODS: Leprosy patients regardless of clinical form and specific leprosy treatment (n=38) were divided into two groups: Group I - leprosy patients with oral infections (n=19), and Group II - leprosy patients without oral infections (n=19). Non-leprosy patients presenting oral infections were assigned to the control Group (n=10). Intracellular IL-2, IL-4, IL-10 and IFN-γ production was evaluated by flow cytometry (FACS) before and 7 days after controlling the oral infection in the Group I, before and 7 days after dental prophylaxis in the Group II, and during oral infection process in control Group. RESULTS: Low percentages of CD3+ lymphocytes bearing IL-2, IL-10 and IFN-γ were observed in the Group I and Group II at baseline and 7 days after therapy or prophylaxis compared to controls. Group I showed reduced percentages of IL-4 at baseline and 7 days after therapy compared to controls, or at baseline of Group II, and the Group II showed reduced percentages of CD3+ cells bearing IL-4 compared to control. An increase of the percentages of CD3+cells bearing IL-4 was observed in the Group I after the oral infections treatment. CONCLUSIONS: The occurrence of oral infections favors the intracellular cytokines expression and, probably, the inflammatory reaction operating as a stimulatory signal triggering the leprosy reactions.

COLOX: a new blood-based test for colorectal cancer screening

INTRODUCTION/OBJECTIVES: Detection rates for adenoma and early colorectal cancer (CRC) are insufficient due to low compliance towards invasive screening procedures, like colonoscopy.Available non-invasive screening tests have unfortunately low sensitivity and specificity performances.Therefore, there is a large unmet need calling for a cost-effective, reliable and non-invasive test to screen for early neoplastic and pre-neoplastic lesions AIMS & Methods: The objective is to develop a screening test able to detect early CRCs and adenomas.This test is based on a nucleic acids multi-gene assay performed on peripheral blood mononuclear cells (PBMCs).A colonoscopy-controlled feasibility study was conducted on 179 subjects.The first 92 subjects was used as training set to generate a statistical significant signature.Colonoscopy revealed 21 subjects with CRC,30 with adenoma bigger than 1 cm and 41 with no neoplastic or inflammatory lesions.The second group of 48 subjects (controls, CRC and polyps) was used as a test set and will be kept blinded for the entire data analysis.To determine the organ and disease specificity 38 subjects were used:24 with inflammatory bowel disease (IBD),14 with other cancers than CRC (OC).Blood samples were taken from each patient the day of the colonoscopy and PBMCs were purified. Total RNA was extracted following standard procedures.Multiplex RT-qPCR was applied on 92 different candidate biomarkers.Different univariate and multivariate statistical methods were applied on these candidates and among them 60 biomarkers with significant p-values (<0.01) were selected.These biomarkers are involved in several different biological functions as cellular movement,cell signaling and interaction,tissue and cellular development,cancer and cell growth and proliferation.Two distinct biomarker signatures are used to separate patients without lesion from those with cancer or with adenoma, named COLOX CRC and COLOX POL respectively.COLOX performances were validated using random resampling method, bootstrap. RESULTS: COLOX CRC and POL tests successfully separate patients without lesions from those with CRC (Se 67%,Sp 93%,AUC 0.87) and from those with adenoma bigger than 1cm (Se 63%,Sp 83%,AUC 0.77),respectively. 6/24 patients in the IBD group and 1/14 patients in the OC group have a positive COLOX CRC CONCLUSION: The two COLOX tests demonstrated a high sensitivity and specificity to detect the presence of CRCs and adenomas bigger than 1 cm.A prospective, multicenter, pivotal study is underway in order to confirm these promising results in a larger cohort.

Rapid in vitro detection of HIV-1-specific antibody secretion by cells-culture with virus antigens

The present report describes an alternative method for in vitro detection of HIV-1 -specific antibody secretion in 24h of culture employing as stimulant of peripheral blood mononuclear cells the disrupted inactivated whole virus adsorbed onto microwells in a commercial ELISA kit plates. The results obtained from this technique have showed high sensitivity and specificity since it was capable of detecting HIV-1 infection early after birth. There were neither false-positivity nor false-negativity when blood samples obtained from HIV-1 seronegative asymptomatic individuals, and HIV-1 seropositive adult patients were analized. This rapid, low cost, simple, highly sensitive and specific assay can be extremely useful for early diagnosis of pediatric HIV infection.

Induction of circulating tumor-reactive CD8+ T cells after vaccination of melanoma patients with the gp100 209-2M peptide.

Patients with stage I-III melanoma were vaccinated with the modified HLA-A2-binding gp100(209-2M)-peptide after complete surgical resection of their primary lesion and sentinel node biopsy. Cytoplasmic interferon-gamma production by freshly thawed peripheral blood mononuclear cells (direct ex vivo analysis) or by peripheral blood mononuclear cells subjected to 1 cycle of in vitro sensitization with peptide, interleukin-2, and interleukin-15 was measured following restimulation with the modified and native gp100 peptides, and also A2gp100 melanoma cell lines. Peptide-reactive and tumor-reactive T cells were detected in 79% and 66% of selected patients, respectively. Patients could be classified into 3 groups according to their vaccine-elicited T-cell responses. One group of patients responded only to the modified peptide used for immunization, whereas another group of patients reacted to both the modified and native gp100 peptides, but not to naturally processed gp100 antigen on melanoma cells. In the third group of patients, circulating CD8 T cells recognized A2gp100 melanoma cell lines and also both the modified and native peptides. T cells with a low functional avidity, which were capable of lysing tumor cells only if tumor cells were first pulsed by the exogenous administration of native gp100(209-217) peptide were identified in most patients. These results indicate that vaccination with a modified gp100 peptide induced a heterogeneous group of gp100-specific T cells with a spectrum of functional avidities; however, high avidity, tumor-reactive T cells were detected in the majority of patients.