HIV-1 induces NALP3-inflammasome expression and interleukin-1 beta secretion in dendritic cells from healthy individuals but not from HIV-positive patients

Objective: NALP3-inflammasome is an innate mechanism, alternative to type-1 interferon, which is able to recognize nucleic acids and viruses in the cytoplasm and to induce pro-inflammatory response. Here, we hypothesized the involvement of inflammasome in the early defense against HIV-1 and in the full maturation of dendritic cells: for this, we evaluated the response of dendritic cells pulsed with HIV-1 in terms of inflammasome activation in healthy donors. Moreover, inflammasome response to HIV was evaluated in HIV-infected individuals. Design and methods: Monocyte-derived dendritic cells isolated from 20 healthy individuals (HC-DC) and 20 HIV-1-infected patients (HIV-DC) were pulsed with alditrithiol-2-inactivated HIV-1. We then analyzed inflammasome genes expression and interleukin-1 beta (IL-1 beta) secretion. Results: In HC-DC, HIV-1 induced higher NLRP3/NALP3 mRNA expression compared with other inflammasome genes such as NALP1/NLRP1 or IPAF/NLRC4 (P < 0.001). This augmented expression was accompanied by CASP1-increased and IL1B-increased mRNA levels and by a significant increment of IL-1b secretion (P < 0.05). Otherwise, HIV-1 failed to activate inflammasome and cytokine production in HIV-DC. HIV-DC showed an increased NLRP3/NALP3 basal expression, suggesting a chronic inflammatory profile of patients' immune cells. Conclusion: HIV-1 was able to induce a NALP3-inflammasome response in healthy individuals, indicating that this inflammasome could play a role in the first steps of HIV-1 infection; the consequent inflammatory process may be important for directing host immune response against the virus and/or disease progression. HIV-DC seemed to be chronically activated, but unresponsive against pathogens. Our findings could be of interest considering the ongoing research about dendritic cell manipulation and therapeutic strategies for AIDS involving dendritic cell-based immune-vaccines. (C) 2011 Wolters Kluwer Health vertical bar Lippincott Williams & Wilkins

The imbalance between Treg and Th17 cells caused by FTY720 treatment in skin allograft rejection

OBJECTIVES: FTY720 modulates CD4(+)T cells by the augmentation of regulatory T cell activity, secretion of suppressive cytokines and suppression of IL-17 secretion by Th17 cells. To further understand the process of graft rejection/acceptance, we evaluated skin allograft survival and associated events after FTY720 treatment. METHODS: F1 mice (C57BL/6xBALB/c) and C57BL/6 mice were used as donors for and recipients of skin transplantation, respectively. The recipients were transplanted and either not treated or treated with FTY720 by gavage for 21 days to evaluate the allograft survival. In another set of experiments, the immunological evaluation was performed five days post-transplantation. The spleens, axillary lymph nodes and skin allografts of the recipient mice were harvested for phenotyping (flow cytometry), gene expression (real-time PCR) and cytokine (Bio-Plex) analysis. RESULTS: The FTY720 treatment significantly increased skin allograft survival, reduced the number of cells in the lymph nodes and decreased the percentage of Tregs at this site in the C57BL/6 recipients. Moreover, the treatment reduced the number of graft-infiltrating cells and the percentage of CD4(+) graft-infiltrating cells. The cytokine analysis (splenocytes) showed decreased levels of IL-10, IL-6 and IL-17 in the FTY720-treated mice. We also observed a decrease in the IL-10, IL-6 and IL-23 mRNA levels, as well as an increase in the IL-27 mRNA levels, in the splenocytes of the treated group. The FTY720-treated mice exhibited increased mRNA levels of IL-10, IL-27 and IL-23 in the skin graft. CONCLUSIONS: Our results demonstrated prolonged but not indefinite skin allograft survival by FTY720 treatment. This finding indicates that the drug did not prevent the imbalance between Tr1 and Th17 cells in the graft that led to rejection.

Distinct mechanisms underlie adaptation of proximal tubule Na+/H+ exchanger isoform 3 in response to chronic metabolic and respiratory acidosis

The Na+/H+ exchanger isoform 3 (NHE3) is essential for HCO3- reabsorption in renal proximal tubules. The expression and function of NHE3 must adapt to acid-base conditions. The goal of this study was to elucidate the mechanisms responsible for higher proton secretion in proximal tubules during acidosis and to evaluate whether there are differences between metabolic and respiratory acidosis with regard to NHE3 modulation and, if so, to identify the relevant parameters that may trigger these distinct adaptive responses. We achieved metabolic acidosis by lowering HCO3- concentration in the cell culture medium and respiratory acidosis by increasing CO2 tension in the incubator chamber. We found that cell-surface NHE3 expression was increased in response to both forms of acidosis. Mild (pH 7.21 +/- 0.02) and severe (6.95 +/- 0.07) metabolic acidosis increased mRNA levels, at least in part due to up-regulation of transcription, whilst mild (7.11 +/- 0.03) and severe (6.86 +/- 0.01) respiratory acidosis did not up-regulate NHE3 expression. Analyses of the Nhe3 promoter region suggested that the regulatory elements sensitive to metabolic acidosis are located between -466 and -153 bp, where two consensus binding sites for SP1, a transcription factor up-regulated in metabolic acidosis, were localised. We conclude that metabolic acidosis induces Nhe3 promoter activation, which results in higher mRNA and total protein level. At the plasma membrane surface, NHE3 expression was increased in metabolic and respiratory acidosis alike, suggesting that low pH is responsible for NHE3 displacement to the cell surface.

Interferon-gamma and interleukin-10 production by mononuclear cells from patients with advanced head and neck cancer

OBJECTIVE: This study aims to evaluate the production of interferon-gamma and interleukin-10 by stimulated peripheral blood mononuclear cells isolated from patients with supraglottic laryngeal cancer before and after surgical treatment. METHODS: Fourteen patients with advanced supraglottic laryngeal cancer were studied. Cultures of peripheral blood mononuclear cells isolated during the preoperative and late postoperative periods were stimulated with concanavalin A and Bacille Calmette-Guerin, and the supernatant concentrations of interferon-gamma and interleukin-10 were measured. RESULTS: For non-stimulated cultures, the interferon-gamma levels produced by the preoperative period and the late postoperative period cultures were lower than the levels produced by the control group cultures. The interferon-gamma levels after stimulation with concanavalin A were higher in the late postoperative period cultures than in the preoperative evaluation cultures. Stimulation with Bacille Calmette-Guerin led to the production of similar levels of interferon-gamma and interleukin-10 by all cultures; thus, stimulation increased the levels of interferon-gamma produced by both the preoperative and postoperative cultures relative to the levels produced by the corresponding unstimulated cultures. CONCLUSION: Patients with advanced supraglottic laryngeal cancer exhibit an in vitro deficiency in interferongamma secretion by mononuclear cells. Stimulated cells seem to recover this function during the postoperative period.

Experimental arthritis exacerbates Aggregatibacter actinomycetemcomitans-induced periodontitis in mice

Aim This study aimed to investigate whether chronic antigen-induced arthritis (AIA) influences infection-induced periodontitis (PD) in mice and whether PD modifies the clinical course of AIA. The contribution of anti-TNF-a therapy was also evaluated. Materials and methods The PD was induced in C57BL/6 mice by oral infection with Aggregatibacter actinomycetemcomitans. AIA was induced after infection. Anti-TNF-a and chlorhexidine therapies were used to investigate the role of TNF-a and oral infection on PD and AIA interaction. Maxillae, knee joints, lymph nodes and serum samples were used for histomorphometric, immunoenzymatic and/or real time-PCR analyses. Results Antigen-induced arthritis exacerbated alveolar bone loss triggered by PD infection. In contrast, PD did not influence AIA in the evaluated time-points. PD exacerbation was associated with enhanced production of IFN-? in maxillae and expression of the Th1 transcription factor tBET in submandibular lymph nodes. Increased serum levels of IL-6 and C-reactive protein were also detected. Anti-TNF-a and antiseptic therapies prevented the development and exacerbation of infectious-PD. Anti-TNF-a therapy also resulted in reduced expression of IFN-?, TNF-a and IL-17 in maxillae. Conclusions Altogether, the current results indicate that the exacerbation of infection-induced PD by arthritis is associated with an alteration in lymphocyte polarization pattern and increased systemic immunoreactivity. This process was ameliorated by anti-TNF-a and antiseptic therapies.

Toll-like receptor 9 activation: a novel mechanism linking placenta-derived mitochondrial DNA and vascular dysfunction in pre-eclampsia

Emerging evidence suggests that in addition to being the 'power houses' of our cells, mitochondria facilitate effector responses of the immune system. Cell death and injury result in the release of mtDNA (mitochondrial DNA) that acts via TLR9 (Toll-like receptor 9), a pattern recognition receptor of the immune system which detects bacterial and viral DNA but not vertebrate DNA. The ability of mtDNA to activate TLR9 in a similar fashion to bacterial DNA stems from evolutionarily conserved similarities between bacteria and mitochondria. mtDNA may be the trigger of systemic inflammation in pathologies associated with abnormal cell death. PE (pre-eclampsia) is a hypertensive disorder of pregnancy with devastating maternal and fetal consequences. The aetiology of PE is unknown and removal of the placenta is the only effective cure. Placentas from women with PE show exaggerated necrosis of trophoblast cells, and circulating levels of mtDNA are higher in pregnancies with PE. Accordingly, we propose the hypothesis that exaggerated necrosis of trophoblast cells results in the release of mtDNA, which stimulates TLR9 to mount an immune response and to produce systemic maternal inflammation and vascular dysfunction that lead to hypertension and IUGR (intra-uterine growth restriction). The proposed hypothesis implicates mtDNA in the development of PE via activation of the immune system and may have important preventative and therapeutic implications, because circulating mtDNA may be potential markers of early detection of PE, and anti-TLR9 treatments may be promising in the management of the disease.

Methionine-induced hyperhomocysteinemia reverts fibrinolytic pathway activation in a murine model of acute promyelocytic leukemia

Increased fibrinolysis is an important component of acute promyelocytic leukemia (APL) bleeding diathesis. APL blasts overexpress annexin II (ANXII), a receptor for tissue plasminogen activator (tPA), and plasminogen, thereby increasing plasmin generation. Previous studies suggested that ANXII plays a pivotal role in APL coagulopathy. ANXII binding to tPA can be inhibited by homocysteine and hyperhomocysteinemia can be induced by L-methionine supplementation. In the present study, we used an APL mouse model to study ANXII function and the effects of hyperhomocysteinemia in vivo. Leukemic cells expressed higher ANXII and tPA plasma levels (11.95 ng/mL in leukemic vs 10.74 ng/mL in wild-type; P = .004). In leukemic mice, administration of L-methionine significantly increased homocysteine levels (49.0 mu mol/mL and < 6.0 mu mol/mL in the treated and nontreated groups, respectively) and reduced tPA levels to baseline concentrations. The latter were also decreased after infusion of the LCKLSL peptide, a competitor for the ANXII tPA-binding site (11.07 ng/mL; P = .001). We also expressed and purified the p36 component of ANXII in Pichia methanolica. The infusion of p36 in wild-type mice increased tPA and thrombin-antithrombin levels, and the latter was reversed by L-methionine administration. The results of the present study demonstrate the relevance of ANXII in vivo and suggest that methionine-induced hyperhomocysteinemia may reverse hyperfibrinolysis in APL. (Blood. 2012;120(1):207-213)

Consequences of pilocarpine-induced status epilepticus in immunodeficient mice

Systemic injection of pilocarpine in rodents induces status epilepticus (SE) and reproduces the main characteristics of temporal lobe epilepsy (TLE). Different mechanisms are activated by SE contributing to cell death and immune system activation. We used BALB/c nude mice, a mutant that is severely immunocompromised, to characterize seizure pattern, neurochemical changes, cell death and c-Fos activation secondarily to pilocarpine-induced SE. The behavioral seizures were less severe in BALB/c nude than in BALB/c wild type mice. However, nude mice presented more tonic clonic episodes and higher mortality rate during SE. The c-Fos expression was most prominent in the caudate-putamen, CA3 (p < 0.05), dentate gyrus, entorhinal cortex (p < 0.001), basolateral nucleus of amygdala (p < 0.01) and piriform cortex (p < 0.05) of BALB/c nude mice than of BALB/c. Besides, nude mice subjected to SE presented high number of Fluorojade-B (FJB) stained cells in the piriform cortex, amygdala (p < 0.05) and hilus (p < 0.05) in comparison with BALB/c mice. A significant increase in the level of glutamate and GABA was found in the hippocampus and cortex of BALB/c mice presenting SE in comparison to controls. However, the level of glutamate was higher in the brains of BALB nude mice than in the brains of BALB/c wild type mice, while the levels of GABA were unchanged. These results indicate that the brains of immunodeficient nude mice are more vulnerable to the deleterious effects of pilocarpine-induced SE as they present intense activation, increased glutamate levels and more cell death. Published by Elsevier B.V.

Effect of treatment delay on disease severity and need for resuscitation in porcine fecal peritonitis

Objective: Early treatment in sepsis may improve outcome. The aim of this study was to evaluate how the delay in starting resuscitation influences the severity of sepsis and the treatment needed to achieve hemodynamic stability. Design: Prospective, randomized, controlled experimental study. Setting: Experimental laboratory in a university hospital. Subjects: Thirty-two anesthetized and mechanically ventilated pigs. Interventions: Pigs were randomly assigned (n = 8 per group) to a nonseptic control group or one of three groups in which fecal peritonitis (peritoneal instillation of 2 g/kg autologous feces) was induced, and a 48-hr period of protocolized resuscitation started 6 (Delta T-6 hrs), 12 (Delta T-12 hrs), or 24 (Delta T-24 hrs) hrs later. The aim of this study was to evaluate the impact of delays in resuscitation on disease severity, need for resuscitation, and the development of sepsis-associated organ and mitochondrial dysfunction. Measurements and Main Results: Any delay in starting resuscitation was associated with progressive signs of hypovolemia and increased plasma levels of interleukin-6 and tumor necrosis factor-alpha prior to resuscitation. Delaying resuscitation increased cumulative net fluid balances (2.1 +/- 0.5 mL/kg/hr, 2.8 +/- 0.7 mL/kg/hr, and 3.2 +/- 1.5 mL/kg/hr, respectively, for groups.T-6 hrs, Delta T-12 hrs, and.T-24 hrs; p < .01) and norepinephrine requirements during the 48-hr resuscitation protocol (0.02 +/- 0.04 mu g/kg/min, 0.06 +/- 0.09 mu g/kg/min, and 0.13 +/- 0.15 mu g/kg/min; p = .059), decreased maximal brain mitochondrial complex II respiration (p = .048), and tended to increase mortality (p = .08). Muscle tissue adenosine triphosphate decreased in all groups (p < .01), with lowest values at the end in groups Delta T-12 hrs and.T-24 hrs. Conclusions: Increasing the delay between sepsis initiation and resuscitation increases disease severity, need for resuscitation, and sepsis-associated brain mitochondrial dysfunction. Our results support the concept of a critical window of opportunity in sepsis resuscitation. (Crit Care Med 2012; 40:2841-2849)

Ethanol Consumption Alters the Expression and Reactivity of Adrenomedullin in the Rat Mesenteric Arterial Bed

Aims: Adrenomedullin (AM) is a peptide that displays cardiovascular protective activity. We investigated the effects of chronic ethanol consumption on arterial blood pressure, vascular reactivity to AM and the expression of AM system components in the rat mesenteric arterial bed (MAB). Methods: Male Wistar rats were treated with ethanol (20% vol/vol) for 6 weeks. Systolic, diastolic and mean arterial blood pressure were monitored in conscious rats. Vascular reactivity experiments were performed on isolated rat MAB. Matrix metalloproteinase-2 (MMP-2) levels were determined by gelatin zymography. Nitrite and nitrate generation were measured by chemiluminescence. Protein and mRNA levels of pre-pro-AM, CRLR (calcitonin receptor-like receptor) and RAMP1, 2 and 3 (receptor activity-modifying proteins) were assessed by western blot and quantitative real-time polymerase chain reaction, respectively. Results: Ethanol consumption induced hypertension and decreased the relaxation induced by AM and acetylcholine in endothelium-intact rat MAB. Phenylephrine-induced contraction was increased in endothelium-intact MAB from ethanol-treated rats. Ethanol consumption did not alter basal levels of nitrate and nitrite, nor did it affect the expression of MMP-2 or the net MMP activity in the rat MAB. Ethanol consumption increased mRNA levels of pre-pro-AM and protein levels of AM in the rat MAB. Finally, no differences in protein levels or mRNA of CRLR and RAMP1, 2 and 3 were observed after treatment with ethanol. Conclusion: Our study demonstrates that ethanol consumption increases blood pressure and the expression of AM in the vasculature and reduces the relaxation induced by this peptide in the rat MAB.

Infantile Encephaloneuromyopathy and Defective Mitochondrial Translation Are Due to a Homozygous RMND1 Mutation

Defects of mitochondrial protein synthesis are clinically and genetically heterogeneous. We previously described a male infant who was born to consanguineous parents and who presented with severe congenital encephalopathy, peripheral neuropathy, myopathy, and lactic acidosis associated with deficiencies of multiple mitochondrial respiratory-chain enzymes and defective mitochondrial translation. In this work, we have characterized four additional affected family members, performed homozygosity mapping, and identified a homozygous splicing mutation in the splice donor site of exon 2 (c.504+1G>A) of RMND1 (required for meiotic nuclear division-1) in the affected individuals. Fibroblasts from affected individuals expressed two aberrant transcripts and had decreased wild-type mRNA and deficiencies of mitochondrial respiratory-chain enzymes. The RMND1 mutation caused haploinsufficiency that was rescued by overexpression of the wild-type transcript in mutant fibroblasts; this overexpression increased the levels and activities of mitochondrial respiratory-chain proteins. Knockdown of RMND1 via shRNA recapitulated the biochemical defect of the mutant fibroblasts, further supporting a loss-of-function pathomechanism in this disease. RMND1 belongs to the sif2 family, an evolutionary conserved group of proteins that share the DUF155 domain, have unknown function, and have never been associated with human disease. We documented that the protein localizes to mitochondria in mammalian and yeast cells. Further studies are necessary for understanding the function of this protein in mitochondrial protein translation.

Accumulation of the SET protein in HEK293T cells and mild oxidative stress: cell survival or death signaling

SET protein (I2PP2A) is an inhibitor of PP2A, which regulates the phosphorylated Akt (protein kinase B) levels. We assessed the effects of SET overexpression in HEK293T cells, both in the presence and the absence of mild oxidative stress induced by 50 mu M tert-butyl hydroperoxide. Immunoblotting assays demonstrated that SET accumulated in HEK293T cells and increased the levels of phosphorylated Akt and PTEN; in addition, SET decreased glutathione antioxidant defense of cell and increased expression of genes encoding antioxidant defense proteins. Immunofluorescence analysis demonstrated that accumulated SET was equally distributed in cytoplasm and nucleus; however, in cells that had been exposed to oxidative stress, SET was found in large aggregates in the cytoplasm. SET accumulation in HEK293T cells correlated with inhibition of basal apoptosis as evidenced by a decrease in annexin V staining and activity of caspases; under mild oxidative stress, SET accumulation correlated with caspase-independent cell death, as evidenced by increased PI and annexin V/PI double staining. The results suggest that accumulated SET could act via Akt/PTEN either as cell survival signal or as oxidative stress sensor for cell death.

NADPH Phagocyte Oxidase Knockout Mice Control Trypanosoma cruzi Proliferation, but Develop Circulatory Collapse and Succumb to Infection

(NO)-N-center dot is considered to be a key macrophage-derived cytotoxic effector during Trypanosoma cruzi infection. On the other hand, the microbicidal properties of reactive oxygen species (ROS) are well recognized, but little importance has been attributed to them during in vivo infection with T. cruzi. In order to investigate the role of ROS in T. cruzi infection, mice deficient in NADPH phagocyte oxidase (gp91(phox-/-) or phox KO) were infected with Y strain of T. cruzi and the course of infection was followed. phox KO mice had similar parasitemia, similar tissue parasitism and similar levels of IFN-gamma and TNF in serum and spleen cell culture supernatants, when compared to wild-type controls. However, all phox KO mice succumbed to infection between day 15 and 21 after inoculation with the parasite, while 60% of wild-type mice were alive 50 days after infection. Further investigation demonstrated increased serum levels of nitrite and nitrate (NOx) at day 15 of infection in phox KO animals, associated with a drop in blood pressure. Treatment with a NOS2 inhibitor corrected the blood pressure, implicating NOS2 in this phenomenon. We postulate that superoxide reacts with (NO)-N-center dot in vivo, preventing blood pressure drops in wild type mice. Hence, whilst superoxide from phagocytes did not play a critical role in parasite control in the phox KO animals, its production would have an important protective effect against blood pressure decline during infection with T. cruzi.

MicroRNA miR-146b-5p regulates signal transduction of TGF-beta by repressing SMAD4 in thyroid cancer

MicroRNAs (miRNA) are small non-coding RNAs involved in post-transcriptional gene regulation that have crucial roles in several types of tumors, including papillary thyroid carcinoma (PTC). miR-146b-5p is overexpressed in PTCs and is regarded as a relevant diagnostic marker for this type of cancer. A computational search revealed that miR-146b-5p putatively binds to the 3' untranslated region (UTR) of SMAD4, an important member of the transforming growth factor beta (TGF-beta) signaling pathway. The TGF-beta pathway is a negative regulator of thyroid follicular cell growth, and the mechanism by which thyroid cancer cells evade its inhibitory signal remains unclear. We questioned whether the modulation of the TGF-beta pathway by miR-146b-5p can contribute to thyroid tumorigenesis. Luciferase reporter assay confirmed the direct binding of miR-146b-5p on the SMAD4 3'UTR. Specific inhibition of miR-146b-5p with a locked nucleic acid-modified anti-miR-146b oligonucleotide significantly increased SMAD4 levels in the human papillary carcinoma cell lines, TPC-1 and BCPAP. Moreover, suppression of miR-146b-5p increased the cellular response to the TGF-beta anti-proliferative signal, significantly decreasing the proliferation rate. The overexpression of miR-146b-5p in normal rat follicular PCCL3 cells decreased SMAD4 levels and disrupted TGF-beta signal transduction. MiR-146b-5p overexpression in PCCL3 cells also significantly increased cell proliferation in the absence of thyroid-stimulating hormone and conferred resistance to TGF-beta-mediated cell-cycle arrest. Additionally, the activation of thyroid most common oncogenes RET/PTC3 and BRAF in PCCL3 cells upregulated miR-146b-5p expression. Our results confirm the oncogenic role of miR-146b-5p in thyroid follicular cells and contribute to knowledge regarding the modulation of TGF-beta signal transduction by miRNAs in PTCs. Oncogene (2012) 31, 1910-1922; doi:10.1038/onc.2011.381; published online 29 August 2011

The protective effect of cilostazol on isolated rabbit femoral arteries under conditions of ischemia and reperfusion: the role of the nitric oxide pathway

OBJECTIVES: The clinical significance of ischemia/reperfusion of the lower extremities demands further investigation to enable the development of more effective therapeutic alternatives. This study investigated the changes in the vascular reactivity of the rabbit femoral artery and nitric oxide metabolites under partial ischemia/reperfusion conditions following cilostazol administration. METHODS: Ischemia was induced using infrarenal aortic clamping. The animals were randomly divided into seven groups: Control 90 minutes, Ischemia/Reperfusion 90/60 minutes, Control 120 minutes, Ischemia/Reperfusion 120/90 minutes, Cilostazol, Cilostazol before Ischemia/Reperfusion 120/90 minutes, and Ischemia 120 minutes/Cilostazol/Reperfusion 90 minutes. Dose-response curves for sodium nitroprusside, acetylcholine, and the calcium ionophore A23187 were obtained in isolated femoral arteries. The levels of nitrites and nitrates in the plasma and skeletal muscle were determined using chemiluminescence. RESULTS: Acetylcholine- and A23187-induced relaxation was reduced in the Ischemia/Reperfusion 120/90 group, and treatment with cilostazol partially prevented this ischemia/reperfusion-induced endothelium impairment. Only cilostazol treatment increased plasma levels of nitrites and nitrates. An elevation in the levels of nitrites and nitrates was observed in muscle tissues in the Ischemia/Reperfusion 120/90, Cilostazol/Ischemia/Reperfusion, and Ischemia/Cilostazol/Reperfusion groups. CONCLUSION: Hind limb ischemia/reperfusion yielded an impaired endothelium-dependent relaxation of the femoral artery. Furthermore, cilostazol administration prior to ischemia exerted a protective effect on endothelium-dependent vascular reactivity under ischemia/reperfusion conditions.