Interactions with Asialo-Glycoprotein Receptors and Platelets Are Dispensable for CD8+ T Cell Localization in the Murine Liver.

Liver-resident CD8+ T cells can play critical roles in the control of pathogens, including Plasmodium and hepatitis B virus. Paradoxically, it has also been proposed that the liver may act as the main place for the elimination of CD8+ T cells at the resolution of immune responses. We hypothesized that different adhesion processes may drive residence versus elimination of T cells in the liver. Specifically, we investigated whether the expression of asialo-glycoproteins (ASGPs) drives the localization and elimination of effector CD8+ T cells in the liver, while interactions with platelets facilitate liver residence and protective function. Using murine CD8+ T cells activated in vitro, or in vivo by immunization with Plasmodium berghei sporozoites, we found that, unexpectedly, inhibition of ASGP receptors did not inhibit the accumulation of effector cells in the liver, but instead prevented these cells from accumulating in the spleen. In addition, enforced expression of ASGP on effector CD8+ T cells using St3GalI-deficient cells lead to their loss from the spleen. We also found, using different mouse models of thrombocytopenia, that severe reduction in platelet concentration in circulation did not strongly influence the residence and protective function of CD8+ T cells in the liver. These data suggest that platelets play a marginal role in CD8+ T cell function in the liver. Furthermore, ASGP-expressing effector CD8+ T cells accumulate in the spleen, not the liver, prior to their destruction.

T-dependent B cell responses to Plasmodium induce antibodies that form a high-avidity multivalent complex with the circumsporozoite protein.

The repeat region of the Plasmodium falciparum circumsporozoite protein (CSP) is a major vaccine antigen because it can be targeted by parasite neutralizing antibodies; however, little is known about this interaction. We used isothermal titration calorimetry, X-ray crystallography and mutagenesis-validated modeling to analyze the binding of a murine neutralizing antibody to Plasmodium falciparum CSP. Strikingly, we found that the repeat region of CSP is bound by multiple antibodies. This repeating pattern allows multiple weak interactions of single FAB domains to accumulate and yield a complex with a dissociation constant in the low nM range. Because the CSP protein can potentially cross-link multiple B cell receptors (BCRs) we hypothesized that the B cell response might be T cell independent. However, while there was a modest response in mice deficient in T cell help, the bulk of the response was T cell dependent. By sequencing the BCRs of CSP-repeat specific B cells in inbred mice we found that these cells underwent somatic hypermutation and affinity maturation indicative of a T-dependent response. Last, we found that the BCR repertoire of responding B cells was limited suggesting that the structural simplicity of the repeat may limit the breadth of the immune response.

Chemically Attenuated Blood-Stage Plasmodium yoelii Parasites Induce Long-Lived and Strain-Transcending Protection.

The development of a vaccine is essential for the elimination of malaria. However, despite many years of effort, a successful vaccine has not been achieved. Most subunit vaccine candidates tested in clinical trials have provided limited efficacy, and thus attenuated whole-parasite vaccines are now receiving close scrutiny. Here, we test chemically attenuated Plasmodium yoelii 17X and demonstrate significant protection following homologous and heterologous blood-stage challenge. Protection against blood-stage infection persisted for at least 9 months. Activation of both CD4(+) and CD8(+) T cells was shown after vaccination; however, in vivo studies demonstrated a pivotal role for both CD4(+) T cells and B cells since the absence of either cell type led to loss of vaccine-induced protection. In spite of significant activation of circulating CD8(+) T cells, liver-stage immunity was not evident. Neither did vaccine-induced CD8(+) T cells contribute to blood-stage protection; rather, these cells contributed to pathogenesis, since all vaccinated mice depleted of both CD4(+) and CD8(+) T cells survived a challenge infection. This study provides critical insight into whole-parasite vaccine-induced immunity and strong support for testing whole-parasite vaccines in humans.

The effect of continuous venovenous hemofiltration on neutrophil gelatinase-associated lipocalin plasma levels in patients with septic acute kidney injury.

BACKGROUND: It is known that continuous venonenous hemofiltration (CVVH) does not affect the plasma level of neutrophil gelatinase-associated lipocalin (pNGAL) in acute kidney injury (AKI) patients. However, because of the unique pathophysiology underlying AKI caused by sepsis, the effect of CVVH on pNGAL in this clinical setting is less certain. The purpose of this study was to determine the effect of CVVH on pNGAL in sepsis-induced AKI patients. METHODS: Between August 1, 2014, and December 31, 2014, 42 patients with sepsis-induced AKI underwent CVVH in the general intensive care unit of our institution and were consecutively enrolled in this study. Prefilter, postfilter, and ultrafiltrate pNGAL measurements were taken at the initiation of continuous renal replacement therapy (CRRT) and repeated after 2, 4, 8, and 12 h (T0, T2h, T4h, T8h, and T12h, respectively). The mass transfer, plasma clearance, and sieving coefficient were calculated based on the mass conservation principle. RESULTS: Following CVVH initiation, we found that pNGAL in the ultrafiltrate decreased significantly (P = 0.013); however, levels at the inlet and outlet showed no significant change (P > 0.05 for both). Furthermore, there was no change in the total mass removal rate, total mass adsorption rate, and plasma clearance over time (P > 0.05 for all), and a significant decrease in the sieving coefficient (P = 0.007) was seen. CONCLUSIONS: The results of this study show a limited effect of CVVH on pNGAL in sepsis-induced AKI patients. This suggests that pNGAL may be used as an indicator of renal progression in these patients. However, a larger study to confirm these findings is needed. TRIAL REGISTRATION: ClinicalTrials.gov, NCT02536027 . Retrospectively registered on 20th August 2015.

A Mutation in DAOA Modifies the Age of Onset in PSEN1 E280A Alzheimer's Disease.

We previously reported age of onset (AOO) modifier genes in the world's largest pedigree segregating early-onset Alzheimer's disease (AD), caused by the p.Glu280Ala (E280A) mutation in the PSEN1 gene. Here we report the results of a targeted analysis of functional exonic variants in those AOO modifier genes in sixty individuals with PSEN1 E280A AD who were whole-exome genotyped for ~250,000 variants. Standard quality control, filtering, and annotation for functional variants were applied, and common functional variants located in those previously reported as AOO modifier loci were selected. Multiloci linear mixed-effects models were used to test the association between these variants and AOO. An exonic missense mutation in the G72 (DAOA) gene (rs2391191, P = 1.94 × 10(-4), P FDR = 9.34 × 10(-3)) was found to modify AOO in PSEN1 E280A AD. Nominal associations of missense mutations in the CLUAP1 (rs9790, P = 7.63 × 10(-3), P FDR = 0.1832) and EXOC2 (rs17136239, P = 0.0325, P FDR = 0.391) genes were also found. Previous studies have linked polymorphisms in the DAOA gene with the occurrence of neuropsychiatric symptoms such as depression, apathy, aggression, delusions, hallucinations, and psychosis in AD. Our findings strongly suggest that this new conspicuous functional AOO modifier within the G72 (DAOA) gene could be pivotal for understanding the genetic basis of AD.

Mutations modifying sporadic Alzheimer's disease age of onset.

The identification of mutations modifying the age of onset (AOO) in Alzheimer's disease (AD) is crucial for understanding the natural history of AD and, therefore, for early interventions. Patients with sporadic AD (sAD) from a genetic isolate in the extremes of the AOO distribution were whole-exome genotyped. Single- and multi-locus linear mixed-effects models were used to identify functional variants modifying AOO. A posteriori enrichment and bioinformatic analyses were applied to evaluate the non-random clustering of the associate variants to physiopathological pathways involved in AD. We identified more than 20 pathogenic, genome-wide statistically significant mutations of major modifier effect on the AOO. These variants are harbored in genes implicated in neuron apoptosis, neurogenesis, inflammatory processes linked to AD, oligodendrocyte differentiation, and memory processes. This set of new genes harboring these mutations could be of importance for prediction, follow-up and eventually as therapeutical targets of AD. © 2016 Wiley Periodicals, Inc.

Diagnostic value of neutrophil gelatinase-associated lipocalin, cystatin C, and soluble triggering receptor expressed on myeloid cells-1 in critically ill patients with sepsis-associated acute kidney injury.

INTRODUCTION: Neutrophil gelatinase-associated lipocalin (NGAL), cystatin C (Cys-C), and soluble triggering receptor expressed on myeloid cells-1 (sTREM-1) are novel diagnostic biomarkers of acute kidney injury (AKI). We aimed to determine the diagnostic properties of these biomarkers for detecting AKI in critically ill patients with sepsis. METHODS: We divided 112 patients with sepsis into non-AKI sepsis (n = 57) and AKI sepsis (n = 55) groups. Plasma and urine specimens were collected on admission and every 24 hours until 72 hours and tested for NGAL, Cys-C, and TREM-1 concentrations. Their levels were compared on admission, at diagnosis, and 24 hours before diagnosis. RESULTS: Both plasma and urine NGAL, Cys-C, and sTREM-1 were significantly associated with AKI development in patients with sepsis, even after adjustment for confounders by using generalized estimating equations. Compared with the non-AKI sepsis group, the sepsis AKI group exhibited markedly higher levels of these biomarkers at diagnosis and 24 hours before AKI diagnosis (P < 0.01). The diagnostic and predictive values of plasma and urine NGAL were good, and those of plasma and urine Cys-C and sTREM-1 were fair. CONCLUSION: Plasma and urine NGAL, Cys-C, and sTREM-1 can be used as diagnostic and predictive biomarkers for AKI in critically ill patients with sepsis.

Estrogen stimulates Th2 cytokine production and regulates the compartmentalisation of eosinophils during allergen challenge in a mouse model of asthma.

BACKGROUND: The observation that asthma becomes more prevalent following puberty in females suggests estrogen potentiates the development of this disease. However, most studies examining the role of estrogen in rodent models of asthma are complicated by their reliance on ovariectomised mice in which hormones other than estrogen are also attenuated. METHODS: We aimed to understand the influence of estrogen on allergic airway disease by using type I (tamoxifen) or type II (ICI 182,780) antagonists in female mice or delivering estradiol to male mice during aeroallergen challenge. RESULTS: The antagonists showed that estrogen promoted both the mobilisation of bone marrow eosinophils and egression of eosinophils to the airway lumen. These findings were corroborated in male mice treated with estradiol, which increased eosinophil numbers in both blood and airways. Estrogen stimulated goblet cell hyperplasia and baseline lung resistance, but had little effect on the number of eosinophils in the bronchial submucosa or methacholine-induced airway hyperreactivity. Estrogen receptor α was expressed by CD4+ T cells from allergic mice, and estrogen promoted the production of IL-5 and IL-13, and suppressed the production of the eicosanoid 12-HETE by mediastinal lymph node cells. CONCLUSIONS: These data show that during aeroallergen challenge, estrogen stimulates Th2 cytokine production, which may be linked to its ability to suppress 12-HETE. Lung resistance at baseline, goblet cell hyperplasia and the compartmentalisation of eosinophils was also influenced by estrogen. However, estrogen does not play a major role in stimulating enhanced sensitivity to methacholine-induced lung resistance.

Splenic Dendritic Cells and Macrophages Drive B Cells to Adopt a Plasmablast Cell Fate.

Upon encountering cognate antigen, B cells can differentiate into short-lived plasmablasts, early memory B cells or germinal center B cells. The factors that determine this fate decision are unclear. Past studies have addressed the role of B cell receptor affinity in this process, but the interplay with other cellular compartments for fate determination is less well understood. Moreover, B cell fate decisions have primarily been studied using model antigens rather than complex pathogen systems, which potentially ignore multifaceted interactions from other cells subsets during infection. Here we address this question using a Plasmodium infection model, examining the response of B cells specific for the immunodominant circumsporozoite protein (CSP). We show that B cell fate is determined in part by the organ environment in which priming occurs, with the majority of the CSP-specific B cell response being derived from splenic plasmablasts. This plasmablast response could occur independent of T cell help, though gamma-delta T cells were required to help with the early isotype switching from IgM to IgG. Interestingly, selective ablation of CD11c+ dendritic cells and macrophages significantly reduced the splenic plasmablast response in a manner independent of the presence of CD4 T cell help. Conversely, immunization approaches that targeted CSP-antigen to dendritic cells enhanced the magnitude of the plasmablast response. Altogether, these data indicate that the early CSP-specific response is predominately primed within the spleen and the plasmablast fate of CSP-specific B cells is driven by macrophages and CD11c+ dendritic cells.

Extrafollicular Plasmablasts Present in the Acute Phase of Infections Express High Levels of PD-L1 and Are Able to Limit T Cell Response.

During infections with protozoan parasites or some viruses, T cell immunosuppression is generated simultaneously with a high B cell activation. It has been described that, as well as producing antibodies, plasmablasts, the differentiation product of activated B cells, can condition the development of protective immunity in infections. Here, we show that, in T. cruzi infection, all the plasmablasts detected during the acute phase of the infection had higher surface expression of PD-L1 than other mononuclear cells. PD-L1hi plasmablasts were induced in vivo in a BCR-specific manner and required help from Bcl-6+CD4+T cells. PD-L1hi expression was not a characteristic of all antibody-secreting cells since plasma cells found during the chronic phase of infection expressed PD-L1 but at lower levels. PD-L1hi plasmablasts were also present in mice infected with Plasmodium or with lymphocytic choriomeningitis virus, but not in mice with autoimmune disorders or immunized with T cell-dependent antigens. In vitro experiments showed that PD-L1hi plasmablasts suppressed the T cell response, partially via PD-L1. Thus, this study reveals that extrafollicular PD-L1hi plasmablasts, whose peaks of response precede the peak of germinal center response, may have a modulatory function in infections, thus influencing T cell response.

Ym1/2 promotes Th2 cytokine expression by inhibiting 12/15(S)-lipoxygenase: identification of a novel pathway for regulating allergic inflammation.

The Ym1/2 lectin is expressed abundantly in the allergic mouse lung in an IL-13-dependent manner. However, the role of Ym1/2 in the development of allergic airways disease is largely unknown. In this investigation, we show that treatment of mice with anti-Ym1/2 Ab during induction of allergic airways disease attenuated mediastinal lymph node production of IL-5 and IL-13. Ym1/2 was found to be expressed by dendritic cells (DCs) in an IL-13-dependent manner and supplementation of DC/CD4(+) T cell cocultures with Ym1/2 enhanced the ability of IL-13(-/-) DCs to stimulate the secretion of IL-5 and IL-13. Affinity chromatography identified 12/15(S)-lipoxygenase (12/15-LOX) as a Ym1/2-interacting protein and functional studies suggested that Ym1/2 promoted the ability of DCs to stimulate cytokine production by inhibiting 12/15-LOX-mediated catalysis of 12-hydroxyeicosatetraenoic acid (12(S)-HETE). Treatment of DC/CD4(+) T cell cultures with the 12/15-LOX inhibitor baicalein enhanced, whereas 12(S)-HETE inhibited the production of Th2 cytokines. Notably, delivery of 12(S)-HETE to the airways of mice significantly attenuated the development of allergic airways inflammation and the production of IL-5 and IL-13. In summary, our results suggest that production of Ym1/2 in response to IL-13 promotes Th2 cytokine production and allergic airways inflammation by inhibiting the production of 12(S)-HETE by 12/15-LOX.

Avid binding by B cells to the Plasmodium circumsporozoite protein repeat suppresses responses to protective subdominant epitopes.

Antibodies targeting the NANP/NVDP repeat domain of the Plasmodium falciparum circumsporozoite protein (CSPRepeat) can protect against malaria. However, it has also been suggested that the CSPRepeat is a decoy that prevents the immune system from mounting responses against other domains of CSP. Here, we show that, following parasite immunization, B cell responses to the CSPRepeat are immunodominant over responses to other CSP domains despite the presence of similar numbers of naive B cells able to bind these regions. We find that this immunodominance is driven by avid binding of the CSPRepeat to cognate B cells that are able to expand at the expense of B cells with other specificities. We further show that mice immunized with repeat-truncated CSP molecules develop responses to subdominant epitopes and are protected against malaria. These data demonstrate that the CSPRepeat functions as a decoy, but truncated CSP molecules may be an approach for malaria vaccination.

NEAT1 Promotes LPS-induced Inflammatory Injury in Macrophages by Regulating MiR-17-5p/TLR4.

BACKGROUND: The inflammatory response of macrophages is responsible for sepsis. Long noncoding RNA nuclear enriched abundant transcript 1 (NEAT1) has been reported to be involved in sepsis development. However, its underlying mechanism remains largely unclear. This study aims to investigate the effect of NEAT1 on inflammatory response of macrophages and explore the regulatory network of NEAT1/microRNA-17-5p (miR-17-5p)/Toll-like receptor 4 (TLR4). METHODS: The serum samples of 68 sepsis patients and 32 heathy controls were collected. THP-1 macrophages were treated with lipopolysaccharide (LPS) to induce inflammatory injury model of sepsis. The expressions of NEAT1, miR-17-5p and TLR4 were measured by quantitative real-time polymerase chain reaction or western blot. The inflammatory response was investigated by levels of inflammatory cytokines, tumor necrosis factor-alpha (TNF-ɑ), interleukin-1beta (IL-1ß) and IL-6 as well as nitric oxide (NO) production. The interaction among NEAT1, miR-17-5p and TLR4 were investigated by bioinformatics analysis, luciferase reporter assay and RNA pull-down. RESULTS: NEAT1 expression was enhanced in patient serum and associated with severity of sepsis. Knockdown of NEAT1 inhibited levels of TNF-ɑ, IL-1ß, IL-6 and NO release in LPS-treated macrophages. miR-17-5p is bound to NEAT1 and its abrogation reversed NEAT1 knockdown-mediated inhibition of inflammatory response in LPS-treated macrophages. Overexpression of miR-17-5p weakened LPS-induced inflammatory response. TLR4 as a target of miR-17-5p was regulated by NEAT1 and miR-17-5p. TLR4 res-to ration alleviated silencing NEAT1-induced inflammatory suppression. CONCLUSION: Silence of NEAT1 suppressed LPS-induced inflammatory response of macrophages by mediating miR-17-5p and TLR4, indicating that NEAT1 might be a promising target for sepsis treatment.

Antibody Feedback Limits the Expansion of B Cell Responses to Malaria Vaccination but Drives Diversification of the Humoral Response.

Generating sufficient antibody to block infection is a key challenge for vaccines against malaria. Here, we show that antibody titers to a key target, the repeat region of the Plasmodium falciparum circumsporozoite protein (PfCSP), plateaued after two immunizations in a clinical trial of the radiation-attenuated sporozoite vaccine. To understand the mechanisms limiting vaccine responsiveness, we developed immunoglobulin (Ig)-knockin mice with elevated numbers of PfCSP-binding B cells. We determined that recall responses were inhibited by antibody feedback, potentially via epitope masking of the immunodominant PfCSP repeat region. Importantly, the amount of antibody that prevents boosting is below the amount of antibody required for protection. Finally, while antibody feedback limited responses to the PfCSP repeat region in vaccinated volunteers, potentially protective subdominant responses to PfCSP C-terminal regions expanded with subsequent boosts. These data suggest that antibody feedback drives the diversification of immune responses and that vaccination for malaria will require targeting multiple antigens.

A Natural Peptide Antigen within the Plasmodium Ribosomal Protein RPL6 Confers Liver TRM Cell-Mediated Immunity against Malaria in Mice.

Liver-resident memory CD8+ T (TRM) cells remain in and constantly patrol the liver to elicit rapid immunity upon antigen encounter and can mediate efficient protection against liver-stage Plasmodium infection. This finding has prompted the development of immunization strategies where T cells are activated in the spleen and then trapped in the liver to form TRM cells. Here, we identify PbRPL6120-127, a H2-Kb-restricted epitope from the putative 60S ribosomal protein L6 (RPL6) of Plasmodium berghei ANKA, as an optimal antigen for endogenous liver TRM cell generation and protection against malaria. A single dose vaccination targeting RPL6 provided effective and prolonged sterilizing immunity against high dose sporozoite challenges. Expressed throughout the parasite life cycle, across Plasmodium species, and highly conserved, RPL6 exhibits strong translation potential as a vaccine candidate. This is further advocated by the identification of a broadly conserved, immunogenic HLA-A∗02:01-restricted epitope in P. falciparum RPL6.

Treatment of mice with fenbendazole attenuates allergic airways inflammation and Th2 cytokine production in a model of asthma.

Mouse models have provided a significant insight into the role of T-helper (Th) 2 cytokines such as IL-5 and IL-13 in regulating eosinophilia and other key features of asthma. However, the validity of these models can be compromised by inadvertent infection of experimental mouse colonies with pathogens such as oxyurid parasites (pinworms). While the benzimidazole derivative, fenbendazole (FBZ), is commonly used to treat such outbreaks, the effects of FBZ on mouse models of Th2 disease are largely unknown. In this investigation, we show that mice fed FBZ-supplemented food during the in utero and post-weaning period developed attenuated lung eosinophilia, antigen-specific IgG1 and Th2 cytokine responses in a model of asthma. Treatment of the mediastinal lymph node cells from allergic mice with FBZ in vitro attenuated cell proliferation, IL-5 and IL-13 production and expression of the early lymphocyte activation marker, CD69 on CD4(+) T cells and CD19(+) B cells. In addition, eosinophilia and Th2 responses remained attenuated after a 4-week withholding period in allergic mice treated preweaning with FBZ. Thus, FBZ modulates the amplitude of Th2 responses both in vivo and in vitro.

Glutathione transferase P1: an endogenous inhibitor of allergic responses in a mouse model of asthma.

RATIONALE: Although epidemiological studies have linked asthma susceptibility and severity to polymorphisms in human glutathione transferase Pi (GSTP) 1, there is no direct evidence for a functional involvement of GSTP1 in processes that are pathognomic of asthma. OBJECTIVES: To examine the role of GSTP1 in modulating the development of allergic airways disease. METHODS: Allergic airways disease was induced in wild-type (WT) and Gstp-null mice employing both acute and chronic models. Eosinophilia, goblet cells, and remodeling were quantified by histological assessment; respiratory function was determined using invasive methods. ELISA was used to evaluate Th2 cytokines, eotaxin, and phospho-c-Jun. Gstp1/2 expression was quantified by reverse transcriptase-polymerase chain reaction. MEASUREMENTS AND MAIN RESULTS: Compared with allergic WT mice, eosinophilia, goblet cell hyperplasia, airway remodeling, lung resistance, and IL-5 were enhanced in allergic Gstp-null mice. However, the protective efficacy of GSTP1 was mouse-strain dependent, and associated with inherent variation in expression of Gstp1. Although elevated levels of phospho-c-Jun were detected in Gstp-null mice, treatment of WT mice with a GSTP/c-Jun N-terminal kinase (JNK) inhibitory peptide enhanced phospho-c-Jun and significantly attenuated allergic responses. CONCLUSIONS: GSTP1 attenuates the severity of allergic airways disease. However, the efficacy of GSTP1 correlated with mouse strain-dependent variation in Gstp1 expression. Although GSTP1 attenuated c-Jun phosphorylation, treatment with a GSTP/JNK inhibitory peptide revealed an inverse relationship between c-Jun phosphorylation and allergic responses, indicating that the mechanism by which GSTP attenuates allergic responses is not dependent on the JNK/c-Jun axis. Our data, together with epidemiological evidence, suggest variation in expression and/or function of this protein is an important determinant in asthma pathophysiology.

[Analysis of risk factors in prognosis in patients requiring long-term mechanical ventilation].

OBJECTIVE: To analyze risk factors in patients receiving mechanical ventilation in intensive care unit (ICU). METHODS: The study group consisted of 42 patients receiving mechanical ventilation for longer than 7 days. The general condition, primary diseases, the vital signs before ventilation, accessory examination, acute physiology and chronic health evaluation II (APACHE II) score, and the time of tracheostomy were collected. The patients were divided into two groups of deceased or survived when the mechanical ventilation was weaned. Comparative analysis of all the data was made with Logistic multiple regression. RESULTS: Of the patients enrolled in the study, 22 (52.4%) survived and 20 (47.6%) died in the ICU. Difference in clinical data between death group and survival group was significant (P<0.05). In death group, the APACHE II score, the pressure adjusted heart rate (PAR), the level of blood urea nitrogen (BUN) were higher (all P<0.01), while the level of plasma albumin (ALB), the level of hematocrit (HCT) value, the amount of platelets (PLT) were lower (P<0.05 or P<0.01), and the time of tracheostomy was later compared with those of survival group (P<0.05). There were no significant differences in the time of mechanical ventilation, white blood cells (WBC) and incidence of ventilator-associated pneumonia (VAP) between two groups (all P>0.05). With Logistic multiple regression analysis, the time of tracheostomy, the levels of HCT value, the amount of PLT were correlated with requirement of long-term mechanical ventilation (LTMV) (P<0.05 or P<0.01). CONCLUSION: The time of tracheostomy, the levels of HCT value, the amount of PLT were independent risk factors associated with patients requiring LTMV.

Dexmedetomidine attenuates lipopolysaccharide-induced acute lung injury by inhibiting oxidative stress, mitochondrial dysfunction and apoptosis in rats.

Previous studies have identified that dexmedetomidine (DEX) treatment can ameliorate the acute lung injury (ALI) induced by lipopolysaccharide and ischemia-reperfusion. However, the molecular mechanisms by which DEX ameliorates lung injury remain unclear. The present study investigated whether DEX, which has been reported to exert effects on oxidative stress, mitochondrial permeability transition pores and apoptosis in other disease types, can exert protective effects in lipopolysaccharide (LPS)­induced ALI by inhibiting oxidative stress, mitochondrial dysfunction and mitochondrial­dependent apoptosis. It was revealed that LPS­challenged rats exhibited significant lung injury, characterized by the deterioration of histopathology, vascular hyperpermeability, wet­to­dry weight ratio and oxygenation index (PaO2/FIO2), which was attenuated by DEX treatment. DEX treatment inhibited LPS­induced mitochondrial dysfunction, as evidenced by alleviating the cellular ATP and mitochondrial membrane potential in vitro. In addition, DEX treatment markedly prevented the LPS­induced mitochondrial­dependent apoptotic pathway in vitro (increases of cell apoptotic rate, cytosolic cytochrome c, and caspase 3 activity) and in vivo (increases of |terminal deoxynucleotidyl transferase dUTP nick­end labeling positive cells, cleaved caspase 3, Bax upregulation and Bcl­2 downregulation). Furthermore, DEX treatment markedly attenuated LPS­induced oxidative stress, as evidenced by downregulation of cellular reactive oxygen species in vitro and lipid peroxides in serum. Collectively, the present results demonstrated that DEX ameliorates LPS­induced ALI by reducing oxidative stress, mitochondrial dysfunction and mitochondrial-dependent apoptosis.

Cationic amino acid transporters play key roles in the survival and transmission of apicomplexan parasites.

Apicomplexans are obligate intracellular parasites that scavenge essential nutrients from their hosts via transporter proteins on their plasma membrane. The identities of the transporters that mediate amino acid uptake into apicomplexans are unknown. Here we demonstrate that members of an apicomplexan-specific protein family-the Novel Putative Transporters (NPTs)-play key roles in the uptake of cationic amino acids. We show that an NPT from Toxoplasma gondii (TgNPT1) is a selective arginine transporter that is essential for parasite survival and virulence. We also demonstrate that a homologue of TgNPT1 from the malaria parasite Plasmodium berghei (PbNPT1), shown previously to be essential for the sexual gametocyte stage of the parasite, is a cationic amino acid transporter. This reveals a role for cationic amino acid scavenging in gametocyte biology. Our study demonstrates a critical role for amino acid transporters in the survival, virulence and life cycle progression of these parasites.