IL-15 transpresentation promotes both human T-cell reconstitution and T-cell-dependent antibody responses in vivo

Cytokine immunotherapies targeting T lymphocytes are attractive clinical interventions against viruses and tumors. In the mouse, the homeostasis of memory α/β CD8⁺ T cells and natural killer (NK) cells is significantly improved with increased IL-15 bioavailability. In contrast, the role of “transpresented” IL-15 on human T-cell development and homeostasis in vivo is unknown. We found that both CD8 and CD4 T cells in human immune system (HIS) mice are highly sensitive to transpresented IL-15 in vivo, with both naïve (CD62L⁺CD45RA⁺) and memory phenotype (CD62L⁻CD45RO⁺) subsets being significantly increased following IL-15 “boosting.” The unexpected global improvement in human T-cell homeostasis involved enhanced proliferation and survival of both naïve and memory phenotype peripheral T cells, which potentiated B-cell responses by increasing the frequency of antigen-specific responses following immunization. Transpresented IL-15 did not modify T-cell activation patterns or alter the global T-cell receptor (TCR) repertoire diversity. Our results indicate an unexpected effect of IL-15 on human T cells in vivo, in particular on CD4⁺ T cells. As IL-15 promotes human peripheral T-cell homeostasis and increases the frequency of neutralizing antibody responses in HIS mice, IL-15 immunotherapy could be envisaged as a unique approach to improve vaccine responses in the clinical setting.In vivo studies of lymphocyte development, homeostasis, and immune responses upon infection, antigenic challenge, or following vaccination have been largely characterized in mice. Although this line of experimentation is valuable, 60 million years of evolution have generated important differences between murine and human immune systems, and therefore some of the knowledge derived from mouse models may not be directly applicable to humans. An intermediate between murine and human in vivo studies exists in the form of human immune system (HIS) mice. A recently developed HIS mouse model involves engraftment of newborn BALB/c Rag2^−/− γ_c^−/− mice with human hematopoietic stem cells (HSCs) from fetal liver or cord blood, which generates human innate and adaptive lymphocytes and dendritic cell subsets required for immune responses (1–3). HIS mice are proving to be a very powerful biotechnology, and although they are successfully used to model human hematopoiesis, their capacity for studying human immune responses is suboptimal (2). This is likely due to perturbed homeostasis of human T cells in BALB/c Rag2^−/− γ_c^−/− HIS mice, as these cells exhibit an abnormally high turnover rate and fail to accumulate (1–5). Not surprisingly, many current efforts are focused on improving human T-cell reconstitution and homeostasis in HIS mice with the ultimate goal of inducing robust and consistent human immune responses in vivo.T-cell homeostasis comprises T-cell generation in the thymus, export to the periphery, maintenance of the peripheral naïve T-cell pool, and regulation of activated effector and memory T-cell compartments (6). Several signals have been implicated in controlling T-cell homeostasis, including those emanating from the T-cell receptor (TCR) following interactions with self-peptide + major histocompatibility complex (pMHC) and those induced by growth factors, including cytokines (6). The common cytokine receptor gamma chain (γ_c) family of cytokines (which comprises IL-2, IL-4, IL-7, IL-9, IL-15, and IL-21) in particular have been demonstrated to play a role in T-cell homeostasis in mammals (7). Humans and mice possessing mutations in genes encoding the γ_c, Jak3 (both critical for signal transduction following binding γ_c cytokines) or the alpha chain of the IL-7 receptor (IL-7Rα), display a severe block in T-cell development and resulting severe combined immunodeficiency (8, 9). The γ_c-dependent cytokine IL-15 is unusual because its bioactive form is a functional complex associated with the IL-15Rα chain. Thus, cells expressing IL-15 such as monocytes, dendritic cells, and stromal cells must also coexpress the IL-15Rα to “transpresent” IL-15 to IL-15–responsive cells (that express the IL-2Rβ/γ_c complex). Accordingly, both IL-15 and IL-15Rα are up-regulated on myeloid cells following inflammation, thereby increasing IL-15 bioavalability (10–12).We demonstrated that transpresented murine IL-15 inefficiently triggered human natural killer (NK) cells in vitro and in vivo providing an explanation for the poor human NK cell reconstitution in BALB/c Rag2^−/− γ_c^−/− HIS mice (3). Exogenous administration of a potent human IL-15R agonist (referred to as RLI, consisting of human IL-15 covalently linked to an extended human IL-15Rα “sushi” domain thus mimicking IL-15 transpresentation) (13–15) was sufficient to restore human NK cell development in HIS mice (3). Whereas memory CD8⁺ T cells in mice are highly responsive to exogenous IL-15 (6, 11–14), naïve CD4⁺ and CD8⁺ T cells are not thought to require IL-15 for normal homeostasis (6, 11–14). However, in vivo effects of human IL-15 on human T cells have not been studied, and it remained possible that the poor reactivity of human T cells to mouse IL-15 might also contribute to the low human T-cell reconstitution in the HIS mouse model. Here we show that human IL-15 transpresentation increases human T-cell reconstitution and the frequency of T-cell–dependent antibody responses in HIS mice. These studies provide a first preclinical trial of transpresented human IL-15 on human T cells in vivo and indicate that increased IL-15 bioavailability globally boosts human naïve and memory T-cell homeostasis in this humanized mouse model. Our findings offer a unique approach to study human T-cell immune responses in vivo and suggest that IL-15 immunotherapy may be useful to promote global T-cell reconstitution in humans.     

Preassembly of interleukin 2 (IL-2) receptor subunits on resting Kit 225 K6 T cells and their modulation by IL-2, IL-7, and IL-15: A fluorescence resonance energy transfer study

Assembly and mutual proximities of α, β, and γ_c subunits of the interleukin 2 receptors (IL-2R) in plasma membranes of Kit 225 K6 T lymphoma cells were investigated by fluorescence resonance energy transfer (FRET) using fluorescein isothiocyanate- and Cy3-conjugated monoclonal antibodies (mAbs) that were directed against the IL-2Rα, IL-2Rβ, and γ_c subunits of IL-2R. The cell-surface distribution of subunits was analyzed at the nanometer scale (2–10 nm) by FRET on a cell-by-cell basis. The cells were probed in resting phase and after coculture with saturating concentrations of IL-2, IL-7, and IL-15. FRET data from donor- and acceptor-labeled IL-2Rβ-α, γ-α, and γ-β pairs demonstrated close proximity of all subunits to each other in the plasma membrane of resting T cells. These mutual proximities do not appear to represent mAb-induced microaggregation, because FRET measurements with Fab fragments of the mAbs gave similar results. The relative proximities were meaningfully modulated by binding of IL-2, IL-7, and IL-15. Based on FRET analysis the topology of the three subunits at the surface of resting cells can be best described by a “triangular model” in the absence of added interleukins. IL-2 strengthens the bridges between the subunits, making the triangle more compact. IL-7 and IL-15 act in the opposite direction by opening the triangle possibly because they associate their private specific α receptors with the β and/or γ_c subunits of the IL-2R complex. These data suggest that IL-2R subunits are already colocalized in resting T cells and do not require cytokine-induced redistribution. This colocalization is significantly modulated by binding of relevant interleukins in a cytokine-specific manner.     

Titanium dioxide induced inflammation in the small intestine

AIM: To investigate the effects of titanium dioxide (TiO₂) nanoparticles (NPTiO₂) and microparticles (MPTiO₂) on the inflammatory response in the small intestine of mice.METHODS: Bl 57/6 male mice received distilled water suspensions containing TiO₂ (100 mg/kg body weight) as NPTiO₂ (66 nm), or MPTiO₂ (260 nm) by gavage for 10 d, once a day; the control group received only distilled water. At the end of the treatment the duodenum, jejunum and ileum were extracted for assessment of cytokines, inflammatory cells and titanium content. The cytokines interleukin (IL)-1b, IL-4, IL-6, IL-8, IL-10, IL-12, IL-13, IL-17, IL-23, tumor necrosis factor-α (TNF-α), intracellular interferon-γ (IFN-γ) and transforming growth factor-β (TGF-β) were evaluated by enzyme-linked immunosorbent assay in segments of jejunum and ileum (mucosa and underlying muscular tissue). CD4⁺ and CD8⁺ T cells, natural killer cells, and dendritic cells were evaluated in duodenum, jejunum and ileum samples fixed in 10% formalin by immunohistochemistry. The titanium content was determined by inductively coupled plasma atomic emission spectrometry.RESULTS: We found increased levels of T CD4⁺ cells (cells/mm²) in duodenum: NP 1240 ± 139.4, MP 1070 ± 154.7 vs 458 ± 50.39 (P < 0.01); jejunum: NP 908.4 ± 130.3, MP 813.8 ± 103.8 vs 526.6 ± 61.43 (P < 0.05); and ileum: NP 818.60 ± 123.0, MP 640.1 ± 32.75 vs 466.9 ± 22.4 (P < 0.05). In comparison to the control group, the groups receiving TiO₂ showed a statistically significant increase in the levels of the inflammatory cytokines IL-12, IL-4, IL-23, TNF-α, IFN-γ and TGF-β. The cytokine production was more pronounced in the ileum (mean ± SE): IL-12: NP 33.98 ± 11.76, MP 74.11 ± 25.65 vs 19.06 ± 3.92 (P < 0.05); IL-4: NP 17.36 ± 9.96, MP 22.94 ± 7.47 vs 2.19 ± 0.65 (P < 0.05); IL-23: NP 157.20 ± 75.80, MP 134.50 ± 38.31 vs 22.34 ± 5.81 (P < 0.05); TNFα: NP 3.71 ± 1.33, MP 5.44 ± 1.67 vs 0.99 ± 019 (P < 0.05); IFNγ: NP 15.85 ± 9.99, MP 34.08 ± 11.44 vs 2.81 ± 0.69 (P < 0.05); and TGF-β: NP 780.70 ± 318.50, MP 1409.00 ± 502.20 vs 205.50 ± 63.93 (P < 0.05).CONCLUSION: Our findings indicate that TiO₂ particles induce a Th1-mediated inflammatory response in the small bowel in mice.     

Computational design of a symmetric homodimer using β-strand assembly

Computational design of novel protein–protein interfaces is a test of our understanding of protein interactions and has the potential to allow modification of cellular physiology. Methods for designing high-affinity interactions that adopt a predetermined binding mode have proved elusive, suggesting the need for new strategies that simplify the design process. A solvent-exposed backbone on a β-strand is thought of as “sticky” and β-strand pairing stabilizes many naturally occurring protein complexes. Here, we computationally redesign a monomeric protein to form a symmetric homodimer by pairing exposed β-strands to form an intermolecular β-sheet. A crystal structure of the designed complex closely matches the computational model (rmsd = 1.0 Å). This work demonstrates that β-strand pairing can be used to computationally design new interactions with high accuracy.     

Structural and kinetic modeling of an activating helix switch in the rhodopsin-transducin interface

Extracellular signals prompt G protein-coupled receptors (GPCRs) to adopt an active conformation (R*) and catalyze GDP/GTP exchange in the α-subunit of intracellular G proteins (Gαβγ). Kinetic analysis of transducin (G_tαβγ) activation shows that an intermediary R*·G_tαβγ·GDP complex is formed that precedes GDP release and formation of the nucleotide-free R*·G protein complex. Based on this reaction sequence, we explore the dynamic interface between the proteins during formation of these complexes. We start from the R* conformation stabilized by a G_tα C-terminal peptide (GαCT) obtained from crystal structures of the GPCR opsin. Molecular modeling allows reconstruction of the fully elongated C-terminal α-helix of G_tα (α5) and shows how α5 can be docked to the open binding site of R*. Two modes of interaction are found. One of them – termed stable or S-interaction – matches the position of the GαCT peptide in the crystal structure and reproduces the hydrogen-bonding networks between the C-terminal reverse turn of GαCT and conserved E(D)RY and NPxxY(x)_5,6F regions of the GPCR. The alternative fit – termed intermediary or I-interaction – is distinguished by a tilt (42°) and rotation (90°) of α5 relative to the S-interaction and shows different α5 contacts with the NPxxY(x)_5,6F region and the second cytoplasmic loop of R*. From the 2 α5 interactions, we derive a “helix switch” mechanism for the transition of R*·G_tαβγ·GDP to the nucleotide-free R*·G protein complex that illustrates how α5 might act as a transmission rod to propagate the conformational change from the receptor-G protein interface to the nucleotide binding site.     

Graph fission in an evolving voter model

We consider a simplified model of a social network in which individuals have one of two opinions (called 0 and 1) and their opinions and the network connections coevolve. Edges are picked at random. If the two connected individuals hold different opinions then, with probability 1 - α, one imitates the opinion of the other; otherwise (i.e., with probability α), the link between them is broken and one of them makes a new connection to an individual chosen at random (i) from those with the same opinion or (ii) from the network as a whole. The evolution of the system stops when there are no longer any discordant edges connecting individuals with different opinions. Letting ρ be the fraction of voters holding the minority opinion after the evolution stops, we are interested in how ρ depends on α and the initial fraction u of voters with opinion 1. In case (i), there is a critical value α_c which does not depend on u, with ρ ≈ u for α > α_c and ρ ≈ 0 for α < α_c. In case (ii), the transition point α_c(u) depends on the initial density u. For α > α_c(u), ρ ≈ u, but for α < α_c(u), we have ρ(α,u) = ρ(α,1/2). Using simulations and approximate calculations, we explain why these two nearly identical models have such dramatically different phase transitions.     

Interleukin-17 plays a critical role in the acute rejection of intestinal transplantation

AIM:To investigate the role of interleukin(IL)-17 in small bowel allograft rejection.METHODS:We detected the expression of helper T cell 17(Th17)cells in biopsy specimens from 3 cases of living small bowel transplantation in our department through immunofluorescence stain.We then established a rat heterotopic small bowel transplantation model.The rats were sacrificed on the 1st,2nd,3rd,5th, and 7th d after small bowel transplantation.The degrees of transplantation rejection in rat intestine graft were examined through hematoxylin eosin(HE)stain, and the expression of Th17 cells in rat intestine graft were detected through immunofluorescence stain. In addition,the recipient rats undergoing intestinal transplantation were administrated with mouse-anti-rat IL-17 monoclonal antibody(mAb),and the survival of rats was analyzed.The recipient rats which received mouse-anti-rat IL-17 mAb treatment were sacrificed on the 1st,2nd,3rd,5th,and 7th d after small bowel transplantation.The degrees of transplantation rejection and the expression of Th17 cells in rat intestine graft were detected through HE and immunofluorescence stain. The expression of IL-17,IL-1β,tumor necroses factor receptor-α(TNF-α),IL-6,and IL-8 in the intestine graft or serum were also detected. RESULTS:The expressions of Th17 cells ran parallel with the degree of acute rejection in human intestine grafts.The intestine graft rejection of rats was aggravated with prolonged duration after intestinal transplantation,and the expressions of Th17 cells were also correlated with the degree of acute rejection in rat intestine grafts.Administration of mouse-anti-rat IL-17 mAb prolonged the survival of rats after small bowel transplantation(P<0.001).Furthermore,we found that the administration of mouse-anti-rat IL-17 mAb significantly decreased the intensity of CD4+IL-17+Th17 cells in intestine grafts on the 2nd,3rd,5th,and the 7th d (97.22±4.05vs 12.45±2.02 on the 7th d,P<0.0001), and suppressed the severity of acute rejection.The expression of IL-17 in     

VLA-4 integrin concentrates at the peripheral supramolecular activation complex of the immune synapse and drives T helper 1 responses

The integrin α4β1 (VLA-4) not only mediates the adhesion and transendothelial migration of leukocytes, but also provides costimulatory signals that contribute to the activation of T lymphocytes. However, the behavior of α4β1 during the formation of the immune synapse is currently unknown. Here, we show that α4β1 is recruited to both human and murine antigen-dependent immune synapses, when the antigen-presenting cell is a B lymphocyte or a dendritic cell, colocalizing with LFA-1 at the peripheral supramolecular activation complex. However, when conjugates are formed in the presence of anti-α4 antibodies, VLA-4 colocalizes with the CD3-ζ chain at the center of the synapse. In addition, antibody engagement of α4 integrin promotes polarization toward a T helper 1 (Th1) response in human in vitro models of CD4⁺ T cell differentiation and naïve T cell priming by dendritic cells. The in vivo administration of anti-α4 integrin antibodies also induces an immune deviation to Th1 response that dampens a Th2-driven autoimmune nephritis in Brown Norway rats. These data reveal a regulatory role of α4 integrins on T lymphocyte-antigen presenting cell cognate immune interactions.After the recognition of antigens (Ag) presented by dendritic cells (DCs), naïve T lymphocytes proliferate and differentiate into T helper (Th) 1 or 2 effector cells. These effector lymphocytes are characterized by distinct patterns of cytokine production and homing behavior. Th1 cells mainly produce IFN-γ and IL-2 and have a key role in the cellular immune responses. Conversely, Th2 cells produce IL-4, IL-5, IL-6, and IL-10 and promote the humoral immune responses (1). DCs are the only Ag-presenting cells (APCs) involved in the priming of naïve Th cells and their polarization toward Th1 or Th2 differentiation. To acquire this capacity, DCs must undergo a maturation process characterized by the loss of their Ag-capturing capacity and the increase of their expression of costimulatory and adhesion molecules, including α4β1 integrin (2). However, other APCs (e.g., B lymphocytes) are also involved in regulating the cytokine profiles of Th cell responses, indicating the importance of postpriming events (3).The interaction between T cells and APCs plays an important role in directing Th cell polarization. The strength of antigenic stimulation, the duration of T cell receptor engagement, the presence of different cytokines, and the participation of distinct costimulatory molecules are critical in determining the phenotype of differentiated T cells. The cytokine IL-12, high doses of Ag, and CD28/B7–1 interaction promote Th1 differentiation, whereas an environment enriched in IL-4, low doses of Ag, and CD28/B7–2 or inducible costimulator (ICOS)/ICOS ligand participation promote Th2 responses (4).Integrins are a large family of αβ heterodimeric transmembrane proteins that mediate cell–cell and cell–extracellular matrix adhesion. Several integrins, lymphocyte function-associated (LFA-1; α_Lβ₂), very late activation antigen-4 (VLA-4; α4β1), and VLA-1 (α1β1) have been involved also in the transduction of costimulatory signals in T cells (5). However, whereas the involvement of α_Lβ2 during Ag presentation is well known, the role of α4β1 has not been addressed. The α_Lβ2 integrin mediates T cell adhesion to APCs, facilitating the formation of the immunological synapse (IS) (6). The pair α_Lβ₂/intracellular adhesion molecule-1 (ICAM-1) forms an adhesion ring that is called the peripheral supramolecular activation complex (pSMAC), that surrounds the T cell receptor–peptide–MHC complexes localized at the central SMAC of the IS (7, 8). Several studies in mouse models revealed that α_Lβ₂/ICAM-1 interaction could be important for driving Th1 polarization (9, 10).The α4β1 integrin is predominantly expressed on hematopoietic cells and serves as a receptor for fibronectin and vascular cell adhesion molecule 1 (VCAM-1). In addition to mediating leukocyte adhesion to endothelium and extracellular matrix, α4β1 has been implicated in T cell costimulation (11–13). The dual role of α4β1 as an adhesion and costimulatory molecule suggests that this integrin could be involved in the modulation of the T cell response during Ag presentation. However, the behavior of α4β1 and its possible function during the establishment of an IS has not been examined. Here, we show that α4β1 is recruited to the pSMAC of IS colocalizing with LFA-1 integrin. We also demonstrate the functional involvement of this integrin in the priming of T lymphocytes toward a Th1 response in vitro and in vivo.     

Structure of an Iron(II) Dioxygen Complex; A Model for Oxygen Carrying Hemeproteins

The preliminary structural characterization of a reversible ferrous dioxygen complex is reported. Mono(N-methyl imidazole) (dioxygen) meso-tetra (α,α,α,α-o-pivalamidephenyl) porphinatorino(II), [Fe(O₂)-(N-Me imid) (α,α,α,α-TpivPP)], 1, isolated from toluene solution, crystallizes in the monoclinic system with four molecules in a unit cell of dimensions a = 18.690 (3), b = 19.514 (3), c = 18.638 (3) Å, and β = 91.00 (1)°. R = 0.15 for 841 reflections having F² > 3σ (F²).The complex 1 has four pivalamido groups on one side of the porphyrin forming a hydrophobic pocket of 5.4-Å depth which encloses coordinated dioxygen. The dioxygen is coordinated “end-on,” with a bent Fe-O-O bond. The Fe-O-O plane bisects an N-Fe-N right angle of the equatorial iron porphyrin plane and is four way statistically disordered. In addition there is a crystallographic 2-fold axis through iron, coordinated oxygen, and nitrogen of the axially bound N-methyl imidazole. Thus there are two types of coordinated dioxygen with the Fe-O-O plane either parallel or perpendicular to the trans axial imidazole plane. Corresponding values for the Fe-O-O bond angles are 135-(4)° and 137(4)° and for the O-O bond lengths are 1.23 (0.08) and 1.26 (0.08) Å, with a dihedral angle of 90° between alternative orientations of the Fe-O-O plane. The Fe-O distance is 1.75 (0.02) Å and Fe-N (imidazole) is 2.07 (0.02) Å, suggesting multiple bond character in the Fe-O moiety. The similarity of the Mössbauer spectrum of the model complex, 1, with oxyhemoglobin indicates that 1 may be a good model for oxygen binding in the oxygen transport hemeproteins.     

Interleukin 7 (IL-7) selectively promotes mouse and human IL-17�Cproducing �æ� cells

IL-17–producing CD27⁻ γδ cells (γδ²⁷⁻ cells) are widely viewed as innate immune cells that make critical contributions to host protection and autoimmunity. However, factors that promote them over IFN-γ–producing γδ²⁷⁺ cells are poorly elucidated. Moreover, although human IL-17–producing γδ cells are commonly implicated in inflammation, such cells themselves have proved difficult to isolate and characterize. Here, murine γδ²⁷⁻ T cells and thymocytes are shown to be rapidly and substantially expanded by IL-7 in vitro and in vivo. This selectivity owes in substantial part to the capacity of IL-7 to activate STAT3 in such cells. Additionally, IL-7 promotes strong responses of IL-17–producing γδ cells to TCR agonists, thus reemphasizing the cells’ adaptive and innate potentials. Moreover, human IL-17–producing γδ cells are also substantially expanded by IL-7 plus TCR agonists. Hence, IL-7 has a conserved potential to preferentially regulate IL-17–producing γδ cells, with both biological and clinical implications.     

Ethyl pyruvate protects against experimental acute-on-chronic liver failure in rats

AIM:To investigate the protective effects of ethyl pyruvate(EP) on acute-on-chronic liver failure(ACLF) in rats.METHODS:An ACLF model was established in rats,and animals were randomly divided into normal,model and EP treatment groups.The rats in EP treatment group received EP(40 mg/kg) at 3 h,6 h,12 h and 24 h after induction of ACLF.Serum endotoxin,high mobility group box-1(HMGB1),alanine transaminase(ALT),tumor necrosis factor-(TNF-),interferon-(IFN-),interleukin(IL)-10 and IL-18 levels,changes of liver histology and HMGB1 expressions in liver tissues were detected at 48 h after induction of ACLF.The effects of EP on the survival of ACLF rats were also observed.RESULTS:Serum levels of endotoxin(0.394 ± 0.066 EU/mL vs 0.086 ± 0.017 EU/mL,P 0.001),HMGB1(35.42 ± 10.86 g/L vs 2.14 ± 0.27 g/L,P 0.001),ALT(8415.87 ± 3567.54 IU/L vs 38.64 ± 8.82 IU/L,P 0.001),TNF-(190.77 ± 12.34 ng/L vs 124.40 ± 4.12 ng/L,P 0.001),IFN-(715.38 ± 86.03 ng/L vs 398.66 ± 32.91 ng/L,P 0.001),IL-10(6.85 ± 0.64 ng/L vs 3.49 ± 0.24 ng/L,P 0.001) and IL-18(85.19 ± 3.49 ng/L vs 55.38 ± 1.25 ng/L,P 0.001) were significantly increased,and liver tissues presented severe pathological injury in the model group compared with the normal group.However,EP administration significantly improved hepatic histopathology and reduced the serum levels of endotoxin(0.155 ± 0.045 EU/mL vs 0.394 ± 0.066 EU/mL,P 0.001) and inflammatory cytokines(11.13 ± 2.58 g/L vs 35.42 ± 10.86 g/L for HMGB1,3512.86 ± 972.67 IU/L vs 8415.87 ± 3567.54 IU/L for ALT,128.55 ± 5.76 ng/L vs 190.77 ± 12.34 ng/L for TNF-,438.16 ± 38.10 ng/L vs 715.38 ± 86.03 ng/L for IFN-,3.55 ± 0.36 ng/L vs 6.85 ± 0.64 ng/L for IL-10,and 60.35 ± 1.63 ng/L vs 85.19 ± 3.49 ng/L for IL-18,respectively,P 0.001),and the levels of HMGB1 in liver tissues regardless of treatment time after induction of ACLF.EP treatment at the four time points prolonged the median survival time of ACLF rats(60 h) to 162 h,120 h,102 h and 78 h,respectively(2 = 41.17,P 0.0001).CONCLUSION:EP administration can protect against ACLF in rats,and is a potential and novel therapeutic agent for severe liver injury.     

Dihydromyricetin alleviates carbon tetrachloride-induced acute liver injury via JNK-dependent mechanism in mice

AIM: To assess the effects of dihydromyricetin(DHM) as a hepatoprotective candidate in reducing hepatic injury and accelerating hepatocyte proliferation after carbon tetrachloride(CCl4) treatment.METHODS: C57 BL/6 mice were used in this study. Mice were orally administered with DHM(150 mg/kg) for 4 d after CCl4 treatment. Serum and liver tissue samples were collected on days 1, 2, 3, 5 and 7 after CCl4 treatment. The anti-inflammatory effect of DHM was assessed directly by hepatic histology detection and indirectly by serum levels of aspartate aminotransferase(AST), alanine aminotransferase(ALT), albumin, and superoxide dismutase(SOD). Inflammatory cytokines, such as interleukin(IL)-1β, IL-6 and tumor necrosis factor-α(TNF-α), were detected using ELISA kits. Proliferating cell nuclear antigen(PCNA) staining was used to evaluate the role of DHM in promoting hepatocyte proliferation. Hepatocyte apoptosis wasmeasured by TUNEL assay.Furthermore,apoptosis proteins Caspases-3,6,8,and 9 were detected by Western blot.SP600125 were used to confirm whether DHM regulated liver regeneration through JNK/TNF-αpathways.RESULTS:DHM showed a strong anti-inflammatory effect on CCl4-induced liver injury in mice.DHM could significantly decrease serum ALT,AST,IL-1β,IL-6 and TNF-αand increase serum albumin,SOD and liver SOD compared to the control group after CCl4 treatment(P0.05).PCNA results indicated that DHM could significantly increase the number of PCNA positive cells compared to the control(348.9±56.0 vs 107.1±31.4,P0.01).TUNEL assay showed that DHM dramatically reduced the number of apoptotic cells after CCl4 treatment compared to the control(365.4±99.4 vs 90.5±13.8,P0.01).Caspase activity detection showed that DHM could reduce the activities of Caspases-8,3,6 and 9 compared to the control(P0.05).The results of Western blot showed that DHM increased the expression of JNK and decreased TNF-αexpression.However,DHM could not affect TNF-αexpression after SP600125 treatment.Furthermore,DHM could significantly improve the survival rate of acute liver failure(ALF)mice(73.3%vs 20.0%,P0.0001),and SP600125 could inhibit the effect of DHM.CONCLUSION:These findings demonstrate that DHM alleviates CCl4-induced liver injury,suggesting that DHM is a promising candidate for reversing liver injury and ALF.     

Systemic inflammation after inspiratory loading in chronic obstructive pulmonary disease

Objective

Patients with chronic obstructive pulmonary disease (COPD) present systemic inflammation. Strenuous resistive breathing induces systemic inflammation in healthy subjects. We hypothesized that the increased respiratory load that characterizes COPD can contribute to systemic inflammation in these patients.

Patients and methods

To test this hypothesis, we compared leukocyte numbers and levels of circulating cytokines (tumor necrosis factor alpha [TNFα], interleukin-1β [IL-1β], IL-6, IL-8, and IL-10), before and 1 hour after maximal incremental inspiratory loading in 13 patients with stable COPD (forced expiratory volume in one second [FEV₁] 29 ± 2.5% ref) and in 8 healthy sedentary subjects (FEV₁ 98 ± 5% ref).

Results

We found that: (1) at baseline, patients with COPD showed higher leukocyte counts and IL-8 levels than controls (p < 0.01); and, (2) one hour after maximal inspiratory loading these values were unchanged, except for IL-10, which increased in controls (p < 0.05) but not in patients with COPD.

Conclusions

This study confirms the presence of systemic inflammation in COPD, shows that maximal inspiratory loading does not increase the levels of pro-inflammatory cytokines (IL-1β, IL-8) in COPD patients or controls, but suggests that the former may be unable to mount an appropriate systemic anti-inflammatory response to exercise.     

Protective effect of naringenin on acetic acid-induced ulcerative colitis in rats

AIM:To evaluate the ameliorative effect of naringenin(NG)during ulcerative colitis(UC)in rats.METHODS:Rats were treated with three different doses(25,50 and 100 mg/kg per day)of NG and a single dose of mesalazine(MES,300 mg/kg per day)for seven days prior to ulcerative colitis induction by4%acetic acid(AA).Twenty four hours after AA rectal administration,animals were scarified and the colonic tissues were dissected.Colonic mucus content was estimated using Alcian blue dye binding technique.In colon tissues,levels of total glutathione sulphadryls(T-GSH),non-protein sulphadryls(NP-SH)and thiobarbituric acid reactive substances(TBARS)were evaluated.The activities of the antioxidant enzymes,catalase(CAT)and superoxide dismutase(SOD)were measured.Concentrations of nucleic acids(DNA and RNA)and total protein were also estimated in colon tissues.Colonic levels of tumor necrosis factor-(TNF-),interleukin-1(IL-1),interleukin-6(IL-6),prostaglandin E2(PGE2)and nitric oxide(NO)were estimated.In cross section of colitis tissue the histopathological changes were observed.RESULTS:Colonic mucus content was decreased in AA compared to controls(587.09±65.59 mg/kg vs941.78±68.41 mg/kg,P<0.001).AA administration markedly reduced T-GSH(5.25±0.37 nmol/L vs 3.04±0.24 nmol/L,P<0.01),NP-SH(3.16±0.04 nmol/L vs 2.16±0.30 nmol/L,P<0.01),CAT(6.77±0.40 U/mg vs 3.04±0.2 U/mg,P<0.01)and SOD(3.10±0.11U/mg vs 1.77±0.18 U/mg,P<0.01)while TBARS,TNF-,IL-1,IL-6,PGE2 and NO levels(15.09±3.84nmol/L vs 59.90±16.34 nmol/L,P<0.01;113.56±1.91 pg/mg vs 134.24±4.77 pg/mg,P<0.01;209.20±36.38 pg/mg vs 422.19±31.47 pg/mg,P<0.01;250.83±25.09 pg/mg vs 638.58±115.9 pg/mg,P<0.01;248.19±36.98 pg/mg vs 541.74±58.34 pg/mg,P<0.01 and 81.26±2.98 mmol/g vs 101.90±10.73 mmol/g,P<0.001)were increased in colon of rats with UC compared controls respectively.Naringenin supplementation,significantly and dose dependently increased the colonic mucus content.The elevated TBARS levels were significantly decreased(39.35±5.86n     

Estimating the hospitalization burden associated with influenza and respiratory syncytial virus in New York City, 2003–2011

Background

Hospitalization burden associated with influenza and respiratory syncytial virus (RSV) is uncertain due to ambiguity in the inference methodologies employed for its estimation.

Objectives

Utilization of a new method to quantitate the above burden.

Methods

Weekly hospitalization rates for several principal diagnoses from 2003 to 2011 in New York City by age group were regressed linearly against incidence proxies for the major influenza subtypes and RSV adjusting for temporal trends and seasonal baselines.

Results

Average annual rates of influenza-associated respiratory hospitalizations per 100 000 were estimated to be 129 [95% CI (79, 179)] for age <1, 36·3 (21·6, 51·4) for ages 1–4, 10·6 (7·5, 13·7) for ages 5–17, 25·6 (21·3, 29·8) for ages 18–49, 65·5 (54·0, 76·9) for ages 50–64, 125 (105, 147) for ages 65–74, and 288 (244, 331) for ages ≥75. Additionally, influenza had a significant contribution to hospitalization rates with a principal diagnosis of septicemia for ages 5–17 [0·76 (0·1, 1·4)], 18–49 [1·02 (0·3, 1·7)], 50–64 [4·0 (1·7, 6·3)], 65–74 [8·8 (2·2, 15·6)], and ≥75 [38·7 (25·7, 52·9)]. RSV had a significant contribution to the rates of respiratory hospitalizations for age <1 [1900 (1740, 2060)], ages 1–4 [117 (70, 167)], and ≥75 [175 (44, 312)] [including chronic lower respiratory disease, 90 (43, 140)] as well as pneumonia & influenza hospitalizations for ages 18–49 [6·2 (1·1, 11·3)] and circulatory hospitalizations for ages ≥75 [199 (13, 375)].

Conclusions

The high burden of RSV hospitalizations among young children and seniors age ≥75 suggests the need for additional control measures such as vaccination to mitigate the impact of annual RSV epidemics. Our estimates for influenza-associated hospitalizations provide further evidence of the burden of morbidity associated with influenza, supporting current guidelines regarding influenza vaccination and antiviral treatment.     

Structures of sequential open states in a symmetrical opening transition of the TolC exit duct

In bacterial drug resistance and virulence pumps, an inner membrane (IM) transporter and periplasmic adaptor recruit an outer membrane (OM) trimeric TolC exit duct that projects an α-helical tunnel across the periplasm. The TolC periplasmic entrance is closed by densely packed α-helical coiled coils, inner H7/H8, and outer H3/H4, constrained by a hydrogen bond network. On recruitment, these coiled coils must undergo transition to the open state. We present 2.9 Å resolution crystal structures of two sequential TolC open states in which the network is incrementally disrupted and channel conductances defined in lipid bilayers. Superimposition of TolC^RS (370 pS) and TolC^YFRS (1,000 pS) on the TolC^WT closed state (80 pS) showed that in the initial open-state TolC^RS, relaxation already causes approximately 14° twisting and expansion of helix H7 at the periplasmic tip, increasing interprotomer distances from 12.2 Å in TolC^WT to 18.9 Å. However, in the crystal structure, the weakened Asp³⁷⁴ pore constriction was maintained at the closed state 11.3 Ų. In the advanced open-state TolC^YFRS, there was little further expansion at the tip, to interprotomer 21.3 Å, but substantial movement of inner and outer coiled coils dilated the pore constriction. In particular, upon abolition of the TolC^YFRS intraprotomer Tyr³⁶²–Asp¹⁵³ link, a redirection of Tyr³⁶² and “bulge” in H3 allowed a simple movement outward of H8, establishing a 50.3 Ų opening. Root mean square deviations (rmsds) over the coiled coils of the three protomers of TolC^RS and TolC^YFRS illustrate that, whereas independent movement at the periplasmic tips may feature in the initial stages of opening, full dilation of the pore constriction is entirely symmetrical.     

Differential contribution of HLA-DR,DQ, and TAP2 alleles to systemic lupus erythematosus susceptibility in Spanish patients: role of TAP2*01 alleles in Ro autoantibody production

OBJECTIVE—To study the influence MHC class II and TAP2 alleles exert on systemic lupus erythematosus (SLE) susceptibility and on the clinical and serological manifestations of the disease, in a cohort of Spanish patients.
METHODS—HLA-DR serological typing and HLA-DQA, DQB, and TAP2 DNA sequence specific oligotyping, were carried out in 85 unrelated Spanish SLE patients and 186 healthy controls. Autoantibodies detection was carried out by indirect immunofluorescence and counter immunoelectrophoresis.
RESULTS—Total SLE group: the frequency of HLA-DR3 and HLA-DQA1*0501 is significantly increased in this group (p_c<0.005, δ=0.34 and p_c<0.005, δ= 0.45, respectively) although the highest δ value (δ=0.87) is obtained when the TAP2*01 alleles are considered. No DQB allele shows significant deviation from the control group. Renal damage: it mainly occurs in HLA-DR3 patients (p_c<0.0005 and δ=0.72). HLA-DQA1*0501 (p_c<0.05, δ=0.57) and DQB1*0201 (p_c NS, δ=0.56) are weaker susceptibility factors. Ro+ (but not La) group: this autoantibody response is associated with TAP2*01 alleles in homozygosity (p<0.05, δ=0.81). Ro/La+ group: it has a different genetic background as HLA-DQA1*0501 (δ=1) and HLA-DQB1*0201 (δ=1) are the main susceptibility factors.
CONCLUSIONS—A differential association between HLA-DR, DQA1, and DQB1 alleles and SLE or its clinical and serological manifestations are found. Furthermore, the associations are different to the ones reported in other ethnic groups. Finally, TAP2*01 group of alleles are associated with the highest susceptibility to SLE (higher than HLA-DR3) and may influence Ro (but not La) autoantibodies production, whereas HLA-DQA1*0501 and DQB1*0201 mediates concomitant Ro and La production.