Obesity is a cardinal risk factor for the development of atherosclerotic cardiovascular disease. Bariatric surgery is an effective method of achieving weight reduction and improving control of cardiovascular risk factors in patients with obesity. However, the effect of bariatric surgery on long-term cardiovascular outcomes has yet to be defined. The aim of this study is to evaluate the effect of bariatric surgery on long-term risk of major adverse cardiovascular events in a large population of patients with obesity. A nested cohort study was carried out; including the 3,701 patients of the Clinical Practice Research Datalink database who had undergone bariatric surgery, and 3,701 age, gender and BMI matched controls. The primary endpoint was the composite of fatal or non-fatal myocardial infarction; and fatal or non-fatal acute ischaemic stroke. Secondary endpoints included all-cause mortality, new diagnosis of heart failure, fatal or non-fatal myocardial infarction, and fatal or non-fatal acute ischaemic stroke. Data was analysed using a Cox proportional hazards model to account for multiple covariates. Patients were followed up for a median of 11.2 years; 20.3% of the population were female, the median age was 36 years and median BMI was 40.4 kg/m2. Patients who had undergone bariatric surgery had a significantly lower occurrence of the primary composite outcome (HR 0.450; 95% CI 0.312–0.671, p<0.001, NNT=62); this was driven by a reduction in myocardial infarction (HR 0.444; 95% CI 0.302–0.654, p<0.001, NNT=64) and not in acute ischaemic stroke (HR 0.528; 95% CI 0.159–1.751, p=0.296). A significant reduction was observed in rates all-cause mortality (HR 0.254; 95% CI 0.183–0.353; p<0.001, NNT=27) and of new diagnosis of heart failure (HR 0.519; 95% CI 0.311–0.864, p=0.012, NNT=153). Table 1. Primary and secondary endpoints during follow-up Events No Bariatric Surgery Bariatric Surgery HR 95% CI p (n=3,701) (n=3,701) Primary endpoint 93 37 0.458 0.312–0.671 <0.001 Secondary endpoints   All-cause mortality 182 45 0.254 0.183–0.353 <0.001   Heart failure 46 22 0.519 0.311–0.864 0.012   Fatal or non-fatal myocardial infarction 93 36 0.444 0.302–0.654 <0.001   Fatal or non-fatal ischaemic stroke 9 4 0.528 0.159–1.751 0.296 Adjusted primary endpoint rates The results of this large, nation-wide nested cohort study support the role of bariatric surgery in reducing the risk of major cardiovascular events, all-cause mortality and new onset of heart failure in patients with obesity.

14 Atmospheric deposition of nitrogen (N) compounds is the major source of anthropogenic N to most 15 upland ecosystems, where leaching of nitrate (NO3) into surface waters contributes to eutrophication 16 and acidification as well as indicating an excess of N in the terrestrial catchment ecosystems. Natural 17 abundance stable isotopes ratios, N/N and O/O, (the “dual isotope” technique) have previously 18 been used in biogeochemical studies of alpine and forested ecosystems to demonstrate that most of the 19 NO3 in upland surface waters has been microbially produced. Here we present an application of the 20 technique to four moorland catchments in the British uplands including a comparison of lakes and their 21 stream inflows at two sites. The NO3 concentrations of bulk deposition and surface waters at three sites 22 are very similar. While noting the constraints imposed by uncertainty in the precise δO value for 23 microbial NO3, however, we estimate that 79-98% of the annual mean NO3 has been microbially 24 produced. Direct leaching of atmospheric NO3 is a minor component of catchment NO3 export, 25 although greater than in many similar studies in forested watersheds. A greater proportion of 26 atmospheric NO3 is seen in the two lake sites relative to their inflow streams, demonstrating the 27 importance of direct NO3 deposition to lake surfaces in catchments where terrestrial ecosystems 28

Background Increasing evidence suggests that patterns of T-cell immunity to inhalant allergens in genetically diverse human populations are more heterogeneous than previously assumed, and that covert differences in expression patterns might underlie variations in airway disease phenotypes. We tested this proposition in a community sample of childrenMethods We analysed data from 172 individuals who had been recruited antenatally to a longitudinal birth cohort study. Of the 194 birth cohort participants, data from the 147 probands (age range 8.6-13.5 years) who consented to blood collection were included along with data from 25 consenting siblings (mean age 11 years [range 7.4-17.4]). We ascertained clinical phenotypes related to asthma and allergy. We measured T-cell responses to allergens and mitogens, together with blood eosinophils and IgE/IgG antibodies, and assessed associations between these indices and clinical phenotypes.Findings Atopy was associated with allergen-specific T-helper (Th)2 responses dominated by interleukin 4, interleukin 5, interleukin 9, interleukin 13, whereas interleukin 10, tumour necrosis factor a, and interferon gamma responses were common to both atopics and non-atopics. The wheal size from skin prick with allergen was positively associated with in-vitro interleukin 5 and interferon gamma responses, and negatively associated with interleukin 10. Asthma, especially in atopics, was strongly associated with eosinophilia/interleukin 5, and bronchial hyperresponsiveness (BHR) was associated with eosinophilia plus polyclonal interferon gamma production. BHR in non-atopics was associated with elevated allergen-specific and polyclonal interleukin 10 production.Interpretation Parallel immunological and clinical profiling of children identified distinctive immune response patterns related to asthma and wheeze compared with BHR, in atopics non-atopics. Immunological hyperresponsiveness, including within the Th1 cytokine compartment, is identified as a hallmark of BHR.Relevance to practice These findings highlight the heterogeneity of immune response patterns in asthmatic children, including those with seemingly homogeneous Th2-driven atopic asthma. Further elucidation of the covert relationships between wheezing phenotypes and underlying immunophenotypes in this age group will potentially lead to more effective treatments for what is an unexpectedly heterogeneous collection of disease subtypes.

Background: High genetic risk (HR) of atopy among unstratified populations of infants is associated with attenuated IFN-gamma responses. However, the role of IFN-gamma in progression from HR status to active disease is less clear.Objective: To identify immune function markers in neonates with HR that are associated with positive atopic outcomes at 2 years.Methods: Cord blood mononuclear cells (CBMCs) were collected from 175 children with HR and cryopreserved. The children were assessed for atopy by skin prick at 0.5 and 2 years. CBMCs were thawed and stimulated with allergens and mitogens PHA and staphylococcal enterotoxin B (SEB), and cytokine responses were determined.Results: No correlations were observed between allergen specific CBMC responses and atopic outcomes. In contrast, sensitization was strongly associated with polyclonal IFN-gamma responses to both PHA (P=.002) and SEB (P =.005), and also with SEB-induced IL-5 (P=.05), IL-10 (P =.02), and IL-13 (P =.01). Logistic regression analysis identified elevated PHA-induced IFN-gamma and SEB-induced IL-13 responses as the strongest independent predictors of atopy development. Cell separation studies confirmed CD8(+) T cells as the source of similar to90 % of IFN-gamma production.Conclusions: IFN-gamma produced by CD8(+) T cells may synergize with T(H)2 cytokines in driving atopy development in children with HR.

Background: Staphylococcus aureus colonization has been found in 80–100% of lesional skin from patients with atopic eczema dermatitis syndrome (AEDS) and is thought to have a role in the pathogenesis of the disease. Furthermore, up to 65% of S. aureus from lesional skin has been shown to produce toxigenic superantigens. Methods: Using a cohort of 11 children under 2 years of age diagnosed with AEDS, we isolated peripheral blood mononuclear cells, cultured them with staphylococcal enterotoxin B (SEB) and phytohaemagglutinin, and assessed the cytokine response profiles. Plasma was also collected for immunoglobulin E analysis. In addition, skin and nasal swabs were taken and cultured to determine the presence of SEB-producing S. aureus by polymerase chain reaction (PCR) and reverse passive latex agglutination. Results: We found a significant increase in the production of the SEB-induced cytokines interleukin (IL)-5 and IL-13 in the patient group when compared with non-atopic, healthy controls. For IL-13, there was almost no overlap in the levels between the groups. However, there was no correlation between SEB-induced IL-13 and disease severity. This difference was not seen when heat-inactivated S. aureus was used to stimulate the cells. Conclusions: IL-13 is an important factor in AEDS development in early childhood, and prophylactic anti-staphylococcal treatment may provide protection from AEDS in atopic individuals.

Background: The incidence of Staphylococcus aureus (S. aureus ) colonization on the skin of patients with atopic eczema/dermatitis syndrome (AEDS) is approximately 90% and a variety of evidence implicates epidermal staphylococcal infection as a pathogenic factor in atopic dermatitis. However, the mechanism(s) underlying the effects of this organism in the disease process are unclear. The cellular responses of AEDS suffers and asymptomatic atopic individuals to bacterial superantigens (SAg) were investigated in an attempt to elucidate the role of staphylococcal enterotoxin B (SEB) in atopic disease.Methods: Peripheral blood mononuclear cells (PBMC) were isolated from normal nonatopic adults, asymptomatic atopic individuals, patients with active AEDS and patients with active allergic asthma. The cells were cultured for 24 or 96 h with house dust mite (HDM), SEB and phytohaemagluttinin (PHA), and the supernatants were assayed for cytokine levels.Results: Staphylococcal enterotoxin B selectively stimulates the production of interleukin (IL)-5 in AEDS sufferers but not in asymptomatic atopics or nonatopics. Additionally, we observed comparable susceptibility to the IL-5-stimulatory effects of SEB in allergic asthmatics.Conclusions: Given the central role of IL-5-driven eosinophilia in progression from mild atopy to severe disease, these findings provide a plausible mechanism for the AEDS-promoting effects of staphylococcal SAg. Staphylococcal enterotoxin B may also have a similar role in atopic respiratory disease.

ABSTRACT Increasing evidence indicates that the capacity to induce protective Th1 immune responses is impaired in early childhood, an observation that can be partially attributed to deficiencies in antigen-presenting-cell function. Synthesis of interleukin 12 (IL-12), a key Th1-trophic cytokine, is markedly reduced in the neonatal period, though there is a paucity of knowledge concerning the ontogeny of IL-12-synthetic capacity throughout the childhood years. Hence, we examined the production of bioactive IL-12 p70 by circulating mononuclear cells in a population of healthy individuals. As expected, the capacity to synthesize IL-12 p70 in response to either lipopolysaccharide or heat-killed Staphylococcus aureus was markedly impaired at birth, even after priming of cells with gamma interferon. Surprisingly however, IL-12 p70 synthesis by peripheral blood mononuclear cells from both 5- and 12-year-old children was still substantially below that seen in adults, and this did not appear to be related to excessive production of IL-10. In contrast, dendritic cells from adults and neonates, derived from monocytes with granulocyte-macrophage colony-stimulating factor and IL-4, synthesized equivalent amounts of IL-12 p70 in response to microbial stimulation. This indicates that the impaired capacity for IL-12 synthesis in childhood is not an intrinsic property of circulating mononuclear cells but rather can be readily overcome in response to appropriate maturational stimuli. Because IL-12 arose predominantly from circulating HLA-DR+ cells that lacked B-cell- and monocyte-specific markers, we propose that the slow maturation of IL-12-synthetic capacity in the childhood years can be attributed to deficiencies in the number and/or function of dendritic cells.

DAP.3 transfectants expressing native H-2E molecules with or without human LFA-3 and ICAM-1 (intercellular adhesion molecule-1) failed to induce proliferation by human peripheral blood T cells. Introduction of sequence from the DR beta 2 domain into the H-2E molecule led to the induction of detectable proliferation, which was substantially augmented by co-expression of human LFA-3 and ICAM-1 to levels comparable to those induced by DAP.3 cells co-expressing wild-type DR alloantigens with human LFA-3/ICAM-1. In marked contrast, cells expressing native H-2A molecules together with human accessory molecules provoked strong primary proliferative responses. The results of Ab inhibition experiments confirmed that this was caused by direct xenorecognition. In limiting dilution assays the frequency of anti-H-2A, IL-2-secreting, CD4+ human T cells was only fivefold lower than that measured against a DR alloantigen expressed on the same background. No measurable frequency was recorded against H-2E-expressing cells. Evidence to suggest that this difference was a result of isotype-specific differences in the interaction with CD4 was provided using transfectants expressing DR alloantigens with either the H-2E or H-2A beta 2 domain. DR molecules with the H-2A beta 2 domain stimulated a substantially stronger response than those with the H-2E beta 2 domain. These results challenge the view that xenogeneic T cell responses between evolutionarily distant species are weak; further emphasize the influence of the interaction between the T cell co-receptor molecule CD4, with its MHC class II molecular ligand on the strength of primary xenoresponses; and suggest that MHC class II isotypes may differ substantially in their interaction with CD4.

One explanation offered for the uniquely high precursor frequencies of T cells which recognize allogeneic major histocompatibility complex (MHC) molecules, and their lack of self-MHC restriction, is that the alloreactive cells are polyclonal populations the primary specificity of which is self-MHC plus peptide X1, X2, ... Xn. These are postulated to cross-react with allo-MHC plus peptides Y1, Y2, ... Yn. It has been further suggested that the structural basis for the crossreactivity between different MHC alleles is the similarity in amino acid sequence of that part of the molecule predicted to make contact with the T cell receptor (TcR). In order to test this concept, T cells were obtained with dual specificity for influenza haemagglutinin (HA), restricted by HLA-DR1Dw1, and for DR4Dw4/Dw14 expressed on allogeneic human B cell lines, and the specificity of one clone was studied in detail. The exposed, TcR-contacting surfaces of these two DR molecules are predicted to be identical. Although the HA-specific response was stimulated by DR1-expressing mouse DAP.3 transfectants, DAP.3 cells expressing the alloantigen DR4Dw4 were unable to stimulate, possibly because of a failure to present the necessary human peptide for anti-DR4 allorecognition. Therefore, the effects of pulsing the DR4Dw4-expressing DAP.3 cells with the HA peptide were examined. This peptide is known to bind to both DR1 and DR4. Addition of the HA peptide restored the anti-DR4Dw4 response. These data support the concept that allorecognition in some responder/stimulator combinations can be explained by cross-reactivity at the level of the MHC molecule and the peptide.

Structural and functional aspects of the accessory molecule lymphocyte function associated antigen (LFA)-3 (CD58) have been examined following the transfection of DAP.3 and P815 cells with a cDNA clone encoding the glycosyl phosphatidylinositol (GPI)-linked form of human LFA-3. Despite earlier observations that DAP.3 cells are deficient in GPI anchoring LFA-3 was expressed efficiently on DAP.3, as well as on P815 cells. Immunoprecipitation of LFA-3 from 35S-labelled cells revealed that the molecule expressed on the DAP.3 cells had a molecular weight intermediate between the transmembrane and GPI-linked forms expressed by human B cells. This suggests that the DAP.3 cells have a default pathway whereby the RNA transcript which encodes the GPI-linked form of the molecule can also encode an integral membrane protein. Functionally, expression of LFA-3 by DAP.3 which had previously been transfected with the genes encoding HLA-DR1 led to a marked augmentation of the proliferative response of five out of eight anti-DR1 human T cell clones. This effect was not reproduced when DR1 and LFA-3 were expressed by separate populations of DAP.3 cells, suggesting that the ligands for CD2 and for the T cell's receptor must be expressed on the same cell membrane. Expression of human LFA-3 also led to a substantial increase in the proliferative response of human peripheral blood T cells to a DR alloantigen. Separation of T cells into CD45RO+ and CD45RO- populations revealed that the augmentation was more marked for the memory than the virgin population. The mechanisms responsible for these differences are discussed.

A segmental analysis of the key regions of HLA-DR1 that control T cell allorecognition was performed by using a series of transfected cell lines expressing the products of recombinant DRB/H-2Eb genes, paired with either DR alpha or H-2E alpha. Four of eight human T cell clones tolerated substitution of the H-2E alpha chain, but only one clone showed any response to the DR alpha/H-2E beta k dimer. Both the membrane-proximal and the membrane-distal domains of the beta-chain played an important part in stimulating these clones. The response of four of eight clones was markedly inhibited by substitution of the H-2E beta 2 for the DR beta 2 domain. This inhibition showed a complete correlation with the sensitivity of the clones to inhibition by anti-CD4 mAb. Taken together, these results suggest that the interaction site for CD4 may include residues on the beta 2-domain. Introduction of H-2Ek sequence into either half of the beta 1-domain led to a complete loss of response by all but two of the clones. This is consistent with these clones having dual specificity for exposed DR1-specific polymorphisms and for DR1-bound peptides. The pattern of response of one of the clones suggested that indirect conformational effects on the alpha 1-domain may also contribute to the influence of the amino-terminal half of the beta 1-domain on T cell recognition. In the presence of H-2E alpha, this clone responded more strongly when the amino-terminal half of the beta 1-domain was of H-2Ek rather than DR1 sequence. This implies that species matching of the floor of the beta 1-domain with the alpha-chain is more important than the presence of the alpha-chain of the parental species.