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Human immune system mice are highly valuable for in vivo dissection of human immune responses. Although they were employed for analyzing tuberculosis (TB) disease, there is little data on the spatial organization and cellular composition of human immune cells in TB granuloma pathology in this model. We demonstrate that human immune system mice, generated by transplanted human fetal liver derived hematopoietic stem cells develop a continuum of pulmonary lesions upon Mycobacterium tuberculosis aerosol infection. In particular, caseous necrotic granulomas, which contribute to prolonged TB treatment time, developed, and had cellular phenotypic spatial-organization similar to TB patients. By comparing two recommended drug regimens, we confirmed observations made in clinical settings: Adding Moxifloxacin to a classical chemotherapy regimen had no beneficial effects on bacterial eradication. We consider this model instrumental for deeper understanding of human specific features of TB pathogenesis and of particular value for the pre-clinical drug development pipeline.

The relative effectiveness of 3 approaches to blood pressure control-(i) an intensive lifestyle intervention (ILI) focused on weight loss, (ii) frequent goal-based monitoring of blood pressure with pharmacological management, and (iii) education and support-has not been established among overweight and obese adults with type 2 diabetes who are appropriate for each intervention.Participants from the Action for Health in Diabetes (Look AHEAD) and the Action to Control Cardiovascular Risk in Diabetes (ACCORD) cohorts who met criteria for both clinical trials were identified. The proportions of these individuals with systolic blood pressure (SBP)140 mm Hg from annual standardized assessments over time were compared with generalized estimating equations.Across 4 years among 480 Look AHEAD and 1,129 ACCORD participants with baseline SBPs between 130 and 159 mm Hg, ILI (OR = 1.46; 95% CI = [1.18-1.81]) and frequent goal-based monitoring with pharmacotherapy (OR = 1.51; 95% CI = [1.16-1.97]) yielded higher rates of blood pressure control compared to education and support. The intensive behavioral-based intervention may have been more effective among individuals with body mass index30 kg/m2, while frequent goal-based monitoring with medication management may be more effective among individuals with lower body mass index (interaction P = 0.047).Among overweight and obese adults with type 2 diabetes, both ILI and frequent goal-based monitoring with pharmacological management can be successful strategies for blood pressure control.clinicaltrials.gov identifiers NCT00017953 (Look AHEAD) and NCT00000620 (ACCORD).

Successful host defense against numerous pulmonary infections depends on bacterial clearance by polymorphonuclear leukocytes (PMNs); however, excessive PMN accumulation can result in life-threatening lung injury. Local expression of CXC chemokines is critical for PMN recruitment. The impact of chemokine-dependent PMN recruitment during pulmonary Mycobacterium tuberculosis infection is not fully understood. Here, we analyzed expression of genes encoding CXC chemokines in M. tuberculosis-infected murine lung tissue and found that M. tuberculosis infection promotes upregulation of Cxcr2 and its ligand Cxcl5. To determine the contribution of CXCL5 in pulmonary PMN recruitment, we generated Cxcl5(-/-) mice and analyzed their immune response against M. tuberculosis. Both Cxcr2(-/-) mice and Cxcl5(-/-) mice, which are deficient for only one of numerous CXCR2 ligands, exhibited enhanced survival compared with that of WT mice following high-dose M. tuberculosis infection. The resistance of Cxcl5(-/-) mice to M. tuberculosis infection was not due to heightened M. tuberculosis clearance but was the result of impaired PMN recruitment, which reduced pulmonary inflammation. Lung epithelial cells were the main source of CXCL5 upon M. tuberculosis infection, and secretion of CXCL5 was reduced by blocking TLR2 signaling. Together, our data indicate that TLR2-induced epithelial-derived CXCL5 is critical for PMN-driven destructive inflammation in pulmonary tuberculosis.

Udgivelsesdato: 2009-Oct-22 Influenza A virus is an important human pathogen causing significant morbidity and mortality every year and threatening the human population with epidemics and pandemics. Therefore, it is important to understand the biology of this virus to develop strategies to control its pathogenicity. Here, we demonstrate that influenza A virus inhibits macroautophagy, a cellular process known to be manipulated by diverse pathogens. Influenza A virus infection causes accumulation of autophagosomes by blocking their fusion with lysosomes, and one viral protein, matrix protein 2, is necessary and sufficient for this inhibition of autophagosome degradation. Macroautophagy inhibition by matrix protein 2 compromises survival of influenza virus-infected cells but does not influence viral replication. We propose that influenza A virus, which also encodes proapoptotic proteins, is able to determine the death of its host cell by inducing apoptosis and also by blocking macroautophagy.

Epstein Barr virus (EBV) causes lymphomas in immune competent and, at increased frequencies, in immune compromised patients. In the presence of an intact immune system, EBV-associated lymphomas express in most cases only 3 or fewer EBV antigens at the protein level, always including the nuclear antigen 1 of EBV (EBNA1). EBNA1 is a prominent target for EBV-specific CD4(+) T cell and humoral immune responses in healthy EBV carriers. Here we demonstrate that patients with EBV-associated lymphomas, primarily Hodgkin's lymphoma, lack detectable EBNA1-specific CD4(+) T-cell responses and have slightly altered EBNA1-specific antibody titers at diagnosis. In contrast, the majority of EBV-negative lymphoma patients had detectable IFN-gamma expression and proliferation by CD4(+) T cells in response to EBNA1, and carry EBNA1-specific immunoglobulins at levels similar to healthy virus carriers. Other EBV antigens, which were not present in the tumors, were recognized in less EBV positive, than negative lymphoma patients, but detectable responses reached similar CD8(+) T cell frequencies in both cohorts. Patients with EBV-positive and -negative lymphomas did not differ in T-cell responses in influenza-specific CD4(+) T cell proliferation and in antibody titers against tetanus toxoid. These data suggest a selective loss of EBNA1-specific immune control in EBV-associated lymphoma patients, which should be targeted for immunotherapy of these malignancies.

BACKGROUND Epidemiologic studies have shown a relationship between glycated hemoglobin levels and cardiovascular events in patients with type 2 diabetes. We investigated whether intensive therapy to target normal glycated hemoglobin levels would reduce cardiovascular events in patients with type 2 diabetes who had either established cardiovascular disease or additional cardiovascular risk factors. METHODS In this randomized study, 10,251 patients (mean age, 62.2 years) with a median glycated hemoglobin level of 8.1% were assigned to receive intensive therapy (targeting a glycated hemoglobin level below 6.0%) or standard therapy (targeting a level from 7.0 to 7.9%). Of these patients, 38% were women, and 35% had had a previous cardiovascular event. The primary outcome was a composite of nonfatal myocardial infarction, nonfatal stroke, or death from cardiovascular causes. The finding of higher mortality in the intensive-therapy group led to a discontinuation of intensive therapy after a mean of 3.5 years of follow-up. RESULTS At 1 year, stable median glycated hemoglobin levels of 6.4% and 7.5% were achieved in the intensive-therapy group and the standard-therapy group, respectively. During follow-up, the primary outcome occurred in 352 patients in the intensive-therapy group, as compared with 371 in the standard-therapy group (hazard ratio, 0.90; 95% confidence interval [CI], 0.78 to 1.04; P=0.16). At the same time, 257 patients in the intensive-therapy group died, as compared with 203 patients in the standard-therapy group (hazard ratio, 1.22; 95% CI, 1.01 to 1.46; P=0.04). Hypoglycemia requiring assistance and weight gain of more than 10 kg were more frequent in the intensive-therapy group (P

DCs activate NK cells during innate immune responses to viral infections. However, the composition and kinetics of the immunological synapse mediating this interaction are largely unknown. Here, we report the rapid formation of an immunological synapse between human resting NK cells and mature DCs. Although inhibitory NK cell receptors were polarized to this synapse, where they are known to protect mature DCs from NK cell lysis, the NK cell also received activation signals that induced mobilization of intracellular calcium and CD69 upregulation. The high-affinity component of the receptor for IL-15, IL-15Ralpha, accumulated at the synapse center on NK cells, and blocking of IL-15Ralpha increased NK cell apoptosis and diminished NK cell survival during their interaction with DCs. Furthermore, IL-15Ralpha-deficient NK cells, obtained from donors with a history of infectious mononucleosis, showed diminished survival in culture with DCs. Synapse formation was required for IL-15Ralpha-mediated NK cell survival, because synapse disruption by adhesion molecule blocking decreased DC-induced NK cell survival. These results identify what we believe to be a novel regulatory NK cell synapse with hallmarks of spatially separated inhibitory and activating interactions at its center. We suggest that this synapse formation enables optimal NK cell activation by DCs during innate immune responses.

To investigate human natural killer (NK)–cell reactivity in vivo we have reconstituted human immune system components by transplantation of human hematopoietic progenitor cells into NOD-scid IL2Rγnull mice. We demonstrate here that this model allows the development of all NK-cell subsets that are also found in human adult peripheral and cord blood, including NKp46+CD56− NK cells. Similar to human cord blood, NK cells from these reconstituted mice require preactivation by interleukin-15 to reach the functional competence of human adult NK cells. Mainly the terminally differentiated CD16+ NK cells demonstrate lower reactivity without this stimulation. After preactivation, both CD16+ and CD16− NK cells efficiently produce interferon-γ and degranulate in response to stimulation with NK cell–susceptible targets, including K562 erythroleukemia cells. NK-cell lines, established from reconstituted mice, demonstrate cytotoxicity against this tumor cell line. Importantly, preactivation can as well be achieved by bystander cell maturation via poly I:C stimulation in vitro and injection of this maturation stimulus in vivo. Preactivation in vivo enhances killing of human leukocyte antigen class I negative tumor cells after their adoptive transfer. These data suggest that a functional, but resting, NK-cell compartment can be established in immune-compromised mice after human hematopoietic progenitor cell transfer.

Many pathogens that cause human disease infect only humans. To identify the mechanisms of immune protection against these pathogens and also to evaluate promising vaccine candidates, a small animal model would be desirable. We demonstrate that primary T cell responses in mice with reconstituted human immune system components control infection with the oncogenic and persistent Epstein-Barr virus (EBV). These cytotoxic and interferon-γ–producing T cell responses were human leukocyte antigen (HLA) restricted and specific for EBV-derived peptides. In HLA-A2 transgenic animals and similar to human EBV carriers, T cell responses against lytic EBV antigens dominated over recognition of latent EBV antigens. T cell depletion resulted in elevated viral loads and emergence of EBV-associated lymphoproliferative disease. Both loss of CD4+ and CD8+ T cells abolished immune control. Therefore, this mouse model recapitulates features of symptomatic primary EBV infection and generates T cell–mediated immune control that resists oncogenic transformation.

Cells of the innate immune system act in synergy to provide a first line of defense against pathogens. Here we describe that dendritic cells (DCs), matured with viral products or mimics thereof, including Epstein-Barr virus (EBV), activated natural killer (NK) cells more efficiently than other mature DC preparations. CD56brightCD16− NK cells, which are enriched in human secondary lymphoid tissues, responded primarily to this DC activation. DCs elicited 50-fold stronger interferon-γ (IFN-γ) secretion from tonsilar NK cells than from peripheral blood NK cells, reaching levels that inhibited B cell transformation by EBV. In fact, 100- to 1,000-fold less tonsilar than peripheral blood NK cells were required to achieve the same protection in vitro, indicating that innate immune control of EBV by NK cells is most efficient at this primary site of EBV infection. The high IFN-γ concentrations, produced by tonsilar NK cells, delayed latent EBV antigen expression, resulting in decreased B cell proliferation during the first week after EBV infection in vitro. These results suggest that NK cell activation by DCs can limit primary EBV infection in tonsils until adaptive immunity establishes immune control of this persistent and oncogenic human pathogen., Author Summary Epstein-Barr virus (EBV) establishes a persistent infection in nearly all human adults. Due to its tumor causing potential EBV infection has to be continuously controlled by the immune system in virus carriers. We demonstrate here that in the first week after infection, when other EBV-specific immune responses are still being recruited, human natural killer (NK) cells are able to prevent transformation of the main host cell type by EBV, the human B cell. Especially NK cells of tonsils, the primary site of EBV infection, inhibit B cell transformation by EBV after they have been activated by dendritic cells (DCs). For this protective function, EBV can directly stimulate DCs to efficiently activate NK cells. Interestingly, NK cells primarily prevent B cell transformation by EBV via secretion of the anti-viral cytokine IFN-γ, and NK cells from tonsils and lymph nodes produce 5-fold more of this cytokine than their peripheral blood counterparts. These data suggest that specialized NK cells in tonsils, the mucosal entry site of EBV, can be efficiently stimulated by EBV-activated DCs, and then limit EBV-induced B cell transformation until EBV-specific immune control by other components of the immune system is established.