Gadd45α activity is the principal effector of Shigella mitochondria-dependent epithelial cell death in vitro and ex vivo

Modulation of death is a pathogen strategy to establish residence and promote survival in host cells and tissues. Shigella spp. are human pathogens that invade colonic mucosa, where they provoke lesions caused by their ability to manipulate the host cell responses. Shigella spp. induce various types of cell death in different cell populations. However, they are equally able to protect host cells from death. Here, we have investigated on the molecular mechanisms and cell effectors governing the balance between survival and death in epithelial cells infected with Shigella. To explore these aspects, we have exploited both, the HeLa cell invasion assay and a novel ex vivo human colon organ culture model of infection that mimics natural conditions of shigellosis. Our results definitely show that Shigella induces a rapid intrinsic apoptosis of infected cells, via mitochondrial depolarization and the ensuing caspase-9 activation. Moreover, for the first time we identify the eukaryotic stress-response factor growth arrest and DNA damage 45α as a key player in the induction of the apoptotic process elicited by Shigella in epithelial cells, revealing an unexplored role of this molecule in the course of infections sustained by invasive pathogens

Seropositivity and Risk Factors Associated with Toxoplasma gondii Infection in Wild Birds from Spain

Toxoplasma gondii is a zoonotic intracellular protozoan parasite of worldwide distribution that infects many species of warm-blooded animals, including birds. To date, there is scant information about the seropositivity of T. gondii and the risk factors associated with T. gondii infection in wild bird populations. In the present study, T. gondii infection was evaluated on sera obtained from 1079 wild birds belonging to 56 species (including Falconiformes (n = 610), Strigiformes (n = 260), Ciconiiformes (n = 156), Gruiformes (n = 21), and other orders (n = 32), from different areas of Spain. Antibodies to T. gondii (modified agglutination test, MAT titer ≥1∶25) were found in 282 (26.1%, IC95%:23.5–28.7) of the 1079 birds. This study constitute the first extensive survey in wild birds species in Spain and reports for the first time T. gondii antibodies in the griffon vulture (Gyps fulvus), short-toed snake-eagle (Circaetus gallicus), Bonelli's eagle (Aquila fasciata), golden eagle (Aquila chrysaetos), bearded vulture (Gypaetus barbatus), osprey (Pandion haliaetus), Montagu's harrier (Circus pygargus), Western marsh-harrier (Circus aeruginosus), peregrine falcon (Falco peregrinus), long-eared owl (Asio otus), common scops owl (Otus scops), Eurasian spoonbill (Platalea leucorodia), white stork (Ciconia ciconia), grey heron (Ardea cinerea), common moorhen (Gallinula chloropus); in the International Union for Conservation of Nature (IUCN) “vulnerable” Spanish imperial eagle (Aquila adalberti), lesser kestrel (Falco naumanni) and great bustard (Otis tarda); and in the IUCN “near threatened” red kite (Milvus milvus). The highest seropositivity by species was observed in the Eurasian eagle owl (Bubo bubo) (68.1%, 98 of 144). The main risk factors associated with T. gondii seropositivity in wild birds were age and diet, with the highest exposure in older animals and in carnivorous wild birds. The results showed that T. gondii infection is widespread and can be at a high level in many wild birds in Spain, most likely related to their feeding behaviour

Global patient outcomes after elective surgery: prospective cohort study in 27 low-, middle- and high-income countries.

BACKGROUND: As global initiatives increase patient access to surgical treatments, there remains a need to understand the adverse effects of surgery and define appropriate levels of perioperative care. METHODS: We designed a prospective international 7-day cohort study of outcomes following elective adult inpatient surgery in 27 countries. The primary outcome was in-hospital complications. Secondary outcomes were death following a complication (failure to rescue) and death in hospital. Process measures were admission to critical care immediately after surgery or to treat a complication and duration of hospital stay. A single definition of critical care was used for all countries. RESULTS: A total of 474 hospitals in 19 high-, 7 middle- and 1 low-income country were included in the primary analysis. Data included 44 814 patients with a median hospital stay of 4 (range 2-7) days. A total of 7508 patients (16.8%) developed one or more postoperative complication and 207 died (0.5%). The overall mortality among patients who developed complications was 2.8%. Mortality following complications ranged from 2.4% for pulmonary embolism to 43.9% for cardiac arrest. A total of 4360 (9.7%) patients were admitted to a critical care unit as routine immediately after surgery, of whom 2198 (50.4%) developed a complication, with 105 (2.4%) deaths. A total of 1233 patients (16.4%) were admitted to a critical care unit to treat complications, with 119 (9.7%) deaths. Despite lower baseline risk, outcomes were similar in low- and middle-income compared with high-income countries. CONCLUSIONS: Poor patient outcomes are common after inpatient surgery. Global initiatives to increase access to surgical treatments should also address the need for safe perioperative care. STUDY REGISTRATION: ISRCTN5181700

Global gene expression profiling of myeloid immune cell subsets in response to in vitro challenge with porcine circovirus 2b

Compelling evidence suggests that the early interaction between porcine circovirus 2 (PCV-2) and the innate immune system is the key event in the pathogenesis of Post-Weaning Multisystemic Wasting Syndrome (PMWS). Furthermore, PCV2 has been detected in bone-marrow samples, potentially enabling an easy spread and reservoir for the virus. To assess the gene-expression differences induced by an in-vitro PCV2b infection in different three different myeloid innate immune cell subsets generated from the same animal, we used the Agilent Porcine Gene Expression Microarray (V2). Alveolar macrophages (AMØs), monocyte-derived dendritic cells (MoDCs) and bone-marrow cells (BMCs) were generated from each animal, and challenged with a UK-isolate of a PCV2 genotype b-strain at a MOI of 0.5. Remarkably, analysis showed a highly distinct and cell-type dependent response to PCV2b challenge. Overall, MoDCs showed the most marked response to PCV2b challenge in vitro and revealed a key role for TNF in the interaction with PCV2b, whereas only few genes were affected in BMCs and AMØs. These observations were further supported by an enrichment of genes in the downstream NF-κB Signalling pathway as well as an up regulation of genes with pro-apoptotic functions post-challenge. PCV2b challenge increases the expression of a large number of immune-related and pro-apoptotic genes mainly in MoDC, which possibly explain the increased inflammation, granulomatous inflammation and lymphocyte depletion seen in PMWS-affected pigs

Thymocyte depletion affects neurotrophin receptor expression in thymic stromal cells

Thymocytes and thymic stromal cells cross-talk in a bidirectional manner within the thymus, thus contributing to the generation of mature T-cells. The thymic stromal cells in the rat express the high- (TrkA, TrkB) and low-affinity (p75NTR) receptors for neurotrophins. In this study we analysed the regulation of TrkA, TrkB and p75NTR expression in the rat thymus by thymocytes. We induced thymocyte apoptosis by administration of corticoids in rats, and then analysed the expression and distribution of these receptors 1, 4 and 10 days later. Thymocyte death was assessed by the activation of caspase-3 in cells undergoing apoptosis. We observed massive thymocyte apoptosis 1 day after injection and, to a lesser extent, after 4 days, which was parallel with a reduction in the density of thymic epithelial cells normally expressing TrkA and p75NTR. Furthermore, TrkA expression was found in cortical thymic epithelial cells, which normally lack this receptor. The expression of TrkB was restricted to a subset of macrophage-dendritic cells, and remained unchanged with treatment. The normal pattern of neurotrophin receptor expression was almost completely restored by day 10. The results demonstrate that the expression of neurotrophin receptors by thymic epithelial cells, but not by macrophage-dendritic cells, is regulated by thymocytes