IgE-tailpiece associates with α-1-antitrypsin (A1AT) to protect IgE from proteolysis without compromising its ability to interact with FcεRI

Several splice variants of IgE exist in human plasma, including a variant called IgE-tailpiece (IgE-tp) that differs from classical IgE by the replacement of two carboxy-terminal amino acids with eight novel residues that include an ultimate cysteine. To date, the role of the secreted IgE-tp isoform in human immunity is unknown. We show that levels of IgE-tp are raised in helminth-infected donors, and that both the classical form of IgE (IgE-c) and IgE-tp interact with polymers of the serine protease inhibitor alpha-1-antitrypsin (A1AT). The association of IgE-tp with A1AT polymers in plasma protects the antibody from serine protease-mediated degradation, without affecting the functional interaction of IgE-tp with important receptors, including FcεR1. That polymers of A1AT protect IgE from degradation by helminth proteases may explain why these common and normally non-disease causing polymorphic variants of A1AT have been retained by natural selection. The observation that IgE can be complexed with polymeric forms of A1AT may therefore have important consequences for our understanding of the pathophysiology of pulmonary diseases that arise either as a consequence of A1AT-deficiency or through IgE-mediated type 1 hypersensitivity responses

Electrical conduction by interface states in semiconductor heterojunctions

peer reviewedaudience: researcher, professionalElectrical conduction in semiconductor heterojunctions containing defect states in the interface region is studied. As the classical drift-diffusion mechanism cannot in any case explain electrical conduction in semiconductor heterojunctions, tunnelling involving interface states is often considered as a possible conduction path. A theoretical treatment is made where defect states in the interface region with a continuous energy distribution are included. Electrical conduction through this defect band then allows the transit of electrons from the conduction band of one semiconductor to the valence band of the second component. The analysis is initiated by electrical measurements on n-CdS/p-CdTe heterojunctions obtained by chemical vapour deposition of CdS on (111) oriented CdTe single crystals, for which current--voltage and capacitance--frequency results are shown. The theoretical analysis is based on the numerical resolution of Poisson's equation and the continuity equations of electrons, holes and defect states, where a current component corresponding to the defect band conduction is explicitly included. Comparison with the experimental curves shows that this formalism yields an efficient tool to model the conduction process through the interface region. It also allows us to determine critical values of the physical parameters when a particular step in the conduction mechanism becomes dominant

Donor Characteristics of Pancreas Transplantation in Australia and New Zealand: A Cohort Study 1984-2014

Background The aim of this study was to audit the characteristics of pancreas donors over time in Australia and New Zealand. Pancreas transplantation was introduced in Australian and New Zealand in 1984. Methods We analyzed data from the Australia and New Zealand Islet and Pancreas Transplant Registry, 1984 to 2014. We investigated the variation of donor characteristics of sex, age, body mass index, smoking status, blood group, multiple organ donation, cytomegalovirus status, terminal creatinine, hypertension, and cause of death for pancreas transplantation over time. We used χ2 test (Fisher test when necessary) or analysis of variance to test difference for categorical or continuous characteristics, respectively. Results There were 628 pancreas donors from 1984 to 2014. Donor body mass index (from 21.9 to 24.0, P < 0.001) and age (from 23.9 to 28.5, P = 0.02) have both increased while terminal creatinine has decreased (86.3 to 73.3, P = 0.01) from 1995 to 2014. In the meantime, the proportions of donors with hypertension (from 19% to 1%, P < 0.001) and who were smokers (from 54% to 15%, P < 0.001) have decreased. Profile of cause of donor death has also changed over time (P = 0.06) with increase in cerebral hypoxia/ischemia (from 3% to 17%) and reductions in intracranial hemorrhage (27% to 13%). Conclusions Many donor characteristics have changed over time. The most significant changes appear to reflect changes in the general population, rather than changes in donor selection

T cell responses induced by adenoviral vectored vaccines can be adjuvanted by fusion of antigen to the oligomerization domain of C4b-binding protein.

Viral vectored vaccines have been shown to induce both T cell and antibody responses in animals and humans. However, the induction of even higher level T cell responses may be crucial in achieving vaccine efficacy against difficult disease targets, especially in humans. Here we investigate the oligomerization domain of the α-chain of C4b-binding protein (C4 bp) as a candidate T cell "molecular adjuvant" when fused to malaria antigens expressed by human adenovirus serotype 5 (AdHu5) vectored vaccines in BALB/c mice. We demonstrate that i) C-terminal fusion of an oligomerization domain can enhance the quantity of antigen-specific CD4(+) and CD8(+) T cell responses induced in mice after only a single immunization of recombinant AdHu5, and that the T cells maintain similar functional cytokine profiles; ii) an adjuvant effect is observed for AdHu5 vectors expressing either the 42 kDa C-terminal domain of Plasmodium yoelii merozoite surface protein 1 (PyMSP1(42)) or the 83 kDa ectodomain of P. falciparum strain 3D7 apical membrane antigen 1 (PfAMA1), but not a candidate 128kDa P. falciparum MSP1 biallelic fusion antigen; iii) following two homologous immunizations of AdHu5 vaccines, antigen-specific T cell responses are further enhanced, however, in both BALB/c mice and New Zealand White rabbits no enhancement of functional antibody responses is observed; and iv) that the T cell adjuvant activity of C4 bp is not dependent on a functional Fc-receptor γ-chain in the host, but is associated with the oligomerization of small (<80 kDa) antigens expressed by recombinant AdHu5. The oligomerization domain of C4 bp can thus adjuvant T cell responses induced by AdHu5 vectors against selected antigens and its clinical utility as well as mechanism of action warrant further investigation

The Importance of Human FcγRI in Mediating Protection to Malaria

The success of passive immunization suggests that antibody-based therapies will be effective at controlling malaria. We describe the development of fully human antibodies specific for Plasmodium falciparum by antibody repertoire cloning from phage display libraries generated from immune Gambian adults. Although these novel reagents bind with strong affinity to malaria parasites, it remains unclear if in vitro assays are predictive of functional immunity in humans, due to the lack of suitable animal models permissive for P. falciparum. A potentially useful solution described herein allows the antimalarial efficacy of human antibodies to be determined using rodent malaria parasites transgenic for P. falciparum antigens in mice also transgenic for human Fc-receptors. These human IgG1s cured animals of an otherwise lethal malaria infection, and protection was crucially dependent on human FcγRI. This important finding documents the capacity of FcγRI to mediate potent antimalaria immunity and supports the development of FcγRI-directed therapy for human malaria

The effect of spiritual healing on in vitro tumour cell proliferation and viability – an experimental study

Alternative treatments such as spiritual healing and prayer are increasingly popular, especially among patients with life-threatening diseases such as cancer. According to theories of spiritual healing, this intervention is thought to influence living cells and organisms independently of the recipient's conscious awareness of the healer's intention. The aim of this study was to test the hypothesis that spiritual healing will reduce proliferation and viability of two cancer cell lines in vitro. Three controlled experiments were conducted with three different healers and randomised allocation of cells to five different doses of healing or control. Researchers conducting the assays and statistical analyses were blinded to the experimental conditions. Main outcome measures were MTT viability, 3H-thymidine incorporation and counts of an adherent human breast cancer cell line (MCF-7), and a nonadherent mouse B-lymphoid cell line (HB-94). Analyses of variance (ANOVAs) revealed no significant main or dose-related effects of spiritual healing compared to controls for either of the two cell lines or any of the assays (P-values between 0.09 and 0.96). When comparing healing and control across all three experimental days, doses, assays, and cells, 34 (51.6%) of 66 independent comparisons showed differences in the hypothesised direction (P=0.90). The average effect size across cell lines, days, assays, and doses approached zero (Cohen's d=−0.01). The results do not support previous reports of beneficial effects of spiritual healing on malignant cell growth in vitro. Reported beneficial effects of spiritual healing on the well-being of cancer patients seem more likely to be mediated by psychosocial and psychophysiological effects of the healer–patient relationship

Group B Streptococcus suppression of phagocyte functions by protein-mediated engagement of human Siglec-5

Group B Streptococcus (GBS) is a leading cause of invasive bacterial infections in human newborns. A key GBS virulence factor is its capsular polysaccharide (CPS), displaying terminal sialic acid (Sia) residues which block deposition and activation of complement on the bacterial surface. We recently demonstrated that GBS Sia can bind human CD33-related Sia-recognizing immunoglobulin (Ig) superfamily lectins (hCD33rSiglecs), a family of inhibitory receptors expressed on the surface of leukocytes. We report the unexpected discovery that certain GBS strains may bind one such receptor, hSiglec-5, in a Sia-independent manner, via the cell wall–anchored β protein, resulting in recruitment of SHP protein tyrosine phosphatases. Using a panel of WT and mutant GBS strains together with Siglec-expressing cells and soluble Siglec-Fc chimeras, we show that GBS β protein binding to Siglec-5 functions to impair human leukocyte phagocytosis, oxidative burst, and extracellular trap production, promoting bacterial survival. We conclude that protein-mediated functional engagement of an inhibitory host lectin receptor promotes bacterial innate immune evasion

Native-state stability determines the extent of degradation relative to secretion of protein variants from Pichia pastoris.

We have investigated the relationship between the stability and secreted yield of a series of mutational variants of human lysozyme (HuL) in Pichia pastoris. We show that genes directly involved in the unfolded protein response (UPR), ER-associated degradation (ERAD) and ER-phagy are transcriptionally up-regulated more quickly and to higher levels in response to expression of more highly-destabilised HuL variants and those variants are secreted to lower yield. We also show that the less stable variants are retained within the cell and may also be targeted for degradation. To explore the relationship between stability and secretion further, two different single-chain-variable-fragment (scFv) antibodies were also expressed in P. pastoris, but only one of the scFvs gave rise to secreted protein. The non-secreted scFv was detected within the cell and the UPR indicators were pronounced, as they were for the poorly-secreted HuL variants. The non-secreted scFv was modified by changing either the framework regions or the linker to improve the predicted stability of the scFv and secretion was then achieved and the levels of UPR indicators were lowered Our data support the hypothesis that less stable proteins are targeted for degradation over secretion and that this accounts for the decrease in the yields observed. We discuss the secretion of proteins in relation to lysozyme amyloidosis, in particular, and optimised protein secretion, in general

Transcriptomic Analysis of Toxoplasma Development Reveals Many Novel Functions and Structures Specific to Sporozoites and Oocysts

Sexual reproduction of Toxoplasma gondii occurs exclusively within enterocytes of the definitive felid host. The resulting immature oocysts are excreted into the environment during defecation, where in the days following, they undergo a complex developmental process. Within each oocyst, this culminates in the generation of two sporocysts, each containing 4 sporozoites. A single felid host is capable of shedding millions of oocysts, which can survive for years in the environment, are resistant to most methods of microbial inactivation during water-treatment and are capable of producing infection in warm-blooded hosts at doses as low as 1–10 ingested oocysts. Despite its extremely interesting developmental biology and crucial role in initiating an infection, almost nothing is known about the oocyst stage beyond morphological descriptions. Here, we present a complete transcriptomic analysis of the oocyst from beginning to end of its development. In addition, and to identify genes whose expression is unique to this developmental form, we compared the transcriptomes of developing oocysts with those of in vitro-derived tachyzoites and in vivo-derived bradyzoites. Our results reveal many genes whose expression is specifically up- or down-regulated in different developmental stages, including many genes that are likely critical to oocyst development, wall formation, resistance to environmental destruction and sporozoite infectivity. Of special note is the up-regulation of genes that appear “off” in tachyzoites and bradyzoites but that encode homologues of proteins known to serve key functions in those asexual stages, including a novel pairing of sporozoite-specific paralogues of AMA1 and RON2, two proteins that have recently been shown to form a crucial bridge during tachyzoite invasion of host cells. This work provides the first in-depth insight into the development and functioning of one of the most important but least studied stages in the Toxoplasma life cycle

Effects of hospital facilities on patient outcomes after cancer surgery: an international, prospective, observational study

Background Early death after cancer surgery is higher in low-income and middle-income countries (LMICs) compared with in high-income countries, yet the impact of facility characteristics on early postoperative outcomes is unknown. The aim of this study was to examine the association between hospital infrastructure, resource availability, and processes on early outcomes after cancer surgery worldwide.Methods A multimethods analysis was performed as part of the GlobalSurg 3 study-a multicentre, international, prospective cohort study of patients who had surgery for breast, colorectal, or gastric cancer. The primary outcomes were 30-day mortality and 30-day major complication rates. Potentially beneficial hospital facilities were identified by variable selection to select those associated with 30-day mortality. Adjusted outcomes were determined using generalised estimating equations to account for patient characteristics and country-income group, with population stratification by hospital.Findings Between April 1, 2018, and April 23, 2019, facility-level data were collected for 9685 patients across 238 hospitals in 66 countries (91 hospitals in 20 high-income countries; 57 hospitals in 19 upper-middle-income countries; and 90 hospitals in 27 low-income to lower-middle-income countries). The availability of five hospital facilities was inversely associated with mortality: ultrasound, CT scanner, critical care unit, opioid analgesia, and oncologist. After adjustment for case-mix and country income group, hospitals with three or fewer of these facilities (62 hospitals, 1294 patients) had higher mortality compared with those with four or five (adjusted odds ratio [OR] 3.85 [95% CI 2.58-5.75]; p&lt;0.0001), with excess mortality predominantly explained by a limited capacity to rescue following the development of major complications (63.0% vs 82.7%; OR 0.35 [0.23-0.53]; p&lt;0.0001). Across LMICs, improvements in hospital facilities would prevent one to three deaths for every 100 patients undergoing surgery for cancer.Interpretation Hospitals with higher levels of infrastructure and resources have better outcomes after cancer surgery, independent of country income. Without urgent strengthening of hospital infrastructure and resources, the reductions in cancer-associated mortality associated with improved access will not be realised