Different sec-requirements for signal peptide cleavage and protein translocation in a model E. coli protein

AbstractWe describe a secretory E. coli protein with a novel phenotype: signal peptide cleavage is largely unaffected whereas chain translocation is efficiently blocked under conditions where SecA, a central component of the secretory machinery, is rendered non-functional, and we have traced this phenotype to the presence of a mildly hydrophobic segment located ~30 residues downstream of the signal peptide. When this segment is deleted, normal SecA-dependent signal peptide cleavage and chain translocation is observed; when its hydrophobicity is increased, it becomes a permanent membrane anchor with cleavage of the signal peptide and membrane insertion both being SecA-independent. These findings suggest that the initial insertion of the signal peptide across the membrane can be uncoupled from the translocation process proper

Supplementary data for the article: Apostolovic, D.; Sánchez-Vidaurre, S.; Waden, K.; Curin, M.; Grundström, J.; Gafvelin, G.; Cirkovic Velickovic, T.; Grönlund, H.; Thomas, W. R.; Valenta, R.; et al. The Cat Lipocalin Fel d 7 and Its Cross-Reactivity with the Dog Lipocalin Can f 1. Allergy: European Journal of Allergy and Clinical Immunology 2016, 71 (10), 1490–1495. https://doi.org/10.1111/all.12955

Supplementary material for: [https://doi.org/10.1111/all.12955]Related to published version: [http://cherry.chem.bg.ac.rs/handle/123456789/2337]Related to accepted version: [http://cherry.chem.bg.ac.rs/handle/123456789/3650

Cross-reactive EBNA1 immunity targets alpha-crystallin B and is associated with multiple sclerosis

Multiple sclerosis (MS) is an inflammatory disease of the central nervous system, for which and Epstein-Barr virus (EBV) infection is a likely prerequisite. Due to the homology between Epstein-Barr nuclear antigen 1 (EBNA1) and alpha-crystallin B (CRYAB), we examined antibody reactivity to EBNA1 and CRYAB peptide libraries in 713 persons with MS (pwMS) and 722 matched controls (Con). Antibody response to CRYAB amino acids 7 to 16 was associated with MS (OR = 2.0), and combination of high EBNA1 responses with CRYAB positivity markedly increased disease risk (OR = 9.0). Blocking experiments revealed antibody cross-reactivity between the homologous EBNA1 and CRYAB epitopes. Evidence for T cell cross-reactivity was obtained in mice between EBNA1 and CRYAB, and increased CRYAB and EBNA1 CD4$^{+}$ T cell responses were detected in natalizumab-treated pwMS. This study provides evidence for antibody cross-reactivity between EBNA1 and CRYAB and points to a similar cross-reactivity in T cells, further demonstrating the role of EBV adaptive immune responses in MS development

Vitamin D and allergies

An increasing amount of evidence has established that the biologically active form of vitamin D, 1,25-dihydroxy vitamin D3, possesses immunoregulatory properties. Vitamin D exerts its effects through binding to the nuclear vitamin D receptor (VDR), which is expressed by cells of the immune system. Most of the immunological effects mediated by vitamin D-VDR are regulatory, inhibiting adaptive immune responses. It has become apparent that the incidence of vitamin D insufficiency is surprisingly high in the general population. A link between low vitamin D serum levels and the increased prevalence of allergic diseases has been proposed. This possible connection has been investigated in numerous studies on associations between vitamin D serum concentrations and different allergic conditions, as well as studies on the effect of vitamin D supplementation. Although there is some evidence for a protective role of vitamin D in asthma, no consensus on the role of vitamin D in allergic disease has yet been reached. Still, treatment strategies involving vitamin D supplementation to risk groups, combinatorial corticosteroid and vitamin D treatment in asthma and vitamin D as an immunomodulator in allergen specific immunotherapy show promise for the future

The non-proteolytic house dust mite allergen Der p 2 induce NF-kappa B and MAPK dependent activation of bronchial epithelial cells

P gt Background House dust mites (HDM) are well-known as a source of indoor aeroallergens and for causing allergic airway diseases. Some proteolytic HDM allergens are known to activate respiratory epithelial cells to produce pro-inflammatory mediators, while there is limited knowledge regarding such activity among non-proteolytic HDM allergens. Objective To investigate whether Der p 2, a major non-proteolytic allergen of Dermatophagoides pteronyssinus, activates respiratory epithelial cells to produce mediators involved in asthma pathogenesis and to elucidate the mechanism of such activation. Methods The human bronchial epithelial cell line BEAS-2B, normal human bronchial epithelial (NHBE) cells and the alveolar epithelial cell line A549 were exposed to recombinant Der p 2. Following exposure, we analysed a panel of soluble mediators and cell adhesion receptors involved in asthma pathogenesis by promoting recruitment, survival and binding of inflammatory cells. The involvement of nuclear factor (NF)-kappa B and mitogen-activated protein kinases (MAPKs) was studied using specific inhibitors. Results Der p 2 activated bronchial BEAS-2B and NHBE cells, but not alveolar A549 cells. In BEAS-2B cells Der p 2 induced dose-dependent up-regulation in both mRNA level and protein secretion of granulocyte-macrophage colony-stimulating factor, IL-6, IL-8, monocyte-chemotactic protein-1 and macrophage inflammatory protein-3 alpha. Secretion as well as surface expression of intercellular adhesion molecule (ICAM)-1 was also up-regulated, which was associated with increased adhesion of monocytes to the epithelial cells. The release of cytokines and chemokines was regulated by NF-kappa B and MAPK activation in different ways, while expression of ICAM-1 was solely dependent on NF-kappa B activation. Conclusion These results show that Der p 2 activates respiratory epithelial cells, indicating that this non-proteolytic allergen, in addition to its immunogenic properties, can aggravate respiratory airway disease by adjuvant-like activation of the lung epithelium

Measurement of Horse Allergens Equ c 1 and Equ c 2 : A Comparison among Breeds

Introduction: Horse allergens are less studied than allergens from other furry animals and these allergens must be evaluated to understand the complexity of allergy to horses. The aims of this study were to develop assays for the horse allergens Equ c 1 and Equ c 2 in dander and saliva and to determine their levels in ten horse breeds. The study also included a comparison of these findings with previous results on the levels of Equ c 4 performed on the same study population. Method: The study population included 170 horses from 10 horse breeds including American Curly and Russian Bashkir horse, which have been suggested to be hypoallergenic. Competitive ELISA assays were developed, with polyclonal antibodies as capture antibodies, for the detection of Equ c 1 and Equ c 2 in dander and saliva samples. Results: The horse allergens Equ c 1 and Equ c 2 were found in all dander and saliva samples from the ten horse breeds. The GM level (ng/mu g protein) of Equ c 1 in dander was 470 (range 129-2,569) and in saliva samples, 40 (range 6-160). The GM level of Equ c 2 in dander was 138 (range 18-1,650) and in saliva samples, 0.8 (range 0.03-17). In dander, there were no significant differences in Equ c 1 and Equ c 2 GM levels between stallions, mares, and geldings. Conclusion: Our results show high intra- and inter-breed variability. Neither the American Curly horse nor the Russian Bashkir horse, earlier categorized as hypoallergenic breeds, was associated with lower allergen levels of Equ c 1, Equ c 2, or Equ c 4 than the other horse breeds investigated

Low levels of endotoxin enhance allergen-stimulated proliferation and reduce the threshold for activation in human peripheral blood cells

Background: Endotoxins, comprised of bacterial cell wall lipopolysaccharides (LPS), have been reported to have both protective and exacerbating effects on the development and maintenance of allergic disease in humans and on markers of allergic inflammation in animal models of allergy. In this study, we investigated the effect of low concentrations of LPS on human peripheral blood mononuclear cells (PBMC) stimulated with the major cat allergen Fel d 1. Methods: Extensive purification of recombinant (r) Fel d 1 yielded essentially endotoxin-free rFel d 1 (0.2 ng LPS/mg protein). PBMCs prepared from 15 subjects having IgE to cat ( gt 0.7 kU(A)/l) and 8 subjects IgE negative to cat were stimulated with 2, 10 or 25 mu g/ml of rFel d 1 in the presence or absence of 50 pg/ml LPS. Proliferation was measured after 7 days of culture and supernatants were analyzed for IFN gamma, IL-5 and IL-10. Results: LPS (50 pg/ml) increased rFel d 1-stimulated proliferation of PBMCs both from subjects IgE-positive and subjects negative to cat allergens. PBMCs from 13 of the subjects did not proliferate in response to stimulation with 2 and 10 mu g/ml rFel d 1 alone but did so in the presence of LPS. Moreover, LPS increased the levels of rFel d 1-stimulated IFN gamma in cultures from cat-negative subjects, IL-5 from cat-positive subjects and IL-10 from both groups. Conclusion: Very low doses of LPS enhance proliferation and decrease the apparent threshold level for cell activation, prompting careful evaluation of allergen stimulated T cell activation in vitro. Copyright (C) 2007 S. Karger AG, Basel