Background Tropomyosins are highly conserved proteins, an attribute that forms the molecular basis for their IgE antibody cross‐reactivity. Despite sequence similarities, their allergenicity varies greatly between ingested and inhaled invertebrate sources. In this study, we investigated the relationship between the structural stability of different tropomyosins, their endolysosomal degradation patterns, and T‐cell reactivity. Methods We investigated the differences between four tropomyosins—the major shrimp allergen Pen m 1 and the minor allergens Der p 10 (dust mite), Bla g 7 (cockroach), and Ani s 3 (fish parasite)—in terms of IgE binding, structural stability, endolysosomal degradation and subsequent peptide generation, and T‐cell cross‐reactivity in a BALB/c murine model. Results Tropomyosins displayed different melting temperatures, which did not correlate with amino acid sequence similarities. Endolysosomal degradation experiments demonstrated differential proteolytic digestion, as a function of thermal stability, generating different peptide repertoires. Pen m 1 (Tm 42°C) and Der p 10 (Tm 44°C) elicited similar patterns of endolysosomal degradation, but not Bla g 7 (Tm 63°C) or Ani s 3 (Tm 33°C). Pen m 1–specific T‐cell clones, with specificity for regions highly conserved in all four tropomyosins, proliferated weakly to Der p 10, but did not proliferate to Bla g 7 and Ani s 3, indicating lack of T‐cell epitope cross‐reactivity. Conclusions Tropomyosin T‐cell cross‐reactivity, unlike IgE cross‐reactivity, is dependent on structural stability rather than amino acid sequence similarity. These findings contribute to our understanding of cross‐sensitization among different invertebrates and design of suitable T‐cell peptide‐based immunotherapies for shrimp and related allergies.

Conclusion: MAESTRO software was very efficient in detecting single point mutations that increase or reduce fold-stability. Thermal stability correlated well with the speed of proteolytic degradation and presentation of peptides on the surface of dendritic cells in vitro. This change in processing kinetics significantly influenced the polarization of T cell responses in vivo. Modulating the fold-stability of proteins thus has the potential to optimize and polarize immune responses, which opens the door to more efficient design of molecular vaccines.

This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

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This is an open access article under the terms of the Creative Commons Attribution-NonCommercial-NoDerivs License, which permits use and distribution in any medium, provided the original work is properly cited, the use is non-commercial and no modifications or adaptations are made. AbstractBackground: Skin-based immunotherapy of type 1 allergies has recently been reinvestigated as an alternative for subcutaneous injections. In the current study, we employed a mouse model of house dust mite (HDM)-induced lung inflammation to explore the potential of laser-facilitated epicutaneous allergen-specific treatment. Methods: Mice were sensitized against native Dermatophagoides pteronyssinus extract and repeatedly treated by application of depigmented D pteronyssinus extract via lasergenerated skin micropores or by subcutaneous injection with or without alum. Following aerosol challenges, lung function was determined by whole-body plethysmography and bronchoalveolar lavage fluid was analyzed for cellular composition and cytokine levels. HDM-specific IgG subclass antibodies were determined by ELISA. Serum as well as cell-bound IgE was measured by ELISA, rat basophil leukemia cell assay, and ex vivo using a basophil activation test, respectively. Cultured lymphocytes were analyzed for cytokine secretion profiles and cellular polarization by flow cytometry. Results: Immunization of mice by subcutaneous injection or epicutaneous laser microporation induced comparable IgG antibody levels, but the latter preferentially induced regulatory T cells and in general downregulated T cell cytokine production. This effect was found to be a result of the laser treatment itself, independent from extract application. Epicutaneous treatment of sensitized animals led to induction of blocking IgG, and improvement of lung function, superior compared to the effects of subcutaneous therapy. During the whole therapy schedule, no local or systemic side effects occurred. Conclusion: Allergen-specific immunotherapy with depigmented HDM extract via laser-generated skin micropores offers a safe and effective treatment option for HDM-induced allergy and lung inflammation. K E Y W O R D S depigmented extract, epicutaneous immunotherapy, house dust mite, laser, skin immunization S U PP O RTI N G I N FO R M ATI O N Additional supporting information may be found online in the Supporting Information section. How to cite this article: Korotchenko E, Moya R, Scheiblhofer S, et al. Laser-facilitated epicutaneous immunotherapy with depigmented house dust mite extract alleviates allergic responses in a mouse model of allergic lung inflammation.

Preterm infants are at increased risk for invasive neonatal bacterial infections. S. epidermidis, a ubiquitous skin commensal, is a major cause of late-onset neonatal sepsis, particularly in high-resource settings. The vulnerability of preterm infants to serious bacterial infections is commonly attributed to their distinct and developing immune system. While developmentally immature immune defences play a large role in facilitating bacterial invasion, this fails to explain why only a subset of infants develop infections with low-virulence organisms when exposed to similar risk factors in the neonatal ICU. Experimental research has explored potential virulence mechanisms contributing to the pathogenic shift of commensal S. epidermidis strains. Furthermore, comparative genomics studies have yielded insights into the emergence and spread of nosocomial S. epidermidis strains, and their genetic and functional characteristics implicated in invasive disease in neonates. These studies have highlighted the multifactorial nature of S. epidermidis traits relating to pathogenicity and commensalism. In this review, we discuss the known host and pathogen drivers of S. epidermidis virulence in neonatal sepsis and provide future perspectives to close the gap in our understanding of S. epidermidis as a cause of neonatal morbidity and mortality.

Background: Tropomyosins are highly conserved proteins, an attribute that forms the molecular basis for their IgE antibody cross-reactivity. Despite structural similarities, their allergenicity varies greatly between ingested and inhaled invertebrate sources. In this study, we investigated the relationship between the structural stability of different tropomyosins, their endolysosomal degradation patterns and T-cell reactivity. Methods:We investigated the differences between four tropomyosins -the major shrimp allergen Pen m 1 and the minor allergens Der p 10 (dust mite), Bla g 7 (cockroach) and Ani s 3 (fish parasite) -in terms of IgE binding, structural stability, endolysosomal degradation and subsequent peptide generation,and T-cell cross-reactivity in a BALB/c murine model. Results:Despite their conserved primary structure and consequent IgE co-reactivity, the invertebrate tropomyosins displayed different protein stabilities. Pen m 1 and Ani s 3, but not Der p 10 and Bla g 7 elicited differential melting temperatures that were pH-dependent. Endolysosomal experiments demonstrated differential degradation, as a function of stability, generating different peptide repertoires.Pen m 1 T-cell clones, with specificity for sequences highly conserved in all four tropomyosins, did not proliferate with Der p 10, Bla g 7 and Ani s 3, indicating that these peptides were not naturally produced for other invertebrate tropomyosins. Conclusions:Our data suggest that, although invertebrate tropomyosins exhibit a high degree of IgE cross-reactivity due to conserved B-cell epitopes, they do not necessarily share identical cross-reactive T-cell epitopes. This is likely due to differential endolysosomal processing as a function of different structural stabilities. Word Count: 3619 14.Kavan D, Man P. MSTools-Web based application for visualization and presentation of HXMS data. Int J Mass Spectrom. 2011;302(1):53-58. 15.Reese G, Viebranz J, Leong-Kee SM, et al. Reduced allergenic potency of VR9-1, a mutant of the major shrimp allergen Pen a 1 (tropomyosin).

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