In cystic fibrosis (CF), the accumulation of viscous lung secretions rich in DNA and actin is a major cause of chronic inflammation and recurrent infections leading to airway obstruction. Mucolytic therapy based on recombinant human DNase1 reduces CF mucus viscosity and promotes airway clearance. However, the marked susceptibility to actin inhibition of this enzyme prompts the research of alternative treatments that could overcome this limitation. Within the human DNase repertoire, DNase1L2 is ideally suited for this purpose because it exhibits metal-dependent endonuclease activity on plasmid DNA in a broad range of pH with acidic optimum and is minimally inhibited by actin. When tested on CF artificial mucus enriched with actin, submicromolar concentrations of DNase1L2 reduces mucus viscosity by 50% in a few seconds. Inspection of superimposed model structures of DNase1 and DNase1L2 highlights differences at the actin-binding interface that justify the increased resistance of DNase1L2 toward actin inhibition. Furthermore, a PEGylated form of the enzyme with preserved enzymatic activity was obtained, showing interesting results in terms of activity. This work represents an effort toward the exploitation of natural DNase variants as promising alternatives to DNase1 for the treatment of CF lung disease.

Insect consumption could address the increasing protein demand in compliance with environmental sustainability. Hermetia illucens (black soldier fly, BSF) is a promising insect for human diet and it is essential to assess the related allergenic risk, meant as primary sensitization or cross-reactivity with known allergens. In this work, we investigate the allergenicity of two tropomyosin variants identified in the BSF genome and produced as recombinant proteins. Immunoblot experiments showed that both proteins were recognized by sera of patients allergic to shrimp or mites highlighting the cross-reactivity risk. CD spectroscopy, cross-linking assays and size-exclusion chromatography showed a structure composed of alpha-helices oligomers for both variants. These proteins were quite stable to pH but sensitive to increasing temperatures. In vitro simulated digestion associated to mass-spectrometry allowed the identification of peptides resistant to gastrointestinal conditions which were compared with epitopes of Arthropoda and Mollusca allergens to predict the persistence of allergenicity upon digestion.

Given their nutritional features and environmental sustainability, black soldier fly (Hermetia illucens) larvae are currently being considered in Europe for commercialization as human food. The primary goal of this study is the determination of in vitro IgE-cross-reactivity to recombinant tropomyosin (_HITPM) and arginine kinase (_HIAK) of H. illucens in subjects sensitized to crustaceans and/or mites. Dot blot assays for recombinant _HITPM were carried out with the sera of 48 subjects, 30 sensitized to crustaceans (Cr+) and/or house dust mites (HDM+) (STUDY group) and 18 non-sensitized (CTRL group). A higher rate of IgE-reactivity to recombinant _HITPM was found in the STUDY group compared to non-sensitized controls (73% vs. 44%; p 0.066). No significant relationship was achieved upon dot blot assays for _HIAK. No relevant association between a positive history of food reactions and immunoreactivity to _HITPM and to _HIAK was reported (15% in _HITPM+ vs. 6% in _HITPM-, p NS; 28% in _HIAK+ vs. 50% in _HIAK-, p NS), contrary to the _HITPM+Cr+HDM+ subset (50% vs. 0%, p 0.022). Considering the wide overlap of pan-allergens within the Arthropoda phylum, concerns about allergenic potential due to the eventual consumption of H. illucens-enriched foods might be valid. Therefore, targeted studies involving basophil activation tests, skin prick tests, and a double-blind placebo-controlled oral food challenge using H. illucens are needed.

Herein, we investigated the toxicity and membrane-permeabilizing capabilities of Lpt and Lpt-like peptides, belonging to type I toxin–antitoxin systems carried by plasmid DNA of Lacticaseibacillus strains. These 29 amino acid peptides are predicted to form α-helical structures with a conserved central hydrophobic sequence and differently charged hydrophilic termini. Like Lpt, the expression of Lpt-like in E. coli induced growth arrest, nucleoid condensation, and cell membrane damage, suggesting membrane interaction as the mode of action. The membrane permeabilization activity of both peptides was evaluated by using liposome leakage assays, dynamic light scattering, and CD spectroscopy. Lpt and Lpt-like showed liposome leakage activity, which did not lead to liposome disruption but depended on peptide concentration. Lpt was generally more effective than Lpt-like, probably due to different physical chemical properties. Leakage was significantly reduced in larger liposomes and increased with negatively charged PCPS liposomes, indicating that electrostatic interactions and membrane curvature influence peptide activity. Contrary to most membrane-active peptides, Lpt an Lpt-like progressively lost their α-helical structure upon interaction with liposomes. Our data are inconsistent with the formation of membrane-spanning peptide pores but support a mechanism relying on the transient failure of the membrane permeability barrier possibly through the formation of “lipid pores”.

Microalgae have emerged as promising sources of sustainable nutrients and bioactive compounds, attracting growing interest for their potential use in future food systems. Arthrospira platensis (commonly known as Spirulina) is particularly valued for its high protein content and functional pigments, among which C-phycocyanin (C-PC) is the most abundant. Although Spirulina is generally recognized as safe by regulatory agencies, recent reports have described allergic reactions in sensitized individuals, raising concerns about the allergenic potential of C-PC and related proteins. In this study, C-PC was extracted and purified from A. platensis, and its structural integrity and oligomeric state were characterized. Immunoreactivity was assessed using sera from Spirulina-sensitized patients and allergic to crustaceans, mites, and fish to explore potential cross-reactivity. Simulated gastrointestinal digestion was then performed to evaluate the stability and allergenic behavior of the protein. C-PC displayed clear IgE-binding activity in its intact form, confirming its relevance as a potential allergen. However, simulated gastrointestinal digestion reduced IgE-binding activity and caused extensive fragmentation and high-resolution LC–MS analysis. This work provides new insights into the digestive profile and immunoreactivity of Spirulina proteins, supporting a more accurate assessment of their safety and informing their responsible use in food and nutraceutical applications.