Biology subjects

Sparber, F.

Publications and source records attributed to Sparber, F..

4 recordsLinked to original sources

bioRxiv2025

Langerhans Cell-targeted mRNA Delivery: A Strategy for Dose-Sparing and Enhanced Anti-Tumor Immunity

Despite the success of mRNA therapeutics, challenges remain in optimizing immune responses and minimizing side effects. Cell-specific antigen delivery may help reduce required doses and improve vaccine efficacy. In this study, we report on the first targeted delivery system for mRNA to a specific subset of skin-resident antigen-presenting cells - Langerhans cells. By functionalizing lipid nanoparticles (LNPs) with a langerin-specific glycomimetic ligand, we achieve selective mRNA delivery to both murine and human primary Langerhans cells with minimal off-target uptake, at the same time resulting in significantly increased mRNA translation. This targeted mRNA delivery not only enhances antigen presentation and T cell responses but also enables dose-sparing and superior anti-tumor immunity compared to conventional immunization in a B16-OVA tumor model. Importantly, our platforms high compatibility with various lipid nanoparticle formulations offers a flexible and precise tool for skin-directed mRNA delivery.

immunology↗

bioRxiv2025

Langerhans Cell-targeted Protein Delivery Enhances Antigen-Specific Cellular Immune Response

Targeted antigen delivery to immune cells, particularly dendritic cells, has emerged as a promising strategy to enhance therapeutic efficacy of vaccines, while minimizing adverse effects associated with conventional immunization. In this study, we use our previously described small glycomimetic molecule that selectively recognizes the Langerhans cell (LC)-specific surface receptor Langerin and demonstrate specific delivery of protein antigens to these specialized dendritic cells. Our results show that Langerin-mediated antigen delivery significantly enhances the immune response in vivo, resulting in increased expansion and activation of antigen-specific T cells, compared to immunization with unmodified antigen. We demonstrate the feasibility of our LC-targeted platform for immune cell-specific immunization with protein antigen and underscore the potential of LCs as an access point for next-generation vaccines and immunotherapies.

immunology↗

bioRxiv2024

Card9 and MyD88 differentially regulate Th17 immunity to the commensal yeast Malassezia in the murine skin

The fungal community of the skin microbiome is dominated by a single genus, Malassezia. Besides its symbiotic lifestyle at the host interface, this commensal yeast has also been associated with diverse inflammatory skin diseases in humans and pet animals. Stable colonization is maintained by antifungal type 17 immunity. The mechanisms driving Th17 responses to Malassezia remain, however, unclear. Here, we show that the C-type lectin receptors Mincle, Dectin-1, and Dectin-2 recognize conserved patterns in the cell wall of Malassezia and induce dendritic cell activation in vitro, while only Dectin-2 is required for Th17 activation during experimental skin colonization in vivo. In contrast, Toll-like receptor recognition was redundant in this context. Instead, inflammatory IL-1 family cytokines signaling via MyD88 were also implicated in Th17 activation in a T cell-intrinsic manner. Taken together, we characterized the pathways contributing to protective immunity against the most abundant member of the skin mycobiome. This knowledge contributes to the understanding of barrier immunity and its regulation by commensals and is relevant considering how aberrant immune responses are associated with severe skin pathologies.

immunology↗

bioRxiv2020

Horizontal gene transfer in the human and skin commensal Malassezia: a bacterially-derived flavohemoglobin is required for NO resistance and host interaction

The skin of humans and animals is colonized by commensal and pathogenic fungi and bacteria that share this ecological niche and have established microbial interactions. Malassezia are the most abundant fungal skin inhabitant of warm-blooded animals, and have been implicated in skin diseases and systemic disorders, including Crohns disease and pancreatic cancer. Flavohemoglobin is a key enzyme involved in microbial nitrosative stress resistance and nitric oxide degradation. Comparative genomics and phylogenetic analyses within the Malassezia genus revealed that flavohemoglobin-encoding genes were acquired through independent horizontal gene transfer events from different donor bacteria that are part of the mammalian microbiome. Through targeted gene deletion and functional complementation in M. sympodialis, we demonstrated that bacterially-derived flavohemoglobins are cytoplasmic proteins required for nitric oxide detoxification and nitrosative stress resistance under aerobic conditions. RNAseq analysis revealed that endogenous accumulation of nitric oxide resulted in upregulation of genes involved in stress response, and downregulation of the MalaS7 allergen-encoding genes. Solution of the high-resolution X-ray crystal structure of Malassezia flavohemoglobin revealed features conserved with both bacterial and fungal flavohemoglobins. In vivo pathogenesis is independent of Malassezia flavohemoglobin. Lastly, we identified additional 30 genus- and species-specific horizontal gene transfer candidates that might have contributed to the evolution of this genus as the most common inhabitants of animal skin. Significance statementMalassezia species are the main fungal components of the mammalian skin microbiome and are associated with a number of skin disorders. Recently, Malassezia has also been found in association with Crohns Disease and with pancreatic cancer. The elucidation of the molecular bases of skin adaptation by Malassezia is critical to understand its role as commensal and pathogen. In this study we employed evolutionary, molecular, biochemical, and structural analyses to demonstrate that the bacterially-derived flavohemoglobins acquired by Malassezia through horizontal gene transfer resulted in a gain of function critical for nitric oxide detoxification and resistance to nitrosative stress. Our study underscores horizontal gene transfer as an important force modulating Malassezia evolution and niche adaptation.

microbiology↗