Biology subjects

Sarno, E. N.

Publications and source records attributed to Sarno, E. N..

4 recordsLinked to original sources

bioRxiv2026

CD1a-Mediated Presentation of Canonical Microbial Peptides to T Cells

Langerhans cells express the nonpolymorphic antigen-presenting molecule CD1a, positioning them as contributors to host immunity against Mycobacterium leprae in human leprosy. CD1a was originally shown to present non-canonical lipopeptide antigens such as dideoxymycobactin and chemically diverse hydrophobic ligands. Here, we generated CD4 T cell lines from leprosy lesions that recognized M. leprae in a CD1a-restricted manner. Unexpectedly, antigen recognition was protease-sensitive, prompting biochemical purification that identified two microbial protein antigens: LppX, a 25-kDa lipoglycoprotein, and Ag85A, a 30-kDa secreted protein with no known lipid modification. Recombinant proteins activated the corresponding T cell lines in a CD1a-dependent manner. Epitope mapping identified 12-mer peptides that fully reconstituted antigenicity, were conserved between M. leprae and M. tuberculosis, and elicited robust, dose-dependent IFN-{gamma} production and T cell proliferation, establishing that DNA-encoded, ribosomally translated peptides serve as CD1a-restricted cognate antigens. Biochemical analyses showed peptide binding to CD1a, supported by isoelectric focusing and surface plasmon resonance (KD [~]75 M for Ag85A). CD1a-peptide tetramers specifically stained cognate T cells, soluble CD1a was sufficient to present peptide antigen, and transfer of the LppX-specific TCR into naive T cells restored antigen responsiveness. Using CD1a-peptide tetramers, we identified antigen-specific T cells enriched in patients undergoing reversal reactions compared with patients with lepromatous leprosy and healthy donors. The CD1a-restricted T cell lines secreted IFN-{gamma} and IL-26, cytokines with established antimicrobial activity. Together, these findings demonstrate that CD1a can present canonical microbial peptides as part of a cell-mediated immune response in leprosy, extending the known spectrum of CD1a ligands. Because CD1a is nonpolymorphic and presents antigens to antimicrobial T cells, CD1a-peptide complexes may provide a broadly applicable platform for studying, detecting, and potentially targeting mycobacterial immunity.

immunology↗

bioRxiv2021

A new paradigm for leprosy diagnosis based on host gene expression

Transcriptional profiling is a powerful tool to investigate and detect human diseases. In this study, we used bulk RNA-sequencing (RNA-Seq) to compare the transcriptomes in skin lesions of leprosy patients or controls affected by other dermal conditions such as granuloma annulare, a confounder for paucibacillary leprosy. We identified five genes capable of accurately distinguishing multibacillary and paucibacillary leprosy from other skin conditions. Indoleamine 2,3-dioxygenase 1 (IDO1) expression alone was highly discriminatory, followed by TLR10, BLK, CD38, and SLAMF7, whereas the HS3ST2 and CD40LG mRNA separated multi- and paucibacillary leprosy. Finally, from the main differentially expressed genes (DEG) and enriched pathways, we conclude that paucibacillary disease is characterized by epithelioid transformation and granuloma formation, with an exacerbated cellular immune response, while multibacillary leprosy features epithelial-mesenchymal transition with phagocytic and lipid biogenesis patterns in the skin. These findings will help catalyze the development of better diagnostic tools and potential host-based therapeutic interventions. Finally, our data may help elucidate host-pathogen interplay driving disease clinical manifestations. Author SummaryDespite effective treatment, leprosy is still a significant public health issue in more than 120 countries, with more than 200 000 new cases yearly. The disease is caused mainly by Mycobacterium leprae, a slow-growing bacillus still uncultivable in axenic media. This limitation has hampered basic research into host-pathogen interaction and the development of new diagnostic assays. Currently, leprosy is diagnosed clinically, with no standalone diagnostic assay accurate enough for all clinical forms. Here, we use RNA-seq transcriptome profiling in leprosy lesions and granuloma annulare to identify mRNA biomarkers with potential diagnostic applications. Also, we explored new pathways that can be useful in further understanding the host-pathogen interaction and how the bacteria bypass host immune defenses. We found that IDO1, a gene involved with tryptophan catabolism, is an excellent candidate for distinguishing leprosy lesions from other dermatoses. Additionally, we observed that a previous signature of keratinocyte development and cornification negatively correlates with epithelial-mesenchymal transition genes in the skin, suggesting new ways in which the pathogen may subvert its host to survive and spread throughout the body. Our study identifies new mRNA biomarkers that can improve leprosy diagnostics and describe new insights about host-pathogen interactions in human skin.

molecular biology↗

bioRxiv2020

Single Cell and Spatial Transcriptomics Defines the Cellular Architecture of the Antimicrobial Response Network in Human Leprosy Granulomas

Granulomas are complex cellular structures comprised predominantly of macrophages and lymphocytes that function to contain and kill invading pathogens. Here, we investigated single cell phenotypes associated with antimicrobial responses in human leprosy granulomas by applying single cell and spatial sequencing to leprosy biopsy specimens. We focused on reversal reactions (RR), a dynamic process in which some patients with disseminated lepromatous leprosy (L-lep) transition towards self-limiting tuberculoid leprosy (T-lep), mounting effective antimicrobial responses. We identified a set of genes encoding proteins involved in antimicrobial responses that are differentially expressed in RR versus L-lep lesions, and regulated by IFN-{gamma} and IL-1{beta}. By integrating the spatial coordinates of the key cell types and antimicrobial gene expression in RR and T-lep lesions, we constructed a map revealing the organized architecture of granulomas depicting compositional and functional layers by which macrophages, T cells, keratinocytes and fibroblasts contribute to the antimicrobial response.

immunology↗

bioRxiv2019

Neutrophil Extracellular Traps contribute to the pathogenesis of leprosy type 2 reactions

Up to 50% of patients with the multibacillary form of leprosy is expected to develop acute systemic inflammatory episodes known as type 2 reactions (T2R), thus aggravating their clinical status. Thalidomide rapidly improves T2R symptoms. But, due to its restricted use worldwide, novel alternative therapies are urgently needed. A hallmark of T2R lesions is the presence of a neutrophil-rich inflammatory infiltrate. In this study, the potential involvement of neutrophil extracellular traps (NETs) production in T2R pathogenesis was investigated. Abundant NETs were found in T2R skin lesions, and increased spontaneous NETs formation was observed in T2R peripheral neutrophils. Both the M. leprae whole-cell sonicate and the CpG-Hlp complex, mimicking a mycobacterial TLR9 ligand, were able to induce NETs production in vitro. Moreover, TLR9 expression was shown to be higher in T2R neutrophils, suggesting that DNA recognition via TLR9 may be one of the pathways triggering this process during T2R. Finally, treatment of T2R patients with thalidomide for 7 consecutive days resulted in decreasing all of the evaluated in vivo and ex vivo NETosis parameters. Altogether, our findings shed light on the pathogenesis of T2R, which, it is hoped, will contribute to the emergence of novel alternative therapies in the near future.\n\nAuthor summaryLeprosy is caused by a mycobacterium that has a predilection for skin and nerve cells. The chronic course of the disease may be interrupted by acute inflammatory episodes known as reactions, despite effective bacterial killing with antibiotics. Reactions aggravate patients clinical status and may become a medical emergency. Type 2 reactions (T2R) only occur in patients with high bacterial burden and is treated with thalidomide and/or corticosteroids. We are interested in understanding how inflammation is triggered and amplified during T2R. In this study we investigated the potential role of extracellular DNA released by neutrophils (known as NETs) in T2R, since they have been shown to cause inflammation. Abundant NETs were found in T2R skin lesions, and increased spontaneous NETs formation was observed in neutrophils present in the blood of T2R patients. Moreover, bacterial constituents were able to induce NETs production. Finally, treatment of T2R patients with thalidomide resulted in decreased NET formation. Altogether, our findings shed light on the pathogenesis of T2R, which, it is hoped, will contribute to the identification of biomarkers for early diagnosis and emergence of novel alternative therapies in the near future.

immunology↗