Biology subjects

Jutras, B. L.

Publications and source records attributed to Jutras, B. L..

2 recordsLinked to original sources

bioRxiv2026

Transposon insertion sequencing of Pseudomonas aeruginosa identifies multiple intersecting pathways essential for extreme colistin resistance

Colistin is used to treat antibiotic resistant gram-negative infections, including those caused by Pseudomonas aeruginosa (Pa). Using a diverse collection of clinical isolates, we identified BWH047, a colistin-resistant isolate with an extremely high minimum inhibitory concentration (MIC, 1280 {micro}g/mL). To characterize the genes conditionally essential for colistin resistance in BWH047, we employed transposon insertion sequencing and identified 20 gene candidates. In-frame deletion validated 75% of the candidates and identified genes in several novel pathways that contribute to colistin resistance, including algU and wapH. We also identified several candidate genes from previously reported colistin resistance pathways (e.g. arn, pmrAB). We further investigated the impact of a colistin resistance-associated inner membrane DedA-family undecaprenyl phosphate flippase, which we named DpcA (DedA of Pseudomonas necessary for colistin resistance A). Deletion of dpcA in BWH047 restored sensitivity to colistin (MIC = 0.5 {micro}g/mL) and resulted in several unique changes to the structure of lipopolysaccharide (LPS), including production of decreased amounts of the colistin resistance-conferring 4-amino-4-deoxy-L-arabinose (L-Ara4N) modification on lipid A. To date, this work represents the most complete analysis of colistin resistance in Pa and identifies novel intersecting pathways that contribute to extreme phenotypic resistance. Author summaryPseudomonas aeruginosa is a bacterium that causes a wide variety of infections. It is especially problematic given its propensity to become resistant to antibiotics. One antibiotic used to treat multidrug-resistant P. aeruginosa infections is colistin. In this study, we investigated colistin resistance mechanisms in a patient-derived, extremely phenotypically resistant P. aeruginosa isolate, BWH047, using transposon insertion sequencing and mass spectrometry. We identified 13 genes conditionally essential for colistin resistance and investigated the role of one of these genes, dpcA, on the composition of the bacterial outer membrane, the target of colistin. Additionally, our study identified novel colistin resistance genes residing in several intersecting pathways that could be targeted to prevent the development of antimicrobial resistance.

microbiology↗

bioRxiv2023

HLA-DR-expressing fibroblast-like synoviocytes are inducible antigen presenting cells that present autoantigens in Lyme arthritis

BackgroundHLA-DR-expressing fibroblast-like synoviocytes (FLS) are a prominent cell type in synovial tissue in chronic inflammatory forms of arthritis. We recently showed that peptides from several extracellular matrix (ECM) proteins, including fibronectin-1 (FN1), contained immunogenic CD4+ T cell epitopes in patients with postinfectious Lyme arthritis (LA). However, the role of FLS in presentation of these T cell epitopes remains uncertain. MethodsPrimary LA FLS and primary murine FLS stimulated with interferon gamma (IFN{gamma}), Borrelia burgdorferi, and/or B. burgdorferi peptidoglycan (PG) were assessed for properties associated with antigen presentation. HLA-DR-presented peptides from stimulated LA FLS were identified by immunopeptidomics analysis. OT-II T cells were cocultured with stimulated murine FLS in the presence of cognate ovalbumin antigen to determine the potential of FLS to act as inducible antigen presenting cells (APC). ResultsFLS expressed HLA-DR molecules within inflamed synovial tissue and tendons from patients with post-infectious LA patients in situ. MHC class II and costimulatory molecules were expressed by FLS following in vitro stimulation with IFN{gamma} and B. burgdorferi and presented both foreign and self MHC-II peptides, including T cell epitopes derived from two Lyme autoantigens fibronectin-1 (FN1) and endothelial cell growth factor (ECGF). Stimulated murine FLS induced proliferation of naive OT-II CD4+ T cells, particularly when FLS were stimulated with both IFN{gamma} and PG. ConclusionsMHC-II+ FLS are inducible APCs that can induce CD4+ T cell activation and can present Lyme autoantigens derived from ECM proteins, thereby amplifying tissue-localized autoimmune CD4+ T cell responses in LA. AUTHORS SUMMARYThis study demonstrates that IFN{gamma}-activated MHC-II+ fibroblast-like synoviocytes (FLS) stimulated with Borrelia burgdorferi present foreign and self MHC-II antigens, including Lyme autoantigens. Furthermore, IFN{gamma}-activated MHC-II+ FLS stimulated with B. burgdorferi peptidoglycan can induce activation and proliferation of naive CD4+ T cells in an MHC-II antigen-dependent manner, demonstrating that activated MHC-II+ FLS are inducible antigen presenting cells.

immunology↗