Biology subjects

Landry, L.

Publications and source records attributed to Landry, L..

4 recordsLinked to original sources

bioRxiv2025

Tracking GAD-specific T-cell expansions in Type 1 diabetes by intradermal GAD-Alum challenge

Identifying and monitoring autoreactive T cells that drive beta cell destruction remains a major obstacle to developing effective immunotherapies for type 1 diabetes (T1D). These cells are extremely rare in peripheral blood and cannot be accessed directly from the pancreas. We used intradermal injection of GAD-Alum to recruit GAD-specific T cells to accessible sites in the skin and skin-draining lymph nodes (LNs), sampled by skin suction blisters and ultrasound-guided LN aspiration. Peripheral blood samples obtained before GAD injection were restimulated with GAD in vitro to detect reactive CD4+ T cells. Re-expression of selected T cell receptors (TCRs) confirmed antigen specificity. Up to 70% of T cells at the skin injection site were clonally-expanded and 4 of 14 (28%) re-expressed TCRs were GAD-reactive. In draining LNs 1 of 14 (4%) clonally-expanded TCRs was GAD-reactive, representing [~]0.08% of all T-cells. GAD-reactive cells across compartments displayed Th1 and Th17-associated transcription signatures. These results demonstrate the intradermal autoantigen challenge, coupled with scRNAseq, enables direct identification and molecular profiling of autoreactive T cells in vivo. This minimally invasive approach provides a powerful platform for tracking antigen-specific specific T cells to monitor disease activity and evaluate immune interventions in T1D.

immunology↗

bioRxiv2023

The intracellular growth of the vacuolar pathogen Legionella pneumophila is dependent on the acyl chain composition of host membranes

Legionella pneumophila is an accidental human bacterial pathogen that infects and replicates within alveolar macrophages causing a severe atypical pneumonia known as Legionnaires disease. As a prototypical vacuolar pathogen L. pneumophila establishes a unique endoplasmic reticulum (ER)-derived organelle within which bacterial replication takes place. Bacteria-derived proteins are deposited in the host cytosol and in the lumen of the pathogen-occupied vacuole via a type IVb (T4bSS) and a type II (T2SS) secretion system respectively. These secretion system effector proteins manipulate multiple host functions to facilitate intracellular survival of the bacteria. Subversion of host membrane glycerophospholipids (GPLs) by the internalized bacteria via distinct mechanisms feature prominently in trafficking and biogenesis of the Legionella-containing vacuole (LCV). Conventional GPLs composed of a glycerol backbone linked to a polar headgroup and esterified with two fatty acids constitute the bulk of membrane lipids in eukaryotic cells. The acyl chain composition of GPLs dictates phase separation of the lipid bilayer and therefore determines the physiochemical properties of biological membranes - such as membrane disorder, fluidity and permeability. In mammalian cells, fatty acids esterified in membrane GPLs are sourced endogenously from de novo synthesis or via internalization from the exogenous pool of lipids present in serum and other interstitial fluids. Here, we exploited the preferential utilization of exogenous fatty acids for GPL synthesis by macrophages to reprogram the acyl chain composition of host membranes and investigated its impact on LCV homeostasis and L. pneumophila intracellular replication. Using saturated fatty acids as well as cis- and trans- isomers of monounsaturated fatty acids we discovered that under conditions promoting lipid packing and membrane rigidification L. pneumophila intracellular replication was significantly reduced. Palmitoleic acid - a C16:1 monounsaturated fatty acid - that promotes membrane disorder when enriched in GPLs significantly increased bacterial replication within human and murine macrophages but not in axenic growth assays. Lipidome analysis of infected macrophages showed that treatment with exogenous palmitoleic acid resulted in membrane acyl chain reprogramming in a manner that promotes membrane disorder and live-cell imaging revealed that the consequences of increasing membrane disorder impinge on several LCV homeostasis parameters. Collectively, we provide experimental evidence that L. pneumophila replication within its intracellular niche is a function of the lipid bilayer disorder and hydrophobic thickness.

microbiology↗

bioRxiv2023

Interferon-α promotes neo-antigen formation andpreferential HLA-B-restricted antigen presentation in pancreatic β-cells

Interferon (IFN)- is the earliest cytokine signature observed in individuals at risk for type 1 diabetes (T1D), but its effect on the repertoire of HLA Class I (HLA-I)-bound peptides presented by pancreatic {beta}-cells is unknown. Using immunopeptidomics, we characterized the peptide/HLA-I presentation in in-vitro resting and IFN--exposed {beta}-cells. IFN- increased HLA-I expression and peptide presentation, including neo-sequences derived from alternative mRNA splicing, post-translational modifications - notably glutathionylation - and protein cis-splicing. This antigenic landscape relied on processing by both the constitutive and immune proteasome. The resting {beta}-cell immunopeptidome was dominated by HLA-A-restricted ligands. However, IFN- only marginally upregulated HLA-A and largely favored HLA-B, translating into a major increase in HLA-B-restricted peptides and into an increased activation of HLA-B-restricted vs. HLA-A-restricted CD8+ T-cells. A preferential HLA-B hyper-expression was also observed in the islets of T1D vs. non-diabetic donors, and we identified islet-infiltrating CD8+ T-cells from T1D donors reactive to HLA-B-restricted granule peptides. Thus, the inflammatory milieu of insulitis may skew the autoimmune response toward epitopes presented by HLA-B, hence recruiting a distinct T-cell repertoire that may be relevant to T1D pathogenesis.

immunology↗

bioRxiv2023

Conserved spatiotemporal expression landscape of dominant tRNA genes in human and mouse

Transfer RNAs are integral for protein synthesis and the interpretation of the information contained in DNA. To date, a few methods, including custom microarrays and custom targeted sequencing, have been used to quantify tRNA. However, methods using available RNA-sequencing data have not yet been reported. We created a bioinformatics pipeline to quantify the highly expressed tRNAs in RNA-Seq effectively, demonstrated by the preserved ratio of the expression levels of two massively duplicated tRNAAla genes in mouse. Using this quantification, we examined the tRNA expression with relation to tissue type and developmental stage in both human and mouse. Heart exhibited the highest overall tRNA expression for both human and mouse. Furthermore, tRNA expression grew to a peak before decreasing steadily with developmental stage, a trend that was conserved in both human and mouse. The two mitochondrial tRNA genes, tRNASer(TCA)(m) and tRNALeu(TTA)(m), which partly contribute to these trends, have been attributed to various human diseases. The tissue-specific high expression of tRNAGln(CAG) and tRNAGln(CAA) in human brains, especially in hindbrain and cerebellum, suggests their important roles in neurological disorders. In summary, our approach revealed conserved spatiotemporal expression of highly expressed tRNAs in both human and mouse. Our method can be applied to other RNA- Seq data to examine the roles of these tRNAs in different human diseases or scientific studies.

genetics↗