Biology subjects

Loffredo, L. F.

Publications and source records attributed to Loffredo, L. F..

3 recordsLinked to original sources

bioRxiv2025

Distinct CD8+ T-cell types Associated with COVID-19 Severity in Unvaccinated HLA-A2+ Patients

Although emerging data have revealed the critical role of memory CD8+ T cells in preventing and controlling SARS-CoV-2 infection, virus-specific CD8+ T-cell responses against SARS-CoV-2 and its memory and innate-like subsets in unvaccinated COVID-19 patients with various disease manifestations in an HLA-restricted fashion remain to be understood. Here, we show the strong association of protective cellular immunity with mild COVID-19 and unique cell types against SARS-CoV-2 virus in an HLA-A2 restricted manner. ELISpot assays reveal that SARS-CoV-2-specific CD8+ T-cell responses in mild COVID-19 patients are significantly higher than in severe patients, whereas neutralizing antibody responses against SARS-CoV-2 virus significantly correlate with disease severity. Single-cell analyses of HLA-A2-restricted CD8+ T cells, which recognize highly conserved immunodominant SARS-CoV-2-specific epitopes, demonstrate divergent profiles in unvaccinated patients with mild versus severe disease. CD8+ T-cell types including cytotoxic KLRB1+ CD8 cells with innate-like T-cell signatures, IFNGhiID3hi memory cells and IL7R+ proliferative stem cell-like memory cells are preferentially observed in mild COVID-19, whereas distinct terminally-differentiated T-cell subsets are predominantly detected in severe COVID-19: highly activated FASLhi T-cell subsets and early-terminated or dysfunctional IL4R+ GATA3+ stem cell-like memory T-cell subset. In conclusion, our findings suggest that unique and contrasting SARS-CoV-2-specific CD8+ T-cell profiles may dictate COVID-19 severity. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=143 SRC="FIGDIR/small/632164v1_ufig1.gif" ALT="Figure 1"> View larger version (25K): org.highwire.dtl.DTLVardef@154796corg.highwire.dtl.DTLVardef@efca24org.highwire.dtl.DTLVardef@c01b9corg.highwire.dtl.DTLVardef@54ad83_HPS_FORMAT_FIGEXP M_FIG O_FLOATNOGraphical abstract.C_FLOATNO SARS-CoV-2 epitope-specific CD8+ T-cell subtypes associated with mild or severe COVID-19 patients. Potent memory CD8+ T-cell subtypes with gene signature in mild COVID-19 patients (upper) and dysfunctional CD8+ T-cell subtypes with gene signature in severe COVID-19 patients (lower). C_FIG

immunology↗

bioRxiv2024

An amphiregulin reporter mouse enables transcriptional and clonal expansion analysis of reparative lung Treg cells

Regulatory T (Treg) cells are known to play critical roles in tissue repair via provision of growth factors such as amphiregulin (Areg). Areg-producing Treg cells have previously been difficult to study because of an inability to isolate live Areg-producing cells. In this report, we created a novel reporter mouse to detect Areg expression in live cells (AregThy1.1). We employed influenza A and bleomycin models of lung damage to sort Areg-producing and -non-producing Treg cells for transcriptomic analyses. Single cell RNA-seq revealed distinct subpopulations of Treg cells and allowed transcriptomic comparisons of damage-induced populations. Single cell TCR sequencing showed that Treg cell clonal expansion is biased towards Areg-producing Treg cells, and largely occurs within damage-induced subgroups. Gene module analysis revealed functional divergence of Treg cells into immunosuppression-oriented and tissue repair-oriented groups, leading to identification of candidate receptors for induction of repair activity in Treg cells. We tested these using an ex vivo assay for Treg cell-mediated tissue repair, identifying 4-1BB agonism as a novel mechanism for reparative activity induction. Overall, we demonstrate that the AregThy1.1mouse is a promising tool for investigating tissue repair activity in leukocytes.

immunology↗

bioRxiv2024

Heparan sulfate regulates amphiregulin signaling towards reparative lung mesenchymal cells during influenza A infection

Amphiregulin (Areg), a growth factor produced by regulatory T (Treg) cells to facilitate tissue repair/regeneration, contains a heparan sulfate (HS) binding domain. How HS, a highly sulfated glycan subtype that alters growth factor signaling, influences Areg repair/regeneration functions is unclear. Here we report that inhibition of HS in various cell lines and primary lung mesenchymal cells (LMC) qualitatively alters downstream signaling and highlights the existence of HS-dependent vs. -independent Areg transcriptional signatures. Utilizing a panel of cell lines with targeted deletions in HS synthesis-related genes, we found that the presence of the glypican family of heparan sulfate proteoglycans is critical for Areg signaling and confirmed this dependency in primary LMC by siRNA-mediated knockdown. Furthermore, in the context of influenza A (IAV) infection in vivo, we found that an Areg-responsive subset of reparative LMC upregulate glypican-4 and HS. Conditional deletion of HS primarily within this LMC subset resulted in reduced blood oxygen saturation following infection with IAV, with no changes in viral load. Finally, we found that co-culture of HS-knockout LMC with IAV-induced Treg cells results in reduced LMC responses. Collectively, this study reveals the essentiality of HS on a specific lung mesenchymal population as a mediator of Treg cell-derived Areg reparative signaling during IAV infection.

immunology↗