Biology subjects

Pappalardo, J.

Publications and source records attributed to Pappalardo, J..

3 recordsLinked to original sources

bioRxiv2024

Systematic Analysis of Immune Changes after B-cell Depletion in Autoimmune Multiple Sclerosis

Multiple sclerosis (MS) is a complex genetically mediated autoimmune disease of the central nervous system where anti-CD20-mediated B cell depletion is remarkably effective in the treatment of early disease. While previous studies investigated the effect of B cell depletion on select immune cell subsets using flow cytometry-based methods, the therapeutic impact on patient immune landscape is unknown. In this study, we explored how a therapy-driven "in vivo perturbation" modulates the diverse immune landscape by measuring transcriptomic granularity with single-cell RNA sequencing (scRNAseq). We demonstrate that B cell depletion leads to cell type-specific changes in the abundance and function of CSF macrophages and peripheral blood monocytes. Specifically, a CSF-specific macrophage population with an anti-inflammatory transcriptomic signature and peripheral CD16+ monocytes increased in frequency post-B cell depletion. This was accompanied by increases in TNF messenger RNA and protein in monocytes post-B cell depletion, consistent with the finding that anti-TNF treatment exacerbates autoimmune activity in MS. In parallel, B cell depletion induced changes in peripheral CD4+ T cell populations, including increases in the frequency of TIGIT+ regulatory T cells and marked decreases in the frequency of myelin peptide loaded-tetramer binding CD4+ T cells. Collectively, this study provides an exhaustive transcriptomic map of immunological changes, revealing different mechanisms of action contributing to the high efficacy in B cell depletion treatment of MS.

immunology↗

bioRxiv2020

Co-stimulation with opposing macrophage polarization cues leads to orthogonal secretion programs in individual cells

Macrophages are innate immune cells that contribute to fighting infections, tissue repair, and maintaining tissue homeostasis. To enable such functional diversity, macrophages resolve potentially conflicting cues in the microenvironment via mechanisms that remain unclear. Here, we used single-cell RNA sequencing to explore how individual macrophages respond when co-stimulated with the inflammatory stimuli, LPS+IFN-{gamma}, and the resolving cytokine, IL-4. We found that co-stimulated macrophages displayed a distinct global transcriptional program. However, variable negative cross-regulation between some LPS+IFN-{gamma}- and IL-4-specific genes resulted in significant cell-to-cell heterogeneity in transcription. Interestingly, negative cross-regulation led to mutually exclusive expression of the T-cell-polarizing cytokines Il6 and Il12b versus the IL-4-associated factors Arg1 and Chil3 in single co-stimulated macrophages, and single-cell secretion measurements showed that these specialized functions were maintained for at least 48 hours. Overall, our study suggests that increasing functional diversity in the population is one strategy macrophages use to respond to conflicting environmental cues.

immunology↗

bioRxiv2018

Single cell RNA sequencing reveals a novel, microglia-like cell type in cerebrospinal fluid during virologically suppressed HIV

Central nervous system (CNS) immune activation in an important driver of neuronal injury during several neurodegenerative and neuroinflammatory diseases. During HIV infection, CNS immune activation is associated with high rates of neurocognitive impairment, even with sustained long-term suppressive antiretroviral therapy (ART). However, the cellular subsets that drive immune activation and neuronal damage in the CNS during HIV infection and neurological conditions remain unknown, in part because CNS cells are difficult to access in living humans. Using single cell RNA sequencing (scRNA-seq) on cerebrospinal fluid (CSF) and blood from adults with HIV, we identified a rare (<5% of cells) subset of myeloid cells in CSF presenting a gene expression signature consistent with neurodegenerative disease associated microglia. This highlights the power of scRNA-seq of CSF to identify rare CNS immune cell subsets that may perpetuate neuronal injury during HIV infection and other conditions.

immunology↗