Biology subjects

Fritz, J. H.

Publications and source records attributed to Fritz, J. H..

4 recordsLinked to original sources

bioRxiv2024

Immunometabolic analysis of primary murine Group 2 Innate Lymphoid Cells: a robust step-by-step approach

Group 2 Innate Lymphoid Cells (ILC2s) have recently been shown to exert key regulatory functions in innate and adaptive immune response networks that drive the establishment and progression of type 2 immunity and its associated pathologies. Although mainly tissue resident, ILC2s and their crosstalk within tissue microenvironments influences both local and systemic metabolism. In turn, the metabolic status shapes the diverse ILC2 phenotypes and effector functions. Hence, deciphering the metabolic networks of ILC2s is essential in understanding ILC2s roles in health as well as pathophysiologies. Here we detail a framework of experimental approaches to study key immunometabolic states of primary murine ILC2s and link them to phenotypes and functionality. Utilizing flow cytometry, Single Cell ENergetIc metabolism by ProfilIng Translation inhibition (SCENITH) as well as the Seahorse platform we provide a framework that allows in-depth analysis of cellular bioenergetic states to determine the immunometabolic wiring of ILC2. Linking immunometabolic states and networks to ILC2 phenotypes and effector functions will allow in-depth studies that assess the potential of novel pharmaceutics to alter ILC2 functionality in experimental and clinical settings.

immunology↗

bioRxiv2024

The transcription factor IRF-5 is essential for the metabolic rewiring of CD8 T cells during chronic infection

Numerous transcription factors are involved in promoting an intricate gene expression program that leads to CD8 T cell exhaustion. Here, we found that the transcription factor IRF-5 is involved in limiting functional exhaustion of CD8 T cells by regulating the cell cycle and contributing to sustaining the mitochondrial functions and oxidative phosphorylation during the chronic stage of LCMV Cl13 infection. CD8 T cells lacking IRF-5 display reduced survival capacity and show increased signs of functional exhaustion during the chronic stage of infection. IRF-5-deficiency also resulted in a severely defective lipid metabolism, in a faulty mitochondrial envelope, and in the reduced capacity to produce ATP. Additionally, we observed increased lipid peroxidation in CD8 T cells lacking IRF-5, when compared with WT cells. These findings identify IRF-5 as a pivotal regulator of the metabolic rewiring that occurs in CD8 T cells during the chronic stages of infection and highlight its role in protecting cells from cell death, possibly by lipid peroxidation. SummaryIRF-5 is critical for regulating mitochondrial functions and oxidative phosphorylation in CD8 T cells during chronic stages of LCMV Cl13 infection.

immunology↗

bioRxiv2022

Selection for immune evasion in SARS-CoV-2 revealed by high-resolution epitope mapping combined with genome sequence analysis

A deeper understanding of the molecular determinants that drive humoral responses to coronaviruses, and in particular severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), is critical for improving and developing diagnostics, therapies and vaccines. Moreover, viral mutations can change key antigens in a manner that alters the ability of the immune system to detect and clear infections. In this study, we exploit a deep serological profiling strategy coupled with an integrated, computational framework for the analysis of SARS-CoV-2 humoral immune responses of asymptomatic or recovered COVID-19-positive patients relative to COVID-19-negative patients. We made use of a novel high-density peptide array (HDPA) spanning the entire proteomes of SARS-CoV-2 and endemic human coronaviruses to rapidly identify B cell epitopes recognized by distinct antibody isotypes in patients blood sera. Using our integrated computational pipeline, we then evaluated the fine immunological properties of detected SARS-CoV-2 epitopes and relate them to their evolutionary and structural properties. While some epitopes are common across all CoVs, others are private to specific hCoVs. We also highlight the existence of hotspots of pre-existing immunity and identify a subset of cross-reactive epitopes that contributes to increasing the overall humoral immune response to SARS-CoV-2. Using a public dataset of over 38,000 viral genomes from the early phase of the pandemic, capturing both inter- and within-host genetic viral diversity, we determined the evolutionary profile of epitopes and the differences across proteins, waves and SARS-CoV-2 variants, which have important implications for genomic surveillance and vaccine design. Lastly, we show that mutations in Spike and Nucleocapsid epitopes are under stronger selection between than within patients, suggesting that most of the selective pressure for immune evasion occurs upon transmission between hosts.

genomics↗

bioRxiv2021

Critical roles of ICOS in controlling Foxp3-expressing T follicular cell subsets during early-stage germinal center reactions

ICOS is a T cell costimulatory receptor critical for Tfh cell generation and function. However, the role of ICOS in Tfr cell differentiation remains unclear. Using Foxp3-Cre-mediated ICOS knockout (ICOS FC) mice, we show that ICOS deficiency in Treg-lineage cells drastically reduces the number of Tfr cells during GC reactions but has a minimal impact on conventional Treg cells. Single-cell transcriptome analysis of Foxp3+ cells at an early stage of the GC reaction suggests that ICOS normally inhibits Klf2 expression to promote follicular features including Bcl6 upregulation. Further, ICOS costimulation promotes nuclear localization of NFAT2, a known driver of CXCR5 expression. Notably, ICOS FC mice had an unaltered overall GC B cell output but showed signs of expanded autoreactive B cells along with elevated autoantibody titers. Thus, our study demonstrates that ICOS costimulation is critical for Tfr cell differentiation and highlights the importance of Tfr cells in maintaining humoral immune tolerance during GC reactions.

immunology↗