Respiratory viral infections remain a leading cause of morbidity and mortality. Using a murine model of human metapneumovirus, we identified recruitment of a C1q-expressing inflammatory monocyte population concomitant with viral clearance by adaptive immune cells. Genetic ablation of C1q led to reduced CD8 T-cell function. Production of C1q by a myeloid lineage was necessary to enhance CD8 T-cell function. Activated and dividing CD8 T cells expressed a C1q receptor, gC1qR. Perturbation of gC1qR signaling led to altered CD8 T-cell IFN-γ production, metabolic capacity, and cell proliferation. Autopsy specimens from fatal respiratory viral infections in children exhibited diffuse production of C1q by an interstitial population. Humans with severe coronavirus disease (COVID-19) infection also exhibited upregulation of gC1qR on activated and rapidly dividing CD8 T cells. Collectively, these studies implicate C1q production from monocytes as a critical regulator of CD8 T-cell function following respiratory viral infection.
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http://dx.doi.org/10.1165/rcmb.2024-0004OC | DOI Listing |
JCI Insight
January 2025
CNRS UMR 5164, INSERM ERL 1303, ImmunoConcEpT, University of Bordeaux, Bordeaux, France.
CD8+ T cells are critical for immune protection against severe COVID-19 during acute infection with SARS-CoV-2. However, the induction of antiviral CD8+ T cell responses varies substantially among infected people, and a better understanding of the mechanisms that underlie such immune heterogeneity is required for pandemic preparedness and risk stratification. In this study, we analyzed SARS-CoV-2-specific CD4+ and CD8+ T cell responses in relation to age, clinical status, and inflammation among patients infected primarily during the initial wave of the pandemic in France or Japan.
View Article and Find Full Text PDFImmunohorizons
January 2025
Center for Virus Research, Chao Family Comprehensive Cancer Center, Department of Molecular Biology and Biochemistry, Charlie Dunlop School of Biological Sciences, University of California, Irvine, Irvine, CA, United States.
The differentiation and functionality of virus-specific T cells during acute viral infections are crucial for establishing long-term protective immunity. While numerous molecular regulators impacting T cell responses have been uncovered, the role of cellular prion proteins (PrPc) remains underexplored. Here, we investigated the impact of PrPc deficiency on the differentiation and function of virus-specific T cells using the lymphocytic choriomeningitis virus (LCMV) Armstrong acute infection model.
View Article and Find Full Text PDFJCI Insight
January 2025
Department of Hepatobiliary Pancreatic Surgery.
T cells targeting a KRAS mutation can induce durable tumor regression in some patients with metastatic epithelial cancer. It is unknown whether T cells targeting mutant KRAS that are capable of killing tumor cells can be identified from peripheral blood of patients with pancreatic cancer. We developed an in vitro stimulation approach and identified HLA-A*11:01-restricted KRAS G12V-reactive CD8+ T cells and HLA-DRB1*15:01-restricted KRAS G12V-reactive CD4+ T cells from peripheral blood of 2 out of 6 HLA-A*11:01-positive patients with pancreatic cancer whose tumors expressed KRAS G12V.
View Article and Find Full Text PDFFront Immunol
January 2025
Neuroimmunology Unit, Santa Lucia Foundation IRCCS, Rome, Italy.
Introduction: Acute COVID-19 infection causes significant alterations in the innate and adaptive immune systems. While most individuals recover naturally, some develop long COVID (LC) syndrome, marked by persistent or new symptoms weeks to months after SARS-CoV-2 infection. Despite its prevalence, there are no clinical tests to distinguish LC patients from those fully recovered.
View Article and Find Full Text PDFFront Immunol
January 2025
Department of Pharmacology and Toxicology, Faculty of Veterinary Medicine, University of Warmia and Mazury in Olsztyn, Olsztyn, Poland.
Introduction: Mycophenolate mofetil (MMF) is an immunosuppressive drug administered in the management of both autoimmune diseases and organ transplantation. The main aims of the study were: (a) to obtain information regarding the safety of using MMF in respect of its effect on normal T and B cells in lymphoid tissues; (b) to investigate whether the generation of inducible Foxp3-expressing regulatory T cells (Treg) might constitute additional mechanisms underlying the immunosuppressive properties of MMF.
Methods: The effect of MMF ( studies) and its active metabolite, mycophenolic acid, ( studies) on murine CD4 and CD8 T cells as well as B cells was determined, regarding: (a) absolute count, proliferation and apoptosis of these cells ( studies); (b) absolute count of these cells in the head and neck lymph nodes, mesenteric lymph nodes and the spleen ( studies).
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