Central memory T (T
) cells patrol lymph nodes and perform conventional memory responses on restimulation: proliferation, migration and differentiation into diverse T cell subsets while also ...self-renewing. Resident memory T (T
) cells are parked within single organs, share properties with terminal effectors and contribute to rapid host protection. We observed that reactivated T
cells rejoined the circulating pool. Epigenetic analyses revealed that T
cells align closely with conventional memory T cell populations, bearing little resemblance to recently activated effectors. Fully differentiated T
cells isolated from small intestine epithelium exhibited the potential to differentiate into T
cells, effector memory T cells and T
cells on recall. Ex-T
cells, former intestinal T
cells that rejoined the circulating pool, heritably maintained a predilection for homing back to their tissue of origin on subsequent reactivation and a heightened capacity to redifferentiate into T
cells. Thus, T
cells can rejoin the circulation but are advantaged to re-form local T
when called on.
Extracellular ATP (eATP) is an ancient 'danger signal' used by eukaryotes to detect cellular damage
. In mice and humans, the release of eATP during inflammation or injury stimulates both innate ...immune activation and chronic pain through the purinergic receptor P2RX7
. It is unclear, however, whether this pathway influences the generation of immunological memory, a hallmark of the adaptive immune system that constitutes the basis of vaccines and protective immunity against re-infection
. Here we show that P2RX7 is required for the establishment, maintenance and functionality of long-lived central and tissue-resident memory CD8
T cell populations in mice. By contrast, P2RX7 is not required for the generation of short-lived effector CD8
T cells. Mechanistically, P2RX7 promotes mitochondrial homeostasis and metabolic function in differentiating memory CD8
T cells, at least in part by inducing AMP-activated protein kinase. Pharmacological inhibitors of P2RX7 provoked dysregulated metabolism and differentiation of activated mouse and human CD8
T cells in vitro, and transient P2RX7 blockade in vivo ameliorated neuropathic pain but also compromised production of CD8
memory T cells. These findings show that activation of P2RX7 by eATP provides a common currency that both alerts the nervous and immune system to tissue damage, and promotes the metabolic fitness and survival of the most durable and functionally relevant memory CD8
T cell populations.
This study examines the extent to which memory CD4
T cells share immunosurveillance strategies with CD8
resident memory T cells (T
). After acute viral infection, memory CD4
T cells predominantly ...used residence to survey nonlymphoid tissues, albeit not as stringently as observed for CD8
T cells. In contrast, memory CD4
T cells were more likely to be resident within lymphoid organs than CD8
T cells. Migration properties of memory-phenotype CD4
T cells in non-SPF parabionts were similar, generalizing these results to diverse infections and conditions. CD4
and CD8
T
shared overlapping transcriptional signatures and location-specific features, such as granzyme B expression in the small intestine, revealing tissue-specific and migration property-specific, in addition to lineage-specific, differentiation programs. Functionally, mucosal CD4
T
reactivation locally triggered both chemokine expression and broad immune cell activation. Thus, residence provides a dominant mechanism for regionalizing CD4
T cell immunity, and location enforces shared transcriptional, phenotypic, and functional properties with CD8
T cells.
Differentiated somatic mammalian cells putatively exhibit species-specific division limits that impede cancer but may constrain lifespans
. To provide immunity, transiently stimulated CD8
T cells ...undergo unusually rapid bursts of numerous cell divisions, and then form quiescent long-lived memory cells that remain poised to reproliferate following subsequent immunological challenges. Here we addressed whether T cells are intrinsically constrained by chronological or cell-division limits. We activated mouse T cells in vivo using acute heterologous prime-boost-boost vaccinations
, transferred expanded cells to new mice, and then repeated this process iteratively. Over 10 years (greatly exceeding the mouse lifespan)
and 51 successive immunizations, T cells remained competent to respond to vaccination. Cells required sufficient rest between stimulation events. Despite demonstrating the potential to expand the starting population at least 10
-fold, cells did not show loss of proliferation control and results were not due to contamination with young cells. Persistent stimulation by chronic infections or cancer can cause T cell proliferative senescence, functional exhaustion and death
. We found that although iterative acute stimulations also induced sustained expression and epigenetic remodelling of common exhaustion markers (including PD1, which is also known as PDCD1, and TOX) in the cells, they could still proliferate, execute antimicrobial functions and form quiescent memory cells. These observations provide a model to better understand memory cell differentiation, exhaustion, cancer and ageing, and show that functionally competent T cells can retain the potential for extraordinary population expansion and longevity well beyond their organismal lifespan.
Angiosarcoma is a highly aggressive cancer of blood vessel-forming cells with few effective treatment options and high patient mortality. It is both rare and heterogenous, making large, well-powered ...genomic studies nearly impossible. Dogs commonly suffer from a similar cancer, called hemangiosarcoma, with breeds like the golden retriever carrying heritable genetic factors that put them at high risk. If the clinical similarity of canine hemangiosarcoma and human angiosarcoma reflects shared genomic etiology, dogs could be a critically needed model for advancing angiosarcoma research. We assessed the genomic landscape of canine hemangiosarcoma via whole-exome sequencing (47 golden retriever hemangiosarcomas) and RNA sequencing (74 hemangiosarcomas from multiple breeds). Somatic coding mutations occurred most frequently in the tumor suppressor
(59.6% of cases) as well as two genes in the PI3K pathway: the oncogene
(29.8%) and its regulatory subunit
(8.5%). The predominant mutational signature was the age-associated deamination of cytosine to thymine. As reported in human angiosarcoma,
was recurrently deleted and
, and
recurrently gained. We compared the canine data to human data recently released by The Angiosarcoma Project, and found many of the same genes and pathways significantly enriched for somatic mutations, particularly in breast and visceral angiosarcomas. Canine hemangiosarcoma closely models the genomic landscape of human angiosarcoma of the breast and viscera, and is a powerful tool for investigating the pathogenesis of this devastating disease. IMPLICATIONS: We characterize the genomic landscape of canine hemangiosarcoma and demonstrate its similarity to human angiosarcoma.
Deregulation of microRNA (miRNA) transcript levels has been observed in many types of tumors including osteosarcoma. Molecular pathways regulated by differentially expressed miRNAs may contribute to ...the heterogeneous tumor behaviors observed in naturally occurring cancers. Thus, tumor-associated miRNA expression may provide informative biomarkers for disease outcome and metastatic potential in osteosarcoma patients. We showed previously that clusters of miRNAs at the 14q32 locus are downregulated in human osteosarcoma.
Human and canine osteosarcoma patient's samples with clinical follow-up data were used in this study. We used bioinformatics and comparative genomics approaches to identify miRNA based prognostic biomarkers in osteosarcoma. Kaplan-Meier survival curves and Whitney Mann U tests were conducted for validating the statistical significance.
Here we show that an inverse correlation exists between aggressive tumor behavior (increased metastatic potential and accelerated time to death) and the residual expression of 14q32 miRNAs (using miR-382 as a representative of 14q32 miRNAs) in a series of clinically annotated samples from human osteosarcoma patients. We also show a comparable decrease in expression of orthologous 14q32 miRNAs in canine osteosarcoma samples, with conservation of the inverse correlation between aggressive behavior and expression of orthologous miRNA miR-134 and miR-544.
We conclude that downregulation of 14q32 miRNA expression is an evolutionarily conserved mechanism that contributes to the biological behavior of osteosarcoma, and that quantification of representative transcripts from this family, such as miR-382, miR-134, and miR-544, provide prognostic and predictive markers that can assist in the management of patients with this disease.
The oral mucosa is a frontline for microbial exposure and juxtaposes several unique tissues and mechanical structures. Based on parabiotic surgery of mice receiving systemic viral infections or ...co-housing with microbially diverse pet shop mice, we report that the oral mucosa harbors CD8+ CD103+ resident memory T cells (TRM), which locally survey tissues without recirculating. Oral antigen re-encounter during the effector phase of immune responses potentiated TRM establishment within tongue, gums, palate, and cheek. Upon reactivation, oral TRM triggered changes in somatosensory and innate immune gene expression. We developed in vivo methods for depleting CD103+ TRM while sparing CD103neg TRM and recirculating cells. This revealed that CD103+ TRM were responsible for inducing local gene expression changes. Oral TRM putatively protected against local viral infection. This study provides methods for generating, assessing, and in vivo depleting oral TRM, documents their distribution throughout the oral mucosa, and provides evidence that TRM confer protection and trigger responses in oral physiology and innate immunity.
Humans experience frequent respiratory infections. Immunology and vaccinology studies in mice are typically performed in naive specific pathogen-free animals responding to their very first ...respiratory challenge. We found that the first respiratory infection induces lifelong enlargement of the lung-draining mediastinal lymph nodes (medLNs). Furthermore, infection-experienced medLNs supported better naive T cell surveillance and effector responses to new unrelated infections that exhibited more biased accumulation and memory establishment within the lung. Moreover, we observed that weight loss induced by influenza infection was substantially reduced in mice that had recovered from a previous unrelated respiratory viral challenge. These data show that the lack of infectious history and corresponding medLN hypoplasia in specific pathogen-free mice alter their immune response to lung infections. Preclinical vaccination and immunology studies should consider the previous infectious experience of the model organism.
Osteosarcomas are sarcomas of the bone, derived from osteoblasts or their precursors, with a high propensity to metastasize. Osteosarcoma is associated with massive genomic instability, making it ...problematic to identify driver genes using human tumors or prototypical mouse models, many of which involve loss of Trp53 function. To identify the genes driving osteosarcoma development and metastasis, we performed a Sleeping Beauty (SB) transposon-based forward genetic screen in mice with and without somatic loss of Trp53. Common insertion site (CIS) analysis of 119 primary tumors and 134 metastatic nodules identified 232 sites associated with osteosarcoma development and 43 sites associated with metastasis, respectively. Analysis of CIS-associated genes identified numerous known and new osteosarcoma-associated genes enriched in the ErbB, PI3K-AKT-mTOR and MAPK signaling pathways. Lastly, we identified several oncogenes involved in axon guidance, including Sema4d and Sema6d, which we functionally validated as oncogenes in human osteosarcoma.
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