While treatment for burn injury has improved significantly over the past few decades, reducing mortality and improving patient outcomes, recent evidence has revealed that burn injury is associated ...with a number of secondary pathologies, many of which arise long after the initial injury has healed. Population studies have linked burn injury with increased risk of cancer, cardiovascular disease, nervous system disorders, diabetes, musculoskeletal disorders, gastrointestinal disease, infections, anxiety and depression. The wide range of secondary pathologies indicates that burn can cause sustained disruption of homeostasis, presenting new challenges for post-burn care. Understanding burn injury as a chronic disease will improve patient care, providing evidence for better long-term support and monitoring of patients. Through focused research into the mechanisms underpinning long-term dysfunction, a better understanding of burn injury pathology may help with the development of preventative treatments to improve long-term health outcomes. The review will outline evidence of long-term health effects, possible mechanisms linking burn injury to long-term health and current research into burns as a chronic disease.
Skin trauma has many different causes including incision, blunt force, and burn. All of these traumas trigger an immune response. However, it is currently unclear whether the immune response is ...specific to the etiology of the injury. This study was established to determine whether the immune response to excision and burn injury of equivalent extent was the same. Using a mouse model of a full-thickness 19 mm diameter excision or 19 mm diameter full-thickness burn injury, we examined the innate immune response at the level of serum cytokine induction, whole-blood lymphocyte populations, dendritic cell function/phenotype, and the ensuing adaptive immune responses of CD4 and CD8 T-cell populations. Strikingly, both the innate and adaptive immune system responses differed between the burn and excision injuries. Acute cytokine induction was faster and different in profile to that of excision injury, leading to changes in systemic monocyte and neutrophil levels. Differences in the immune profile between burn and excision were also noted up to day 84 post injury, suggesting that the etiology of injury leads to sustained changes in the response. This may in part underlie clinical observations of differences in patient morbidity and mortality in response to different skin injury types.
Burn injury initiates an acute inflammatory response that subsequently drives wound repair. However, acute disruption to the immune response is also common, leading to susceptibility to sepsis and ...increased morbidity and mortality. Despite increased understanding of the impact of burn injury on the immune system in the acute phase, little is known about long-term consequences of burn injury on immune function. This study was established to determine whether burn injury has long-term clinical impacts on patients' immune responses.
Using a population-based retrospective longitudinal study and linked hospital morbidity and death data from Western Australia, comparative rates of hospitalisation for respiratory infections in burn patients and a non-injured comparator cohort were assessed. In addition, a mouse model of non-severe burn injury was also used in which viral respiratory infection was induced at 4 weeks post-injury using a mouse modified version of the Influenza A virus (H3NN; A/mem/71-a).
The burn injured cohort contained 14893 adult patients from 1980-2012 after removal of those patients with evidence of smoke inhalation or injury to the respiratory tract. During the study follow-up study a total of 2,884 and 2,625 respiratory infection hospital admissions for the burn and uninjured cohorts, respectively, were identified. After adjusting for covariates, the burn cohort experienced significantly elevated admission rates for influenza and viral pneumonia (IRR, 95%CI: 1.73, 1.27-2.36), bacterial pneumonia (IRR, 95%CI: 2.05, 1.85-2.27) and for other types of upper and lower respiratory infections (IRR, 95% CI: 2.38, 2.09-2.71). In the mouse study an increased viral titre was observed after burn injury, accompanied by a reduced CD8 response and increased NK and NKT cells in the draining lymph nodes. This data suggests burn patients are at long-term increased risk of infection due to sustained modulation of the immune response.
Abstract
The biological determinants of the response to immune checkpoint blockade (ICB) in cancer remain incompletely understood. Little is known about dynamic biological events that underpin ...therapeutic efficacy due to the inability to frequently sample tumours in patients. Here, we map the transcriptional profiles of 144 responding and non-responding tumours within two mouse models at four time points during ICB. We find that responding tumours display on/fast-off kinetics of type-I-interferon (IFN) signaling. Phenocopying of this kinetics using time-dependent sequential dosing of recombinant IFNs and neutralizing antibodies markedly improves ICB efficacy, but only when IFNβ is targeted, not IFNα. We identify Ly6C
+
/CD11b
+
inflammatory monocytes as the primary source of IFNβ and find that active type-I-IFN signaling in tumour-infiltrating inflammatory monocytes is associated with T cell expansion in patients treated with ICB. Together, our results suggest that on/fast-off modulation of IFNβ signaling is critical to the therapeutic response to ICB, which can be exploited to drive clinical outcomes towards response.
Abstract
A growing body of evidence supports the concept of a systemic response to non-severe thermal trauma. This provokes an immunosuppressed state that predisposes paediatric patients to poor ...recovery and increased risk of secondary morbidity. In this study, to understand the long-term systemic effects of non-severe burns in children, targeted mass spectrometry assays for biogenic amines and tryptophan metabolites were performed on plasma collected from child burn patients at least three years post injury and compared to age and sex matched non-burn (healthy) controls. A panel of 12 metabolites, including urea cycle intermediates, aromatic amino acids and quinolinic acid were present in significantly higher concentrations in children with previous burn injury. Correlation analysis of metabolite levels to previously measured cytokine levels indicated the presence of multiple cytokine-metabolite associations in the burn injury participants that were absent from the healthy controls. These data suggest that there is a sustained immunometabolic imprint of non-severe burn trauma, potentially linked to long-term immune changes that may contribute to the poor long-term health outcomes observed in children after burn injury.
Immune checkpoint therapy (ICT) results in durable responses in individuals with some cancers, but not all patients respond to treatment. ICT improves CD8
cytotoxic T lymphocyte (CTL) function, but ...changes in tumor antigen-specific CTLs post-ICT that correlate with successful responses have not been well characterized. Here, we studied murine tumor models with dichotomous responses to ICT. We tracked tumor antigen-specific CTL frequencies and phenotype before and after ICT in responding and non-responding animals. Tumor antigen-specific CTLs increased within tumor and draining lymph nodes after ICT, and exhibited an effector memory-like phenotype, expressing IL-7R (CD127), KLRG1, T-bet, and granzyme B. Responding tumors exhibited higher infiltration of effector memory tumor antigen-specific CTLs, but lower frequencies of regulatory T cells compared to non-responders. Tumor antigen-specific CTLs persisted in responding animals and formed memory responses against tumor antigens. Our results suggest that increased effector memory tumor antigen-specific CTLs, in the presence of reduced immunosuppression within tumors is part of a successful ICT response. Temporal and nuanced analysis of T cell subsets provides a potential new source of immune based biomarkers for response to ICT.
The therapeutic response to immune checkpoint blockade (ICB) is highly variable, not only between different cancers but also between patients with the same cancer type. The biological mechanisms ...underlying these differences in response are incompletely understood. Identifying correlates in patient tumor samples is challenging because of genetic and environmental variability. Murine studies usually compare different tumor models or treatments, introducing potential confounding variables. This protocol describes bilateral murine tumor models, derived from syngeneic cancer cell lines, that display a symmetrical yet dichotomous response to ICB. These models enable detailed analysis of whole tumors in a highly homogeneous background, combined with knowledge of the therapeutic outcome within a few weeks, and could potentially be used for mechanistic studies using other (immuno-)therapies. We discuss key considerations and describe how to use two cell lines as fully optimized models. We discuss experimental details, including proper inoculation technique to achieve symmetry and one-sided surgical tumor removal, which takes only 5 min per mouse. Furthermore, we outline the preparation of bulk tissue or single-cell suspensions for downstream analyses such as bulk RNA-seq, immunohistochemistry, single-cell RNA-seq and flow cytometry.
Epidemiological studies have demonstrated that survivors of acute burn trauma are at long-term increased risk of developing a range of morbidities. The mechanisms underlying this increased risk ...remain unknown. This study aimed to determine whether burn injury leads to sustained immune dysfunction that may underpin long-term morbidity. Plasma and peripheral blood mononuclear cells were collected from 36 pediatric burn survivors >3 years after a non-severe burn injury (<10% total body surface area) and from age/sex-matched non-injured controls. Circulating cytokine and vaccine antibody levels were assessed using multiplex immunoassays and cell profiles compared using a panel of 40 metal-conjugated antibodies and mass cytometry. TNF-α (1.31-fold change from controls), IL-2 (1.18-fold), IL-7 (1.63-fold), and IFN-γ (1.18-fold) were all significantly elevated in the burn cohort. Additionally, burn survivors demonstrated diminished antibody responses to the diphtheria, tetanus, and pertussis vaccine antigens. Comparisons between groups using unsupervised clustering identified differences in proportions of clusters within T-cells, B-cells and myeloid cells. Manual gating confirmed increased memory T-regulatory and central memory CD4+ T-cells, with altered expression of T-cell, B-cell, and dendritic cell markers. Conclusions: This study demonstrates a lasting change to the immune profile of pediatric burn survivors, and highlights the need for further research into post-burn immune suppression and regulation.
Over 400 million people worldwide are living with a rare disease. Next Generation Sequencing (NGS) identifies potential disease causative genetic variants. However, many are identified as variants of ...uncertain significance (VUS) and require functional laboratory validation to determine pathogenicity, and this creates major diagnostic delays.
In this study we test a rapid genetic variant assessment pipeline using CRISPR homology directed repair to introduce single nucleotide variants into inducible pluripotent stem cells (iPSCs), followed by neuronal disease modelling, and functional genomics on amplicon and RNA sequencing, to determine cellular changes to support patient diagnosis and identify disease mechanism.
As proof-of-principle, we investigated an EHMT1 (Euchromatin histone methyltransferase 1; EHMT1 c.3430C > T; p.Gln1144*) genetic variant pathogenic for Kleefstra syndrome and determined changes in gene expression during neuronal progenitor cell differentiation. This pipeline rapidly identified Kleefstra syndrome in genetic variant cells compared to healthy cells, and revealed novel findings potentially implicating the key transcription factors REST and SP1 in disease pathogenesis.
The study pipeline is a rapid, robust method for genetic variant assessment that will support rare diseases patient diagnosis. The results also provide valuable information on genome wide perturbations key to disease mechanism that can be targeted for drug treatments.
PDF
