Concept: Major histocompatibility complex
It is widely accepted that aging is accompanied by remodelling of the immune system including thymic atrophy and increased frequency of senescent T cells, leading to immune compromise. However, physical activity, which influences immunity but declines dramatically with age, is not considered in this literature. We assessed immune profiles in 125 adults (55-79 years) who had maintained a high level of physical activity (cycling) for much of their adult lives, 75 age-matched older adults and 55 young adults not involved in regular exercise. The frequency of naïve T cells and recent thymic emigrants (RTE) were both higher in cyclists compared with inactive elders, and RTE frequency in cyclists was no different to young adults. Compared with their less active counterparts, the cyclists had significantly higher serum levels of the thymoprotective cytokine IL-7 and lower IL-6, which promotes thymic atrophy. Cyclists also showed additional evidence of reduced immunesenescence, namely lower Th17 polarization and higher B regulatory cell frequency than inactive elders. Physical activity did not protect against all aspects of immunesenescence: CD28-veCD57+vesenescent CD8 T-cell frequency did not differ between cyclists and inactive elders. We conclude that many features of immunesenescence may be driven by reduced physical activity with age.
Sunlight has important biological effects in human skin. Ultraviolet (UV) light striking the epidermis catalyzes the synthesis of Vitamin D and triggers melanin production. Although a causative element in skin cancers, sunlight is also associated with positive health outcomes including reduced incidences of autoimmune diseases and cancers. The mechanisms, however, by which light affects immune function remain unclear. Here we describe direct photon sensing in human and mouse T lymphocytes, a cell-type highly abundant in skin. Blue light irradiation at low doses (<300 mJ cm(-2)) triggers synthesis of hydrogen peroxide (H2O2) in T cells revealed by the genetically encoded reporter HyPerRed. In turn, H2O2 activates a Src kinase/phospholipase C-γ1 (PLC-γ1) signaling pathway and Ca(2+) mobilization. Pharmacologic inhibition or genetic disruption of Lck kinase, PLC-γ1 or the T cell receptor complex inhibits light-evoked Ca(2+) transients. Notably, both light and H2O2 enhance T-cell motility in a Lck-dependent manner. Thus, T lymphocytes possess intrinsic photosensitivity and this property may enhance their motility in skin.
Background Patients with diffuse large B-cell lymphoma or follicular lymphoma that is refractory to or that relapses after immunochemotherapy and transplantation have a poor prognosis. High response rates have been reported with the use of T cells modified by chimeric antigen receptor (CAR) that target CD19 in B-cell cancers, although data regarding B-cell lymphomas are limited. Methods We used autologous T cells that express a CD19-directed CAR (CTL019) to treat patients with diffuse large B-cell lymphoma or follicular lymphoma that had relapsed or was refractory to previous treatments. Patients were monitored for response to treatment, toxic effects, the expansion and persistence of CTL019 cells in vivo, and immune recovery. Results A total of 28 adult patients with lymphoma received CTL019 cells, and 18 of 28 had a response (64%; 95% confidence interval [CI], 44 to 81). Complete remission occurred in 6 of 14 patients with diffuse large B-cell lymphoma (43%; 95% CI, 18 to 71) and 10 of 14 patients with follicular lymphoma (71%; 95% CI, 42 to 92). CTL019 cells proliferated in vivo and were detectable in the blood and bone marrow of patients who had a response and patients who did not have a response. Sustained remissions were achieved, and at a median follow-up of 28.6 months, 86% of patients with diffuse large B-cell lymphoma who had a response (95% CI, 33 to 98) and 89% of patients with follicular lymphoma who had a response (95% CI, 43 to 98) had maintained the response. Severe cytokine-release syndrome occurred in 5 patients (18%). Serious encephalopathy occurred in 3 patients (11%); 2 cases were self-limiting and 1 case was fatal. All patients in complete remission by 6 months remained in remission at 7.7 to 37.9 months (median, 29.3 months) after induction, with a sustained reappearance of B cells in 8 of 16 patients and with improvement in levels of IgG in 4 of 10 patients and of IgM in 6 of 10 patients at 6 months or later and in levels of IgA in 3 of 10 patients at 18 months or later. Conclusions CTL019 cells can be effective in the treatment of relapsed or refractory diffuse large B-cell lymphoma and follicular lymphoma. High rates of durable remission were observed, with recovery of B cells and immunoglobulins in some patients. Transient encephalopathy developed in approximately one in three patients and severe cytokine-release syndrome developed in one in five patients. (Funded by Novartis and others; ClinicalTrials.gov number, NCT02030834 .).
Devil facial tumour disease (DFTD) is a fatal contagious cancer that has decimated Tasmanian devil populations. The tumour has spread without invoking immune responses, possibly due to low levels of Major Histocompatibility Complex (MHC) diversity in Tasmanian devils. Animals from a region in north-western Tasmania have lower infection rates than those in the east of the state. This area is a genetic transition zone between sub-populations, with individuals from north-western Tasmania displaying greater diversity than eastern devils at MHC genes, primarily through MHC class I gene copy number variation. Here we test the hypothesis that animals that remain healthy and tumour free show predictable differences at MHC loci compared to animals that develop the disease.
Human leukocyte antigen (HLA) typing at the allelic level can in theory be achieved using whole exome sequencing (exome-seq) data with no added cost but has been hindered by its computational challenge. We developed ATHLATES, a program that applies assembly, allele identification and allelic pair inference to short read sequences, and applied it to data from Illumina platforms. In 15 data sets with adequate coverage for HLA-A, -B, -C, -DRB1 and -DQB1 genes, ATHLATES correctly reported 74 out of 75 allelic pairs with an overall concordance rate of 99% compared with conventional typing. This novel approach should be broadly applicable to research and clinical laboratories.
It is generally accepted that the success of immunotherapy depends on the presence of tumor-specific CD8+ cytotoxic T cells and the modulation of the tumor environment. In this study, we validated mRNA encoding soluble factors as a tool to modulate the tumor microenvironment to potentiate infiltration of tumor-specific T cells. Intratumoral delivery of mRNA encoding a fusion protein consisting of interferon-β and the ectodomain of the transforming growth factor-β receptor II, referred to as Fβ2, showed therapeutic potential. The treatment efficacy was dependent on CD8+ T cells and could be improved through blockade of PD-1/PD-L1 interactions. In vitro studies revealed that administration of Fβ2 to tumor cells resulted in a reduced proliferation and increased expression of MHC I but also PD-L1. Importantly, Fβ2 enhanced the antigen presenting capacity of dendritic cells, whilst reducing the suppressive activity of myeloid-derived suppressor cells. In conclusion, these data suggest that intratumoral delivery of mRNA encoding soluble proteins, such as Fβ2, can modulate the tumor microenvironment, leading to effective antitumor T cell responses, which can be further potentiated through combination therapy.
Recent events have made it clear that potentially pandemic strains of influenza regularly pose a threat to human populations. Therefore, it is essential that we develop better strategies to enhance vaccine design and evaluation to predict those that will be poor responders to vaccination and to identify those that are at particular risk of disease-associated complications following infection. Animal models have revealed the discrete functions that CD4 T cells play in developing immune response and to influenza immunity. However, humans have a complex immunological history with influenza through periodic infection and vaccination with seasonal variants, leading to the establishment of heterogeneous memory populations of CD4 T cells that participate in subsequent responses. The continual evolution of the influenza-specific CD4 T cell repertoire involves both specificity and function and overlays other restrictions on CD4 T cell activity derived from viral antigen handling and MHC class II:peptide epitope display. Together, these complexities in the influenza-specific CD4 T cell repertoire constitute a formidable obstacle to predicting protective immune response to potentially pandemic strains of influenza and in devising optimal vaccine strategies to potentiate these responses. We suggest that more precise efforts to identify and enumerate both the positive and negative contributors within the CD4 T cell compartment will aid significantly in the achievement of these goals.
We identified a polyclonal CD8+ T-cell response against mutant KRAS G12D in tumor-infiltrating lymphocytes obtained from a patient with metastatic colorectal cancer. We observed objective regression of all seven lung metastases after the infusion of approximately 1.11×10(11) HLA-C*08:02-restricted tumor-infiltrating lymphocytes that were composed of four different T-cell clonotypes that specifically targeted KRAS G12D. However, one of these lesions had progressed on evaluation 9 months after therapy. The lesion was resected and found to have lost the chromosome 6 haplotype encoding the HLA-C*08:02 class I major histocompatibility complex (MHC) molecule. The loss of expression of this molecule provided a direct mechanism of tumor immune evasion. Thus, the infusion of CD8+ cells targeting mutant KRAS mediated effective antitumor immunotherapy against a cancer that expressed mutant KRAS G12D and HLA-C*08:02.
Major histocompatibility (MHC) class II molecules are strongly associated with many autoimmune disorders. In type 1 diabetes, the DQ8 molecule is common, confers significant disease risk and is involved in disease pathogenesis. We hypothesized blocking DQ8 antigen presentation would provide therapeutic benefit by preventing recognition of self-peptides by pathogenic T cells. We used the crystal structure of DQ8 to select drug-like small molecules predicted to bind structural pockets in the MHC antigen-binding cleft. A limited number of the predicted compounds inhibited DQ8 antigen presentation in vitro with one compound preventing insulin autoantibody production and delaying diabetes onset in an animal model of spontaneous autoimmune diabetes. An existing drug of similar structure, methyldopa, specifically blocked DQ8 in recent-onset patients with type 1 diabetes along with reducing inflammatory T cell responses toward insulin, highlighting the relevance of blocking disease-specific MHC class II antigen presentation to treat autoimmunity.
After mapping out the molecular mechanisms of T-cell antigen recognition, regulation, and function in the 1980s and 1990s, immunologist James P. Allison hypothesized that blocking negative immune regulators (checkpoints) would give the human immune system the power to fight cancer. His testing of this hypothesis in preclinical models led to the clinical development of a new generation of active agents for cancer treatment. In some subgroups of patients, unleashing native immune-system cells to fight cancer now provides a realistic chance of long-term remission. For this seminal work, Allison, a professor at the M.D. Anderson Cancer Center in Houston, has won . . .