Expression of CD39 on Activated T Cells Impairs their Survival in Older Individuals

The presence of cytotoxic CD4 and exhausted-like CD8+ T-cells is a signature of active tuberculosis

Chronic infections induce CD4+ T-cells with cytotoxic functions (CD4 CTLs); at present, it is still unknown whether latent tuberculosis (LTB) and active tuberculosis (ATB) induce CD4 CTLs. Plasma and cells from four patient groups-uninfected contact (UC), LTB, and ATB (divided as sensitive [DS-TB]- or resistant [DR-TB]-drug)-were evaluated by flow cytometry, q-PCR, and proteomics. The data showed that ATB patients had an increased frequency of CD4+ T-cells and a decreased frequency of CD8+ T-cells. The latter displays an exhausted-like profile characterized by CD39, CD279, and TIM-3 expression. ATB had a high frequency of CD4 + perforin+ cells, suggesting a CD4 CTL profile. The expression (at the transcriptional level) of granzyme A, granzyme B, granulysin, and perforin, as well as the genes T-bet (Tbx21) and NKG2D (Klrk1), in enriched CD4+ T-cells, confirmed the cytotoxic signature of CD4+ T-cells during ATB (which was stronger in DS-TB than in DR-TB). Moreover, proteomic analysis revealed the presence of HSP70 (in DS-TB) and annexin A5 (in DR-TB), which are molecules that have been associated with favoring the CD4 CTL profile. Finally, we found that lipids from Mycobacterium tuberculosis increased the presence of CD4 CTLs in DR-TB patients. Our data suggest that ATB is characterized by exhausted-like CD8+ T-cells, which, together with a specific microenvironment, favor the presence of CD4 CTLs.

Gluten-Free Diet Induces Rapid Changes in Phenotype and Survival Properties of Gluten-Specific T Cells in Celiac Disease

BACKGROUND & AIMS

The treatment of celiac disease (CeD) with gluten-free diet (GFD) normalizes gut inflammation and disease-specific antibodies. CeD patients have HLA-restricted, gluten-specific T cells persisting in the blood and gut even after decades of GFD, which are reactivated and disease driving upon gluten exposure. Our aim was to examine the transition of activated gluten-specific T cells into a pool of persisting memory T cells concurrent with normalization of clinically relevant biomarkers during the first year of treatment.

METHODS

We followed 17 CeD patients during their initial GFD year, leading to disease remission. We assessed activation and frequency of gluten-specific CD4+ blood and gut T cells with HLA-DQ2.5:gluten tetramers and flow cytometry, disease-specific serology, histology, and symptom scores. We assessed gluten-specific blood T cells within the first 3 weeks of GFD in 6 patients and serology in an additional 9 patients.

RESULTS

Gluten-specific CD4+ T cells peaked in blood at day 14 while up-regulating Bcl-2 and down-regulating Ki-67 and then decreased in frequency within 10 weeks of GFD. CD38, ICOS, HLA-DR, and Ki-67 decreased in gluten-specific cells within 3 days. PD-1, CD39, and OX40 expression persisted even after 12 months. IgA-transglutaminase 2 decreased significantly within 4 weeks.

CONCLUSIONS

GFD induces rapid changes in the phenotype and number of gluten-specific CD4+ blood T cells, including a peak of nonproliferating, nonapoptotic cells at day 14. Subsequent alterations in T-cell phenotype associate with the quiescent but chronic nature of treated CeD. The rapid changes affecting gluten-specific T cells and disease-specific antibodies offer opportunities for clinical trials aiming at developing nondietary treatments for patients with newly diagnosed CeD.

The aged microenvironment impairs BCL6 and CD40L induction in CD4+ T follicular helper cell differentiation

Weakened germinal center responses by the aged immune system result in diminished immunity against pathogens and reduced efficacy of vaccines. Prolonged contacts between activated B cells and CD4+ T cells are crucial to germinal center formation and T follicular helper cell (Tfh) differentiation, but it is unclear how aging impacts the quality of this interaction. Peptide immunization confirmed that aged mice have decreased expansion of antigen-specific germinal center B cells and reduced antibody titers. Furthermore, aging was associated with accumulated Tfh cells, even in naïve mice. Despite increased numbers, aged Tfh had reduced expression of master transcription factor BCL6 and increased expression of the ectonucleotidase CD39. In vitro activation revealed that proliferative capacity was maintained in aged CD4+ T cells, but not the costimulatory molecule CD40L. When activated in vitro by aged antigen-presenting cells, young CD4+ naïve T cells generated reduced numbers of activated cells with upregulated CD40L. To determine the contribution of cell-extrinsic influences on antigen-specific Tfh induction, young, antigen-specific B and CD4+ T cells were adoptively transferred into aged hosts prior to peptide immunization. Transferred cells had reduced expansion and differentiation into germinal center B cell and Tfh and reduced antigen-specific antibody titers when compared to young hosts. Young CD4+ T cells transferred aged hosts differentiated into Tfh cells with reduced PD-1 and BCL6 expression, and increased CD39 expression, though they maintained their mitochondrial capacity. These results highlight the role of the lymphoid microenvironment in modulating CD4+ T cell differentiation, which contributes to impaired establishment and maintenance of germinal centers.

Relationship between immune cells and diabetic nephropathy: a Mendelian randomization study

OBJECTIVE

Although previous studies have suggested potential correlations between immunocytes and diabetic nephropathy (DN), the causal correlations between them remain unclarified. In this study, we employed Mendelian randomization (MR) to analyze the potential causative correlations between immune 731 cells and DN.

METHODS

We used the Genome-Wide Association Studies (GWAS) database to aggregate signatures of immune cells and DN from European and East Asian populations. Single-nucleotide polymorphisms (SNPs) were used as instrumental variables. MR analysis was conducted using Mendelian randomization-Egger (MR-Egger) regression and the random-effects inverse-variance weighted (IVW) method.

RESULTS

A total of 3,571 SNPs were included as instrumental variables. The MR-Egger regression model indicated no genetic pleiotropy (P = 0.6284). The results of the IVW method indicated a statistically significant causal relationship between immune cell HLA-DR on CD14-CD16- (P = 0.029), CD45RA-CD28-CD8 + T cell% T cells (P = 0.0278), CD11c on myeloid dendritic cells (P = 0.0352), HLA-DR on CD14+ monocytes (P < 0.001), CD27 on CD24 + CD27 + B cells (P = 0.0334), CD27 on IgD + CD24 + B cells (P = 0.0137), CD4 on CD39 + CD4 + T cells (P = 0.0347), CD28 on CD39 + CD4 + T cells (P = 0.0414), CD39 on CD39 + CD4 + T cells (P = 0.0426), and DN. Additionally, there was no heterogeneity in SNPs related HLA-DR on CD14-CD16-cells and DN(I2 = 32%, Cochran's Q = 2.9476, P = 0.2291). Moreover, leave-one-out analysis showed a causal correlation between HLA-DR on CD14-CD16- cells and DN.

CONCLUSION

Higher expression of immune cell HLA-DR on CD14-CD16- cells may indicate a lower risk of DN.

Regulatory role of CD39 and CD73 in tumor immunity

CD39 is the rate-limiting enzyme for the molecular signal cascade leading to the generation of ADP and adenosine monophosphate (AMP). In conjunction with CD73, CD39 converts adenosine triphosphate (ATP) to ADP and AMP, which leads to the accumulation of immunosuppressive adenosine in the tumor microenvironment. This review focuses on the role of CD39 and CD73 in immune response and malignant progression, including the expression of CD39 within the tumor microenvironment and its relationship to immune effector cells, and its role in antigen presentation. The role of CD39- and CD73-targeting therapeutics and cancer-directed clinical trials investigating CD39 modulation are also explored.

CD39 is expressed on functional effector and tissue resident memory CD8+ T cells

The ecto-ATPase CD39 is expressed on exhausted CD8+ T cells in chronic viral infection and has been proposed as a marker of tumor-specific CD8+ T cells in cancer, but the role of CD39 in an effector and memory T cell response has not been clearly defined. We report that CD39 is expressed on antigen-specific CD8+ short-lived effector cells (SLECs), while it's co-ecto-enzyme, CD73, is found on memory precursor effector cells (MPEC) in vivo . Inhibition of CD39 enzymatic activity during in vitro T cell priming enhances MPEC differentiation in vivo after transfer and infection. The enriched MPEC phenotype is associated with enhanced tissue resident memory (T RM ) establishment in the brain and salivary gland following an acute intranasal viral infection, suggesting that CD39 ATPase activity plays a role in memory CD8+ T cell differentiation. We also show that CD39 is expressed on human and murine T RM across several non-lymphoid tissues and melanoma, while CD73 is expressed on both circulating and resident memory subsets in mice. In contrast to exhausted CD39+ T cells in chronic infection, CD39+ T RM are fully functional when stimulated ex vivo with cognate antigen. This work further expands the identity of CD39 beyond a T cell exhaustion marker.

CD73 as a T cell dysfunction marker predicting cardiovascular and infection events in patients undergoing hemodialysis

BACKGROUND

T cell dysfunction observed in patients undergoing hemodialysis (HD) has been linked to an extremely high morbidity of cardiovascular events (CVEs) and infections. The cell-surface 5'-nucleotidase CD73 sets the balance between pro-inflammatory nucleotides and anti-inflammatory adenosine.

METHODS

A total of 395 patients who had been receiving HD for at least six months were evaluated for proportions of CD73+ cells in both the CD4+ T cell and CD8+ T cell compartment and followed for one year to document CVEs and infections. Differences in the proportions of CD73-expressingT cells between healthy controls and patients undergoing HD were compared. The relationship between CD73+ T cells and clinical outcomes was analyzed using the Kaplan-Meier curve and Cox regression.

RESULTS

HD was significantly related to a lower fraction of CD4+CD73+ T cells. In patients on HD, lower proportions of CD4+ CD73+T cells and CD8+ CD73+T cells were both associated with systemic inflammation and T cell terminal differentiation. More importantly, a lower CD4+CD73+T cell ratio independently predicted CVEs and infection in these patients.

CONCLUSION

We identified CD73 as a T cell dysfunction marker predicting cardiovascular and infection events in patients undergoing HD, which provides a potential target in future studies of uremia-related immune dysfunction.

Immunological Landscapes in Lung Transplantation: Insights from T Cell Profiling in BAL and PBMC

Lung transplant recipients frequently encounter immune-related complications, including chronic lung allograft dysfunction (CLAD). Monitoring immune cells within the lung microenvironment is pivotal for optimizing post-transplant outcomes. This study examined the proportion of T cell subsets in paired bronchoalveolar lavage (BAL) and peripheral PBMC comparing healthy (n = 4) and lung transplantation patients (n = 6, no CLAD and n = 14 CLAD) using 14-color flow cytometry. CD4+ T cell proportions were reduced in CD3 cells in both PBMC and BAL, and positive correlations were discerned between T cell populations in peripheral PBMC and BAL, suggesting the prospect of employing less invasive PBMC sampling as a means of monitoring lung T cells. Furthermore, regulatory T cells (Tregs) were enriched in BAL when compared to peripheral PBMC for transplant recipients. A parallel positive correlation emerged between Treg proportions in BAL and peripheral PBMC, underscoring potential avenues for monitoring lung Tregs. Finally, the most promising biomarker was the Teff (CD8+Granzyme B+)-Treg ratio, which was higher in both the PBMC and BAL of transplant recipients compared to healthy individuals, and increased in the patients with CLAD compared to no CLAD and healthy patients. Conclusions: Distinct T cell profiles in BAL and peripheral PBMC underscore the significance of localized immune monitoring in lung transplantation. The Teff (CD8+granzyme B+)-Treg ratio, particularly within the context of CLAD, emerges as a promising blood and BAL biomarker reflective of inflammation and transplant-related complications. These findings emphasize the imperative need for personalized immune monitoring strategies that tailored to address the unique immunological milieu in post-transplant lungs.

Surface protein and functional analyses identify CD4+CD39+ TCR αβ+ and activated TCR Vδ1+ cells with distinct pro-inflammatory functions in Crohn's disease lesions

Crohn's disease (CD) is a chronic immune-mediated disorder of the gastrointestinal tract. Extensive screening studies have revealed the accumulation of immune cell subsets with unique plasticity and immunoregulatory properties in patients with CD. We performed phenotypic and functional studies on inflamed and non-inflamed bioptic tissue to investigate the presence of distinct T cells in the intestinal mucosa of CD patients. We analysed hundreds of surface molecules expressed on cells isolated from the intestinal tissue of CD patients using anti-CD45 mAbs-based barcoding. A gene ontology enrichment analysis showed that proteins that regulate the activation of T cells were the most enriched group. We, therefore, designed T-cell focused multicolour flow-cytometry panels and performed clustering analysis which revealed an accumulation of activated TEM CD4+CD39+ T cells producing IL-17 and IL-21 and increased frequency of terminally differentiated TCR Vδ1+ cells producing TNF-α and IFN-γ in inflamed tissue of CD patients. The different functional capacities of CD4+ and TCR Vδ1+ cells in CD lesions indicate their non-overlapping contribution to inflammation. The abnormally high number of terminally differentiated TCR Vδ1+ cells suggests that they are continuously activated in inflamed tissue, making them a potential target for novel therapies.

Immunological features of ESRD patients undergoing hemodialysis of various ages

AIMS

To investigate the immunological characteristics of hemodialysis (HD) patients with end-stage renal disease (ESRD) of various ages, and the impact of age-related immune alterations on these patients, with a focus on peripheral T cells.

METHODS

From September 2016 to September 2019, HD patients were enrolled and followed prospectively for 3 years. Patients were divided into three groups based on their ages: < 45, 45 to 64, and ≥ 65. The distribution of T cell subsets in different age groups was investigated and compared. The effects of altered T cell subsets on overall survival were also investigated.

RESULTS

A total of 371 HD patients were enrolled. The reduced number of naive CD8+ T cells (P < 0.001) and increased number of EMRA CD8+ T cells (P = 0.024) were independently associated with the advanced age among all T cell subsets studied. Patient survival may be affected by numerical changes in naive CD8+ T cells. However, when HD patients were < 45 or ≥ 65 years, the reduction had no significant impact on survival. Only in HD patients aged 45 to 64 years, the number of naïve CD8+ T cells found to be insufficient but not deficient, identified as an independent predictor of poor survival.

CONCLUSIONS

The most significant age-related immune change in HD patients was a decrease in peripheral naive CD8+ T cells, which was an independent predictor of 3-year overall survival in HD patients aged 45 ~ 64 years.

T cell fate decisions during memory cell generation with aging

The defense against infectious diseases, either through natural immunity or after vaccinations, relies on the generation and maintenance of protective T cell memory. Naïve T cells are at the center of memory T cell generation during primary responses. Upon activation, they undergo a complex, highly regulated differentiation process towards different functional states. Naïve T cells maintained into older age have undergone epigenetic adaptations that influence their fate decisions during differentiation. We review age-sensitive, molecular pathways and gene regulatory networks that bias naïve T cell differentiation towards effector cell generation at the expense of memory and Tfh cells. As a result, T cell differentiation in older adults is associated with release of bioactive waste products into the microenvironment, higher stress sensitivity as well as skewing towards pro-inflammatory signatures and shorter life spans. These maladaptations not only contribute to poor vaccine responses in older adults but also fuel a more inflammatory state.

Age-dependent changes in T follicular helper cells shape the humoral immune response to vaccination

Vaccination is an excellent strategy to limit the morbidity and mortality associated with infectious disease. Vaccination creates protective, long-lived antibody-mediated immunity by inducing the germinal centre response, an intricate immune reaction that produces memory B cells and long-lived antibody-secreting plasma cells that provide protection against (re)infection. The magnitude and quality of the germinal centre response declines with age, contributing to poor vaccine-induced immunity in older individuals. T follicular helper cells are essential for the formation and function of the germinal centre response. This review will discuss how age-dependent changes in T follicular helper cells influence the germinal centre response, and the evidence that age-dependent changes need not be a barrier to successful vaccination in the later years of life.

Heterogeneity of memory T cells in aging

Immune memory is a requisite and remarkable property of the immune system and is the biological foundation of the success of vaccinations in reducing morbidity from infectious diseases. Some vaccines and infections induce long-lasting protection, but immunity to other vaccines and particularly in older adults rarely persists over long time periods. Failed induction of an immune response and accelerated waning of immune memory both contribute to the immuno-compromised state of the older population. Here we review how T cell memory is influenced by age. T cell memory is maintained by a dynamic population of T cells that are heterogeneous in their kinetic parameters under homeostatic condition and their function. Durability of T cell memory can be influenced not only by the loss of a clonal progeny, but also by broader changes in the composition of functional states and transition of T cells to a dysfunctional state. Genome-wide single cell studies on total T cells have started to provide insights on the influence of age on cell heterogeneity over time. The most striking findings were a trend to progressive effector differentiation and the activation of pro-inflammatory pathways, including the emergence of CD4+ and CD8+ cytotoxic subsets. Genome-wide data on antigen-specific memory T cells are currently limited but can be expected to provide insights on how changes in T cell subset heterogeneity and transcriptome relate to durability of immune protection.

Cancer-associated fibroblasts drive CXCL13 production in activated T cells via TGF-beta

Introduction

Tumour-reactive T cells producing the B-cell attractant chemokine CXCL13, in solid tumours, promote development of tertiary lymphoid structures (TLS) and are associated with improved prognosis and responsiveness to checkpoint immunotherapy. Cancer associated fibroblasts are the dominant stromal cell type in non-small cell lung cancer (NSCLC) where they co-localise with T cells and can influence T cell activation and exhaustion. We questioned whether CAF directly promote CXCL13-production during T cell activation.

Methods

We characterised surface markers, cytokine production and transcription factor expression in CXCL13-producing T cells in NSCLC tumours and paired non-cancerous lung samples using flow cytometry. We then assessed the influence of human NSCLC-derived primary CAF lines on T cells from healthy donors and NSCLC patients during activation in vitro measuring CXCL13 production and expression of cell-surface markers and transcription factors by flow cytometry.

Results

CAFs significantly increased the production of CXCL13 by both CD4+ and CD8+ T cells. CAF-induced CXCL13-producing cells lacked expression of CXCR5 and BCL6 and displayed a T peripheral helper cell phenotype. Furthermore, we demonstrate CXCL13 production by T cells is induced by TGF-β and limited by IL-2. CAF provide TGF-β during T cell activation and reduce availability of IL-2 both directly (by reducing the capacity for IL-2 production) and indirectly, by expanding a population of activated Treg. Inhibition of TGF-β signalling prevented both CAF-driven upregulation of CXCL13 and Treg expansion.

Discussion

Promoting CXCL13 production represents a newly described immune-regulatory function of CAF with the potential to shape the immune infiltrate of the tumour microenvironment both by altering the effector-function of tumour infiltrating T-cells and their capacity to attract B cells and promote TLS formation.

CD39 (ENTPD1) in tumors: a potential therapeutic target and prognostic biomarker

As a regulator of the dynamic balance between immune-activated extracellular ATP and immunosuppressive adenosine, CD39 ectonucleotidase impairs the ability of immune cells to exert anticancer immunity and plays an important role in the immune escape of tumor cells within the tumor microenvironment. In addition, CD39 has been studied in cancer patients to evaluate the prognosis, the efficacy of immunotherapy (e.g., PD-1 blockade) and the prediction of recurrence. This article reviews the importance of CD39 in tumor immunology, summarizes the preclinical evidence on targeting CD39 to treat tumors and focuses on the potential of CD39 as a biomarker to evaluate the prognosis and the response to immune checkpoint inhibitors in tumors.

Hilaire C, Reddy A, Kim J, Pinsky DJ, Murthy VL, Sutton NR. Circulating Ectonucleotidases Signal Impaired Myocardial Perfusion at Rest and Stress

Background Ectonucleotidases maintain vascular homeostasis by metabolizing extracellular nucleotides, modulating inflammation and thrombosis, and potentially, myocardial flow through adenosine generation. Evidence implicates dysfunction or deficiency of ectonucleotidases CD39 or CD73 in human disease; the utility of measuring levels of circulating ectonucleotidases as plasma biomarkers of coronary artery dysfunction or disease has not been previously reported. Methods and Results A total of 529 individuals undergoing clinically indicated positron emission tomography stress testing between 2015 and 2019 were enrolled in this single-center retrospective analysis. Baseline demographics, clinical data, nuclear stress test, and coronary artery calcium score variables were collected, as well as a blood sample. CD39 and CD73 levels were assessed as binary (detectable, undetectable) or continuous variables using ELISAs. Plasma CD39 was detectable in 24% of White and 8% of Black study participants (P=0.02). Of the clinical history variables examined, ectonucleotidase levels were most strongly associated with underlying liver disease and not other traditional coronary artery disease risk factors. Intriguingly, detection of circulating ectonucleotidase was inversely associated with stress myocardial blood flow (2.3±0.8 mL/min per g versus 2.7 mL/min per g±1.1 for detectable versus undetectable CD39 levels, P<0.001) and global myocardial flow reserve (Pearson correlation between myocardial flow reserve and log(CD73) -0.19, P<0.001). A subanalysis showed these differences held true independent of liver disease. Conclusions Vasodilatory adenosine is the expected product of local ectonucleotidase activity, yet these data support an inverse relationship between plasma ectonucleotidases, stress myocardial blood flow (CD39), and myocardial flow reserve (CD73). These findings support the conclusion that plasma levels of ectonucleotidases, which may be shed from the endothelial surface, contribute to reduced stress myocardial blood flow and myocardial flow reserve.

CISH impairs lysosomal function in activated T cells resulting in mitochondrial DNA release and inflammaging

Chronic systemic inflammation is one of the hallmarks of the aging immune system. Here we show that activated T cells from older adults contribute to inflammaging by releasing mitochondrial DNA (mtDNA) into their environment due to an increased expression of the cytokine-inducible SH2-containing protein (CISH). CISH targets ATP6V1A, an essential component of the proton pump V-ATPase, for proteasomal degradation, thereby impairing lysosomal function. Impaired lysosomal activity caused intracellular accumulation of multivesicular bodies and amphisomes and the export of their cargos, including mtDNA. CISH silencing in T cells from older adults restored lysosomal activity and prevented amphisomal release. In antigen-specific responses in vivo, CISH-deficient CD4+ T cells released less mtDNA and induced fewer inflammatory cytokines. Attenuating CISH expression may present a promising strategy to reduce inflammation in an immune response of older individuals.

T cell aging and Alzheimer’s disease

The brain has long been considered an immune-privileged organ due to the presence of the blood-brain barrier (BBB). However, recent discoveries have revealed the underestimated role of T cells in the brain through the meningeal lymphatic system. Age is the primary risk factor for Alzheimer’s disease (AD), resulting in marked age-dependent changes in T cells. Manipulating peripheral T cell immune response has been shown to impact AD, but the relationship between T cell aging and AD remains poorly understood. Given the limited success of targeting amyloid beta (Aβ) and the growing evidence of T cells’ involvement in non-lymphoid organ aging, a deeper understanding of the relationship between T cells and AD in the context of aging is crucial for advancing therapeutic progress. In this review, we comprehensively examine existing studies on T cells and AD and offer an integrated perspective on their interconnections in the context of aging. This understanding can inform the development of new interventions to prevent or treat AD.

Role of T Cells in the Pathogenesis of Rheumatoid Arthritis: Focus on Immunometabolism Dysfunctions

Evidence demonstrated that metabolic-associated T cell abnormalities could be detected in the early stage of RA development. In this context, molecular evaluations have revealed changes in metabolic pathways, leading to the aggressive phenotype of RA T cells. A growing list of genes is downregulated or upregulated in RA T cells, and most of these genes with abnormal expression fall into the category of metabolic pathways. It has been shown that RA T cells shunt glucose towards the pentose phosphate pathway (PPP), which is associated with a high level of nicotinamide adenine dinucleotide phosphate (NADPH) and intermediate molecules. An increased level of NADPH inhibits ATM activation and thereby increases the proliferation capabilities of the RA T cells. Defects in the DNA repair nuclease MRE11A cause failures in repairing mitochondrial DNA, resulting in inhibiting the fatty acid oxidation pathway and further elevated cytoplasmic lipid droplets. Accumulated lipid droplets employ to generate lipid membranes for the cell building program and are also used to form the front-end membrane ruffles that are accomplices with invasive phenotypes of RA T cells. Metabolic pathway involvement in RA pathogenesis expands the pathogenic concept of the disease beyond the common view of autoimmunity triggered by autoantigen recognition. Increased knowledge about metabolic pathways' implications in RA pathogenesis paves the way to understand better the environment/gene interactions and host/microbiota interactions and introduce potential therapeutic approaches. This review summarized emerging data about the roles of T cells in RA pathogenesis with a focus on immunometabolism dysfunctions and how these metabolic alterations can affect the disease process.

Aging-associated HELIOS deficiency in naive CD4+ T cells alters chromatin remodeling and promotes effector cell responses

Immune aging combines cellular defects in adaptive immunity with the activation of pathways causing a low-inflammatory state. Here we examined the influence of age on the kinetic changes in the epigenomic and transcriptional landscape induced by T cell receptor (TCR) stimulation in naive CD4+ T cells. Despite attenuated TCR signaling in older adults, TCR activation accelerated remodeling of the epigenome and induced transcription factor networks favoring effector cell differentiation. We identified increased phosphorylation of STAT5, at least in part due to aberrant IL-2 receptor and lower HELIOS expression, as upstream regulators. Human HELIOS-deficient, naive CD4+ T cells, when transferred into human-synovium-mouse chimeras, infiltrated tissues more efficiently. Inhibition of IL-2 or STAT5 activity in T cell responses of older adults restored the epigenetic response pattern to the one seen in young adults. In summary, reduced HELIOS expression in non-regulatory naive CD4+ T cells in older adults directs T cell fate decisions toward inflammatory effector cells that infiltrate tissue.

The DARC Side of Inflamm-Aging: Duffy Antigen Receptor for Chemokines (DARC/ACKR1) as a Potential Biomarker of Aging, Immunosenescence, and Breast Oncogenesis among High-Risk Subpopulations

The proclivity of certain pre-malignant and pre-invasive breast lesions to progress while others do not continues to perplex clinicians. Clinicians remain at a crossroads with effectively managing the high-risk patient subpopulation owing to the paucity of biomarkers that can adequately risk-stratify and inform clinical decisions that circumvent unnecessary administration of cytotoxic and invasive treatments. The immune system mounts the most important line of defense against tumorigenesis and progression. Unfortunately, this defense declines or "ages" over time-a phenomenon known as immunosenescence. This results in "inflamm-aging" or the excessive infiltration of pro-inflammatory chemokines, which alters the leukocyte composition of the tissue microenvironment, and concomitant immunoediting of these leukocytes to diminish their antitumor immune functions. Collectively, these effects can foster the sequelae of neoplastic transformation and progression. The erythrocyte cell antigen, Duffy antigen receptor for chemokines(DARC/ACKR1), binds and internalizes chemokines to maintain homeostatic levels and modulate leukocyte trafficking. A negative DARC status is highly prevalent among subpopulations of West African genetic ancestry, who are at higher risk of developing breast cancer and disease progression at a younger age. However, the role of DARC in accelerated inflamm-aging and malignant transformation remains underexplored. Herein, we review compelling evidence suggesting that DARC may be protective against inflamm-aging and, therefore, reduce the risk of a high-risk lesion progressing to malignancy. We also discuss evidence supporting that immunotherapeutic intervention-based on DARC status-among high-risk subpopulations may evade malignant transformation and progression. A closer look into this unique role of DARC could glean deeper insight into the immune response profile of individual high-risk patients and their predisposition to progress as well as guide the administration of more "cyto-friendly" immunotherapeutic intervention to potentially "turn back the clock" on inflamm-aging-mediated oncogenesis and progression.

The influence of three-dimensional structure on naïve T cell homeostasis and aging

A breakdown in cellular homeostasis is thought to drive naïve T cell aging, however the link between naïve T cell homeostasis and aging in humans is poorly understood. To better address this, we developed a lymphoid organoid system that maintains resting naïve T cells for more than 2 weeks, in conjunction with high CD45RA expression. Deep phenotypic characterization of naïve T cells across age identified reduced CD45RA density as a hallmark of aging. A conversion from CD45RA^high naive cells to a CD45RA^low phenotype was reproduced within our organoid system by structural breakdown, but not by stromal cell aging or reduced lymphocyte density, and mediated by alternative CD45 splicing. Together, these data suggest that external influences within the lymph node microenvironment may cause phenotypic conversion of naïve T cells in older adults.

How Can We Improve the Vaccination Response in Older People? Part II: Targeting Immunosenescence of Adaptive Immunity Cells

The number of people that are 65 years old or older has been increasing due to the improvement in medicine and public health. However, this trend is not accompanied by an increase in quality of life, and this population is vulnerable to most illnesses, especially to infectious diseases. Vaccination is the best strategy to prevent this fact, but older people present a less efficient response, as their immune system is weaker due mainly to a phenomenon known as immunosenescence. The adaptive immune system is constituted by two types of lymphocytes, T and B cells, and the function and fitness of these cell populations are affected during ageing. Here, we review the impact of ageing on T and B cells and discuss the approaches that have been described or proposed to modulate and reverse the decline of the ageing adaptive immune system.

Targeting purine metabolism in ovarian cancer

Purine, an abundant substrate in organisms, is a critical raw material for cell proliferation and an important factor for immune regulation. The purine de novo pathway and salvage pathway are tightly regulated by multiple enzymes, and dysfunction in these enzymes leads to excessive cell proliferation and immune imbalance that result in tumor progression. Maintaining the homeostasis of purine pools is an effective way to control cell growth and tumor evolution, and exploiting purine metabolism to suppress tumors suggests interesting directions for future research. In this review, we describe the process of purine metabolism and summarize the role and potential therapeutic effects of the major purine-metabolizing enzymes in ovarian cancer, including CD39, CD73, adenosine deaminase, adenylate kinase, hypoxanthine guanine phosphoribosyltransferase, inosine monophosphate dehydrogenase, purine nucleoside phosphorylase, dihydrofolate reductase and 5,10-methylenetetrahydrofolate reductase. Purinergic signaling is also described. We then provide an overview of the application of purine antimetabolites, comprising 6-thioguanine, 6-mercaptopurine, methotrexate, fludarabine and clopidogrel. Finally, we discuss the current challenges and future opportunities for targeting purine metabolism in the treatment-relevant cellular mechanisms of ovarian cancer.

Alterations in CD39/CD73 axis of T cells associated with COVID-19 severity

Purinergic signaling modulates immune function and is involved in the immunopathogenesis of several viral infections. This study aimed to investigate alterations in purinergic pathways in coronavirus disease 2019 (COVID‐19) patients. Mild and severe COVID‐19 patients had lower extracellular adenosine triphosphate and adenosine levels, and higher cytokines than healthy controls. Mild COVID‐19 patients presented lower frequencies of CD4⁺CD25⁺CD39⁺ (activated/memory regulatory T cell [mTreg]) and increased frequencies of high‐differentiated (CD27⁻CD28⁻) CD8⁺ T cells compared with healthy controls. Severe COVID‐19 patients also showed higher frequencies of CD4⁺CD39⁺, CD4⁺CD25⁻CD39⁺ (memory T effector cell), and high‐differentiated CD8⁺ T cells (CD27⁻CD28⁻), and diminished frequencies of CD4⁺CD73⁺, CD4⁺CD25⁺CD39⁺ mTreg cell, CD8⁺CD73⁺, and low‐differentiated CD8⁺ T cells (CD27⁺CD28⁺) in the blood in relation to mild COVID‐19 patients and controls. Moreover, severe COVID‐19 patients presented higher expression of PD‐1 on low‐differentiated CD8⁺ T cells. Both severe and mild COVID‐19 patients presented higher frequencies of CD4⁺Annexin‐V⁺ and CD8⁺Annexin‐V⁺ T cells, indicating increased T‐cell apoptosis. Plasma samples collected from severe COVID‐19 patients were able to decrease the expression of CD73 on CD4⁺ and CD8⁺ T cells of a healthy donor. Interestingly, the in vitro incubation of peripheral blood mononuclear cell from severe COVID‐19 patients with adenosine reduced the nuclear factor‐κB activation in T cells and monocytes. Together, these data add new knowledge to the COVID‐19 immunopathology through purinergic regulation.

Prostate Cancer Survivors Present Long-Term, Residual Systemic Immune Alterations

Simple Summary

The development of cancer is very often accompanied by systemic immune alterations which can be further aggravated by major anti-cancer therapies. However, there is very little known about how long these alterations persist in patients successfully cured of cancer. The aim of our work was to investigate how cancer and radiotherapy as major anti-cancer treatment modalities impact the immune system long after the successful treatment of a tumor. We investigated prostate cancer patients treated with a special form of radiotherapy (low-dose rate brachytherapy) often used for the treatment of prostate cancer and followed a wide range of immune parameters at regular intervals up to 3 years after the start of the treatment. Our results showed that some immune alterations did not recover after the treatment of the disease, on the contrary, they persisted, and in some cases got even worse. Further studies are needed to explain the causes and the potential long-term consequences of these alterations.

Abstract

Background: The development of cancer and anti-tumor therapies can lead to systemic immune alterations but little is known about how long immune dysfunction persists in cancer survivors. Methods: We followed changes in the cellular immune parameters of prostate cancer patients with good prognostic criteria treated with low dose rate brachytherapy before and up to 3 years after the initiation of therapy. Results: Patients before therapy had a reduced CD4+ T cell pool and increased regulatory T cell fraction and these alterations persisted or got amplified during the 36-month follow-up. A significant decrease in the total NK cell number and a redistribution of the circulating NK cells in favor of a less functional anergic subpopulation was seen in patients before therapy but tumor regression led to the regeneration of the NK cell pool and functional integrity. The fraction of lymphoid DCs was increased in patients both before therapy and throughout the whole follow-up. Increased PDGF-AA, BB, CCL5 and CXCL5 levels were measured in patients before treatment but protein levels rapidly normalized. Conclusions: while NK cell dysfunction recovered, long-term, residual alterations persisted in the adaptive and partly in the innate immune system.

IL-4 prevents adenosine-mediated immunoregulation by inhibiting CD39 expression

The ectonucleotidase CD39 functions as a checkpoint in purinergic signaling on effector T cells. By depleting eATP and initiating the generation of adenosine, it impairs memory cell development and contributes to T cell exhaustion, thereby causing defective tumor immunity and deficient T cell responses in older adults who have increased CD39 expression. Tuning enzymatic activity of CD39 and targeting the transcriptional regulation of ENTPD1 can be used to modulate purinergic signaling. Here, we describe that STAT6 phosphorylation downstream of IL-4 signaling represses CD39 expression on activated T cells by inducing a transcription factor network including GATA3, GFI1, and YY1. GATA3 suppresses ENTPD1 transcription through prevention of RUNX3 recruitment to the ENTPD1 promoter. Conversely, pharmacological STAT6 inhibition decreases T cell effector functions via increased CD39 expression, resulting in the defective signaling of P2X receptors by ATP and stimulation of A2A receptors by adenosine. Our studies suggest that inhibiting the STAT6 pathway to increase CD39 expression has the potential to treat autoimmune disease while stimulation of the pathway could improve T cell immunity.

Combined High-Throughput Approaches Reveal the Signals Driven by Skin and Blood Environments and Define the Tumor Heterogeneity in Sézary Syndrome

Simple Summary

Sézary syndrome (SS) is a leukemic and incurable variant of cutaneous T-cell lymphoma characterized by the accumulation of neoplastic CD4+ lymphocytes in the blood, lymph nodes, and skin. With the exception of allogenic transplantation, no curative chance is available to treat SS, and it is a priority to find new therapies that target SS cells within all disease compartments. This review aims to summarize the more recent analyses conducted on skin- and blood-derived SS cells concurrently obtained from the same SS patients. The results highlighted that skin-SS cells were more active/proliferating with respect to matched blood SS cells that instead appeared quiescent. These data shed the light on the possibility to treat blood and skin SS cells with different compounds, respectively. Moreover, this review recaps the more recent findings on the heterogeneity of circulating SS cells that presented a series of novel markers that could improve diagnosis, prognosis and therapy of this lymphoma.

Abstract

Sézary syndrome (SS) is an aggressive variant of cutaneous t-cell lymphoma characterized by the accumulation of neoplastic CD4+ lymphocytes—the SS cells—mainly in blood, lymph nodes, and skin. The tumor spread pattern of SS makes this lymphoma a unique model of disease that allows a concurrent blood and skin sampling for analysis. This review summarizes the recent studies highlighting the transcriptional programs triggered by the crosstalk between SS cells and blood–skin microenvironments. Emerging data proved that skin-derived SS cells show consistently higher activation/proliferation rates, mainly driven by T-cell receptor signaling with respect to matched blood SS cells that instead appear quiescent. Biochemical analyses also demonstrated an hyperactivation of PI3K/AKT/mTOR, a targetable pathway by multiple inhibitors currently in clinical trials, in skin SS cells compared with a paired blood counterpart. These results indicated that active and quiescent SS cells coexist in this lymphoma, and that they could be respectively treated with different therapeutics. Finally, this review underlines the more recent discoveries into the heterogeneity of circulating SS cells, highlighting a series of novel markers that could improve the diagnosis and that represent novel therapeutic targets (GPR15, PTPN13, KLRB1, and ITGB1) as well as new genetic markers (PD-1 and CD39) able to stratify SS patients for disease aggressiveness.

T-Cell Aging-Associated Phenotypes in Autoimmune Disease

The aging process causes profound restructuring of the host immune system, typically associated with declining host protection against cancer and infection. In the case of T cells, aging leads to the accumulation of a diverse set of T-cell aging-associated phenotypes (TASP), some of which have been implicated in driving tissue inflammation in autoimmune diseases. T cell aging as a risk determinant for autoimmunity is exemplified in two classical autoimmune conditions: rheumatoid arthritis (RA), a disease predominantly affecting postmenopausal women, and giant cell arteritis (GCA), an inflammatory vasculopathy exclusively occurring during the 6th-9th decade of life. Pathogenic T cells in RA emerge as a consequence of premature immune aging. They have shortening and fragility of telomeric DNA ends and instability of mitochondrial DNA. As a result, they produce a distinct profile of metabolites, disproportionally expand their endoplasmic reticulum (ER) membranes and release excess amounts of pro-inflammatory effector cytokines. Characteristically, they are tissue invasive, activate the inflammasome and die a pyroptotic death. Patients with GCA expand pathogenic CD4⁺ T cells due to aberrant expression of the co-stimulatory receptor NOTCH1 and the failure of the PD-1/PD-L1 immune checkpoint. In addition, GCA patients lose anti-inflammatory Treg cells, promoting tissue-destructive granulomatous vasculitis. In summary, emerging data identify T cell aging as a risk factor for autoimmune disease and directly link TASPs to the breakdown of T cell tolerance and T-cell-induced tissue inflammation.

Immune phenotype of the CD4+ T cells in the aged lymphoid organs and lacrimal glands

Aging is associated with a massive infiltration of T lymphocytes in the lacrimal gland. Here, we aimed to characterize the immune phenotype of aged CD4⁺ T cells in this tissue as compared with lymphoid organs. To perform this, we sorted regulatory T cells (Tregs, CD4⁺CD25⁺GITR⁺) and non-Tregs (CD4⁺CD25^negGITR^neg) in lymphoid organs from female C57BL/6J mice and subjected these cells to an immunology NanoString® panel. These results were confirmed by flow cytometry, live imaging, and tissue immunostaining in the lacrimal gland. Importantly, effector T helper 1 (Th1) genes were highly upregulated on aged Tregs, including the master regulator Tbx21. Among the non-Tregs, we also found a significant increase in the levels of EOMES^med/high, Tbet^negIFN-γ⁺, and CD62L⁺CD44^negCD4⁺ T cells with aging, which are associated with cell exhaustion, immunopathology, and the generation of tertiary lymphoid tissue. At the functional level, aged Tregs from lymphoid organs are less able to decrease proliferation and IFN-γ production of T responders at any age. More importantly, human lacrimal glands (age range 55-81 years) also showed the presence of CD4⁺Foxp3⁺ cells. Further studies are needed to propose potential molecular targets to avoid immune-mediated lacrimal gland dysfunction with aging.

Investigating the Potential of Isolating and Expanding Tumour-Infiltrating Lymphocytes from Adult Sarcoma

Simple Summary

Sarcomas are rare cancers that arise from connective tissue. There are more than 50 subtypes, many of which are associated with a high risk of metastasis and poor prognosis. Subtype-specific treatment is limited and conventional treatment for advanced disease has varying effects across individuals and tumour subtypes. Adoptive cell therapy shows potential to provide more personalized treatment; this study aims to explore the potential of using tumour-infiltrating lymphocytes (TIL) to treat sarcoma. We optimized a sarcoma-specific expansion protocol and successfully expanded TILs from 54 of 92 sarcoma specimens. We characterized primarily CD4⁺ and CD8⁺ T-cells in the expanded TIL cultures and demonstrated their reactivity to general stimuli. Although sarcomas in general do not have abundant lymphocytic infiltration, our expansion protocol allowed for successful expansions of viable and reactive lymphocytes, thus showing the prospects of adopting TIL therapy in sarcoma.

Abstract

Sarcomas are a heterogeneous group of mesenchymal neoplasms, many of which are associated with a high risk of metastasis and poor prognosis. Conventional chemotherapy and targeted therapies have varying effects across individuals and tumour subtypes. The current therapies frequently provide limited clinical benefit; hence, more effective treatments are urgently needed. Recent advances in immunotherapy, such as checkpoint inhibition or adoptive cell therapy (ACT), show potential in increasing efficacy by providing a more personalized treatment. Therapy with tumour-infiltrating lymphocytes (TILs) is an emerging field in immunotherapy. Here, we collected 190 sarcoma tumour specimens from patients without pre-operative adjuvant treatment in order to isolate TILs. We compared different methods of TIL expansion and optimized a protocol specifically for efficacy in culturing TILs from sarcoma. The expanded TIL populations were characterized by flow cytometry analysis using CD3, CD4, CD8, CD14, CD19 and CD56 markers. The TIL populations were non-specifically stimulated to establish TIL reactivity. Through an optimized expansion protocol, TILs were isolated and cultured from 54 of 92 primary sarcoma specimens. The isolated TILs varied in CD4⁺ and CD8⁺ T-cell compositions and retained their ability to release IFNγ upon stimulation. Our results suggest that certain sarcoma subtypes have the potential to yield a sufficient number of TILs for TIL therapy.

Overexpression of PD-1 and CD39 in tumor-infiltrating lymphocytes compared with peripheral blood lymphocytes in triple-negative breast cancer

Background and aim

Growing evidence highlighted the primary role of the immune system in the disease course of triple-negative breast cancer (TNBC). The study aim was to investigate the expression of PD-1 and CD39 on CD4⁺ and CD8⁺ cells infiltrating tumor tissue compared to their counterparts in peripheral blood and explore its association with tumor characteristics, disease progression, and prognosis in females with TNBC.

Patients and methods

The study included 30 TNBC patients and 20 healthy controls. Cancer and normal breast tissue and peripheral blood samples were collected for evaluation of the expression of PD-1 and CD39 on CD4⁺ and CD8⁺T cells by flow cytometry.

Results

A marked reduction in the percentage of CD8⁺ T lymphocytes and a significant increase in the frequencies of CD4⁺ T lymphocytes and CD4⁺ and CD8⁺ T lymphocytes expressing PD1 and CD39 were evident in tumor tissue in comparison with the normal breast tissue. The DFS was inversely related to the cancer tissue PD1⁺CD8⁺ and CD39⁺CD8⁺ T lymphocytes. Almost all studied cells were significantly increased in the tumor tissue than in peripheral blood. Positive correlations were detected among peripheral PD1⁺CD4⁺T lymphocytes and each of cancer tissue PD1⁺CD4⁺, PD1⁺CD8⁺and CD39⁺CD8⁺T cells, and among peripheral and cancer tissue CD39⁺CD4⁺and CD39⁺CD8⁺ T cells.

Conclusions

The CD39 and PD1 inhibitory pathways are synergistically utilized by TNBC cells to evade host immune response causing poor survival. Hence, combinational immunotherapy blocking these pathways might be a promising treatment strategy in this type of cancer.

Systemic high-dose dexamethasone treatment may modulate the efficacy of intratumoral viral oncolytic immunotherapy in glioblastoma models

Background

Intratumoral viral oncolytic immunotherapy is a promising new approach for the treatment of a variety of solid cancers. CAN-2409 is a replication-deficient adenovirus that delivers herpes simplex virus thymidine kinase to cancer cells, resulting in local conversion of ganciclovir or valacyclovir into a toxic metabolite. This leads to highly immunogenic cell death, followed by a local immune response against a variety of cancer neoantigens and, next, a systemic immune response against the injected tumor and uninjected distant metastases. CAN-2409 treatment has shown promising results in clinical studies in glioblastoma (GBM). Patients with GBM are usually given the corticosteroid dexamethasone to manage edema. Previous work has suggested that concurrent dexamethasone therapy may have a negative effect in patients treated with immune checkpoint inhibitors in patients with GBM. However, the effects of dexamethasone on the efficacy of CAN-2409 treatment have not been explored.

Methods

In vitro experiments included cell viability and neurosphere T-cell killing assays. Effects of dexamethasone on CAN-2409 in vivo were examined using a syngeneic murine GBM model; survival was assessed according to Kaplan-Meier; analyses of tumor-infiltrating lymphocytes were performed with mass cytometry (CyTOF - cytometry by time-of-flight). Data were analyzed using a general linear model, with one-way analysis of variance followed by Dunnett’s multiple comparison test, Kruskal-Wallis test, Dunn’s multiple comparison test or statistical significance analysis of microarrays.

Results

In a mouse model of GBM, we found that high doses of dexamethasone combined with CAN-2409 led to significantly reduced median survival (29.0 days) compared with CAN-2409 treatment alone (39.5 days). CyTOF analyses of tumor-infiltrating immune cells demonstrated potent immune stimulation induced by CAN-2409 treatment. These effects were diminished when high-dose dexamethasone was used. Functional immune cell characterization suggested increased immune cell exhaustion and tumor promoting profiles after dexamethasone treatment.

Conclusion

Our data suggest that concurrent high-dose dexamethasone treatment may impair the efficacy of oncolytic viral immunotherapy of GBM, supporting the notion that dexamethasone use should be balanced between symptom control and impact on the therapeutic outcome.

B cells imprint adoptively transferred CD8+ T cells with enhanced tumor immunity

BACKGROUND

Adoptive T cell transfer (ACT) therapy improves outcomes in patients with advanced malignancies, yet many individuals relapse due to the infusion of T cells with poor function or persistence. Toll-like receptor (TLR) agonists can invigorate antitumor T cell responses when administered directly to patients, but these responses often coincide with toxicities. We posited that TLR agonists could be repurposed ex vivo to condition T cells with remarkable potency in vivo, circumventing TLR-related toxicity.

METHODS

In this study we investigated how tumor-specific murine CD8+ T cells and human tumor infiltrating lymphocytes (TILs) are impacted when expanded ex vivo with the TLR9 agonist CpG.

RESULTS

Herein we reveal a new way to reverse the tolerant state of adoptively transferred CD8+ T cells against tumors using TLR-activated B cells. We repurposed the TLR9 agonist, CpG, commonly used in the clinic, to bolster T cell-B cell interactions during expansion for ACT. T cells expanded ex vivo from a CpG-treated culture demonstrated potent antitumor efficacy and prolonged persistence in vivo. This antitumor efficacy was accomplished without in vivo administration of TLR agonists or other adjuvants of high-dose interleukin (IL)-2 or vaccination, which are classically required for effective ACT therapy. CpG-conditioned CD8+ T cells acquired a unique proteomic signature hallmarked by an IL-2RαhighICOShighCD39low phenotype and an altered metabolic profile, all reliant on B cells transiently present in the culture. Likewise, human TILs benefitted from expansion with CpG ex vivo, as they also possessed the IL-2RαhighICOShighCD39low phenotype. CpG fostered the expansion of potent CD8+ T cells with the signature phenotype and antitumor ability via empowering a direct B-T cell interaction. Isolated B cells also imparted T cells with the CpG-associated phenotype and improved tumor immunity without the aid of additional antigen-presenting cells or other immune cells in the culture.

CONCLUSIONS

Our results demonstrate a novel way to use TLR agonists to improve immunotherapy and reveal a vital role for B cells in the generation of potent CD8+ T cell-based therapies. Our findings have immediate implications in the clinical treatment of advanced solid tumors.

Hallmarks of the aging T-cell system

The adaptive immune system has the enormous challenge to protect the host through the generation and differentiation of pathogen-specific short-lived effector T cells while in parallel developing long-lived memory cells to control future encounters with the same pathogen. A complex regulatory network is needed to preserve a population of naïve cells over lifetime that exhibit sufficient diversity of antigen receptors to respond to new antigens, while also sustaining immune memory. In parallel, cells need to maintain their proliferative potential and the plasticity to differentiate into different functional lineages. Initial signs of waning immune competence emerge after 50 years of age, with increasing clinical relevance in the 7th-10th decade of life. Morbidity and mortality from infections increase, as drastically exemplified by the current COVID-19 pandemic. Many vaccines, such as for the influenza virus, are poorly effective to generate protective immunity in older individuals. Age-associated changes occur at the level of the T-cell population as well as the functionality of its cellular constituents. The system highly relies on the self-renewal of naïve and memory T cells, which is robust but eventually fails. Genetic and epigenetic modifications contribute to functional differences in responsiveness and differentiation potential. To some extent, these changes arise from defective maintenance; to some, they represent successful, but not universally beneficial adaptations to the aging host. Interventions that can compensate for the age-related defects and improve immune responses in older adults are increasingly within reach.

The cell-surface 5'-nucleotidase CD73 defines a functional T memory cell subset that declines with age

Memory T cells exhibit considerable diversity that determines their ability to be protective. Here, we examine whether changes in T cell heterogeneity contribute to the age-associated failure of immune memory. By screening for age-dependent T cell-surface markers, we identify CD4 and CD8 memory T cell subsets that are unrelated to previously defined subsets of central and effector memory cells. Memory T cells expressing the ecto-5'-nucleotidase CD73 constitute a functionally distinct subset of memory T cells that declines with age. They resemble long-lived, polyfunctional memory cells but are also poised to display effector functions and to develop into cells resembling tissue-resident memory T cells (T_RMs). Upstream regulators of differential chromatin accessibility and transcriptomes include transcription factors that facilitate CD73 expression and regulate TRM differentiation. CD73 is not just a surrogate marker of these regulatory networks but is directly involved in T cell survival.

mRNA vaccines for infectious diseases: principles, delivery and clinical translation

Over the past several decades, messenger RNA (mRNA) vaccines have progressed from a scepticism-inducing idea to clinical reality. In 2020, the COVID-19 pandemic catalysed the most rapid vaccine development in history, with mRNA vaccines at the forefront of those efforts. Although it is now clear that mRNA vaccines can rapidly and safely protect patients from infectious disease, additional research is required to optimize mRNA design, intracellular delivery and applications beyond SARS-CoV-2 prophylaxis. In this Review, we describe the technologies that underlie mRNA vaccines, with an emphasis on lipid nanoparticles and other non-viral delivery vehicles. We also overview the pipeline of mRNA vaccines against various infectious disease pathogens and discuss key questions for the future application of this breakthrough vaccine platform.

CD39+ Fibroblasts Enhance Myofibroblast Activation by Promoting IL-11 Secretion in Hypertrophic Scars

Fibroblasts (Fbs) are critical to hypertrophic scar (HTS) formation and were recently shown to be highly heterogeneous. However, Fb heterogeneity in HTSs has not been fully elucidated. In this study, we observed an increased fraction of CD39⁺ Fbs in HTS after screening four Fb subtypes (CD26⁺, CD36⁺, FAP⁺, and CD39⁺). CD39⁺ Fbs, enriched in the upper dermis, were positively correlated with scar severity. The transcriptional analysis of CD39⁺ and CD39^- Fbs sorted from HTS revealed that IL-11 was more highly expressed in CD39⁺ Fbs. We then showed that IL-11 was upregulated in HTSs and that its expression was induced by TGFβ1 in vitro. TGFβ1 also stimulated the expression of CD39 at the transcriptional and protein levels, mediating the maintenance of the CD39⁺ phenotype. Furthermore, IL-11 facilitated myofibroblast activation and extracellular matrix production in both CD39⁺ and CD39^- Fbs. Interestingly, CD39⁺ Fbs secreted more IL-11 on TGFβ1 treatment and were less responsive to IL-11 than CD39^- Fbs. Notably, a CD39 inhibitor effectively reduced stretch-induced scar formation and attenuated bleomycin-induced skin fibrosis, suggesting an antiscarring approach by targeting CD39⁺ Fbs.

On the mechanism of anti-CD39 immune checkpoint therapy

With the coming of age of cancer immunotherapy, the search for new therapeutic targets has led to the identification of immunosuppressive adenosine as an important regulator of antitumor immunity. This resulted in the development of selective inhibitors targeting various components of the adenosinergic pathway, including small molecules antagonists targeting the high affinity A2A adenosine receptor and low affinity A2B receptor, therapeutic monoclonal antibodies (mAbs) and small molecules targeting CD73 and therapeutic mAbs targeting CD39. As each regulator of the adenosinergic pathway present non-overlapping biologic functions, a better understanding of the mechanisms of action of each targeted approach should accelerate clinical translation and improve rational design of combination treatments. In this review, we discuss the potential mechanisms-of-action of anti-CD39 cancer therapy and potential toxicities that may emerge from sustained CD39 inhibition. Caution should be taken, however, in extrapolating data from gene-targeted mice to patients treated with blocking anti-CD39 agents. As phase I clinical trials are now underway, further insights into the mechanism of action and potential adverse events associated with anti-CD39 therapy are anticipated in coming years.

CD39 Regulation and Functions in T Cells

CD39 is an enzyme which is responsible, together with CD73, for a cascade converting adenosine triphosphate into adenosine diphosphate and cyclic adenosine monophosphate, ultimately leading to the release of an immunosuppressive form of adenosine in the tumor microenvironment. Here, we first review the environmental and genetic factors shaping CD39 expression. Second, we report CD39 functions in the T cell compartment, highlighting its role in regulatory T cells, conventional CD4⁺ T cells and CD8⁺ T cells. Finally, we compile a list of studies, from preclinical models to clinical trials, which have made essential contributions to the discovery of novel combinatorial approaches in the treatment of cancer.

Extracellular vesicles regulate purinergic signaling and epithelial sodium channel expression in renal collecting duct cells

Purinergic signaling regulates several renal physiological and pathophysiological processes. Extracellular vesicles (EVs) are nanoparticles released by most cell types, which, in non-renal tissues, modulate purinergic signaling. The aim of this study was to investigate the effect of EVs from renal proximal tubule (HK2) and collecting duct cells (HCD) on intra- and intersegment modulation of extracellular ATP levels, the underlying molecular mechanisms, and the impact on the expression of the alpha subunit of the epithelial sodium channel (αENaC). HK2 cells were exposed to HK2 EVs, while HCD cells were exposed to HK2 and HCD EVs. Extracellular ATP levels and αENaC expression were measured by chemiluminescence and qRT-PCR, respectively. ATPases in EV populations were identified by mass spectrometry. The effect of aldosterone was assessed using EVs from aldosterone-treated cells and urinary EVs (uEVs) from primary aldosteronism (PA) patients. HK2 EVs downregulated ectonucleoside-triphosphate-diphosphohydrolase-1 (ENTPD1) expression, increased extracellular ATP and downregulated αENaC expression in HCD cells. ENTPD1 downregulation could be attributed to increased miR-205-3p and miR-505 levels. Conversely, HCD EVs decreased extracellular ATP levels and upregulated αENaC expression in HCD cells, probably due to enrichment of 14-3-3 isoforms with ATPase activity. Pretreatment of donor cells with aldosterone or exposure to uEVs from PA patients enhanced the effects on extracellular ATP and αENaC expression. We demonstrated inter- and intrasegment modulation of renal purinergic signaling by EVs. Our findings postulate EVs as carriers of information along the renal tubules, whereby processes affecting EV release and/or cargo may impact on purinergically regulated processes.

Targeting Dermal Fibroblast Subtypes in Antifibrotic Therapy: Surface Marker as a Cellular Identity or a Functional Entity?

Fibroblasts are the chief effector cells in fibrotic diseases and have been discovered to be highly heterogeneous. Recently, fibroblast heterogeneity in human skin has been studied extensively and several surface markers for dermal fibroblast subtypes have been identified, holding promise for future antifibrotic therapies. However, it has yet to be confirmed whether surface markers should be looked upon as merely lineage landmarks or as functional entities of fibroblast subtypes, which may further complicate the interpretation of cellular function of these fibroblast subtypes. This review aims to provide an update on current evidence on fibroblast surface markers in fibrotic disorders of skin as well as of other organ systems. Specifically, studies where surface markers were treated as lineage markers and manipulated as functional membrane proteins are both evaluated in parallel, hoping to reveal the underlying mechanism behind the pathogenesis of tissue fibrosis contributed by various fibroblast subtypes from multiple angles, shedding lights on future translational researches.

Regulation of immune responses through CD39 and CD73 in cancer: Novel checkpoints

The immunosuppressive tumor microenvironment has been implicated in attenuating anti-tumoral immune responses and tumor growth in various cancers. Inhibitory immune checkpoints have been introduced as the primary culprits for developing the immunosuppressive tumor microenvironment. Therefore, a better understanding of the cross-talk between inhibitory immune checkpoints in the tumor microenvironment can pave the way for introducing novel approaches for treating affected patients. Growing evidence indicates that CD39 and CD73, as novel checkpoints, can transform adenosine triphosphate (ATP)-mediated pro-inflammatory tumor microenvironment into an adenosine-mediated immunosuppressive one via the purinergic signaling pathway. Indeed, enzymatic processes of CD39 and CD73 have crucial roles in adjusting the extent, intensity, and chemical properties of purinergic signals. This study aims to review the biological function of CD39 and CD73 and shed light on their significance in regulating anti-tumoral immune responses in various cancers.

T cells drive negative feedback mechanisms in cancer associated fibroblasts, promoting expression of co-inhibitory ligands, CD73 and IL-27 in non-small cell lung cancer

The success of immune checkpoint therapy shows tumor-reactive T cells can eliminate cancer cells but are restrained by immunosuppression within the tumor micro-environment (TME). Cancer associated fibroblasts (CAFs) are the dominant stromal cell in the TME and co-localize with T cells in non-small cell lung cancer. We demonstrate the bidirectional nature of CAF/T cell interactions; T cells promote expression of co-inhibitory ligands, MHC molecules and CD73 on CAFs, increasing their production of IL-6 and eliciting production of IL-27. In turn CAFs upregulate co-inhibitory receptors on T cells including the ectonucleotidase CD39 promoting development of an exhausted but highly cytotoxic phenotype. Our results highlight the bidirectional interaction between T cells and CAFs in promoting components of the immunosuppressive CD39, CD73 adenosine pathway and demonstrate IL-27 production can be induced in CAF by activated T cells.

Activation of mTORC1 at late endosomes misdirects T cell fate decision in older individuals

The nutrient-sensing mammalian target of rapamycin (mTOR) is integral to cell fate decisions after T cell activation. Sustained mTORC1 activity favors the generation of terminally differentiated effector T cells instead of follicular helper and memory T cells. This is particularly pertinent for T cell responses of older adults who have sustained mTORC1 activation despite dysfunctional lysosomes. Here, we show that lysosome-deficient T cells rely on late endosomes rather than lysosomes as an mTORC1 activation platform, where mTORC1 is activated by sensing cytosolic amino acids. T cells from older adults have an increased expression of the plasma membrane leucine transporter SLC7A5 to provide a cytosolic amino acid source. Hence, SLC7A5 and VPS39 deficiency (a member of the HOPS complex promoting early to late endosome conversion) substantially reduced mTORC1 activities in T cells from older but not young individuals. Late endosomal mTORC1 is independent of the negative-feedback loop involving mTORC1-induced inactivation of the transcription factor TFEB that controls expression of lysosomal genes. The resulting sustained mTORC1 activation impaired lysosome function and prevented lysosomal degradation of PD-1 in CD4+ T cells from older adults, thereby inhibiting their proliferative responses. VPS39 silencing of human T cells improved their expansion to pertussis and to SARS-CoV-2 peptides in vitro. Furthermore, adoptive transfer of CD4+ Vps39-deficient LCMV-specific SMARTA cells improved germinal center responses, CD8+ memory T cell generation, and recall responses to infection. Thus, curtailing late endosomal mTORC1 activity is a promising strategy to enhance T cell immunity.

CD32+CD4+ T Cells Sharing B Cell Properties Increase With Simian Immunodeficiency Virus Replication in Lymphoid Tissues

CD4 T cell responses constitute an important component of adaptive immunity and are critical regulators of anti-microbial protection. CD4⁺ T cells expressing CD32a have been identified as a target for HIV. CD32a is an Fcγ receptor known to be expressed on myeloid cells, granulocytes, B cells and NK cells. Little is known about the biology of CD32⁺CD4⁺ T cells. Our goal was to understand the dynamics of CD32⁺CD4⁺ T cells in tissues. We analyzed these cells in the blood, lymph nodes, spleen, ileum, jejunum and liver of two nonhuman primate models frequently used in biomedical research: African green monkeys (AGM) and macaques. We studied them in healthy animals and during viral (SIV) infection. We performed phenotypic and transcriptomic analysis at different stages of infection. In addition, we compared CD32+CD4+ T cells in tissues with well-controlled (spleen) and not efficiently controlled (jejunum) SIV replication in AGM. The CD32⁺CD4⁺ T cells more frequently expressed markers associated with T cell activation and HIV infection (CCR5, PD-1, CXCR5, CXCR3) and had higher levels of actively transcribed SIV RNA than CD32^-CD4⁺T cells. Furthermore, CD32⁺CD4⁺ T cells from lymphoid tissues strongly expressed B-cell-related transcriptomic signatures, and displayed B cell markers at the cell surface, including immunoglobulins CD32+CD4+ T cells were rare in healthy animals and blood but increased strongly in tissues with ongoing viral replication. CD32⁺CD4⁺ T cell levels in tissues correlated with viremia. Our results suggest that the tissue environment induced by SIV replication drives the accumulation of these unusual cells with enhanced susceptibility to viral infection.

miR-181a-regulated pathways in T-cell differentiation and aging

MicroRNAs (miRNAs) are regulatory noncoding RNAs important for many aspects of cellular processes including cell differentiation and proliferation. Functions of numerous miRNAs have been identified in T cells, with miR-181a regulating T cell activation thresholds during thymic T cell development and during activation of peripheral T cells. Intriguingly, miR-181a is implicated in defective antiviral and vaccine responses in older individuals, as its expression declines in naïve T cells with increasing age. Here, we review the pathways that are regulated by miR-181a and that explain the unique role of miR-181a in T cell development, T cell activation and antiviral T cell responses. These studies provide a framework for understanding how a decline in miR-181a expression in T cells could contribute to age-related defects in adaptive immunity. We furthermore review the mechanisms that cause the age-related decline in miR-181a expression and discuss the potential of restoring miR-181a expression or targeting miR-181a-regulated pathways to improve impaired T cell responses in older individuals.