Regulation of miR-181a expression in T cell aging

miR-181a: regulatory roles, cancer-associated signaling pathway disruptions, and therapeutic potential

INTRODUCTION

microRNA-181a (miR-181a) is a crucial post-transcriptional regulator of many mRNA transcripts and noncoding-RNAs, influencing cell proliferation, cancer cell stemness, apoptosis, and immune responses. Its abnormal expression is well-characterized in numerous cancers, establishing it as a significant genomic vulnerability and biomarker in cancer research.

AREAS COVERED

Here, we summarize miR-181a's correlation with poor patient outcomes across numerous cancers and the mechanisms governing miR-181a's activity and processing. We comprehensively describe miR-181a's involvement in multiple regulatory cancer signaling pathways, cellular processes, and the tumor microenvironment. We also discuss current therapeutic approaches to targeting miR-181a, highlighting their limitations and future potential.

EXPERT OPINION

miR-181a is a clinically relevant pan-cancer biomarker with potential as a therapeutic target. Its regulatory control of tumorigenic signaling pathways and immune responses positions it as a promising candidate for personalized treatments. The success of miR-181a as a target relies on the development of specific therapeutics platforms. Future research on miR-181a's role in the tumor microenvironment and the RNA binding proteins that regulate its stability will help uncover new techniques to targeting miR-181a. Further research into miR-181a serum levels in patients undergoing therapy will help to better stratify patients and enhance therapeutic success.

Identifying and validating the key regulatory transcription factor YY1 in the aging process of pancreatic beta cells based on bioinformatics

The aging of pancreatic beta cells is closely associated with various diseases, such as impaired glucose tolerance, yet the underlying regulatory mechanisms remain unclear. In this study, we screened young and aged mouse pancreatic beta cells' high-throughput sequencing data from the GEO public database. Utilizing bioinformatics techniques, we identified the key regulatory factor YY1 in the aging process of pancreatic islets. We observed a significant decrease in the expression of YY1 in a D-gal-induced mouse model of pancreatic aging and an H2O2-induced MIN6 cell model of aging. Moreover, both vivo and vitro models, we found that the YY1 agonist eudesmin (EDN) improved glucose intolerance in mice, alleviated aging of pancreatic beta cells, and downregulated the expression of cell cycle protein P21. Mechanistically, we discovered that EDN inhibited the P38/JNK MAPK pathway in aging cells. In summary, our study confirms the regulatory role of the transcription factor YY1 in the aging process of pancreatic beta cells. This finding may provide a new approach for the clinical treatment of pancreatic aging-related diseases such as impaired glucose tolerance or diabetes.

Digital PCR-based quantification of miR-181a in the cerebrospinal fluid aids patient stratification in pediatric acute lymphoblastic leukemia

Despite remarkable improvements in the survival of pediatric acute lymphoblastic leukemia (ALL), sensitive detection and clinical management of central nervous system leukemia (CNSL) are still immensely challenging. Blast cells residing in the CNS but not circulating in the cerebrospinal fluid (CSF) remain undetected by current diagnostic methods, preventing a truly risk-adapted anti-leukemic treatment in this compartment. We examined the clinical applicability of the molecular marker microRNA (miR)-181a quantified in the cell-free CSF to evaluate the level of CNS involvement and to optimize patient stratification based on CNS status. Normalized copy number of miR-181a was longitudinally profiled using droplet digital PCR, and the results were compared with the degree of leukemic involvement of the CNS. After combining cytospin- and flow cytometry (FCM) data with miR-181a expression, we could stratify previously ambiguous cases and reclassify patients into a CNS-positive/miR-significant group (mean ± SE for miR-181a copies: 3300.70 ± 809.69) bearing remarkable infiltration as well as into CNS-minimal/miR-significant and CNS-minimal/miR-minimal groups differentiating putative, clinically significant occult CNSL cases (2503.50 ± 275.89 and 744.02 ± 86.81 copies, respectively, p = 1.13 × 10-6). In summary, miR-181a expression is a promising biomarker for CNSL detection, facilitating the robust identification of patients who could benefit from intensified CNS-directed therapy.

Extracellular vesicles miR-574-5p and miR-181a-5p as prognostic markers in NSCLC patients treated with nivolumab

Immune checkpoint inhibitors (ICIs) have revolutionized the management of advanced non-small cell lung cancer (NSCLC), although patient survival is still unsatisfactory. Accurate predictive markers capable of personalizing the treatment of patients with NSCLC are still lacking. Circulating extracellular vesicles involved in cell-to-cell communications through miRNAs (EV-miRs) transfer are promising markers. Plasma from 245 patients with advanced NSCLC who received nivolumab as second-line therapy was collected and analyzed. EV-miRnome was profiled on 174/245 patients by microarray platform, and selected EV-miRs were validated by qPCR. A prognostic model combining EV-miR and clinical variables was built using stepwise Cox regression analysis and tested on an independent patient cohort (71/245). EV-PD-L1 gene copy number was assessed by digital PCR. For 54 patients with disease control, EV-miR changes at best response versus baseline were investigated by microarray and validated by qPCR. EV-miRNome profiling at baseline identified two EV-miRs (miR-181a-5p and miR-574-5p) that, combined with performance status, are capable of discriminating patients unlikely from those that are likely to benefit from immunotherapy (median overall survival of 4 months or higher than 9 months, respectively). EV-PD-L1 digital evaluation reported higher baseline copy number in patients at increased risk of mortality, without improving the prognostic score. Best response EV-miRNome profiling selected six deregulated EV-miRs (miR19a-3p, miR-20a-5p, miR-142-3p, miR-1260a, miR-1260b, and miR-5100) in responding patients. Their longitudinal monitoring highlighted a significant downmodulation already in the first treatment cycles, which lasted more than 6 months. Our results demonstrate that EV-miRs are promising prognostic markers for NSCLC patients treated with nivolumab.

The RNA binding protein IGF2BP2/IMP2 alters the cargo of cancer cell-derived extracellular vesicles supporting tumor-associated macrophages

BACKGROUND

Tumor cells release extracellular vesicles (EVs) that contribute to the polarization of macrophages towards tumor-associated macrophages (TAMs). High expression levels of the RNA binding protein IGF2BP2/IMP2 are correlated with increased tumor cell proliferation, invasion, and poor prognosis in the clinic. However, there is a lack of understanding of whether IMP2 affects the cargo of cancer cell-derived EVs, thereby modulating macrophage polarization.

METHODS

EVs were isolated from IMP2-expressing HCT116 parental cells (WT) and CRISPR/Cas9 IMP2 knockout (KO) cells. EVs were characterized according to MISEV guidelines, microRNA cargo was assessed by microRNA-Seq, and the protein cargo was analyzed by proteomics. Primary human monocyte-derived macrophages (HMDMs) were polarized by EVs, and the expression of genes and surface markers was assessed using qPCR and flow cytometry, respectively. Morphological changes of macrophages, as well as the migratory potential of cancer cells, were assessed by the Incucyte® system and macrophage matrix degradation potential by zymography. Changes in the metabolic activity of macrophages were quantified using a Seahorse® analyzer. For in vivo studies, EVs were injected into the yolk sac of zebrafish larvae, and macrophages were isolated by fluorescence-activated cell sorting.

RESULTS

EVs from WT and KO cells had a similar size and concentration and were positive for 25 vesicle markers. The expression of tumor-promoting genes was higher in macrophages polarized with WT EVs than KO EVs, while the expression of TNF and IL6 was reduced. A similar pattern was observed in macrophages from zebrafish larvae treated in vivo. WT EV-polarized macrophages showed a higher abundance of TAM-like surface markers, higher matrix degrading activity, as well as a higher promotion of cancer cell migration. MicroRNA-Seq revealed a significant difference in the microRNA composition of WT and KO EVs, particularly a high abundance of miR-181a-5p in WT EVs, which was absent in KO EVs. Inhibitors of macropinocytosis and phagocytosis antagonized the delivery of miR-181a-5p into macrophages and the downregulation of the miR-181a-5p target DUSP6. Proteomics data showed differences in protein cargo in KO vs. WT EVs, with the differentially abundant proteins mainly involved in metabolic pathways. WT EV-treated macrophages exhibited a higher basal oxygen consumption rate and a lower extracellular acidification rate than KO EV-treated cells.

CONCLUSION

Our results show that IMP2 determines the cargo of EVs released by cancer cells, thereby modulating the EVs' actions on macrophages. Expression of IMP2 is linked to the secretion of EVs that polarize macrophages towards a tumor-promoting phenotype.

Molecular insights of exercise therapy in disease prevention and treatment

Despite substantial evidence emphasizing the pleiotropic benefits of exercise for the prevention and treatment of various diseases, the underlying biological mechanisms have not been fully elucidated. Several exercise benefits have been attributed to signaling molecules that are released in response to exercise by different tissues such as skeletal muscle, cardiac muscle, adipose, and liver tissue. These signaling molecules, which are collectively termed exerkines, form a heterogenous group of bioactive substances, mediating inter-organ crosstalk as well as structural and functional tissue adaption. Numerous scientific endeavors have focused on identifying and characterizing new biological mediators with such properties. Additionally, some investigations have focused on the molecular targets of exerkines and the cellular signaling cascades that trigger adaption processes. A detailed understanding of the tissue-specific downstream effects of exerkines is crucial to harness the health-related benefits mediated by exercise and improve targeted exercise programs in health and disease. Herein, we review the current in vivo evidence on exerkine-induced signal transduction across multiple target tissues and highlight the preventive and therapeutic value of exerkine signaling in various diseases. By emphasizing different aspects of exerkine research, we provide a comprehensive overview of (i) the molecular underpinnings of exerkine secretion, (ii) the receptor-dependent and receptor-independent signaling cascades mediating tissue adaption, and (iii) the clinical implications of these mechanisms in disease prevention and treatment.

MicroRNA-181 in cardiovascular disease: Emerging biomarkers and therapeutic targets

Cardiovascular disease (CVD) is the leading cause of death worldwide. MicroRNAs (MiRNAs) have attracted considerable attention for their roles in several cardiovascular disease states, including both the physiological and pathological processes. In this review, we will briefly describe microRNA-181 (miR-181) transcription and regulation and summarize recent findings on the roles of miR-181 family members as biomarkers or therapeutic targets in different cardiovascular-related conditions, including atherosclerosis, myocardial infarction, hypertension, and heart failure. Lessons learned from these studies may provide new theoretical foundations for CVD.

Non-coding RNAs in exercise immunology: A systematic review

Regular physical exercise has been recognized as a potent modulator of immune function, with its effects including enhanced immune surveillance, reduced inflammation, and improved overall health. While strong evidence exists that physical exercise affects the specific expression and activity of non-coding RNAs (ncRNAs) also involved in immune system regulation, heterogeneity in individual study designs and analyzed exercise protocols exists, and a condensed list of functional, exercise-dependent ncRNAs with known targets in the immune system is missing from the literature. A systematic review and qualitative analysis was used to identify and categorize ncRNAs participating in immune modulation by physical exercise. Two combined approaches were used: (a) a systematic literature search for "ncRNA and exercise immunology", (b) and a database search for microRNAs (miRNAs) (miRTarBase and DIANA-Tarbase v8) aligned with known target genes in the immune system based on the Reactome database, combined with a systematic literature search for "ncRNA and exercise". Literature searches were based on PubMed, Web of Science, and SPORTDiscus; and miRNA databases were filtered for targets validated by in vitro experimental data. Studies were eligible if they reported on exercise-based interventions in healthy humans. After duplicate removal, 95 studies were included reporting on 164 miRNAs, which were used for the qualitative synthesis. Six studies reporting on long-noncoding RNAs (lncRNAs) or circular RNAs were also identified. Results were analyzed using ordering tables that included exercise modality (endurance/resistance exercise), acute or chronic interventions, as well as the consistency in reported change between studies. Evaluation criteria were defined as "validated" with 100% of ≥3 independent studies showing identical direction of regulation, "plausible" (≥80%), or "suggestive" (≥70%). For resistance exercise, upregulation of miR-206 was validated while downregulation of miR-133a appeared plausible. For endurance exercise, 15 miRNAs were categorized as validated, with 12 miRNAs being consistently elevated and 3 miRNAs being downregulated, most of them after acute exercise training. In conclusion, our approach provides evidence that miRNAs play a major role in exercise-induced effects on the innate and adaptive immune system by targeting different pathways affecting immune cell distribution, function, and trafficking as well as production of (anti-)inflammatory cytokines. miRNAs miR-15, miR-29c, miR-30a, miR-142/3, miR-181a, and miR-338 emerged as key players in mediating the immunomodulatory effects of exercise predominantly after acute bouts of endurance exercise.

Senescent T Cells in Age-Related Diseases

Age-induced alterations in human immunity are often considered deleterious and are referred to as immunosenescence. The immune system monitors the number of senescent cells in the body, while immunosenescence may represent the initiation of systemic aging. Immune cells, particularly T cells, are the most impacted and involved in age-related immune function deterioration, making older individuals more prone to different age-related diseases. T-cell senescence can impact the effectiveness of immunotherapies that rely on the immune system's function, including vaccines and adoptive T-cell therapies. The research and practice of using senescent T cells as therapeutic targets to intervene in age-related diseases are in their nascent stages. Therefore, in this review, we summarize recent related literature to investigate the characteristics of senescent T cells as well as their formation mechanisms, relationship with various aging-related diseases, and means of intervention. The primary objective of this article is to explore the prospects and possibilities of therapeutically targeting senescent T cells, serving as a valuable resource for the development of immunotherapy and treatment of age-related diseases.

Role of microRNAs in Immune Regulation with Translational and Clinical Applications

MicroRNAs (miRNAs) are 19-23 nucleotide long, evolutionarily conserved noncoding RNA molecules that regulate gene expression at the post-transcriptional level. In this review, involvement of miRNAs is summarized in the differentiation and function of immune cells, in anti-infective immune responses, immunodeficiencies and autoimmune diseases. Roles of miRNAs in anticancer immunity and in the transplantation of solid organs and hematopoietic stem cells are also discussed. Major focus is put on the translational clinical applications of miRNAs, including the establishment of noninvasive biomarkers for differential diagnosis and prediction of prognosis. Patient selection and response prediction to biological therapy is one of the most promising fields of application. Replacement or inhibition of miRNAs has enormous therapeutic potential, with constantly expanding possibilities. Although important challenges still await solutions, evaluation of miRNA fingerprints may contribute to an increasingly personalized management of immune dysregulation with a remarkable reduction in toxicity and treatment side effects. More detailed knowledge of the molecular effects of physical exercise and nutrition on the immune system may facilitate self-tailored lifestyle recommendations and advances in prevention.

Potential role of mesenchymal stem cells in T cell aging

Immunosenescence occurs with progressive age. T cell aging is manifested by immunodeficiency and inflammation. The main mechanisms are thymic involution, mitochondrial dysfunction, genetic and epigenetic alterations, loss of protein stability, reduction of T cell receptor (TCR) repertoire, naïve-memory T cell ratio imbalance, T cell senescence, and lack of effector plasticity. Mesenchymal stem cells (MSCs) are thought to hold great potential as anti-aging therapy. However, the role of MCSs in T cell aging remains elusive. This review makes a tentative summary of the potential role of MSCs in the protection against T cell aging. It might provide a new idea to intervene in the aging of the immune system.

Cellular senescence in skeletal disease: mechanisms and treatment

The musculoskeletal system supports the movement of the entire body and provides blood production while acting as an endocrine organ. With aging, the balance of bone homeostasis is disrupted, leading to bone loss and degenerative diseases, such as osteoporosis, osteoarthritis, and intervertebral disc degeneration. Skeletal diseases have a profound impact on the motor and cognitive abilities of the elderly, thus creating a major challenge for both global health and the economy. Cellular senescence is caused by various genotoxic stressors and results in permanent cell cycle arrest, which is considered to be the underlying mechanism of aging. During aging, senescent cells (SnCs) tend to aggregate in the bone and trigger chronic inflammation by releasing senescence-associated secretory phenotypic factors. Multiple signalling pathways are involved in regulating cellular senescence in bone and bone marrow microenvironments. Targeted SnCs alleviate age-related degenerative diseases. However, the association between senescence and age-related diseases remains unclear. This review summarises the fundamental role of senescence in age-related skeletal diseases, highlights the signalling pathways that mediate senescence, and discusses potential therapeutic strategies for targeting SnCs.

Reliable Hallmarks and Biomarkers of Senescent Lymphocytes

The phenomenon of accumulation of senescent adaptive immunity cells in the elderly is attracting attention due to the increasing risk of global epidemics and aging of the global population. Elderly people are predisposed to various infectious and age-related diseases and are at higher risk of vaccination failure. The accumulation of senescent cells increases age-related background inflammation, "Inflammaging", causing lymphocyte exhaustion and cardiovascular, neurodegenerative, autoimmune and cancer diseases. Here, we present a comprehensive contemporary review of the mechanisms and phenotype of senescence in the adaptive immune system. Although modern research has not yet identified specific markers of aging lymphocytes, several sets of markers facilitate the separation of the aging population based on normal memory and exhausted cells for further genetic and functional analysis. The reasons for the higher predisposition of CD8+ T-lymphocytes to senescence compared to the CD4+ population are also discussed. We point out approaches for senescent-lymphocyte-targeting markers using small molecules (senolytics), antibodies and immunization against senescent cells. The suppression of immune senescence is the most relevant area of research aimed at developing anti-aging and anti-cancer therapy for prolonging the lifespan of the global population.

Regulation of cardiac fibroblasts by lymphocytes after a myocardial infarction: playing in the major league

Cardiac fibrosis is a pathological condition characterized by excessive accumulation of extracellular matrix components within the myocardium, which can lead to impaired cardiac function and heart failure. Studies have shown that lymphocytes including B and T cells play important roles in the development and progression of cardiac fibrosis after a myocardial infarction. In this review, we focus on the regulation of cardiac fibrosis by lymphocyte subsets, with a particular emphasis on CD4+ and CD8+ T cells and their effects on fibroblasts and cardiac remodeling. We also highlight areas for further exploration of the interactions between T cells and fibroblasts necessary for understanding and treating cardiac fibrosis and heart failure.

Mitochondrial epigenetics in aging and cardiovascular diseases

Mitochondria are cellular organelles which generate adenosine triphosphate (ATP) molecules for the maintenance of cellular energy through the oxidative phosphorylation. They also regulate a variety of cellular processes including apoptosis and metabolism. Of interest, the inner part of mitochondria-the mitochondrial matrix-contains a circular molecule of DNA (mtDNA) characterised by its own transcriptional machinery. As with genomic DNA, mtDNA may also undergo nucleotide mutations that have been shown to be responsible for mitochondrial dysfunction. During physiological aging, the mitochondrial membrane potential declines and associates with enhanced mitophagy to avoid the accumulation of damaged organelles. Moreover, if the dysfunctional mitochondria are not properly cleared, this could lead to cellular dysfunction and subsequent development of several comorbidities such as cardiovascular diseases (CVDs), diabetes, respiratory and cardiovascular diseases as well as inflammatory disorders and psychiatric diseases. As reported for genomic DNA, mtDNA is also amenable to chemical modifications, namely DNA methylation. Changes in mtDNA methylation have shown to be associated with altered transcriptional programs and mitochondrial dysfunction during aging. In addition, other epigenetic signals have been observed in mitochondria, in particular the interaction between mtDNA methylation and non-coding RNAs. Mitoepigenetic modifications are also involved in the pathogenesis of CVDs where oxygen chain disruption, mitochondrial fission, and ROS formation alter cardiac energy metabolism leading to hypertrophy, hypertension, heart failure and ischemia/reperfusion injury. In the present review, we summarize current evidence on the growing importance of epigenetic changes as modulator of mitochondrial function in aging. A better understanding of the mitochondrial epigenetic landscape may pave the way for personalized therapies to prevent age-related diseases.

T cell aging as a risk factor for autoimmunity

Immune aging is a complex process rendering the host susceptible to cancer, infection, and insufficient tissue repair. Many autoimmune diseases preferentially occur during the second half of life, counterintuitive to the concept of excess adaptive immunity driving immune-mediated tissue damage. T cells are particularly susceptible to aging-imposed changes, as they are under extreme proliferative pressure to fulfill the demands of clonal expansion and of homeostatic T cell repopulation. T cells in older adults have a footprint of genetic and epigenetic changes, lack mitochondrial fitness, and fail to maintain proteostasis, diverging them from host protection to host injury. Here, we review recent progress in understanding how the human T-cell system ages and the evidence detailing how T cell aging contributes to autoimmune conditions. T cell aging is now recognized as a risk determinant in two prototypic autoimmune syndromes; rheumatoid arthritis and giant cell arteritis. The emerging concept adds susceptibility to autoimmune and autoinflammatory disease to the spectrum of aging-imposed adaptations and opens new opportunities for immunomodulatory therapy by restoring the functional intactness of aging T cells.

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.

Age-associated remodeling of T cell immunity and metabolism

Aging results in remodeling of T cell immunity and is associated with poor clinical outcomes in age-related diseases such as cancer. Among the hallmarks of aging, changes in host and cellular metabolism critically affect the development, maintenance, and function of T cells. Although metabolic perturbations impact anti-tumor T cell responses, the link between age-associated metabolic dysfunction and anti-tumor immunity remains unclear. In this review, we summarize recent advances in our understanding of aged T cell metabolism, with a focus on the bioenergetic and immunologic features of T cell subsets unique to the aging process. We also survey insights into mechanisms of metabolic T cell dysfunction in aging and discuss the impacts of aging on the efficacy of cancer immunotherapy. As the average life expectancy continues to increase, understanding the interplay between age-related metabolic reprogramming and maladaptive T cell immunity will be instrumental for the development of therapeutic strategies for older patients.

Transcription Factor YY1 Ameliorates Liver Ischemia-reperfusion Injury Through Modulating the miR-181a-5p/ESR1/ERBB2 Axis

BACKGROUND

Liver ischemia/reperfusion injury (I/RI) is characterized by inflammatory actions. Understanding the mechanistic insights underpinning inflammation is critical to developing treatment strategies. In this study, we illustrated the mechanistic insights of transcription factor Yin-Yang 1 (YY1)-mediated microRNA (miR)-181a-5p/estrogen receptor alpha (ESR1)/epidermal growth factor receptor 2 (ERBB2) axis in liver I/RI.

METHODS

First, we established liver I/RI models in mice and hypoxia-reperfusion (H/R) cell models in mouse hepatocytes (AML12). Subsequently, the expression of YY1, miR-181a-5p, and ESR1 was determined in the 2 models. I/RI mouse models were further injected with lentivirus carrying oe-YY1' and H/R-exposed AML12 cells were subjected to a series of inhibitors, mimics, and shRNAs to validate the mechanisms of YY1 in controlling miR-181a-5p and ESR1 in liver I/RI.

RESULTS

Upregulated expression of miR-181a-5p and downregulated expression of YY1 were identified in the liver tissues of liver I/RI mice and H/R-exposed hepatocytes. Moreover, overexpression of YY1 inhibited the miR-181a-5p expression and thus repressed the H/R-induced hepatocyte apoptosis and inflammation. ESR1 was further validated as a target gene of miR-181a-5p and could be negatively regulated by miR-181a-5p. miR-181a-5p inhibition elevated ESR1 expression, which consequently enhanced the ERBB2 expression and reduced H/R-induced hepatocyte apoptosis and inflammation.

CONCLUSIONS

Overall, these findings highlighted that YY1 repressed the miR-181a-5p expression and stimulated ESR1-mediated activation of ERBB2, thereby ameliorating liver I/RI. This study provides insight into the development of novel targets for liver I/RI.

Circulating miR-181a as a novel potential plasma biomarker for multimorbidity burden in the older population

Background

Chronic low-level inflammation is thought to play a role in many age-related diseases and to contribute to multimorbidity and to the disability related to this condition. In this framework, inflamma-miRs, an important subset of miRNA able to regulate inflammation molecules, appear to be key players. This study aimed to evaluate plasma levels of the inflamma-miR-181a in relation to age, parameters of health status (clinical, physical, and cognitive) and indices of multimorbidity in a cohort of 244 subjects aged 65- 97.

Methods

MiR-181a was isolated from plasma according to standardized procedures and its expression levels measured by qPCR. Correlation tests and multivariate regression analyses were applied on gender-stratified groups.

Results

MiR-181a levels resulted increased in old men, and significantly correlated with worsened blood parameters of inflammation (such as low levels of albumin and bilirubin and high lymphocyte content), particularly in females. Furthermore, we found miR-181a positively correlated with the overall multimorbidity burden, measured by CIRS Comorbidity Score, in both genders.

Conclusions

These data support a role of miR-181a in age-related chronic inflammation and in the development of multimorbidity in older adults and indicate that the routes by which this miRNA influence health status are likely to be gender specific. Based on our results, we suggest that miR-181a is a promising biomarker of health status of the older population.

Levels of the inflamma-miR-181a correlate with multimorbidity burden in older people.

MiR-181a levels correlate with blood inflammation markers in a gender-specific manner.

MiR-181a is positively correlated with age in males but not in females.

The paths by which miR-181a can influence health status likely differ between genders.

The Regulatory Effects of MicroRNAs on Tumor Immunity

MicroRNAs are endogenous noncoding small RNAs that posttranscriptionally regulate the expressions of their target genes. Accumulating research shows that miRNAs are crucial regulators of immune cell growth and antitumor immune response. Studies on miRNAs and tumors primarily focus on the tumor itself. At the same time, relatively few studies on the indirect regulatory effects of miRNAs in the development of tumors are achieved by affecting the immune system of tumor hosts and altering their immune responses. This review discusses the influence of miRNAs on the antitumor immune system.

Interaction between endogenous microRNAs and virus-derived small RNAs controls viral replication in insect vectors

MicroRNAs (miRNAs) play an important role in resisting virus infection in insects. Viruses are recognized by insect RNA interference systems, which generate virus-derived small RNAs (vsRNAs). To date, it is unclear whether viruses employ vsRNAs to regulate the expression of endogenous miRNAs. We previously found that miR-263a facilitated the proliferation of rice stripe virus (RSV) in the insect vector small brown planthopper. However, miR-263a was significantly downregulated by RSV. Here, we deciphered the regulatory mechanisms of RSV on miR-263a expression. The promoter region of miR-263a was characterized, and the transcription factor YY1 was found to negatively regulate the transcription of miR-263a. The nucleocapsid protein of RSV promoted the inhibitory effect of YY1 on miR-263a transcription by reducing the binding ability of RNA polymerase II to the promoter of miR-263a. Moreover, an RSV-derived small RNA, vsR-3397, downregulated miR-263a transcription by directly targeting the promoter region with partial sequence complementarity. The reduction in miR-263a suppressed RSV replication and was beneficial for maintaining a tolerable accumulation level of RSV in insect vectors. This dual regulation mechanism reflects an ingenious adaptation strategy of viruses to their insect vectors.

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.

Long non-coding RNA Gm37494 alleviates osteoarthritis chondrocyte injury via the microRNA-181a-5p/GABRA1 axis

Objective

This study was conducted to investigate the effect of long non-coding RNA (lncRNA) Gm37494 on osteoarthritis (OA) and its related molecular mechanism.

Methods

The cartilage tissues were obtained from OA patients, and an OA mouse model was induced by the destabilization of the medial meniscus, followed by measurement of Gm37494, microRNA (miR)-181a-5p, GABRA1 mRNA, and the encoded GABA_AR_α1 protein expression. Thereafter, a cellular model was induced by interleukin-1β (IL-1β) treatment in chondrocytes, followed by ectopic and silencing experiments. Chondrocyte proliferation was detected by CCK-8 and EdU assays, chondrocyte apoptosis by flow cytometry and western blot, and the levels of inflammatory factors by ELISA. The binding of Gm37494 to miR-181a-5p was evaluated by dual-luciferase reporter gene and RIP assays, and that of GABRA1 to miR-181a-5p by dual-luciferase reporter gene and RNA pull-down assays.

Results

OA patients and mice had decreased GABRA1 mRNA and GABA_AR_α1 protein levels and elevated miR-181a-5p expression in cartilage tissues. Additionally, Gm37494 was poorly expressed in OA mice. Mechanistically, Gm37494 directly bound to and inversely modulated miR-181a-5p that negatively targeted GABRA1. In IL-1β-induced chondrocytes, Gm37494 overexpression enhanced cell proliferation and suppressed cell apoptosis and inflammation, whereas further miR-181a-5p up-regulation or GABRA1 silencing abolished these trends.

Conclusions

Conclusively, Gm37494 elevated GABRA1 expression by binding to miR-181a-5p, thus ameliorating OA-induced chondrocyte damage.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13018-022-03202-5.

Immunomodulatory Effects of α-Tocopherol on the H1N1 Influenza Vaccine: Improving the Potency and Efficacy of the Influenza Vaccine in Aged Mice

Declined immune response is the main cause of decreased potency of the influenza vaccine in the elderly, regardless of virus mutations. Herein, we hypothesized that the addition of α-tocopherol to the influenza vaccine formulation might increase vaccine potency and efficacy. Hemagglutinin of the H1N1 virus was formulated in Alum and α-tocopherol, and then aged (16-20-month-old) and young (6-8-week-old) mice were immunized subcutaneously two times with 2-week intervals with 5 μg of different vaccine formulations. Two weeks after the final boosting, IFN-γ and IL-4 cytokines were assessed by using ELISA. Humoral immune responses were assessed by hemagglutination inhibition (HI). In addition, vaccine efficacy was determined by intranasal viral challenge of mice using mouse-adapted H1N1 virus. Our results showed that the new vaccine formulation improved IFN-γ and IL-4 responses in the experimental mice. However, the increase was evident mainly in the aged group and, to some extent, in the young group. Results from the HI assay showed that α-tocopherol in the vaccine formulation could increase HI activity in both young and aged mice. Furthermore, α-tocopherol, as an adjuvant, increased the protectivity of the influenza vaccine in both aged and young groups through the decreased lung viral load and increased survival rate of the experimental mice. In conclusion, it seems that α-tocopherol can not only be used as an appropriate adjuvant for aged people, but also empower old and worn out cells to increase the effectiveness of the vaccine in the elderly.

Mechanisms underpinning poor antibody responses to vaccines in ageing

Vaccines are a highly effective intervention for conferring protection against infections and reducing the associated morbidity and mortality in vaccinated individuals. However, ageing is often associated with a functional decline in the immune system that results in poor antibody production in older individuals after vaccination. A key contributing factor of this age-related decline in vaccine efficacy is the reduced size and function of the germinal centre (GC) response. GCs are specialised microstructures where B cells undergo affinity maturation and diversification of their antibody genes, before differentiating into long-lived antibody-secreting plasma cells and memory B cells. The GC response requires the coordinated interaction of many different cell types, including B cells, T follicular helper (Tfh) cells, T follicular regulatory (Tfr) cells and stromal cell subsets like follicular dendritic cells (FDCs). This review discusses how ageing affects different components of the GC reaction that contribute to its limited output and ultimately impaired antibody responses in older individuals after vaccination. An understanding of the mechanisms underpinning the age-related decline in the GC response is crucial in informing strategies to improve vaccine efficacy and extend the healthy lifespan amongst older people.

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.

Nuclear Sirtuins and the Aging of the Immune System

The immune system undergoes major changes with age that result in altered immune populations, persistent inflammation, and a reduced ability to mount effective immune responses against pathogens and cancer cells. Aging-associated changes in the immune system are connected to other age-related diseases, suggesting that immune system rejuvenation may provide a feasible route to improving overall health in the elderly. The Sir2 family of proteins, also called sirtuins, have been broadly implicated in genome homeostasis, cellular metabolism, and aging. Sirtuins are key responders to cellular and environmental stress and, in the case of the nuclear sirtuins, they do so by directing responses to chromatin that include gene expression regulation, retrotransposon repression, enhanced DNA damage repair, and faithful chromosome segregation. In the immune system, sirtuins instruct cellular differentiation from hematopoietic precursors and promote leukocyte polarization and activation. In hematopoietic stem cells, sirtuins safeguard quiescence and stemness to prevent cellular exhaustion. Regulation of cytokine production, which, in many cases, requires NF-κB regulation, is the best-characterized mechanism by which sirtuins control innate immune reactivity. In adaptive immunity, sirtuins promote T cell subset differentiation by controlling master regulators, thereby ensuring an optimal balance of helper (Th) T cell-dependent responses. Sirtuins are very important for immune regulation, but the means by which they regulate immunosenescence are not well understood. This review provides an integrative overview of the changes associated with immune system aging and its potential relationship with the roles of nuclear sirtuins in immune cells and overall organismal aging. Given the anti-aging properties of sirtuins, understanding how they contribute to immune responses is of vital importance and may help us develop novel strategies to improve immune performance in the aging organism.

Hormetic effect of low doses of rapamycin triggers anti-aging cascades in WRL-68 cells by modulating an mTOR-mitochondria cross-talk

BACKGROUND

Rapamycin is hormetic in nature-it demonstrates contrasting effects at high and low doses. It is toxic at moderate/high doses, while it can restrain aging and extend lifespan at low doses. However, it is not fully understood how rapamycin governs cellular aging. On the other hand, aging is putatively correlated to mitochondrial dysregulation. Although previous studies have suggested that hormetic (low) doses of rapamycin can cause partial/incomplete inhibition of mTOR, the actual modus operandi of how such partial mTOR inhibition might modulate the mTOR-mitochondria cross-talk remained to be deciphered in the context of cellular aging. The present study was designed to understand the hormetic effects of rapamycin on cellular factors that govern aging-associated changes in mitochondrial facets, such as functional and metabolic homeostases, sustenance of membrane potential, biogenesis, mitophagy, and oxidative injury to mitochondrial macromolecules.

METHODS AND RESULTS

WRL-68 cells treated (24 h) with variable doses of rapamycin were studied for estimating their viability, apoptosis, senescence, mitochondrial density and Δψm. Expression levels of key functional proteins were estimated by immunofluorescence/immunoblots. Oxidative damage to mtDNA/mtRNA/proteins was measured in mitochondrial lysates. We demonstrated that hormetic doses (0.1 and 1 nM) of rapamycin can alleviate aging-associated mitochondrial dyshomeostasis in WRL-68 cells, such as oxidative injury to mitochondrial nucleic acids and proteins, as well as disequilibrium of mitochondrial density, membrane potential, biogenesis, mitophagy and overall metabolism.

CONCLUSIONS

We established that low doses of rapamycin can hormetically amend the mTOR-mitochondria cross-talk, and can consequently promote anti-aging outcome in cells.

An update on the roles of immune system-derived microRNAs in cardiovascular diseases

Cardiovascular diseases (CVD) are a leading cause of human death worldwide. Over the past two decades, the emerging field of cardioimmunology has demonstrated how cells of the immune system play vital roles in the pathogenesis of CVD. MicroRNAs (miRNAs) are critical regulators of cellular identity and function. Cell-intrinsic, as well as cell-extrinsic, roles of immune and inflammatory cell-derived miRNAs have been, and continue to be, extensively studied. Several 'immuno-miRNAs' appear to be specifically expressed or demonstrate greatly enriched expression within leucocytes. Identification of miRNAs as critical regulators of immune system signalling pathways has posed the question of whether and how targeting these molecules therapeutically, may afford opportunities for disease treatment and/or management. As the field of cardioimmunology rapidly continues to advance, this review discusses findings from recent human and murine studies which contribute to our understanding of how leucocytes of innate and adaptive immunity are regulated-and may also regulate other cell types, via the actions of the miRNAs they express, in the context of CVD. Finally, we focus on available information regarding miRNA regulation of regulatory T cells and argue that targeted manipulation of miRNA regulated pathways in these cells may hold therapeutic promise for the treatment of CVD and associated risk factors.

Deficiency of MicroRNA-181a Results in Transcriptome-Wide Cell-Specific Changes in the Kidney and Increases Blood Pressure

[Figure: see text].

Noncoding RNAs link metabolic reprogramming to immune microenvironment in cancers

Altered metabolic patterns in tumor cells not only meet their own growth requirements but also shape an immunosuppressive microenvironment through multiple mechanisms. Noncoding RNAs constitute approximately 60% of the transcriptional output of human cells and have been shown to regulate numerous cellular processes under developmental and pathological conditions. Given their extensive action mechanisms based on motif recognition patterns, noncoding RNAs may serve as hinges bridging metabolic activity and immune responses. Indeed, recent studies have shown that microRNAs, long noncoding RNAs and circRNAs are widely involved in tumor metabolic rewiring, immune cell infiltration and function. Hence, we summarized existing knowledge of the role of noncoding RNAs in the remodeling of tumor metabolism and the immune microenvironment, and notably, we established the TIMELnc manual, which is a free and public manual for researchers to identify pivotal lncRNAs that are simultaneously correlated with tumor metabolism and immune cell infiltration based on a bioinformatic approach.

MicroRNAs as Factors in Bidirectional Crosstalk Between Mitochondria and the Nucleus During Cellular Senescence

Mitochondria are essential organelles that generate most of the chemical energy to power the cell through ATP production, thus regulating cell homeostasis. Although mitochondria have their own independent genome, most of the mitochondrial proteins are encoded by nuclear genes. An extensive bidirectional communication network between mitochondria and the nucleus has been discovered, thus making them semi-autonomous organelles. The nucleus-to-mitochondria signaling pathway, called Anterograde Signaling Pathway can be deduced, since the majority of mitochondrial proteins are encoded in the nucleus, less is known about the opposite pathway, the so-called mitochondria-to-nucleus retrograde signaling pathway. Several studies have demonstrated that non-coding RNAs are essential "messengers" of this communication between the nucleus and the mitochondria and that they might have a central role in the coordination of important mitochondrial biological processes. In particular, the finding of numerous miRNAs in mitochondria, also known as mitomiRs, enabled insights into their role in mitochondrial gene transcription. MitomiRs could act as important mediators of this complex crosstalk between the nucleus and the mitochondria. Mitochondrial homeostasis is critical for the physiological processes of the cell. Disruption at any stage in their metabolism, dynamics and bioenergetics could lead to the production of considerable amounts of reactive oxygen species and increased mitochondrial permeability, which are among the hallmarks of cellular senescence. Extensive changes in mitomiR expression and distribution have been demonstrated in senescent cells, those could possibly lead to an alteration in mitochondrial homeostasis. Here, we discuss the emerging putative roles of mitomiRs in the bidirectional communication pathways between mitochondria and the nucleus, with a focus on the senescence-associated mitomiRs.

Role of miRNA and lncRNAs in organ fibrosis and aging

Fibrosis is the endpoint of pathological remodeling. This process contributes to the pathogenesis of several chronic disorders and aging-associated organ damage. Different molecular cascades contribute to this process. TGF-β, WNT, and YAP/TAZ signaling pathways have prominent roles in this process. A number of long non-coding RNAs and microRNAs have been found to regulate organ fibrosis through modulation of the activity of related signaling pathways. miR-144-3p, miR-451, miR-200b, and miR-328 are among microRNAs that participate in the pathology of cardiac fibrosis. Meanwhile, miR-34a, miR-17-5p, miR-122, miR-146a, and miR-350 contribute to liver fibrosis in different situations. PVT1, MALAT1, GAS5, NRON, PFL, MIAT, HULC, ANRIL, and H19 are among long non-coding RNAs that participate in organ fibrosis. We review the impact of long non-coding RNAs and microRNAs in organ fibrosis and aging-related pathologies.

ACE2 Netlas: In silico Functional Characterization and Drug-Gene Interactions of ACE2 Gene Network to Understand Its Potential Involvement in COVID-19 Susceptibility

Angiotensin-converting enzyme-2 (ACE2) receptor has been identified as the key adhesion molecule for the transmission of the SARS-CoV-2. However, there is no evidence that human genetic variation in ACE2 is singularly responsible for COVID-19 susceptibility. Therefore, we performed an integrative multi-level characterization of genes that interact with ACE2 (ACE2-gene network) for their statistically enriched biological properties in the context of COVID-19. The phenome-wide association of 51 genes including ACE2 with 4,756 traits categorized into 26 phenotype categories, showed enrichment of immunological, respiratory, environmental, skeletal, dermatological, and metabolic domains (p < 4e-4). Transcriptomic regulation of ACE2-gene network was enriched for tissue-specificity in kidney, small intestine, and colon (p < 4.7e-4). Leveraging the drug-gene interaction database we identified 47 drugs, including dexamethasone and spironolactone, among others. Considering genetic variants within ± 10 kb of ACE2-network genes we identified miRNAs whose binding sites may be altered as a consequence of genetic variation. The identified miRNAs revealed statistical over-representation of inflammation, aging, diabetes, and heart conditions. The genetic variant associations in RORA, SLC12A6, and SLC6A19 genes were observed in genome-wide association study (GWAS) of COVID-19 susceptibility. We also report the GWAS-identified variant in 3p21.31 locus, serves as trans-QTL for RORA and RORC genes. Overall, functional characterization of ACE2-gene network highlights several potential mechanisms in COVID-19 susceptibility. The data can also be accessed at https://gpwhiz.github.io/ACE2Netlas/.

A microRNA expression and regulatory element activity atlas of the mouse immune system

To better define the control of immune system regulation, we generated an atlas of microRNA (miRNA) expression from 63 mouse immune cell populations and connected these signatures with assay for transposase-accessible chromatin using sequencing (ATAC-seq), chromatin immunoprecipitation followed by sequencing (ChIP-seq) and nascent RNA profiles to establish a map of miRNA promoter and enhancer usage in immune cells. miRNA complexity was relatively low, with >90% of the miRNA compartment of each population comprising <75 miRNAs; however, each cell type had a unique miRNA signature. Integration of miRNA expression with chromatin accessibility revealed putative regulatory elements for differentially expressed miRNAs, including miR-21a, miR-146a and miR-223. The integrated maps suggest that many miRNAs utilize multiple promoters to reach high abundance and identified dominant and divergent miRNA regulatory elements between lineages and during development that may be used by clustered miRNAs, such as miR-99a/let-7c/miR-125b, to achieve distinct expression. These studies, with web-accessible data, help delineate the cis-regulatory elements controlling miRNA signatures of the immune system.

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.

TP73-AS1 is induced by YY1 during TMZ treatment and highly expressed in the aging brain

Aging is a factor associated with poor prognosis in glioblastoma (GBM). It is therefore important to understand the molecular features of aging contributing to GBM morbidity. TP73-AS1 is a long noncoding RNA (lncRNA) over expressed in GBM tumors shown to promote resistance to the chemotherapeutic temozolomide (TMZ), and tumor aggressiveness. How the expression of TP73-AS1 is regulated is not known, nor is it known if its expression is associated with aging. By analyzing transcriptional data obtained from natural and pathological aging brain, we found that the expression of TP73-AS1 is high in pathological and naturally aging brains. YY1 physically associates with the promoter of TP73-AS1 and we found that along with TP73-AS1, YY1 is induced by TMZ. We found that the TP73-AS1 promoter is activated by TMZ, and by YY1 over expression. Using CRISPRi to deplete YY1, we found that YY1 promotes up regulation of TP73-AS1 and the activation of its promoter during TMZ treatment. In addition, we identified two putative YY1 binding sites within the TP73-AS1 promoter, and used mutagenesis to find that they are essential for TMZ mediated promoter activation. Together, our data positions YY1 as an important TP73-AS1 regulator, demonstrating that TP73-AS1 is expressed in the natural and pathological aging brain, including during neurodegeneration and cancer. Our findings advance our understanding of TP73-AS1 expression, bringing forth a new link between TMZ resistance and aging, both of which contribute to GBM morbidity.

Histone deficiency and accelerated replication stress in T cell aging

With increasing age, individuals are more vulnerable to viral infections such as with influenza or the SARS-CoV-2 virus. One age-associated defect in human T cells is the reduced expression of miR-181a. miR-181ab1 deficiency in peripheral murine T cells causes delayed viral clearance after infection, resembling human immune aging. Here we show that naive T cells from older individuals as well as miR-181ab1-deficient murine T cells develop excessive replication stress after activation, due to reduced histone expression and delayed S-phase cell cycle progression. Reduced histone expression was caused by the miR-181a target SIRT1 that directly repressed transcription of histone genes by binding to their promoters and reducing histone acetylation. Inhibition of SIRT1 activity or SIRT1 silencing increased histone expression, restored cell cycle progression, diminished the replication-stress response, and reduced the production of inflammatory mediators in replicating T cells from old individuals. Correspondingly, treatment with SIRT1 inhibitors improved viral clearance in mice with miR-181a-deficient T cells after LCMV infection. In conclusion, SIRT1 inhibition may be beneficial to treat systemic viral infection in older individuals by targeting antigen-specific T cells that develop replication stress due to miR-181a deficiency.

Hallmarks of T cell aging

The aged adaptive immune system is characterized by progressive dysfunction as well as increased autoimmunity. This decline is responsible for elevated susceptibility to infection and cancer, as well as decreased vaccination efficacy. Recent evidence indicates that CD4⁺ T cell-intrinsic alteratins contribute to chronic inflammation and are sufficient to accelerate an organism-wide aging phenotype, supporting the idea that T cell aging plays a major role in body-wide deterioration. In this Review, we propose ten molecular hallmarks to represent common denominators of T cell aging. These hallmarks are grouped into four primary hallmarks (thymic involution, mitochondrial dysfunction, genetic and epigenetic alterations, and loss of proteostasis) and four secondary hallmarks (reduction of the TCR repertoire, naive-memory imbalance, T cell senescence, and lack of effector plasticity), and together they explain the manifestation of the two integrative hallmarks (immunodeficiency and inflammaging). A major challenge now is weighing the relative impact of these hallmarks on T cell aging and understanding their interconnections, with the final goal of defining molecular targets for interventions in the aging process.

Ageing of T-dependent B cell responses

The human immune system is in continuous interaction with environmental factors (pathogens, exercise, stress, pollutants, diet, vaccines, and therapeutics) that condition its efficiency by promoting or moderating multiple immune mechanisms. While the deleterious impact of external factors can be avoided or limited, the immune system itself grows weaker with age. Immune cells persist in the elderly, and the observed decline of cellular immunity is related to cellular senescence. Immunosenescence, which affects both T and B cells, erodes lymphocyte-dependent responses to vaccines and pathogens. Germinal centers (GCs), the organized lymphoid structures where B cells engage in affinity maturation, are regulated by follicular helper (Tfh) and follicular regulatory (Tfr) T cells, the major T cell components of GCs. This review discusses how age-related changes affect Tfh and Tfr cells as key components of B cell immunity, and how they ultimately shape the response of the ageing immune system to vaccines and infectious challenges.

Remodeling of Stromal Cells and Immune Landscape in Microenvironment During Tumor Progression

The molecular understanding of carcinogenesis and tumor progression rests in intra and inter-tumoral heterogeneity. Solid tumors confined with vast diversity of genetic abnormalities, epigenetic modifications, and environmental cues that differ at each stage from tumor initiation, progression, and metastasis. Complexity within tumors studied by conventional molecular techniques fails to identify different subclasses in stromal and immune cells in individuals and that affects immunotherapies. Here we focus on diversity of stromal cell population and immune inhabitants, whose subtypes create the complexity of tumor microenvironment (TME), leading primary tumors towards advanced-stage cancers. Recent advances in single-cell sequencing (epitope profiling) approach circumscribes phenotypic markers, molecular pathways, and evolutionary trajectories of an individual cell. We discussed the current knowledge of stromal and immune cell subclasses at different stages of cancer development with the regulatory role of non-coding RNAs. Finally, we reported the current therapeutic options in immunotherapies, advances in therapies targeting heterogeneity, and possible outcomes.

Arachidonic acid-regulated calcium signaling in T cells from patients with rheumatoid arthritis promotes synovial inflammation

Rheumatoid arthritis (RA) and psoriatic arthritis (PsA) are two distinct autoimmune diseases that manifest with chronic synovial inflammation. Here, we show that CD4⁺ T cells from patients with RA and PsA have increased expression of the pore-forming calcium channel component ORAI3, thereby increasing the activity of the arachidonic acid-regulated calcium-selective (ARC) channel and making T cells sensitive to arachidonic acid. A similar increase does not occur in T cells from patients with systemic lupus erythematosus. Increased ORAI3 transcription in RA and PsA T cells is caused by reduced IKAROS expression, a transcriptional repressor of the ORAI3 promoter. Stimulation of the ARC channel with arachidonic acid induces not only a calcium influx, but also the phosphorylation of components of the T cell receptor signaling cascade. In a human synovium chimeric mouse model, silencing ORAI3 expression in adoptively transferred T cells from patients with RA attenuates tissue inflammation, while adoptive transfer of T cells from healthy individuals with reduced expression of IKAROS induces synovitis. We propose that increased ARC activity due to reduced IKAROS expression makes T cells more responsive and contributes to chronic inflammation in RA and PsA.

ORAI3 is part of pore forming calcium channels involved in T cell activation. Here the authors show that there is increased expression of ORAI3 in T cells from patients with rheumatoid arthritis and that the transcription factor IKAROS negatively regulates the ORAI3 promoter, indicating a regulatory loop that can control auto-reactivity of T cells in these patients.

The GSK3β-β-catenin-TCF1 pathway improves naive T cell activation in old adults by upregulating miR-181a

MicroRNAs play an important role in the regulation of T cell development, activation, and differentiation. One of the most abundant microRNAs in lymphocytes is miR-181a, which controls T cell receptor (TCR) activation thresholds in thymic selection as well as in peripheral T cell responses. We previously found that miR-181a levels decline in T cells in the elderly. In this study, we identified TCF1 as a transcriptional regulator of pri-miR-181a. A decline in TCF1 levels in old individuals accounted for the reduced miR-181a expression impairing TCR signaling. Inhibition of GSK3ß restored expression of miR-181a by inducing TCF1 in T cells from old adults. GSK3ß inhibition enhanced TCR signaling to increase downstream expression of activation markers and production of IL-2. The effect involved the upregulation of miR-181a and the inhibition of DUSP6 expression. Thus, inhibition of GSK3ß can restore responses of old T cells by inducing miR-181a expression through TCF1.

Ageing promotes early T follicular helper cell differentiation by modulating expression of RBPJ

Ageing profoundly changes our immune system and is thought to be a driving factor in the morbidity and mortality associated with infectious disease in older people. We have previously shown that the impaired immunity to vaccination that occurs in aged individuals is partly attributed to the effect of age on T follicular helper (Tfh) cell formation. In this study, we examined how age intrinsically affects Tfh cell formation in both mice and humans. We show increased formation of Tfh precursors (pre-Tfh) but no associated increase in germinal centre (GC)-Tfh cells in aged mice, suggesting age-driven promotion of only early Tfh cell differentiation. Mechanistically, we show that ageing alters TCR signalling which drives expression of the Notch-associated transcription factor, RBPJ. Genetic or chemical modulation of RBPJ or Notch rescues this age-associated early Tfh cell differentiation, and increased intrinsic Notch activity recapitulates this phenomenon in younger mice. Our data offer mechanistic insight into the age-induced changes in T-cell activation that affects the differentiation and ultimately the function of effector T cells.

Altered Ca2+ Homeostasis in Immune Cells during Aging: Role of Ion Channels

Aging is an unstoppable process and begins shortly after birth. Each cell of the organism is affected by the irreversible process, not only with equal density but also at varying ages and with different speed. Therefore, aging can also be understood as an adaptation to a continually changing cellular environment. One of these very prominent changes in age affects Ca²⁺ signaling. Especially immune cells highly rely on Ca²⁺-dependent processes and a strictly regulated Ca²⁺ homeostasis. The intricate patterns of impaired immune cell function may represent a deficit or compensatory mechanisms. Besides, altered immune function through Ca²⁺ signaling can profoundly affect the development of age-related disease. This review attempts to summarize changes in Ca²⁺ signaling due to channels and receptors in T cells and beyond in the context of aging.

Distinct Age-Related Epigenetic Signatures in CD4 and CD8 T Cells

Healthy immune aging is in part determined by how well the sizes of naïve T cell compartments are being maintained with advancing age. Throughout adult life, replenishment largely derives from homeostatic proliferation of existing naïve and memory T cell populations. However, while the subpopulation composition of CD4 T cells is relatively stable, the CD8 T cell compartment undergoes more drastic changes with loss of naïve CD8 T cells and accumulation of effector T cells, suggesting that CD4 T cells are more resilient to resist age-associated changes. To determine the epigenetic basis for these differences in behaviors, we compared chromatin accessibility maps of CD4 and CD8 T cell subsets from young and old individuals and related the results to the expressed transcriptome. The dominant age-associated signatures resembled hallmarks of differentiation, which were more pronounced for CD8 naïve and memory than the corresponding CD4 T cell subsets, indicating that CD8 T cells are less able to keep cellular quiescence upon homeostatic proliferation. In parallel, CD8 T cells from old adults, irrespective of their differentiation state, displayed greater reduced accessibility to genes of basic cell biological function, including genes encoding ribosomal proteins. One possible mechanism is the reduced expression of the transcription factors YY1 and NRF1. Our data suggest that chromatin accessibility signatures can be identified that distinguish CD4 and CD8 T cells from old adults and that may confer the higher resilience of CD4 T cells to aging.

ACE2 Netlas: In-silico functional characterization and drug-gene interactions of ACE2 gene network to understand its potential involvement in COVID-19 susceptibility

Angiotensin-converting enzyme-2 ( ACE2 ) receptor has been identified as the key adhesion molecule for the transmission of the SARS-CoV-2. However, there is no evidence that human genetic variation in ACE2 is singularly responsible for COVID-19 susceptibility. Therefore, we performed a multi-level characterization of genes that interact with ACE2 (ACE2-gene network) for their over-represented biological properties in the context of COVID-19. The phenome-wide association of 51 genes including ACE2 with 4,756 traits categorized into 26 phenotype categories, showed enrichment of immunological, respiratory, environmental, skeletal, dermatological, and metabolic domains (p<4e-4). Transcriptomic regulation of ACE2-gene network was enriched for tissue-specificity in kidney, small intestine, and colon (p<4.7e-4). Leveraging the drug-gene interaction database we identified 47 drugs, including dexamethasone and spironolactone, among others. Considering genetic variants within ± 10 kb of ACE2-network genes we characterized functional consequences (among others) using miRNA binding-site targets. MiRNAs affected by ACE2-network variants revealed statistical over-representation of inflammation, aging, diabetes, and heart conditions. With respect to variants mapped to the ACE2-network, we observed COVID-19 related associations in RORA, SLC12A6 and SLC6A19 genes. Overall, functional characterization of ACE2-gene network highlights several potential mechanisms in COVID-19 susceptibility. The data can also be accessed at https://gpwhiz.github.io/ACE2Netlas/.

The Transcription Factor TCF1 in T Cell Differentiation and Aging

The transcription factor T cell factor 1 (TCF1), a pioneer transcription factor as well as a downstream effector of WNT/β-catenin signaling, is indispensable for T cell development in the thymus. Recent studies have highlighted the additional critical role of TCF1 in peripheral T cell responses to acute and chronic infections as well as cancer. Here, we review the regulatory functions of TCF1 in the differentiation of T follicular helper cells, memory T cells and recently described stem-like exhausted T cells, where TCF1 promotes less differentiated stem-like cell states by controlling common gene-regulatory networks. These studies also provide insights into the mechanisms of defective T cell responses in older individuals. We discuss alterations in TCF1 expression and related regulatory networks with age and their consequences for T cell responses to infections and vaccination. The increasing understanding of the pathways regulating TCF1 expression and function in aged T cells holds the promise of enabling the design of therapeutic interventions aiming at improving T cell responses in older individuals.