Naive T cell maintenance and function in human aging

Shelterin dysfunction promotes CD4+ T cell senescence in Behçet's disease

OBJECTIVES

To investigate the potential role of shelterin dysfunction in naïve CD4+ T cells in the pathogenesis of Behçet's disease (BD).

METHODS

Naïve CD4+ T cells were isolated from 40 BD patients and 40 sex- and age-matched healthy controls (HC). Senescent profiles, shelterin subunits expression, telomere length, telomerase activity and critical DNA damage response (DDR) were evaluated. Telomere repeat factor-2 (TRF2) silencing was conducted for further validation.

RESULTS

Compared with HC, BD patients had significantly decreased naïve CD4+ T cells, increased cell apoptosis, senescence, and productions of TNF-α and IFN-γ upon activation. Notably, BD naïve CD4+ T cells had shortened telomere, impaired telomerase activity, and expressed lower levels of shelterin subunits TRF2, TRF1- and TRF2-Interacting Nuclear Protein 2 (TIN2) and Repressor/Activator Protein 1 (RAP1). Furthermore, BD naïve CD4+ T cells exhibited significantly increased DDR, evidenced by elevated phosphorylated ataxia telangiectasia (AT) mutated (pATM), phosphorylated p53 (pp53) and p21. Finally, TRF2 silencing markedly upregulated DDR, apoptosis and proinflammatory cytokines production in HC naïve CD4+ T cells.

CONCLUSION

Our study demonstrated that TRF2 deficiency in BD naïve CD4+ T cells promoted cell apoptosis and senescence, leading to proinflammatory cytokines overproduction. Therefore, restoring TRF2 might be a promising therapeutic strategy for BD.

Multidimensional profiling of human T cells reveals high CD38 expression, marking recent thymic emigrants and age-related naive T cell remodeling

Thymic involution is a key factor in human immune aging, leading to reduced thymic output and a decline in recent thymic emigrant (RTE) naive T cells in circulation. Currently, the precise definition of human RTEs and their corresponding cell surface markers lacks clarity. Analysis of single-cell RNA-seq/ATAC-seq data distinguished RTEs by the expression of SOX4, IKZF2, and TOX and CD38 protein, whereby surface CD38hi expression universally identified CD8+ and CD4+ RTEs. We further determined the dynamics of RTEs and mature cells in a cohort of 158 individuals, including age-associated transcriptional reprogramming and shifts in cytokine production. Spectral cytometry profiling revealed two axes of aging common to naive CD8+ and CD4+ T cells: (1) a decrease in CD38++ cells (RTEs) and (2) an increase in CXCR3hi cells. Identification of RTEs enables direct assessment of thymic health. Furthermore, resolving the dynamics of naive T cell remodeling yields insight into vaccination and infection responsiveness throughout aging.

Distinctive evolution of alveolar T cell responses is associated with clinical outcomes in unvaccinated patients with SARS-CoV-2 pneumonia

The evolution of T cell molecular signatures in the distal lung of patients with severe pneumonia is understudied. Here, we analyzed T cell subsets in longitudinal bronchoalveolar lavage fluid samples from 273 patients with severe pneumonia, including unvaccinated patients infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) or with respiratory failure not linked to pneumonia. In patients with SARS-CoV-2 pneumonia, activation of interferon signaling pathways, low activation of the NF-κB pathway and preferential targeting of spike and nucleocapsid proteins early after intubation were associated with favorable outcomes, whereas loss of interferon signaling, activation of NF-κB-driven programs and specificity for the ORF1ab complex late in disease were associated with mortality. These results suggest that in patients with severe SARS-CoV-2 pneumonia, alveolar T cell interferon responses targeting structural SARS-CoV-2 proteins characterize individuals who recover, whereas responses against nonstructural proteins and activation of NF-κB are associated with poor outcomes.

The RESIST Senior Individuals Cohort: Design, participant characteristics and aims

The number of older adults worldwide is growing exponentially. However, while living longer, older individuals are more susceptible to both non-infectious and infectious diseases, at least in part due to alterations of the immune system. Here, we report on a prospective cohort study investigating the influence of age on immune responses and susceptibility to infection. The RESIST Senior Individuals (SI) cohort was established as a general population cohort with a focus on the elderly, enrolling an age- and sex-stratified sample of 650 individuals (n = 100 20-39y, n = 550 61-94y, 2019-2023, Hannover, Germany). It includes clinical, demographic, and lifestyle data and also extensive biomaterial sampling. Initial insights indicate that the SI cohort exhibits characteristics of the aging immune system and the associated susceptibility to infection, thereby providing a suitable platform for the decoding of age-related alterations of the immune system and unraveling the molecular mechanisms underlying the impaired immune responsiveness in aging populations by exploring comprehensive, unbiased multi-omics datasets.

Chronic TNF in the aging microenvironment exacerbates Tet2 loss-of-function myeloid expansion

ABSTRACT

Somatic mutations in the TET2 gene occur more frequently with age, imparting an intrinsic hematopoietic stem cells (HSCs) advantage and contributing to a phenomenon termed clonal hematopoiesis of indeterminate potential (CHIP). Individuals with TET2-mutant CHIP have a higher risk of developing myeloid neoplasms and other aging-related conditions. Despite its role in unhealthy aging, the extrinsic mechanisms driving TET2-mutant CHIP clonal expansion remain unclear. We previously showed an environment containing tumor necrosis factor (TNF) favors TET2-mutant HSC expansion in vitro. We therefore postulated that age-related increases in TNF also provide an advantage to HSCs with TET2 mutations in vivo. To test this hypothesis, we generated mixed bone marrow chimeric mice of old wild-type (WT) and TNF-/- genotypes reconstituted with WT CD45.1+ and Tet2-/- CD45.2+ HSCs. We show that age-associated increases in TNF dramatically increased the expansion of Tet2-/- cells in old WT recipient mice, with strong skewing toward the myeloid lineage. This aberrant myelomonocytic advantage was mitigated in old TNF-/- recipient mice, suggesting that TNF signaling is essential for the expansion Tet2-mutant myeloid clones. Examination of human patients with rheumatoid arthritis with clonal hematopoiesis revealed that hematopoietic cells carrying certain mutations, including in TET2, may be sensitive to reduced TNF bioactivity following blockade with adalimumab. This suggests that targeting TNF may reduce the burden of some forms of CHIP. To our knowledge, this is the first evidence to demonstrate that TNF has a causal role in driving TET2-mutant CHIP in vivo. These findings highlight TNF as a candidate therapeutic target to control TET2-mutant CHIP.

Development of an epigenetic clock resistant to changes in immune cell composition

Epigenetic clocks are age predictors that use machine-learning models trained on DNA CpG methylation values to predict chronological or biological age. Increases in predicted epigenetic age relative to chronological age (epigenetic age acceleration) are connected to aging-associated pathologies, and changes in epigenetic age are linked to canonical aging hallmarks. However, epigenetic clocks rely on training data from bulk tissues whose cellular composition changes with age. Here, we found that human naive CD8+ T cells, which decrease in frequency during aging, exhibit an epigenetic age 15-20 years younger than effector memory CD8+ T cells from the same individual. Importantly, homogenous naive T cells isolated from individuals of different ages show a progressive increase in epigenetic age, indicating that current epigenetic clocks measure two independent variables, aging and immune cell composition. To isolate the age-associated cell intrinsic changes, we created an epigenetic clock, the IntrinClock, that did not change among 10 immune cell types tested. IntrinClock shows a robust predicted epigenetic age increase in a model of replicative senescence in vitro and age reversal during OSKM-mediated reprogramming.

Immunosenescence-related T cell phenotypes and white matter in schizophrenia patients with tardive dyskinesia

Schizophrenia patients with tardive dyskinesia (TD) are associated with accelerated biological aging, immunological dysfunction, and premature morbidity and mortality. Older individuals are particularly vulnerable to TD development. As a characteristic of immunosenescence, alterations in the relative proportions of naïve or memory T cell subpopulations may be negatively or positively associated with brain structure abnormalities; however, whether these changes are correlated with TD remains unclear. In this study, we investigated correlations between distributions of T cell phenotypes and brain structure abnormalities (especially white matter) in schizophrenia patients with (TD) and without (NTD) TD (n = 50 and 58, respectively) relative to healthy controls (HC, n = 41). Immune markers, including naïve (CD45RA+), memory (CD45RO+), and apoptotic (CD95+) CD4+ and CD8+ T cells, were examined by flow cytometry, as were the intracellular levels of cytokines (interferon (IFN)-γ, interleukin (IL)-6, IL-1β, and tumor necrosis factor (TNF)-α) in CD8 + CD45RA + CD95+ and CD8 + CD45RO + CD95+ T cells. MRI was employed to evaluate the fractional anisotropy (FA) of white matter tracts and subcortical volumes, following published routines. The percentage of CD8 + CD45RO + CD95+ T cells was higher in TD compared with NTD and HC groups and correlated with the choroid plexus volume in TD group. The intracellular level of IFN-γ in CD8 + CD45RO + CD95+ T cells, the FA of the fornix/stria terminalis, and the pallidum volume were correlated with orofacial TD, whereas the FAs of the inferior fronto-occipital fasciculus, cingulum, and superior longitudinal fasciculus were correlated with limb-truncal TD. These findings provide preliminary evidence that the association between immunosenescence-related T cell subpopulations and brain structure may underline the pathological process of TD.

Real-World Assessment of Recommended COVID-19 Vaccination Waiting Period after Chemotherapy

There is a knowledge gap concerning the proper timing for COVID-19 vaccination in cancer patients undergoing chemotherapy. We aimed to evaluate the suitability of the guidelines that recommend waiting at least three months after undergoing chemotherapy before receiving a COVID-19 vaccine. This retrospective cohort study used aggregated data from the TriNetX US Collaboratory network. Participants were grouped into two groups based on the interval between chemotherapy and vaccination. The primary outcome assessed was infection risks, including COVID-19; skin, intra-abdominal, and urinary tract infections; pneumonia; and sepsis. Secondary measures included healthcare utilization and all causes of mortality. Kaplan-Meier analysis and the Cox proportional hazard model were used to calculate the cumulative incidence and hazard ratio (HR) and 95% confidence intervals for the outcomes. The proportional hazard assumption was tested with the generalized Schoenfeld approach. Four subgroup analyses (cancer type, vaccine brand, sex, age) were conducted. Sensitivity analyses were performed to account for competing risks and explore three distinct time intervals. Patients receiving a vaccine within three months after chemotherapy had a higher risk of COVID-19 infection (HR: 1.428, 95% CI: 1.035-1.970), urinary tract infection (HR: 1.477, 95% CI: 1.083-2.014), and sepsis (HR: 1.854, 95% CI: 1.091-3.152) compared to those who adhered to the recommendations. Hospital inpatient service utilization risk was also significantly elevated for the within three months group (HR: 1.692, 95% CI: 1.354-2.115). Adhering to a three-month post-chemotherapy waiting period reduces infection and healthcare utilization risks for cancer patients receiving a COVID-19 vaccine.

The aged tumor microenvironment limits T cell control of cancer

The etiology and effect of age-related immune dysfunction in cancer is not completely understood. Here we show that limited priming of CD8+ T cells in the aged tumor microenvironment (TME) outweighs cell-intrinsic defects in limiting tumor control. Increased tumor growth in aging is associated with reduced CD8+ T cell infiltration and function. Transfer of T cells from young mice does not restore tumor control in aged mice owing to rapid induction of T cell dysfunction. Cell-extrinsic signals in the aged TME drive a tumor-infiltrating age-associated dysfunctional (TTAD) cell state that is functionally, transcriptionally and epigenetically distinct from canonical T cell exhaustion. Altered natural killer cell-dendritic cell-CD8+ T cell cross-talk in aged tumors impairs T cell priming by conventional type 1 dendritic cells and promotes TTAD cell formation. Aged mice are thereby unable to benefit from therapeutic tumor vaccination. Critically, myeloid-targeted therapy to reinvigorate conventional type 1 dendritic cells can improve tumor control and restore CD8+ T cell immunity in aging.

Conventional Tregs in treatment-naïve rheumatoid arthritis are deficient in suppressive function with an increase in percentage of CXCR3 and CCR6 expressing Tregs

In rheumatoid arthritis (RA), immune homeostasis is maintained by T regulatory cells (Tregs) that in an inflammatory milieu can change towards T-helper-like phenotypes (Th-like Tregs). Our aim was to examine the phenotypic and functional characteristics of CD4+CD25+CD127lo/- Tregs, Th-like Tregs and T effector (Teff) cells in the peripheral blood (PB) and synovial fluid (SF) of treatment-naïve early RA, as compared to osteoarthritis (OA) and healthy control (HC) peripheral blood. Frequencies of Tregs, CXCR3, CCR6 expressing Tregs (Th-like Tregs), and Teff cells were analyzed using flow cytometry in RA (n = 80), OA (n = 20), and HC (n = 40). Cytokine concentrations of the respective T cell subsets in plasma and SF were measured using flow cytometric bead array. Tregs sorted from RA and HC PB using magnetic beads were analyzed for functional capacities by CFSE proliferation assay and FOXP3 gene expression using real-time PCR. We observed that the frequencies of Th17 cells in PB and SF were significantly higher in RA when compared to HC, whereas Tregs were lower in PB and high in SF compared to HC and OA respectively. Th1- and Th17-related pro-inflammatory cytokines IL12p70, INF-γ, TNF-α, and IL-6, and IL-17A were significantly higher in the plasma and SF of RA. Tregs expressing CXCR3 (Th1-like Tregs) and CCR6 (Th17-like Treg) were significantly higher in PB and SF of RA compared to controls and was positively associated with seropositivity and disease activity. Treg cells isolated from peripheral blood of RA showed decreased function and reduced FOXP3 gene expression compared to HC. In our study, we have demonstrated higher frequencies of Th1 and Th17 cells and increased circulatory and SF pro-inflammatory cytokines (IL12P70, INF-γ, IL-6, IL-17A, and TNF-α) in RA. This inflammatory milieu might alter total Tregs frequencies and influence conversion of Tregs into Th-like Tregs.

Alterations in Immune Responses Are Associated with Dysfunctional Intracellular Signaling in Peripheral Blood Mononuclear Cells of Men and Women with Mild Cognitive Impairment and Alzheimer's disease

Deficits in the neuroendocrine-immune network in the periphery associated with the onset and progression of mild cognitive impairment (MCI) and Alzheimer's disease (AD) have not been extensively studied. The present study correlatively examines the association between cell-mediated immune responses, stress hormones, amyloid precursor protein (APP) expression, peripheral blood mononuclear cells (PBMC), and intracellular signaling molecules in the pathophysiology of MCI and AD compared to adults. Serum APP, lymphocyte proliferation, total cholinesterase (TChE), butyrylcholinesterase (BChE) activities, cytokines (IL-2, IFN-γ, IL-6, and TNF-α), and intracellular signaling molecules (p-ERK, p-CREB, and p-Akt) were measured in the PBMCs of adult, old, MCI, and AD men and women initially and after 3 years in the same population. An age- and disease-associated decline in mini-mental state examination (MMSE) scores and lymphocyte proliferation of MCI and AD men and women were observed. An age- and disease-related increase in serum APP, cortisol levels, and TChE activity were observed in men and women. Enhanced production of Th1 cytokine, IL-2, pro-inflammatory cytokines, and suppressed intracellular transcription factors may promote the inflammatory environment in MCI and AD patients. The expression of CREB and Akt was lower in MCI and AD men, while the expression of p-ERK was higher, and p-CREB was lower in MCI and AD women after 3 years. These results suggest that changes in specific intracellular signaling pathways may influence alterations in cell-mediated immunity to promote disease progression in MCI and AD patients.

Immunosenescence and inflammaging: Conspiracies against alveolar bone turnover

OBJECTIVE

Inflammaging and immunosenescence are characteristics of senescent immune system alterations. This review provides insights into inflammaging and immunosenescence in periodontitis and focuses on the innerlink of inflammaging and immunosenescence in alveolar bone turnover from a perspective of cell-cell interaction.

METHODS

This review is conducted by a narrative approach to discuss the effect of inflammaging and immunosenescence in aging-related alveolar bone loss. A comprehensive literature research in PubMed and Google was applied to identify reports in English.

RESULTS

Inflammaging is concerned with abnormal M1 polarization and increasing circulating inflammatory cytokines, while immunosenescence involves reduced infection and vaccine responses, depressed antimicrobial function, and infiltration of aged B cells and memory T cells. TLR-mediated inflammaging and altered adaptive immunity significantly affect alveolar bone turnover and aggravate aging-related alveolar bone loss. Besides, energy consumption also plays a vital role in aged immune and skeletal system of periodontitis.

CONCLUSIONS

Senescent immune system exerts a significant function in aging-related alveolar bone loss. Inflammaging and immunosenescence interact functionally and mechanistically, which affects alveolar bone turnover. Therefore, further clinical treatment strategies targeting alveolar bone loss could be based on the specific molecular mechanism connecting inflammaging, immunosenescence, and alveolar bone turnover.

A multi-organ map of the human immune system across age, sex and ethnicity

Understanding tissue biology's heterogeneity is crucial for advancing precision medicine. Despite the centrality of the immune system in tissue homeostasis, a detailed and comprehensive map of immune cell distribution and interactions across human tissues and demographics remains elusive. To fill this gap, we harmonised data from 12,981 single-cell RNA sequencing samples and curated 29 million cells from 45 anatomical sites to create a comprehensive compositional and transcriptional healthy map of the healthy immune system. We used this resource and a novel multilevel modelling approach to track immune ageing and test differences across sex and ethnicity. We uncovered conserved and tissue-specific immune-ageing programs, resolved sex-dependent differential ageing and identified ethnic diversity in clinically critical immune checkpoints. This study provides a quantitative baseline of the immune system, facilitating advances in precision medicine. By sharing our immune map, we hope to catalyse further breakthroughs in cancer, infectious disease, immunology and precision medicine.

Insights into vaccines for elderly individuals: from the impacts of immunosenescence to delivery strategies

Immunosenescence increases the risk and severity of diseases in elderly individuals and leads to impaired vaccine-induced immunity. With aging of the global population and the emerging risk of epidemics, developing adjuvants and vaccines for elderly individuals to improve their immune protection is pivotal for healthy aging worldwide. Deepening our understanding of the role of immunosenescence in vaccine efficacy could accelerate research focused on optimizing vaccine delivery for elderly individuals. In this review, we analyzed the characteristics of immunosenescence at the cellular and molecular levels. Strategies to improve vaccination potency in elderly individuals are summarized, including increasing the antigen dose, preparing multivalent antigen vaccines, adding appropriate adjuvants, inhibiting chronic inflammation, and inhibiting immunosenescence. We hope that this review can provide a review of new findings with regards to the impacts of immunosenescence on vaccine-mediated protection and inspire the development of individualized vaccines for elderly individuals.

Predictors of prolonged length of stay in adult patients with respiratory syncytial virus infections - a multi-center historical cohort study

Objectives

Several studies have reported risk factors for severe disease and mortality in hospitalized adults with RSV infections. There is limited information available regarding the factors that affect the duration of a patient's hospital length of stay (LOS).

Methods

This was a multicenter historical cohort study of adult patients hospitalized for laboratory-confirmed RSV in Southeast Michigan between January 2017 and December 2021. Hospitalized patients were identified using the International Classification of Diseases, Tenth Revision 10 codes for RSV infection. Mean LOS was computed; prolonged LOS was defined as greater than the mean.

Results

We included 360 patients with a mean age (SD) of 69.9 ± 14.7 years, 63.6% (229) were female and 63.3% (228) of white race. The mean hospital LOS was 7.1 ± 5.4 days. Factors associated with prolonged LOS in univariable analysis were old age, body mass index (BMI), smoking status, Charlson Weighted Index of Comorbidity (CWIC), home oxygen, abnormal chest x-ray (CXR), presence of sepsis, use of oxygen, and antibiotics at the time of presentation. Predictors for prolonged LOS on admission in multivariable analysis were age on admission (p < 0.001), smoking status (p = 0.001), CWIC (p = 0.038) and abnormal CXR (p = 0.043).

Interpretation

Our study found that age on admission, smoking history, higher CWIC and abnormal CXR on admission were significantly associated with prolonged LOS among adult patients hospitalized with RSV infection. These findings highlight the significance of promptly recognizing and implementing early interventions to mitigate the duration of hospitalization for adult patients suffering from RSV infection.

T-cell lymphocytes' aging clock: telomeres, telomerase and aging

Aging is the decline of physiological capabilities required for life maintenance and reproduction over time. The human immune cells, including T-cells lymphocytes, undergo dramatic aging-related changes, including those related to telomeres and telomerase. It was demonstrated that telomeres and telomerase play crucial roles in T-cell differentiation, aging, and diseases, including a well-documented link between short telomeres and telomerase activation demonstrated in several T-cells malignancies. Herein, we provide a comprehensive review of the literature regarding T-cells' telomeres and telomerase in health and age related-diseases.

Immune signature and phagocytosis of circulating DC subsets in healthy adults during aging

Dendritic cells (DC) play a pivotal role in the onset and progression of immunosenescence-associated diseases, serving as a link between innate and adaptive immunity. Thus, there is a need to establish reference ranges for DC subset levels in healthy adults and investigate the potential impact of age on DC subset levels and phagocytic activity. Single-platform multi-color flow cytometry was performed to assess the proportions of circulating conventional type 1 DC (cDC1), conventional type 2 DC (cDC2), and plasmacytoid DC (pDC), as well as the percentages of CD80, CD86, CD83, PD-L1, and CD32 in cDC1, cDC2, and pDC. Reference ranges were established based on age and gender, and the percentage of circulating DC subsets in different age groups was compared. In addition, circulating DC were enriched using a magnetic bead sorting kit and co-cultured with polystyrene (PS) beads, categorized by age groups, followed by the evaluation of PS bead phagocytosis using light microscopy and flow cytometry. The results indicated that the percentages of circulating cDC1, cDC2, and CD32+cDC2 decreased with age (P < 0.05) and revealed age-related impairment in phagocytic percentage of cDC2 (P < 0.05). These findings provide a deeper understanding of the impact of age on the phenotype and phagocytic activity of DC subsets, shedding light on their role and function in immunosenescence.

Aging-related biomarker discovery in the era of immune checkpoint inhibitors for cancer patients

Older patients with cancer, particularly those over 75 years of age, often experience poorer clinical outcomes compared to younger patients. This can be attributed to age-related comorbidities, weakened immune function, and reduced tolerance to treatment-related adverse effects. In the immune checkpoint inhibitors (ICI) era, age has emerged as an influential factor impacting the discovery of predictive biomarkers for ICI treatment. These age-linked changes in the immune system can influence the composition and functionality of tumor-infiltrating immune cells (TIICs) that play a crucial role in the cancer response. Older patients may have lower levels of TIICs infiltration due to age-related immune senescence particularly T cell function, which can limit the effectivity of cancer immunotherapies. Furthermore, age-related immune dysregulation increases the exhaustion of immune cells, characterized by the dysregulation of ICI-related biomarkers and a dampened response to ICI. Our review aims to provide a comprehensive understanding of the mechanisms that contribute to the impact of age on ICI-related biomarkers and ICI response. Understanding these mechanisms will facilitate the development of treatment approaches tailored to elderly individuals with cancer.

Differentiation marker-negative CD4+ T cells persist after yellow fever virus vaccination and contribute to durable memory

Factors that contribute to durable immunological memory remain incompletely understood. In our longitudinal analyses of CD4+ T cell responses to the yellow fever virus (YFV) vaccine by peptide-MHC tetramers, we unexpectedly found naïve phenotype virus-specific CD4+ T cells that persisted months to years after immunization. These Marker negative T cells (TMN) lacked CD95, CXCR3, CD11a, and CD49d surface protein expression, distinguishing them from previously discovered stem-cell memory T cells. Functionally, they resembled genuine naïve T cells upon in vitro stimulation. Single-cell TCR sequencing detected expanded clonotypes within the TMN subset and identified a shared repertoire with memory and effector T cells. T cells expressing TMN-associated TCRs were rare before vaccination, suggesting their expansion following vaccination. Longitudinal tracking of YFV-specific responses over the subsequent years revealed superior stability of the TMN subset and their association with the longevity of the overall population. The identification of these long-lived, antigen-experienced T cells may inform the design of durable T cell-based vaccines and engineered T cell therapies.

11-deoxycortisol positively correlates with T cell immune traits in physiological conditions

BACKGROUND

Endogenous steroid hormones have significant effects on inflammatory and immune processes, but the immunological activities of steroidogenesis precursors remain largely unexplored.

METHODS

We conducted a systematic approach to examine the association between steroid hormones profile and immune traits in a cohort of 534 healthy volunteers. Serum concentrations of steroid hormones and their precursors (cortisol, progesterone, testosterone, androstenedione, 11-deoxycortisol and 17-OH progesterone) were determined by liquid chromatography-tandem mass spectrometry. Immune traits were evaluated by quantifying cellular composition of the circulating immune system and ex vivo cytokine responses elicited by major human pathogens and microbial ligands. An independent cohort of 321 individuals was used for validation, followed by in vitro validation experiments.

FINDINGS

We observed a positive association between 11-deoxycortisol and lymphoid cellular subsets numbers and function (especially IL-17 response). The association with lymphoid cellularity was validated in an independent validation cohort. In vitro experiments showed that, as compared to androstenedione and 17-OH progesterone, 11-deoxycortisol promoted T cell proliferation and Candida-induced Th17 polarization at physiologically relevant concentrations. Functionally, 11-deoxycortisol-treated T cells displayed a more activated phenotype (PD-L1high CD25high CD62Llow CD127low) in response to CD3/CD28 co-stimulation, and downregulated expression of T-bet nuclear transcription factor.

INTERPRETATION

Our findings suggest a positive association between 11-deoxycortisol and T-cell function under physiological conditions. Further investigation is needed to explore the potential mechanisms and clinical implications.

FUNDING

Found in acknowledgements.

A distinctive evolution of alveolar T cell responses is associated with clinical outcomes in unvaccinated patients with SARS-CoV-2 pneumonia

Pathogen clearance and resolution of inflammation in patients with pneumonia require an effective local T cell response. Nevertheless, local T cell activation may drive lung injury, particularly during prolonged episodes of respiratory failure characteristic of severe SARS-CoV-2 pneumonia. While T cell responses in the peripheral blood are well described, the evolution of T cell phenotypes and molecular signatures in the distal lung of patients with severe pneumonia caused by SARS-CoV-2 or other pathogens is understudied. Accordingly, we serially obtained 432 bronchoalveolar lavage fluid samples from 273 patients with severe pneumonia and respiratory failure, including 74 unvaccinated patients with COVID-19, and performed flow cytometry, transcriptional, and T cell receptor profiling on sorted CD8+ and CD4+ T cell subsets. In patients with COVID-19 but not pneumonia secondary to other pathogens, we found that early and persistent enrichment in CD8+ and CD4+ T cell subsets correlated with survival to hospital discharge. Activation of interferon signaling pathways early after intubation for COVID-19 was associated with favorable outcomes, while activation of NF-κB-driven programs late in disease was associated with poor outcomes. Patients with SARS-CoV-2 pneumonia whose alveolar T cells preferentially targeted the Spike and Nucleocapsid proteins tended to experience more favorable outcomes than patients whose T cells predominantly targeted the ORF1ab polyprotein complex. These results suggest that in patients with severe SARS-CoV-2 pneumonia, alveolar T cell interferon responses targeting structural SARS-CoV-2 proteins characterize patients who recover, yet these responses progress to NF-κB activation against non-structural proteins in patients who go on to experience poor clinical outcomes.

Single-cell atlas of healthy human blood unveils age-related loss of NKG2C+GZMB-CD8+ memory T cells and accumulation of type 2 memory T cells

Extensive, large-scale single-cell profiling of healthy human blood at different ages is one of the critical pending tasks required to establish a framework for the systematic understanding of human aging. Here, using single-cell RNA/T cell receptor (TCR)/BCR-seq with protein feature barcoding, we profiled 317 samples from 166 healthy individuals aged 25-85 years old. From this, we generated a dataset from ∼2 million cells that described 55 subpopulations of blood immune cells. Twelve subpopulations changed with age, including the accumulation of GZMK+CD8+ T cells and HLA-DR+CD4+ T cells. In contrast to other T cell memory subsets, transcriptionally distinct NKG2C+GZMB-CD8+ T cells counterintuitively decreased with age. Furthermore, we found a concerted age-associated increase in type 2/interleukin (IL)4-expressing memory subpopulations across CD4+ and CD8+ T cell compartments (CCR4+CD8+ Tcm and Th2 CD4+ Tmem), suggesting a systematic functional shift in immune homeostasis with age. Our work provides novel insights into healthy human aging and a comprehensive annotated resource.

Impact of age and telomere length on circulating T cells and rejection risk after lung transplantation for idiopathic pulmonary fibrosis

BACKGROUND

Most idiopathic pulmonary fibrosis (IPF) lung transplant recipients (IPF-LTRs) have short telomere (ST) length. Inherited mutations in telomere-related genes are associated with the development of T cell immunodeficiency. Despite this, IPF-LTRs with telomere-related rare variants are not protected from acute cellular rejection (ACR). We set out to determine the impact of both age and telomere length on the circulating T cell compartment and ACR burden of IPF-LTRs.

METHODS

We identified 106 IPF-LTRs who had telomere length testing using flowFISH (57 with short telomeres and 49 with long telomeres) as well as a subset from both cohorts who had cryopreserved PBMC at least 1 time point, 6 months posttransplantation. Circulating T cells from before transplantation and at 6 and 12 months posttransplantation were analyzed using multiparameter flow cytometry to study phenotype and functional capacity, and bulk T cell receptor sequencing was performed to study repertoire diversity. Linear regression was used to study the relationship of age and telomere length on early (within 1 year) and late (between 1 and 2 years) ACR.

RESULTS

IPF-LTRs with ST were found to have premature "aging" of their circulating T cell compartment, with age-agnostic elevations in posttransplant terminal differentiation of CD8+ T cells, increased granzyme B positivity of both CD8+ and CD4+ T cells, upregulation of the exhaustion marker, CD57, and chemotactic protein CCR5, and enhanced T cell receptor clonal expansion. Additionally, we found a significant decline in early ACR burden with increasing age, but only in the ST cohort.

CONCLUSIONS

IPF-LTRs with ST have premature "aging" of their circulating T cell compartment posttransplantation and a clear age-related decline in ACR burden.

From cardiovascular system to brain, the potential protective role of Mas Receptors in COVID-19 infection

Coronavirus disease 2019 (COVID-19) has been declared a new pandemic in March 2020. Although most patients are asymptomatic, those with underlying cardiovascular comorbidities may develop a more severe systemic infection which is often associated with fatal pneumonia. Nonetheless, neurological and cardiovascular manifestations could be present even without respiratory symptoms. To date, no COVID-19-specific drugs are able for preventing or treating the infection and generally, the symptoms are relieved with general anti-inflammatory drugs. Angiotensin-converting-enzyme 2 (ACE2) may function as the receptor for virus entry within the cells favoring the progression of infection in the organism. On the other hand, ACE2 is a relevant enzyme in renin angiotensin system (RAS) cascade fostering Ang1-7/Mas receptor activation which promotes protective effects in neurological and cardiovascular systems. It is known that RAS is composed by two functional countervailing axes the ACE/AngII/AT1 receptor and the ACE/AngII/AT2 receptor which counteracts the actions mediated by AngII/AT1 receptor by inducing anti-inflammatory, antioxidant and anti-growth functions. Subsequently an "alternative" ACE2/Ang1-7/Mas receptor axis has been described with functions similar to the latter protective arm. Here, we discuss the neurological and cardiovascular effects of COVID-19 highlighting the role of the stimulation of the RAS "alternative" protective arm in attenuating pulmonary, cerebral and cardiovascular damages. In conclusion, only two clinical trials are running for Mas receptor agonists but few other molecules are in preclinical phase and if successful these drugs might represent a successful strategy for the treatment of the acute phase of COVID-19 infection.

Risk Factors for Long COVID in Older Adults

As time has passed following the COVID-19 pandemic, individuals infected with SARS-CoV-2 have gradually exhibited a variety of symptoms associated with long COVID in the postacute phase of infection. Simultaneously, in many countries worldwide, the process of population aging has been accelerating. Within this context, the elderly population has not only become susceptible and high-risk during the acute phase of COVID-19 but also has considerable risks when confronting long COVID. Elderly individuals possess specific immunological backgrounds, and during the process of aging, their immune systems can enter a state known as "immunosenescence". This further exacerbates "inflammaging" and the development of various comorbidities in elderly individuals, rendering them more susceptible to long COVID. Additionally, long COVID can inflict both physical and mental harm upon elderly people, thereby reducing their overall quality of life. Consequently, the impact of long COVID on elderly people should not be underestimated. This review seeks to summarize the infection characteristics and intrinsic factors of older adults during the COVID-19 pandemic, with a focus on the physical and mental impact of long COVID. Additionally, it aims to explore potential strategies to mitigate the risk of long COVID or other emerging infectious diseases among older adults in the future.

The paradox of aging: Aging-related shifts in T cell function and metabolism

T cell survival, differentiation after stimulation, and function are intrinsically linked to distinct cellular metabolic states. The ability of T cells to readily transition between metabolic states enables flexibility to meet the changing energy demands defined by distinct effector states or T cell lineages. Immune aging is characterized, in part, by the loss of naïve T cells, accumulation of senescent T cells, severe dysfunction in memory phenotype T cells in particular, and elevated levels of inflammatory cytokines, or 'inflammaging'. Here, we review our current understanding of the phenotypic and functional changes that occur with aging in T cells, and how they relate to metabolic changes in the steady state and after T cell activation. We discuss the apparent contradictions in the aging T cell phenotype - where enhanced differentiation states and metabolic profiles in the steady state can correspond to a diminished capacity to adapt metabolically and functionally after T cell activation. Finally, we discuss key recent studies that indicate the enormous potential for aged T cell metabolism to induce systemic inflammaging and organism-wide multimorbidity, resulting in premature death.

Towards a better preclinical cancer model - human immune aging in humanized mice

BACKGROUND

Preclinical models are often used for cancer studies and evaluation of novel therapeutics. The relevance of these models has vastly improved with mice bearing a human immune system, especially in the context of immunotherapy. Nonetheless, cancer is an age-related disease, and studies often overlook the effects of aging. Here we have established a humanized mouse model of human immune aging to investigate the role of this phenomenon on liver tumor dynamics.

METHODS

Multiple organs and tissues (blood, thymus, lung, liver, spleen and bone marrow) were harvested from NOD-scid IL2rγ-/- (NIKO) mice reconstituted with human immune cells, over a period of 60 weeks post-birth, for immune profiling. Young and aging immune cells were compared for transcriptomic changes and functional differences. Effect of immune aging was investigated in a liver cancer humanized mouse model.

RESULTS

Focusing on the T cell population, which is central to cancer immunosurveillance and immunotherapy, we showed that the proportion of naïve T cells declined while memory subsets and senescent-like cells increased with age. RNA-sequencing revealed that downregulated genes were related to immune responses and processes, and this was corroborated by reduced cytokine production in aging T cells. Finally, we showed faster liver tumor growth in aging than younger humanized mice, which could be attributed to specific pathways of aging T cell exhaustion.

CONCLUSION

Our work improves on existing humanized (immune) mouse model and highlights the importance of considering immune aging in liver cancer modeling.

Thymalfasin therapy accelerates COVID-19 pneumonia rehabilitation through anti-inflammatory mechanisms

INTRODUCTION

Thymosin drugs are commonly used for the treatment of viral infections due to their immunomodulatory effects. The comprehensive clinical efficacy of Thymalfasin therapy for COVID-19 associated pneumonia is not yet fully researched, another issue, whether the use of thymosin drugs can reduce the rate of COVID-19 progression to severe pneumonia has not been well documented. The aim of the present study was to multi-angle evaluate the clinical efficacy of Thymalfasin therapy for COVID-19 pneumonia by retrospective review of the clinical data of 338 inpatients with common COVID-19 infection who received treatment in our hospital.

METHODS

The primary index of observation was whether progression to severe pneumonia occurred within a week after admission, and the secondary indexes were the length of hospital stay, time of negative conversion of COVID-19 antigen, the number of peripheral lymphocytes and white blood cells (WBC), and C-reactive protein (CRP) and procalcitonin (PCT) levels,and the control of pneumonia related symptoms, for example, fever, listlessness, inflammatory exudate area shown on lung CT (%).

RESULTS

The length of hospital stay of patients in Thymalfasin group was significantly shorter than that of patients in the control group (p < 0.01). The proportion of relief of pneumonia related symptoms (fever, fatigue) in the Thymalfasin therapy group was significantly higher than that in the control group, and the inflammatory exudate area shown on CT was significantly lower than that in the control group (p < 0.05). Multivariate logistic regression analysis showed that the use of Thymalfasin was an independent protective factor affecting the progression to severe pneumonia. Multifactorial Cox model analysis indicated that negative conversion of COVID-19 antigen was significantly faster in patients using Thymalfasin and younger patients.

CONCLUSION

Thymalfasin therapy has shown excellent clinical efficacy in the treatment of COVID-19 pneumonia, it can reduce inflammatory reactions, promote the relief of COVID-19 pneumonia related symptoms such as fever and fatigue, facilitate effusion absorption, and accelerate COVID-19 pneumonia recovery. Thymalfasin can prevent progression of common COVID-19 infection to severe pneumonia via multiple immunity-enhancing and anti-inflammatory protective mechanisms.

Human immune phenotyping reveals accelerated aging in type 1 diabetes

The proportions and phenotypes of immune cell subsets in peripheral blood undergo continual and dramatic remodeling throughout the human life span, which complicates efforts to identify disease-associated immune signatures in type 1 diabetes (T1D). We conducted cross-sectional flow cytometric immune profiling on peripheral blood from 826 individuals (stage 3 T1D, their first-degree relatives, those with ≥2 islet autoantibodies, and autoantibody-negative unaffected controls). We constructed an immune age predictive model in unaffected participants and observed accelerated immune aging in T1D. We used generalized additive models for location, shape, and scale to obtain age-corrected data for flow cytometry and complete blood count readouts, which can be visualized in our interactive portal (ImmScape); 46 parameters were significantly associated with age only, 25 with T1D only, and 23 with both age and T1D. Phenotypes associated with accelerated immunological aging in T1D included increased CXCR3+ and programmed cell death 1-positive (PD-1+) frequencies in naive and memory T cell subsets, despite reduced PD-1 expression levels on memory T cells. Phenotypes associated with T1D after age correction were predictive of T1D status. Our findings demonstrate advanced immune aging in T1D and highlight disease-associated phenotypes for biomarker monitoring and therapeutic interventions.

Immunoaging - the effect of age on serum levels of NET biomarkers in men: a pilot study

OBJECTIVES

The study aimed to evaluate the impact of aging on the formation of neutrophil extracellular traps (NETs). The impaired formation of NETs is the cause of an abnormal innate immune response.

MATERIAL AND METHODS

The study included a total of 45 healthy male subjects of different age groups. Whole blood was collected from the subjects, and the concentration of myeloperoxidase (MPO), the main biocidal protein in NETs, was determined in serum using ELISA. The serum levels of circulating free DNA (cfDNA), which are the structural basis of NETs, were also measured by fluorescence. In addition, the white blood cell count was determined, whole blood smear was evaluated, and the neutrophillymphocyte ratio was calculated. The variations in the levels of NET biomarkers were analyzed in different age groups.

RESULTS

The low levels of MPO (243.70 ng/ml) and cfDNA (6.24 ng/100 μl) in boys indicated neutrophil insufficiency for NETosis in children. A progressive increase in the levels of MPO and cfDNA with age was observed among adolescents (420.91, p = 0.04; 13.55, p = 0.03, respectively), with the highest level noted in the healthy adult group (466.58, p = 0.01; 14.07, p = 0.01, respectively). The levels of the studied parameters were comparable in adolescents and young adults, which proved that the NETosis process was appropriate and suggested the attainment of neutrophil maturity for the release of NETs in adolescence. The levels of MPO and cfDNA were low in older men (225.46, p < 0.01; 5.19, p < 0.01, respectively) indicating impaired NET formation.

CONCLUSIONS

Data on the generation of NETs in different age groups obtained in this study can allow a better understanding of the ontogenesis of the immune system in terms of the course of NETosis, and also indicate the need to support nonspecific responses in children and adults. Further research should be performed to determine the possibility of regulating the NETosis process. Int J Occup Med Environ Health. 2023;36(3):333-48.

Complete fatty degeneration of thymus associates with male sex, obesity and loss of circulating naïve CD8+ T cells in a Swedish middle-aged population

BACKGROUND

Fatty degeneration of thymus (or thymus involution) has long been considered a normal ageing process. However, there is emerging evidence that thymic involution is linked to T cell aging, chronic inflammation and increased morbidity. Other factors, aside from chronological age, have been proposed to affect the involution rate. In the present study, we investigated the imaging characteristics of thymus on computed tomography (CT) in a Swedish middle-aged population. The major aims were to establish the prevalence of fatty degeneration of thymus and to determine its associations with demographic, lifestyle and clinical factors, as well as inflammation, T cell differentiation and thymic output.

RESULTS

In total, 1 048 randomly invited individuals (aged 50-64 years, 49% females) were included and thoroughly characterized. CT evaluation of thymus included measurements of attenuation, size and a 4-point scoring system, with scale 0-3 based on the ratio of fat and soft tissue. A majority, 615 (59%) showed complete fatty degeneration, 259 (25%) predominantly fatty attenuation, 105 (10%) half fatty and half soft-tissue attenuation, while 69 (6.6%) presented with a solid thymic gland with predominantly soft-tissue attenuation. Age, male sex, high BMI, abdominal obesity and low dietary intake of fiber were independently associated with complete fatty degeneration of thymus. Also, fatty degeneration of thymus as well as low CT attenuation values were independently related to lower proportion of naïve CD8+ T cells, which in turn was related to lower thymic output, assessed by T-cell receptor excision circle (TREC) levels.

CONCLUSION

Among Swedish middle-aged subjects, nearly two-thirds showed complete fatty degeneration of thymus on CT. This was linked to depletion of naïve CD8+ T cells indicating that CT scans of thymus might be used to estimate immunological aging. Furthermore, our findings support the intriguing concept that obesity as well as low fiber intake contribute to immunological aging, thereby raising the possibility of preventive strategies.

Negative Influence of Aging on Differentiation and Proliferation of CD8+ T-Cells in Dogs

Immunosenescence is an age-related change in the immune system characterized by a reduction in naïve T-cells and an impaired proliferative capacity of CD8+ T-cells in older individuals. Recent research revealed the crucial impact of immunosenescence on the development and control of cancer, and aging is one of the causes that diminish the therapeutic efficacy of cancer immunotherapies targeting CD8+ T-cell activation. Despite dog cancer being defined as an age-related disease, there are few fundamental understandings regarding the relationship between aging and the canine immune system. Therefore, we aimed to elucidate the characteristics of immunosenescence in dogs and analyzed the effects of aging on the differentiation status and proliferation of canine CD8+ T cells using T-cell specific stimulation with anti-canine CD3/CD28 antibody-coated beads and interleukin-2. As a result, we found that older dogs have a lower proliferative capacity of CD8+ T-cells and a reduction in the naïve subset in their peripheral blood. Further analysis showed that older dogs had attenuated proliferation of the effector and central memory subsets. These results indicate the importance of maintaining less differentiated subsets to expand CD8+ T-cells in dogs and provide helpful insight into the development of dog immune therapies that require T-cell expansion ex vivo.

Natural products target glycolysis in liver disease

Mitochondrial dysfunction plays an important role in the occurrence and development of different liver diseases. Oxidative phosphorylation (OXPHOS) dysfunction and production of reactive oxygen species are closely related to mitochondrial dysfunction, forcing glycolysis to become the main source of energy metabolism of liver cells. Moreover, glycolysis is also enhanced to varying degrees in different liver diseases, especially in liver cancer. Therefore, targeting the glycolytic signaling pathway provides a new strategy for the treatment of non-alcoholic fatty liver disease (NAFLD) and liver fibrosis associated with liver cancer. Natural products regulate many steps of glycolysis, and targeting glycolysis with natural products is a promising cancer treatment. In this review, we have mainly illustrated the relationship between glycolysis and liver disease, natural products can work by targeting key enzymes in glycolysis and their associated proteins, so understanding how natural products regulate glycolysis can help clarify the therapeutic mechanisms these drugs use to inhibit liver disease.

A meta-analysis of immune-cell fractions at high resolution reveals novel associations with common phenotypes and health outcomes

BACKGROUND

Changes in cell-type composition of tissues are associated with a wide range of diseases and environmental risk factors and may be causally implicated in disease development and progression. However, these shifts in cell-type fractions are often of a low magnitude, or involve similar cell subtypes, making their reliable identification challenging. DNA methylation profiling in a tissue like blood is a promising approach to discover shifts in cell-type abundance, yet studies have only been performed at a relatively low cellular resolution and in isolation, limiting their power to detect shifts in tissue composition.

METHODS

Here we derive a DNA methylation reference matrix for 12 immune-cell types in human blood and extensively validate it with flow-cytometric count data and in whole-genome bisulfite sequencing data of sorted cells. Using this reference matrix, we perform a directional Stouffer and fixed effects meta-analysis comprising 23,053 blood samples from 22 different cohorts, to comprehensively map associations between the 12 immune-cell fractions and common phenotypes. In a separate cohort of 4386 blood samples, we assess associations between immune-cell fractions and health outcomes.

RESULTS

Our meta-analysis reveals many associations of cell-type fractions with age, sex, smoking and obesity, many of which we validate with single-cell RNA sequencing. We discover that naïve and regulatory T-cell subsets are higher in women compared to men, while the reverse is true for monocyte, natural killer, basophil, and eosinophil fractions. Decreased natural killer counts associated with smoking, obesity, and stress levels, while an increased count correlates with exercise and sleep. Analysis of health outcomes revealed that increased naïve CD4 + T-cell and N-cell fractions associated with a reduced risk of all-cause mortality independently of all major epidemiological risk factors and baseline co-morbidity. A machine learning predictor built only with immune-cell fractions achieved a C-index value for all-cause mortality of 0.69 (95%CI 0.67-0.72), which increased to 0.83 (0.80-0.86) upon inclusion of epidemiological risk factors and baseline co-morbidity.

CONCLUSIONS

This work contributes an extensively validated high-resolution DNAm reference matrix for blood, which is made freely available, and uses it to generate a comprehensive map of associations between immune-cell fractions and common phenotypes, including health outcomes.

Quantifying cellular dynamics in mice using a novel fluorescent division reporter system

The dynamics of cell populations are frequently studied in vivo using pulse-chase DNA labeling techniques. When combined with mathematical models, the kinetic of label uptake and loss within a population of interest then allows one to estimate rates of cell production and turnover through death or onward differentiation. Here we explore an alternative method of quantifying cellular dynamics, using a cell fate-mapping mouse model in which dividing cells can be induced to constitutively express a fluorescent protein, using a Ki67 reporter construct. We use a pulse-chase approach with this reporter mouse system to measure the lifespans and division rates of naive CD4 and CD8 T cells using a variety of modeling approaches, and show that they are all consistent with estimates derived from other published methods. However we propose that to obtain unbiased parameter estimates and full measures of their uncertainty one should simultaneously model the timecourses of the frequencies of labeled cells within both the population of interest and its precursor. We conclude that Ki67 reporter mice provide a promising system for modeling cellular dynamics.

The use of alpha 1 thymosin as an immunomodulator of the response against SARS-Cov2

BACKGROUND

Since the beginning of SARS-CoV2 pandemic, the mortality rate among elderly patients (60-90 years) has been around 50%, so age has been a determining factor of a worse COVID-19 prognosis. Associated with age, the thymic function involution and depletion plays an important role, that could be related to a dysregulated and ineffective innate and adaptive immune response against SARS-CoV2. Our study aims to further in vitro effect of human Thymosin-alpha-1 (α1Thy) treatment on the immune system in population groups with different thymic function levels in the scenario of SARS-CoV2 infection.

RESULTS

Activation markers such as CD40, CD80 and TIM-3 were upregulated in α1Thy presence, especially in plasmacytoid dendritic cells (pDCs) and, with increased TNFα production was observed compared to untreated condition. Co-cultures of CD4 + and CD8 + T cells with DCs treated with α1Thy in response to SARS-CoV2 peptides showed a decrease in the cytokine production compared to the condition without α1Thy pre-treated. A decrease in CD40L activation co-receptor expression in CD8 + LTs was also observed, as well as an increase in PD1 in CD4 + TLs expression in both age groups. In fact, there are no age-related differences in the immunomodulatory effect of the hormone, and it seems that effector memory and terminally differentiated memory T lymphocyte subsets were the most actively influenced by the immunomodulatory α1Thy effect. Finally, the polyfunctionality measured in SARS-CoV2 Specific-T cells response was maintained in α1Thy presence in total and memory subpopulations CD4 + and CD8 + T-cells, despite decreased proinflammatory cytokines production.

CONCLUSION

The hormone α1Thy could reduce, through the modulation of DCs, the amount of proinflammatory cytokines produced by T cells. Moreover, α1Thy improve lymphocyte functionality and could become a beneficial therapeutic alternative as an adjuvant in SARS-CoV2 treatment either in the acute phase after infection or reinfection. In addition, the effect on the T immune response means that α1Thy can be incorporated into the vaccination regimen, especially in the most immunologically vulnerable individuals such as the elderly.

SUBJECTS

Thymosin alpha 1, Dendritic cells, SARS-CoV2-specific T cells response, Immunomodulation.

Senescent T cells: Beneficial and detrimental roles

As the thymus involutes during aging, the T-cell pool has to be maintained by the periodic expansion of preexisting T cells during adulthood. A conundrum is that repeated episodes of activation and proliferation drive the differentiation of T cells toward replicative senescence, due to telomere erosion. This review discusses mechanisms that regulate the end-stage differentiation (senescence) of T cells. Although these cells, within both CD4 and CD8 compartments, lose proliferative activity after antigen-specific challenge, they acquire innate-like immune function. While this may confer broad immune protection during aging, these senescent T cells may also cause immunopathology, especially in the context of excessive inflammation in tissue microenvironments.

The diverse effects of transforming growth factor-β and SMAD signaling pathways during the CTL response

Cytotoxic T lymphocytes (CTLs) play an important role in defense against infections with intracellular pathogens and anti-tumor immunity. Efficient migration is required to locate and destroy infected cells in different regions of the body. CTLs accomplish this task by differentiating into specialized subsets of effector and memory CD8 T cells that traffic to different tissues. Transforming growth factor-beta (TGFβ) belongs to a large family of growth factors that elicit diverse cellular responses via canonical and non-canonical signaling pathways. Canonical SMAD-dependent signaling pathways are required to coordinate changes in homing receptor expression as CTLs traffic between different tissues. In this review, we discuss the various ways that TGFβ and SMAD-dependent signaling pathways shape the cellular immune response and transcriptional programming of newly activated CTLs. As protective immunity requires access to the circulation, emphasis is placed on cellular processes that are required for cell-migration through the vasculature.

Association between the epigenetic lifespan predictor GrimAge and history of suicide attempt in bipolar disorder

Bipolar disorder (BD) has been previously associated with premature mortality and aging, including acceleration of epigenetic aging. Suicide attempts (SA) are greatly elevated in BD and are associated with decreased lifespan, biological aging, and poorer clinical outcomes. We investigated the relationship between GrimAge, an epigenetic clock trained on time-to-death and associated with mortality and lifespan, and SA in two independent cohorts of BD individuals (discovery cohort - controls (n = 50), BD individuals with (n = 77, BD/SA) and without (n = 67, BD/non-SA) lifetime history of SA; replication cohort - BD/SA (n = 48) and BD/non-SA (n = 47)). An acceleration index for the GrimAge clock (GrimAgeAccel) was computed from blood DNA methylation (DNAm) and compared between groups with multiple general linear models. Differences in epigenetic aging from the discovery cohort were validated in the independent replication cohort. In the discovery cohort, controls, BD/non-SA, and BD/SA significantly differed on GrimAgeAccel (F = 5.424, p = 0.005), with the highest GrimAgeAccel in BD/SA (p = 0.004, BD/SA vs. controls). Within the BD individuals, BD/non-SA and BD/SA differed on GrimAgeAccel in both cohorts (p = 0.008) after covariate adjustment. Finally, DNAm-based surrogates revealed possible involvement of plasminogen activator inhibitor 1, leptin, and smoking pack-years in driving accelerated epigenetic aging. These findings pair with existing evidence that not only BD, but also SA, may be associated with an accelerated biological aging and provide putative biological mechanisms for morbidity and premature mortality in this population.

Regulative Roles of Metabolic Plasticity Caused by Mitochondrial Oxidative Phosphorylation and Glycolysis on the Initiation and Progression of Tumorigenesis

One important feature of tumour development is the regulatory role of metabolic plasticity in maintaining the balance of mitochondrial oxidative phosphorylation and glycolysis in cancer cells. In recent years, the transition and/or function of metabolic phenotypes between mitochondrial oxidative phosphorylation and glycolysis in tumour cells have been extensively studied. In this review, we aimed to elucidate the characteristics of metabolic plasticity (emphasizing their effects, such as immune escape, angiogenesis migration, invasiveness, heterogeneity, adhesion, and phenotypic properties of cancers, among others) on tumour progression, including the initiation and progression phases. Thus, this article provides an overall understanding of the influence of abnormal metabolic remodeling on malignant proliferation and pathophysiological changes in carcinoma.

Elevated CD153 Expression on Aged T Follicular Helper Cells is Vital for B cell Responses

Our recent data showed that an aberrant IL-10-producing T follicular helper population (Tfh10) accumulates dramatically with age and is associated with age-related declines in vaccine responsiveness. Through single cell gene expression and chromatin accessibility analysis of IL-10+ and IL-10- memory CD4+ T cells from young and aged mice, we identified increased expression of CD153 on aged Tfh and Tfh10 cells. Mechanistically, we linked inflammaging (increased IL-6 levels) to elevated CD153 expression of Tfh cells through c-Maf. Surprisingly, blockade of CD153 in aged mice significantly reduced their vaccine-driven antibody response, which was associated with decreased expression of ICOS on antigen-specific Tfh cells. Combined, these data show that an IL-6/c-Maf/CD153 circuit is critical for maintaining ICOS expression. Thus, although overall Tfh-mediated B cell responses are reduced in the context of vaccines and aging, our data suggest that elevated expression of CD153 on Tfh cells potentiates the remaining Tfh function in aged mice.

Immunology of Aging: the Birth of Inflammaging

The inflammaging concept was introduced in 2000 by Prof. Franceschi. This was an evolutionary or rather a revolutionary conceptualization of the immune changes in response to a lifelong stress. This conceptualization permitted to consider the lifelong proinflammatory process as an adaptation which could eventually lead to either beneficial or detrimental consequences. This dichotomy is influenced by both the genetics and the environment. Depending on which way prevails in an individual, the outcome may be healthy longevity or pathological aging burdened with aging-related diseases. The concept of inflammaging has also revealed the complex, systemic nature of aging. Thus, this conceptualization opens the way to consider age-related processes in their complexity, meaning that not only the process but also all counter-processes should be considered. It has also opened the way to add new concepts to the original one, leading to better understanding of the nature of inflammaging and of aging itself. Finally, it showed the way towards potential multimodal interventions involving a holistic approach to optimize the aging process towards a healthy longevity.

Immunosenescence, Inflammaging, and Frailty: Role of Myeloid Cells in Age-Related Diseases

The immune system is the central regulator of tissue homeostasis, ensuring tissue regeneration and protection against both pathogens and the neoformation of cancer cells. Its proper functioning requires homeostatic properties, which are maintained by an adequate balance of myeloid and lymphoid responses. Aging progressively undermines this ability and compromises the correct activation of immune responses, as well as the resolution of the inflammatory response. A subclinical syndrome of "homeostatic frailty" appears as a distinctive trait of the elderly, which predisposes to immune debilitation and chronic low-grade inflammation (inflammaging), causing the uncontrolled development of chronic and degenerative diseases. The innate immune compartment, in particular, undergoes to a sequela of age-dependent functional alterations, encompassing steps of myeloid progenitor differentiation and altered responses to endogenous and exogenous threats. Here, we will review the age-dependent evolution of myeloid populations, as well as their impact on frailty and diseases of the elderly.

Vitamin D as a Shield against Aging

Aging can be seen as a physiological progression of biomolecular damage and the accumulation of defective cellular components, which trigger and amplify the process, toward whole-body function weakening. Senescence initiates at the cellular level and consists in an inability to maintain homeostasis, characterized by the overexpression/aberrant expression of inflammatory/immune/stress responses. Aging is associated with significant modifications in immune system cells, toward a decline in immunosurveillance, which, in turn, leads to chronic elevation of inflammation/oxidative stress, increasing the risk of (co)morbidities. Albeit aging is a natural and unavoidable process, it can be regulated by some factors, like lifestyle and diet. Nutrition, indeed, tackles the mechanisms underlying molecular/cellular aging. Many micronutrients, i.e., vitamins and elements, can impact cell function. This review focuses on the role exerted by vitamin D in geroprotection, based on its ability to shape cellular/intracellular processes and drive the immune response toward immune protection against infections and age-related diseases. To this aim, the main biomolecular paths underlying immunosenescence and inflammaging are identified as biotargets of vitamin D. Topics such as heart and skeletal muscle cell function/dysfunction, depending on vitamin D status, are addressed, with comments on hypovitaminosis D correction by food and supplementation. Albeit research has progressed, still limitations exist in translating knowledge into clinical practice, making it necessary to focus attention on the role of vitamin D in aging, especially considering the growing number of older individuals.

High-throughput Treg cell receptor sequencing reveals differential immune repertoires in rheumatoid arthritis with kidney deficiency

Background

Regulatory T (Treg) cells are important immune cells that are regulated by adaptive immunity in the composition of Treg-cell subsets and T-cell receptors (TCRs). Treg cells are related to most autoimmune diseases, such as rheumatoid arthritis (RA). In traditional Chinese medicine (TCM), RA is typically attributed to kidney deficiency (KD) associated with the immunosenescence that causes immune dysfunction and the impaired function of Treg cells. So far, however, no mechanism related to KD and immune repertoires has been identified in RA.

Methods

Flow cytometry and high-throughput Treg-cell receptor sequencing were used to investigate the amount of different Treg-cell subsets and the diversity of TCRs between RA patients and healthy subjects, as well as between KD RA and non-KD RA patients. RT-qPCR was used to validate the high-throughput sequencing results.

Results

The data showed that the amount of naïve Treg cells in KD patients was less than in non-KD RA patients (P = 0.004) with no significant differences observed between other subsets. In the TCR of Treg cells, the length of complementarity determining region 3 (CDR3) was low and clonotypes increased in the KD group compared with the non-KD group. The diversity and abundance of Treg TCRs were low, as determined by the Hill number. In addition, several V(D)J combinations, such as T-cell receptor beta variable 7-2 (TRBV7-2), TRBV11-1, TRBV13, TRBV15, and TRBJ2-3, varied significantly between the two groups, indicating that KD causes Treg dysfunction. RT-qPCR shows that FOXP3 expression in peripheral blood Treg is lower in KD than in non-KD.

Conclusion

The results demonstrate the close correlation between KD and immune repertoires in RA and provide a new evaluation method for RA in TCM.

Multimodal single-cell analyses of peripheral blood mononuclear cells of COVID-19 patients in Japan

SARS-CoV-2 continues to spread worldwide. Patients with COVID-19 show distinct clinical symptoms. Although many studies have reported various causes for the diversity of symptoms, the underlying mechanisms are not fully understood. Peripheral blood mononuclear cells from COVID-19 patients were collected longitudinally, and single-cell transcriptome and T cell receptor repertoire analysis was performed. Comparison of molecular features and patients' clinical information revealed that the proportions of cells present, and gene expression profiles differed significantly between mild and severe cases; although even among severe cases, substantial differences were observed among the patients. In one severely-infected elderly patient, an effective antibody response seemed to have failed, which may have caused prolonged viral clearance. Naïve T cell depletion, low T cell receptor repertoire diversity, and aberrant hyperactivation of most immune cell subsets were observed during the acute phase in this patient. Through this study, we provided a better understanding of the diversity of immune landscapes and responses. The information obtained from this study can help medical professionals develop personalized optimal clinical treatment strategies for COVID-19.

Association between Immunosenescence, Mitochondrial Dysfunction and Frailty Syndrome in Older Adults

Aging is associated with changes in the immune system, increased inflammation and mitochondrial dysfunction. The relationship between these phenomena and the clinical phenotype of frailty is unclear. Here, we evaluated the immune phenotypes, T cell functions and mitochondrial functions of immune cells in frail and robust older subjects. We enrolled 20 frail subjects age- and gender-matched with 20 robust controls, and T cell phenotype, response to immune stimulation, cytokine production and immune cell mitochondrial function were assessed. Our results showed that numbers of CD4+ and CD8+ T cells were decreased in frail subjects, without impairment to their ratios. Memory and naïve T cells were not significantly affected by frailty, whereas the expression of CD28 but not that of ICOS was decreased in T cells from frail subjects. T cells from robust subjects produced more IL-17 after CD28 stimulation. Levels of serum cytokines were similar in frail subjects and controls. Mitochondrial bioenergetics and ATP levels were significantly lower in immune cells from frail subjects. In conclusion, we suggest that changes in T cell profiles are associated with aging rather than with frailty syndrome; however, changes in T cell response to immune stimuli and reduced mitochondrial activity in immune cells may be considered hallmarks of frailty.

The interplay of post-acute COVID-19 syndrome and aging: a biological, clinical and public health approach

The post-acute COVID-19 syndrome (PACS) is characterized by the persistence of fluctuating symptoms over three months from the onset of the possible or confirmed COVID-19 acute phase. Current data suggests that at least 10% of people with previously documented infection may develop PACS, and up to 50-80% of prevalence is reported among survivors after hospital discharge. This viewpoint will discuss various aspects of PACS, particularly in older adults, with a specific hypothesis to describe PACS as the expression of a modified aging trajectory induced by SARS CoV-2. This hypothesis will be argued from biological, clinical and public health view, addressing three main questions: (i) does SARS-CoV-2-induced alterations in aging trajectories play a role in PACS?; (ii) do people with PACS face immuno-metabolic derangements that lead to increased susceptibility to age-related diseases?; (iii) is it possible to restore the healthy aging trajectory followed by the individual before pre-COVID?. A particular focus will be given to the well-being of people with PACS that could be assessed by the intrinsic capacity model and support the definition of the healthy aging trajectory.

Calibrating a Comprehensive Immune Age Metric to Analyze the Cross Sectional Age-Related Decline in Cardiorespiratory Fitness

Cardiorespiratory fitness (CRF) is essential for sustained work ability in good health, but declines with aging, as does the functionality of the immune system, the latter process commonly referred to as immunosenescence. This study aimed to compare the capacity of immunosenescence biomarkers with chronological age for predicting low CRF in a cross-sectional sample recruited from the regional working population. CRF was determined by submaximal bicycle ergometer testing in a cross-sectional sample of 597 volunteers aged 20-70 years from the 'Dortmund Vital Study' (DVS, ClinicalTrials.gov Identifier: NCT05155397). Low CRF was scored if the ergometer test was not completed due to medical reasons or if the power output projected to a heart rate of 130 bpm divided by body mass was below sex-specific reference values of 1.25 W/kg for females and 1.5 W/kg for males, respectively. In addition to established biomarkers of immunosenescence, we calibrated a comprehensive metric of immune age to our data and compared its predictive capacity for low CRF to chronological age, while adjusting our analysis for the influence of sex, obesity, and the level of regular physical activity, by applying univariate and multiple logistic regression. While obesity, low physical activity, chronological and immune age were all associated with increased probability for low CRF in univariate analyses, multiple logistic regression revealed that obesity and physical activity together with immune age, but not chronological age, were statistically significant predictors of low CRF outcome. Sex was non-significant due to the applied sex-specific reference values. These results demonstrate that biological age assessed by our immunological metric can outperform chronological age as a predictor for CRF and indicate a potential role for immunosenescence in explaining the inter-individual variability of the age-related decline in cardiorespiratory fitness.