Aging trajectories of memory CD8 + T cells differ by their antigen specificity.

Memory T cells are a highly dynamic and heterogeneous population that is maintained by cytokine-driven homeostatic proliferation interspersed with episodes of antigen-mediated expansion and contraction which affect their functional state and their durability. This heterogeneity complicates studies on the impact of aging on global human memory cells, specifically, it is unclear how aging drives memory T cell dysfunction. Here, we used chronic infection with Epstein-Barr virus (EBV) to assess the influence of age on memory states at the level of antigen-specific CD8 + T cells. We find that in young adults (<40 years), EBV-specific CD8 + T cells assume preferred differentiation states depending on their peptide specificity. By age >65-years, different T cell specificities had undergone largely distinct aging trajectories, which had in common a loss in adaptive and a gain in innate immunity signatures. No evidence was seen for cellular senescence or exhaustion. While naïve/stem-like EBV-specific T cells disappeared with age, T cell diversity of EBV-specific memory cells did not change or even increased. In summary, by controlling for antigen specificity we uncover age-associated shifts in gene expression and TCR diversity that have implications for optimizing vaccination strategies and adoptive T cell therapy.

Advanced Electroanalysis for Electrosynthesis.

Electrosynthesis is a popular, environmentally friendly substitute for conventional organic methods. It involves using charge transfer to stimulate chemical reactions through the application of a potential or current between two electrodes. In addition to electrode materials and the type of reactor employed, the strategies for controlling potential and current have an impact on the yields, product distribution, and reaction mechanism. In this Review, recent advances related to electroanalysis applied in electrosynthesis were discussed. The first part of this study acts as a guide that emphasizes the foundations of electrosynthesis. These essentials include instrumentation, electrode selection, cell design, and electrosynthesis methodologies. Then, advances in electroanalytical techniques applied in organic, enzymatic, and microbial electrosynthesis are illustrated with specific cases studied in recent literature. To conclude, a discussion of future possibilities that intend to advance the academic and industrial areas is presented.

Comparative Evaluation of Efficacy of Platelet Rich Plasma (PRP) and Platelet Rich Fibrin (PRF) in Bone Regeneration after Surgical Removal of Impacted Bilateral Mandibular Third Molars - A Comparative Study.

Aims and Objectives: To compare the efficacy of platelet rich plasma (PRP) and platelet rich fibrin (PRF) in bone regeneration after removal of impacted bilateral third molars. Materials and Methods: The study was carried out as an open clinical trial on 20 patients chosen from the ones referred to the department of Oral & Maxillofacial Surgery for surgical removal of bilateral mandibular third molar. Patients were prepared for surgical procedure, Inferior alveolar nerve block given using 2% lignocaine hydrochloride with 1:2,00,000 adrenaline. Third molar were removed by flap reflection and bone drilling. Finally, PRF in lower left mandibular third molar region and PRP in lower right mandibular third molar region was inserted and wound closure was done. Cone bean computer tomography (CBCT) was made on 1st postoperative day and 4 months after surgery to evaluate alveolar bone height and density. Result: Alveolar bone height and bone density at post-operative 1st day and 4 months were compared between PRP and PRF group. The bone density and bone volume were analyzed, and there was no significant difference between bone density in PRP and PRF at day 1 and 4th month. Conclusion: As per our study and evaluation, in our postoperative follow up there was no statistically significant differences in bone regeneration by placement of PRP and PRF in extracted socket of third molar. Thus, with this study we can conclude that PRF, would be a good option to Oral and Maxillofacial Surgeons in the near future due to ease of extraction.

PREX1 improves homeostatic proliferation to maintain a naive CD4+ T cell compartment in older age.

The human adult immune system maintains normal T cell counts and compensates for T cell loss throughout life, mainly through peripheral homeostatic proliferation after the ability of the thymus to generate new T cells has rapidly declined at adolescence. This process is mainly driven by STAT5-activating cytokines, most importantly IL-7, and is very effective in maintaining a large naive CD4+ T cell compartment into older age. Here, we describe that naive CD4+ T cells undergo adaptations to optimize IL-7 responses by upregulating the guanine-nucleotide exchange factor PREX1 in older age. PREX1 promotes nuclear translocation of phosphorylated STAT5, thereby supporting homeostatic proliferation in response to IL-7. Through the same mechanism, increased expression of PREX1 also biases naive cells to differentiate into effector T cells. These findings are consistent with the concept that primarily beneficial adaptations during aging, i.e., improved homeostasis, account for unfavorable functions of the aged immune system, in this case biased differentiation.

Phenyl Acrylate-Based Cross-Linked Anion Exchange Membranes for Non-aqueous Redox Flow Batteries.

Redox flow batteries (RFBs) are of recent interest to store harvested renewable energy for improving grid reliability and utilization. In this study, we synthesized and characterized a series of phenyl acrylate-based UV-cross-linked anion exchange membranes (AEMs) and explored the performance of these AEMs in a model non-aqueous RFB under model conditions. Infrared spectroscopy was utilized to confirm the incorporation of ion carriers in the phenyl acrylate backbone. The electrochemical performance was compared with the commercial Fumasep membrane Fuma-375 based on high stability in non-aqueous solvents, high permeability to the charge-carrying ion, low resistance, low crossover of the redox-active molecules, and low cost. Our results show 55% total capacity retention through 1000 charge/discharge cycles because of low crossover as compared to the Fumasep commercial membrane which retained only 28% capacity. This result is promising in understanding and developing next-generation AEMs for non-aqueous RFBs and other electrochemical systems utilizing organic solvents.

Unraveling Hydrogen Atom Transfer Mechanisms with Voltammetry: Oxidative Formation and Reactivity of Cobalt Hydride.

The utility of transition metal hydride catalyzed hydrogen atom transfer (MHAT) has been widely demonstrated in organic transformations such as alkene isomerization and hydrofunctionalization reactions. However, the highly reactive nature of the hydride and radical intermediates has hindered mechanistic insight into this pivotal reaction. Recent advances in electrochemical MHAT have opened up the possibility for new analytical approaches for mechanistic diagnosis. Here, we report a voltammetric interrogation of Co-based MHAT reactivity, describing in detail the oxidative formation and reactivity of the key Co-H intermediate and its reaction with aryl alkenes. Insights from cyclic voltammetry and finite element simulations help elucidate the rate-limiting step as metal hydride formation, which we show to be widely tunable based on ligand design. Voltammetry is also suggestive of the formation of Co-alkyl intermediates and a dynamic equilibrium with the reactive neutral radical. These mechanistic studies provide information for the design of future hydrofunctionalization reactions, such as catalyst and silane choice, the relative stability of metal-alkyl species, and how hydrofunctionalization reactions utilize Co-alkyl intermediates. In summary, these studies establish an important template for studying MHAT reactions from the perspective of electrochemical kinetic frameworks.

Bioelectrocatalytic Synthesis: Concepts and Applications.

Bioelectrocatalytic synthesis is the conversion of electrical energy into value-added products using biocatalysts. These methods merge the specificity and selectivity of biocatalysis and energy-related electrocatalysis to address challenges in the sustainable synthesis of pharmaceuticals, commodity chemicals, fuels, feedstocks and fertilizers. However, the specialized experimental setups and domain knowledge for bioelectrocatalysis pose a significant barrier to adoption. This review introduces key concepts of bioelectrosynthetic systems. We provide a tutorial on the methods of biocatalyst utilization, the setup of bioelectrosynthetic cells, and the analytical methods for assessing bioelectrocatalysts. Key applications of bioelectrosynthesis in ammonia production and small-molecule synthesis are outlined for both enzymatic and microbial systems. This review serves as a necessary introduction and resource for the non-specialist interested in bioelectrosynthetic research.

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

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

TRIB2 safeguards naive T cell homeostasis during aging.

Naive CD4+ T cells are more resistant to age-related loss than naive CD8+ T cells, suggesting mechanisms that preferentially protect naive CD4+ T cells during aging. Here, we show that TRIB2 is more abundant in naive CD4+ than CD8+ T cells and counteracts quiescence exit by suppressing AKT activation. TRIB2 deficiency increases AKT activity and accelerates proliferation and differentiation in response to interleukin-7 (IL-7) in humans and during lymphopenia in mice. TRIB2 transcription is controlled by the lineage-determining transcription factors ThPOK and RUNX3. Ablation of Zbtb7b (encoding ThPOK) and Cbfb (obligatory RUNT cofactor) attenuates the difference in lymphopenia-induced proliferation between naive CD4+ and CD8+ cells. In older adults, ThPOK and TRIB2 expression wanes in naive CD4+ T cells, causing loss of naivety. These findings assign TRIB2 a key role in regulating T cell homeostasis and provide a model to explain the lesser resilience of CD8+ T cells to undergo changes with age.

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

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

Effect of Smoking on Nasal Mucociliary Clearance.

Nasal mucociliary clearance (NMC) system is an important defence mechanism in respiratory tract. The contents present in the smoke are found to be toxic to cilia in vitro. Our study aims at evaluating the NMC in smokers so as to know effect of tobacco smoke on ciliary function and also comparing it with non smokers. We also studied effect of duration, intensity and pattern of smoking on the NMC. A total of 60 participants in the age group 21-40 years (30 smokers and 30 non smokers) were included in the study. Saccharin test was performed in all participants. A 0.5 mm diameter particle of saccharin was placed 1 cm from the anterior end of the inferior nasal turbinate. The time duration was noted for the first appearance of sweet taste. The mean NMC in smoker group was 16.53 min and in nonsmoker group was 9.28 min On comparison it was found that NMC time in smoker group was significantly higher than nonsmoker group p < 0.001 also a positive correlation noted between pack years of smoking and NMC. Saccharin test is a simple test to assess NMC. The prolonged NMC in smokers may be due to reduced ciliary activity or due to changes in viscoelastic properties.

PD-1 combination therapy with IL-2 modifies CD8+ T cell exhaustion program.

Combination therapy with PD-1 blockade and IL-2 is highly effective during chronic lymphocytic choriomeningitis virus infection1. Here we examine the underlying basis for this synergy. We show that PD-1 + IL-2 combination therapy, in contrast to PD-1 monotherapy, substantially changes the differentiation program of the PD-1+TCF1+ stem-like CD8+ T cells and results in the generation of transcriptionally and epigenetically distinct effector CD8+ T cells that resemble highly functional effector CD8+ T cells seen after an acute viral infection. The generation of these qualitatively superior CD8+ T cells that mediate viral control underlies the synergy between PD-1 and IL-2. Our results show that the PD-1+TCF1+ stem-like CD8+ T cells, also referred to as precursors of exhausted CD8+ T cells, are not fate-locked into the exhaustion program and their differentiation trajectory can be changed by IL-2 signals. These virus-specific effector CD8+ T cells emerging from the stem-like CD8+ T cells after combination therapy expressed increased levels of the high-affinity IL-2 trimeric (CD25-CD122-CD132) receptor. This was not seen after PD-1 blockade alone. Finally, we show that CD25 engagement with IL-2 has an important role in the observed synergy between IL-2 cytokine and PD-1 blockade. Either blocking CD25 with an antibody or using a mutated version of IL-2 that does not bind to CD25 but still binds to CD122 and CD132 almost completely abrogated the synergistic effects observed after PD-1 + IL-2 combination therapy. There is considerable interest in PD-1 + IL-2 combination therapy for patients with cancer2,3, and our fundamental studies defining the underlying mechanisms of how IL-2 synergizes with PD-1 blockade should inform these human translational studies.

Self-assembled benzoselenadiazole-capped tripeptide hydrogels with inherent in vitro anti-cancer and anti-inflammatory activity.

Self-assembled benzoselenadiazole (BSe)-capped tripeptide based nanofibrillar hydrogels have been developed with inherent anticancer and anti-inflammatory activity.

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

[This corrects the article DOI: 10.3389/fimmu.2020.585168.].

Reduced chromatin accessibility to CD4 T cell super-enhancers encompassing susceptibility loci of rheumatoid arthritis.

BACKGROUND: Rheumatoid arthritis (RA) is an inflammatory disease that manifests as a preclinical stage of systemic autoimmunity followed by chronic progressive synovitis. Disease-associated genetic SNP variants predominantly map to non-coding, regulatory regions of functional importance in CD4 T cells, implicating these cells as key regulators. A better understanding of the epigenome of CD4 T cells holds the promise of providing information on the interaction between genetic susceptibility and exogenous factors. METHODS: We mapped regions of chromatin accessibility using ATAC-seq in peripheral CD4 T cell subsets of patients with RA (n=18) and compared them to T cells from patients with psoriatic arthritis (n=11) and age-matched healthy controls (n=10). Transcripts of selected genes were quantified using qPCR. FINDINGS: RA-associated epigenetic signatures were identified that in part overlapped between central and effector memory CD4 T cells and that were to a lesser extent already present in naïve cells. Sites more accessible in RA were highly enriched for the motif of the transcription factor (TF) CTCF suggesting differences in the three-dimensional chromatin structure. Unexpectedly, sites with reduced chromatin accessibility were enriched for motifs of TFs pertinent for T cell function. Most strikingly, super-enhancers encompassing RA-associated SNPs were less accessible. Analysis of selected transcripts and published DNA methylation patterns were consistent with this finding. The preferential loss in accessibility at these super-enhancers was seen in patients with high and low disease activity and on a variety of immunosuppressive treatment modalities. INTERPRETATION: Disease-associated genes are epigenetically less poised to respond in CD4 T cells from patients with established RA. FUNDING: This work was supported by I01 BX001669 from the Veterans Administration.

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.

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.

A platinum nanoparticle doped self-assembled peptide bolaamphiphile hydrogel as an efficient electrocatalyst for the hydrogen evolution reaction.

Noble metal-based nanomaterials have shown great potential for catalytic application with higher selectivity and activity. Owing to their self-assembly properties with various molecular interactions, peptides play an essential role in the controlled synthesis of noble metal-based catalysts with high surface area. In this work, a phenylalanine (F) and tyrosine (Y) based peptide bolaamphiphile is prepared by solution-phase peptide synthesis. The peptide bolaamphiphile readily self-assembles into a hydrogel with a cross-linked nanofibrillar network. The platinum nanoparticles (Pt NPs) are in situ generated within the cross-linked nanofibrillar network of the hydrogel matrix of the peptide bolaamphiphile. Benefiting from the synergistic properties of the Pt nanoparticles doped on three-dimensional fibrous networks, Pt6@hydrogel shows efficient catalytic activity for the electrochemical hydrogen evolution reaction (HER) in 0.5 M H2SO4 solution. The Pt6@hydrogel requires an overpotential of 45 mV at -10 mA cm-2 with a Tafel slope of 52 mV dec-1. The Pt6@hydrogel also shows electrocatalytic activity in basic and neutral pH solutions. The excellent activity and stability of Pt6@hydrogel for the HER shows great potential for energy conversion applications.

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.

Pulse electrodeposited, morphology controlled organic-inorganic nanohybrids as bifunctional electrocatalysts for urea oxidation.

Organic-inorganic nanohybrids with nanoscale architectures and electrocatalytic properties are emerging as a new branch of advanced functional materials. Herein, nanohybrid organic-inorganic nanosheets are grown on carbon paper via a pulse-electrochemical deposition technique. A benzo[2,1,3]selenadiazole-5-carbonyl protected dipeptide BSeFL (BSe = benzoselenadiazole; F = phenylalanine; and L = leucine) cross-linked with Ni2+ ions (Ni-BSeFL) and nickel hydroxide (Ni(OH)2) in a BSeFL/Ni(OH)2 electrode exhibits stable electrocatalytic activity toward urea oxidation. The cross-linked nanosheet morphology of nanohybrids was optimized by controlling the reduction potential during pulse electrodeposition. The BSeFL/Ni(OH)2 (-1.0 V) nanohybrid deposited at -1.0 V provides abundant active sites of Ni3+ with low charge transfer resistance (RCT) and high exchange current density (J0) at the electrocatalytic interface. The nanohybrids with Ni-BSeFL and Ni(OH)2 show low overpotential and superior stability for electrocatalytic urea electro-oxidation. The BSeFL/Ni(OH)2 (-1.0 V) nanohybrid based electrode requires a low potential of 1.30 V (vs. RHE) to acquire a current density of 10 mA cm-2 for the urea oxidation reaction (UOR) in urea containing alkaline solution which is lower than that for water oxidation in alkaline solution (1.49 V vs. RHE). The organic-inorganic nanohybrid BSeFL/Ni(OH)2 (-1.0 V) shows durability over 10 h for oxygen evolution and urea electro-oxidation, thereby confirming the BSeFL/Ni(OH)2 (-1.0 V) nanohybrid-based electrode as an efficient electrocatalyst.