CD4(+) T cell anergy prevents autoimmunity and generates regulatory T cell precursors.

The role of anergy, an acquired state of T cell functional unresponsiveness, in natural peripheral tolerance remains unclear. In this study, we found that anergy was selectively induced in fetal antigen-specific maternal CD4(+) T cells during pregnancy. A naturally occurring subpopulation of anergic polyclonal CD4(+) T cells, enriched for self antigen-specific T cell antigen receptors, was also present in healthy hosts. Neuropilin-1 expression in anergic conventional CD4(+) T cells was associated with hypomethylation of genes related to thymic regulatory T cells (Treg cells), and this correlated with their ability to differentiate into Foxp3(+) Treg cells that suppressed immunopathology. Thus, our data suggest that not only is anergy induction important in preventing autoimmunity but also it generates the precursors for peripheral Treg cell differentiation.

TLR-driven early glycolytic reprogramming via the kinases TBK1-IKKɛ supports the anabolic demands of dendritic cell activation.

The ligation of Toll-like receptors (TLRs) leads to rapid activation of dendritic cells (DCs). However, the metabolic requirements that support this process remain poorly defined. We found that DC glycolytic flux increased within minutes of exposure to TLR agonists and that this served an essential role in supporting the de novo synthesis of fatty acids for the expansion of the endoplasmic reticulum and Golgi required for the production and secretion of proteins that are integral to DC activation. Signaling via the kinases TBK1, IKKɛ and Akt was essential for the TLR-induced increase in glycolysis by promoting the association of the glycolytic enzyme HK-II with mitochondria. In summary, we identified the rapid induction of glycolysis as an integral component of TLR signaling that is essential for the anabolic demands of the activation and function of DCs.

Cell-intrinsic lysosomal lipolysis is essential for alternative activation of macrophages.

Alternative (M2) activation of macrophages driven via the α-chain of the receptor for interleukin 4 (IL-4Rα) is important for immunity to parasites, wound healing, the prevention of atherosclerosis and metabolic homeostasis. M2 polarization is dependent on fatty acid oxidation (FAO), but the source of the fatty acids that support this metabolic program has not been clear. We found that the uptake of triacylglycerol substrates via the scavenger receptor CD36 and their subsequent lipolysis by lysosomal acid lipase (LAL) was important for the engagement of elevated oxidative phosphorylation, enhanced spare respiratory capacity (SRC), prolonged survival and expression of genes that together define M2 activation. Inhibition of lipolysis suppressed M2 activation during infection with a parasitic helminth and blocked protective responses to this pathogen. Our findings delineate a critical role for cell-intrinsic lysosomal lipolysis in M2 activation.

Mitochondrial Pyruvate Import Promotes Long-Term Survival of Antibody-Secreting Plasma Cells.

Durable antibody production after vaccination or infection is mediated by long-lived plasma cells (LLPCs). Pathways that specifically allow LLPCs to persist remain unknown. Through bioenergetic profiling, we found that human and mouse LLPCs could robustly engage pyruvate-dependent respiration, whereas their short-lived counterparts could not. LLPCs took up more glucose than did short-lived plasma cells (SLPCs) in vivo, and this glucose was essential for the generation of pyruvate. Glucose was primarily used to glycosylate antibodies, but glycolysis could be promoted by stimuli such as low ATP levels and the resultant pyruvate used for respiration by LLPCs. Deletion of Mpc2, which encodes an essential component of the mitochondrial pyruvate carrier, led to a progressive loss of LLPCs and of vaccine-specific antibodies in vivo. Thus, glucose uptake and mitochondrial pyruvate import prevent bioenergetic crises and allow LLPCs to persist. Immunizations that maximize these plasma cell metabolic properties might thus provide enduring antibody-mediated immunity.

Memory CD8(+) T cells use cell-intrinsic lipolysis to support the metabolic programming necessary for development.

Generation of CD8(+) memory T cells requires metabolic reprogramming that is characterized by enhanced mitochondrial fatty-acid oxidation (FAO). However, where the fatty acids (FA) that fuel this process come from remains unclear. While CD8(+) memory T cells engage FAO to a greater extent, we found that they acquired substantially fewer long-chain FA from their external environment than CD8(+) effector T (Teff) cells. Rather than using extracellular FA directly, memory T cells used extracellular glucose to support FAO and oxidative phosphorylation (OXPHOS), suggesting that lipids must be synthesized to generate the substrates needed for FAO. We have demonstrated that memory T cells rely on cell intrinsic expression of the lysosomal hydrolase LAL (lysosomal acid lipase) to mobilize FA for FAO and memory T cell development. Our observations link LAL to metabolic reprogramming in lymphocytes and show that cell intrinsic lipolysis is deterministic for memory T cell fate.

Metabolic Links between Plasma Cell Survival, Secretion, and Stress.

Humoral immunity is generated and maintained by antigen-specific antibodies that counter infectious pathogens. Plasma cells are the major producers of antibodies during and after infections, and each plasma cell produces some thousands of antibody molecules per second. This magnitude of secretion requires enormous quantities of amino acids and glycosylation sugars to properly build and fold antibodies, biosynthetic substrates to fuel endoplasmic reticulum (ER) biogenesis, and additional carbon sources to generate energy. Many of these processes are likely to be linked, thereby affording possibilities to improve vaccine design and to develop new therapies for autoimmunity. We review here aspects of plasma cell biology with an emphasis on recent studies and the relationships between intermediary metabolism, antibody production, and lifespan.

Non-pharmacological and pharmacological treatments for bone health after stroke: Systematic review with meta-analysis.

BACKGROUND: Hemi-osteoporosis is a common secondary complication of stroke. No systematic reviews of pharmacological and non-pharmacological agents for post-stroke bone health have estimated the magnitude and precision of effect sizes to guide better clinical practice. OBJECTIVES: To examine the benefits and harms of pharmacological and non-pharmacological agents on bone health in post-stroke individuals. METHODS: Eight databases were searched (PubMed, Cochrane library, Scopus, CINAHL Complete, Embase, PEDro, Clinicaltrils.gov and ICTRP) up to June 2023. Any controlled studies that applied physical exercise, supplements, or medications and measured bone-related outcomes in people with stroke were included. PEDro and the GRADE approach were used to examine the methodological quality of included articles and quality of evidence for outcomes. Effect sizes were calculated as standardized mean differences (SMD) and risk ratio (RR). Review Manager 5.4 was used for data synthetization. RESULTS: Twenty-four articles from 21 trials involving 22,500 participants (3,827 in 11 non-pharmacological and 18,673 in 10 pharmacological trials) were included. Eight trials were included in the meta-analysis. The methodological quality of half of the included non-pharmacological studies was either poor or fair, whereas it was good to excellent in 8 of 10 pharmacological studies. Meta-analysis revealed a beneficial effect of exercise on the bone mineral density (BMD) of the paretic hip (SMD: 0.50, 95 % CI: 0.16; 0.85; low-quality evidence). The effects of anti-resorptive medications on the BMD of the paretic hip were mixed and thus inconclusive (low-quality evidence). High-quality evidence showed that the administration of antidepressants increased the risk of fracture (RR: 2.36, 95 % CI 1.64-3.39). CONCLUSION: Exercise under supervision may be beneficial for hip bone health in post-stroke individuals. The effect of anti-resorptive medications on hip BMD is uncertain. The adverse effects of antidepressants on fracture risk among post-stroke individuals warrant further attention. Further high-quality studies are required to better understand this issue. REGISTRATION: PROSPERO CRD42022359186.

Tonic TCR Signaling Inversely Regulates the Basal Metabolism of CD4+ T Cells.

The contribution of self-peptide-MHC signaling in CD4+ T cells to metabolic programming has not been definitively established. In this study, we employed LLO118 and LLO56, two TCRtg CD4+ T cells that recognize the same Listeria epitope. We previously have shown that LLO56 T cells are highly self-reactive and respond poorly in a primary infection, whereas LLO118 cells, which are less self-reactive, respond well during primary infection. We performed metabolic profiling and found that naive LLO118 had a dramatically higher basal respiration rate, a higher maximal respiration rate, and a higher glycolytic rate relative to LLO56. The LLO118 cells also exhibited a greater uptake of 2-NBD-glucose, in vitro and in vivo. We extended the correlation of low self-reactivity (CD5lo) with high basal metabolism using two other CD4+ TCRtg cells with known differences in self-reactivity, AND and Marilyn. We hypothesized that the decreased metabolism resulting from a strong interaction with self was mediated through TCR signaling. We then used an inducible knock-in mouse expressing the Scn5a voltage-gated sodium channel. This channel, when expressed in peripheral T cells, enhanced basal TCR-mediated signaling, resulting in decreased respiration and glycolysis, supporting our hypothesis. Genes and metabolites analysis of LLO118 and LLO56 T cells revealed significant differences in their metabolic pathways, including the glycerol phosphate shuttle. Inhibition of this pathway reverts the metabolic state of the LLO118 cells to be more LLO56 like. Overall, these studies highlight the critical relationship between peripheral TCR-self-pMHC interaction, metabolism, and the immune response to infection.

Parental Decision-Making on Childhood Vaccination.

A growing number of parents delay vaccinations or are deciding not to vaccinate their children altogether. This increases the risk of contracting vaccine-preventable diseases and disrupting herd immunity, and also impairs the trust in the capacities of health care systems to protect people. Vaccine hesitancy is related to a range of both psychological and demographic determinants, such as attitudes toward vaccinations, social norms, and trust in science. Our aim is to understand those determinants in parents, because they are a special group in this issue-they act as proxy decision makers for their children, who are unable to decide for themselves. The fact that deciding to vaccinate is a socially forced choice that concerns a child's health makes vaccine-related decisions highly important and involving for parents. This high involvement might lead to parents overemphasizing the potential side effects that they know to be vaccine-related, and by amplifying those, parents are more focused on the potential outcomes of vaccine-related decisions, which can yield specific pattern of the outcome bias. We propose two related studies to investigate factors which promote vaccine hesitancy, protective factors that determine parental vaccination decisions, and outcome bias in parental vaccination intentions. We will explore demographic and psychological factors, and test parental involvement related to vaccine hesitancy using an online battery in a correlation panel design study. The second study is an experimental study, in which we will investigate the moderating role of parents' high involvement in the specific domain of vaccination decision making. We expect that higher involvement among parents, compared to non-parents, will shape the pattern of the proneness to outcome bias. The studies will be conducted across eight countries in Europe and Asia (Finland, Germany, Hong Kong, the Netherlands, Serbia, Slovenia, Spain, and the United Kingdom), rendering findings that will aid with understanding the underlying mechanisms of vaccine hesitancy and paving the way for developing interventions custom-made for parents.

Metabolic and Transcriptional Modules Independently Diversify Plasma Cell Lifespan and Function.

Plasma cell survival and the consequent duration of immunity vary widely with infection or vaccination. Using fluorescent glucose analog uptake, we defined multiple developmentally independent mouse plasma cell populations with varying lifespans. Long-lived plasma cells imported more fluorescent glucose analog, expressed higher surface levels of the amino acid transporter CD98, and had more autophagosome mass than did short-lived cells. Low amino acid concentrations triggered reductions in both antibody secretion and mitochondrial respiration, especially by short-lived plasma cells. To explain these observations, we found that glutamine was used for both mitochondrial respiration and anaplerotic reactions, yielding glutamate and aspartate for antibody synthesis. Endoplasmic reticulum (ER) stress responses, which link metabolism to transcriptional outcomes, were similar between long- and short-lived subsets. Accordingly, population and single-cell transcriptional comparisons across mouse and human plasma cell subsets revealed few consistent and conserved differences. Thus, plasma cell antibody secretion and lifespan are primarily defined by non-transcriptional metabolic traits.

Little Things Matter: A Time and Motion Study of Pharmacists' Activities in a Paediatric Hospital.

How healthcare providers distribute their time can impact on the quality and safety of care delivered, and this has been widely studied in hospitals providing care to adult patients. Children are different to adults and the workflow of healthcare providers in paediatric settings is largely unknown. The aim of this study was to quantify how clinical pharmacists working in a paediatric hospital spend their time. A direct observational time and motion study was conducted where two independent observers shadowed seven pharmacists covering eight wards for over 60 hours. Pharmacists spent the majority of time performing medication review (32.6%), followed by communication, non-clinical tasks, supply, medication discussion and in-transit. They were interrupted 3.5 times per hour and spent 4.4% of observed time multi-tasking. This is the first study to quantify how pharmacists in a paediatric hospital distribute their time. These results could act as useful baseline data against which to measure the impact of innovations, such as electronic medication management systems, on pharmacists' workflow.

Migratory CD103+ dendritic cells suppress helminth-driven type 2 immunity through constitutive expression of IL-12.

CD8α(+) and CD103(+) dendritic cells (DCs) play a central role in the development of type 1 immune responses. However, their role in type 2 immunity remains unclear. We examined this issue using Batf3(-/-) mice, in which both of these DC subsets are missing. We found that Th2 cell responses, and related events such as eosinophilia, alternative macrophage activation, and immunoglobulin class switching to IgG1, were enhanced in Batf3(-/-) mice responding to helminth parasites. This had beneficial or detrimental consequences depending on the context. For example, Batf3 deficiency converted a normally chronic intestinal infection with Heligmosomoides polygyrus into an infection that was rapidly controlled. However, liver fibrosis, an IL-13-mediated pathological consequence of wound healing in chronic schistosomiasis, was exacerbated in Batf3(-/-) mice infected with Schistosoma mansoni. Mechanistically, steady-state production of IL-12 by migratory CD103(+) DCs, independent of signals from commensals or TLR-initiated events, was necessary and sufficient to exert the suppressive effects on Th2 response development. These findings identify a previously unrecognized role for migratory CD103(+) DCs in antagonizing type 2 immune responses.

Helminth-induced arginase-1 exacerbates lung inflammation and disease severity in tuberculosis.

Parasitic helminth worms, such as Schistosoma mansoni, are endemic in regions with a high prevalence of tuberculosis (TB) among the population. Human studies suggest that helminth coinfections contribute to increased TB susceptibility and increased rates of TB reactivation. Prevailing models suggest that T helper type 2 (Th2) responses induced by helminth infection impair Th1 immune responses and thereby limit Mycobacterium tuberculosis (Mtb) control. Using a pulmonary mouse model of Mtb infection, we demonstrated that S. mansoni coinfection or immunization with S. mansoni egg antigens can reversibly impair Mtb-specific T cell responses without affecting macrophage-mediated Mtb control. Instead, S. mansoni infection resulted in accumulation of high arginase-1-expressing macrophages in the lung, which formed type 2 granulomas and exacerbated inflammation in Mtb-infected mice. Treatment of coinfected animals with an antihelminthic improved Mtb-specific Th1 responses and reduced disease severity. In a genetically diverse mouse population infected with Mtb, enhanced arginase-1 activity was associated with increased lung inflammation. Moreover, in patients with pulmonary TB, lung damage correlated with increased serum activity of arginase-1, which was elevated in TB patients coinfected with helminths. Together, our data indicate that helminth coinfection induces arginase-1-expressing type 2 granulomas, thereby increasing inflammation and TB disease severity. These results also provide insight into the mechanisms by which helminth coinfections drive increased susceptibility, disease progression, and severity in TB.