Platelets differentially modulate CD4+ Treg activation via GPIIa/IIIb-, fibrinogen-, and PAR4-dependent pathways

CD4+FoxP3+ regulatory T cells (CD4+ Tregs) are known to dampen inflammation following severe trauma. Platelets were shown to augment their posttraumatic activation in burn injury, but the exact mechanisms remain unclear. We hypothesized that platelet activation mechanisms via GPIIb/IIIa, fibrinogen, and PAR4 have an immunological effect and modulate CD4+ Treg activation early after trauma. Therefore, C57Bl/6 N mice were injected with tirofiban (GPIIb/IIIa inhibition), ancrod (fibrinogen splitting enzyme), or tcY-NH2 (selective PAR4 antagonist peptide) before inducing a third-degree burn injury of 25% of the total body surface area. Changes in coagulation, and local and systemic CD4+ Treg activity were assessed via rotational thromboelastometry (ROTEM®) and phospho-flow cytometry 1 h post intervention. The inhibition of GPIIb/IIIa and fibrinogen locally led to a higher basic activity of CD4+ Tregs compared to non-inhibited animals. In contrast, PAR4 disruption on platelets locally led to an increased posttraumatic activation of CD4+ Tregs. Fibrinogen led to complete elimination of coagulation, whereas GPIIb/IIIa or PAR4 inhibition did not. GPIIb/IIIa receptor and fibrinogen inhibition increase CD4+ Tregs activity independently of trauma. Both are crucial for thrombus formation. We suggest platelets trapped in thrombi are unable to interact with CD4+ Tregs but augment their activity when circulating freely. In contrast, PAR4 seems to reduce CD4+ Treg activation following trauma. In summary, GPIIb/IIIa-, PAR4-, and fibrinogen-dependent pathways in platelets modulate CD4+ Treg baseline activity, independently from their hemostatic functionality. PAR4-dependent pathways modulate the posttraumatic interplay of platelets and CD4+ Tregs.

A Mathematical Model of Mitochondria in Proximal Tubule and Thick Ascending Limb Cells

Mitochondria are a key player in several kinds of tissue injury, and are even the ultimate cause of certain diseases. In this work we introduce new models of mitochondrial ATP generation in multiple tissues, including liver hepatocytes and the medullary thick ascending limb in the kidney. Using this model, we predict these tissues' responses to hypoxia, uncoupling, ischemia-reperfusion, and oxidative phosphorylation dysfunction. Our results suggest mechanisms explaining differences in robustness of mitochondrial function across tissues. The medullary thick ascending limb and proximal tubule in the kidney both experience a high metabolic demand, while having lower baseline activity of oxidative phosphorylation relative to the liver. These factors make these tissues susceptible to dysfunction of Complex III. A lower baseline oxygen tension observed in the thick ascending limb makes it susceptible to Complex IV. On the other hand, since the liver lacks these risk factors, and has higher baseline rates of glycolysis, it is less susceptible to all kinds of oxidative phosphorylation dysfunction.

Developmental consequences of early life stress on risk for psychopathology: Longitudinal associations with children's multisystem physiological regulation and executive functioning

The etiology of psychopathology is multifaceted and warrants consideration of factors at multiple levels and across developmental time. Although experiences of adversity in early life have been associated with increased risk of developing psychopathology, pathways toward maladaptation or resilience are complex and depend upon a variety of factors, including individuals’ physiological regulation and cognitive functioning. Therefore, in a longitudinal cohort of 113 mother–child dyads, we explored associations from early adverse experiences to physiological coregulation across multiple systems and subsequent variations in executive functioning. Latent profile analysis derived multisystem profiles based on children's heart rate, respiratory sinus arrhythmia, pre-ejection period, and cortisol measured during periods of rest and reactivity throughout a developmentally challenging protocol. Three distinct profiles of multisystem regulation emerged: heightened multisystem baseline activity (anticipatory arousal/ autonomic nervous system [ANS] responder), typically adaptive patterns across all systems (active copers/mobilizers), and heightened hypothalamic–pituitary–adrenal (HPA) axis activity (HPA axis responders). Path models revealed that children exposed to adversity before 18 months were more likely to evidence an anticipatory arousal/ANS responders response at 36 months, and children in this profile had lower executive functioning scores than the active copers/mobilizers. In sum, these findings provide important information about potential physiological associations linking early adversity to variations in children's task-based executive functioning.

Long-Term Effects of a Video-Based Smartphone App (“VIDEA Bewegt”) to Increase the Physical Activity of German Adults: A Single-Armed Observational Follow-Up Study

As physical inactivity is one of the four leading risk factors for mortality, it should be intensively treated. Therefore, this one-year follow-up study aimed to evaluate the long-term effects of a preventive app to increase physical activity in German adults under real-life circumstances. Data collection took place from July 2019 to July 2021 and included six online questionnaires. Physical activity was studied as the primary outcome based on MET-minutes per week (metabolic equivalent). Secondary outcomes included health-related quality of life based on a mental (MCS) and physical health component summary score (PCS). At the time of publication, 46/65 participants completed the study (median 52 years, 81.5% women). A significant increase of physical activity was observed in people with a low/moderate baseline activity during the first four months of follow-up (median increase by 490 MET-minutes per week, p < 0.001, r = 0.649). Both MCS (median increase by 2.8, p = 0.006, r = 0.344) and PCS (median increase by 2.6, p < 0.001, r = 0.521) significantly increased during the first two months and the BMI significantly decreased during the first six months after the intervention (median decrease by 0.96 kg/m2, p < 0.001, r = 0.465). Thus, this study provides evidence for the medium-term impact of the app, since the effects decreased over time. However, due to the chosen study design and a sizeable loss to follow-up, the validity of these findings is limited.

Exploring Owner Perceptions of the Impacts of Seasonal Weather Variations on Canine Activity and Potential Consequences for Human–Canine Relationships

Climate change is leading to more instances of seasonal weather variation. Studies have explored the impact of adverse winter weather on dog walking, but the impact on the dog’s overall activity levels have not been previously considered. This study explored dog owner perceptions of the effects of both summer and winter weather on their dog’s activity levels. An international online survey recruited 3153 respondents between May and December 2018, to explore the impact of summer and winter weather conditions on baseline activity levels. Owners reported their dogs were more impacted by cold (48.2% less likely to exercise their dog in the cold) and ice (64.0% less likely), than rain (25.3% were less likely). In hot weather, over 80% of owners reported reduced exercise duration and vigour for their dogs. Carrying water or walking near water to facilitate activity in the summer was the most popular mitigation strategy (90.8%). Participation in dog sports appeared to reduce the impact of winter weather on canine activity and increase owner awareness of cooling strategies to facilitate summer activity. Strategies to promote safe activity participation are needed to maintain canine activity levels amidst rising global temperatures, including better understanding of cooling strategies for exercising dogs.

Repetition effects in action planning reflect effector- but not hemisphere-specific coding

Action choices are influenced by future and recent past action states. For example, when performing two actions in succession, response times (RT) to initiate the second action are reduced when the same hand is used. These findings suggest the existence of effector-specific processing for action planning. However, given that each hand is primarily controlled by the contralateral hemisphere, the RT benefit might actually reflect effector-independent, hemisphere-specific rather than effector-specific repetition effects. Here, participants performed two consecutive movements, each with a hand or a foot, in one of two directions. Direction was specified in an egocentric reference frame (inward, outward) or in an allocentric reference frame (left, right). Successive actions were initiated faster when the same limb (e.g., left hand - left hand), but not when the other limb of the same body side (e.g., left foot - left hand) executed the second action. The same-limb advantage was evident even when the two movements involved different directions, whether specified egocentrically or allocentrically. Corroborating evidence from computational modeling lends support to the claim that repetition effects in action planning reflect persistent changes in baseline activity within neural populations that encode effector-specific action plans.

Preclinical studies for plant-based oral enzyme replacement therapy (Oral-ERT) in Pompe disease knockout mice with transgenic tobacco seeds expressing human GAA (tobrhGAA)

Genetic deficiency of acid α-glucosidase (GAA) results in glycogen storage disease type II (GSDII) or Pompe disease (PD) encompassing at least four clinical subtypes of varying severity (infantile; childhood, juvenile and late onset). Our objective is to develop an innovative and affordable approach for enzyme replacement therapy (ERT) via oral administration (Oral-ERT) to maintain a sustained, therapeutic level of enzyme on a daily basis to improve efficacy of treatment and quality of life for people living with Pompe disease. A consensus at a 2019 US Acid Maltase Deficiency (AMDA) conference suggested that a multi-pronged approach including gene therapy, diet, exercise, etc. must be evaluated for a successful treatment of Pompe disease. Tobacco seeds contain the metabolic machinery that is more compatible with mammalian glycosylation-phosphorylation and processing. Previously, we have shown that a lysate from transgenic tobacco seeds expressing human GAA (tobrhGAA) was enzymatically active and can correct enzyme deficiency in cultured PD cells and in adult lymphocytes of Pompe patients and in vivo in disease-relevant tissues in GAA knockout (KO) mice when administered IP. We have extended these pre-clinical studies in PD knockout (KO) mice with ground tobrhGAA seeds that supports proof-of-concept for Oral-ERT for future clinical trials. Briefly in GAA KO mice, Oral-ERT with ground tobrhGAA seeds showed significant reversal of fore-limb and hind-limb muscle weakness, increased motor coordination/balance/strength and mobility, improved spontaneous learning, increased GAA baseline activity in tissues, reduced glycogen in tissues and negible serum titers to GAA. Pharmacokinetics showed maximum serum GAA concentration (Cs) at 8-10 hr and peak urine excretion at 10-12 hr. The tobrhGAA was taken up in PD fibroblast, lymphoid and myoblast cells. Enzyme kinetics compared favorably or superior to placental hGAA, plus alglucosidase alfa or other rhGAAs for Km, Vmax, pH optima, thermal heat stability and IC50 for inhibitors. The tobrhGAA in seeds was extremely stable stored for 15 years at room temperature. NGS-genome sequencing of the tobrhGAA and wild-type plants and RNA expression profiles was performed and will be posted on our website. Thus, Oral-ERT with ground tobrhGAA seeds is an innovative approach that overcomes some of the challenges of alglucosidase alfa-ERT and provides a more effective, safe and significantly less expensive treatment.

Real-Time Monitoring of Levetiracetam Effect on the Electrophysiology of an Heterogenous Human iPSC-Derived Neuronal Cell Culture Using Microelectrode Array Technology

Levetiracetam (LEV) is a broad-spectrum and widely used antiepileptic drug that also has neuroprotective effects in different neurological conditions. Given its complex interaction with neuronal physiology, a better comprehension of LEV effects on neurons activity is needed. Microelectrode arrays (MEAs) represent an advanced technology for the non-invasive study of electrophysiological activity of neuronal cell cultures. In this study, we exploited the Maestro Edge MEA system, a platform that allows a deep analysis of the electrical network behavior, to study the electrophysiological effect of LEV on a mixed population of human neurons (glutamatergic, GABAergic and dopaminergic neurons, and astrocytes). We found that LEV significantly affected different variables such as spiking, single-electrode bursting, and network bursting activity, with a pronounced effect after 15 min. Moreover, neuronal cell culture completely rescued its baseline activity after 24 h without LEV. In summary, MEA technology confirmed its high sensitivity in detecting drug-induced electrophysiological modifications. Moreover, our results allow one to extend the knowledge on the electrophysiological effects of LEV on the complex neuronal population that resembles the human cortex.

Association between behavioral phenotypes and sustained use of smartphones and wearable devices to remotely monitor physical activity

Smartphones and wearable devices can be used to remotely monitor health behaviors, but little is known about how individual characteristics influence sustained use of these devices. Leveraging data on baseline activity levels and demographic, behavioral, and psychosocial traits, we used latent class analysis to identify behavioral phenotypes among participants randomized to track physical activity using a smartphone or wearable device for 6 months following hospital discharge. Four phenotypes were identified: (1) more agreeable and conscientious; (2) more active, social, and motivated; (3) more risk-taking and less supported; and (4) less active, social, and risk-taking. We found that duration and consistency of device use differed by phenotype for wearables, but not smartphones. Additionally, “at-risk” phenotypes 3 and 4 were more likely to discontinue use of a wearable device than a smartphone, while activity monitoring in phenotypes 1 and 2 did not differ by device type. These findings could help to better target remote-monitoring interventions for hospitalized patients.

From spikes to intercellular waves: Tuning intercellular calcium signaling dynamics modulates organ size control

Information flow within and between cells depends significantly on calcium (Ca2+) signaling dynamics. However, the biophysical mechanisms that govern emergent patterns of Ca2+ signaling dynamics at the organ level remain elusive. Recent experimental studies in developing Drosophila wing imaginal discs demonstrate the emergence of four distinct patterns of Ca2+ activity: Ca2+ spikes, intercellular Ca2+ transients, tissue-level Ca2+ waves, and a global “fluttering” state. Here, we used a combination of computational modeling and experimental approaches to identify two different populations of cells within tissues that are connected by gap junction proteins. We term these two subpopulations “initiator cells,” defined by elevated levels of Phospholipase C (PLC) activity, and “standby cells,” which exhibit baseline activity. We found that the type and strength of hormonal stimulation and extent of gap junctional communication jointly determine the predominate class of Ca2+ signaling activity. Further, single-cell Ca2+ spikes are stimulated by insulin, while intercellular Ca2+ waves depend on Gαq activity. Our computational model successfully reproduces how the dynamics of Ca2+ transients varies during organ growth. Phenotypic analysis of perturbations to Gαq and insulin signaling support an integrated model of cytoplasmic Ca2+ as a dynamic reporter of overall tissue growth. Further, we show that perturbations to Ca2+ signaling tune the final size of organs. This work provides a platform to further study how organ size regulation emerges from the crosstalk between biochemical growth signals and heterogeneous cell signaling states.