The Influence of a Competitive Field Hockey Match on Cognitive Function

Despite the known positive effects of acute exercise on cognition, the effects of a competitive team sport match are unknown. In a randomized crossover design, 20 female and 17 male field hockey players (19.7 ± 1.2 years) completed a battery of cognitive tests (Visual Search, Stroop, Corsi Blocks, and Rapid Visual Information Processing) prior to, at half-time, and immediately following a competitive match (or control trial of seated rest); with effect sizes (ES) presented as raw ES from mixed effect models. Blood samples were collected prior to and following the match and control trial, and analyzed for adrenaline, noradrenaline, brain derived neurotrophic factor (BDNF), cathepsin B, and cortisol. The match improved response times for a simple perception task at full-time (ES = –14 ms; P < 0.01) and response times on the complex executive function task improved at half-time (ES = –44 ms; P < 0.01). Working memory declined at full-time on the match (ES = –0.6 blocks; P < 0.01). The change in working memory was negatively correlated with increases in cortisol (r = –0.314, P = 0.01; medium), as was the change in simple perception response time and the change in noradrenaline concentration (r = –0.284, P = 0.01; small to medium). This study is the first to highlight the effects a competitive hockey match can have on cognition. These findings have implications for performance optimization, as understanding the influence on specific cognitive domains across a match allows for the investigation into strategies to improve these aspects.

Antibody secreting cells are critically dependent on integrin α4β7/MAdCAM-1 for intestinal recruitment and control of the microbiota during chronic colitis

T and B cells employ integrin α4β7 to migrate to intestine under homeostatic conditions. Whether those cells differentially rely on α4β7 for homing during inflammatory conditions has not been fully examined. This may have implications for our understanding of the mode of action of anti-integrin therapies in inflammatory bowel disease (IBD). Here, we examined the role of α4β7 integrin during chronic colitis using IL-10^-/- mice, β7-deficient IL-10^-/-, IgA-deficient IL-10^-/- mice, and antibody blockade of MAdCAM-1. We found that α4β7 was predominantly expressed by B cells. β7 deficiency and MAdCAM-1 blockade specifically depleted antibody secreting cells (ASC) (not T cells) from the colonic LP, leading to a fecal pan-immunoglobulin deficit, severe colitis, and alterations of microbiota composition. Colitis was not due to defective regulation, as dendritic cells (DC), regulatory T cells, retinaldehyde dehydrogenase (RALDH) expression, activity, and regulatory T/B-cell cytokines were all comparable between the strains/treatment. Finally, an IgA deficit closely recapitulated the clinical phenotype and altered microbiota composition of β7-deficient IL-10^-/- mice. Thus, a luminal IgA deficit contributes to accelerated colitis in the β7-deficient state. Given the critical/nonredundant dependence of IgA ASC on α4β7:MAdCAM-1 for intestinal homing, B cells may represent unappreciated targets of anti-integrin therapies.

Integrin β7 is required for B cell migration and regulation of the intestinal microbiota during colitis

The incidence of ulcerative colitis (UC) is increasing worldwide. A proven therapeutic strategy for UC is the inhibition of leukocyte trafficking via blockade of integrin β7. Despite this, the mechanism of action of vedolizumab (anti-α4β7) is poorly defined. Clear definitions of the immune subsets targeted by vedolizumab are essential for understanding the pathogenesis of UC, and development of biological endpoints for assessing treatment efficacy.

Methods

The IL-10−/− colitis model was crossed with integrin β7 deficient mice, and clinical features and histological scores were recorded. Flow cytometry of B-cell populations was conducted in colonic cell isolations. 16S bacterial sequencing was conducted on intestinal content.

Results

IL-10−/−β7−/− mice displayed increased mortality compared to IL-10−/− mice at 12 weeks and uniformly developed rectal prolapses. IL-10−/−β7−/− mice displayed increased colonic inflammatory indices (n&gt;10, p&lt;0.001), associated with a reduced B-cell, but normal T-cell, intestinal infiltrate (n&gt;6, p&lt;0.001). IL-10−/−β7−/− mice displayed a resulting IgA deficiency and significant alterations to the resident microbiota. The presence of systemic bacterial infection was observed. Blockade of the α4β7 ligand MAdCAM-1 in IL-10−/− mice resulted in a parallel phenotype.

Discussion

Integrin β7 deficiency results in a worsening of colitis in mice, resulting from a B-cell deficit in the inflamed colon and control the microbiota, via IgA. B-cells are largely ignored in the field of IBD and the potential complications associated with chronic integrin blockade. Our data suggests that the role of integrin β7 on B-cell migration may have important implications on the pathogenesis of colitis in mice and humans.

Sphingosine-1-phosphate lyase inhibition exacerbates DSS-induced colitis via promoting the disruption of epithelial barrier

S1P is a bioactive sphingolipid that participates as a critical regulator of many physiological processes, mainly in lymphocyte egress from lymphoid tissue, mediated by S1P gradients through the activity of S1P lyase (SPL). Inhibition of both S1P-specific receptors and Lyase activity has been shown to improve inflammatory conditions during Crohn’s-like ileitis. In contrast to this, initial observations show acute DSS-induced colitis was aggravated by SPL inhibition. Here we investigate whether the inhibition of Lyase in the intestinal epithelium is the cause of the exacerbation of colitis.

To induce global or epithelial cell specific SPL deletion, Gt(rosa)-cre or Villin-cre Sgpl1 transgenic mice were administered with tamoxifen (80 mg/kg) by oral gavage for 5 consecutive days. Then, mice were treated with DSS (2.5%) in drinking water for 7 days. Clinical features and histological scores were recorded. Permeability assays were performed to evaluate integrity of the intestinal epithelium with fluorescein isothiocyanate (FITC)-dextran 4 kDa.

Significant differences in the histopathological features (inflammation and injury) in colon were observed between Gt(rosa)Cre+/−/SPL−/− or VillinCre+/−/SPL−/− mice compared to their respective controls (without tamoxifen treatment) (n&gt;10, p&lt;0.001). In addition, these animals presented higher levels of epithelial permeability since the concentration of serum (FITC)-dextran was higher than their respective controls (n&gt;10, p&lt;0.001).

In conclusion, in the acute model of DSS-induced colitis the presence of S1P in the intestinal epithelium exacerbates inflammatory conditions, demonstrating that there could be differences in the mechanisms with chronic models of IBD.

Inherent Immune Cell Variation Within Colonic Segments Presents Challenges for Clinical Trial Design

BACKGROUND AND AIMS

Intestinal biopsy sampling during IBD trials represents a valuable adjunct strategy for understanding drug responses at the tissue level. Given the length and distinctive embryonic origins of the proximal and distal colon, we investigated whether inherent regional differences of immune cell composition could introduce confounders when sampling different disease stages, or pre/post drug administration. Here, we capitalise on novel mass cytometry technology to perform deep immunophenotyping of distinct healthy colonic segments, using the limited numbers of biopsies that can be harvested from patients.

METHODS

Biopsies [2.8 mm] were collected from the caecum, transverse colon, descending colon, and rectum of normal volunteers. Intestinal leukocytes were isolated, stained with a panel of 37 antibodies, and mass cytometry data acquired.

RESULTS

Site-specific patterns of leukocyte localisation were observed. The proximal colon featured increased CD8+ T cells [particularly resident memory], monocytes, and CD19+ B cells. Conversely, the distal colon and rectum tissues exhibited enrichment for CD4+ T cells and antibody-secreting cells. The transverse colon displayed increased abundance of both γδ T cells and NK cells. Subsets of leukocyte lineages also displayed gradients of expression along the colon length.

CONCLUSIONS

Our results show an inherent regional immune cell variation within colonic segments, indicating that regional mucosal signatures must be considered when assessing disease stages or the prospective effects of trial drugs on leukocyte subsets. Precise protocols for intestinal sampling must be implemented to allow for the proper interpretation of potential differences observed within leukocyte lineages present in the colonic lamina propria.

Sphingosine-1-Phosphate Lyase Inhibition Alters the S1P Gradient and Ameliorates Crohn's-Like Ileitis by Suppressing Thymocyte Maturation

BACKGROUND

Lymphocytes recirculate from tissues to blood following the sphingosine-1-phosphate (S1P) gradient (low in tissues, high in blood), maintained by synthetic and degradative enzymes, among which the S1P lyase (SPL) irreversibly degrades S1P. The role of SPL in the intestine, both during homeostasis and IBD, is poorly understood. We hypothesized that modulation of tissue S1P levels might be advantageous over S1P receptor (S1PR) agonists (eg, fingolimod, ozanimod, etrasimod), as without S1PR engagement there might be less likelihood of potential off-target effects.

METHODS

First we examined SPL mRNA transcripts and SPL localization in tissues by quantitative reverse transcription polymerase chain reaction and immunohistochemistry. The in vivo effects of the SPL inhibitors 4-deoxypyridoxine hydrochloride (30 mg/L) and 2-acetyl-4 (tetrahydroxybutyl)imidazole (50 mg/L) were assessed through their oral administration to adult TNF∆ARE mice, which spontaneously develop Crohn's-like chronic ileitis. The effect of SPL inhibition on circulating and tissue lymphocytes, transcriptional regulation of proinflammatory cytokines, and on the histological severity of ileitis was additionally examined. Tissue S1P levels were determined by liquid chromatography-mass spectrometry. Mechanistically, the potential effects of high S1P tissue levels on intestinal leukocyte apoptosis were assessed via terminal deoxynucleotidyl transferase dUTP nick end-labeling assay and annexin 5 staining. Finally, we examined the ability of T cells to home to the intestine, along with the effects of SPL inhibition on cellular subsets within immune compartments via flow and mass cytometry.

RESULTS

S1P lyase was ubiquitously expressed. In the gut, immunohistochemistry predominantly localized it to small intestinal epithelia, although the lamina propria leukocyte fraction had higher mRNA transcripts. Inhibition of SPL markedly increased local intestinal S1P levels, induced peripheral lymphopenia, downregulated proinflammatory cytokines, and attenuated chronic ileitis in mice. SPL inhibition reduced T and myeloid cells in secondary lymphoid tissues and the intestine and decreased naïve T-cell recruitment. The anti-inflammatory activity of SPL inhibition was not mediated by leukocyte apoptosis, nor by interference with the homing of lymphocytes to the intestine, and was independent of its peripheral lymphopenic effect. However, SPL inhibition promoted thymic atrophy and depleted late immature T cells (CD4+CD8+ double positive), with accumulation of mature CD4+CD8- and CD4-CD8+ single-positive cells.

CONCLUSIONS

Inhibition of the S1P lyase alters the S1P gradient and attenuates chronic ileitis via central immunosuppression. SPL inhibition could represent a potential way to tame an overactive immune response during IBD and other T-cell-mediated chronic inflammatory diseases.

Short-term isothermic heat acclimation elicits beneficial adaptations but medium-term elicits a more complete adaptation

Purpose

To investigate the effects of 60 min daily, short-term (STHA) and medium-term (MTHA) isothermic heat acclimation (HA) on the physiological and perceptual responses to exercise heat stress.

Methods

Sixteen, ultra-endurance runners (female = 3) visited the laboratory on 13 occasions. A 45 min sub-maximal (40% W_max) cycling heat stress test (HST) was completed in the heat (40 °C, 50% relative humidity) on the first (HST_PRE), seventh (HST_STHA) and thirteenth (HST_MTHA) visit. Participants completed 5 consecutive days of a 60 min isothermic HA protocol (target T_re 38.5 °C) between HST_PRE and HST_STHA and 5 more between HST_STHA and HST_MTHA. Heart rate (HR), rectal (T_re), skin (T_sk) and mean body temperature (T_body), perceived exertion (RPE), thermal comfort (TC) and sensation (TS) were recorded every 5 min. During HSTs, cortisol was measured pre and post and expired air was collected at 15, 30 and 45 min.

Results

At rest, T_re and T_body were lower in HST_STHA and HST_MTHA compared to HST_PRE, but resting HR was not different between trials. Mean exercising T_re, T_sk, T_body, and HR were lower in both HST_STHA and HST_MTHA compared to HST_PRE. There were no differences between HST_STHA and HST_MTHA. Perceptual measurements were lowered by HA and further reduced during HST_MTHA.

Conclusion

A 60 min a day isothermic STHA was successful at reducing physiological and perceptual strain experienced when exercising in the heat; however, MTHA offered a more complete adaptation.

Examining the Immune Composition of the Intestinal Mucosa by Mass Cytometry

BACKGROUND

The inflammatory bowel diseases (IBD) can affect various segments of the gastrointestinal tract, and the biology behind regional differences in disease remains poorly understood, in part due to a lack of understanding of regional variation of the particular cell subsets present. By utilizing mass cytometry, our objective was to identify regional differences in the immune composition of the digestive tract in healthy individuals.

METHOD

Intestinal pinch biopsies were obtained from the following sites of healthy individuals (n=10); duodenum, terminal ileum, ascending colon, transverse colon, descending colon, and rectum. Immune cells were isolated from biopsies and stained with a panel of 37 markers for analysis using mass cytometry.

RESULTS

Marked variations in immune cell composition were observed along the digestive tract, in particular T and B lymphocytes. Increased abundance of T lymphocytes (&gt;30% of total CD45+ cells) was identified in the duodenum and terminal ileum, whereas B lymphocytes became more abundant (&gt;30% of total CD45+ cells) towards the distal end of the tract. In addition, intestinal homing molecules displayed variation at each site; integrin α4β7, a target for IBD therapeutic intervention, was increasingly expressed in the terminal ileum and ascending colon, compared with the descending colon (Mean 40% vs 25% abundance, n=10, p&lt;0.01).

CONCLUSIONS

Mass cytometry has the ability to identify and characterize numerous distinct immune subsets throughout the intestinal mucosa, allowing a deep understanding of regional differences in immune composition. This understanding may shed light on the pathogenesis of IBD and allow standardization of intestinal sampling during the evaluation of therapeutics.

Targeting Cytokine Signaling and Lymphocyte Traffic via Small Molecules in Inflammatory Bowel Disease: JAK Inhibitors and S1PR Agonists

The inflammatory Bowel diseases (IBDs) are a chronic, relapsing inflammatory diseases of the gastrointestinal tract with heterogeneous behavior and prognosis. The introduction of biological therapies including anti-TNF, anti-IL-12/23, and anti-integrins, has revolutionized the treatment of IBD, but these drugs are not universally effective. Due to the complex molecular structures of biologics, they are uniformly immunogenic. New discoveries concerning the underlying mechanisms involved in the pathogenesis of IBD have allowed for progress in the development of new treatment options. The advantage of small molecules (SMs) over biological therapies includes their lack of immunogenicity, short half-life, oral administration, and low manufacturing cost. Among these, the Janus Kinases (JAKs) inhibition has emerged as a novel strategy to modulate downstream cytokine signaling during immune-mediated diseases. These drugs target various cytokine signaling pathways that participate in the pathogenesis of IBD. Tofacitinib, a JAK inhibitor targeting predominantly JAK1 and JAK3, has been approved for the treatment of ulcerative colitis (UC), and there are other specific JAK inhibitors under development that may be effective in Crohn's. Similarly, the traffic of lymphocytes can now be targeted by another SM. Sphingosine-1-phosphate receptor (S1PR) agonism is a novel strategy that acts, in part, by interfering with lymphocyte recirculation, through blockade of lymphocyte egress from lymph nodes. S1PR agonists are being studied in IBD and other immune-mediated disorders. This review will focus on SM drugs approved and under development, including JAK inhibitors (tofacitinib, filgotinib, upadacitinib, peficitinib) and S1PR agonists (KRP-203, fingolimod, ozanimod, etrasimod, amiselimod), and their mechanism of action.

Cell Trafficking Interference in Inflammatory Bowel Disease: Therapeutic Interventions Based on Basic Pathogenesis Concepts

After 20 years of successful targeting of pro-inflammatory cytokines for the treatment of IBD, an alternative therapeutic strategy has emerged, based on several decades of advances in understanding the pathogenesis of IBD. The targeting of molecules involved in leukocyte traffic has recently become a safe and effective alternative. With 2 currently approved drugs (ie, natalizumab, vedolizumab) and several others in phase 3 trials (eg, etrolizumab, ozanimod, anti-MAdCAM-1), the blockade of trafficking molecules has firmly emerged as a new therapeutic era for IBD. We discuss the targets that have been explored in clinical trials: chemokines and its receptors (eg, IP10, CCR9), integrins (eg, natalizumab, AJM300, vedolizumab, and etrolizumab), and its endothelial ligands (MAdCAM-1, ICAM-1). We also discuss a distinct strategy that interferes with lymphocyte recirculation by blocking lymphocyte egress from lymph nodes (small molecule sphingosine-phosphate receptor [S1PR] agonists: fingolimod, ozanimod, etrasimod, amiselimod). Strategies on the horizon include additional small molecules, allosteric inhibitors that specifically bind to the active integrin form and nanovectors that allow for the use of RNA interference in the quest to modulate pro-inflammatory leukocyte trafficking in IBD.

Practical Torso Cooling During Soccer-Specific Exercise in the Heat

CONTEXT

Precooling and midevent cooling of the torso using cooling vests can improve exercise performance in the heat with or without physiological changes; however, the effects of such cooling during intermittent exercise in the heat are unknown.

OBJECTIVE

To investigate the effects of torso cooling during intermittent exercise in the heat (35°C, 50% relative humdity) on sprint performance and the physiological and perceptual responses to the exercise.

DESIGN

Crossover study.

SETTING

Walk-in environmental chamber.

PATIENTS OR OTHER PARTICIPANTS

Ten non-heat-acclimated, male soccer players (age = 25 ± 2 years, height = 1.77 ± 0.06 m, mass = 72.9 ± 7.6 kg).

INTERVENTION(S)

Two 90-minute bouts of soccer-specific intermittent running in the heat: 1 trial with a cooling vest worn during the exercise and 1 trial without a cooling vest. Each trial comprised two 45-minute periods separated by approximately 15 minutes of seated rest in cool conditions (approximately 23°C, 50% relative humdity).

MAIN OUTCOME MEASURE(S)

Peak sprint speed, rectal temperature (T_r), mean-weighted skin temperature (T_sk), heart rate (HR), rating of perceived exertion (RPE), and thermal sensation (TS) were measured every 5 minutes.

RESULTS

Peak sprint performance was largely unaffected by the cooling vest. The T_r, T_sk, HR, RPE, and TS were unaffected in the cooling-vest trial during the first 45 minutes, but T_r rose at a slower rate in the cooling-vest trial (0.026°C^.min^-1 ± 0.008°C^.min^-1) than in the no-vest trial (0.032°C^.min^-1 ± 0.009°C^.min^-1). During the second 45-minute period, T_r, T_r rate of rise, T_sk, RPE, and TS were lower in the cooling-vest trial (Hedges g range, 0.55-0.84), but mean HR was unaffected.

CONCLUSIONS

Wearing a cooling vest during soccer-specific intermittent running in the heat reduced physiological and perceptual strain but did not increase peak sprint speed.

Implementation of Mass Cytometry as a Tool for Mechanism of Action Studies in Inflammatory Bowel Disease

Background

Novel therapeutics for inflammatory bowel disease (IBD) are under development, yet mechanistic readouts at the tissue level are lacking. Techniques to assess intestinal immune composition could represent a valuable tool for mechanism of action (MOA) studies of novel drugs. Mass cytometry enables analysis of intestinal inflammatory cell infiltrate and corresponding molecular fingerprints with unprecedented resolution. Here, we aimed to optimize the methodology for isolation and cryopreservation of cells from intestinal tissue to allow for the potential implementation of mass cytometry in MOA studies.

Methods

We investigated key technical issues, including minimal tissue requirements, cell isolation protocols, and cell storage, using intestinal biopsies and peripheral blood from healthy individuals. High-dimensional mass cytometry was employed for the analyses of biopsy-derived intestinal cellular subsets.

Results

Dithiothreitol and mechanical dissociation decreased epithelial cell contamination and allowed for isolation of adequate cell numbers from 2 to 4 colonic or ileal biopsies (6 × 104±2 × 104) after a 20-minute collagenase digestion, allowing for reliable detection of most major immune cell subsets. Biopsies and antibody-labeled mononuclear cells could be cryopreserved for later processing and acquisition (viability > 70%; P < 0.05).

Conclusions

Mass cytometry represents a unique tool for deep immunophenotyping intestinal cell composition. This technique has the potential to facilitate analysis of drug actions at the target tissue by identifying specific cellular subsets and their molecular signatures. Its widespread implementation may impact not only IBD research but also other gastrointestinal conditions where inflammatory cells play a role in pathogenesis.

Passive Heat Exposure Alters Perception and Executive Function

Findings regarding the influence of passive heat exposure on cognitive function remain equivocal due to a number of methodological issues including variation in the domains of cognition examined. In a randomized crossover design, forty-one male participants completed a battery of cognitive function tests [Visual Search, Stroop, Corsi Blocks and Rapid Visual Information Processing (RVIP) tests] prior to and following 1 h of passive rest in either hot (39.6 ± 0.4°C, 50.8 ± 2.3% Rh) or moderate (21.2 ± 1.8°C, 41.9 ± 11.4% Rh) conditions. Subjective feelings of heat exposure, arousal and feeling were assessed alongside physiological measures including core temperature, skin temperature and heart rate, at baseline and throughout the protocol. Response times were slower in the hot trial on the simple (main effect of trial, P < 0.001) and complex (main effect of trial, P < 0.001) levels of the Stroop test (Hot: 872 ± 198 ms; Moderate: 834 ± 177 ms) and the simple level of the visual search test (Hot: 354 ± 54 ms; Moderate: 331 ± 47 ms) (main effect of trial, P < 0.001). Participants demonstrated superior accuracy on the simple level of the Visual Search test in the hot trial (Hot: 98.5 ± 3.1%; Moderate: 97.4 ± 3.6%) (main effect of trial, P = 0.035). Participants also demonstrated an improvement in accuracy on the complex level of the visual search test following 1 h passive heat exposure (Pre: 96.8 ± 5.9%; Post: 98.1 ± 3.1%), whilst a decrement was seen across the trial in the moderate condition (Pre: 97.7 ± 3.5; Post: 97.0 ± 5.1%) (time^*trial interaction, P = 0.029). No differences in performance were observed on the RVIP or Corsi Blocks tests (all P > 0.05). Subjective feelings of thermal sensation and felt arousal were higher, feeling was lower in the hot trial, whilst skin temperature, core temperature and heart rate were higher (main effects of trial, all P < 0.001). The findings of the present study suggest that response times for perception and executive function tasks are worse in the heat. An improvement in accuracy on perceptual tasks may suggest a compensatory speed-accuracy trade-off effect occurring within this domain, further highlighting the task dependant nature of heat exposure on cognition.

Core and skin temperature influences on the surface electromyographic responses to an isometric force and position task

The large body of work demonstrating hyperthermic impairment of neuromuscular function has utilized maximal isometric contractions, but extrapolating these findings to whole-body exercise and submaximal, dynamic contractions may be problematic. We isolated and compared core and skin temperature influences on an isometric force task versus a position task requiring dynamic maintenance of joint angle. Surface electromyography (sEMG) was measured on the flexor carpi radialis at 60% of baseline maximal voluntary contraction while either pushing against a rigid restraint (force task) or while maintaining a constant wrist angle and supporting an equivalent inertial load (position task). Twenty participants performed each task at 0.5°C rectal temperature (T_re) intervals while being passively heated from 37.1±0.3°C to ≥1.5°C T_re and then cooled to 37.8±0.3°C, permitting separate analyses of core versus skin temperature influences. During a 3-s contraction, trend analysis revealed a quadratic trend that peaked during hyperthermia for root-mean-square (RMS) amplitude during the force task. In contrast, RMS amplitude during the position task remained stable with passive heating, then rapidly increased with the initial decrease in skin temperature at the onset of passive cooling (p = 0.010). Combined hot core and hot skin elicited shifts toward higher frequencies in the sEMG signal during the force task (p = 0.003), whereas inconsistent changes in the frequency spectra occurred for the position task. Based on the patterns of RMS amplitude in response to thermal stress, we conclude that core temperature was the primary thermal afferent influencing neuromuscular response during a submaximal force task, with minimal input from skin temperature. However, skin temperature was the primary thermal afferent during a position task with minimal core temperature influence. Therefore, temperature has a task-dependent impact on neuromuscular responses.

The Antigen-Presenting Potential of Vγ9Vδ2 T Cells During Plasmodium falciparum Blood-Stage Infection

During Plasmodium falciparum infections, erythrocyte-stage parasites inhibit dendritic cell maturation and function, compromising effective antimalarial adaptive immunity. Human Vγ9Vδ2 T cells can act in vitro as antigen-presenting cells (APCs) and induce αβ T-cell activation. However, the relevance of this activity in vivo has remained elusive. Because Vγ9Vδ2 T cells are activated during the early immune response against P. falciparum infection, we investigated whether they could contribute to the instruction of adaptive immune responses toward malaria parasites. In P. falciparum-infected patients, Vγ9Vδ2 T cells presented increased surface expression of APC-associated markers HLA-DR and CD86. In response to infected red blood cells in vitro, Vγ9Vδ2 T cells upregulated surface expression of HLA-DR, HLA-ABC, CD40, CD80, CD83, and CD86, induced naive αβ T-cell responses, and cross- presented soluble prototypical protein to antigen-specific CD8+ T cells. Our findings qualify Vγ9Vδ2 T cells as alternative APCs, which could be harnessed for therapeutic interventions and vaccine design.

Antigen-Presenting Human γδ T Cells Promote Intestinal CD4+ T Cell Expression of IL-22 and Mucosal Release of Calprotectin

The cytokine IL-22 plays a critical role in mucosal barrier defense, but the mechanisms that promote IL-22 expression in the human intestine remain poorly understood. As human microbe-responsive Vγ9/Vδ2 T cells are abundant in the gut and recognize microbiota-associated metabolites, we assessed their potential to induce IL-22 expression by intestinal CD4+ T cells. Vγ9/Vδ2 T cells with characteristics of APCs were generated from human blood and intestinal organ cultures, then cocultured with naive and memory CD4+ T cells obtained from human blood or the colon. The potency of blood and intestinal γδ T-APCs was compared with that of monocytes and dendritic cells, by assessing CD4+ T cell phenotypes and proliferation as well as cytokine and transcription factor profiles. Vγ9/Vδ2 T cells in human blood, colon, and terminal ileum acquired APC functions upon microbial activation in the presence of microenvironmental signals including IL-15, and were capable of polarizing both blood and colonic CD4+ T cells toward distinct effector fates. Unlike monocytes or dendritic cells, gut-homing γδ T-APCs employed an IL-6 independent mechanism to stimulate CD4+ T cell expression of IL-22 without upregulating IL-17. In human intestinal organ cultures, microbial activation of Vγ9/Vδ2 T cells promoted mucosal secretion of IL-22 and ICOSL/TNF-α-dependent release of the IL-22 inducible antimicrobial protein calprotectin without modulating IL-17 expression. In conclusion, human γδ T-APCs stimulate CD4+ T cell responses distinct from those induced by myeloid APCs to promote local barrier defense via mucosal release of IL-22 and calprotectin. Targeting of γδ T-APC functions may lead to the development of novel gut-directed immunotherapies and vaccines.

Neck-cooling improves repeated sprint performance in the heat

The present study evaluated the effect of neck-cooling during exercise on repeated sprint ability in a hot environment. Seven team-sport playing males completed two experimental trials involving repeated sprint exercise (5 × 6 s) before and after two 45 min bouts of a football specific intermittent treadmill protocol in the heat (33.0 ± 0.2°C; 53 ± 2% relative humidity). Participants wore a neck-cooling collar in one of the trials (CC). Mean power output and peak power output declined over time in both trials but were higher in CC (540 ± 99 v 507 ± 122 W, d = 0.32; 719 ± 158 v 680 ± 182 W, d = 0.24 respectively). The improved power output was particularly pronounced (d = 0.51-0.88) after the 2nd 45 min bout but the CC had no effect on % fatigue. The collar lowered neck temperature and the thermal sensation of the neck (P < 0.001) but had no effect on heart rate, fluid loss, fluid consumption, lactate, glucose, plasma volume change, cortisol, or thermal sensation (P > 0.05). There were no trial differences but interaction effects were demonstrated for prolactin concentration and rating of perceived exertion (RPE). Prolactin concentration was initially higher in the collar cold trial and then was lower from 45 min onwards (interaction trial × time P = 0.04). RPE was lower during the football intermittent treadmill protocol in the collar cold trial (interaction trial × time P = 0.01). Neck-cooling during exercise improves repeated sprint performance in a hot environment without altering physiological or neuroendocrinological responses. RPE is reduced and may partially explain the performance improvement.

Human Vγ9/Vδ2 T cells: Innate adaptors of the immune system

Unconventional T cells are gaining center stage as important effector and regulatory cells that orchestrate innate and adaptive immune responses. Human Vγ9/Vδ2 T cells are amongst the best understood unconventional T cells, as they are easily accessible in peripheral blood, can readily be expanded and manipulated in vitro, respond to microbial infections in vivo and can be exploited for novel tumor immunotherapies. We here review findings that suggest that Vγ9/Vδ2 T cells, and possibly other unconventional human T cells, play an important role in bridging innate and adaptive immunity by promoting the activation and differentiation of various types of antigen-presenting cells (APCs) and even turning into APCs themselves, and thereby pave the way for antigen-specific effector responses and long-term immunological memory. Although the direct physiological relevance for most of these mechanisms still needs to be demonstrated in vivo, these findings may have implications for novel therapies, diagnostic tests and vaccines.

Microbe-specific unconventional T cells induce human neutrophil differentiation into antigen cross-presenting cells

The early immune response to microbes is dominated by the recruitment of neutrophils whose primary function is to clear invading pathogens. However, there is emerging evidence that neutrophils play additional effector and regulatory roles. The present study demonstrates that human neutrophils assume Ag cross-presenting functions and suggests a plausible scenario for the local generation of APC-like neutrophils through the mobilization of unconventional T cells in response to microbial metabolites. Vγ9/Vδ2 T cells and mucosal-associated invariant T cells are abundant in blood, inflamed tissues, and mucosal barriers. In this study, both human cell types responded rapidly to neutrophils after phagocytosis of Gram-positive and Gram-negative bacteria producing the corresponding ligands, and in turn mediated the differentiation of neutrophils into APCs for both CD4(+) and CD8(+) T cells through secretion of GM-CSF, IFN-γ, and TNF-α. In patients with acute sepsis, circulating neutrophils displayed a similar APC-like phenotype and readily processed soluble proteins for cross-presentation of antigenic peptides to CD8(+) T cells, at a time when peripheral Vγ9/Vδ2 T cells were highly activated. Our findings indicate that unconventional T cells represent key controllers of neutrophil-driven innate and adaptive responses to a broad range of pathogens.

The energy costs of wading in water

Studies measuring the energy costs of wading in water have been limited to higher walking speeds in straight lines, in deep water. However, much foraging in water, by both humans and other primates, is conducted in the shallows and at low speeds of locomotion that include elements of turning, as befits searching for cryptic or hidden foods within a patch. The present study brings together data on the rate of oxygen consumption during wading by humans from previous studies, and augments these with new data for wading in shallower depths, with slower and more tortuous walking, to obtain a better understanding both of the absolute costs of wading in typical scenarios of aquatic foraging and of how the cost of wading varies as a function of water depth and speed of locomotion. Previous and present data indicate that, at low speeds, wading has a similar energetic cost to walking on land, particularly at lower water depths, and only at higher speeds is the cost of wading noticeably more expensive than when water is absent. This is probably explained by the relatively small volume of water that must be displaced during locomotion in shallow waters coupled with the compensating support to the limbs that the water affords. The support to the limbs/body provided by water is discussed further, in the context of bipedal locomotion by non-human primates during wading.

Differential actions of orexin receptors in brainstem cholinergic and monoaminergic neurons revealed by receptor knockouts: implications for orexinergic signaling in arousal and narcolepsy

Orexin neuropeptides influence multiple homeostatic functions and play an essential role in the expression of normal sleep-wake behavior. While their two known receptors (OX₁ and OX₂) are targets for novel pharmacotherapeutics, the actions mediated by each receptor remain largely unexplored. Using brain slices from mice constitutively lacking either receptor, we used whole-cell and Ca²⁺ imaging methods to delineate the cellular actions of each receptor within cholinergic [laterodorsal tegmental nucleus (LDT)] and monoaminergic [dorsal raphe (DR) and locus coeruleus (LC)] brainstem nuclei—where orexins promote arousal and suppress REM sleep. In slices from OX^−/−₂ mice, orexin-A (300 nM) elicited wild-type responses in LDT, DR, and LC neurons consisting of a depolarizing current and augmented voltage-dependent Ca²⁺ transients. In slices from OX^−/−₁ mice, the depolarizing current was absent in LDT and LC neurons and was attenuated in DR neurons, although Ca²⁺-transients were still augmented. Since orexin-A produced neither of these actions in slices lacking both receptors, our findings suggest that orexin-mediated depolarization is mediated by both receptors in DR, but is exclusively mediated by OX₁ in LDT and LC neurons, even though OX₂ is present and OX₂ mRNA appears elevated in brainstems from OX^−/−₁ mice. Considering published behavioral data, these findings support a model in which orexin-mediated excitation of mesopontine cholinergic and monoaminergic neurons contributes little to stabilizing spontaneous waking and sleep bouts, but functions in context-dependent arousal and helps restrict muscle atonia to REM sleep. The augmented Ca²⁺ transients produced by both receptors appeared mediated by influx via L-type Ca²⁺ channels, which is often linked to transcriptional signaling. This could provide an adaptive signal to compensate for receptor loss or prolonged antagonism and may contribute to the reduced severity of narcolepsy in single receptor knockout mice.

Dual orexin actions on dorsal raphe and laterodorsal tegmentum neurons: noisy cation current activation and selective enhancement of Ca2+ transients mediated by L-type calcium channels

The hypocretin/orexins (Hcrt/Orxs) are hypothalamic neuropeptides that regulate stress, addiction, feeding, and arousal behaviors. They depolarize many types of central neurons and can increase [Ca2+]i in some, including those of the dorsal raphe (DR) and laterodorsal tegmental (LDT) nuclei-two structures likely to contribute to the behavioral actions of Hcrt/Orx. In this study, we used simultaneous whole cell and Ca2+-imaging methods in mouse brain slices to compare the Hcrt/Orx-activated current in DR and LDT neurons and to determine whether it contributes to the Ca2+ influx evoked by Hcrt/Orx. We found Hcrt/Orx activates a similar noisy cation current that reversed near 0 mV in both cell types. Contrary to our expectation, this current did not contribute to the somatic Ca2+ influx evoked by Hcrt/Orx. In contrast, Hcrt/Orx enhanced the Ca2+ transients produced by voltage steps (-60 to -30 mV) by approximately 30% even in neurons lacking an inward current. This effect was abolished by nifedipine, augmented by Bay-K and abolished by bisindolylmaleimide I. Thus Hcrt/Orx has two independent actions: activation of noisy cation channels that generate depolarization and activation of a protein kinase C (PKC)-dependent enhancement of Ca2+ transients mediated by L-type Ca2+ channels. Immunocytochemistry verified that both these actions occurred in serotonergic and cholinergic neurons, indicating that Hcrt/Orx can function as a neuromodulator in these key neurons of the reticular activating system. Because regulation of Ca2+ transients mediated by L-channels is often linked to the control of transcriptional signaling, our findings imply that Hcrt/Orxs may also function in the regulation of long-term homeostatic or trophic processes.

Urotensin II acts as a modulator of mesopontine cholinergic neurons

Urotensin II (UII) is a vasomodulatory peptide that was not predicted to elicit CNS activity. However, because we have recently shown that the urotensin II receptor (UII-R) is selectively expressed in rat mesopontine cholinergic (MPCh) neurons, we hypothesize that UII may have a central function. The present study demonstrates that the UII system is able to modulate MPCh neuron activity. Brain slice experiments demonstrate that UII excites MPCh neurons of the mouse laterodorsal tegmentum (LDTg) by activating a slow inward current. Furthermore, microinfusion of UII into the ventral tegmental area produces a sustained increase in dopamine efflux in the nucleus accumbens, as measured by in vivo chronoamperometry. In agreement with UII activation of MPCh neurons, intracerebroventricular injections of UII significantly modulate ambulatory movements in both rats and mice but do not significantly affect startle habituation or prepulse inhibition. The present study establishes that UII is a neuromodulator that may be exploited to target disorders involving MPCh dysfunction.

Intra- and inter-areal connections between the primary visual cortex V1 and the area immediately surrounding V1 in the rat

We have qualitatively and quantitatively analysed the anatomical connections within and between rat primary visual cortex (V1) and the rim region surrounding area V1, using both ortho- and retrograde anatomical tracers (biotinylated dextran amine, biocytin, cholera toxin b subunit). From the analysis of the projection patterns, and with the assumption that single points in the rat visual cortex, as in other species, have projection fields made up of multiple patches of terminals, we have concluded that just two V1 recipient areas occupy the entire rim region: an anterolateral area, probably homologous with V2 in other mammals, previously named Oc2L, and a medial area, corresponding to Oc2M. A non-reciprocal projection from the anterolateral area to the medial area was identified. Small injections (300-600microm uptake zone diameter) of the anatomical tracers in area V1, or in the rim region, label orthograde intra-areal connections from each injection site to offset small patches. This is found in all regions of the rim and within at least the relatively expanded central dorsal field representation of V1. From the extent of these projections in V1 and the two rim regions, we have estimated that the neurons at the injection site send diverging laterally spreading projections to other neurons whose receptive fields share any part of the area included in the pooled receptive fields of the neurons at the injection site. Orthogradely labelled inter-areal feedforward projections from V1 to either rim region are estimated to diverge in their projections to neurons that share any part of the area of the pooled receptive fields of the V1 intra-areal connectional field of the same injection. The orthogradely labelled feedback projections to V1, from injection sites in either rim region, reach V1 neurons whose pooled receptive fields match those of the neurons in the rim injection site, i.e. with no divergence. Despite patchy anatomical connectional fields, our estimates indicate that visual space is represented continuously in the receptive fields of neurons postsynaptic to each intra- or inter-areal field of orthograde label. We suggest that, despite the absence of regularly mapped functions in rat V1 (e.g. regularly arranged orientation specificity), which in other species (e.g. primates and cats) relate to the patchy connectional patterns, the rat visual cortex intra- and inter-areal anatomical connections follow similar patterns and scaling factors to those in other species.

Anatomical comparison of the macaque and marsupial visual cortex: common features that may reflect retention of essential cortical elements

This study identifies fundamental anatomical features of primary visual cortex, area V1 of macaque monkey cerebral cortex, i.e., features that are present in area V1 of phylogenetically distant mammals of quite different lifestyle and features that are common to other regions of cortex. We compared anatomical constituents of macaque V1 with V1 of members of the two principal marsupial lines, the dunnart and the quokka, that diverged from the eutherian mammalian line over 135 million years ago. Features of V1 common to both macaque and marsupials were then compared with anatomical features we have previously described for macaque prefrontal cortex. Despite large differences in overall area and thickness of V1 cortex between these animals, the absolute size of pyramidal neurons is remarkably similar, as are their specific dendritic branch patterns and patterns of distribution of intrinsic axons. Pyramidal neuron patchy connections exist in the supragranular V1 in both the marsupial quokka and macaque as well as in macaque prefrontal cortex. Several specific types of aspinous interneurons are common to area V1 in both marsupial and macaque and are also present in macaque prefrontal cortex. Spiny stellate cells are a common feature of the thalamic-recipient, mid-depth lamina 4 of V1 in all three species. Because these similarities exist despite the very different lifestyles and evolutionary histories of the animals compared, this finding argues for a highly conserved framework of cellular detail in macaque primary visual cortex rather than convergent evolution of these features.

Distribution of GAD-like immunoreactivity in the retina and central visual system of Rana pipiens

Immunohistochemistry was used to survey the distribution of glutamic acid decarboxylase (GAD), the synthesizing enzyme for gamma-aminobutyric acid (GABA), throughout the visual system of the frog Rana pipiens. GAD-like immunoreactivity (GAD-LI) was assessed in the retina, in primary retinorecipient targets, and in thalamic nuclear groups postsynaptic to primary retinal terminal zones. Within the retina, the inner plexiform layer displayed intense GAD-LI, but immunoreactivity was absent in the ganglion cell layer (GCL). Putative amacrine, bipolar, and horizontal cell somata were also labeled. Centrally, GAD-LI was observed in all primary visual nuclei. Dense, GAD-like immunoreactive punctate structures (puncta), presumably terminals, were observed in the pretectal nucleus lentiformis mesencephali, posterior thalamic neuropil, and uncinate neuropil. GAD-like immunoreactive puncta were noted in several laminae of the optic tectum, with the highest concentrations located within the 9th and 8th laminae. Moderate numbers of GAD-like immunoreactive puncta were found in the mesencephalic nucleus of the basal optic root, and two thalamic neuropils--corpus geniculatum and neuropil of Bellonci. The ventrolateral area, posterocentral nucleus, and posterolateral nucleus all contained sparse amounts of GAD-LI. These observations suggest that GABA plays an important physiological role in all central visual areas of Rana pipiens.

Sexual dimorphism in the vasotocin system of the bullfrog (Rana catesbeiana)

Arginine vasotocin (AVT) is widespread in amphibian brains, where its levels have been correlated with reproductive behaviors. To better understand which neural systems are involved in central actions of AVT, we used immunocytochemistry to compare the distribution of AVT in the brains of male and female bullfrogs (Rana catesbeiana). AVT-immunoreactive cells were observed in the septal nucleus, amygdala pars lateralis, magnocellular preoptic area, suprachiasmatic nucleus, and hypothalamus. AVT-immunoreactive cells were also found in the pretrigeminal nucleus, but only in animals killed in the fall. Immunoreactive fibers were broadly distributed in hypothalamic and extrahypothalamic areas. The most obvious sex differences were found in the amygdala pars lateralis, where the density of immunoreactive cells and fibers was significantly greater in male than in female bullfrogs. In addition, in the habenular nucleus, males had a denser distribution of AVT-immunoreactive fibers than females. In the suprachiasmatic nucleus, AVT-immunoreactive cells were larger in females than in males but did not differ in number. Since the areas that showed sex differences in AVT distribution have also been implicated in control of reproductive behaviors, they may form the neural substrates for the effects of AVT on sexually dimorphic behaviors in amphibians.