Marginal Pool Research Articles

Blood concentrations of brain natriuretic peptide (Nt-pro-BNP) and the regulation of hemodynamic reactions in healthy adult Arctic residents

BACKGROUND: In previous studies, we have observed that the levels of Nt-pro-BNP in healthy individuals are lower than among patients with coronary heart disease and hypertension. Additionally, Nt-pro-BNP concentration increases with age. Interestingly, Arctic residents have higher levels of Nt-pro-BNP compared to those living in other northern territories.
 AIM: To study the role of Nt-pro-BNP in the regulation of hemodynamic reactions in adults residing in the Arctic.
 MATERIALS AND METHODS: In total, 111 healthy adults (66 women and 45 men) aged 4655 years living and working on Svalbard, and in the Murmansk region comprised the study group. The comparison group included 118 healthy adults of the same age from the Arkhangelsk region (59 women and 59 men). Peripheral venous blood samples were taken. Hemogram and concentrations of CD3+, CD4+, CD8+, CD10+, CD16+, CD19+, CD23+, CD25+, CD71+ lymphocytes were studied by an indirect immunoperoxidase reaction and a flow cytometry. Blood concentrations of Nt-pro-BNP, endothelin-1, total NO, endogenous NO2, nitrate NO3, cortisol, norepinephrine, epinephrine were assessed using enzyme immunoassay. Data were presented as means and standard errors of the mean (Mm). Depending on the distribution, unpaired t-tests or MannWhitney U-tests were used for all comparisons.
 RESULTS: Blood concentration of Nt-pro-BNP was higher in the Arctic residents compared with those living in Arkhangelsk. Elevated concentrations of Nt-pro-BNP in the Arctic residents were associated with higher levels of norepinephrine and cortisol and lower concentrations of epinephrine and endothelin-1. Moreover, we observed a re-distribution of lymphocytes and monocytes from the circulating to the marginal pool. These features of the hemodynamic reaction were more pronounced among the Arctic residents and among women in all settings.
 CONCLUSION: The effect of natriuretic peptide is associated with simultaneous activation of the concurrent activation of norepinephrine and cortisol secretion, which poses a risk of disrupting the body's mechanisms for maintaining a narrow range of osmolarity in the internal environment.

In vivo imaging of CD8+ T cells in metastatic cancer patients: first clinical experience with simultaneous [89Zr]Zr-Df-IAB22M2C PET/MRI.

Aim/Introduction: Despite the spectacular success of immune checkpoint inhibitor therapy (ICT) in patients with metastatic cancer, only a limited proportion of patients benefit from ICT. CD8+ cytotoxic T cells are important gatekeepers for the therapeutic response to ICT and are able to recognize MHC class I-dependent tumor antigens and destroy tumor cells. The radiolabeled minibody [89Zr]Zr-Df-IAB22M2C has a high affinity for human CD8+ T cells and was successfully tested in a phase I study. Here, we aimed to gain the first clinical PET/MRI experience with the noninvasive assessment of the CD8+ T-cell distribution in cancer patients by in vivo [89Zr]Zr-Df-IAB22M2C with a distinct focus of identifying potential signatures of successful ICT. Material and Methods: We investigated 8 patients with metastasized cancers undergoing ICT. Radiolabeling of Df-IAB22M2C with Zr-89 was performed according to Good Manufacturing Practice. Multiparametric PET/MRI was acquired 24 h after injection of 74.2±17.9 MBq [89Zr]Zr-Df-IAB22M2C. We analyzed [89Zr]Zr-Df-IAB22M2C uptake within the metastases and within primary and secondary lymphatic organs. Results: [89Zr]Zr-Df-IAB22M2C injection was tolerated well without noticeable side effects. The CD8 PET/MRI data acquisitions 24 hours post-administration of [89Zr]Zr-Df-IAB22M2C revealed good image quality with a relatively low background signal due to only low unspecific tissue uptake and marginal blood pool retention. Only two metastatic lesions showed markedly increased tracer uptake in our cohort of patients. Furthermore, we observed high interpatient variability in [89Zr]Zr-Df-IAB22M2C uptake within the primary and secondary lymphoid organs. Four out of five ICT patients exhibited rather high [89Zr]Zr-Df-IAB22M2C uptake in the bone marrow. Two of these four patients as well as two other patients yielded pronounced [89Zr]Zr-Df-IAB22M2C uptake within nonmetastatic lymph nodes. Interestingly, cancer progression in ICT patients was associated with a relatively low [89Zr]Zr-Df-IAB22M2C uptake in the spleen compared to the liver in 4 out of the 6 patients. Lymph nodes with enhanced [89Zr]Zr-Df-IAB22M2C uptake revealed significantly reduced apparent diffusion coefficient (ADC) values in diffusion weighted MRI. Conclusion: Our first clinical experiences revealed the feasibility of [89Zr]Zr-Df-IAB22M2C PET/MRI in assessing potential immune-related changes in metastases and primary and secondary lymphatic organs. According to our results, we hypothesize that alterations in [89Zr]Zr-Df-IAB22M2C uptake in primary and secondary lymphoid organs might be associated with the response to ICT.

MHCII Expression on Peripheral Blood Monocytes in Canine Lymphoma: An Impact of Glucocorticoids.

Simple SummaryLoss or decreased expression of human leukocyte antigen—D-related (HLA-DR) on the surface of monocytes is related to the dysfunction of the immune system and was reported in human neoplasia, including lymphoma. Canine lymphoma is frequently presented as a valuable comparative model for studies on human non-Hodgkin’s lymphoma. However, there are no studies on the expression of analogue proteins—MHCII antigens—on monocytes in canine lymphoma. In this study, we have evaluated the changes in the expression of MHCII on monocytes in the blood of dogs with lymphoma before any treatment and in dogs that had previously received glucocorticoids. Glucocorticoids are often used by clinicians as first drugs after diagnosis for immediate health improvement and are known to impact monocyte number. We have shown an increase in the percentage of MHCII− monocytes, regardless of treatment. However, only in dogs that had received glucocorticoids were changes in the proportion of MHCII+ and MHCII− monocytes reflected also by the changes in the number of MHCII− monocytes in the blood, which was significantly higher. Evaluating the changes in canine monocytes might be helpful in the diagnosis of various tumor types, monitoring of the treatment or assessing the immune status of dogs.An increase in the percentage of monocytes with reduced HLA-DR expression and immunosuppressive properties has been reported in numerous human neoplastic diseases, including lymphoma. However, there are no analogous studies on phenotypical variations in the peripheral blood monocytes in dogs with lymphoma. The aim of this study was to determine the difference in the expression of the MHCII molecule on peripheral blood monocytes in dogs with lymphoma before any treatment (NRG) and in dogs that had previously received glucocorticoids (RG) in comparison to healthy dogs. Flow cytometry immunophenotyping of peripheral blood leukocytes was performed using canine-specific or cross-reactive antibodies against CD11b, CD14 and MHCII. In the blood of dogs with lymphoma (NRG and RG), compared to that of healthy ones, the MHCII+ and MHCII− monocytes ratio was changed due to an increase in the percentage of MHCII− monocytes. The number of MHCII− monocytes was significantly higher only in RG dogs compared to healthy ones, which might result from the release of these cells from the blood marginal pool due to the action of glucocorticoids. Our results encourage further studies to assess if changes in MHCII expression affect immune status in dogs with lymphoma.

Availability and Structure of Coarse Woody Debris in Hemiboreal Mature to Old-Growth Aspen Stands and Its Implications for Forest Carbon Pool

European aspen deadwood is extensively studied as a habitat for saproxylic species, while less is known of its dynamics and role in carbon sequestration. We studied unmanaged mature (41–60 years), moderately overmature (61–80 years), overmature (81–100 years), and old-growth (101–140 years) and managed mature and moderately overmature aspen stands on fertile mineral soils. In unmanaged stands, marginal mean CWD volume was from 67.3 ± 12.1 m3 ha−1 in moderately overmature to 92.4 ± 5.1 m3 ha−1 in old-growth stands, with corresponding marginal mean CWD carbon pool 8.2 ± 1.6 t ha−1 and 12.5 ± 0.7 t ha−1 (all p > 0.05), respectively. High CWD volume was present in most stands, by at least two-thirds of plots comprising more than 20 m3 ha−1, and about half of CWD was larger than 30 cm in diameter. Changes in CWD species composition toward a higher proportion of deciduous deadwood in old-growth stands, together with a high volume of recently dead trees, suggest early senescence of the dominant aspen cohort.

Coelomocyte replenishment in adult Asterias rubens: the possible ways.

The origin of cells involved in regeneration in echinoderms remains an open question. Replenishment of circulatory coelomocytes-cells of the coelomic cavity in starfish-is an example of physiological regeneration. The coelomic epithelium is considered to be the main source of coelomocytes, but many details of this process remain unclear. This study examined the role of coelomocytes outside circulation, named marginal coelomocytes and small undifferentiated cells of the coelomic epithelium in coelomocyte replenishment in Asterias rubens. A qualitative and quantitative comparison of circulatory and marginal coelomocytes, as well as changes of circulatory coelomocyte concentrations in response to injury at different physiological statuses, was analysed. The presence of cells morphologically similar to coelomocytes in the context of coelomic epithelium was evaluated by electron microscopy. The irregular distribution of small cells on the surface and within the coelomic epithelium was demonstrated and the origin of small undifferentiated cells and large agranulocytes from the coelomic epithelium was suggested. Two events have been proposed to mediate the replenishment of coelomocytes in the coelom: migration of mature coelomocytes of the marginal cell pool and migration of small undifferentiated cells of the coelomic epithelium. The proteomic analysis of circulatory coelomocytes, coelomic epithelial cells and a subpopulation of coelomic epithelial cells, enriched in small undifferentiated cells, revealed proteins that were common and specific for each cell pool. Among these molecules were regulatory proteins, potential participants of regenerative processes.

Pseudoneutropenia as a factor-limiting access to chemotherapy for cancer patients: the effect of a simple meal.

Absolute neutrophil count (ANC) below 1.5 G/l or 1 G/l is commonly used as a factor to determine the decision to administer antineoplastic treatment including chemotherapy and novel agents to cancer patients. This practice is based on observations that below this ANC, there is an increased risk of bacterial and fungal infection. This is further based on the assumption that this parameter always correctly reflects the true shortage of these germ-fighting cells in patients. In reality, the circulating pool of neutrophils is only one of four reservoirs (bone marrow, circulating, marginal and tissue pools) and its size is influenced not only by shortage but also by transient shift of cells between these reservoirs. The aim of this study was to evaluate whether repeated blood collection affects ANC in the patient. We retrospectively analysed the medical records of cancer patients with 0.8 G/l ≤ ANC < 1.5 G/l in whom CBC was repeated based on the physician's decision, which was done on the same day roughly 2 h after the first one. The patients at the time of repeating CBC had consumed breakfast. In 31 out of 32 patients, ANC exceeded 1 G/l or 1.5 G/l and antineoplastic treatment was administered as originally planned. There were no infectious complications observed. Cancer patients should not be fasting prior to blood collection, with the exception of special and rare situations. To achieve the maximum clinical benefit, delays and/or reductions of antineoplastic treatment should be avoided wherever possible. Pseudoneutropenia is an unnecessary reason for postponing chemotherapy.

Hematological reactions in the inhabitants of the Arctic on a polar night and a polar day.

PurposeThe purpose of this study is to identify the features of hematological reactions in the inhabitants of the Arctic territory of the Kola Peninsula on a polar night and a polar day.MethodsThe study included determining the hemogram, neutrograms, monocytograms, lymphocytograms, and phagocytic activity neutrophil granulocytes, enzyme immunoassay, flow cytometry.ResultsIt was established that during the polar night, there is an increase in the activity of migration of leukocytes from the marginal pool to the circulating pool, an increase in the intensity of phagocytosis by neutrophils, an increase in the concentrations of noradrenaline, cortisol, as well as an increase in hyperergic reactions involving immunoglobulin E and inhibitory processes due to an increase in interleukin‐10.ConclusionA prolonged lack of sunlight causes a decrease in the reserve capacity for regulating homeostasis and forces the body to use proliferative reactions, which is reflected in the increase in stab neutrophils, large lymphocytes in the structure of the lymphocytogram and CD10+ lymphocytes. In winters, the frequency of neutropenia registration also increases to 13% of cases, the deficit of phagocytic activity of neutrophils; lymphopenia is recorded in 20% with T‐helper deficiency (37%). A part of the population probably has a relatively high degree of vulnerability to the action of natural environmental factors and is not able to completely restore the initial levels of the effectiveness of adaptation reactions in the summer. So at the end of the polar day in 8% of adults born in the north, neutropenia is recorded and in 21%—lymphopenia.

Deadwood Characteristics in Mature and Old-Growth Birch Stands and Their Implications for Carbon Storage

As one of the most abundant tree species in the hemiboreal zone, birch is important from both commercial and biodiversity perspectives. While old-growth deciduous stands are important for biodiversity conservation with an emphasis on deadwood availability, the role that deadwood in these stands plays in carbon sequestration remains unclear. We studied mature (71–110 years old) and old-growth (121–150 years old) birch stands on fertile mineral soils. The marginal mean deadwood volume was 43.5 ± 6.4 m3 ha−1 in all mature stands, 51.3 ± 7.1 m3 ha−1 in recently unmanaged mature stands, and 54.4 ± 4.4 m3 ha−1 in old-growth stands; the marginal mean deadwood carbon pool for each stand type was 5.4 ± 0.8 t·ha−1, 6.3 ± 0.9 t·ha−1, and 7.9 ± 0.6 t·ha−1, respectively. Deadwood volume was not related to stand productivity in terms of stand basal area, stand height, or stand age. The difference between mature and old-growth stands remained non-significant (p &lt; 0.05). A high volume of deadwood was almost continuously present throughout the landscape in assessed unmanaged sites; moreover, 88% of sample plots in old-growth stands and 63% of sample plots in mature stands had a deadwood volume higher than 20 m3·ha−1. Old-growth stands had a slightly greater volume of large deadwood than unmanaged mature stands; in both, almost half of the deadwood was more than 30 cm in diameter and approximately one-fifth had a diameter greater than 40 cm. Both groups of stands had similar proportions of coniferous and deciduous deadwood and lying and standing deadwood. Old-growth stands had a higher volume of recently and weakly decayed wood, indicating increased dieback during recent years.

Monocyte Subsets in Atherosclerosis and Modification with Exercise in Humans.

Atherosclerosis is a progressive pathological remodeling of the arteries and one of its hallmarks is the presence of chronic inflammation. Notably, there is an increased proportion and activation state of specific monocyte subsets in systemic blood circulation. Monocyte subsets have distinct contributions to the formation, progression, and destabilization of the atherosclerotic plaque. Strong clinical and epidemiological studies show that regular aerobic exercise mitigates the progression of cardiovascular disease. In fact, aerobic fitness is a powerful predictor of cardiovascular mortality in adults, independent of traditional risk factors such as hypertension and hyperlipidemia. Acute bouts and chronic exercise training modulate monocyte behavior, ranging from their recruitment from the bone marrow or marginal pool, to tissue margination and functional changes in cytokine and chemokine production. Such modulation could reflect a potential mechanism for the cardio-protective effect of exercise on atherosclerosis. This review summarizes the current knowledge of monocyte subsets and highlights what is known about their responses to exercise.

Environmental Determinants of Malaria Transmission Around the Koka Reservoir in Ethiopia.

New dam construction is known to exacerbate malaria transmission in Africa as the vectors of malaria—Anopheles mosquitoes—use bodies of water as breeding sites. Precise environmental mechanisms of how reservoirs exacerbate malaria transmission are yet to be identified. Understanding of these mechanisms should lead to a better assessment of the impacts of dam construction and to new prevention strategies. Combining extensive multiyear field surveys around the Koka Reservoir in Ethiopia and rigorous model development and simulation studies, environmental mechanisms of malaria transmission around the reservoir were examined. Most comprehensive and detailed malaria transmission model, Hydrology, Entomology, and Malaria Transmission Simulator, was applied to a village adjacent to the reservoir. Significant contributions to the dynamics of malaria transmission are shaped by wind profile, marginal pools, temperature, and shoreline locations. Wind speed and wind direction influence Anopheles populations and malaria transmission during the major and secondary mosquito seasons. During the secondary mosquito season, a noticeable influence was also attributed to marginal pools. Temperature was found to play an important role, not so much in Anopheles population dynamics, but in malaria transmission dynamics. Change in shoreline locations drives malaria transmission dynamics, with closer shoreline locations to the village making malaria transmission more likely. Identified environmental mechanisms help in predicting malaria transmission seasons and in developing village relocation strategies upon dam construction to minimize the risk of malaria.

Southeastern marginal West Pacific Warm Pool sea-surface and thermocline dynamics during the Pleistocene (2.5–0.5 Ma)

The internal development of the tropical West Pacific Warm Pool and its interaction with high latitude ocean regions on geological timescales is only poorly constrained. Based on two newly recovered sediment cores from the southeastern margin of the West Pacific Warm Pool (northern and southern Manihiki Plateau), we provide new aspects on the dynamically interacting ocean circulation at surface, subsurface, thermocline, and deep thermocline levels during the Pleistocene (~2.5–0.5Ma). Notably, the variability of thermocline and deep thermocline (~150–400m water depth) foraminiferal Mg/Ca-based temperatures with up to ~6°C amplitude variations exceeds those at shallower depths (down to ~120m) with only ~2–3°C temperature variations. A major gradual reorganization of the West Pacific Warm Pool oceanography occurred during the transitional time period of ~1.7–1.35Ma. Prior to ~1.7Ma, pronounced meridional and latitudinal gradients in sea-surface to subsurface ocean properties point to the eastward displacement of the West Pacific Warm Pool boundaries, with the South Pacific Convergence Zone being shifted further northeastward across Manihiki Plateau. Simultaneously, the low amplitude variations of thermocline and deep thermocline temperatures refer to an overall deep and stable thermocline.The meridional and zonal gradients in sea-surface and subsurface ocean properties within the West Pacific Warm Pool reveal a pronounced change after 1.5Ma, leading to a more southward position of the warm South Pacific Convergence Zone between ~1.35–0.9Ma and ~0.75–0.5Ma. Synchronous to the changes in the upper ocean, the deeper water masses experienced high amplitude variations in temperature, most prominently since ~1.5Ma. This and the dynamically changing thermocline were most likely associated to the impact of southern-sourced mode waters, which might have developed coincidently with the emergence of the East Pacific Cold Tongue and high latitude sea-surface cooling.

Proinflammatory Effects of Hypoglycemia in Humans With or Without Diabetes.

Severe hypoglycemic events have been associated with increased cardiovascular mortality in patients with diabetes, which may be explained by hypoglycemia-induced inflammation. We used ex vivo stimulations of peripheral blood mononuclear cells (PBMCs) and monocytes obtained during hyperinsulinemic-euglycemic (5.0 mmol/L)-hypoglycemic (2.6 mmol/L) clamps in 11 healthy participants, 10 patients with type 1 diabetes and normal awareness of hypoglycemia (NAH), and 10 patients with type 1 diabetes and impaired awareness (IAH) to test whether the composition and inflammatory function of immune cells adapt to a more proinflammatory state after hypoglycemia. Hypoglycemia increased leukocyte numbers in healthy control participants and patients with NAH but not in patients with IAH. Leukocytosis strongly correlated with the adrenaline response to hypoglycemia. Ex vivo, PBMCs and monocytes displayed a more robust cytokine response to microbial stimulation after hypoglycemia compared with euglycemia, although it was less pronounced in patients with IAH. Of note, hypoglycemia increased the expression of markers of demargination and inflammation in PBMCs. We conclude that hypoglycemia promotes mobilization of specific leukocyte subsets from the marginal pool and induces proinflammatory functional changes in immune cells. Inflammatory responses were less pronounced in IAH, indicating that counterregulatory hormone responses are key modulators of hypoglycemia-induced proinflammatory effects. Hypoglycemia-induced proinflammatory changes may promote a sustained inflammatory state.

Abstract # 1813 G-alpha-s-protein coupled receptor signaling suppresses integrin-mediated cell adhesion of antigen-specific human CD8+ T cells

An efficient immune response requires a selective and strong interaction of T cells with endothelium or target cells. These interactions are strengthened by the rapid induction of beta2-integrin-mediated adhesion upon chemokine receptor or T-cell receptor (TCR) stimulation, respectively. We and others have shown that an increase in G-alpha-s-protein coupled receptor (GalphasPCR) signaling, such as via beta2-adrenergic receptors counteracts chemokine-induced beta2-integrin activation and promotes de-adhesion and mobilization of effector CD8+ T cells from the marginal pool into the circulation. We asked whether GalphasPCR agonists also inhibit integrin activation induced by TCR stimulation of human antigen-specific T cells. Using soluble multimeric ICAM1-Fc-F(ab)2 fluorescent complexes, we developed a flow cytometry assay to identify integrin activation on virus-specific CD8+ T cells following short-term stimulation and staining with cytomegalovirus, Epstein–Barr virus, or influenza virus peptide-major histocompatibility complex class I HLA-multimers. From the GalphasPCR agonists used, epinephrine, norepinephrine, prostaglandins E2/D2 and adenosine strongly down-modulated the beta2-integrin activation on all virus-specific T cells and subsets of different stages of activation, while dopamine, serotonin and histamine had no effects. This active down-modulation of integrin activation through GalphasPCR signaling might be an essential mechanism by which the immune response is suppressed in a variety of pathologies characterized by increased levels of catecholamines (e.g., sleep deprivation), prostaglandins (e.g., tumor growth), or adenosine (e.g., hypoxia).

Abstract # 1711 Sleep maintains homeostasis and function of monocytes in mice

Sleep has a strong impact on both humoral and cellular immunity, but its acute effects on innate immune defense remain unclear. Here we elucidated in mice whether sleep affects innate immune cells and defense against systemic infection. Mice were allowed to sleep for 6 h at the beginning of the resting phase and compared to mice being awake for the same time. Sleep significantly increased the frequency and absolute cell counts of classical and non-classical monocytes in blood and secondary lymphatic organs whereas neutrophils (PMNs) were unaffected. Changes in monocyte numbers upon sleep compared to wakefulness remained for up to 24 h, did not involve CCR2 signaling and were not caused by impaired myelopoesis or bone marrow egress, cell death, differentiation into macrophages, or redistribution to peripheral tissues. On the contrary, SD also reduced macrophage numbers in spleen, as well as monocyte content in lung and gut. These findings suggest that sleep reduced monocyte adhesion in the marginal pool and promoted monocyte extravasation to peripheral tissues. In a mouse model of systemic bacterial infection to mimic sepsis, the bacterial load in the spleen of sleep mice was significantly reduced throughout the infection. Consequently, sleep significantly increased survival upon infection. These data provide evidence that sleep maintains homeostasis and function of innate immune cells thereby supporting early defense against bacterial pathogens.

Stably Stratified Flow in a Shallow Valley

Stratified nocturnal flow above and within a small valley of approximately 12-m depth and a few hundred metres width is examined as a case study, based on a network of 20 sonic anemometers and a central 20-m tower with eight levels of sonic anemometers. Several regimes of stratified flow over gentle topography are conceptually defined for organizing the data analysis and comparing with the existing literature. In our case study, a marginal cold pool forms within the shallow valley in the early evening but yields to larger ambient wind speeds after a few hours, corresponding to stratified terrain-following flow where the flow outside the valley descends to the valley floor. The terrain-following flow lasts about 10 h and then undergoes transition to an intermittent marginal cold pool towards the end of the night when the larger-scale flow collapses. During this 10-h period, the stratified terrain-following flow is characterized by a three-layer structure, consisting of a thin surface boundary layer of a few metres depth on the valley floor, a deeper boundary layer corresponding to the larger-scale flow, and an intermediate transition layer with significant wind-directional shear and possible advection of lee turbulence that is generated even for the gentle topography of our study. The flow in the valley is often modulated by oscillations with a typical period of 10 min. Cold events with smaller turbulent intensity and duration of tens of minutes move through the observational domain throughout the terrain-following period. One of these events is examined in detail.

G-alpha-s-coupled receptor signaling controls circadian rhythm in integrin-mediated cell adhesion of virus-specific human CD8+ T cells

Abstract Beta2-integrin activation in response to inside-out signaling by chemokines plays a major role in T-cell adhesion to the endothelium and the following extravasation into the inflamed tissue. We and others have previously shown that daytime increase in G-alpha-s-coupled receptor (GαsPCR) signaling, such as via beta2-adrenergic receptors counteracts integrin activation and promotes mobilization of effector CD8+ T cells from the marginal pool into the recirculation. In T cells, integrin activation is also rapidly induced by stimulation of antigen-specific T-cell receptors (TCR), resulting in the formation of stable immunological synapses. Therefore, we asked whether daytime increase in GαsPCR signaling inhibits integrin activation induced by TCR stimulation of human virus-specific T cells. Using ligand-complex-based adhesion assay to measure beta2-integrin activation, we show that affinity of integrins, which were activated by soluble cytomegalovirus virus peptide-major histocompatibility complex class I HLA-multimers is minimal during daytime. Additional in vitro experiments with GαsPCR agonists showed that epinephrine, norepinephrine, histamine, adenosine, and prostaglandins E2/D2 down-modulate the beta2-integrin activation; however, only epinephrine did so in physiological daytime concentrations, suggesting its mayor role in circadian regulation of T-cell adhesion. This active down-modulation of integrin activation through GαsPCR might be an essential mechanism of circadian immune defense regulation.

Common Marginal Cold Pools

AbstractThis study examines marginal cold pools forming in a shallow valley. “Marginal” refers to cold pools that are generally weak and intermittent. Nineteen stations were instrumented with sonic anemometers and accurate slow-response temperature measurements. The vertical structure of the cold pool is determined from a 20-m tower on the valley floor that includes eight levels of sonic anemometers and eight additional levels of slow-response temperature. On the basis of the data analysis, the traditional concept of a cold pool must be generalized to include cold-pool intermittency, complex variation of temperature related to some three-dimensional effects of terrain, and a diffuse cold-pool top. Different types of cold pools are classified in terms of the stratification and gradient of potential temperature along the slope. The strength of the cold pool is related to a forcing temperature scale that is proportional to the net radiative cooling divided by the wind speed above the valley. The scatter is large partly because of nonstationarity of the marginal cold pool in this shallow valley.

Role of neutrophils in pulmonary vaso-occlusion during sickle cell disease acute chest syndrome (CAM3P.200)

Abstract Sickle cell disease (SCD) is a hematological disorder that leads to sickling of red blood cells within the microcirculation. The sickle red blood cells (sRBCs) are not only less deformable, but also express α4β1, ICAM-4, Sialyl Lewis X and glycolipids not expressed on non SCD-RBCs. These rigid sRBCs can get sequestered in the microcirculation to cause painful vaso-occlusive crisis (VOC) in SCD patients. In the lung, VOC can contribute to acute chest syndrome, which is a form of acute lung injury. Several factors including the pro-adhesive sRBCs, the large marginated pool of neutrophils, and the hyper-inflammatory state present in SCD can contribute to pulmonary VOC. Although neutrophil-RBC-endothelium interactions are known to play a role in systemic VOC, the cellular mechanism that drives pulmonary VOC remains unknown. Intravital study of the lung microcirculation of live BERK or Townes SCD mice is conducted using two-photon microscopy. Prior to observation, mice are challenged with lipopolysaccharide or PBS to cause lung inflammation and administered (iv) with fluorescent anti-mouse Gr-1 and Ter-119 antibodies to label circulating neutrophils and RBCs, respectively. Vaso-occlusion is defined as cellular aggregation and stasis of blood flow within the lumen of pulmonary capillaries. Preliminary results reveal that circulating macro-aggregates of neutrophils and RBCs may play a role in pulmonary VOC.

Role of neutrophils in pulmonary vaso‐occlusion during sickle cell disease acute chest syndrome (669.6)

Sickle cell disease (SCD) is a hematological disorder that leads to sickling of red blood cells within the microcirculation. The sickle red blood cells (sRBCs) are not only less deformable, but also express α4β1, ICAM‐4, Sialyl Lewis X and glycolipids not expressed on non SCD‐RBCs. These rigid sRBCs can get sequestered in the microcirculation to cause painful vaso‐occlusive crisis (VOC) in SCD patients. In the lung, VOC can contribute to acute chest syndrome, which is a form of acute lung injury. Several factors including the pro‐adhesive sRBCs, the large marginated pool of neutrophils, and the hyper‐inflammatory state present in SCD can contribute to pulmonary VOC. Although neutrophil‐RBC‐endothelium interactions are known to play a role in systemic VOC, the cellular mechanism that drives pulmonary VOC remains unknown. Intravital study of the lung microcirculation of live BERK or Townes SCD mice is conducted using two‐photon microscopy. Prior to observation, mice are challenged with lipopolysaccharide or PBS to cause lung inflammation and administered (iv) with fluorescent anti‐mouse Gr‐1 and Ter‐119 antibodies to label circulating neutrophils and RBCs, respectively. Vaso‐occlusion is defined as cellular aggregation and stasis of blood flow within the lumen of pulmonary capillaries. Preliminary results reveal that circulating macro‐aggregates of neutrophils and RBCs may play a role in pulmonary VOC.Grant Funding Source: Supported by AHA, VMI startup account, and NIH Pulmonary T32 training grant

75. Circadian rhythms of human T cell subsets

Human blood T cell numbers show a high amplitude rhythm that peaks during sleep. This rhythm mainly reflects temporal changes in numbers of T cell subsets that are at early stages of differentiation like naive and central memory CD4 and CD8 T cells. In a set of experiments in healthy men we show that the early morning rise in endogenous cortisol enhances CXCR4 expression on these cells via the glucocorticoid receptor and thereby facilitates their extravasation presumably to the bone marrow. In contrast, numbers of terminally differentiated subsets like CD8 effector T cells are not influenced by cortisol and show an opposing rhythm that peaks during the wake period. Our findings indicate that this rhythm is governed by daytime increases in epinephrine that mobilizes CD8 effector T cells out of the marginal pool into the circulation presumably by attenuating adhesive CX3CR1 signaling. Thus cortisol and epinephrine govern opposing rhythms in numbers of T cell subsets at early and late stages of differentiation, respectively. We hypothesize that the bone marrow and the marginal pool are sheltering niches where these T cell subsets become inactive and receive survival signals. Upon release from the bone marrow, activation of naive and central memory T cells in lymph nodes may take place during sleep, while mobilization of CD8 effector T cells during daytime may ensure immunosurveillance of peripheral tissues.