Redistribution Of Leukocytes Research Articles

69. Redistribution of Leukocytes Following Stress Correlates With Resting State Networks

69. Redistribution of Leukocytes Following Stress Correlates With Resting State Networks

Analysis of phagocytic activity of peripheral blood and exudate leukocytes in patients with facial phlegmon

Objective. To assess the phagocytic activity of peripheral blood and exudate leukocytes in patients with facial phlegmon. Currently, relatively little attention is paid to assessing the functional activity of peripheral blood and exudate leukocytes in facial phlegmon, the incidence of which is characterized by an increase in the number of cases and, especially, among patients with comorbid pathology.
 Materials and methods. To study the phagocytic activity of leukocytes using a method based on the assessment of the absorption of formalinized sheep erythrocytes by neutrophils and monocytes, the samples of peripheral blood and exudate were obtained from 18 patients diagnosed facial phlegmon. Blood leukocytes obtained from 29 healthy donors were used as a comparison group.
 Results. It was shown that for patients with phlegmon of the face, an increase in the phagocytic activity of peripheral blood leukocytes is characteristic. There was observed a redistribution of leukocytes according to the number of absorbed objects towards an increase in actively phagocytizing cells 4438 721 per 1 l (in the comparison group 297 67 per 1 l; p 0.05). However, after migration to the foci of the pathological process, leukocytes lost their phagocytic activity and the number of phagocytic cells decreased to 35.0 8.3 % (for peripheral blood leukocytes of the same patients 64.3 5.4 %; p 0.05). Changes in the phagocytic activity of exudate leukocytes affected both neutrophils and monocytes.
 Conclusions. Thus, in patients with phlegmon of the face, changes in the phagocytic activity of blood leukocytes are probably associated with the indirect influence of cytokines, and in the focus of inflammation, leukocytes come under pressure from microorganisms. In such a situation, it is necessary to select an effective immunotropic therapy.

Female Scent Activated Expression of Arginase1 and Inducible NO-Synthetase in Lung of BALB/c Male Mice.

Simple SummaryThe scent of receptive females stimulates the breeding behavior of male mice. However, searching for breeding partners is associated with an increased risk of sniffing contaminated fecal and urinary marks containing various infectious agents, activating males’ immunity to protect them from infection. We found that the scent of specific pathogen-free (SPF) females stimulated male mouse immunity but was not associated with changes in the hormonal background. The percentage of T-cells decreased after the female scent treatment, affecting a specific immune reaction. The female scent caused an activation of the Nos2 and Arg1 genes in the macrophages in the lungs of male mice, which could increase resistance to potentially infectious agents. Our data showed activation of nonspecific immunity in male mice in response to the sniffing SPF female scent. We suggest that our study may impact future multidisciplinary behavioral and immunological studies and veterinary practice.Scent signals play an important role in the life of rodents. The scent of the opposite sex can modulate immunity. In mice populations with natural specific pathogens, in males, the scent of a female leads to a redistribution of leukocytes between the lung and the blood, resistance to the influenza virus, and a decrease in antibody production, but not in the development of inflammation induced by bacterial endotoxins. This study demonstrates the effect of the scent of soiled bedding of specific pathogen-free (SPF) status female mice on the percentage of different types of leukocytes in the blood, the expression of Nos2, Arg1, and Foxp3 genes, and the presence of M1/M2 macrophages in the lungs of male BALB/c mice. The scent of the female SPF mice caused a redistribution between T- and B-cells in the blood, the increase in the expression of Nos2, Arg1 genes, and the percentage of M1 type macrophages in the lung, but did not affect the different types of T-cells in the periphery or the lungs. Activation of macrophages in the lung is part of mucosal immunity, which is necessary for males as an adaptive mechanism to prevent potential infection during the search for a sexual partner.

Communication requested: Boar semen transport through the uterus and possible consequences for insemination

Recent insemination techniques bypass the interactions between sperm and the uterine wall because the semen is deposited deep into the tip of uterine horn or directly into the oviduct. Such techniques allow high dilution of the ejaculates. After normal mating, semen entering the uterus communicates with the uterine milieu. Intact sperm of high mitochondrial membrane potential bind to uterine epithelial cells, whereas most of the unbound sperm in the uterine lumen have damaged membranes. Lectins are the most likely factors to mediate these sperm–uterine interactions. The lectin wheat germ agglutinin is known to induce the strongest binding of sperm, whereas binding is impaired when sialic acid receptors are blocked by wheat germ agglutinin. This suggests that sialic acid is involved in porcine sperm–endometrium interactions, and it is hypothesized that the use of a semen extender supplemented with sialidase would allow insemination with reduced sperm numbers. A lack of contact of sperm and seminal plasma with the uterine wall, as a result of deep insemination, may adversely affect (1) events during ovulation, (2) induction of immunologic tolerance against paternal antigens, (3) preparation of the endometrium for implantation and placentation, and (4) immunologic support required for the fetus during pregnancy. Seminal plasma is known to signal post-insemination changes in the uterine endometrium involving the redistribution of leukocytes. This may involve migration of leukocytes from the uterine wall to the ovary, as seminal plasma particularly increases the appearance of the major histocompatibility complex class II-positive cells. Uterine epithelial cells respond to sperm binding by the production of pro- or anti-inflammatory cytokines. These cytokines may include synchronizing substances, transferred through a counter-current pathway to the ipsilateral ovary, thereby accelerating the final maturation of preovulatory follicles and advancing time of ovulation. In several species, an ovulation-inducing factor exists in seminal plasma, first identified as ß-nerve growth factor in camelid semen, indicating another pathway that influences the hypothalamic-pituitary-gonadal axis. In summary, low-dose inseminations may not necessarily require semen deposition deep into the uterine horn, as binding inhibitors can circumvent the binding of sperm to the uterine wall. However, subsequent immune-relevant events that control ovulation and prepare the uterine milieu for the developing embryo should be taken into account.

Differential Effects of Escherichia coli Subtilase Cytotoxin and Shiga Toxin 2 on Chemokine and Proinflammatory Cytokine Expression in Human Macrophage, Colonic Epithelial, and Brain Microvascular Endothelial Cell Lines

Subtilase cytotoxin (SubAB) is the prototype of a recently emerged family of AB5 cytotoxins produced by Shiga-toxigenic Escherichia coli (STEC). Its mechanism of action involves highly specific A-subunit-mediated proteolytic cleavage of the essential endoplasmic reticulum (ER) chaperone BiP. Our previous in vivo studies showed that intraperitoneal injection of purified SubAB causes a major redistribution of leukocytes and elevated leukocyte apoptosis in mice, as well as profound splenic atrophy. In the current study, we investigated selected chemokine and proinflammatory cytokine responses to treatment with SubAB, a nontoxic derivative (SubAA272B), or Shiga toxin 2 (Stx2) in human macrophage (U937), brain microvascular endothelial (HBMEC), and colonic epithelial (HCT-8) cell lines, at the levels of secreted protein, cell-associated protein, and gene expression. Stx2 treatment upregulated expression of chemokines and cytokines at both the protein and mRNA levels. In contrast, SubAB induced significant decreases in secreted interleukin-8 (IL-8) and monocyte chemoattractant protein 1 (MCP-1) in all three tested cell lines and a significant decrease in secreted IL-6 in HBMECs. The downregulation of secreted chemokines or cytokines was not observed in SubAA272B-treated cells, indicating a requirement for BiP cleavage. The downregulation of secreted chemokines and cytokines by SubAB was not reflected at the mRNA and cell-associated protein levels, suggesting a SubAB-induced export defect.

The inhibition of rat leukocytes apoptosis under the condition of experimental diabetes mellitus type 1 by Galega officinalis L.extract

The article contains the data of Galega officinalis extract (GOE) nonalkaloid-containing fraction influence on the structural and functional state of leukocytes under the condition of experimental diabetes mellitus type 1 (EDM). Immunohistochemical method has shown the quantitative redistribution of leukocytes containing proapoptotic protein p53 and PARylated [poly(ADP-ribosyl) ated] proteins under EDM conditions and admission of the tested extract. GOE administration to animals with EDM leads to the reduction in the number of cells with positive and strongly positive reaction to the p53 protein and PARylated proteins content, indicating its depressing effect on apoptosis of immune cells.

Inducible bronchus-associated lymphoid tissue reduces Th2-driven pathology by redistributing leukocytes within the lung (P6214)

Abstract Inducible bronchus-associated lymphoid tissue (iBALT) is an ectopic lymphoid tissue formed in the lung after pulmonary infection or inflammation. This local lymphoid tissue is structurally similar to conventional secondary lymphoid organs, with separated B and T cell areas, specialized stromal cells and lymphoid dendritic cells (DCs). Here, we tested whether the presence of iBALT affects pulmonary immune responses to allergens. We induced iBALT formation in neonatal mice by pulmonary administration of LPS, and when the mice were adults, challenged them intranasally with OVA. We found that although mice with iBALT had more lymphocytes in their lungs, they had fewer eosinophils, less goblet cells and had reduced Th2 cytokine production in bronchoalveolar (BAL) fluid and lung tissue after OVA challenge. Surprisingly, using IL-4 reporter and by transferring OVA-specific OT-II cells, we found that the presence of iBALT did not reduce the number of Th2 cells that accumulated in the lung. Despite similar numbers of Th2 effectors in the lungs of mice with and without iBALT, we found that Th2 cells were differentially distributed in these two groups of mice. Those in the lungs of mice without iBALT were more widely dispersed, whereas the cells in the lungs of mice with iBALT were predominantly concentrated in the lymphoid tissue. These results suggest that the reduction in Th2-driven pathology with iBALT is due to the redistribution of leukocytes within the lung after iBALT formation.

Changes in transcriptional output of human peripheral blood mononuclear cells following resistance exercise

Various types of exercise alter the population of circulating peripheral blood mononuclear cells (PBMCs) and change their transcriptional output. This work examines changes in PBMC populations and transcription in response to resistance exercise training (RET), and identify key transcriptional changes in PBMCs that may play a role in altering peripheral tissues in response to RET. Ten resistance-trained men (20-24 years), performed an acute bout of RET for ~30 min following a 12 h fast. Venous blood was sampled at rest, immediately following exercise, and at 2 h post-exercise and analyzed for total and differential leukocytes and global gene expression using Affymetrix Genechips. Results showed elevated leukocytes, monocytes, lymphocytes, and lactate values immediately post-exercise (P < 0.05) over baseline. At 2 h post-exercise, leukocytes, and granulocytes remained elevated (P < 0.05), whereas lymphocytes were lower than (P < 0.05) baseline values. Initial microarray results showed the greatest transcriptional changes in pathways related to immune response, inflammation, and cellular communication. The change in PBMC population (2 h time point) correlated with a dramatic decrease in the expression of CD160, and XCL1, markers of lymphocyte populations. At the 2 h recovery time point upregulation of matrix metalloproteinase 9, orosomucoid 1, dishevelled-associated activator of morphogenesis 2, and arginase 1 suggest an induction in muscle damage and repair during this time frame. These results demonstrate that an acute bout of RET disrupts cellular homeostasis, induces a transient redistribution of certain leukocytes, and results in transcriptional changes in PBMCs translating into systemic changes in response to RET.

In Vivo Leukocyte Changes Induced by Escherichia coli Subtilase Cytotoxin

Subtilase cytotoxin (SubAB) is the prototype of a new family of AB(5) cytotoxins produced by Shiga-toxigenic Escherichia coli. Its cytotoxicity is due to its capacity to enter cells and specifically cleave the essential endoplasmic reticulum chaperone BiP. Previous studies have shown that intraperitoneal injection of mice with purified SubAB causes a pathology that overlaps with that seen in human cases of hemolytic-uremic syndrome, as well as dramatic splenic atrophy, suggesting that leukocytes are targeted. Here we investigated SubAB-induced leukocyte changes in the peritoneal cavity, blood, and spleen. After intraperitoneal injection, SubAB bound peritoneal leukocytes (including T and B lymphocytes, neutrophils, and macrophages). SubAB elicited marked leukocytosis, which peaked at 24 h, and increased neutrophil activation in the blood and peritoneal cavity. It also induced a marked redistribution of leukocytes among the three compartments: increases in leukocyte subpopulations in the blood and peritoneal cavity coincided with a significant decline in splenic cells. SubAB treatment also elicited significant increases in the apoptosis rates of CD4(+) T cells, B lymphocytes, and macrophages. These findings indicate that apart from direct cytotoxic effects, SubAB interacts with cellular components of both the innate and the adaptive arm of the immune system, with potential consequences for disease pathogenesis.

Global Gene Expression Analysis In Human Peripheral Blood Mononuclear Cells Following Resistance Exercise

Identifying global alterations in genomic factors as a result of various exercise stimuli has the potential to afford a better understanding of adaptive responses to exercise. To date, only a limited number of gene transcripts related to the immune and inflammatory processes have been examined. PURPOSE: The present study utilized an acute bout of resistance exercise to examine the effects on the immune- and inflammatory-related genes in peripheral blood mononuclear cells (PBMCs). METHODS: Ten resistance-trained men (20-24 yrs), with at least 2 yrs resistance exercise training (RET) experience performed an acute bout of RET for ∼30 min following a 12 hr fast. Venous blood was sampled at rest, immediately following exercise, and at 2 hr post-exercise and analyzed for total and differential leukocytes and global gene expression using Affymetrix Genechips. RESULTS: Using a conservative false discovery rate (FDR) of p<0.05 and a two-fold change of or higher threshold, 167 genes were differentially detected between baseline and 2 hr post-exercise, 259 genes between 2 hr post-exercise and immediately post-exercise, and six genes between immediately post-exercise and baseline indicating the greatest gene response was seen at the 2 hour post-exercise. At the 2 hr recovery time point, matrix metalloproteinase 9 (MMP 9), orosomucoid 1 (ORM 1) and arginase 1 (ARG 1) all showed significant up regulation, while the gene CD160 was down regulated. CONCLUSION: Initial microarray results indicate that gene expression signatures are highly correlated with peripheral blood mononuclear counts and that differentially expressed genes supported the immunophenotyping results. These results demonstrate that an acute bout of RET disrupts cellular homeostasis, induces a transient redistribution of certain leukocytes, and results in a transcriptional change in blood samples consistent with phenotyping results that differs from aerobic exercise. Support made possible by the Vermont Genetics Network through Grant Number P20 RR16462 from the INBRE Program of the National Center for Research Resources (NCRR), a component of the National Institutes of Health (NIH). Its contents are solely the responsibility of the authors and do not necessarily represent the official views of NCRR or NIH.

Hematological, immunological and neurochemical effects of chronic amphetamine treatment in male rats

In the present study, we have analyzed the effect of chronic amphetamine sulfate (AMPH) treatment on haematological, immunological and neurochemical parameters in the male rat. AMPH increased the total peripheral leukocyte count, and altered its differential counts, decreasing lymphocytes and increasing neutrophils. Flow cytometry study showed that the decline in circulating lymphocytes was caused by the loss of a particular lymphocyte subset, B-cell, which reduced both in percentage and in absolute number by 50%. T-cell population increased by 15% but not in absolute number, however there was no difference in either CD4+ or CD8+ T lymphocyte subsets between experimental groups. Neurochemically, AMPH reduced norepinephrine (NE) and serotonin (5-HT) contents in the hypothalamus and increased dopamine (DA) content in the striatum. Chronic AMPH increased in a dose-dependent manner serum corticosterone levels, had no effect on circulating catecholamines, reduced adrenal weights, and did not affect spleen weights although reduced their cellularities. These results show that chronic AMPH have important effects on immune function, particularly on humoral immune response because it reduced the circulating B cell population by half. In addition, AMPH plays an important role in the redistribution and trafficking of leukocytes, and both effects seem to be mediated by sympathetic innervation of the lymphoid organs.

Effects of social stress on blood leukocyte distribution: the role of α- and β-adrenergic mechanisms

Social stress in mammals has repeatedly been shown to cause substantial alterations in the distribution pattern of immune cells in the peripheral blood. The studies described here investigated the role of adrenergic mechanisms in mediating stressor-induced changes in blood leukocyte numbers using a social confrontation procedure in the rat. Experimental manipulations were carried out to eliminate the stress-associated release of adrenal hormones or to block the binding of endogenous catecholamines to α- and β-adrenergic receptors. Adrenalectomy completely abolished the stressor-induced decreases in circulating numbers of T helper cells (CD4 +), cytotoxic T cells (CD8 +) and B cells but was ineffective in preventing neutrophil granulocytosis, monocytosis and an increase in natural killer (NK) cells. Treatment with the α-adrenergic antagonist phentolamine (PHE) was highly effective in preventing granulocytosis and partially blocked lymphopenia, but failed to abolish monocytosis and an increase in NK cells. Treatment with the β-adrenergic antagonists propranolol (PROP) or nadolol (NAD) entirely blocked the increases in monocytes and NK cells. In addition, β-adrenergic blockade also significantly reduced neutrophilia, with PROP being more effective than NAD. The results presented here provide evidence that catecholamines play an important role in the redistribution of blood leukocytes during social stress. In particular, the mobilization of cells of the innate immune response seems to be regulated by adrenergic mechanisms.

Low Glycemic Index Pre-exercise Meal Attenuates Blood Leukocyte Redistribution During Subsequent Exercise

1761 Carbohydrate ingestion during prolonged strenuous exercise attenuates the leukocytosis and subsequent neutrophilia and lymphopenia by maintaining plasma glucose concentration and minimizing stress hormone responses. Ingestion of a low glycemic index (LGI) meal before exercise has been demonstrated to better maintain plasma glucose levels during subsequent submaximal exercise compared with a high glycemic index (HGI) meal. PURPOSE: To determine whether the redistribution of leukocytes during endurance exercise is affected by the glycemic index of a preexercise high carbohydrate meal. METHODS: Eight male subjects (age 27.5 ± 1.5 yrs, body mass 72.1 ± 1.6 kg, height 1.77 ± 0.02 m, VO2max 60.7 ± 1.3 mL·kg−1·min−1; mean ± S.E.M.) performed two 90-min runs on a treadmill at 70% VO2max three hours after ingesting a HGI or LGI meal. Each isocaloric test meal contained 2 g·kg−1 body mass of carbohydrate and the glycemic index values were 77 and 37, respectively. Trials were separated by at least 7 days in counterbalanced order. Results were analysed using a two-factor (trial × time) repeated measures ANOVA with post hoc comparison as appropriate. RESULTS: Blood leukocyte and neutrophil counts were significantly lower in LGI than HGI at 90-min of exercise (8.70 ± 0.80 vs. 10.12 ± 0.94 and 4.75 ± 0.63 vs. 6.47 ± 0.77 × 109·L−1; both P < 0.05). The ratio of neutrophils/lymphocytes was significantly lower in LGI than HGI at 90-min (1.57 ± 0.17 vs. 2.28 ± 0.27, P < 0.05). Plasma glucose concentrations were significantly higher in LGI than HGI at 15-min and 45-min of exercise. However, there were no significant differences in plasma cortisol, human growth hormone and interleukin-6 concentrations between trials. CONCLUSION: Ingestion of a LGI meal 3 h before submaximal exercise attenuates the increase in circulating leukocyte and neutrophil counts, and better maintains plasma glucose concentration during subsequent exercise when compared with ingestion of a HGI meal. However, it seems to have limited effects on circulating stress hormone and cytokine responses to exercise.

Short day lengths augment stress-induced leukocyte trafficking and stress-induced enhancement of skin immune function

Environmental conditions influence the onset and severity of infection and disease. Stressful conditions during winter may weaken immune function and further compromise survival by means of hypothermia, starvation, or shock. To test the hypothesis that animals may use photoperiod to anticipate the onset of seasonal stressors and adjust immune function, we evaluated glucocorticoids and the distribution of blood leukocytes in Siberian hamsters (Phodopus sungorus) exposed to long day lengths (i.e., summer) or short day (SD) lengths (i.e., winter) at baseline and during acute stress. We also investigated the influence of photoperiod and acute stress on a delayed-type hypersensitivity response in the skin. SDs increased glucocorticoid concentrations and the absolute number of circulating blood leukocytes, lymphocytes, T cells, and natural killer cells at baseline in hamsters. During stressful challenges, it appears beneficial for immune cells to exit the blood and move to primary immune defense areas such as the skin, in preparation for potential injury or infection. Acute (2 h) restraint stress induced trafficking of lymphocytes and monocytes out of the blood. This trafficking occurred more rapidly in SDs compared to long days. Baseline delayed-type hypersensitivity responses were enhanced during SDs; this effect was augmented by acute stress and likely reflected more rapid redistribution of leukocytes out of the blood and into the skin. These results suggest that photoperiod may provide a useful cue by which stressors in the environment may be anticipated to adjust the repertoire of available immune cells and increase survival likelihood.

Phenotypic Analysis of Splenocyte Subsets Following Acute Morphine Treatment in the Rat

Prior studies by our laboratory demonstrated that a single injection of morphine produces dose-dependent, naltrexone-reversible, suppressive effects in assays of mitogen-stimulated lymphocyte proliferation and natural killer (NK) cell cytotoxicity in the spleen. The present study used flow cytometry to assess directly whether acute morphine treatment produces these immune alterations by altering the leukocyte composition of the spleen. In agreement with our previous findings, morphine suppressed the concanavalin A-stimulated proliferation of T cells, lipopolysaccharide-stimulated proliferation of B cells, and NK cell cytotoxicity in the spleen. However, the same morphine treatment protocol did not alter the total number of splenic leukocytes, the percentage of live splenic leukocytes (as assessed by forward-scatter versus side-scatter histograms), or the relative number of CD4+CD3+ T cells, CD8+CD3+ T cells, CD45RA/B+ B cells, NKR-P1AhiCD3− NK cells, NKR-P1AloCD3+ T cells, CD11b/c+HIS48− monocytes/macrophages, or CD11b/c+HIS48+ granulocytes in the spleen. These findings indicate that the effects of a single sc dose of morphine on functional measures of immune status in the spleen do not result from a redistribution of splenic leukocytes; instead, morphine's effects likely result from direct alterations in leukocyte activities.

Stress-induced enhancement of cell-mediated immunity.

We have demonstrated that acute stress induces a large-magnitude, rapid, and reversible redistribution of leukocytes from the blood to other compartments within the body. These changes in leukocyte distribution are mediated by adrenal stress hormones. Because the skin is one of the target organs of a stress-induced redistribution of leukocyes, we hypothesized that such a leukocyte redistribution could be one of the factors by which acute stress may enhance cutaneous immune function. This hypothesis was tested by examining the effects of acute stress on cutaneous delayed-type hypersensitivity (DTH). DTH reactions are antigen-specific, cell-mediated immune responses that, depending on the antigen involved, mediate beneficial (resistance to viruses, bacteria, and fungi) or harmful (allergic dermatitis, autoimmunity) aspects of immune function. DTH was induced by challenging the pinnae of previously sensitized rats with 2,4-dinitro-1-fluorobenzene (DNFB). Experiments showed that acute stress administered immediately before the introduction of an antigenic challenge significantly enhances a cutaneous DTH response. In contrast, chronic stress suppresses cutaneous DTH. These results demonstrate a bidirectional relationship between stress and immune function, such that acute stress enhances, while chronic stress suppresses, an important class of immune responses in vivo. They also suggest that stress-induced alterations in lymphocyte redeployment within the body may play an important role in mediating these bidirectional effects of stress on cell-mediated immunity.

Effects of stress on immune cell distribution. Dynamics and hormonal mechanisms.

Immune cell trafficking is crucial to the performance of the surveillance as well as effector functions of the immune system. Because immune cells travel between tissues through the bloodstream, the numbers and proportions of leukocytes in the circulation provide an important representation of the state of leukocyte distribution in the body. The studies described here examine significant and selective changes in numbers and percentages of peripheral blood leukocyte subpopulations in the rat. These changes were rapidly induced under conditions of mild acute stress. Stress-induced increases in plasma corticosterone were accompanied by a significant decrease in numbers and percentages of lymphocytes, and by an increase in numbers and percentages of neutrophils. flow cytometric analysis revealed that B cell, NK cell, and monocyte numbers showed a greater stress-induced decrease than did T cells. All stress-induced changes were observed during the light (inactive) as well as the dark (active) period of the animal's diurnal cycle. Importantly, the stress-induced changes in leukocyte numbers and percentages were rapidly reversed upon the cessation of stress. Furthermore, the effects of stress were largely dependent on adrenal hormones, because the magnitude of the stress-induced changes was significantly reduced in adrenalectomized animals. Moreover, administration of corticosterone to adrenalectomized animals resulted in a close replication of stress-induced changes observed in adrenal-intact animals. These results suggest that endocrine factors released during stress modulate leukocyte trafficking and result in the redistribution of leukocytes between the blood and other immune compartments. Such a redistribution may significantly affect the ability of the immune system to respond to potential or ongoing immune challenge.

Replacement of lateral line sensory organs during tail regeneration in salamanders: identification of progenitor cells and analysis of leukocyte activity

It has been proposed that supporting cells may be the progenitors of regenerated hair cells that contribute to recovery of hearing in birds, but regeneration is difficult to visualize in the ear, because it occurs deep in the skull. Hair cells and supporting cells that are comparable to those in the ear are present in lateral line neuromasts, and in axolotl salamanders these cells are accessible to microscopic observation in vivo. After amputation of a segment of the tail that contains neuromasts, cells from the posteriormost neuromast on the tail stump divide rapidly and form a migratory regenerative placode. The cells of the regenerative placode represent a lineage that eventually produces both hair cells and supporting cells in replacement neuromasts. We sought to identify the progenitors of the regenerative placode by using differential interference contrast microscopy combined with time-lapse video recording in living axolotl salamanders. In response to amputation, the mantle-type supporting cells at the posteroventral edge of the neuromast that is nearest to the wound increased their frequency of cell division, and gave rise to the first cells of the placode. The increase in mitotic activity of mantle-type supporting cells was accompanied by an unexplained decrease in the frequency of divisions in the same neuromast's population of internal supporting cells. The time-lapse records suggested that the changes in the mitotic activity of supporting cells might have been linked to the presence of phagocytic leukocytes in the vicinity of the neuromast that was nearest to the wound. Leukocytes were evenly distributed around control neuromasts, but during regeneration leukocyte activity increased significantly in the vicinity of the posterior half of the posteriormost neuromast. The redistribution of leukocytes occurred early in the regenerative response, but a causal role for the leukocytes has not been conclusively established. It is possible that the leukocytes could contribute to the formation of the regenerative placode at that location by breaking down the glycocalyx that ensheaths the outermost cells of the neuromast, or through the secretion of mitogenic growth factors.

Leukocyte Redistribution and Eicosanoid Changes During the Autoperfused Working Heart-Lung Preparation

We studied the role of leukocyte redistribution and eicosanoid changes in the early stages of instituting 16 rabbit autoperfused working heart-lung preparations (AWHLP). Physiological changes occurring during the transition from the intact animal to the AWHLP may determine the survival and viability of the organ blocks for transplantation. White blood cell (WBC) count decreased from 5,160/microL to 1430/microL (P less than .01) at 60 min of autoperfusion. Differential WBC counts performed in ten of these AWHLP revealed a 63% decrease in lymphocyte count and an 88% decrease in the granulocyte count at 60 min. Thus, the predominant leukocyte remaining in the circulation was the lymphocyte. Blood samples were collected from the intact animal and from the AWHLP for assay of the stable metabolites of thromboxane A2 (TxA2) and prostacyclin (PGI2). Transition from the in situ heart-lung block to the in vitro AWHLP stage caused significant changes in these metabolites. The PGI2 metabolite 6-ketoprostaglandin F1a (6KPGF1a) increased from 2680 +/- 487 to 4339 +/- 478 (pg/mL), P less than .05, while the TxA2 metabolite, thromboxane B2 (TxB2) decreased from 618 +/- 105 to 289 +/- 63 (pg/mL). However, assays of 11-dehydro-TxB2 (11-DHT), a longer lived metabolite of TxA2 (n = 7) increased (668.4 +/- 84.6 to 946.4 +/- 43.7, P less than .05). The transition from the in situ heart-lung block of the intact animal to the AWHLP involves significant physiological changes. Redistribution of leukocytes occurs with a predominant decrease in the granulocyte count, while levels of bioactive lipid mediators show a distinct large rise in the PGI2 metabolites and a lesser increase in TxA2 metabolites.(ABSTRACT TRUNCATED AT 250 WORDS)