Characterization of in vitro Chlamydia muridarum persistence and utilization in an in vivo mouse model of Chlamydia vaccine

Problem: Chlamydia trachomatis genital tract infections are easily treated with antibiotics, however the majority of infections are asymptomatic and therefore untreated, highlighting the need for a vaccine. Because most infections are asymptomatic, vaccination could potentially be administered to individuals who may have an acute infection at that time. In such individuals the effect of vaccination on the existing infection is unknown; however one potential outcome could be the development of a persistent infection. In vitro chlamydial persistence has been well characterized in various strains, however there have been no reported studies in C. muridarum. Method of Study: We performed ultrastructural characterization, and transcriptome analysis of selected genes. We then used the transcriptional profiles of the selected genes to examine whether intranasal immunization of mice during an active genital infection would induce persistence in the upper reproductive tract of female mice. Results and Conclusions: We found that persistence developed in the oviducts of mice as a result of immunization. This is a significant finding, not only because it is the first time that C. muridarum persistence has been characterized in vitro, but also due to the fact that there is minimal characterization of in vivo persistence of any chlamydial species. This highlights the importance of the timing of vaccination in individuals.

Microbial colonisation of follicular fluid : alterations in cytokine expression and adverse assisted reproductive technology outcomes

Previous studies have measured cytokine expression within follicular fluid collected at the time of trans-vaginal oocyte retrieval and compared the profiles with the aetiology of infertility and/or successful or unsuccessful assisted reproductive technology (ART) outcomes. Seventy-one paired follicular fluid and vaginal swab specimens collected from ART patients were cultured to detect microorganisms and then were tested for the presence of cytokines by multiplex fluorescence bead assays. Specimen selection was based on two criteria: whether the follicular fluid specimen was colonised (with microorganisms prior to oocyte retrieval) or contaminated by lower genital tract microflora at the time of oocyte retrieval and; the aetiology of infertility...

Reproductive behavioural differences between wild-caught and pond-reared Penaeus monodon prawn broodstock

Ongoing problems exist with the commercial scale domestication of Penaeus monodon. One of the major issues, in terms of reproductive performance, is the low egg hatch rate of eggs from these captive bred prawns. The current study investigated the related issue of mating success. Time lapse video observations were conducted to compare the mating behaviour of pond-reared (domesticated) and wild-caught prawn P. monodon broodstock. Mating success of the pond-reared prawns was found to be low relative to wild-caught. It was determined that both male and female prawns contributed to this low mating rate suggesting both genders were impacted negatively by the domestication process. The causative factors for the low mating success are yet to be determined, however external physical abnormalities and lack of sexual maturity did not appear to play a role. The most notable behavioural difference between wild-caught and domesticated prawns was a reduced level of pursuit behaviour by domesticated males. This and other behavioural differences are discussed in relation to an increasing body of evidence that male prawns respond to sex pheromones produced by receptive females and that males detect these chemical signals in part, via their second antennal flagella. Accordingly we hypothesise that pond-reared (domesticated) females may have a reduced ability to produce or release sex pheromones and males, a reduced ability to detect them when compared to their wild-caught counterparts.

Reduction in resting plasma granulysin as a marker of increased training load

Granulysin is a cytolytic granule protein released by natural killer cells and activated cytotoxic T lymphocytes. The influence of exercise training on circulating granulysin concentration is unknown, as is the relationship between granulysin concentration, natural killer cell number and natural killer cell cytotoxicity. We examined changes in plasma granulysin concentration, natural killer cell number and cytotoxicity following acute exercise and different training loads. Fifteen highly trained male cyclists completed a baseline 40-km cycle time trial (TT401) followed by five weeks of normal training and a repeat time trial (TT402). The cyclists then completed four days of high intensity training followed by another time trial (TT403) on day five. Following one final week of normal training cyclists completed another time trial (TT404). Fasting venous blood was collected before and after each time trial to determine granulysin concentration, natural killer cell number and natural killer cell cytotoxicity. Granulysin concentration increased significantly after each time trial (P<0.001). Pre-exercise granulysin concentration for TT403 was significantly lower than pre-exercise concentration for TT401 (-20.3 +/- 7.5%, P<0.026), TT402 (-16.7 +/- 4.3%, P<0.003) and 7T404 (-21 +/- 4.2%, P<0.001). Circulating natural killer cell numbers also increased significantly post-exercise for each time trial (P<0.001), however there was no significant difference across TT40 (P>0.05). Exercise did not significantly alter natural killer cell cytotoxicity on a per cell basis, and there were no significant differences between the four time trials. In conclusion, plasma granulysin concentration increases following moderate duration, strenuous exercise and is decreased in response to a short-term period of intensified training.

Exercise-recruited NK cells display exercise-associated eHSP-70

It is hypothesized that increased plasma or serum concentrations of extracellular heat shock proteins (eHSP) serve as a danger signal to the innate immune system. Cellular binding of eHSP leads to activation of NK cells and monocytes, as measured by their increased cytokine production, mitotic division and killing capacity. We examined whether eHSP binds to NK lymphocytes in vivo in athletes performing endurance exercise in the heat. Eighteen trained male runners ran at 70% VO2max at 35 degrees C and 40% relative humidity. Venous blood collected before, after and 1.5 h after exercise was analysed for leukocyte distribution, phenotype and eHSP70. NK cell-enriched samples were examined for co-localization of CD94 and eHSP70 expression. Plasma eHSP-70 concentration was measured by ELISA. Subjects ran for approximately 50 min, which elicited a reversible leukocytosis. NK cell count increased 83% (p < 0.01) immediately after exercise, then decreased to 66% of the resting level 1.5 h after exercise (p < 0.05). Plasma eHSP concentration increased 167% after exercise and remained elevated (by up to 71%) 1.5 h after exercise (p < 0.01). eHSP was expressed on both NK cells and monocytes at all times; the count of NK cells positive for eHSP doubled from 0.04 +/- 0.02 10(9)/L (mean +/- SD) to 0.08 +/- 0.06 10(9)/L after exercise. In summary, exercise in the heat increased free plasma eHSP concentration, and the eHSP co-localized with CD94 on NK cells. These data confirm the link between exercise and activation of the innate immune system.

The influence of antioxidant supplementation on markers of inflammation and the relationship to oxidative stress after exercise

Interest in the relationship between inflammation and oxidative stress has increased dramatically in recent years, not only within the clinical setting but also in the fields of exercise biochemistry and immunology. Inflammation and oxidative stress share a common role in the etiology of a variety of chronic diseases. During exercise, inflammation and oxidative stress are linked via muscle metabolism and muscle damage. Because oxidative stress and inflammation have traditionally been associated with fatigue and impaired recovery from exercise, research has focused on nutritional strategies aimed at reducing these effects. In this review, we have evaluated the findings of studies involving antioxidant supplementation on alterations in markers of inflammation (e.g., cytokines, C-reactive protein and cortisol). This review focuses predominantly on the role of reactive oxygen and nitrogen species generated from muscle metabolism and muscle damage during exercise and on the modulatory effects of antioxidant supplements. Furthermore, we have analyzed the influence of factors such as the dose, timing, supplementation period and bioavailability of antioxidant nutrients.

Characterization of inflammatory responses to eccentric exercise in humans

Eccentric exercise commonly results in muscle damage. The primary sequence of events leading to exercise-induced muscle damage is believed to involve initial mechanical disruption of sarcomeres, followed by impaired excitation-contraction coupling and calcium signaling, and finally, activation of calcium-sensitive degradation pathways. Muscle damage is characterized by ultrastructural changes to muscle architecture, increased muscle proteins and enzymes in the bloodstream, loss of muscular strength and range of motion and muscle soreness. The inflammatory response to exercise-induced muscle damage is characterized by leukocyte infiltration and production of pro-inflammatory cytokines within damaged muscle tissue, systemic release of leukocytes and cytokines, in addition to alterations in leukocyte receptor expression and functional activity. Current evidence suggests that inflammatory responses to muscle damage are dependent on the type of eccentric exercise, previous eccentric loading (repeated bouts), age and gender. Circulating neutrophil counts and systemic cytokine responses are greater after eccentric exercise using a large muscle mass (e.g. downhill running, eccentric cycling) than after other types of eccentric exercise involving a smaller muscle mass. After an initial bout of eccentric exercise, circulating leukocyte counts and cell surface receptor expression are attenuated. Leukocyte and cytokine responses to eccentric exercise are impaired in elderly individuals, while cellular infiltration into skeletal muscle is greater in human females than males after eccentric exercise. Whether alterations in intracellular calcium homeostasis influence inflammatory responses to muscle damage is uncertain. Furthermore, the effects of antioxidant supplements are variable, and the limited data available indicates that anti-inflammatory drugs largely have no influence on inflammatory responses to eccentric exercise. In this review, we compare local versus systemic inflammatory responses, and discuss some of the possible mechanisms regulating the inflammatory responses to exercise-induced muscle damage in humans.

Neutrophil activation, antioxidant supplements and exercise-induced oxidative stress

Neutrophils produce free radicals known as reactive oxygen species (ROS), which assist in the clearance of damaged host tissue. Tissue damage may occur during exercise due to muscle damage, thermal stress and ischaemia/reperfusion. When produced in excess, neutrophil-derived ROS may overwhelm the body's endogenous antioxidant defence mechanisms, and this can lead to oxidative stress. There is increasing evidence for links between oxidative stress and a variety of pathological disorders such as cardiovascular diseases, cancer, chronic inflammatory diseases and post-ischaemic organ injury. A small number of studies have investigated whether there is a link between neutrophil activation and oxidative stress during exercise. In this review, we have summarised the findings of these studies. Exercise promotes the release of neutrophils into the circulation, and some evidence suggests that neutrophils mobilised after exercise have an enhanced capacity to generate some forms of ROS when stimulated in vitro. Neutrophil activation during exercise may challenge endogenous antioxidant defence mechanisms, but does not appear to increase lipid markers of oxidative stress to any significant degree, at least in the circulation. Antioxidant supplements such as N-acetylcysteine are effective at attenuating increases in the capacity of neutrophils to generate ROS when stimulated in vitro, whereas vitamin E reduces tissue infiltration of neutrophils during exercise. Free radicals generated during intense exercise may lead to DNA damage in leukocytes, but it is unknown if this damage is the result of neutrophil activation. Exercise enhances the expression of inducible haem (heme)-oxygenase (HO-1) in neutrophils after exercise, however, it is uncertain whether oxidative stress is the stimulus for this response.

Changes in inflammatory mediators following eccentric exercise of the elbow flexors

The aims of this study were to examine the plasma concentrations of inflammatory mediators including cytokines induced by a single bout of eccentric exercise and again 4 weeks later by a second bout of eccentric exercise of the same muscle group. Ten untrained male subjects performed two bouts of the eccentric exercise involving the elbow flexors (6 sets of 5 repetitions) separated by four weeks. Changes in muscle soreness, swelling, and function following exercise were compared between the bouts. Blood was sampled before, immediately after, 1 h, 3 h, 6 h, 24 h (1 d), 48 h (2 d), 72 h (3 d), 96 h (4 d) following exercise bout to measure plasma creatine kinase (CK) activity, plasma concentrations of myoglobin (Mb), interleukin (IL)-1beta, IL-1 receptor antagonist (IL-1ra), IL-4, IL-6, IL-8, IL-10, IL-12p40, tumor necrosis factor (TNF)-alpha, granulocyte colony-stimulating factor (G-CSF), myeloperoxidase (MPO), prostaglandin E2 (PGE2), heat shock protein (HSP) 60 and 70. After the first bout, muscle soreness increased significantly, and there was also significant increase in upper arm circumference; muscle function decreased and plasma CK activity and Mb concentration increased significantly. These changes were significantly smaller after the second bout compared to the first bout, indicating muscle adaptation to the repeated bouts of the eccentric exercise. Despite the evidence of greater muscle damage after the first bout, the changes in cytokines and other inflammatory mediators were quite minor, and considerably smaller than that following endurance exercise. These results suggest that eccentric exercise-induced muscle damage is not associated with the significant release of cytokines into the systemic circulation. After the first bout, plasma G-CSF concentration showed a small but significant increase, whereas TNF-alpha and IL-8 showed significant decreases compared to the pre-exercise values. After the second bout, there was a significant increase in IL-10, and a significant decrease in IL-8. In conclusion, although there was evidence of severe muscle damage after the eccentric exercise, this muscle damage was not accompanied by any large changes in plasma cytokine concentrations. The minor changes in systemic cytokine concentration found in this study might reflect more rapid clearance from the circulation, or a lack of any significant metabolic or oxidative demands during this particular mode of exercise. In relation to the adaptation to the muscle damage, the anti-inflammatory cytokine IL-10 might work as one of the underlying mechanisms of action.

Exercise-induced alterations in neutrophil degranulation and respiratory burst activity : possible mechanisms of action

Neutrophils constitute 50-60% of all circulating leukocytes; they present the first line of microbicidal defense and are involved in inflammatory responses. To examine immunocompetence in athletes, numerous studies have investigated the effects of exercise on the number of circulating neutrophils and their response to stimulation by chemotactic stimuli and activating factors. Exercise causes a biphasic increase in the number of neutrophils in the blood, arising from increases in catecholamine and cortisol concentrations. Moderate intensity exercise may enhance neutrophil respiratory burst activity, possibly through increases in the concentrations of growth hormone and the inflammatory cytokine IL-6. In contrast, intense or long duration exercise may suppress neutrophil degranulation and the production of reactive oxidants via elevated circulating concentrations of epinephrine (adrenaline) and cortisol. There is evidence of neutrophil degranulation and activation of the respiratory burst following exercise-induced muscle damage. In principle, improved responsiveness of neutrophils to stimulation following exercise of moderate intensity could mean that individuals participating in moderate exercise may have improved resistance to infection. Conversely, competitive athletes undertaking regular intense exercise may be at greater risk of contracting illness. However, there are limited data to support this concept. To elucidate the cellular mechanisms involved in the neutrophil responses to exercise, researchers have examined changes in the expression of cell membrane receptors, the production and release of reactive oxidants and more recently, calcium signaling. The investigation of possible modifications of other signal transduction events following exercise has not been possible because of current methodological limitations. At present, variation in exercise-induced alterations in neutrophil function appears to be due to differences in exercise protocols, training status, sampling points and laboratory assay techniques.

Transcriptome analysis of neutrophils after endurance exercise reveals novel signaling mechanisms in the immune response to physiological stress

Neutrophils serve as an intriguing model for the study of innate immune cellular activity induced by physiological stress. We measured changes in the transcriptome of circulating neutrophils following an experimental exercise trial (EXTRI) consisting of 1 h of intense cycling immediately followed by 1 h of intense running. Blood samples were taken at baseline, 3 h, 48 h, and 96 h post-EXTRI from eight healthy, endurance-trained, male subjects. RNA was extracted from isolated neutrophils. Differential gene expression was evaluated using Illumina microarrays and validated with quantitative PCR. Gene set enrichment analysis identified enriched molecular signatures chosen from the Molecular Signatures Database. Blood concentrations of muscle damage indexes, neutrophils, interleukin (IL)-6 and IL-10 were increased (P < 0.05) 3 h post-EXTRI. Upregulated groups of functionally related genes 3 h post-EXTRI included gene sets associated with the recognition of tissue damage, the IL-1 receptor, and Toll-like receptor (TLR) pathways (familywise error rate, P value < 0.05). The core enrichment for these pathways included TLRs, low-affinity immunoglobulin receptors, S100 calcium binding protein A12, and negative regulators of innate immunity, e.g., IL-1 receptor antagonist, and IL-1 receptor associated kinase-3. Plasma myoglobin changes correlated with neutrophil TLR4 gene expression (r = 0.74; P < 0.05). Neutrophils had returned to their nonactivated state 48 h post-EXTRI, indicating that their initial proinflammatory response was transient and rapidly counterregulated. This study provides novel insight into the signaling mechanisms underlying the neutrophil responses to endurance exercise, suggesting that their transcriptional activity was particularly induced by damage-associated molecule patterns, hypothetically originating from the leakage of muscle components into the circulation.

Host selection in phytophagous insects: a new explanation for learning in adults

Insect learning can change the preferences an egg laying female displays towards different host plant species. Current hypotheses propose that learning may be advantageous in adult host selection behaviour through improved recognition, accuracy or selectivity in foraging. In this paper, we present a hypothesis for when learning can be advantageous without such improvements in adult host foraging. Specifically, that learning can be an advantageous strategy for egg laying females when larvae must feed on more than one plant in order to complete development, if the fitness of larvae is reduced when they switch to a different host species. Here, larvae benefit from developing on the most abundant host species, which is the most likely choice of host for an adult insect which increases its preference for a host species through learning. The hypothesis is formalised with a mathematical model and we provide evidence from studies on the behavioural ecology of a number of insect species which demonstrate that the assumptions of this hypothesis may frequently be fulfilled in nature. We discuss how multiple mechanisms may convey advantages in insect learning and that benefits to larval development, which have so far been overlooked, should be considered in explanations for the widespread occurrence of learning.

A general model for host plant selection in phytophagous insects

We develop a general theoretical framework for exploring the host plant selection behaviour of herbivorous insects. This model can be used to address a number of questions, including the evolution of specialists, generalists, preference hierarchies, and learning. We use our model to: (i) demonstrate the consequences of the extent to which the reproductive success of a foraging female is limited by the rate at which they find host plants (host limitation) or the number of eggs they carry (egg limitation); (ii) emphasize the different consequences of variation in behaviour before and after landing on (locating) a host (termed pre- and post-alighting, respectively); (iii) show that, in contrast to previous predictions, learning can be favoured in post-alighting behaviour--in particular, individuals can be selected to concentrate oviposition on an abundant low-quality host, whilst ignoring a rare higher-quality host; (iv) emphasize the importance of interactions between mechanisms in favouring specialization or learning.

Host location behaviour in the desert caterpillar, Heliothis punctifera

The host location behaviour of foraging caterpillars has received little attention, despite the wealth of theoretical and empirical studies that have been directed at this behavioural trait in adult Lepidoptera. Here, we study caterpillars of the moth Heliothis punctifera Walker (Lepidoptera: Noctuidae), which inhabits the arid inland desert areas of Australia. Caterpillars of this species consume many flowerheads before completing development and can be observed moving across the sand in search of new hosts. Consequently, if host location behaviour favours attraction to certain plant species, it might be expected to influence the distribution and abundance of caterpillars in the field. We present field data showing that H. punctifera caterpillars are unevenly distributed throughout mixed patches of two of its host species, with a higher abundance on Senecio gregorii F. Muell., the annual yellow top, compared to Myriocephalus stuartii (F. Muell. & Sond.) Benth., the poached egg daisy (both Asteraceae). Using laboratory studies, we test whether this distribution may, in part, be due to host location behaviour of caterpillars. Our results show that caterpillars exhibit a preference for locating S. gregorii in their pre- and post-contact foraging behaviour. In addition, our results provide evidence that feeding history plays a role in host location behaviour in this insect. We propose that key features of the desert environment and the ecology of H. punctifera would favour adaptations to host location behaviour by immatures.