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End-stage renal disease patients exhibit markedly elevated cardiovascular risk when compared to the general population, as well as chronic systemic inflammation as a result of aberrant immune system activation. Circulating microparticles are also elevated, driving both inflammation and thrombosis and further increasing cardiovascular risk. Regular, moderate intensity aerobic exercise may be a therapeutic strategy for the impaired immune function and pro-inflammatory environment seen in these patients, however previous studies investigating this effect have been methodologically limited. The studies included in this thesis aimed to characterise the impact of acute and regular aerobic exercise on immune function, markers of inflammation and microparticles in end-stage renal disease patients. It is hypothesised that aerobic exercise will have an anti-inflammatory impact on the immune system and cytokine environment and reduce circulating microparticle thrombotic potential.

Prolonged exercise has been associated with depressed immune function, and hence an increased risk of infection. However, several nutritional supplements may reduce or overcome this problem. Thus, the aims of this thesis were to investigate the effects of some nutritional supplements on athletes immune function. In study 1 (Chapter 3), effects of several vaccine stimulant dose on whole blood culture cytokine production was carried out to determine effective vaccine stimulant dose; which was found to be between a dilution of 4000 (dose 4) and 1000 (dose 6) of the original vaccine. This finding was used for the other studies (Chapter 4 and 5). In addition, the relationship between data obtained from Evidence Investigator analyser and enzyme linked-immuno-sorbent assay (ELISA) for IL-10 was analysed and the results show a positive strong correlation between them. In study 2 (Chapter 4), in vitro effects of various immunomodulatory nutritional compounds on antigen-stimulated whole blood culture cytokine production was investigated and it was found that caffeine and quercetin showed tendency towards decrease cytokine production as the doses were increased. On the other hand, an upward trend was evident with kaloba, where high dose of kaloba seemed to increase the cytokine production. Since kaloba appeared to act as an immunostimulant in vitro, its effects on the immune response to prolonged exercise were examined in study 3 (Chapter 5). However, 7 days kaloba supplementation (20 mg of the root extract) did not alter athletes immune response although prolonged moderate intensity exercise significantly decreased S-IgA secretion rate and concentration post-exercise with the values returning to baseline by 1 h post-exercise. A 14-strain probiotic supplement effects on salivary antimicrobial proteins at rest and in response to an acute bout of prolonged exercise was investigated in study 4 (Chapter 6). Unfortunately, 30 days supplementation of the 14-strain probiotic appeared not enough to induce any significant effects on salivary antimicrobial proteins. Lastly, in study 5 (Chapter 7), the effects of a Lactobacillus probiotic on healthy people, who tend to have a higher than normal incidence of infection due to exercise stress-induced immune impairment was studied. In summary, this 16-week intervention study on 267 athletes found that regular ingestion of the probiotic reduced the extent to which training was negatively affected in endurance athletes when infection was present, and increased both S-IgA concentration and secretion rate over time. But it did not appear to reduce URTI incidence or the duration and severity of URTI episodes. Two major confounding factors, namely the unexpectedly low incidence of URTI during the winter period and the lower baseline S-IgA in the probiotic group may have prevented potential beneficial effects of probiotic supplementation from being identified.

The human major histocompatibility complex (MHC), on the short arm of chromosome 6, contains a cluster of genes which show diverse immune functions, like the recognition of foreign antigen and the generation of an inflammatory response. However, the RINGS gene shows no obvious immune function despite its location in the centre of the MHC. RING3 was found to span 12 kb and contains 13 exons, with two alternative start codons. The RINGS gene was also isolated in the mouse and mapped to a syntenic position in the murine MHC. Comparison of the RINGS gene structure in human, mouse and chicken revealed a perfect conservation in the intron/exon boundaries of the coding exons and high conservation at the amino acid level. The ORFX gene, a human homologue of RING3, was isolated and mapped to 9q34. This gene shows a highly conserved gene structure but is almost three times larger than RING3, mainly due to the presence of repeat elements. Evolutionary analysis indicates that RING3 may be over 1 billion years old with homologues isolated in yeast, worm, fly, fish, chicken, mouse and human. The gene structure has been conserved for at least 350 million years and linkage to the MHC has been established in five vertebrate species. Evidence also suggests that ORFX and RING3 arose by an ancient duplication 350-400 million years ago. Both RING3 and ORFX are ubiquitously expressed in human adult and foetal tissues, with a highly abundant expression in the testis. Human and mouse have three variant RING3 transcripts, one of which is purely testis-specific. Growing evidence suggests that RING3 may be a nuclear kinase with a raised activity in certain types of leukaemia. Mutation analysis of the RING3 coding regions in ALL, CML and normal individuals, revealed a low level of polymorphism across the gene. However, for one deletion mutation, a significant deviation from Hardy-Weinberg proportions was observed in the leukaemic samples.

High altitude is a physiologically stressful environment due to oxygen limitation and low atmospheric pressure. Despite these conditions, over 160 million people live, work, or travel to high altitude annually. Several systemic physiological changes in response to hypoxia promote acclimatization to high altitude. However, even in acclimatized individuals, there is still a significant risk of developing high-altitude illnesses (HAIs), such as acute mountain sickness, high-altitude pulmonary edema, or high-altitude cerebral edema. While it is clear that HAIs result from high altitude/hypoxia, gaps in our knowledge remain regarding the underlying mechanisms that drive the development of these pathologies. The molecular pathways that control hypoxia responses are evolutionary conserved and have significant crosstalk to essential mechanisms that drive inflammation. While these responses may be key for acute adaptation to hypoxia, they may become maladaptive if not properly mediated. For example, native highlanders show evidence of natural selection for traits that promote adaptation to chronic hypoxia, but different native high-altitude populations display distinct adaptations. However, not all these adaptations are beneficial. Most notably, Andean highlanders have a high prevalence of Chronic Mountain Sickness (CMS), an incapacitating syndrome induced by lifelong exposure to hypoxia. The underlying mechanisms behind CMS are also unknown, however it has been suspected that inflammation may play a role in CMS pathogenesis. The goal of my dissertation research was to determine how high-altitude hypoxia induces changes in inflammatory profiles and immune cell populations. Furthermore, I aimed to investigate if immune cells at high altitude are sensitized to inflammatory stimuli, and if these responses are dependent on hypoxia inducible factor (HIF) activity. To accomplish these goals, I employed several techniques such as multi-parameter flow cytometry, multiplex immunoassays, in vitro stimulation experiments, and an unbiased transcriptomic approach. These studies demonstrate that acute high-altitude exposure increases inflammatory expression, as well as promotes a pro-inflammatory immunophenotype. Furthermore, HIF plays a role in immune cell surface markers, most notably CD14. As sojourners acclimatize, the inflammatory profile favors an anti-inflammatory phenotype. Overall, these studies provide important insights into the role of inflammation in high altitude acclimatization and characterize a potential mechanism underlying hypoxia-induced immune sensitization.

Abstract: Choline is an essential nutrient that can be found in the diet as water- (i.e., free choline (FC)) and lipid-soluble forms. Animal studies have demonstrated that choline is needed for optimal maternal immune function and immune system development in offspring. Moreover, the forms of choline modulate the development of the immune system differently, with diets high in phosphatidylcholine (PC; lipid-soluble form of choline) enhancing the development of the immune system to a greater extent than diets containing only FC in rodent. Despite evidence suggesting a greater impact of PC on immune responses, little is known about the role of sphingomyelin (SM), another lipid-soluble form, on immune system development. In addition, the benefits observed of dietary PC on immune function are consistently accompanied by an increased T cell proliferation as measured by higher interleukin (IL)-2 production. Obesity is characterized by the presence of immune dysfunction in both rodents and humans where a lower IL-2 production upon T cell stimulation is typically observed. To date, it is unknown whether dietary choline, especially the lipid-soluble forms, would counteract the obesity-related immune dysfunction observed in the state of obesity. Therefore, the objective of this thesis was to determine the impact of feeding different forms of choline on the immune system through different life stages (i.e., early in life and obesity). In a series of experiments, we aimed to determine the impact of feeding diets high in SM and/or PC on immune responses of lactating dams and local and peripheral immune systems development in offspring. Dams were fed one of three experimental diets all containing the same amount of total choline but differing in the form of choline: 1) a control diet containing only FC (water-soluble form); 2) a 50%PC diet (50% PC, 25% GPC and 25% FC); 3) a diet high in SM and PC (SMPC, 34-36% each). We observed that the forms of choline in the maternal diet were able to modulate the proportion of choline forms in breastmilk. Moreover, diets containing a high proportion of choline in the form of SM, improved T cells response in lactating dams by increasing ex vivo IL-2, TNF-α, and IFN-γ production by splenocytes. Meanwhile, growth was improved in offspring from the SMPC group. In addition, both diets containing a high proportion of lipid-soluble forms (at least 50%) improve the maturation of peripheral immune responses in suckled pups by increasing the production by splenocytes of TNF-α, and IFN-γ following T cells mitogen stimulation. In weaned pups (10 weeks of age), peripheral immune responses were enhanced by both diets high in lipid-soluble forms of choline. There was a higher production of IL-2 by splenocytes along with IFN-γ after T cell mitogen stimulation. Moreover, the lipid-soluble forms of choline positively modulated T cell responses in the gut by increasing IL-2, TNF-α, and IFN-γ production in mesenteric lymph nodes (MLN) and the proportion of B cells in Peyer’s patches. In addition, upon dietary antigen stimulation, there was a lower production of IL-2, TNF-α, and IL-6 and higher IL-10 production by immune cells from both spleen and MLN suggesting that the lipid-soluble forms of choline could potentially favor the development of oral tolerance. In a parallel study, we examined the effect of dietary PC in the context of a high-fat diet (HFD) feeding. Male Wistar rats were randomized to consumed one of three experimental diets: a control low-fat diet (FC only); a control HFD (FC only) and a HFD with PC as the main source of dietary choline. We observed that when fed the control HFD, Wistar rats had a lower ex vivo IL-2 and TNF-α production by splenocytes when compared to the control low-fat diet. When adding PC to a HFD these changes were no longer observed. Overall, we concluded that the lipid-soluble forms of choline provide more benefits for the development of both local and peripheral immune responses and the establishment of oral tolerance early in life. In addition, these results were also translated to a different model (HFD feeding) where we observed that the lipid-soluble forms (PC) can attenuate to some extent the obesity-related immune dysfunction.

Up to 70% of female breast cancer survivors (fBCS) fail to achieve recommended physical activity (PA) levels due to unique geographical, financial, emotional, aspirational and physical barriers that commonly as a result of diagnosis and treatment. This is problematic as it can lead to a poor health prognosis long-term. Therefore, research into motivational strategies to improve adherence to PA is pivotal. However, studies commonly incorporate complex interventions that are not always feasible nor founded in established behavioural change theories. The overall aim of this cross-over randomised pilot study was to investigate the effect of a psychological tool, motivational interviewing (MI), on levels of self-directed PA (as measured by step count), quality of life (QoL), self-efficacy and self-regulatory types. The behavioural change theory used to inform the design of the intervention, the selfdetermination theory (SDT), focuses on enhancing an individual’s intrinsic motivators to change and developing a strong sense of autonomy over their behaviour. This pilot study is a component of a larger trial that will investigate the outcomes mentioned before in addition to immune function and psychological health. The results of this pilot study showed there was no effect of MI on any of the outcomes except for the breast cancer subscale within the QoL measure. There is great variation in these findings in comparison to other research, however, understanding the sources of the large heterogeneity found between studies is vital to finding the key moderators and help to inform future research. Limitations included the global COVID19 pandemic which impacted recruitment, health status and ability of the participants to engage in self-directed PA as well as the small sample size which means results should be interpreted with caution. Additional limitations were possible under-reporting of step count data from the FitBit monitor. Suggestions for future research are inclusion of other tools such as tailored print materials, additional self-reporting PA measures, a change of QoL measure, online support and group walking sessions. Additionally, increasing the number of MI sessions including an initial in-person session as well as other objective measures to ensure the fidelity of the MI. Finally, incorporating another behavioural framework to enhance social aspects of the self-directed PA components and intentional aspects of the intervention to facilitate greater changes as well as a two-armed RCT design rather than cross-over is recommended. This study has been invaluable in identifying key aspects of MI and study design to help inform future research that may produce evidence to ultimately improve the well-being of fBCS long-term.

The circadian system is composed of a subset of temporal oscillators that function through a transcriptional and post-translational molecular and functional negative feedback loop cycling approximately every 24 hours. The central clock located in the suprachiasmatic nucleus is responsible for entrainment using light as the key timekeeper (zeitgeber); it is responsible for synchronizing and optimizing physiological behavior and function to the environment. Exogenous information, such as day length and light-dark cycles, provide critical temporal cues for adjusting to environmental conditions. Proper alignment to natural light dark cycles and circadian rhythms is optimal for vital health, fitness, and survival in organisms. Although considered previously innocuous, exposure to nighttime lighting is becoming increasingly prevalent due to development and urbanization. This can disrupt time of day variations to environmental adaptations and current literature has demonstrated that light at night (LAN) substantially disrupts physiological function and behavior, dysregulates circadian organization of immune function, metabolism. Further, this is associated with increased cardiometabolic disease, cancer, and other significant health risks. Exposure to LAN is becoming more pervasive to modern life and environments, where over 80% globally, and up to 99% of the United States and European populations are exposed to nighttime lighting. Circadian disruption has been linked to poor disease outcome in cases such as stroke, sepsis, and global ischemia, and critically ill and compromised patients may be especially at risk and vulnerable to the detrimental impacts of nighttime light. During acute injury, critically ill hospital patients require modern intensive care, which often results in nighttime lighting exposure. Circadian disruption through dim lighting exposure has been demonstrated to dysregulate pro-inflammatory cytokine production and neuroinflammation, and immune function. This is a concern given that chronic neuroinflammation can potentiate increased secondary damage in patients experiencing injury or exacerbate the effects of aging. However, there are critical gaps of knowledge that delineate the molecular and cellular mechanisms that are identifying how circadian disruption directly affects physiology. Because previous literature has identified neuroinflammation as a key aspect of physiological changes after exposure to light at night, a strategy for delineating how nighttime lighting exposure can change physiology after injury and in aged populations would involve focusing on immune system changes that would likely contribute to injury progression, and physiological aging and cognitive impairments. In this dissertation, I propose that disruptions to circadian rhythms through exposure to dim white light at night (dLAN) disrupts the circadian clock, resulting in increased health risks after ischemic injury, changes to immunological function, and greater susceptibility to cognitive impairments in aged mice. The central hypothesis tested in this dissertation is that exposure to light at night changes immune physiology and parameters that adversely affects injury progression in a murine model of stroke, physiology, and cognitive aging. The studies presented in this dissertation characterize the role of light at night affecting ischemic injury and infarct progression across two murine models of stroke. Further in Chapter 2, a cellular mechanism was identified. driving changes in immune response through shifts in microglial population phenotypes that drives increased infarct progression from nighttime lighting. The effect of nighttime lighting on immune activation and stroke outcome was prevented by using alternative spectral lighting that minimally activates intrinsically photosensitive retinal ganglion cells (ipRGCs) (Chapter 3). Next, the role of dLAN was investigated in aged populations that resulted in sex-specific alterations in physiology, immune response, and lifespan in Chapter 4. Lastly, I identified the role of disrupted circadian rhythms in aged populations to identify that chronic phase advances increase cognitive impairment and alters a component of vascular structure in aged populations in Chapter 5. Taken together, these studies indicate that exposure to ecologically relevant levels of dim broad spectrum (white) LAN can result in changes to physiology that adversely affect the development of neuronal damage and ischemic injury producing poor functional outcomes. Further, these results suggest that disruptions to circadian rhythms in aged populations could be an additional risk factor for cognitive impairments and dementia, and LAN accelerates physiological aging. Together, these studies provide evidence that characterizes and further emphasizes the harmful consequences of disruptions to circadian rhythms and nighttime lighting exposure. These data can provide foundational research required to identify potential chronotherapeutic targets for pharmacological intervention or to improve thrombolytic therapy intervention in ischemic strokes that occur across time of day.

There are an estimated 56,000 new human immune deficiency virus (HIV) infections diagnosed nationally each year. Research has indicated that restored immunologic function results in a reduction in HIV transmission rates by more than 96%. Treatment adherence is instrumental in reducing HIV transmission rates as well as in preventing the progression of HIV to acquired immune deficiency syndrome (AIDS) and in improving health outcomes. However, depressive symptoms and psychological stress have been linked to poor treatment adherence. Poor sleep quality has been directly and indirectly associated with elevated HIV viral load and increased mortality in this population. The purpose of this study was to explore the relationships among population characteristics (demographic data, HIV/AIDS classification, psychological stress, and depressive symptoms), health behaviors (treatment adherence, sleep, and the use of health services), and health outcomes (immunologic function) in HIV-infected individuals. Andersen's Behavioral Model for Healthcare Utilization was the theoretical framework used to guide this study. It provided further clarification about factors that may impact immune function of people living with HIV/AIDS. The study sample consisted of 104 HIV-positive adults living in Northeast Ohio. This study was a descriptive, correlational secondary data analysis of a previously collected dataset. Descriptive statistics, Pearson's correlations and multiple linear regressions were used to identify the relationships among demographic data, HIV/AIDS classification, psychological stress, depressive symptoms, treatment adherence, sleep, missed clinic visits and immune function. Results found that population characteristics and health behaviors explained 23% of the variance in CD4+ T-lymphocyte count (R2= .227, F= 2.795, p= .009) and 24% of the variance in HIV viral load (R2= .244, F= 5.869, p< .001). More research is needed to identify what explains the additional variance in immune function among people living with HIV/AIDS. Understanding inter-relationship among factors such as psychological stress, depressive symptoms, and sleep and their impact the health status of people living with HIV/AIDS may allow for the development of interventions that may improve immune function and reduce HIV transmission rates.

Individuals with cancer may experience cognitive symptoms related to the immune system’s response to the cancer and cancer treatments. Specifically, inflammatory cytokines can induce clusters of physical symptoms and behavioral responses called ‘sickness behaviors’. Cognitive symptoms appear to occur alongside sickness behaviors in individuals with cancer. Little research has examined cognitive symptoms and immune function in individuals with colorectal cancer (CRC). The purpose of this cross-sectional comparative study was to 1) describe cognitive symptoms and inflammatory cytokine and biomarker expression in individuals with CRC, and 2) begin to characterize the relationship between cognitive symptoms and inflammatory cytokines and biomarkers. A biobehavioral model was used to examine cancer-related cognitive symptoms and proposes that symptoms and physiologic changes share a common psychoneuroimmunologic mechanism. Participants included 50 men and women newly diagnosed with primary or recurrent CRC within the past six months (M = 55 years) and a comparison group of 50 similar individuals without CRC (M = 58 years). Cognitive symptoms were measured using tests of attention (Attention Network Test), directed attention and working memory (Digit Span, Trail Making Test, Attentional Function Index), and long-term memory (Rey Auditory Verbal Learning Test, Everyday Memory Questionnaire). Pro-inflammatory cytokines (interleukin-1beta, interleukin-6, tumor necrosis factor-alpha) and biomarkers (interleukin-1 receptor antagonist, c-reactive protein, interleukin-10, transforming growth factor-beta1) were measured using standard commercial assays. As hypothesized, CRC participants performed worse on measures of directed attention and working memory and had higher serum levels of interleukin-6, c-reactive protein, and interleukin-10 compared to healthy controls. Unexpectedly, CRC participants had lower serum levels of transforming growth factor-beta1 compared to controls. Significant relationships were found between cognitive and immune variables using multiple regression analyses. Specifically, 1) higher serum c-reactive protein levels predicted poorer directed attention and working memory performance [F = (7, 91) = 6.17, p < 0.001], and 2) higher c-reactive protein and lower transforming growth factor-beta1 levels predicted poorer directed attention and working memory on self-report [F = (8, 90) = 9.92, p < 0.001] after controlling for covariates. These novel findings have important implications for understanding the illness experience in CRC and developing interventions to optimize cognitive function.

Feeding raw food diets to domestic cats is controversial. The objective of this study was to determine if raw feline diets were nutritionally adequate for kittens and whether they enhance immune function, reduce oxidative stress and improve digestibility. Twenty-four 9-week-old kittens underwent a 10-week growth feeding trial with two raw diet groups and one control group (commercial heat-processed canned diet) of eight kittens each. Anthropomorphic measurements, feed efficiency, oxidative stress, and blood biomarkers for innate and humoral immune function were evaluated. Additionally, 6 kittens and 4 adults participated in a 14 day digestibility trial using a 3 x 3 latin square design. Composite fecal cultures were periodically monitored for common bacterial pathogens. Both raw diets passed an American Association of Feed Control Officials (AAFCO) growth trial and had similar growth performance compared to the control diet. Minimal differences were measured in markers of innate or humoral immune function. Over time, higher lymphocyte and immunoglobulin responses were measured in kittens consuming the raw diets. A trend toward higher IgM levels was noted in one raw diet group. Higher exposure to bacterial degradation products, pathogen exposure, or nutritional differences may have stimulated a more robust immune response in the raw-fed groups. No differences in levels of oxidative stress were noted among the three groups. All kittens had decreasing levels of urinary isoprostanes over the 10-week testing period. Significantly higher digestibility of dry matter, organic matter, protein and energy were noted in the raw vs. control groups for both kittens and adult cats, despite similar levels of intake. These changes may be attributed to structural changes in proteins following processing, alterations in gastrointestinal flora, or differences in ingredient quality among diets. In conclusion, there was neither an advantage nor disadvantage of the two raw feline diets when compared with the commercial heat-processed, control diet and both diets would be deemed nutritionally adequate for feline growth based on AAFCO feeding trials. The raw food diets were associated with higher digestibility and decreased fecal matter. Future research on methods to reduce pathogen load while minimizing processing of animal tissue proteins is recommended.

Breastfeeding is thought to play a major role in protecting infants from disease. However, the immunological effects of breastmilk have not been studied systematically within the context of biological anthropology. In order to understand the factors that influence the production and transfer of breastmilk immunity, I used an evolutionary and biocultural framework to assess the complex interplay between immunity, reproduction, growth, and culture in Ariaal mothers and infants of northern Kenya. Specifically, I investigated two research questions: 1) How do maternal reproductive and nutritional characteristics influence immune biomarkers in breastmilk? and 2) How do breastmilk immune factors protect infants from disease and affect their health and growth? This dissertation utilized immunoglobulin A as a marker of immunity. It is found in abundance in breastmilk, providing pathogen protection to developing infants. Two hundred and fifty-one Ariaal mother-infant pairs were recruited into the study and gave breastmilk and saliva samples, underwent anthropometric measurement, and answered an extensive questionnaire. Immunoglobulin A was analyzed in breastmilk and saliva using a method I developed in the Clinical Ligand Assay Satellite Service laboratory at the University of Michigan. This work yielded three main results. First, maternal reproductive status and history was associated with the amount of breastmilk immunoglobulin A transferred to the infant, although maternal nutritional status was not. Specifically, energetic preparation for future offspring and reproductive history influenced maternal ability to produce immunoglobulin A in breastmilk. Second, the level of immunoglobulin A in breastmilk was not associated with infant growth, health, or protection from disease-exposing behaviors, although it did appear to vary with changes in infant body fat, indicating that breastmilk immunoglobulin A and infant body fat may work symbiotically to protect infants from disease. Finally, stunted infants had greater activation of salivary immunoglobulin A than infants who were not stunted, suggesting that costly immune activation may trade-off with growth in infancy. The results of this work indicate that reproductive and nutritional factors are intimately associated with the breastmilk immunoglobulin A system. Future long-term and comparative studies will assess the impact of immunoglobulin A in mothers and infants in other populations.

Amphibian populations are dramatically reduced from historical numbers on a global scale. Amphibians in agricultural regions experience a diverse set of environmental stressors that may disrupt immune function and increase susceptibility to infection. The draining of wetlands for water and land usage leads to desiccation, crowding, and ultimately temperature extremes. Fertilizers and pesticides further degrade the quality of the available water. American bullfrogs (Lithobates catesbeiana) were collected throughout a gradient of agricultural land use in the Sacramento, San Joaquin, and Salinas River watersheds of California, USA. Animals collected downstream of intense agricultural land use had increased stress hormone (corticosterone) concentrations and altered white blood cell differentials and activity relative to those in upstream locations. An individual stressor of global importance, an agrichemical mix, as well as the amphibian immune response to chronic stress were furthered examined in the laboratory. Exposure to a mixture of pesticides and nutrients commonly applied in California did not affect plasma corticosterone or immune function of adult L. catesbeiana, suggesting that additional factors or exposure scenarios influence amphibians in the wild. The effects of chronic stress on blood cell differentials and function were characterized in lab-bred African clawed frogs (Xenopus laevis) and wild-caught L. catesbeiana. In both species, increased plasma corticosterone was associated with increased whole blood oxidative burst activity and blood neutrophil concentrations, while blood lymphocyte and eosinophil concentrations were decreased. Taken together, our results suggest that wild amphibians experience stressful conditions in agricultural habitats and that stressors may alter immunity and result in disease.

Life-history theory predicts that energetically costly activities, such as growth, reproduction, or predator defenses should trade off against immunity. However, the effects of predator induced phenotypes immune system are relatively unexplored. I experimentally tested the effect of natural predators on the immune system of wood frog tadpoles (Rana sylvatica) by exposing half of the tadpoles to caged dragonfly larvae predators, and half to empty cages. I then administered a standard immunoassay, the phytohemagglutinin (PHA) assay to a randomly selected group of animals from each treatment. These results reveal that exposure to predators reduces the response to PHA in larval R. sylvatica. Furthermore, predator-exposed larvae lack the typical decline in immunocompetence during metamorphosis that is found in normal amphibian larvae and have a weaker response to PHA throughout their development. Thus, predators have an effect on both immunocompetence and developmental patterns of immunity. Generally, predator exposure may facilitate parasitic infection in amphibians by reducing immune function, and thereby render amphibian populations vulnerable to co-exploitation by both predators and parasites.

Two experiments were conducted to examine the effects of dietary boron (B) on immune response and physiological responses to a viral disease challenge in growing steers. In experiment 1, 36 Angus and Angus x Simmental cross steers with an initial average body weight (BW) of 284 kg were fed one of three dietary treatments: 1) control (no supplemental B), 2) 5 mg supplemental B⁄kg DM, and 3) 15 mg supplemental B⁄kg DM from Na2B4O7 for 47 d. The control diet analyzed 13.3 mg B⁄kg DM. On d 34 of the study steers were inoculated intranasally with bovine herpevirus type-1 (BHV-1). Supplementation of dietary B increased (P < 0.01) plasma B concentration in a dose responsive manner. The change in DMI from d 0 (pre-inoculation) differed (P < 0.05) on d 1 and 2 among the control steers and those supplemented with 15 mg B⁄kg DM, due to an increase in DMI in control steers. The rectal temperature change from pre-inoculation values for steers supplemented with 15 mg B⁄kg DM tended (P < 0.10) to be less on d 6 and was less (P < 0.01) on d 7 and 8 post challenge than steers supplemented with 5 mg B⁄kg DM. On d 8 steers consuming the control diet had a greater decrease (P < 0.05) in rectal temperature change relative to d 0 when compared to steers supplemented with 5 mg B⁄kg DM. Inoculation of BHV-1 increased (P < 0.01) plasma concentrations of acute phase proteins by d 4 post challenge relative to d 0 values. Inoculation of BHV-1 decreased (P < 0.01) plasma IFN-γ concentrations on d 4, and increased (P < 0.01) plasma concentrations of TNF-α on d 2 post inoculation and d 4 TNF-α concentrations were lower(P < 0.01) than d 0 concentrations. ii In experiment 2, 36 Angus and Angus x Simmental cross steers with an initial average body weight (BW) of 269 kg were used to determine the effect of dietary B on immune response. Steers were fed one of three dietary treatments: 1) control (no supplemental B), 2) 5 mg supplemental B⁄kg DM, and 3) 50 mg supplemental B⁄kg DM from sodium borate (Na2B4O7 · 5H2O) for 78 d. The control diet analyzed 10.2 mg B⁄kg DM. Supplementation of dietary B increased (P < 0.01) plasma B concentration in a dose responsive manner. Also, supplemental B tended (P = 0.12) to increase the blastogenic response of B-lymphocytes to pokeweed mitogen, but did not affect proliferation of T-lymphocytes when stimulated with concanavalin A or phytohaemagglutinin (PHA). Furthermore, specific anti-PRBC IgG titers tended to be affected by a treatment x day interaction (P = 0.07). Boron supplemented steers had greater (P < 0.05) IgG titers than controls on d 7 but not on d 14 or 21 post-injection. Specific anti-PRBC IgM titers were not affected by dietary B. Dietary B did not affect skinfold thickness following PHA injection. Boron supplemented steers tended (P = 0.12) to have greater ADFI than control steers. Average daily gain and G:F was not affected during the study. Supplementation of dietary B had minimal effects on immune responses and disease resistance in growing steers. Lack of a significant effect of B was likely due to the B content in the basal diet. The basal diets containing 13.3 and 10.2 mg B⁄kg DM seemed to provide optimal physiological responses.

Both exposure to positive social interactions and stress can influence health outcome, via alterations in the hypothalamic-pituitary-adrenal (HPA) axis and changes in immune functioning. The first series of experiments examined the roles of social interactions and stress on wound healing and HPA axis activity in Peromyscus species exhibiting various social structures. Social facilitation decreased wound size in male monogamous versus male polygamous Peromyscus; this relationship was mediated by physical contact. Further investigation of social facilitation and stress effects on wound healing elucidated the interactions between pair housing and wound healing by examining various housing dyads. Positive social interactions facilitate wound healing in monogamous and polygynous Peromyscus regardless of the sex of the experimental or stimulus mouse. However, the effects of pair housing on wound healing are limited; male and female polygynous mice benefit from pair housing, but only under non-stressed conditions. Thus, differences in social systems can influence the extent to which social interactions may be beneficial to wound healing.The second series of experiments examined the impact of endogenous glucocorticoids on physiological parameters following experimental stroke. Stress exacerbates post-stroke neuronal damage, via increases in circulating corticosteroid concentrations and greater cerebral edema, compared to mice not experiencing stress or those allowed a temporal window between the conclusion of stress and the onset of stroke.The third series of experiments examined the effects of experimental stroke on peripheral immune function. An augmentation in the peripheral immune response is observed following stroke; however, stroke failed to alter the rate of cutaneous wound healing. This augmentation in peripheral immune function was mitigated when neuronal damage was prevented via hypothermia. Pair housing also mitigated the effects of stroke on cell-mediated immune function and reduced wound size, regardless of the surgical condition. Restraint stress increases neuronal damage, which can lead to a decrease in humoral immune function when coupled with stress following stroke; however, stress, in the absence of neuronal damage, increases humoral immune function, thereby further adding to the literature elucidating stress effects on immune function. In conclusion, the work described in this dissertation adds to the body of literature that elucidates the relationship between social interactions, stress, and health.

The purpose of this study was to evaluate the effectiveness of a whey protein isolate (WPI), a reported glutathione (GSH) booster, on exercise performance, immune function, and antioxidant status during weight maintenance and energy restriction in humans. Twenty well-trained, college age, male cyclists performed a cycling exercise test for 45 min, the first 7 min at 70% of VO2peak and the remaining 38 min at 55% VO₂peak immediately followed by a performance test set at 90% VO2peak until exhaustion. Blood samples were collected prior to the exercise test, after 45 min of exercise, within 5 min of exhaustion, and 1 h after exercise. Blood samples were analyzed for GSH, GSH/GSSG ratio, glutathione peroxidase (GPx), lipid hydroperoxides (LPO), phagocytosis, oxidative burst, peripheral blood mononuclear cell (PBMC) proliferation, and PBMC phenotyping. Subjects consumed 40g/day of WPI or casein placebo (P) along with their normal diet for 2 wk, repeated the exercise test, and then began a low energy period continuing the same supplementation for 4 d before the final exercise test. WPI was not associated with superior exercise performance or antioxidant status following exercise or weight loss. WPI supplementation did result in 33% greater lymphocyte proliferation capacity following exercise. Following exhaustive exercise for all trials, tGSH and GPx increased 7% and 11%, respectively, while WBCGSH decreased 13%. For WPI, GPx activity was 10% lower than P following exhaustive exercise for all trials combined. Weight loss (2.67 ± 0.26 kg) resulted in increases in phagocytosis (65%), white blood cell (WBC) GSH (40%), and GPx (35%) while decreasing the GSH/GSSG ratio (55%) and LPO (16%). Exhaustive exercise caused a 28% increase in CD8+ PBMCs and decreased CD4+ (34%), CD3+ (15%), the CD4+/8+ ratio (45%), and phagocytosis (8%) with all values returning to baseline after 1 h recovery. Supplementation with WPI did not enhance GSH status or exercise performance in trained cyclists, during weight maintenance or energy restriction. Following exercise, WPI is associated with greater lymphocyte proliferation of PBMCs which may help maintain an athlete's health during heavy training or competition.

A growing body of evidence has demonstrated that soy isoflavone consumption may protect against the development of various chronic diseases. This defense could be linked to isoflavone-induced alterations in immune function. However, to date, no study has examined the effect of soy isoflavone supplementation on human immunity in vivo. Establishing whether isoflavones affect immunity in aging adults is particularly relevant since compromised immune function has been observed in this population. Therefore, the purpose of this double-blind, placebo-controlled, 4-wk intervention trial was to investigate whether supplementation with soy isoflavones influenced the distribution and/or function of specific lymphocytes in postmenopausal women. Healthy postmenopausal women (50-69 y), who were not using hormone replacement therapy, were randomly divided into 2 treatment groups. The experimental group (n=9) consumed two-50 mg soy isoflavone tablets/d for 4 wk, while the control group (n=9) received placebo tablets. Fasting blood samples were drawn at baseline and on d 28 to assess distribution of T-helper cells (CD3+CD4+), T-cytotoxic cells (CD3+CD8+), total T lymphocytes (CD3+), B lymphocytes (CD19+) and natural killer (NK) cells (CD16+CD56+) via flow cytometry. Cytotoxicity of NK cells was quantified based on lactate dehydrogenase release of lysed K562 cancer cells following co-culture with NK cells from subjects. Analysis of plasma isoflavone concentrations by HPLC demonstrated a significant increase (p