Chronic exercise increases macrophage-mediated tumor cytolysis in young and old mice

Physical exercise, health, and disease treatment: The role of macrophages

Subclinical inflammation is linked to comorbidities and risk factors, consolidating the diagnosis of chronic non-communicable diseases, such as insulin resistance, atherosclerosis, hepatic steatosis, and some types of cancer. In this context, the role of macrophages is highlighted as a marker of inflammation as well as for the high power of plasticity of these cells. Macrophages can be activated in a wide range between classical or proinflammatory, named M1, and alternative or anti-inflammatory, also known as M2 polarization. All nuances between M1 and M2 macrophages orchestrate the immune response by secreting different sets of chemokines, while M1 cells promote Th1 response, the M2 macrophages recruit Th2 and Tregs lymphocytes. In turn, physical exercise has been a faithful tool in combating the proinflammatory phenotype of macrophages. This review proposes to investigate the cellular and molecular mechanisms in which physical exercise can help control inflammation and infiltration of macrophages within the non-communicable diseases scope. During obesity progress, proinflammatory macrophages predominate in adipose tissue inflammation, which reduces insulin sensitivity until the development of type 2 diabetes, progression of atherosclerosis, and diagnosis of non-alcoholic fatty liver disease. In this case, physical activity restores the balance between the proinflammatory/anti-inflammatory macrophage ratio, reducing the level of meta-inflammation. In the case of cancer, the tumor microenvironment is compatible with a high level of hypoxia, which contributes to the advancement of the disease. However, exercise increases the level of oxygen supply, favoring macrophage polarization in favor of disease regression.

Influence of Industrial Factors on Cytomorphological Indicators of Phagocytic Cells

AIM: The article has researched cell morphological changes of phagocytic system’s cell of experimented animals by influence of cool-rock dust phisical loading basis. METHODS: The phagocytic activity in combined operation of destructive changes in the cells and the lowering of vital capacity was investigated. RESULTS: The taken results let cosider the structure-functional condition of the phagocytal system’s cell in operation of unfavorable and industrial factors. CONCLUSION: Experimental animals with intratracheal administration of CRD have pronounced changes in phagocytic activity in AML, RBM and PA as compared with the control group.

Exercise-induced late preconditioning in mice is triggered by eNOS-dependent generation of nitric oxide and activation of PKCε and is mediated by increased iNOS activity

The purpose of this study was to assess whether short-term, mild exercise induces protection against myocardial infarction and, if so, what role the eNOS-PKCε-iNOS axis plays. Mice were subjected to 2 bouts/day of treadmill exercise (60 min at 15 m/min) for 2 consecutive days. At 24 h after the last bout of exercise, mice were subjected to a 30-min coronary artery occlusion and 24 h of reperfusion. In the exercise group (group III, wild-type mice), infarct size (25.5 ± 8.8% of risk region) was significantly (P < 0.05) reduced compared with the control groups (sham exercise, group II [63.4 ± 7.8%] and acute myocardial infarction, group I [58.6 ± 7.0%]). This effect was abolished by pretreatment with the NOS inhibitor L-NA (group VI, 56.1 ± 16.2%) and the PKC inhibitor chelerythrine (group VIII, 57.9 ± 12.5%). Moreover, the late PC effect of exercise was completely abrogated in eNOS^-/- mice (group XIII, 61.0 ± 11.2%). The myocardial phosphorylated eNOS at Ser-1177 was significantly increased at 30 min after treadmill training (exercise group) compared with sham-exercised hearts. PKCε translocation was significantly increased at 30 min after exercise in WT mice but not in eNOS^-/- mice. At 24 h after exercise, iNOS protein was upregulated compared with sham-exercised hearts. The protection of late PC was abrogated in iNOS^-/- mice (group XVI, 56.4 ± 12.9%) and in wildtype mice given the selective iNOS inhibitor 1400 W prior to ischemia (group X 62.0 ± 8.8% of risk region). We conclude that 1) even short, mild exercise induces a delayed PC effect that affords powerful protection against infarction; 2) this cardioprotective effect is dependent on activation of eNOS, eNOS-derived NO generation, and subsequent PKCε activation during PC; 3) the translocation of PKCε is dependent on eNOS; 4) the protection 24 h later is dependent on iNOS activity. Thus, eNOS is the trigger and iNOS the mediator of PC induced by mild exercise.

Biofilm-Innate Immune Interface: Contribution to Chronic Wound Formation

Delayed wound healing can cause significant issues for immobile and ageing individuals as well as those living with co-morbid conditions such as diabetes, cardiovascular disease, and cancer. These delays increase a patient’s risk for infection and, in severe cases, can result in the formation of chronic, non-healing ulcers (e.g., diabetic foot ulcers, surgical site infections, pressure ulcers and venous leg ulcers). Chronic wounds are very difficult and expensive to treat and there is an urgent need to develop more effective therapeutics that restore healing processes. Sustained innate immune activation and inflammation are common features observed across most chronic wound types. However, the factors driving this activation remain incompletely understood. Emerging evidence suggests that the composition and structure of the wound microbiome may play a central role in driving this dysregulated activation but the cellular and molecular mechanisms underlying these processes require further investigation. In this review, we will discuss the current literature on: 1) how bacterial populations and biofilms contribute to chronic wound formation, 2) the role of bacteria and biofilms in driving dysfunctional innate immune responses in chronic wounds, and 3) therapeutics currently available (or underdevelopment) that target bacteria-innate immune interactions to improve healing. We will also discuss potential issues in studying the complexity of immune-biofilm interactions in chronic wounds and explore future areas of investigation for the field.

Exercise and cancer: a position statement from the Spanish Society of Medical Oncology

Due to improvements in the number of cancer survivors and survival time, there is a growing interest in healthy behaviors, such as physical activity (PA), and their potential impact on cancer- and non-cancer-related morbidity in individuals with cancer. Commissioned by the Spanish Society of Medical Oncology (SEOM), in this review, we sought to distill the most recent evidence on this topic, focusing on the mechanisms that underpin the effects of PA on cancer, the role of PA in cancer prevention and in the prognosis of cancer and practical recommendations for clinicians regarding PA counseling. Despite the available information, the introduction of exercise programs into the global management of cancer patients remains a challenge with several areas of uncertainty. Among others, the most effective behavioral interventions to achieve long-term changes in a patient’s lifestyle and the optimal intensity and duration of PA should be defined with more precision in future studies.

Effects of Exercise on the Tumour Microenvironment

Epidemiological evidence suggests that exercise improves survival in cancer patients. However, much is still unknown regarding the mechanisms of this positive survival effect and there are indications that exercise may not be universally beneficial for cancer patients. The key to understanding in which situations exercise is beneficial may lie in understanding its influence on the tumour microenvironment (TME)-and conversely, the influence of the tumour on physical functioning. The TME consists of a vast multitude of different cell types, mechanical and chemical stressors and humoral factors. The interplay of these different components greatly influences tumour cell characteristics and, subsequently, tumour growth rate and aggression. Exercise exerts whole-body physiological effects and can directly and indirectly affect the TME. In this chapter, we first discuss the possible role of exercise capacity ('fitness') and exercise adaptability on tumour responsiveness to exercise. We summarise how exercise affects aspects of the TME such as tumour perfusion, vascularity, hypoxia (reduced oxygenation) and immunity. Additionally, we discuss the role of myokines and other circulating factors in eliciting these changes in the TME. Finally, we highlight unanswered questions and key areas for future research in exercise oncology and the TME.

Modifiable Host Factors in Melanoma: Emerging Evidence for Obesity, Diet, Exercise, and the Microbiome

PURPOSE OF REVIEW

We discuss how potentially modifiable factors including obesity, the microbiome, diet, and exercise may impact melanoma development, progression, and therapeutic response.

RECENT FINDINGS

Obesity is unexpectedly associated with improved outcomes with immune and targeted therapy in melanoma, with early mechanistic data suggesting leptin as one mediator. The gut microbiome is both a biomarker of response to immunotherapy and a potential target. As diet is a major determinant of the gut microbiome, ongoing studies are examining the interaction between diet, the gut microbiome, and immunity. Data are emerging for a potential role of exercise in reducing hypoxia and enhancing anti-tumor immunity, though this has not yet been well-studied in the context of contemporary therapies. Recent data suggests energy balance may play a role in the outcomes of metastatic melanoma. Further studies are needed to demonstrate mechanism and causality as well as the feasibility of targeting these factors.

Can Exercise-Induced Modulation of the Tumor Physiologic Microenvironment Improve Antitumor Immunity?

The immune system plays an important role in controlling cancer growth. However, cancers evolve to evade immune detection. Immune tolerance and active immune suppression results in unchecked cancer growth and progression. A major contributor to immune tolerance is the tumor physiologic microenvironment, which includes hypoxia, hypoglucosis, lactosis, and reduced pH. Preclinical and human studies suggest that exercise elicits mobilization of leukocytes into circulation (also known as "exercise-induced leukocytosis"), especially cytotoxic T cells and natural killer cells. However, the tumor physiologic microenvironment presents a significant barrier for these cells to enter the tumor and, once there, properly function. We hypothesize that the effect of exercise on the immune system's ability to control cancer growth is linked to how exercise affects the tumor physiologic microenvironment. Normalization of the microenvironment by exercise may promote more efficient innate and adaptive immunity within the tumor. This review summarizes the current literature supporting this hypothesis.

Slowing down glioblastoma progression in mice by running or the anti-malarial drug dihydroartemisinin? Induction of oxidative stress in murine glioblastoma therapy

Influencing cancer metabolism by lifestyle changes is an attractive strategy as - if effective - exercise-induced problems may be less severe than those induced by classical anti-cancer therapies. Pursuing this idea, clinical trials evaluated the benefit of e.g. different diets such as the ketogenic diet, intermittent caloric restriction and physical exercise (PE) in the primary and secondary prevention of different cancer types. PE proved to be beneficial in the context of breast and colon cancer.Glioblastoma has a dismal prognosis, with an average overall survival of about one year despite maximal safe resection, concomitant radiochemotherapy with temozolomide followed by adjuvant temozolomide therapy. Here, we focused on the influence of PE as an isolated and adjuvant treatment in murine GB therapy.PE did not reduce toxic side effects of chemotherapy in mice administered in a dose escalating scheme as shown before for starvation. Although regular treadmill training on its own had no obvious beneficial effects, its combination with temozolomide was beneficial in the treatment of glioblastoma-bearing mice. As PE might partly act through the induction of reactive oxygen species, dihydroartemisinin - an approved anti-malarial drug which induces oxidative stress in glioma cells - was further evaluated in vitro and in vivo. Dihydroartemisinin showed anti-glioma activity by promoting autophagy, reduced the clonogenic survival and proliferation capacity of glioma cells, and prolonged the survival of tumor bearing mice. Using the reactive oxygen species scavenger n-acetyl-cysteine these effects were in part reversible, suggesting that dihydroartemisinin partly acts through the generation of reactive oxygen species.

Exercise and gut immune function: evidence of alterations in colon immune cell homeostasis and microbiome characteristics with exercise training

There is robust evidence that habitual physical activity is anti-inflammatory and protective against developing chronic inflammatory disease. Much less is known about the effects of habitual moderate exercise in the gut, the compartment that has the greatest immunological responsibility and interactions with the intestinal microbiota. The link between the two has become evident, as recent studies have linked intestinal dysbiosis, or the disproportionate balance of beneficial to pathogenic microbes, with increased inflammatory disease susceptibility. Limited animal and human research findings imply that exercise may have a beneficial role in preventing and ameliorating such diseases by having an effect on gut immune function and, recently, microbiome characteristics. Emerging data from our laboratory show that different forms of exercise training differentially impact the severity of intestinal inflammation during an inflammatory insult (for example, ulcerative colitis) and may be jointly related to gut immune cell homeostasis and microbiota-immune interactions. The evidence we review and present will provide data in support of rigorous investigations concerning the effects of habitual exercise on gut health and disease.

Innate immune response adaptation in mice subjected to administration of DMBA and physical activity

Although there is growing interest in studies that promote the benefits of exercise and the correlation between exercise and fighting cancer, previous studies have not been able to elucidate the underlying mechanisms. The aim of the present study was to investigate cytokine synthesis by peritoneal macrophages in the presence of mammary tumors and the effect of physical activity. Female BALB/c virgin mice (age, eight weeks) were obtained for the present study and divided into four groups: A no tumor/non-trained control group; a no tumor/trained group subjected to swim training; a tumor/non-trained group in which the mice received the carcinogenic drug, DMBA and a tumor/trained group in which the mice were subjected to DMBA and swim training protocols. Following the experimental period, immune cells were collected from the peritoneal fluid, placed in culture medium and stimulated with lipopolysaccharide. The presence of the cluster of differentiation-14 marker and expression of the interleukin (IL)-12 cytokine was assessed by flow cytometry and measured via an enzyme-linked immunosorbent assay. The following cytokines were also identified: Interferon-γ, IL-4, IL-10, IL-12, tumor necrosis factor-α and transforming growth factor-β. Physical activity increased the quantity of IL-12 producing macrophages, whereas the presence of a tumor decreased the quantity of macrophages expressing IL-12. Tumor induction, in the absence of swim training, reduced macrophage-profile 1 (M1) cytokine levels while increasing the presence of macrophage-profile 2 cytokines. Physical activity in mice with tumors resulted in reductions in tumor development and promoted immune system polarization towards an antitumor M1 response pattern profile.

Advanced age impairs macrophage polarization

Aging affects many aspects of the cellular function of macrophages. Macrophages play a critical role in innate immunity, acting as sentinels to fight pathogens, promoting wound healing, and orchestrating the development of the specific acquired immune response. However, little is known about how age influences the ability of macrophage to change phenotypes in response to environmental factors. This study examined the age-associated defects on macrophage polarization toward a pro-inflammatory (M1) or an anti-inflammatory (M2) phenotype. Adherent splenocytes enriched for macrophages were cultured with or without lipopolysaccharide (LPS), a combination of interferon (IFN)-γ and tumor necrosis factor (TNF)-α or interleukin (IL)-4. A panel of M1 markers, inducible nitric oxide synthase (iNOS), IL-6, IL-1β, and TNF-α, and M2 markers, including arginase-1 (Arg1), Ym1, and Found In Inflammatory Zone 1 (FIZZ1), were analyzed. IL-6 mRNA in cells from aged mice was decreased by 78% and 58% compared with young after stimulation with LPS or IFN-γ and TNF-α (P<0.05), respectively. Also, there was a marked reduction in the induced levels of iNOS, IL-1β, and TNF-α in cells from aged mice relative to young controls. Similarly, IL-4 exposure resulted in a reduction of M2 markers in adherent splenocytes from aged mice compared with younger animals. This was consistent with a 28% decrease in splenic F4/80(+)IL-4R(+) cells in aged mice relative to controls, although IL-4R expression on these cells did not vary between age groups. In contrast, levels of M1 and most M2 markers, save for FIZZ1, in bone marrow-derived macrophages were similar between the age groups, irrespective of stimuli. These data imply that impaired macrophage polarization in the elderly may dysregulate the development of the host response, making them more susceptible to infectious diseases and that the aging microenvironment may be a key modulator of these macrophage-elicited responses.

Thrombosis, physical activity, and acute coronary syndromes

Acute coronary syndromes (ACS) are common, life-threatening cardiac disorders that typically are triggered by rupture or erosion of an atherosclerotic plaque. Platelet deposition and activation of the blood coagulation cascade in response to plaque disruption lead to the formation of a platelet-fibrin thrombus, which can grow rapidly, obstruct coronary blood flow, and cause myocardial ischemia and/or infarction. Several clinical studies have examined the relationship between physical activity and ACS, and numerous preclinical and clinical studies have examined specific effects of sustained physical training and acute physical activity on atherosclerotic plaque rupture, platelet function, and formation and clearance of intravascular fibrin. This article reviews the available literature regarding the role of physical activity in determining the incidence of atherosclerotic plaque rupture and the pace and extent of thrombus formation after plaque rupture.

Aging of the Innate Immune System: An Update

The relationship between advanced age and immunologic deficits is becoming an area of rapidly advancing research. Many of the clinical hurdles in the elderly population result from dysregulation of the immune system leading to the inability of the elderly to swiftly combat infection and to the increased incidence of chronic disease states and autoimmune conditions. Herein, we address the crucial alterations in the innate immune system that occur with advancing age. Specifically, we discuss how the effects of advanced age may lead to functional changes in the neutrophil, macrophage, dendritic cell, natural killer cell, and natural killer T cell populations in human and murine models that translate into aberrant innate immune responses. Furthermore, we elucidate how these changes may contribute to documented deficits in adaptive immunity as well as the pathological conditions and the increased morbidity and mortality seen in the elderly population.

The melanocortin 3 receptor: a novel mediator of exercise-induced inflammation reduction in postmenopausal women?

The purpose of this study was to determine whether resistance exercise training-induced reductions in inflammation are mediated via melanocortin 3 receptor expression in obese (BMI 32.7 ± 3.7) women (65.6 ± 2.8 yrs) randomized to either a control (N = 11) or resistance training group (N = 12). The resistance trained group performed resistance training 3 days/week for 12 weeks. Resting blood samples were collected before and after the training intervention in both resistance trained and control groups. Resistance training upregulated melanocortin 3 receptor mRNA by 16-fold (P = .035) and decreased monocyte count, without changing leukocyte number, body composition, or body weight. Resistance trained individuals exhibited increased sensitivity to inflammatory stimuli, whereas control individuals exhibited no change. While there was no change in whole blood tumor necrosis factor alpha mRNA between the groups, whole blood interleukin 10 mRNA was higher in the resistance trained group following the intervention period. In summary, it appears that resistance training may modulate melanocortin 3 receptor expression, providing a possible mechanism for the anti-inflammatory effects of exercise training.

The interaction of a high-fat diet and regular moderate intensity exercise on intestinal polyp development in Apc Min/+ mice

Diet and exercise are two environmental factors that can alter colon cancer risk. The purpose of this study was to determine if regular moderate-intensity treadmill exercise training could attenuate polyp formation in Apc(Min/+) mice fed the Western-style diet. Four-week-old male Apc(Min/+) mice (n = 12 per group) were assigned to AIN-76A Control, AIN-76A Exercise, Western Control, or Western Exercise treatment groups. Mice were weaned to these diets and either subjected to regular moderate-intensity treadmill exercise (18 m/min, 60 min/d, 6 d/wk) or remained sedentary for 6 weeks. Mice fed the Western-style diet consumed approximately 14% more calories and had 42% more epididymal fat compared with mice fed the AIN-76A diet. Exercise had no effect on fat pad mass with either diet treatment. Exercise reduced total intestinal polyp number by 50% and the number of large polyps (>1 mm diameter) by 67% in AIN-76A-fed mice. The Western-style diet increased polyp number by 75% when compared with AIN-76A-fed mice, but exercise did not decrease polyp number or alter polyp size in mice fed the Western-style diet. Markers of systemic inflammation and immune system function were improved with exercise in mice fed the AIN-76A diet. Mice fed the Western-style diet showed more inflammation and immunosuppression, which were not completely ameliorated by exercise. These data suggest that the induction of adiposity, inflammation, and immunosuppression by the Western-style diet may compromise the beneficial effect of moderate-intensity exercise on the intestinal polyp burden in Apc(Min/+) mice.

Physical activity and cancer prevention : pathways and targets for intervention

The prevalence of obesity, an established epidemiological risk factor for many cancers, has risen steadily for the past several decades in the US and many other countries. Particularly alarming are the increasing rates of obesity among children, portending continuing increases in the rates of obesity and obesity-related cancers for many years to come. Modulation of energy balance, via increased physical activity, has been shown in numerous comprehensive epidemiological reviews to reduce cancer risk. Unfortunately, the effects and mechanistic targets of physical activity interventions on the carcinogenesis process have not been thoroughly characterized. Studies to date suggest that exercise can exert its cancer-preventive effects at many stages during the process of carcinogenesis, including both tumour initiation and progression. As discussed in this review, exercise may be altering tumour initiation events by modifying carcinogen activation, specifically by enhancing the cytochrome P450 system and by enhancing selective enzymes in the carcinogen detoxification pathway, including, but not limited to, glutathione-S-transferases. Furthermore, exercise may reduce oxidative damage by increasing a variety of anti-oxidant enzymes, enhancing DNA repair systems and improving intracellular protein repair systems. In addition to altering processes related to tumour initiation, exercise may also exert a cancer-preventive effect by dampening the processes involved in the promotion and progression stages of carcinogenesis, including scavenging reactive oxygen species (ROS); altering cell proliferation, apoptosis and differentiation; decreasing inflammation; enhancing immune function; and suppressing angiogenesis. A paucity of data exists as to whether exercise may be working as an anti-promotion strategy via altering ROS in initiated or preneoplastic models; therefore, no conclusions can be made about this possible mechanism. The studies directly examining cell proliferation and apoptosis have shown that exercise can enhance both processes, which is difficult to interpret in the context of carcinogenesis. Studies examining the relationship between exercise and chronic inflammation suggest that exercise may reduce pro-inflammatory mediators and reduce the state of low-grade, chronic inflammation. Additionally, exercise has been shown to enhance components of the innate immune response (i.e. macrophage and natural killer cell function). Finally, only a limited number of studies have explored the relationship between exercise and angiogenesis; therefore, no conclusions can be made currently about the role of exercise in the angiogenesis process as it relates to tumour progression. In summary, exercise can alter biological processes that contribute to both anti-initiation and anti-progression events in the carcinogenesis process. However, more sophisticated, detailed studies are needed to examine each of the potential mechanisms contributing to an exercise-induced decrease in carcinogenesis in order to determine the minimum dose, duration and frequency of exercise needed to yield significant cancer-preventive effects, and whether exercise can be used prescriptively to reverse the obesity-induced physiological changes that increase cancer risk.

Higher antibody, but not cell-mediated, responses to vaccination in high physically fit elderly

The purpose of this study was to examine whether cardiovascular fitness, independent of confounding factors, was associated with immune responsiveness to clinically relevant challenges in older adults (60-76 yr). Thirteen sedentary, low-fit (LF; maximal O(2) uptake = 21.1 +/- 1.1 ml.kg(-1).min(-1)) and 13 physically active, high-fit (HF; maximal O(2) uptake = 46.8 +/- 3.4 ml.kg(-1).min(-1)) older adults participated in this study. Dietary intake was assessed, and a battery of psychosocial tests was administered. In vivo antibody and ex vivo proliferative and cytokine responses to influenza (Fluzone) and tetanus toxoid (TT) vaccination and delayed-type hypersensitivity skin tests were performed. HF elderly individuals displayed a higher antibody response to two of the three strains included in the Fluzone vaccine as measured by hemagluttination inhibition, but there was no difference between groups in influenza-specific ex vivo proliferation or IFN-gamma or IL-10 production. HF elderly individuals exhibited a lower IgG(1) response and a tendency for a higher IgG(2) response to the TT vaccine. There were, however, no differences in TT-specific ex vivo proliferation or IFN-gamma or IL-10 production. In contrast, HF subjects had higher proliferative responses to phytohemagluttinin. In addition, there were no differences in delayed-type hypersensitivity responses to fungal antigens between groups. These results suggest that, after accounting for confounding factors, HF elderly individuals have higher antibody responses to Fluzone vaccine and a Th2 skewing of the antibody response to TT. There was little evidence that HF mounted better cell-mediated immune responses to the Fluzone or TT vaccine measured in peripheral blood cells or to other recall antigens in vivo.

Lymphocyte responses to influenza and tetanus toxoid in vitro following intensive exercise and carbohydrate ingestion on consecutive days

The effect of carbohydrate (CHO) ingestion on antigen- (rather than mitogen-) stimulated T-cell responses to prolonged, intensive exercise may give a more realistic insight into the effect of CHO on T-cell functional capacity and subsequent infection risk. This study investigated the effect of CHO ingestion during prolonged, intensive exercise on influenza- and tetanus toxoid-stimulated T-cell cytokine mRNA expression and proliferation. Mitogen- [phytohemagglutinin (PHA)] stimulated proliferation was assessed for comparison. Responses were assessed following exercise on consecutive mornings to determine any carryover effect. Fifteen male games players performed two exercise trials in a double-blind, randomized, crossover design. Each trial comprised 90 min of intensive, intermittent running on consecutive mornings, with either CHO (6.4% wt/vol) or placebo (PLA) beverage ingestion before, during, and after each bout of exercise. Postexercise CD3(+) cell counts were higher in PLA than CHO on both days (P < 0.05). Antigen-stimulated T-cell cytokine mRNA expression was unaffected by exercise or CHO ingestion. Before exercise on day 2, T-cell proliferative responses to PHA, influenza, and tetanus toxoid were higher in CHO than PLA by 99, 80, and 58%, respectively (P < 0.01 for PHA, P < 0.05 for influenza and tetanus toxoid). At 1 h postexercise on day 2, PHA-induced proliferation was 70% higher in CHO than PLA (P < 0.05), yet there were no differences between trials for antigen-induced proliferative responses. Therefore, mitogen-induced T-cell proliferation following strenuous exercise and CHO does not necessarily reflect responses to specific antigens and, consequently, may not provide a good model for the situation in vivo.

Age effects on macrophage function vary by tissue site, nature of stimulant, and exercise behavior

We explored the effects of aging on macrophage function in male BALB/c mice from three age groups: young (2 months), middle-aged (12 months), and old (21 months). Macrophages were collected from alveoli, peritonea, and spleens of each age group. Cells were cultured in vitro with LPS or LPS+IFN-gamma and assayed for production of IL-1, IL-12, NO, and TNF-alpha. Using herpes simplex virus-1, age-related changes in intrinsic antiviral resistance (plaque assay) and extrinsic antiviral resistance (NO and TNF-alpha production) were determined in alveolar and/or peritoneal macrophages. Effects of chronic exercise on age-related macrophage changes were examined. In vitro, macrophages from the alveoli and spleen of older mice generally produced more cytokine and NO compared to younger counterparts. Conversely, macrophages from the peritonea of older mice generally produced less cytokine and NO in vitro compared to younger counterparts. Alveolar macrophages from both old and young mice showed higher intrinsic antiviral resistance to HSV-1 compared to middle-aged mice, while peritoneal macrophages from young mice showed reduced intrinsic resistance compared to those from both middle-aged and old mice. When challenged with HSV-1, a trend towards decreased peritoneal macrophage production of TNF-alpha and decreased alveolar macrophage production of IL-12 with advancing age was found. Chronic moderate exercise tended to reverse age-associated changes in macrophage function in old mice.

Role of lung macrophages on susceptibility to respiratory infection following short-term moderate exercise training

Moderate exercise training is associated with a decreased risk for upper respiratory tract infection in human and animal studies, but the mechanisms have not been elucidated. Lung macrophages play an important role in resistance to respiratory infection, and moderate exercise can enhance macrophage antiviral resistance, but no studies have directly tested the role of lung macrophages in this response. This study tested the effect of lung macrophage depletion on susceptibility to infection following short-term moderate exercise training. Mice were assigned to one of four groups: exercise (Ex) and resting controls (Con) with and without clodronate encapsulated liposomes (CL2MDP-lip). Ex mice ran for 1 h on a treadmill for 6 days at 36 m/min, 8% grade. Fifteen minutes following exercise or rest on the last day of training, mice were intranasally inoculated with a standardized dose of herpes simplex virus type 1. Clodronate (Ex-CL2MDP-lip and Con-CL2MDP-lip) or PBS liposomes (Ex-PBS-lip and Con-PBS-lip) (100 μl) were intranasally administered following exercise or rest on the 4th day of training and again on the 4th day postinfection. Morbidity, mortality, and symptom severity were monitored for 21 days. Exercise decreased morbidity by 36%, mortality by 61%, and symptom severity score on days 5–7 ( P < 0.05). Depletion of lung macrophages negated the beneficial effects of moderate exercise. This was indicated by no differences between Ex-CL2MDP-lip and Con-PBS-lip in morbidity (89 vs. 95%), mortality (79 vs. 95%), or symptom severity. Results indicate that lung macrophages play an important role in mediating the beneficial effects of moderate exercise on susceptibility to respiratory infection.

Effects of moderate exercise and oat β-glucan on lung tumor metastases and macrophage antitumor cytotoxicity

Both moderate exercise and the soluble fiber β-glucan can have beneficial effects on the initiation and growth of tumors, but the data are limited, and there is no information on their combined effects. This study tested the independent and combined effects of short-term moderate-exercise training and the soluble oat fiber β-glucan (OβG) on the metatastic spread of injected tumor cells and macrophage antitumor cytotoxicity. Male C57BL/6 mice were assigned to one of four groups: exercise (Ex)-H2O, Ex-OβG, control (Con)-H2O, or Con-OβG. OβG was fed in the drinking water for 10 days before tumor administration and death. Exercise consisted of treadmill running (1 h/day) for 6 days. After rest or exercise on the last day of training, syngeneic B16 melanoma cells (2 × 105) were administered via intravenous injection ( n = 8–11 per group). Lungs were removed 14 days later, and tumor foci were counted. Additional mice ( n = 8 per group) were killed, and peritoneal macrophages were assayed for cytotoxicity against the same mouse tumor cell line at various effector-to-target ratios. Both moderate exercise and OβG decreased lung tumor foci and increased macrophage cytotoxicity. However, there were no differences in lung tumor foci and macrophage cytotoxicity between Ex-OβG and either Ex-H2O or Con-OβG. These data suggest that, although not additive in their effects, both short-term moderate-exercise training and consumption of the soluble OβG can decrease the metatastic spread of injected B16 melanoma cells, and these effects may be mediated in part by an increase in macrophage cytotoxicity to B16 melanoma.

Long-term combined beneficial effects of physical training and metabolic treatment on atherosclerosis in hypercholesterolemic mice

The pathogenic mechanisms by which physical exercise influences atherosclerotic lesion formation remain poorly understood. Because vigorous physical training increases oxidative stress, this study tested the hypothesis that graduated and moderate physical exercise together with metabolic intervention (l-arginine and antioxidants) may contribute to increased vascular protection. Exercise training in mice was induced by graduated swimming. In hypercholesterolemic male mice on an atherogenic high-cholesterol diet, graduated and moderate exercise lowered plasma cholesterol and decreased atherosclerotic lesions compared with sedentary control mice. Antioxidants (1.0% vitamin E added to the chow and 0.05% vitamin C added to the drinking water) and l-arginine (6% in drinking water) supplementation to exercising hypercholesterolemic mice further and synergistically reduced atherosclerosis compared with untreated exercised mice. Arterial oxidation-specific epitopes and systemic oxidative stress were reduced by metabolic intervention. Graduated chronic exercise elicited an increase in production of nitric oxide through increased endothelial nitric oxide synthase expression and ameliorated scavenger activities. Thus, metabolic intervention with l-arginine and antioxidants together with graduated and moderate exercise training reduce atherosclerotic lesion formation.

Increased serum nIgM in voluntarily physically active rats: a potential role for B-1 cells

Moderate, habitual physical activity improves health, possibly because of beneficial changes in immune function. For example, physical activity can increase natural killer cell cytotoxicity, T cell proliferation, and macrophage function but has minimal impact on antigen-driven B-2-mediated immunoglobulin (Ig) responses. The following studies tested whether physical activity selectively impacts nonantigen-driven B-1-natural IgM (nIgM) but not antigen-driven B-2 Ig. Adult male, pathogen-free Sprague-Dawley rats in a barrier facility voluntarily ran in wheels from 7 to 56 days or were housed in an enriched environment for 56 days. Rats received either no antigen or keyhole limpet hemocyanin (KLH) to assess the B-2 response. Blood samples assessed serum nIgM, total IgG, total serum protein, anti-KLH IgM, and anti-KLH IgG. Physically active rats had higher serum nIgM after 7 days of running, and nIgM remained elevated over 56 days of running. In contrast, free-wheel running produced no changes in total IgG, total serum protein, anti-KLH IgM, and anti-KLH IgG. Environmental enrichment did not alter immune measures from controls. These results suggest that B-1, not B-2, cell responses are selectively impacted by physical activity. Because nIgM is important in multiple aspects of the immune response, an elevation in this innate humoral component could contribute to improved immunity in physically active organisms.

Effects of different durations of exercise on macrophage functions in mice

The effects of differing durations of daily exercise on macrophage functions in mice were studied. Male ICR mice aged 4 wk were divided into five groups: a nonexercise group (control) and four exercise groups with differing daily exercise durations of 15--120 min (Exr groups). The exercise applied was 5 days/wk treadmill running at 13 m/min for 12 wk. The potentiation of the phagocytosis function of the reticuloendothelial system and the glucose consumption of peritoneal macrophages in the Exr 30, 60, and 120 groups were significantly higher than those in the control group. Superoxide anion production of peritoneal macrophages in both the absence and the presence of phorbol 12-myristate 13-acetate in the Exr 60 and 120 groups was significantly higher than that in the control group. The acid phosphatase and beta-glucuronidase activities of peritoneal macrophages in the Exr 30, 60, and 120 groups were significantly increased. These results suggest that treadmill running exercise for at least 30 min/day (30--120 min) effectively enhances macrophage functions in mice. These data provide preliminary evidence indicating that chronic exercise-induced increases in phagocytic activity exhibit a dose-dependent relationship with exercise duration.

Intracellular mechanisms responsible for exercise-induced suppression of macrophage antigen presentation

In a previous study, we demonstrated that exhaustive exercise suppressed peritoneal macrophage antigen presentation (AP). In this study, we explored the intracellular mechanism(s) responsible for this suppression. Pathogen-free male BALB/c mice (8 +/- 2 wk) were randomly assigned to either home cage control (HCC) or exhaustive exercise stress (Exh, 18-30 m/min for 3 h/day) treatment groups. The mice underwent treatments for a period of 4 days during induced peritoneal thioglycollate inflammation. Elicited macrophages were harvested, purified, and incubated with chicken ovalbumin (C-Ova, 2. 5 and 10 mg/ml) for 18 h. After macrophages were washed, they were cocultured with C-Ova-specific T cells for 48 h at which time the supernates were harvested and analyzed via ELISA for interleukin (IL)-2 as an indication of macrophage AP. There was no significant (P > 0.05) difference in macrophage AP between cells fixed with paraformaldehyde vs. those that remained unfixed, suggesting that Exh did not affect production of soluble factors influencing macrophage AP (i.e., IL-1, IL-4, PGE(2)). The ability of macrophages to generate C-Ova immunogenic peptides was analyzed using FITC-labeled C-Ova, which shows fluorescence only when degraded intracellularly. There was a significant ( approximately 20%, P < 0. 05) suppression in fluorescence in the Exh compared with HCC, indicating a possible defect in the ability of macrophages from Exh to degrade C-Ova into immunogenic peptides. Macrophages were also incubated with C-Ova immunogenic peptide in a manner identical to that for native C-Ova. We found a similar suppression ( approximately 22-38%, P < 0.05) in macrophage AP using a C-Ova peptide when compared with native C-Ova in the Exh group, indicating reduced major histocompatibility complex (MHC) II loading and/or C-Ova-MHC II complex cell surface expression. In conclusion, these data indicate an intracellular defect in the macrophage antigen processing pathway induced by Exh.