Immunomodulation by 8-week voluntary exercise in mice

Effects of branched-chain amino acids on immune status of young racing horses

High-intensity exercise and competition are associated with depressed immune function. Young horses, which participate in high-intensity exercise and competitions, are at increased risk for the development of infectious disease due to depression of immune function. The effects of branched-chain amino acid (BCAA) supplementation on the immune status of young racing horses were evaluated, determining whether BCAA might help to avoid or reduce immune suppression during exercise and competitions. Twenty horses (10 male and 10 female) were treated with BCAA supplementation; another twenty untreated horses (10 male and 10 female) constituted control group. Peripheral blood was collected from each animal and evaluated for lymphocyte subsets, phagocytosis analysis of monocytes and granulocytes, lymphocyte proliferative response, and expression of cytokine-encoding messenger ribonucleic acids (mRNAs). The numbers of CD4⁺, CD8⁺, and major histocompatibility complex (MHC) class II⁺ cells in females of the treated group were significantly higher than those in females of the control group. The lymphocyte proliferative response in female of the treated group also was significantly higher than that in females of the control group. In addition, expression of mRNAs encoding interleukin-1β (IL-1β) and interferon-γ (IFN-γ) in females of the treated group was significantly higher than that in females of the control group. There were no significant differences between males of the treated and control groups. The results of this study indicated the positive effects of BCAA supplementation in counteracting immunosuppression in young female racing horses during and following high-intensity exercise.

Immunomodulatory effects of Bacillus subtilis (natto) B4 spores on murine macrophages

To investigate the immunomodulatory effects of Bacillus subtilis (B. subtilis) (natto) B4 spores on murine macrophage, RAW 264.7 cells were cultured alone or with B subtilis (natto) B4 spores at 37°C for 12 hrs, then both cells and culture supernatants were collected for analyses. Exposure of RAW 264.7 cells to B. subtilis (natto) B4 spores had no significant effects on macrophage viability and amounts of extracellular lactate dehydrogenase (LDH). However, it remarkably increased the activities of acid phosphatase (ACP), lactate dehydrogenase (LDH) and inducible nitric oxide synthase (iNOS) in cells and the amounts of nitric oxide (NO) and cytokines (tumor necrosis factor-alpha, interferon-gamma, interleukin [IL]-1 beta, IL-6, IL-12, IL-10 and macrophage inflammatory protein-2) in culture supernatants. These results demonstrate that B. subtilis (natto) B4 spores are harmless to murine macrophages and can stimulate their activation through up-regulation of ACP and LDH activities and enhance their immune function by increasing iNOS activity and stimulating NO and cytokine production. The above findings suggest that B. subtilis (natto) B4 spores have immunomodulatory effects on macrophages.

Induction of tumoricidal activity in mouse peritoneal macrophages by ginseng polysaccharide

This study examined the effects of ginseng polysaccharide (GPS) on mouse peritoneal macrophage (PM)-mediated cytotoxicity towards K562, HL-60, or KG1alpha cells. GPS had no direct effect on killing of tumor cells. However, when mouse PMs were treated with GPS, cytotoxic activity against K562, HL-60, or KG1alpha cells was significantly induced. In addition, phagocytic activity was enhanced in GPS-treated mouse PMs compared to the control. The expressions of CD(68), ACP and alpha-ANE in mouse PMs were increased by the treatment with GPS. Moreover, the levels of cytokines, including tumor necrosis factor-alpha (TNF-alpha), interleukin-1 (IL-1), IL-6 were increased and the production of nitric oxide (NO) was enhanced. Taken together, these results suggest that GPS possess a potent antitumor activity by stimulating macrophage and a potentiality as an immunomodulator against diseases such as cancer.

Effects of physical training on the immune system in diabetic rats

AIMS

This study aims to investigate the influence of physical training on the immune system of diabetic rats.

MATERIALS AND METHODS

Adult male Wistar rats were distributed into Sedentary Control (SC), Trained Control (TC), Sedentary Diabetic (SD) and Trained Diabetic (TD) groups were used. Diabetes was induced by alloxan (32 mg/bw-i.v.). Training protocol consisted of swimming, at 32 +/- 1 degrees C, one hour/day, five days/week, supporting an overload equivalent to 5% of the body weight, during four weeks. At the end of the experiment the rats were sacrificed by decapitation and blood samples were collected for glucose, insulin, albumin, hematocrit determinations, total and differential leukocyte counting. Additionally, liver samples for glycogen analyses were obtained.

RESULTS

The results were analyzed by one way at a significance level of 5%. Diabetes reduced blood insulin, liver glycogen stores and increased blood glucose and neutrophil count. Physical training restored glycemia, liver glycogen levels, neutrophils and lymphocytes count in diabetic rats.

CONCLUSIONS

In summary, physical training was able to improve metabolic and immunological aspects in the experimental diabetic rats.

Endurance training modulates lymphocyte function in rats with post-MI CHF

PURPOSE

Exercise training restores innate immune system cell function in post-myocardial infarction (post-MI) rats. However, studies of the involvement of lymphocyte (Ly) in the setting of the congestive heart failure (CHF) are few. To address this issue, we investigated the function of Ly obtained from cervical lymph nodes from post-MI CHF rats submitted to treadmill running training.

METHODS

Twenty-five male Wistar rats were randomly assigned to the following groups: rats submitted to ligation of the left coronary artery, which were sedentary (MI-S, N = 7, only limited activity) or trained (MI-T, N = 6, on a treadmill (0% grade at 13-20 m.m) for 60 min.d, 5 d.wk, for 8-10 wk); or sham-operated rats, which were sedentary (sham-S, N = 6) or trained (sham-T, N = 6). The incorporation of [2-C]-thymidine by Ly cultivated in the presence of concanavalin A (Con A) and lipopolysaccharide (LPS), cytokine production by Ly cultivated in the presence of phytohemagglutinin (PHA), and plasma concentration of glutamine were assessed in all groups, 48 h after the last exercise session.

RESULTS

Proliferative capacity was increased, following incubation with Con-A in the MI groups, when compared with the sham counterparts. When incubated in the presence of PHA, MI-S produced more IL-4 (96%) than sham-S (P < 0.001). The training protocol induced a 2.2-fold increase in the production of interleukin-2 (P < 0.001) of the cells obtained from the cervical lymph nodes of MI-T, compared with MI-S.

CONCLUSION

The moderate endurance training protocol caused an increase in IL-2 production, and a trend toward the reversion of the Th1/Th2 imbalance associated with IL-4 production increased in the post-MI CHF animal model.

Endurance training restores peritoneal macrophage function in post-MI congestive heart failure rats

Congestive heart failure (CHF) induces a state of immune activation, and peritoneal macrophages (Mφs) may play an important role in the development and progression of one such condition. Moderate endurance training modulates peritoneal Mφ function. We evaluated the effect of endurance training on different stages of the phagocytic process and in the production of interleukin-6 (IL-6), interleukin-1β (IL-1β) and tumor necrosis factor-α (TNF-α) after LPS stimulation. Either ligation of the left coronary artery or Sham operations were performed in adult Wistar rats. After 4 wk, control (Sham operated) and MI (ligation of the left coronary artery) animals were randomly assigned to either a sedentary (Sham-operated sedentary, n = 7 and MI sedentary, n = 10) or a trained group (Sham-operated trained, n = 8 and MI trained, n = 8). Trained rats ran on a treadmill (0% grade at 13–20 m/min) for 60 min/day, 5 days/wk, for 8–10 wk, whereas sedentary rats had only limited activity. Training increased maximal oxygen uptake normalized for body weight (ml·kg−1·min−1), as well as skeletal muscle citrate synthase maximal activity, when compared with sedentary groups. The resident and total cell number, the chemotaxis index, and the production of TNF-α stimulated by LPS were significantly higher in the MI sedentary group when compared with the Sham sedentary group. Moderate endurance training reversed these alterations promoted by post-MI. These results demonstrate that moderate intensity exercise training modulates peritoneal Mφ function and induces beneficial metabolic effects in rats with post-MI CHF.

Resting cellular and physiological effects of freewheel running

INTRODUCTION/PURPOSE

Exercise modulates many aspects of physiology. The purpose of the current experiment was to characterize the impact of regular, moderate physical activity on resting, baseline measures of cellular immunity blood lipids, and muscle enzyme.

METHODS

Male Fischer 344 rats were housed with either mobile (run, N = 10) or immobile (sedentary, N = 10) running wheels. After 4 wk of running, rats were sacrificed. Blood and muscle (long and medial heads of the triceps) were collected. From blood, white blood cell (WBC) differentials, red blood cell (RBC) count, hemoglobin, hematocrit, and lipid profiles were measured. Muscle citrate synthase (CS) activity was measured by spectrophotometric analysis.

RESULTS

Rats ran an average of 9.89 +/- 0.79 km.wk(-1). There were no differences in the total number of circulating WBC, RBC, or eosinophils. Freewheel running decreased the number of circulating neutrophils (P < 0.001), monocytes (P < 0.01), and basophils (P < 0.01), while increasing the number of lymphocytes (P < 0.001), when compared with sedentary animals. Mean corpuscular content of hemoglobin was elevated in the freewheel group (P < 0.01). Physically active animals had slightly lower triglycerides and LDL, and elevated HDL. These changes resulted in a significant improvement in LDL/HDL ratio (P < 0.05). Muscle CS activity was unchanged between groups.

CONCLUSION

Both the alterations in the RBC hemoglobin and lipid proteins are positive health changes associated with exercise training. The impact of the alterations in WBC differentials remains unknown but could indicate a reduction in inflammatory load. In conclusion, freewheel running provides sufficient exercise stimulus to produce some, but not all, training associated physiological adaptations.

Hydrophobic dipeptide Leu-Ile protects against neuronal death by inducing brain-derived neurotrophic factor and glial cell line-derived neurotrophic factor synthesis

We investigated whether certain hydrophobic dipeptides, Leu-Ile, Leu-Pro, and Pro-Ile, which partially resemble the site on FK506 that binds to immunophilin, could stimulate glial cell line-derived neurotrophic factor (GDNF) and brain-derived neurotrophic factor (BDNF) synthesis in cultured neurons and found only Leu-Ile to be an active dipeptide. Leu-Ile protected against the death of mesencephalic neurons from wild-type mice but not from mice lacking the BDNF or GDNF gene. Next, we examined the effects of i.p. or i.c.v. administration of Leu-Ile on BDNF and GDNF contents. Both types of administration increased the contents of BDNF and GDNF in the striatum of mice. Also, peripheral administration of Leu-Ile inhibited dopaminergic (DA) denervation caused by unilateral injection of 6-hydroxydopamine (6-OHDA) into the striatum of mice. The number of rotations following a methamphetamine challenge was lower in the Leu-Ile-treated group than in the nontreated group. Next, we compared the calcineurin activity and immunosuppressant activity of Leu-Ile with those of FK506. Leu-Ile was not inhibitory toward calcineurin cellular activity in cultured neuronal cells. Furthermore, Leu-Ile did not suppress concanavalin A (ConA)-induced synthesis/secretion of interleukin-2 by cultured spleen cells, suggesting that the immunosuppressant activity of Leu-Ile may be negligible when used as a therapeutic tool for neurodegenerative diseases.

Moderate exercise may attenuate some aspects of immunosenescence

BACKGROUND

Immunosenescence is related to the deterioration of many immune functions, which may be manifested in increased susceptibility to infection, cancer, and autoimmunity. Lifestyle factors, such as diet or physical activity, may influence the senescence of the immune system. It is widely accepted that moderate physical activity may cause beneficial effects for physical and psychological health as well as for the immune system activity in aged people.

METHODS

Thirty elderly women aged 62 to 86 were subjected to a two-years authorized physical activity program. Peripheral blood lymphocytes distribution and the production of cytokines involved in the immune response development and regulation (IL-2, IL-4 and IFN-gamma) were investigated. The same parameters were evaluated in two control groups of women: a sedentary group of 12 elderly women selected for the second round of the physical activity program and in a group of 20 sedentary young women. Flow cytometry methods were used for the examination of surface markers on peripheral blood lymphocytes and intracellular cytokines expression.

RESULTS

The distribution of the main lymphocytes subpopulations in the peripheral blood of elderly women did not show changes after long-term moderate physical training. The percentage of lymphocytes expressing intracellular IL-2 was higher in the group of women attending 2-years physical activity program than in the control group of elderly sedentary women, and it was similar to the value estimated in the group of young sedentary women. There was no difference in the intracellular expression of IL-4 and IFN-gamma between the active and elderly sedentary women.

CONCLUSIONS

Our results suggest that moderate, long-term physical activity in elderly women may increase the production of IL-2, an important regulator of the immune response. This may help ameliorate immunosenescence in these women.

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.

Immunomodulatory action of chronic exercise on macrophage and lymphocyte cytokine production in mice

This study was designed to evaluate the effects of 8-week voluntary running exercise on cytokine production of macrophages and lymphocytes. Seven-week-old-male BALB/c inbred mice were divided into two groups: a group given voluntary exercise (exercise group, n=32), and the other, a non-exercise group (control group, n=32). Exercise consisted of spontaneous running in wheels for 3 days per week over 8 weeks. The levels of nitric oxide (NO2-) and interleukin (IL)-1 beta production by lipopolysaccharide (LPS)-stimulated peritoneal macrophages from the exercise group was significantly higher than that in the control group (P < 0.05-P < 0.01). In the exercise group, stimulation indices by concanavalin A (Con A) was significantly higher than they were in the control group (P < 0.05-P < 0.001). When compared with the control group, the exercise group showed a significant (P < 0.05) increase in the splenic lymphocyte production of IL-2 stimulated by Con A (449.5 +/- 28.2 and 853.7 +/- 116.0 pg 4 x 10(5) cells(-1) 48 h(-1) for the control group and the exercise group, respectively). IL-4 production of splenocytes stimulated by Con A in the exercise group (37.6 +/- 5.1 pg 4 x 10(5) cells(-1) 48 h(-1)) was higher than that in the control group (30.9 +/- 3.9 pg 4 x 10(5) cells(-1) 48 h(-1)); however, the difference was not statistically significant. These results suggest that 8-week voluntary running exercise effectively enhanced macrophage and lymphocyte functions in mice.

Exercise alters the immune response to equine influenza virus and increases susceptibility to infection

Equine influenza virus remains a major health concern for the equine industry in spite of ongoing vaccination programmes. Previous work has shown that the immune system of horses can be affected by strenuous exercise. The possible adverse consequence of exercise-induced alterations in lymphocyte responses measured in vitro was unknown. Here we demonstrate that subjecting vaccinated ponies to a 5 day strenuous exercise programme results in a significant suppression of their T cell-mediated immune response to equine influenza virus as measured by decreased lymphoproliferation and gamma interferon production measured in vitro. These same ponies also demonstrated increased susceptibility to influenza disease following a challenge exposure to the same strain of virus. Rested ponies that had received the same vaccine and challenge were completely protected from disease. Our results demonstrate that exercise-induced suppression of the equine immune response to influenza virus can be associated with an increased susceptibility to disease.

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.