Effects of age, sex and physical exercise on the phagocytic process of murine peritoneal macrophages.

Different stages of the phagocytic process, i.e. chemotaxis, ingestion of latex beads and superoxide anion production, were measured in peritoneal macrophages from young (12 +/- 2 weeks old) and old (60 +/- 2 weeks old) male and female BALB/C mice, which were subjected to an acute bout of exercise (swimming until exhaustion) or to a period of training exercise (90 min of swimming each day during 20 days). Sedentary male and female mice as well as young and old animals were used as sex and age controls. The results show that both acute and training exercise stimulate the phagocytic process of murine peritoneal macrophages. The macrophage functions from sedentary controls were lower in the old than in the young animals. The chemotaxis and ingestion capacities of macrophages were higher in the female young and old sedentary mice than in their male counterparts. After exercise, the stimulation of the phagocytic process was higher in old and female mice than in young and male animals. In addition, serum corticosterone levels were measured in order to investigate the relations between stress and macrophage activity. Old and female mice as well as animals subjected to exercise showed, in general, higher corticosterone levels than young, male and sedentary animals.     

Effect of physical activity stress on the phagocytic process of peritoneal macrophages from old guinea pigs.

The different stages of the phagocytic function in peritoneal macrophages from old guinea pigs (27 +/- 3-months-old) were studied before, immediately after and 24 h after being subjected to physical activity stress (swimming until exhaustion) which raised the blood levels of corticosterone. The phagocytosis of opsonized Candida albicans was stimulated immediately after physical activity. No modifications in adherence, chemotaxis, ingestion of inert particles, or microbicide capacity, measured by nitroblue tetrazolium (NBT) reduction, were found. At 24 h, when no stress could be shown by corticosterone analysis, the phagocytosis of opsonized C. albicans remained stimulated and chemotaxis was increased while ingestion of inert particles and microbicide capacity remained unchanged. The adherence, however, was at a smaller level. No correlations were found between the corticosterone levels and the status of the phagocytic process of peritoneal macrophages.     

Stimulation of the phagocytic function in guinea pig peritoneal macrophages by physical activity stress

Summary A study was made of all the different stages of the phagocytic function in peritoneal macrophages from male guinea pigs [3 (SD 1) months old] before, immediately after, and 24 h after being subjected to stress from physical activity (swimming until exhaustion). The early (10 min) and late (40 min) adherence to tissue substrates, chemotaxis, attachment and phagocytosis ofCandida albicans, ingestion of inert particles (latex beads), and basal oxidative metabolism [measured by nitroblue tetrazolium (NBT) reduction] were significantly stimulated by the physical activity. After 24 h, late adherence, attachment capacities, and basal oxidative metabolism returned to basal values, whereas early adherence, chemotaxis, phagocytosis of cells and inert particles, and microbicidal capacity (production of superoxide anion measured by NBT reduction in presence of ingested material) remained significantly increased. The stress produced by physical activity, reflected in increased serum corticosterone values, led to a global stimulation of the phagocytic function.     

Ageing modulates some aspects of the non-specific immune response of murine macrophages and lymphocytes

The deterioration of the immune system with ageing, which leads to an increased morbidity and mortality from infections, appears to be related to decreases in specific lymphocyte functions. However, the alteration of non-specific immunity is a more controversial subject. Our purpose was to investigate the age-related changes of different functions of the non-specific immune response in peritoneal macrophages (adherence to tissues, mobility directed to a chemical gradient from an infectious focus or chemotaxis, phagocytosis of foreign agents and destruction of these agents by superoxide anion production) and in lymphocytes (adherence and chemotaxis) from peritoneum, axillary lymph nodes, spleen and thymus. We used young (12 weeks), adult (22 weeks), mature (48 weeks) and old (72 weeks) female BALB/c mice. The adherence capacity of macrophages and lymphocytes was greater in adult and old mice than in young animals. The chemotaxis of macrophages showed higher values in cells from young mice than in those from adult mice, increasing again in macrophages from mature and old animals. A similar behaviour was shown by phagocytosis, which reached its highest values in old animals. Anion superoxide production increased with age and again the highest values were obtained in the oldest mice. Conversely, chemotaxis of lymphocytes was higher in the adult and mature animals than in the young and old animals. We conclude that, although there is a decrease in lymphocyte chemotaxis in old animals, the non-specific immune response of macrophages instead of decreasing, may increase in aged mice with respect to the values seen in adult mice.     

Running reduces stress and enhances cell genesis in aged mice

Cell proliferation and neurogenesis are diminished in the aging mouse dentate gyrus. However, it is not known whether isolated or social living affects cell genesis and stress levels in old animals. To address this question, aged (17–18 months old) female C57Bl/6 mice were single or group housed, under sedentary or running conditions. We demonstrate that both individual and socially housed aged C57Bl/6 mice have comparable basal cell proliferation levels and demonstrate increased running-induced cell genesis. To assess stress levels in young and aged mice, corticosterone (CORT) was measured at the onset of the active/dark cycle and 4 h later. In young mice, no differences in CORT levels were observed as a result of physical activity or housing conditions. However, a significant increase in stress in socially housed, aged sedentary animals was observed at the onset of the dark cycle; CORT returned to basal levels 4 h later. Together, these results indicate that voluntary exercise reduces stress in group housed aged animals and enhances hippocampal cell proliferation.     

Hypothermia affects the phagocytic activity of rat peritoneal macrophages

To examine the effect of hypothermia on the phagocytic capacity of rat peritoneal macrophages for latex particles, male Wistar rats were exposed to 4 degrees C for 8 and 72 h. While the shorter exposure to cold did not affect body temperature and macrophage function, animals exposed to 4 degrees C for 72 h showed a mean decrease of their body temperature by 1.5 degrees C. The superoxide anion production was significantly increased whereas the number of phagocytic cells decreased. In addition, the mean number of latex particles engulfed by each individual cell was lower than that of controls. Peripheral blood mononuclear cells (PBMC) of these animals showed lower mitogen response to phytohaemagglutinin (PHA), while that for concanavalin A (Con-A) remained unchanged. Peritoneal macrophages exposed in vitro to 24 degrees C for 60 min showed a decreased phagocytic capacity in comparison with macrophages kept at 37 degrees C, an observation suggesting the development of an indigenous cell defect for phagocytosis at lower temperatures. On the other hand, the effect of additional humoral factor(s) on macrophage activity, such as an increase in serum level of catecholamines and corticosterone, cannot be excluded. The results of the study may contribute to understanding the predisposition to infections during exposure to cold.     

Murine lung response to kaolin conveyed by cigarette smoke

Summary The effects of chronic (3 to 8.5 months) smoke inhalation from cigarettes laced with 0.1, 1.0 and 10.0 mg kaolin (hydrated aluminum silicate) per gram of tobacco on the morphological integrity of lungs and the pulmonary macrophage population were evaluated in young and old male C57BL/6 mice. Lacing procedures, monitored by determining aluminum content in acid-digested aliquots of tobacco via atomic absorption spectrometry (AAS), proved to be uniform. Amounts of aluminum in right lungs of young mice evaluated by AAS and of kaolin assessed by electron diffraction and polarizing light microscopy were larger in mice which inhaled smoke from cigarettes laced with more kaolin. A more pronounced increase in lung parenchymal tissue and decrease of alveolar space was observed in old mice subjected to smoke from cigarettes containing higher doses of kaolin than in similarly treated young animals. Concomitant with the above, the lung macrophage population did not increase as markedly in response to smoke inhalation in old mice nor did it increase in as clear a dose-response fashion to kaolin as it did in young animals. Further, the degree of ultrastructural alteration of the phagocytes in the old mice suggested impaired cell function. Plate-like material resembling kaolin crystals was most conspicuous in lung macrophages of mice which inhaled largest amounts of kaolin. Manifestations of abnormal aggregates of lymphocytes and macrophages correlated with kaolin dose inhaled in old mice but not in young animals. The reported observations indicate that 1) kaolin gains access to lungs via cigarette smoke inhalation, 2) macrophages are important in maintaining pulmonary homeostasis and 3) the inorganic compound kaolin appears to impede macrophage function, resulting in potentiation of lung abnormalities.     

Modulation of phagocytic function in murine peritoneal macrophages by bombesin, gastrin-releasing peptide and neuromedin C.

Bombesin, as well as the two mammalian bombesin-like peptides gastrin-releasing peptide and neuromedin C, have been shown in this study to stimulate in vitro all steps of the phagocytic process in murine peritoneal macrophages: adherence to substrate, chemotaxis, ingestion of cells (Candida albicans) and inert particles (latex beads), and production of superoxide anion as measured by nitroblue tetrazolium reduction. A dose-response relationship was observed, with maximal stimulation of phagocytic process between 10(-12)M and 10(-9)M. Gastrin-releasing peptide (GRP) and neuromedin C caused a higher activation of adherence, chemotaxis and ingestion of C. albicans than bombesin. The three neuropeptides induced in murine macrophages a significant, but transient, increase of inositol 1,4,5-trisphosphate (IP3) levels at 60 seconds. On the contrary, these neuropeptides produced a rapid, transient and significant decrease of cAMP at 30 seconds. These results suggest that there are close relations between IP3 and cAMP messenger systems and the phagocytic process in murine peritoneal macrophages when these cells are incubated in the presence of bombesin, GRP or neuromedin C.     

Auditory Stress Induces Changes in Membrane Functions of Mouse Peritoneal Macrophages

Stressful events induce responses in the endocrine and immune systems. The authors analysed the influence of repetitive noise stress on peritoneal macrophage oxidative and phagocytic responses. Plasma corticosterone levels were also measured. Different groups of 6- to 8-week-old C57BL/6 male mice were exposed for 1 night ( n =14) and 3 nights ( n =21) to a sound stress of 110 dB in an audiogenic stress chamber. Control animals were submitted to a sham stress for 1 night ( n =13) and 3 nights ( n =17). A marked decrease was observed in the phagocytic response to yeast ( P =3×10⁻⁴) while a mild increase in the oxidative response stimulated by opsonized zymosan was noted only after the 3 night stress ( P =0.02). Corticosterone levels of control and stressed mice did not differ. These results indicate that the stress resulting from repetitive noise causes modifications in peritoneal macrophage activity, and that these changes are dependant on the duration of stress. These functional alterations seem more complex than a simple general suppression or activation.     

Changes with aging and physical exercise in ascorbic acid content and proliferative response of murine lymphocytes.

Ascorbic acid content and lymphoproliferative response to phytohemagglutinin were measured in lymphocytes from axillary nodes, spleen and thymus of young (15 +/- 2 weeks) and old (60 +/- 5 weeks) BALB/c mice. Ascorbic acid content in lymphocytes from spleen and thymus was found to be significantly higher and the lymphoproliferative response in the three immunocompetent organs significantly lower in old mice as compared to young mice. Moreover, young and old BALB/c mice were required to maintain a swimming activity until exhaustion (exhaustive exercise) or 90 min of swimming each day for a total of 20 days (continuous exercise). In both young and old mice the stress produced by exhaustive exercise and confirmed by the existence in serum of significantly increased levels of corticosterone compared to controls, caused a significant decrease in ascorbic acid content as well as in lymphoproliferative response. Continuous exercise, characterized by the presence in serum of significantly decreased levels of corticosterone compared to controls, produced the most significant decrease in ascorbic acid content from young and old murine lymphocytes. Moreover, this exercise resulted in a significant increase in lymphoproliferative response. Our results suggest that aging results in an increase in the ascorbic acid content of lymphocytes accompanied by a decline in the lymphoproliferative response in old BALB/c mice.     

小鼠腹腔巨噬细胞Fc受体的观察

本文对不同免疫水平的小鼠腹腔巨噬细胞作了 EA-花环试验。发现Fc受体功能在昆明杂交系小鼠比近交系C_(57)BL 的同年龄小鼠活跃,而在C_(57)BL系小鼠中,年青动物的Fc受体功能又较老年鼠强,从而证明小鼠腹腔巨噬细胞的Fc受体功能状态可随机体的免疫水平变化而发生改变,因此,对巨噬细胞 Fc受体的观察可作为衡量机体免疫水平的实验指标之一。 当小鼠腹腔巨噬细胞被厌氧棒状杆菌菌苗激活后,发现其 EA-花环形成百分率明显上升,而且吞噬活性也明显增强,尤其是在抗体调理吞噬反应中,还表现出单位细胞吞噬能力的显著提高,这说明菌苗激活的巨噬细胞可促进其表面 Fc 受体的功能,进而使巨噬细胞在调理吞噬反应中变得更为活跃。由此可见,提高巨噬细胞 Fc 受体的功能,对其功能的发挥具有积极意义。     

Stimulation of the phagocytic function of neutrophils in sedentary men after acute moderate exercise

Summary All the different stages of phagocytic function in blood polymorphonuclear neutrophils of sedentary (untrained) young men before, immediately after, and 15 min after being subjected to submaximal acute moderate exercise (50% maximal oxygen uptake) on a cycle ergometer were studied. No statistically significant differences were found in adherence or microbicide capacity againstCandida albicans immediately after physical exercise. However, spontaneous mobility, chemotaxis and attachment and phagocytosis ofCandida albicans at 15 min of incubation were significantly stimulated. Fifteen minutes after exercise spontaneous mobility, chemotaxis, and attachment ofCandida albicans had returned to basal values, while phagocytosis ofCandida albicans remained higher than basal values. One can, therefore, conclude that acute moderate exercise stimulates the phagocytic capacity of neutrophils in sedentary young men. In addition, no differences were found in the plasma adrenocorticotropic hormone concentration after exercise. However, immediately after exercise there was a decrease in the serum cortisol concentration, which had returned to basal 15 min later.     

Changes with aging in the modulation of macrophages by norepinephrine

The effect of aging on the norepinephrine (NE)-induced modulation of phagocytic and oxygen-dependent microbicidal processes of mouse peritoneal macrophages was studied. Phagocytosis of latex beads on culture plates and superoxide anion production was evaluated in young (12 weeks), adult (22 weeks), mature (48 weeks) and old (72 weeks) BALB/c mice after in vitro incubation with 10(-12), 10(-9), 10(-7), 10(-5) or 10(-3) M concentrations of NE. The results indicate that the phagocytic response to NE is quite similar in young and mature mice, with increased phagocytosis after incubation with 10(-7) and 10(-3) M, and decreased phagocytosis with 10(-5) M. Macrophages from adult mice increased their phagocytic capacity after incubation with the highest concentrations of NE (10(-5) and 10(-3) M) and macrophages from old animals only were stimulated with 10(-3) M. In addition, it was found that usually NE increased the extracellular superoxide anion production in the absence of phagocytosis in adult mice. No statistically significant changes were found in intracellular superoxide anion levels, but an increase was seen after phagocytosis in macrophages from adult, mature and old animals, especially after incubation with 10(-5) M. In conclusion, the results obtained indicate that the modulation of macrophages by NE does not only depend on the concentration of this neurotransmitter, but also on age.     

The effects of malnutrition on murine peritoneal macrophages

Differences were detected between peritoneal macrophages (both resident and elicited) from mice on a low protein diet and from normal animals. The concentration of resident peritoneal macrophages was lower in animals on low protein diets than in normal controls. Although total protein (and therefore cell mass) of resident macrophages from malnourished mice was increased, their contents of thiamine pyrophosphatase, succinate dehydrogenase, and non-specific esterase were disproportionately reduced. In addition they did not ingest as many glutaraldehyde-fixed sheep erythrocytes or attach to as many adherent C3b sensitized sheep red blood cells as those from normal animals, although reduction of nitroblue tetrazolium was unaffected. Initially (24 hr after thioglycollate), elicited macrophages from malnourished mice did not divide as frequently as those from normal mice but by 48 hr the differences were insignificant. The elicited macrophage possessed lower levels of total protein (indicating a reduced cell mass); the levels of acid phosphatase, thiamine pyrophosphatase, succinate dehydrogenase, and nonspecific esterase and nitroblue reducing activity were also proportionately reduced. They ingested fewer glutaraldehyde-fixed erythrocytes and reacted with fewer C3b sensitised sheep red blood cells than those from normal mice; ingestion of IgG-coated sheep erythrocytes, on the other hand, was somewhat increased. These abnormalities may influence adversely the efficiency of early phlogistic responses and favor the establishment of infection in malnourished animals.     

Ontogeny of macrophage-mediated protection against Listeria monocytogenes.

We investigated the ontogenic development of macrophage functions which are important in the expression of host defense against infection by Listeria monocytogenes. Macrophage functions, including accumulation in response to local stimuli, chemotaxis in vitro, and intracellular killing, as well as number of macrophages, were examined by using mice 1, 2, 3, 4, and 8 weeks old. The number of peritoneal macrophages was extremely low in younger mice even when their body weights were taken into consideration. Macrophage accumulation in response to infectious stimulus with viable listeria was poor in younger mice and showed an age-dependent development. In younger groups, chemotaxis in vitro was as immature as chemotaxis in vivo. In 1- and 2-week-old mice, macrophages did not show any intracellular killing activity against L. monocytogenes, but killing was observed in mice over 3 weeks of age. These functions developed in an age-dependent manner and reached the 8-week-old adult level after the mice were 4 weeks of age. In adult mice, these macrophage functions were shown to be enhanced after immunization with viable listeria; however, such an immunization-induced enhancement was very poor in the younger groups of mice. Protection judged by mortality and in vivo bacterial growth was weaker in the younger groups against both primary and secondary challenges. In vivo protection against L. monocytogenes seemed to develop in the same age-dependent manner as the development of macrophage functions. These results indicate that age-dependent immaturity of macrophage functions mainly comprises the age-dependent immaturity of protection against L. monocytogenes.     

Differential effects of osteopontin on the cytotoxic activity of macrophages from young and old mice.

Osteopontin (OPN) is a secreted phosphoprotein found in body fluids (e.g. plasma, urine, milk) and in mineralized tissues. Its expression is increased in many transformed cells and in normal cells exposed to various cytokines. When stimulated with the inflammatory mediators lipopolysaccharide and interferon-gamma, mouse macrophages secrete nitric oxide (NO) as a cytotoxic agent effective against microbial invaders and tumour cells. This report documents (1) that thioglycollate-elicited peritoneal macrophages, activated with the inflammatory mediators, produced less NO and exhibited reduced cytotoxicity towards target cells when they were obtained from old animals than when they were obtained from young animals; and (2) that OPN was able to inhibit both the induced NO synthesis and cytotoxicity, but more effectively in macrophages from the young animals than those from the old animals. This may be due to the observed higher level of OPN expression in macrophages from old animals.     

An impairment of phagocytic function is linked to a shorter life span in two strains of prematurely aging mice

In previous cross-sectional studies on Swiss mouse populations we have shown that at the same chronological age, animals that take longer to explore a simple T-maze (slow mice) are hyper-emotional and show an impairment of the immune system than those which quickly explore the maze (fast mice). Therefore, we have proposed that the slow mice are a model of prematurely aging mice (PAM). In the present work we have carried out a longitudinal study of age-dependent changes in key functions of phagocytic cells (peritoneal macrophages) such as phagocytosis and superoxide anion production in both male and female Swiss (outbred strain) and BALB/c (inbred strain) PAM and non-prematurely aging mice (NPAM). Gender differences were found showing the females better phagocytic and digestion capacities with concomitant longer life span. The PAM showed an impaired phagocytosis capacity and intracellular superoxide anion production as well as an increase of its extracellular production as compared to NPAM, which could be related to the shortened life span of those animals in both sexes and strains.     

Phagocytic responses of peritoneal macrophages and neutrophils are different in rats following prolonged exercise

OBJECTIVE:

To analyze the effects of exhausting long‐duration physical exercise (swimming) sessions of different durations and intensities on the number and phagocytic capacity of macrophages and neutrophils in sedentary rats.

INTRODUCTION:

Exercise intensity, duration and frequency are important factors in determining immune response to physical effort. Thus, the effects of exhausting long‐duration exercise are unclear.

METHODS:

Wistar rats were divided into two groups: an untreated group (macrophage study) and oyster glycogen‐treated rats (neutrophil study). In each group, the animals were subdivided into five groups (10 rats per group): unexercised controls, an unadapted low‐intensity exercise group, an unadapted moderate‐intensity exercise group, a preadapted low‐intensity exercise group and a preadapted moderate‐intensity exercise group. All exercises were performed to exhaustion, and preadaptation consisted of 5, 15, 30 and 45 min sessions.

RESULTS:

Macrophage study: the number of peritoneal macrophages significantly decreased (9.22 ± 1.78 × 10⁶) after unadapted exercise but increased (21.50 ± 0.63 × 10⁶) after preadapted low‐intensity exercise, with no changes in the moderate‐intensity exercise group. Phagocytic capacity, however, increased by more than 80% in all exercise groups (low/moderate, unadapted/preadapted). Neutrophil study: the number of peritoneal neutrophils significantly decreased after unadapted (29.20 ± 3.34 × 10⁶) and preadapted (50.00 ± 3.53 × 10⁶) low‐intensity exercise but increased after unadapted (127.60 ± 5.14 × 10⁶) and preadapted (221.80 ± 14.85 × 10⁶) moderate exercise. Neutrophil phagocytic capacity decreased by 63% after unadapted moderate exercise but increased by 90% after corresponding preadapted sessions, with no changes in the low‐intensity exercise groups.

CONCLUSION:

Neutrophils and macrophages of sedentary rats respond differently to exercise‐induced stress. Adaptation sessions reduce exercise‐induced stress on the immune system.     

Functions of peritoneal macrophages during adaptation to dosed heat factor

Experiments on mice were made to study functional activity of peritoneal macrophages in adaptation of the animals to dosed heat factor by a phagocytic ability of the cells, chemiluminescence (CL), activity of acid phosphatase and phagocyte production of lymphocyte-activating factors (LAF). Daily overheating of mice (20 min, 43-44 degrees C) for 5, 10, 20 and 30 days resulted in suppression of macrophage function. The deepest depression of phagocyte functional activity was observed on overheating day 10-20. This was evident from subnormal phagocytic ability of the cells, suppression of CL response and activity of acid macrophage phosphatase, low production of LAF. Thermotraining led to recovery of macrophage function as the studied parameters returned to control 40 days after overheating onset.     

Effect of L‐Arginine on Age‐Related Changes in Macrophage Phagocytic Activity

Aging is associated with decline in the functioning of immune cells and reductions in serum L‐arginine and excretion of nitric oxide metabolites. Studies have shown that L‐arginine plays an important role in many physiological, biological and immunological processes. The present study was performed to determine if treatment with L‐arginine could prevent age‐related changes in phagocytic function of peritoneal macrophages. The effects of L‐arginine on phagocytic activity of peritoneal macrophages were compared between young and middle‐aged rats. Studies were performed in four groups of rats for 8 weeks: group 1 (3 month‐old) received physiological saline; group 2 (3 month‐old) received L‐arginine (160 mg/kg/day); group 3 (12 month‐old) received physiological saline; group 4 (12 month‐old) received L‐arginine (160 mg/kg/day). There were no significant differences in percentage of cells which were phagocytized. However, the phagocytosis of activated charcoal by peritoneal macrophages reduced with age. Thus, the phagocytic index was lower in macrophages of middle‐aged rats. L‐arginine treatment increased phagocytosis by peritoneal macrophages of both young and middle‐aged rats. L‐arginine‐induced augmentation in phagocytosis by macrophages were much higher in the middle‐aged rats compared with young rats. In summary, we found that L‐arginine prevented the age‐related reduction in phagocytic capability of peritoneal macrophages.