L. F. B. P. Costa Rosa

Creatine supplementation reduces plasma levels of pro-inflammatory cytokines and PGE2 after a half-ironman competition.

Summary.Objective. The effect of creatine supplementation upon plasma levels of pro-inflammatory cytokines: Interleukin (IL) 1β and IL-6, Tumor Necrosis Factor α (TNFα), and Interferon α (INFα) and Prostaglandin E2 (PGE2) after a half-ironman competition were investigated. Methods. Eleven triathletes, each with at least three years experience of participation in this sport were randomly divided between the control and experimental groups. During 5 days prior to competition, the control group (n = 6) was supplemented with carbohydrate (20 g · d−1) whereas the experimental group (n = 5) received creatine (20 g · d−1) in a double-blind trial. Blood samples were collected 48 h before and 24 and 48 h after competition and were used for the measurement of cytokines and PGE2. Results. Forty-eight hours prior to competition there was no difference between groups in the plasma concentrations (pg · ml−1, mean ± SEM) of IL-6 (7.08 ± 0.63), TNFα (76.50 ± 5.60), INFα (18.32 ± 1.20), IL-1β (23.42 ± 5.52), and PGE2 (39.71 ± 3.8). Twenty-four and 48 h after competition plasma levels of TNFα, INFα, IL-1β and PGE2 were significantly increased (P < 0.05) in both groups. However, the increases in these were markedly reduced following creatine supplementation. An increase in plasma IL-6 was observed only after 24 h and, in this case, there was no difference between the two groups. Conclusion. Creatine supplementation before a long distance triathlon competition may reduce the inflammatory response induced by this form of strenuous of exercise.

Effect of a moderate intensity exercise training protocol on the metabolism of macrophages and lymphocytes of tumour‐bearing rats

It is commonly accepted that moderate intensity exercise is beneficial to the immune system. We tested the influence of a moderate intensity training protocol (8 weeks) upon immune system function in Wistar tumour‐bearing (TB) rats. The metabolism of glucose and glutamine in lymphocytes and macrophages was assessed, together with some functional parameters (hydrogen peroxide production and lymphocyte proliferative response). These substrates were chosen since they represent the most important energetic and synthetic metabolites for these cellular types. The training protocol caused a decrease of 17·4 per cent in the production of H2O2 by macrophages, as well as a decrease in glucose consumption (25 per cent) and lactate production (47·1 per cent), and an increase in the production of labelled CO2 from the oxidation of [U‐14C]‐glucose, in TB rats. The training protocol was also able to induce changes in the maximal activity of some key enzymes in the metabolism of glucose and glutamine, a reduction of hexokinase (68·8 per cent) activity and an increase in the activity of citrate synthase (10·1 per cent) in TB rats. The training protocol increased the proliferative response of lymphocytes cultivated in the absence of mitogens (75 per cent), of those cultivated in the presence of ConA (38·2 per cent) and in the presence of LPS (45·0 per cent). These cells also showed an increase in the maximal activity of some key enzymes of the glycolytic and glutaminolytic pathways. Our data demonstrated that the training protocol was able to induce an increase in aerobic utilisation of both substrates in lymphocytes and macrophages. The training protocol was also able to prevent several changes in glucose and glutamine metabolism that are normally present in sedentary TB rats. These changes in immune cell metabolism induced by the training protocol were able to increase TB rat survival. Copyright

Superoxide dismutase, catalase, and glutathione peroxidase activities in muscle and lymphoid organs of sedentary and exercise-trained rats

The effect of swimming-training upon the activities of the enzymes involved in the generation of reducing-equivalents (citrate synthase-mitochondria and glucose-6-phosphate dehydrogenase-cytosol) and of antioxidant enzymes (CuZn- and Mn-SOD, catalase and glutathione peroxidase) in the lymphoid organs (thymus, mesenteric lymph nodes and spleen) was examined. The skeletal muscles (soleus-red and gastrocnemius-white) were also studied. Although our data suggest an apparently random, organ-specific change in enzymatic activity, some interesting trends can be observed. Firstly, the increased citrate synthase and Mn-SOD activities observed in red, but not in white muscle, corroborate the well-known effect of endurance exercise-training on mitochondrial oxidative metabolism. Secondly, there was an inverse relationship between TBARs-monitored lipoperoxidation and glutathione peroxidase activity in all tissues studied, what is in accordance with the previous findings showing that such enzyme exerts the fine control of intracellular lipoperoxide concentration. Except in the case of the spleen, there was a trend for elevated glucose-6-phosphate dehydrogenase activity, coadjuvant of glutathione peroxidase in the antioxidant response to physical exercise in all tissues. Thirdly, Mn-SOD and catalase were conspicuously associated to oxidative stress in the thymus, while glutathione and catalase could be linked to this parameter in the spleen. Fourthly, the lymph nodes seem to be more dependent on the glucose-6-phosphate dehydrogenase/glutathione peroxidase pair for protection against damage promoted by physical exercise. Mn-SOD and catalase activities were lower in the lymph nodes after swimming training.(ABSTRACT TRUNCATED AT 250 WORDS)

Tryptophan consumption and indoleamines production by peritoneal cavity macrophages.

Melatonin has been shown to regulate several immune functions, and some authors showed that leukocytes are also able to produce the indolamine. In fact, it seems to take part in some immunoregulatory axis, including that related to interferon (IFN) production. So, we evaluated the rate of tryptophan consumption and melatonin and serotonin production in peritoneal cavity‐isolated macrophages and the effect of IFN‐α and ‐γ, lipopolysaccharide (LPS), and phorbol myristate acetate (PMA) on such parameters. Our results indicate that macrophages obtained from the peritoneal cavity of normal rats when incubated with tryptophan show an increase in arylalkylamine N‐acetyltransferase activity that corresponds to an increased melatonin production, as determined in the incubation medium. This process is regulated by IFN‐α and ‐γ, PMA, LPS, and the serum from tumor‐bearing rats, opening the possibility of speculation about different immunoregulatory loops acting through the balance of melatonin/serotonin production by such cells.

THE EFFECT OF ADRENALINE AND WALKER-256 TUMOUR-INDUCED CACHEXIA UPON KUPFFER CELL METABOLISM

Kupffer cells (KC), the liver macrophages, are able to produce PGE2, which is involved in immune suppression and in the aggravation of cancer cachexia due to interference with lipid metabolism in the liver. Since tumour‐bearing (TB) rats present high plasma epinephrine levels, and this hormone is able to affect macrophage metabolism and function, we have assessed the effect of epinephrine (5 nm) upon Kupffer cell PGE2 production. Epinephrine induced increased production of PGE2 both by control (3·5‐fold) and TB rats (27 per cent) KC, an effect blocked by propranolol. Enhancement of cAMP content in the cells by addition of isoproterenol (0·1 μm) to the incubations, however, failed to induce the same response in the cells. Nevertheless, when phenylephrine (1 μm) was added to the incubation, a similar pattern of PGE2 production to that observed for epinephrine was found for control and TB rat KC. We propose that the effect of epinephrine upon KC PGE2 production is mediated by α‐adrenergic receptors and that Ca2+ is involved in the response, since increasing concentrations of the ion added to the incubation medium (0·25, 0·5 and 1·0 mm) enhanced the eicosanoid production, while EDTA abolished the response. Copyright

EFFECT OF ADRENALINE ON LYMPHOCYTE METABOLISM AND FUNCTION. A MECHANISM INVOLVING CAMP AND HYDROGEN PEROXIDE

This study examined the effect of adrenaline on lymphocyte metabolism and function. The following parameters were addressed: cell proliferation, glucose and glutamine metabolism as indicated by the measurement of enzyme activities, the utilization of metabolites and production and oxidation of substrates. We also evaluated the involvement of beta-receptors in this response as well as the possible effect of cAMP and hydrogen peroxide in the process of lymphocyte activation by adrenaline. The results indicated that adrenaline is able to induce metabolic changes in lymphocytes that are related to enhanced proliferative capacity, but under physiological conditions fails to initiate the process, the catecholamine could, increase cell proliferation via increased production of H2O2 by macrophages, since this reactive oxygen intermediate can act as a trigger for lymphocyte activation. The results also showed that distinct populations of lymphocytes present different responses to adrenaline activation, as demonstrated by cells obtained from the same site but exposed to different mitogens such as LPS and ConA.This study examined the effect of adrenaline on lymphocyte metabolism and function. The following parameters were addressed: cell proliferation, glucose and glutamine metabolism as indicated by the measurement of enzyme activities, the utilization of metabolites and production and oxidation of substrates. We also evaluated the involvement of beta‐receptors in this response as well as the possible effect of cAMP and hydrogen peroxide in the process of lymphocyte activation by adrenaline. The results indicated that adrenaline is able to induce metabolic changes in lymphocytes that are related to enhanced proliferative capacity, but under physiological conditions fails to initiate the process, the catecholamine could, increase cell proliferation via increased production of H2O2 by macrophages, since this reactive oxygen intermediate can act as a trigger for lymphocyte activation. The results also showed that distinct populations of lymphocytes present different responses to adrenaline activation, as demonstrated by cells obtained from the same site but exposed to different mitogens such as LPS and ConA.

Metabolic and functional changes in lymphocytes and macrophages as induced by ageing.

Key enzyme activities of glycolysis, pentosephosphate pathway, Krebs cycle, and glutaminolysis were measured in lymphocytes and macrophages of 3- and 15-month-old rats from the control, thioglycollate-injected, and Walker 256 tumor-implanted groups. The percentage of phagocytosis, phagocytic index, and production of H2O2 in macrophages and the rates of [2-14C]-thymidine and [5-3H]-uridine incorporation in cultured lymphocytes were also determined. The results indicate that the percentage of phagocytosis was not affected but the phagocytic index increased by twofold as a consequence of ageing, whereas the production of H2O2 reduced. The rates of both [2-14C]-thymidine and [5-3H]-uridine incorporation in lymphocytes from aged rats were lower as compared to those of mature animals in the three groups. Taken as a whole, the results of enzyme activities suggest that ageing may reduce the capacity for glucose utilization in lymphocytes and macrophages under the three conditions. Lymphocyte and macrophage glutamine metabolism was not markedly affected by ageing. Therefore, an impaired glucose metabolism during ageing may be one important mechanism for the alteration in lymphocyte proliferation and macrophage phagocytosis observed and also for the modification of the response to inflammatory and tumor challenges.

Antioxidant enzyme activities in the lymphoid organs and muscles of rats fed fatty acids-rich diets subjected to prolonged physical exercise-training.

Rats weighing 45-50 g were fed 3 diets for 8 wk: a balanced control diet (CD) consisting of 4% fat (polyunsaturated/saturated fatty acids [P/S] ratio 2.9/1) and two fat-rich diets: polyunsaturated (UD)--P/S 7.6/1 and saturated (SD) P/S 0.3/1. After 8 wk feeding on the respective diets, rats were subjected to swimming for 90 min at 30 degrees C daily, 5 d/wk for 8 wk. At the end of this period, the rats were killed and the lymphoid organs (LO--thymus, spleen, and mesenteric lymph nodes) and muscles (soleus and gastrocnemius) removed for the measurement of TBARs (Thiobarbituric Acid Reactant Substances) content and of the activities of antioxidant enzymes (CuZn- and Mn-Superoxide dismutase--SOD--, catalase, and glutathione peroxidase). To evaluate the changes in the sites of generation of reducing equivalents involved in the formation of free radicals, the activities of citrate synthase and glucose-6-phosphate dehydrogenase were measured. The exercise-training clearly modified the enzyme activities and TBARs content of the lymphoid organs and skeletal muscles, but this effect was dependent upon the diet given to the rats. However, fatty acid rich diets had presented a more pronounced effect on the studied aspects than did physical activity. Although one could expect a summatory effect of polyunsaturated fatty acid-rich diet and exercise-training, swimming increased the activities of CuZn- and Mn-SOD in almost all tissues from the elevated level promoted by fat-rich diets.

The effect of N-3 PUFA rich diet upon macrophage and lymphocyte metabolism and function.

A large body of evidence from experimental studies has documented that n‐3 fatty acids can modify a variety of cell functions and disease states. As lymphocytes and macrophages are important cells for the development of the inflammatory and non‐inflammatory immune response and are known to utilize high rates of glucose and glutamine, we have evaluated the effect of n‐3 PUFA rich diet on the metabolisation of glucose and glutamine these cells, as well as the effect of one such diet upon the proliferative response of lymphocytes and the phagocytic capacity and hydrogen peroxide production by macrophages. The diet provoked an increase in the flux of glucose through the Krebs cycle in macrophages as well as a reduction in G6PDh and glutaminase activity in these cells. Lymphocytes from n‐3 PUFA rich diet‐fed rats showed a reduction in glucose and glutamine decarboxylation. Taken together the data show that, at least in part, the functional changes observed in macrophages and lymphocytes from n‐3 PUFA‐rich diet fed rats are related to the effect of this diet upon glucose and glutamine metabolism, leading to immunosupression

Effect of doxorubicin on cytokine production by lymphocytes and the Th1/Th2 balance

Doxorubicin (DOXO) is a potent chemotherapeutic used mainly against solid tumours; however, it has several side effects that can limit its clinical use. On the other hand, the effect of DOXO upon lymphocyte function is controversial. Some studies demonstrate that DOXO administration in vitro suppresses T-cell activation, while the cellular function has been shown to increase in vitro. The objective of this study was to investigate the effect of DOXO on lymphocyte cytokine production in rats. The animals were divided into: SAL (control, n=10) and DOX (DOXO treated, n=10). The DOX group received only one DOXO dose at 15 kg Kg(-1) by intraperitoneal injection. Forty-eight hours after DOXO administration, the animals were killed by decapitation. IL-2 production was significantly enhanced (p<0.05) in lymphocytes from rats treated with DOXO (169.17 ± 21.73 pg mL 10(5) cell) as compared to cells from SAL (45.92 ± 10.53 pg mL 10(5) cell). The administration of DOXO decreased (<0.05) IL-4 production in the DOXO group (29.85 ± 13.09 pg mL 10(5)cell) relative to the SAL group (75.08 ± 15.31 pg mL 10(5)cell). The IL-2/IL-4 ratio was higher (<0.05) in the DOX group (5.99 ± 0.44), as compared to SAL group (0.73 ± 0.12). In conclusion, our results suggest that a dose of DOXO promotes an alteration in the Th1/Th2 balance, promoting a shift towards a Th1-dominant cytokine response.