Effect of fish oil supplementation for 2 generations on changes in macrophage function induced by Walker 256 cancer cachexia in rats

Crotoxin modulates metabolism and secretory activity of peritoneal macrophages from Walker 256 tumor-bearing rats

Crotoxin (CTX), the major toxin of Crotalus durissus terrificus snake venom, induces an inhibitory effect on tumor development and modulates the functions of macrophages (MØs), which play a key role as a defense mechanism against tumor growth. In early tumor progression stage, MØs are avidly phagocytic (inflammatory cell), releasing reactive nitrogen intermediates-RNI/ROI and cytokines TNF-α, IL-1β, and IL-6. However, when the tumor has been developed, tumor-associated MØ (angiogenic cell) presents a decrease in the mentioned activities. We reported that CTX stimulates H₂O₂ release, NO production and secretion of cytokines by peritoneal MØs obtained from non-tumor-bearing rats. Considering that the mentioned mediators control tumor growth, it is mandatory to investigate whether CTX stimulates the production of these mediators by MØs obtained from tumor-bearing animals. The aim of this work was then to evaluate the CTX effect on metabolism and functions of peritoneal MØs obtained from Walker 256 tumor-bearing rats. For this purpose, male Wistar rats were subcutaneously inoculated in the right flank with 1 mL sterile suspension of 2 × 10⁷ Walker 256 tumor cells. CTX (18 μg per animal) was subcutaneously administered in two protocols: a) on the 1st day of tumor cell injection and b) on the 4th day of tumor cell inoculation. In both protocols, MØs were obtaining on the 14th day of tumor cell inoculation to evaluate the release of H₂O_2, NO, and pro-inflammatory cytokines (IL-1β, TNFα, and IL-6); maximal activity of hexokinase, glucose-6-phosphate dehydrogenase, citrate synthase, and ¹⁴CO₂ production from [U-¹⁴C]-glucose and [U-¹⁴C]-glutamine. The treatment with CTX stimulated the release of NO, H₂O₂, and cytokines, and glucose and glutamine metabolism. Metabolic and functional changes induced by CTX were accompanied by a decrease of tumor growth as indicated by tumor fresh weight and diameter. These results indicate CTX not only as a scientific tool to investigate changes in metabolism and functions of peritoneal MØs but also for a better understanding of the mechanisms involved in tumor growth.

Fish Oil Diet during Pre-mating, Gestation, and Lactation in Adult Offspring Rats on Cancer Cachexia Prevention

SCOPE

Nutritional supplementation of the maternal diet can modify the cancer susceptibility in adult offspring. Therefore, the authors evaluate the effects of a fish-oil diet administered to a long-term, during pre-mating, gestation, and lactation, in reducing cancer-cachexia damages in adult Walker-256 tumor-bearing offspring.

METHODS AND RESULTS

Female rats receive control or fish oil diet during pre-mating, gestation, and lactation. After weaning, male offspring are fed the control diet until adulthood and distributed in (C) control adult-offspring; (W) adult tumor-bearing offspring; (OC) adult-offspring of maternal fish oil diet; (WOC) adult tumor-bearing offspring of maternal fish oil diet groups. Fat body mass is preserved, muscle expression of mechanistic target of rapamicin (mTOR) and eukariotic binding protein of eukariotic factor 4E (4E-BP1) is modified, being associated with lower 20S proteasome protein expression, and the liver alanine aminotransferase (ALT) enzyme content maintained in the WOC group. Also, the OC group shows reduced triglyceridemia.

CONCLUSION

In this experimental model of cachexia, the long-term maternal supplementation is a positive strategy to improve liver function and lipid metabolism, as well as to modify muscle proteins expression in the mTOR pathway and also reduce the 20S muscle proteasome protein, without altering the tumor development and muscle wasting in adult tumor-bearing offspring.

Modulatory Effect of Dietary Polyunsaturated Fatty Acids on Immunity, Represented by Phagocytic Activity

Lately, dietary polyunsaturated fatty acids (PUFAs) have shown substantial importance in human and animal nutrition, especially those of the n-3 group. Development and optimal functioning of the immune system are directed affected by diet. These dietary fatty acids have an important impact on the health and immune competence of various species including human beings. They are essential for the modulation of immune responses in health and disease. Fatty acid composition of immune cells can be modulated by the action of dietary fats and the outcomes in the composition can produce functional effects on reactivity and functioning of immune cells in a short period. There are several mechanisms involved in impacting dietary fatty acids on immune function; however, lipid mediator synthesis from PUFAs is of great importance in terms of inflammation. The objectives of this article are reviewing studies on the impact of PUFA in the diet on phagocytosis of chickens, murine, rats, ruminants, and humans. It also sheds light on the possible mechanism by which this immunomodulation occurs.

Nutrition and Cancercapsaicin Treatment Reduces Tumor Growth, Tumor Cell Proliferation Ex Vivo and Partially Reverses Cancer Cachexia in Walker 256 Tumor-Bearing Rats

Capsaicin (trans-8-methyl-n-vanillyl-6-nonenamide) is the main pungent component found in hot peppers.

AIM

In this study, we investigated the effect of capsaicin treatment on tumor growth and the metabolic indicators of cachexia in Walker 256 tumor-bearing rats.

METHODS

Male Wistar rats were inoculated subcutaneously in the right flank with 1 ml of a sterile suspension of 3 × 10⁷ Walker tumor cells. The treated groups received capsaicin intraperitoneal 5 mg/kg body weight for 13 days.

RESULTS

The tumor weight on Day 14 in the non-treated group was 18 g. The rats also had a body weight loss, hypoglycemia, hyperlactacidemia, hypertriacylglycerolemia, and a depletion in glycogen storage. Treatment with capsaicin decreased tumor growth by 49% and a reversal of triacylglycerol serum. We also found a 32% reduction in tumor cell proliferation ex vivo. Lactate serum concentrations and body weight were lower but did not reach control levels.

CONCLUSION

The treatment with capsaicin reduces tumor growth and cellular proliferation along with increased apoptosis and partial cachexia reversal.

Metabolic disturbances due to a high-fat diet in a non-insulin-resistant animal model

Objective:

Shift workers have metabolic changes more often than day workers. It is also known that night workers prefer foods high in saturated fat. Such data suggest that shift workers are prone to cardiovascular disease. Therefore, the objective of this study was to propose an animal model to test the effect of high-fat diet (HFD) based on shift workers' diet.

Methods:

This is an experimental study with 20 Wistar rats. Ten rats were allocated to the control group (CG) and were fed standard diet. Ten rats were allocated to the experimental group (EG) and were fed HFD (45% fat). Serum triglycerides (TG), glucose and high-density lipoprotein-cholesterol (HDL-cho) were measured 5, 10 and 15 weeks after the beginning of the study. The amount of visceral adipose tissue (VAT) was determined. Body weight was assessed weekly, and food and water intake were measured daily. Student's t-test was used for independent samples, and P<0.05 was considered significant.

Results:

After 15 weeks of intervention, the EG showed increased serum levels of TG (P=0.001) and glucose (P<0.001) and decreased HDL-cho (P<0.001) when compared with the CG. The EG showed increased VAT (P=0.005) and liver weight (P=0.01). Food intake and water intake were higher in the CG (P<0.001 and P<0.001, respectively), whereas energy intake showed no difference (P=0.48). No difference was found in the weight of adrenal glands (P=0.07) and body weight (P=0.63).

Conclusions:

The experimental diet was effective to show changes in the serum levels of glucose, TG and HDL-cho and visceral fat in spite of no change in body weight in 15 weeks.

Omega-3 supplementation improves pancreatic islet redox status: in vivo and in vitro studies

OBJECTIVES

The aim of the study was to evaluate the potential changes induced by fish oil (FO) supplementation on the redox status of pancreatic islets from healthy rats. To test whether these effects were due to eicosapentaenoic acid and docosahexaenoic acid (ω-3), in vitro experiments were performed.

METHODS

Rats were supplemented with FO, and pancreatic islets were obtained. Islets were also treated in vitro with palmitate (P) or eicosapentaenoic acid + docosahexaenoic acid (ω-3). Insulin secretion (GSIS), glucose oxidation, protein expression, and superoxide content were analyzed.

RESULTS

The FO group showed a reduction in superoxide content. Moreover, FO reduced the expression of NAD(P)H oxidase subunits and increased superoxide dismutase, without altering β-cell function. Palmitate increased β-cell reactive oxygen species (ROS) production, apoptosis, and impaired GSIS. Under these conditions, ω-3 triggered a parallel reduction in ROS production and β-cell apoptosis induced by P and protected against the impairment in GSIS. There was no difference in mitochondrial ROS production.

CONCLUSIONS

Our results show that ω-3 protect pancreatic islets from alterations induced by P. In vivo FO supplementation modulates the redox state of pancreatic β-cell. Considering that in vitro effects do not involve mitochondrial superoxide production, we can speculate that this protection might involve NAD(P)H oxidase activity.

Exercício de força associado a óleo de peixe reduzem massa tumoral e caquexia em ratos

OBJETIVO: Investigar o efeito do treinamento de salto associado à suplementação com óleo de peixe (1g/kg peso corporal/dia) em ratos portadores do tumor de Walker 256, sobre parâmetros bioquímicos de caquexia e crescimento tumoral.MÉTODOS: Oitenta Ratos foram divididos em sedentário sem ou com tumor (S ou SW), exercitado (EX ou EXW), suplementado com óleo de peixe (SO ou SWO) e suplementado e exercitado (EXO ou EXWO). Sessões de treinamento de salto consistiram de 10 séries com duração de 30 segundos e intervalo de 1 minuto entre cada série. Após seis semanas de treinamento, células do tumor de Walker 256 foram inoculadas e após 15 dias os animais foram mortos.RESULTADOS: O peso médio do tumor no grupo SW foi de 25,32 g, p<0,05 vs. ao dos SWO, EXW e EXWO (~11 g). O grupo SW apresentou hipoglicemia, hiperlactatemia, hipertriacilglicerolemia e perda de peso (-7,52±3,19g), caracterizando estado caquético. Suplementação com óleo de peixe (SWO), exercício (EXW) e associação de ambos (EXWO) impediram a instalação da caquexia (p<0,05 vs. SW). No grupo SWO, EXW e suas associações (EXWO) promoveram ganho de peso (p<0,05 vs. SW), mas inferior ao da suplementação isolada (p<0,05 vs. SWO). A proliferação celular in vitro das células tumorais foi menor no grupo SWO (p<0,05 vs. SW) e o exercício reduziu ainda mais (p<0,05 vs. SW e SWO), não havendo incremento quando se associaram ambas as terapias. Lipoperoxidação (p<0,05) foi maior nos SWO, EXW, EXWO vs. S. A expressão de Bcl-2 foi menor também nestes grupos vs. SW.CONCLUSÕES: O treinamento de força e a suplementação com óleo de peixe foram eficazes em evitar a caquexia e induzir a redução do crescimento tumoral, da proliferação tumoral e expressão de Bcl-2, mas a associação de ambos não promoveu efeito aditivo.

Antitumor and anti-cachectic effects of shark liver oil and fish oil: comparison between independent or associative chronic supplementation in Walker 256 tumor-bearing rats

BACKGROUND

Shark liver oil (SLOil) and fish oil (FOil), which are respectively rich in alkylglycerols (AKGs) and n-3 polyunsaturated fatty acids (PUFAs), are able to reduce the growth of some tumors and the burden of cachexia. It is known that FOil is able to reduce proliferation rate and increase apoptotic cells and lipid peroxidation of tumor cells efficiently. However, there are few reports revealing the influence of SLOil on these parameters. In the current study, effects of FOil chronic supplementation on tumor growth and cachexia were taken as reference to compare the results obtained with SLOil supplementation. Also, we evaluated if the association of SLOil and FOil was able to promote additive effects.

METHODS

Weanling male Wistar rats were divided into 4 groups: fed regular chow (C), supplemented (1 g/kg body weight) with SLOil (CSLO), FOil (CFO) and both (CSLO + FO). After 8 weeks half of each group was inoculated with Walker 256 cells originating new groups (W, WSLO, WFO and WSLO + FO). Biochemical parameters of cachexia, tumor weight, hydroperoxide content, proliferation rate and percentage of apoptotic tumor cells were analysed. Fatty acids and AKG composition of tumor and oils were obtained by high performance liquid chromatography and gas chromatography - mass spectrometry, respectively. Statistical analysis was performed by unpaired t-test and one-way ANOVA followed by a post hoc Tukey test.

RESULTS

Fourteen days after inoculation, SLOil was able to restore cachexia parameters to control levels, similarly to FOil. WSLO rats presented significantly lower tumor weight (40%), greater tumor cell apoptosis (~3-fold), decreased tumor cell proliferation (35%), and higher tumor content of lipid hydroperoxides (40%) than observed in W rats, but FOil showed more potent effects. Supplementation with SLOil + FOil did not promote additive effects. Additionally, chromatographic results suggested a potential incorporation competition between the n-3 fatty acids and the AKGs in the tumor cells' membranes.

CONCLUSIONS

SLOil is another marine source of lipids with similar FOil anti-cachectic capacity. Furthermore, despite being less potent than FOil, SLOil presented significant in vivo antitumor effects. These results suggest that the chronic supplementation with SLOil may be adjuvant of the anti-cancer therapy.

Fish oil supplementation for two generations increases insulin sensitivity in rats

We investigated the effect of fish oil supplementation for two consecutive generations on insulin sensitivity in rats. After the nursing period (21 days), female rats from the same prole were divided into two groups: (a) control group and (b) fish oil group. Female rats were supplemented with water (control) or fish oil at 1 g/kg body weight as a single bolus for 3 months. After this period, female rats were mated with male Wistar rats fed on a balanced chow diet (not supplemented). Female rats continued to receive supplementation throughout gestation and lactation periods. The same treatment was performed for the next two generations (G1 and G2). At 75 days of age, male offspring from G1 and G2 generations from both groups were used in the experiments. G1 rats did not present any difference with control rats. However, G2 rats presented reduction in glycemia and lipidemia and improvement in in vivo insulin sensitivity (model assessment of insulin resistance, insulin tolerance test) as well as in vitro insulin sensitivity in soleus muscle (glucose uptake and metabolism). This effect was associated with increased insulin-stimulated p38 MAP kinase phosphorylation and lower n-6/n-3 fatty acid ratio, but not with activation of proteins from insulin signaling (IR, IRS-1 and Akt). Global DNA methylation was decreased in liver but not in soleus muscle. These results suggest that long-term fish oil supplementation improves insulin sensitivity in association with increased insulin-stimulated p38 activation and decreased n-6:n-3 ratio in skeletal muscle and decreased global DNA methylation in liver.

Walker-256 tumor growth is inhibited by the independent or associative chronic ingestion of shark liver and fish oil: a response linked by the increment of peritoneal macrophages nitrite production in Wistar rats

Fish oil (FO) is widely known by its capacity to positively modulate immune parameters and decrease the growth of some tumors. Despite the enormous number of studies addressing the effects of FO, there are few reports showing similar results using other marine sources of lipid compounds with biologic importance. This study aimed to compare the effects of shark liver oil (SLO), which is a source of omega-3 fatty acids and alkylglycerols, with those obtained with FO administration, or the association of both, on tumor growth and the innate immune system in Walker-256 tumor-bearing rats. Beginning at 21 days of age, Wistar rats were fed regular chow and/or FO and/or SLO supplement (1 g/kg body weight per day) for 14 weeks. Walker-256 tumor cells were inoculated on the 90th day. As expected, 14 days after inoculation, rats fed with FO presented tumor weights that were 50% lower than the control tumors (P < .05). The association of both FO and SLO and ingestion of SLO alone also reached the same reduction level. Except for adhesion, all macrophage parameters assayed were 200% higher in rats fed with FO and those supplemented with both FO and SLO compared with control rats. Only reactive nitrogen species production was increased by SLO. These results suggest that SLO might also have indirect antitumor properties. Conversely, there were no additive effects when SLO was administered with FO. Therefore, SLO is another marine compound with in vivo antitumor effects, but its action mechanisms seem not to be related to major modifications on macrophage function.

Effect of fish oil supplementation for two generations on changes of lymphocyte function induced by Walker 256 cancer cachexia in rats

Fish oil supplementation has been shown to improve the cachectic state of tumor-bearing animals and humans. Our previous study showed that fish oil supplementation (1 g per kg body weight per day) for 2 generations had anticancer and anticachetic effects in Walker 256 tumor-bearing rats as demonstrated by reduced tumor growth and body weight loss and increased food intake and survival. In this study, the effect of fish oil supplementation for 2 generations on membrane integrity, proliferation capacity, and CD4/CD8 ratio of lymphocytes isolated from mesenteric lymph nodes, spleen, and thymus of Walker 256 tumor-bearing animals was investigated. We also determined fish oil effect on plasma concentration and ex vivo production of cytokines [tumor necrosis factor-alpha (TNF-alpha), interferon-gamma (IFN-gamma), interleukin-4 (IL-4), IL-6, and IL-10]. Lymphocytes from thymus of tumor-bearing rats presented lower viability, but this change was abolished by fish oil supplementation. Tumor growth increased proliferation of lymphocytes from all lymphoid organs, and fish oil supplementation abolished this effect. Ex vivo production of TNF-alpha and IL-6 was reduced in supplemented animals, but IL-4 and IL-10 secretion was stimulated in both nontumor and tumor-bearing rats. IL-10 and IFN-gamma plasma levels was also decreased in supplemented animals. These results suggest that the anticachetic effects of fish oil supplementation for a long period of time (2 generations) in Walker 256 tumor-bearing rats may be associated to a decrease in lymphocyte function as demonstrated by reduced viability, proliferation capacity, and cytokine production.

Glucose metabolism by lymphocytes, macrophages, and tumor cells from Walker 256 tumor-bearing rats supplemented with fish oil for one generation

Here we investigated the effect of lifelong supplementation of the diet with coconut fat (CO, rich in saturated fatty acids) or fish oil (FO, rich in n-3 polyunsaturated fatty acids) on tumor growth and lactate production from glucose in Walker 256 tumor cells, peritoneal macrophages, spleen, and gut-associated lymphocytes. Female Wistar rats were supplemented with CO or FO prior to mating and then throughout pregnancy and gestation and then the male offspring were supplemented from weaning until 90 days of age. Then they were inoculated subcutaneously with Walker 256 tumor cells. Tumor weight at 14 days in control rats (those fed standard chow) and CO supplemented was approximately 30 g. Supplementation of the diet with FO significantly reduced tumor growth by 76%. Lactate production (nmol h(-1) mg(-1) protein) from glucose by Walker 256 cells in the group fed regular chow (W) was 381.8 +/- 14.9. Supplementation with coconut fat (WCO) caused a significant reduction in lactate production by 1.6-fold and with fish oil (WFO) by 3.8-fold. Spleen lymphocytes obtained from W and WCO groups had markedly increased lactate production (553 +/- 70 and 635 +/- 150) when compared to non-tumor-bearing rats ( approximately 260 +/- 30). FO supplementation reduced significantly the lactate production (297 +/- 50). Gut-associated lymphocytes obtained from W and WCO groups increased lactate production markedly (280 +/- 31 and 276 +/- 25) when compared to non-tumor-bearing rats ( approximately 90 +/- 18). FO supplementation reduced significantly the lactate production (168 +/- 14). Lactate production by peritoneal macrophages was increased by tumor burden but there was no difference between the groups fed the various diets. Lifelong consumption of FO protects against tumor growth and modifies glucose metabolism in Walker tumor cells and lymphocytes but not in macrophages.

Central mechanisms controlling appetite and food intake in a cancer setting: an update

PURPOSE OF REVIEW

Cachexia, also known as disease-associated wasting, is an important factor in the mortality of many patients with diseases such as cancer, as well as renal and congestive heart failure. Yet the syndrome is not yet well defined, making diagnosis difficult and often subjective on the part of the physician. Nor are the central mechanisms of cachexia fully elucidated. Recent studies have begun to address these gaps by focusing on three areas: the role of cytokines in cachexia, other proteins and peptides that might be involved, and potential treatments for this devastating syndrome.

RECENT FINDINGS

Cachexia can be caused, in the absence of disease, by inflammatory stimuli and some chemotherapy drugs, suggesting possible central mechanisms in cachexia. Promising treatments include melanocortin antagonism and some hormones.

SUMMARY

While more research is necessary to illuminate causal mechanisms and uncover potential therapies of cachexia, several of its major molecular pathways have become elucidated, suggesting directions for therapeutic approaches.