Pathological beige remodeling induced by cancer cachexia depends on the disease severity and involves mainly the trans-differentiation of mature white adipocytes.

In cancer associated cachexia (CAC), white adipose tissue undergoes morphofunctional and inflammatory changes that lead to tissue dysfunction and remodeling. In addition to metabolic changes in white adipose tissues (WAT), adipose tissue atrophy has been implicated in several clinical complications and poor prognoses associated with cachexia. Adipocyte atrophy may be associated with increased beige remodeling in human CAC as evidenced by the "beige remodeling" observed in preclinical models of CAC. Even though beige remodeling is associated with CAC-induced WAT dysfunction, there are still some open questions regarding their cellular origins. In this study, we investigated the development of beige remodeling in CAC from a broader perspective. In addition, we used a grading system to identify the scAT as being affected by mice weight loss early and intensely. Using different in vitro and ex-vivo techniques, we demonstrated that Lewis LLC1 cells can induce a switch from white to beige adipocytes, which is specific to this type of tumor cell. During the more advanced stages of CAC, beige adipocytes are mainly formed from the transdifferentiation of cells. According to our results, humanizing the CAC classification system is an efficient approach to defining the onset of the syndrome in a more homogeneous manner. Pathological beige remodeling occurred early in the disease course and exhibited phenotypic characteristics specific to LLC cells' secretomes. Developing therapeutic strategies that recruit beige adipocytes in vivo may be better guided by an understanding of the cellular origins of beige adipocytes emitted by CAC.

Cachexia causes time-dependent activation of the inflammasome in the liver.

BACKGROUND: Cachexia is a wasting syndrome associated with systemic inflammation and metabolic disruption. Detection of the early signs of the disease may contribute to the effective attenuation of associated symptoms. Despite playing a central role in the control of metabolism and inflammation, the liver has received little attention in cachexia. We previously described relevant disruption of metabolic pathways in the organ in an animal model of cachexia, and herein, we adopt the same model to investigate temporal onset of inflammation in the liver. The aim was thus to study inflammation in rodent liver in the well-characterized cachexia model of Walker 256 carcinosarcoma and, in addition, to describe inflammatory alterations in the liver of one cachectic colon cancer patient, as compared to one control and one weight-stable cancer patient. METHODS: Colon cancer patients (one weight stable [WSC] and one cachectic [CC]) and one patient undergoing surgery for cholelithiasis (control, n = 1) were enrolled in the study, after obtainment of fully informed consent. Eight-week-old male rats were subcutaneously inoculated with a Walker 256 carcinosarcoma cell suspension (2 × 107 cells in 1.0 mL; tumour-bearing [T]; or phosphate-buffered saline-controls [C]). The liver was excised on Days 0 (n = 5), 7 (n = 5) and 14 (n = 5) after tumour cell injection. RESULTS: In rodent cachexia, we found progressively higher numbers of CD68+ myeloid cells in the liver along cancer-cachexia development. Similar findings are described for CC, whose liver showed infiltration of the same cell type, compared with both WSC and control patient organs. In advanced rodent cachexia, hepatic phosphorylated c-Jun N-terminal kinase protein content and the inflammasome pathway protein expression were increased in relation to baseline (P < 0.05). These changes were accompanied by augmented expression of the active interleukin-1ß (IL-1ß) form (P < 0.05 for both circulating and hepatic content). CONCLUSIONS: The results show that cancer cachexia is associated with an increase in the number of myeloid cells in rodent and human liver and with modulation of hepatic inflammasome pathway. The latter contributes to the aggravation of systemic inflammation, through increased release of IL-1ß.

Sympathetic nerve-adipocyte interactions in response to acute stress.

Psychological stress predisposes our body to several disorders. Understanding the cellular and molecular mechanisms involved in the physiological responses to psychological stress is essential for the success of therapeutic applications. New studies show, by using in vivo inducible Cre/loxP-mediated approaches in combination with pharmacological blockage, that sympathetic nerves, activated by psychological stress, induce brown adipocytes to produce IL-6. Strikingly, this cytokine promotes gluconeogenesis in hepatocytes, that results in the decline of tolerance to inflammatory organ damage. The comprehension arising from this research will be crucial for the handling of many inflammatory diseases. Here, we review recent advances in our comprehension of the sympathetic nerve-adipocyte axis in the tissue microenvironment.

Analysis of mouse faecal dysbiosis, during the development of cachexia, induced by transplantation with Lewis lung carcinoma cells.

Cachexia (CC) is a complex wasting syndrome that significantly affects life quality and life expectancy among cancer patients. Original studies, in which CC was induced in mouse models through inoculation with BaF and C26 tumour cells, demonstrated that CC development correlates with bacterial gut dysbiosis in these animals. In both cases, a common microbial signature was observed, based on the expansion of Enterobacteriaceae in the gut of CC animals. However, these two types of tumours induce unique microbial profiles, suggesting that different CC induction mechanisms significantly impact the outcome of gut dysbiosis. The present study sought to expand the scope of such analyses by characterizing the CC-associated dysbiosis that develops when mice are inoculated with Lewis lung carcinoma (LLC) cells, which constitutes one of the most widely employed mechanisms for CC induction. Interestingly, Enterobacteriaceae expansion is also observed in LLC-induced CC. However, the dysbiosis identified herein displays a more complex pattern, involving representatives from seven different bacterial phyla, which were consistently identified across successive levels of taxonomic hierarchy. These results are supported by a predictive analysis of gene content, which identified a series of functional/structural changes that potentially occur in the gut bacterial population of these animals, providing a complementary and alternative approach to microbiome analyses based solely on taxonomic classification.

Three-Dimensional Adipocyte Culture as a Model to Study Cachexia-Induced White Adipose Tissue Remodeling.

Cancer cachexia (CC) presents itself as a syndrome with multiple manifestations, causing a marked multi-organ metabolic imbalance. Recently, cachectic wasting has been proposed to be stimulated by several inflammatory mediators, which may disrupt the integrative physiology of adipose tissues and other tissues such as the brain and muscle. In this scenario, the tumor can survive at the host's expense. In recent clinical research, the intensity of depletion of the different fat deposits has been negatively correlated with the patient's survival outcome. Studies have also shown that various metabolic disorders can alter white adipose tissue (WAT) remodeling, especially in the early stages of cachexia development. WAT dysfunction resulting from tissue remodeling is a contributor to overall cachexia, with the main modifications in WAT consisting of morpho-functional changes, increased adipocyte lipolysis, accumulation of immune cells, reduction of adipogenesis, changes in progenitor cell population, and the increase of "niches" containing beige/brite cells. To study the various facets of cachexia-induced WAT remodeling, particularly the changes progenitor cells and beige remodeling, two-dimensional (2D) culture has been the first option for in vitro studies. However, this approach does not adequately summarize WAT complexity. Improved assays for the reconstruction of functional AT ex vivo help the comprehension of physiological interactions between the distinct cell populations. This protocol describes an efficient three-dimensional (3D) printing tissue culture system based on magnetic nanoparticles. The protocol is optimized for investigating WAT remodeling induced by cachexia induced factors (CIFs). The results show that a 3D culture is an appropriate tool for studying WAT modeling ex vivo and may be useful for functional screens to identify bioactive molecules for individual adipose cell populations applications and aid the discovery of WAT-based cell anticachectic therapy.

Fungal Dysbiosis Correlates with the Development of Tumor-Induced Cachexia in Mice.

Cachexia (CC) is a devastating metabolic syndrome associated with a series of underlying diseases that greatly affects life quality and expectancy among cancer patients. Studies involving mouse models, in which CC was induced through inoculation with tumor cells, originally suggested the existence of a direct correlation between the development of this syndrome and changes in the relative proportions of several bacterial groups present in the digestive tract. However, these analyses have focus solely on the characterization of bacterial dysbiosis, ignoring the possible existence of changes in the relative populations of fungi, during the development of CC. Thus, the present study sought to expand such analyses, by characterizing changes that occur in the gut fungal population (mycobiota) of mice, during the development of cancer-induced cachexia. Our results confirm that cachectic animals, submitted to Lewis lung carcinoma (LLC) transplantation, display significant differences in their gut mycobiota, when compared to healthy controls. Moreover, identification of dysbiotic fungi showed remarkable consistency across successive levels of taxonomic hierarchy. Many of these fungi have also been associated with dysbioses observed in a series of gut inflammatory diseases, such as obesity, colorectal cancer (CRC), myalgic encephalomyelitis (ME) and inflammatory bowel disease (IBD). Nonetheless, the dysbiosis verified in the LLC model of cancer cachexia seems to be unique, presenting features observed in both obesity (reduced proportion of Mucoromycota) and CRC/ME/IBD (increased proportions of Sordariomycetes, Saccharomycetaceae and Malassezia). One species of Mucoromycota (Rhyzopus oryzae) stands out as a promising probiotic candidate in adjuvant therapies, aimed at treating and/or preventing the development of CC.

Exercise Training as Therapeutic Approach in Cancer Cachexia: A Review of Potential Anti-inflammatory Effect on Muscle Wasting.

Cachexia is a multifactorial inflammatory syndrome with high prevalence in cancer patients. It is characterized by a metabolic chaos culminating in drastic reduction in body weight, mainly due to skeletal muscle and fat depletion. Currently, there is not a standard intervention for cachexia, but it is believed that a dynamic approach should be applied early in the course of the disease to maintain or slow the loss of physical function. The present review sought to explain the different clinical and experimental applications of different models of exercise and their contribution to a better prognosis of the disease. Here the advances in knowledge about the application of physical training in experimental models are elucidated, tests that contribute substantially to elucidate the cellular and biochemical mechanisms of exercise in different ways, as well as clinical trials that present not only the impacts of exercise in front cachexia but also the challenges of its application in clinical practice.

Toll-Like Receptor-4 Disruption Suppresses Adipose Tissue Remodeling and Increases Survival in Cancer Cachexia Syndrome.

Cancer-induced cachexia, characterized by systemic inflammation, body weight loss, adipose tissue (AT) remodeling and muscle wasting, is a malignant metabolic syndrome with undefined etiology. Here, we show that both genetic ablation and pharmacological inhibition of TLR4 were able to attenuate the main clinical markers of cachexia in mice bearing Lewis lung carcinoma (LLC). AT remodelling was not found in LLC tumor-bearing (TB) TLR4-/- mice due to reduced macrophage infiltration and adipocyte atrophy. TLR4-/- mice were also resistant to cold-induced browning of subcutaneous AT (scAT). Importantly, pharmacological inhibition of TLR4 (Atorvastatin) reproduced the main protective effect against AT remodeling found in TLR4-/- TB mice. Moreover, the treatment was effective in prolonging survival and attenuating tumor mass growth when compared to non-treated-TB animals. Furthermore, tumor-induced elevation of circulating pro-inflammatory cytokines was similarly abolished in both genetic ablation and pharmacological inhibition of TLR4. These data suggest that TLR4 is a critical mediator and a promising target for novel anti-cachexia therapies.

Physical Exercise-Induced Myokines and Muscle-Adipose Tissue Crosstalk: A Review of Current Knowledge and the Implications for Health and Metabolic Diseases.

Physical exercise has beneficial effects on metabolic diseases, and a combined therapeutic regimen of regular exercise and pharmaceutical treatment is often recommended for their clinical management. However, the mechanisms by which exercise produces these beneficial effects are not fully understood. Myokines, a group of skeletal muscle (SkM) derived peptides may play an important part in this process. Myokines are produced, expressed and released by muscle fibers under contraction and exert both local and pleiotropic effects. Myokines such as IL-6, IL-10, and IL-1ra released during physical exercise mediate its health benefits. Just as exercise seems to promote the myokine response, physical inactivity seems to impair it, and could be a mechanism to explain the association between sedentary behavior and many chronic diseases. Myokines help configure the immune-metabolic factor interface and the health promoting effects of physical exercise through the release of humoral factors capable of interacting with other tissues, mainly adipose tissue (AT). AT itself secretes proinflammatory cytokines (adipokines) as a result of physical inactivity and it is well recognized that AT inflammation can lead to the development of metabolic diseases, such as type 2 diabetes mellitus (T2DM) and atherosclerosis. On the other hand, the browning phenotype of AT has been suggested to be one of the mechanisms through which physical exercise improves body composition in overweight/obese individuals. Although, many cytokines are involved in the crosstalk between SkM and AT, in respect of these effects, it is IL-6, IL-15, irisin, and myostatin which seem to have the decisive role in this "conversation" between AT and SkM. This review article proposes to bring together the latest "state of the art" knowledge regarding Myokines and muscle-adipose tissue crosstalk. Furthermore, it is intended to particularly focus on the immune-metabolic changes from AT directly mediated by myokines.

Lipases and lipid droplet-associated protein expression in subcutaneous white adipose tissue of cachectic patients with cancer.

BACKGROUND: Cancer cachexia is a multifactorial metabolic syndrome characterized by marked loss of adipose tissue and skeletal muscle. Fat loss from adipose tissue in cancer cachexia is partly the result of increased lipolysis. Despite the growing amount of studies focused on elucidating the mechanisms through which lipolysis-related proteins regulate the lipolytic process, there are scarce data concerning that profile in the adipose tissue of cancer cachectic patients. Considering its fundamental importance, it was our main purpose to characterize the expression of the lipolysis-related proteins in the white adipose tissue of cachectic cancer patients. METHODS: Patients from the University Hospital were divided into three groups: control, cancer cachexia (CC), and weight-stable cancer patients (WSC). To gain greater insight into adipose tissue wasting during cancer cachexia progression, we have also analyzed an experimental model of cachexia (Walker 256 carcinosarcoma). Animals were divided into: control, intermediate cachexia (IC) and terminal cachexia (TC). Subcutaneous white adipose tissue of patients and epidydimal white adipose tissue of animals were investigated regarding molecular aspects by determining the protein content and gene expression of hormone-sensitive lipase (HSL), adipose triglyceride lipase (ATGL), comparative gene identification-58 (CGI-58), perilipin 1, leptin, adiponectin, visfatin, and tumour necrosis factor alpha (TNF-alpha). RESULTS: We found augmented lipolysis in CC associated with increased HSL expression, as well as upregulation of ATGL expression and reduction in perilipin 1 content. In IC, there was an imbalance in the secretion of pro- and anti-inflammatory factors. The alterations at the end-stage of cachexia were even more profound, and there was a reduction in the expression of almost all proteins analyzed in the animals. CONCLUSIONS: Our findings show that cachexia induces important morphological, molecular, and humoral alterations in the white adipose tissue, which are specific to the stage of the syndrome.

White adipose tissue cells and the progression of cachexia: inflammatory pathways.

BACKGROUND: Cachexia is a systemic syndrome leading to body wasting, systemic inflammation, and to metabolic chaos. It is a progressive condition, and little is known about its dynamics. Detection of the early signs of the disease may lead to the attenuation of the associated symptoms. The white adipose tissue is an organ with endocrine functions, capable of synthesising and secreting a plethora of proteins, including cytokines, chemokines, and adipokines. It is well established that different adipose tissue depots demonstrate heterogeneous responses to physiological and pathological stimuli. The present study aimed at providing insight into adipocyte involvement in inflammation along the progression of cachexia. METHODS: Eight-weeks-old male rats were subcutaneously inoculated with a Walker 256 carcinosarcoma cell suspension (2 × 10(7) cells in 1.0 mL; tumour-bearing, T) or Phosphate-buffered saline (control, C). The retroperitoneal, epididymal, and mesenteric adipose pads were excised on Days 0, 7, and 14 post-tumour cell injection, and the adipocytes were isolated. RESULTS: Mesenteric and epididymal adipocytes showed up-regulation of IL-1ß protein expression and activation of the inflammasome pathway, contributing for whole tissue inflammation. The stromal vascular fraction of the retroperitoneal adipose tissue, on the other hand, seems to be the major contributor for the inflammation in this specific pad. CONCLUSION: Adipocytes seem to play a relevant role in the establishment of white adipose tissue inflammation, through the activation of the NF-κB and inflammasome pathways. In epididymal adipocytes, induction of the inflammasome may be detected already on Day 7 post-tumour cell inoculation.

Cachexia-associated adipose tissue morphological rearrangement in gastrointestinal cancer patients.

BACKGROUND AND AIMS: Cachexia is a syndrome characterized by marked involuntary loss of body weight. Recently, adipose tissue (AT) wasting has been shown to occur before the appearance of other classical cachexia markers. We investigated the composition and rearrangement of the extracellular matrix, adipocyte morphology and inflammation in the subcutaneous AT (scAT) pad of gastrointestinal cancer patients. METHODS: Surgical biopsies for scAT were obtained from gastrointestinal cancer patients, who were signed up into the following groups: cancer cachexia (CC, n = 11), weight-stable cancer (WSC, n = 9) and weight-stable control (non-cancer) (control, n = 7). The stable weight groups were considered as those with no important weight change during the last year and body mass index <25 kg/m(2). Subcutaneous AT fibrosis was quantified and characterized by quantitative PCR, histological analysis and immunohistochemistry. RESULTS: The degree of fibrosis and the distribution and collagen types (I and III) were different in WSC and CC patients. CC patients showed more pronounced fibrosis in comparison with WSC. Infiltrating macrophages surrounding adipocytes and CD3 Ly were found in the fibrotic areas of scAT. Subcutaneous AT fibrotic areas demonstrated increased monocyte chemotactic protein 1 (MCP-1) and Cluster of Differentiation (CD)68 gene expression in cancer patients. CONCLUSIONS: Our data indicate architectural modification consisting of fibrosis and inflammatory cell infiltration in scAT as induced by cachexia in gastrointestinal cancer patients. The latter was characterized by the presence of macrophages and lymphocytes, more evident in the fibrotic areas. In addition, increased MCP-1 and CD68 gene expression in scAT from cancer patients may indicate an important role of these markers in the early phases of cancer.

Pioglitazone treatment increases survival and prevents body weight loss in tumor-bearing animals: possible anti-cachectic effect.

Cachexia is a multifactorial syndrome characterized by profound involuntary weight loss, fat depletion, skeletal muscle wasting, and asthenia; all symptoms are not entirely attributable to inadequate nutritional intake. Adipose tissue and skeletal muscle loss during cancer cachexia development has been described systematically. The former was proposed to precede and be more rapid than the latter, which presents a means for the early detection of cachexia in cancer patients. Recently, pioglitazone (PGZ) was proposed to exhibit anti-cancer properties, including a reduction in insulin resistance and adipose tissue loss; nevertheless, few studies have evaluated its effect on survival. For greater insight into a potential anti-cachectic effect due to PGZ, 8-week-old male Wistar rats were subcutaneously inoculated with 1 mL (2×107) of Walker 256 tumor cells. The animals were randomly assigned to two experimental groups: TC (tumor + saline-control) and TP5 (tumor + PGZ/5 mg). Body weight, food ingestion and tumor growth were measured at baseline and after removal of tumor on days 7, 14 and 26. Samples from different visceral adipose tissue (AT) depots were collected on days 7 and 14 and stored at -80o C (5 to 7 animals per day/group). The PGZ treatment showed an increase in the survival average of 27.3% (P< 0.01) when compared to TC. It was also associated with enhanced body mass preservation (40.7 and 56.3%, p< 0.01) on day 14 and 26 compared with the TC group. The treatment also reduced the final tumor mass (53.4%, p<0.05) and anorexia compared with the TC group during late-stage cachexia. The retroperitoneal AT (RPAT) mass was preserved on day 7 compared with the TC group during the same experimental period. Such effect also demonstrates inverse relationship with tumor growth, on day 14. Gene expression of PPAR-γ, adiponectin, LPL and C/EBP-α from cachectic rats was upregulated after PGZ. Glucose uptake from adipocyte cells (RPAT) was entirely re-established due to PGZ treatment. Taken together, the results demonstrate beneficial effects of PGZ treatment at both the early and final stages of cachexia.

Cessation of physical exercise changes metabolism and modifies the adipocyte cellularity of the periepididymal white adipose tissue in rats.

All of the adaptations acquired through physical training are reversible with inactivity. Although significant reductions in maximal oxygen uptake (Vo2max) can be observed within 2 to 4 wk of detraining, the consequences of detraining on the physiology of adipose tissue are poorly known. Our aim was therefore to investigate the effects of discontinuing training (physical detraining) on the metabolism and adipocyte cellularity of rat periepididymal (PE) adipose tissue. Male Wistar rats, aged 6 wk, were divided into three groups and studied for 12 wk under the following conditions: 1) trained (T) throughout the period; 2) detrained (D), trained during the first 8 wk and detrained during the remaining 4 wk; and 3) age-matched sedentary (S). Training consisted of treadmill running sessions (1 h/day, 5 days/wk, 50-60% Vo2max). The PE adipocyte size analysis revealed significant differences between the groups. The adipocyte cross-sectional area (in µm(2)) was significantly larger in D than in the T and S groups (3,474 ± 68.8; 1,945.7 ± 45.6; 2,492.4 ± 49.08, respectively, P < 0.05). Compared with T, the isolated adipose cells (of the D rats) showed a 48% increase in the ability to perform lipogenesis (both basal and maximally insulin-stimulated) and isoproterenol-stimulated lipolysis. No changes were observed with respect to unstimulated lipolysis. A 15% reduction in the proportion of apoptotic adipocytes was observed in groups T and D compared with group S. The gene expression levels of adiponectin and PPAR-gamma were upregulated by factors of 3 and 2 in D vs. S, respectively. PREF-1 gene expression was 3-fold higher in T vs. S. From these results, we hypothesize that adipogenesis was stimulated in group D and accompanied by significant adipocyte hypertrophy and an increase in the lipogenic capacity of the adipocytes. The occurrence of apoptotic nuclei in PE fat cells was reduced in the D and T rats; these results raise the possibility that the adipose tissue changes after detraining are obesogenic.

Hypothalamic inflammation is reversed by endurance training in anorectic-cachectic rats.

AIM: We tested the effects of a cancer cachexia-anorexia sydrome upon the balance of anti and pro-inflammatory cytokines in the hypothalamus of sedentary or trained tumour-bearing (Walker-256 carcinosarcoma) rats. METHODS: Animals were randomly assigned to a sedentary control (SC), sedentary tumour-bearing (ST), and sedentary pair-fed (SPF) groups or, exercised control (EC), exercised tumour-bearing (ET) and exercised pair-fed (EPF) groups. Trained rats ran on a treadmill (60%VO2max) for 60 min/d, 5 days/wk, for 8 wks. We evaluated food intake, leptin and cytokine (TNF-α, IL1ß) levels in the hypothalamus. RESULTS: The cumulative food intake and serum leptin concentration were reduced in ST compared to SC. Leptin gene expression in the retroperitoneal adipose tissue (RPAT) was increased in SPF in comparison with SC and ST, and in the mesenteric adipose tissue (MEAT) the same parameter was decreased in ST in relation to SC. Leptin levels in RPAT and MEAT were decreased in ST, when compared with SC. Exercise training was also able to reduce tumour weight when compared to ST group. In the hypothalamus, IL-1ß and IL-10 gene expression was higher in ST than in SC and SPF. Cytokine concentration in hypothalamus was higher in ST (TNF-α and IL-1ß, p < 0.05), compared with SC and SPF. These pro-inflammatory cytokines concentrations were restored to control values (p < 0.05), when the animals were submitted to endurance training. CONCLUSION: Cancer-induced anorexia leads towards a pro-inflammatory state in the hypothalamus, which is prevented by endurance training which induces an anti-inflammatory state, with concomitant decrease of tumour weight.

Chronic exercise decreases cytokine production in healthy rat skeletal muscle.

Skeletal muscle is the source of pro- and anti-inflammatory cytokines, and recently, it has been recognized as an important source of interleukin-6 (IL-6). Acute physical exercise is known to induce a pro-inflammatory cytokine profile in the plasma. However, the effect of chronic physical exercise in the production of pro- and anti-inflammatory cytokines by the skeletal muscle has never been examined. We assessed IL-6, TNF-alpha, IL-1beta and IL-10 levels in the skeletal muscle of rats submitted to endurance training. Animals were randomly assigned to either a sedentary group (S, n = 7) or an endurance exercise trained group (T, n = 8). Trained rats ran on a treadmill for 5 days week(-1) for 8 weeks (60% VO(2max)). Detection of IL-6, TNF-alpha, IL-1beta and IL-10 protein expression was carried out by ELISA. We found decreased expression of IL-1beta, IL-6, TNF-alpha and IL-10 (28%, 27%, 32% and 37%, respectively, p < 0.05) in the extensor digital longus (EDL) from T, when compared with S. In the soleus, IL-1beta, TNF-alpha and IL-10 protein levels were similarly decreased (34%, 42% and 50%, respectively, p < 0.05) in T in relation to S, while IL-6 expression was not affected by the training protocol. In conclusion, exercise training induced decreased cytokine protein expression in the skeletal muscle. These data show that in healthy rats, 8-week moderate-intensity aerobic training down regulates skeletal muscle production of cytokines involved in the onset, maintenance and regulation of inflammation, and that the response is heterogeneous according to fibre composition.

Exhaustive exercise causes an anti-inflammatory effect in skeletal muscle and a pro-inflammatory effect in adipose tissue in rats.

It is well known that exhaustive exercise increases serum and skeletal muscle IL-6 concentrations. However, the effect of exhaustive exercise on the concentrations of other cytokines in the muscle and in the adipose tissue is controversial. The purpose of this study was to evaluate the effect of exhaustive exercise on mRNA and protein expression of IL-10, TNF-alpha and IL-6 in different types of skeletal muscle (EDL, soleus) and in two different depots of white adipose tissue (mesenteric-MEAT and retroperitoneal-RPAT). Rats were killed by decapitation immediately (E0 group, n = 6), 2 (E2 group, n = 6) and 6 (E6 group, n = 6) hours after the exhaustion protocol, which consisted of running on a treadmill (approximately 70% VO(2max) for 50 min and then subsequently at an elevated rate that increased at 1 m/min every minute, until exhaustion). The control group (C group, n = 6) was not subjected to exercise. Cytokine protein expression increased in EDL, soleus, MEAT and RPAT from all exercised groups, as detected by ELISA. EDL IL-10 and TNF-alpha expression was higher than that of the soleus. The IL-10/TNF-alpha ratio was increased in the skeletal muscle, especially in EDL, but it was found to be decreased in the adipose tissue. These results show that exhaustive exercise presents a different effect depending on the tissue which is analysed: in the muscle, it induces an anti-inflammatory effect, especially in type 2 fibres, while the pro-inflammatory effect prevails in adipose tissue, possibly contributing to increased lipolysis to provide energy for the exercising muscle.

Effect of exercise on glutamine synthesis and transport in skeletal muscle from rats.

1. Reductions in plasma glutamine are observed after prolonged exercise. Three hypotheses can explain such a decrease: (i) high demand by the liver and kidney; (ii) impaired release from muscles; and (iii) decreased synthesis in skeletal muscle. The present study investigated the effects of exercise on glutamine synthesis and transport in rat skeletal muscle. 2. Rats were divided into three groups: (i) sedentary (SED; n = 12); (ii) rats killed 1 h after the last exercise bout (EX-1; n = 15); and (iii) rats killed 24 h after the last exercise bout (EX-24; n = 15). Rats in the trained groups swam 1 h/day, 5 days/week for 6 weeks with a load equivalent to 5.5% of their bodyweight. 3. Plasma glutamine and insulin were lower and corticosterone was higher in EX-1 compared with SED rats (P < 0.05 and P < 0.01, respectively). Twenty-four hours after exercise (EX-24), plasma glutamine was restored to levels seen in SED rats, whereas insulin levels were higher (P < 0.001) and corticosterone levels were lower (P < 0.01) than in EX-1. In the soleus, ammonia levels were lower in EX-1 than in SED rats (P < 0.001). After 24 h, glutamine, glutamate and ammonia levels were lower in EX-24 than in SED and EX-1 rats (P < 0.001). Soleus glutamine synthetase (GS) activity was increased in EX-1 and was decreased in EX-24 compared with SED rats (both P < 0.001). 4. The decrease in plasma glutamine concentration in EX-1 is not mediated by GS or glutamine transport in skeletal muscle. However, 24 h after exercise, lower GS may contribute to the decrease in glutamine concentration in muscle.

Regulation of inflammation in the adipose tissue in cancer cachexia: effect of exercise.

The paraneoplastic syndrome of cachexia is considered a degenerative chronic inflammatory disease, being deeply related to the increase of pro-inflammatory factors, especially tumour necrosis factor alpha (TNF-alpha). It is known that the adipose tissue is affected by cachexia and contributing with the secretion of pro-inflammatory factors which reach the adjacent tissues and the circulation. The effect of pro-inflammatory factors is balanced by the effect of anti-inflammatory factors, such as interleukin 10 (IL-10). The IL-10/TNF-alpha ratio has been recently postulated as a marker for the assessment of the degree of inflammation, which correlates with disease-associated morbidity and mortality. In order to counteract inflammation in chronic disease, our group has currently adopted chronic endurance exercise in models of cancer cachexia and chronic heart failure. Since it is clear that white adipose tissue is strongly implicated in the secretion of both pro- and anti-inflammatory factors in disease, we chose to address its contribution to cachexia-related inflammation and the effect of endurance training on the capacity of cytokine expression and secretion by this tissue. Our results show an enhancement of IL-10 adipose tissue content, and increased IL-10/TNF-alpha ratio induced by endurance training. The mechanisms are discussed.