The role of cytokines in cancer cachexia

Insulin in combination with pioglitazone prevents advanced cachexia in 256-Walker tumor-bearing rats: effect is greater than treatment alone and is associated with improved insulin sensitivity

BACKGROUND

Insulin (INS) resistance and hypoinsulinemia commonly observed in cancer-carrying, can contribute to cachexia. However, the effects of INS and INS sensitizers, such as pioglitazone (PIO), particularly when used in combination therapy, on cancer cachexia have not been evaluated sufficiently. We investigated the effects of INS and PIO, at various doses, either isolated or combined, on cachexia in Walker-256 tumor-bearing rats (TB rats).

METHODS

INS or INS + PIO were administered in TB rats, for 6 or 12 days, starting from the day of tumor cells inoculation.

RESULTS

INS at 18 or 27 U/kg (12-days treatment), but not 9 U/kg, reduced fat loss and slightly prevented weight loss. However, INS 18 U/kg + PIO 5, 10, 20, or 40 mg/kg (6 or 12-day treatment) reduced fat loss and markedly prevented weight loss but did not affect muscle wasting. While TB rats lost weight (37.9% in 12 days), TB rats treated with INS 18 U/kg + PIO 5 mg/kg showed pronounced weight gain (73.7%), which was greater than the sum (synergism) of the weight gains promoted by isolated treatments with INS 18 U/kg (14.7%) or PIO 5 mg/kg (13.1%). The beneficial effect of the INS 18 U/kg + PIO 5 mg/kg on weight loss was associated with improved INS sensitivity, as indicated by the higher blood glucose clearance constant (kITT), decreased levels of free fatty acids and triacylglycerols (INS resistance-inducing factors) in the blood, and increased expression of p-Akt (INS signaling pathway protein) in adipose tissue.

CONCLUSIONS

The combined treatment with INS 18 U/kg + PIO 5 mg/kg was more effective in preventing advanced cachexia in TB rats than each treatment alone, emerging as the best approach, considering the lower dosage and higher efficacy. This combination completely preserved adipose mass and markedly reduced weight loss through a synergistic mechanism linked to improved insulin sensitivity. These findings provide new insights into the importance of drug combinations in effectively combating fat loss in advanced cachexia.

Cancer Cachexia: Underlying Mechanisms and Potential Therapeutic Interventions

Cancer cachexia, a multifactorial metabolic syndrome developed during malignant tumor growth, is characterized by an accelerated loss of body weight accompanied by the depletion of skeletal muscle mass. This debilitating condition is associated with muscle degradation, impaired immune function, reduced functional capacity, compromised quality of life, and diminished survival in cancer patients. Despite the lack of the known capability of fully reversing or ameliorating this condition, ongoing research is shedding light on promising preclinical approaches that target the disrupted mechanisms in the pathophysiology of cancer cachexia. This comprehensive review delves into critical aspects of cancer cachexia, including its underlying pathophysiological mechanisms, preclinical models for studying the progression of cancer cachexia, methods for clinical assessment, relevant biomarkers, and potential therapeutic strategies. These discussions collectively aim to contribute to the evolving foundation for effective, multifaceted counteractive strategies against this challenging condition.

Associations of Prior Chronic Use of Non-Steroidal Anti-Inflammatory Drugs (NSAIDs) and Glucocorticoids With Cachexia Incidence and Survival

Background

Cachexia is an inflammatory and metabolic syndrome of unintentional weight loss through depletion of muscle and adipose tissue. There is limited knowledge of how chronic use of non-steroidal anti-inflammatory drugs (NSAIDs) and glucocorticoids affect cachexia development. The purpose of this study was to investigate associations between prior long-term use of NSAIDs or glucocorticoids with cachexia incidence and post-diagnosis weight loss progression in a retrospective cancer patient cohort.

Methods

Of 3,802 lung or gastrointestinal cancer patient records, 3,180 comprised our final cohort. Patient demographic information, tumor qualities, medication histories, and comorbidities were assessed. Cachexia was defined as having developed prior to oncologic treatment. Statistical evaluations included categorical, multivariate logistic regression, and log-rank survival analyses. Development of substantial post-diagnosis weight loss was calculated and interpreted for patients without cachexia at diagnosis.

Results

Chronic prior use of any NSAID or glucocorticoid medication was associated with approximate absolute and relative reductions in cachexia incidence at diagnosis of 10 and 25 percent (P<0.0001). In multivariate analyses, NSAID medications demonstrated a 23 percent reduction in cachexia incidence likelihood (OR=0.770; 95% CI=0.594, 0.998; P=0.0481). Patients without cachexia at diagnosis were significantly more likely to develop substantial post-diagnosis weight loss from pre-diagnosis use groups of glucocorticoids (OR= 1.452; 95% CI=1.065, 1.979; P=0.0183) or NSAIDs (OR=1.411; 95% CI=1.082, 1.840; P=0.011).

Conclusions

Our findings suggest a protective effect of prior anti-inflammatory medications, primarily NSAIDs, against manifestations of the cachexia phenotype at cancer diagnosis. These observations support further exploration of potential therapeutic benefits from anti-inflammatory medications early in cancer management.

Macrophages in the pancreas: Villains by circumstances, not necessarily by actions

Introduction

Mounting evidence suggest that macrophages play crucial roles in disease and tissue regeneration. However, despite much efforts during the past decade, our knowledge about the extent of macrophages' contribution to adult pancreatic regeneration after injury or during pancreatic disease progression is still limited. Nevertheless, it is generally accepted that some macrophage features that normally would contribute to healing and regeneration may be detrimental in pancreatic cancer. Altogether, the current literature contains conflicting reports on whether macrophages act as friends or foe in these conditions.

Methods and Results

In this review, we briefly review the origins of tissue resident and infiltrating macrophages and the importance of cellular crosstalking between macrophages and other resident cells in tissue regeneration. The primary objective of this review is to summarize our knowledge of the distinct roles of tissue resident and infiltrating macrophages, the impact of M1 and M2 macrophage phenotypes, and emerging evidence on macrophage crosstalking in pancreatic injury, regeneration, and disease.

Conclusion

Macrophages are involved with various stages of pancreatic cancer development, pancreatitis, and diabetes. Elucidating their role in these conditions will aid the development of targeted therapeutic treatments.

[Hypothalamic inflammation and energy balance deregulations: focus on chemokines.]

The hypothalamus is a key brain region in the regulation of energy balance. It especially controls food intake and both energy storage and expenditure through integration of humoral, neural and nutrient-related signals and cues. Hypothalamic neurons and glial cells act jointly to orchestrate, both spatially and temporally, regulated metabolic functions of the hypothalamus. Thus, the existence of a causal link between hypothalamic inflammation and deregulations of feeding behavior, such as involuntary weight-loss or obesity, has been suggested. Among the inflammatory mediators that could induce deregulations of hypothalamic control of the energy balance, chemokines represent interesting candidates. Indeed, chemokines, primarily known for their chemoattractant role of immune cells to the inflamed site, have also been suggested capable of neuromodulation. Thus, chemokines could disrupt cellular activity together with synthesis and/or secretion of multiple neurotransmitters/mediators that are involved in the maintenance of energy balance. Here, we relate, on one hand, recent results showing the primary role of the central chemokinergic signaling CCL2/CCR2 for metabolic and behavioral adaptation to high-grade inflammation, especially loss of appetite and weight, through its activity on hypothalamic neurons producing the orexigenic peptide Melanin-Concentrating Hormone (MCH) and, on the other hand, results that suggest that chemokines could also deregulate hypothalamic neuropeptidergic circuits to induce an opposite phenotype and eventually participate in the onset/development of obesity. In more details, we will emphasize a study recently showing, in a model of high-grade acute inflammation of LPS injection in mice, that central CCL2/CCR2 signaling is of primary importance for several aspects explaining weight loss associated with inflammation: after LPS injection, animals lose weight, reduce their food intake, increase their fat oxidation (thus energy consumption from fat storage)...These inflammation-induced metabolic and behavioral changes are reduced when central CCR2 signaling is disrupted either pharmacologically (by a specific inhibitor of CCR2) or genetically (in mice deficient for CCR2). This underlines the importance of this signaling in inflammation-related weight loss. We further determined that the LPS-induced and CCR2-mediated weight loss depends on the direct effect of CCR2 activation on MCH neurons activity. Indeed, the MCH neurons express CCR2, and the application of CCL2 on brain slices revealed that activation of CCR2 actually depolarizes MCH neurons and induces delays and/or failures of action potential emission. Furthermore, CCL2 is able to reduce KCl-evoked MCH secretion from hypothalamic explants. Taken together, these results demonstrate the role of the central CCL2/CCR2 signaling in metabolic and behavioral adaptation to inflammation. On the other hand, this first description of how the chemokinergic system can actually modulate the activity of the hypothalamic regulation of energy balance, but also some less advanced studies and some unpublished data, suggest that some other chemokines, such as CCL5, could participate in the development of the opposite phenotype, that is to say obesity.

Hypothalamic Inflammation and Energy Balance Disruptions: Spotlight on Chemokines

The hypothalamus is a key brain region in the regulation of energy balance as it controls food intake and both energy storage and expenditure through integration of humoral, neural, and nutrient-related signals and cues. Many years of research have focused on the regulation of energy balance by hypothalamic neurons, but the most recent findings suggest that neurons and glial cells, such as microglia and astrocytes, in the hypothalamus actually orchestrate together several metabolic functions. Because glial cells have been described as mediators of inflammatory processes in the brain, the existence of a causal link between hypothalamic inflammation and the deregulations of feeding behavior, leading to involuntary weight loss or obesity for example, has been suggested. Several inflammatory pathways that could impair the hypothalamic control of energy balance have been studied over the years such as, among others, toll-like receptors and canonical cytokines. Yet, less studied so far, chemokines also represent interesting candidates that could link the aforementioned pathways and the activity of hypothalamic neurons. Indeed, chemokines, in addition to their role in attracting immune cells to the inflamed site, have been suggested to be capable of neuromodulation. Thus, they could disrupt cellular activity together with synthesis and/or secretion of multiple neurotransmitters/mediators involved in the maintenance of energy balance. This review discusses the different inflammatory pathways that have been identified so far in the hypothalamus in the context of feeding behavior and body weight control impairments, with a particular focus on chemokines signaling that opens a new avenue in the understanding of the major role played by inflammation in obesity.

Hypothalamic inflammation and the central nervous system control of energy homeostasis

The control of energy homeostasis relies on robust neuronal circuits that regulate food intake and energy expenditure. Although the physiology of these circuits is well understood, the molecular and cellular response of this program to chronic diseases is still largely unclear. Hypothalamic inflammation has emerged as a major driver of energy homeostasis dysfunction in both obesity and anorexia. Importantly, this inflammation disrupts the action of metabolic signals promoting anabolism or supporting catabolism. In this review, we address the evidence that favors hypothalamic inflammation as a factor that resets energy homeostasis in pathological states.

Effect of Sipjeondaebo-tang on cancer-induced anorexia and cachexia in CT-26 tumor-bearing mice

Cancer-associated anorexia and cachexia are a multifactorial condition described by a loss of body weight and muscle with anorexia, asthenia, and anemia. Moreover, they correlate with a high mortality rate, poor response to chemotherapy, poor performance status, and poor quality of life. Cancer cachexia is regulated by proinflammatory cytokines such as interleukin-6 (IL-6), monocyte chemoattractant protein-1 (MCP-1), and tumor necrosis factor-α (TNF-α). In addition, glucagon like peptide-1 (GIP-1), peptide YY (PYY), ghrelin, and leptin plays a crucial role in food intake. In this study, we investigated the therapeutic effects of one of the traditional herbal medicines, Sipjeondaebo-tang (Juzen-taiho-to in Japanese; SJDBT), on cancer anorexia and cachexia in a fundamental mouse cancer anorexia/cachexia model, CT-26 tumor-bearing mice. SJDBT was more significantly effective in a treatment model where it was treated after anorexia and cachexia than in a prevention model where it was treated before anorexia and cachexia on the basis of parameters such as weights of muscles and whole body and food intakes. Moreover, SJDBT inhibited a production of IL-6, MCP-1, PYY, and GLP-1 and ameliorated cancer-induced anemia. Therefore, our in vivo studies provide evidence on the role of SJDBT in cancer-associated anorexia and cachexia, thereby suggesting that SJDBT may be useful for treating cancer-associated anorexia and cachexia.

Cancer cachexia pathophysiology and translational aspect of herbal medicine

About half of all cancer patients show a syndrome of cachexia, characterized by anorexia and loss of adipose tissue and skeletal muscle mass. Numerous cytokines have been postulated to play a role in the etiology of cancer cachexia. Cytokines can elicit effects that mimic leptin signaling and suppress orexigenic ghrelin and neuropeptide Y signaling, inducing sustained anorexia and cachexia not accompanied by the usual compensatory response. Furthermore, cytokines have been implicated in the induction of cancer-related muscle wasting. In particular, tumor necrosis factor-alpha, interleukin-1, interleukin-6 and interferon-gamma have been implicated in the induction of cancer-related muscle wasting. Cytokine-induced skeletal muscle wasting is probably a multifactorial process, which involves a depression in protein synthesis, an increase in protein degradation or a combination of both. Cancer patients suffer from the reduction in physical function, tolerance to anti-cancer therapy and survival, while many effective chemotherapeutic agents for cancer are burdened by toxicities that can reduce patient's quality of life or hinder their effective use. Herbal medicines have been widely used to help improve such conditions. Recent studies have shown that herbal medicines such as rikkunshito enhance ghrelin signaling and consequently improve nausea, appetite loss and cachexia associated with cancer or cancer chemotherapy, which worsens the quality of life and life expectancy of the patients. The multicomponent herbal medicines capable of targeting multiple sites could be useful for future drug discovery. Mechanistic studies and identification of active compounds could lead to new discoveries in biological and biomedical sciences.

Cancer cachexia--pathophysiology and management

About half of all cancer patients show a syndrome of cachexia, characterized by anorexia and loss of adipose tissue and skeletal muscle mass. Cachexia can have a profound impact on quality of life, symptom burden, and a patient's sense of dignity. It is a very serious complication, as weight loss during cancer treatment is associated with more chemotherapy-related side effects, fewer completed cycles of chemotherapy, and decreased survival rates. Numerous cytokines have been postulated to play a role in the etiology of cancer cachexia. Cytokines can elicit effects that mimic leptin signaling and suppress orexigenic ghrelin and neuropeptide Y (NPY) signaling, inducing sustained anorexia and cachexia not accompanied by the usual compensatory response. Furthermore, cytokines have been implicated in the induction of cancer-related muscle wasting. Cytokine-induced skeletal muscle wasting is probably a multifactorial process, which involves a protein synthesis inhibition, an increase in protein degradation, or a combination of both. The best treatment of the cachectic syndrome is a multifactorial approach. Many drugs including appetite stimulants, thalidomide, cytokine inhibitors, steroids, nonsteroidal anti-inflammatory drugs, branched-chain amino acids, eicosapentaenoic acid, and antiserotoninergic drugs have been proposed and used in clinical trials, while others are still under investigation using experimental animals. There is a growing awareness of the positive impact of supportive care measures and development of promising novel pharmaceutical agents for cachexia. While there has been great progress in understanding the underlying biological mechanisms of cachexia, health care providers must also recognize the psychosocial and biomedical impact cachexia can have.

Changes in liver gluconeogenesis during the development of Walker-256 tumour in rats

Few studies have investigated liver gluconeogenesis in cancer and there is no agreement as to whether the activity of this pathway is increased or decreased in this disease. The aim of this study was to evaluate gluconeogenesis from alanine, pyruvate and glycerol, and related metabolic parameters in perfused liver from Walker-256 tumour-bearing rats on days 5 (WK5 group), 8 (WK8 group) and 12 (WK12 group) of tumour development. There was reduction (P < 0.05) of liver glucose production from alanine and pyruvate in WK5, WK8 and WK12 groups, which was accompanied by a decrease (P < 0.05) in oxygen consumption. Moreover, there was higher (P < 0.05) pyruvate and lactate production from alanine in the WK5 group and a marked reduction (P < 0.05) of pyruvate and urea production from alanine in the WK12 group. In addition, liver glucose production and oxygen consumption from glycerol were not reduced in WK5, WK8 and WK12 groups. Thus the, the results show inhibition of hepatic gluconeogenesis from alanine and pyruvate, but not from glycerol, on days 5, 8 and 12 of Walker-256 tumour development, which can be attributed to the metabolic step in which the substrate enters the gluconeogenic pathway.

Nutrition in the care of patients with cancer cachexia

Cancer cachexia, a progressive wasting syndrome experienced by approximately 80% of patients, is characterized by loss of adipose tissue and lean body mass. This complex metabolic process reflects both reduced nutrient availability and increased nutritional demand. Though cachexia is most commonly associated with particular tumours, no patient or tumour are excluded. This article provides an overview of cachexia and its pathophysiology and the factors contributing to its development before considering its impact on individuals. Emphasis is placed on the nutritional aspects of its management.

Cachexia, malnutrition, the refeeding syndrome, and lessons from Goldilocks

Cachexia has plagued clinicians for centuries. Although all cachexia is related to malnutrition, cachexia associated with malignant diseases differs from starvation cachexia in that it is more recalcitrant to nutritional therapy. All cachexia responds to judicious nutritional support; however, cancer cachexia worsens autonomously as the disease advances and cannot be arrested or reversed by any known form of nutrition, hormonal, or pharmacologic therapy. Cachexia must be treated cautiously to avoid overfeeding syndrome, which may result in serious or dangerous complications or death.

Deletion of the gene encoding MyD88 protects from anorexia in a mouse tumor model

The anorexia-cachexia syndrome, characterized by a rise in energy expenditure and loss of body weight that paradoxically are associated with loss of appetite and decreased food intake, contributes significantly to the morbidity and mortality in cancer. While the pathophysiology of cancer anorexia-cachexia is poorly understood, evidence indicates that pro-inflammatory cytokines are key mediators of this response. Although inflammation hence is recognized as an important component of cancer anorexia-cachexia, the molecular pathways involved are largely unknown. We addressed this issue in mice carrying a deletion of the gene encoding MyD88, the key intracellular adaptor molecule in Toll-like and interleukin-1 family receptor signaling. Wild-type and MyD88-deficient mice were transplanted subcutaneously with a syngenic methylcholanthrene-induced tumor (MCG 101) and daily food intake and body weight were recorded. Wild-type mice showed progressively reduced food intake from about 5days after tumor transplantation and displayed a slight body weight loss after 10days when the experiment was terminated. In contrast, MyD88-deficient mice did not develop anorexia, and displayed a positive body weight development during the observation period. While the MyD88-deficient mice on average developed somewhat smaller tumors than wild-type mice, this did not explain the absence of anorexia, because anorexia was seen in wild-type mice with similar tumor mass as non-anorexic knock-out mice. These data suggest that MyD88-dependent mechanisms are involved in the metabolic derangement during cancer anorexia-cachexia and that innate immune signaling is important for the development of this syndrome.

Usage of megestrol acetate in the treatment of anorexia-cachexia syndrome in the elderly

The aim of this review is to assess the efficacy and safety of megestrol acetate (MA) in geriatric cachexia. The paper presented here reviews a previously published study of MA use in 69 patients in a randomized double blind placebo-controlled trial. This paper will also address the underlying pathogenesis of cachexia (specifically, the role of cytokines) along with the use of MA, its mechanism of action and its side effects.

OBJECTIVE

To compare the effects of MA oral suspension (O.S.), 800 mg/day, versus placebo on weight in geriatric nursing home patients with weight loss or low body weight.

DESIGN

Twelve weeks, randomized, double-blind, placebo-controlled trial with a 13-week follow-up period.

PATIENTS

Northport VAMC Nursing home patients with weight loss of * 5% of usual body weight over the past 3 months, or body weight 20% below their ideal body weight.

INTERVENTIONS

Patients were randomly assigned to receive placebo or MA 800 mg/d for 12 weeks and were then followed for 13 weeks off treatment and mortality 4 years post treatment.

MEASUREMENTS

Primary outcome- weight and appetite change. Secondary outcome-sense of well being, enjoyment of life, change in depression scale, laboratory nutrition parameters, energy intake counts, body composition, and adverse events.

RESULTS

At 12 weeks there were no significant differences in weight gain between treatment groups, while MA-treated patients reported significantly greater improvement in appetite, enjoyment of life, and well being. At week 25 (3 months after treatment), 61.9% of MA-treated patients had gained * 1.82 kg (4 lbs) compared to 21.7% of placebo patients. There was no difference in survival between MA and placebo groups. Considering possible confounders, higher initial IL-6, initial TNFR-p75 levels, and final neutrophil percentage were associated with elevated mortality, whereas higher initial pre-albumin, initial albumin, final pre-albumin, final albumin and final weight gain were associated with decreased death.

The omega-3 fatty acid, eicosapentaenoic acid (EPA), prevents the damaging effects of tumour necrosis factor (TNF)-alpha during murine skeletal muscle cell differentiation

Background

Eicosapentaenoic acid (EPA) is a ώ-3 polyunsaturated fatty acid with anti-inflammatory and anti-cachetic properties that may have potential benefits with regards to skeletal muscle atrophy conditions where inflammation is present. It is also reported that pathologic levels of the pro-inflammatory cytokine tumour necrosis factor (TNF)-α are associated with muscle wasting, exerted through inhibition of myogenic differentiation and enhanced apoptosis. These findings led us to hypothesize that EPA may have a protective effect against skeletal muscle damage induced by the actions of TNF-α.

Results

The deleterious effects of TNF-α on C2C12 myogenesis were completely inhibited by co-treatment with EPA. Thus, EPA prevented the TNF-mediated loss of MyHC expression and significantly increased myogenic fusion (p < 0.05) and myotube diameter (p < 0.05) indices back to control levels. EPA protective activity was associated with blocking cell death pathways as EPA completely attenuated TNF-mediated increases in caspase-8 activity (p < 0.05) and cellular necrosis (p < 0.05) back to their respective control levels. EPA alone significantly reduced spontaneous apoptosis and necrosis of differentiating myotubes (p < 0.001 and p < 0.05, respectively). A 2 hour pre-treatment with EPA, prior to treatment with TNF alone, gave similar results.

Conclusion

In conclusion, EPA has a protective action against the damaging effects of TNF-α on C2C12 myogenesis. These findings support further investigations of EPA as a potential therapeutic agent during skeletal muscle regeneration following injury.

Identification of rat brainstem neuronal structures activated during cancer-induced anorexia

In cancer-related anorexia, body weight loss is paradoxically associated with reduced appetite, which is contrary to the situation during starvation, implying that the normal coupling of food intake to energy expenditure is disarranged. Here we examined brainstem mechanisms that may underlie suppression of food intake in a rat model of cancer anorexia. Cultured Morris 7777 hepatoma cells were injected subcutaneously in Buffalo rats, resulting in slowly growing tumor and reduced food intake and body weight loss after about 10 days. The brainstem was examined for induced expression of the transcription factors Fos and FosB as signs of neuronal activation. The results showed that anorexia and retarded body weight growth were associated with Fos protein expression in the area postrema, the general visceral region of the nucleus of the solitary tract, and the external lateral parabrachial nucleus, structures that also display Fos after peripheral administration of satiating or anorexigenic stimuli. The magnitude of the Fos expression was specifically related to the size of induced tumor, and not associated with weight loss per se, because it was not present in pair-fed or food-deprived rats. It also appeared to be independent of proinflammatory cytokines, as determined by the absence of increased cytokine levels in plasma and induced cytokine and cyclooxygenase expression in the brain. The findings thus provide evidence that cancer-associated anorexia and weight loss in this model is associated with activation of brainstem circuits involved in the suppression of food intake, and suggest that this occurs by inflammatory-independent mechanisms.

Anorexia in cancer: role of feeding-regulatory peptides

Anorexia is one of the most common symptoms in advanced cancer and is a frequent cause of discomfort for cancer patients and their families. The pathogenesis of cancer anorexia is multi-factorial and involves most of the hypothalamic neuronal signalling pathways modulating energy homeostasis. It is considered to be the result of a failure of usual appetite and satiety signals. Loss of appetite can arise from decreased taste and smell of food, as well as from dysfunctional hypothalamic signalling pathways and cytokine production. Cytokines in particular, appear to play a key role in energy balance through persistent activation of the melanocortin system and inhibition of the neuropeptide Y pathway. The imbalance between anorexigenic and orexigenic peptides leads to suppression of appetite, and increased satiety and satiation associated with marked weight loss and decline in physical performance. High levels of serotonin also appear to contribute to these effects and recent findings implicate corticotropin-releasing factor in the pathogenesis of cancer anorexia as well. Despite significant advances in our understanding of the regulation of food intake and energy expenditure, few effective therapies are available. A better appreciation of the molecular and neuronal mechanisms that control body weight homeostasis may lead to the development of new therapies for improving the survival and quality of life of these patients.

Neopterin as an indicator of immune activation and prognosis in patients with gynecological malignancies

Malignant tumors may contribute to host response that involves both the adaptive and innate immune systems. Among other biochemical indicators of systemic immune and inflammatory activity, activation of macrophages by interferon-gamma induces a marked increase in the production of neopterin. Neopterin production by activated macrophages is also associated with tryptophan degradation. In addition to tumors of other primary locations, increased urinary and serum neopterin concentrations have been reported in patients with gynecological cancers, including epithelial ovarian carcinoma, cervical carcinoma, endometrial carcinoma, uterine sarcomas, and vulvar carcinoma, but not in women with benign neoplasms or precancerous disorders. Increased neopterin concentrations have been associated with poor prognosis. Elevated levels of neopterin have also been observed in the tumor microenvironment. Systemic (urinary or serum) or local (ascitic fluid) neopterin concentrations increased after therapeutic administration of cytokines. Elevated neopterin concentrations have been associated with anemia of chronic disease and increased urinary zinc loss in patients with gynecological malignancy. Elevated neopterin has also been connected with depressed function of peripheral blood lymphocytes and a decrease in CD4+ T-cell numbers.

The causes and consequences of cancer-associated malnutrition

Cancer-associated malnutrition can result from local effects of a tumour, the host response to the tumour and anticancer therapies. Although cancer patients often have reduced food intake (due to systemic effects of the disease, local tumour effects, psychological effects or adverse effects of treatment), alterations in nutrient metabolism and resting energy expenditure (REE) may also contribute to nutritional status. Several agents produced by the tumour directly, or systemically in response to the tumour, such as pro-inflammatory cytokines and hormones, have been implicated in the pathogenesis of malnutrition and cachexia. The consequences of malnutrition include impairment of immune functions, performance status, muscle function, and quality of life. In addition, responses to chemotherapy are decreased, chemotherapy-induced toxicity and complications are more frequent and severe, and survival times are shortened. Depression, fatigue and malaise also significantly impact on patient well-being. In addition, cancer-related malnutrition is associated with significant healthcare-related costs. Nutritional support, addressing the specific needs of this patient group, is required to help improve prognosis, and reduce the consequences of cancer-associated nutritional decline.

Catabolic outcome from non-gastrointestinal malignancy-related malabsorption leading to malnutrition and weight loss

PURPOSE OF REVIEW

Malnutrition of cancer patients is a significant cause of mortality and morbidity.

RECENT FINDINGS

The contributory factors in cancers anatomically involving the gastrointestinal tract are self-evident. However, how non-gastrointestinal malignancies affect gastrointestinal structure and function is not clear. The aim of this paper is to review the relationship between non-gastrointestinal malignancies and malabsorption, which leads to malnutrition, weight loss and increased mortality. In non-gastrointestinal cancer patients, intestinal morphological atrophy occurs, whereas in the jejunum absorption is impaired. Cytokines including IL-1 and TNF-alpha primarily induce delayed gastric emptying and also act directly on intestinal mucosa to induce malabsorption. These cytokines also directly act on several gastrointestinal hormones including cholecystokinin, neuropeptides including corticotropin-releasing factor, and via the vagus to decrease gastrointestinal motility.

SUMMARY

The combination of small intestine atrophy and delayed gastrointestinal motility are some of the reasons for malabsorption in cancer patients with non-gastrointestinal malignancies that contribute to the catabolic process.

Multifaceted roles of TNF-alpha in myoblast destruction: a multitude of signal transduction pathways

In catabolic conditions, such as cancer cachexia, a balance favouring a cytokine environment culminates in muscle destruction. Utilising an in vitro model to mimic muscle wasting, we elucidate here the multifaceted roles that one such cytokine, TNF-alpha, invokes in the degeneration process. Treatment of C2 skeletal myoblasts with TNF-alpha not only suppresses morphological and biochemical differentiation, but following an initial wave of proliferation, and of survival (24 h), induces apoptosis. Investigating the mechanisms underlying these diverse actions of TNF-alpha, we demonstrate that cell replication is dependent on rapid and sustained activation of MAP kinase. Map kinase is not, however, central to the death process, which is associated with a progressive rise in caspase-8 activity, and is accompanied by sustained activation of JNK1 and transient activation of JNK2. Caspase inhibition caused a dose responsive reduction in cell death, while inhibition of the JNKs caused a significant increase in apoptosis. We further report that PI3 kinase is not involved in conferring early protection against TNF-alpha-induced death. By contrast, inhibition of NF-kappaB in the presence of TNF-alpha culminates in increased cell cycle progression, decreased gadd45beta expression and significant and precociously increased cell death, when compared with TNF-alpha alone. Our results begin to characterise the mechanisms underlying the acute mitogenic and anti-apoptotic roles of TNF-alpha, which appear to be defined by a balance between MAP kinase, Jun kinase (JNK), NF-kappaB and gadd45beta. They establish that inhibition of any one of these molecules, as may occur following caspase activation, could eliminate vital stem cells required for skeletal muscle regeneration during chronic catabolic conditions.

Insulin-like growth factor-1 and interleukin 6 predict sarcopenia in very old community-living men and women: the Framingham Heart Study

OBJECTIVES

To assess the prognostic role of the inflammatory cytokine, interleukin 6 (IL-6), and insulin-like growth factor-1 (IGF-1) in predicting 2-year changes in fat-free mass (FFM) while controlling for potential confounders.

DESIGN

Population-based cohort, the Framingham Heart Study, examined in 1992-93 and 1994-95.

SETTING

General community.

PARTICIPANTS

Two hundred thirty-two men and 326 women aged 72 to 92.

MEASUREMENTS

IGF-1 was measured using radio-immunoassay and cellular IL-6 production using non-cross-reacting radioimmunoassays. FFM was estimated using population-specific equations for predicting FFM from bioelectrical impedance analysis developed separately for men and women.

RESULTS

Higher IGF-1 predicted smaller loss of FFM in men than lower IGF-1 did (P=.002), after adjusting for age, baseline FFM, fat mass, and 2-year weight changes, whereas cellular IL-6 was a significant predictor of sarcopenia in women (P=.02). Weight change was a strong determinant of change in FFM in both sexes (P<.0001).

CONCLUSION

Predictors of sarcopenia include body composition characteristics that are common to men and women and sex-specific metabolic predictors. Sarcopenia appears to reflect a withdrawal of anabolic stimuli, such as growth hormone, in men but an increase in catabolic stimuli, such as cellular IL-6, in women.

Managing cancer-related anorexia/cachexia

Cancer-related anorexia/cachexia (CAC) is a complex phenomenon in which metabolic abnormalities, proinflammatory cytokines produced by the host immune system, circulating tumour-derived catabolic factors, decreased food intake, and probably additional unknown factors, all play different roles. This review examines the mechanisms of CAC and its management. All the potential modalities of intervention from nutritional to pharmacological approaches are included with a clear distinction between unproven, investigational and well established treatments. Among the latter, the progestogens are currently considered the most effective and safest drugs for the management of CAC. Agents currently under investigation for CAC include thalidomide, pentoxifylline and melatonin, which most probably act on cytokine release, and clenbuterol, which acts on muscle mass and to antagonise protein wasting. Our personal experience with the synthetic progestogens megestrol and medroxyprogesterone supports their use as first-line agents. In addition, our work on the potential role of antioxidant agents in counteracting the oxidative stress, which appears to be involved in CAC, shows them to be promising agents when used in combination chemotherapy regimens either alone or with other 'biologics'. There is an ongoing need for quality of life questionnaires which specifically address the most significant symptoms present in patients with CAC.

The correlation of cytokine levels with body weight after megestrol acetate treatment in geriatric patients

BACKGROUND

Cachexia is associated with elevated levels of cytokines in cancer and human immunodeficiency virus patients. Studies in cancer and acquired immunodeficiency syndrome patients showed that treatment with megestrol acetate (MA) is associated with improvement in appetite and weight gain. Reduction in the levels of cytokines is associated with weight gain in laboratory animals with cancer. This study evaluates the correlation between changes in cytokine (or their receptor) levels and weight following MA treatment in geriatric weight-loss patients.

METHODS

Veterans Administration Medical Center nursing home patients (N = 69) with a weight loss of > or =5% of usual body weight over the past 3 months or body weight 20% below their ideal body weight participated in a 12-week, randomized, double-blind, placebo-controlled trial, with an additional 13-week follow-up period. Patients were randomly assigned to receive a placebo or MA oral suspension of 800 mg/d for 12 weeks. Levels of the following cytokines (or their receptors) were measured at baseline and after 12 weeks of treatment: tumor necrosis factor soluble receptor (TNFR) subunits. TNFR-p55 and TNFR-p75: interleukin 6 (IL-6); and the soluble interleukin-2 receptor (sIL-2R). The subjects' weight and body composition were measured at the start of the study. Weight and mortality were followed up for another 13 weeks after discontinuing the MA study drug.

RESULTS

Elevated levels of IL-6 in almost all geriatric cachexic patients, compared with normal volunteers (mean, <4.6 pg/ml). were noted at baseline. At 12 weeks after the study drug treatment, there was a decrease in cytokine levels (or their receptors) in the MA group (mean change in IL-6, 3.63+/-6.62 pg/ml; TNFR-p55, -0.06+/-0.11 ng/ml; TNFR-p75. -0.01+/-0.29 ng/ml; and sIL-2R, 0.08+/-0.07 ng/ml) and the placebo group (mean change in IL-6, -2.08+/-3.92 pg/ml; TNFR-p55, -0.02+/-0.08 ng/ml; TNFR-p75, -0.20+/-0.18 ng/ml; and sIL-2R, 0.02+/-0.03 ng/ml). Although the change in cytokine levels was not statistically significant between the two groups, significant negative correlation (p < .05) was found. For example, increased weight correlated with decreased sIL-2R levels (r = .36) and TNFR-p75 (r = -.31; fat-free mass (FFM) gain and reduction of sIL-2R (r = -.39), TNFR-p75 (r = -.30). There was a significant correlation between weight gain and reduction of TNFR-p75 (r = .54), TNFR-p55 (r- = .47), and sIL-2R (r = -.53); FFM gain and reduction of sIL-2R (r = -.59), TNFR-p75 (r = -.41), TNFR-p55 (r = -.42); and fat gain and reduction of TNFR-p75 (r = -.41) in the MA group (p < .05), but not in the placebo group.

CONCLUSIONS

Although there was no significant change in cytokine levels between the two groups, the reduction in cytokine levels after MA treatment correlated with improvement in weight, fat mass, and FFM at 12 weeks.

Survival of malnourished head and neck cancer patients can be predicted by human leukocyte antigen-DR expression and interleukin-6/tumor necrosis factor-alpha response of the monocyte

BACKGROUND

Patients with advanced stages of head and neck cancer are often characterized by malnutrition and by an impaired immune system. Because some of the suppressed immune parameters were shown to be of prognostic importance in trauma and sepsis, we investigated whether these would also correlate with survival in head and neck cancer.

METHODS

Severely malnourished head and neck cancer patients undergoing ablative and reconstructive surgery were followed prospectively and their perioperative immune parameters were related to long-term survival.

RESULTS

Forty-nine patients with a preoperative weight loss of more than 10% were followed up for a period of at least 16 months after surgery. Analyses of variance revealed that preoperative human leukocyte antigen-DR (HLA-DR) expression on monocytes and endotoxin-induced production of tumor necrosis factor-alpha (TNF-alpha) and interleukin-6 (IL-6) were different between patients who survived and patients who died. Proportional hazards identified a weight loss of more than 12%, the presence of coexistent disease, and an HLA-DR expression on monocytes below the cutoff points (mean fluorescence index < 15, peak channel index < 9) to be of significant influence on survival.

CONCLUSIONS

In addition to known prognostic parameters such as tumor stage, coexistent disease, and weight loss, the immune parameters HLA-DR expression on monocytes and endotoxin-induced cytokine production may carry prognostic value in cancer patients. Immunomodulating therapies leading to improvement of these parameters might in the future lead to increased options for treatment.

Nutrition in cancer: an overview

OBJECTIVES

To provide a review of weight loss, cachexia (both primary and secondary), and weight gain in cancer patients.

DATA SOURCES

Research reports, review articles, textbooks, and personal communications.

CONCLUSIONS

Alterations in nutritional status have the potential to affect mortality, morbidity, and quality of life outcomes. The detection and treatment of malnutrition is important to success of therapy.

IMPLICATIONS FOR NURSING PRACTICE

Nursing interventions to help maintain optimal nutritional status in patients with cancer include careful assessment, identification of patients at risk, and management of problems before the initiation of therapy.

Results of a dose-intense phase 1 study of a combination chemotherapy regimen with cisplatin and epidoxorubicin including medroxyprogesterone acetate and recombinant interleukin-2 in patients with inoperable primary lung cancer

Based on the role of cytokines in the pathogenesis of cancer-related anorexia-cachexia and the ability of progestins, such as medroxyprogesterone acetate, to reduce cytokine production and relieve cancer-related anorexia-cachexia symptoms, the authors designed an open, dose-finding phase I study of a combined chemotherapy regimen (cisplatin [CDDP], epidoxorubicin [EPI]), including recombinant interleukin-2 (IL-2) and medroxyprogesterone acetate for patients with stage IIIB to IV inoperable primary lung cancer. The end points were clinical response and toxicity with definition of dose-limiting toxicity and maximal tolerable dose; relief of cancer-related anorexia-cachexia symptoms; the assessment of patient serum levels of IL-1beta, IL-6, tumor-necrosing factor-alpha (TNF-alpha), and soluble IL-2 receptor (sIL-2R). From March to October 1997, 16 patients (M:F ratio, 14:2; mean age, 60.5 years; age range, 41 to 74 years) were enrolled. All patients were evaluable for toxicity and 14 of them for response. The patients were assigned to increasing dose levels of drugs according to a dose-escalation schedule. The weekly schedule consisted of a combination of CDDP given intravenously on day 1, EPI given intravenously on day 1, 1 g/day medroxyprogesterone acetate given orally on days 1 to 7, and recombinant IL-2 1.8 MIU administered subcutaneously on days 2 to 7 plus 300 microg granulocyte-colony stimulating factor support given subcutaneously on days 2 to 5. Administration of medroxyprogesterone acetate began 1 week before the first cycle. Dose escalation of the drugs was as follows: 30 mg x m2 x week(-1) CDDP and 25 mg x m2 x week(-1) EPI (first level, two patients); 30 mg x m2 x week(-1) CDDP and 33 mg x m2 x week(-1) EPI (second level, 2 patients); 40 mg x m2 x week(-1) CDDP and 33 mg x m2 x week(-1) EPI (third level, 6 patients); and 40 mg x m2 x week(-1) CDDP and 40 mg x m2 x week(-1) EPI (fourth level, 6 patients). Six cycles were planned for each patient. The actual dose intensity delivered was more than 80% of the projected dose intensity of all drugs. After six cycles, clinical response (according to World Health Organization criteria), toxicity (according to World Health Organization criteria), Eastern Cooperative Oncology Group (ECOG) performance status, body weight, appetite, and serum levels of cytokines were evaluated. After six cycles, 9 of 14 patients (64.3%) had partial response, 3 of 14 (21.4%) had stable disease, and 2 of 14 (14.3%) had progressive disease, and the objective response rate was 64.3%. ECOG performance status and body weight did not change significantly after treatment, whereas appetite showed an increase that was of borderline statistical significance. Toxicity was acceptable and only hematologic. Dose-limiting toxicity was established at the fourth dose level; consequently, maximal tolerable dose was assessed at the third dose level. Before treatment, the serum levels of IL-1beta, IL-6, and TNF-alpha were significantly greater in the patients than in healthy persons. The comparison between pretreatment and posttreatment serum values of IL-1beta, IL-6, TNF-alpha, and sIL-2R did not reveal significant differences in the patients. Similar results were obtained when the patients were considered as responders (partial response) or non-responders (stable or progressive disease) to therapy. Only IL-6 serum levels were increased (p = 0.014) after treatment.

Geriatric cachexia: the role of cytokines

Weight loss in elderly patients is a common clinical problem. Wasting and cachexia are associated with severe physiologic, psychologic, and immunologic consequences, regardless of the underlying causes. Cachexia has been associated with infections, decubitus ulcers, and even death. Multivariate analyses of risk and prognostic factors in community-acquired pneumonia in the elderly have found that age by itself is not a significant factor related to prognosis. Among the significant risk factors, only nutritional status is amenable to medical intervention. Cachexia in the elderly may have profound consequences: medical, cognitive, and psychiatric disorders may diminish self-reliance in activities of daily living, thus reducing quality of life and increasing the frequency of secondary procedures, hospitalizations, and the need for skilled care. Cachexia is associated with higher-than-normal concentrations of tumor necrosis factor alpha (TNF-alpha), interleukin (IL) 1, IL-6, serotonin, and interferon gamma. The role of these proinflammatory cytokines has been established in the cachexia seen in cancer and AIDS patients. Reduction in the concentrations of these cytokines is associated with weight gain. Drugs that promote appetite stimulation and weight gain, such as progestational agents, cyproheptadines, pentoxifylline, and thalidomide may work by down-regulating these proinflammatory cytokines. An understanding of the relation between cachexia and negative regulatory cytokines may point to effective treatment of geriatric cachexia as well.

Enteral nutrition in wasting disorders

Cachexia, weight loss, and malnutrition are found commonly in patients with gastrointestinal tract cancer and in patients with human immunodeficiency virus. This wasting has been linked not only to survival, but also to alterations in host defenses, functional ability, and quality of life in these patients. Enteral nutritional support has been provided to these patients with the goal of preventing or correcting malnutrition in an attempt to improve measures of mortality, morbidity, and quality of life. Studies presented in this review have examined the impact of the timing, the composition, and the route of nutritional support on these outcome variables to evaluate the use of enteral nutritional support in these wasting disorders. There remains a paucity of strong clinical evidence that supports any improvements in outcome variables associated with the provision of enteral nutritional support in these patients.

Total parenteral nutrition and home parenteral nutrition: an effective combination to sustain malnourished children with cancer

A patient with Wilms' tumor and severe failure to thrive required total parenteral nutrition (TPN) for "catch-up" growth. This case underscores how TPN might be useful in the management of a child with cancer. Cancer cachexia, chemotherapy, radiation, and infections caused by immune suppression can lead to potentially serious macro- and micronutrient deficiencies.

Circulating interleukin 6 concentrations and insulin resistance in patients with cancer

BACKGROUND

The mechanism of insulin resistance in patients with cancer is not clear. This study was conducted to evaluate the possible role of circulating cytokines in inducing insulin resistance in patients with cancer.

METHODS

Twenty-three patients with a variety of cancers were studied, including one patient with oesophageal cancer, 12 with gastric cancer, four with colon cancer and six with lung cancer. Six normal volunteers served as controls. Insulin resistance was evaluated by euglycaemic hyperinsulinaemic glucose clamp with a high physiological insulin concentration of 100 microunits/ml. Metabolized glucose, the M value, was compared between patients with cancer and controls. Serum concentrations of interleukin (IL) 6 and other cytokines (tumour necrosis factor (TNF) alpha, IL-8 and IL-10) were measured by enzyme-linked immunosorbent assay.

RESULTS

The mean(s.d.) M value for patients with cancer (5.47(1.59) mg per kg per min) was significantly lower than that for controls (8.23(0.79) mg per kg per min) (P< 0.001). There was no relationship between the M value and degree of body-weight loss. Serum IL-6 concentration was measurable in eight of 23 patients: four with lung cancer, two with gastric cancer, and one each with oesophageal and colon cancer. None of the controls had a measurable serum IL-6 concentration. There was no significant relationship between serum IL-6 concentration and body-weight loss. TNF-alpha was undetectable in the serum of both patients with cancer and controls. Serum IL-8 and IL-10 were detected in seven and one of 23 patients respectively. These cytokines were not detected in the serum of controls. The M value was significantly smaller in those with measurable serum IL-6 (4.01(1.22) mg per kg per min) than in those with no measurable IL-6 (6.26(1.16) mg per kg per min) (P< 0.001). IL-6 and IL-8 levels were raised more frequently in the same patient but there was no significant relationship between IL-8 and M values.

CONCLUSION

These results may suggest that IL-6 is related to insulin resistance in patients with cancer.

Levels of HIV RNA are quantitatively related to prior weight loss in HIV-associated wasting

Thirty-three patients referred to a wasting clinic were evaluated to assess whether levels of HIV RNA were related to the magnitude of prior weight loss. Their median RNA level was 46,887 gene copies/ml (range, <200-510,070 gene copies/ml) at the time of referral. Patients had lost 10.5 +/- 6.4 kg over 461 +/- 304 days. RNA levels were correlated with the absolute amount and percentage of weight lost as well as the difference in body mass index (BMI) at the prior maximal and minimal recorded weights (r = 0.7, 0.67, 0.69; p = .0001 for the comparisons). The magnitude of these changes increased across strata of HIV RNA levels (p < or = .004), previously defined as associated with increasing risk for disease progression. The other parameter that could be associated with weight loss was the CD4 lymphocyte count (r = -0.43; p = .01). Low levels of testosterone and measures of body cell mass, fat free mass, or fat mass within 6 weeks of the RNA level could not be related to weight loss, change in BMI, or RNA levels. Thirty-two of the patients had chronic, relentless weight loss; in 15 of these subjects, no apparent secondary opportunistic complications were associated with weight loss or gastrointestinal symptoms to impair energy intake. Levels of HIV replication appear to be causally related to the magnitude of weight loss in some patients with wasting.

Malnutrition associated with HIV/AIDS. Part One: Definition and scope, epidemiology, and pathophysiology

A documented association exists between nutritional status and immunologic function, development, and outcome of infectious processes, and treatment-related toxicity and vital organ function. In persons with AIDS, nutritional deficits precipitate a cycle that results in a downward spiral of weight lost, malabsorption, diarrhea, anorexia, body image disturbance, and increased risk for morbidity and mortality. This article presents an overview of the malnutrition in HIV/AIDS patients. It critiques the current Centers for Disease Control's definitions of wasting syndrome, describes the incidence of weight loss, delineates the implications of untreated malnutrition, and traces the etiology of weight loss and contributing factors. This article serves as an introduction to HIV/AIDS related malnutrition. A subsequent article will review nursing implications and clinical management programs.

Tumor growth, weight loss and cytokines in SCID mice

It has been proposed that immunoregulatory cytokines play a role in the onset and development of cancer cachexia, although evidence supporting this theory remains inconclusive. In the present study, SCID mice were implanted with one of two tumor cell lines known to induce weight loss in rats. Growth of the Morris 7777 hepatoma was associated with weight loss as well as increased levels of tumor necrosis factor and interleukins 1 and 6 in spleen cells of tumor-bearing mice. Growth of the MCA sarcoma did not induce weight loss, nor did it increase cytokine expression in spleen cells of tumor-bearing mice. We conclude that increased cytokine expression is associated with weight loss in tumor-bearing SCID mice, and immune activation for cytokine expression does not require the presence of T or B cells.

Cachexia and anorexia in malignancy

The cancer cachexia syndrome may be present in up to 80% of patients with cancer. Malnutrition resulting from cancer cachexia is a significant cause of morbidity and mortality. Anorexia, tissue wasting, and weight loss appear to be the result of metabolic abnormalities caused by host cytokine production in response to the tumor. The host cytokines include TNF-alpha, IL-1, IL-6, IFN-gamma, and D-factor. Nutritional support in the patient with cancer has been controversial, with the belief that tumor growth may be augmented; however, human studies fail to confirm that tumor growth occurs in excess of normal tissue growth. The efficacy of nutritional support in the cancer has not been adequately studied. Considerable interest exists in providing nutritional support pharmacologically to modify the response to malignancy.

From laboratory to bedside: new strategies in the treatment of malnutrition in cancer patients

The objective of this review is to present and discuss the current and the possible future perspectives of artificial nutrition in preventing and treating cancer cachexia. English-language studies published in the last 25 years were retrieved using MEDLINE, bibliographies and consultation with experts. MEDLINE search terms included "cancer," "malnutrition," and "nutritional support." In vivo and in vitro controlled studies were selected, and data from each study were independently abstracted by the authors. Data obtained indicate that cancer cachexia is a common manifestation of advanced malignant disease, characterized by marasmus due to impaired nutrient metabolism, weight loss, and anemia. In patients, the presence of cachexia increases morbidity and mortality, delays or impedes the delivery of the adequate treatment, reduces the efficacy of anti-neoplastic therapy, and impairs patient's quality of life. Indirect evidence indicates that cancer cachexia is mediated by circulating cytokines, produced by the host in response to the presence of the malignancy. In the past two decades, nutritional support was used to counteract the detrimental effect of cancer cachexia on the host, but with limited success. More recently, the better understanding of the mechanisms of cancer cachexia and the identification of pharmacologic effects provided by specific nutrients, has formed the rationale for a "new" mode of nutrition therapy/nutritional support, adding pharmacotherapy to adjunctive initial care.

Studies on the regulation of food intake using rat total parenteral nutrition as a model

Total parenteral nutrition (TPN) is essential for maintaining the nutritional status of patients who are unable to eat sufficiently to meet their metabolic needs. However, TPN suppresses appetite and ultimately diminishes food intake. Theories concerning the role(s) of peripheral metabolites as signals, acting via the liver and the hypothalamus, for the metabolic control of food intake, have been put forward to explain the anorectic effect of TPN. In addition, it is postulated that changes in peripheral metabolites during TPN may be translated into changes in the levels of brain neurotransmitters known to decrease food intake. This review summarizes studies concerning the effect of TPN on food intake. These studies have involved: (1) characterizing the changes in feeding activity due to TPN; (2) investigating the involvement of the central nervous system; and (3) investigating the role of the periphery and its metabolites in the regulation of food intake during TPN. Some insight into the mechanism of action of TPN on food intake is provided.

Assessment of feeding response of tumor-bearing rats to hypothalamic injection and infusion of neuropeptide Y

Tumor-bearing rats exhibited significant decreases in 1- to 4-h intake of rat chow following the intrahypothalamic injection of 2 micrograms neuropeptide Y (NPY). This refractory feeding response was present prior to the onset of anorexia and became more severe as anorexia worsened. The constant infusion of NPY (125 ng/h) into the perifornical hypothalamus of TB and control rats elicited increased feeding for only 2 days. Because chromatography revealed minipump NPY to be intact after 10 infusion days, downregulation of NPY receptors may have occurred. Daily injection of increasing doses of NPY stimulated ad lib feeding in non-TB rats, while having no effect on TB rats. Desensitization to NPY-induced feeding following daily injections of the peptide was suggested by the loss of feeding response to a dose (500 ng) of NPY that increased food intake prior to the daily NPY treatments. These results suggest that hypothalamic NPY feeding systems are refractory in TB rats, even before they exhibit anorexia. In addition, a rapid loss of the feeding response occurred in rats with constant infusion of NPY into hypothalamic tissue or with daily intrahypothalamic injections of the peptide, suggesting possible NPY receptor-mediated alterations. Therefore, control of obesity or anorexia through NPY feeding mechanisms may prove difficult due to rapid compensatory receptor changes.