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Query: UMLS:C0006625 (cachexia)
 5,650 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

There is, at present, considerable interest in the possible role for the proinflammatory cytokines, tumor necrosis factor-alpha, interleukin-1, interleukin-6, and interferon-gamma in the pathogenesis of cancer cachexia. Indirect evidence for such a role is based on the observation that chronic administration of many of these cytokines, either alone or in combination, can reproduce the myriad of host responses seen in experimental and human cancer cachexia. Elevated plasma levels of tumor necrosis factor-alpha, interleukin-2, and interferon-gamma have rarely been detected in patients or experimental animals with cancer, although interleukin-6 levels appear to correlate with tumor progression in animal models. The strongest evidence for a causal role for cytokines has come from rodent studies in which tumor-bearing animals have been passively immunized with antibodies directed against individual cytokines. Several groups have shown modest but significant improvements in food intake and lean tissue retention with antibodies directed against tumor necrosis factor-alpha, interleukin-1, interleukin-6, and interferon-gamma. However, there has been no consistent finding that one cytokine is universally involved in cancer cachexia in histologically distinct tumor models. One ominous finding in several tumor models has been that the endogenous production of cytokines appears to support tumor growth. Such findings raise the intriguing possibility that these cytokines, although contributors to tissue wasting and anorexia, may also serve the tumor as either direct or indirect cell growth factors.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:The role of cytokines in cancer cachexia. 128 23

Cancer cachexia describes a syndrome that consists of weight loss, and abnormalities in carbohydrate, protein, and lipid metabolism, which result in a state of persistent net negative energy balance. Patients suffering from cancer cachexia have a significantly shortened survival after cancer treatment. Recent experimental studies have focused on the belief that the mechanisms of cancer cachexia involve the host's production of inflammatory cytokines, which through broad physiologic actions ultimately lead to a chronic state of wasting, malnourishment, and death. Cytokines that have been thought to play a role in the pathophysiology of cachexia include tumor necrosis factor, interleukin-1, interleukin-6, interferon-gamma and differentiation factor. It has become clear that these cytokines have overlapping physiologic activities, which makes it likely that no single substance is the sole cause of cachexia in most cancer patients. Only further investigation may make it possible to more clearly define the role of cytokines in the pathophysiology of cancer cachexia. Specific strategies to reverse the cachectic effects of these substances may then be developed to ultimately improve cancer treatment.
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PMID:Cytokines and their role in the pathophysiology of cancer cachexia. 128 24

The immune system produces cytokines and other humoral factors to protect the host when threatened by inflammatory agents, microbial invasion, or injury. In some cases this complex defense network successfully restores normal homeostasis, but at other times the overproduction of immunoregulatory mediators may actually prove deleterious to the host. Some examples of immune system-mediated injury have been extensively investigated including anaphylactic shock, autoimmune disease, and immune complex disorders. More recently it has become clear that the cytokine cachectin/tumor necrosis factor (TNF) occupies a key role in the pathophysiology associated with diverse inflammatory states and other serious illnesses including septic shock and cachexia. For example, when cachectin/TNF is produced by resident macrophages during early microbial infection, it mediates an inflammatory response that may alienate and repel the attacking organisms. If the infection spreads, however, the subsequent release of large quantities of cachectin/TNF into the circulation may be catastrophic and trigger a state of lethal shock. These toxic effects occur by direct action of TNF on host cells and by the interaction with a cascade of other endogenous mediators including interleukin-1 and interferon-gamma. The biology of cachectin/TNF will be reviewed, along with the potential for modulating the effects of this pluripotent molecule in a variety of pathologic states.
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PMID:Inflammatory cytokines. 172 86

It is currently hypothesized that the mechanisms of cancer cachexia involve the host's production of inflammatory cytokines, which in turn orchestrate a series of complex interrelated steps that ultimately lead to a chronic state of wasting, malnourishment, and death (see Fig. 1). The metabolic changes seen in the tumor-bearing host are similar, but not identical, to those seen in sepsis and inflammation and appear to result from a generalized response of the host to the stimulus of invasion--the tumor. Although there are likely to be several humoral factors, of either host or tumor origin (see Fig. 1), involved in cancer cachexia, recombinant DNA methodology has provided sufficient amounts of only a few cytokines to enable careful investigation of their cachectic potential. TNF/cachectin has been most extensively studied and appears to play a clear role, because administration of low-dose continuous or escalating doses simulates changes associated with cancer cachexia. In addition, these cachectic changes have been blocked by a specific antisera. IL-1, IL-6, and interferon-gamma all have potential as mediators of cancer cachexia and more work is clearly indicated. It is possible that, given our current understanding of the mechanisms of cancer cachexia, it can be theorized that TNF, which causes many of the manifestations of cancer cachexia, and IL-1 are released by macrophages in response to tumor (see Fig. 1). Interferon-gamma appears to potentiate these effects and may also be necessary for the complete syndrome of cancer cachexia. IL-6 probably is released as another mediator, principally mediating the acute phase response seen in cancer cachexia. Other factors are certain to be involved. Further study into the mechanisms and possible treatment of cancer cachexia is needed, because a large proportion of cancer patients who are incurable by current therapies continue to suffer from this lethal wasting diathesis. Furthermore, specific strategies to reverse the cachectic changes associated with cancer will likely improve antitumor treatment.
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PMID:Mechanisms of cancer cachexia. 202 66

The clinical syndrome of cachexia is characterized by anorexia, continued losses of lean body mass, and altered carbohydrate and lipid metabolism. As early as the 1930s, this "chronic wasting" syndrome had been identified as the most frequent immediate cause of death in patients with cancer [Warren: Am J Med Sci 184:610-619, 1932]. At present, controversy remains as to the benefit of supplemental parenteral or enteral feedings in the nutritional repletion of cachectic cancer patients, since only selected patient groups have demonstrated clear benefit from their administration [Copeland et al.: Cancer 43:2108-2116, 1979; Copeland et al.: Cancer Res 37:2451-2456, 1977; Terepka and Waterhouse: Am J Med 20:225-238, 1956]. Despite having these advanced nutritional modalities firmly in our therapeutic armamentarium, the progression of cachexia in the nutritionally depleted cancer patient often continues unabated, and our ability to intervene successfully remains limited. This review proposes that host: tumor interactions lead to a nonspecific inflammatory response mediated in part by the chronic production and release of proinflammatory cytokines, including interleukin-1, tumor necrosis factor alpha, interleukin-6 and interferon-gamma, which antagonize the anabolic signals associated with enteral and parenteral nutrition support. Cytokine-mediated alterations can explain the inability of adequate dietary nitrogen and calories to result in lean tissue repletion. Based on this proposal, interrupting proinflammatory cytokine production or target organ action may be an appropriate therapeutic objective to improve nutrient utilization in patients with tumors.
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PMID:Cytokine-mediated alterations in host metabolism prevent nutritional repletion in cachectic cancer patients. 784 87

Anorexia, net proteolysis of skeletal muscle and consumption of body fat are hallmarks of the cachexia syndrome associated with chronic disease states. While inanition contributes to cachexia, this wasting diathesis has little in common with simple starvation. The cachexia syndrome is characterized by progressive weight loss and depletion of lean body mass in excess to that resulting from comparable caloric restriction. Accelerated mobilization and consumption of host protein stores from peripheral tissues occurs to support gluconeogenesis and acute phase protein synthesis [1, 2]. In contrast, simple starvation is associated with a relative sparing of lean tissue with the preferential consumption of fat. While the clinical manifestations of cachexia are readily apparent, identification of the specific mechanisms responsible for the development of cachexia remains an enigma. In recent years, interest has focused on the role that the immune system plays in the development of cachexia. Investigators initially hypothesized that the chronic production of two inflammatory cytokines, tumour necrosis factor alpha (TNF alpha) and/or interleukin-1 (IL-1), could explain the host non-specific responses resulting in cachexia [3-5]. Other pro-inflammatory cytokines, including interleukin-6 (IL-6) [6, 7] and interferon-gamma [8, 9], have been more recently proposed to be involved in this complex process. Although no consensus exists for the exclusive role of any one cytokine in the pathogenesis of cachexia, there is growing acceptance that the progression of cachexia results in part from the inappropriate release of one or more pro-inflammatory cytokines [10, 11]. In the present review, the current role of TNF alpha as a mediator of cachexia is examined.
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PMID:Tumor necrosis factor and cachexia: a current perspective. 788 18

Human immunodeficiency virus infection leads to a deregulated production of a number of cytokines. Some of them (IL-1, IL-6, TNF-alpha, interferon-gamma) are produced in increased amounts in vivo, whereas the production of IL-2 is decreased. This latter abnormality plays a pivotal role in the establishment of the immunodeficiency. Some cytokines (IL-1, IL-6, TNF-alpha) stimulate the in vitro replication of HIV, whereas others (mainly the interferons) inhibit it. The effect of cytokines in vivo in the spreading of HIV remains, however, largely unknown. Cytokines may also be involved in the development of many clinical manifestations associated with HIV infection. IL-1, IL-6 and TNF-alpha may play a role in tissue damages associated with opportunistic infections, in HIV-related encephalopathy and in cachexia. Cytokines, mainly IL-6, IL-10 and IL-13, may stimulate the growth of malignant cells during Kaposi sarcoma or lymphomas. Better knowledge of the role of cytokines during HIV infection should allow new therapeutic approaches based on the use of either recombinant cytokines or specific antagonists, with the aim of limiting both HIV spreading and the clinical manifestations of this infection.
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PMID:Cytokines in HIV infection. 792 84

Microsporidia cause opportunistic infections in AIDS patients and commonly infect laboratory animals, as well. Euthymic C57B1/6 mice experimentally infected with intraperitoneal injections of 1 x 10(6) Encephalitozoon cuniculi Levaditi, Nicolau et Schoen, 1923, Encephalitozoon hellem Didier et al., 1991, or Nosema corneum Shadduck et al., 1990 displayed no clinical signs of disease. Athymic mice, however, developed ascites and died 8-16 days after inoculation with N. corneum, 21-25 days after inoculation with E. cuniculi, and 34-37 days after inoculation with E. hellem. All athymic mice displayed hepatomegaly, dilated intestine and accumulation of ascites fluid. Granulomatous lesions are primarily located in the liver, lung, pancreas, spleen, and on serosal surfaces of abdominal organs. The murine microsporidiosis model also was used to examine immune response that inhibit microsporidia growth in vitro. Recombinant murine interferon-gamma (mIFN-gamma, 100 mu/ml) alone or in combination with lipopolysaccharide (LPS; 10 ng/ml) could activate thioglycollate-induced peritoneal murine macrophages to destroy E. cuniculi. The production of the nitrogen intermediate, NO2-, correlated with parasite destruction. Inhibition of NO2- generation by addition of the L-arginine analogue, NG-monomethyl L-arginine (NMMA), inhibited microsporidia killing, as well. Since microsporidiosis is becoming an important opportunistic infection in AIDS patients, a microsporidiosis model is being developed using SIV/DeltaB670-infected rhesus macaque monkeys (Macaca mulatta). SIV-infected immunocompetent monkeys given E. cuniculi or E. hellem per os developed specific antibodies, and microsporidia could be detected sporadically by calcofluor or antibody fluorescence staining of stool and urine sediment smears. As immunodeficiency progressed, monkeys developed diarrhoea, cachexia, and anorexia, and organisms were detected in urine and stool with greater frequency. Immunodeficient SIV-infected monkeys died approximately 27 days after receiving E. hellem by intravenous inoculation, and approximately 110 days after receiving E. hellem per os. Lesions typical for SIV-infection were observed in both groups of monkeys and microsporidia were detected in kidney and liver of the intravenously-injected monkeys. The murine microsporidiosis model provides an efficient means for studying protective immune responses to microsporidiosis, and may prove useful for screening immunological and chemotherapeutic agents. The pathogenesis of Encephalitozoon microsporidiosis in SIV-infected monkeys appears to parallel encephalitozoonosis in AIDS patients, suggesting that simian microsporidiosis may provide a useful model for evaluating diagnostic methods and therapeutic strategies during various stages of progressing immunodeficiency.
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PMID:Experimental microsporidiosis in immunocompetent and immunodeficient mice and monkeys. 805 Jul 48

Besides their growth-inhibiting and differentiation-inducing properties, retinoids have been shown to exert immunomodulatory and anti-inflammatory functions by mechanisms that are not well understood. Tumor necrosis factor-alpha (TNF), a cytokine produced by mononuclear phagocytes, has been shown to be an important mediator of endotoxin-induced septic shock, cachexia, bone resorption, and inflammation. Nitric oxide may also have a role in septic shock, hypotension, and vasodilatation. In this study, we examined the effects of retinoids on the production of TNF and nitric oxide by murine peritoneal macrophages. Of the various retinoids studied, all-trans-retinoic acid (RA) was most potent; it almost completely inhibited the production of TNF by macrophages activated with endotoxin and interferon-gamma. The inhibitory effect was dependent on the dose and duration of RA exposure to macrophages. RA also blocked phorbol ester-induced TNF production in a macrophage cell line (RAW 264.7). Besides TNF, the retinoid suppressed the production of nitric oxide from activated peritoneal macrophages. The importance of these results in relation to controlling various harmful effects of cytokines released by activated macrophages is discussed.
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PMID:Inhibition by all-trans-retinoic acid of tumor necrosis factor and nitric oxide production by peritoneal macrophages. 812 Apr 50

Weight loss is the main symptom of so-called tumor cachexia. The pathogenetic mechanisms underlying cachexia are poorly understood; however, it appears that enhanced formation of cytokines such as interferon-gamma and tumor necrosis factor-alpha are involved. In 94 patients suffering from hematological neoplasias we compared body weight changes with serum neopterin, tryptophan, and kynurenine. Biochemical changes, the formation of neopterin, the degradation of tryptophan are closely related to interferon-gamma activity. The majority of our patients had increased neopterin and decreased tryptophan concentrations. Weight loss was seen particularly in patients with higher neopterin and lower tryptophan values. An association between higher neopterin levels and greater weight loss was apparent at study entry and during the follow-up of patients. Our data support the concept that weight loss is closely linked to endogenous interferon-gamma activity.
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PMID:Weight loss in patients with hematological neoplasias is associated with immune system stimulation. 845 58


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