Neural Mechanisms of Cancer Cachexia

Integrative metabolic profiling of hypothalamus and skeletal muscle in a mouse model of cancer cachexia

Cancer cachexia is a multifactorial metabolic syndrome characterized by progressive weight loss, muscle wasting, and systemic inflammation. Despite its clinical significance, the underlying mechanisms linking central and peripheral metabolic changes remain incompletely understood. In this study, we employed a murine model of cancer cachexia induced by intraperitoneal injection of Lewis lung carcinoma (LLC1) cells to investigate tissue-specific metabolic adaptations. Cachectic mice exhibited reduced food intake, body weight loss, impaired thermoregulation, and decreased energy expenditure. Metabolomic profiling of serum, skeletal muscle, and hypothalamus revealed distinct metabolic shifts, with increased fatty acid and ketone body utilization and altered amino acid metabolism. Notably, hypothalamic metabolite changes diverged from peripheral tissues, showing decreased neurotransmitter-related metabolites and enhanced lipid-based energy signatures. Gene expression analysis further confirmed upregulation of glycolysis- and lipid oxidation-related genes in both hypothalamus and muscle. These findings highlight coordinated yet compartmentalized metabolic remodeling in cancer cachexia and suggest that hypothalamic adaptations may play a central role in the systemic energy imbalance associated with cachexia progression.

A neuroimmune circuit mediates cancer cachexia-associated apathy

Cachexia, a severe wasting syndrome associated with inflammatory conditions, often leads to multiorgan failure and death. Patients with cachexia experience extreme fatigue, apathy, and clinical depression, yet the biological mechanisms underlying these behavioral symptoms and their relationship to the disease remain unclear. In a mouse cancer model, cachexia specifically induced increased effort-sensitivity, apathy-like symptoms through a cytokine-sensing brainstem-to-basal ganglia circuit. This neural circuit detects elevated interleukin-6 (IL-6) at cachexia onset and translates inflammatory signals into decreased mesolimbic dopamine, thereby increasing effort sensitivity. We alleviated these apathy-like symptoms by targeting key circuit nodes: administering an anti-IL-6 antibody treatment, ablating cytokine sensing in the brainstem, and optogenetically or pharmacologically boosting mesolimbic dopamine. Our findings uncovered a central neural circuit that senses systemic inflammation and orchestrates behavioral changes, providing mechanistic insights into the connection between chronic inflammation and depressive symptoms.

Cachexia Alters Central Nervous System Morphology and Functionality in Cancer Patients

BACKGROUND

Cachexia is a clinically challenging multifactorial and multi-organ syndrome, associated with poor outcome in cancer patients, and characterised by inflammation, wasting and loss of appetite. The syndrome leads to central nervous system (CNS) function dysregulation and to neuroinflammation; nevertheless, the mechanisms involved in human cachexia remain unclear.

METHODS

We used in vivo structural and functional magnetic resonance imaging (Cohort 1), as well as postmortem neuropathological analyses (Cohort 2) in cachectic cancer (CC) patients compared to weight stable cancer (WSC) patients. Cohort 1 included treatment-naïve adults diagnosed with colorectal cancer, further divided into WSC (n = 12; 6/6 [male/female], 61.3 ± 3.89 years) and CC (n = 10; 6/4, 63.0 ± 2.74 years). Cohort 2 was composed by human postmortem cases where gastrointestinal carcinoma was the underlying cause of death (WSC n = 6; 3/3, 82.7 ± 3.33 years and CC n = 10; 5/5, 84.2 ± 2.28 years).

RESULTS

Here we demonstrate that the CNS of CC patients presents regional structural differences within the grey matter (GM). Cachectic patients presented an augmented area within the region of the orbitofrontal cortex, olfactory tract and the gyrus rectus (coordinates X, Y, Z = 6, 20,-24; 311 voxels; pFWE = 0.023); increased caudate and putamen volume (-10, 20, -8; 110 voxel; pFWE = 0.005); and reduced GM in superior temporal gyrus and rolandic operculum (56,0,2; 156 voxels; pFWE = 0.010). Disrupted functional connectivity was found in several regions such as the salience network, subcortical and temporal cortical areas of cachectic patients (20 decreased and 5 increased regions connectivity pattern, pFDR < 0.05). Postmortem neuropathological analyses identified abnormal neuronal morphology and density, increased microglia/macrophage burden, astrocyte profile disruption and mTOR pathway related neuroinflammation (p < 0.05).

CONCLUSIONS

Our results indicate that cachexia compromises CNS morphology mostly causing changes in the GM of cachectic patients, leading to alterations in regional volume patterns, functional connectivity, neuronal morphology, neuroglia profile and inducing neuroinflammation, all of which may contribute to the loss of homeostasis control and to deficient information processing, as well as to the metabolic and behavioural derangements commonly observed in human cachexia. This first human mapping of CNS cachexia responses will now pave the way to mechanistically interrogate these pathways in terms of their therapeutic potential.

Association of Systemic Inflammation with Dietary Intake, Nutrition Impact Symptoms, and Eating-Related Distress Among Patients with Advanced Cancer

BACKGROUND

Serum C-reactive protein (CRP) levels are correlated with patient outcomes in cancer. This study aimed to determine associations between the CRP level and the dietary intake, symptoms, and eating-related distress (ERD).

METHODS

We conducted a multicenter survey among advanced cancer patients. Information on patient characteristics was retrieved from the electronic medical records. Data on patient outcomes were obtained through the questionnaire. Patients were categorized into the low CRP group (<5 mg/dL) and the high CRP group (≥5 mg/dL). Comparisons were calculated using the Mann-Whitney U test or chi-squared test. To assess associations between CRP levels and ERD, multivariate logistic regression analysis was performed.

RESULTS

A total of 191 patients were enrolled and divided into the low CRP group (n = 117) and the high CRP group (n = 74). The high CRP group had a more reduced dietary intake (p = 0.002) and more severe appetite loss (p = 0.008). The total scores of the ERD questionnaire (both the long and short versions) were significantly higher in the high CRP group (p = 0.040 and 0.029). The high CRP group also had significantly higher risks for ERD, as assessed using the long and short versions of the questionnaire (odds ratio [OR] 2.13, 95% confidence interval [CI] 1.10-4.11; OR 2.06, 95% CI 1.05-4.05).

CONCLUSIONS

High CRP levels were significantly associated with reduced dietary intake, appetite loss, and ERD. A serum CRP value of 5 mg/dL may be a useful indicator for initiating cancer cachexia care.

The area postrema: a critical mediator of brain-body interactions

The dorsal vagal complex contains three structures: the area postrema, the nucleus tractus solitarii, and the dorsal motor nucleus of the vagus. These structures are tightly linked, both anatomically and functionally, and have important yet distinct roles in not only conveying peripheral bodily signals to the rest of the brain but in the generation of behavioral and physiological responses. Reports on the new discoveries in these structures were highlights of the symposium. In this outlook, we focus on the roles of the area postrema in mediating brain-body interactions and its potential utility as a therapeutic target, especially in cancer cachexia.

Lipid Nanoparticles Elicit Reactogenicity and Sickness Behavior in Mice Via Toll-Like Receptor 4 and Myeloid Differentiation Protein 88 Axis

mRNA therapeutics encapsulated in lipid nanoparticles (LNPs) offer promising avenues for treating various diseases. While mRNA vaccines anticipate immunogenicity, the associated reactogenicity of mRNA-loaded LNPs poses significant challenges, especially in protein replacement therapies requiring multiple administrations, leading to adverse effects and suboptimal therapeutic outcomes. Historically, research has primarily focused on the reactogenicity of mRNA cargo, leaving the role of LNPs understudied in this context. Adjuvanticity and pro-inflammatory characteristics of LNPs, originating at least in part from ionizable lipids, may induce inflammation, activate toll-like receptors (TLRs), and impact mRNA translation. Knowledge gaps remain in understanding LNP-induced TLR activation and its impact on induction of animal sickness behavior. We hypothesized that ionizable lipids in LNPs, structurally resembling lipid A from lipopolysaccharide, could activate TLR4 signaling via MyD88 and TRIF adaptors, thereby propagating LNP-associated reactogenicity. Our comprehensive investigation utilizing gene ablation studies and pharmacological receptor manipulation proves that TLR4 activation by LNPs triggers distinct physiologically meaningful responses in mice. We show that TLR4 and MyD88 are essential for reactogenic signal initiation, pro-inflammatory gene expression, and physiological outcomes like food intake and body weight─robust metrics of sickness behavior in mice. The application of the TLR4 inhibitor TAK-242 effectively reduces the reactogenicity associated with LNPs by mitigating TLR4-driven inflammatory responses. Our findings elucidate the critical role of the TLR4-MyD88 axis in LNP-induced reactogenicity, providing a mechanistic framework for developing safer mRNA therapeutics and offering a strategy to mitigate adverse effects through targeted inhibition of this pathway.

Central neural mechanisms of cancer cachexia

PURPOSE OF REVIEW

Cachexia is a devasting syndrome which impacts a large number of patients with cancer. This review aims to provide a comprehensive overview of the central mechanisms of cancer cachexia. In particular, it focuses on the role of the central nervous system (CNS), the melanocortin system, circulating hormones and molecules which are produced by and act on the CNS and the psychological symptoms of cancer cachexia.

RECENT FINDINGS

A growing body of evidence suggests that a central mechanism of action underpins this multi-system disorder. Recent research has focused on the role of neuroinflammation that drives the sickness behaviour seen in cancer cachexia, with emphasis on the role of the hypothalamus. Melanocortin receptor antagonists are showing promise in preclinical studies. There are also new pharmacological developments to overcome the short half-life of ghrelin. GDF-15 has been identified as a core target and trials of compounds that interfere with its signalling or its central receptor are underway.

SUMMARY

Understanding the central mechanisms of cancer cachexia is pivotal for enhancing treatment outcomes in patients. While emerging pharmacological interventions targeting these pathways have shown promise, further research is essential.

Central activation of catecholamine-independent lipolysis drives the end-stage catabolism of all adipose tissues

Several adipose depots, including constitutive bone marrow adipose tissue (cBMAT), resist conventional lipolytic cues, making them metabolically non-responsive. However, under starvation, wasting, or cachexia, the body can eventually catabolize these stable adipocytes through unknown mechanisms. To study this, we developed a mouse model of brain-evoked depletion of all fat, including cBMAT, independent of food intake. Genetic, surgical, and chemical approaches demonstrated that depletion of stable fat required adipose triglyceride lipase-dependent lipolysis but was independent of local nerves, the sympathetic nervous system, and catecholamines. Instead, concurrent hypoglycemia and hypoinsulinemia activated a potent catabolic state by suppressing lipid storage and increasing catecholamine-independent lipolysis via downregulation of cell-autonomous lipolytic inhibitors Acvr1c, G0s2, and Npr3. This was also sufficient to delipidate classical adipose depots. Overall, this work defines unique adaptations of stable adipocytes to resist lipolysis in healthy states while isolating a potent in vivo neurosystemic pathway by which the body can rapidly catabolize all adipose tissues.

Anamorelin for the Treatment of Cancer Anorexia-Cachexia Syndrome

PURPOSE OF REVIEW

The following review will highlight the development of anamorelin to treat cancer anorexia-cachexia syndrome (CACS) including the potential benefits, limitations, and future directions.

RECENT FINDINGS

Ghrelin, a 28-amino acid peptide hormone, is secreted by the stomach mucosa and regulates appetite, promotes lipogenesis, increases body weight, improves gastric motility, reduces catabolic wasting and inflammation. Several randomized, double-blind, placebo-controlled clinical trials evaluating anamorelin, a ghrelin agonist, for the treatment of CACS have reported improvement in appetite and body composition including both lean body and fat mass; however, most studies noted no improvement in physical function as assessed by measuring non-dominant hand-grip strength. Common adverse effects of anamorelin include the development of diabetes mellitus, hyperglycemia, and less frequently, hepatic abnormalities and cardiovascular events including conduction abnormalities, hypertension, and ischemic cardiomyopathy. Anamorelin has the potential to stimulate appetite, improve gastric movement, and may have anti-inflammatory effects on patients with CACS. In patients with cancer, studies involving anamorelin combined with other multimodal treatments including nutrition counseling (branched chain amino acids, omega 3 fatty acids, and other nutrients), exercise, treatment of hormonal abnormalities including hypogonadism and hypovitaminosis D, and anti-inflammatory agents are needed. Compliance with multimodality treatment has been a barrier and future studies may need to incorporate motivational counseling to promote adherence.

Area postrema neurons mediate interleukin-6 function in cancer cachexia

Interleukin-6 (IL-6) has been long considered a key player in cancer cachexia. It is believed that sustained elevation of IL-6 production during cancer progression causes brain dysfunctions, which ultimately result in cachexia. However, how peripheral IL-6 influences the brain remains poorly understood. Here we show that neurons in the area postrema (AP), a circumventricular structure in the hindbrain, is a critical mediator of IL-6 function in cancer cachexia in male mice. We find that circulating IL-6 can rapidly enter the AP and activate neurons in the AP and its associated network. Peripheral tumor, known to increase circulating IL-6, leads to elevated IL-6 in the AP, and causes potentiated excitatory synaptic transmission onto AP neurons and AP network hyperactivity. Remarkably, neutralization of IL-6 in the brain of tumor-bearing mice with an anti-IL-6 antibody attenuates cachexia and the hyperactivity in the AP network, and markedly prolongs lifespan. Furthermore, suppression of Il6ra, the gene encoding IL-6 receptor, specifically in AP neurons with CRISPR/dCas9 interference achieves similar effects. Silencing Gfral-expressing AP neurons also attenuates cancer cachectic phenotypes and AP network hyperactivity. Our study identifies a central mechanism underlying the function of peripheral IL-6, which may serve as a target for treating cancer cachexia.

Addressing cancer anorexia-cachexia in older patients: Potential therapeutic strategies and molecular pathways

Cancer cachexia (CC) syndrome, a feature of cancer-associated muscle wasting, is particularly pronounced in older patients, and is characterised by decreased energy intake and upregulated skeletal muscle catabolic pathways. To address CC, appetite stimulants, anabolic drugs, cytokine mediators, essential amino acid supplementation, nutritional counselling, cognitive behavioural therapy, and enteral nutrition have been utilised. However, pharmacological treatments that have also shown promising results, such as megestrol acetate, anamorelin, thalidomide, and delta-9-tetrahydrocannabinol, have been associated with gastrointestinal and cardiovascular complications. Emerging evidence on the efficacy of probiotics in modulating gut microbiota also presents a promising adjunct to traditional therapies, potentially enhancing nutritional absorption and systemic inflammation control. Additionally, low-dose olanzapine has demonstrated improved appetite and weight management in older patients undergoing chemotherapy, offering a potential refinement to current therapeutic approaches. This review aims to elucidate the molecular mechanisms underpinning CC, with a particular focus on the role of anorexia in exacerbating muscle wasting, and to propose pharmacological and non-pharmacological strategies to mitigate this syndrome, particularly emphasising the needs of an older demographic. Future research targeting CC should focus on refining appetite-stimulating drugs with fewer side-effects, specifically catering to the needs of older patients, and investigating nutritional factors that can either enhance appetite or minimise suppression of appetite in individuals with CC, especially within this vulnerable group.

Harnessing the Systemic Biology of Functional Decline and Cachexia to Inform more Holistic Therapies for Incurable Cancers

Options for treatment of incurable cancer remain scarce and are largely focused on limited therapeutic mechanisms. A new approach specific to advanced cancers is needed to identify new and effective treatments. Morbidity in advanced cancer is driven by functional decline and a number of systemic conditions, including cachexia and fatigue. This review will focus on these clinical concepts, describe our current understanding of their underlying biology, and then propose how future therapeutic strategies, including pharmaceuticals, exercise, and rehabilitation, could target these mechanisms as an alternative route to addressing incurable cancer.

Evaluation of Anorexia in Cancer and Its Association with Autonomic Nervous System Activity Assessed by Heart Rate Variability

Alterations in the central nervous system in cancer patients are pivotal in determining appetite dysregulation and body weight loss (BWL). Autonomic nervous system activity was tested by measuring heart rate variability (HRV) in cancer patients presenting with anorexia. We considered inpatients with different types of cancer and investigated anorexia using their FAACT scores. HRV was evaluated by a three-channel Holter ECG. The domains of low frequencies (LF, sympathetic activity) and high frequencies (HF, parasympathetic activity) were calculated. Also, SDNN (autonomic activity) and RMSSD (parasympathetic activity) were assessed. We enrolled 56 patients with cancer and 23 controls. In cancer patients, RMSSD and SDNN were lower than in controls (p < 0.001 and p = 0.009). Sympathetic activity (LF nu) was lower in cancer patients than in controls (p = 0.023), including sympathovagal balance (LF/HF nu ratio) (p = 0.025). RMSSD was reduced in anorexic (p < 0.001) and non-anorexic (p = 0.003) cancer patients compared to controls. The SDNN was lower in anorexic cancer patients than in non-anorexic cancer patients (p = 0.025), and it was lower in anorexic cancer patients than in controls (p = 0.001). LF nu was lower in anorexic cancer patients than in controls (p = 0.015), as was LF/HF (p = 0.031). SDNN was negatively correlated with BWL in the cancer group (rho = -0.40; p = 0.007). Our data support the hypothesis that autonomic nervous system dysregulation exists in patients with cancer presenting with anorexia, with implications for its diagnosis and treatment.

Cancer cachexia - adopting a systems wide approach

PURPOSE OF REVIEW

Cancer cachexia results in the death of approximately 2 million people worldwide annually. Despite the impact of this devastating condition, there is limited therapy and no standard of care. Although multiple definitions exist, confusion remains as a true understanding of the biology has not yet been achieved and distinct phases of cachexia have not been examined. Research has mainly focused on weight loss and muscle wasting, but cachexia is increasingly recognized as a multiorgan disorder involving adipose tissue, liver, brain, gut and heart, with systemic inflammation a central unifying feature.

RECENT FINDINGS

In this review, we will discuss some of the extra-muscular features and multisystem interactions in cachexia, and describe how moving our focus beyond muscle can lead to a greater understanding of the mechanisms and clinical features seen in cachexia.

SUMMARY

We describe the need for robust characterization of patients with cachexia, to allow clinical phenotypes and multisystem mechanisms to be untangled, and to enable the implementation of multimodal treatment strategies.

Cancer cachexia: involvement of an expanding macroenvironment

Advanced cancers often present with the cachexia syndrome that impacts peripheral tissues, leading to involuntary weight loss and reduced prognosis. The central tissues undergoing depletion are skeletal muscle and adipose, but recent findings reveal an expanding tumor macroenvironment involving organ crosstalks that underlie the cachectic state.

Is There a Need to "Modernize" and "Simplify" the Diagnostic Criteria of Protein-Energy Wasting?

Protein energy wasting(PEW) is a term that most nephrologists used to define nutritional disorders in patients with acute kidney injury and chronic kidney disease. Although this nomenclature is well implemented in the field of nephrology, the use of other terms such as cachexia or malnutritionin the majority of chronic diseases can induce confusion regarding the definition and interpretation of these terms. There is ample evidence in the literature that the pathways involved in cachexia/malnutrition and PEW are common. However, in kidney diseases, there are pathophysiological conditions such as accumulation of uremic toxins, and the use of dialysis, which may induce a phenotypic specificity justifying the original term PEW. In light of the latest epidemiologic studies, the criteria for PEW used in 2008 probably need to be updated. The objective of this review is to summarize the main mechanisms involved in cachexia/malnutrition and PEW. We discuss the need to modernize and simplify the current definition and diagnostic criteria of PEW. We consider the interest of proposing a specific nomenclature of PEW for children and elderly patients with kidney diseases.

Food Aversion during Cancer Treatment: A Systematic Review

Individuals with cancer often present food aversion after initiation of anti-tumor treatment, which may impair nutritional status. We aim to assess the prevalence and factors associated with food aversion during cancer treatment. Articles from three databases were searched: MEDLINE, EMBASE and Cochrane Library. English was used, with no restriction on the year of publication. Inclusion criteria were original articles that evaluated food aversion in adults and the elderly undergoing chemotherapy and/or radiotherapy treatment. Fifteen articles were included. A high prevalence of food aversion (21-62%) was observed, with meat considered the most aversive food. The aversion is usually transient and may be due to gastrointestinal problems, such as nausea and vomiting, caused by chemotherapy or radiotherapy treatment, and even psychological and emotional issues. Offering a new food before the beginning of treatment seems to be an effective strategy to reduce aversion, combined with nutritional and psychological monitoring. Cancer patients have a high prevalence of food aversion. Multidisciplinary care can minimize the consequences of cancer treatment.

Area postrema neurons mediate interleukin-6 function in cancer-associated cachexia

Interleukin-6 (IL-6) has been long considered a key player in cancer-associated cachexia 1-15 . It is believed that sustained elevation of IL-6 production during cancer progression causes brain dysfunctions, which ultimately result in cachexia 16-20 . However, how peripheral IL-6 influences the brain remains poorly understood. Here we show that neurons in the area postrema (AP), a circumventricular structure in the hindbrain, mediate the function of IL-6 in cancer-associated cachexia in mice. We found that circulating IL-6 can rapidly enter the AP and activate AP neurons. Peripheral tumor, known to increase circulating IL-6 1-5,15,18,21-23 , leads to elevated IL-6 and neuronal hyperactivity in the AP, and causes potentiated excitatory synaptic transmission onto AP neurons. Remarkably, neutralization of IL-6 in the brain of tumor-bearing mice with an IL-6 antibody prevents cachexia, reduces the hyperactivity in an AP network, and markedly prolongs lifespan. Furthermore, suppression of Il6ra , the gene encoding IL-6 receptor, specifically in AP neurons with CRISPR/dCas9 interference achieves similar effects. Silencing of Gfral-expressing AP neurons also ameliorates the cancer-associated cachectic phenotypes and AP network hyperactivity. Our study identifies a central mechanism underlying the function of peripheral IL-6, which may serve as a target for treating cancer-associated cachexia.

Perspectives of Health Care Professionals on Multimodal Interventions for Cancer Cachexia

Background

Holistic multimodal interventions have not been established for cancer cachexia. The beliefs and perceptions of health care professionals (HCPs) based on their experiences influence the interventions.

Objectives

HCPs' knowledge, perceptions, and practices in cancer cachexia management were evaluated.

Design/Setting/Subjects/Measurements

A nationwide questionnaire survey was conducted that focused on the perspectives of HCPs on interventions in 451 designated cancer hospitals across Japan. Descriptive statistics were applied.

Results

Among 2255 participants, 1320 responded (58.5%), and 1188 in 258 institutes were included in the analysis. The current international definition of cancer cachexia is not commonly known and recent clinical practice guidelines have not been widely adopted. More than 50% of participants considered ≥5% weight loss in six months and ECOG PS (Eastern Cooperative Oncology Group Performance Status) 2-4 to be cancer cachexia, whereas 50% answered that there was no relationship between life expectancy and cancer cachexia. Participants tended to consider it important to initiate nutritional and exercise interventions before cancer cachexia becomes apparent. The majority of participants recognized the importance of holistic multimodal interventions, particularly for the management of physical and psychological symptoms; however, only 20% reported that they educated patients and families. Furthermore, 33% of participants considered themselves to have provided patients and families with sufficient nutritional and exercise interventions and evidence-based information.

Conclusion

The results reveal that HCPs are not regularly providing education and emotional support to patients and families suffering from cancer cachexia. The results also show the need for education for HCPs to enhance implementation of holistic multimodal interventions for cancer cachexia.

Targeting cancer cachexia: Molecular mechanisms and clinical study

Cancer cachexia is a complex systemic catabolism syndrome characterized by muscle wasting. It affects multiple distant organs and their crosstalk with cancer constitute cancer cachexia environment. During the occurrence and progression of cancer cachexia, interactions of aberrant organs with cancer cells or other organs in a cancer cachexia environment initiate a cascade of stress reactions and destroy multiple organs including the liver, heart, pancreas, intestine, brain, bone, and spleen in metabolism, neural, and immune homeostasis. The role of involved organs turned from inhibiting tumor growth into promoting cancer cachexia in cancer progression. In this review, we depicted the complicated relationship of cancer cachexia with the metabolism, neural, and immune homeostasis imbalance in multiple organs in a cancer cachexia environment and summarized the treatment progress in recent years. And we discussed the molecular mechanism and clinical study of cancer cachexia from the perspective of multiple organs metabolic, neurological, and immunological abnormalities. Updated understanding of cancer cachexia might facilitate the exploration of biomarkers and novel therapeutic targets of cancer cachexia.

Cancer cachexia as a multiorgan failure: Reconstruction of the crime scene

Cachexia is a devastating syndrome associated with the end-stage of several diseases, including cancer, and characterized by body weight loss and severe muscle and adipose tissue wasting. Although different cancer types are affected to diverse extents by cachexia, about 80% of all cancer patients experience this comorbidity, which highly reduces quality of life and response to therapy, and worsens prognosis, accounting for more than 25% of all cancer deaths. Cachexia represents an urgent medical need because, despite several molecular mechanisms have been identified, no effective therapy is currently available for this devastating syndrome. Most studies focus on skeletal muscle, which is indeed the main affected and clinically relevant organ, but cancer cachexia is characterized by a multiorgan failure. In this review, we focus on the current knowledge on the multiple tissues affected by cachexia and on the biomarkers with the attempt to define a chronological pathway, which might be useful for the early identification of patients who will undergo cachexia. Indeed, it is likely that the inefficiency of current therapies might be attributed, at least in part, to their administration in patients at the late stages of cachexia.

The systemic-level repercussions of cancer-associated inflammation mediators produced in the tumor microenvironment

The tumor microenvironment is a dynamic, complex, and redundant network of interactions between tumor, immune, and stromal cells. In this intricate environment, cells communicate through membrane-membrane, ligand-receptor, exosome, soluble factors, and transporter interactions that govern cell fate. These interactions activate the diverse and superfluous signaling pathways involved in tumor promotion and progression and induce subtle changes in the functional activity of infiltrating immune cells. The immune response participates as a selective pressure in tumor development. In the early stages of tumor development, the immune response exerts anti-tumor activity, whereas during the advanced stages, the tumor establishes mechanisms to evade the immune response, eliciting a chronic inflammation process that shows a pro-tumor effect. The deregulated inflammatory state, in addition to acting locally, also triggers systemic inflammation that has repercussions in various organs and tissues that are distant from the tumor site, causing the emergence of various symptoms designated as paraneoplastic syndromes, which compromise the response to treatment, quality of life, and survival of cancer patients. Considering the tumor-host relationship as an integral and dynamic biological system, the chronic inflammation generated by the tumor is a communication mechanism among tissues and organs that is primarily orchestrated through different signals, such as cytokines, chemokines, growth factors, and exosomes, to provide the tumor with energetic components that allow it to continue proliferating. In this review, we aim to provide a succinct overview of the involvement of cancer-related inflammation at the local and systemic level throughout tumor development and the emergence of some paraneoplastic syndromes and their main clinical manifestations. In addition, the involvement of these signals throughout tumor development will be discussed based on the physiological/biological activities of innate and adaptive immune cells. These cellular interactions require a metabolic reprogramming program for the full activation of the various cells; thus, these requirements and the by-products released into the microenvironment will be considered. In addition, the systemic impact of cancer-related proinflammatory cytokines on the liver-as a critical organ that produces the leading inflammatory markers described to date-will be summarized. Finally, the contribution of cancer-related inflammation to the development of two paraneoplastic syndromes, myelopoiesis and cachexia, will be discussed.

Leucine Supplementation in Cancer Cachexia: Mechanisms and a Review of the Pre-Clinical Literature

Cancer cachexia (CC) is a complex syndrome of bodily wasting and progressive functional decline. Unlike starvation, cachexia cannot be reversed by increased energy intake alone. Nonetheless, targeted nutritional support is a necessary component in multimodal syndrome management. Due to the highly catabolic nature of cancer cachexia, amino acid supplementation has been proposed. Interestingly, leucine has been found to increase protein synthesis and decrease protein degradation via mTORC1 pathway activation. Multiple pre-clinical studies have explored the impact of leucine supplementation in cachectic tumor-bearing hosts. Here, we provide an overview of leucine’s proposed modes of action to preserve lean mass in cachexia and review the current pre-clinical literature related to leucine supplementation during CC. Current research indicates that a leucine-rich diet may attenuate CC symptomology; however, these works are difficult to compare due to methodological differences. There is need for further pre-clinical work exploring leucine’s potential ability to modulate protein turnover and immune response during CC, as well as the impact of additive leucine on tumor growth.

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.

Psychological symptoms of illness and emotional distress in advanced cancer cachexia

PURPOSE OF REVIEW

Cachexia induces both physical and psychological symptoms of illness in patients with advanced cancer and may generate emotional distress in patients and families. However, physical symptoms of cachexia received the most emphasis. The aims of this review are to elucidate a link between systemic inflammation underlying cachexia and psychological symptoms and emotional distress, and to advance care strategy for management of psychological symptoms and emotional distress in patients and families.

RECENT FINDINGS

The main themes in the literature covered by this review are psychological symptoms in patients and emotional distress in patients and families. Studies of the underlying biology of cachexia identify the role of the central nervous system to amplify tumor-induced systemic inflammation. The brain mediates a cluster of symptoms, such as sleep disruption, anxiety, cognitive impairment, and reduction in motivated behavior (notably anorexia). These are distressing to patients as well as to families.

SUMMARY

There is growing recognition that holistic multimodal interventions are needed to alleviate psychological symptoms and emotional distress and to improve quality of life in patients with cancer cachexia and families. This is an approach that addresses not only physical health but also psychological, emotional, and social well being issues.

Single nuclei RNA sequencing of the rat AP and NTS following GDF15 treatment

Objective

Growth differentiation factor 15 (GDF15) is known to play a role in feeding, nausea, and body weight, with action through the GFRAL-RET receptor complex in the area postrema (AP) and nucleus tractus solitarius (NTS). To further elucidate the underlying cell type-specific molecular mechanisms downstream of GDF15 signaling, we used a single nuclei RNA sequencing (snRNAseq) approach to profile AP and NTS cellular subtype-specific transcriptomes after systemic GDF15 treatment.

Methods

AP and NTS micropunches were used for snRNAseq from Sprague Dawley rats 6 h following GDF15 or saline injection, and Seurat was used to identify cellular subtypes and cell type-specific alterations in gene expression that were due to the direct and secondary effects of systemic GDF15 treatment.

Results

Using the transcriptome profile of ∼35,000 individual AP/NTS nuclei, we identified 19 transcriptomically distinct cellular subtypes, including a single population Gfral and Ret positive excitatory neurons, representing the primary site of action for GDF15. A total of ∼600 cell type-specific differential expression events were identified in neurons and glia, including the identification of transcriptome alterations specific to the direct effects of GDF15 in the Gfral-Ret positive excitatory neurons and shared transcriptome alterations across neuronal and glial cell types. Downstream analyses identified shared and cell type-specific alterations in signaling pathways and upstream regulatory mechanisms of the observed transcriptome alterations.

Conclusions

These data provide a considerable advance in our understanding of AP and NTS cell type-specific molecular mechanisms associated with GDF15 signaling. The identified cellular subtype-specific regulatory mechanism and signaling pathways likely represent important targets for future pharmacotherapies.

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GDF15 directly alters transcription in Gfral- and Ret-positive excitatory neurons.

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GDF15 indirectly alters transcription in other neuronal and glial populations.

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Cell type-specific expression changes identify regulatory and signaling mechanisms.