The GDF15-GFRAL axis mediates chemotherapy-induced fatigue in mice

Growth and differentiation factor 15: An emerging therapeutic target for brain diseases

Growth and differentiation factor 15 (GDF15), a member of the transforming growth factor-βsuperfamily, is considered a stress response factor and has garnered increasing attention in recent years due to its roles in neurological diseases. Although many studies have suggested that GDF15 expression is elevated in patients with neurodegenerative diseases (NDDs), glioma, and ischemic stroke, the effects of increased GDF15 expression and the potential underlying mechanisms remain unclear. Notably, many experimental studies have shown the multidimensional beneficial effects of GDF15 on NDDs, and GDF15 overexpression is able to rescue NDD-associated pathological changes and phenotypes. In glioma, GDF15 exerts opposite effects, it is both protumorigenic and antitumorigenic. The causes of these conflicting findings are not comprehensively clear, but inhibiting GDF15 is helpful for suppressing tumor progression. GDF15 is also regarded as a biomarker of poor clinical outcomes in ischemic stroke patients, and targeting GDF15 may help prevent this disease. Thus, we systematically reviewed the synthesis, transcriptional regulation, and biological functions of GDF15 and its related signaling pathways within the brain. Furthermore, we explored the potential of GDF15 as a therapeutic target and assessed its clinical applicability in interventions for brain diseases. By integrating the latest research findings, this study provides new insights into the future treatment of neurological diseases.

The metabolic basis of cancer-related fatigue

Although we are all familiar with the sensation of fatigue, there are still profound divergences on what it represents and its mechanisms. Fatigue can take various forms depending on the condition in which it develops. Cancer-related fatigue is considered a symptom of exhaustion that is often present at the time of diagnosis, increases in intensity during cancer therapy, and does not always recede after completion of treatment. It is usually attributed to the inflammation induced by damage-associated molecular patterns released by tumor cells during cancer progression and in response to its treatment. In this review, we argue that it is necessary to go beyond the symptoms of fatigue to understand its nature and mechanisms. We propose to consider fatigue as a psychobiological process that regulates the behavioral activities an organism engages in to satisfy its needs, according to its physical ability to do so and to the capacity of its intermediary metabolism to exploit the resources procured by these activities. This last aspect is critical as it implies that these metabolic aspects need to be considered to understand fatigue. Based on the findings we have accumulated over several years of studying fatigue in diverse murine models of cancer, we show that energy metabolism plays a key role in the development and persistence of this condition. Cancer-related fatigue is dependent on the energy requirements of the tumor and the negative impact of cancer therapy on the mitochondrial function of the host. When inflammation is present, it adds to the organism's energy expenses. The organism needs to adjust its metabolism to the different forms of cellular stress it experiences thanks to specialized communication factors known as mitokines that act locally and at a distance from the cells in which they are produced. They induce the subjective, behavioral, and metabolic components of fatigue by acting in the brain. Therefore, the targeting of mitokines and their brain receptors offers a window of opportunity to treat fatigue when it is no longer adaptive but an obstacle to the quality of life of cancer survivors.

Identification of diagnostic biomarkers in prostate cancer-related fatigue by construction of predictive models and experimental validation

BACKGROUND

Cancer-related fatigue (CRF) is a prominent cancer-related complication occurring in Prostate cancer (PCa) patients, profoundly affecting prognosis. The lack of diagnostic criteria and biomarkers hampers the management of CRF.

METHODS

The CRF-related data and PCa single-cell data were retrieved from the GEO database and clinical data was downloaded from the TCGA database. The univariate logistic/Cox regression analysis were used to construct the prediction models. The predictive value of models was analyzed using the ROC curve and Kaplan-Meier survival. The hub genes were screened by an intersection analysis of DEGs. The mice model of PCa and PCa-related fatigue were established, and fatigue-like behaviors of mice were detected. The expression of selected hub genes was validated by RT-PCR and IHC analysis.

RESULTS

The diagnosis and risk models showed great predictive value both in the training and validation dataset. Five genes (Baiap2l2, Cacng4, Sytl2, Sec31b and Ms4a1) that enriched the CXCL signaling were identified as hub genes. Among all hub genes, the MS4A1 expression is the most significant in PCa-related fatigue mice.

CONCLUSIONS

We identified MS4A1 as a promising biomarker for the diagnosis of PCa-related fatigue. Our findings would lay a foundation for revealing the pathogenesis and developing therapies for PCa-related fatigue.

Diversity in chemotherapy-induced cachexia

Preclinical and clinical studies suggest that chronic administration of cytotoxic drugs (e.g., chemotherapy) may contribute to the occurrence of skeletal muscle wasting and weakness/fatigue (i.e., cachexia). Doxorubicin, folfiri, and cisplatin are known to promote cachexia by triggering common alterations such as skeletal muscle atrophy, protein breakdown, and mitochondrial dysfunction, whereas each also possesses distinguishing features in terms of the activated molecular pathways. Similarly, commonalities exist between different cancer types including the development of muscle wasting early in treatment that can persist for years. The impact of treatment for gastrointestinal, head and neck, and nonsmall cell lung cancers (NSCLCs) on the development of cachexia and survival outcomes is well documented. However, a disconnect occurs between preclinical studies on cachexia, which are often performed on younger mice, and clinical studies on cachexia, which are focused on patients over 60 yr old. Yet, several preclinical studies have examined the impact of age on chemotherapy-induced cachexia. Finally, sex differences have been identified in both preclinical and clinical studies focused on the onset of cachexia consequential to chemotherapy administration and raise the question of whether treatments for this condition should be based on sex specificities. In conclusion, although cancer cachexia has been widely studied for its impact on patients affected by various malignancies, the effects of chemotherapy on the development of cachexia are less explored. Here, we examine diversity in chemotherapy-induced cachexia with respect to specific types of chemotherapy regimens and cancer, and differences based on age and sex.

Melanocortin-4 receptor antagonist TCMCB07 alleviates chemotherapy-induced anorexia and weight loss in rats

Cancer patients undergoing chemotherapy often experience anorexia and weight loss that substantially deteriorates overall health, reduces treatment tolerance and quality of life, and worsens oncologic outcomes. There are currently few effective therapeutic options to mitigate these side effects. The central melanocortin system, which plays a pivotal role in regulating appetite and energy homeostasis, presents a logical target for treating anorexia and weight loss. In this preclinical study, we evaluated the efficacy of TCMCB07, a synthetic antagonist of the melanocortin-4 receptor, in mitigating anorexia and weight loss in several rat models of chemotherapy: cisplatin, 5-fluorouracil, cyclophosphamide, vincristine, doxorubicin, and a combination of irinotecan and 5-fluorouracil. Our results indicate that peripheral administration of TCMCB07 improved appetite, stabilized body weight, preserved fat and heart mass, and slightly protected lean mass after multiple cycles of chemotherapy. Furthermore, combining TCMCB07 with a growth differentiation factor 15 antibody enhanced treatment effectiveness. Similar effects from TCMCB07 treatment were observed in a rat tumor model following combination chemotherapy. No notable adverse effects nor increased chemotherapy-related toxicities were observed with TCMCB07 treatment. These findings suggest that peripheral administration of TCMCB07 holds promise as a therapeutic approach for alleviating chemotherapy-induced anorexia and weight loss, potentially benefiting numerous patients undergoing chemotherapy.

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.

Stress relief of chemo illness

New studies (Tang et al. 2024. J. Exp. Med.https://doi.org/10.1084/jem.20231395) describe a liver stress pathway that is activated by certain chemotherapeutic drugs, which in turn induces a peptide hormone which partially mediates the lower food intake and body weight loss during chemotherapy treatment.

Cancer-related fatigue among patients with advanced cancer receiving immune-checkpoint inhibitors: a prospective study

PURPOSE

The aim of this study was to determine the frequency and factors associated with severity of cancer related fatigue (CRF) as assessed by Functional Assessment of Cancer Illness Therapy-Fatigue (FACIT-F), prior to, and during 12 weeks of immune-checkpoint inhibitors (ICIs). We also explored the effects of ICIs on fatigue dimensions and interference with daily activities (Multidimensional Functional Symptom Inventory, MFSI-SF, Patient-Related Outcome Symptom Measurement Information System Short form Fatigue 7a, PROMIS F-SF), QOL (Functional Assessment of Cancer Therapy-General, FACT-G), and cancer symptoms (Edmonton Symptom Assessment Scale, ESAS).

METHODS

In this prospective, longitudinal observational study, patients with a diagnosis of advanced cancer receiving ICIs were evaluated. Patient demographics, FACT-G, FACIT-F, MFSI-SF, PROMIS F-SF, and ESAS were collected prior to, and during 12 weeks of ICIs.

RESULTS

A total of 160 of the 212 enrolled patients were analyzed. The median age was 61 years, 60% were female, most common cancer was melanoma (73%), and most common ICI was nivolumab 46%. The frequency of clinically significant fatigue (defined as ≤ 34/52 on FACIT-F score) was 25.6% at baseline, 25.7% at week 8, and 19.5% at week 12. There was significant improvement in FACIT-F (P = 0.016), FACT-G physical well-being (P = 0.041), FACT-G emotional well-being (P = 0.011), ESAS anxiety (P = 0.045), and ESAS psychological distress (P = 0.03) scores from baseline to week 12 of ICIs. Multivariate analysis found significant association between clinically significant CRF and PROMIS F-SF (P < 0.001) and MFSI-SF global scores (P < 0.001).

CONCLUSIONS

CRF is frequent prior to the initiation of ICI treatment. Over 12 weeks of ICI treatment, CRF significantly improved. FACT-G physical well-being, FACT-G emotional well-being, ESAS anxiety, and ESAS psychological distress scores improved overtime. Further studies are needed to validate these findings.

A nomogram for predicting the risk of cancer-related cognitive impairment in breast cancer patients based on a scientific symptom model

Cancer-related cognitive impairment is a significant clinical challenge observed in patients with breast cancer, manifesting during or after treatment. This impairment leads to deteriorations in memory, processing speed, attention, and executive functioning, which profoundly impact patients' occupational performance, daily living activities, and overall quality of life. Grounded in the Symptom Science Model 2.0, this study investigates the contributing factors to Cancer-related cognitive impairment in breast cancer patients and develops a predictive nomogram for this demographic. Employing both univariate and multivariate logistic regression analyses, this investigation delineates the predictive factors influencing outcomes in breast cancer patients. A nomogram was constructed leveraging these identified predictive factors, accompanied by internal validation through bootstrap resampling methodology (1000 bootstrap samples). The efficacy of the predictive model was assessed by employing the Hosmer-Lemeshow goodness-of-fit test and calibration curves. The prevalence of cognitive impairment in breast cancer patients was identified to be 45.83%.Multivariate logistic regression analysis identified the independent predictors of Cancer-related cognitive impairment in breast cancer patients as place of residence, educational level, chemotherapy, benefit finding, post-traumatic growth, anxiety, fear of cancer progression, and fasting blood glucose levels. these factors were integrated into the nomogram. The Hosmer-Lemeshow goodness-of-fit test demonstrated that the prediction model was appropriately calibrated (χ2 = 11.520, P = 0.174). Furthermore, the model exhibited an area under the curve of 0.955 (95% CI 0.939 to 0.971) and a sensitivity of 0.906, evidencing its robust discriminative capacity and accuracy. Utilizing the Symptom Science Model 2.0 as a framework, this study comprehensively examines the multifaceted factors influencing Cancer-related cognitive impairment in breast cancer patients, spanning five critical domains: complex symptoms, phenotypic characterization, biobehavioral factors, social determinants of health, and patient-centered experiences. A predictive nomogram model was established, demonstrating satisfactory predictive accuracy and capability. This model is capable of identifying breast cancer patients with cognitive impairments with high precision. The findings furnish empirical evidence in support of the early detection, diagnosis, and intervention strategies for high-risk breast cancer patients afflicted with Cancer-related cognitive impairment.

Phase 2 study of the efficacy and safety of ponsegromab in patients with cancer cachexia: PROACC-1 study design

BACKGROUND

Cancer cachexia is a multifactorial metabolic wasting syndrome characterized by anorexia, unintentional loss of weight involving both skeletal muscle and adipose tissues, progressive functional impairment and reduced survival. Therapeutic strategies for this serious condition are very limited. Growth differentiation factor 15 (GDF-15) is a cytokine that is implicated in cancer cachexia and may represent both a biomarker of cancer cachexia and a potential therapeutic target. Ponsegromab is a potent and selective humanized monoclonal antibody that inhibits GDF-15-mediated signalling. Preclinical and preliminary phase 1 data suggest that ponsegromab-mediated inactivation of circulating GDF-15 may lead to improvement in key characteristics of cachexia. The primary objective of this phase 2 study is to assess the effect of ponsegromab on body weight in patients with cancer, cachexia and elevated GDF-15 concentrations. Secondary objectives include assessing physical activity, physical function, actigraphy, appetite, nausea and vomiting, fatigue and safety. Exploratory objectives include evaluating pharmacokinetics, pharmacodynamics, immunogenicity, lumbar skeletal muscle index and Response Evaluation Criteria in Solid Tumors.

METHODS

Approximately 168 adults with non-small-cell lung, pancreatic or colorectal cancers who have cachexia and elevated GDF-15 concentrations will be randomized in a double-blind, placebo-controlled study (NCT05546476). Participants meeting eligibility criteria will be randomized 1:1:1:1 to one of three dose groups of ponsegromab (100, 200 or 400 mg) or matching placebo administered subcutaneously every 4 weeks for an initial 12-week treatment period. This is followed by optional open-label treatment with ponsegromab of 400 mg administered every 4 weeks for up to 1 year. The primary endpoint is mean change from baseline in body weight at Week 12. A mixed model for repeated measures followed by a Bayesian Emax model will be used for the primary analysis. Secondary endpoints include physical activity, physical function and actigraphy measured by remote digital sensors; patient-reported appetite-related symptoms assessed by Functional Assessment of Anorexia-Cachexia Therapy subscale scores; anorexia/appetite, nausea and vomiting, and fatigue evaluated according to questions from the Cancer-Related Cachexia Symptom Diary; and incidence of adverse events, safety laboratory tests, vital signs and electrocardiogram abnormalities.

PERSPECTIVE

Cancer-related cachexia is an area of significant unmet medical need. This study will support the clinical development of ponsegromab as a novel inhibitor of GDF-15, which may ameliorate key pathologies of cancer cachexia to improve patient symptoms, functionality and quality of life.

TRIAL REGISTRATION

ClinicalTrials.gov ID: NCT05546476.

The fatigue-inducing effects of cancer and its therapy are characterized by decreased physical activity in the absence of any motivational deficit

Although cancer and its therapy are well known to be associated with fatigue, the exact nature of cancer-related fatigue remains ill-defined. We previously reported that fatigue-like behavior induced independently by tumor growth and by the chemotherapeutic agent cisplatin is characterized by reduced voluntary wheel running and an intact motivation to expand effort for food rewards. The present set of experiments was initiated to characterize the functional consequences of fatigue induced by chemoradiotherapy in tumor-bearing mice and relate them to changes in the expression of genes coding for inflammation, mitochondria dynamics and metabolism. Two syngeneic murine models of cancer were selected for this purpose, a model of human papilloma virus-related head and neck cancer and a model of lung cancer. In both models, tumor-bearing mice were submitted to chemoradiotherapy to limit tumor progression. Two dimensions of fatigue were assessed, the physical dimension by changes in physical activity in mice trained to run in wheels and the motivational dimension by changes in the performance of mice trained to nose poke to obtain a food reward in a progressive ratio schedule of food reinforcement. Chemoradiotherapy reliably decreased wheel running activity but had no effect on performance in the progressive ratio in both murine models of cancer. These effects were the same for the two murine models of cancer and did not differ according to sex. Livers and brains were collected at the end of the experiments for qRT-PCR analysis of expression of genes coding for inflammation, mitochondria dynamics, and metabolism. The observed changes were mainly apparent in the liver and typical of activation of type I interferon and NF-κB-dependent signaling, with alterations in mitochondrial dynamics and a shift toward glycolysis. Although the importance of these alterations for the pathophysiology of cancer-related fatigue remains to be explored, the present findings indicate that fatigue brought on by cancer therapy in tumor-bearing mice is more physical than motivational.

Biomarkers of fatigue in oncology: A systematic review

Cancer-related fatigue (CRF) is a distressing side effect of cancer and treatment, affecting both patients during active treatment and survivors, negatively impacting quality of life. While its exact cause remains uncertain, various mechanisms such as immune dysfunction, HPA-axis dysfunction, and treatment toxicity are proposed. Inflammatory biomarkers of CRF have been explored in previous research, but non-inflammatory markers have not been comprehensively studied. This systematic review analysed 33 studies to identify non-inflammatory peripheral blood biomarkers associated with CRF. Promising markers included Hb, blood coagulation factors, BDNF, tryptophan, GAA, mtDNA, platinum, CA125, and cystatin-C. Inconsistent findings were observed for other markers like VEGF, leptin, and stress hormones. Most studies focused on adults. Research in pediatrics is limited. This review showed partial evidence for the inflammaging hypothesis (neurotoxicity due to neuro-inflammation) laying at the basis of CRF. Further research, especially in pediatrics, is needed to confirm this hypothesis and guide future biomarker studies.

Growth differentiation factor-15 is an IFN-γ regulated mediator of infection-induced weight loss and the hepatic FGF21 response

Infections are often accompanied by weight loss caused by alterations in host behavior and metabolism, also known as sickness behaviors. Recent studies have revealed that sickness behaviors can either promote or impede survival during infections depending on factors such as the type of infectious pathogen. Nevertheless, we have an incomplete understanding of the underlying mechanisms of sickness behaviors. Furthermore, although the host immune responses to infections have long been known to contribute to the induction of sickness behaviors, recent studies have identified emerging cytokines that are also key regulators of host metabolism during infection and inflammation, such as growth differentiation factor 15 (GDF-15). GDF-15 is a distant member of the TGF-β superfamily that causes weight loss by suppressing appetite and food consumption and causing emesis. These effects require activation of neurons that express the only known GDF-15 receptor, the GFRAL receptor. GDF-15 also functions in the periphery including the induction of ketogenesis and immunoregulation. Nevertheless, the functions and regulation of GDF-15 during live infections is not yet known. Murine infection with avirulent Toxoplasma gondii is an established model to understand infection-induced weight loss. Past studies have determined that acute T. gondii infection causes weight loss due to diminished food consumption and increased energy expenditure through unknown mechanisms. Additionally, our lab previously demonstrated that T. gondii causes upregulation in serum GDF-15 in an IFN-γ-dependent manner during the post-acute phase of the infection. In this study, we interrogated the in-vivo functions and immune regulation of GDF-15 during Toxoplasma gondii infection. First, we found that in wild-type mice, acute T. gondii infection caused a significant weight loss that is preceded by elevation of serum levels of IFN-γ and GDF-15. To determine whether IFN-γ regulates GDF-15, we neutralized IFN-γ on days 5 and 6 and measured GDF-15 on day 7 and found that serum but not tissue levels of GDF-15 decreased after IFN-γ neutralization. Additionally, exogenous IFN-γ was sufficient to elevate serum GDF-15 in the absence of infection. Next, we compared the outcomes of T. gondii infection between WT and Gdf15-/- mice. We observed that the weight trajectories were declining in WT mice while they were increasing in Gdf15-/-mice during the acute phase of the infection. This difference in trajectories extended throughout the chronic infection resulting to an overall weight loss relative to initial weights in WT mice but not Gdf15-/-mice. Then, we determined that GDF-15 is not essential for survival and immunoregulation during T. gondii infection. We also demonstrated that GDF-15 is required for the induction of FGF21, stress-induced cytokine with prominent roles in regulating host metabolism. Finally, we discovered a cytokine cascade IFN-γ-GDF-15-FGF21 that is likely involved in the regulation of host metabolism. Overall, our study provides evidence that IFN-γ contributes to the regulation of host metabolism during infection by inducing GDF-15 and FGF21. GDF-15 orchestrates changes in host metabolism that supports the host immune response in clearing the infection. These physiological alterations induce FGF21, which in turn, orchestrates the adaptive responses to the effects of GDF-15, which can be detrimental when protracted.

Cross-species comparison of pregnancy-induced GDF15

Growth differentiation factor 15 (GDF15) is a stress-induced cytokine. Although the exact physiological function of GDF15 is not yet fully comprehended, the significant elevation of circulating GDF15 levels during gestation suggests a potential role for this hormone in pregnancy. This is corroborated by genetic association studies in which GDF15 and the GDF15 receptor, GDNF family receptor alpha like (GFRAL) have been linked to morning sickness and hyperemesis gravidarum (HG) in humans. Here, we studied GDF15 biology during pregnancy in mice, rats, macaques, and humans. In contrast to macaques and humans, mice and rats exhibited an underwhelming induction in plasma GDF15 levels in response to pregnancy (∼75-fold increase in macaques vs. ∼2-fold increase in rodents). The changes in circulating GDF15 levels were corroborated by the magnitude of Gdf15 mRNA and GDF15 protein expression in placentae from mice, rats, and macaques. These species-specific findings may help guide future studies focusing on GDF15 in pregnancy and on the evaluation of pharmacological strategies to interfere with GDF15-GFRAL signaling to treat severe nausea and HG.NEW & NOTEWORTHY In the present study pregnancy-induced changes in circulating growth differentiation factor 15 (GDF15) in rodents, rhesus macaques, and humans are mapped. In sum, it is demonstrated that humans and macaques exhibit a tremendous increase in placental and circulating GDF15 during pregnancy. In contrast, GDF15 is negligibly increased in pregnant mice and rats, questioning a physiological role for GDF15 in pregnancy in rodents.

Loss of appetite in patients with cancer: an update on characterization, mechanisms, and palliative therapeutics

PURPOSE OF REVIEW

Over the past year, loss of appetite in patients with cancer has continued to be an area of active investigation. This review provides an update of recently published findings.

RECENT FINDINGS

Despite the emergence of new cancer therapeutic agents, this symptom of loss of appetite continues to trouble patients, and it continues to be associated with poor survival. Recent preclinical research promises to lead to newer approaches and newer, more effective palliative agents. Recent clinical research shows that agents such as olanzapine, anamorelin, and cannabis either do or might palliate this symptom.

SUMMARY

Loss of appetite in patients with cancer remains an important area of clinical and research focus. Recent published data provide greater clarity with respect to how to palliate this symptom. Today, although clinicians have more options to palliate cancer-associated loss of appetite than ever before, questions remain unanswered about how to palliate this symptom optimally and how to improve the quality of life of patients who suffer from it.

Cisplatin decreases voluntary wheel-running activity but does not impair food-motivated behavior in mice

Cisplatin is a chemotherapeutic agent that is still commonly used to treat solid tumors. However, it has several toxic side effects due in large part to the mitochondrial damage that it induces. As this mitochondrial damage is likely to result in a decrease in the amount of metabolic energy that is available for behavioral activities, it is not surprising that fatigue develops in cancer patients treated with cisplatin. The present preclinical study was initiated to determine whether the detrimental effects of cisplatin were more pronounced on physical effort requiring a lot of energy versus effort that not only requires less energy but also procures energy in the form of food. For this purpose, mice were either trained to run in a wheel or to work for food in various schedules of food reinforcement before being treated with cisplatin. The experiments were carried out only in male mice as we had already reported that sex differences in cisplatin-induced neurotoxicities are minimal. Cisplatin was administered daily for one cycle of five days, or two cycles separated by a five-day rest. As observed in previous experiments, cisplatin drastically reduced voluntary wheel running. In contrast, when cisplatin was administered to food-restricted mice trained to work for a food reward in a progressive ratio schedule or in a fixed-interval schedule, it tended to increase the number of responses emitted to obtain the food rewards. This increase was not associated with any change in the temporal distribution of responses during the interval between two reinforcements in mice submitted to the fixed interval schedule of food reinforcement. When cisplatin was administered to food-restricted mice trained in an effort-based decision-making task in which they had to choose between working for a grain pellet with little effort and working for a preferred chocolate pellet with more effort, it decreased the total number of responses emitted to obtain food rewards. However, this effect was much less marked than the decrease in wheel running induced by cisplatin. The decrease in the effort invested in the procurement of food rewards was not associated with any change in the relative distribution of effort between low reward and high reward during the time course of the test session. These findings show that cisplatin decreases energy-consuming activities but not energy-procuring activities unless they require a choice between options differing in their cost-benefit ratio. Furthermore, they indicate that the physical dimension of fatigue is more likely to develop in cisplatin-treated individuals than the motivational dimension of fatigue.

Resolution of cisplatin-induced fatigue does not require endogenous interleukin-10 in male mice

Based on previous results showing a pivotal role of endogenous interleukin-10 (IL-10) in the recovery from cisplatin-induced peripheral neuropathy, the present experiments were carried out to determine whether this cytokine plays any role in the recovery from cisplatin-induced fatigue in male mice. Fatigue was measured by decreased voluntary wheel running in mice trained to run in a wheel in response to cisplatin. Mice were treated with a monoclonal neutralizing antibody (IL-10na) administered intranasally during the recovery period to neutralize endogenous IL-10. In the first experiment, mice were treated with cisplatin (2.83 mg/kg/day) for five days and IL-10na (12 μg/day for three days) five days later. In the second experiment, they were treated with cisplatin (2.3 mg/kg/day for 5 days twice at a five-day interval) and IL10na (12 μg/day for three days) immediately after the last injection of cisplatin. In both experiments, cisplatin decreased body weight and reduced voluntary wheel running. However, IL-10na did not impair recovery from these effects. These results show that the recovery from the cisplatin-induced decrease in wheel running does not require endogenous IL-10 in contrast to the recovery from cisplatin-induced peripheral neuropathy.