Our study was to characterize sarcopenia in C57BL/6J mice using a clinically relevant definition to investigate the underlying molecular mechanisms. Aged male (23–32 months old) and female (27–28 months old) C57BL/6J mice were classified as non-, probable-, or sarcopenic based on assessments of grip strength, muscle mass, and treadmill running time, using 2 SDs below the mean of their young counterparts as cutoff points. A 9%–22% prevalence of sarcopenia was identified in 23–26 month-old male mice, with more severe age-related declines in muscle function than mass. Females aged 27–28 months showed fewer sarcopenic but more probable cases compared with the males. As sarcopenia progressed, a decrease in muscle contractility and a trend toward lower type IIB fiber size were observed in males. Mitochondrial biogenesis, oxidative capacity, and AMPK-autophagy signaling decreased as sarcopenia progressed in males, with pathways linked to mitochondrial metabolism positively correlated with muscle mass. No age- or sarcopenia-related changes were observed in mitochondrial biogenesis, OXPHOS complexes, AMPK signaling, mitophagy, or atrogenes in females. Our results highlight the different trajectories of age-related declines in muscle mass and function, providing insights into sex-dependent molecular changes associated with sarcopenia progression, which may inform the future development of novel therapeutic interventions.

Autologous hematopoietic stem cell transplantation (AHCT) is an accepted strategy for various hematologic malignancies that can lead to functional impairment, fatigue, muscle wasting, and reduced quality of life (QOL). In cancer cachexia, these symptoms are associated with inflammation, hypermetabolism, and decreased anabolic hormones. The relative significance of these factors soon after AHCT setting is unclear. The purpose of this study was to characterize the acute effects of AHCT on physical function, body composition, QOL, energy expenditure, cytokines, and testosterone. Outcomes were assessed before (PRE) and 30 ± 10 days after (FU) AHCT in patients with multiple myeloma (n = 15) and non-Hodgkin lymphoma (n = 6). Six-minute walk test (6MWT; p = 0.014), lean mass (p = 0.002), and fat mass (p = 0.02) decreased; nausea and fatigue increased at FU (both p = 0.039). Recent weight change and steroid exposure were predictors of reduced aerobic capacity (p < 0.001). There were no significant changes in interleukin (IL)-1β, IL-6, tumor necrosis factor (TNF), energy expenditure, or bioavailable testosterone. Alterations in cytokines, energy expenditure, and testosterone were not associated with functional impairment acutely following AHCT. Recent history of weight loss and steroid exposure were predictors of worse physical function after AHCT, suggesting that targeting nutritional status and myopathy may be viable strategies to mitigate these effects.

Cancer cachexia is characterized by a significant loss in body weight due to the wasting of skeletal muscle and adipose tissue. Systemic inflammation has long been associated with cachexia, with various tumor secreted factors shown to correlate with as well as cause tissue wasting. In addition to systemic inflammation, it has become increasingly appreciated that inflammation occurs in specific tissues in cancer cachexia, with tissues such as muscle, adipose, liver and brain being affected. While several studies have shown that this local tissue inflammation contributes to cachexia, there is evidence that some aspects of the inflammatory response may play a protective role to mitigate tissue wasting. Here, we will review the findings on local tissue inflammation in cachexia, comparing the impacts of such inflammation on tissue wasting and cachexia progression overall. Furthermore, we discuss the methods used to mitigate inflammation in various tissues and highlight the outcomes on the cachectic phenotype. Collectively, understanding how inflammation contributes to cachexia in each tissue will ultimately influence how therapies can be designed to treat cachexia while minimizing possible adverse side effects.

Adipose tissue (AT) atrophy is a hallmark of cancer cachexia contributing to increased morbidity/mortality. Ghrelin has been proposed as a treatment for cancer cachexia partly by preventing AT atrophy. However, the mechanisms mediating ghrelin’s effects are incompletely understood, including the extent to which its only known receptor, GHSR-1a, is required for these effects. This study characterizes the pathways involved in AT atrophy in the Lewis Lung Carcinoma (LLC)-induced cachexia model and those mediating the effects of ghrelin in Ghsr^+/+ and Ghsr^−/− mice. We show that LLC causes AT atrophy by inducing anorexia, and increasing AT inflammation, thermogenesis and energy expenditure. These changes were greater in Ghsr^−/−. Ghrelin administration prevented LLC-induced anorexia only in Ghsr^+/+, but prevented WAT inflammation and atrophy in both genotypes, although its effects were greater in Ghsr^+/+. LLC-induced increases in BAT inflammation, WAT and BAT thermogenesis, and energy expenditure were not affected by ghrelin. In conclusion, ghrelin ameliorates WAT inflammation, fat atrophy and anorexia in LLC-induced cachexia. GHSR-1a is required for ghrelin’s orexigenic effect but not for its anti-inflammatory or fat-sparing effects.