Activated mast cells in skeletal muscle can be a potential mediator for cancer-associated cachexia

Oncosis is the predominant type of cell death in rhabdomyolysis following exertional heat stroke

BACKGROUND

Rhabdomyolysis (RM), particularly heat exhaustion-associated rhabdomyolysis (ehsRM), is a significant clinical issue associated with high mortality and healthcare costs. However, the cellular death mechanisms remain incompletely understood. Oncosis, a form of passive cell death distinct from apoptosis, is characterized by cell swelling and triggered by ATP depletion. Additionally, porimin, a specific biomarker, can uniquely identify oncosis. This study aims to investigate the role and mechanisms of oncosis in both in vitro and in vivo models of ehsRM.

OBJECTIVE

This study aims to investigate the role and mechanisms of oncosis in both in vitro and in vivo models of ehsRM.

METHODS

In the in vitro study, 6-8-week-old male rats were subjected to treadmill exercise at an ambient temperature of (39.5 ± 0.5)°C and relative humidity of 50%-60%, at a speed of 15 meters per minute until their core body temperature (Tc) reached 43.0°C to establish a heatstroke animal model. Skeletal muscle and blood samples from the gastrocnemius were collected for cytokine, biochemical, and histopathological analyses. Pathological findings revealed decreased muscle fiber density, structural disarray, swelling, degeneration, and hemorrhage. Ultrastructural analysis showed cell swelling, structural disarray, cytoplasmic vacuolation, mitochondrial swelling and degeneration, loss of cristae, and nuclear degeneration, indicating myocyte swelling and necrosis. Porimin, CytC, Bax, and caspase-1 expression increased, while Bcl-2 expression decreased. JC-1 staining indicated a decline in mitochondrial membrane potential and dysfunction. ATP levels decreased, and reactive oxygen species (ROS) production increased. In the in vivo study, HSKMC cells were subjected to 4 hours of heat shock at 43°C to establish a heatstroke-induced rhabdomyolysis cell model. Electron microscopy revealed cell swelling, cytoplasmic vacuolation, mitochondrial swelling and degeneration, and nuclear swelling; late-stage (necrotic-like death) was characterized by nucleolar dissolution, nuclear fragmentation, chromatin condensation, and collapse of cytoplasmic structures. After 24 hours post-modeling, the proportion of double-positive cells (porimin + /PI+) and ROS levels significantly increased, as did porimin expression, while mitochondrial membrane potential and ATP levels significantly decreased. The proportion of Annexin V + /PI + double-positive cells and caspase-3 levels showed no significant changes.

RESULTS

In both in vitro and in vivo studies, oncosis played a crucial role in ehsRM. Pathological and ultrastructural analyses demonstrated cell swelling, structural disarray, mitochondrial damage, and nuclear degeneration. Porimin, CytC, Bax, and caspase-1 expression increased, while Bcl-2 expression decreased. ATP levels decreased, and ROS production increased. In the in vivo study, the proportion of porimin + /PI + double-positive cells and ROS levels significantly increased, while mitochondrial membrane potential and ATP levels significantly decreased. The proportion of Annexin V + /PI + double-positive cells and caspase-3 levels showed no significant changes.

CONCLUSION

Oncosis is predominant in ehsRM, involving mitochondrial dysfunction, ATP depletion, and oxidative stress.

Predictive models of sarcopenia based on inflammation and pyroptosis-related genes

Background

Sarcopenia is a prevalent condition associated with aging. Inflammation and pyroptosis significantly contribute to sarcopenia.

Methods

Two sarcopenia-related datasets (GSE111016 and GSE167186) were obtained from the Gene Expression Omnibus (GEO), followed by batch effect removal post-merger. The "limma" R package was utilized to identify differentially expressed genes (DEGs). Subsequently, LASSO analysis was conducted on inflammation and pyroptosis-related genes (IPRGs), resulting in the identification of six hub IPRGs. A novel skeletal muscle aging model was developed and validated using an independent dataset. Additionally, Gene Ontology (GO) enrichment analysis was performed on DEGs, along with Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis and gene set enrichment analysis (GSEA). ssGSEA was employed to assess differences in immune cell proportions between healthy muscle groups in older versus younger adults. The expression levels of the six core IPRGs were quantified via qRT-PCR.

Results

A total of 44 elderly samples and 68 young healthy samples were analyzed for DEGs. Compared to young healthy muscle tissue, T cell infiltration levels in aged muscle tissue were significantly reduced, while mast cell and monocyte infiltration levels were relatively elevated. A new diagnostic screening model for sarcopenia based on the six IPRGs demonstrated high predictive efficiency (AUC = 0.871). qRT-PCR results indicated that the expression trends of these six IPRGs aligned with those observed in the database.

Conclusion

Six biomarkers-BTG2, FOXO3, AQP9, GPC3, CYCS, and SCN1B-were identified alongside a diagnostic model that offers a novel approach for early diagnosis of sarcopenia.

Multimodal cell atlas of the ageing human skeletal muscle

Muscle atrophy and functional decline (sarcopenia) are common manifestations of frailty and are critical contributors to morbidity and mortality in older people1. Deciphering the molecular mechanisms underlying sarcopenia has major implications for understanding human ageing2. Yet, progress has been slow, partly due to the difficulties of characterizing skeletal muscle niche heterogeneity (whereby myofibres are the most abundant) and obtaining well-characterized human samples3,4. Here we generate a single-cell/single-nucleus transcriptomic and chromatin accessibility map of human limb skeletal muscles encompassing over 387,000 cells/nuclei from individuals aged 15 to 99 years with distinct fitness and frailty levels. We describe how cell populations change during ageing, including the emergence of new populations in older people, and the cell-specific and multicellular network features (at the transcriptomic and epigenetic levels) associated with these changes. On the basis of cross-comparison with genetic data, we also identify key elements of chromatin architecture that mark susceptibility to sarcopenia. Our study provides a basis for identifying targets in the skeletal muscle that are amenable to medical, pharmacological and lifestyle interventions in late life.

Immunoregulation in cancer-associated cachexia

BACKGROUND

Cancer-associated cachexia is a multi-organ disorder associated with progressive weight loss due to a variable combination of anorexia, systemic inflammation and excessive energy wasting. Considering the importance of immunoregulation in cachexia, it still lacks a complete understanding of the immunological mechanisms in cachectic progression.

AIM OF REVIEW

Our aim here is to describe the complex immunoregulatory system in cachexia. We summarize the effects and translational potential of the immune system on the development of cancer-associated cachexia and we attempt to conclude with thoughts on precise and integrated therapeutic strategies under the complex immunological context of cachexia.

KEY SCIENTIFIC CONCEPTS OF REVIEW

This review is focused on three main key concepts. First, we highlight the inflammatory factors and additional mediators that have been identified to modulate this syndrome. Second, we decipher the potential role of immune checkpoints in tissue wasting. Third, we discuss the multilayered insights in cachexia through the immunometabolic axis, immune-gut axis and immune-nerve axis.

Phosphatidylethanolamine (18:2e/18:2) may inhibit adipose tissue wasting in patients with cancer cachexia by increasing lysophosphatidic acid receptor 6

BACKGROUND

Cancer associated cachexia is characterized by the significant loss of adipose tissue, leading to devastating weight loss and muscle wasting in the majority of cancer patients. The effects and underlying mechanisms of degradation metabolites on adipocytes in cachectic patients remain poorly understood. To address this knowledge gap, we conducted a comprehensive study combining lipidomic analysis of subcutaneous and visceral adipose tissue with transcriptomics data from the database to investigate the mechanisms of lipid regulation in adipocytes.

METHODS

We collected subcutaneous and visceral adipose tissue samples from cachectic and noncachectic cancer patients. Lipidomic analysis was performed to identify differentially expressed lipids in both types of adipose tissue. Additionally, transcriptomics data from the GEO database were analyzed to explore gene expression patterns in adipocytes. Bioinformatics analysis was employed to determine the enrichment of differentially expressed genes in specific pathways. Furthermore, molecular docking studies were conducted to predict potential protein targets of specific lipids, with a focus on the PI3K-Akt signaling pathway. Western blot analysis was used to validate protein levels of the identified target gene, lysophosphatidic acid receptor 6 (LPAR6), in subcutaneous and visceral adipose tissue from cachectic and noncachectic patients.

RESULTS

Significant lipid differences in subcutaneous and visceral adipose tissue between cachectic and noncachectic patients were identified by multivariate statistical analysis. Cachectic patients exhibited elevated Ceramides levels and reduced CerG2GNAc1 levels (P < 0.05). A total of 10 shared lipids correlated with weight loss and IL-6 levels, enriched in Sphingolipid metabolism, GPI-anchor biosynthesis, and Glyceropholipid metabolism pathways. LPAR6 expression was significantly elevated in both adipose tissues of cachectic patients (P < 0.05). Molecular docking analysis indicated strong binding of Phosphatidylethanolamine (PE) (18:2e/18:2) to LPAR6.

CONCLUSIONS

Our findings suggest that specific lipids, including PE(18:2e/18:2), may mitigate adipose tissue wasting in cachexia by modulating the expression of LPAR6 through the PI3K-Akt signaling pathway. The identification of these potential targets and mechanisms provides a foundation for future investigations and therapeutic strategies to combat cachexia. By understanding the underlying lipid regulation in adipocytes, we aim to develop targeted interventions to ameliorate the devastating impact of cachexia on patient outcomes and quality of life. Nevertheless, further studies and validation are warranted to fully elucidate the intricate mechanisms involved and translate these findings into effective clinical interventions.

Pyroptosis-Derived Long Noncoding RNA Profiles Reveal a Novel Signature for Evaluating the Prognosis of Patients With Lung Adenocarcinoma

PURPOSE

Long noncoding RNAs (lncRNAs) were recently implicated in modifying pyroptosis. Nonetheless, pyroptosis-related lncRNAs and their possible clinical relevance persist largely uninvestigated in lung adenocarcinoma (LUAD).

MATERIALS AND METHODS

A sum of 921 samples were collected from three independent data sets. We obtained pyroptosis-related genes from both the Molecular Signatures Database and relevant literature sources and used four machine learning techniques, comprising stepwise Cox, ridge regression, least absolute shrinkage and selection operator, and random forest. Multiple bioinformatics approaches were used to further investigate the underlying mechanisms.

RESULTS

In total, 39 differentially expressed pyroptosis genes were identified by comparing normal and tumor samples. Correlation analysis revealed 933 pyroptosis-related lncRNAs. Furthermore, univariate Cox regression determined 11 lncRNAs that exhibited stable associations with prognosis in the three cohorts, which were used to construct the pyroptosis-derived lncRNA signature. After analyzing the optimal results from four machine learning algorithms, we ultimately selected random forest to develop the pyroptosis-derived lncRNA signature. This signature was proven to be an independent prognostic factor and exhibited robust performance in three cohorts.

CONCLUSION

We provided novel insight and established a pyroptosis-derived lncRNA signature for patients with LUAD, exhibiting strong predictive capabilities in both the training and validation sets.

Clinical Efficacy and Mechanism of Vitamin D2 in Treating Hashimoto's Thyroiditis

Objective

Hashimoto's thyroiditis (HT) is one of the most common autoimmune diseases, with the highest incidence rate among autoimmune thyroid disorders. Vitamin D2 may have therapeutic effects on HT. This study aimed to elucidate the molecular mechanisms underlying vitamin D2 therapy for HT.

Methods

Differentially expressed genes (DEGs) associated with vitamin D2-treated HT were identified, and the DEG-associated gene enrichment pathway was explored using Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses. The correlation between the hub genes and infiltrating immune cells was investigated, and the interactions among the hub genes and target drug and competing endogenous RNA (ceRNA; long non-coding RNA [lncRNA]-microRNA [miRNA]-messenger RNA [mRNA]) regulatory networks were determined.

Results

GO and KEGG enrichment analyses identified a total of 102 DEGs (6 upregulated and 96 downregulated) in the vitamin D2-treated group samples. The area under the curve values of the identified 10 hub genes was as follows: CCR1(0.920), CXCL1 (0.960), CXCL8 (0.960), EGR1 (0.960), FCGR3B (0.920), FOS (1.000), FPR1 (0.840), MMP9 (0.720), PTGS2 (0.960), and TREM1 (1.000). The immune enrichment scores of the mast cell (P = 0.008), neutrophil (P = 0.016), and plasmacytoid dendritic cell (P = 0.016) were significantly decreased in the vitamin D2-treated group (P < 0.05). The hub gene/drug regulatory network included 8 hub genes, 108 molecular drugs, and 114 interaction relationship pairs. The ceRNA regulatory network included 129 lncRNAs, 145 miRNAs, mRNAs (hub genes), and 324 interaction relationship pairs.

Conclusion

Vitamin D2 may play an immunomodulatory role by regulating the aforementioned immune-related molecules and immune cells, thereby improving its therapeutic effects on HT.

Implications of different cell death patterns for prognosis and immunity in lung adenocarcinoma

In recent years, lung adenocarcinoma (LUAD) has become a focus of attention due to its low response to treatment, poor prognosis, and lack of reliable indicators to predict the progression or therapeutic effect of LUAD. Different cell death patterns play a crucial role in tumor development and are promising for predicting LUAD prognosis. From the TCGA and GEO databases, we obtained bulk transcriptomes, single-cell transcriptomes, and clinical information. Genes in 15 types of cell death were analyzed for cell death index (CDI) signature establishment. The CDI signature using necroptosis + immunologic cell death-related genes was established in the TCGA cohort with the 1-, 2-, 3-, 4- and 5-year AUC values were 0.772, 0.736, 0.723, 0.795, and 0.743, respectively. The prognosis was significantly better in the low CDI group than in the high CDI group. We also investigated the relationship between the CDI signature and clinical variables, published prognosis biomarkers, immune cell infiltration, functional enrichment pathways, and immunity biomarkers. In vitro assay showed that HNRNPF and FGF2 promoted lung cancer cell proliferation and migration and were also involved in cell death. Therefore, as a robust prognosis biomarker, CDI signatures can screen for patients who might benefit from immunotherapy and improve diagnostic accuracy and LUAD patient outcomes.

Physiological and environmental factors affecting cancer risk and prognosis in obesity

Obesity results from a chronic excessive accumulation of adipose tissue due to a long-term imbalance between energy intake and expenditure. Available epidemiological and clinical data strongly support the links between obesity and certain cancers. Emerging clinical and experimental findings have improved our understanding of the roles of key players in obesity-associated carcinogenesis such as age, sex (menopause), genetic and epigenetic factors, gut microbiota and metabolic factors, body shape trajectory over life, dietary habits, and general lifestyle. It is now widely accepted that the cancer-obesity relationship depends on the site of cancer, the systemic inflammatory status, and micro environmental parameters such as levels of inflammation and oxidative stress in transforming tissues. We hereby review recent advances in our understanding of cancer risk and prognosis in obesity with respect to these players. We highlight how the lack of their consideration contributed to the controversy over the link between obesity and cancer in early epidemiological studies. Finally, the lessons and challenges of interventions for weight loss and better cancer prognosis, and the mechanisms of weight gain in survivors are also discussed.

Mast Cell Involvement in the Pathogenesis of Selected Musculoskeletal Diseases

In recent years, there has been a noteworthy revival of interest in the function of mast cells (MCs) in the human body. It is now acknowledged that MCs impact a wide array of processes beyond just allergies, leading to a shift in research direction. Unfortunately, some earlier conclusions were drawn from animal models with flawed designs, particularly centered around the receptor tyrosine kinase (Kit) pathway. Consequently, several subsequent findings may have been unreliable. Thus, what is now required is a re-examination of these earlier findings. Nevertheless, the remaining data are fascinating and hold promise for a better comprehension of numerous diseases and the development of more effective therapies. As the field continues to progress, many intriguing issues warrant further investigation and analysis. For instance, exploring the bidirectional action of MCs in rheumatoid arthritis, understanding the extent of MCs' impact on symptoms associated with Ehlers-Danlos syndrome, and unraveling the exact role of the myofibroblast-mast cell-neuropeptides axis in the joint capsule during post-traumatic contractures are all captivating areas for exploration. Hence, in this review, we summarize current knowledge regarding the influence of MCs on the pathogenesis of selected musculoskeletal diseases, including rheumatoid arthritis, spondyloarthritis, psoriatic arthritis, gout, muscle and joint injuries, tendinopathy, heterotopic ossification, and Ehlers-Danlos syndrome. We believe that this review will provide in-depth information that can guide and inspire further research in this area.

A protocol for single nucleus RNA-seq from frozen skeletal muscle

Single-cell technologies are a method of choice to obtain vast amounts of cell-specific transcriptional information under physiological and diseased states. Myogenic cells are resistant to single-cell RNA sequencing because of their large, multinucleated nature. Here, we report a novel, reliable, and cost-effective method to analyze frozen human skeletal muscle by single-nucleus RNA sequencing. This method yields all expected cell types for human skeletal muscle and works on tissue frozen for long periods of time and with significant pathological changes. Our method is ideal for studying banked samples with the intention of studying human muscle disease.

Oral Exposure to Polystyrene Microplastics of Mice on a Normal or High-Fat Diet and Intestinal and Metabolic Outcomes

BACKGROUND

Microplastics (MPs) are small particles of plastic (≤5mm in diameter). In recent years, oral exposure to MPs in living organisms has been a cause of concern. Leaky gut syndrome (LGS), associated with a high-fat diet (HFD) in mice, can increase the entry of foreign substances into the body through the intestinal mucosa.

OBJECTIVES

We aimed to evaluate the pathophysiology of intestinal outcomes associated with consuming a high-fat diet and simultaneous intake of MPs, focusing on endocrine and metabolic systems.

METHODS

C57BL6/J mice were fed a normal diet (ND) or HFD with or without polystyrene MP for 4 wk to investigate differences in glucose tolerance, intestinal permeability, gut microbiota, as well as metabolites in serum, feces, and liver.

RESULTS

In comparison with HFD mice, mice fed the HFD with MPs had higher blood glucose, serum lipid concentrations, and nonalcoholic fatty liver disease (NAFLD) activity scores. Permeability and goblet cell count of the small intestine (SI) in HFD-fed mice were higher and lower, respectively, than in ND-fed mice. There was no obvious difference in the number of inflammatory cells in the SI lamina propria between mice fed the ND and mice fed the ND with MP, but there were more inflammatory cells and fewer anti-inflammatory cells in mice fed the HFD with MPs in comparison with mice fed the HFD without MPs. The expression of genes related to inflammation, long-chain fatty acid transporter, and Na+/glucose cotransporter was significantly higher in mice fed the HFD with MPs than in mice fed the HFD without MPs. Furthermore, the genus Desulfovibrio was significantly more abundant in the intestines of mice fed the HFD with MPs in comparison with mice fed the HFD without MPs. Muc2 gene expression was decreased when palmitic acid and microplastics were added to the murine intestinal epithelial cell line MODE-K cells, and Muc2 gene expression was increased when IL-22 was added.

DISCUSSION

Our findings suggest that in this study, MP induced metabolic disturbances, such as diabetes and NAFLD, only in mice fed a high-fat diet. These findings suggest that LGS might have been triggered by HFD, causing MPs to be deposited in the intestinal mucosa, resulting in inflammation of the intestinal mucosal intrinsic layer and thereby altering nutrient absorption. These results highlight the need for reducing oral exposure to MPs through remedial environmental measures to improve metabolic disturbance under high-fat diet conditions. https://doi.org/10.1289/EHP11072.

Development and validation of a novel diagnostic model for musculoskeletal aging (sarcopenia) based on cuproptosis-related genes associated with immunity

OBJECTIVE

Sarcopenia is a geriatric disease characterized by accelerated skeletal muscle mass and function loss due to aging. Cell death plays a pivotal role in the onset and progress of sarcopenia. The purpose of this study was to investigate the role of cuproptosis-related genes (CRGs) and immune infiltration in sarcopenia development.

METHODS

Three microarray expression datasets from the Gene Expression Omnibus (GEO) database were merged and batch-corrected by R software to identify differentially expressed genes (DEGs) between old and young skeletal muscles. Subsequently, DEGs were subjected to functional enrichment and gene set enrichment analysis (GSEA) to investigate the roles of DEGs and immune infiltration in the pathogenesis of musculoskeletal aging. Then, ssGSEA was performed to calculate the proportion of immune cells and functions within each muscle sample to analyze the differences between the older and young healthy muscle groups. In order to select candidate CRGs, the correlation between CRGs and immune infiltration was analyzed. Finally, a novel nomogram model of musculoskeletal aging was constructed based on candidate CRGs associated with immunity. Additionally, the diagnostic model based on key CRGs was tested using a validation dataset, and its diagnostic performance was evaluated by the area under curve (AUC) value.

RESULTS

141 DEGs were identified between 45 older samples and 50 young healthy samples. Compared to young healthy muscle tissues, significantly lower infiltration levels of T-regulatory cells were identified in older muscle tissues, while dendritic cells (DCs) and mast cells were relatively higher. Based on the CRGs from seven candidates, a novel model with high prediction efficiency (AUC = 0.856) was established to diagnose and screen for sarcopenia.

CONCLUSION

The CRGs associated with immunity may play a vital role in the development of musculoskeletal aging, providing a novel avenue for early diagnosis. Furthermore, immune cell infiltration is essential for the progression of musculoskeletal aging.

ACSL4 contributes to ferroptosis-mediated rhabdomyolysis in exertional heat stroke

BACKGROUND

Rhabdomyolysis (RM) is a common complication of exertional heat stroke (EHS) and constitutes a direct cause of death. However, the mechanism underlying RM following EHS remains unclear.

METHODS

The murine EHS model was prepared by our previous protocol. RNA sequencing is applied to identify the pathological pathways that contribute to RM following EHS. Inhibition of the acyl-CoA synthetase long-chain family member 4 (ACSL4) was achieved by RNA silencing in vitro prior to ionomycin plus heat stress exposure or pharmacological inhibitors in vivo prior to heat and exertion exposure. The histological changes, the iron accumulation, oxidized phosphatidylethanolamines species, as well as histological evaluation and levels of lipid metabolites in skeletal muscle tissues were measured.

RESULTS

We demonstrated that ferroptosis contributes to RM development following EHS. Ferroptosis inhibitor ferrostatin-1 administration once EHS onset significantly ameliorated the survival rate of EHS mice from 35.357% to 52.288% within 24 h after EHS (P = 0.0028 compared with control) and markedly inhibited RM development induced by EHS. By comparing gene expression of between sham heat rest (SHR) (n = 3) and EHS (n = 3) mice in the gastrocnemius (Gas) muscle tissue, we identified that Acsl4 mRNA expression is elevated in Gas muscle tissue of EHS mice (P = 0.0038 compared with SHR), so as to its protein levels (P = 0.0001 compared with SHR). Followed by increase in creatine kinase (CK) and myoglobin (MB) levels, the labile iron accumulation, decrease in glutathione peroxidase 4 (GPX4) expression, and elevation of lipid peroxidation products. From in vivo and in vitro experiments, inhibition of Acsl4 significantly improves muscle cell death caused by EHS, thereby ameliorating RM development, followed by reduction in CK and MB levels by 30-40% (P < 0.0001; n = 8-10) and 40% (P < 0.0001; n = 8-10), restoration of GPX4 expression, and decrease in lipid peroxidation products. Mechanistically, ACSL4-mediated RM seems to be Yes-associated protein (YAP) dependent via TEA domain transcription factor1/TEA domain transcription factor4.

CONCLUSIONS

These findings demonstrate an important role of ACSL4 in mediating ferroptosis activation in the development of RM following EHS and suggest that targeting ACSL4 may represent a novel therapeutic strategy to limit the skeletal muscle cell death and prevent RM after EHS.

Extracellular lipidome change by an SGLT2 inhibitor, luseogliflozin, contributes to prevent skeletal muscle atrophy in db/db mice

BACKGROUND

Diabetes mellitus increases the excretion of urinary glucose from the renal glomeruli due to elevated blood glucose levels. In the renal tubules, SGLT2 is expressed and reabsorbs the excreted urinary glucose. In the pathogenesis of diabetes mellitus, glucose reabsorption by SGLT2 is increased, and SGLT2 inhibitors improve hyperglycaemia by inhibiting this reabsorption. When urinary glucose excretion is enhanced, glucose supply to skeletal muscle may be insufficient and muscle protein catabolism may be accelerated. On the other hand, SGLT2 inhibitors not only ameliorate hyperglycaemia but also improve fatty acid metabolism in muscle, which may prevent muscle atrophy.

METHODS

Eight-week-old male db/m mice or db/db mice were fed a standard diet with or without the SGLT2i luseogliflozin (0.01% w/w in chow) for 8 weeks. Mice were sacrificed at 16 weeks of age, and skeletal muscle and serum lipidomes, as well as skeletal muscle transcriptome, were analysed.

RESULTS

Administration of SGLT2i led to not only decreased visceral fat accumulation (P = 0.004) but also increased soleus muscle weight (P = 0.010) and grip strength (P = 0.0001). The levels of saturated fatty acids, especially palmitic acid, decreased in both muscles (P = 0.017) and sera (P = 0.041) upon administration of SGLT2i, while the content of monosaturated fatty acids, especially oleic acid, increased in both muscle (P < 0.0001) and sera (P = 0.009). Finally, the accumulation of transcripts associated with fatty acid metabolism, such as Scd1, Fasn, and Elovl6, and of muscle atrophy-associated transcripts, such as Foxo1, Mstn, Trim63, and Fbxo32, decreased following SGLT2i administration.

CONCLUSIONS

Intramuscular fatty acid metabolism and gene expression were influenced by the extracellular lipidome, which was modified by SGLT2i. Hence, secondary effects, other than the hypoglycaemic effects of SGLT2i, might lead to the alleviation of sarcopenia.

Sarcopenia Predicts Cancer Mortality in Male but Not in Female Patients Undergoing Surgery for Cholangiocellular Carcinoma

Simple Summary

Cholangiocellular adenocarcinoma is the second most common primary liver tumor. If resectable, this is the therapeutic method of choice. Unfortunately, there are insufficient prognostic markers to determine which patients benefit most from surgery and which do not. The general condition of the patient, especially their muscle mass and quality, has become more and more the focus of recent research as a possible marker for therapeutic outcome. In our study we investigated how the preoperative muscle mass of patients with cholangiocellular adenocarcinoma affects postoperative overall survival. We showed that patients with a higher preoperative muscle mass had a significantly longer survival than patients with reduced muscle mass. Furthermore, we were able to show that this is particularly relevant in men and that in women preoperative muscle mass plays a significantly less important role in postoperative survival than in men.

Abstract

Introduction: Surgery represents the only curative treatment option for patients with cholangiocarcinoma. However, complete tumor resection requires extensive surgery in many patients, and it is still debated which patients represent the ideal candidates for such therapy in terms of overall survival. Sarcopenia has been associated with an adverse outcome for various malignancies, but its role in the context of patients undergoing tumor resection for cholangiocellular adenocarcinoma (CCA) is only poorly understood. Here, we evaluated the role of sarcopenia in the outcome of CCA patients undergoing radical tumor resection. Methods: Pre-operative CT scans were used to assess the skeletal muscle index (L3SMI) as well as the psoas muscle index (L3PMI) in n = 76 patients receiving curative intended surgery for CCA. L3SMI and L3PMI were correlated with clinical and laboratory markers. Results: Patients with a skeletal muscle index or psoas muscle index above an established ideal cut-off (54.26 and 1.685 cm²/m²) showed a significantly better overall survival in Kaplan–Meier Curve analyses (L3SMI: 1814 days (95% CI: 520–3108) vs. 467 days (95% CI: 225–709) days; log rank X²(1) = 7.18, p = 0.007; L3PMI: 608 days (95% CI: 297–919) vs. 87 days (95% CI: 33–141), log rank X²(1) = 18.71; p < 0.001). Notably, these findings, especially for L3PMI, were confirmed in univariate (L3SMI: HR 0.962 (0.936–0.989); p = 0.006; L3PMI: HR 0.529 (0.366–0.766); p ≤ 0.001) and multivariate Cox regression analyses. Further analyses revealed that the prognostic value of both L3SMI and L3PMI was restricted to male patients, while in female patients survival was independent of the individual muscle mass. Conclusion: Measurement of muscle mass from preoperative CT scans represents an easily obtainable tool to estimate patient prognosis following curative surgery. The prognostic value was restricted to male patients, while in female patients these parameters did not reflect the patient outcome.

Activated mast cells in skeletal muscle can be a potential mediator for cancer-associated cachexia

BACKGROUND

Eighty per cent of United States advanced cancer patients faces a worsened prognosis due to cancer-associated cachexia. Inflammation is one driver of muscle atrophy in cachexia, and skeletal muscle-resident immune cells could be a source of inflammation. This study explores the efficacy of cancer activated skeletal muscle-resident mast cells as a biomarker and mediator of cachexia.

METHODS

Individual gene markers for immune cells were assessed in a publicly available colon carcinoma cohort of normal (n = 3), moderate cachexia (n = 3), and severe cachexia (n = 4) mice. Lewis lung carcinoma (LL/2) cells induced cachexia in C57BL/6 mice, and a combination of toluidine blue staining, immunofluorescence, quantitative polymerase chain reaction, and western blots measured innate immune cell expression in hind limb muscles. In vitro measurements included C2C12 myotube diameter before and after treatment with media from primary murine mast cells activated with LL/2 conditioned media. To assess translational potential in human samples, innate immune cell signatures were assessed for correlation with skeletal muscle atrophy and apoptosis, dietary excess, and cachexia signatures in normal skeletal muscle tissue. Gene set enrichment analysis was performed with innate immune cell signatures in publicly available cohorts for upper gastrointestinal (GI) cancer and pancreatic ductal adenocarcinoma (PDAC) patients (accession: GSE34111 and GSE130563, respectively).

RESULTS

Individual innate immunity genes (TPSAB1 and CD68) showed significant increases in severe cachexia (weight loss > 15%) mice in a C26 cohort (GSE24112). Induction of cachexia in C57BL/6 mice with LL/2 subcutaneous injection significantly increased the number of activated skeletal muscle-resident degranulating mast cells. Murine mast cells activated with LL/2 conditioned media decreased C2C12 myotube diameter (P ≤ 0.05). Normal human skeletal muscle showed significant positive correlations between innate immune cell signatures and muscle apoptosis and atrophy, dietary excess, and cachexia signatures. The mast cell signature was up-regulated (positive normalized enrichment score and false discovery rate ≤ 0.1) in upper GI cachectic patients (n = 12) compared with control (n = 6), as well as in cachectic PDAC patients (n = 17) compared with control patients (n = 16).

CONCLUSIONS

Activated skeletal muscle-resident mast cells are enriched in cachectic muscles, suggesting skeletal-muscle resident mast cells may serve as a biomarker and mediator for cachexia development to improve patient diagnosis and prognosis.