Tissue Lipidomic Alterations Induced by Prolonged Dexamethasone Treatment

The recent development, application, and future prospects of muscle atrophy animal models

Muscle atrophy, characterized by the loss of muscle mass and function, is a hallmark of sarcopenia and cachexia, frequently associated with aging, malignant tumors, chronic heart failure, and malnutrition. Moreover, it poses significant challenges to human health, leading to increased frailty, reduced quality of life, and heightened mortality risks. Despite extensive research on sarcopenia and cachexia, consensus in their assessment remains elusive, with inconsistent conclusions regarding their molecular mechanisms. Muscle atrophy models are crucial tools for advancing research in this field. Currently, animal models of muscle atrophy used for clinical and basic scientific studies are induced through various methods, including aging, genetic editing, nutritional modification, exercise, chronic wasting diseases, and drug administration. Muscle atrophy models also include in vitro and small organism models. Despite their value, each of these models has certain limitations. This review focuses on the limitations and diverse applications of muscle atrophy models to understand sarcopenia and cachexia, and encourage their rational use in future research, therefore deepening the understanding of underlying pathophysiological mechanisms, and ultimately advancing the exploration of therapeutic strategies for sarcopenia and cachexia.

Analyses of plasma metabolites using a high performance four-channel CIL LC-MS method and identification of metabolites associated with enteric methane emissions in beef cattle

Reducing enteric methane (one greenhouse gas) emissions from beef cattle not only can be beneficial in reducing global warming, but also improve efficiency of nutrient utilization in the production system. However, direct measurement of enteric methane emissions on individual cattle is difficult and expensive. The objective of this study was to detect plasma metabolites that are associated with enteric methane emissions in beef cattle. Average enteric methane emissions (CH4) per day (AVG_DAILYCH4) for each individual cattle were measured using the GreenFeed emission monitoring (GEM) unit system, and beef cattle with divergent AVG_DAILYCH4 from Angus (n = 10 for the low CH4 group and 9 for the high CH4 group), Charolais (n = 10 for low and 10 for = high), and Kinsella Composite (n = 10 for low and 10 for high) populations were used for plasma metabolite quantification and metabolite-CH4 association analyses. Blood samples of these cattle were collected near the end of the GEM system tests and a high performance four-channel chemical isotope labeling (CIL) liquid chromatography (LC) mass spectrometer (MS) method was applied to identify and quantify concentrations of metabolites. The four-channel CIL LC-MS method detected 4235 metabolites, of which 1105 were found to be significantly associated with AVG_DAILYCH4 by a t-test, while 1305 were significantly associated with AVG_DAILYCH4 by a regression analysis at p<0.05. Both the results of the t-test and regression analysis revealed that metabolites that were associated with enteric methane emissions in beef cattle were largely breed-specific whereas 4.29% to 6.39% CH4 associated metabolites were common across the three breed populations and 11.07% to 19.08% were common between two breed populations. Pathway analyses of the CH4 associated metabolites identified top enriched molecular processes for each breed population, including arginine and proline metabolism, arginine biosynthesis, butanoate metabolism, and glutathione metabolism for Angus; beta-alanine metabolism, pyruvate metabolism, glycolysis / gluconeogenesis, and citrate cycle (TCA cycle) for Charolais; phenylalanine, tyrosine and tryptophan biosynthesis, phenylalanine metabolism, arginine biosynthesis, and arginine and proline metabolism for Kinsella Composite. The detected CH4 associated metabolites and enriched molecular processes will help understand biological mechanisms of enteric methane emissions in beef cattle. The detected CH4 associated plasma metabolites will also provide valuable resources to further characterize the metabolites and verify their utility as biomarkers for selection of cattle with reduced methane emissions.

An experimental study for quantitative assessment of fatty infiltration and blood flow perfusion in quadriceps muscle of rats using IDEAL-IQ and BOLD-MRI for early diagnosis of sarcopenia

BACKGROUND

Severe sarcopenia may result in severe disability. Early diagnosis is currently the key to enhancing the treatment of sarcopenia, and there is an urgent need for a highly sensitive and dependable tool to evaluate the course of early sarcopenia in clinical practice. This study aims to investigate longitudinally the early diagnosability of magnetic resonance imaging (MRI)-based fat infiltration and blood flow perfusion technology in sarcopenia progression.

METHODS

48 Sprague-Dawley rats were randomly assigned into six groups that were based on different periods of dexamethasone (DEX) injection (0, 2, 4, 6, 8, 10 days). Multimodal MRI was scanned to assess muscle mass. Grip strength and swimming exhaustion time of rats were measured to assess muscle strength and function. Immunofluorescence staining for CD31 was employed to assess skeletal muscle capillary formation, and western blot was used to detect vascular endothelial growth factor-A (VEGF-A) and muscle ring finger-1 (MuRF-1) protein expression. Subsequently, we analyzed the correlation between imaging and histopathologic parameters. A receiver operating characteristic (ROC) analysis was conducted to assess the effectiveness of quantitative MRI parameters for discriminating diagnosis in both pre- and post-modeling of DEX-induced sarcopenic rats.

RESULTS

Significant differences were found in PDFF, R2* and T2 values on day 2 of DEX-induction compared to the control group, occurring prior to the MRI-CSA values and limb grip strength on day 6 of induction and swimming exhaustion time on day 8 of induction. There is a strong correlation between MRI-CSA with HE-CSA values (r = 0.67; p < 0.001), oil red O (ORO) area with PDFF (r = 0.67; p < 0.001), microvascular density (MVD) (r = -0.79; p < 0.001) and VEGF-A (r = -0.73; p < 0.001) with R2*, MuRF-1 with MRI-CSA (r = -0.82; p < 0.001). The AUC of PDFF, R2*, and T2 values used for modeling evaluation are 0.81, 0.93, and 0.98, respectively.

CONCLUSION

Imaging parameters PDFF, R2*, and T2 can be used to sensitively evaluate early pathological changes in sarcopenia. The successful construction of a sarcopenia rat model can be assessed when PDFF exceeds 1.25, R2* exceeds 53.85, and T2 exceeds 33.88.

The Effects of Probiotic Bacillus Spores on Dexamethasone-Treated Rats

Glucocorticoids are effective anti-inflammatory and immunosuppressive agents. Long-term exposure is associated with multiple metabolic side effects. Spore-forming probiotic bacteria have shown modulatory properties regarding glycolipid metabolism and inflammation. The aim of this study was to evaluate, for the first time, the effects of Bacillus species spores (B. licheniformis, B. indicus, B. subtilis, B. clausii, and B. coagulans) alone and in combination with metformin against dexamethasone-induced systemic disturbances. A total of 30 rats were randomly divided into 5 groups: group 1 served as control (CONTROL), group 2 received dexamethasone (DEXA), group 3 received DEXA and MegaSporeBiotic (MSB), group 4 received DEXA and metformin (MET), and group 5 received DEXA, MSB, and MET. On the last day of the experiment, blood samples and liver tissue samples for histopathological examination were collected. We determined serum glucose, total cholesterol, triglycerides, tumor necrosis factor-alpha (TNF-α), interleukin-6 (IL-6), interleukin-10 (IL-10), catalase, total antioxidant capacity (TAC), and metformin concentration. DEXA administration caused hyperglycemia and hyperlipidemia, increased inflammation cytokines, and decreased antioxidant markers. Treatment with MSB reduced total cholesterol, suggesting that the administration of Bacillus spores-based probiotics to DEXA-treated rats could ameliorate metabolic parameters.

The metabolic and lipidomic profiling of the effects of tracheal occlusion in a rabbit model of congenital diaphragmatic hernia

PURPOSE

Fetal tracheal occlusion (TO) reverses the pulmonary hypoplasia associated with congenital diaphragmatic hernia (CDH), but its mechanism of action remains poorly understood. 'Omic' readouts capture metabolic and lipid processing function, which aid in understanding CDH and TO metabolic mechanisms.

METHODS

CDH was created in fetal rabbits at 23 days, TO at 28 days and lung collection at 31 days (Term ∼32 days). Lung-body weight ratio (LBWR) and mean terminal bronchiole density (MTBD) were determined. In a cohort, left and right lungs were collected, weighed, and samples homogenized, and extracts collected for non-targeted metabolomic and lipidomic profiling via LC-MS and LC-MS/MS, respectively.

RESULTS

LBWR was significantly lower in CDH while CDH + TO was similar to controls (p = 0.003). MTBD was significantly higher in CDH fetuses and restored to control and sham levels in CDH + TO (p < 0.001). CDH and CDH + TO resulted in significant differences in metabolome and lipidome profiles compared to sham controls. A significant number of altered metabolites and lipids between the controls and CDH groups and the CDH and CDH + TO fetuses were identified. Significant changes in the ubiquinone and other terpenoid-quinone biosynthesis pathway and the tyrosine metabolism pathway were observed in CDH + TO.

CONCLUSION

CDH + TO reverses pulmonary hypoplasia in the CDH rabbit, in association with a specific metabolic and lipid signature. A synergistic untargeted 'omics' approach provides a global signature for CDH and CDH + TO, highlighting cellular mechanisms among lipids and other metabolites, enabling comprehensive network analysis to identify critical metabolic drivers in disease pathology and recovery.

TYPE OF STUDY

Basic Science, Prospective.

LEVEL OF EVIDENCE

II.

Hydrocortisone-Containing Animal-Derived Food Intake Affects Lipid Nutrients Utilization

SCOPE

As the tremendous increases in consumption of animal-derived food, endogenous hydrocortisone migrating along the food chain to organism arouses extensive attention. This study aims to investigate the cumulative impacts of dietary hydrocortisone intake and mechanistic understanding on metabolism of lipid nutrients.

METHODS AND RESULTS

A total of 120 porcine muscles samples with different concentrations of hydrocortisone are collected at three time points. An operational food chain simulation framework is constructed and 175 lipid molecules are identified by UHPLC-Q-Orbitrap HRMS. Compared to the control group, 66 lipid molecules are significantly different, including 17 triglycerides and 31 glycerophospholipids. Integrated analyses of lipidomics and proteomics indicate that hydrocortisone promotes adipose triglyceride lipase and hormone sensitive lipase activity to precondition for triglycerides hydrolysis. Quantitative lipidomics analysis shows the presence of hydrocortisone decreases the concentration of docosahexaenoic acid (3.66 ± 0.15-3.09 ± 0.12 mg kg^-1 ) and eicosapentanoic acid (0.54 ± 0.09-0.48 ± 0.06 mg kg^-1 ). A noteworthy increase of most saturated triglycerides concentration with the prolonging of time is observed.

CONCLUSIONS

Hydrocortisone originating from animal-derived food induces glycerophospholipids degradation and triglycerides hydrolysis through promoting adipose triglyceride lipase, hormone sensitive lipase, and phosphoglycerate kinase activity and further intervenes lipid nutrients utilization.

Coriander Oil Reverses Dexamethasone-Induced Insulin Resistance in Rats

In the present study, we aimed to investigate the effect of coriander oil on dexamethasone-induced insulin resistance in rats and characterize its chemical composition using gas chromatography-mass spectrometry (GC-MS). Rats were divided into five groups (n = 6): Normal control, insulin resistance (IR) control, IR + metformin (50 mg/kg/day, PO, Per Oral), IR + coriander oil low dose (0.5 mL/kg, PO), and IR + coriander oil high dose (1 mL/kg, PO). IR groups were injected with a dose of 10 mg/kg dexamethasone subcutaneously for four consecutive days. All groups received either vehicle or drugs daily for four days. Animal weights and pancreatic weights were measured, and oral glucose tolerance test was performed at the end of study. Fasting glucose, triglycerides (TG), total cholesterol (TC), HDL and insulin levels in serum, MDA, and GSH levels in pancreatic tissue were measured and HOMA-IR was calculated. Immunoexpression of apoptosis markers BAX, and BCL2 was measured in pancreatic tissues and BAX/BCL2 ratio was calculated. Histopathological examination of pancreatic tissues was also performed. Pancreatic weight, serum HDL, pancreatic GSH, and BCL2 were decreased while serum glucose, insulin, TG, TC levels, AUC of OGGT, HOMA-IR, pancreatic MDA, BAX, and BAX/BCL2 ratio were increased in IR rats. Histopathological examination showed congestion, vacuolation and hemorrhage in pancreatic islets. These changes were reversed by metformin and the high dose of coriander oil treatments. The obtained activities could be attributed to the presence of 21 volatile compounds, identified by GC-MS. Our study indicates that coriander oil can be used as an adjuvant antihyperglycemic agent in type 2 diabetes. Further experiments are needed to determine the therapeutic dose and the treatment time.

Potent Anti-Inflammatory, Arylpyrazole-Based Glucocorticoid Receptor Agonists That Do Not Impair Insulin Secretion

Glucocorticoids (GCs) are widely used in medicine for their role in the treatment of autoimmune-mediated conditions, certain cancers, and organ transplantation. The transcriptional activities GCs elicit include transrepression, postulated to be responsible for the anti-inflammatory activity, and transactivation, proposed to underlie the undesirable side effects associated with long-term use. A GC analogue that could elicit only transrepression and beneficial transactivation properties would be of great medicinal value and is highly sought after. In this study, a series of 1-(4-substituted phenyl)pyrazole-based GC analogues were synthesized, biologically screened, and evaluated for SARs leading to the desired activity. Activity observed in compounds bearing an electron deficient arylpyrazole moiety showed promise toward a dissociated steroid, displaying transrepression while having limited transactivation activity. In addition, compounds 11aa and 11ab were found to have anti-inflammatory efficacy comparable to that of dexamethasone at 10 nM, with minimal transactivation activity and no reduction of insulin secretion in cultured rat 832/13 beta cells.

Comprehensive Serum Lipidomics for Detecting Incipient Dementia in Parkinson's Disease

While a number of methods are available for analyzing lipids, unbiased untargeted lipidomics with high coverage remains a challenge. In this work, we report a study of isotope-standard-assisted liquid chromatography mass spectrometry lipidomics of serum for biomarker discovery. We focus on Parkinson's disease (PD), a neurodegenerative disorder that often progresses to dementia. Currently, the diagnosis of PD is purely clinical and there is limited ability to predict which PD patients will transition to dementia, hampering early interventions. We studied serum samples from healthy controls and PD patients with no clinical signs of dementia. A follow-up 3 years later revealed that a subset of PD patients had transitioned to dementia. Using the baseline samples, we constructed two biomarker panels to differentiate (1) PD patients from healthy controls and (2) PD patients that remained cognitively stable from PD patients with incipient dementia (diagnosed 3 years after sample collection). The proposed biomarker panels displayed excellent performance and may be useful for detecting prodromal PD dementia, allowing early interventions and prevention efforts. The biochemistry of significantly changed lipids is also discussed within the current knowledge of neurological pathologies. Our results are promising and future work using a larger cohort of samples is warranted.

Emodin ameliorates acute pancreatitis-induced lung injury by suppressing NLRP3 inflammasome-mediated neutrophil recruitment

Severe acute pancreatitis (SAP) activates the systemic inflammatory response and is potentially lethal. The aim of the present study was to determine the effects of emodin on acute lung injury (ALI) in rats with SAP and investigate the role of the Nod-like receptor protein 3 (NLRP3) inflammasome and its association with neutrophil recruitment. Sodium taurocholate (5.0%) was used to establish the SAP model. All animals were randomly assigned into four groups: Sham, SAP, emodin and dexamethasone (positive control drug) groups (n=10 mice per group). Histopathology observation of pancreatic and lung tissues was detected by hematoxylin and eosin staining. The levels of serum amylase, IL-1β and IL-18 were measured by ELISA. Single-cell suspensions were obtained from enzymatically digested lung tissues, followed by flow cytometric analysis for apoptosis. In addition, the expression levels of NLRP3 inflammasome-associated and apoptosis-associated proteins in lung tissues were measured by western blotting. Moreover, lymphocyte antigen 6 complex locus G6D⁺ (Ly6G⁺) cell recruitment was detected using immunohistochemical analysis. The results revealed that emodin markedly improved pancreatic histological injury and decreased the levels of serum amylase, IL-1β and IL-18. Pulmonary edema and apoptosis were significantly alleviated by emodin. Additionally, the protein expression levels of intercellular adhesion molecule 1, NLRP3, apoptosis-associated speck-like protein containing a CARD and cleaved caspase-1 were downregulated following emodin treatment. Moreover, emodin inhibited Ly6G⁺ cell recruitment in lung tissues. The present study demonstrated that emodin may offer protection against ALI induced by SAP via inhibiting and suppressing NLRP3 inflammasome-mediated neutrophil recruitment and may be a novel therapeutic strategy for the clinical treatment of ALI.