Aminophylline Improves Ventilator-Induced Diaphragmatic Dysfunction by Targeting IGF-1-FOXO1-MURF1 Pathway.

BACKGROUND: The usage of life-saving mechanical ventilation (MV) could cause ventilator-induced diaphragmatic dysfunction (VIDD), increasing both mortality and morbidity. Aminophylline (AP) has the potential to enhance the contractility of animal skeletal muscle fibers and improve the activity of human respiratory muscles, and the insulin-like growth factor-1 (IGF-1)- forkhead box protein O1 (FOXO1)-muscle RING finger-1 (MURF1) pathway plays a crucial role in skeletal muscle dysfunction. This study aimed to investigate the impact of AP on VIDD and to elucidate the role of the IGF-1-FOXO1-MURF1 pathway as an underlying mechanism. METHODS: Rat models of VIDD were established through MV treatment. IGF-1 lentiviral (LV) interference (LV-IGF-1-shRNA; controlled by lentiviral negative control LV-NC) was employed to inhibit IGF-1 expression and thereby block the IGF-1-FOXO1-MURF1 pathway. Protein and mRNA levels of IGF-1, FOXO1, and MURF1 were assessed using western blot and real-time reverse transcriptase-polymerase chain reaction (RT-qPCR), respectively. Diaphragm contractility and morphometry were examined through measurement of compound muscle action potentials (CMAPs) and hematoxylin and eosin (H&E) staining. Oxidative stress was evaluated by levels of hydrogen peroxide (H2O2), superoxide dismutase (SOD), antioxidant glutathione (GSH), and carbonylated protein. Mitochondrial stability was assessed by measuring the mitochondrial membrane potential (MMP), and mitochondrial fission and mitophagy were examined through protein levels of dynamin-related protein 1 (DRP1), mitofusin 2 protein (MFN2), phosphatase and tensin homolog (PTEN)-induced kinase 1 (PINK1), and Parkin (western blot). Apoptosis was evaluated using the terminal deoxynucleotidyl transferase-mediated uridine 5'-triphosphate (UTP) nick-end labeling (TUNEL) assay and levels of Bax, B-cell lymphoma 2 (BCL-2), and Caspase-3. Levels of Atrogin-1, neuronally expressed developmentally downregulated 4 (NEDD4), and muscle ubiquitin ligase of SCF complex in atrophy-1 (MUSA1) mRNA, as well as ubiquitinated protein, were utilized to determine protein degradation. Furthermore, the SUnSET (surface sensing of translation) method was employed to determine rates of protein synthesis. RESULTS: MV treatment upregulated IGF-1 while downregulated FOXO1 and MURF1 (p < 0.05). AP administration reversed IGF-1, FOXO1 and MURF1 (p < 0.05), which was suppressed again by IGF-1 inhibition (p < 0.05), demonstrating the blockage of the IGF-1-FOXO1-MURF1 pathway. MV treatment caused decreased CMAP and cross-sectional areas of diaphragm muscle fibers, and increased time course of CMAP (p < 0.05). Additionally, oxidative stress, cell apoptosis, and protein degradation were increased and mitochondrial stability was decreased by MV treatment (p < 0.05). Conversely, AP administration reversed all these changes induced by MV, but this reversal was disrupted by the blockage of the IGF-1-FOXO1-MURF1 pathway. CONCLUSIONS: In this study, MV treatment induced symptoms of VIDD in rats, which were all effectively reversed by AP regulating the IGF-1-FOXO1-MURF1 pathway, demonstrating the potential of AP in ameliorating VIDD.

IGF-1 Regulates Skeletal Muscle Degradation and Remolding in Ventilator-Induced Diaphragmatic Dysfunction by Mediating FOXO1 Expression.

BACKGROUND: Mechanical ventilation (MV) sustains life in critically ill patients by providing adequate alveolar ventilation. However, prolonged MV could induce inspiratory muscle atrophy known as ventilator-induced diaphragmatic dysfunction (VIDD). Insulin-like growth factor (IGF)-1 has been proven to play crucial roles in regulating skeletal muscle size and function. Meanwhile, the forkhead box protein O1 (FOXO1) has been linked to muscle atrophy. This study aimed to explore the effect of IGF-1 on muscle degradation and remodeling in VIDD and delved into the association of the underlying mechanism involving FOXO1. METHODS: VIDD models were established by treating rats with MV. Adeno-associated virus (AAV) was used for transfection to construct IGF-1 and/or FOXO1 overexpressed rats. There were four groups in this study: normal rats (NC), normal rats with MV treatment (MV), IGF-1-overexpressed rats with MV treatment (MV+IGF-1), and rats overexpressing both IGF-1 and FOXO1 with MV treatment (MV+IGF-1+FOXO1). Protein levels were measured by western blot or enzyme-linked immunosorbent assay (ELISA), and mRNA levels were detected by real-time reverse transcriptase-polymerase chain reaction (RT-qPCR). IGF-1 and FOXO1 expression were validated by detecting mRNA and protein levels. Diaphragmatic muscle contractility and morphometry were tested using stimulating electrodes in conjunction with hematoxylin and eosin (H&E) staining. Interleukin (IL)-6 and carbonylated protein were used for evaluating muscle atrophy and oxidation, respectively. Protein degradation was determined by troponin-I level and tyrosine release. Apoptosis was assessed using the terminal deoxynucleotidyl transferase-mediated uridine 5'-triphosphate (UTP) nick-end labeling (TUNEL) assay, alongside markers like Bax, B-cell lymphoma 2 (BCL-2), and Cleaved Caspase-3. Atrogin-1, muscle RING finger 1 (MURF1), neuronally expressed developmentally downregulated 4 (NEDD4), muscle ubiquitin ligase of SCF complex in atrophy-1 (MUSA1), and ubiquitinated protein was used to determine proteolysis. Additionally, protein synthesis was measured by assessing the rates of mixed muscle protein (MMP) and myosin heavy chain (MHC). RESULTS: MV treatment caused IGF-1 downregulation (p < 0.01) and FOXO1 upregulation (p < 0.01). The IGF-1 upregulation downregulated FOXO1 in the MV+IGF-1 group (p < 0.001) while IGF-1 and FOXO1 were both upregulated in the MV+IGF-1+FOXO1 group (p < 0.001). The treatment of MV decreased muscle contractility and cross-sectional areas of diaphragm muscle fibers (p < 0.01). Additionally, IL-6, troponin-1, tyrosine release, carbonylated protein, TUNEL positive nuclei, Bax, Cleaved Caspase-3, Atrogin-1, MURF1, neuronally expressed developmentally downregulated 4 (NEDD4), MUSA1, and ubiquitinated protein levels increased significantly in MV group (p < 0.001) while levels of BCL-2, fractional synthetic rate of MMP and MHC, and type I and type II MHC protein mRNA expression decreased in MV group (p < 0.001). All of these alterations were reversed in the MV+IGF-1 group (p < 0.01), while the IGF-1-induced reversion was disrupted in the MV+IGF-1+FOXO1 group (p < 0.01). CONCLUSIONS: IGF-1 may protect diaphragmatic muscles from VIDD-induced structural damage and function loss by downregulating FOXO1. This action suppresses muscle breakdown and facilitates muscle remodeling in diaphragmatic muscles affected by VIDD.

Serum YKL-40 predicts long-term outcome in patients undergoing primary percutaneous coronary intervention for ST-segment elevation myocardial infarction.

Serum YKL-40, a potential inflammatory marker, is greatly increased at the early stage of ST-segment elevation myocardial infarction (STEMI). Here, we hypothesized that YKL-40 levels at admission could predict the long-term outcomes after STEMI.A total of 324 patients with acute STEMI undergoing primary percutaneous coronary intervention (PCI) were consecutively enrolled and followed for 24 months. The baseline clinical and procedural data were recorded, and serum YKL-40 levels at admission were measured using ELISA method. The endpoint of interest was major adverse cardiac event (MACE), including all-cause death, recurrent myocardial infarction, and hospitalization for heart failure.Patients with elevated serum YKL-40 levels (≥126.8 ng/mL) were more likely to be older and smoker and to present with type 2 diabetes, advanced Killip class, multivessel disease and intra-aortic balloon pump, with increased levels of admission glucose, triglyceride, and high-sensitivity C-reactive protein and decreased level of high-density lipoprotein cholesterol. During the follow-up period, the incidence of MACE was notably higher in the high than in the low YKL-40 groups (28.4% vs 11.1%, P < .001). Kaplan-Meier curve showed that elevated YKL-40 levels were associated with reduced MACE-free survivals (log-rank P < .001). In multivariate Cox regression analysis, we found that high serum YKL-40 level was an independent predictor of MACE after controlling for clinical and angiographic variables (hazard ratio: 1.65, 95% confidence interval: 1.14-2.39, P = .008).The results of our study indicate that serum YKL-40 may be used as a biomarker to predict the long-term outcome after PCI in patients with STEMI.

[Efficacy of local injection of RhTNFR: Fc in collagen-induced arthritis of rats].

OBJECTIVE: To evaluate the efficacy of recombinant human tumor necrosis factor-α receptor II: IgG fusion protein (RhTNFR:Fc) local injection in collagen-induced arthritis (CIA) of rats. METHODS: Twenty-four CIA rats were randomly divided into 3 groups: single therapy (Group I), multiply therapies (Group II) and control (Group III). Group I received normal saline thrice after a single RhTNFR:Fc local treatment while Groups II and III had 4 times of RhTNFR:Fc or normal saline local injection. The severities of right ankle and systemic inflammation were assessed by arthritis index (AI) at baseline and every week after local injection (visits 1, 2, 3 and 4). Serum C reactive protein (CRP) was measured after the last visit. And right ankles were further examined through radiology and pathology. RESULTS: Local or systemic AI of Group I were significantly lower than that of baseline at visit 1 (P < 0.05), but increased during other visits. And local or systemic AI of Group II gradually decreased at each follow-up, but AI of Group III showed no decline. The radiographic scores (5.70±0.67 and 4.90±0.73), histopathological scores (6.00±0.67 and 3.80±0.91) and serum CRP concentration (7.50±0.87 and 3.09±0.76 µg/ml) of Group I and Group II were lower than those of Group III (6.60±1.26, 7.10±0.7 and 12.15±3.47 µg/ml, P < 0.05). And all these parameters of Group I were higher than those of Group II (P < 0.05). CONCLUSION: Local injection of RhTNFR:Fc can effectively alleviate disease activity of CIA and reduce CRP concentration, radiographic and histopathological scores. Multiple therapies show a better efficacy than single injection.