Skeletal muscle proteolysis is associated with sympathetic activation and TNF-α-ubiquitin-proteasome pathway in liver cirrhotic rats

The Glymphatic System May Play a Vital Role in the Pathogenesis of Hepatic Encephalopathy: A Narrative Review

Hepatic encephalopathy (HE) is a neurological complication of liver disease resulting in cognitive, psychiatric, and motor symptoms. Although hyperammonemia is a key factor in the pathogenesis of HE, several other factors have recently been discovered. Among these, the impairment of a highly organized perivascular network known as the glymphatic pathway seems to be involved in the progression of some neurological complications due to the accumulation of misfolded proteins and waste substances in the brain interstitial fluids (ISF). The glymphatic system plays an important role in the clearance of brain metabolic derivatives and prevents aggregation of neurotoxic agents in the brain ISF. Impairment of it will result in aggravated accumulation of neurotoxic agents in the brain ISF. This could also be the case in patients with liver failure complicated by HE. Indeed, accumulation of some metabolic by-products and agents such as ammonia, glutamine, glutamate, and aromatic amino acids has been reported in the human brain ISF using microdialysis technique is attributed to worsening of HE and correlates with brain edema. Furthermore, it has been reported that the glymphatic system is impaired in the olfactory bulb, prefrontal cortex, and hippocampus in an experimental model of HE. In this review, we discuss different factors that may affect the function of the glymphatic pathways and how these changes may be involved in HE.

Molecular mechanism of anti-inflammatory effects of the proteasome inhibitor MG-132 on Con A-induced acute liver injury in mice

MG-132, an aldehyde-based peptide proteasome inhibitor (PI) that binds to the proteasome and reversibly inhibits proteasome activity, has been widely used in experimental research. However, it is not clear whether MG-132 has anti-inflammatory effects on liver injury. The molecular mechanism of the anti-inflammatory effect of the PI MG-132 on Con A-induced acute liver injury (ALI) mice was investigated by ELISA, HE, q RT-PCR, and IHC. The results showed that the serum activities of alanine aminotransferase (ALT) and aspartate aminotransferase (AST) and TNF-α and IL-6 contents of mice in the high and medium dose groups were reduced compared with those in the ALI group. The superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) levels in liver tissues were significantly increased, and the malondialdehyde (MDA) content was decreased. The pathological sections of mice in the ALI group showed typical ALI manifestations such as significant central venous stasis of liver tissues, cell swelling, and inflammatory cell infiltration. The pathological damage of liver tissues was relieved significantly in the three dose groups, especially in the high-dose group. The transcriptional level of TLR4/NF-κB pathway key factors mRNA was significantly reduced, and the expression of TLR4 and NF-κB P65 protein in liver tissues was significantly and positively correlated with the contents of TNF-α and IL-1β (p < 0.01). Our findings suggest that MG-132 can alleviate the inflammatory response to Con A-induced ALI and exert a hepatoprotective effect, and its anti-inflammatory effect is related to the inhibition of TLR4/NF-κB signaling pathway activation.

The TNF-α rs361525 and IFN-γ rs2430561 polymorphisms are associated with liver cirrhosis risk: a comprehensive meta-analysis

Background

Inflammation serves as an essential driver of liver cirrhosis (LC) incidence. Accordingly, a meta-analysis was carried out to explore the association between specific polymorphisms in the interferon-γ (IFN-γ) and tumor necrosis factor-α (TNF-α) genes and the incidence of LC based on comparisons of genotype and allele frequencies.

Objectives

To study the relationship between TNF-α rs361525 and IFN-γ rs2430561 polymorphisms and the risk of LC.

Methods

A database search was performed for all studies published as of September 10, 2022. The strength of risk relationships was assessed based on odds ratios (ORs) with 95% confidence intervals (CIs).

Results

Pooled analyses were conducted for one common TNF-α polymorphism (rs361525) as well as one common IFN-γ polymorphism (rs2430561). Both of these SNPs were identified as LC-related risk factors. Specifically, rs361525 was related to LC incidence in both alcoholic liver cirrhosis (OR: 1.86, 95%CI: 1.03-3.34) and hepatitis B virus (HBV)-related cirrhosis cases (OR: 1.44, 95%CI: 1.00-2.06) when using an allelic contrast model. Moreover, rs2430561 was significantly related to LC in an Asian population (OR: 1.45, 95%CI: 1.13-1.86) and in the context of HBV-related cirrhosis (OR: 1.48, 95%CI: 1.13-1.93) when using an allelic contrast model.

Conclusion

These findings indicate that rs361525 and rs2430561 represent LC-related risk factors, although additional large-scale clinical and case-control studies will be vital to confirm these results.

Deletion of intestinal SIRT1 exacerbated muscle wasting in cirrhotic mice by decreasing the intestinal concentration of short-chain fatty acids and inflammation

Systemic sirtuin 1 (SIRT1) activation alleviates muscle wasting and improves muscle function by downregulation of myotropic and proteolytic markers. In this study, we evaluated the effects of the intestinal Sirt1 deletion on the dysregulated gutmuscle axis in cirrhotic mice. Cirrhosis-related muscle wasting was induced by common bile duct ligated (BDL) in either wild-type (WT) or intestine-specific Sirt1-deleted (Sirt1IEC-KO) mice, including WT-BDL, WT-sham, Sirt1IEC-KO-BDL and Sirt1IEC-KO-sham mice. Compared with WT-BDL mice, Sirt1IEC-KO-BDL mice showed worsened low lean mass, exacerbated muscle wasting, increased expression of myotropic markers, increased muscular protein degradation, and decreased expression of myogenic markers through aggravation of intestinal inflammation (as evidenced by increased fecal calprotectin/lipocalin-2 levels, increased intestinal macrophage infiltration, and increased intestinal TNFα/IL-6 levels), decrease in abundance of short-chain fatty acid (SCFA)-producing bacteria, decrease in levels of intestinal SCFAs (with anti-inflammatory effects), and downregulation of SCFA receptor GPR43. In biliary cirrhotic mice, a decrease in the abundance of SCFA-producing bacteria and an increase in the levels of intestinal/muscular inflammatory markers are involved in the pathogenesis of dysregulated gut-muscle axis-related muscle wasting, and intestinal deletion of Sirt1 exacerbated these changes.

Elucidating the interaction between maternal physical activity and circulating myokines throughout gestation: A scoping review

Physical activity (PA) during pregnancy provides both maternal and fetal health benefits. It has been theorized that myokines, peptides secreted by contracting skeletal muscle, may play an important mechanistic role in facilitating the health benefits obtained from prenatal exercise. The objective of this review was to synthesize the current literature on the relationship between maternal PA and myokine response. A search strategy was developed using the terms pregnancy, PA, IL-6, IL-10, IL-13, and TNF-α. A systematic search was completed in July 2020, in Medline, SPORTDiscus, EMBASE, CENTRAL, and in November 2020 for unpublished dissertations (grey literature; Proquest). Both human- and animal-based studies of any design were included, while commentaries and editorial articles were excluded. Data were extracted by two independent reviewers and summarized narratively. Data were thematically summarized based on the myokine and whether findings were from human or animal studies. Ten studies were included in this review. Findings from studies that examined IL-6, IL-10, and TNF-α suggest a trimester-specific interaction between PA and myokine levels; no studies evaluated IL-13. Future research should investigate the PA-myokine relationship throughout all stages of gestation.

Non-Selective Beta-Blockers Decrease Infection, Acute Kidney Injury Episodes, and Ameliorate Sarcopenic Changes in Patients with Cirrhosis: A Propensity-Score Matching Tertiary-Center Cohort Study

Background: Cirrhotic complications resulting from portal hypertension can be considerably reduced by non-selective beta-blockers (NSBBs); however, scarce studies have investigated therapeutic agents for other complications. We aimed to investigate the effects of NSBBs on common cirrhotic complications of infection, acute kidney injury (AKI), chronic renal function declination, and sarcopenic changes. Methods: Medical records of hospitalization for cirrhosis with at least a 4-year follow-up were analyzed and selected using propensity-score matching (PSM). Generalized estimating equation (GEE) was applied to assess the association of NSBBs with infection requiring hospitalization and AKI. Chronic renal function declination was evaluated by slope of regression lines derived from reciprocal of the serum creatinine level. The covariates of CT-measured skeletal muscle index (SMI) alterations were analyzed by generalized linear mixed model. Results: Among the 4946 reviewed individuals, 166 (83 NSBB group, 83 non-NSBB group) were eligible. Using GEE, Charlson comorbidity index, Child-Pugh score and non-NSBB were risk factors for infection; non-NSBB group revealed a robust trend toward AKI, showed no significant difference with chronic renal function declination of NSBB group, and was negatively associated with SMI alteration. Conclusion: Chronic NSBB use lowered the episodes of infection requiring hospitalization and AKIs, whereas non-NSBB was associated with sarcopenic changes.

Recovery of Diabetic Rats After Physical Exhaustion: Kinetic Alterations in Muscle Inflammation and Muscle-Signaling Proteins to Atrophy and Hypertrophy

The complexity of the adaptive response of diabetics to intense exercise is still poorly understood. To optimize exercise interventions in diabetics, the chronology of inflammatory mediators in muscle and the signaling involved in muscle hypertrophy/atrophy must be understood. Herein, we studied the kinetic inflammatory profile and cellular signaling pathways modulated by physical exhaustion after the induction of type 1 diabetes by streptozotocin in rats. Soleus muscle samples were obtained from diabetic and control groups at the following moments: baseline (no exercise); immediately after exhaustive exercise; and at 2 h, 24 h, 48 h, and 72 h after a treadmill exhaustive exercise. Kinetic production of cytokines and kinetic activation of proteins related to muscle synthesis (p70S6K and Akt) and degradation (GSK3, MuRF1, and MAFbx) were measured in the soleus muscle. We observed that the muscle TNF-α (0.9-fold; p = 0.0007), IL-1β (0.8-fold; p = 0.01), IL-6 (0.8-fold; p = 0.0013), L-selectin (1.0-fold; p = 0.0019), and CINC-2α/β (0.9-fold; p = 0.04) levels were higher in almost all stages of the study in the diabetic animals compared with the control group. Our data showed that exhaustive exercise decreased MAFbx expression in diabetic animals compared to the control group in a time-dependent manner. The decreased activation ratios of MAFbx were followed by a decrease in TNF-α, IL-1β, and IL-6 levels. p70S6k phosphorylation was also decreased in the diabetic group compared to the control group after physical exhaustion. Regarding the activation of proteins related to muscle synthesis and degradation, we found that the alterations induced by exhaustive exercise in the diabetic rats might involve pathways related to synthesis and muscle breakdown. Moreover, after an exhaustive exercise session, the recovery of the inflammatory response in the diabetic animals was slower than that in the control rats while the return of inflammatory cytokines to baseline levels was more effective in the diabetic animals.

Liver Cirrhosis and Sarcopenia from the Viewpoint of Dysbiosis

Sarcopenia in patients with liver cirrhosis (LC) has been attracting much attention these days because of the close linkage to adverse outcomes. LC can be related to secondary sarcopenia due to protein metabolic disorders and energy metabolic disorders. LC is associated with profound alterations in gut microbiota and injuries at the different levels of defensive mechanisms of the intestinal barrier. Dysbiosis refers to a state in which the diversity of gut microbiota is decreased by decreasing the bacterial species and the number of bacteria that compose the gut microbiota. The severe disturbance of intestinal barrier in LC can result in dysbiosis, several bacterial infections, LC-related complications, and sarcopenia. Here in this review, we will summarize the current knowledge of the relationship between sarcopenia and dysbiosis in patients with LC.

Relationship between presarcopenia and event occurrence in patients with primary hepatocellular carcinoma

Presarcopenia is a prognostic factor in patients with hepatocellular carcinoma (HCC). The Japan integrated staging (JIS) score is a prognostic method that combines the Child–Turcotte–Pugh classification and the tumor-node-metastasis (TNM) staging for HCC. We investigated the relationship between presarcopenia, the JIS score, and prognosis in patients with primary HCC. This retrospective study included 153 patients with primary HCC who were hospitalized from October 2011 to March 2018 at Municipal Hospital of Kofu. The skeletal muscle mass was measured using simplified psoas muscle mass index (PMI) based on CT imaging, and PMI using the volume analyzer SYNAPSE VINCENT ver3.0. We diagnosed presarcopenia based on the cut off value according to the assessment criteria for sarcopenia in liver disease defined by the Japan Society of Hepatology. Forty-three patients (28%) were diagnosed with presarcopenia. The median event-free survival was significantly worse in patients with presarcopenia than those without presarcopenia (P = 0.016). In multivariate analysis, presence of presarcopenia, JIS score ≥3, alpha-fetoprotein ≥200 ng/ml, and prothrombin induced by vitamin K absence-II ≥ 200 mAU/ml were significant prognostic factors. Among the patients with JIS scores ≥3, there was no difference in the event occurrence rate with presence of presarcopenia (P = 0.96). Among the patients with JIS scores ≤2, the median event-free-survival was significantly shorter in those with presarcopenia than those without presarcopenia (P = 0.045). Presarcopenia was an independent prognostic factor in patients with primary HCC. In patients with JIS scores ≤2, the median event-free survival was significantly shorter in those with presarcopenia compared to those without presarcopenia. In the patients with JIS scores ≥3, there was no difference in the event occurrence rates in those with and without presarcopenia.

Ischemic preconditioning improved renal ischemia/reperfusion injury and hyperglycemia

Renal ischemia/reperfusion (I/R) is an alternation of renal hemodynamics, which results in diverse postischemic responses and eventually acute kidney injury. Although renal ischemic preconditioning (IPC) is known to protect the kidney from I/R injury, the precise renoprotective mechanisms are not completely understood. The multiple renoprotective effects of IPC underscore the importance in understanding molecular mechanisms and the targets of action involved. This study aimed to identify the biochemical changes in renal I/R injury and investigate the renoprotective mechanisms of IPC. Herein, renal I/R was produced in adult male Sprague-Dawley rats through the bilateral ligation of renal pedicles for 45 min, followed by reperfusion for 24 h. For the IPC group, rats were subjected to three cycles of 2-min ischemia, followed by a 5-min reperfusion, 15 min prior to renal I/R. Our data confirmed the beneficial effects that IPC has on renal I/R injury. IPC-mediated renoprotection was associated with the resolution of oxidative stress, inflammation, apoptosis, and hyperglycemia. Among the numerous signaling molecules involved in the renoprotective mechanisms of IPC, an elevated protein expression of Nrf2, HO-1, LC3 II conversion, along with Atg12 and protein phosphorylation of AMPK, as well as a decreased protein phosphorylation of ERK, p38 MAPK, and Akt and NF-κB DNA binding activity were identified. Importantly, the post renal I/R overproduction of counter-regulatory hormones, impaired hepatic insulin action, and augmented hepatic gluconeogenesis were improved through IPC. As counter-regulatory hormones have been implicated in the induction of oxidative stress, inflammation, apoptosis, impaired insulin action, hyperglycemia, and tissue destruction, our findings suggest that counter-regulatory hormones may well be valuable targets of IPC for combatting renal I/R injury. © 2018 IUBMB Life, 71(3):321-329, 2019.

Experimental Periodontitis in the Potentialization of the Effects of Immobilism in the Skeletal Striated Muscle

This study aims to evaluate if ligature-induced periodontitis can potentiates the deleterious effects of immobilization in the skeletal striated muscle, contributing to the development of muscle atrophy due to disuse. Forty Wistar rats were divided into four groups: (1) Control Group (CG), (2) Periodontal Disease (PDG), (3) Immobilized (IG), and (4) Immobilized with Periodontal Disease (IPDG). Periodontal disease was induced for 30 days, with ligature method, and the immobilization was performed with cast bandage for 15 days. Prior to euthanasia, nociceptive threshold and muscular grasping force were evaluated. Afterwards, the soleus muscle was dissected and processed for sarcomere counting and morphological/morphometric analysis. For data analysis, was used the one-way ANOVA and post-test Tukey (p < 0.05). The IG and IPDG presented lower muscle weight, lower muscular grip strength, and less number of sarcomeres compared to CG. The PDG showed reduction of muscle strength and nociceptive threshold after 15 days of periodontal disease and increased connective tissue compared to CG. The IPDG presented lower muscle length and nociceptive threshold. The IG presented reduction in cross-sectional area and smaller diameter, increase in the number of nuclei and a nucleus/fiber ratio, decrease in the number of capillaries and capillary/fiber ratio, with increase in connective tissue. The IPDG had increased nucleus/fiber ratio, decreased capillaries, and increased connective tissue when compared to the IG. The IPDG presented greater muscle tissue degeneration and increased inflammatory cells compared to the other groups. Ligature-induced periodontitis potentiated the deleterious effects of immobilization of the skeletal striated muscle.

Lipopolysaccharide inhibits myogenic differentiation of C2C12 myoblasts through the Toll-like receptor 4-nuclear factor-κB signaling pathway and myoblast-derived tumor necrosis factor-α

Background

Circulating lipopolysaccharide (LPS) concentrations are often elevated in patients with sepsis or with various endogenous diseases that are associated with metabolic endotoxemia. Involuntary loss of skeletal muscle, termed muscle wasting, is commonly observed in these conditions, suggesting that circulating LPS might play an essential role in its development. Although impairment of muscle regeneration is an important determinant of skeletal muscle wasting, it is unclear whether LPS affects this process and, if so, by what mechanism. Here, we used the C2C12 myoblast cell line to investigate the effects of LPS on myogenesis.

Methods

C2C12 myoblasts were grown to 80% confluence and induced to differentiate in the absence or presence of LPS (0.1 or 1 μg/mL); TAK-242 (1 μM), a specific inhibitor of Toll-like receptor 4 (TLR4) signaling; and a tumor necrosis factor (TNF)-α neutralizing antibody (5 μg/mL). Expression of a skeletal muscle differentiation marker (myosin heavy chain II), two essential myogenic regulatory factors (myogenin and MyoD), and a muscle negative regulatory factor (myostatin) was analyzed by western blotting. Nuclear factor-κB (NF-κB) DNA-binding activity was measured using an enzyme-linked immunosorbent assay.

Results

LPS dose-dependently and significantly decreased the formation of multinucleated myotubes and the expression of myosin heavy chain II, myogenin, and MyoD, and increased NF-κB DNA-binding activity and myostatin expression. The inhibitory effect of LPS on myogenic differentiation was reversible, suggesting that it was not caused by nonspecific toxicity. Both TAK-242 and anti-TNF-α reduced the LPS-induced increase in NF-κB DNA-binding activity, downregulation of myogenic regulatory factors, and upregulation of myostatin, thereby partially rescuing the impairment of myogenesis.

Conclusions

Our data suggest that LPS inhibits myogenic differentiation via a TLR4–NF-κB-dependent pathway and an autocrine/paracrine TNF-α-induced pathway. These pathways may be involved in the development of muscle wasting caused by sepsis or metabolic endotoxemia.

Glechoma hederacea extracts attenuate cholestatic liver injury in a bile duct-ligated rat model

ETHNOPHARMACOLOGICAL RELEVANCE

In traditional Chinese medicine, Glechoma hederacea is frequently prescribed to patients with cholelithiasis, dropsy, abscess, diabetes, inflammation, and jaundice. Polyphenolic compounds are main bioactive components of Glechoma hederacea.

AIM OF THE STUDY

This study was aimed to investigate the hepatoprotective potential of hot water extract of Glechoma hederacea against cholestatic liver injury in rats.

MATERIALS AND METHODS

Cholestatic liver injury was produced by ligating common bile ducts in Sprague-Dawley rats. Saline and hot water extract of Glechoma hederacea were orally administrated using gastric gavages. Liver tissues and bloods were collected and subjected to evaluation using histological, molecular, and biochemical approaches.

RESULTS

Using a rat model of cholestasis caused by bile duct ligation (BDL), daily oral administration of Glechoma hederacea hot water extracts showed protective effects against cholestatic liver injury, as evidenced by the improvement of serum biochemicals, ductular reaction, oxidative stress, inflammation, and fibrosis. Glechoma hederacea extracts alleviated BDL-induced transforming growth factor beta-1 (TGF-β1), connective tissue growth factor, and collagen expression, and the anti-fibrotic effects were accompanied by reductions in α-smooth muscle actin-positive matrix-producing cells and Smad2/3 activity. Glechoma hederacea extracts attenuated BDL-induced inflammatory cell infiltration/accumulation, NF-κB and AP-1 activation, and inflammatory cytokine production. Further studies demonstrated an inhibitory effect of Glechoma hederacea extracts on the axis of high mobility group box-1 (HMGB1)/toll-like receptor-4 (TLR4) intracellular signaling pathways.

CONCLUSIONS

The hepatoprotective, anti-oxidative, anti-inflammatory, and anti-fibrotic effects of Glechoma hederacea extracts seem to be multifactorial. The beneficial effects of daily Glechoma hederacea extracts supplementation were associated with anti-oxidative, anti-inflammatory, and anti-fibrotic potential, as well as down-regulation of NF-κB, AP-1, and TGF-β/Smad signaling, probably via interference with the HMGB1/TLR4 axis.

Down-regulation of common NFκB-iNOS pathway by chronic Thalidomide treatment improves Hepatopulmonary Syndrome and Muscle Wasting in rats with Biliary Cirrhosis

Thalidomide can modulate the TNFα-NFκB and iNOS pathway, which involve in the pathogenesis of hepatopulmonary syndrome (HPS) and muscle wasting in cirrhosis. In bile duct ligated-cirrhotic rats, the increased circulating CD16⁺ (inflammatory) monocytes and its intracellular TNFα, NFκB, monocyte chemotactic protein (MCP-1) and iNOS levels were associated with increased circulating MCP-1/soluable intercellular cell adehesion molecule-1 (sICAM-1), pulmonary TNFα/NOx, up-regulated M1 polarization, exacerbated angiogenesis and hypoxemia (increased AaPO₂) in bronchoalveolar lavage (BAL) fluid and pulmonary homogenates. Meanwhile, a significant correlation was noted between circulating CD16⁺ monocyte/M1 (%) macrophages in BAL; M1 (%) macrophages in BAL/pulmonary iNOS mRNA expression; pulmonary iNOS mRNA expression/relative pulmonary MVD; pulmonary NOx level/AaPO₂; circulating CD16⁺ monocyte/M1 (%) macrophages in muscle homogenates; 3-nitrotyrosine (representative of peroxynitrite) concentration/M1 (%) macrophages in muscle homogenates. The in vitro data demonstrated an iNOS-dependent inhibition of thalidomide on the TNFα-stimulated angiogenesis and myogenesis in human pulmonary artery endothelial cells (HPAECs) and C2C12 myoblasts. Significantly, the co-culture of CD16⁺ monocyte from different rats with HPAECs, or co-culture of supernatant of above mixed cultures with HPAECs or C2C12 myoblasts stimulated angiogenesis, migration and myogenesis. Our findings demonstrate that TNFα inhibitor thalidomide markedly diminishes the severity of experimental HPS and muscle wasting by down-regulation of common peripheral and local NFκB-iNOS pathway.