[Effect of mogroside VI on acute liver injury induced by sepsis in mice and related mechanisms].

OBJECTIVE: To study the effect of mogroside VI (MVI) on acute liver injury induced by sepsis in mice and its possible mechanisms. Methods A total of 60 male C57BL/6 mice were randomly divided into five groups: sham-operation, model, low-dose MVI (25 mg/kg), high-dose MVI (100 mg/kg), peroxisome proliferator-activated receptor gamma coactivator-1 alpha (PGC-1α) inhibitor (100 mg/kg MVI+30 mg/kg PGC-1α inhibitor SR-18292), with 12 mice in each group. Cecal ligation and puncture were performed to establish a mouse model of sepsis. The drugs were given by intraperitoneal injection after the model was established, once a day for 3 consecutive days. ELISA was used to measure the serum levels of alanine aminotransferase (ALT) and aspartate aminotransferase (AST). Colorimetry was used to measure the levels of malondialdehyde (MDA), superoxide dismutase (SOD), and glutathione peroxidase (GSH-Px) in liver tissue. Hematoxylin-eosin staining was used to observe liver histopathological changes. Liver mitochondrial respiratory function was measured, and mitochondrial respiratory control rate was calculated. RT-PCR was used to measure the copy number of mitochondrial DNA (mtDNA) in liver tissue and the mRNA expression levels of PGC-1α, nuclear respiratory factor-1 (NRF-1), and mitochondrial transcription factor A (TFAM) in liver tissue. Western blot was used to measure the protein expression levels of PGC-1α, NRF-1, and TFAM in liver tissue. RESULTS: Compared with the sham-operation group, the model group had significant increases in the serum levels of ALT and AST and the content of MDA in liver tissue (P<0.05) and significant reductions in the activities of GSH-Px and SOD in liver tissue (P<0.05). The model group had also severe liver histopathological injury and significant reductions in the mitochondrial respiratory control rate, the copy number of mtDNA, and the mRNA and protein expression levels of PGC-1α, NRF-1, and TFAM in liver tissue (P<0.05). Compared with the model group, the high-dose group had significant reductions in the serum levels of ALT and AST and the content of MDA in liver tissue (P<0.05), significant increases in the activities of GSH-Px and SOD in liver tissue (P<0.05), significant improvement in liver histopathological injury, and significant increases in the mitochondrial respiratory control rate, the copy number of mtDNA, and the mRNA and protein expression levels of PGC-1α, NRF-1, and TFAM in liver tissue (P<0.05). There were no significant differences in the above indicators between the low-dose and model groups (P>0.05). The PGC-1α inhibitor SR-18292 significantly inhibited the intervention effect of high-dose MVI (P<0.05). CONCLUSIONS: MVI can effectively alleviate acute liver injury caused by sepsis in mice, possibly by enhancing mitochondrial biosynthesis mediated by PGC-1α.

[Predictive value of red blood cell distribution width for acute kidney injury in children with sepsis].

OBJECTIVE: To study the clinical value of red blood cell distribution width (RDW) in the early prediction of acute kidney injury (AKI) in children with sepsis. METHODS: A total of 126 children with sepsis were divided into an AKI group (n=66) and a non-AKI group (n=60) according to the presence or absence of AKI. These patients were also classified into high-RDW and low-RDW groups according to the mean RDW. The groups were compared in terms of age, male-to-female ratio, body mass index (BMI), Acute Physiology and Chronic Health Evaluation II (APACHE II) score, Sequential Organ Failure Assessment (SOFA) score, serum blood urea nitrogen (BUN), creatinine (Cr), uric acid (UA), serum C-reactive protein (CRP), and routine blood test results. Independent factors associated with RDW were analyzed by multiple linear regression. RESULTS: Age, male-to-female ratio, BMI, CRP, SOFA score, and APACHE II score did not differ significantly between the AKI and non-AKI groups (P>0.05), but the AKI group had significantly higher BUN, Cr, UA, and RDW levels than the non-AKI group (P<0.05). Age, male-to-female ratio, and BMI did not differ significantly between the high-RDW and low-RDW groups (P>0.05), but the high-RDW group had significantly higher BUN, Cr, UA, CRP, SOFA score, APACHE II score, Hb, and mean corpuscular volume (MCV) than the low-RDW group (P<0.05). The multiple linear regression analysis showed that age, sex, APACHE II score, Cr, Hb, and MCV were independent factors associated with RDW. CONCLUSIONS: RDW has a certain clinical value in the early prediction of AKI in children with sepsis.

Genetic ablation of dynactin p150Glued in postnatal neurons causes preferential degeneration of spinal motor neurons in aged mice.

BACKGROUND: Dynactin p150Glued, the largest subunit of the dynactin macromolecular complex, binds to both microtubules and tubulin dimers through the N-terminal cytoskeleton-associated protein and glycine-rich (CAP-Gly) and basic domains, and serves as an anti-catastrophe factor in stabilizing microtubules in neurons. P150Glued also initiates dynein-mediated axonal retrograde transport. Multiple missense mutations at the CAP-Gly domain of p150Glued are associated with motor neuron diseases and other neurodegenerative disorders, further supporting the importance of microtubule domains (MTBDs) in p150Glued functions. However, most functional studies were performed in vitro. Whether p150Glued is required for neuronal function and survival in vivo is unknown. METHODS: Using Cre-loxP genetic manipulation, we first generated a line of p150Glued knock-in mice by inserting two LoxP sites flanking the MTBD-coding exons 2 to 4 of p150Glued-encoding Dctn1 gene (Dctn1LoxP/), and then crossbred the resulting Dctn1LoxP/ mice with Thy1-Cre mice to generate the bigenic p150Glued (Dctn1LoxP/LoxP; Thy1-Cre) conditional knockout (cKO) mice for the downstream motor behavioral and neuropathological studies. RESULTS: P150Glued expression was completely abolished in Cre-expressing postnatal neurons, including corticospinal motor neurons (CSMNs) and spinal motor neurons (SMNs), while the MTBD-truncated forms remained. P150Glued ablation did not affect the formation of dynein/dynactin complex in neurons. The p150Glued cKO mice did not show any obvious developmental phenotypes, but exhibited impairments in motor coordination and rearing after 12 months of age. Around 20% loss of SMNs was found in the lumbar spinal cord of 18-month-old cKO mice, in company with increased gliosis, neuromuscular junction (NMJ) disintegration and muscle atrophy. By contrast, no obvious degeneration of CSMNs, striatal neurons, midbrain dopaminergic neurons, cerebellar granule cells or Purkinje cells was observed. Abnormal accumulation of acetylated α-tubulin, and autophagosome/lysosome proteins was found in the SMNs of aged cKO mice. Additionally, the total and cell surface levels of glutamate receptors were also substantially elevated in the p150Glued-depleted spinal neurons, in correlation with increased vulnerability to excitotoxicity. CONCLUSION: Overall, our findings demonstrate that p150Glued is particularly required to maintain the function and survival of SMNs during aging. P150Glued may exert its protective function through regulating the transportation of autophagosomes, lysosomes, and postsynaptic glutamate receptors in neurons.

[Diagnostic value of high mobility group box 1 for acute appendicitis in children].

OBJECTIVE: To evaluate the value of high mobility group box 1(HMGB1) in the diagnosis of pediatric acute appendicitis. METHODS: The children with acute abdomen who had a diagnosis of suspected acute appendicitis between January and July 2013 and 25 healthy children were enrolled in this study. Serum HMGB1 levels were measured using ELISA on admission. The patients were classified into 2 groups according to surgery confirmation or pathological results: appendicitis (n=28) and non-appendicitis (n=35). RESULTS: Serum HMGB1 levels and WBC in the appendicitis and non-appendicitis groups were significantly higher than in the healthy children group (P<0.01). The appendicitis group showed more increased serum HMGB1 levels compared with the non-appendicitis group (median: 32.9 ng/mL vs 22.0 ng/mL; P<0.01). For a diagnosis of acute appendicitis, the sensitivity and specificity of serum HMGB1 was 71.4% and 82.9% respectively at the best cutoff of 28.0 ng/mL, with the accuracy of 77.8% and the area under the curve of 0.765 (95%CI 0.638-0.893). CONCLUSIONS: HMGB1 may play a role in the diagnosis of pediatric acute appendicitis.

[Clinical risk factors for capillary leak syndrome in children with sepsis].

OBJECTIVE: To investigate the clinical features of capillary leak syndrome (CLS) in children with sepsis, and to analyze its risk factors. METHODS: Clinical data of 384 children with sepsis was studied retrospectively. They included 304 cases of general sepsis, 54 cases of severe sepsis and 26 cases of septic shock, and were divided into non-CLS (n=356) and CLS groups (n=28). Univariate analysis was performed for each of the following variables: sex, age, malnutrition, anemia, coagulation disorders, white blood cell count, C-reactive protein (CRP), procalcitonin (PCT), tumor necrosis factor (TNF), interleukin (IL)-1, IL-6, blood glucose, lactic acid, Pediatric Risk of Mortality (PRISM) III score, pediatric critical illness score (PICS), severe sepsis and number of failed organs≥3. The statistically significant variables (as independent variables) were subjected to multivariate logistic regression analysis. RESULTS: The incidence rate of CLS in children with septic shock, severe sepsis and general sepsis were 42.3%, 20.1% and 1.3%, respectively, with significant differences among them (P<0.01). There were significant differences in anemia, coagulation disorders, CRP, PCT>2 ng/mL, TNF, IL-1, IL-6, blood glucose, lactic acid, PRISM III score, PICS and number of failed organs≥3 between the non-CLS and CLS groups (P<0.05). Severe sepsis/shock and PRISM III score were the independent risk factors for CLS in children with sepsis. CONCLUSIONS: The severity of sepsis and PRISM III score are positively correlated with the incidence of CLS in children with sepsis. Early monitoring of such factors as infection markers and blood glucose in children with severe sepsis and high PRISM III score may contribute to early diagnosis and effective intervention, thus reducing the mortality from CLS in children with sepsis.

Conditional expression of Parkinson's disease-related mutant α-synuclein in the midbrain dopaminergic neurons causes progressive neurodegeneration and degradation of transcription factor nuclear receptor related 1.

α-Synuclein (α-syn) plays a prominent role in the degeneration of midbrain dopaminergic (mDA) neurons in Parkinson's disease (PD). However, only a few studies on α-syn have been performed in the mDA neurons in vivo, which may be attributed to a lack of α-syn transgenic mice that develop PD-like severe degeneration of mDA neurons. To gain mechanistic insights into the α-syn-induced mDA neurodegeneration, we generated a new line of tetracycline-regulated inducible transgenic mice that overexpressed the PD-related α-syn A53T missense mutation in the mDA neurons. Here we show that the mutant mice developed profound motor disabilities and robust mDA neurodegeneration, resembling some key motor and pathological phenotypes of PD. We also systematically examined the subcellular abnormalities that appeared in the mDA neurons of mutant mice and observed a profound decrease of dopamine release, the fragmentation of Golgi apparatus, and the impairments of autophagy/lysosome degradation pathways in these neurons. To further understand the specific molecular events leading to the α-syn-dependent degeneration of mDA neurons, we found that overexpression of α-syn promoted a proteasome-dependent degradation of nuclear receptor-related 1 protein (Nurr1), whereas inhibition of Nurr1 degradation ameliorated the α-syn-induced loss of mDA neurons. Given that Nurr1 plays an essential role in maintaining the normal function and survival of mDA neurons, our studies suggest that the α-syn-mediated suppression of Nurr1 protein expression may contribute to the preferential vulnerability of mDA neurons in the pathogenesis of PD.

Astrocytic expression of Parkinson's disease-related A53T alpha-synuclein causes neurodegeneration in mice.

BACKGROUND: Parkinson's disease (PD) is the most common movement disorder. While neuronal deposition of alpha-synuclein serves as a pathological hallmark of PD and Dementia with Lewy Bodies, alpha-synuclein-positive protein aggregates are also present in astrocytes. The pathological consequence of astrocytic accumulation of alpha-synuclein, however, is unclear. RESULTS: Here we show that PD-related A53T mutant alpha-synuclein, when selectively expressed in astrocytes, induced rapidly progressed paralysis in mice. Increasing accumulation of alpha-synuclein aggregates was found in presymptomatic and symptomatic mouse brains and correlated with the expansion of reactive astrogliosis. The normal function of astrocytes was compromised as evidenced by cerebral microhemorrhage and down-regulation of astrocytic glutamate transporters, which also led to increased inflammatory responses and microglial activation. Interestingly, the activation of microglia was mainly detected in the midbrain, brainstem and spinal cord, where a significant loss of dopaminergic and motor neurons was observed. Consistent with the activation of microglia, the expression level of cyclooxygenase 1 (COX-1) was significantly up-regulated in the brain of symptomatic mice and in cultured microglia treated with conditioned medium derived from astrocytes over-expressing A53T alpha-synuclein. Consequently, the suppression of COX-1 activities extended the survival of mutant mice, suggesting that excess inflammatory responses elicited by reactive astrocytes may contribute to the degeneration of neurons. CONCLUSIONS: Our findings demonstrate a critical involvement of astrocytic alpha-synuclein in initiating the non-cell autonomous killing of neurons, suggesting the viability of reactive astrocytes and microglia as potential therapeutic targets for PD and other neurodegenerative diseases.

Phosphorylation of ezrin/radixin/moesin proteins by LRRK2 promotes the rearrangement of actin cytoskeleton in neuronal morphogenesis.

Leucine-rich repeat kinase 2 (LRRK2) functions as a putative protein kinase of ezrin, radixin, and moesin (ERM) family proteins. A Parkinson's disease-related G2019S substitution in the kinase domain of LRRK2 further enhances the phosphorylation of ERM proteins. The phosphorylated ERM (pERM) proteins are restricted to the filopodia of growing neurites in which they tether filamentous actin (F-actin) to the cytoplasmic membrane and regulate the dynamics of filopodia protrusion. Here, we show that, in cultured neurons derived from LRRK2 G2019S transgenic mice, the number of pERM-positive and F-actin-enriched filopodia was significantly increased, and this correlates with the retardation of neurite outgrowth. Conversely, deletion of LRRK2, which lowered the pERM and F-actin contents in filopodia, promoted neurite outgrowth. Furthermore, inhibition of ERM phosphorylation or actin polymerization rescued the G2019S-dependent neuronal growth defects. These data support a model in which the G2019S mutation of LRRK2 causes a gain-of-function effect that perturbs the homeostasis of pERM and F-actin in sprouting neurites critical for neuronal morphogenesis.

Leucine-rich repeat kinase 2 regulates the progression of neuropathology induced by Parkinson's-disease-related mutant alpha-synuclein.

Mutations in alpha-synuclein and Leucine-rich repeat kinase 2 (LRRK2) are linked to autosomal dominant forms of Parkinson's disease (PD). However, little is known about any potential pathophysiological interplay between these two PD-related genes. Here we show in transgenic mice that although overexpression of LRRK2 alone did not cause neurodegeneration, the presence of excess LRRK2 greatly accelerated the progression of neuropathological abnormalities developed in PD-related A53T alpha-synuclein transgenic mice. Moreover, we found that LRRK2 promoted the abnormal aggregation and somatic accumulation of alpha-synuclein in A53T mice, which likely resulted from the impairment of microtubule dynamics, Golgi organization, and the ubiquitin-proteasome pathway. Conversely, genetic ablation of LRRK2 preserved the Golgi structure and suppressed the aggregation and somatic accumulation of alpha-synuclein, and thereby delayed the progression of neuropathology in A53T mice. These findings demonstrate that overexpression of LRRK2 enhances alpha-synuclein-mediated cytotoxicity and suggest inhibition of LRRK2 expression as a potential therapeutic option for ameliorating alpha-synuclein-induced neurodegeneration.