Characterization of palmitic acid toxicity induced insulin resistance in HepG2 cells

BACKGROUND

An etiology of palmitic acid (PA) induced insulin resistance (IR) is complex for which two mechanisms are proposed namely ROS induced JNK activation and lipid induced protein kinase-C (PKCε) activation. However, whether these mechanisms act alone or in consortium is not clear.

METHODS AND RESULTS

In this study, we have characterized PA induced IR in liver cells. These cells were treated with different concentrations of PA for either 8 or 16 h. Insulin responsiveness of cells treated with PA for 8 h was found to be same as that of control. However, cells treated with PA for 16 h, showed increased glucose output both in the presence and in absence of insulin only at higher concentrations, indicating development of IR. In these, both JNK and PKCε were activated in response to increased ROS and lipid accumulation, respectively. Activated JNK and PKCε phosphorylated IRS1 at Ser-307 resulting in inhibition of AKT which in turn inactivated GSK3β, leading to reduced glycogen synthase activity. Inhibition of AKT also reduced insulin suppression of hepatic gluconeogenesis by activating Forkhead box protein O1 (FOXO1) and increased expression of the gluconeogenic enzymes and their transcription factors.

CONCLUSION

Thus, our data clearly demonstrate that both these mechanisms work simultaneously and more importantly, identified a threshold of HepG2 cells, which when crossed led to the pathological state of IR in response to PA.

Th17 cell promotes apoptosis of IL-23R+ neurons in experimental autoimmune encephalomyelitis

Myelin antigen-reactive Th1 and Th17 cells are critical drivers of central nervous system (CNS) autoimmune inflammation. Transcription factors T-bet and RORγt play a crucial role in the differentiation and function of Th1 and Th17 cells, and impart them a pathogenic role in CNS autoimmune inflammation. Mice deficient in these two factors do not develop experimental autoimmune encephalomyelitis (EAE). While T-bet and RORγt are known to regulate the expression of several cell adhesion and migratory molecules in T cells, their role in supporting Th1 and Th17 trafficking to the CNS is not completely understood. More importantly, once Th1 and Th17 cells reach the CNS, how the function of these transcription factors modulates the local inflammatory response during EAE is unclear. In the present study, we showed that myelin oligodendrocyte glycoprotein 35-55 peptide (MOG35-55)-specific Th1 cells deficient in RORγt could cross the blood-brain barrier (BBB) but failed to induce demyelination, apoptosis of neurons, and EAE. Pathogenic Th17 cell-derived cytokines GM-CSF, TNF-α, IL-17A, and IL-21 significantly increased the surface expression of IL-23R on neuronal cells. Furthermore, we showed that, in EAE, neurons in the brain and spinal cord express IL-23R. IL-23-IL-23R signaling in neuronal cells caused phosphorylation of STAT3 (Ser727 and Tyr705) and induced cleaved caspase 3 and cleaved poly (ADP-ribose) polymerase-1 (PARP-1) molecules in an IL-23R-dependent manner and caused apoptosis. Thus, we provided a mechanism showing that T-bet is required to recruit pathogenic Th17 cells to the CNS and RORγt-mediated inflammatory response to drive the apoptosis of IL-23R+ neurons in the CNS and cause EAE. Understanding detailed molecular mechanisms will help to design better strategies to control neuroinflammation and autoimmunity. ONE SENTENCE SUMMARY: IL-23-IL-23R signaling promotes apoptosis of CNS neurons.

Molecular mechanism of anti-adipogenic effect of vitexin in differentiating hMSCs

In this study, we evaluated a detailed molecular mechanism of anti-adipogenic activity of vitexin, apigenin flavone glucoside, present in germinated fenugreek seeds, in differentiating human mesenchymal stem cells (hMSCs). The lipid content of differentiated adipocytes was estimated by ORO staining. Effect on mitotic clonal expansion was checked by cell cycle analysis. Expression of early and terminal adipocyte differentiation markers, anti- and pro-adipogenic transcription factors and signalling intermediates regulating them was evaluated at RNA and protein level. We found vitexin to be non-cytotoxic up to 20 μM at which intracellular lipid accumulation was significantly decreased. Cell cycle analysis suggested that vitexin does not affect mitotic clonal expansion. Expression of early and late differentiation markers, such as CEBPα, CEBPβ, PPARγ, FABP4, perilipin, adiponectin and Glut4 was significantly reduced in the presence of vitexin. Expression of KLF4 and KLF15, positive regulators of PPARγ, was decreased, whereas that of negative regulators, namely KLF2, GATA2, miR20a, miR27a, miR27b, miR128, miR130a, miR130b, miR182 and miR548 increased with vitexin treatment. This effect was mediated by the activation of the AMP-activated protein kinase (AMPK) pathway via the activation of LepR and additionally by inhibiting ROS. Thus, our results showed that vitexin regulates the expression of PPARγ and inhibits adipogenesis of hMSCs at an early stage of differentiation.

Activation of TRPV4 by mechanical, osmotic or pharmaceutical stimulation is anti-inflammatory blocking IL-1β mediated articular cartilage matrix destruction

OBJECTIVE

Cartilage health is maintained in response to a range of mechanical stimuli including compressive, shear and tensile strains and associated alterations in osmolality. The osmotic-sensitive ion channel Transient Receptor Potential Vanilloid 4 (TRPV4) is required for mechanotransduction. Mechanical stimuli inhibit interleukin-1β (IL-1β) mediated inflammatory signalling, however the mechanism is unclear. This study aims to clarify the role of TRPV4 in this response.

DESIGN

TRPV4 activity was modulated glycogen synthase kinase (GSK205 antagonist or GSK1016790 A (GSK101) agonist) in articular chondrocytes and cartilage explants in the presence or absence of IL-1β, mechanical (10% cyclic tensile strain (CTS), 0.33 Hz, 24hrs) or osmotic loading (200mOsm, 24hrs). Nitric oxide (NO), prostaglandin E₂ (PGE₂) and sulphated glycosaminoglycan (sGAG) release and cartilage biomechanics were analysed. Alterations in post-translational tubulin modifications and primary cilia length regulation were examined.

RESULTS

In isolated chondrocytes, mechanical loading inhibited IL-1β mediated NO and PGE₂ release. This response was inhibited by GSK205. Similarly, osmotic loading was anti-inflammatory in cells and explants, this response was abrogated by TRPV4 inhibition. In explants, GSK101 inhibited IL-1β mediated NO release and prevented cartilage degradation and loss of mechanical properties. Upon activation, TRPV4 cilia localisation was increased resulting in histone deacetylase 6 (HDAC6)-dependent modulation of soluble tubulin and altered cilia length regulation.

CONCLUSION

Mechanical, osmotic or pharmaceutical activation of TRPV4 regulates HDAC6-dependent modulation of ciliary tubulin and is anti-inflammatory. This study reveals for the first time, the potential of TRPV4 manipulation as a novel therapeutic mechanism to supress pro-inflammatory signalling and cartilage degradation.

miR-3666 inhibits development of hepatic steatosis by negatively regulating PPARγ

AIMS

PPARγ is a crucial transcription factor involved in development of hepatic steatosis, an early stage of NAFLD. PPARγ is tightly regulated through various positive and negative regulators including miRNAs. In this study, we report for the first time miR-3666 as a negative regulator of PPARγ and its involvement in development of hepatic steatosis.

METHODS

Binding of miR-3666 to regulate PPARγ was checked by luciferase assay and was confirmed by mutating PPARγ 3'UTR. Regulation of PPARγ was determined by overexpression of miR-3666 in HepG2 cells. Hepatic steatotic state in HepG2 cells was developed by exposure to excess palmitic acid and expression of PPARγ, miR-3666 and some PPARγ target and non-target genes was checked. Involvement of mir-3666 by regulating PPARγ in hepatic steatosis was also examined in liver of HFD fed mice.

RESULTS

On overexpression of miR-3666, PPARγ expression decreased significantly in a dose-dependent manner in HepG2 cells. Binding of miR-3666 to PPARγ was confirmed as the luciferase activity using pMIR-REPORT with PPARγ 3'UTR decreased in PA treated HepG2 cells overexpressing miR-3666 and remained unchanged when PPARγ 3'UTR was mutated. In PA treated HepG2 cells during development of hepatic steatosis PPARγ was significantly up-regulated concomitant with down-regulation of miR-3666. Overexpression of miR-3666 in these cells decreased the extent of hepatic steatosis. Significant up-regulation of PPARγ and down-regulation of miR-3666 was also observed in liver of HFD fed mice indicating that miR-3666 regulates PPARγ in vivo.

CONCLUSIONS

miR-3666 negatively regulates PPARγ by binding to its 3'UTR during development of hepatic steatosis.

Vitexin alleviates non-alcoholic fatty liver disease by activating AMPK in high fat diet fed mice

Non-alcoholic fatty liver disease (NAFLD) is a most common liver disorder characterized by accumulation of fat in the liver and currently there is no approved treatment for it. Obesity and diabetes being leading cause of NAFLD, compounds having anti-obesity activity and potential to reduce insulin resistance are considered suitable candidate for NAFLD treatment. In this study, we checked effect of vitexin, a naturally occurring flavonoid, on high fat diet (HFD) induced NAFLD in C57BL/6J mice. In presence of vitexin, significant reduction in body and liver weight, triglyceride and cholesterol content in serum and liver was observed. Serum Alanine aminotransferase (ALT) and Aspartate aminotransferase (AST) levels were reduced significantly by vitexin which were elevated in HFD group whereas serum lipase activity remained unchanged. Vitexin suppressed de novo lipogenesis by downregulating expression of Peroxisome proliferator-activated receptor γ (PPARγ), CCAAT/enhancer-binding protein-α (C/EBP-α), sterol regulatory element-binding protein-1c (SREBP-1c), Fatty acid synthase (FAS) and Acetyl-CoA Carboxylase (ACC). Additionally, it also enhanced fatty acid oxidation and lipolysis by upregulating Peroxisome proliferator-activated receptor α (PPAR-α), carnitine palmitoyltransferase-1a (CPT-1a) and Adipose triglyceride lipase (ATGL). Inhibition of lipogenesis and activation of lipolysis and fatty acid oxidation by vitexin was found to be mediated by activation of AMP-activated protein kinase (AMPK). Vitexin also improved insulin signalling by activating insulin receptor substrate-1 (IRS-1) and its downstream target AKT. AMPK activation of vitexin was possibly through binding of vitexin to leptin receptor (LepR) which was confirmed by molecular docking studies and by observed enhanced expression of LepR. Thus, we propose that vitexin alleviates NAFLD by activating AMPK possibly by binding to LepR.

Cell mechanics, structure, and function are regulated by the stiffness of the three-dimensional microenvironment

This study adopts a combined computational and experimental approach to determine the mechanical, structural, and metabolic properties of isolated chondrocytes cultured within three-dimensional hydrogels. A series of linear elastic and hyperelastic finite-element models demonstrated that chondrocytes cultured for 24 h in gels for which the relaxation modulus is <5 kPa exhibit a cellular Young's modulus of ∼5 kPa. This is notably greater than that reported for isolated chondrocytes in suspension. The increase in cell modulus occurs over a 24-h period and is associated with an increase in the organization of the cortical actin cytoskeleton, which is known to regulate cell mechanics. However, there was a reduction in chromatin condensation, suggesting that changes in the nucleus mechanics may not be involved. Comparison of cells in 1% and 3% agarose showed that cells in the stiffer gels rapidly develop a higher Young's modulus of ∼20 kPa, sixfold greater than that observed in the softer gels. This was associated with higher levels of actin organization and chromatin condensation, but only after 24 h in culture. Further studies revealed that cells in stiffer gels synthesize less extracellular matrix over a 28-day culture period. Hence, this study demonstrates that the properties of the three-dimensional microenvironment regulate the mechanical, structural, and metabolic properties of living cells.

Innovative use of intact seeds of Mucuna monosperma Wight for improved yield of L-DOPA

The drug L-DOPA has been widely used against Parkinson’s disease and is extracted from plants. Due to the increasing demand of this drug, new plant sources need to be discovered in addition to the existing sources. The paper embodies results on Mucuna monosperma, which can be a promising candidate for L-DOPA. The seed powder of this plant contains 5.48% of (dry weight) the drug and when the seeds were soaked in distilled water, content was increased to 6.58%. Different elicitors when added, enhanced the drug level in seed up to 11.8%. The possible rationale behind this increase was confirmed by increase in tyrosinase activity in the seeds. Presence of L-DOPA was confirmed using various analytical techniques as HPLC, HPTLC and NMR. The work demonstrates a potential candidate plant as a source for L-DOPA when a novel method was adopted as described here.

Externalizing behaviors and television viewing in children of low-income minority parents

The parents of 151 children, ages 4-16 years, attending the pediatric outpatient clinic of an urban hospital were surveyed to determine if aggressive behavior among children of low literacy and low-income parents is related to excessive television viewing or to sociological variables such as ethnicity/race, education, occupation, and parents' marital status. The survey consisted of 22 questions about the ethnicity, marital status, education, and occupation of the parent, the television viewing behavior of the child, and the externalizing behavior scale of the Child Behavior Checklist of Achenbach (CBC). The television viewing habits of children in this study were not significantly different from viewing habits reported in national surveys of the US population. T scores in the aggression scale of CBC were unrelated to the hours of television watched by children and the control of viewing by the parent but were significantly associated with the employment and marital status of the mother. Children of unemployed and single mothers had higher externalizing-behavior scores, suggesting that family ecological variables may have more influence on children's behavior than the duration of television viewing.

Prevalence of hepatitis viruses among multi-transfused homogenous thalassaemia patients

Thalassaemic children being multi-transfused are at increased risk of parenterally transmissible hepatitis viruses and majority of them prone to develop chronic liver disease. The study is designed to find out the prevalence of hepatitis B virus (HBV), hepatitis C virus (HCV) and hepatitis D virus (HDV) seromarkers and correlation of age, sex, number of transfusions and the viral aetiology in thalassaemics of central India. One hundred and four thalassaemic children were subjected to clinical, biochemical and serological analysis for the HBV, HCV and HDV viruses. The chi(2) test was applied to check the statistical significance of different variables. In the present study HBV markers were detected in 57 (56%) of the subjects while anti-HCV antibodies were observed in 21% of the patients. However, only four subjects were detected hepatitis B surface antigen (HBsAg) reactive but none of them were reactive for anti-HDV antibodies. Forty patients had raised alanine transaminase (ALT) levels and among them two were HBsAg reactive, 16 were anti-HBc antibody positive and 14 were anti-HCV reactive. The prevalence of hepatitis viruses and raised ALT levels are found to be significantly associated with the increasing age and number of blood units transfused to them. The present findings also document the excellent contribution of stringent screening of blood units and HBV vaccination programme for containing the HBV infection among thalassaemics.

Treatment of duodenocutaneous fistula with somatostatin analog in a child with dermatomyositis

A 6-year-old girl with juvenile dermatomyositis complicated by five duodenal perforations is described. The treatment consisted of suture closure of the perforations, reinforcement of the suture line with an omental graft, and adequate drainage of the closure site. The use of a somatostatin analog was successful in promptly arresting a leak from the duodenal perforations that had persisted for 3 months after the operation despite prolonged bowel rest and total parenteral nutrition. On follow-up observation 2 months later, the patient had no abdominal complaints and was tolerating oral intake without problems.

Lyme disease in childhood: clinical and epidemiologic features of ninety cases

In 1982 and 1983 practicing pediatricians in a Lyme disease-endemic county, reported 90 cases of Lyme disease among children 19 years of age and younger (median age, 9 years). Three-fourths of the children had initial symptom onset in the summer months, with peak incidence in July. Infection occurred twice as often in boys than in girls, and tick bites were recalled by less than half (49%) of the children or parents. Erythema chronicum migrans was present in two-thirds (67%) of the cases with median onset 7 days after a definite tick bite. Arthritis or arthralgia occurred in 59% and neurologic symptoms, especially seventh nerve palsy, occurred in 14%. Asymmetric involvement of a few large joints, especially the knee, was most commonly reported for those with joint involvement. antibiotics were prescribed for 79% of the children, three-fourths of whom were treated with oral penicillin. Initial diagnosis of Lyme disease is usually made on clinical grounds alone because serologic tests are often negative. Serologic tests for antibody to Borrelia burgdorferi were more often positive in cases with neurological or joint involvement, in addition to erythema chronicums migrans (80%), than in cases presenting with erythema chronicums migrans only.

Emergency ultrasound in the evaluation of acute-onset abdominal pain in children

The diagnostic efficacy of abdominal ultrasound obtained within 72 hours of admission in children with undiagnosed, acute-onset abdominal pain was studied. In our 54 patients, sonogram supported the clinical diagnosis in 22 patients (40.7%), established a previously unsuspected diagnosis in nine (16.6%), and was normal in 23/54 (42.6%). Twenty-one of the patients with a normal study recovered uneventfully. Two patients had a false negative study (sensitivity of 91%) and in three, the study was falsely positive (specificity 90.3%). Thus, our data suggest that emergency abdominal ultrasound may be of significant diagnostic value in the evaluation of children with acute-onset abdominal pain.

Multivariate analyses of the EEG in normal adolescents

We investigated the computerized electroencephalography (cEEG) in a group of 85 normal adolescents. The spatial frequency of the cEEG was analyzed using various multivariate statistical techniques. The factor analyses revealed three factors that accounted for most of the variability in the data and that could be interpreted as a low versus high frequency, a beta frequency, and a frontal versus posterior factor. The cluster analysis revealed various EEG patterns that distinguished among subgroups of normal individuals.

Use of intravenous methylprednisolone in acute idiopathic thrombocytopenic purpura

Twenty newly diagnosed children with acute idiopathic thrombocytopenic purpura (ITP) with a platelet count (PC) of less than 20,000 were treated with intravenous methyl prednisolone (IVMP) 5 mg/kg/day in four divided doses until the platelet count increased to 50,000/mm3. They were then placed on oral prednisone at conventional doses for a total of three weeks of steroid therapy. The platelet counts increased by an average of 55,000/mm3 within 48 h of treatment. Within 72 h (day 3) of treatment all patients achieved a PC of greater than 20,000/mm3. By day 5, all 20 patients achieved a PC of greater than 50,000. IVMP is highly effective in rapidly raising the PC in acute ITP above the critical level of 20,000, thereby reducing the duration of risk for intracranial hemorrhage (ICH).

Vesical gigantism or congenital megacystis

We report on a child who was born with a large unobstructed bladder with normal trigone and normal ureteral insertions. The differences between vesical gigantism and the congenital megacystis-megaureter syndrome are discussed. In our patient, reduction cystoplasty was efficacious in alleviating the child's symptoms and recurrent urinary tract infections. More cases would be of benefit in confirming the usefulness of this procedure.

Acquired postganglionic cholinergic dysautonomia: case report and review of the literature

An 8-year-old girl with acute abdominal pain had cholinergic autonomic dysfunction. There have been only four patients with acquired postganglionic cholinergic dysautonomia described in the literature. The characteristic clinical features are atony of the bowel and bladder, lack of tears, saliva, and sweat, internal ophthalmoplegia, and normal adrenergic functions. Special studies for autonomic nervous function help in confirming this diagnosis. The exact pathogenesis of the disorder is still not clear. This case demonstrates successful treatment with bethanechol chloride.