Juvenile dermatomyositis: is periodontal disease associated with dyslipidemia?

BACKGROUND: Association between periodontal disease and dyslipidemia was recently reported in healthy adults. However, a systematic evaluation of concomitant periodontal diseases and lipid profile was not carried out in juvenile dermatomyositis (JDM). A cross-section study was performed in 25 JDM patients and 25 healthy controls, assessing demographic data, periodontal evaluation, fasting lipoproteins and anti-lipoprotein lipase antibodies. Disease parameters, laboratorial tests and treatment were also evaluated in JDM patients. RESULTS: The mean current age was similar in patients and controls (11.5 ± 3.75 vs. 11.2 ± 2.58 years,p = 0.703). Regarding lipid profile, the median triglycerides [80(31-340) vs. 61(19-182)mg/dL,p = 0.011] and VLDL[16(6-68) vs. 13(4-36)mg/dL,p = 0.020] were significantly higher in JDM patients versus controls. Gingival vasculopathy pattern was significantly higher in the former group (60% vs. 0%,p = 0.0001), as well as the median of gingival bleeding index (GBI) [24.1(4.2-69.4) vs. 11.1(0-66.6)%,p = 0.001] and probing pocket depth (PPD) [1.7(0.6-2.4) vs.1.4(0-2.12)mm,p = 0.006]. Comparison between JDM patients with and without dyslipidemia revealed that the median of dental plaque index (PI) [100(26.7-100) vs. 59(25-100)%,p = 0.022], PPD[1.9(0.6-2.4) vs. 1.4(1.2-1.8)mm,p = 0.024] and clinical attachment level (CAL) [1.31(0.7-1.7) vs. 0.8(0.6-1.7)mm,p = 0.005] were significantly higher in patients with dyslipidemia. Further analysis between JDM patients with and without gingivitis revealed that the median of current age [12.4 (8.3-18.4) vs. 9.2 (5.5-17.5) years, p = 0.034] and disease duration [7.09 ± 3.07 vs. 3.95 ± 2.1 years, p = 0.008] were significantly higher in the former group. CONCLUSION: Our study showed that gingival inflammation seems to be related to dyslipidemia in JDM patients, suggesting underlying mechanisms for both complications.

mGluR1/5 activation in the lateral hypothalamus increases food intake via the endocannabinoid system.

Mounting evidence has shown that glutamatergic and endocannabinoid systems in the hypothalamus regulate mammalian food intake. Stimulation of hypothalamic mGluR1/5 and CB1 receptors induces hyperphagia suggesting a possible interaction between these systems to control food intake. In addition, synthesis of endocannabinoids has been reported after mGluR1/5 stimulation in the brain. The aim of this study was to examine the potential cannabinergic activity in the food intake induction by lateral hypothalamic stimulation of mGluR1/5. Wistar albino male rats received bilateral infusions in the lateral hypothalamus (LH) of: (i) vehicle; (ii) (RS)-2-Chloro-5-hidroxyphenylglycine (CHPG; mGluR1/5 agonist); (iii) 2-AG (CB1 endogenous agonist); (iv) AM251 (CB1 antagonist); (v) tetrahydrolipstatin (THL, 1.2µg; diacyl-glycerol lipase inhibitor); and (vi) combinations of CHPG + with the other aforementioned drugs. Food intake was evaluated the first two hours after drug administration. CHPG significantly increased food intake; whereas CHPG in combination with a dose of 2-AG (with no effects on food intake) greatly increased food ingestion compared to CHPG alone. The increase induced by CHPG in food intake was prevented with AM251 or THL. These results suggest that activation of mGluR1/5 in the lateral hypothalamus induces an orexigenic effect via activation of the endocannabinoid system.

Age-associated changes of insulin action on the hydrolysis of diacylglycerol generated from phosphatidic acid.

Age-related changes in insulin action on diacylglycerol (DAG) degradation was studied in rat cerebral cortex synaptosomes. The generation of monoacylglycerol (MAG) and water soluble products (WSP, glycerol plus glycerol-3-phosphate) from DAG was studied in cerebral cortex (CC) synaptosomes from adult (4-month-old) and aged (28-month-old) rats. Additionally, the effect of porcine insulin and tyrosine phosphorylation was evaluated in the same group of animals. In this study we demonstrate that the age-related increase in WSP generation was accompanied by unmodified MAG levels. In the presence of diacylglycerol lipase (DAG lipase) inhibitor, RHC-80267, a lower inhibitory effect on MAG production was observed in CC synaptosomes from aged rats with respect to that in adult membranes. Under these experimental conditions, WSP formation was only diminished in aged membranes. Insulin stimulated MAG and WSP formation at long incubation times (30 min) in adult animals, while it had an inhibitory effect in aged animals. Insulin plus vanadate (as tyrosine-phosphatase inhibitor) inhibited MAG production at short incubation times whereas the same effect was observed in aged animals at long times of incubation. WSP formation was stimulated by insulin plus vanadate both in adult and aged animals at 30 min of incubation. Our results show that insulin differentially modulates MAG and WSP production from exogenous PA in CC synaptosomes from aged rats compared with adult rats.

Characterization of the lipid-binding properties and lipoprotein lipase inhibition of a novel apolipoprotein C-III variant Ala23Thr.

We have identified a G-to-A transition in exon 3 of the APOC3 gene resulting in a novel Ala23Thr apolipoprotein (apo) C-III variant, associated with apoC-III deficiency in three unrelated Yucatan Indians. The Ala23Thr substitution modifies the hydrophobic/hydrophilic repartition of the helical N-terminal peptide and hence could disturb the lipid association. In vitro expression in Escherichia coli of wild-type and mutant apoC-III enabled the characterization of the variant. Compared with wild-type apoC-III-Ala23, the mutant apoC-III-Thr23 showed reduced affinity for dimyristoylphosphatidylcholine (DMPC) multilamellar vesicles with higher amounts of free apoC-III. Displacement of apoE from discoidal apoE:dipalmitoylphosphatidycholine (DPPC) complex by apoC-III-Thr23 was comparable to wild type but the less efficient binding of the apoC-III-Thr23 to the discoidal complex resulted in a higher apoE/apoC-III (mol/mol) ratio (34%) than with wild-type/apoE:DPPC mixtures. The inhibition of lipoprotein lipase (LPL) by apoC-III-Thr23 was comparable to that of wild type, and therefore effects on LPL activity could not explain the lower triglyceride (Tg) levels in Thr-23 carriers. Thus, these in vitro results suggest that in vivo the less efficient lipid binding of apoC-III-Thr23 might lead to a faster catabolism of free apoC-III, reflected in the reduced plasma apoC-III levels identified in Thr-23 carriers, and poorer competition with apoE, which might enhance clearance of Tg-rich lipoproteins and lower plasma Tg levels seen in Thr-23 carriers.

Comparative effects of insulin and isoproterenol on lipoprotein lipase in rat adipose cells.

The effects of insulin and isoproterenol on lipoprotein lipase mass and enzyme activity were investigated in rat adipocytes. Cells were pulse labeled for 1 h with [35S]methionine to measure immunoprecipitable lipoprotein lipase. The results showed that 80% of the newly synthesized enzyme was membrane associated and 20% was secreted into the cell incubation medium. Enzyme activity was mainly associated with lipoprotein lipase secreted into the medium. A 10-min incubation with 10(-7) M insulin stimulated the secretion of lipoprotein lipase activity and the activity associated with adipocyte membranes. Conversely, 10(-6) M isoproterenol decreased the activity in all fractions. In addition, insulin increased lipoprotein lipase mass associated with cell membranes and decreased that in the incubation medium, whereas isoproterenol induced a decrease in both cell membranes and medium. Insulin and isoproterenol stimulated phosphorylation of lipoprotein lipase. These findings suggest that insulin stimulates the secretion of active lipoprotein lipase and a reuptake of inactive secreted enzyme, and isoproterenol decreases the activity by enzyme degradation. Moreover, because both agents stimulate phosphorylation of lipoprotein lipase, phosphorylation may play a role in the effect of insulin increasing enzyme activity, in secretion or reuptake, and in the effect of isoproterenol inducing degradation of lipoprotein lipase.

The role of cachectin/TNF in the pathogenesis of tuberculosis

The presence of cachectin or tumor necrosis factor (TNF) associated with hyperlipidemia was demonstrated in the serum of patients with pulmonary tuberculosis. The hyperlipidemia that accompanies this infection may be mediated by the TNF inhibition of lipoprotein lipase activity. This sequence of events may be sufficient to explain, in part, the complex metabolic changes and emaciation observed in tuberculosis patients

The role of cachectin/TNF in the pathogenesis of tuberculosis.

The presence of cachectin or tumor necrosis factor (TNF) associated with hypertriglyceridemia was demonstrated in the serum of patients with pulmonary tuberculosis. The hyperlipidemia that accompanies this infection may be mediated by the TNF inhibition of lipoprotein lipase activity. This sequence of events may be sufficient to explain, in part, the complex metabolic changes and emaciation observed in tuberculosis patients.