The influence of high-density lipoprotein (HDL) and HDL subfractions on insulin secretion and cholesterol efflux in pancreatic derived β-cells

BACKGROUND

High-density lipoprotein (HDL) is considered a complex plasma-circulating particle with subfractions that vary in function, size, and chemical composition. We sought to test the effects of HDL, and HDL subfractions on insulin secretion and cholesterol efflux in the β-cell line MIN-6.

METHODS

We used total HDL and HDL subfractions 2a, 2b, 3a, 3b, and 3c, isolated from human plasma, to test insulin secretion under different glucose concentrations as well as insulin content and cholesterol efflux in the insulinoma MIN-6 cell line.

RESULTS

Incubation of MIN-6 cells with low glucose and total HDL increased insulin release two-fold. Meanwhile, when high glucose and HDL were used, insulin release increased more than five times. HDL subfractions 2a, 2b, 3a, 3b, and 3c elicited higher insulin secretion and cholesterol efflux than their respective controls, at both low and high glucose concentrations. The insulin content of the MIN-6 cells incubated with low glucose and any of the five HDL subclasses had a modest reduction compared with their controls. However, there were no statistically significant differences between each HDL subfraction on their capacity of eliciting insulin secretion, insulin content, or cholesterol efflux.

CONCLUSIONS

HDL can trigger insulin secretion under low, normal, and high glucose conditions. We found that all HDL subfractions exhibit very similar capacity to increase insulin secretion and cholesterol efflux. This is the first report demonstrating that HDL subfractions act both as insulin secretagogues (under low glucose) and insulin secretion enhancers (under high glucose) in the MIN-6 cell line.

Cacalol Acetate, a Sesquiterpene from Psacalium decompositum, Exerts an Anti-inflammatory Effect through LPS/NF-KB Signaling in Raw 264.7 Macrophages

Inflammatory diseases remain critical health problems worldwide. The search for anti-inflammatory drugs is a primary activity in the pharmaceutical industry. Cacalol is a sesquiterpene with anti-inflammatory potential that is isolated from Psacalium decompositum, a medicinal plant with several scientific reports supporting its anti-inflammatory activity. Cacalol acetate (CA) is the most stable form. Nevertheless, the participation of CA in the main signaling pathway associated with inflammation is unknown. Our aim was to study the anti-inflammatory effect of CA and to determine its participation in NF-κB signaling. In TPA-induced edema in mice, CA produced 70.3% inhibition. To elucidate the influence of CA on the NF-κB pathway, RAW 264.7 macrophages were pretreated with CA and then stimulated with LPS, evaluating NF-ΚB activation, IKK phosphorylation, IΚB-α, p65, cytokine expression, and COX-2 release and activity. CA inhibited NF-κB activation and its upstream signaling, decreasing phosphorylation IKB-α and p65 levels. CA also reduced expression and secretion of TNF-α, IL-1β, and IL-6. Additionally, it decreased the activity and expression of COX-2 mRNA. These data support that CA regulates the NF-κB signaling pathway, which might explain, at least in part, its anti-inflammatory effect. CA is a bioactive molecule useful for the development of anti-inflammatory agents with innovative mechanisms of action.

R230C but not - 565C/T variant of the ABCA1 gene is associated with type 2 diabetes in Mexicans through an effect on lowering HDL-cholesterol levels

PURPOSE

Type 2 diabetes (T2D) and low serum concentration of high-density lipoprotein cholesterol (HDL-c) are common coexisting metabolic disorders. ABCA1 variants have been shown to be associated to these conditions. We sought to test the combined effect of two ABCA1 gene common variants, rs2422493 (- 565C > T) and rs9282541 (R230C) on HDL-c levels and T2D risk.

METHODS

Path analysis was conducted in 3,303 Mexican-mestizos to assess the specific contributions of rs2422493 and rs9282541 ABCA1 variants, insulin resistance, waist-to-height ratio (WHtR), and age on HDL-c levels and T2D risk. Participants were classified into four groups according to their ABCA1 variants carrier status: (i) the reference group carried wild type alleles for both ABCA1 variants (-/-), (ii)  +/-  were carriers of rs2422493 but non-carriers of rs9282541, (iii) -/+ for carriers of rs9282541 but not carriers of rs2422493 and (iv) carriers of minor alleles for both SNPs (+/+). Principal components from two previous genome-wide association studies were used to control for ethnicity.

RESULTS

We identified significant indirect effects on T2D risk mediated by HDL-c in groups -/+ and +/+ (β = 0.04; p = 0.03 and β = 0.06; p < 0.01, respectively) in comparison to the -/- reference group. Low concentrations of HDL-c were directly and significantly associated with increased T2D risk (β = -0.70; p < 0.01). WHtR, male gender, age, and insulin resistance were also associated with T2D risk (p < 0.05). There was no significant direct effect for any of the ABCA1 groups on T2D risk: p = 0.99, p = 0.58, and p = 0.91 for groups +/-, -/+, and +/+ respectively.

CONCLUSIONS

The ABCA1 rs9282541 (R230C) allele is associated with T2D in Mexicans through its effect on lowering HDL-c levels. This is the first report demonstrating that HDL-c levels act as an intermediate factor between an ABCA1 variant and T2D.

The Mexican consensus on the detection and treatment of early gastric cancer

Gastric cancer is one of the most frequent neoplasias in the digestive tract and is the result of premalignant lesion progression in the majority of cases. Opportune detection of those lesions is relevant, given that timely treatment offers the possibility of cure. There is no consensus in Mexico on the early detection of gastric cancer, and therefore, the Asociación Mexicana de Gastroenterología brought together a group of experts and produced the "Mexican consensus on the detection and treatment of early gastric cancer" to establish useful recommendations for the medical community. The Delphi methodology was employed, and 38 recommendations related to early gastric cancer were formulated. The consensus defines early gastric cancer as that which at diagnosis is limited to the mucosa and submucosa, irrespective of lymph node metástasis. In Mexico, as in other parts of the world, factors associated with early gastric cancer include Helicobacter pylori infection, a family history of the disease, smoking, and diet. Chromoendoscopy, magnification endoscopy, and equipment-based image-enhanced endoscopy are recommended for making the diagnosis, and accurate histopathologic diagnosis is invaluable for making therapeutic decisions. The endoscopic treatment of early gastric cancer, whether dissection or resection of the mucosa, should be preferred to surgical management, when similar oncologic cure results can be obtained. Endoscopic surveillance should be individualized.

Neutrophil extracellular traps are a source of extracellular HMGB1 in lupus nephritis: associations with clinical and histopathological features

OBJECTIVE

This study aimed to analyze the expression of the high mobility group box-1 (HMGB1) protein in neutrophil extracellular traps (NETs) of patients with lupus nephritis (LN) and its association with clinical and histopathological features of the disease.

METHODS

Twenty-three patients with biopsy-confirmed LN and 14 systemic lupus erythematosus (SLE) patients with active disease (SLE Disease Activity Index (SLEDAI) score ≥ 6) and no evidence of LN were included. Clinical and laboratory features were recorded. NETs and the expression of HMGB1 were assessed by confocal microscopy, and serum HMGB1 levels were measured by ELISA.

RESULTS

In comparison to patients without kidney disease, patients with LN had a higher expression of HMGB1 in spontaneous (57 vs. 30.4; p = 0.027) and lipopolysaccharide (LPS)-induced (55.8 vs. 24.9; p = 0.005) NETs. We found a positive correlation between serum HMGB1 and the expression of HMGB1 in LPS-induced NETs (r = 0.447, p = 0.017). The expression of HMGB1 in spontaneous NETs correlated with SLEDAI score (r = 0.514, p = 0.001), anti-dsDNA antibodies (r = 0.467, p = 0.004), the rate of glomerular filtration descent (r = 0.543, p = 0.001), and diverse histopathological components of active nephritis in the kidney biopsy, such as the activity index (r = 0.581, p = 0.004), fibrinoid necrosis (r = 0.603, p = 0.002), and cellular crescents (r = 0.486, p = 0.019).

CONCLUSIONS

In patients with SLE, NETs are a source of extracellular HMGB1. The expression of HMGB1 in NETs is higher among patients with LN, which correlates with clinical and histopathological features of active nephritis and suggest a possible role of this alarmin in the pathophysiology of kidney damage in SLE.

(-)-Epicatechin inhibits development of dilated cardiomyopathy in δ sarcoglycan null mouse

BACKGROUND AND AIMS

Several studies propose that (-)-epicatechin, a flavonol present in high concentration in the cocoa, has cardioprotective effects. This study aimed to evaluate the impact of (-)-epicatechin on the development of dilated cardiomyopathy in a δ sarcoglycan null mouse model.

METHODS AND RESULTS

δ Sarcoglycan null mice were treated for 15 days with (-)-epicatechin. Histological and morphometric analysis of the hearts treated mutant mice showed significant reduction of the vasoconstrictions in the coronary arteries as well as fewer areas with fibrosis and a reduction in the loss of the ventricular wall. On the contrary, it was observed a thickening of this region. By Western blot analysis, it was shown, and increment in the phosphorylation level of eNOS and PI3K/AKT/mTOR/p70S6K proteins in the heart of the (-)-epicatechin treated animals. On the other hand, we observed a significantly decreased level of the atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP) heart failure markers.

CONCLUSION

All the results indicate that (-)-epicatechin has the potential to prevent the development of dilated cardiomyopathy of genetic origin and encourages the use of this flavonol as a pharmacological therapy for dilated cardiomyopathy and heart failure diseases.

TNF as marker of oral candidiasis, HSV infection, and mucositis onset during chemotherapy in leukemia patients

OBJECTIVE

To assess changes in the salivary expression of IL-1α, IL-1β, IL-2, IL-6, IL-10, IL-17, and TNF in acute leukemia (AL) patients before and during chemotherapy, and its association with HSV infection, oral candidiasis (OC), and oral mucositis (OM) onset.

METHODS

Cohort study in AL patients >15 years starting induction chemotherapy at a Mexican oncological center (2013-2014). Onset of oral lesions (OLs) was assessed during follow-up, and saliva was obtained at baseline, at visit 2 (days 4-12), and at visit 3 (days 13-21) after chemotherapy, treated with a protease inhibitor and stored at -70°C. An enzyme-linked immunosorbent assay was performed. Cox proportional hazards regression models were constructed to estimate hazard ratios and its 95% CI (HR, 95% CI) for OL development.

RESULTS

Forty-one patients were followed up, and 17 (41.5%) developed OLs. OL patients had higher baseline salivary IL-1α than those without lesions (p = 0.040). During visit 2, OL patients had higher levels of IL-1α (p = 0.033), IL-1β (p = 0.016), IL-6 (p = 0.035), and TNF (p = 0.019) than those who did not develop OLs. Patients with HSV infection, OC, and OM showed higher salivary TNF levels during follow-up (HR: 3.52, 95% CI: 1.35-9.14, p = 0.010).

CONCLUSION

AL patients undergoing chemotherapy with high salivary TNF levels were more likely to develop HSV infection, OC, and OM.

Abstract P5-04-15: Inhibitory effects of calcitriol and the vitamin D analogue paricalcitol in combination with chemotherapy on the growth of HER2 overexpressing breast cancer cells

Introduction: Despite recent advances in therapy, additional options for improving the outcomes of patients with HER2-overexpressing breast cancer (BC) are needed. The role of vitamin D in relation to BC outcomes is controversial. Both calcitriol and synthetic vitamin D analogues have been shown to increase sensitivity to chemotherapy in BC cell lines. In this study, we aimed to determine the effect of combined treatment with either calcitriol or the vitamin D analogue paricalcitol plus doxorubicin or paclitaxel in HER2+ BC cells.

Methods: Cell characterization was performed using western blot for estrogen receptor (ER) α, progesterone receptor (PR) A-B, HER2 receptor and vitamin D receptor (VDR) A-B. Flow cytometry was used to determine the quantitative expression of HER2 in an established breast cancer cell line known to express VDR (SKBR3 [ERα-, PR A-B -, HER2+]). The effects of calcitriol and paricalcitol, alone or in combination with doxorubicin or paclitaxel, were evaluated using a Sulforhodamine B growth assay. We calculated IC20 inhibitory concentrations by non-linear regression analysis using sigmoidal fitting of dose-response curves. Results are presented as the mean cell proliferation percentage (%) ± standard deviation. Statistical analyses were carried out using one-way ANOVA and the Holm-Sidak method.

Results: Calcitriol, paricalcitol, doxorubicin and paclitaxel inhibited cell proliferation in a dose dependent manner. Calcitriol 100nM in combination with doxorubicin 0.01 μM inhibited the proliferation of SKBR3 cells to 30.9% ± 24.1, compared to 74.6% ± 6.6 with calcitriol alone (p = 0.003) and 86.6% ± 4.1 with doxorubicin alone (p &lt; 0.001). Similarly, the combination of calcitriol 100nM plus paclitaxel 0.001 μM inhibited the proliferation of SKBR3 cells to 11.6% ± 10.4, compared to 77.5% ± 6.1 with calcitriol alone (p &lt; 0.001) and 50.7% ± 8.4 with paclitaxel alone (p &lt; 0.001). Paricalcitol 25nM in combination with doxorubicin 0.01 μM inhibited the proliferation of SKBR3 cells to 49.1% ± 25.2, compared to 72.3 ± 13.2 with paricalcitol alone (p = 0.21) and with doxorubicin alone (p = 0.05). Paricalcitol 10nM in combination with paclitaxel 0.001μM inhibited the proliferation of SKBR3 cells to 26.1% ± 23.1, compared to 72.3% ± 13.2 with paricalcitol alone (p = 0.05) and 43.2% ± 12.1 with paclitaxel alone (p =0.285).

Conclusions: Simultaneous treatment of SKBR3 cells with calcitriol plus either doxorubicin or paclitaxel showed a cooperative growth-inhibiting effect when compared with each cytotoxic drug alone. The combination of paricalcitol with each of the cytotoxic agents also showed a trend towards a higher growth-inhibiting effect, but failed to reach statistical significance when compared with each drug alone. Although these results point towards the presence of a cooperative antiproliferative effect of Vitamin D compounds on HER2+ BC cells when combined with chemotherapy, the concentrations needed to reach such an effect were high, which could potentially limit their use in clinical practice.

Citation Format: Mateos-Soria AS, Garcia-Becerra RA, Diaz-Nieto L, Ventura-Gallegos JL, Jacobo-Herrera N, Soto-Perez-de-Celis E, Zentella-Dehesa A, Chávarri-Guera Y. Inhibitory effects of calcitriol and the vitamin D analogue paricalcitol in combination with chemotherapy on the growth of HER2 overexpressing breast cancer cells. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P5-04-15.

Nitric oxide is involved in the upregulation of IFN-γ and IL-10 mRNA expression by CD8⁺ T cells during the blood stages of P. chabaudi AS infection in CBA/Ca mice

Nitric oxide (NO) is involved in the clearance of several types of bacteria, viruses and parasites. Although the roles of NO and CD8⁺ T cells in the immune response to malaria have been extensively studied, their actual contributions during the blood stages of malaria infection remain unclear.

In this work, we corroborate that serum NO levels are not associated with the in vivo elimination of the blood stages of Plasmodium chabaudi AS. In addition, we show that CD8⁺ T cells exhibit increased apoptosis and up regulate the expression of TNF-α mRNA on day 4 post-infection and IFN-γ and IL-10 mRNA on day 11 post-infection. Interestingly, only the levels of IFN-γ and IL-10 expression are affected when iNOS is inhibited with aminoguanidine (AG), suggesting that NO could be involved in the activation of CD8⁺ T cells during the blood stages of plasmodium infection.

Immunomodulatory role of chloroquine and pyrimethamine in Plasmodium yoelii 17XL infected mice

Chloroquine (CLQ) and Pyrimethamine (PYR) are used for the treatment of malaria and some autoimmune diseases; although their mechanism of action is only partially understood, their therapeutic effectiveness in the second case has been attributed to their ability to increase apoptosis of T lymphocytes. In view of the potential for immunomodulation during malaria chemotherapy, we investigated the effects of CLQ and PYR treatment on lymphocyte apoptosis and cytokine expression during infection with blood-stage Plasmodium. This work shows that infection of BALB/c mice with Plasmodium yoelii 17XL (Py17XL) reduced apoptosis in spleen cells but when infected mice were treated with CLQ, apoptosis of B and T lymphocytes increased significantly via a Fas-mRNA expression independent mechanism associated with downregulation of Bcl-2 expression, whereas treatment with PYR increased apoptosis to a lesser extent and only in B lymphocytes. CLQ treatment of Py17XL infected mice upregulated tumour necrosis factor-alpha mRNA expression, while PYR treatment increased interferon-gamma mRNA expression. In infected mice, treatment with CLQ downregulated expression of the anti-inflammatory cytokines, interleukin-10 and transforming growth factor-beta (TGF-beta), while PYR treatment upregulated TGF-beta. Thus, in addition to their anti-malarial effects, both drugs modulate the immune response in malaria by increasing apoptosis and modulating the mRNA expression of cytokines involved in parasite elimination and regulation of inflammatory responses.

NF-κB signaling blockade by Bay 11-7085 during early cardiac morphogenesis induces alterations of the outflow tract in chicken heart

Nuclear factor kappaB (NF-kappaB) is a pleiotropic transcription factor implicated in the regulation of diverse morphologic cardiac alterations, for which the p50 and p65 subunits form the most prevalent dimeric form in the heart. NF-kappaB is inactivated by proteins of the IkappaB family, which trap it in the cytoplasm. It is not known whether NF-kappaB influences cardiac development.

OBJECTIVE

Here we investigated the role of NF-kappaB in regulating transcription in chicken heart morphogenesis. Specifically, we tested whether NF-kappaB activation is required for normal formation of the outflow tract (OFT) during a critical stage of heart development.

METHODS AND RESULTS

We designed a reporter vector with kappaB binding sites for Rel family members in the promoter, upstream from the cDNA of Green Fluorescent Protein (GFP). This construct was injected directly into the developing heart of chicken embryos. NF-kappaB activation was subsequently inhibited by administration of the specific pharmacological agent Bay 11-7085. We found that forced NF-kappaB expression was associated with multiple congenital cardiac alterations of the OFT (mainly IVC, DORV and great arteries stenosis).

CONCLUSION

These findings indicate that blockade of NF-kappaB induces apoptosis and is an important factor in the development of OFT during cardiogenesis. However, it remains unknown which members of the Rel family are relevant in this process.

NF-?B translocation and endothelial cell activation is potentiated by macrophage-released signals co-secreted with TNF-? and IL-1?

OBJECTIVE AND METHODS

Over-expression of the immune response can lead to pathological conditions such as septic shock or chronic inflammation. Endothelial cell activation by pro-inflammatory products of activated macrophages plays a key role in these conditions. Here we examine the response of primary human endothelial cells (HUVEC) to conditioned media (CM) obtained from LPS-activated macrophages. We further characterized the translocation of NF-kappaB in the presence of CM by studying the degradation rate of individual IkappaB isoforms.

RESULTS

We show that, as expected, CM induced NF-kappaB translocation, as well as adhesion capacity in HUVEC. We further show that this response is critically dependent on TNF-alpha and IL1beta naturally present in the CM. However, both the amplitude of NF-kappaB translocation and adhesiveness observed with CM were well beyond the saturation levels attained after the sole stimulation with recombinant TNF-alpha and IL-1beta, either separately or together. Our results show that CM induced a faster degradation of the IkappaB-beta and IkappaB-epsilon isoforms than the recombinant cytokines, leading to an enhanced recruitment of NF-kappaB activity.

CONCLUSIONS

The above results suggest that the physiological context of factors co-secreted by LPS-activated macrophages enhances TNF-alpha mediated endothelial activation.

The carboxy-terminal tail of the Ste2 receptor is involved in activation of the G protein in the Saccharomyces cerevisiae alpha-pheromone response pathway

The Ste2 gene encodes the yeast alpha-pheromone receptor that belongs to the superfamily of seven-transmembrane G protein-coupled receptors. Binding of pheromone induces activation of the heterotrimeric G protein triggering growth arrest in G1 phase and induction of genes required for mating. By random PCR-mediated mutagenesis we isolated mutant 8L4, which presents a substitution of an asparagine residue by serine at position 388 of the alpha-factor receptor. The 8L4 mutant strain shows phenotypic defects such as: reduction in growth arrest after pheromone treatment, diminished activation of the Fus1 gene, and impaired mating competence. The asparagine residue lies in the second half of the intracellular protruding C-terminal tail of the receptor, and its replacement by serine affects interaction with both the G(alpha) and Gbeta subunits. Since expression of the receptor as well as its kinetic parameters, i.e., ligand affinity and receptor number, are unaffected in the mutant strain, we propose that association of the C-terminal tail of the receptor with G(alpha) and Gbeta subunits is required for proper activation of the heterotrimeric G protein. Besides its described role in downregulation and in formation of preactivation complex, the results here shown indicate that the C-terminal tail of the receptor plays an active role in transmitting the stimulus of mating pheromone to the heterotrimeric G protein.

(Tetrakis(2-pyridylmethyl)ethylenediamine)iron(II) perchlorate. Study of density functional methods

On the basis of the data obtained by X-ray diffraction, the properties of two independent crystallographic subsystems in the [Fe(tpen)](ClO4)2.2/3H2O complex are studied in detail with the density functional method B3LYP. The energies of singlet, triplet, and quintet states at different temperatures are obtained, the influences of geometry on energy changes are analyzed, the regularity of the spin-state interconversions is investigated, and the effect of the triplet and action of the anion on spin crossover are discussed. This investigation demonstrates that (1) the energy difference between the high-spin state and singlet state decreases as the Fe-N distance and geometric distortion increase, (2) the spin-equilibrium system is predominantly in low-spin form below room temperature and the proportion of high-spin state rapidly increases above room temperature, (3) one of the two cation sites has a greater presence of the high-spin content, (4) the triplet state may be responsible for the fast rate of spin-state interconversions, and (5) the B3LYP method proves to be very adequate to study the spin-state transition of this complex.

Membrane bound CETP mediates the transfer of free cholesterol between lipoproteins and membranes

Cholesteryl ester transfer protein (CETP) has been shown to transfer cholesteryl esters among plasma lipoproteins. However, when reconstituted into phosphatidylcholine liposomes, the 74,000 protein mediates above non-specific values the transfer of HDL bound [3H]cholesterol into the artificial membrane system. Employing the known cDNA sequence of CETP, we synthesized a series of oligonucleotides with specific sequences for different regions of CETP and RNA isolated from tissues known to be producers of CETP (liver), and tissues not design to synthesize and secrete CETP (ovary, lung, intestine and heart). Hybridization experiments showed that independently of the type of tissue tested CETP sequences were found. It is suggested that a membrane form of CETP might have important repercussions locally.

Induction, identification, and cell-free translation of mRNAs coding for peroxisomal proteins in Candida tropicalis

Peroxisomes have been purified from Candida tropicalis grown on oleic acid and shown to be nearly pure by marker enzyme analysis, electron microscopy, and comparative sodium dodecyl sulfate-polyacrylamide gel electrophoresis. They contain approximately 20 polypeptides, among which acyl-CoA oxidase, trifunctional hydratase-dehydrogenase-epimerase, and catalase have been identified. Rabbit antisera have been elicited that react with these three proteins. When C. tropicalis is grown on alkanes, a dozen mRNAs are strikingly induced. Nine of the 12 induced mRNAs code for polypeptides that comigrate in sodium dodecyl sulfate-polyacrylamide gel electrophoresis with peroxisomal proteins, among which three have been identified immunochemically as the acyl-CoA oxidase, the trifunctional protein, and catalase. These results indicate that some genes coding for peroxisomal proteins are strongly expressed during growth of C. tropicalis on alkanes. The data are consistent with evidence in other species that peroxisomes form by the post-translational incorporation of newly made proteins into pre-existing peroxisomes, generally without proteolytic processing, followed by peroxisome division.