Novel Nongenetic Murine Model of Hyperglycemia and Hyperlipidemia-Associated Aggravated Atherosclerosis

Objective

Atherosclerosis, the main pathology underlying cardiovascular diseases is accelerated in diabetic patients. Genetic mouse models require breeding efforts which are time-consuming and costly. Our aim was to establish a new nongenetic model of inducible metabolic risk factors that mimics hyperlipidemia, hyperglycemia, or both and allows the detection of phenotypic differences dependent on the metabolic stressor(s).

Methods and Results

Wild-type mice were injected with gain-of-function PCSK9^D377Y (proprotein convertase subtilisin/kexin type 9) mutant adeno-associated viral particles (AAV) and streptozotocin and fed either a high-fat diet (HFD) for 12 or 20 weeks or a high-cholesterol/high-fat diet (Paigen diet, PD) for 8 weeks. To evaluate atherosclerosis, two different vascular sites (aortic sinus and the truncus of the brachiocephalic artery) were examined in the mice. Combined hyperlipidemic and hyperglycemic (HGHCi) mice fed a HFD or PD displayed characteristic features of aggravated atherosclerosis when compared to hyperlipidemia (HCi HFD or PD) mice alone. Atherosclerotic plaques of HGHCi HFD animals were larger, showed a less stable phenotype (measured by the increased necrotic core area, reduced fibrous cap thickness, and less α-SMA-positive area) and had more inflammation (increased plasma IL-1β level, aortic pro-inflammatory gene expression, and MOMA-2-positive cells in the BCA) after 20 weeks of HFD. Differences between the HGHCi and HCi HFD models were confirmed using RNA-seq analysis of aortic tissue, revealing that significantly more genes were dysregulated in mice with combined hyperlipidemia and hyperglycemia than in the hyperlipidemia-only group. The HGHCi-associated genes were related to pathways regulating inflammation (increased Cd68, iNos, and Tnfa expression) and extracellular matrix degradation (Adamts4 and Mmp14). When comparing HFD with PD, the PD aggravated atherosclerosis to a greater extent in mice and showed plaque formation after 8 weeks. Hyperlipidemic and hyperglycemic mice fed a PD (HGHCi PD) showed less collagen (Sirius red) and increased inflammation (CD68-positive cells) within aortic plaques than hyperlipidemic mice (HCi PD). HGHCi-PD mice represent a directly inducible hyperglycemic atherosclerosis model compared with HFD-fed mice, in which atherosclerosis is severe by 8 weeks.

Conclusion

We established a nongenetically inducible mouse model allowing comparative analyses of atherosclerosis in HCi and HGHCi conditions and its modification by diet, allowing analyses of multiple metabolic hits in mice.

Secreted Ligands of the NK Cell Receptor NKp30: B7-H6 Is in Contrast to BAG6 Only Marginally Released via Extracellular Vesicles

NKp30 (Natural Cytotoxicity Receptor 1, NCR1) is a powerful cytotoxicity receptor expressed on natural killer (NK) cells which is involved in tumor cell killing and the regulation of antitumor immune responses. Ligands for NKp30, including BAG6 and B7-H6, are upregulated in virus-infected and tumor cells but rarely detectable on healthy cells. These ligands are released by tumor cells as part of the cellular secretome and interfere with NK cell activity. BAG6 is secreted via the exosomal pathway, and BAG6-positive extracellular vesicles (EV-BAG6) trigger NK cell cytotoxicity and cytokine release, whereas the soluble protein diminishes NK cell activity. However, the extracellular format and activity of B7-H6 remain elusive. Here, we used HEK293 as a model cell line to produce recombinant ligands and to study their impact on NK cell activity. Using this system, we demonstrate that soluble B7-H6 (sB7-H6), like soluble BAG6 (sBAG6), inhibits NK cell-mediated target cell killing. This was associated with a diminished cell surface expression of NKG2D and NCRs (NKp30, NKp40, and NKp46). Strikingly, a reduced NKp30 mRNA expression was observed exclusively in response to sBAG6. Of note, B7-H6 was marginally released in association with EVs, and EVs collected from B7-H6 expressing cells did not stimulate NK cell-mediated killing. The molecular analysis of EVs on a single EV level using nano flow cytometry (NanoFCM) revealed a similar distribution of vesicle-associated tetraspanins within EVs purified from wildtype, BAG6, or B7-H6 overexpressing cells. NKp30 is a promising therapeutic target to overcome NK cell immune evasion in cancer patients, and it is important to unravel how extracellular NKp30 ligands inhibit NK cell functions.

ELM 2016--data update and new functionality of the eukaryotic linear motif resource

The Eukaryotic Linear Motif (ELM) resource (http://elm.eu.org) is a manually curated database of short linear motifs (SLiMs). In this update, we present the latest additions to this resource, along with more improvements to the web interface. ELM 2016 contains more than 240 different motif classes with over 2700 experimentally validated instances, manually curated from more than 2400 scientific publications. In addition, more data have been made available as individually searchable pages and are downloadable in various formats.

Abstract 254: TiMi1 is a novel immune-checkpoint in solid tumors identified via a tumor-infiltrating lymphocyte (TIL)-based RNAi screening

Immunotherapeutic treatment of melanoma achieved major progress in recent years leading for the first time to improved survival. However, since melanoma cells employ various suppressive mechanisms in order to evade recognition and destruction by immune effector cells many patients still do not benefit from immunotherapy. These mechanisms are far more diverse than reflected by currently used immune modulatory drugs. In this study, we established and utilized a novel high throughput RNAi screening to identify new immune checkpoint molecules in melanoma using antigen-specific patient-derived tumor infiltrating lymphocytes (TILs) in conjunction with primary HLA-matched melanoma cells. Using this approach, we screened a siRNA library targeting more than 1200 surface receptors and kinases to explore novel targets for immunotherapy.

Briefly, HLA-A2 and luciferase positive M579-A2-luc melanoma cells were reversely transfected with the siRNA library and then co-cultured with MART1- and gp100-specific TILs to validate the TIL-mediated tumor lysis. Local regression models (LOESS) were applied to generate a hit list of 48 candidates that negatively regulated CTL cytotoxicity. Interestingly, four candidates of a related breast cancer screen were among the top hits. To streamline the discovery process for large scale molecule libraries, we established a secondary screen assaying multiple T cell activation markers, including effector cytokines.

One of the strongest candidates from our primary and secondary screening is TiMi1 (name altered), a cell surface receptor belonging to the class of GPCRs. We found that knock-down of TiMi1 increased TIL-mediated killing of M579-A2-luc without affecting their viability. TiMi1 knock-down increased TIL activity measured by production of type 1-associated cytokines (e.g. IFN γ and TNF-α), reduced TC apoptosis and increased markers associated with raised activity and cytotoxicity (4-1BB and CD107a). We were able to verify the immune checkpoint function of TiMi1 in melanoma patients using an autologous set of melanoma cells and TILs. Phosphoplex analysis in T cells revealed an involvement of the transcription factor CREB in the mode of action of TiMi1. Preliminary experiments suggest that TiMi1 inhibits anti-tumor immune responses in pancreatic (PDAC) and colorectal (CRC) cancers as well.

In summary, we established a novel antigen-specific screening approach for immune checkpoints expressed in melanoma and were able to identify TiMi1 as a promising candidate. Moreover, TiMi1 inhibits T cell responses in melanoma, PDAC and CRC and might be an interesting target for immunotherapy. Our novel high-throughput screening offers a systematic platform to uncover the “immune-modulatome” of cancer and subsequently discover novel targets for immunotherapy. Since the presented work is considered for patent protection, some gene targets are masked in the presented study.

Citation Format: Tillmann Michels, Christina A. Hartl, Nisit Khandelwal, Marco Breinig, Antonio Sorrentino, Christina Mäder, Ludmila Umansky, Isabel Poschke, Rienk Offringa, Michael Boutros, Galit Eisenberg, Michal Lotem, Philipp Beckhove. TiMi1 is a novel immune-checkpoint in solid tumors identified via a tumor-infiltrating lymphocyte (TIL)-based RNAi screening. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 254. doi:10.1158/1538-7445.AM2015-254

A retrospective study of combined fixed-removable reconstructions with their analysis of failures

The survival rate and the reasons for failures of 130 combined fixed-removable reconstructions (CFR), incorporated in 112 patients, were assessed. Each CFR reconstruction was classified depending on its attachments: 76 reconstructions were attached with rigid, precise attachments, and constituted the rigid group; 54 reconstructions were attached with either semi-precision or individual attachments and were defined as the semi-rigid group. Of the 130 reconstructions, 41 were determined as complete successes, 39 as partial successes and 50 as failures, leading to 37 major repairs and to 13 new reconstructions. Three reconstructions failed due to technical reasons, 36 due to biological reasons and for 11 reconstructions, both categories of reasons were responsible for their failure. In total, technical reasons were counted 15 times in comparison to 73 biological reasons for those 50 failed reconstruction, with 29 fractured abutment teeth as the most common biological reason. Within the rigid group, 45 failed reconstructions were observed, whereas within the semi rigid group only 5 failures occurred, leading to an 8-year survival estimate (+/- SD) of 30.1% (+/- 6.9%) for the rigid group and 93.1% (+/- 3.9%) for the semi rigid group. Beside the attachment type, the anatomy of the partially edentulous tooth arch in form of the free-end situation and the dentate opposing jaw were identified as risk factors.

Use of an in vitro absorption model system for predicting sustained release of verapamil

It is shown that it is possible to characterize sustained release formulations in vitro using not only dissolution data but also an absorption model system. The mean dissolution time (MDT) has been shown to be a suitable parameter for evaluating sustained release formulations in vitro. t1/2 and mean residence time (MRT) have been shown to be convenient pharmacokinetic parameters for characterizing sustained release formulations. For comparing in vitro and in vivo results the quotients MDT normal/MDT retard and MRT normal/MRT retard do seem to be useful.

Decrease in LDL and increase in HDL concentrations in type II hyperlipoproteinaemic patients on low-dose combination therapy of cholestyramine and Complamin

A low-dose combination of Complamin retard (1 g t.i.d.) and cholestyramine (4 g b.i.d.) was compared with each agent alone in 2 serial open trials without dietary restriction using type IIa and IIb hyperlipoproteinaemic patients. Complamin alone produced decreases in LDL and VLDL cholesterol concentrations (up to 20%) whereas cholestyramine alone produced only a modest reduction in LDL (up to 15%). The combination produced marked, progressive reductions in total cholesterol (up to 35%) and LDL (up to 40%); reductions in VLDL (up to 45%), total triglyceride (up to 60%) and free fatty acids (up to 60%) were found only in type IIb patients. The average increase in HDL-cholesterol from the 2 studies for combination therapy was 35%. No side-effects were reported or measured and compliance was excellent. The results demonstrate the potential of a method of achieving beneficial actions on lipoprotein levels with a well-tolerated therapy.

Human neutrophilic and eosinophilic granulocytes display different levels of c-fos proto-oncogene expression: an in situ hybridization study

The cellular homologue of the retroviral oncogene v-fos has been shown to be involved in cell differentiation of hematopoietic cells. By use of the human promyelocyte cell line HL-60, several in vitro differentiation studies suggested a selective activation of c-fos during monocytic differentiation of myeloid precursor cells. In contrast to these observations, we found high levels of c-fos mRNA in purified normal human granulocytes, whereas c-fos was only faintly expressed in blood monocytes. In situ hybridization revealed that the high level of c-fos expression is restricted to neutrophilic granulocytes, whereas c-fos transcription is not detectable in eosinophilic granulocytes. These results indicate that in vitro differentiation systems can be misleading and may not reflect the in vivo situation. The high level of c-fos expression in neutrophilic granulocytes may be caused by superinduction due to the reduced capacity for protein synthesis in these cells.

Serum profile of non-esterified fatty acids (NEFA) in patients with hyperlipoproteinemia under xantinol--nicotinate (XN) medication

The effect of 50 mg/kg body weight Xantinol-nicotinate (XN) on serum lipids and on non-esterified fatty acids (NEFA) was tested in 94 out-patients with hyperlipoproteinemia Types IIa, IIb, IV and V. The lipids were measured before treatment, during a 3-week period of drug administration and 10 days after rejection. In each group of hyperlipoproteinemic patients the lipid lowering effect of XN was accompanied by a constant fall in serum NEFA levels. The time dependent course of NEFA showed that the higher the initial level, the longer the time span required to achieve the lowest values. In the context of the partially conflicting data on the hypolipidemic action of nicotinic acid and its derivatives, it is suggested that the constant decrease in NEFA induced by XN treatment might contribute significantly to the lipid lowering effect of this drug.

Efficacy of hypolipidemic treatment in inhibition of experimental atherosclerosis: the effect of nicotinic acid and related compounds

The hypolipidemic and antiatherogenic effects of different nicotinic acid derivatives were studied. Five rabbit groups maintained on an atherogenic diet were given simultaneously various nicotinic acid derivatives (50 mg/kg body weight/day): nicotinic acid, Xantinol-nicotinate, beta-pyridylcarbinol or Pirozadil (bis-3,4,5-trimethoxybenzoate, 2,6-pyridindiyldimethylene). All 4 compounds showed a clear hypocholesterolemic and antiatherogenic effect, as measured by serum cholesterol, and by planimetric evaluation of the aortic lesions in terms of percent surface area affected in the aortas and coronary lumen. The simultaneously observed elevation of the HDL/LDL cholesterol ratio of the aortic tissue possibly indicates an antiatherogenic effect of these changes.

[Diagnosis of primary hyperlipoproteinemia in umbilical cord blood (author's transl)]

The aim of the present investigation was to assay the frequency of primary dyslipoproteinemia in a random sample of one hundred newborns and to describe the minimal methodical requirements for sound diagnosis. After comparison of different methods total lipids were determined by gravimetry, cholesterol and triglycerides by enzymatic methods, nonesterified fatty acids by direct colorimetry; phospholipids were estimated indirectly. All measurements were applied to umbilical cord sera and to lipoprotein fractions separated by selective precipitation. The diagnosis of hyperlipoproteinemia type IV, which is the most frequent one in adults, is highly afflicted with pitfalls in the postnatal period. A primary hyper-alpha-liproteinemia occured in one case and type II-hyperlipoproteinemia in two cases, one of the parents being involved in each case. For mass screening triglycerides should be assayed in serum and cholesterol in precipitated and resolubilized LDL-fraction, for which the minimal requirements are described.

[Therapy of hyperlipoproteinemia type II with Xantinol-nicotinate (author's transl)]

In 61 out-patients with hyperlipoproteinemia type II the action of 50 mg Xantinol-nicotinate per kg body weight on lipids of plasma and lipoproteins was investigated in a three week trial. The results of six patients had been discharged: two patients failed to attend the follow-up examinations, in four patients a lipid lowering effect could not be demonstrated. 40 Type IIa patients and 15 Type IIb patients were examined. In this two groups cholesterol, phospholipids and triglycerides of plasma were significantly lowered. In Type IIa hyperlipoproteinemia mainly the LDL lipids and in Type IIb additionally the VLDL lipids decreased. In Type IIb patients the decrease of lipids were more rapid than in Type IIa patients. This effect is interpreted by the short half life of VLDL. Withdrawel of the drug resulted in an increase of the lipids to the mean values of the untreated patients within ten days.

[Xantinol-nicotinate in primary type-V hyperlipoproteinaemia (author's transl)]

The effect of xantinol-nicotinate (50 mg/kg body-weight) on serum lipids and lipoproteins was tested in 16 out-patients with primary type V hyperlipoproteinaemia. The lipids and lipoproteins were measured before treatment, during a three-week period of drug administration and ten days after it had been stopped. There were no side effects such as flushing or gastritis, and no notable reduction of weight. Each serum-lipid fraction (triglycerides, nonesterified fatty acids, phospholipids, ester-cholesterol and free cholesterol) decreased significantly, regaining the initial values ten days after the drug had been stopped. While chylomicrons and very low-density lipoproteins (VLDL) decreased, there was a significant increase in low-density lipoproteins (LDL). High-density lipoproteins were not significantly changed. The decrease in chylomicrons and the significant decrease in VLDL with xantinol-nicotinate was opposite to that seen with dietary treatment. In none of the patients did LDL increase to abnormally high levels.

[Corneal arcus and hyperlipoproteinemia (author's transl)]

In 60 patients with corneal arcus the incidence of hyperlipoproteinemia was examined by serum lipid and lipoprotein analysis. An elevation of the serum lipid, or lipoprotein contents was found in every patient. 52 patients showed a primary type II hyperlipoproteinemia, three had a type IV, and one a type V pattern. In three cases hyperlipoproteinemia was found to be secondary to a severe cholestasis. The results show that the occurrence of corneal arcus in nearly every subject under 50 years of age and in most subjects over 50 years of age is highly suggestive of the presence of type II hyperlipoproteinemia. Until atherosclerotic complications appear, the course of the type II hyperlipoproteinemia is lingering and shows poor symptoms. Therefore, corneal arcus is of special importance for the early detection of this type of hyperlipoproteinemia.

Disc-electrophoretic protein pattern of cervical mucus in cases of humoral sensitization against spermatozoa

Midcycle cerevical mucus samples from 20 fertile women with negative, and from 6 infertile women with positive serum-sperm agglutinating activity were subjected to a qualitative protein analysis by the Ouchterlony-technique, to polyacrylamide (PAA) discelectrophoresis and after purification on spermatozoa they were also run against rabbit antihuman serum in the Laurell immuno-electrophoretic technique. By the Ouchterlony method the main serum protein fractions were shown to occur also in cervical mucus. No significant differences could be found in the protein pattern of samples from fertile and infertile females as detected by polyacrylamide (PAA) electrophoresis. In all samples a split protein fraction corresponding to serum albumin and a band preceding the protein fraction corresponding to serum preablumin were observed. In 2 samples from infertile females it could be demonstrated that immunoglobulins occurring in the cervical mucus were directed towards antigenic sperm components.

[Lipid constellation in low density lipoproteins of primary type II hyperlipoproteinemia (author's transl)]

The lipid composition of purified low density lipoproteins (LDL) was investigated in normal subjects and in type II a and b hyperlipoproteinemia. A significant increase of ester cholesterol in LDL of type II a patients and a decrease of phospholipids in LDL of type II b patients as compared with normal controls, were encountered. The results are compared with other reports from the literature and discussed with regard to the disturbance of LDL metabolism in type II hyperlipoproteinemia.