Meta-analysis of epigenome-wide association studies of carotid intima-media thickness

Common carotid intima-media thickness (cIMT) is an index of subclinical atherosclerosis that is associated with ischemic stroke and coronary artery disease (CAD). We undertook a cross-sectional epigenome-wide association study (EWAS) of measures of cIMT in 6400 individuals. Mendelian randomization analysis was applied to investigate the potential causal role of DNA methylation in the link between atherosclerotic cardiovascular risk factors and cIMT or clinical cardiovascular disease. The CpG site cg05575921 was associated with cIMT (beta?=??0.0264, p value?=?3.5?×?10^–8) in the discovery panel and was replicated in replication panel (beta?=??0.07, p value?=?0.005). This CpG is located at chr5:81649347 in the intron 3 of the aryl hydrocarbon receptor repressor gene (AHRR). Our results indicate that DNA methylation at cg05575921 might be in the pathway between smoking, cIMT and stroke. Moreover, in a region-based analysis, 34 differentially methylated regions (DMRs) were identified of which a DMR upstream of ALOX12 showed the strongest association with cIMT (p value?=?1.4?×?10^–13). In conclusion, our study suggests that DNA methylation may play a role in the link between cardiovascular risk factors, cIMT and clinical cardiovascular disease.

     

Antimicrobial effects of murine mesenchymal stromal cells directed against Toxoplasma gondii and Neospora caninum: role of immunity-related GTPases (IRGs) and guanylate-binding proteins (GBPs)

Mesenchymal stromal cells (MSCs) have a multilineage differentiation potential and provide immunosuppressive and antimicrobial functions. Murine as well as human MSCs restrict the proliferation of T cells. However, species-specific differences in the underlying molecular mechanisms have been described. Here, we analyzed the antiparasitic effector mechanisms active in murine MSCs. Murine MSCs, in contrast to human MSCs, could not restrict the growth of a highly virulent strain of Toxoplasma gondii (BK) after stimulation with IFN-γ. However, the growth of a type II strain of T. gondii (ME49) was strongly inhibited by IFN-γ-activated murine MSCs. Immunity-related GTPases (IRGs) as well as guanylate-binding proteins (GBPs) contributed to this antiparasitic effect. Further analysis showed that IFN-γ-activated mMSCs also inhibit the growth of Neospora caninum, a parasite belonging to the apicomplexan group as well. Detailed studies with murine IFN-γ-activated MSC indicated an involvement in IRGs like Irga6, Irgb6 and Irgd in the inhibition of N. caninum. Additional data showed that, furthermore, GBPs like mGBP1 and mGBP2 could have played a role in the anti-N. caninum effect of murine MSCs. These data underline that MSCs, in addition to their regenerative and immunosuppressive activity, function as antiparasitic effector cells as well. However, IRGs are not present in the human genome, indicating a species-specific difference in anti-T. gondii and anti-N. caninum effect between human and murine MSCs.     

Die diabetischen Folgeerkrankungen

Zusammenfassung Die diabetesassoziierten Folgeerkrankungen tragen zu einer erheblichen Verminderung der Lebensqualität und deutlichen Erhöhung der Mortalität bei. Die Folgeschäden manifestieren sich im Sinne einer Makroangiopathie als koronare Herzkrankheit, periphere arterielle Verschlusskrankheit und zerebrovaskuläre Insuffizienz. Außerdem besteht ein hohes Risiko für eine diabetische Nephropathie, Neuropathie und Retinopathie, mit der Gefahr der Entwicklung einer chronischen Niereninsuffizienz, eines Visusverlusts oder eines diabetischen Fußsyndroms. Obwohl die chronische Hyperglykämie einen eigenständigen Risikofaktor für makro- und mikroangiopathische Komplikationen darstellt, steigern assoziierte Erkrankungen wie die arterielle Hypertonie und Hypercholesterinämie das Mortalitätsrisiko in einem erheblichen Maße. In den letzten Jahren wurden deshalb neue Konzepte für die Verbesserung der Diagnose, Therapie und Langzeitbetreuung von Diabetikern erstellt, die neben einer normnahen Blutzuckereinstellung die konsequente Behandlung begleitender Risikofaktoren beinhaltet. Durch diese optimierte Betreuung kann die Lebensqualität und Prognose von Patienten mit Diabetes mellitus verbessert werden.

---

     

Preliminary evidence that an endogenous retroviral long-terminal repeat (LTR13) at the HLA-DQB1 gene locus confers susceptibility to Addison's disease

OBJECTIVE: Addison's disease is associated with particular haplotypes of the human leucocyte antigen (HLA) region [DQA1*0501-DQB1*0201 (DQ2) and DQA1*0301-DQB1*0302 (DQ8)]. This locus harbours several human endogenous retroviral (HERV) long-terminal repeats (LTR). LTRs within the HLA region have been shown to confer additional susceptibility to type 1 diabetes and rheumatoid arthritis. DESIGN: We investigated the role of LTR3 and LTR13, both of which are located adjacent to the DQB1 gene, in Addison's disease. PATIENTS: Eighty-seven patients and 160 controls were genotyped for HLA-DQA, -DQB, and the presence or absence of LTR3 and LTR13. RESULTS: Significantly more patients' HLA alleles than those of controls carried the LTR13 insertion (19.0% vs. 10.6%, P = 0.0143), whereas there was only a trend for LTR3 (allele-wise chi-squared test: P = 0.0941). Both, LTR3 and LTR13 are in strong linkage disequilibrium with DQ8, which itself was significantly more frequent in patients than in controls (29.9% vs. 15.0%, P = 0.0089). However, significantly more alleles of DQ8+ patients than of DQ8+ controls carried the LTR13 insertion (44.2% vs. 18.8%, P = 0.0119), whereas we did not observe any difference for LTR3 in the DQ8+ subset (30.5 vs. 23.1%, P = 0.9416). CONCLUSIONS: We have found preliminary evidence that the endogenous retroviral element DQ-LTR13, but not LTR3, is associated with Addison's disease. LTR13 appears to enhance HLA-DQ8 mediated disease risk. This retroviral insertion therefore might represent a novel susceptibility factor in Addison's disease, but these findings need to be confirmed in a larger data set.     

Dendritic cell-based immunotherapy in thyroid malignancies

A new approach for anti-tumor immunotherapy is to use dendritic cells (DCs) as adjuvants in order to actively immunize cancer patients with antigens specifically expressed in tumor cells. DCs possess a unique capacity to effectively activate CD4+ T helper cells and CD8+ cytotoxic T cells. During the last years, several clinical trials in various malignancies demonstrated that immunizations with tumor antigen pulsed DCs could break the tolerance of the immune system against antigens expressed by the tumor cells resulting in partial or complete remission in some cases. This review describes the most important findings on the interaction between DCs and T cells as well as natural killer cells and summarizes recent data on DC vaccination of endocrine and non-endocrine malignancies. The results from current pilot studies suggest that DC vaccination may represent a promising strategy for the development of an anti-cancer vaccine to treat chemotherapy and radioresistant endocrine malignancies.     

Spiral volumetric CT with single-breath-hold technique, continuous transport, and continuous scanner rotation

Continuous computed tomographic (CT) scanning of organ volumes during a single breath hold was studied. The authors modified the table feed mechanism of a continuously rotating CT scanner to allow patient transport at low, but accurately controlled, speeds (0.1-11.0 mm/sec) during continuous 1-second scanning. An algorithm was designed to reconstruct artifact-free images for arbitrary table positions from the helical data by interpolating between adjacent scans. Section sensitivity profiles were enlarged; the section width for a 10-mm section and a speed of 10.0 mm/sec was increased by a factor of 1.3, compared with the nominal value. Clinical examples were presented for studies of lung nodules and studies enhanced with contrast medium. Major advantages are the possibility of continuous scanning of extended volumes within a breath-hold period and retrospective, arbitrary selection of anatomic levels.     

Cell therapeutic strategies to improve pig islet graft survival after xenotransplantation

Transplantation of the whole pancreas organ or isolated Langerhans‐islets is the only methods to cure Type 1 diabetes. Transplantation is largely limited by the lack of organ donors and considerable side effects of immunosuppressive therapies. Porcine pancreas represents a promising cell source to overcome the shortage of islets. Due to the strong rejection of xenoantigens novel strategies such as the generation of transgenic pig islets are needed. Another complementary alternative is the co‐transplantation with immunomodulatory cells that mediate only local immunosuppression at the transplantation site. Mesenchymal stem cells (MSCs) are unique cells residing in different tissues which possess pleiotropic immunoregulatory activities. We isolated murine and human MSCs from bone‐marrow (CD73⁺, CD105⁺) and used them for in vitro experiments (mixed lymphocyte reaction after mitogen, allogenic and xenogenic stimulation) and co‐transplantation studies in diabetic C57BL/6 mice. Both murine and human MSCs exert strong immunosuppressive effects on lymphocyte proliferation (up to 75% and 80% respectively). Interestingly, there were major differences in the underlying mechanisms. We were able to demonstrate for the first time that mouse MSCs suppressed MLR by a combination of prostaglandin E2 production and adenosine formation. Only human but not mouse MSCs do express the tryptophan degrading enzyme indoleamine 2,3‐dioxygenase (IDO) upon stimulation with proinflammatory cytokines. Our features such as TGFβ and hepatocyte growth factor (HGF) production also contribute to the immunoregulatory effect. When human lymphocytes were challenges with porcine antigens there was a strong proliferative immune response which can be suppressed in a dose‐dependent manner by the addition of hMSCs (inhibition up to 95%). Co‐transplantation of allogenic islets with MSCs favoured islet cell function and survival. This effect was dependent on the MSC source as demonstrated by the fact that the use of donor MSCs resulted in longer survival rate as compared to syngenic MSCs. In current experiments we test the effect of hMSCs in the NOD SCID‐IL2R^–/–mouse model to study immune response of human PBMCs towards porcine islets. In conclusion, our results strongly support and extend the concept that MSCs are potent candidates to control cellular immune rejection. We observed surprising differences in the immunosuppressive properties between mouse and human MSCs. Since human MSCs also strongly suppress immune response against pig antigens, they are promising novel candidates to modulate the local microenviroment for islet cell xenotransplantation. The next step is to analyse survival of transgenic pig islets (CTLA‐4 Ig) with and without hMSC in diabetic NOD SCID‐IL2R^–/–mice. Supported by the Deutsche Forschungsgemeinschaft (Transregio Forschergruppe ‘‘Xenotransplantation’’, FOR 535).