Sitagliptin reduces plaque macrophage content and stabilises arteriosclerotic lesions in Apoe (-/-) mice

AIMS/HYPOTHESIS

Inhibitors of dipeptidyl peptidase-IV (DPP-IV), such as sitagliptin, increase glucagon-like peptide-1 (GLP-1) concentrations and are current treatment options for patients with type 2 diabetes mellitus. As patients with diabetes exhibit a high risk of developing severe atherosclerosis, we investigated the effect of sitagliptin on atherogenesis in Apoe (-/-) mice.

METHODS

Apoe (-/-) mice were fed a high-fat diet and treated with either sitagliptin or placebo for 12 weeks. Plaque size and plaque composition were analysed using Oil Red O staining and immunohistochemistry. Furthermore, in vitro experiments with the modified Boyden chamber and with gelatine zymography were performed to analyse the effects of GLP-1 on isolated human monocyte migration and metalloproteinase-9 (MMP-9) release.

RESULTS

Treatment of Apoe (-/-) mice with sitagliptin significantly reduced plaque macrophage infiltration (the aortic root and aortic arch both showing a 67% decrease; p < 0.05) and plaque MMP-9 levels (aortic root showing a 69% and aortic arch a 58% reduction; both p < 0.01) compared with controls. Moreover, sitagliptin significantly increased plaque collagen content more than twofold (aortic root showing an increase of 58% and aortic arch an increase of 73%; both p < 0.05) compared with controls but did not change overall lesion size (8.1 ± 3.5% vs 5.1 ± 2.5% for sitagliptin vs controls; p=NS). In vitro, pretreatment of isolated human monocytes with GLP-1 significantly decreased cell migration induced by both monocyte chemotactic protein-1 and by the protein known as regulated on activation, normal T cell expressed and secreted (RANTES) in a concentration-dependent manner. Furthermore, GLP-1 significantly decreased MMP-9 release from isolated human monocyte-derived macrophages.

CONCLUSIONS/INTERPRETATION

Sitagliptin reduces plaque inflammation and increases plaque stability, potentially by GLP-1-mediated inhibition of chemokine-induced monocyte migration and macrophage MMP-9 release. The effects observed may provide potential mechanisms for how DPP-IV inhibitors could modulate vascular disease in high-risk patients with type 2 diabetes mellitus.

Protocols for efficient repetitive and secondary somatic embryogenesis in Helianthus maximiliani (Schrader)

 Indirect somatic embryogenesis was induced on leaf explants of greenhouse-grown Helianthus maximiliani plants. Leaves of the regenerated plants were used as starting explants for the induction of direct somatic embryogenesis. Another cycle of somatic embryogenesis was induced on the leaves of regenerated plants. In both cases, leaf explants were cultured on media containing different auxin/cytokinin ratios. The auxin/cytokinin ratio had an influence on the intensity of embryo formation, germination and the capability to regenerate plants. Somatic embryogenesis was generally more intensive on the medium with lower concentrations of 6-benzylamino-purine. Further, the percentage of regenerated plants was higher when embryos were induced on high-cytokinin, low-auxin medium. Secondary somatic embryogenesis was induced on embryos by culture in liquid hormone-free medium. Similar to direct embryogenesis the efficiency of secondary embryogenesis depended on the medium used for the induction of the primary embryos. In contrast to the mostly low frequencies of conversion of secondary embryos into plants that has been observed in other species, the percentage of regenerated plants from secondary embryos of H. maximiliani was quite high, although slightly lower than that obtained in primary embryos.

[Possibility of serious damage when handling air guns]

The possibilities of serious injury being caused by firearms are well known. Less known is the fact that air guns also have such potential. We present the case of a six year old boy shot in the back with an air gun at a distance of four meters. Vital signs were normal. A small entrance wound was found in the back. On a CT scan, an air gun pellet was found to be situated partly inside the posterior wall of the stomach. There was no sign of peritonitis or complications of any other kind so one chose to await the course of events without surgical intervention. A few days later the patient was discharged in good health. An X-ray taken some days later showed no projectile; it seems to have migrated into the gastrointestinal tract and been shed along with faeces. The available literature suggests that air guns have considerable penetration abilities; this case underlines that. Articles on this subject are summarized and we discuss the options available in similar cases.