Long-term cyclosporine treatment in non-transplanted rats and metabolic risk factors of vascular diseases

Dual action of macrophage miR-204 confines cyclosporine A-induced atherosclerosis

BACKGROUND AND PURPOSE

Atherosclerosis induced by cyclosporine A (CsA), an inhibitor of the calcineurin/nuclear factor of activated T cells (NFAT) pathway, is a major concern after organ transplantation. However, the atherosclerotic mechanisms of CsA remain obscure. We previously demonstrated that calcineurin/NFAT signalling inhibition contributes to atherogenesis via suppressing microRNA-204 (miR-204) transcription. We therefore hypothesised that miR-204 is involved in the development of CsA-induced atherosclerosis.

EXPERIMENTAL APPROACH

ApoE-/- mice with macrophage-miR-204 overexpression were generated to determine the effects of miR-204 on CsA-induced atherosclerosis. Luciferase reporter assays and chromatin immunoprecipitation sequencing were performed to explore the targets mediating miR-204 effects.

KEY RESULTS

CsA alone did not significantly affect atherosclerotic lesions or serum lipid levels. However, it exacerbated high-fat diet-induced atherosclerosis and hyperlipidemia in C57BL/6J and ApoE-/- mice, respectively. miR-204 levels decreased in circulating monocytes and plaque lesions during CsA-induced atherosclerosis. The upregulation of miR-204 in macrophages inhibited CsA-induced atherosclerotic plaque formation but did not affect serum lipid levels. miR-204 limited the CsA-induced foam cell formation by reducing the expression of the scavenger receptors SR-BII and CD36. SR-BII was post-transcriptionally regulated by mature miR-204-5p via 3'-UTR targeting. Additionally, nuclear-localised miR-204-3p prevented the CsA-induced binding of Ago2 to the CD36 promoter, suppressing CD36 transcription. SR-BII or CD36 expression restoration dampened the beneficial effects of miR-204 on CsA-induced atherosclerosis.

CONCLUSION AND IMPLICATIONS

Macrophage miR-204 ameliorates CsA-induced atherosclerosis, suggesting that miR-204 may be a potential target for the prevention and treatment of CsA-related atherosclerotic side effects.

Effect of Simulated Geomagnetic Activity on Myocardial Ischemia/Reperfusion Injury in Rats

Objective

To study the response of myocardial ischemia/reperfusion injury (MI/RI) in rats to simulated geomagnetic activity.

Methods

In a simulated strong geomagnetic outbreak, the MI/RI rat models were radiated, and their area of myocardial infarction, hemodynamic parameters, creatine kinase (CK), lactate dehydrogenase (LDH), melatonin, and troponin I values were measured after a 24-hour intervention.

Results

Our analysis indicates that the concentrations of troponin I in the geomagnetic shielding+operation group were lower than in the radiation+operation group (P<0.05), the concentrations of melatonin in the shielding+operation group and normal+operation group were higher than in the radiation + operation group (P<0.01), and the concentrations of CK in the shielding + operation group were lower than in the radiation + operation group and normal + operation group (P<0.05). Left ventricular developed pressure (LVDP) and ± dP/dtmax in the radiation+operation group were lower than in the shielding + operation group and normal+operation group (P<0.01). Left ventricular end-diastolic pressure (LEVDP) in the shielding + operation group was higher than in the normal + operation group (P<0.05). There was no significant difference in area of myocardial infarction and LDH between the shielding + operation group and the radiation + operation group.

Conclusion

Our data suggest that geomagnetic activity is important in regulating myocardial reperfusion injury. The geomagnetic shielding has a protective effect on myocardial injury, and the geomagnetic radiation is a risk factor for aggravating the cardiovascular and cerebrovascular diseases.

Effect of long-term immunosuppressive therapy on native rat liver morphology and hepatocyte- apoptosis

A negative result of therapy based on immunosuppressive drugs is its leading to pathological alterations in the organ, including liver. Use of immunosuppressive medication may also lead to organized and genetically controlled cell death - apoptosis. The aim of this study was to examine histopathological changes in the livers of rats treated with immunosuppressive drugs, and also to determine the effects of different groups of immunosuppressive drugs on apoptosis activity in the hepatocytes of rat livers. The study was conducted on archival material obtained from Department of Nephrology, Transplantology and Internal Medicine of the Independent Public Clinical Hospital No. 2 at the Pomeranian Medical University in Szczecin, Poland. Statistical comparison of the treatment groups showed that all groups with rapamycin (sirolimus)-based regimens: Tacrolimus, Rapamycin, Glucocorticosteroid (TRG); Cyclosporine, Rapamycin, Glucocorticosteroid (CRG); Mycophenolate, Rapamycin, Glucocorticosteroid (MRG) and additionally Cyclosporine, Mycophenolate, Glucocorticosteroid (CMG) exhibited significantly more pronounced apoptosis than the control group, with p < 0.01, p < 0.05, p < 0.01 and p < 0.01, respectively. Furthermore, in the TRG group, over 90% of apoptotic hepatocytes were seen in the examined classic lobules. Additionally, every liver from treatment group was pathologically altered, including dilated sinusoids, pyknotic nuclei, swollen walls of the vessels. Long-lasting immunosuppressive treatment affects the liver both in terms of histological changes within the structure of the liver and in terms of the percentage of apoptotic hepatocytes. The following study seems to be very innovating due to the duration of the experiment and used drugs-protocols, since they reflect human treatment.

Effects of cyclosporine and sirolimus on insulin-stimulated glucose transport and glucose tolerance in a rat model

Cyclosporine (CsA) and sirolimus (SRL) have been associated with undesirable side effects, including posttransplantation diabetes and hyperlipidemia, but the molecular mechanisms underlying these effects remain to be elucidated. Animal studies focusing on clinically relevant doses are advised. This study sought to compare the metabolic effects on isolated rat adipocytes treated with either CsA or SRL ex vivo and after long-term in vivo treatment in Wistar rats. We assessed the ex vivo effects of CsA (0.5-30 μmol/L) and SRL (1-250 μmol/L) on insulin-stimulated (14)C-glucose uptake in epididymal adipocytes (n = 6-9). In parallel, rats (n = 12) were treated with either vehicle, CsA (5 mg/kg/d) or SRL (1 mg/kg/d) for either 3 or 9 weeks. At the end of the treatment, glucose tolerance test (GTT) and insulin-stimulated (14)C-glucose uptake as well as biochemical parameters were analyzed. A significant reduction in the insulin-stimulated glucose uptake over basal was observed among isolated adipocytes, whether exposed ex vivo or in vivo to CsA or SRL treatment. Furthermore, the SRL group showed significantly lighter fat pads and smaller adipocytes at 3 weeks with a smaller gain in body weight throughout the study compared with either the vehicle or CsA cohorts. Glucose intolerance was observed after a GTT, at the end of the treatment with either drug. Additionally, at 9 weeks serum triglycerides were increased by CsA compared with vehicle or SRL treatment. Interestingly, although SRL-treated animals presented higher fed and fasted insulin levels compared with either group, suggesting insulin resistance, the CsA group presented lower fed and fasted insulin values, suggesting a defect in insulin secretion at 9 weeks. These results suggested that either ex vivo treatment of fat cells or in vivo treatment of rats with CsA or SRL impaired insulin-stimulated glucose uptake by adipocytes. Both drugs caused glucose intolerance, which altogether could be responsible for the development of posttransplantation diabetes.

Chronic treatment with cyclosporine affects systemic purinergic parameters, homocysteine levels and vascular disturbances in rats

Vascular disease is a major cause of morbidity and mortality among transplanted recipients and cyclosporine (CsA) treatment has been consistently implicated in this event. In this study we assessed total blood homocysteine levels (tHcy), ecto-nucleotidase activities and adenine nucleotide/nucleoside levels searching for parameters related to the mechanisms of vascular damage induced by chronic CsA treatment in non-transplanted rats. Thirty male Wistar rats were divided in three groups: control group treated with corn oil, CsA 5mg/kg and CsA 15 mg/kg, administered by daily gastric gavage during 8 weeks. CsA 15 mg/kg treatment increased blood levels of tHcy. Both CsA treatments (5mg/kg and 15 mg/kg) decreased adenine nucleotides hydrolysis by ecto-nucleotidases in serum, which negatively correlated with tHcy levels (r: -0.74, r: -0.63 and r: -0.63, p<0.004, for ATP, ADP and AMP, respectively). CsA 15mg/kg induced a statistically significant increase in ADP and decrease in adenosine (ADO) plasma levels compared to control group. THcy levels were positively correlated with plasma ADP levels and negatively correlated with ADO levels (r: 0.84, p<0.0001 and r: -0.68, p<0.0001, respectively). Rats under CsA 15 mg/kg treatment presented cell injury and inflammatory responses in the endothelium and intima layer of the aorta artery. In conclusion, blood ecto-nucleotidases activity, tHcy, and ADP and ADO levels may be implicated in vascular injury induced by CsA treatment.

Cyclosporin A and atherosclerosis--cellular pathways in atherogenesis

Cyclosporin A (CsA) is an immunosuppressant drug widely used in organ transplant recipients and people with autoimmune disorders. Long term treatment with CsA is associated with many side effects including hyperlipidemia and an increased risk of atherosclerosis. While its immunosuppressive effects are closely linked to its effects on T cell activation via the inhibition of the nuclear factor of activated T cells (NFAT) pathway, the precise mechanisms underlying its cardiovascular effects appear to involve multiple pathways additional to those relevant for immunosuppression. These include inhibition of calcineurin activity and intracellular cyclophilin peptidylprolyl isomerase and chaperone activities, inhibition of pro-inflammatory extracellular cyclophilin A, and NFAT-independent transcriptional effects. CsA demonstrates complex effects on lipoprotein metabolism and bile acid production, and affects endothelial cells, smooth muscle cells and macrophages, all of which are critical to the atherosclerotic process. Interpretation of the available data is hampered as many experimental models are used to study the effects of CsA in vivo and in vitro, leading to diverse and often contradictory findings. In this review we will describe the cellular mechanisms related to CsA-induced hyperlipidemia and atherosclerosis, with a focus on identifying pro-atherogenic pathways that are distinct from those relevant to its immunosuppressant effects. The potential of CsA analogues to avoid such sequelae will be discussed.