Immunosuppressive agents and endothelial repair. Prednisolone delays migration and cytoskeletal rearrangement in wounded porcine aortic monolayers

Prednisolone suppresses adriamycin-induced vascular smooth muscle cell senescence and inflammatory response via the SIRT1-AMPK signaling pathway

Cellular senescence is associated with inflammation and the senescence-associated secretory phenotype (SASP) of secreted proteins. Vascular smooth muscle cell (VSMC) expressing the SASP contributes to chronic vascular inflammation, loss of vascular function, and the developments of age-related diseases. Although VSMC senescence is well recognized, the mechanism of VSMC senescence and inflammation has not been established. In this study, we aimed to determine whether prednisolone (PD) attenuates adriamycin (ADR)-induced VSMC senescence and inflammation through the SIRT1-AMPK signaling pathway. We found that PD inhibited ADR-induced VSMC senescence and inflammation response by decreasing p-NF-κB expression through the SIRT1-AMPK signaling pathway. In addition, Western blotting revealed PD not only increased SIRT1 expression but also increased the phosphorylation of AMPK at Ser485 in ADR-treated VSMC. Furthermore, siRNA-mediated downregulation or pharmacological inhibitions of SIRT1 or AMPK significantly augmented ADR-induced inflammatory response and senescence in VSMC despite PD treatment. In contrast, the overexpression of SIRT1 or constitutively active AMPKα (CA-AMPKα) attenuated cellular senescence and p-NF-κB expression. Taken together, the inhibition of p-NF-κB by PD through the SIRT1 and p-AMPK (Ser485) pathway suppressed VSMC senescence and inflammation. Collectively, our results suggest that anti-aging effects of PD are caused by reduced VSMC senescence and inflammation due to reciprocal regulation of the SIRT1/p-AMPK (Ser485) signaling pathway.

The Lymphocytes Stimulation Induced DNA Release, a Phenomenon Similar to NETosis

The release of DNA into the extracellular milieu by neutrophil during a process called NETosis has been postulated as an additional source of autoantigens; a process believed to be important in the pathogenesis of some autoimmune disease, such as systemic lupus erythematosus (SLE). However, it is not established if the B and T cells undergo the release of DNA to the extracellular milleu, in response to different stimuli. In this study, it was observed that the treatment of B and T cells with PMA, ionomycin and the serum from patients with SLE induced the extracellular DNA presence in B and T cells. These findings suggest that the phenomenon were similar to those observed in neutrophil's Etosis; B and T cells also released their DNA into the extracellular milieu. The findings express that serum from patients with SLE and SLEDAI ≤ 8 triggers the release of extracellular DNA in neutrophils, B and T cells, that suggested the presence of soluble factors in the serum that favoured this phenomenon.

Graft microvascular disease in solid organ transplantation

Alloimmune inflammation damages the microvasculature of solid organ transplants during acute rejection. Although immunosuppressive drugs diminish the inflammatory response, they do not directly promote vascular repair. Repetitive microvascular injury with insufficient regeneration results in prolonged tissue hypoxia and fibrotic remodeling. While clinical studies show that a loss of the microvascular circulation precedes and may act as an initiating factor for the development of chronic rejection, preclinical studies demonstrate that improved microvascular perfusion during acute rejection delays and attenuates tissue fibrosis. Therefore, preservation of a functional microvasculature may represent an effective therapeutic strategy for preventing chronic rejection. Here, we review recent advances in our understanding of the role of the microvasculature in the long-term survival of transplanted solid organs. We also highlight microvessel-centered therapeutic strategies for prolonging the survival of solid organ transplants.

Proinflammatory Reaction and Cytoskeletal Alterations in Endothelial Cells after Shock Wave Exposure

BACKGROUND

Although the effects on human organs by shock waves (SWs) induced by medical treatments or high-energy trauma are well recognized, little is known about the effects on the cellular level. Since blood vessel injury is a common finding after SW exposure, we assessed the in vitro effects of SWs on human umbilical vein endothelial cells (HUVECs).

METHODS

An in vitro trauma model was used to expose HUVEC monolayers to focused SWs or to shock waves plus cavitation (SWC), a subsequent phenomenon that is often considered the main cause of SW vascular injury.

RESULTS

SWs alone did not cause any changes in the studied variables. In contrast, HUVEC monolayers exposed to SWC exhibited discrete central lesions with extensive cell death. Cells peripheral to the main lesion area displayed disassembly of dense peripheral bands and formation of actin stress fibers, indicating increased intercellular gaps. Expression of P-selectin was enhanced 11-fold compared with controls, whereas expression of E-selectin and intercellular adhesion molecule 1 was enhanced 8-fold (p < .05) and 1.5-fold (p < .01), respectively. The latter responses were preceded by nuclear translocation of nuclear factor kappaB subunit p65 by 16% (p < .01). When compared with mechanically produced lesions used as controls, SWC lesions exhibited an impaired regeneration rate of the endothelial cell layer (p < .001). Redistribution of centrosomes toward the lesion borders was less effective in the SWC samples compared with the mechanically produced lesions (p < .01).

CONCLUSIONS

SWC lesions were associated with a switch to an endothelial proinflammatory phenotype, with an impaired regeneration rate and changes in cytoskeletal functions.

Effects of azathioprine and its metabolites on repair mechanisms of the intestinal epithelium in vitro

Erosions and ulcerations of the intestinal epithelium are hallmarks of inflammatory bowel diseases (IBD). Intestinal epithelial cell migration (restitution) and proliferation are pivotal mechanisms for healing of epithelial defects after mucosal injury. In addition, the rate of apoptosis of epithelial cells may modulate intestinal wound healing. The purine antagonists azathioprine (AZA) and 6-mercaptopurine (6-MP) are widely used drugs in the treatment of IBD. In the present study, the hitherto unknown effects of AZA as well as its metabolites 6-MP and 6-thioguanine (6-TG) on repair mechanisms and apoptosis of intestinal epithelia were analysed. Intestinal epithelial cell lines (human Caco-2, T-84 and HT-29 cells, rat IEC-6 cells) were incubated with AZA, 6-MP or 6-TG for 24 h (final concentrations 0.1-10 microM). Migration of Caco-2 and IEC-6 cells was analysed by in vitro restitution assays. Caco-2 and IEC-6 cell proliferation was evaluated by measurement of [3H]thymidine incorporation into DNA. Apoptosis of Caco-2, T-84, HT-29 and IEC-6 cells was assessed by histone ELISA, 4'6'diamidino-2'phenylindole-dihydrochloride staining as well as flow cytometric analysis of Annexin V/propidium iodide (PI)-stained cells. Cell cycle progression was evaluated by PI staining and flow cytometry. Epithelial restitution was not significantly affected by any of the substances tested. However, proliferation of intestinal epithelial cells was inhibited in a dose-dependent manner (maximal effect 92%) by AZA, 6-MP as well as 6-TG. In HT-29 cells, purine antagonist-effected inhibition of cell proliferation was explained by a cell cycle arrest in the G2 phase. In contrast, AZA, 6-MP and 6-TG induced no cell cycle arrest in Caco-2, T-84 and IEC-6 cells. AZA, 6-MP as well as 6-TG induced apoptosis in the non-transformed IEC-6 cell line but not in human Caco-2, T-84 and HT-29 cells. In summary, AZA and its metabolites exert no significant effect on intestinal epithelial restitution. However, they profoundly inhibit intestinal epithelial cell growth via various mechanisms: they cause a G2 cell cycle arrest in HT-29 cells, induce apoptosis in IEC-6 cells and dose-dependently inhibit intestinal epithelial proliferation.

Healing following tooth extraction in cyclosporine-fed rats

Healing after tooth extraction was studied in rats treated with cyclosporine-A (CSA) for four weeks. Sixty male Sprague-Dawley rats were assigned to one of three groups of 20 rats each. The maxillary right molars were extracted from two groups; the third group served as a non-extraction control. The non-extraction group and one extraction group (vehicle control) received the solvent mineral oil daily, and the other extraction group received 15 mg/kg CSA in mineral oil. Five rats from each group were killed 5, 10, 14 and 28 days after extraction and samples analyzed histologically. On days 5 and 10, bone volume was significantly lower and marrow volume significantly higher in both extraction groups than in the non-extraction group. The fractional-formation surfaces were significantly lower in the extraction groups than in the non-extraction group on day 5 only. Osteoid volume was significantly higher in the extraction vehicle control group than in the other two groups on days 10 and 14; however, the osteoid volume was higher in the CSA group than in the other two groups on day 28. On days 14 and 28, bone volume was lower and marrow volume higher in the CSA group than in the extraction vehicle control and non-extraction groups. On day 28, bony surface areas were significantly greater in the CSA group than in the extraction vehicle control and non-extraction groups. Soft-tissue evaluation showed significantly greater epithelial areas, connective tissue areas and total tissue areas in the CSA group than in the extraction vehicle control group on day 28, but not on day 14. These data suggest that CSA may influence healing of both the gingival tissue and the alveolar bony sockets in the tooth-extraction wound. Further detailed study is needed to identify the mechanisms responsible.

Reactivity patterns of antiphospholipid antibodies and endothelial cells: effect of antiendothelial antibodies on cell migration

Antiphospholipid syndrome (APS) is characterized by the presence of a heterogeneous class of antibodies directed against phospholipids and associated with high occurrence of thrombotic complications. Antiendothelial cell antibodies (AECAs) have been identified in various autoimmune disorders including APS, but their reactivity patterns remain unclear. We used eluted endothelial membrane-bound antibodies (EC eluates) to investigate possible cross-reactivity of AECAs and their pathogenic effects on endothelial cell integrity. The heterogeneous and nonspecific nature of AECAs was confirmed by our finding that they cross-react with fibroblasts and platelets and bind to cardiolipin. In addition, platelet-bound antibodies from sera of patients with APS reacted with endothelial cells. A dose-dependent binding of human monoclonal anticardiolipin antibody was demonstrated, but this antibody did not compete with AECAs in EC eluates, indicating that only small portion of AECAs are directed against cardiolipin. Although sera from APS patients prolonged coagulation tests, EC eluates did not affect coagulation, suggesting that AECAs may belong to antiphospholipid antibodies subsets that does not interfere with coagulation. Vascular damage is a common feature of autoimmune disorders associated with AECAs. Possible effects of AECAs on vascular perturbance were investigated by cytotoxicity, attachment, and migration assays. Although AECAs were not shown to be cytotoxic or to affect cell attachment, sera from APS patients caused reduced cellular migration (by 30%), and EC eluates caused even more significant inhibition (by 50%). These findings suggest possible interference of AECAs in vascular repair mechanisms and provide an explanation for the thrombotic complications frequently seen in APS patients.

Accelerated atherosclerosis and coronary disease in SLE

Atherosclerosis may represent a significant cause of death and morbidity in patients with systemic lupus erythematosus. Coronary involvement is more premature in lupus patients. We present the case of a young woman diagnosed with SLE at the age of 20 years who had a myocardial infarction at age 29 years. We review the mechanisms of atherosclerosis, the interrelations between atherosclerosis and autoimmunity, and between atherosclerosis and SLE. We also review the risk factors, influence of disease and treatment and the guidelines for management of accelerated atherosclerosis in lupus patients.