Morphological, immunohistochemical and biochemical effects of non-pulsatile ex vivo perfusion with crescent pressures in human saphenous veins.

AIM: On the average, 15% to 25% of peripheral grafts and 10% to 30% of coronary grafts fail within 5 years. Changes in mechanical forces to which the vein is subjected could be an explanation for this phenomenon. We submitted human saphenous vein segments to non-pulsatile ex vivo perfusion with crescent pressures and evaluated morphology, nitric oxide synthase immunohistochemical expression; tissue levels of nitrite/nitrate and oxidative stress products. METHODS: Intact segments of human saphenous veins were obtained from 30 patients submitted to elective coronary artery bypass graft surgery. Ex vivo perfusion was performed during 3 hours, using oxygenated Krebs solution, flow of 100 mL/min and pressures of 0, 50, 100, 200 and 300 mmHg, defining five groups. RESULTS: Optical microscopy showed that veins of groups perfused with 200 and 300 mmHg presented increased luminal area and endothelial denuding. Electron microscopy transmission showed alterations in veins perfused with 200 and 300 mmHg. Immunohistochemical expression of the three nitric oxide synthase isoforms was observed in all vein layers, without significant difference among groups. Tissue levels of nitrite/nitrate were not significantly different among distinctive perfusion. Nitrotyrosine was not immunohistochemically expressed in all veins and malondialdehyde tissue levels were not different among groups. CONCLUSION: Non-pulsatile ex vivo perfusion during 3h caused morphological alterations in human saphenous veins (HSVs), which were not accompanied by immunohistochemical and biochemical alterations. Even with mechanical lesions, HSVs maintained the ability of express nitric oxide synthase (NOS) and release nitric oxide.

Activation of cytokines corroborate with development of inflammation and autoimmunity in thromboangiitis obliterans patients.

Thromboangiitis obliterans (TAO) is a segmental inflammatory occlusive disorder that affects the arm and leg arteries of young smokers. The immune system seems to play a critical role in the aetiology of TAO; however, knowledge of the aspects involved in the progression of vascular tissue inflammation and, consequently, the evolution of this disease is still limited. This study was carried out to investigate the cytokine levels of tumour necrosis factor (TNF)-α, interleukin (IL)-1ß, IL-4, IL-17 and IL-23 in the plasma of TAO patients presenting with acute clinical manifestations. The study included 20 TAO patients (n = 10 women; n = 10 men) aged 38-59 years under clinical follow-up, classified into two groups: (i) TAO former smokers (n = 11) and (ii) TAO active smokers (n = 9); the control groups included normal volunteer non-smokers (n = 10, active smokers (n = 10) and former smokers (n = 10). Patients' plasma samples were measured using the sandwich enzyme-linked immunosorbent assay. Statistical analyses were performed using the non-parametric Mann-Whitney U-test, with parameters significant at P < 0·05. The activities of all cytokines were different in groups of TAO patients when compared with normal controls, and decreased for control smokers. Increased levels of TNF-α, IL-1ß, IL-4, IL-17 and IL-23 were significant in patients with TAO when compared to the controls (P < 0·005, all parameters). The results presented here indicate an increased production of cytokines in TAO, possibly contributing to the inflammatory response observed in the patients' vascular levels. In addition, the increased levels of IL-17 and IL-23 suggest that the disturbance of TAO is involved with mechanisms of autoimmunity. Thus, the discovery of IL-17 and its association with inflammation and autoimmune pathology has reshaped our viewpoint regarding the pathogenesis of TAO, which was based previously on the T helper type 1 (Th1)-Th2 paradigm.

Determination of kininogens levels and kallikrein/kininase II activities in patients with thromboangiitis obliterans.

Some components of the kinin system such as plasma kallikrein levels, the activities of tissue kallikrein (including saliva) and kininase II and the concentrations of kininogen fractions (low-molecular weight/LKg and high-molecular weight/HKg) were evaluated in the plasma of patients with thromboangiitis obliterans (TAO) presenting clinical symptoms of the condition. Twenty TAO were diagnosed by means of the traditional Shionoya and Olin criteria and later classified into non-smokers (n = 11) and active smokers (n = 9). Fifty-three normal, non-smoking/smoking individuals (control) were also studied. Kininogen levels were determined by ELISA; the activities of kallikreins and kininase II were determined using selective substrates. The levels of enzymes (kallikreins and kininase II) and protein (kininogens) were significantly higher in patients with TAO who were active smokers compared to the control groups (no matter whether control individuals were active smokers or non-smokers, P < 0.001 for all comparisons). Interestingly, regardless of the time of disease onset, a significant increase in the levels of these components of the kinin system was also observed in patients when TAO active smokers were compared with TAO ex-smokers (P < 0.01 for all analysed parameters). Activation of the kinin system in patients with TAO may indicate the involvement of vasodilatation in an attempt to control vascular changes, thereby favouring the deposition of immune complexes at the vascular level because of nicotine stimulation. Moreover, our results corroborate the idea that TAO can be an autoimmune disorder with specific mechanisms.