Distributions of most of the measured parameters were different from normal (Shapiro–Wilk’s test), therefore we used non-parametric tests. Changes in concentrations of cytokines in graft’s renal vein plasma were analyzed using Friedmann ANOVA and Wilcoxon signed-rank test.
Mann–Whitney U-test was performed to compare pa-rameters between DGF and non-DGF groups. Medians and interquartile ranges were calculated for each parameter.
Results
The plasma concentrations of cytokines in graft’s renal vein during 5 fi rst min. of reperfusion are shown in table 1.
The concentrations of IL-6 increased signifi cantly 1 min. after the start of reperfusion in patients with and without DGF. In 3 and 5 min. of reperfusion we observed the decrease in IL-6 concentrations, nevertheless the IL-6 concentrations in 5 min.
of reperfusion were signifi cantly higher than before reperfusion (tab. 1, fi g. 1). The concentrations of TNF-α increased dur-ing reperfusion and were signifi cantly higher in both groups than before reperfusion. The concentrations of IL-1β were also signifi cantly increased in 5 min. after the start of reperfusion compared to values before reperfusion. The concentrations of TNF-β, IL-4, IL-2 and IFN-γ did not change signifi cantly during fi rst 5 min. of reperfusion in both groups. The concentrations of IL-8 were undetectable in most samples.
CYTOKINE CONCENTRATIONS IN GRAFT RENAL VEIN DURING REPERFUSION 51
T a b l e 1. Median (interquartile range) renal vein plasma concentrations of cytokines before (RV0) and during reperfusion
(RV1, RV3, RV5) in recipients with and without delayed graft function (DGF)
T a b e l a 1. Mediana (rozstęp kwartylowy) stężeń cytokin w osoczu żyły nerkowej przed (RV0) i podczas reperfuzji (RV1, RV3, RV5)
u biorców z opóźnioną i bez opóźnionej funkcji graftu (DGF)
Cytokines IL-2 RV0 22.5 (49.9) 34.8 (31.4) 0.44 IL-2 RV1 25.2 (45.1) 19.9 (20.7) 0.94 IL-2 RV3 44.6 (24.5) 29.5 (51.3) 0.44 IL-2 RV5 56.3 (89.7) 32.3 (24.5) 0.44 IL-10 RV0 2.5 (5.4) 3.9 (3.9) 0.72 IL-4 RV0 453.5 (143.1) 452.6 (316.9) 0.94 IL-4 RV1 101.0 (133.1) 410.4 (431.4) 0.22 IL-4 RV3 278.8 (356.5) 561.5 (258.9) 0.35 IL-4 RV5 608.2 (512.0) 637.0 (420.6) 0.72 IL-1β RV0 20.4 (28.4) 5.4 (9.6) 0.13 IL-1β RV1 50.1 (65.2) 8.0 (44.9) 0.35 IL-1β RV3 4.7 (9.0) 8.2 (85.5) 0.83 IL-1β RV5 37.2 (57.5)* 32.3 (42.0)* 0.62 TNF-α RV0 31.3 (141.3) 112.7 (403.3) 0.22 TNF-α RV1 14.8 (77.6) 131.1 (250.0) 0.17 TNF-α RV3 167.8 (136.0)* 101.0 (267.1) 0.83 TNF-α RV5 223.2 (59.2)* 256.3 (139.5)* 0.44 TNF-β RV0 0.0 (17.2) 12.3 (35.8) 0.35 TNF-β RV1 22.5 (45.4) 7.0 (125.9) 0.62 TNF-β RV3 29.0 (40.1) 45.2 (36.6) 0.22 TNF-β RV5 8.6 (30.2) 21.8 (25.9) 0.52
* p < 0.05, for difference vs RV0 (Wilcoxon signed-rank test) / p < 0,05 dla różnicy vs RV0 (test Wilcoxona)
Fig. 1. The plasma concentrations of IL-6 in graft’s renal vein during 5 fi rst min. of reperfusion
Ryc. 1. Osoczowe stężenie IL-6 w żyle nerkowej graftu podczas pierwszych 5 min reperfuzji
Discussion
Despite recent advances in immunosuppressive therapy, DGF remains an important problem after kidney transplanta-tion. Different studies have related various clinical factors to DGF, such as donor age, recipient age, cold ischemia time, initial immunosuppressive regimens [8, 9, 10]. Cytokines have previously been studied in patients undergoing solid organ transplantation, and certain cytokines have been im-plicated in the development of complications such as acute rejection and chronic allograft failure [6]. The immune sys-tem is regulated by an array of cytokines, which infl uence cellular activation, differentiation, and function.
In the present study we examined the release of cyto-kines during 5 fi rst min. during kidney allograft reperfusion in patients with and without DGF. We observed the signifi -cant increase of IL-6, TNF-α and IL-1β release after the start of reperfusion in both groups. However there were no signifi cant differences in cytokine concentrations between patients with and without DGF. Above results indicate the increased release of IL-6, TNF-α and IL-1β during kidney allograft reperfusion, and no signifi cant release of IFN-γ, IL-2, IL-10, IL-8, IL-4 and TNF- β.
IL-6 is a pleiotropic cytokine involved in the regula-tion of immune responses. Although initially thought to be a proinfl ammatory cytokine, recent fi ndings suggest that IL-6 has many anti-infl ammatory and immunosuppressive effects [11]. Evidence for an anti-infl ammatory role of IL-6 also derived from studies in which co-administration of IL-6 was shown to suppress the acute neutrophil exudation caused by intratracheal administration of lipopolisaccharide (LPS) [12]. IL-6 exerts its protective effects through mul-tiple mechanisms, including the reduction of TNF-α pro-duction, thereby supporting an anti-infl ammatory role for IL-6. Further evidence of the role of IL-6 in the initiation of an anti-infl ammatory response comes from studies of oral infection of mice with Yersinia enterocolica: this resulted in the expression IL-1ra mRNA and synthesis of IL-1ra [13].
Aside from its role as an inducer of cytokine antagonists, IL-6 acts on the central nervous system (CNS) to elicit the
release of adrenocorticotropic hormone (ACTH), and ACTH in turn increases the synthesis of glucocorticoids in the adrenal gland. IL-6 stimulates the pituitary-adrenal axis when admin-istered at safe doses to human [14]. TNF-α is powerful inducer of the infl ammatory response and central regulator of innate immunity. Infl ammatory responses to TNF-α are mediated both directly and through stimulation of other proinfl ammatory cytokines [15]. The proinfl ammatory cytokine TNF-α, which stimulates macrophages function and increases MHC class II antigen expression, has been implicated in acute rejection and chronic rejection [16]. The activation of endothelial cells and the subsequent expression of the intercellular adhesion molecule-1 (ICAM-1) induced by TNF-α can enhance vascular permeability and therefore augment the infi ltration of proin-fl ammatory granulocytes into the graft [17]. The expression of ICAM-1 on the vascular endothelium has been associated with acute rejection in kidney transplants. The level of pro-duction of these cytokines at the site of the allograft could be important in accelerating rejection.
IL-1 is an important cytokine because it possesses sev-eral biological properties resulting in the increased expres-sion of proinfl ammatory genes. The most relevant property is the ability of IL-1 to initiate and sustain the expression of cyclooxygenase type 2 (COX-2) and inducible nitric oxide synthase. This accounts for the large amount of prosta-glandin-E2 (PGE2) and nitric oxide (NO) produced by cells exposed to IL-1 [18]. Another important proinfl ammatory property of IL-1 is its ability to increase the expression of adhesion molecules such as ICAM-1 on endothelial and other cell surfaces [19]. This property promotes the infi l-tration of infl ammatory and immunocompetent cells into the extravascular space.
The local environment in which an antigen-lymphocyte interaction takes place plays a major role in infl uencing the nature, severity and duration of the subsequent immune re-sponse, and cytokines are a major determinant of this milieu.
These are proteins that amplify and direct the immune re-sponse, and are produced by a wide variety of cells, including lymphocytes, antigen-presenting cells, and parenchymal cells.
However, cytokines do not act in isolation, but form a complex network of interacting proteins. Our previous study showed the lack of association between cytokine gene polymorphisms and delayed graft function [20]. The results of the present study indicated the enhanced release of IL-6, TNF-α and IL-1β during kidney allograft reperfusion, nevertheless it has no signifi cant effect on early graft function.
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A N N A L E S A C A D E M I A E M E D I C A E S T E T I N E N S I S
R O C Z N I K I P O M O R S K I E J A K A D E M I I M E D Y C Z N E J W S Z C Z E C I N I E 2008, 54, 1, 53–59
LESZEK DOMAŃSKI, TADEUSZ SULIKOWSKI1, MACIEJ ROMANOWSKI1, KRZYSZTOF SAFRANOW2, ANDRZEJ PAWLIK3, KATARZYNA JAKUBOWSKA2, VIOLETTA DZIEDZIEJKO2, MAGDA WIŚNIEWSKA,
MACIEJ DOMAŃSKI, DARIUSZ CHLUBEK2 , MARIA OLSZEWSKA2, KAZIMIERZ CIECHANOWSKI