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Background: There are presently no established pre-transplant tests that consistently identify patients who may be at increased risk for acute rejection episodes after renal transplantation. We studied whether pretransplant serum levels of C-reactive protein (CRP), a marker for the presence of systemic inflammation, would predict the occurrence of acute rejection episodes after renal transplantation., Methods: Pretransplant serum was tested for CRP level in 97 consecutive renal transplant recipients. Time to acute rejection after transplantation was stratified by CRP level and compared using the Kaplan-Meier method. In addition, Cox regression multivariate analysis was performed to assess whether any pretransplant covariates could independently predict the subsequent occurrence of acute rejection episodes., Results: Pretransplant mean CRP levels were higher in patients who subsequently had a rejection episode versus those who had no rejection (22.2+/-2.9 vs. 11.7+/-1.8 microg/ml, respectively, P=0.003). Patients less than the median CRP value had a significantly longer time to rejection compared to those with higher CRP levels (P=0.002). Similarly, patients within the lowest CRP quartile had longer times to rejection when compared with the highest quartile (P=0.006). Cox proportional hazards regression multivariate analysis identified CRP level as the only independent pretransplant risk factor for rejection identified (P=0.044)., Conclusions: Pretransplant systemic inflammation as manifested by elevated serum CRP level independently predicts the risk of acute rejection after renal transplantation and may be useful in stratifying patients at the time of transplantation according to immunological risk. Thus, assessment of pretransplant systemic inflammatory status may be helpful in prospective individualization of immunosuppression therapy after renal transplantation.

A computer-assisted intravital microscopy technology has been developed to noninvasively and objectively study diabetic microangiopathy in the conjunctival microcirculation of type-1 diabetics. Quantitative characterization of the conjunctival microcirculation was performed on 12 patients pre- and 18 months postsimultaneous pancreas-kidney transplantation (SPK). Healthy nondiabetic volunteers (n=12), solitary kidney (K) transplanted type-1 diabetics (n=5), and nontransplanted type-1 diabetics (n=12) served as controls. Pre-SPK diabetics showed abnormal-sized venules (diameter=66+/-7 microm) and reduced presence of arterioles (arteriole length/area=18+/-6 microm(-1)) compared with nondiabetic controls (53+/-4 microm; 31+/-8 microm(-1); P<0.05). The computed vascular perfusion capacity of the conjunctival microvasculature was diminished in the same patients (pre-SPK diabetics=49+/-9%; nondiabetic healthy controls=71+/-6%; P<0.05). Significant improvement in microangiopathy was observed in all post-SPK diabetics (diameter=58+/-6 microm; arteriole length/area=26+/-9 microm(-1); vascular perfusion=63+/-8%; P<0.05) 18 months post-SPK. Blood flow velocities in the conjunctival microcirculation in the same post-SPK patients showed noticeable but not significant improvements (nondiabetic controls=2.94+/-0.57 mm/sec; pre-SPK=1.23+/-0.49 mm/sec; post-SPK=1.65+/-0.42 mm/sec). The solitary kidney transplant controls (post-K) showed no significant improvements in diabetic microangiopathy, confirming the unique role of the pancreas in SPK. In general, significant improvements (P<0.05) in diabetic microangiopathy were observed in all 12 diabetics 18 months post-SPK but not in the controls.

Background: Enhanced Kupffer cell production of the immunosuppressive arachidonic acid metabolite prostaglandin E2 (PGE2) has been shown to be a mechanism of the immunosuppressive effect of portal venous transfusions (PVT). Butyrate, a four-carbon short-chain fatty acid, has received increased attention because of its ability to enhance gene transcription. This study tested the hypothesis that the intrahepatic delivery of butyrate enhances Kupffer cell PGE2 production and thus augments the immunosuppressive effect of PVT., Methods: Butyrate was incorporated into liposomes and administered intravenously to Lewis rats. Control rats were administered liposomes without butyrate. Twenty-four hours after liposome injection, rats were administered a PVT of 1 ml of Wistar-Furth blood. Kupffer cells were isolated, and PGE2 and tumor necrosis factor-alpha levels were measured in the culture medium after 24 hr. Additionally, Kupffer cells from butyrate-treated and control animals were added to one-way mixed lymphocyte reaction cultures., Results: Intrahepatic delivery of butyrate via liposomes increased Kupffer cell PGE2 (3800+/-1220 vs. 1010+/-119 pg/ml, P<0.05) and decreased tumor necrosis factor-alpha (1670+/-81 vs. 3360+/-415 pg/ml, P<0.01) production as compared with controls. Butyrate also augmented the Kupffer cell-mediated immunosuppression as demonstrated by significant depression of the mixed lymphocyte reaction (690+/-119 vs. 3850+/-148 cpm, P<0.01)., Conclusion: The results support the hypothesis that intrahepatic delivery of butyrate enhances Kupffer cell PGE2 production, and specific targeting of Kupffer cells with liposomes containing immunomodulating agents such as butyrate may be a useful means of augmenting immunosuppression protocols in organ transplantation.

Portal venous transfusions (PVTs) of blood have been shown to induce significant immunosuppression in animal models of organ transplantation. A proposed mechanism of PVT-induced immunosuppression is via alteration of Kupffer cell arachidonic acid metabolism with increased secretion of the suppressive metabolite prostaglandin E2 (PGE2). This study assessed the hypothesis that PVT increases Kupffer cell PGE2 production via up-regulation of Kupffer cell phospholipase A2 (PLA2) as well as constitutive (COX1) and inducible (COX2) cyclooxygenase. Kupffer cells from Lewis rats were harvested 1 hr after PVT with either 1 ml of Wistar-Furth blood, systemic transfusion (SVT), or saline via portal vein (PVSal). After lipopolysaccharide stimulation, 24-hr Kupffer cell supernatant fractions were assayed for PGE2. PGE2 was increased after SVT (1465+/-234 pg/ml) compared with PVSal (597+/-99; P<0.01). PVT increased Kupffer cell PGE2 (5370+/-533; P<0.001 vs. SVT and vs. PVSal) even more substantially. Kupffer cells from PVT-treated rats were then cultured in the presence of inhibitors of PLA2, COX1, or COX2. When Kupffer cells were treated with mepacrine to inhibit PLA2 (5575+/-453 pg/ml), PGE2 production was not different from that by PVSal-treated controls (6467+/-614 pg/ml), but when Kupffer cells were incubated in the presence of the COX1 inhibitor flurbiprofen (3512+/-407 pg/ml) or the COX2 inhibitor nimesulide (2800+/-830 pg/ml), production was decreased 46.7% and 56.7%, respectively, over control activity without added inhibitor. PVT also increased Kupffer cells COX1 and COX2 mRNA as measured by Northern blot. Heart transplants were then performed from Wistar-Furth donors into Lewis recipients at the time of PVT, SVT, PVSal, or PVT + indomethacin (COX1/2 inhibitor). PVT prolonged allograft survival (12.0+/-0.9 days) compared with PVSal (6.3+/-0.3; P<0.01) or SVT (6.3+/-0.3; P<0.04). Indomethacin shortened graft survival when given with PVT (6.5+/-0.3 days). In summary, PVT increased Kupffer cell PGE2 production, up-regulated transcription of Kupffer cells COX1 and COX2 mRNA, and prolonged cardiac allograft survival. COX1/2 inhibition abrogated the effect of PVT. The results indicated that the immunosuppressive effect of PVT may be mediated by up-regulation of Kupffer cell COX1 and COX2. Manipulation of Kupffer cell arachidonic acid metabolism may be useful in augmentation of PVT-induced immunosuppression.

To further define the role of arachidonic acid (AA) metabolites in transfusion-induced immunosuppression (TII), the effects of pharmacological manipulation of AA metabolism were examined in a rodent model. If the prostaglandins of the E series are mediators of TII, as has been recently hypothesized, then inhibition of cyclooxygenase (indomethacin) should abrogate whereas inhibition of lipoxygenase (nordihydroguaiaretic acid [NDGA]), or thromboxane synthetase (4-63557A) could potentiate the transfusion effect. Lewis rats received donor-specific transfusions from Buffalo rats in conjunction with one of the above inhibitors. Two weeks later they received intraabdominal Buffalo heart allografts or were used for one-way mixed lymphocyte reactions. Cyclooxygenase inhibition partially abrogated TII with shortened cardiac allograft survival. Lipoxygenase inhibition augmented TII, with depression of MLR and prolongation of allograft survival. Thromboxane synthetase inhibition had no effect. These results indicate that AA metabolites play a role in TII, and that immunoregulation via pharmacological manipulation of AA metabolism is possible.

Dietary supplementation with fatty acids was carried out to examine whether the type and timing of dietary manipulation would have an effect on transfusion-induced immunosuppression in a rat cardiac transplant model. Linoleic acid (LA), oleic acid (OA), and fish oil (FO) were used because of their different effects on arachidonic acid (AA) metabolism. Pretransplant inhibition of AA metabolism (OA) shortened graft survival when compared with water-fed controls. Posttransplant LA (AA precursor) significantly prolonged graft survival. Pre- and posttransplant supplementation of LA and OA resulted in even more prolongation and shortening of graft survival, respectively. These findings suggest that transfusion-induced immunosuppression is partially mediated by AA metabolites, which are necessary for the pretransplant induction and posttransplant maintenance of the suppressed state. Dietary immunoregulation of transfusion induced immunosuppression is possible. The timing of dietary intervention and type of lipid supplementation is important in regulation of the immune response.

Increased prostaglandin production is a possible mechanism for the immunosuppressive effects of both cyclosporine and blood transfusions. Therefore, dietary supplementation with linoleic acid, a prostaglandin precursor, combined with either modality could act synergistically. Intraabdominal cardiac allografts were performed from Buffalo rat donors to Lewis recipients. Transplant recipients received a single donor-specific transfusion, low-dose cyclosporine (CsA, 1 mg/kd/d x 7 days), dietary supplementation with linoleic acid (LA, 16% of total calories) or a combination of the three modalities. CsA, DST or LA alone significantly prolonged allograft survival. Both CsA and LA acted synergistically with DST in further prolongation of survival--however, animals receiving all three modalities achieved 100% long-term survival. Augmentation of transfusion- and cyclosporine-induced immunosuppression with dietary prostaglandin precursor is possible.