Soluble intercellular adhesion molecule-1 (sICAM-1) after kidney transplantation: the origin and role of urinary sICAM-1?

BACKGROUND: Intercellular adhesion molecule-1 (ICAM-1) binds to leukocyte adhesion receptors LFA-1 and MAC-1, and mediates leukocyte adhesion to target structures. During acute rejection there is increased expression of ICAM-1 in vascular and tubulointestial cells, and consequently accumulation of inflammatory leukocytes. Soluble ICAM-1 (sICAM-1) is released from ICAM-1 expressing cells and excreted into the surrounding fluid. Increased serum sICAM-1 levels are found in patients with acute rejections of various allografts, and high urinary levels in steroid resistant acute kidney allograft rejection. METHODS: Urinary excretion of sICAM-1 was measured by EIA in 136 kidney allograft recipients during the first 1-6 post transplant weeks: 30 patients developed acute rejection, and 106 patients had stable graft function. The molecular weight, binding to hyaluronan, and the origin of urinary sICAM-1 were studied. RESULTS: We show that urinary sICAM-1 circulates as a monomer with a molecular weight between 50 and 100 kD. It binds to immobilized, but not to circulating hyaluronan. About one week after transplantation the mean sICAM-1/creatinine ratio (306 ng/mmol) in transplanted patients was higher than in the healthy controls (167 ng/mmol, P<0.01), and remained basically unchanged during the follow-up in patients with stable graft function, whereas it increased in patients developing rejection, being about 2.5-fold above the initial level a few days before rejection (P<0.01). Urinary sICAM-1 did not correlate with the urinary albumin, whereas in patients developing rejection it correlated with urinary IL-2R (r=0.5146, P<0.001), a marker of lymphocyte activation. In the urinary sediment of rejecting patients ICAM-1 was demonstrated in the tubular epithelial cells, and in the macrophages. CONCLUSIONS: Increased urinary excretion of sICAM-1 was demonstrated in kidney transplanted patients a few days before acute rejection. It seems to originate from activated macrophages and/or from the tubular epithelial cells. The fact that urinary sICAM-1 is not bound to hyaluronan or to leukocytes suggests that it is not able to compete with membrane-bound ICAM-1 for these bindings, but may do so for the binding of activated macrophages.     

Localization of C-X-C and C-C chemokines to renal tubular epithelial cells in human kidney transplants is not confined to acute cellular rejection

Chemokines are important mediators of leucocyte chemoattraction to inflammatory sites. Previous work has shown that the expression of some chemokines is upregulated during renal transplant rejection. The objectives of the present study were to determine whether chemokine expression is increased during renal transplant rejection. Immunohistochemistry was used to localize the C-X-C (alpha) chemokine interleukin-8 (IL-8) and the C-C (beta) chemokines monocyte chemoattractant protein-1 (MCP-1) and macrophage inflammatory protein-1beta (MIP-1beta) in 30 needle biopsies of human kidney transplants taken for diagnosis of renal dysfunction. Urine samples from transplant patients taken immediately prior to biopsy were assayed for chemokine content using enzyme-linked immunosorbent assays (ELISAs). Results from groups of patients having different clinicopathological diagnoses were then compared. All three chemokines were detected in most renal transplant biopsies showing acute cellular rejection but, although infiltrating leucocytes were often positive, staining was predominantly localized to renal tubular epithelium. Staining for MCP-1 was generally weaker than for the other chemokines, and collecting tubules were usually stained more strongly than proximal convoluted tubules. Tubular epithelial staining was also found in biopsies from patients without signs of acute cellular rejection. There were significantly higher amounts of IL-8 in the urine of patients with acute cellular rejection, even when patients with urinary tract infections were excluded, but mean titres of urinary MIP-1beta did not differ between patient groups. This was also found when titres were normalized for urine volume and creatinine levels. Production of IL-8, MCP-1 and MIP-1beta is not confined to kidney transplants showing acute cellular rejection, and may be a relatively nonspecific response of tubular epithelial cells to renal damage.     

Clinical graft evolution of lymphocytes, polymorphonuclear cells, and antigen expression in tubular renal cells in the urine sediment of 20 renal allograft recipients

Urinary samples from 20 kidney transplant recipients were studied to determine the cellular composition of the sediments using an immunocytological (IC) technique. The expression of HLA class I (A, B, C) and class II (DR, DQ, DP), CD2, CD3, CD4, CD8, and interleukin (IL)-2 receptor (IL-2R) on lymphocytes was assessed using a panel of monoclonal antibodies. The results were correlated with graft function and with the number of episodes of acute renal graft rejection (AR) during a period of 6 months posttransplantation. The cellular infiltration of lymphocytes (LC) and polymorphonuclear cells (PMNC) also was studied using a standard cytology (SC) technique. During this period, 17 of 30 episodes of graft dysfunction due to AR occurred in 12 patients: 8 to acute tubular necrosis (ATN) (n = 8); 4 to cyclosporine (CsA) toxicity (n = 4) and 1 to amphotericin toxicity (n = 1). The diagnosis of AR was made clinically by 3 independent observers, using biopsy in some cases. The immunocytology showed a significantly increased expression of HLA-DR, DO, and DP namely, greater than 20% positivity in 10% of samples on the tubular epithelial cells (TEC) of patients presenting with versus without AR (P < or =.001). In addition, a high correlation was observed between the expression of IL-2R and the presence of AR (p < or =.002). The standard cytology results showed a significantly increased percentage of LC and decreased percentage of PMNCs in samples obtained 2 days prior to the clinical manifestations of patients who developed AR (P =.001). A greater level of expression of antigen determinants was observed prior to AR. These results suggest that immunocytology of urinary sediments, which is a noninvasive technique, has enormous clinical potential for the differential diagnosis of AR, ATN, and CsA toxicity. In our study, the use of HLA class IL-specific monoclonal antibodies (Abs) gave a 100% specificity, 95% sensitivity, and 95% predictability. Although our results also indicate a potential value in the increased IL-2R expression, these findings must be confirmed by further studies. Furthermore, the combination of both immunologic and SC techniques in urinary sediments allows early detection of AR and is cost effective and simple features that could be used routinely for follow-up of renal transplant recipients.     

Intragraft mRNA expression of cytokines and growth factors in human kidney allograft biopsies by in situ RT-PCR analysis

The aim of our study was to correlate intragraft mRNA expression of cytokines and growth factors with histopathologic features in renal allograft biopsies. Fifty-six core biopsies performed in 51 kidney transplant recipients were assessed by the Banff '97 classification. Tubular and glomerular expressions of IFN-gamma, TGF-beta1, and PDGF-B as well as IL-2, IL-6, and IL-10 mRNA were assessed using semiquantitative RT-PCR in situ. No significant differences were noted between acute cellular and vascular rejection with regard to the glomerular and tubular mRNA expression of cytokines examined. We observed a positive correlation between tubular and glomerular IL-10 and IFN-gamma mRNAs during acute rejection. In chronic rejection the mRNA expression levels of IFN-gamma and IL-2, IL-6, and IL-10 did not differ from those of acute rejection; moreover, the glomerular expression of mRNA for TGF-beta1 (P < .05) and PDGF-B (P < .1) was even lower than during acute rejection episodes. Both tubular and glomerular IL-2, TGF-beta1, and PDGF-B mRNA expression levels in biopsies with acute rejection were significantly higher than in acute tubular necrosis (ATN). Biopsy samples with borderline changes exhibited the lowest levels of cytokine gene expression and were close to the intensity of control specimens obtained from living donor kidney biopsies taken during organ harvest. Our data failed to show a dichotomy between Th1 and Th2 cytokine activation in biopsy specimens from kidney allograft recipients; both Th1- and Th2-derived cytokines were involved to similar extents in rejection processes.     

白细胞介素6mRNA在移植肾中的表达及意义

目的 探讨肾移植急性排斥反应时白细胞介素6(IL-6)产生的主要来源,并为初步阐明肾移植急性排斥反应的分子学发病机制提供实验依据。方法 采用3＇IL-6寡核苷酸探针,运用原位杂交技术观察IL-6mRNA在移植肾中的表达。结果 (1)在急性排斥反应时,移植肾各部位表达IL-6mRNA明显增多,较环孢素A(CsA)中毒、稳定期移植肾及正常人均有显著升高。(2)在急性排斥反应时,肾小管上皮细胞表达IL-6mRNA强度较肾小球细胞、血管内皮细胞及间质细胞均有明显升高。(3)CsA中毒患者肾脏IL-6mRNA表达较稳定期移植肾及正常对照无明显增多。结论 肾移植急性排斥反应时,移植肾细胞可直接产生IL-6,移植肾中IL-6异常激活与表达同肾移植急性排斥反应的发生机制有密切的关系;肾小管表达IL-6的异常增多和活化揭示了肾小管上皮细胞在肾移植急性排斥反应的发病机理中具有重要意义。     

Urinary excretion of proteins and tubular enzymes in renal transplant patients

The aim of this study was to evaluate, in renal transplant recipients with different function of the graft, the urinary excretion of some low molecular weight proteins and tubular enzymes frequently employed as indicators of tubular dysfunction.

Urinary excretion of proteins and enzymes was measured in 51 renal transplant patients and, for comparison, in 73 patients affected by different kidney diseases with various degrees of renal function.

Values of urinary β2-microglobulin and retinol-binding protein higher than normal were found in most transplanted patients, even in those with good renal function. On the other hand, in renal patients the urinary excretion of low molecular weight proteins was high only when creatinine clearance was lower than 30 mL/min/1.73 m². Furthermore, an increased urinary excretion of tubular enzymes was found in a higher number of transplanted patients than of renal patients. This behavior was particularly evident for lysosomal enzyme N-acetyl-β-D-glucosaminidase.

In conclusion, a tubular dysfunction occurs in the transplanted kidneys, even in those with well preserved glomerular function.     

Relationship of HLA-DR expression to rejection and mononuclear cell infiltration in renal allograft biopsies

Research on renal biopsies has shown that HLA class I antigens are distributed throughout the renal parenchyma, but that the distribution of HLA-DR varies greatly. We investigated HLA-DR expression in biopsies of 90 renal transplants, and also semiquantitatively assessed the proportions of CD68-, CD3-, and HLA-DR-positive infiltrating cells by immunohistochemistry. The relationships between tubular DR expression and interstitial lymphocyte and macrophage infiltration were examined. Forty of the biopsies showed acute rejection (AR), 33 showed chronic rejection (CR), 10 showed suspected rejection (SR), and 7 showed no evidence of rejection (NR). HLA-DR expression was noted in 35/40 (87.5%) of the AR cases, 22/33 (66.6%) of the CR cases, and 6/10 (60%) of the SR cases. Only 1 (14.3%) of the NR cases exhibited HLA-DR antigen expression in the renal tubules. The proportions of lymphocyte and macrophage infiltration observed in the interstitium were significantly correlated with tubular DR expression in all cases (p<0.01). At 6 months after biopsy was done, 24/35 (68.6%) of the AR patients with tubular DR expression had showed second episode of rejection or showed deteriorated renal function. The remaining 11 AR cases with tubular DR expression had stable renal function at this stage. The cases that had no significant tubular DR expression had no problems with rejection or functional deterioration. These findings are consistent with the theory that expression of HLA-DR antigens on renal tubular cells may be a marker of rejection and poor graft outcome.     

TGF-beta1 expression in renal allograft rejection and cyclosporine A toxicity

BACKGROUND: To assess short- and long-term influence of the TGF-beta1 on renal allografts. METHODS: Expression of TGF-beta1 and TNF-alpha, and the proportion of macrophages and eosinophils in interstitium were evaluated in 64 cases including five cases with nonrejected kidneys (NRK), 18 cases with acute rejection (AR), 26 cases with chronic allograft nephropathy (CAN), and 15 cases with acute cyclosporine A (CsA) toxicity. Follow-up biopsies of all cases with AR and CsA toxicity were evaluated for development of interstitial fibrosis (IF) and graft atherosclerosis (GAS). Additionally, influence of tubular-TGF-beta1 expression on graft function during 6 months after the diagnostic biopsy was evaluated. RESULTS: A significant differences was seen between rejected kidneys and acute CsA toxicity in regards of tubular TGF-beta1 expression that patients with CsA toxicity exhibited significantly higher grade of tubular TGF-beta1 expression than patients with AR (P<0.05) and CAN (P<0.05). A significant difference was found between the grades of tubular TGF-beta1 expression in regards to graft function of cases with AR and CsA toxicity (P<0.05). Higher grade tubular TGF-beta1 expression showed better graft function during 6 months. Besides the degree of renal TGF-beta1 expression was positively correlated with development of diffuse IF and GAS (P<0.05) that the risk of the IF and GAS was higher in cases with grade 2 renal TGF-beta1 expression. CONCLUSIONS: Despite the short-term posttransplantation tubule-repairing effects of TGF-beta1, the overall effects of TGF-beta1 in the kidney seem to be negative that increased expression of TGF-beta1 promotes IF and vasculopathy associated with CAN.     

Interleukin-6 and neopterin in renal transplant recipients: a longitudinal study

Serum and urine interleukin-6 (IL-6) levels and serum neopterin/creatinine ratios were longitudinally studied in 86 renal transplant recipients until 4 months after transplantation. During acute rejection and acute tubular necrosis (ATN), serum and urine IL-6 levels were elevated compared to during stable transplant function (P<0.001). During acute rejection, serum IL-6 levels increased at least 2 days before plasma creatinine started to rise (P<0.05), indicating its early involvement in the rejection process. During cytomegalovirus (CMV) disease, serum, but not urine, IL-6 levels were higher (P<0.01), and serum neopterin/creatinine values were higher than during stable transplant function, ATN, or acute rejection (P<0.01). No significant differences with stable transplant function occurred during cyclosporin A toxicity. Measurement of serum IL-6 provided a sensitivity of 84% and a specificity of 85% for the diagnosis of acute rejection episodes not coinciding with ATN. All cases of CMV disease could be diagnosed by measurement of serum neopterin/creatinine, which provided a specificity of 73%.     

Urinary Transforming Growth Factor-β1 Excretion in Renal Allograft Recipients During the Early Post-transplantation Period

Background.?Transforming growth factor-β₁ (TGF-β₁), the major fibrogenic growth factor, is implicated in the pathogenesis of renal scarring in experimental and clinical nephropathies as well as in chronic allograft nephropathy. In this study we examined the pattern of changes of TGF-β₁ excretion in the urine and the sites of TGF-β₁ expression in the kidney of transplanted patients during the early post-transplantation period. Methods.?Eighteen renal allograft recipients were included in the study. In all patients urinary TGF-β₁ levels were determined by ELISA in sequential measurements during the first two postoperative months and compared to that of 14 healthy subjects. The renal expression of TGF-β₁ protein was studied in 4 patients that underwent a biopsy of the transplanted kidney at the same period. All patients were treated with prednisolone, cyclosporin, and mycophenolate mofetil. Results.?Urinary TGF-β₁ levels were increased during the first postoperative days. Although they were gradually reduced during the first two post-operative months, they remained significantly higher compared to those of normal subjects (580 ± 148 ng/24 h vs. 310 ± 140 ng/24 h p<0.01). The decline of urinary TGF-β₁ excretion followed that of serum creatinine. TGF-β₁ protein expression was identified within the cytoplasm of tubular epithelial cells of transplanted patients. Conclusions.?Elevated urinary TGF-β₁ levels are observed during the early post-transplantation period in renal allograft recipients and are maintained high even after restoration of renal function to normal.     

Effects of everolimus on cellular and humoral immune processes leading to chronic allograft nephropathy in a rat model with sensitized recipients

BACKGROUND: Chronic allograft nephropathy (CAN) remains the most common cause of late graft loss especially in sensitized patients. The aim of this study is to evaluate the therapeutic effect of everolimus on cellular and humoral mechanisms of chronic allograft damage in a rat model with sensitized recipients. METHODS: F344 kidneys were transplanted to LEW.RNU rats. The athymic recipients were reconstituted with 3.5 x 10(7) or 5 x 10(7) presensitized CD4+T-lymphocytes. In the treatment group, everolimus was introduced five weeks posttransplantation. Rats were monitored for peripheral blood lymphocytes, renal function, histological changes in the graft, and the development of donor-specific alloantibodies. RESULTS: Rats developed cell dose-dependent renal failure. Increased urinary albumin excretion and glomerulopathy were frequently accompanied by the development of donor-specific major histocompatibility complex (MHC) alloantibodies. In the everolimus group, five of six animals survived for 20 weeks with stable serum creatinine and displayed neither acute cellular rejection nor CAN. Prolonged survival was accompanied with significantly reduced tubulointerstitial cell infiltrate in the graft. Increased urinary albumin excretion was present in all, acute tubular necrosis in five of six, and glomerular sclerosis in two grafts. MHC alloantibodies were found in four of six animals. CONCLUSION: The used rat model offers the opportunity to study the influence of everolimus on the interaction of humoral and cellular mechanisms involved in chronic renal damage. Everolimus leads to a prolongation of allograft survival, reduced cell infiltrate in the graft, and prevents tubular atrophy and interstitial fibrosis. The development of alloantibodies and albuminuria was not prevented. These data suggest that although cellular rejection is clearly suppressed, humoral mechanisms of CAN cannot be completely controlled by everolimus treatment in the sensitized rat model.     

Fractional excretion of sodium after renal transplantation.

After renal transplantation low urinary sodium concentration (UNa) has been used to diagnose acute rejection (AR), for the early phase of AR is often associated with reduced renal perfusion. Early postoperative graft failure without low UNa favors the diagnosis of ischemic tubular damage (ATN). As fractional excretion of filtered sodium (FENa) better reflects glomerulotubular balance in renal sodium handling, FENa was analyzed during the first 2 weeks in 118 renal allografts. From data on 41 transplants with good early renal function (GEF), a temporal profile of FENa was obtained and used to evaluate the behavior of FENa by means of standardized FENa (Z score). Individual subjects followed their own profile with a small deviation (delta Z less than 1.4 for 2 days). In 31 instances, acute rejection was diagnosed. In 14 with AR, the Z score deviated little; 2 responded to methylprednisolone given intravenously. In 17 with AR, the Z score fell significantly (delta Z greater than 1.5 for 2 days), an average of 2.6 days before the first rise in serum creatinine concentration; 15 responded to treatment. The difference between these two groups was significant (P less than 0.001). This functional heterogeneity and different responses to treatment may indicate different immunologic mechanisms which damage different target cells in the graft in AR. In 46 patients with acute tubular necrosis after cadaver kidney transplantation FENa was significantly higher than it was in the GEF group as early as the first posttransplantation day and approached normal as the renal function recovered. This behavior of FENa was clearly different from that in AR.     

CXCR3 and CCR5 positive T-cell recruitment in acute human renal allograft rejection

BACKGROUND: Experimental studies suggest that the infiltration of activated T cells into the allograft, the key event in the development of acute renal allograft rejection, depends on the expression of chemokines and their interaction with chemokine receptors expressed on T cells. METHODS: For a more detailed comprehension of the pathogenesis of T-cell recruitment in human acute rejection, the in situ expression of chemokines and chemokine receptors in allografts of 26 patients between day 3 and 9 after renal transplantation was examined in the present prospective study. RESULTS: Immunohistochemical staining showed a significantly increased number of CXCR3 (P<0.01) and CCR5 positive T cells (P<0.01) in the tubulointerstitium of patients with acute allograft rejection according to Banff grade Ia-IIb. Likewise the intrarenal RNA expression of the CXCR3 ligands IP-10 (5.2-fold) and I-TAC (7.2-fold) and the CCR5 ligand RANTES (5.7-fold), was significantly up-regulated in rejecting organs. In situ hybridization revealed that IP-10 but not I-TAC was predominantly expressed by infiltrating leukocytes in the tubulointerstitial area, co-localizing with CXCR3 positive T cells. To a lesser degree expression by tubular cells could be detected, providing a possible explanation for the increased urinary IP-10 excretion we found in patients with rejecting organs. CONCLUSIONS: These data from a prospective, biopsy-controlled study indicate that the local expression of IP-10 and RANTES leads to the directional movement of activated CXCR3 and CCR5 bearing T cells into the renal allograft and mediates acute rejection. Our data provide a rationale that blocking CXCR3 and CCR5 may offer a unique therapeutic approach to prevent episodes of acute rejection in the early phase after renal transplantation.     

Surveillance of acute rejection in baboon renal transplantation by elevation of interferon-gamma inducible protein-10 and monokine induced by interferon-gamma in urine

BACKGROUND: CXCR3 binding chemokines play a key role in recruitment of inflammatory cells into an organ transplant. This study addresses the question of whether urinary excretion of these chemokines correlates with acute rejection in a baboon kidney transplantation model. METHODS: Seven outbred baboons underwent renal allotransplantation from major histocompatibility complex (MHC)-mismatched donors. The treatment of baboons consisted of anti-CD4 monoclonal antibody (mAb), anti-CD8 mAb, rapamycin, and mycophenolate mofetil (MMF). Urinary levels of interferon-gamma inducible protein-10 (IP-10) and monokine induced by interferon-gamma (Mig) were determined by ELISA. Renal biopsies were examined by immunohistochemical staining for CXCR3 and Mig. RESULTS: Urinary levels of IP-10 and Mig increased significantly in all of the five baboons at the time of acute rejection of renal transplant. The IP-10 and Mig levels did not rise in two nonrejecting baboons. In two baboons, urinary levels of IP-10 and Mig rose before the elevation of the serum creatinine. In renal biopsies, expression of Mig was detected in glomeruli, tubules, and infiltrating cells, and the expression was significantly elevated in biopsies with acute rejection (P<0.01). CXCR3 was constitutively expressed in tubular cells in biopsies derived from both normal grafts and grafts with acute rejection. Whereas the infiltrating cells were increased in the biopsies with acute rejection, the expression of CXCR3 was also significantly higher (P<0.01) in these infiltrating cells compared with those in the normal controls. CONCLUSIONS: This study shows an important correlation between urinary excretion of IP-10 and Mig and acute rejection in baboon kidney transplantation.     

Expression of MHC class I-related Chain B (MICB) molecules on renal transplant biopsies

BACKGROUND: MICA and MICB (MHC class I-related chain A and B) are polymorphic genes that encode molecules related to MHC class I and are expressed on epithelial cells in response to stress. Incompatible donor MIC antigens can stimulate antibody production in transplant recipients. This study was designed to determine MICB expression in kidney pretransplant and any subsequent changes in expression following transplantation and to correlate changes with inflammatory markers and clinical events. METHODS: Paired renal biopsies obtained from living donor (n=10) and cadaveric allografts (n=50) before and 7 days posttransplant were stained for MICB, leukocytic infiltration, and HLA class II antigens. RESULTS: Variable tubular MICB expression was evident in donor biopsies [high 6/60 (10%), low/negative 13/60 (22%), intermediate 41/60 (68%)]. Following transplantation, MICB was up-regulated on renal tubules of 17/60 (28%) biopsies and was associated with MHC class II antigen induction (P=0.02) and leukocyte infiltration (P=0.01). Acute tubular necrosis leading to delayed graft function (DGF) and acute rejection (AR) cause cellular stress within the transplanted kidney. We found a strong association between up-regulation of MICB and cellular stress, 15/17 biopsies with up-regulated MICB expression had AR and/or DGF (P=0.003). CONCLUSIONS: This is the first study demonstrating variable levels of MICB expression in kidneys before transplantation and induction of MICB expression following renal transplantation. MICB expression is associated with HLA class II antigen induction, leukocytic infiltration of the graft and cellular stress in the transplanted kidney. Expression of MICB could contribute significantly to the alloimmune response in mismatched donors and recipients.     

肾移植前后表皮生长因子含量研究

为了探讨细胞生长调节因子之一的表皮生长因子（ＥＧＦ）在肾脏损害修复中的作用及ＥＧＦ与肾功能及缺血性肾损伤修复之间的关系，观察了１３８例慢性肾功能衰竭（尿毒症期）患者血ＥＧＦ含量和肾移植术前后血和尿中ＥＧＦ含量。结果显示，肾功能衰竭、肾脏损伤期血ＥＧＦ水平极低，移植后肾功能恢复早期，血ＥＧＦ即明显回升。恢复后期，血ＥＧＦ水平稍降，但仍比移植前增高。血ＥＧＦ含量持续不升高者与急性排斥反应和急性肾小管坏死的发生有关。ＥＧＦ的存在，在肾损伤修复时具有重要的作用。检测血清ＥＧＦ含量可作为判断移植肾损伤修复状态的指标之一。     

Interleukin-6 expression after renal transplantation

BACKGROUND: Interleukin-6 (IL-6) is an inflammatory cytokine that plays a role in transplant rejection. We tested the hypothesis that IL-6 levels in serum or urine could be of value in predicting acute and chronic allograft rejection. Furthermore, we examined whether or not such levels reflected IL-6 expression in the kidney. METHODS: We measured IL-6 and IL-6 soluble receptor (IL-6sR) in serum and urine of 145 transplant patients and 20 normal controls. In parallel, we studied 108 renal biopsies. IL-6 was measured with a bioassay system using an IL-6 dependent cell line. IL-6sR was measured with enzyme-linked immunosorbent assay. The biopsies were examined for IL-6 and IL-6 receptor (IL-6R) expression with immunohistochemistry. RESULTS: Rejection episodes occurring within 2 months of transplantation were accompanied by elevated IL-6 concentrations in serum (17 +/- 4.8 pg/ml, P < 0.05) and urine (114 +/- 27 pg/ml, P < 0.005), compared to controls. These values returned towards baseline (0-5 pg/ml) after successful rejection treatment. The sensitivity of urine measurements was much higher (93%) than serum (54%). The specificity in serum (70%) and urine (60%) was reduced by infection, acute tubular necrosis, and antithymocyte globulin treatment. Serum and urine IL-6sR values did not correlate with rejection. In biopsy tissue, IL-6 and IL-6R were both elevated during rejection. Especially, mononuclear cells within the interstitial infiltrate stained positive. However, the amount of IL-6 positive cells did not correlate with peripheral IL-6 concentrations. CONCLUSIONS: Urine but not serum IL-6 values are sensitive indicators of rejection; however, they are confounded by infection, acute tubular necrosis, and certain antirejection treatments. These features limit their usefulness.      

Increased Urinary Excretion of Monocyte Chemoattractant Protein-1 in Proteinuric Renal Diseases

Monocyte chemoattractant protein-1 (MCP-1) is a chemokine that is produced mainly by tubular epithelial cells in kidney and contributes to renal interstitial inflammation and fibrosis. More recently, we have demonstrated that urinary MCP-1 excretion is increased in proportion to the degree of albuminuria (proteinuria) and positively correlated with urinary N-acetylglucosaminidase (NAG) levels in type 2 diabetic patients. Based on these findings, we have suggested that heavy proteinuria, itself, probably aggravates renal tubular damage and accelerates the disease progression in diabetic nephropathy by increasing the MCP-1 expression in renal tubuli. In the present study, to evaluate whether urinary MCP-1 excretion is increased in the proteinuric states not only in diabetic nephropathy but also in other renal diseases, we examined urinary MCP-1 levels in IgA nephropathy patients with macroalbuminuria (IgAN group; n = 6), and compared the results with the data obtained from type 2 diabetic patients with overt diabetic nephropathy (DN group; n = 23) and those without diabetic nephropathy (non-DN group; n = 27). Urinary MCP-1 excretion levels in non-DN, DN, IgAN groups were 157.2 (52.8–378.5), 346.1 (147.0–1276.7), and 274.4 (162.2–994.5) ng/g creatinine, median (range), respectively. Expectedly, urinary MCP-1 and NAG excretion levels in DN and IgAN groups were significantly elevated as compared with non-DN group. Therefore, we suggest that MCP-1 expression in renal tubuli is enhanced in proteinuric states, irrespective of the types of renal disease, and that increased MCP-1 expression probably contributes to renal tubular damage in proteinuric states.