Human Renal Allograft Rejection Research Articles

Properdin produced by dendritic cells contributes to the activation of T cells

The complement system does not only play an important role in the defence against microorganism and pathogens, but also contributes to the regulation of innate and adaptive immunity. Especially activation fragments C3a and C5a and complement activation at the interface of antigen presenting cell (APC) and T cell, were shown to have a role in T cell activation and proliferation. Whereas most complement factors are produced by the liver, properdin, a positive regulator of the C3 convertase, is mainly produced by myeloid cells. Here we show that properdin can be detected in myeloid cell infiltrate during human renal allograft rejection. In vitro, properdin is produced and secreted by human immature dendritic cells (iDCs), which is further increased by CD40-L-matured DCs (mDCs). Transfection with a specific properdin siRNA reduced properdin secretion by iDCs and mDCs, without affecting the expression of co-stimulatory markers CD80 and CD86. Co-culture of properdin siRNA-transfected iDCs and mDCs with human allogeneic T cells resulted in reduced T cell proliferation, especially under lower DC-T cell ratio’s (1:30 and 1:90 ratio). In addition, T cell cytokines were altered, including a reduced TNF-α and IL-17 secretion by T cells co-cultured with properdin siRNA-transfected iDCs. Taken together, these results indicate a local role for properdin during the interaction of DCs and allogeneic T cells, contributing to the shaping of T cell proliferation and activation.

Signaling through tumor necrosis receptor 2 induces stem cell marker in CD133+ regenerating tubular epithelial cells in acute cell-mediated rejection of human renal allografts.

Tumor necrosis factor receptor 2 (TNFR2) is strongly upregulated on renal tubular epithelial cells by acute cell-mediated rejection (ACR. In human kidney organ culture, TNFR2 signaling both upregulates TNFR2 expression and promotes cell cycle entry of tubular epithelial cells. We find significantly more cells express CD133 mRNA and protein, a putative stem cell marker, in allograft biopsy samples with ACR compared to acute tubular injury without rejection or pretransplant "normal kidney" biopsy samples. Of CD133+ cells, ~85% are within injured tubules and ~15% are interstitial. Both populations express stem cell marker TRA-1-60 and TNFR2, but only tubular CD133+ cells express proximal tubular markers megalin and aquaporin-1. TNFR2+ CD133+ cells in tubules express proliferation marker phospho-histone H3S10 (pH3S10 ). Tubular epithelial cells in normal kidney organ cultures respond to TNFR2 signaling by expressing CD133 mRNA and protein, stem cell marker TRA-1-60, and pH3S10 within 3hours of treatment. This rapid response time suggests that CD133+ cells in regenerating tubules of kidneys undergoing ACR represent proliferating tubular epithelial cells with TNFR2-induced stem cell markers rather than expansion of resident stem cells. Infiltrating host mononuclear cells are a likely source of TNF as these changes are absent in acute tubular injury .

Macrophage-to-Myofibroblast Transition Contributes to Interstitial Fibrosis in Chronic Renal Allograft Injury.

Interstitial fibrosis is an important contributor to graft loss in chronic renal allograft injury. Inflammatory macrophages are associated with fibrosis in renal allografts, but how these cells contribute to this damaging response is not clearly understood. Here, we investigated the role of macrophage-to-myofibroblast transition in interstitial fibrosis in human and experimental chronic renal allograft injury. In biopsy specimens from patients with active chronic allograft rejection, we identified cells undergoing macrophage-to-myofibroblast transition by the coexpression of macrophage (CD68) and myofibroblast (α-smooth muscle actin [α-SMA]) markers. CD68+/α-SMA+ cells accounted for approximately 50% of the myofibroblast population, and the number of these cells correlated with allograft function and the severity of interstitial fibrosis. Similarly, in C57BL/6J mice with a BALB/c renal allograft, cells coexpressing macrophage markers (CD68 or F4/80) and α-SMA composed a significant population in the interstitium of allografts undergoing chronic rejection. Fate-mapping in Lyz2-Cre/Rosa26-Tomato mice showed that approximately half of α-SMA+ myofibroblasts in renal allografts originated from recipient bone marrow-derived macrophages. Knockout of Smad3 protected against interstitial fibrosis in renal allografts and substantially reduced the number of macrophage-to-myofibroblast transition cells. Furthermore, the majority of macrophage-to-myofibroblast transition cells in human and experimental renal allograft rejection coexpressed the M2-type macrophage marker CD206, and this expression was considerably reduced in Smad3-knockout recipients. In conclusion, our studies indicate that macrophage-to-myofibroblast transition contributes to interstitial fibrosis in chronic renal allograft injury. Moreover, the transition of bone marrow-derived M2-type macrophages to myofibroblasts in the renal allograft is regulated via a Smad3-dependent mechanism.

Currently available useful immunohistochemical markers of renal pathology for the diagnosis of renal allograft rejection.

Renal allograft dysfunction may be induced by various causes, including alloimmune rejection, viral infection, urinary tract obstruction, calcineurin inhibitor nephrotoxicity and/or recurrent renal disease. In order to determine the underlying cause, a renal biopsy is performed and the renal transplant pathology is diagnosed using the internationally consensus Banff classification. Although a progressive understanding of allograft rejection has provided numerous immunohistochemical markers, only the C4d is regarded to be a sufficiently useful marker for antibody-mediated allograft rejection according to the Banff classification. This review summarizes currently available useful immunohistochemical markers of renal transplant pathology, including C4d, with diagnostic implications for human renal allograft rejection. In particular, we discuss immunohistochemical markers in the following three categories: immunohistochemical markers of renal pathology used to (i) analyze the mechanisms of alloimmune rejection, (ii) monitor cell injury and/or inflammation associated with rejection and (iii) identify renal components in order to improve the diagnosis of rejection. In addition, recent progress in the field of renal transplant pathology includes the development of a new method for assessing molecular pathology using OMICS analyses. As the recent findings of various studies in patients undergoing renal transplantation are very encouraging, novel immunohistochemical markers must be also developed and combined with new technologies for the diagnosis of human renal allograft rejection.

MiRNA Profiling Discriminates Types of Rejection and Injury in Human Renal Allografts

Increasing evidence accumulates on the central involvement of microRNAs (miRNAs) in disease pathophysiology. We identified distinctly deregulated miRNAs in human renal allograft biopsies from patients undergoing acute cellular rejection, antibody-mediated rejection (ABMR), and delayed graft function (DGF). Sixty-five posttransplantation kidney biopsy samples covering 41 cases with acute rejection (15 vascular rejection, 15 interstitial rejection, and 11 ABMR), 14 DGF cases, and 10 protocol biopsies serving as controls were analyzed using the Affymetrix GeneChip miRNA Array. Differentially regulated miRNAs were identified by Student's t test and Bonferroni correction. Target genes for the set of miRNAs were retrieved from miRTarBase (experimentally verified targets) as well as by applying the target prediction routines DIANAmT, miRanda, and Targetscan. Patients with acute cellular rejection, ABMR, and DGF discriminate from the control group (protocol biopsies) in unsupervised clustering of miRNA profiles, clearly identifying deregulated miRNAs in rejection and DGF. Angiogenesis, apoptosis, and transforming growth factor-β signaling were identified as relevant pathways in ischemic response following an integrative analysis of miRNA targets and mRNA expression profiles. Inflammation by chemokine and cytokine signaling, T-cell activation, and B-cell activation were identified as relevant in acute rejection accordingly. These data suggest that distinct miRNA signatures playing a role in specific biological pathways discriminate acute cellular and humoral rejection and DGF. This finding serves as valuable tool for a rational selection of diagnostic, prognostic, and potentially therapeutic molecular targets of posttransplantation events.

MiRNA Profiling Discriminates Types of Rejection and Injury in Human Renal Allografts

miRNA Profiling Discriminates Types of Rejection and Injury in Human Renal Allografts

High Frequency of CCR5 and CCR2 Expressing T Cells and Its Association with Acute Renal Allograft Rejection

Introduction: Acute cellular rejection (ACR) of human renal allografts is a frequent serious post transplantation complication; occurring in up to 50% of renal transplant recipients. Leukocyte recruitment is a central feature of acute allograft rejection. The receptors for chemokines are expressed on leukocytes in a cell type specific manner. Recently it was observed that CCR5+ and CXCR3+ cells were found in allograft biopsies of patients with ACR. Here we investigated the expression of Th1 (CCR5, CXCR3 and CCR2) and Th2 (CCR4, CCR3 and CCR8) associated chemokine receptor on CD4 and CD8 T cell population. Aim: to correlate chemokine receptor expression in peripheral blood T cell subset in patients with ACR (biopsy proven rejections). Methods: Venous blood was collected for fluorescence-activated cell sorter (FACS) analysis at the time of graft rejection (ACR; n=10) (8 men, 2 women; mean age, 29 years; age range, 18-48 years) and well functioning grafts (WFG) (n=21) (20 men, 1 women; mean age, 30 years; age range, 18-48 years) FACS analysis was performed using a FACS calibur flow cytometer and antibodies conjugated with the fluorochromes fluorescein isothiocyanate (FITC), phycoerythrin (PE), Cy5PE as follows: CD4-Cy5PE, CD8- Cy5PE, CXCR3-PE Subsequent gating and analyses were performed using FLOW-JO software. Results: Frequency and expression of chemokine receptors in biopsy proven ACR (n=10) with that of WFG (n=21), frequency of CCR5+ (CD4; 11.08 % vs. 4.37 %; P=0.04), CD8; 27.6% vs. 13.6 %; P=0.02)] and CCR2+ [CD4; 1.23% vs. 0.27%; P=0.0002), CD8; 1.26% vs. 0.22% (P=0.004)] was high in ACR cases. We found high frequency of CCR3 only in the CD8 (0.46% vs. 0.94%; P=0.02) compartment of patients with ACR. Expression of chemokine receptors, analyzed by median fluorescent intensities (MFI), were in coherence with data for chemokine receptor frequency in T cells. MFI of CD4+CCR5+ (270 [202-421] Vs 207 [188-251] P=0.04) and CCR2+ (292[219-577]-161[143-240]) was found to be significantly high in ACR cases in comparison to WFG. Similarly CD8+ CCR5+ (P=0.04)], and CCR2 (193[164-334] vs 169[152-206]) were found to be significantly high in ACR cases. Among Th2 chemokine receptors there was no significant difference in the MFIs of chemokine receptors in ACR and WFG. Conclusion: CCR5 and CCR2 are the major Th1 associated chemokine receptors found to have high expression as well as in frequency during ACR. They seem to play a major role in the T cell mediated renal allograft rejection. However, high CCR3+ CD4 and CD8 T cells ACR (CD8+ only) indicates towards a possible role of this Th2 associated chemokine receptor in balancing the pro and anti-inflammatory T cell function. Thus we propose an important role of both CCR5 and CCR2 in T cell recruitment in the renal allograft during ACR and these receptors are possibly an important point of intervention for development of new therapeutic modalities as well as non interventional prognostic assay for monitoring allograft function.

High Frequency of CCR5 and CCR2 Expressing T Cells and Its Association with Acute Renal Allograft Rejection

Introduction: Acute cellular rejection (ACR) of human renal allografts is a frequent serious post transplantation complication; occurring in up to 50% of renal transplant recipients. Leukocyte recruitment is a central feature of acute allograft rejection. The receptors for chemokines are expressed on leukocytes in a cell type specific manner. Recently it was observed that CCR5+ and CXCR3+ cells were found in allograft biopsies of patients with ACR. Here we investigated the expression of Th1 (CCR5, CXCR3 and CCR2) and Th2 (CCR4, CCR3 and CCR8) associated chemokine receptor on CD4 and CD8 T cell population. Aim: to correlate chemokine receptor expression in peripheral blood T cell subset in patients with ACR (biopsy proven rejections). Methods: Venous blood was collected for fluorescence-activated cell sorter (FACS) analysis at the time of graft rejection (ACR; n=10) (8 men, 2 women; mean age, 29 years; age range, 18-48 years) and well functioning grafts (WFG) (n=21) (20 men, 1 women; mean age, 30 years; age range, 18-48 years) FACS analysis was performed using a FACS calibur flow cytometer and antibodies conjugated with the fluorochromes fluorescein isothiocyanate (FITC), phycoerythrin (PE), Cy5PE as follows: CD4-Cy5PE, CD8- Cy5PE, CXCR3-PE Subsequent gating and analyses were performed using FLOW-JO software. Results: Frequency and expression of chemokine receptors in biopsy proven ACR (n=10) with that of WFG (n=21), frequency of CCR5+ (CD4; 11.08 % vs. 4.37 %; P=0.04), CD8; 27.6% vs. 13.6 %; P=0.02)] and CCR2+ [CD4; 1.23% vs. 0.27%; P=0.0002), CD8; 1.26% vs. 0.22% (P=0.004)] was high in ACR cases. We found high frequency of CCR3 only in the CD8 (0.46% vs. 0.94%; P=0.02) compartment of patients with ACR. Expression of chemokine receptors, analyzed by median fluorescent intensities (MFI), were in coherence with data for chemokine receptor frequency in T cells. MFI of CD4+CCR5+ (270 [202-421] Vs 207 [188-251] P=0.04) and CCR2+ (292[219-577]-161[143-240]) was found to be significantly high in ACR cases in comparison to WFG. Similarly CD8+ CCR5+ (P=0.04)], and CCR2 (193[164-334] vs 169[152-206]) were found to be significantly high in ACR cases. Among Th2 chemokine receptors there was no significant difference in the MFIs of chemokine receptors in ACR and WFG. Conclusion: CCR5 and CCR2 are the major Th1 associated chemokine receptors found to have high expression as well as in frequency during ACR. They seem to play a major role in the T cell mediated renal allograft rejection. However, high CCR3+ CD4 and CD8 T cells ACR (CD8+ only) indicates towards a possible role of this Th2 associated chemokine receptor in balancing the pro and anti-inflammatory T cell function. Thus we propose an important role of both CCR5 and CCR2 in T cell recruitment in the renal allograft during ACR and these receptors are possibly an important point of intervention for development of new therapeutic modalities as well as non interventional prognostic assay for monitoring allograft function.

Retraction

The Journal of PathologyVolume 228, Issue 2 p. 260-260 RetractionFree Access Retraction This article retracts the following: Retracted: Evidence for the early involvement of interleukin 17 in human and experimental renal allograft rejection Che-Chuan Loong, Hsian-Guey Hsieh, Wing-Yiu Lui, Ann Chen, Ching-Yuang Lin, Volume 197Issue 3The Journal of Pathology pages: 322-332 First Published online: April 16, 2002 First published: 10 September 2012 https://doi.org/10.1002/path.4079Citations: 1AboutSectionsPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat The following article from The Journal of Pathology, “Evidence for the early involvement of interleukin 17 in human and experimental renal allograft rejection”, by C. C. Loong, H. G. Hsieh, W. Y. Lui, A. Chen and C. Y. Lin [1], published online on 16th April 2002 on Wiley Online Library (http://onlinelibrary.wiley.com/doi/10.1002/path.1117/abstract) and in Volume 197, Issue 3, pages 322–332, July 2002, has been retracted by agreement between the authors, the journal Editor, and John Wiley & Sons Ltd. The retraction has been agreed owing to a substantial overlap between the content of this article and an article by the same authors entitled “IL-17 expression as a possible predictive parameter for subclinical renal allograft rejection”, previously published in Transplant International, Volume 14, Issue 5, pages 287–298, September 2001. References 1Loong C-C, Hsieh H-G, Lui W-Y, Chen A, Lin C-Y. Evidence for the early involvement of interleukin 17 in human and experimental renal allograft rejection. J Pathol 2002; 197: 322– 332. Wiley Online LibraryCASPubMedWeb of Science®Google Scholar Citing Literature Volume228, Issue2October 2012Pages 260-260 ReferencesRelatedInformation

Frequency of T Cell Expressing Th1 and Th2 Associated Chemokine Receptor in Patients With Renal Allograft Dysfunction

Acute rejection of human renal allografts is a frequent, serious posttransplantation complication, occurring in up to 50% of recipients. Leukocyte recruitment is a central feature of acute allograft rejection. Chemokine receptors are expressed on leukocytes in a cell type–specific manner. Recently CCR5+ and CXCR3+ cells have been observed in allograft biopsy specimens of patients undergoing acute cellular rejection (ACR). Herein we investigated the expression of Th1 (CCR5, CXCR3, and CCR2) and Th2 (CCR4, CCR3, and CCR8)–associated chemokine receptors on CD4 and CD8 T-cell populations. We sought to correlate chemokine receptor expression in peripheral blood T-cell subsets with the types of graft dysfunction (biopsy-proven rejections). In the peripheral blood CD4+ and CD8+ T-cell populations of patients with graft dysfunction, we observed a high frequency of Th1-associated chemokine receptors CCR5+ and CCR2+ but not CXCR3.

Urinary Cell Levels of mRNA for OX40, OX40L, PD-1, PD-L1, or PD-L2 and Acute Rejection of Human Renal Allografts

The positive costimulatory proteins OX40 and OX40L and negative regulatory proteins programmed death (PD)-1, PD ligand 1, and PD ligand 2 have emerged as significant regulators of acute rejection in experimental transplantation models. We obtained 21 urine specimens from 21 renal allograft recipients with graft dysfunction and biopsy-confirmed acute rejection and 25 specimens from 25 recipients with stable graft function and normal biopsy results (stable). Urinary cell levels of mRNAs were measured using real-time quantitative polymerase chain reaction assays, and the levels were correlated with allograft status and outcomes. Levels of OX40 mRNA (P<0.0001, Mann-Whitney test), OX40L mRNA (P=0.0004), and PD-1 mRNA (P=0.004), but not the mRNA levels of PD ligand 1 (P=0.08) or PD ligand 2 (P=0.20), were significantly higher in the urinary cells from the acute rejection group than the stable group. Receiver operating characteristic curve analysis demonstrated that acute rejection is predicted with a sensitivity of 95% and a specificity of 92% (area under the curve=0.98, 95% confidence interval 0.96-1.0, P<0.0001) using a combination of levels of mRNA for OX40, OX40L, PD-1, and levels of mRNA for the previously identified biomarker Foxp3. Within the acute rejection group, levels of mRNA for OX40 (P=0.0002), OX40L (P=0.0004), and Foxp3 (P=0.04) predicted acute rejection reversal, whereas only OX40 mRNA levels (P=0.04) predicted graft loss after acute rejection. A linear combination of urinary cell levels of mRNA for OX40, OX40L, PD-1, and Foxp3 was a strong predictor of acute rejection in human renal allograft biopsies. This prediction model should be validated using an independent cohort of renal allograft recipients.

Impact of Toll-like receptor 2 expression in renal allograft rejection

An important role of TLR2 has been shown in various experimental models of renal ischaemia/reperfusion injury. To study the expression of TLR2 in renal allograft rejection systematically, we established an experimental rat transplantation model. TLR2 expression was analysed in 99 human renal allograft biopsies, and in rat allografts at Day 6 and 28 after experimental renal transplantation. To discriminate whether regulation of TLR2 was following immunological processes after allogeneic transplantation or was a consequence from ischaemia/reperfusion injury, control animals subjected to syngeneic transplantation or to ischaemia/reperfusion damage were also investigated. TLR2 mRNA was significantly elevated in rat allografts with acute rejection on Day 6 and decreased spontaneously towards Day 28. TLR2 induction correlated with renal function and TLR2 excretion in the urine of transplanted rats. TLR2 staining was also significantly increased in human allografts with acute rejection. TLR2 protein could be localized in tubular epithelial cells and vascular endothelial cells, and in CD68- and CD4-positive infiltrating cells. TLR2 is markedly up-regulated in both experimental and human acute renal allograft rejection. Our data suggest a role for TLR2 during allogen-dependent graft damage after renal transplantation.

Renal tubular PD-L1 (CD274) suppresses alloreactive human T-cell responses

Renal proximal tubular epithelial cells, a target of infiltrating T cells during renal allograft rejection, may be protected from this injury by the cell surface protein CD274 (also termed PD-L1 for programmed death ligand 1). The co-inhibitory molecules PD-L1 (CD274) and PD-L2 (CD273) are ligands of PD-1 (programmed death 1; CD279). Here we determine the functional role of PD-1/PD-L pathways in human renal allograft rejection. Treatment of human primary tubular epithelial cells with interferon-beta and -gamma caused a dose-dependent and synergistic increase of PD-L1 and PD-L2 expression. Blockade of surface PD-L1, but not PD-L2, on interferon-treated tubular epithelial cells resulted in a significant increase in CD4+ T-cell proliferation and cytokine production by CD4+ and CD8+ T cells. The expression of PD-L1, PD-L2, and PD-1 mRNA and protein was upregulated in biopsies of patients with renal allograft rejection compared to the respective levels found in the pre-transplant biopsies. Induction of PD-L1 was significantly associated with acute vascular rejection. Our study suggests that the renal epithelial PD-1/PD-L1 pathway exerts an inhibitory effect of on alloreactive T-cell responses. The upregulation of PD-L1 on proximal tubular epithelial cells in patients with acute allograft rejection may reduce T-cell-mediated injury.

The chemokine receptor CXCR7 is expressed on lymphatic endothelial cells during renal allograft rejection

CXCR7 is an atypical receptor for the chemokines CXCL11 and CXCL12, which were found to be involved in animal models of allograft injury. We studied the expression of CXCR7 and its ligands in human kidneys by first quantifying the mRNA in 53 renal allograft biopsies. Receptor and ligand mRNAs were expressed in renal allografts, with a significant induction of CXCL11 and CXCL12 in biopsies showing borderline lesions and acute rejection. Immunohistochemical analysis for CXCR7 was performed in a series of 64 indication and 24 protocol biopsies. The indication biopsies included 46 acute rejections, 6 with interstitial fibrosis and tubular atrophy, and 12 pretransplant biopsies as controls. In control biopsies, CXCR7 protein was found on smooth muscle and on endothelial cells of a small number of peritubular vessels. The number of CXCR7-positive vessels was increased in acute rejection and, using double immunofluorescence labeling, a subset of these CXCR7-positive endothelial cells were identified as lymphatic vessels. Both CXCR7-positive blood and lymphatic vessels increased during allograft rejection. We found that CXCR7 is present in both blood and lymphatic endothelial cells in human renal allografts. Whether its presence modulates the formation of chemokine gradients and the recruitment of inflammatory cells will require further experimental studies.

Noninvasive diagnosis of acute rejection of renal allografts

Acute rejection is an immune process that begins with the recognition of the allograft as nonself and ends in graft destruction. Histological features of the allograft biopsy are currently used for the differential diagnosis of allograft dysfunction. In view of the safety and the opportunity for repetitive sampling, development of noninvasive biomarkers of allograft status is an important objective in transplantation. Herein, we review some of the progress towards the development of noninvasive biomarkers of human allograft status. Urinary cell and peripheral blood cell mRNA profiles have been associated with acute rejection of human renal allografts. Emerging data support the idea that development of noninvasive biomarkers predictive of antibody-mediated rejection is feasible. The demonstration that intragraft microRNA expression predicts renal allograft status suggests that noninvasively ascertained microRNA profiles may be of value. We are pleased with the progress to date, and anticipate clinical trials investigating the hypotheses that noninvasively ascertained mRNA profiles will minimize the need for invasive biopsy procedures, predict the development of acute rejection and chronic allograft nephropathy, facilitate preemptive therapy capable of preserving graft function, and facilitate personalization of immunosuppressive therapy for the allograft recipient.

Chemokine Receptor CCR5 Mediates AlloImmune Responses in Graft-versus-Host Disease

Allogeneic bone marrow transplantation (BMT) is an effective therapy for hematologic malignancies. However graft-versus-host disease (GVHD) is a major limiting factor for a successful patient outcome. GVHD is a result of alloimmune responses of donor T lymphocytes attacking the recipient's cells and tissues. Chemokine receptor CCR5 plays a role in solid organ allograft rejection and mediates murine GVHD pathogenesis. Herein, we report that infiltrating lymphocytes in the skin of human acute GVHD (aGVHD) samples are predominantly CCR5(+) T cells. In addition, we characterized the features of the CCR5 expression on alloreactive T lymphocytes. We found that the CCR5(+) population exhibits the characteristics of the activated effector T cell phenotype. CCR5 expression is upregulated upon allogenic stimulation, and CCR5(+) cells are proliferating with coexpression of T cell activation markers. Furthermore, the activated T cells producing inflammatory cytokine tumor necrosis factor (TNF)alpha, interleukin (IL)-2, or interferon (IFN)-gamma, are positive for CCR5. Thus, CCR5 is a marker for GVHD effector cells and CCR5(+) T cells are active participants in the pathogenesis of human aGVHD.

Promotion of cardiovascular disease by exposure to the air pollutant ozone

in the decades following the discovery of the chemical nature of environmental air pollutants and the biochemical reactions they could undergo, it was viewed that the primary tissue target of air pollution would be our lungs. This made sense, as the principal constituents of photochemical air

Expression of Carcinoembryonic Antigen–Related Cell Adhesion Molecule 1 in Acute Rejection of Human Renal Allografts

Background Carcinoembryonic antigen–related cell adhesion molecule 1 (CEACAM1) is expressed on various cell types and mediates homophilic cell adhesion. CEACAM1 plays an important role in cell morphogenesis and angiogenesis. Furthermore, CEACAM1 regulates adhesive activity of immune-competent cells, suggesting an additional role in inflammatory processes. Methods Therefore, in the present study the expression of CEACAM1 was analysed retrospectively in renal biopsies from kidney transplant recipients (stable graft [Ctr; n = 18], acute vascular rejection [AVR; n = 14], acute tubulointerstitial rejection [AIR; n = 9], and combined vascular and interstitial rejection [AVIR; n = 7]). Expression patterns of CEACAM1 were determined using immunohistochemistry and quantitative morphometry. Results All biopsy specimens from patients with stable grafts showed low CEACAM1 levels, suggesting a constitutive expression in renal transplants. In patients with acute rejection, CEACAM1 was markedly up-regulated. AVR revealed the highest tubular CEACAM1 levels (4.9 ± 0.5% [AVR] vs 2.2 ± 0.3% [Ctr] of tubular area; P < .05), whereas interstitial rejections showed the highest glomerular expressions (4.5 ± 0.5% [AIR] vs 0.9 ± 0.1% [Ctr] of glomerular area; P < .05). Conclusions An up-regulated expression of CEACAM1 in tubular and/or glomerular cells is an indicator of acute inflammatory processes in biopsy specimens from patients with acute renal allograft rejections and, therefore, might be used as a new clinical marker.

Upregulation of TNF Receptor Type 2 in Human and Experimental Renal Allograft Rejection

An important role of TNF interacting with TNFR2 has been shown in different models of ischemic, nephrotoxic and immune-mediated renal injury. To systematically evaluate the expression of TNFR2 in renal allograft rejection, we investigated human renal allograft biopsies and, in addition, established an experimental transplantation model in rats to verify the human data under standardized conditions. The expression of TNFR2 was analyzed in 96 human renal allograft biopsies with different disease entities. In a 6-day and a 28-day experimental protocol, TNFR2 was examined in kidney specimens and in the urine of control, uni-nephrectomized and transplanted rats +/- cyclosporine treatment (n = 114). In human biopsies and in rat allografts on day 6 with acute allograft rejection, significantly elevated expression of TNFR2 was observed in tubular epithelial cells, podocytes, B cells and monocytes/macrophages. The expression level was associated with renal function. The TNFR2 expression level at day 28 was significantly lower compared to day 6. TNFR2 is markedly upregulated both in human and experimental acute renal allograft rejection. Our data are robust and consistent between different species, suggesting a role for TNFR2 in the early course of rejection.

Subendothelial Heparan Sulfate Proteoglycans Become Major L-Selectin and Monocyte Chemoattractant Protein-1 Ligands upon Renal Ischemia/Reperfusion

Leukocyte infiltration into inflamed tissues is considered to involve sequential steps of rolling over the endothelium, adhesion, and transmigration. In this model, the leukocyte adhesion molecule L-selectin and its ligands expressed on inflamed endothelial cells are involved in leukocyte rolling. We show that upon experimental and human renal ischemia/reperfusion, associated with severe endothelial damage, microvascular basement membrane (BM) heparan sulfate proteoglycans (HSPGs) are modified to bind L-selectin and monocyte chemoattractant protein-1. In an in vitro rolling and adhesion assay, L-selectin-binding HSPGs in artificial BM induced monocytic cell adhesion under reduced flow. We examined the in vivo relevance of BM HSPGs in renal ischemia/reperfusion using mice mutated for BM HSPGs perlecan (Hspg2(Delta3/Delta3)), collagen type XVIII (Col18a1(-/-)), or both (cross-bred Hspg2(Delta3/Delta3)xCol18a1(-/-)) and found that early monocyte/macrophage influx was impaired in Hspg2(Delta3/Delta3)xCol18a1(-/-) mice. Finally, we confirmed our observations in human renal allograft biopsies, showing that loss of endothelial expression of the extracellular endosulfatase HSulf-1 may be a likely mechanism underlying the induction of L-selectin- and monocyte chemoattractant protein-1-binding HSPGs associated with peritubular capillaries in human renal allograft rejection. Our results provide evidence for the concept that not only endothelial but also (microvascular) BM HSPGs can influence inflammatory responses.