Arteriolitis in renal transplant biopsies is associated with poor graft outcome

AIMS: The Banff 1997 classification of renal allograft pathology identifies arteriolitis as a finding of uncertain significance. We sought to improve our understanding of arteriolitis by correlating its occurrence with histopathological and clinical parameters. METHODS AND RESULTS: Twenty allograft kidney biopsies from 19 patients, showing arteriolitis, were identified. Arterioles were defined as small vessels with: (1) wall thickness of 1-3 myocytes; (2) diameter less than one-third of an adjacent glomerulus; and (3) discontinuous or absent elastica. Arteriolitis was defined as mural infiltration by lymphocytes. Other histological findings were categorized according to the Banff 1997 working formulation. Ten biopsies (50%) showed type IIA rejection, seven (35%) showed type I rejection, and three (15%) showed borderline change. Two patients with borderline change had acute rejection in the next biopsy. None of the seven patients with type I rejection had previous or subsequent type II rejection on biopsy. A total 11/20 biopsies (10/19 patients) showing arteriolitis had type IIA rejection in the index or next biopsy. On follow-up, graft loss due to rejection occurred in 5/19 (26%) patients (median 126 days); all had shown type IIA rejection on a previous biopsy. Chronic allograft nephropathy developed in a further 4/19 (21%) patients (median 157 days), of whom three had shown only type I rejection on biopsy. CONCLUSION: Arteriolitis is associated with acute rejection, often type II rejection, and is associated with poor graft outcome. Other causes of arteriolitis were not encountered in this series.     

CCL21 expression pattern of human secondary lymphoid organ stroma is conserved in inflammatory lesions with lymphoid neogenesis

CCL21 is a homeostatic lymphoid chemokine instrumental in the recruitment and organization of T cells and dendritic cells into lymphoid T areas. In human secondary lymphoid organs (SLOs), CCL21 is produced by cells distributed throughout the T zone, whereas high endothelial venules (HEVs) lack CCL21 mRNA. A critical question remains whether the development of ectopic lymphoid tissue (ELT) in chronic inflammation recapitulates the features of SLOs. Thus, we systematically investigated in situ the cellular sources of CCL21 in SLOs and ELTs in several human diseases characterized by lymphoid neogenesis. By in situ hybridization and the use of combinatorial cell markers, we show that CCL21-producing vessels in inflamed tissues systematically display typical markers of lymphatic vessels, whereas, as in SLOs, ectopic HEVs do not synthesize detectable levels of CCL21. We also provide first-time evidence that a common pattern of CCL21 expression by CD45-negative myofibroblast-like cells localized in extra-HEV position and organized in a fibroblastic reticular network similarly characterizes human SLOs and organized ELTs. Altogether, our results demonstrate that in humans the pattern of CCL21 production in SLOs is maintained during inflammation and that the phenotypic and functional properties of stromal cells, found in SLO T-cell areas, are reproduced at ectopic sites.     

Acquired flavor acceptance and intake facilitated by monosodium glutamate in humans

Monosodium glutamate (MSG) is known to enhance liking for the flavor of savory foods, but whether associations between flavors and effects of MSG lead to changes in subsequent liking and intake for the flavor alone is unclear. To test this, 32 volunteers evaluated and consumed a novel savory soup with no added MSG before and after four training sessions where the same soup was consumed either unchanged (Control) or with added MSG. The addition of MSG during training increased both pleasantness and savory character of the soup and resulted in a larger increase in rated pleasantness of the soup in the MSG-trained relative to control condition when the soup was re-evaluated Post-training without MSG. There was also a significant increase in voluntary soup intake Post-training after the soup had been paired with MSG but not in the Control condition, and rated hunger increased more after tasting the soup Post-training in the MSG-trained but not Control condition. These findings demonstrate that co-experience of a savory flavor and MSG can result in increased subsequent liking and intake for the flavor in the absence of MSG, and possible explanations for how MSG reinforces learning are discussed.     

Intragraft immunological events associated with EBV DNAemia in liver transplant patients

Epstein-Barr virus (EBV) may cause post-transplant lymphoproliferative disorder, but most EBV infections after liver transplantation (Ltx) are clinically silent reactivations. In this study, we investigated the intragraft immunological events associated with EBV DNAemia. Altogether, 105 adult Ltx patients were monitored for EBV DNAemia. Fourteen (13%) patients developed EBV DNAemia during the first year after transplantation. Liver biopsies obtained associated with EBV DNAemia, without evidence of other herpes or hepatitis viruses or rejection, were available from five patients. The numbers of lymphocytes positive for B-cell marker (CD20), T-cell markers (CD3, CD4 and CD8) and IL-2R, adhesion molecules (ICAM-1, VCAM-1 and ELAM-1) and their ligands [lymphocyte function-associated antigen-1 (LFA-1), very late antigen (VLA-4) and Sialyl Lewis X (sLeX)] were demonstrated in liver biopsies by immunohistochemistry, and zero-biopsies from donor livers were used as controls. EBV DNAemia was associated with increased number of CD20-positive (22±30, p=0.09) and significantly increased numbers of CD3 (80±16, p=0.001)-, CD4 (23±8, p=0.009)- and CD8 (38±8, p=0.001)-positive lymphocytes in the graft. ICAM-1, but not VCAM-1 or ELAM-1, was strongly expressed and the number of LFA-1-positive cells was significantly increased (48±10, p=0.0002). Low-level EBV DNAemia was associated with B- and especially T-cell infiltration of the graft, as well as an increase in ICAM-1 and the number of LFA-1-positive cells. However, EBV DNAemia or these immunological events did not have any effect on the liver transplant.     

Donor-specific hyporesponsiveness in ELISPOT assay is associated with early recurrence of hepatitis C in liver transplant recipients

Recurrence of hepatitis C in liver transplant recipients is a common event that often leads to loss of the allograft. There are no means to prevent, or even predict, those patients who are more prone to early aggressive recurrence. Therefore there is an increased need for tailored immunosuppression protocols specific to this patient population. Fifteen liver transplant recipients (eight hepatitis C virus [HCV]+; 7 HCV-) were followed for 12-24 months after transplantation. The frequency of donor-specific interferon (IFN)-gamma- or interleukin-10-producing lymphocytes was monitored using ELISPOT assays. Of the eight HCV+ recipients, six experienced recurrence within the first year after transplant. All six patients had very low (negligible) frequency of donor-specific IFN-gamma precursors; in most cases not higher than the nonstimulated (spontaneous) secretion rate. The other two patients who did not recur exhibited donor-specific IFN-gamma reactivity. A significant difference in the frequency of alloantigen-specific T cells was observed between HCV+ recipients and patients with other indications for transplantation. The results of this preliminary study suggest that posttransplant monitoring of the frequency of donor-specific IFN-gamma-producing precursors may differentiate a subset of patients at risk for early recurrent hepatitis C and therefore may help to devise treatment strategies for HCV+ liver recipient after transplantation.     

The chemokine receptor CXCR5 is pivotal for ectopic mucosa-associated lymphoid tissue neogenesis in chronic Helicobacter pylori-induced inflammation

Ectopic lymphoid follicles are a key feature of chronic inflammatory autoimmune and infectious diseases, such as rheumatoid arthritis, Sjögren's syndrome, and Helicobacter pylori-induced gastritis. Homeostatic chemokines are considered to be involved in the formation of such tertiary lymphoid tissue. High expression of CXCL13 and its receptor, CXCR5, has been associated with the formation of ectopic lymphoid follicles in chronic infectious diseases. Here, we defined the role of CXCR5 in the development of mucosal tertiary lymphoid tissue and gastric inflammation in a mouse model of chronic H. pylori infection. CXCR5-deficient mice failed to develop organized gastric lymphoid follicles despite similar bacterial colonization density as infected wild-type mice. CXCR5 deficiency altered Th17 responses but not Th1-type cellular immune responses to H. pylori infection. Furthermore, CXCR5-deficient mice exhibited lower H. pylori-specific serum IgG and IgA levels and an overall decrease in chronic gastric immune responses. In conclusion, the development of mucosal tertiary ectopic follicles during chronic H. pylori infection is strongly dependent on the CXCL13/CXCR5 signaling axis, and lack of de novo lymphoid tissue formation attenuates chronic immune responses.     

Acute rejection in heart transplant patients is associated with the presence of committed donor-specific cytotoxic lymphocytes in the graft but not in the blood.

In vivo-activated, committed donor-specific cytotoxic lymphocytes (cCTL) can be propagated and expanded from endomyocardial biopsies (EMB) in IL-2-enriched medium especially during an acute rejection episode. We report here our efforts to detect these cCTL by the same technique in peripheral blood at the moment of rejection and when no rejection was diagnosed. During or just before rejection, significantly less frequent (P less than 0.01) donor reactive cCTL were found in PBL samples (two out of 20) than in the simultaneously taken EMB samples (13 out of 19). Donor B-LCL and/or third-party B-LCL were lysed by 15 PBL samples. Inhibition studies revealed that this lysis was due to LAK-like cytotoxicity. The results show that peripheral blood does not reflect intra-graft events, which is probably the reason for the irreproducible results of diagnosis of rejection by monitoring immunological parameters in the peripheral blood.     

BLC expression in pancreatic islets causes B cell recruitment and lymphotoxin-dependent lymphoid neogenesis

CXCR5, the receptor for B lymphocyte chemoattractant (BLC), is required for normal development of Peyer's patches, inguinal lymph nodes, and splenic follicles. To test the in vivo activity of BLC in isolation of other lymphoid organizers, transgenic mice were generated expressing BLC in the pancreatic islets. In addition to attracting B cells, BLC expression led to development of lymph node-like structures that contained B and T cell zones, high endothelial venules, stromal cells, and the chemokine SLC. Development of these features was strongly dependent on B lymphocytes and on lymphotoxin alpha1beta2 and could be reversed by blocking lymphotoxin alpha1beta2. These findings establish that BLC is sufficient to activate a pathway of events leading to formation of organized lymphoid tissue.     

Nerve growth factor accelerates the early cellular events associated with wound healing

The effects of injecting nerve growth factor (NGF) into subdermal air sacs on the backs of mice was studied. Sequential infiltration of cells into the lining of the sacs was observed. The initial cell type to infiltrate was the polymorphonuclear leukocyte, followed by highly vacuolated mononuclear cells, and then by fibroblast-like cells. This resembles the classical pattern of cellular responses during the normal process of wound healing. The kinetics for the peak accumulation of each cell type were dependent upon the concentration of NGF injected, and significant acceleration of infiltration of each cell type was observed with as little as 1 nM NGF. A similar acceleration of cellular infiltration was observed when mice were injected with the synthetic chemotactic peptide n-formyl-methionyl-leucyl-phenylalanine. This finding suggests that application of any chemotactic factor to wound sites may lead to accelerated tissue repair and an enhanced rate of wound contraction. The observation that NGF can act as a chemotactic factor in vivo may explain its ability to accelerate the healing of experimentally induced wounds in mice.     

Antithymocyte globulin is associated with complement deposition in cardiac transplant biopsies

Polyclonal antithymocyte globulin preparations contain antibodies with reactivity to endothelial cells. Therefore, we investigated whether treatment with this reagent caused complement deposition in human cardiac transplants. Frozen tissue was available from endomyocardial biopsies of 75 patients, who were transplanted between April 1995 and April 2000. Nine of these patients were converted from cyclosporin A (CsA) to horse antithymocyte globulin (ATGAM) in the first month after transplantation. All of the biopsies were stained by immunofluorescence for C4d as evidence of activation of the classical pathway of complement. In addition, biopsies from patients treated with ATGAM and control patients were stained for deposition of horse immunoglobulin (Ig)G. All nine patients who received ATGAM had deposition of horse IgG and C4d. Two color stains demonstrated that the horse IgG colocalized with the C4d staining. No staining for horse IgG or C4d was evident in biopsies obtained before ATGAM treatment. Likewise, no staining for horse IgG was detected in seven control patients who had C4d staining. Most patients treated with ATGAM had no histologic evidence of rejection, but did have myocyte damage and macrophage infiltration. Thus prophylactic treatment with ATGAM is associated with the deposition of horse IgG and activation of complement in the transplant.     

Early post-operative acute phase response in patients with early graft dysfunction is predictive of 6-month and 12-month mortality in liver transplant recipients

Early allograft dysfunction (EAD) after liver transplantation is mostly a reversible event caused by factors related to ischemia/reperfusion (I/R) injury. EAD represents a hepatic injury associated with pre- and early post-transplant inflammatory cytokine responses. Aim of the present study was to evaluate the prognostic and diagnostic value of CRP in liver transplant recipients with EAD.Materials and methodsForty-seven patients with EAD were compared with 115 non-EAD patients. Pre- and post-transplant parameters were analyzed. EAD was defined based on postoperative liver function tests such as INR, bilirubin and liver enzymes. Statistical analysis was performed using SPSS version 18.0.ResultsPre-transplant liver enzyme were not significantly different in the two groups. At day 3, 5 and 10 post-transplant CRP was significantly higher in patients with EAD than in non-EAD patients (p ⩽ 0.001 for all investigations) and remained consistently high in patients with EAD and low in non-EAD patients. EAD patients with high CRP at post-transplant days 3 and 5 showed lower survival at 6-month and 12-month post-transplant than patients with low CRP.ConclusionOur results indicate a prognostic and diagnostic value of CRP in patients with early graft dysfunction and predict 6-month and 12-month mortality in liver transplant recipients.     

Lymphoid tissue engineering: invoking lymphoid tissue neogenesis in immunotherapy and models of immunity

The plasticity of the immune system is evident in the reorganization of secondary lymphoid organs during immune responses, lymphoid tissue neogenesis occurring during chronic inflammation or graft rejection, and the engineered lymphoid tissue formation induced by ectopic expression of single lymphoid tissue-associated genes. Approaches seeking to harness this plasticity for immunotherapy are under investigation, particularly by controlling immune cell recruitment and lymphoid tissue formation at tumor sites. By combining strategies from ectopic tissue induction models with methods from tissue engineering, new approaches for studying lymphoid tissue development and immunotherapy may be possible.     

Equid herpesvirus-induced immunosuppression is associated with lymphoid cells and not soluble circulating factors

A paresis isolate of equid herpesvirus 1 (EHV1, Ab4/8) and a plaque-purified virus derived from it (EHV1, Ab4/13), induced long-term suppression of both mitogenic and antigen-specific lymphocyte proliferations in adult outbred ponies. Peripheral blood mononuclear cells (PBMC) taken from a pony after EHV1 infection suppressed the in vitro function of normal cells but serum did not. This showed that the observed immune suppression was associated with circulating PBMC and/or their products rather than circulating soluble factors such as antigen or immune complexes. The results suggested that productive infection of lymphocytes by EHV1 was unlikely to result in the observed in vitro effects. Moreover, prostaglandin release from monocytes was not likely to have caused the observed suppression, because lymphocyte responsiveness was not restored in the presence of indomethacin.     

Disturbance of the gut-associated lymphoid tissue is associated with disease progression in chronic HIV infection

Why and how HIV makes people sick is highly debated. Recent evidence implicates heightened immune activation due to breakdown of the gastrointestinal barrier as a determining factor of lentiviral pathogenesis. HIV-mediated loss of Th17 cells from the gut-associated lymphoid tissue (GALT) impairs mucosal integrity and innate defense mechanisms against gut microbes. Translocation of microbial products from the gut, in turn, correlates with increased immune activation in chronic HIV infection and may further damage the immune system by increasing viral and activation-induced T cell death, by reducing T cell reconstitution due to tissue scarring, and by impairing the function of other cell types, such as γδ T cells and epithelial cells. Maintaining a healthy GALT may be the key to reducing the pathogenic potential of HIV.     

Olfactory social memory in rats is facilitated by histamine

Inflammation Research -     

Human bone marrow transplant rejection is associated with telomere cleavage.

Telomeres that guard chromosomes are shortened with each cell division because of replication-dependent sequence loss at both termini. The gradual erosion of telomeric length has been directly related to the process of aging in vivo. Recently we have reported, in murine and human cancer cells treated with different apoptogens, cleavage and extrusion of telomeric DNA prior to cell death on one hand and an amplification of telomeric DNA in metastatic epithelial malignancies of different histopathologic origin on the other. This study tested our hypothesis that telomere cleavage is linked to transplant rejection in cancer patients receiving stem cells either from bone marrow (BM) or umbilical cord blood transfusion. Telomere integrity and mitotic catastrophe were studied by cytogenetic and molecular fluorescence in situ hybridization (FISH) techniques in two BM samples taken from a male stem cell transplant recipient diagnosed with aplastic anemia. The first BM sample, which was aspirated 27 days after transplant, was mitotically active. Only one of 50 metaphases showed a chromatid break. Every cell karyotyped was of male origin with 46, XY chromosome constitution. The second BM sample aspirated 52 days after transplant gave no metaphases and most interphase cells appeared dead. FISH preparations of the second BM sample showed cleavage and drastic reduction of telomeric DNA at the time the patient was rejecting the transplant. In contrast, the first BM sample had shown no indication of cleavage of the telomeric DNA, although the percentage of telomeric area was smaller than in the control. The replicative stress imposed on the stem cells engrafted may result in an accelerated aging effect, possibly due to the erosion of telomeric DNA. We, therefore, conclude that BM rejection could be directly associated with the cleavage, clustering, and extrusion of telomeric DNA in the donor cells.     

Lymphoid neogenesis in chronic rejection: the murderer is in the house

Although chronic rejection is currently the main cause of long-term allograft failure, its pathogenesis remains elusive, hereby preventing the development of effective therapy. Recent advances in the comprehension of the pathophysiology of chronic inflammatory diseases could shed new light on the pathogenesis of chronic rejection. Lymphoid neogenesis is a mechanism responsible for the progressive organization of chronic inflammatory infiltrates into functional ectopic germinal centers, and has been evidenced recently in various pathological situations sharing a common feature: the failure of the immune response to eradicate the targeted antigen(s). Chronic rejection is such a situation as it results from a sustained alloimmune response against the donor's antigens that are constantly replenished by the grafted tissue. Accordingly, functional ectopic germinal centers develop within chronically rejected organs. This implies that, during chronic rejection, graft is at the same time the target and the site of elicitation of the alloimmune response.     

Accelerated arteriosclerosis in heart transplant recipients is associated with a T-lymphocyte-mediated endothelialitis.

Accelerated arteriosclerosis has emerged as a major life-threatening complication in long-term survivors of heart transplantation. It has been proposed that accelerated arteriosclerosis is an immune-mediated complication of rejection. We observed a striking endothelialitis in the coronary arteries of two explanted hearts obtained from patients with severe transplant-related accelerated arteriosclerosis. This finding prompted us to review the pathologic changes in the coronary arteries of 23 autopsied patients who had received heart transplants. The infiltrate in these vessels was characterized using immunohistochemical stains for lymphocytes (CD45), macrophages (MAC-387), T lymphocytes (CD45RO), B lymphocytes (L-26), and smooth muscle cells (actin). In addition, a full panel of monoclonal antibodies was used on the fresh-frozen tissue available from one of the two explanted hearts. Ten of the eleven recipients with accelerated arteriosclerosis had a moderate to marked lymphocytic endothelialitis compared to 3 of 14 without transplant-related arteriosclerosis (P less than 0.005). Immunohistochemical staining of the paraffin-embedded material demonstrated that most of the lymphocytes in the subendothelial space of these vessels were T lymphocytes and that this infiltrate was associated with an accumulation of macrophages and a proliferation of smooth muscle cells in the intima. In the explanted heart from which fresh-frozen tissue was available for more detailed cell typing, the T cells marked predominantly as cytotoxic T lymphocytes (CD8+, CD2+). These results suggest that accelerated arteriosclerosis may be mediated, in part, by a cytotoxic T-lymphocyte-directed endothelialitis.