Role of RANTES in experimental cardiac allograft rejection

Immunological and inflammatory mapping of vascularized composite allograft rejection processes in a rat model

BACKGROUND

Hand and face vascularized composite allotransplantation (VCA) is an evolving and challenging field with great opportunities. During VCA, massive surgical damage is inflicted on both donor and recipient tissues, which may contribute to the high VCA rejection rates. To segregate between the damage-induced and rejection phase of post-VCA responses, we compared responses occurring up to 5 days following syngeneic versus allogeneic vascularized groin flap transplantations, culminating in transplant acceptance or rejection, respectively.

METHODS

The immune response elicited upon transplantation of a syngeneic versus allogeneic vascularized groin flap was compared at Post-operative days 2 or 5 by histology, immunohistochemistry and by broad-scope gene and protein analyses using quantitative real-time PCR and Multiplex respectively.

RESULTS

Immune cell infiltration began at the donor-recipient interface and paralleled expression of a large group of wound healing-associated genes in both allografts and syngrafts. By day 5 post-transplantation, cell infiltration spread over the entire allograft but remained confined to the wound site in the syngraft. This shift correlated with upregulation of IL-18, INFg, CXCL9, 10 and 11, CCL2, CCL5, CX3CL1 and IL-10 in the allograft only, suggesting their role in the induction of the anti-alloantigen adaptive immune response.

CONCLUSIONS

High resemblance between the cues governing VCA and solid organ rejection was observed. Despite this high resemblance we describe also, for the first time, a damage induced inflammatory component in VCA rejection as immune cell infiltration into the graft initiated at the surgical damage site spreading to the entire allograft only at late stage rejection. We speculate that the highly inflammatory setting created by the unique surgical damage during VCA may enhance acute allograft rejection.

Myocardial Gene Expression Profiling to Predict and Identify Cardiac Allograft Acute Cellular Rejection: The GET-Study

Aims

Serial invasive endomyocardial biopsies (EMB) remain the gold standard for acute cellular rejection (ACR) diagnosis. However histological grading has several limitations. We aimed to explore the value of myocardial Gene Expression Profiling (GEP) for diagnosing and identifying predictive biomarkers of ACR.

Methods

A case-control study nested within a retrospective heart transplant patients cohort included 126 patients with median (IQR) age 50 (41–57) years and 111 (88%) males. Among 1157 EMB performed, 467 were eligible (i.e, corresponding to either ISHLT grade 0 or ≥3A), among which 36 were selected for GEP according to the grading: 0 (C_ISHLT, n = 13); rejection ≥3A (R_ISHLT, n = 13); 0 one month before ACR (BR_ISHLT, n = 10).

Results

We found 294 genes differentially expressed between C_ISHLT and R_ISHLT, mainly involved in immune activation, and inflammation. Hierarchical clustering showed a clear segregation of C_ISHLT and R_ISHLT groups and heterogeneity of GEP within R_ISHLT. All EMB presented immune activation, but some R_ISHLT EMB were strongly subject to inflammation, whereas others, closer to C_ISHLT, were characterized by structural modifications with lower inflammation level. We identified 15 probes significantly different between BR_ISHLT and C_ISHLT, including the gene of the muscular protein TTN. This result suggests that structural alterations precede inflammation in ACR. Linear Discriminant Analysis based on these 15 probes was able to identify the histological status of every 36 samples.

Conclusion

Myocardial GEP is a helpful method to accurately diagnose ACR, and predicts rejection one month before its histological occurrence. These results should be considered in cardiac allograft recipients’ care.

Gene transfer of the S24F regulated on activation normal T-cell expressed and secreted-chemokine ligand 5 variant attenuates cardiac allograft rejection

BACKGROUND

Regulated on activation normal T-cell expressed and secreted (RANTES)-chemokine ligand 5 plays a key role in mediating heart transplant rejection. Suppression of RANTES-mediated signals can reduce leukocyte recruitment and mitigate transplant rejection severity. The present study describes the construction of an adenovirus overexpression vector encoding a natural S24F RANTES variant as a means of reducing leukocyte recruitment, resulting in the prevention of allograft rejection.

METHODS

The in vitro transendothelial chemotaxis assay was used to compare RANTES-induced transmigration of peripheral blood mononuclear cells across human umbilical vein endothelial cells cultured on the upper Transwell chamber. Intracoronary delivery of Ad-S24F, Ad-Null, or phosphate-buffered saline was performed in BALB/c donor hearts that were transplanted into the abdominal cavity of C57BL/6 recipients as a measure of allograft survival. Intragraft inflammatory cell infiltrates and associated proinflammatory cytokine expression profiles were detected by immunohistochemistry and quantitative real-time polymerase chain reaction on day 6 after transplantation, respectively.

RESULTS

Regulated on activation normal T-cell expressed and secreted-induced peripheral blood mononuclear cell transendothelial chemotaxis is inhibited by S24F (Ad-S24F, 9.2%±0.02%; Ad-Null, 17.7%±0.02%; medium control, 15.1%±0.01%; P<0.05). Cardiac allograft survival was prolonged after delivery of 1×10 plaque-forming units of Ad-S24F (13.00±0.33 days compared with 9.38±0.60 and 9.00±0.38 days after Ad-Null or phosphate-buffered saline treatment, respectively, P<0.05). S24F gene transfer reduced the number of intragraft CD8 T lymphocytes, monocyte-macrophages, and T-cell receptor αβ cell infiltrates (P<0.05) and decreased transcripts for RANTES and interferon-γ (P<0.05).

CONCLUSION

S24F is an important component of the chemokine network involved in regulating the biologic activity of RANTES, and its expression can be used in the prevention and treatment of cardiac allograft rejection.

Role of regulated upon activation normal T-cell expressed and secreted in a model of retransplantation acute rejection mediated by alloreactive memory CD4+ T cells

BACKGROUND

It is unknown what role Regulated Upon Activation Normal T-Cell Exposed and Secreted may play in retransplantation or T-cell memory-transfer models. The experiment observed the influence of the chemokine RANTES in a mouse model of acute cardiac allograft rejection induced by adoptive transfer of alloreactive CD4(+) memory T (Tm) cells.

METHODS

Alloreactive CD4(+) Tm cells from spleens of skin-grafted C57BL/6 were adoptively transferred to naïve C57BL/6 recipients prior to heterotopic heart transplantation. We measured the median survival time of cardiac grafts and performed some tests.

RESULTS

Spleens from skin-grafted C57BL/6 contained 26.83% CD4(+) Tm cells. The median graft survival time of heterotopic heart transplantations (n = 6) was 5.17 ± 0.17 days for hosts receiving CD4(+) Tm cells compared with 7.76 ± 0.21 days among controls (n = 6; P < .001). The mean rejection activity in histological sections of cardiac allografts at day 5 postgrafting was 3.92 ± 0.08 in the CD4(+) Tm cell recipient group (n = 6) compared with 2.67 ± 0.14 in the controls (n = 6; P < .001). Gene expression of Ccl5, interferon (IFN)-γ and interleukin2 was significantly higher among CD4(+) Tm recipients compared with controls. Serum concentrations of RANTES and IFN-γ were higher in the heterotopic heart transplantation group receiving CD4(+) Tm compared with controls.

CONCLUSIONS

Alloreactive CD4(+) Tm cells contribute to increased expression and secretion of RANTES, and to the Tm and other inflammatory cells migration into the graft.

Neutralizing nanobodies targeting diverse chemokines effectively inhibit chemokine function

Chemokine receptors and their ligands play a prominent role in immune regulation but many have also been implicated in inflammatory diseases such as multiple sclerosis, rheumatoid arthritis, allograft rejection after transplantation, and also in cancer metastasis. Most approaches to therapeutically target the chemokine system involve targeting of chemokine receptors with low molecular weight antagonists. Here we describe the selection and characterization of an unprecedented large and diverse panel of neutralizing Nanobodies (single domain camelid antibodies fragment) directed against several chemokines. We show that the Nanobodies directed against CCL2 (MCP-1), CCL5 (RANTES), CXCL11 (I-TAC), and CXCL12 (SDF-1α) bind the chemokines with high affinity (at nanomolar concentration), thereby blocking receptor binding, inhibiting chemokine-induced receptor activation as well as chemotaxis. Together, we show that neutralizing Nanobodies can be selected efficiently for effective and specific therapeutic treatment against a wide range of immune and inflammatory diseases.

Role of cold shock Y-box protein-1 in inflammation, atherosclerosis and organ transplant rejection

Chemokines (chemoattractant cytokines) are crucial regulators of immune cell extravasation from the bloodstream into inflamed tissue. Dysfunctional regulation and perpetuated chemokine gene expression are linked to progressive chronic inflammatory diseases and, in respect to transplanted organs, may trigger graft rejection. RANTES (regulated upon activation, normal T cell expressed and secreted (also known as CCL5)) is a model chemokine with relevance in numerous inflammatory diseases where the innate immune response predominates. Transcription factor Y-box binding protein-1 (YB-1) serves as a trans-regulator of CCL5 gene transcription in vascular smooth muscle cells and leucocytes. This review provides an update on YB-1 as a mediator of inflammatory processes and focuses on the role of YB-1 in CCL5 expression in diseases with monocytic cell infiltrates, albeit acute or chronic. Paradigms of such diseases encompass atherosclerosis and transplant rejection where cold shock protein YB-1 takes a dominant role in transcriptional regulation.

Cardiac allograft rejection: examination of the expression and function of the decoy chemokine receptor D6

BACKGROUND

Inflammatory cell recruitment during allograft rejection is driven by a group of inflammatory cytokines termed chemokines. Chemokines are presented on the surface of the vascular endothelium where they ligate specific receptors expressed on the surface of leukocytes. Recently, a group of nonsignaling chemokine receptors have been described. These bind and internalize chemokines but do not drive leukocyte migration. It is believed that these compete with classical signaling receptors to modulate inflammation.

METHODS

This study describes the first examination of the human decoy chemokine receptor D6 during rejection; D6 binds at least 12 potent proinflammatory chemokines. The expression of D6 by graft infiltrating leukocytes was examined in cardiac allografts by confocal microscopy on biopsy sections (n=19). Cytokine regulation of D6 was examined in vitro, and a chemokine scavenging assay was performed using the prototypical transplant-associated chemokine CCL5/RANTES.

RESULTS

D6 expression was found to be higher in the biopsies taken from more severe cardiac allograft rejection (P<0.01) and was predominantly localized to graft infiltrating CD45(+)CD68(+) leukocytes. In vitro studies demonstrated that the transforming growth factor-beta strongly increased the expression of D6 by monocytes, which significantly enhanced D6-mediated chemokine scavenging (by 85%, P<0.05).

CONCLUSIONS

We present the first examination of the biology of D6 during rejection and identify a transplant-associated cytokine that is able to regulate its expression. These data suggest an exciting new mechanism for the antiinflammatory actions of transforming growth factor-beta. Understanding the expression patterns of D6 may provide important insight into the regulation and control of inflammatory cell recruitment during allograft rejection.

Comparison of platelet-rich plasma, bovine BMP, and rhBMP-4 on bone matrix protein expression in vitro

This study investigated the potential use of platelet-rich plasma (PRP) in conjunction with mRNA expression of bone matrix proteins using bioassay and RT-PCR comparing bovine bone morphogenetic proteins (BMP), recombinant human BMP-4 (rhBMP-4) during rat bone marrow stromal cell (Mesenchymal Stem Cell) differentiation at 14 days. The results showed that all three growth factors were associated with significantly elevated alkaline phosphatase activity. PRP and bovine BMP resulted in increased protein content. The mRNA of type I collagen was expressed with all three growth factors and remained consistently elevated. Osteopontin was observed with PRP from days 1 to 7; bone sialoprotein expression was detected on days 1 and 3. PRP, bovine BMP and rhBMP-4 enhanced the steady-state expression of PDGF-A as time-dependent to day 14 and in PRP was the strongest. PTHr was expressed at days 1 and 5. Vascular endothelial growth factor expression was the most highly expressed after day 3. These findings suggest that PRP increases mRNA expression of bone matrix protein, enchances osteogenesis and angiogenesis in vitro.

Platelet-rich plasma induces mRNA expression of VEGF and PDGF in rat bone marrow stromal cell differentiation

OBJECTIVE

To investigate the potentially useful of platelet-rich plasma (PRP) on mRNA expression of angiogenesis.

STUDY DESIGN

Adjunct assay and reverse-transcription polymerase chain reaction (RT-PCR) analysis of type I collagen, vascular endothelial growth factor (VEGF), and platelet-derived growth factor (PDGF) in rat bone marrow stromal cells differentiation in 14 days' culture.

RESULTS

The PRP significantly elevated alkaline phosphatase activity after day 5 (P < .05), and DNA and protein content increased at culture days 1, 3, and 5 (P < .01) with PRP compared with control. The RT-PCR demonstrated that type I collagen was expressed in all substrates and remained high with PRP during 14 days of culture, and that mRNA expression of VEGF and PDGF were higher over time.

CONCLUSIONS

This study indicates a potential contribution of PRP as possibly starting the process of angiogenesis, recruiting the endothelial cells which line blood vessels, and beginning the initiation of bone regeneration.

Relationship between natriuretic peptides and inflammation: proteomic evidence obtained during acute cellular cardiac allograft rejection in humans

BACKGROUND

Cardiac natriuretic peptides (NPs) atrial natriuretic factor (ANF) and brain natriuretic peptide (BNP) are polypeptide hormones secreted by the heart. Previously, we found that BNP, but not ANF, plasma levels may increase during an acute cellular cardiac allograft rejection episode. In vitro, the pro-inflammatory cytokines interleukin-1beta (IL-1beta) and tumor necrosis factor-alpha (TNF-alpha) produced a selective increase of BNP gene expression and secretion. Other pro-inflammatory cytokines had no such effects.

METHODS

We identified cytokines associated with the selective upregulation of BNP during cardiac allograft rejection using a proteomics approach to measure 120 cytokines and related substances in the plasma of 16 transplant patients before, during and after an acute rejection episode. The values obtained were correlated with BNP plasma levels. Cytokines identified as being significantly related to BNP plasma levels were tested in neonatal rat ventricular cardiocytes in culture for their ability to selectively promote BNP secretion. The signaling pathway related to this phenomenon was pharmacologically characterized.

RESULTS

Regulated-on-activation, normal T-expressed and secreted (RANTES), neutrophil-activating protein-2 (NAP-2) and insulin growth factor binding protein-1 (IGFBP-1) had significant correlations with BNP plasma levels during Grade 3A (Grade 2 revised [2R]) or above rejection as diagnosed by endomyocardial biopsy score according to the International Society for Heart and Lung Transplantation (ISHLT) grading system. In rat neonatal ventricular cardiocyte cultures, IGFBP-1 and RANTES were capable of promoting BNP, but not ANF secretion, as observed in rejecting patients. The BNP-promoting secretion activity of the identified cytokines was abolished by SB203580, a specific p38 MAP kinase inhibitor.

CONCLUSIONS

This work shows that cytokines other than pro-inflammatory cytokines correlate with BNP plasma levels observed during acute cardiac allograft rejection, and that the substances identified have in common p38 signaling. This finding provides a unifying mechanistic explanation regarding the relationship between inflammation and cardiac hormone production in acute cardiac allograft rejection.

CCR1/CCL5 (RANTES) receptor-ligand interactions modulate allogeneic T-cell responses and graft-versus-host disease following stem-cell transplantation

Acute graft-versus-host disease (GVHD) and leukemic relapse are serious complications of allogeneic stem-cell transplantation (SCT). Recruitment of activated T cells to host target tissues or sites of leukemic infiltration (graft-versus-leukemia [GVL]) is likely mediated by chemokine receptor-ligand interactions. We examined the contribution of donor cell CCR1 expression to the development of GVHD and GVL using a well-established murine SCT model (B6 --> B6D2F1) and CCR1-deficient mice (CCR1(-/-)). Allo-SCT with CCR1(-/-) donor cells significantly reduced systemic and target organ GVHD severity, and CCR1 expression on both T cells and accessory cells contributed to GVHD mortality. Significant GVL activity was preserved following CCR1(-/-) SCT, but the survival advantage diminished with increasing tumor burden. We then explored the effects of CCR1 expression on allo-specific T-cell responses. Although cytolytic effector function was maintained on a per-cell basis, T-cell proliferation and IFNgamma secretion were significantly reduced both in vivo and in vitro. T-cell function was partially dependent on interactions between CCR1 and CCL5. Collectively, these data demonstrate that CCR1 expression on donor cells contributes to the development of both GVHD and GVL, and suggest that CCR1/CCL5 receptor-ligand interactions modulate allo-specific T-cell responses occurring in this context.

Poly (ADP) ribose polymerase inhibition improves rat cardiac allograft survival

BACKGROUND

Heart transplantation is an accepted treatment modality for end-stage heart failure. However, acute cellular rejection (ACR) continues to be a morbid complication. Recently a novel mechanism of inflammatory allograft injury has been characterized which involves overactivation of the nuclear enzyme poly (ADP-ribose) polymerase (PARP). In the present studies, we compared the efficacy of INO-1001, a novel, potent PARP inhibitor, in limiting ACR with and without adjuvant low-dose cyclosporine (CSA).

METHODS

Heterotopic heart transplantation was performed utilizing Brown-Norway strains as donors and Lewis rats as recipients. Groups received daily intraperitoneal injections of: vehicle, low-dose CSA, low-dose INO-1001, high-dose INO-1001, and low-dose CSA combined with high-dose INO-1001. Additional animals were sacrificed on postoperative Day 5 for histologic assessments of allograft inflammation, including immunohistochemistry for nitrotyrosine and poly (ADP-ribose) (the product of PARP) staining.

RESULTS

PARP inhibition significantly prolonged allograft survival relative to vehicle controls. The combination of low-dose CSA and INO-1001 resulted in a marked increase in allograft survival and significant reductions in allograft rejection scores. This was associated with decreased nitrotyrosine and PAR staining in transplanted cardiac allografts.

CONCLUSIONS

Pharmacologic inhibition of INO-1001 prolongs allograft survival in a dose-dependent fashion in a rodent model of heart transplantation. PARP inhibitors may permit reductions in the dose of CSA needed for adequate immunosuppression after heart transplantation.

Angiotensin II Receptor Expression Following Intestinal Transplantation in Mice

BACKGROUND

To further improve the success rate of intestinal transplantation there is a need to find early appearing indicators of rejection. The specific aim of this study was to compare Angiotensin (Ang) II type 1 receptor and Ang II type 2 receptor expression in relation to histological signs of rejection.

METHODS

Mice of the C57BL6 strain with syngeneic intestinal grafts were compared to mice subjected to allogeneic intestinal transplantation with BalbC strain as donors. Local expression of Ang II type 1 and 2 receptor was evaluated using rt-PCR and Western blot and compared to histological picture in grafts and native intestine.

RESULTS

The Ang II type 2 receptor protein expression was markedly up-regulated in the allogeneically transplanted graft from day 1 postoperatively. Histological signs of rejection were not seen until day 6.

CONCLUSION

Intestinal allograft transplantation in mice is associated with a marked up-regulation of the Ang II type 2 receptor. However, the detailed role of the renin-angiotensin system in the immune rejection following intestinal transplantation remains to be clarified.

Changes of inducible protein-10 and regulated upon activation, normal T cell expressed and secreted protein in acute rejection of pancreas transplantation in rats

AIM: To investigate the role of IFN-γ inducible protein -10 (IP-10) and regulated upon activation, normal T cell expressed and secreted (RANTES) protein in acute pancreatic allograft rejection in rats.

METHODS: An experimental pancreas transplantation model was established using diabetic SD rats as the recipient, induced by applying streptozocin (STZ). Pancreas transplantation was performed with a physiologic method of portal venous and enteric drainage. Rats were divided into two groups, isograft group (group A, n = 24) and allograft group (group B, n = 24) in which either healthy SD rats or Wistar rats served as donors, respectively. Twelve diabetic or healthy SD rats were used as controls. At d 1, 4, 7, and 10 post transplantation, serum IP-10 and RANTES were assessed by ELISA and their expression in the allografts was determined by immunohistochemistry.

RESULTS: In group B (allograft group), the development of acute rejection was significantly correlated with increased serum concentration and tissue expression of IP-10 and RANTES, with a peak level at d 7 post transplantation. In contrast, there was no obvious change before and after transplantation in group A (isograft group).

CONCLUSION: Our study suggests a possible role of IP-10 and RANTES in acute rejection and early monitoring of chemokines may be helpful in predicting the outcome of pancreas transplantation.

Gene transfer of RANTES and MCP-1 chemokine antagonists prolongs cardiac allograft survival

Vascularized organ allografts are rapidly destroyed by host immune cells that are recruited along chemokine gradients. Among chemokines, Regulated on Activation, Normal T-cell Expressed and Secreted (RANTES) CC chemokine ligand (CCL5) and monocyte chemoattractant protein (MCP)-1 (CCL2) are upregulated in rejecting cardiac allografts. To antagonize these chemokines, we constructed adenoviral vectors expressing NH(2)-terminal deletion (8ND) mutants of the respective genes. Using the F344-to-LEW rat model, intragraft gene transfer of chemokine analogs prolonged cardiac allograft survival from 10.1+/-0.7 and 10.4+/-0.7 days using non-coding adenovirus and vehicle alone, respectively, to 17.0+/-0.7 days for 8ND-RANTES (P<0.001) and 14.2+/-0.8 days for 8ND-MCP-1 (P<0.01). 8ND-RANTES reduced graft infiltration by monocytes/macrophages, cluster of differentiation (CD) 8alpha(+) and T-cell receptor alphabeta(+) cells, while 8ND-MCP-1 reduced monocytes/macrophages. In mixed leukocyte reactions in vitro, proliferation of host lymphocytes from regional lymph nodes in response to donor splenocytes was unaffected by 8ND-RANTES gene transfer. Using a two-gene approach, the contribution of 8ND-MCP-1 was negligible, consistent with available evidence that 8ND-RANTES inhibits both RANTES and MCP-1 activities. 8ND-RANTES gene transfer and a short course of low-dose cyclosporine A synergistically prolonged graft survival to 37.8+/-5.5 vs 15.4+/-0.5 days with cyclosporine alone (P<0.001). These results suggest a role for anti-chemokine gene therapy as an adjuvant therapy in heart transplantation.

CCR5, RANTES and CX3CR1 polymorphisms: possible genetic links with acute heart rejection

BACKGROUND

The inflammation response is modulated by the elaborated chemokine-chemokine receptor system, which also plays an important role in the development of acute rejection (AR). In this study, we hypothesized that functional genetic variants of some of these modulatory proteins might influence the outcome of AR.

METHODS

In a retrospective analysis of a cohort of heart transplanted patients (n=158), we examined eight polymorphisms in four genes implicated in this inflammatory process: RANTES, CCR5, CCR2 and CX3CR1. On the basis of timing occurrence, AR episodes (grade>or= 3A) were classified in "early" (0-3 months posttransplantation; EAR) or "late" outcomes (4-12 months posttransplantation; LAR).

RESULTS

The incidences of EAR and LAR were 57.6% and 41%, respectively. Number of LAR episodes was significantly higher in subjects that have already experienced one or more EAR episodes, as compared to subjects that had no EAR (median [25%-75%]: 4 () vs. 1 [1-2.5] respectively; P<0.0001). Statistical univariate analysis showed that none of the mentioned polymorphisms were correlated with EAR or LAR. However, allele-allele association analysis showed that subjects carrying both the CX3CR1 249I allele and CCR5 No-E haplotypes were significantly at lower risk of experiencing EAR (OR=0.2 [95%-CI=0.1-0.5], P=0.001). In contrast subjects carrying both the CCR5 E haplotype and the RANTES -403A allele were significantly at higher risk to develop LAR (OR=8.1 [95%-CI=2.3-28.7], P=0.002).

CONCLUSIONS

This exploratory study in heart transplantation suggests that the outcomes of EAR and LAR episodes may be influenced by genetic variant interactions such as "CX3CR1 249I*CCR5 No-E" and "CCR5 E*RANTES -403A."

The role of CC and CXC chemokines in cardiac allograft rejection in rats

Acute cellular rejection is due in part to an upregulation of chemokine genes, resulting in eventual cell-mediated cytotoxicity. The role of chemokines in acute cardiac allograft rejection is not fully characterized presently. These studies compared the patterns of expression for multiple chemokines in rodent cardiac allograft rejection. Allogeneic transplants were performed from Brown-Norway donors to Lewis recipients. Survival studies utilized daily administration of neutralizing antisera to MCP-1, CINC, and MIP-1alpha. Patterns of mRNA and protein expression were determined by Northern blots and immunohistochemistry. Allogeneic controls rejected at mean of 6.5 days. Neutralization of MCP-1 (10.8 days, P<0.001) and MIP-1alpha (7.5 days, P=0.004) function, but not CINC (6.2 days, P>0.05), significantly prolonged allograft survival. Message expression for the beta chemokines studied were increased by day 2 and continued to increase until day 6 just before rejection, while CINC levels did not change as dramatically after day 2. Chemokine protein levels mirrored mRNA patterns by IHC analysis. MCP-1 and MIP-1alpha appear to play regulatory roles in cardiac allograft rejection, while CINC is expressed, but not functional, in injury development. Beta chemokine activity should be studied further in hope of developing more targeted immunosuppression, or identifying specific chemokines that may be useful for immunosurveillance purposes.

Donor T-cell production of RANTES significantly contributes to the development of idiopathic pneumonia syndrome after allogeneic stem cell transplantation

Idiopathic pneumonia syndrome (IPS) is a major cause of mortality following allogeneic stem cell transplantation (allo-SCT). Clinical and experimental data support a role for conditioning-induced inflammation and alloreactive T-cell responses in IPS pathophysiology, but the mechanisms by which donor leukocytes are ultimately recruited to the lung are not fully understood. RANTES is a chemokine ligand that is up-regulated during inflammation and promotes the recruitment of T cells and macrophages to sites of tissue damage. Using a lethally irradiated murine SCT model (B6 --> B6D2F1), we evaluated the role of donor leukocyte-derived RANTES in the development of IPS. Pulmonary mRNA and protein levels of RANTES were significantly elevated in allo-SCT recipients compared to syngeneic controls and were associated with enhanced mRNA expression of CCR5 and CCR1 and with inflammatory cell infiltration into the lung. Allo-SCT with RANTES-/- donor cells significantly decreased IPS and improved survival. Combinations of allogeneic wild-type or RANTES-/- bone marrow with wild-type or RANTES-/- T cells demonstrated that the expression of RANTES by donor T cells was critical to the development of lung injury after SCT. These data reveal that donor T cells can help regulate leukocyte recruitment to the lung after allo-SCT and provide a possible mechanism through which inflammation engendered by SCT conditioning regimens is linked to allo-specific T-cell responses during the development of IPS.

CC-chemokine RANTES is increased in serum and urine in the early post-transplantation period of human renal allograft recipients

BACKGROUND

The chemokine RANTES is a potent chemoattractant for T cells and monocytes that has been shown to enhance inflammation. The aim of our study was to investigate whether RANTES is upregulated within the early post-transplantation period that may influence short-time allograft function rate.

METHODS

Serum and urine samples from transplanted renal allograft recipients (n = 17) were obtained from specimens taken for diagnostic reasons. Four patients developed biopsy-proven rejection episodes within the first month. Time course of RANTES was studied within the first 12 days after renal transplantation using ELISA technique. Data were tested for significances between patients with rejection and without rejection, compared to healthy volunteers as controls, and correlated with clinical data.

RESULTS

In the control group RANTES concentration was 37.2 +/- 2.7 ng/ml (serum) and 8.1 +/- 1.3 pg/ml (urine), respectively. In transplanted recipients serum RANTES was significantly upregulated up to 132 +/- 28 ng/ml on day 1 after transplantation and remained elevated within the first 12 days (n = 17). Time course of urine RANTES demonstrated elevated concentrations with 754 +/- 115 pg/ml on day 1 followed by an continuous decrease to 22.3 +/- 7 pg/ml on day 12 (n = 17). No significant differences could be detected between patients with rejection and without rejection episodes.

CONCLUSIONS

In contrast to data of other urinary marker molecules (like IL-6), there are no significant differences between the rejection and non-rejection group. RANTES is therefore not suitable for early detection of rejection. Nevertheless, serum and urine RANTES concentrations were highly elevated in freshly transplanted renal allograft recipients reflecting an activated immune system.

Chemokines and atherosclerosis

Atherosclerosis is an inflammatory disease of the vessel wall, characterized by the accumulation of leukocytes, especially macrophages and T-cells. Chemokines are small heparin-binding polypeptides, whose main function is to attract cells to the areas of developing inflammation. They function by ligating G-protein coupled chemokine receptors initiating different signaling cascades. In vivo and in vitro investigations showed that chemokines are produced by a variety of cells and play important roles in the development and progression of many physiological and pathological conditions including atherosclerosis. Chemokines such as MCP-1, MCP-4, MIP-1 and RANTES may mediate leukocyte trafficking to, and their retention in, the plaque while CXCL16 seems to fulfill the dual function of a chemokine and a scavenger receptor. Chemokine and chemokine receptor homologues are secreted by several viruses, which may also play a role in the pathogenesis of atherosclerosis. Expression levels and gene polymorphisms of some chemokines may become useful clinical markers of atherosclerosis and other cardiovascular diseases. Modulation of chemokines and chemokine receptors' expression as well as their signaling pathways may provide important anti-atherogenic strategies.

Heterogeneity of endothelial cells from different organ sites in T-cell subset recruitment

Chemokines and adhesion molecules play a critical role in the recruitment of leukocytes into specific organ sites. Little is known, however, regarding the repertoire of chemokines and adhesion molecules expressed within different vascular beds. In this study, we compare adhesion molecule expression, chemokine induction, and T-cell subset-endothelial interactions under defined flow conditions on resting and tumor necrosis factor (TNF)-alpha-activated murine lung endothelial cells (MLECs) and heart endothelial cells (MHECs). Our study revealed that only MHECs exhibited high constitutive VCAM-1 expression. Exposure to TNF-alpha up-regulated adhesion molecule expression and chemokine production in both MLECs and MHECs. However, high levels of Regulated on Activation Normal T cell Expressed And Secreted (RANTES) expression were detected only in TNF-alpha-activated MHECs. TNF-alpha-stimulated MLECs and MHECs both supported T-helper cell interactions under defined flow conditions. Most T cells instantaneously arrested on MHECs but exhibited a rolling phenotype on MLECs. Blocking studies revealed that T-cell arrest on MHECs was mediated by constitutive VCAM-1 and TNF-alpha-induced RANTES. These findings are consistent with the hypothesis that functional heterogeneity of endothelial cells from different sites exists and some of it is retained in vitro. Furthermore, these results provide an insight into the molecular mechanisms that may mediate T-helper cell recruitment to these organs.

T-cell mediated induction of allogeneic endothelial cell chemokine expression

BACKGROUND

The goal of the current study was to test the ability of T cells to stimulate allogeneic endothelial cells to express chemokines, particularly the T-cell recruiting factors monokine induced by interferon-gamma (Mig) and inducible protein (IP)-10.

METHODS

Lymph node cells from C57BL/6 (H-2b) recipients of C3H (H-2k) skin grafts or from naïve mice were added to monolayers of C3H-derived endothelial cell line 2F-2B. After 5 or 24 hr, the lymph node cells were removed, and RNA was prepared from the endothelial cells and tested by ribonuclease protection assay or Northern blot hybridization for endothelial cell expression of chemokines.

RESULTS

Alloantigen-primed T cells induced endothelial cell expression of regulated on activation normal T-cell expressed and secreted (RANTES), IP-10, Mig, monocyte chemotactic protein-1, macrophage inflammatory protein-1alpha, and macrophage inflammatory protein-1beta within 5 hr of coculture. In vitro chemotaxis assays demonstrated the production of T-cell chemoattractants by the endothelial cells. With the exception of low levels of monocyte chemotactic protein-1 and RANTES, culture with naïve C57BL/6 lymph node T cells did not induce endothelial cell chemokine expression. Alloantigen-primed CD4 T cells induced endothelial expression of IP-10 and RANTES but none of the other chemokines tested, whereas primed CD8 T cells induced all of the chemokines tested. Expression of IP-10 and Mig was not induced when alloantigen-primed T cells from interferon-gamma deficient recipients of C3H skin grafts were cultured with the endothelial cells. This expression was blocked by addition of intercellular adhesion molecule-1 or lymphocyte function-associated antigen-1 specific antibodies to the cultures. CONCLUSIONS These results demonstrate the ability of alloantigen-primed CD8 T cells to quickly and directly stimulate endothelial cells to express and produce chemokines, including those recruiting T cells.

Gene expression during acute allograft rejection: novel statistical analysis of microarray data

High-throughput microarrays promise a comprehensive analysis of complex biological processes, yet their applicability is hampered by problems of reproducibility and data management. The current study examines some of the major questions of microarray use in a well-described model of allograft rejection. Using the Brown Norway to Lewis heterotopic heart transplant model, highly purified RNA was isolated from cardiac tissue at postoperative days (POD) 3, 5 and 7 and hybridized onto Affymetrix U34A microarrays. Using the log average ratio (LAR), changes in gene expression were monitored at each timepoint and p-values generated through statistical analysis. Microarray data were verified for 13 significant transcripts using RT-PCR. Of the 8800 transcripts studied, 2864 were increased on POD 3, 1418 on POD 5 and 2745 on POD 7. Verifying previous studies, many up-regulated genes appeared to be associated with the inflammatory process and graft infiltrating cells. Down-regulated transcripts included many novel molecules such as SC1 and decorin. LAR analysis provides a useful approach to analyze microarray data. Results were reproducible and correlated well with both RT-PCR and prior studies. Most importantly, these results provide new insights into the pathogenesis of acute rejection and suggest new molecules for future studies.

Chronic antagonism of Mig inhibits cellular infiltration and promotes survival of class II MHC disparate skin allografts

BACKGROUND

The goal of the current study was to test the ability of monokine induced by IFN-gamma (Mig)-specific antibodies to inhibit long-term T cell infiltration into class II major histocompatibility complex (MHC) disparate skin allografts and to test cellular and molecular changes in the graft during the rejection observed following cessation of treatment.

METHODS

C57BL/6 recipients of B6.H-2bm12 skin grafts were treated with normal rabbit serum (NRS) or rabbit Mig antiserum (Mig AS) every other day from day 7 until day 21 posttransplant and then weekly thereafter. Allografts were retrieved during the course of treatment and following cessation. Tissue sections were prepared and stained to compare infiltration by macrophages and CD4+ and CD8+ T cells and to assess collagen deposition in the grafts. RNA was prepared and tested by ribonuclease protection assay for intragraft levels of Mig, monocyte chemotactic protein-1 (MCP-1) and regulated on activation normal T-cell expressed and secreted (RANTES).

RESULTS

T cell and macrophage infiltration into allografts was inhibited and graft survival maintained as long as Mig-specific antibodies were given. Following cessation of treatment, T cells and macrophages infiltrated the allografts. In contrast to the histology of acute rejection observed in allografts from NRS-treated recipients, the resulting rejection of the allografts from Mig AS-treated recipients was accompanied by dense collagen deposition and high level expression of Mig and RANTES.

CONCLUSIONS

Mig directs T cell infiltration into B6.H-2bm12 skin allografts on C57BL/6 recipients. Delayed T cell and macrophage infiltration and rejection of the grafts following cessation of Mig AS treatment results in rejection that is histologically and molecularly distinct from acute rejection.

Role of IL-18 in acute lung inflammation

We have examined the role of IL-18 after acute lung inflammation in rats caused by intrapulmonary deposition of IgG immune complexes. Constitutive IL-18 mRNA and protein expression (precursor form, 26 kDa) were found in normal rat lung, whereas in inflamed lungs, IL-18 mRNA was up-regulated; in bronchoalveolar (BAL) fluids, the 26-kDa protein form of IL-18 was increased at 2-4 h in inflamed lungs and remained elevated at 24 h, and the "mature" protein form of IL-18 (18 kDa) appeared in BAL fluids 1-8 h after onset of inflammation. ELISA studies confirmed induction of IL-18 in inflamed lungs (in lung homogenates and in BAL fluids). Prominent immunostaining for IL-18 was found in alveolar macrophages from inflamed lungs. When rat lung macrophages, fibroblasts, type II cells, and endothelial cells were cultured in vitro with LPS, only the first two produced IL-18. Intratracheal administration of rat recombinant IL-18 in the lung model caused significant increases in lung vascular permeability and in BAL content of neutrophils and in BAL content of TNF-alpha, IL-1beta, and cytokine-induced neutrophil chemoattractant, whereas intratracheal instillation of anti-IL-18 greatly reduced these changes and prevented increases in BAL content of IFN-gamma. Intratracheal administration of the natural antagonist of IL-18, IL-18 binding protein, resulted in suppressed lung vascular permeability and decreased BAL content of neutrophils, cytokines, and chemokines. These findings suggest that endogenous IL-18 functions as a proinflammatory cytokine in this model of acute lung inflammation, serving as an autocrine activator to bring about expression of other inflammatory mediators.

Monokine induced by IFN-gamma is a dominant factor directing T cells into murine cardiac allografts during acute rejection

The use of chemokine antagonism as a strategy to inhibit leukocyte trafficking into inflammatory sites requires identification of the dominant chemokines mediating recruitment. The chemokine(s) directing T cells into cardiac allografts during acute rejection remain(s) unidentified. The role of the CXC chemokines IFN-gamma inducible protein 10 (IP-10) and monokine induced by IFN-gamma (Mig) in acute rejection of A/J (H-2(a)) cardiac grafts by C57BL/6 (H-2(b)) recipients was tested. Intra-allograft expression of Mig was observed at day 2 posttransplant and increased to the time of rejection at day 7 posttransplant. IP-10 mRNA and protein production were 2.5- to 8-fold lower than Mig. Whereas allografts were rejected at day 7-9 in control recipients, treatment with rabbit antiserum to Mig, but not to IP-10, prolonged allograft survival up to day 19 posttransplant. At day 7 posttransplant, allografts from Mig antiserum-treated recipients had marked reduction in T cell infiltration. At the time of rejection in Mig antiserum-treated recipients (i.e., days 17-19), intra-allograft expression of macrophage-inflammatory protein-1alpha, -1beta, and their ligand CCR5 was high, whereas expression of CXCR3, the Mig receptor, was virtually absent. Mig was produced by the allograft endothelium as well as by recipient allograft-infiltrating macrophages and neutrophils, indicating the synergistic interactions between innate and adaptive immune compartments during acute rejection. Collectively, these results indicate that Mig is a dominant recruiting factor for alloantigen-primed T cells into cardiac allografts during acute rejection. Although Mig antagonism delays acute heart allograft rejection, the results also suggest that the alloimmune response circumvents Mig antagonism through alternative mechanisms.

Targeted deletion of CX(3)CR1 reveals a role for fractalkine in cardiac allograft rejection

Fractalkine (Fk) is a structurally unusual member of the chemokine family. To determine its role in vivo, we generated mice with a targeted disruption of CX(3)CR1, the receptor for Fk. CX(3)CR1(-/-) mice were phenotypically indistinguishable from wild-type mice in a pathogen-free environment. In response to antibody-induced glomerulonephritis, CX(3)CR1(-/-) and CX(3)CR1(+/+) mice had similar levels of proteinuria and injury. CX(3)CR1(-/-) and CX(3)CR1(+/+) mice also developed similar levels of disease in myelin oligodendrocyte glycoprotein-induced experimental autoimmune encephalomyelitis. We performed heterotopic MHC class I/II cardiac transplants from BALB/c mice into C57BL/6 mice. In the absence of cyclosporin A (CsA), there was no difference in graft survival time between CX(3)CR1(-/-) and CX(3)CR1(+/+) recipient mice. However, in the presence of subtherapeutic levels of CsA, graft survival time was significantly increased in the CX(3)CR1(-/-) mice. Characterization of cells infiltrating the grafts revealed a selective reduction in natural killer cells in the CX(3)CR1(-/-) recipients in the absence of CsA and a reduction in macrophages, natural killer cells, and other leukocytes in the presence of CsA. We conclude that Fk plays an important role in graft rejection. The development of CX(3)CR1 antagonists may allow reductions in the doses of immunosuppressive drugs used in transplantation.