Rantes production during development of cardiac allograft vasculopathy

Nuclear Factor Kappa B Signaling Complexes in Acute Inflammation

Significance: Nuclear factor kappa B (NF-κB) is a master regulator of the inflammatory response and represents a key regulatory node in the complex inflammatory signaling network. In addition, selective NF-κB transcriptional activity on specific target genes occurs through the control of redox-sensitive NF-κB interactions. Recent Advances: The selective NF-κB response is mediated by redox-modulated NF-κB complexes with ribosomal protein S3 (RPS3), Pirin (PIR). cAMP response element-binding (CREB)-binding protein (CBP)/p300, peroxisome proliferator-activated receptor gamma coactivator 1 alpha (PGC-1α), activator protein-1 (AP-1), signal transducer and activator of transcription 3 (STAT3), early growth response protein 1 (EGR-1), and SP-1. NF-κB is cooperatively coactivated with AP-1, STAT3, EGR-1, and SP-1 during the inflammatory process, whereas NF-κB complexes with CBP/p300 and PGC-1α regulate the expression of antioxidant genes. PGC-1α may act as selective repressor of phospho-p65 toward interleukin-6 (IL-6) in acute inflammation. p65 and nuclear factor erythroid 2-related factor 2 (NRF2) compete for binding to coactivator CBP/p300 playing opposite roles in the regulation of inflammatory genes. S-nitrosylation or tyrosine nitration favors the recruitment of specific NF-κB subunits to κB sites. Critical Issues: NF-κB is a redox-sensitive transcription factor that forms specific signaling complexes to regulate selectively the expression of target genes in acute inflammation. Protein-protein interactions with coregulatory proteins, other transcription factors, and chromatin-remodeling proteins provide transcriptional specificity to NF-κB. Furthermore, different NF-κB subunits may form distinct redox-sensitive homo- and heterodimers with distinct affinities for κB sites. Future Directions: Further research is required to elucidate the whole NF-κB interactome to fully characterize the complex NF-κB signaling network in redox signaling, inflammation, and cancer.

Impact on rats from acute intratracheal inhalation exposures to WTC dusts

Background: Studies have revealed the increased incidence of health disorders in First Responders (FR) who were at Ground Zero over the initial 72 hr after the World Trade Center (WTC) collapses. Previous studies in rats exposed to WTC dusts using exposure scenarios that mimicked FR mouthbreathing showed exposure led to altered expression of genes whose products could be involved in lung ailments. Nevertheless, it was uncertain if repeated exposures (as occurred in earliest days post-disaster) might have given rise to long-term changes in the lungs/other organs, in white blood cell (WBC) profiles, and/or systemic expression of select (mostly immune-related) proteins.Methods: To examine this, rats were exposed on 2 consecutive days (2 hr/d, intratracheal inhalation) to WTC dusts and then examined over a 1-yr period thereafter. At select times post-exposure, organ (lung, heart, liver, kidney, spleen) weights, WBC profiles, and blood levels of a variety of proteins were evaluated.Results: The study showed that over the 1-yr period, there were nominal effects on organ weights (absolute, index) as a result of the dust exposures. There were significant changes (relative to in naïve rats) in WBC profiles, with exposed rats having increased monocyte-macrophage and decreased lymphocyte percentages. The study also found that dust exposure led to significant systemic increases in many proteins, including MCP-1, RANTES, MMP-9, RAGE, and Galectin-3.Conclusions: These results provide further support for our longstanding hypothesis that the WTC dusts could potentially have acted as direct inducers of many of the health effects that have been seen in the exposed FR.

Deciphering the Contribution of γδ T Cells to Outcomes in Transplantation

γδ T cells are a subpopulation of lymphocytes expressing heterodimeric T-cell receptors composed of γ and δ chains. They are morphologically and functionally heterogeneous, innate yet also adaptive in behavior, and exhibit diverse activities spanning immunosurveillance, immunomodulation, and direct cytotoxicity. The specific responses of γδ T cells to allografts are yet to be fully elucidated with evidence of both detrimental and tolerogenic roles in different settings. Here we present an overview of γδ T-cell literature, consider ways in which their functional heterogeneity contributes to the outcomes after transplantation, and reflect on methods to harness their beneficial properties.

IL-32θ downregulates CCL5 expression through its interaction with PKCδ and STAT3

Interleukin-32 (IL-32) exists in several isoforms and plays an important role in inflammatory response. Recently, we identified a new isoform, IL-32θ, and performed a microarray analysis to identify IL-32θ-regulated genes in THP-1 myelomonocytic cells. Upon stimulating IL-32θ-expressing THP-1 cells with phorbol myristate acetate (PMA), we found that the CCL5 transcript level was significantly reduced. We confirmed the downregulation of CCL5 protein expression by using an enzyme-linked immunosorbent assay (ELISA). Because STAT3 phosphorylation on Ser727 by PKCδ is reported to suppress CCL5 protein expression, we examined whether IL-32θ-mediated STAT3 Ser727 phosphorylation occurs through an interaction with PKCδ. In this study, we first demonstrate that IL-32θ interacts with PKCδ and STAT3 using co-immunoprecipitation (Co-IP) and pulldown assay. Moreover, STAT3 was rarely phosphorylated on Ser727 in the absence of IL-32θ, leading to the binding of STAT3 to the CCL5 promoter. These results indicate that IL-32θ, through its interaction with PKCδ, downregulates CCL5 expression by mediating the phosphorylation of STAT3 on Ser727 to render it transcriptionally inactive. Therefore, similar to what we have reported for IL-32α and IL-32β, our data from this study suggests that the newly identified IL-32θ isoform also acts as an intracellular modulator of inflammation.

Array-based methods for diagnosis and prevention of transplant rejection

DNA microarray is a microhybridization-based assay that is used to simultaneously study the expression of thousands of genes, thus providing a global view of gene expression in a tissue sample. This powerful technique has been adopted by many biomedical disciplines and will likely have a profound impact on the diagnosis, treatment and prognosis of human diseases. This review article presents an overview of the application of microarray technology to the field of solid-organ transplantation.

The link between major histocompatibility complex antibodies and cell proliferation

Experimental evidence indicates that donor-specific antibodies targeting major histocompatibility complex classes I and II molecules can elicit the key features of transplant vasculopathy by acting on the graft vasculature in 3 ways: directly activating proliferative, prosurvival, and migratory signaling in the target endothelial and smooth muscle cells; increasing expression of mitogenic factors in vascular endothelial cells, creating a potential proliferative autocrine loop; and promoting recruitment of inflammatory cells that produce mitogenic factors and elicit chronic inflammation, proliferation, and fibrosis. Here, we review the experimental literature showing the complement and Fc-independent effects of major histocompatibility complex classes I and II antibodies on graft vascular cells that may directly contribute to the proliferative aspect of transplant vasculopathy.

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.

Stat3-dependent acute Rantes production in vascular smooth muscle cells modulates inflammation following arterial injury in mice

Inflammation is a key component of arterial injury, with VSMC proliferation and neointimal formation serving as the final outcomes of this process. However, the acute events transpiring immediately after arterial injury that establish the blueprint for this inflammatory program are largely unknown. We therefore studied these events in mice and found that immediately following arterial injury, medial VSMCs upregulated Rantes in an acute manner dependent on Stat3 and NF-kappaB (p65 subunit). This led to early T cell and macrophage recruitment, processes also under the regulation of the cyclin-dependent kinase inhibitor p21Cip1. Unique to VSMCs, Rantes production was initiated by Tnf-alpha, but not by Il-6/gp130. This Rantes production was dependent on the binding of a p65/Stat3 complex to NF-kappaB-binding sites within the Rantes promoter, with shRNA knockdown of either Stat3 or p65 markedly attenuating Rantes production. In vivo, acute NF-kappaB and Stat3 activation in medial VSMCs was identified, with acute Rantes production after injury substantially reduced in Tnfa-/- mice compared with controls. Finally, we generated mice with SMC-specific conditional Stat3 deficiency and confirmed the Stat3 dependence of acute Rantes production by VSMCs. Together, these observations unify inflammatory events after vascular injury, demonstrating that VSMCs orchestrate the arterial inflammatory response program via acute Rantes production and subsequent inflammatory cell recruitment.

RETRACTED: Chronic cardiac allograft rejection in mice is alleviated by inhibition of CCR5 in combination with cyclosporine A

The chemokine receptor CCR5 plays important roles in acute allograft rejection. In this study, we examined the inhibition of CCR5 in combination with the treatment with cyclosporine A (CsA) in chronic rejection in cardiac transplantation. Forty-five transplant recipients were randomized to three groups. Recipients in group A were treated with anti-CCR5 mAb and CsA, mice in group B were given anti-CCR5 mAb alone, and animals in group C were administered with only CsA. On day 45 after transplantation, the allografts were harvested and examined by immunohistologic technique and PT-PCR methods. Allografts treated with anti-CCR5 mAb and CsA showed significantly prolonged survival (44.73 ± 0.258 days, P < 0.01) as compared with CsA-treated group (37.00 ± 2.04 days). Treatment with anti-CCR5 mAb plus CsA significantly inhibited the progression of cardiac allograft vasculopathy. Our findings demonstrated that anti-CCR5 mAb in combination with CsA can prolong the survival of allograft through their cardio-protective and immunomodulative properties. Thus, combined administration of anti-CCR5 mAb and CsA may become a new therapeutic approach for the prevention of cardiac graft failure that has not been obviated by conventional immunosuppressive agents.

The role of chemokines in transplant graft arterial disease

Despite the development of effective immunosuppressive therapy, transplant graft arterial disease (GAD) remains the major limitation to long-term graft survival. Multiple immune and nonimmune risk factors contribute to this vasculopathic intimal hyperplastic process. Thus, initial interplay between host inflammatory cells and donor endothelial cells triggers alloimmune responses, whereas alloantigen-independent factors such as prolonged ischemia, surgical manipulation, ischemia-reperfusion injury, and hyperlipidemia enhance the antigen-dependent events. Intrinsic to all stages of this process are chemokines, a family of 8- to 10-kDa proteins mediating directional migration of immune cells to sites of inflammation and injury. Beyond their role in immune-cell chemotaxis, chemokines also contribute to cellular activation, vascular remodeling, and angiogenesis. Expression of chemokines and their cognate receptors in allografts correlates with acute organ rejection, as well as GAD. Moreover, chemokine or chemokine receptor blockade prolongs graft survival and attenuates GAD in experimental models. Further studies will likely confirm a substantial utility for antichemokine therapy in human organ transplantation.

Quilty in biopsy is associated with poor prognosis after heart transplantation

We tested if Quilty (endocardial infiltration of lymphocytes) in routinely processed endomyocardial biopsy is associated with poor outcome after heart transplantation (HTx). Biopsies (n=9829) harvested within the first post-transplant year from 938 patients (778 men, mean age 49 years) were evaluated for Quilty and acute cellular rejection (according to the International Society for Heart and Lung Transplantation, ISHLT, classification). Transplant vasculopathy was evaluated by coronary angiography, and severe stenosis was found in 19% of patients. Survival was tested by Kaplan-Meier and Cox regression analyses for all-cause mortality and major cardiac events (lethal acute cellular rejection, graft loss or myocardial infarction). We found 1840 (19%) Quilty-positive biopsies in 487 Quilty-positive patients (52%). Quilty was more prevalent in women (p=0.038) and younger men (p=0.001), and was correlated with ISHLT grade 1R (OR 1.45, 95% CI 1.36-1.55; p<0.001) and ISHLT grade 2R (OR 2.48, 95% CI 2.21-3.41; p<0.001). Quilty in any biopsy was associated with a higher all-cause mortality (log rank p=0.045) due to a higher risk for major cardiac event (p=0.0001). Multivariate regression analysis showed Quilty (RR 1.69, 95%CI 1.05-2.73) and transplant vasculopathy (RR 2.78, 95%CI 1.68-4.61) as risk factors for major cardiac events and treated hyperlipidemia as lowering the risk for major cardiac events (RR 0.47, 95%CI 0.28-0.77). Quilty is associated with graft loss and poor outcome post HTx. Index biopsy during the first post-transplant year is a useful tool to identify patients at risk and is recommended during routine post-transplant management.

T cells in cardiac allograft vasculopathy are skewed to memory Th-1 cells in the presence of a distinct Th-2 population

Cardiac allograft vasculopathy (CAV) in heart transplantation (HTx) patients remains the major complication for long-term survival, due to concentric neointima hyperplasia induced by infiltrating mononuclear cells (MNC). Previously, we showed that activated memory T-helper-1 (Th-1) cells are the major component of infiltrating MNC in coronary arteries with CAV. In this study, a more detailed characterization of the MNC in human coronary arteries with CAV (n = 5) was performed and compared to coronary arteries without CAV (n = 5), by investigating MNC markers (CD1a, DRC-1, CD3, CD20, CD27, CD28, CD56, CD68, CD69, FOXP3 and HLA-DR), cytokines (IL-1A, 2, 4, 10, 12B, IFN-gamma, and TGF-beta1), and chemokine receptors (CCR3, CCR4, CCR5, CCR7, CCR8, CXCR3 and CX3CR1) by immunohistochemical double-labeling and quantitative PCR on mRNA isolated from laser microdissected layers of coronary arteries. T cells in the neointima and adventitia of CAV were skewed toward an activated memory Th-1 phenotype, but in the presence of a distinct Th-2 population. FOXP3 positive T cells were not detected and production of most cytokines was low or absent, except for IFN-gamma, and TGF-beta. This typical composition of T-helper cells and especially production of IFN-gamma and TGF-beta may play an important role in the proliferative CAV reaction.

Genetic control of chemokines in severe human internal carotid artery stenosis

BACKGROUND AND PURPOSE

Atherosclerosis is an inflammatory disease. Chemokines and chemokine receptors are known to be involved in atherogenesis. Common single nucleotide polymorphisms (SNPs) affect transcription in response to inflammatory stimuli. The aim of this study was to evaluate the correlations between MCP-1, RANTES, SDF-1, CCR2, and CCR5 gene polymorphisms with increased risk of internal carotid artery (ICA) stenosis.

METHODS

Hundred and twelve patients, consecutively recruited for ICA occlusive disease, and 282 controls were genotyped for MCP-1-2518G, RANTES-403A, CCR5Delta32, CCR2 V64I, and SDF-1-801A polymorphisms.

RESULTS

The frequency of the SDF-1A allele was significantly different between cases and controls: 0.32 vs. 0.20, respectively (OR 1.81; 95% CI 1.25-2.60; p=0.007). The frequency of the RANTES-403G allele was significantly higher in patients with stenosis >70% (OR, 2.45; 95% CI 1.12-5.71; p=0.015). No significant differences were observed with the other polymorphisms.

CONCLUSION

The reported results seem to correlate the polymorphisms of the genes encoding for SDF-1, RANTES with pathogenesis and progression of ICA occlusive disease. Although suggestive, these results need confirmation in prospective cross-sectional studies.

Macrophage depletion suppresses cardiac allograft vasculopathy in mice

Cardiac allograft vasculopathy (CAV) is a major source of late posttransplant mortality. Although numerous cell types are implicated in the pathogenesis of CAV, it is unclear which cells actually induce the vascular damage that results in intimal proliferation. Because macrophages are abundant in CAV lesions and are capable of producing growth factors implicated in neointimal proliferation, they are leading end-effector candidates. Macrophages were depleted in a murine heterotopic cardiac transplant system known to develop fulminant CAV lesions. C57BL/6 hearts were transplanted into (C57BL/6 x BALB/c)F(1) recipients, which then received anti-macrophage therapy with intraperitoneal carrageenan or i.v. gadolinium. Intraperitoneal carrageenan treatment depleted macrophages by 30-80% with minimal effects upon T, B or NK cells as confirmed by flow cytometry and NK cytotoxicity assays. Carrageenan treatment led to a 70% reduction in the development of CAV, as compared to mock-treated controls (p = 0.01), which correlated with the degree of macrophage depletion. Inhibition of macrophage phagocytosis alone with gadolinium failed to prevent CAV. Macrophages may represent the end-effector cells in a final common pathway towards CAV independent of T-cell or B-cell alloreactivity and exert their injurious effects through mechanisms related to cytokine/growth factor production rather than phagocytosis.

CCR5 Blockade Modulates Inflammation and Alloimmunity in Primates

Pharmacologic antagonism of CCR5, a chemokine receptor expressed on macrophages and activated T cells, is an effective antiviral therapy in patients with macrophage-tropic HIV infection, but its efficacy in modulating inflammation and immunity is only just beginning to be investigated. In this regard, the recruitment of CCR5-bearing cells into clinical allografts is a hallmark of acute rejection and may anticipate chronic rejection, whereas conventionally immunosuppressed renal transplant patients homozygous for a nonfunctional Delta32 CCR5 receptor rarely exhibit late graft loss. Therefore, we explored the effects of a potent, highly selective CCR5 antagonist, Merck's compound 167 (CMPD 167), in an established cynomolgus monkey cardiac allograft model. Although perioperative stress responses (fever, diminished activity) and the recruitment of CCR5-bearing leukocytes into the graft were markedly attenuated, anti-CCR5 monotherapy only marginally prolonged allograft survival. In contrast, relative to cyclosporine A monotherapy, CMPD 167 with cyclosporine A delayed alloantibody production, suppressed cardiac allograft vasculopathy, and tended to further prolong graft survival. CCR5 therefore represents an attractive therapeutic target for attenuating postsurgical stress responses and favorably modulating pathogenic alloimmunity in primates, including man.

Vascular Remodeling in Transplant Vasculopathy

As therapeutic strategies to prevent acute rejection progressively improve, transplant vasculopathy (TV) constitutes the single most important limitation for long-term functioning of solid organ allografts. In TV, allograft arteries characteristically develop severe, diffuse intimal hyperplastic lesions that eventually compromise luminal flow and cause ischemic graft failure. Traditional immunosuppressive strategies that check acute allograft rejection do not prevent TV; indeed 50% of transplant recipients will have significant disease within five years of organ transplantation, and 90% will have significant TV a decade after their surgery. TV can involve the entire length of the transplanted arterial bed, including penetrating intraorgan arterioles. Indeed, the luminal narrowing of such penetrating vessels may be the most functionally significant because arterioles represent the major contributors to tissue vascular resistance. Because of the diffuseness of TV involvement in the allograft vascular bed, the only currently definitive therapy requires re-transplantation. Nevertheless, as we better understand the pathogenesis and critical mediators of these lesions, pharmacological advances can be anticipated. Other articles in this thematic review series focus on the specifics of the inciting injury, the cytokines and chemokines that drive TV development, and the nature of the recruited cells in TV lesions, as well as the pathogenic similarities between TV and other vascular lesions such as atherosclerosis. This review focuses on the mechanisms of vascular wall remodeling in TV, including the intimal accumulation of smooth muscle-like cells and associated extracellular matrix, medial smooth muscle cell degeneration, and adventitial fibrosis. A brief overview highlights the aneurysmal changes that can accrue when vessel wall inflammation has a cytokine profile distinct from the typical proinflammatory interferon-gamma-dominated milieu.

Deletion of the chemokine receptor CCR1 prolongs corneal allograft survival

PURPOSE

Many corneal grafts undergo immune rejection, and current therapies are associated with many side effects. The purpose of this study was to identify critical chemokine pathways involved in generating the alloimmune response to corneal transplants.

METHODS

Orthotopic corneal transplantation was performed in fully mismatched strains. Cytokine and chemokine receptor gene expression was determined by the RNase protection assay. Knockout (KO) strains for chemokine-chemokine receptors that are upregulated after transplantation underwent corneal transplantation. Results derived from KO murine hosts were compared with cyclosporine (Cy) therapy. In addition to graft survival, graft infiltration, allospecific delayed-type hypersensitivity (DTH), and cytokine expression were compared among the recipient groups.

RESULTS

Initial experiments revealed gene upregulation of the chemokine receptors CCR1, -2, and -5 after corneal allorejection. Although CCR1 KO hosts showed a significant increase in graft survival compared with wild-type (WT) hosts, allografts in CCR5, CCR2/CCL3(MIP-1alpha), CXCR3, CXCL10/IP-10, and CCL3/MIP-1alpha KO mice did not show a significant improvement in graft survival. Further, CCR1 KO hosts showed a significantly higher survival rate than with systemic Cy therapy in WT hosts. Moreover, graft infiltration by leukocytes and gene expression of proinflammatory cytokines were reduced in CCR1 KO mice compared with both Cy treated and untreated WT mice, as was the induction of allospecific DTH.

CONCLUSIONS

These studies provide, for the first time, evidence that targeting of specific chemokine pathways can significantly promote survival of corneal transplants, and suggest that select deletion or suppression of CCR1 can be a useful therapeutic target in corneal transplant immunity.

Janus kinase 3 inhibition with CP-690,550 prevents allograft vasculopathy

Janus kinase 3 (JAK3) mediates signal transduction from cytokine receptors using the common gamma chain. The rationally designed inhibitor of JAK3, CP-690,550, prevents acute allograft rejection in rodents and in nonhuman primates. Here we investigated the ability of CP-690,550, to prevent allograft vasculopathy in a rodent model of aorta transplantation. Aortas from AxC Irish (RT1(a)) or Lewis (RT1(l)) rats were heterotopically transplanted into the infra-renal aorta of Lewis recipients and harvested at 28 or 56 days. Treated recipients received CP-690,550 by osmotic pumps (mean drug exposure of 110 +/- 38 ng/ml). Significant intimal hyperplasia was demonstrated in untreated allografts when compared with isografts at 28 days (2.08 +/- 0.85% vs. 0.43 +/- 0.2% luminal obliteration, respectively, P = 0.001) and 56 days (5.3 +/- 2.4% vs. 0.38 +/- 0.3%, P = 0.002). Treatment caused a 51% reduction in intimal hyperplasia at day 56. CP-690,550-treated animals also had a significant reduction of donor-specific IgG production and of the gene expression for suppressor of cytokine signaling-3 and with unchanged levels of expression of RANTES, IP-10 and transforming growth factor-beta1. These results are the first to show that JAK3 blockade by CP-690,550 effectively prevents allograft vasculopathy in this rat model of aorta transplantation.

The Chemokine and Chemokine Receptor Profile of Infiltrating Cells in the Wall of Arteries With Cardiac Allograft Vasculopathy Is Indicative of a Memory T–Helper 1 Response

BACKGROUND

Despite improvement in short-term patient survival after heart transplantation (HTx), long-term survival rates have not improved much, mainly because of cardiac allograft vasculopathy (CAV). Cytokines and chemokines are considered to play an important role in CAV development.

METHODS AND RESULTS

We focused on coronary arteries of HTx patients and made an inventory of the infiltrating cells and the expression of cytokines as well as chemokines and chemokine receptors (C+CR) in the different layers of the vessel wall with CAV. Tissue slides were stained for a variety of cell markers (CD3, CD4, CD8, CD20, CD68, CD79a), chemokines (monokine induced by interferon [MIG], interferon-inducible protein 10 [IP-10], interferon-inducible T cell-alpha chemoattractant [ITAC], RANTES [regulated on activation normal T cell expressed and secreted], and fractalkine), and chemokine receptors (CXCR3, CCR5, and CX3CR1). In reference coronary arteries (not transplanted), almost no infiltrating cells were found, and in transplanted hearts with CAV (HTx+CAV), a large number of T cells were observed (CD4:CD8=2:1), mainly localized in the neointima and adventitia. Most of these T cells appeared to be activated (human leukocyte antigen DR positive). Coronary arteries from transplanted hearts without CAV (HTx-CAV), HTx+CAV, and references were also analyzed for cytokine and C+CR mRNA expression with the use of quantitative polymerase chain reaction. Interferon-gamma was highly expressed in HTx+CAV compared with HTx-CAV. Interleukin-4 and interleukin-10 were expressed at the same level in both HTx groups and references. In HTx+CAV, all C+CR, but especially the T-helper 1 (TH1) C+CR, were more abundant than in the HTx-CAV and references. However, TH2 CCR4 expression did not differ significantly between both HTx groups.

CONCLUSIONS

In coronary arteries with CAV, most T cells are CD4+ and express human leukocyte antigen DR. These activated TH cells are mainly memory TH1 cells on the basis of their C+CR profile and cytokine expression.

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.

Protective effect of carbon monoxide in transplantation

During the last decades due to the development of new immunosuppressive agents and improvements in organ preservation methods, surgical techniques, and postoperative care, organ transplantation has become an ultimate therapeutic option for irreversible organ failure. Early graft survival has significantly improved; however, the long-term outcome remains unsatisfactory. Multiple factors, both immunogenic and non-immunogenic etiologies, are involved in the deterioration of the allografts, and the recent use of expanded criteria donors to overcome the organ shortage may also contribute to the graft losses. Carbon monoxide (CO) is commonly viewed as a poison in high concentrations due to its ability to interfere with oxygen delivery. However, CO is endogenously produced in the body as a byproduct of heme degradation by the heme oxygenase (HO) and has recently received notable attention as a gaseous regulatory molecule. In fact, an augmentation of endogenous CO by induction of HO-1 or exogenously added CO is known to have potent cytoprotective effects in various disease models. Several recent reports have demonstrated that CO provides potent cytoprotective effects in the field of organ and cell transplantation. CO is able to prevent ischemia/reperfusion injury, allograft rejection, and xenograft rejection via its anti-inflammatory, anti-apoptotic and anti-proliferation effects, suggesting that CO might be a valuable therapeutic option in the field of transplantation. Based on the recent advancement of our understanding of CO as a new therapeutic molecule, this review attempts to summarize the functional roles as well as biological and molecular mechanisms of CO in transplantation and discusses potential CO application to the clinical transplant setting.

Cytokines in Atherosclerosis: Pathogenic and Regulatory Pathways

Atherosclerosis is a chronic disease of the arterial wall where both innate and adaptive immunoinflammatory mechanisms are involved. Inflammation is central at all stages of atherosclerosis. It is implicated in the formation of early fatty streaks, when the endothelium is activated and expresses chemokines and adhesion molecules leading to monocyte/lymphocyte recruitment and infiltration into the subendothelium. It also acts at the onset of adverse clinical vascular events, when activated cells within the plaque secrete matrix proteases that degrade extracellular matrix proteins and weaken the fibrous cap, leading to rupture and thrombus formation. Cells involved in the atherosclerotic process secrete and are activated by soluble factors, known as cytokines. Important recent advances in the comprehension of the mechanisms of atherosclerosis provided evidence that the immunoinflammatory response in atherosclerosis is modulated by regulatory pathways, in which the two anti-inflammatory cytokines interleukin-10 and transforming growth factor-β play a critical role. The purpose of this review is to bring together the current information concerning the role of cytokines in the development, progression, and complications of atherosclerosis. Specific emphasis is placed on the contribution of pro- and anti-inflammatory cytokines to pathogenic (innate and adaptive) and regulatory immunity in the context of atherosclerosis. Based on our current knowledge of the role of cytokines in atherosclerosis, we propose some novel therapeutic strategies to combat this disease. In addition, we discuss the potential of circulating cytokine levels as biomarkers of coronary artery disease.

Chemokines and their receptors: roles in specific clinical conditions and measurement in the clinical laboratory

Considerable progress has been achieved in our knowledge of the function of the chemokine system and in understanding its role in the pathophysiology of human diseases. This complex system, presently including approximately 50 cytokines and 20 receptors, coordinates leukocyte recruitment in a variety of human diseases, ranging from infectious and inflammatory diseases to cancer. A large body of literature has been published describing various assays for the measurement of chemokines in biologic fluids and tissues. We review information available on the role of chemokines in selected human diseases and provide examples of clinical situations in which chemokine determination might be of practical value, and we describe the currently available assays for their measurement.

CXCL9 antagonism further extends prolonged cardiac allograft survival in CCL19/CCL21-deficient mice

CCL19/MIP-3beta and CCL21/SLC are essential for chemotactic recruitment of mature dendritic cells (DC) to T-cell areas of secondary lymphoid tissue. Paucity of lymph node T-cells (plt/plt) mice lack CCL21-serine (ser) and CCL19 expression. We tested plt/plt and wild type (wt) BALB/c (H2d) mice as recipients of heart or skin allografts from C57BL/10J (H2b) donors. Donor DC trafficking to secondary lymphoid tissue was markedly reduced in plt heart but not skin allograft recipients. Heart, but not skin grafts survived significantly longer in plt recipients. Accordingly, T cells from plt heart transplant recipients demonstrated poor anti-donor responses in ex vivo MLR, compared to wt heart or wt and plt skin recipients. Moreover, donor-reactive T cells from plt heart recipients exhibited Th2-skewing in comparison to T cells from wt heart or skin graft recipients. Anti-CXCL9/Mig was administered for 2 weeks post-transplant to determine whether impairment of activated T-cell migration could further prolong cardiac allograft survival in plt recipients. CXCL9-antagonism extended graft survival significantly only in plt mice, likely due, in part, to retention of alloactivated T cells in secondary lymphoid tissue/reduction of graft-infiltrating T cells. Thus, targeting DC and activated T-cell migration concomitantly has additive effects in prolonging heart graft survival with potential for therapeutic application.

A novel small-molecule compound targeting CCR5 and CXCR3 prevents acute and chronic allograft rejection

BACKGROUND

Chemokines and chemokine receptors are critical in leukocyte recruitment, activation, and differentiation. Among them, CC chemokine receptor 5 (CCR5) and CXC chemokine receptor 3 (CXCR3) have been reported to play important roles in alloimmune responses and may be potential targets for posttransplant immunosuppression.

METHODS

Fully major histocompatibility complex (MHC)-mismatched murine cardiac and islet transplant models were used to test the effect in vivo of a novel, small-molecule compound TAK-779 by targeting CCR5 and CXCR3 in acute allograft rejection. An MHC class II mismatched cardiac transplant model was used to evaluate its efficacy in chronic allograft rejection. Intragraft expression of cytokines, chemokines, and chemokine receptors was measured by quantitative real-time polymerase chain reaction and by histological analysis.

RESULTS

Treatment of TAK-779 significantly prolonged allograft survival across the MHC barrier in two distinct transplant models. The treatment downregulated local immune activation as observed by the reduced expression of several chemokines, cytokines, and chemokine receptors. Thereby, the recruitment of CD4, CD8, and CD11c cells into transplanted allografts were inhibited. Furthermore, TAK-779 treatment significantly attenuated the development of chronic vasculopathy, fibrosis, and cellular infiltration.

CONCLUSIONS

Antagonism of CCR5 and CXCR3 has a substantial therapeutic effect on inhibiting both acute and chronic allograft rejection. CCR5 and CXCR3 are functional in the process of allograft rejection and may be potential targets in clinical transplantation in the future.

Effect of cis-resveratrol on genes involved in nuclear factor kappa B signaling

This study investigated for the first time the effects of the cis isomer of RESV (c-RESV), a polyphenol present in red wine, on an array of genes whose expression is controlled by nuclear factor kappa B (NF-kappaB) and whose transcriptional activation is critical in a number of pathologies (including some cardiovascular diseases). In inflammatory peritoneal macrophages stimulated with lipopolysaccharide (LPS) and gamma interferon (IFN-gamma), c-RESV significantly blocked the expression of genes related to the REL/NF-kappaB/IkappaB family, adhesion molecules and acute-phase proteins; however, the greatest modulatory effect was obtained on the expression of genes related to the pro-inflammatory cytokines. c-RESV down-regulated the nuclear factor of kappa light chain gene enhancer in B-cells 1 (NFkappaBL1) gene product p105 and up-regulated the nuclear factor of kappa light chain gene enhancer in B-cells inhibitor alpha (IkappaBalpha) gene. c-RESV also significantly inhibited intercellular adhesion molecule-1 (ICAM-1) gene expression and the transmembrane receptors RIP (receptor TNFRSF) and TLR3 (toll-like receptor 7). At 100 muM, c-RESV significantly inhibited transcription of Scya2 (chemokine MCP-1), the chemokine RANTES (regulated on activation, normal T cell expressed and secreted), pro-inflammatory cytokines that attract monocyte-granulocyte cells such as M-CSF (colony-stimulating factor 1), GM-CSF (colony-stimulating factor 2) and G-CSF (colony-stimulating factor 3), the cytokine tumor growth factor beta (TGF-beta) and the extracellular ligand IL-1alpha. In contrast, c-RESV stimulated transcription of the pro-inflammatory cytokines IL-6 and tumor necrosis factor alpha (TNF-alpha), the extracellular ligand IL-1beta, and the IFN regulatory factor (IRF)-1. In conclusion, c-RESV has a significant modulatory effect on the NF-kappaB signaling pathway and, consequently, an important antioxidant role that may partially explain the cardioprotective effects attributed to long-term moderate red wine consumption.

Chemokine gene expression during allograft rejection: Comparison of two quantitative PCR techniques

The ability to analyse expression of genes rapidly in small samples of tissue is essential for the clinical assessment of many conditions, including the onset of rejection after transplantation. Chemokines have been shown to play a critical role in leukocyte recruitment to transplanted organs and in leukocyte localisation within tissues and antagonism of certain chemokines or chemokine receptors, identified as being up-regulated during allograft rejection, it has been shown to delay leukocyte infiltration into the graft and to prolong graft survival. The analysis of chemokine and chemokine receptor expression in allografts after transplantation may therefore be a useful early indicator of the onset of rejection. RT-PCR techniques are the most sensitive for the detection of low abundance mRNA when the amount of tissue sample is limited. Here we compared competitive-quantitative RT-PCR (CQ-PCR) with real-time PCR for the sequential quantification of chemokine transcripts after transplantation of a fully MHC mismatched mouse cardiac allograft. Although CQ-PCR was found to be an accurate and sensitive technique, real-time PCR was more sensitive and reproducible. Despite the reproducibility, differences in sensitivity between the two techniques were high. Real-time PCR avoids hazardous post-PCR manipulations thereby decreasing the potential risk of sample contamination, and offers the advantage that several genes can be analysed from small tissue samples in a shorter period of time, a key parameter for graft biopsy samples. Real-time PCR was therefore used to extend the analysis of intragraft mRNA chemokine expression levels. Expression of CXCL5 and CCL2 was found to be independent of T cell infiltration while intragraft expression of CCL3, CCL4, CCL5, CXCL9, CXCL10, XCL1 and CCL1 was clearly T cell dependent and increased significantly with time after transplantation. Overall, real-time PCR analysis showed that chemokine gene expression during rejection is clearly distinct from that in non-rejecting syngeneic grafts and is altered by the onset of infiltration of alloantigen-reactive T cells into the graft.

Roles of an IkappaB kinase-related pathway in human cytomegalovirus-infected vascular smooth muscle cells: a molecular link in pathogen-induced proatherosclerotic conditions

Viral and bacterial pathogens have long been suspected to affect atherogenesis directly. However, mechanisms linking innate immunity to chronic inflammatory diseases such as atherosclerosis are still poorly defined. Here we show that infection of primary human aortic smooth muscle cells (HAOSMC) with human cytomegalovirus (HCMV) leads to activation of the novel IkappaB kinase (IKK)-related kinase, Tank-binding kinase-1 (TBK1), a major effector of the cellular innate immune response. We demonstrate that part of the HCMV inflammatory response is most likely mediated via this novel kinase because the canonical IKK complex was only poorly activated upon infection of HAOSMC. An increase in TBK1 phosphotransferase activity led to a strong activation of the interferon regulatory factor (IRF)-3 transcription factor as measured by its C-terminal phosphorylation, dimerization, and DNA binding activity. In addition to TBK1, HAOSMC also express another IKK-related kinase isoform, IKKepsilon, albeit at a lower level. Nevertheless, both isoforms were required for full activation of IRF-3 by HCMV. The transcripts of proatherosclerotic genes Ccl5 (encoding for the chemokine RANTES (regulated upon activation, normal T cell expressed and secreted)) and Cxcl10 (encoding for the chemokine IP-10 (interferon-gamma-inducible protein 10)) were induced in an IRF-3-dependent manner after HCMV infection of smooth muscle cells. In addition, cytokine arrays analysis showed that RANTES and IP-10 were the predominant chemokines present in the supernatant of HCMV-infected HAOSMC. Activation of the TBK1/IRF-3 pathway was independent of epidermal growth factor receptor and pertussis toxin-sensitive G protein-coupled receptor activation. Our results thus add additional molecular clues to a possible role of HCMV as a modulator of atherogenesis through the induction of a proinflammatory response that is, in part, dependent of an IKK-related kinase pathway.

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.

Statins in solid organ transplantation: is there an immunosuppressive effect?

Cardiac allograft vasculopathy is one of the major causes of mortality late after heart transplantation. This disease process occurs to a lesser extent in patients with other donor organs; however, a long-term graft dysfunction is similarly described in kidney, liver and lung transplant recipients. There are multiple immune and nonimmune risk factors associated with this vasculopathic disease process, one of which includes hyperlipidemia. Use of lipid lowering agents, specifically HMG-CoA reductase inhibitors (statins) was initially reported to have possible immunosuppressive effects in a single center study of heart transplant recipients. This has not been observed in kidney transplant recipients; however, a large randomized trial demonstrated a significant cardiovascular risk reduction in fluvastatin-treated kidney transplant patients, outcome similar to the numerous nontransplant clinical trials of statins in atherosclerosis. In two recent in vitro studies, statins have been reported to repress induction of MHC-II by interferon-gamma and selectively block leukocyte function antigen-1, both of which decrease T-lymphocyte activation. In conclusion, statins appear to have outcome benefits in heart and kidney transplant patients; however, firm evidence for a clinical immunosuppressive effect is lacking. Further studies in humans will be needed to demonstrate this potential effect of statins. Overall, the outcome benefits of statins from the heart and kidney clinical studies provide a firm rationale to support the use of statins in organ transplantation.

Antagonism of RANTES Receptors Reduces Atherosclerotic Plaque Formation in Mice

Increasing evidence supports the involvement of inflammation in the early phases of atherogenesis. Recruitment of leukocytes within the vascular wall, controlled by chemokines, is an essential process in the development of this common disease. In this study, we report that blocking a chemokine pathway in vivo with the CC chemokine antagonist Met-RANTES reduces the progression of atherosclerosis in a hypercholesterolemic mouse model. The reduction of lesions was correlated with a diminution of expression of several major chemokines and chemokine receptors, a decrease in leukocyte infiltration, and an increase of collagen-rich atheroma, features associated with stable atheroma. Treatment was well tolerated and serum lipid profiles were not affected. Whereas genetically engineered mice with deletion of either a CC chemokine or its receptor have demonstrated resistance to disease, to our knowledge, this is the first demonstration that treatment with a chemokine receptor antagonist limits the progression of atherosclerosis in vivo. Thus, our findings indicate that blockade of chemokine receptor/ligand interactions might become a novel therapeutic strategy to reduce the evolution of this common disease.

Combined blockade of the chemokine receptors CCR1 and CCR5 attenuates chronic rejection

BACKGROUND

Chemokine-chemokine receptor interaction and the subsequent recruitment of T-lymphocytes to the graft are early events in the development of chronic rejection of transplanted hearts or cardiac allograft vasculopathy (CAV). In this study, we sought to determine whether blockade of chemokine receptors CCR1 and CCR5 with Met-RANTES affects the development of CAV in a murine model.

METHODS AND RESULTS

B6.CH-2(bm12) strain donor hearts were transplanted heterotopically into wild-type C57BL/6 mice (myosin heavy chain II mismatch). Recipients were treated daily with either Met-RANTES or vehicle starting on postoperative day 4 and were euthanized on postoperative days 24 and 56. We found that Met-RANTES significantly reduced intimal thickening in this model of chronic rejection and that Met-RANTES markedly decreased the infiltration of CD4 and CD8 T lymphocytes and MOMA-2+ monocytes/macrophages into transplanted hearts. Met-RANTES also suppressed the ex vivo and in vitro proliferative responses of recipient splenocytes to donor antigens. Finally, Met-RANTES treatment was associated with a marked reduction in RANTES/CCL5 and monocyte chemoattractant protein-1 gene transcript levels in the donor hearts.

CONCLUSIONS

Antagonism of the chemokine receptors CCR1 and CCR5 with Met-RANTES attenuates CAV development in vivo by reducing mononuclear cell recruitment to the transplanted heart, proliferative responses to donor antigens, and intragraft RANTES/CCL5 and monocyte chemoattractant protein-1 gene transcript levels. These findings suggest that chemokine receptors CCR1 and CCR5 play significant roles in the development of chronic rejection and may serve as potential therapeutic targets.

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.

Coronary artery vasculopathy in pediatric cardiac transplant patients: the therapeutic potential of immunomodulators

The single largest cause of late graft loss in pediatric cardiac transplantation is transplant coronary artery vasculopathy (CAV). The mechanism of CAV remains unknown; it appears to have both immune and non-immune causes. The final common pathway of these mechanisms is endothelial activation, a prothrombotic environment, and endothelial damage with subsequent diffuse intimal proliferation. The disease process has largely been thought to be progressive and unresponsive to treatment. Re-transplantation has been advocated as the only definitive treatment. The appropriate management is largely unknown; intervention or surgical management has had limited utility, while medical management appears to have the most promise. Improvement in outcome can be achieved by optimizing non-immune factors and aggressive management of the immune mechanisms. Long-term survival of transplant patients after diagnosis with CAV is now being reported.

Direct Anti-Inflammatory Mechanisms Contribute to Attenuation of Experimental Allograft Arteriosclerosis by Statins

BACKGROUND

Despite the development of effective immunosuppressive therapy, transplant graft arterial disease (GAD) remains the major limitation to long-term graft survival. The interplay between host inflammatory cells and donor vascular wall cells results in an intimal hyperplastic lesion, which leads to ischemia and graft failure. HMG-CoA reductase inhibitors (statins) reduce GAD in human cardiac allografts, although it is unclear whether this is secondary to cholesterol lowering or other mechanisms. This study tested the hypothesis that statins can suppress GAD by cholesterol-independent pathways.

METHODS AND RESULTS

We performed heterotopic murine cardiac transplants in total allogeneic or major histocompatibility complex class II-mismatched combinations. Transplanted animals received either control chow, chow containing 25 ppm cerivastatin (low dose), or chow containing 125 ppm cerivastatin (high dose). Mean plasma cerivastatin concentrations were 0.0 (control), 10.1 (low dose), and 21.9 (high dose) nmol/L, respectively. Plasma cholesterol levels were the same in all groups. GAD scores decreased in low-dose (P<0.05) and high-dose (P<0.0001) cerivastatin groups compared with controls, with concomitant reduction in graft-infiltrating cells and significantly decreased intragraft RANTES and monocyte chemotactic protein-1 mRNA expression. Cerivastatin, as well as other statins, also reduced RANTES and monocyte chemotactic protein-1 production in mouse endothelial cells stimulated with interferon-gamma and tumor necrosis factor-alpha in vitro.

CONCLUSIONS

Clinically achievable levels of an HMG-CoA reductase inhibitor attenuate GAD in murine heart transplants, diminish host inflammatory cell recruitment, and do not alter cholesterol levels. These results indicate that statins can affect arterial biology and inflammation independently of their effects on cholesterol metabolism.

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.

The role of MIG/CXCL9 in cardiac allograft vasculopathy

T lymphocytes play a critical role in chronic rejection of transplanted hearts, or cardiac allograft vasculopathy (CAV). However, the molecular mediators of T lymphocyte recruitment in CAV are incompletely defined. We hypothesized that the chemokine, monokine induced by interferon-gamma (MIG/CXCL9), which induces T lymphocyte migration in vitro, participates in T lymphocyte recruitment in CAV. In a previously characterized MHC II-mismatched murine model of CAV, intragraft MIG/CXCL9 gene transcript and protein levels increased on days 7, 14, and 24 days after transplantation, paralleling T lymphocyte recruitment and preceding intimal thickening. Antibody neutralization of MIG/CXCL9 significantly reduced CD4(+) T lymphocyte infiltration and intimal thickening in this model. MIG/CXCL9 was produced by graft-infiltrating MOMA-2+ macrophages in early and late stages of CAV. And, although T lymphocytes did not produce MIG/CXCL9, recipient CD4(+) T lymphocytes were required for sustained intragraft MIG/CXCL9 production and CAV development. These findings demonstrate that 1) MIG/CXCL9 plays an important role in CD4(+) T lymphocyte recruitment and development of CAV, 2) MOMA-2+ macrophages are the predominant recipient-derived source of MIG/CXCL9, and 3) recipient CD4 lymphocytes are necessary for sustained MIG/CXCL9 production and CAV development in this model. Neutralization of the chemokine MIG/CXCL9 may have therapeutic potential for the treatment of chronic rejection after heart transplantation.

Chemokines: directing leukocyte infiltration into allografts

Chemokines have been shown to play a critical role in the recruitment of leukocytes to transplanted organs. Animal models and clinical studies have demonstrated predictable temporal and spatial correlations between chemokine production and leukocyte infiltration into allografts. Antagonism of chemokines or chemokine receptors has been shown to delay leukocyte infiltration and prolong graft function, demonstrating an important role for chemokines in allograft rejection.

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.

Chemokines, their receptors, and transplant outcome

Organ transplant rejection is mediated largely by circulating peripheral leukocytes induced to infiltrate the graft by various inflammatory stimuli. Of these, chemotactic cytokines called chemokines, expressed by inflamed graft tissues, as well as by early innate-responding leukocytes that infiltrate the graft, are responsible for the recruitment of alloreactive leukocytes. This report discusses the impact of these leukocyte-directing proteins on transplant outcome and novel therapeutic approaches for antirejection therapy based on targeting of chemokines and/or their receptors.