Intrapulmonary production of RANTES during rejection and CMV pneumonitis after lung transplantation

Screening and identification of key regulatory connections and immune cell infiltration characteristics for lung transplant rejection using mucosal biopsies

This study aimed to explore key regulatory connections underlying lung transplant rejection. The differentially expressed genes (DEGs) between rejection and stable lung transplantation (LTx) samples were screened using R package limma, followed by functional enrichment analysis and protein-protein interaction network construction. Subsequently, a global triple network, including miRNAs, mRNAs, and transcription factors (TFs), was constructed. Furthermore, immune cell infiltration characteristics were analyzed to investigate the molecular immunology of lung transplant rejection. Finally, potential drug-target interactions were generated. In brief, 739 DEGs were found between rejection and stable LTx samples. PTPRC, IL-6, ITGAM, CD86, TLR8, TYROBP, CXCL10, ITGB2, and CCR5 were defined as hub genes. Eight TFs, including STAT1, SPIB, NFKB1, SPI1, STAT5A, RUNX1, VENTX, and BATF, and five miRNAs, including miR-335-5p, miR-26b-5p, miR-124-3p, miR-1-3p, and miR-155-5p, were involved in regulating hub genes. The immune cell infiltration analysis revealed higher proportions of activated memory CD4 T cells, follicular helper T cells, γδ T cells, monocytes, M1 and M2 macrophages, and eosinophils in rejection samples, besides lower proportions of resting memory CD4 T cells, regulatory T cells, activated NK cells, M0 macrophages, and resting mast cells. This study provided a comprehensive perspective of the molecular co-regulatory network underlying lung transplant rejection.

Infectious Triggers of Chronic Lung Allograft Dysfunction

Survival after lung transplantation is limited in large part due to the high incidence of chronic rejection, known as chronic lung allograft dysfunction (CLAD). Pulmonary infections are a frequent complication in lung transplant recipients, due both to immunosuppressive medications and constant exposure of the lung allograft to the external environment via the airways. Infection is a recognized risk factor for the development of CLAD, and both acute infection and chronic lung allograft colonization with microorganisms increase the risk for CLAD. Acute infection by community acquired respiratory viruses, and the bacteria Pseudomonas aeruginosa and Staphylococcus aureus are increasingly recognized as important risk factors for CLAD. Colonization by the fungus Aspergillus may also augment the risk of CLAD. Fostering this transition from healthy lung to CLAD in each of these infectious episodes is the persistence of an inflammatory lung allograft environment.

High CXCL-16 levels correlate with symptomatic disease in lung transplant recipients with human cytomegalovirus replication in the allograft

Human cytomegalovirus (HCMV) is an important pathogen in lung transplant recipients (LTRs). In LTRs, HCMV may replicate in the transplanted lung, and this is indicated by HCMV DNA detection in the bronchoalveolar lavage fluid (BALF). Local replication may occur without causing clinical symptoms or, in some patients, it may lead to symptomatic HCMV disease. In the present study, we analyzed whether HCMV replication in the allograft induces CXCL-16, a chemokine that may play a key role in the regulation of mucosal immunity, and investigated whether CXCL-16 levels in BALF can be used to differentiate LTRs with asymptomatic HCMV replication from patients who simultaneously develop disease. In total, BALF samples from 57 LTRs, of whom 8 developed HCMV disease, were assessed for CXCL-16 levels using a quantitative enzyme-linked immunosorbent assay. We found that HCMV replication in the lung triggered a significant rise in CXCL-16 levels in the BALF (p < 0.001, Wilcoxon signed-rank test). Furthermore, the CXCL-16 increase, induced by HCMV, was significantly lower in LTRs who did not develop HCMV disease (p < 0.001, Mann-Whitney U-test). Thus, CXCL-16 is a potential marker that may contribute to identify those LTRs in whom local HCMV replication in the lung remains asymptomatic.

Novel aspects on the pathogenesis of Mycoplasma pneumoniae pneumonia and therapeutic implications

Mycoplasma pneumoniae (Mp) is a leading cause of community acquired pneumonia. Knowledge regarding Mp pneumonia obtained from animal models or human subjects has been discussed in many different reports. Accumulated expertise concerning this critical issue has been hard to apply clinically, and potential problems may remain undiscovered. Therefore, our multidisciplinary team extensively reviewed the literature regarding Mp pneumonia, and compared findings from animal models with those from human subjects. In human beings, the characteristic pathological features of Mp pneumonia have been reported as alveolar infiltration with neutrophils and lymphocytes and lymphocyte/plasma cell infiltrates in the peri-bronchovascular area. Herein, we demonstrated the novel aspects of Mp pneumonia that the severity of the Mp pneumonia seemed to depend on the host innate immunity to the Mp, which might be accelerated by antecedent Mp exposure (re-exposure or latent respiratory infection) through up-regulation of Toll-like receptor 2 expression on bronchial epithelial cells and alveolar macrophages. The macrolides therapy might be beneficial for the patients with macrolide-resistant Mp pneumonia via not bacteriological but immunomodulative effects. This exhaustive review focuses on pathogenesis and extends to some therapeutic implications such as clarithromycin, and discusses the various diverse aspects of Mp pneumonia. It is our hope that this might lead to new insights into this common respiratory disease.

RANTES polymorphisms and the risk of graft-versus-host disease in human leukocyte antigen-matched sibling allogeneic hematopoietic stem cell transplantation

We investigated the association between RANTES (regulated upon activation, normal T cell expressed and secreted) polymorphisms and clinical outcomes in patients treated with allogeneic hematopoietic stem cell transplantation (allo-HSCT). Three RANTES gene polymorphisms, i.e., -403G/A (rs2107538), -28C/G (rs2280788) and In1.1T/C (rs2280789), were genotyped, and the effects of the genotypes and haplotypes of RANTES on clinical outcomes were analyzed. The competing risk regression analysis was used to investigate the relationship between the polymorphisms and the cumulative risk of graft-versus-host disease (GVHD). An AGC haplotype in a recessive model showed significant harmful effects on the cumulative risk of acute GVHD and relapse-free survival (adjusted hazard ratios 2.42 and 2.71, 95% confidence intervals 1.29-4.55 and 1.30-5.64; p = 0.018 and 0.024, respectively), whereas a GCT haplotype did not. RANTES polymorphisms were not significantly associated with overall survival and the risk of chronic GVHD. This study suggests that RANTES polymorphisms might be associated with the occurrence of acute GVHD rather than of chronic GVHD and also of relapse-free survival in the patients treated with allo-HSCT. Further larger prospective investigations are needed to establish the role of RANTES polymorphisms in patients treated with allo-HSCT.

Pretreatment with lornoxicam, a cyclooxygenase inhibitor, relieves postoperative immuno-suppression after total abdominal hysterectomy

Total abdominal hysterectomy (TAH) is most commonly performed for benign lesions and malignant diseases of the uterus. Postoperative immuno-suppression caused by TAH has become a serious clinical problem, due to the high incidence of infectious complications after this operation. Lornoxicam (LOR) is a member of non-steroidal anti-inflammatory drugs and a cyclooxygenase inhibitor. In this study, 45 patients undergoing TAH for uterine myoma were enrolled and given intravenous injection of normal saline (untreated patients) or LOR (8 or 16 mg) preoperatively (15 patients/group). We studied the effects of LOR on postoperative immuno-suppression by determining the serum levels of three cytokines, RANTES, monocyte chemotactic protein-1 (MCP-1), and stromal cell-derived factor 1alpha (SDF-1alpha). MCP-1 and RANTES are involved in the pathophysiology of acute and chronic inflammatory processes, and SDF-1alpha is considered as an inflammatory chemoattractant. Following TAH, the serum levels of RANTES were reduced in the untreated patients, but were significantly higher in the patients treated with LOR. In addition, the levels of MCP-1 and SDF-1alpha were significantly elevated in the untreated patients, but were significantly lower in the patients treated with LOR. Furthermore, preoperative treatment with LOR 16 mg could regulate the serum levels of these three chemokines more effectively, compared to that with LOR 8 mg. In conclusion, preoperatively intravenous injection of LOR may effectively restrain the decreased serum levels of RANTES and the increased expression of MCP-1 and SDF-1alpha in TAH patients. LOR may help to maintain the stability of immune function of TAH patients.

Pulmonary hypertension: advances in pathogenesis and treatment

Pulmonary hypertension is an orphan disease that until recently has received limited attention within the wider medical community. This has changed distinctly in the last 10 years with the advent of new classes of therapy and a renewed interest in mechanisms of pathogenesis. This review utilized information gathered from recent conferences, and a review of the literature was conducted using MedLine and Pubmed. Accepted mechanisms of pathogenesis and currently available treatments are presented. We will discuss interesting new concepts in pathogenesis, including the importance of genetic forms of the disease and in particular the transforming growth factor receptor superfamily and the evolving evidence of the contribution of dysregulated immunity. Areas of research may yield therapeutic benefits in the not-too-distant future, including anti-proliferative therapies and stem cell therapy.

Altered levels of CC chemokines during pulmonary CMV predict BOS and mortality post-lung transplantation

Pulmonary CMV infection (CMVI) and disease (CMVD) is associated with reduced long-term survival post-lung transplantation, however, the specific biologic mechanisms remain unclear. We have demonstrated a role of CC chemokines during lung allograft dysfunction. Based on these findings, we hypothesized that pulmonary CMV upregulates the expression of multiple CC chemokines that leads to allograft dysfunction and decreased long-term survival. We performed a nested case control study in lung transplant recipients to investigate alterations in CC chemokine biology during pulmonary CMV. Levels of CC chemokines were measured in bronchoalveolar lavage fluid (BALF) from recipients with CMVI (n = 33), CMVD (n = 6), and in healthy lung transplant controls (n = 33). We found a trend toward increased levels of MIP-1alpha/CCL3 during pulmonary CMVI. Levels of MCP-1/CCL2 and RANTES/CCL5 were significantly elevated during pulmonary CMV. Interestingly, elevated levels of CCL3 in BALF were protective with regards to survival. Importantly, elevated levels of CCL2 in BALF predicted the development of BOS, while elevated levels of CCL5 in BALF predicted an increase in mortality post-lung transplant. Altered levels of specific CC chemokines during pulmonary CMV are associated with future clinical outcomes. These results suggest a possible utility of BALF CC chemokines as biomarkers for guiding risk assessment during pulmonary CMV post-lung transplantation.

Simultaneous LFA-1 and CD40 ligand antagonism prevents airway remodeling in orthotopic airway transplantation: implications for the role of respiratory epithelium as a modulator of fibrosis

Airway remodeling is a prominent feature of certain immune-mediated lung diseases such as asthma and chronic lung transplant rejection. Under conditions of airway inflammation, the respiratory epithelium may serve an important role in this remodeling process. Given the proposed role of respiratory epithelium in nonspecific injury models, we investigated the respiratory epithelium in an immune-specific orthotopic airway transplant model. MHC-mismatched tracheal transplants in mice were used to generate alloimmune-mediated airway lesions. Attenuation of this immune injury and alteration of antidonor reactivity were achieved by the administration of combined anti-LFA-1/anti-CD40L mAbs. By contrast, without immunotherapy, transplanted airways remodeled with a flattening of respiratory epithelium and significant subepithelial fibrosis. Unopposed alloimmune injury for 10 days was associated with subsequent epithelial transformation and subepithelial fibrosis that could not be reversed with immunotherapy. The relining of donor airways with recipient-derived epithelium was delayed with immunotherapy resulting in partially chimeric airways by 28 days. Partial chimerism was sufficient to prevent luminal fibrosis. However, epithelial chimerism was also associated with airway remodeling. Therefore, there appears to be an intimate relationship between the morphology and level of chimerism of the respiratory epithelium and the degree of airway remodeling following alloimmune injury.

Impact of MHC class II incompatibility on localization of mononuclear cell infiltrates to the bronchiolar compartment of orthotopic lung allografts

Chronic pathological changes in transplanted lungs are unique because they center on the airways. We examined the relative role of MHC class I and II antigens in causing bronchial pathology in orthotopic lung transplants to rats maintained on cyclosporin A (CsA). Transplants mismatched for MHC class II antigens had significantly more peri-bronchiolar infiltrates than MHC class I incompatible transplants. No significant increase in infiltrates was found in lung transplants incompatible for MHC class I plus II antigens compared to MHC class II antigens alone. Immunohistochemistry demonstrated that MHC class II antigen expression was confined to macrophages in MHC class I incompatible transplants, but was upregulated on bronchial epithelium in transplants with MHC class II incompatibilities. Vascular endothelium was notably devoid of MHC class II antigen expression in all transplants. However, both peri-bronchial and peri-vascular infiltrates were frequently cuffed by alveolar macrophages and type II pneumocytes that expressed MHC class II antigens. PCR analysis demonstrated that IFN-gamma and regulated on activation, normal T cells expressed and secreted (RANTES) were upregulated in MHC class II incompatible transplants. Thus, MHC class II incompatible orthotopic lung transplants in rats maintained on CsA immunosuppression undergo a bronchiolcentric upregulation of alloantigens.

Respiratory viral infections are a distinct risk for bronchiolitis obliterans syndrome and death

Bronchiolitis obliterans syndrome (BOS) is the major obstacle to long-term survival after lung transplantation, in part because its pathogenesis is poorly understood and treatment options are limited. To identify unique risk factors for BOS and death, we performed a retrospective cohort study on 259 consecutive adult lung transplant recipients over a 5-year period. The demographic and clinical characteristics of this population were analyzed for an association between BOS or death and potential risk factors, including community-acquired respiratory viral (CARV) infections, acute rejection, and cytomegalovirus pneumonitis. Respiratory syncytial virus, parainfluenza, influenza, and adenovirus accounted for 21 CARV infections. Univariate and multivariate time-dependent Cox regression analyses demonstrated that this CARV group was more likely to develop BOS, death, and death from BOS. Furthermore, these trends were more pronounced in patients with evidence of lower respiratory tract-CARV (lower-CARV) infections. Notably, the CARV and lower-CARV infections were risk factors for BOS, death, and death from BOS distinct from the risk attributable to acute rejection. Identification of CARV and lower-CARV infections as BOS and mortality risk factors has important clinical implications and may provide insight into disease pathogenesis and accelerate the development of novel treatment strategies to modify post-CARV BOS.

In vitro pharmacoregulation of CC chemokine ligand 5 and its receptor CCR5 in diffuse lung diseases

BACKGROUND

CC chemokine ligand (CCL)5 and its receptor CCR5 contribute to leukocyte migration into lungs of patients with diffuse lung diseases (DLD). Pharmacological regulation of CCL5 and CCR5 expression was therefore explored in bronchoalveolar cells obtained from patients with DLD.

METHODS

Cells from 21 patients were co-cultivated in vitro with tumour necrosis factor-alpha and dexamethasone, cyclosporin A (CyA) or pentoxifylline. Chemokine mRNA expression and protein production was assessed by reverse transcription-polymerase chain reaction and enzyme-linked immunosorbent assay, respectively.

RESULTS

Dexamethasone altered CCL5 mRNA expression and suppressed its protein levels. CyA inhibited chemokine mRNA expression but not protein production. Pentoxifylline did not affected chemokine expression. Both dexamethasone and CyA suppressed CCR5 mRNA transcripts.

CONCLUSION

In conclusion, while dexamethasone downregulates the CCL5 functional form, CyA and pentoxifylline have no effects on CCL5 protein. These data provide in vitro correlation for clinical applications of immunomodulators in therapy of DLD.

Viral chemokine receptors and chemokines in human cytomegalovirus trafficking and interaction with the immune system. CMV chemokine receptors

The ubiquitous, opportunistic pathogen human cytomegalovirus (CMV) encodes several proteins homologous to those of the host organism. Four different CMV genes encode chemokine receptor-like peptides. These genes, UL33, UL78, US27, and US28, are expressed at various stages of infection in vitro. Their functions remain largely unknown. To date, chemokine binding and signalling has only been demonstrated for the US28 gene product. Putative ligands for the other CMV-encoded chemokine receptors are discussed on basis of phylogenetic analysis. The potential roles of these receptors in virus trafficking, persistence, and immune evasion are summarized. Similarly, modulation of expression of the host chemokines IL-8, MCP-1a and RANTES in relation to viral dissemination and persistence is reviewed.

Recipient iNOS but not eNOS deficiency reduces luminal narrowing in tracheal allografts

Chronic airway rejection is characterized by prolonged inflammation, epithelial damage, and eventual luminal obliterative bronchiolitis (OB). In cardiac allografts, the inducible nitric oxide synthase (iNOS) promotes acute rejection but paradoxically reduces neointimal formation, the hallmark of chronic rejection. The specific roles of NOS isoforms in modulating lymphocyte traffic and airway rejection are not known. Using a double lumen mouse tracheal transplant model, tracheal grafts from B10.A (allo) or C57BL/6J (iso) mice were transplanted into cyclosporine-treated wild-type (WT) iNOS(-/-) or endothelial NOS (eNOS)(-/-) recipients. OB was observed in WT tracheal allografts at 3 weeks (53 +/- 2% luminal occlusion vs. 17 +/- 1% for isografts, P < 0.05) with sites of obstructive lesion formation coinciding with areas of CD3(+) CD8(+) T cell-rich lymphocytic bronchitis. In contrast, allografts in iNOS(-/-) recipients exhibited reductions in local expression of proinflammatory chemokines and cytokines, graft T cell recruitment and apoptosis, and luminal obliteration (29 +/- 2%, P < 0.05 vs. WT allografts). Recipient eNOS deficiency, however, suppressed neither chemokine expression, lymphocyte infiltration, nor airway occlusion (54 +/- 2%). These data demonstrate that iNOS exacerbates luminal obliteration of airway allografts in contrast with the known suppression by iNOS of cardiac allograft vasculopathy. Because iNOS(-/-) airways transplanted into WT allograft hosts are not protected from rejection, these data suggest that iNOS expressed by graft-infiltrating leukocytes exerts the dominant influence on airway rejection.

Signaling of gp34 (OX40 ligand) induces vascular endothelial cells to produce a CC chemokine RANTES/CCL5

We previously showed that gp34 (OX40 ligand) expressed on vascular endothelial cells is not only involved in adhesion between activated T cells and endothelial cells but also by itself able to transmit intracellular signals leading to expression of c-fos and c-jun mRNA upon OX40 binding. In the present study, we searched for genes that were induced or upregulated by gp34 signaling in human umbilical vein endothelial cells (HUVECs) to define its downstream biological events. HUVECs expressing high levels of gp34 were stimulated with recombinant soluble OX40 or mock control and subjected to analysis using cDNA expression arrays. We found that a CC chemokine RANTES (regulated upon activation, normal T cell expressed and secreted)/CCL5 is one of such inducible genes. Reverse transcriptase-PCR analysis showed that expression of RANTES mRNA was induced after incubation with soluble OX40 and this induction was inhibited by anti-gp34 mAb. We could detect expression of intracellular RANTES protein by flow cytometry in HUVECs stimulated with soluble OX40 as well as fixed OX40 transfectant cells but not those stimulated with mock supernatants or mock transfectant cells. Again, this induction of RANTES protein was inhibited by anti-gp34 mAb. These results clearly indicate that gp34 signaling induces expression of RANTES at both mRNA and protein levels in HUVECs and suggest a possible link between the OX40/gp34 system and RANTES during the process of T cell adhesion to endothelial cells and subsequent extravasation.

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.

Upregulation of chemokines in bronchoalveolar lavage fluid as a predictive marker of post-transplant airway obliteration

BACKGROUND

The early stage of post-transplant obliterative bronchiolitis (OB) is characterized by an influx of inflammatory cells to the lung, among which neutrophils may play a role in key events. The potential for chemokines to induce leukocyte accumulation in the alveolar space was investigated. We assessed whether changes in the chemotactic expression profile could be used as sensitive markers of the onset of OB.

METHODS

Serial bronchoalveolar lavage (BAL) fluids from 13 stable healthy recipients and 8 patients who developed bronchiolitis obliterans syndrome (BOS) were analyzed longitudinally for concentrations of interleukin-8 (IL-8), chemokines regulated-upon-activation and normal T-cell expressed and secreted (RANTES) and monocyte chemoattractant protein-1 (MCP-1), soluble intracellular adhesion molecule-1 (sICAM-1) and vascular cell adhesion molecule-1 (VCAM-1). These were assessed by enzyme-linked immunosorbent assay (ELISA).

RESULTS

Significantly elevated percentages of BAL neutrophils and IL-8 levels were found at the pre-clinical stage of BOS, on average 151 +/- 164 days and 307 +/- 266 days, respectively, before diagnosis of BOS. There was also early upregulation of RANTES and MCP-1 in the BOS group (mean 253 +/- 323 and 152 +/- 80 days, respectively, before diagnosis of BOS). The level of MCP-1 was consistently higher than that of RANTES until airway obliteration. BAL sICAM-1 and sVCAM-1 levels were not statistically different between the groups.

CONCLUSIONS

These data support the belief that RANTES, IL-8 and MCP-1 play a crucial role in the pathogenesis of OB. The results show that relevant increased levels of such chemokines may predict BOS, and suggest that there is potential for some of these markers to be used as early and sensitive markers of the onset of BOS. Longitudinal monitoring of these chemokine signals may contribute to better management of patients at risk for developing OB, at a stage when remodeling can either be reversed or altered.

Expression of the chemokine receptor CXCR3 and its ligand IP-10 during human cardiac allograft rejection

BACKGROUND

Chemokines play an essential role in regulating the infiltration of leukocytes into allografts in experimental models. Little is known of their expression or function after human cardiac transplantation.

METHODS AND RESULTS

We analyzed 169 sequential human endomyocardial biopsies by immunocytochemistry for infiltration by CD3(+) T cells and the expression of the chemokine receptors CCR1, CCR3, CCR5, and CXCR3. In both cross-sectional and longitudinal analyses, the expression of each of the chemokine receptors correlated with the degree of CD3(+) T-cell infiltration. In particular, the expression of CXCR3 was temporally and spatially associated with CD3(+) T-cell infiltrates and correlated with the histopathological diagnosis of acute rejection (OR, 11.73 and 4.05, respectively; P<0.001). Of 7 patients followed up longitudinally for 1 year, 4 with consecutive biopsies developed intimal thickening by intravascular ultrasound. In these patients, there was a trend for persistent expression of CD3- and CXCR3-expressing infiltrates in the later part of the first posttransplant year. The chemokines eotaxin, IP-10, lymphotactin, MCP-1, Mig, RANTES, and SDF-1 were examined in an additional 35 biopsies by RT-PCR. Eotaxin, lymphotactin, MCP-1, Mig, and SDF-1 were present in both normal and rejecting biopsies. However, the CXCR3 ligand IP-10, which was rarely expressed in normal biopsies, was markedly induced in acute rejection (OR, 19.43; P=0.01).

CONCLUSIONS

The presence of CXCR3(+) T cells and the CXCR3 ligand IP-10 within endomyocardial biopsies is strongly associated with acute rejection. The CXCR3-IP-10 interaction warrants consideration as a therapeutic target in the management of cardiac allograft recipients.

Rantes production during development of cardiac allograft vasculopathy

BACKGROUND

RANTES (regulated on activation, normal T cell expressed and secreted) production has been shown to correlate with mononuclear cell recruitment and precede intimal thickening in cardiac allograft vasculopathy (CAV). However, the cells that produce RANTES in CAV are undefined. Therefore, in an MHC II-mismatched murine model of CAV, we sought to (1) define the cellular sources of RANTES and (2) determine the role of CD4+ lymphocytes in RANTES production during CAV development.

METHODS

B6.CH-2bm12 strain donor hearts were transplanted heterotopically into wild-type (WT) or CD4 knockout (CD4KO) C57BL/6 mice (MHC II mismatch). No immunosuppression was used. Recipients were sacrificed at 7, 14, and 24 days. Intragraft RANTES gene expression and protein levels were determined with ribonuclease protection assay and ELISA, respectively. At days 7 and 24, RANTES production by graft-infiltrating cells was defined with intracellular RANTES staining and multicolor FACS analysis. Intimal thickening was quantitated morphometrically. In murine hearts and in six explanted human hearts with advanced CAV, RANTES was also localized immunohistochemically.

RESULTS

NK, NKT, and gammadelta+ cells, in addition to CD4+, CD8+ lymphocytes, and CD11b+ macrophages, produced RANTES in early and late stages of CAV. RANTES-producing NK, NKT, and gammadelta+ cells tripled in number during CAV development; by day 24, NK and gammadelta+ cells each outnumbered CD4+ lymphocytes and CD11b+ macrophages. The presence of CD4+ lymphocytes was required for sustained RANTES production in allografts, which correlated with mononuclear cell recruitment and preceded intimal thickening. In murine and explanted human hearts with advanced CAV, RANTES immunolocalized with graft-infiltrating mononuclear cells and vessel wall cells.

CONCLUSIONS

We present evidence that other cell types in addition to CD4+, CD8+ T lymphocytes, and CD11b+ macrophages contribute significantly to RANTES production in CAV. In this MHC II-mismatched murine model of CAV, sustained RANTES production requires CD4+ lymphocytes, correlates with mononuclear cell recruitment, and precedes intimal thickening. In experimental and human CAV, vessel wall cells may also produce RANTES. Interventions aimed at inhibiting RANTES production in CAV may need to target several types of cells, and neutralization of RANTES bioactivity may reduce mononuclear cell recruitment and CAV development.

Cxcr3 and its ligand CXCL10 are expressed by inflammatory cells infiltrating lung allografts and mediate chemotaxis of T cells at sites of rejection

The attraction of T lymphocytes into the pulmonary parenchyma represents an essential step in mechanisms ultimately leading to lung allograft rejection. In this study we evaluated whether IP-10 (CXCL10), a chemokine that is induced by interferon-gamma and stimulates the directional migration of activated T cells, plays a role in regulating the trafficking of effector T cells during lung allograft rejection episodes. Immunohistochemical examination showed that areas characterized by acute cellular rejection (grades 1 to 4) and active obliterative bronchiolitis (chronic rejection, Ca) were infiltrated by T cells expressing CXCR3, i.e., the specific receptor for CXCL10. In parallel, T cells accumulating in the bronchoalveolar lavage of lung transplant recipients with rejection episodes were CXCR3+ and exhibited a strong in vitro migratory capability in response to CXCL10. In lung biopsies, CXCL10 was abundantly expressed by graft-infiltrating macrophages and occasionally by epithelial cells. Alveolar macrophages expressed and secreted definite levels of CXCL10 capable of inducing chemotaxis of the CXCR3+ T-cell line 300-19; the secretory capability of alveolar macrophages was up-regulated by preincubation with interferon-gamma. Interestingly, striking levels of CXCR3 ligands could be demonstrated in the fluid component of the bronchoalveolar lavage in individuals with rejection episodes. These data indicate the role of the CXCR3/CXCL10 interactions in the recruitment of lymphocytes at sites of lung rejection and provide a rationale for the use of agents that block the CXCR3/CXCL10 axis in the treatment of lung allograft rejection.

Differential expression of RANTES chemokine, TGF-beta, and leukocyte phenotype in acute cellular rejection and quilty B lesions

BACKGROUND

Because of the complexity of the trabeculated endocardial surface and tangential histologic sectioning, the differentiation of acute cellular rejection (ACR) from Quilty B lesions (QB) in endomyocardial biopsies (EMBs) is problematic. We hypothesized that the phenotype chemokine RANTES (regulated upon activation, normal T cell expressed and secreted) expression of infiltrating cells and the pattern of expression of transforming growth factor-beta (TGF-beta) may distinguish ACR from QB. In previous studies, the number of RANTES-positive cells and the expression of TGF-beta correlated with the severity of rejection.

METHODS

We used immunohistochemical techniques to stain sections of human EMBs with only QB (n = 14) or with only ACR (International Society for Heart and Lung Transplantation Grades 1A and 1B, n = 7; Grades 3A and 3B, n = 7) for B (CD20) and T-lymphocytes (CD3), macrophages (CD68), RANTES, and TGF-beta expression. We graded the percentage of positive cells from 0 to 4 (1 = 1% to 25%; 2 = 26% to 50%; 3 = 51% to 75%, and 4 = 76% to 100%).

RESULTS

When ACR was compared with QB, we found no difference in the proportion of myocardial B cells (0.9 +/- 0.3 vs 1.1 +/- 0.3, p = 0.17); however, we found a lesser proportion of T cells (1.8 +/- 0.5 vs. 2.8 +/- 0.9, p <0.01) but more macrophages (2.9 +/- 0.5 vs. 1.1 +/- 0.6, p < 0.0001) in ACR than in QB. We also found more RANTES-positive leukocytes in ACR vs. QB (2.8 +/- 1.3 vs. 1.9 +/- 0.9, p = 0.03). In QB, many endocardial vessels stained for TGF-beta (2.9 +/- 1.6). Myocardial vessels and injured myocytes in both ACR and QB expressed TGF-beta.

CONCLUSIONS

In ACR, although T-lymphocytes are numerous, more than 50% of infiltrating cells are macrophages and more than 50% express RANTES. In QB lesions, more than 50% of infiltrating cells are T-lymphocytes and less that 50% of leukocytes will express RANTES. B cells are present in both ACR and QB, but on average comprise only 25% of the cells present. Thus, a relatively simple immunohistochemical analysis of endomyocardial biopsies may be useful in distinguishing ACR from QB.

Monocyte chemoattractant protein-1 and RANTES are chemotactic for graft infiltrating lymphocytes during acute lung allograft rejection

Graft infiltrating lymphocytes (GILs) are crucial to rejection of lung allografts. However, chemotactic activities, chemokines responsible for GIL recruitment, and cells involved in chemokine production during lung allograft rejection have not been evaluated. This study determined whether chemotactic activity for GILs is upregulated, and whether the chemokines monocyte chemoattractant protein (MCP)-1 and regulated on activation, normal T cells expressed and secreted (RANTES) have roles in GIL chemotaxis during lung allograft rejection. F344 (RT1(lv1)) rat lung allografts were transplanted into WKY (RT1(l)) recipients. Chemotactic activity for GILs and quantities of MCP-1 and RANTES were determined in allograft bronchoalveolar lavage fluid 1 wk after transplantation. Data showed that during rejection, chemotactic activity for GILs is upregulated, MCP-1 and RANTES are produced locally, and both MCP-1 and RANTES are operative in GIL recruitment. Immunohistochemistry showed that alveolar macrophages (AMs) were the major source of MCP-1 and that other lung cells, including AMs, were the source of RANTES. Further, depletion of AMs in the donor lung before transplantation downregulated chemotaxis for GILs and production of MCP-1 during rejection episodes. These data show that chemotaxis for GILs is upregulated locally during lung allograft rejection, and that MCP-1 and RANTES contribute to GIL recruitment during the rejection response.

Ex vivo modulation of RANTES and sCD30 by proinflammatory stimuli in HIV-seropositive and -negative individuals

RANTES and sCD30 were measured in ex vivo culture supernatants of unstimulated or stimulated PBMC in order to investigate their potential role as markers of acute immune activation. Patients in an advanced stage of HIV infection (AIDS A) were compared to AIDS patients who were evaluated for pneumonia at the time of blood withdrawal (AIDS B); HIV(+) individuals with nonprogressive infection (LTNP) and healthy donors (N) served as controls. Constitutive levels of RANTES were significantly elevated in AIDS B patients (P 0.0001), whereas spontaneous release of sCD30 was strongly correlated with the presence of both pneumonia (P 0.002) and HIV infection (P 0.004). LPS was a strong inducer of RANTES in all four categories; however, in AIDS B patients a negative and positive correlation between constitutive and induced levels was observed with LPS (P 0.0004) and IFN-gamma (P 0.006), respectively. We clearly showed that IFN-gamma reached a fourfold superinduction of sCD30 release in both HIV-positive and -negative individuals, whereas IL-6-driven production of both sCD30 and RANTES occurred only in healthy donors. Ex vivo RANTES levels may also be monitored as an index of acute immune activation under conditions of chronic activation of the immune system, whereas sCD30 release may be equally indicative of both acute and chronic processes of T cell activation. Proinflammatory stimuli differentially affected RANTES and sCD30 secretion in ex vivo PBMC cultures, suggesting complex pathways in the in vivo regulation of these two molecules.

RANTES plays an important role in the evolution of allograft transplant-induced fibrous airway obliteration

Although lung transplantation is a widely applied therapeutic modality for end-stage pulmonary disease, the long-term survival following this procedure is limited by the development of bronchiolitis obliterans (BO). We investigated the role of RANTES, a C-C chemokine, in the evolution of fibrous airway obliteration (FAO) using a rat heterotopic tracheal transplant model. RANTES was highly expressed in infiltrating mononuclear cells in both allogeneic and isogeneic grafts as revealed by immunohistochemistry. Using a miniosmotic pump, neutralizing anti-RANTES antibody was locally and continuously infused to allografts, whereas recombinant rat RANTES was administered to isografts. Anti-RANTES antibody treatment decreased the number of CD4(+) infiltrating cells in allotracheas and preserved luminal patency compared with those of allocontrols. However, RANTES infusion in isografts did not induce FAO, even though CD4(+) cell migration was increased by this treatment. It appears that RANTES is relevant to the recruitment of CD4(+) cells and the development of FAO in the process of allorejection. Local administration of anti-RANTES might be a therapeutic option for BO following lung transplantation.

The role of the CC chemokine, RANTES, in acute lung allograft rejection

Lung transplantation is a therapeutic option for patients with end-stage lung disease. Acute allograft rejection is a major complication of lung transplantation and is characterized by the infiltration of activated mononuclear cells. The specific mechanisms that recruit these leukocytes have not been fully elucidated. The CC chemokine, RANTES, is a potent mononuclear cell chemoattractant. In this study we investigated RANTES involvement during acute lung allograft rejection in humans and in a rat model system. Patients with allograft rejection had a 2.3-fold increase in RANTES in their bronchoalveolar lavages compared with healthy allograft recipients. Rat lung allografts demonstrated a marked time-dependent increase in levels of RANTES compared with syngeneic control lungs. RANTES levels correlated with the temporal recruitment of mononuclear cells and the expression of RANTES receptors CCR1 and CCR5. To determine RANTES involvement in lung allograft rejection, lung allograft recipients were passively immunized with either anti-RANTES or control Abs. In vivo neutralization of RANTES attenuated acute lung allograft rejection and reduced allospecific responsiveness by markedly decreasing mononuclear cell recruitment. These experiments support the idea that RANTES, and the expression of its receptors have an important role in the pathogenesis of acute lung allograft rejection.

Chemokines and soluble adhesion molecules in renal transplant recipients with cytomegalovirus infection

Cytomegalovirus (CMV) infection is associated with leucocyte infiltration in various organs, which supports a role for chemokines and adhesion molecules in the pathogenesis of CMV infection. In a prospectively conducted study of renal transplant recipients, 10 patients with CMV disease, five patients with asymptomatic CMV infection and 10 patients who did not have any CMV infection were included. During CMV infection, and in particular during CMV disease, plasma levels of the chemokines IL-8, macrophage inflammatory protein-1alpha (MIP-1alpha) and monocyte chemotactic protein-1 (MCP-1) and the soluble adhesion molecules vascular cell adhesion molecule-1 (VCAM-1), intercellular adhesion molecule-1 (ICAM-1) and L-selectin increased and were positively correlated with the degree of CMV pp65 antigenaemia. Furthermore, a decrease in plasma levels of these chemokines and adhesion molecules was observed following ganciclovir therapy in the patients with CMV disease. This could suggest a role for these molecules in the pathogenesis of CMV infection.

Depletion of extracellular RANTES during human cytomegalovirus infection of endothelial cells

Human cytomegalovirus (CMV) infection results in pneumonitis in bone-marrow and lung-transplant recipients. The source of CMV infection contributing to the onset of pneumonitis is unclear, but may involve infection of the lung endothelium in the presence of infiltrating mononuclear cells. Viral infection stimulates the host cell to express chemokines as signals to recruit specific immune cells to the site of injury. CMV encodes a chemokine receptor that may function to reduce host cell expression of chemokines. In the study reported here we found that extracellular concentrations of the chemokine regulated on activation, normal T cell expressed and secreted (RANTES) are depleted during productive infection of primary endothelial cells with CMV strain 4010, an endothelial-adapted strain of CMV. Utilizing adenovirus-transformed human kidney epithelial cells (type 293 cells) that stably express the CMV-encoded chemokine receptor US28, we found that depletion of extracellular RANTES during infection is attributable to US28, which binds and internalizes extracellular RANTES.

Patterns and significance of CD44 expression in lung allografts

BACKGROUND

Lung allograft rejection involves the interplay of multiple cellular populations, soluble mediators, and extracellular matrix proteins. The CD44 family of cell surface glycoproteins mediates a variety of cell-cell and cell-matrix interactions including lymphocyte homing to sites of antigenic challenge and fibroblast migration and invasion into extracellular matrix, processes integral to lung allograft rejection.

METHODS

We performed immunohistochemical staining for CD44 on biopsies from allograft recipients with differing rejection experiences: Group 1 (n = 5 patients/10 biopsies) never exceeded Grade A1 or B2 acute rejection (AR); Group 2 (n = 7 patients/26 biopsies) had 2 or more episodes of Grade A2 or higher AR and no obliterative bronchiolitis (OB); Group 3 (n = 6 patients/17 biopsies) had clinical and pathologic OB. Nine infected allograft biopsies, 8 near-normal lung sections (non-transplant controls), and 13 non-transplant biopsies showing bronchiolitis obliterans organizing pneumonia (BOOP), organizing diffuse alveolar damage (DAD), or usual interstitial pneumonia (UIP) were also studied.

RESULTS

Allograft biopsies demonstrated significantly more CD44 staining among lymphocytes, macrophages, Type II pneumocytes, and respiratory epithelial cells than non-transplant controls, while staining of lymphocytes, macrophages, and Type II pneumocytes did not differ significantly between allograft groups. Fibroblast CD44 staining in Group 3 biopsies significantly exceeded that of controls and Groups 1 and 2, and biopsies with AR and/or OB showed more fibroblast staining than biopsies with BOOP, organizing DAD, or UIP. Alveolar CD44-positive fibroblasts did not predict development of OB, while bronchial CD44-positive fibroblasts were followed in one case by OB.

CONCLUSIONS

These findings suggest that CD44 expression is characteristic of graft-infiltrating inflammatory cells and resident parenchymal cells, and may be related to the initiation and evolution of AR and OB.

Current understanding of chemokine involvement in allograft transplantation

Multiple studies have demonstrated that chemokines play an essential role in regulating and co-ordinating the infiltration of leucocytes into allografts. Chemokines are expressed in skin, liver, heart, and kidney allografts following initial engraftment, ischemic injury, viral infection, and acute and chronic rejection. To date, most of our understanding of chemokine biology has been generated from studies of animal models of transplantation and little is known about the role of chemokines in human allograft rejection. Chemokines may play important mechanistic roles in transplant rejection, in the development of graft arteriosclerosis, and in chronic sclerosing cholangiopathy. Furthermore, these molecules may serve as sensitive diagnostic indicators for the analysis of rejection, including chronic rejection or other forms of graft dysfunction. Lastly, it is possible that chemokine-targeted therapy might become a feasible option for the treatment of allograft rejection.

Eosinophils in acute cellular rejection in liver allografts

Eosinophils have a role in various allergic and inflammatory disease processes and participate in the process of acute rejection in solid organ allografts. Initial studies described the diagnostic value of eosinophils in kidney allograft rejection. Graft eosinophilia is a sensitive and specific marker of acute rejection in liver allografts and has been incorporated as one of the diagnostic criteria of acute rejection by the Royal Free Hospital scoring system. Blood eosinophilia also has been investigated and is a useful diagnostic marker of acute rejection in liver and kidney allografts, although studies differ in defining the day of onset of eosinophilia in relation to rejection. Eosinophils probably act through the chemokines interleukin-5 and RANTES (regulated on activation, normal T cells expressed and secreted) in the pathogenesis of acute rejection. Basic cytotoxic proteins, such as eosinophil cationic protein and major basic protein, are released by the eosinophils, and their effector role in acute rejection has been studied through the use of specific monoclonal antibodies. Successful treatment of acute rejection with corticosteroids has been associated with a decrease in graft and blood eosinophil counts. Eosinophils also act as prognostic markers of acute rejection, as shown by studies reporting that patients with elevated eosinophil counts and steroid-resistant rejection showed a worse prognosis. Further research into the effector mechanisms of eosinophils in acute rejection needs to be performed. The ability of eosinophils to distinguish those diseases with different responses to standard immunosuppression and other diseases in the context of acute rejection also needs to be studied.

Expression and modulation of ICAM-1, TNF-alpha and RANTES in human alveolar macrophages from lung-transplant recipients in vitro

Alveolar macrophages (AMs) play a central role in pulmonary inflammation in response to local stimuli. As a model for investigating anti-inflammatory drugs, we studied the effects of the cyclohexadepsipeptide antibiotic, fusafungine, and that of the glucocorticoid dexamethasone on the expression of ICAM-1, TNF-alpha and RANTES, induced in vitro by rIFN-gamma in human AMs freshly isolated from bronchoalveolar lavage fluid (BAL) obtained in lung-transplanted patients. ICAM-1 antigen expression, induced on AMs after 24 h of culture, was significantly inhibited by fusafungine in a concentration-dependent manner, as measured by flow cytometry analysis using an anti-CD54 monoclonal antibody. TNF-alpha production, but not RANTES release (measured by ELISA), was significantly inhibited. mRNA studies, by means of polymerase chain reaction amplification of complementary deoxyribonucleic acids (RT-PCR), showed no significant modification of mRNA levels, suggesting that fusafungine acts mainly at a post-transcriptional level. In the same conditions, dexamethasone significantly inhibited the release both of TNF-alpha and RANTES by AMs, mainly acting at the mRNA level, but had no effect on ICAM-1 expression. Assessment of the cellular and molecular targets of anti-inflammatory drugs in this model of human AM activation should lead to more appropriate treatment of inflammatory process of the respiratory tract. By virtue of its anti-inflammatory effects on alveolar macrophages, combined with its antibacterial properties, fusafungine should prove particularly suitable for local treatment of bacterial infections of the respiratory tract.

Nitric oxide mediates murine cytomegalovirus-associated pneumonitis in lungs that are free of the virus

4 wk after intraperitoneal inoculation of 0.2 LD50 (50% lethal dose) of murine cytomegalovirus (MCMV) in adult BALB/c mice, MCMV remained detectable in the salivary glands, but not in the lungs or other organs. When the T cells of these mice were activated in vivo by a single injection of anti-CD3 monoclonal antibody, interstitial pneumonitis was induced in the lungs that were free of the virus with an excessive production of the cytokines. In the lungs of such mice persistently infected with MCMV, the mRNA of the cytokines such as IL-2, IL-6, TNF-alpha, and IFN-gamma were abundantly expressed 3 h after the anti-CD3 injection, and the elevated levels continued thereafter. A marked expression of inducible nitric oxide synthetase (iNOS) was then noted in the lungs, suggesting that such cytokines as TNF-alpha and IFN-gamma may have induced iNOS. Although the increase in NO formation was demonstrated by the significant elevation of the serum levels of nitrite and nitrate, the interstitial pneumonitis was not associated with either increased superoxide formation or peroxynitrite-induced tyrosine nitration. Nevertheless, the administration of an NO antagonist also alleviated the interstitial pneumonitis provoked by anti-CD3 mAb. Based on these findings, it was concluded that MCMV-associated pneumonitis is mediated by a molecule of cytokine-induced NO other than peroxynitrite.

Human cytomegalovirus infection up-regulates interleukin-8 gene expression and stimulates neutrophil transendothelial migration

Virus-induced alterations in the cellular expression of chemokines may be important in directing the migration of specific leucocyte subsets to sites of infection, thereby playing a pivotal role in viral pathogenesis. We show here that cytomegalovirus (CMV) infection of human fibroblasts resulted in significantly increased expression of the C-X-C or alpha-chemokine interleukin-8 (IL-8), at both the mRNA and protein levels. Increased IL-8 production was seen following infection with the high passage laboratory CMV strains AD169, Towne, or Davis, as well as the low passage clinical CMV isolates Toledo or C1F. The increase in IL-8 production had functional consequences, as demonstrated by the ability of supernatants from CMV-infected fibroblasts to significantly enhance neutrophil transendothelial migration. The latter was independent of alterations in adhesion molecule expression on the endothelial cells, and was abrogated by neutralizing antibodies specific for IL-8. Direct infection of endothelium with the endothelial cell-tropic CMV strain C1FE, also resulted in enhanced neutrophil transendothelial migration. Neutrophils play an important role in the dissemination of CMV throughout the body, and thus CMV-induced neutrophil recruitment would be expected to enhance CMV dissemination. Increased production of chemokines in response to CMV infection could also disrupt the fine balance between a beneficial and a destructive immune response, thereby potentially contributing to pathology.

Modulation of RANTES production by human cytomegalovirus infection of fibroblasts

Chemokines play a major role in inflammatory responses and affect hematopoiesis both negatively and positively. We show that fresh isolates and laboratory strains (Towne and Ad-169) of human cytomegalovirus (HCMV) induce production of the CC chemokine RANTES in fibroblasts. Induction of extracellular RANTES production occurred as early as 8 h after infection, peaked around 24 h after infection, and was almost undetectable by 48 and 72 h. Upregulation occurred in the absence of viral DNA synthesis, suggesting that it was due to immediate-early-early HCMV gene expression. CMV infection stimulated RANTES transcription, since reverse transcription-PCR detected a sharp increase in RANTES RNA which persisted even when extracellular RANTES was no longer detected. Induction of RANTES in fibroblasts was not due to prior induction of tumor necrosis factor alpha or interleukin 1 beta. Down-regulation required an active viral genome. Decrease of RANTES in culture supernatants may be associated with the appearance of the HCMV CC chemokine receptor US28, since we show that this gene is transcribed as early as 8 h after infection. Modulation of CC chemokine production early during CMV infection might have a regulatory effect on viral replication, as well as affect immune surveillance.

Soluble HLA class I in epithelial lining fluid of lung transplants: associations with graft outcome

We hypothesized that the small amounts of donor HLA-A and HLA-B proteins detected in the serum during organ allograft rejection are indicative of higher local releases within the graft itself. We determined the concentrations of total HLA class I (HLA-I) and, in selected cases, specific donor and host HLA-A and HLA-B proteins, in the epithelial lining fluid (ELF) sampled by bronchoalveolar lavage (BAL) of lung transplant recipients (n = 37) and of normal controls (n = 25). We found that 1) HLA-I proteins were enriched in the lung ELF relative to other proteins; 2) the concentration of HLA-I in the ELF of well-functioning transplants was similar to that in normal lungs; 3) HLA-I proteins and total proteins were elevated in the ELF of patients who developed chronic rejection or refractory acute rejection; 4) the concentration of HLA-I was correlated with the percentage of neutrophils but not with the percentage of lymphocytes in the ELF of transplanted lungs; and 5) only the percentage of lymphocytes was elevated in the ELF of transplant patients with active CMV infections. Total HLA-I from the ELF was found to contain a mixture of both donor- and recipient-type HLA-A and HLA-B proteins and the donor-type HLA-A2 was found to be highly enriched in the ELF relative to serum.