Adhesion molecules (E-selectin and ICAM-1) in pulmonary allograft rejection

Genetic effect of ischemia-reperfusion injury upon primary graft dysfunction and chronic lung allograft dysfunction in lung transplantation: evidence based on transcriptome data

The unclear mechanism that ischemia-reperfusion injury (IRI) contributes to the development of primary graft dysfunction (PGD) and chronic lung allograft dysfunction (CLAD) remains a major issue in lung transplantation. Differentially expressed PGD-related genes and CLAD-related genes during IRI (IRI-PGD common genes and IRI-CLAD common genes) were identified using GEO datasets (GSE127003, GSE8021, GSE9102) and GeneCards datasets. Enrichment analysis and four network analyses, namely, protein-protein interaction, microRNA (miRNA)-gene, transcription factor (TF)-gene, and drug-gene networks, were then performed. Moreover, GSE161520 was analyzed to identify the differentially expressed core miRNAs during IRI in rats. Finally, Pearson correlation analysis and ROC analysis were performed. Eight IRI-PGD common genes (IL6, TNF, IL1A, IL1B, CSF3, CXCL8, SERPINE1, and PADI4) and 10 IRI-CLAD common genes (IL1A, ICAM1, CCL20, CCL2, IL1B, TNF, PADI4, CXCL8, GZMB, and IL6) were identified. Enrichment analysis showed that both IRI-PGD and IRI-CLAD common genes were significantly enriched in "AGE-RAGE signaling pathway in diabetic complication" and "IL-17 signaling pathway". Among the core miRNAs, miR-1-3p and miR-335 were differentially expressed in IRI rats. Among core TFs, CEBPB expression had a significant negative correlation with P/F ratio (r = -0.33, P = 0.021). In the reperfused lung allografts, the strongest positive correlation was exhibited between PADI4 expression and neutrophil proportion (r = 0.76, P < 0.001), and the strongest negative correlation was between PADI4 expression and M2 macrophage proportion (r = -0.74, P < 0.001). In lung allografts of PGD recipients, IL6 expression correlated with activated dendritic cells proportion (r = 0.86, P < 0.01), and IL1B expression correlated with the neutrophils proportion(r = 0.84, P < 0.01). In whole blood of CLAD recipients, GZMB expression correlated with activated CD4+ memory T cells proportion (r = 0.76, P < 0.001).Our study provides the novel insights into the molecular mechanisms by which IRI contributes to PGD and CLAD and potential targets for therapeutic intervention.

Antibody-mediated rejection after lung transplantation

Antibody-mediated rejection (AMR) has been identified as a significant form of acute allograft dysfunction in lung transplantation. The development of consensus diagnostic criteria has created a uniform definition of AMR; however, significant limitations of these criteria have been identified. Treatment modalities for AMR have been adapted from other areas of medicine and data on the effectiveness of these therapies in AMR are limited. AMR is often refractory to these therapies, and graft failure and death are common. AMR is associated with increased rates of chronic lung allograft dysfunction (CLAD) and poor long-term survival. In this review, we discuss the history of AMR and describe known mechanisms, application of the consensus diagnostic criteria, data for current treatment strategies, and long-term outcomes. In addition, we highlight current gaps in knowledge, ongoing research, and future directions to address these gaps. Promising diagnostic techniques are actively being investigated that may allow for early detection and treatment of AMR. We conclude that further investigation is required to identify and define chronic and subclinical AMR, and head-to-head comparisons of currently used treatment protocols are necessary to identify an optimal treatment approach. Gaps in knowledge regarding the epidemiology, mechanisms, diagnosis, and treatment of AMR continue to exist and future research should focus on these aspects.

The role of C4d deposition in the diagnosis of antibody-mediated rejection after lung transplantation

Antibody-mediated rejection (AMR) is an increasingly recognized form of lung rejection. C4d deposition has been an inconsistent finding in previous reports and its role in the diagnosis has been controversial. We conducted a retrospective single-center study to characterize cases of C4d-negative probable AMR and to compare these to cases of definite (C4d-positive) AMR. We identified 73 cases of AMR: 28 (38%) were C4d-positive and 45 (62%) were C4d-negative. The two groups had a similar clinical presentation, and although more patients in the C4d-positive group had neutrophilic capillaritis (54% vs. 29%, P = .035), there was no significant difference in the presence of other histologic findings. Despite aggressive antibody-depleting therapy, 19 of 73 (26%) patients in the overall cohort died within 30 days, but there was no significant difference in freedom from chronic lung allograft dysfunction (CLAD) or survival between the two groups. We conclude that AMR may cause allograft failure, but that the diagnosis requires a multidisciplinary approach and a high index of suspicion. C4d deposition does not appear to be a necessary criterion for the diagnosis, and although some cases may respond initially to therapy, there is a high incidence of CLAD and poor survival after AMR.

E-Selectin Ligands in the Human Mononuclear Phagocyte System: Implications for Infection, Inflammation, and Immunotherapy

The mononuclear phagocyte system comprises a network of circulating monocytes and dendritic cells (DCs), and “histiocytes” (tissue-resident macrophages and DCs) that are derived in part from blood-borne monocytes and DCs. The capacity of circulating monocytes and DCs to function as the body’s first-line defense against offending pathogens greatly depends on their ability to egress the bloodstream and infiltrate inflammatory sites. Extravasation involves a sequence of coordinated molecular events and is initiated by E-selectin-mediated deceleration of the circulating leukocytes onto microvascular endothelial cells of the target tissue. E-selectin is inducibly expressed by cytokines (tumor necrosis factor-α and IL-1β) on inflamed endothelium, and binds to sialofucosylated glycan determinants displayed on protein and lipid scaffolds of blood cells. Efficient extravasation of circulating monocytes and DCs to inflamed tissues is crucial in facilitating an effective immune response, but also fuels the immunopathology of several inflammatory disorders. Thus, insights into the structural and functional properties of the E-selectin ligands expressed by different monocyte and DC populations is key to understanding the biology of protective immunity and the pathobiology of several acute and chronic inflammatory diseases. This review will address the role of E-selectin in recruitment of human circulating monocytes and DCs to sites of tissue injury/inflammation, the structural biology of the E-selectin ligands expressed by these cells, and the molecular effectors that shape E-selectin ligand cell-specific display. In addition, therapeutic approaches targeting E-selectin receptor/ligand interactions, which can be used to boost host defense or, conversely, to dampen pathological inflammatory conditions, will also be discussed.

Humoral responses after lung transplantation

PURPOSE OF REVIEW

In recent years, there has been increasing awareness and appreciation for the role of humoral immune responses in lung allograft rejection. This review summarizes our current understanding of this role and the associated challenges.

RECENT FINDINGS

Recent studies have described a syndrome of acute antibody-mediated rejection with a generally poor response to therapy and a high mortality. In addition, there is significant evidence implicating donor-specific human leukocyte antigen antibodies in the development of chronic lung allograft dysfunction. However, the optimal intervention to mitigate the risk of chronic lung allograft dysfunction after donor-specific human leukocyte antigen antibodies development remains unclear.

SUMMARY

There is mounting evidence that humoral immune responses play an important role in lung allograft rejection. However, therapeutic implications of this increased awareness have been limited. Indeed, there is insufficient evidence to adequately guide therapy, and the optimal treatment is unknown.

E-Selectin Mediates Immune Cell Trafficking in Corneal Transplantation

BACKGROUND

Immune rejection continues to threaten all tissue transplants. Here we sought to determine whether platelet (P)- and endothelial (E)-selectin mediate T cell recruitment in corneal transplantation and whether their blockade can reduce T cell graft infiltration and improve long-term corneal allograft survival.

METHODS

In a murine model of allogeneic corneal transplantation, we used PCR and immunohistochemistry to investigate expression of P- and E-selectin in rejected versus accepted allografts and lymph node flow cytometry to assess expression of selectin ligands by effector T cells. Using P- and E-selectin neutralizing antibodies, we evaluated the effect of blockade on CD4 T cell recruitment, as well as the effect of anti-E-selectin on long-term allograft survival.

RESULTS

The P- (93.3-fold, P < 0.05) and E-selectin (17.1-fold, P < 0.005) are upregulated in rejected versus accepted allogeneic transplants. Type 1 T helper cells from hosts with accepted and rejected grafts express high levels of P-selectin glycoprotein ligand 1 and glycosylated CD43. In vivo blockade of P (0.47 ± 0.03, P < 0.05) and E selectin (0.49 ± 0.1, P < 0.05) reduced the number of recruited T cells compared with IgG control (0.98 ± 0.1). Anti-E-selectin reduced the number of mature antigen-presenting cells trafficking to lymphoid tissue compared with control (6.96 ± 0.9 vs 12.67 ± 0.5, P < 0.05). Anti-E-selectin treatment delayed graft rejection and increased survival compared with control, although this difference did not reach statistical significance.

CONCLUSIONS

In a model of corneal transplantation, P- and E-selectin mediate T cell recruitment to the graft, E-selectin mediates APC trafficking to lymphoid tissue, and blockade of E-selectin has a modest effect on improving long-term graft survival.

Antibody-mediated Rejection in Lung Transplantation

There has been increasing awareness of antibody-mediated rejection (AMR) as an important cause of graft failure after lung transplantation in recent years. However, the diagnostic criteria for pulmonary AMR are not well defined. All four tenets of AMR in kidney and heart transplantation, graft dysfunction, complement component deposition, circulating donor-specific antibodies (DSA), and histopathologic changes consistent with AMR, are infrequently present in lung transplantation. Nonetheless, the lung transplant community has made important progress recognizing cases of AMR and developing a definition. However, AMR is often refractory to therapy resulting in graft failure and death. In this review, we discuss the progress and challenges in the diagnosis and therapeutic options for pulmonary AMR. In addition, we briefly examine emerging paradigms of C4d-negative AMR and chronic AMR, and conclude that significant progress is needed to mitigate the effects of humoral immune responses after lung transplantation.

Dendrimer-Inspired Nanomaterials for the in Vivo Delivery of siRNA to Lung Vasculature

Targeted RNA delivery to lung endothelial cells has the potential to treat conditions that involve inflammation, such as chronic asthma and obstructive pulmonary disease. To this end, chemically modified dendrimer nanomaterials were synthesized and optimized for targeted small interfering RNA (siRNA) delivery to lung vasculature. Using a combinatorial approach, the free amines on multigenerational poly(amido amine) and poly(propylenimine) dendrimers were substituted with alkyl chains of increasing length. The top performing materials from in vivo screens were found to primarily target Tie2-expressing lung endothelial cells. At high doses, the dendrimer-lipid derivatives did not cause chronic increases in proinflammatory cytokines, and animals did not suffer weight loss due to toxicity. We believe these materials have potential as agents for the pulmonary delivery of RNA therapeutics.

Cardiac allograft vasculopathy: a donor or recipient induced pathology?

Cardiac allograft vasculopathy (CAV) is one of the main causes of late-stage heart failure after heart transplantation. CAV is characterized by concentric luminal narrowing of the coronary arteries, but the exact pathogenesis of CAV is still not unraveled. Many researchers show evidence of an allogeneic immune response of the recipient, whereas others show contrasting results in which donor-derived cells induce an immune response against the graft. In addition, fibrosis of the neo-intima can be induced by recipient-derived circulating cells or donor-derived cells. In this review, both donor and recipient sides of the story are described to obtain better insight in the pathogenesis of CAV. Dual outcomes were found regarding the contribution of donor and recipient cells in the initiation of the immune response and the development of fibrosis during CAV. Future research could focus more on the potential synergistic interaction of donor and recipient cells leading to CAV.

Acute antibody-mediated rejection after lung transplantation

BACKGROUND

Antibody-mediated rejection (AMR) after lung transplantation remains enigmatic, and there is no consensus on the characteristic clinical, immunologic and histologic features.

METHODS

We performed a retrospective, single-center cohort study and identified cases of acute AMR based on the presence of circulating donor-specific human leukocyte antigen (HLA) antibodies (DSA), histologic evidence of acute lung injury, C4d deposition and clinical allograft dysfunction.

RESULTS

We identified 21 recipients with acute AMR based on the aforementioned criteria. AMR occurred a median 258 days after transplantation; 7 recipients developed AMR within 45 days of transplantation. All patients had clinical allograft dysfunction, DSA, histology of acute lung injury and capillary endothelial C4d deposition. Fifteen recipients improved clinically and survived to hospital discharge, but 6 died of refractory AMR. One survivor had bronchiolitis obliterans syndrome at the time of AMR diagnosis; 13 of the 14 remaining survivors developed chronic lung allograft dysfunction (CLAD) during follow-up. Overall, 15 recipients died during the study period, and the median survival after the diagnosis of AMR was 593 days.

CONCLUSIONS

Acute AMR can be a fulminant form of lung rejection, and survivors are at increased risk of developing CLAD. The constellation of acute lung injury, DSA and capillary endothelial C4d deposition is compelling for acute AMR in recipients with allograft dysfunction. This clinicopathologic definition requires validation in a multicenter cohort, but may serve as a foundation for future studies to further characterize AMR.

Small interfering RNA efficiently suppresses adhesion molecule expression on pulmonary microvascular endothelium

Background. Adhesion molecules are known to influence postoperative organ function, they are hardly involved in the inflammatory response following the ischemia-reperfusion injury. We sought to investigate the potency of small interfering RNAs to suppress adhesion molecule expression in human pulmonary microvascular endothelial cells. Methods. Human lung microvascular endothelial cells were transfected with specific siRNA followed by a stimulation of the cells with an inflammatory cytokine. Adhesion molecule expression was determined by FACS-analysis, and reduction of intracellular mRNA was determined by qRT-PCR. Furthermore, the attachment of isolated neutrophils on the endothelial layer was determined after siRNA transfection. Results. In summary, siRNA transfection significantly decreased the percentage positive cells in a single cocktail transfection of each adhesion molecule investigated. Adhering neutrophils were diminished as well. Conclusion. siRNA might be a promising tool for the effective suppression of adhesion molecule expression on pulmonary microvascular cells, potentially minimizing leukocyte-endothelial depending interactions of a pulmonary allograft.

Inhibition of adhesion molecule expression on human venous endothelial cells by non-viral siRNA transfection

Objective: Expression of adhesion molecule receptors on venous endothelial cells crucially influences the fate of venous grafts by mediating leukocyte-endothelium interactions. These interactions include adhesion of leukocytes to the endothelium, followed by transendothelial migration, leading to neointimal hyperplasia and finally graft occlusion. Therefore, inhibition of adhesion molecule expression may be a promising strategy to improve the quality of venous grafts. We tested the efficiency of non-viral transfection of human venous endothelial cells with short interfering RNA (siRNA) to specificially down-regulate adhesion molecule expression. Methods: Primary cultures of human venous endothelial cells (HVEC) were examined for expression of the adhesion molecules ICAM1, VCAM1 and E-selectin (SELE) after non viral siRNA transfection. Adhesion molecule expression was measured by flow cytometry, real-time PCR and immunoblotting after stimulation with TNF-alpha, an inflammatory cytokine. Results: Non-transfected cells showed a strong increase of adhesion molecule expression following cytokine stimulation (p<0.01). Upon transfection with specific siRNAs a six fold decrease in ICAM1 (p<0.001) and SELE expression and cell positivity (p<0.05) and a twofold decrease in VCAM1 expression and cell positivity (p<0.01) could be observed. SiRNA-mediated gene suppression of adhesion molecules was also reflected by corresponding decreases in adhesion protein and transcript levels. Conclusions: The expression of adhesion molecules on HVECs can be effectively inhibited by specific siRNAs using a safe, non-viral transfection approach. This is a promising tool to precondition venous bypass grafts in order to interfere with endothelium-leukocyte interactions and to prohibit neointima thickening or atherosclerosis, which are regarded to be the most important causes of venous graft failure.

Importance of donor- and recipient-derived selectins in cardiac allograft rejection

The selectins expressed on activated endothelial cells (E- and P-selectin), leukocytes (L-selectin), and platelets (P-selectin) play crucial roles in the rolling and tethering of leukocytes. We explored the importance of donor and recipient selectins in acute and chronic cardiac allograft rejection using mice deficient in all three selectins (ELP-/-). In BALB/c recipients, survival of fully allomismatched hearts from ELP-/- C57BL/6 donors was almost double that of wild-type grafts. In ELP-/- cardiac allografts, mononuclear cell infiltration and vasculitis of intramyocardial coronary arteries were significantly reduced. Interestingly, ELP-/- grafts were rejected similarly in both the presence and the absence of recipient selectins, and both wild-type and ELP-/- recipients promptly rejected wild-type hearts. Alternative adhesive molecules such as alpha4beta7 integrin may compensate for the lack of selectins and may mediate rejection in ELP-/- recipients. Chronic rejection was evaluated in a major histocompatibility complex (MHC) class II mismatch model using C57BL/6.C-H2(bm12) mice. While lack of selectins in recipients did not offer protection against chronic rejection, luminal stenosis of coronary arteries in ELP-/- grafts was markedly diminished. In conclusion, donor-derived selectins contribute to the development of both acute and chronic cardiac allograft rejection, and targeting donor selectins may open novel therapeutic approaches in clinical transplantation.

Inhibition of adhesion molecule expression on human venous endothelial cells by non-viral siRNA transfection

Objective:

Expression of adhesion molecule receptors on venous endothelial cells crucially influences the fate of venous grafts by mediating leukocyte-endothelium interactions. These interactions include adhesion of leuko-cytes to the endothelium, followed by transendothelial migration, leading to neointimal hyperplasia (NIH) and finally graft occlusion. Therefore, inhibition of adhesion molecule expression may be a promising strategy to improve the quality of venous grafts.We tested the efficiency of non-viral transfection of human venous endothe-lial cells (HVEC) with short interfering RNA (siRNA) to specifically down-regulate adhesion molecule expression.

Methods:

Primary cultures of HVEC were examined for expression of the adhesion molecules ICAM1, VCAM1 and E-selectin (SELE) after non viral siRNA transfection. Adhesion molecule expression was measured by flow cytom-etry, real-time polymerase chain reaction and immunoblotting after stimulation with TNF-α, an inflammatory cytokine.

Results:

Non-transfected cells showed a strong increase of adhesion molecule expression following cytokine stimulation (P < 0.01). Upon transfection with specific siRNAs a sixfold decrease in ICAM1 (P < 0.001) and SELE expression and cell positivity (P < 0.05) and a twofold decrease in VCAM1 expression and cell positiv-ity (P < 0.01) Pcould be observed. SiRNA-mediated gene suppression of adhesion molecules was also reflected by corresponding decreases in adhesion protein and transcript levels.

Conclusions:

The expression of adhesion molecules on HVECs can be effectively inhibited by specific siRNAs using a safe, non-viral transfection approach. This is a promising tool to pre-condition venous bypass grafts in order to interfere with endothelium-leukocyte interactions and to prohibit neointima thickening or ath-erosclerosis, which are regarded to be the most important causes of venous graft failure.

IL-12 p80 is an innate epithelial cell effector that mediates chronic allograft dysfunction

RATIONALE

Bronchiolitis obliterans syndrome is the leading cause of chronic lung allograft dysfunction. We have demonstrated that respiratory viral infection is a bronchiolitis obliterans syndrome risk factor and virus-dependent injury induces expression of innate airway epithelial genes belonging to the interleukin (IL)-12 family. Thus, we hypothesized that epithelial cell IL-12 family members could mediate lung allograft dysfunction.

OBJECTIVES

We used mouse and human allograft specimens to evaluate the role of epithelial cell IL-12 family members in allograft dysfunction associated with and without viral infection.

METHODS

Murine and human IL-12 family members were characterized and manipulated in allografts and then correlated with epithelial cell injury, immune cell accumulation, and collagen deposition.

RESULTS

In a mouse model of lung transplantation, concurrent viral infection and allogeneic transplantation increased epithelial injury and this was followed by exaggerated accumulation of macrophages and collagen deposition. This virus-driven allograft dysfunction was associated with an epithelial innate response manifested by a synergistic increase in the production of the macrophage chemoattractant IL-12 p80 (p80), but not IL-12 or IL-23. Blockade or overexpression of donor epithelial p80 resulted in a corresponding abrogation or enhancement of macrophage accumulation and allograft dysfunction. We extended these findings to human recipients with viral infection and transplant bronchitis and again observed excessive epithelial p80 expression that correlated with increased macrophage accumulation.

CONCLUSIONS

These experiments support a role for an enhanced epithelial innate response as a central process in allograft dysfunction and identify the macrophage chemoattractant p80 as an innate epithelial effector of disease progression.

Community acquired respiratory viral infections after lung transplantation: clinical features and long-term consequences

Community acquired respiratory viruses (CARVs) are increasingly recognized as serious threats to lung transplant recipients. While CARVs such as respiratory syncytial virus, parainfluenza, influenza, and adenovirus usually cause self-limited illnesses in immunocompetent subjects, infections in the transplant recipient can be dramatic. As transplant recipients live longer and diagnostic methods improve, the burden of CARVs will undoubtedly increase. Because of limited therapeutic options, some patients may succumb to CARV infections, while many survivors develop chronic allograft dysfunction. Recognition of this latter phenomenon has implicated CARVs in the pathogenesis of bronchiolitis obliterans.

The participation of P- and E-selectins on biomaterial-mediated tissue responses

Biomaterial-mediated inflammatory responses often compromise the functions of implantable devices. The mechanism(s) involved in the inflammatory responses, which can be arbitrarily divided into phagocyte transmigration, chemotaxis, and adhesion to implant surfaces, are not totally understood. Because adhesion molecules have been shown to involved in phagocyte transmigration, this study was designed to investigate the participation of endothelial adhesion molecules in the pathogenesis of biomaterial-mediated inflammatory responses and fibrotic tissue formation. Using transgenic adhesion molecule knockout mice, we found that (1) deficiency of P-selectin reduced polymorphonuclear neutrophils (PMN) but not macrophages/monocytes (Mphi) transmigration and adhesion. (2) Furthermore, absence of both P- and E-selectin (P/E-deficient) dramatically diminished both PMN and Mphi recruitment to the peritoneal cavity and accumulation on implanted biomaterials. (3) Finally, the impairment of inflammatory responses in P/E-deficient mice significantly reduced the extent of subsequent biomaterial-mediated fibrotic responses. We conclude that P- and E-selectins are important for both biomaterial-mediated inflammatory and fibrotic reactions. Our results also indicate that the reduction of phagocyte accumulation might be responsible to the decrease of fibrotic tissue formation surrounding material implants. Better understanding of such sequence of events may help the rational design of biomaterials with desired tissue reactivity.

Alveolar neutrophilia is a predictor for the bronchiolitis obliterans syndrome, and increases with degree of severity

BACKGROUND

Bronchiolitis obliterans syndrome (BOS) is a common complication of lung transplantation (LT), associated with a tremendous mortality and morbidity. Recent innovative research has focused on bronchoalveolar lavage (BAL) analysis, assuming that neutrophilia might be a marker of chronic rejection.

PATIENTS AND METHODS

To address this issue, we retrospectively analyzed 258 sequential BAL from 44 lung transplant recipients, having survived for more than 3 months after surgery.

RESULTS

At the end of the follow-up, 22, 7, 7 and 8 patients had BOS stage 0, 1, 2 and 3, respectively. The total cell count and neutrophilia increased with BOS severity (P < 0.01). BOS occuring before and after the 12th month of LT were associated with early and more delayed increases of BAL neutrophils, respectively. Finally, the various kinetic profiles of neutrophil progression were identified, allowing for an earlier identification of BOS stages 2 and 3, by 3 and 6 months, respectively. Conversely, neutrophilia associated to BOS stage 1 remained low, and could not be distinguished from that of stage 0.

CONCLUSIONS

These results support the possible role of neutrophils in BOS pathogenesis, and may be of interest for an earlier detection and management of chronic 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.

A minor E-selectin ligand, CD65, is critical for extravascular infiltration of acute myeloid leukemia cells

Adhesive ligands on acute myeloid leukemic (AML) blasts may mediate transmigration and extravascular infiltration. In this study, 30 AML samples were examined for expression and density of adhesion antigens. By univariate analysis, four patients with extravascular infiltration showed significantly higher expression of CD2, CD11a, CD11b, CD11c, CD15, CD65, CD86, and HLA-DR as compared with patients without infiltration. These four patients also showed significantly higher density of CD11a, CD11b, CD11c, CD15 and CD65 expression. By multivariate analysis, CD65 expression was the only significant independent risk factor for infiltration, suggesting that this is a critical adhesion molecule for extravascular AML infiltration.

Immune cells and immunosuppression in a porcine bronchial model of obliterative bronchiolitis

BACKGROUND

To study obliterative bronchiolitis (OB), we have developed a porcine heterotopic bronchial model. Allografts obliterate within 3 weeks, the immunosuppression cyclosporine (CsA)-azathioprine (AZA)-methylprednisolone (MP) delays OB, but OB is prevented when AZA is switched to 40-0-(2-hydroxyethyl)-rapamycin (RAD). To characterize our model, we studied immune cells under various immunosuppressive conditions.

METHODS

The groups studied were autografts (U), allografts (A), and allografts given either CsA-RAD-MP (R), or CsA-AZA-MP (C). The implants were harvested at 3, 7, 10, 14, 21, 30, 60, and 90 days after transplantation. Epithelial damage and obliteration were graded histologically, and the number of CD4, CD8, MHC class II expressing cells, macrophages, and B lymphocytes were counted (mean+SEM)/high-power visual field.

RESULTS

In group U, normal epithelium was regained with no obliteration and only few immune cells. In group A, consistent with initially acute ejection, an influx of CD4 (105+23), CD8 (166+23), and class II (92+20) cells was seen up to day 21, when total obliteration preceded by epithelial destruction had already developed. Some macrophages were seen and B cells were scarce. In group R, epithelial damage and obliteration were insignificant, but moderate numbers of CD4, CD8, and class II cells were seen. In group C, epithelial damage and obliteration were only delayed, but the immune cell response was clearly blunted.

CONCLUSIONS

In our model, rejection with significant immune cell influx was still active when obliteration was total in nontreated allografts. In immunosuppressed allografts, decrease in the number of immune cells alone did prevent OB. These results support OB being T-cell mediated. RAD may have additional important effects on growth factors and proliferation in prevention of OB.

Early lung leukocyte infiltration, HLA and adhesion molecule expression predict chronic rejection

Obliterative bronchiolitis remains the main cause of graft dysfunction and death after 1 year. Defined by an irreversible airway obstruction, bronchiolitis obliterans syndrome is usually recognized in the advanced stage of the disease, with histological evidence of fibrotic damage. Fibrosis represents the end-stage of an inflammatory process, leading to the postulate that chronic lung graft dysfunction is preceded by cellular and molecular events. This study was performed during the first year following lung transplantation, in the absence of histological or functional criteria of chronic rejection. Transbronchial biopsies from eight lung allografts were examined. Four developed a bronchiolitis obliterans syndrome (Group I), and 4 had good outcomes (Group II) at 2 years. Using immunohistochemistry, the aim of the study was to correlate early immunological events with graft outcomes at 2 years. An up-regulation of HLA class I antigen (P = 0.0001), an overexpression of Ki-67 (P = 0.006) on bronchial epithelium, and graft infiltration by CD45+, CD25+ cells (P = 0.003) were significantly associated with the development of chronic rejection. An overexpression of numerous adhesion molecules was observed. However, only very late antigen-4 had a discriminative value (P = 0.04), preceding chronic graft dysfunction. Our results suggest that graft dysfunction is associated with early molecular and cellular events, and raises the possibility that a fibroproliferative disorder is initiated shortly after transplantation. The recognition of such early immunological markers might facilitate improved graft management and prognosis.

Increased expression of inflammatory cytokines and adhesion molecules by alveolar macrophages of human lung allograft recipients with acute rejection: decline with resolution of rejection

BACKGROUND

Alveolar macrophages (AM) are the major population in bronchoalveolar lavage (BAL) cells; we assessed their role in human lung allograft recipients by correlating the expression of adhesion molecules and inflammatory cytokines with clinical outcome of allograft.

METHODS

We obtained BAL samples from patients and enriched them for AM in plastic petri dish for 2 hours at 37 degrees C in 5% CO(2). Expression of intercellular adhesion molecule-1 (ICAM-1, CD54), platelet endothelial cell adhesion molecule-1 (PECAM-1, CD31), and CD11c was assessed by flow cytometry using monoclonal antibodies. We assessed cytokine profile using Multi-Probe RNase protection assay.

RESULTS

Alveolar macrophages that express CD11c, CD31 and CD54 were increased in patients with either rejection or infection compared with those without rejection and infection. The difference in the percentage of AM expressing CD11c and CD31 between the rejection group and patients without rejection and infection group was statistically significant (CD11c, p < 0.01; CD31, p < 0.03). Interleukin (IL)-1 alpha, IL-1 beta, IL-1 receptor antagonist (IL-1Ra), and IL-6 expression was higher in the rejection group than in patients without rejection. Five out of 9 patients in the rejection group expressed high levels of IL-15 and tumor necrosis factor-alpha compared with patients without rejection and infection. The increased number of AM expressing adhesion molecules and elevated expression of cytokines observed during acute rejection declined to basal levels after successful treatment and resolution of rejection. This study demonstrates that lung allograft rejection is associated with increased expression of adhesion molecules and inflammatory cytokines by AM, which could facilitate mononuclear cell adhesion and extravasation contributing to the allograft injury in lung transplant recipients.

Antisense intercellular adhesion molecule-1 (ICAM-1) oligodeoxyribonucleotide delivered during organ preservation inhibits posttransplant ICAM-1 expression and reduces primary lung isograft failure

Transiently increased expression of leukocyte adhesion receptors after lung preservation contributes to early graft demise by recruiting leukocytes, activating complement, and causing microcirculatory stasis. We hypothesized that inhibiting intercellular adhesion molecule-1 (ICAM-1) expression even briefly may significantly improve lung graft function and that the preservation period might provide a unique window to deliver a therapeutic pulse of antisense oligonucleotide ICAM-1 to inhibit ICAM-1 expression after transplantation. Interleukin-1beta-treated rat pulmonary endothelial cells given a 20-mer phosphorothioate oligonucleotide comprising an antisense span targeted to the 3'-untranslated region of rat ICAM-1 demonstrated an oligonucleotide dose-dependent reduction in ICAM-1 expression. Using a cationic liposomal carrier, this same antisense oligonucleotide (but not the sense control) instilled into the pulmonary vasculature at the time of preservation reduced subsequent graft ICAM-1 expression and graft leukostasis and markedly improved oxygenation, pulmonary blood flow, and graft survival. These experiments demonstrate that the preservation period presents a window during which to target an anti-ICAM-1 expression strategy to inhibit early adhesion receptor expression and improve functional outcome after lung transplantation.

Surveillance transbronchial lung biopsies: implication for survival after lung transplantation

OBJECTIVES

We wished to determine whether early rejection after lung transplantation as assessed by surveillance transbronchial biopsy predicts for survival.

METHODS

Between 1990 and 1997, 96 consecutive patients had lung transplantation: 89 had a minimum 1-month follow-up. For 71 consecutive patients we have 1-year follow-up and for 69 patients we have the results of the first 3 biopsies. Cytomegalovirus status, bronchiolitis obliterans prevalence, and use of total lymphoid irradiation are noted. Biopsies were done at 1 week and 1, 3, and 6 months. Standard immunosuppression consisted of induction antilymphocyte globulin and high-dose methylprednisolone induction for 1 week and standard maintenance triple therapy. Acute rejection treatment was with pulse methylprednisolone. Bronchiolitis obliterans syndrome was treated with total lymphoid irradiation and a change to tacrolimus and mycophenolate. Blinded grading using International Society for Heart and Lung Transplantation classification was done retrospectively.

RESULTS

Survival at 1 month and 1, 2, and 3 years for the 96-patient cohort with 1-year follow-up was 93%, 74%, 62%, and 56%. Survival was not significantly different for subsets with rejection on any combination of the first 3 biopsies (1/3, 2/3, 3/3) or absence of rejection on the first 3 biopsies. Ninety-one positive biopsy results were graded. Eighteen of 71 patients had one or more moderate or severe rejection episodes without survival difference relative to the others. There was no statistically significant association between acute rejection on the first 3 surveillance biopsy results and bronchiolitis obliterans.

CONCLUSIONS

Intensive induction and maintenance immunotherapy with surveillance transbronchial biopsies and aggressive treatment of acute rejection is associated with a survival similar to that of patients without early acute rejection. This regimen appears to uncouple the association between early acute rejection and bronchiolitis obliterans. Further study may elucidate this mechanism.

Adhesion molecules in patients after lung transplantation

Leukocyte adhesion molecules, such as intercellular adhesion molecule (ICAM)-1 and its ligands, are involved in inflammatory processes of the lung. For ICAM-1, differential expression during different kinds of complications after transplantation has been proposed. We analyzed the role of ICAM-1, CD18, CD11a, CD11b, and CD11c during episodes of rejection or infection in patients after lung transplantation and compared the results to episodes without apparent complication. A total of 98 bronchoalveolar lavage (BAL) samples and 90 serum samples were analyzed. ICAM-1, CD18, CD11a, CD11b, and CD11c expressions were detected immunocytochemically on alveolar macrophages. Soluble ICAM-1 was quantified in serum and BAL. In the control group, 49.8 +/- 18% of macrophages stained positive for CD11b. During rejection, the mean of cells showing CD11b on the surface was significantly higher (64.6 +/-11.4%) with no difference compared to episodes of infection (59.7 +/-22.7). All other epitopes were not expressed differently with regard to a normal clinical course or episodes of infection and rejections. In summary, assessment of ICAM-1 and corresponding ligands did not allow for a reliable discrimination between episodes of rejection or infection in lung transplantation.

Perioperative management of patients undergoing lung transplantation

This review focuses on recent developments in the perioperative management of patients undergoing lung transplantation. Relevant current literature and the experience of the Munich Lung Transplant Group were taken into consideration. Recent advances include the use of inhalational nitric oxide for the treatment of early graft dysfunction and the use of aerosolized cyclosporine for the treatment of recurrent and steroid-resistant acute rejection. Opportunistic infections remain a major source of morbidity and mortality in lung transplant recipients.