Chemokine redundancy in BOS pathogenesis. A possible role also for the CC chemokines: MIP3-beta, MIP3-alpha, MDC and their specific receptors

Fifteen-Year Surveillance of LTR Receiving Pre-Emptive Therapy for CMV Infection: Prevention of CMV Disease and Incidence of CLAD

The efficacy of pre-emptive therapy in the prevention of cytomegalovirus (CMV) disease and the potential association of CMV infection with the occurrence of chronic lung allograft dysfunction (CLAD) was evaluated in 129 lung transplant recipients receiving pre-emptive therapy based on pp65-antigenemia or CMV-DNA in the blood and in the bronchoalveolar lavage. Seventy-one (55%) patients received pre-emptive ganciclovir/valganciclovir (GCV/VGCV) for CMV infection for a median of 28 (9-191) days. Possible CMV disease occurred in six (5%) patients and was healed after the GCV/VGCV therapy. The cumulative incidence of CLAD was 38% and 54% at 5 and 10 years. Acute rejection and CMV load in the blood (but not in the lung) were independent predictors of the occurrence of CLAD. Pre-emptive therapy is highly effective in preventing CMV disease in lung recipients and does not induce a superior incidence of CLAD compared to what reported for other cohorts of patients who received an extended antiviral prophylaxis.

Chronic Lung Allograft Dysfunction Is Associated with Increased Levels of Cell-Free Mitochondrial DNA in Bronchoalveolar Lavage Fluid of Lung Transplant Recipients

Chronic Lung Allograft Dysfunction (CLAD) is a life-threatening complication that limits the long-term survival of lung transplantation patients. Early diagnosis remains the basis of efficient management of CLAD, making the need for distinctive biomarkers critical. This explorative study aimed to investigate the predictive power of mitochondrial DNA (mtDNA) derived from bronchoalveolar lavages (BAL) to detect CLAD. The study included 106 lung transplant recipients and analyzed 286 BAL samples for cell count, cell differentiation, and inflammatory and mitochondrial biomarkers, including mtDNA. A receiver operating curve analysis of mtDNA levels was used to assess its ability to detect CLAD. The results revealed a discriminatory pro-inflammatory cytokine profile in the BAL fluid of CLAD patients. The concentration of mtDNA increased in step with each CLAD stage, reaching its highest concentration in stage 4, and correlated significantly with decreasing FEV1. The receiver operating curve analysis of mtDNA in BAL revealed a moderate prediction of CLAD when all stages were grouped together (AUROC 0.75, p-value < 0.0001). This study has found the concentration mtDNA in BAL to be a potential predictor for the early detection of CLAD and the differentiation of different CLAD stages, independent of the underlying pathology.

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.

Effector immune cells in Chronic Lung Allograft Dysfunction: a Systematic Review

Chronic lung allograft dysfunction (CLAD) remains the major barrier to long‐term survival after lung transplantation and improved insight into its underlying immunological mechanisms is critical to better understand the disease and to identify treatment targets. We systematically searched the electronic databases of PubMed and EMBASE for original research publications, published between January 2000 and April 2021, to comprehensively assess current evidence on effector immune cells in lung tissue and bronchoalveolar lavage fluid from lung transplant recipients with CLAD. Literature search revealed 1351 articles, 76 of which met the criteria for inclusion in our analysis. Our results illustrate significant complexity in both innate and adaptive immune cell responses in CLAD, along with presence of numerous immune cell products, including cytokines, chemokines and proteases associated with tissue remodelling. A clear link between neutrophils and eosinophils and CLAD incidence has been seen, in which eosinophils more specifically predisposed to restrictive allograft syndrome. The presence of cytotoxic and T‐helper cells in CLAD pathogenesis is well‐documented, although it is challenging to draw conclusions about their role in tissue processes from predominantly bronchoalveolar lavage data. In restrictive allograft syndrome, a more prominent humoral immune involvement with increased B cells, immunoglobulins and complement deposition is seen. Our evaluation of published studies over the last 20 years summarizes the complex multifactorial immunopathology of CLAD onset and progression. It highlights the phenotype of several key effector immune cells involved in CLAD pathogenesis, as well as the paucity of single cell resolution spatial studies in lung tissue from patients with CLAD.

Indispensable Role of CX3CR1+ Dendritic Cells in Regulation of Virus-Induced Neuroinflammation Through Rapid Development of Antiviral Immunity in Peripheral Lymphoid Tissues

A coordinated host immune response mediated via chemokine network plays a crucial role in boosting defense mechanisms against pathogenic infections. The speed of Ag presentation and delivery by CD11c⁺ dendritic cells (DCs) to cognate T cells in lymphoid tissues may decide the pathological severity of the infection. Here, we investigated the role of CX₃CR1 in the neuroinflammation induced by infection with Japanese encephalitis virus (JEV), a neurotrophic virus. Interestingly, CX₃CR1 deficiency strongly enhanced susceptibility to JEV only after peripheral inoculation via footpad. By contrast, both CX₃CR1^+/+ and CX₃CR1^-/- mice showed comparable susceptibility to JEV following inoculation via intranasal and intraperitoneal routes. CX₃CR1^-/- mice exhibited lethal neuroinflammation after JEV inoculation via footpad route, showing high mortality, morbidity, pro-inflammatory cytokine expression, and uncontrolled CNS-infiltration of peripheral leukocytes including Ly-6C^hi monocytes and Ly-6G^hi granulocytes. Furthermore, the absence of CX₃CR1⁺CD11c⁺ DCs appeared to enhance susceptibility of CX₃CR1^-/- mice to JE after peripheral JEV inoculation. CX₃CR1 ablation impaired the migration of CX₃CR1⁺CD11c⁺ DCs from JEV-inoculated sites to draining lymph nodes (dLNs), resulting in decreased NK cell activation and JEV-specific CD4⁺/CD8⁺ T-cell responses. However, CX₃CR1-competent mice showed rapid temporal expression of viral Ags in dLNs. Subsequently, JEV was rapidly cleared, with concomitant generation of antiviral NK cell activation and T-cell responses mediated by rapid migration of JEV Ag⁺CX₃CR1⁺CD11c⁺ DCs. Using biallelic functional CX₃CR1 expression system, the functional expression of CX₃CR1 on CD11c^hi DCs appeared to be essentially required for inducing rapid and effective responses of NK cell activation and Ag-specific CD4⁺ T cells in dLNs. Strikingly, adoptive transfer of CX₃CR1⁺CD11c⁺ DCs was found to completely restore the resistance of CX₃CR1^-/- recipients to JEV, as corroborated by the rapid delivery of JEV Ags in dLNs and attenuation of neuroinflammation in the CNS. Collectively, these results indicate that CX₃CR1⁺CD11c⁺ DCs play an important role in generating rapid and effective responses of antiviral NK cell activation and Ag-specific T cells after peripheral inoculation with the virus, thereby resulting in conferring resistance to viral infection by reducing the peripheral viral burden.

A Pilot Study to Investigate the Balance between Proteases and α1-Antitrypsin in Bronchoalveolar Lavage Fluid of Lung Transplant Recipients

The neutrophilic component in bronchiolitis obliterans syndrome (BOS, the main form of chronic lung rejection), plays a crucial role in the pathogenesis and maintenance of the disorder. Human Neutrophil Elastase (HNE), a serine protease responsible of elastin degradation whose action is counteracted by α1-antitrypsin (AAT), a serum inhibitor specific for this protease. This work aimed to investigate the relationship between HNE and AAT in bronchoalveolar lavage fluid (BALf) from stable lung transplant recipients and BOS patients to understand whether the imbalance between proteases and inhibitors is relevant to the development of BOS. To reach this goal a multidisciplinary procedure was applied which included: (i) the use of electrophoresis/western blotting coupled with liquid chromatography-mass spectrometric analysis; (ii) the functional evaluation of the residual antiprotease activity, and (iii) a neutrophil count. The results of these experiments demonstrated, for the first time, the presence of the complex between HNE and AAT in a number of BALf samples. The lack of this complex in a few specimens analyzed was investigated in relation to a patient’s lung inflammation. The neutrophil count and the determination of HNE and AAT activities allowed us to speculate that the presence of the complex correlated with the level of lung inflammation.

Dual TLR2/9 Recognition of Herpes Simplex Virus Infection Is Required for Recruitment and Activation of Monocytes and NK Cells and Restriction of Viral Dissemination to the Central Nervous System

The importance of TLR2 and TLR9 in the recognition of infection with herpes simplex virus (HSV) and HSV-caused diseases has been described, but some discrepancies remain concerning the benefits of these responses. Moreover, the impact of TLR2/9 on innate and adaptive immune responses within relevant mucosal tissues has not been elucidated using natural mucosal infection model of HSV. Here, we demonstrate that dual TLR2/9 recognition is essential to provide resistance against mucosal infection with HSV via an intravaginal route. Dual TLR2/9 ablation resulted in the highly enhanced mortality with exacerbated symptoms of encephalitis compared with TLR2 or TLR9 deficiency alone, coinciding with highly increased viral load in central nervous system tissues. TLR2 appeared to play a minor role in providing resistance against mucosal infection with HSV, since TLR2-ablated mice showed higher survival rate compared with TLR9-ablated mice. Also, the high mortality in dual TLR2/9-ablated mice was closely associated with the reduction in early monocyte and NK cell infiltration in the vaginal tract (VT), which was likely to correlate with low expression of cytokines and CCR2 ligands (CCL2 and CCL7). More interestingly, our data revealed that dual TLR2/9 recognition of HSV infection plays an important role in the functional maturation of TNF-α and iNOS-producing dendritic cells (Tip-DCs) from monocytes as well as NK cell activation in VT. TLR2/9-dependent maturation of Tip-DCs from monocytes appeared to specifically present cognate Ag, which effectively provided functional effector CD4⁺ and CD8⁺ T cells specific for HSV Ag in VT and its draining lymph nodes. TLR2/9 expressed in monocytes was likely to directly facilitate Tip-DC-like features after HSV infection. Also, dual TLR2/9 recognition of HSV infection directly activated NK cells without the aid of dendritic cells through activation of p38 MAPK pathway. Taken together, these results indicate that dual TLR2/9 recognition plays a critical role in providing resistance against mucosal infection with HSV, which may involve a direct regulation of Tip-DCs and NK cells in VT. Therefore, our data provide a more detailed understanding of TLR2/9 role in conferring antiviral immunity within relevant mucosal tissues after mucosal infection with HSV.

Regulation of Chemokine Function: The Roles of GAG-Binding and Post-Translational Nitration

The primary function of chemokines is to direct the migration of leukocytes to the site of injury during inflammation. The effects of chemokines are modulated by several means, including binding to G-protein coupled receptors (GPCRs), binding to glycosaminoglycans (GAGs), and through post-translational modifications (PTMs). GAGs, present on cell surfaces, bind chemokines released in response to injury. Chemokines bind leukocytes via their GPCRs, which directs migration and contributes to local inflammation. Studies have shown that GAGs or GAG-binding peptides can be used to interfere with chemokine binding and reduce leukocyte recruitment. Post-translational modifications of chemokines, such as nitration, which occurs due to the production of reactive species during oxidative stress, can also alter their biological activity. This review describes the regulation of chemokine function by GAG-binding ability and by post-translational nitration. These are both aspects of chemokine biology that could be targeted if the therapeutic potential of chemokines, like CXCL8, to modulate inflammation is to be realised.

Analysis of long term CD4+CD25highCD127- T-reg cells kinetics in peripheral blood of lung transplant recipients

Background

The role of CD4⁺CD25^highCD127⁻ T-reg cells in solid-organ Transplant (Tx) acceptance has been extensively studied. In previous studies on kidney and liver recipients, peripheral T-reg cell counts were associated to graft survival, while in lung Tx, there is limited evidence for similar findings. This study aims to analyze long term peripheral kinetics of T-reg-cells in a cohort of lung recipients and tests its association to several clinical variables.

Methods

From jan 2009 to dec 2014, 137 lung Tx recipients were submitted to an immunological follow up (median: 105.9 months (6.7–310.5)). Immunological follow up consisted of a complete blood peripheral immuno-phenotype, inclusive of CD4⁺CD25^highCD127⁻ T and FOXP3+ cells. We tested the association between T-reg and relevant variables by linear OR regression models for repeated measures, adjusting for time from Tx. Also, by ordered logistic models for panel data, the association between Chronic Lung Allograft Dysfuncton (CLAD) onset/progression and T-reg counts in the previous 3 months was tested.

Results

Among all variables analyzed at multivariate analysis: Bronchiolitis Obliterans Syndrome (OR −6.51, p < 0.001), Restrictive Allograft Syndrome (OR −5.19, p = 0.04) and Extracorporeal photopheresis (OR −5.65, p < 0.001) were significantly associated to T-reg cell. T-reg cell counts progressively decreased according to the severity of CLAD. Furthermore, patients with higher mean T-reg counts in a trimester had a significantly lower risk (OR 0.97, p = 0.012) of presenting CLAD or progressing in the graft dysfunction in the following trimester.

Conclusions

Our present data confirm animal observations on the possible role of T-reg in the evolution of CLAD.

Clinical utility of CD4+ function assessment (ViraCor-IBT ImmuKnow test) in lung recipients

The ImmuKnow assay measures cell-mediated immunity, quantifying ATP production from peripheral blood CD4+T-cells in solid-organ transplant patients who undergo immunosuppressive therapy. We aimed to measure functional immunity in lung transplant recipients and correlate Immuknow values with immunosuppression levels, presence of chronic lung allograft dysfunction (CLAD) and infections. We evaluated 61 lung recipients who underwent follow-up for lung transplantation between 2010 and 2014. Rejection and infection were retrospectively analyzed. The association between over-immunosuppression and a number of predictors was assessed by means of univariate and multivariate logistic regression models. 71 out of 127 samples (56%) showed an over-immunosuppression with an ImmuKnow assay mean level of 112.92ng/ml (SD±58.2), vs. 406.14ng/ml (SD±167.7) of the rest of our cohort. In the over-immunosuppression group we found 51 episodes of infection (71%) (OR 2.754, 95% CI 1.40-5.39; P-value 0.003). In the other group, only 25 samples (44%) were taken during an infectious episode. The mean absolute ATP level was significantly different between patients with or without infection (202.38±139.06ng/ml vs. 315.51±221.60ng/ml; P<0.001). RAS (Restrictive allograft syndrome) was associated to low ImmuKnow level (P<0.001). These results were confirmed by the multivariate analysis. The ImmuKnow assay levels were significantly lower in infected lung transplant recipients compared with non-infected recipients and in RAS patients.

Distinct Upstream Role of Type I IFN Signaling in Hematopoietic Stem Cell-Derived and Epithelial Resident Cells for Concerted Recruitment of Ly-6Chi Monocytes and NK Cells via CCL2-CCL3 Cascade

Type I interferon (IFN-I)-dependent orchestrated mobilization of innate cells in inflamed tissues is believed to play a critical role in controlling replication and CNS-invasion of herpes simplex virus (HSV). However, the crucial regulators and cell populations that are affected by IFN-I to establish the early environment of innate cells in HSV-infected mucosal tissues are largely unknown. Here, we found that IFN-I signaling promoted the differentiation of CCL2-producing Ly-6C^hi monocytes and IFN-γ/granzyme B-producing NK cells, whereas deficiency of IFN-I signaling induced Ly-6C^lo monocytes producing CXCL1 and CXCL2. More interestingly, recruitment of Ly-6C^hi monocytes preceded that of NK cells with the levels peaked at 24 h post-infection in IFN-I–dependent manner, which was kinetically associated with the CCL2-CCL3 cascade response. Early Ly-6C^hi monocyte recruitment was governed by CCL2 produced from hematopoietic stem cell (HSC)-derived leukocytes, whereas NK cell recruitment predominantly depended on CC chemokines produced by resident epithelial cells. Also, IFN-I signaling in HSC-derived leukocytes appeared to suppress Ly-6G^hi neutrophil recruitment to ameliorate immunopathology. Finally, tissue resident CD11b^hiF4/80^hi macrophages and CD11c^hiEpCAM⁺ dendritic cells appeared to produce initial CCL2 for migration-based self-amplification of early infiltrated Ly-6C^hi monocytes upon stimulation by IFN-I produced from infected epithelial cells. Ultimately, these results decipher a detailed IFN-I–dependent pathway that establishes orchestrated mobilization of Ly-6C^hi monocytes and NK cells through CCL2-CCL3 cascade response of HSC-derived leukocytes and epithelium-resident cells. Therefore, this cascade response of resident–to-hematopoietic–to-resident cells that drives cytokine–to-chemokine–to-cytokine production to recruit orchestrated innate cells is critical for attenuation of HSV replication in inflamed tissues.

Herpes simplex virus type 1 and 2 (HSV-1 and HSV-2) are the most common cause of genital ulceration in humans worldwide with lifelong latent infection after peripheral replication in mucosal tissues. Furthermore, acquisition of human immunodeficiency virus (HIV) is increased in HSV-infected individuals, underscoring the contribution of this virus in facilitating increased susceptibility to other microbial pathogens. Therefore, it is imperative to characterize the host defense to HSV infection and identify key components that regulate virus resistance, in order to devise therapeutic strategy. Although type I interferon (IFN-I)-dependent orchestrated mobilization of innate cells in inflamed tissues is considered a key player to control replication and CNS-invasion of HSV, the regulators and cell population that are affected by IFN-I to establish the orchestrated environment of innate cells in HSV-infected tissues are largely unknown. In the present study, we demonstrate that IFN-I signal governs the sequential recruitment of Ly-6C^hi monocytes and then NK cells into mucosal tissues, depending on CCL2-CCL3 cascade mediated by HSC-derived leukocytes and epithelial resident cells, respectively. Also, tissue resident CD11b^hiF4/80^hi macrophages and CD11c^hiEpCAM⁺ dendritic cells were involved in producing the initial CCL2 for migration-based self-amplification of rapidly infiltrated Ly-6C^hi monocytes through stimulation by IFN-I produced from infected epithelial cells. This study deciphers detailed IFN-I-dependent pathway that establishes orchestrated mobilization of Ly-6C^hi monocytes and NK cells through CCL2-CCL3 cascade.

Long-Term Off-Line Extracorporeal Photochemotherapy in Patients with Chronic Lung Allograft Rejection Not Responsive to Conventional Treatment: A 10-Year Single-Centre Analysis

BACKGROUND

Extracorporeal photochemotherapy (ECP) for chronic lung allograft dysfunction (CLAD) has been reported as beneficial in a few short-term studies.

OBJECTIVES

In this retrospective cohort study on 48 CLAD patients treated by ECP (off-line technique) for a period of >8 years (compared to 58 controls), we explored potential predictors of survival and response.

METHODS

Failures were defined as a decrease in forced expiratory volume in 1 s (FEV1) of >10% from ECP initiation.

RESULTS

ECP patients were enrolled between February 2003 and December 2013; 14 (29.2%) with restrictive allograft syndrome (RAS) and 34 with bronchiolitis obliterans syndrome. Grade 1 severity was indicated in 58.3%, grade 2 in 20.8%, and grade 3 in 20.8% of patients. The median follow-up was 65 months (cumulative 2,284.4 person-months). Twenty (41.7%) patients died, including 17 (85%) CLAD-related deaths. Among the controls, there were 42 deaths (72.4%), of which 32 (76.2%) were CLAD related, over a median of 51 months (cumulative 3,066.5 person-months; p = 0.09). Among ECP patients, the FEV1 slope flattened out after a decline in the initial months (slope -19 ml/month in months 0-6, +4 in months 36-48 and later; p = 0.001). RAS was associated with poorer survival, whereas a 'rapid decline in the previous 6 months' was not. No ECP side effects or complications were observed.

CONCLUSION

Long-term ECP for CLAD is safe and reduces FEV1 decline over time; the RAS phenotype might show a poorer response. ECP deserves to be evaluated in a randomized controlled trial.

Bronchoalveolar lavage as a tool to predict, diagnose and understand bronchiolitis obliterans syndrome

Bronchiolitis obliterans syndrome (BOS), a condition of irreversible small airway fibrosis, is the principal factor limiting long-term survival after lung transplantation. Bronchoscopy and bronchoalveolar lavage (BAL), techniques central to lung transplant clinical practice, provide a unique opportunity to interrogate the lung allograft during BOS development and identify potential disease mechanisms or biomarkers. Over the past 20 years, numerous studies have evaluated the BAL cellular composition, cytokine profiles and protein constituents in lung transplant recipients with BOS. To date, however, no summative evaluation of this literature has been reported. We developed and applied objective criteria to qualitatively rank the strength of associations between BAL parameters and BOS in order to provide a comprehensive and systematic assessment of the literature. Our analysis indicates that several BAL parameters, including neutrophil count, interleukin-8, alpha defensins and MMP-9, demonstrate highly replicable associations with BOS. Additionally, we suggest that considerable opportunity exists to increase the knowledge gained from BAL analyses in BOS through increased sample sizes, covariant adjustment and standardization of the BAL technique. Further efforts to leverage analysis of BAL constituents in BOS may offer great potential to provide additional in-depth and mechanistic insights into the pathogenesis of this complex disease.

Aqueous fraction of Sauropus androgynus might be responsible for bronchiolitis obliterans

BACKGROUND AND OBJECTIVE

Bronchiolitis obliterans (BO) has been reported to develop following ingestion of Sauropus androgynus (SA), a leafy shrub distributed in Southeast Asia. Little is known about direct effects of SA on airway resident cells or haematopoietic cells in vitro. Identification of the SA component responsible for the development of BO would be an important key to elucidate its mechanism. We sought to elucidate the direct effects of SA on airway resident cells or haematopoietic cells and identify the SA element responsible for the pathogenesis of BO.

METHODS

SA dry powder was partitioned into fractions by solvent extraction. Human and murine monocytic cells, epithelial cells and endothelial cells were cultured with SA solution or fractions eluted from SA. We also investigated the effect of SA in vivo using a murine BO syndrome (BOS) model.

RESULTS

The aqueous fraction of SA induced significant increases of inflammatory cytokine and chemokine production from monocytic lineage cells. This fraction also induced significant apoptosis of endothelial cells and enhanced intraluminal obstructive fibrosis in allogeneic trachea allograft in the murine BOS model. We found individual differences in tumour necrosis factor α (TNF-α) production from monocytes of healthy controls stimulated by this aqueous fraction of SA, whereas it induced high-level TNF-α production from monocytes of patients with SA-induced BO.

CONCLUSIONS

These results suggest that an aqueous fraction of SA may be responsible for the pathogenesis of BO.

Lung transplantation affects expression of the chemokine receptor type 4 on specific T cell subsets

Alloreactive T cells that infiltrate the graft after lung transplantation (LTx) play a role in chronic rejection. Chemokines such as thymus and activation-regulated chemokine (TARC), macrophage-derived chemokine (MDC) and monocyte chemotactic protein-1 (MCP-1) are produced locally in the lung and attract T cells via chemokine receptor 4 (CCR4). In a TARC gradient, cells expressing CCR4(++) migrate more efficiently than CCR4(+) -expressing cells. In this study, we compared the CCR4 expression of T cells in blood from 20 lung transplant recipients to healthy controls. We then examined whether CCR4 expression is associated with the occurrence of chronic rejection. The CCR4(++) expression was decreased on CD4 T cells from LTx patients (P < 0·0001) when compared to healthy controls. The analysis of CD4 T cell subsets showed that this decrease was present on central memory, effector memory and terminally differentiated T cells (P = 0·0007, P < 0·0001 and P = 0·05, respectively), while a trend was found for naive CD4 T cells (P = 0·06). Also, the expression of CCR4(+) on regulatory T cells (T(regs) ) was decreased in LTx patients when compared to healthy controls (P = 0·02). Interestingly, the CCR4(++) expression on CD4 effector memory T cells was decreased in patients developing chronic rejection sometimes more than a year before the clinical diagnosis when compared to patients who did not (P = 0·04). The analysis of CD8 T cell subsets only showed the CCR4(+) expression to be increased significantly on effector memory and terminally differentiated CD8 T cells (P = 0·02, P = 0·03, respectively) in LTx patients, but no relation was found in chronic rejection. In conclusion, the expression of CCR4 on T cell subsets was altered after LTx and appears to be related to chronic rejection.

Endothelin-1 governs proliferation and migration of bronchoalveolar lavage-derived lung mesenchymal stem cells in bronchiolitis obliterans syndrome

BACKGROUND

Bronchiolitis obliterans syndrome (BOS) has an incidence of 57% at 5 years after lung transplantation, accounts for 30% of all deaths 3 years posttransplant and because treatment options are extremely limited, it constitutes a significant health care problem. Adult mesenchymal stem cells (MSCs) play a role in lung turnover; however, their role in BOS remains unknown.

METHODS

MSCs were isolated from bronchoalveolar lavage (BAL) in 101 lung allograft recipients. BAL was screened by protein array and MSCs were analyzed by real-time polymerase chain reaction, proliferation, migration, and enzyme linked immunosorbent assays.

RESULTS

Multipotent MSCs were isolated from BAL of lung recipients independent of BOS presence. However, MSCs from BOS patients proliferated at higher rates (P<0.001) and were associated with higher α-smooth muscle actin (P = 0.03) but lower surfactant protein B (P = 0.02) compared with those from no-BOS patients. Histological analysis revealed that MSCs are abundant in lung tissue of BOS patients. MSCs from BOS patients produced higher endothelin-1 (ET-1) amounts (P<0.001) compared with those from no-BOS; and ET-1 stimulated whereas ET-1 blockade suppressed MSC proliferation, migration, and differentiation.

CONCLUSIONS

These results indicate that MSCs are associated with BOS and are governed by ET-1. Targeting MSCs by ET-1 blockade might be useful in BOS treatment.

Endothelin-1 is a useful biomarker for early detection of bronchiolitis obliterans in lung transplant recipients

OBJECTIVES

Bronchiolitis obliterans (BO) is a severe complication limiting long-term survival after lung transplantation. To date, no cure exists for BO, and the mechanisms leading to BO are not well understood. Endothelin-1 (ET-1) is a potent mitogenic and profibrotic peptide produced by pulmonary vascular endothelial cells that play a role in the pathophysiology of lung allograft dysfunction. Whether ET-1 could predict BO syndrome (BOS) development is unknown.

METHODS

Transbronchial biopsy specimens and serum and bronchoalveolar lavage were obtained from 30 lung transplantation patients with and 30 without BOS at 3 points. The serum and bronchoalveolar lavage ET-1 concentrations were measured by enzyme-linked immunosorbent assay, and the ET-1 mRNA expression in the transbronchial biopsy specimens was examined using real-time polymerase chain reaction.

RESULTS

The pretransplant ET-1 serum concentrations were greater in the patients with BOS (P = .02); and ET-1 mRNA was significantly upregulated in the lung grafts of those with versus those without BOS at 3 and 12 months after transplant (P = .01). At 3 and 12 months after transplantation, the ET-1 concentrations were significantly elevated in the serum (P < .01 and P < .0001, respectively) and bronchoalveolar lavage (P < .01 and P = .02, respectively) of patients with compared with those without BOS. On logistic regression analysis, the pretransplant and 3-month post-transplant serum ET-1 level predicted for BOS (odds ratio, 1.01; 95% confidence interval, 1.004-1.025; P < .007; odds ratio, 2.9; 95% confidence interval, 1.01-8.52; P < .001). The serum ET-1 level at 12 months was diagnostic for BOS (odds ratio, 3.9; 95% confidence interval, 1.42-10.80; P = .008).

CONCLUSIONS

Elevated serum ET-1 concentrations were predictive of BOS, and the assessment of circulating ET-1 might be beneficial in diagnosing and monitoring BO.

Serum thymus and activation regulated chemokine levels post-lung transplantation as a predictor for the bronchiolitis obliterans syndrome

The main reason for mortality after lung transplantation is the bronchiolitis obliterans syndrome (BOS), which represents chronic rejection. As soluble CD30, which is produced mainly by activated T helper 2 (Th2) cells, was shown to be related to development of BOS, we aimed to investigate the relation between development of BOS and Th2 chemoattractant thymus and activation regulated chemokine (TARC/CCL17). In 54 patients we measured serum TARC levels prior to transplantation by enzyme-linked immunosorbent assay, and in 44 of these patients sera were analysed at months 1, 2 and 3 after lung transplantation. In addition, longitudinal measurements were performed in sera from eight healthy controls and 14 patients, the latter taken over a period of 2 years post-transplantation from seven patients developing BOS plus seven clinically matched BOS-free patients. Median serum TARC levels post-transplantation of patients who developed BOS were significantly lower than those of the matched BOS-free patients (P = 0.05). A receiver operating characteristics analysis (area under the curve 0.77), together with a Kaplan-Meyer analysis, showed that serum TARC levels below 325 pg/ml in the first month post-transplantation can predict development of BOS post-transplantation (P = 0.001). In contrast, pretransplant serum TARC levels were not significantly different between patients developing BOS, BOS-free patients or healthy controls. In conclusion, pretransplantation serum TARC levels do not predict the development of BOS post-transplantation, but measurement of the serum TARC levels in the first month directly after transplantation can provide us with a tool to identify the group at risk of developing BOS.

Chemokine-directed strategies to attenuate allograft rejection

A key event during T cell-mediated rejection of allografts is the trafficking of donor antigen-primed effector T cells from the lymphoid tissue to the graft. This trafficking is mediated in part by chemokine produced in the graftengaging receptors on the T cells and other graftinfiltrating leukocytes. The presence of specific sets of chemokines and chemokine receptors is detectable in rejecting allografts. In animal models, allograft rejection is delayed when chemokine-chemokine receptor function is absent or antagonized but cellular infiltration and graft survival eventually occur, suggesting that T cells and other leukocytes use several trafficking mechanisms during rejection. The use of chemokines as footprints of rejection may be of considerable value as noninvasive biomarkers in transplantation.