Biomarkers of pulmonary rejection

Efficacy and safety of total lymphoid irradiation in different chronic lung allograft dysfunction phenotypes

Total lymphoid irradiation (TLI) is an alternative treatment for chronic lung allograft dysfunction (CLAD). However, data regarding its efficacy and tolerance are scarce. This study included patients with CLAD treated with TLI at our center between 2011 and 2018. Clinical characteristics before and after TLI and related complications were analyzed. Forty patients with CLAD (twenty-nine bronchiolitis obliterans syndrome [BOS], nine restrictive allograft syndrome [RAS], and two mixed) were included. Significant attenuation of the forced expiratory volume in 1-sec (FEV₁ ) decline slope was observed in all phenotypes, in both the BOS and RAS. The median FEV₁ 12, 6, and 3 months pre-TLI were as follows: 1980 (IQR 1720-2560), 1665 (IQR 1300-2340) and 1300 (IQR 1040-1740) ml (p < .001), while the median FEV₁ at 3, 6, and 12 months post-TLI was 1110 (IQR 810-1440), 1130 (IQR 860-1470), and 1115 (IQR 865-1490) ml (p = .769). No dropouts due to radiation toxicity were observed. The mean survival according to the Karnofsky Performance Status Scale (KPS) >70 or ≤70 at baseline was 1837 (IQR 259-2522) versus 298 (IQR 128-554) days (p < .0001), respectively. In conclusion, TLI may stop FEV₁ decline in both BOS and RAS. Moreover, a good KPS score may be an important prognostic factor.

Corticotropin releasing hormone as an identifier of bronchiolitis obliterans syndrome

Lung transplantion (LTx) recipients have low long-term survival and a high incidence of bronchiolitis obliterans syndrome (BOS), an inflammation of the small airways in chronic rejection of a lung allograft. There is great clinical need for a minimally invasive biomarker of BOS. Here, 644 different proteins were analyzed to detect biomarkers that distinguish BOS grade 0 from grades 1–3. The plasma of 46 double lung transplant patients was analyzed for proteins using a high-component, multiplex immunoassay that enables analysis of protein biomarkers. Proximity Extension Assay (PEA) consists of antibody probe pairs which bind to targets. The resulting polymerase chain reaction (PCR) reporter sequence can be quantified by real-time PCR. Samples were collected at baseline and 1-year post transplantation. Enzyme-linked immunosorbent assay (ELISA) was used to validate the findings of the PEA analysis across both time points and microarray datasets from other lung transplantation centers demonstrated the same findings. Significant decreases in the plasma protein levels of CRH, FERC2, IL-20RA, TNFB, and IGSF3 and an increase in MMP-9 and CTSL1 were seen in patients who developed BOS compared to those who did not. In this study, CRH is presented as a novel potential biomarker in the progression of disease because of its decreased levels in patients across all BOS grades. Additionally, biomarkers involving the remodeling of the extracellular matrix (ECM), such as MMP-9 and CTSL1, were increased in BOS patients.

COMP: A Potential Early Biomarker of RAS After Lung Transplantation

Chronic rejection, defined as chronic lung allograft dysfunction (CLAD), is the major factor limiting long-term survival after lung transplantation (LTx). A specific subgroup of CLAD is restrictive allograft syndrome (RAS). CLAD’s pathogenesis is largely unknown, but previous findings suggest that it is associated with increased fibrosis in the transplanted lung. Cartilage oligomeric matrix protein (COMP) has been associated with multiple fibrotic conditions. The current study aimed to explore the relation between COMP serum levels and development of CLAD, and RAS in particular, in a retrospective cohort of LTx patients.

Bronchoalveolar bile acid and inflammatory markers to identify high-risk lung transplant recipients with reflux and microaspiration

BACKGROUND

Gastroesophageal reflux disease (GERD) is a risk factor for chronic lung allograft dysfunction. Bile acids-putative markers of gastric microaspiration-and inflammatory proteins in the bronchoalveolar lavage (BAL) have been associated with chronic lung allograft dysfunction, but their relationship with GERD remains unclear. Although GERD is thought to drive chronic microaspiration, the selection of patients for anti-reflux surgery lacks precision. This multicenter study aimed to test the association of BAL bile acids with GERD, lung inflammation, allograft function, and anti-reflux surgery.

METHODS

We analyzed BAL obtained during the first post-transplant year from a retrospective cohort of patients with and without GERD, as well as BAL obtained before and after Nissen fundoplication anti-reflux surgery from a separate cohort. Levels of taurocholic acid (TCA), glycocholic acid, and cholic acid were measured using mass spectrometry. Protein markers of inflammation and injury were measured using multiplex assay and enzyme-linked immunosorbent assay.

RESULTS

At 3 months after transplantation, TCA, IL-1β, IL-12p70, and CCL5 were higher in the BAL of patients with GERD than in that of no-GERD controls. Elevated TCA and glycocholic acid were associated with concurrent acute lung allograft dysfunction and inflammatory proteins. The BAL obtained after anti-reflux surgery contained reduced TCA and inflammatory proteins compared with that obtained before anti-reflux surgery.

CONCLUSIONS

Targeted monitoring of TCA and selected inflammatory proteins may be useful in lung transplant recipients with suspected reflux and microaspiration to support diagnosis and guide therapy. Patients with elevated biomarker levels may benefit most from anti-reflux surgery to reduce microaspiration and allograft inflammation.

Differential gene analysis during the development of obliterative bronchiolitis in a murine orthotopic lung transplantation model: A comprehensive transcriptome-based analysis

BACKGROUND

Obliterative bronchiolitis (OB) is a known issue during minor histocompatibility antigen (mHA) disparity during lung transplantation. This study evaluated gene expression in a murine orthotropic lung transplantation model using microarray analysis.

METHODS

Left lungs from C57BL/10(H-2b) donor mice were transplanted into mHA-mismatched C57BL/6(H-2b) recipient mice. Three groups (OB, non-OB, and sham controls) were confirmed pathologically and analyzed. Gene expression changes in the lung grafts were determined by microarray and immunohistochemical staining, and genes were verified by quantitative PCR in the lungs and mediastinal lymph nodes (LNs).

RESULTS

A total of 1343 genes were upregulated in the OB lungs compared to the sham group. Significant upregulation was observed for genes related to innate, e.g. Tlr2 and CCL3 and adaptive immunity, e.g. H2-ab1 and Il-21. Positive labeling for MHC class II antigen was observed in the bronchial epithelium of OB accompanied with B cells. We found increased Tlr2, Ccl3, H2-ab1, Il-21, Ighg3, Ifng, and Pdcd1 mRNA expression in the OB lung, and increased Il-21, Ighg3, and Pdcd1 expression in the OB LNs.

CONCLUSIONS

Adaptive and innate immune reactions were involved in OB after lung transplantation, and genetic examination of related genes could be used for detection of OB.

Lung transplant outcomes are influenced by severity of neutropenia and granulocyte colony-stimulating factor treatment

Although neutropenia is a common complication after lung transplant, its relationship with recipient outcomes remains understudied. We evaluated a retrospective cohort of 228 adult lung transplant recipients between 2008 and 2013 to assess the association of neutropenia and granulocyte colony-stimulating factor (GCSF) treatment with outcomes. Neutropenia was categorized as mild (absolute neutrophil count 1000-1499), moderate (500-999), or severe (<500) and as a time-varying continuous variable. Associations with survival, acute rejection, and chronic lung allograft dysfunction (CLAD) were assessed with the use of Cox proportional hazards regression. GCSF therapy impact on survival, CLAD, and acute rejection development was analyzed by propensity score matching. Of 228 patients, 101 (42.1%) developed neutropenia. Recipients with severe neutropenia had higher mortality rates than those of recipients with no (adjusted hazard ratio [aHR] 2.97, 95% confidence interval [CI] 1.05-8.41, P = .040), mild (aHR 14.508, 95% CI 1.58-13.34, P = .018), or moderate (aHR 3.27, 95% CI 0.89-12.01, P = .074) neutropenia. Surprisingly, GCSF treatment was associated with a higher risk for CLAD in mildly neutropenic patients (aHR 3.49, 95% CI 0.93-13.04, P = .063), although it did decrease death risk in severely neutropenic patients (aHR 0.24, 95% CI 0.07-0.88, P = .031). Taken together, our data point to an important relationship between neutropenia severity and GCSF treatment in lung transplant outcomes.

Precision medicine: integration of genetics and functional genomics in prediction of bronchiolitis obliterans after lung transplantation

PURPOSE OF REVIEW

Lung transplantation (LTx) can be a life saving treatment in end-stage pulmonary diseases, but survival after transplantation is still limited. Posttransplant development of chronic lung allograft dysfunction with bronchiolits obliterans syndrome (BOS) as the major subphenotype, is the main cause of morbidity and mortality. Early identification of high-risk patients for BOS is a large unmet clinical need. In this review, we discuss gene polymorphisms and gene expression related to the development of BOS.

RECENT FINDINGS

Candidate gene studies showed that donor and recipient gene polymorphisms affect transplant outcome and BOS-free survival after LTx. Both selective and nonselective gene expression studies revealed differentially expressed fibrosis and apoptosis-related genes in BOS compared with non-BOS patients. Significantly, recent microarray expression analysis of blood and broncho-alveolar lavage suggest a role for B-cell and T-cell responses prior to the development of BOS. Furthermore, 6 months prior to the development of BOS differentially expressed genes were identified in peripheral blood cells.

SUMMARY

Genetic polymorphisms and gene expression changes are associated with the development of BOS. Future genome wide studies are needed to identify easily accessible biomarkers for prediction of BOS toward precision medicine.

Transplant arteriosclerosis in humanized mice reflects chronic lung allograft dysfunction and is controlled by regulatory T cells

OBJECTIVE

Chronic lung allograft dysfunction (CLAD) is a severe complication of lung transplantation limiting long-term survival. We studied correlations between CLAD after clinical lung transplantation and leukocyte-mediated development of transplant arteriosclerosis (TA) in a humanized mouse model. The pericardiophrenic artery was procured from surplus tissue of donor lungs (n = 22) transplanted in our clinical program and was implanted into the abdominal aorta of immune-deficient mice.

METHODS

Allogeneic human peripheral blood mononuclear cells (PBMCs) had been procured 1 day after lung transplantation from the respective recipients with or without enriching for CD4⁺CD25^high T cells were used. TA was assessed in mice 28 days later by histology. The respective clinical lung recipients were later divided into 2 groups. Eight patients (36.3%) had developed CLAD 23 ± 5 months after lung transplantation, whereas the remaining 14 (63.6%) did not develop CLAD within 25 ± 5 months.

RESULTS

In the PBMC CLAD+ group of mouse experiments, TA was significantly more severe than in the PBMC CLAD- group (39.9% ± 13% vs 14.9% ± 4% intimal thickening; P = .0081). Then, intimal thickening was significantly inhibited in the PBMC+ regulatory T cells CLAD+ group compared with the PBMC CLAD+ group (0.4% ± 4% vs 39.9% ± 13%; P = .003). In the experiments using PBMCs from lung recipients without CLAD, enriching regulatory T cells also suppressed the development of TA (0.9% ± 3% PBMC CLAD- vs 14.9% ± 4% PBMC+ regulatory T cells CLAD-; P = .001).

CONCLUSIONS

Lung transplant recipients who later develop CLAD have peripheral leukocytes already at the time of transplant that transfer proinflammatory properties leading to TA in a humanized mouse model. TA remains sensitive to inhibition by autologous regulatory T cells, suggesting a cell therapy-based approach for the prevention of CLAD after lung transplantation.

Esophageal motor disorders are frequent during pre and post lung transplantation. Can they influence lung rejection?

BACKGROUND

lung transplantation (LTx) is a viable option for most patients with end-stage lung diseases. Esophageal motor disorders (EMD) are frequent in candidates for LTx, but there is very little data about changes in esophageal motility post-LTx.

AIM

the aim of our study was to assess esophageal motor disorders by high resolution manometry (HRM) both pre-LTx and six months post-LTx in patients with and without organ rejection.

STUDY

HRM (Manoscan®) was performed in 57 patients both pre-LTx and six months post-LTx. HRM plots were analyzed according to the Chicago classification 3.0.

RESULTS

EMD were found in 33.3% and in 49.1% of patients pre-LTx and post-LTx, respectively, and abnormal peristalsis was more frequently found post-LTx (p = 0.018). Hypercontractile esophagus was frequently found post-LTx (1.8% and 19.3% pre-LTx and post-LTx, respectively). Esophagogastric junction (EGJ) morphology changed significantly pre-LTx and post-LTx; type I (normal) was more frequent post-LTx (63-2% and 82.5% respectively, p = 0.007). EMD were more frequent post-LTx in both the non-rejection and rejection group, although particularly in the rejection group (43.2% and 69.2% respectively, p = 0.09). EMD such as distal spasm, hypercontractile esophagus and EGJ outflow obstruction were also observed more frequently post-LTx in the rejection group.

CONCLUSION

significant changes in esophageal motility were observed pre-LTx and particularly post-LTx; hypercontractile esophagus was a frequent EMD found post-LTx. EMD were more frequent in the group of patients that experienced organ rejection compared to the non-rejection group. EMD leading to an impaired esophageal clearance should be considered as an additional factor that contributes to LTx failure.

Heparin-binding protein, lysozyme, and inflammatory cytokines in bronchoalveolar lavage fluid as diagnostic tools for pulmonary infection in lung transplanted patients

Pulmonary infection is a common complication after lung transplantation, and early detection is crucial for outcome. However, the condition can be clinically difficult to diagnose and to distinguish from rejection. The aim of this prospective study was to evaluate heparin-binding protein (HBP), lysozyme, and the cytokines interleukin (IL)-1β, IL-6, IL-8, IL-10 and tumor necrosis factor (TNF) in bronchoalveolar lavage fluid (BALF) as potential biomarkers for pulmonary infection in lung-transplanted patients. One hundred thirteen BALF samples from 29 lung transplant recipients were collected at routine scheduled bronchoscopies at 3 and 6 months, or on clinical indication. Samples were classified into no, possible, probable, or definite infection at the time of sampling. Rejection was defined by biopsy results. HBP, lysozyme, and cytokines were analyzed in BALF and correlated to likelihood of infection and rejection. All biomarkers were significantly increased in BALF during infection, whereas patients with rejection presented low levels that were comparable to noninfection samples. HBP, IL-1β, and IL-8 were the best diagnostic markers of infection with area under the receiver-operating characteristic curve values of 0.88, 0.91, and 0.90, respectively. In conclusion, HBP, IL-1β, and IL-8 could be useful diagnostic markers of pulmonary infection in lung-transplanted patients.

Association between a Single Donor TARC/CCL17 Promotor Polymorphism and Obstructive Chronic Lung Allograft Dysfunction after Lung Transplantation

Lung transplantation (LTx) outcome is hampered by development of chronic rejection, often manifested as the bronchiolitis obliterans syndrome (BOS). Low serum levels of thymus and activation-regulated chemokine (TARC/CCL17), a chemoattractant, measured during the first month post-LTx are predictive for BOS development. Since TARC/CCL17 promotor polymorphisms correlate with serum TARC/CCL17 levels, we investigated seven single-nucleotide polymorphisms (SNPs) within this region and their potential association with LTx outcome. We analyzed donor and patient SNP configurations and haplotypes and observed a trend between a donor SNP (rs223899) configuration and patient TARC/CCL17 serum levels post-LTx (p = 0.066). Interestingly, this SNP configuration in patients did not show any correlation with pre-LTx TARC/CCL17 serum levels (p = 0.776). Survival analysis showed that receiving a graft from a donor heterozygous for rs223899 has a disadvantageous impact on transplantation outcome. When stratified per donor SNP genotype, patients receiving a transplant from a heterozygous donor showed a lower BOS-free survival (p = 0.023) and survival rate (p = 0.0079). Since rs223899 is located within a NFκB binding site, heterozygosity at this position could result in a reduced TARC/CCL17 expression. Our data indicate that a single TARC/CCL17 promotor SNP in the donor correlates with lower serum TARC/CCL17 levels measured 1 month after LTx and affects clinical outcome after LTx.

Incidence of acute cellular rejection following granulocyte colony-stimulating factor administration in lung transplantation: A retrospective case-cohort analysis

Granulocyte colony-stimulating factor (GCSF) is an option to treat leukopenia in lung transplant recipients. Conflicting evidence exists regarding its effects on acute cellular rejection (ACR). A retrospective, case-cohort study was conducted to assess whether the use of GCSF in lung transplant recipients is associated with an increased incidence of ACR. Patients had to have received at least one dose of GCSF but were excluded if they received GCSF within 30 days prior to transplant or received a lymphocyte-depleting agent within 14 days of GCSF administration. Thirty-five patients who received GCSF within 3 months of transplant met inclusion criteria and 105 patients were identified as controls based on a 1:3 allocation scheme. Incidence of ACR was 57.1% in the GCSF group versus 50.5% in the control group (relative risk (RR)=1.13; 95% CI, 0.80 to 1.59; P=.48). At 3 months post-transplant, 74.3% of the GCSF group had a dose reduction or discontinuation of their antiproliferative agent versus 17.1% of the control group (RR=4.33; 95% CI, 2.73 to 6.89; P<.0001). Rejection severity and incidence of infections was similar among groups. These findings show that GCSF administration within 3 months following lung transplantation was not associated with a higher incidence or severity of ACR.

Rapid detection of donor cell free DNA in lung transplant recipients with rejections using donor-recipient HLA mismatch

Fiberoptic bronchoscopy and transbronchial lung biopsy are currently the gold standard for detection of acute rejection following human lung transplantation (LTx). However, these surveillance procedures are expensive and invasive. Up to now, there are few new methods that have demonstrated clinical utility for detecting early stages of rejection following human lung transplantation. We optimized and technically validated a novel method to quantify donor-derived circulating cell free DNA (DcfDNA) that can be used as an early biomarker for lung allograft rejection. The method involves the initial development of a panel of probes in which each probe will specifically target a unique sequence of a human leukocyte antigen (HLA) allele. After transplantation, donor/recipient specific probes are chosen based on the mismatched HLA loci, followed by droplet digital PCR (ddPCR) used as a quantitative assay to accurately track the trace amount of DcfDNA in an ample excess of recipient DNA background. The average false positive rate noted was about 1 per 800,000 molecules. Serially 2-fold diluted cfDNA, representing donor fractions of cfDNA, were spiked into a constant level of cfDNA representing the recipient cfDNA. The fraction of spiked cfDNA was measured and quantitative linearity was observed across seven serially diluted cfDNA samples. We were able to measure the minor portion of cfDNA as low as 0.2% of total cfDNA. We subsequently applied the method to a pilot set of 18 LTx recipients grouped into biopsy-proven acute rejection, bronchiolitis obliterans syndrome (BOS) or stable groups. Serial plasma samples were used to identify the percentage of DcfDNA over total cfDNA. The level of DcfDNA was significantly elevated in patients diagnosed with acute rejection (10.30±2.80, n=18), compared to that from stable (1.71±0.50, n=24) or from BOS patients (2.52±0.62, n=20). In conclusion, we present results validating the application of digital PCR to quantify DcfDNA assay in primary clinical specimens, which demonstrate that DcfDNA can be used as an early non-invasive biomarker for acute lung allograft rejection.

Diagnostic value of plasma and bronchoalveolar lavage samples in acute lung allograft rejection: differential cytology

Diagnosis of acute lung allograft rejection is currently based on transbronchial lung biopsies. Additional methods to detect acute allograft dysfunction derived from plasma and bronchoalveolar lavage samples might facilitate diagnosis and ultimately improve allograft survival. This review article gives an overview of the cell profiles of bronchoalveolar lavage and plasma samples during acute lung allograft rejection. The value of these cells and changes within the pattern of differential cytology to support the diagnosis of acute lung allograft rejection is discussed. Current findings on the topic are highlighted and trends for future research are identified.