Proteomic identification of human neutrophil alpha-defensins in chronic lung allograft rejection

Chronic allograft rejection remains a leading cause of morbidity and mortality in lung transplant recipients. Currently, diagnosis is based on lung biopsies or the presence of bronchiolitis obliterans syndrome (BOS). To identify a biomarker of rejection we performed a proteome survey of archived bronchoalveolar lavage fluid (BALF) acquired from lung transplant recipients between 1993 and 1996 using mass spectrometry (MS). A total of 126 BALF samples from 57 individuals were tested. Initial MS assessment revealed numerous differences in a majority of individuals who experienced BOS, but three unusually intense peaks at m/z = 3373, 3444, and 3488. These were identified as human neutrophil peptides 1-3 (HNP). Quantification by enzyme-linked immunoabsorbent assay showed an elevated HNP level (>0.3 ng/microg protein) in 89% of patients who developed BOS2-3 within 15 months, reaching as high as 6% of the total BALF protein. In control patients, 35% demonstrated a slightly elevated HNP level that declined in all who had subsequent BALF available for testing. HNP levels did not correlate with episodes of acute rejection, cytomegalovirus or fungal infection. In conclusion, elevated HNP levels are associated with the onset of BOS and can predate the clinical onset of disease up to 15 months.     

Identification and Validation of Proteinase 3 and Latent Matrix-Metalloproteinase 9 as Potential Biomarkers for Chronic Lung Transplant Rejection

Introduction

This study examined potential biomarkers for the diagnosis and early detection of chronic allograft rejection after lung transplantation.

Methods

Protein ratios in pooled samples of bronchoalveolar lavage fluid (BALF) from lung transplant recipients at different stages of pre- and postchronic rejection were determined by iTRAQ labeling and mass spectrometry. The potential biomarkers were validated using enzyme-linked immunosorbent assay (ELISA) assay.

Results

Two hundred sixty-five proteins were identified, about two thirds of which showed more than a twofold difference between a pooled control sample (individuals who did not develop chronic rejection in 100 months) and a pooled sample from those with chronic rejection. Proteinase 3 (PR-3) and matrix metalloproteinase 9 (MMP-9) were validated by ELISA assay of 124 individual samples. PR-3 and the latent form of MMP-9 (proMMP9) both demonstrated a specificity of 92% with sensitivities of 76% and 82%, respectively, for disease diagnosis; both were also predictors of developing chronic rejection up to 15 months before diagnosis. While immunoglobulin M (IgM) was upregulated in the pooled samples, individual sample analysis revealed that this arose from outlier values.

Conclusions

iTRAQ can be used to detect a large number of proteins in pooled samples for the discovery of potential biomarkers, but the findings must be validated with technology capable of distinguishing broadly based changes from outcomes as a result of a few extreme cases. The proteins identified in this study expanded the panel of potential biomarkers for the diagnosis and prediction of chronic rejection and provided additional insight into the mechanism of the disease.     

Association of Soluble HLA-G with Acute Rejection Episodes and Early Development of Bronchiolitis Obliterans in Lung Transplantation

Lung transplantation has evolved into a life-saving therapy for select patients with end-stage lung diseases. However, long-term survival remains limited because of bronchiolitis obliterans syndrome (BOS). Soluble HLA-G, a mediator of adaptive immunity that modulates regulatory T cells and certain classes of effector T cells, may be a useful marker of survival free of BOS. We conducted a retrospective, single-center, pilot review of 38 lung transplant recipients who underwent collection of serum and bronchoalveolar lavage fluid 3, 6 and 12 months after transplantation, and compared soluble HLA-G concentrations in each to the presence of type A rejection and lymphocytic bronchiolitis in the first 12 months and to the presence of BOS at 24 months after transplantation. Lung soluble HLA-G concentrations were directly related to the presence of type A rejection but not to lymphocytic bronchiolitis. Our data demonstrate that soluble HLA-G concentrations in bronchoalveolar lavage but not in serum correlates with the number of acute rejection episodes in the first 12 months after lung transplantation, and thus may be a reactive marker of rejection.     

Identification and validation of a potential lung cancer serum biomarker detected by matrix-assisted laser desorption/ionization-time of flight spectra analysis

Many abnormalities detected in the thorax by routine conventional imaging studies are benign, yet all require further evaluation because of the concern for cancer. To address this deficiency and develop a serum biomarker for lung cancer, we designed a matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF MS) based platform to display the proteins present in the serum of patients with or without lung cancer, and then challenged the scientific community to analyze these data with the aim of determining specific ion signal differences among the resulting spectra. The most statistically significant ion peak identified by the various analysis algorithms that differentiated the serum of patients with lung cancer from the serum of individuals without lung cancer was found at m/z 11,702. We identified the protein responsible for this ion peak as serum amyloid A (SAA; M(r) = 11,682.7) by partial purification followed by in-gel digestion and peptide mapping. By enzyme-linked immunosorbent assay, we showed SAA to be present at 286 ng/mL in the serum of cancer patients vs. 34.1 ng/mL in the serum of individuals without cancer. These data suggest that the combination of MALDI-TOF MS and computer analysis can be a powerful tool in the search for serum biomarkers of lung cancer and other diseases.     

Platelet factor-4 is an indicator of blood count recovery in acute myeloid leukemia patients in complete remission

To investigate whether serum biomarkers can be used to indicate the responsiveness of acute myeloid leukemia to remission induction chemotherapy, we performed MALDI-TOF protein profile analysis of patient sera. The resulting spectra revealed a protein (or peptide) peak at m/z 7764 that varied in intensity; its intensity was much higher in samples from patients in complete remission than in those from patients with resistant disease or in samples taken prior to treatment (at the time of diagnosis). Using fractionation, trypsin digestion, MS/MS, and protein molecular weight analyses, we identified the m/z 7764 protein as platelet factor-4 (PF4). This identification was confirmed by a magnetic bead-based MALDI immunoassay. Statistical comparison of PF4 levels and platelet counts in patient sera revealed a significant positive correlation between the two variables. This study demonstrates that PF4 protein levels are a good indicator for the recovery of blood count in the complete remission of acute myeloid leukemia. The linear positive correlation curve indicates that blood count recovery of platelets to >100,000/mm(3) is equivalent to a serum PF4 recovery level of >2.492 microg/ml.     

Peptidome profiling of induced sputum by mesoporous silica beads and MALDI-TOF MS for non-invasive biomarker discovery of chronic inflammatory lung diseases

Induced sputum is recognized as being of increasing importance for the diagnosis and monitoring of chronic inflammatory lung diseases. The main purpose of this study is to provide a valid approach to better fractionate and characterize the still under-estimated low-molecular weight proteome of induced sputum by using mesoporous silica beads (MSBs) SPE coupled to MALDI-TOF MS. Sputum peptides were captured from both derivatized and non-derivatized MSBs and then profiled by MALDI-TOF MS. Depending on the chemical groups present on the mesoporous surface, complex peptide mixtures were extracted from induced sputum and converted into reproducible MALDI profiles. The number of peaks detected as a function of S/N was evaluated for each mesoporous surface. More than 400 peaks with an S/N>5 were obtained in comparison to 200 peaks detected without MSBs. Additionally, as a proof-of-principle, we investigated the ability of this platform to discriminate between the "sputome" of patients with asthma and chronic obstructive pulmonary disease, and between these groups and those of healthy control subjects. Six m/z peaks emerged as potential diagnostic peptidic patterns able to differentiate these inflammatory airway diseases in the sputome range. Human α-defensins (human neutrophil peptide (HNP)1, HNP2, HNP3) and three C-terminal amidated peptides, one of which is phosphorylated on serine, were identified by MALDI-TOF/TOF MS. These findings may contribute to defining a high-throughput screening MS-based platform for monitoring key peptidic-biomarkers for inflammatory and chronic respiratory diseases in induced sputum samples.     

IL-13 is pivotal in the fibro-obliterative process of bronchiolitis obliterans syndrome

Acute allograft rejection is considered to be a predominately type 1 immune mediated response to the donor alloantigen. However, the type 2 immune mediated response has been implicated in multiple fibroproliferative diseases. Based on the fibro-obliterative lesion found during bronchiolitis obliterans syndrome (BOS), we hypothesized that the type 2 immune mediated response is involved in chronic lung allograft rejection. Specifically, whereas acute rejection is, in part, a type 1 immune response, chronic rejection is, in part, a type 2 immune response. We found the type 2 cytokine, IL-13, to be elevated and biologically active in human bronchoalveolar lavage fluid during BOS. Translational studies using a murine model of BOS demonstrated increased expression of IL-13 and its receptors that paralleled fibro-obliteration. In addition, in vivo neutralization of IL-13 reduced airway allograft matrix deposition and murine BOS, by a mechanism that was independent of IL-4. Furthermore, using IL-13Ralpha2(-/-) mice, we found increased fibro-obliteration. Moreover, anti-IL-13 therapy in combination with cyclosporin A had profound effects on reducing murine BOS. This supports the notion that IL-13 biological axis plays an important role during the pathogenesis of BOS independent of the IL-4 biological axis.     

Utilization of Whole-Cell MALDI-TOF Mass Spectrometry to Differentiate Burkholderia pseudomallei Wild-Type and Constructed Mutants

Whole-cell matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (whole-cell MALDI-TOF MS) has been widely adopted as a useful technology in the identification and typing of microorganisms. This study employed the whole-cell MALDI-TOF MS to identify and differentiate wild-type and mutants containing constructed single gene mutations of Burkholderia pseudomallei, a pathogenic bacterium causing melioidosis disease in both humans and animals. Candidate biomarkers for the B. pseudomallei mutants, including rpoS, ppk, and bpsI isolates, were determined. Taxon-specific and clinical isolate-specific biomarkers of B. pseudomallei were consistently found and conserved across all average mass spectra. Cluster analysis of MALDI spectra of all isolates exhibited separate distribution. A total of twelve potential mass peaks discriminating between wild-type and mutant isolates were identified using ClinProTools analysis. Two peaks (m/z 2721 and 2748 Da) were specific for the rpoS isolate, three (m/z 3150, 3378, and 7994 Da) for ppk, and seven (m/z 3420, 3520, 3587, 3688, 4623, 4708, and 5450 Da) for bpsI. Our findings demonstrated that the rapid, accurate, and reproducible mass profiling technology could have new implications in laboratory-based rapid differentiation of extensive libraries of genetically altered bacteria.     

Critical role for CXCR3 chemokine biology in the pathogenesis of bronchiolitis obliterans syndrome

Bronchiolitis obliterans syndrome (BOS) is the major limitation to survival post-lung transplantation and is characterized by a persistent peribronchiolar inflammation that eventually gives way to airway fibrosis/obliteration. Acute rejection is the main risk factor for the development of BOS and is characterized by a perivascular/bronchiolar leukocyte infiltration. The specific mechanism(s) by which these leukocytes are recruited have not been elucidated. The CXC chemokines (monokine induced by IFN-gamma (MIG)/CXC chemokine ligand (CXCL)9, IP-10/CXCL10, and IFN-inducible T cell alpha chemoattractant (ITAC)/CXCL11) act through their shared receptor, CXCR3. Because they are potent leukocyte chemoattractants and are involved in other inflammation/fibroproliferative diseases, we hypothesized that the expression of these chemokines during an allogeneic response promotes the persistent recruitment of mononuclear cells, leading to chronic lung rejection. We found that elevated levels of MIG/CXCL9, IFN-inducible protein 10 (IP-10)/CXCL10, and ITAC/CXCL11 in human bronchoalveolar lavage fluid were associated with the continuum from acute to chronic rejection. Translational studies in a murine model demonstrated increased expression of MIG/CXCL9, IP-10/CXCL10, and ITAC/CXCL11 paralleling the recruitment of CXCR3-expressing mononuclear cells. In vivo neutralization of CXCR3 or its ligands MIG/CXCL9 and IP-10/CXCL10 decreased intragraft recruitment of CXCR3-expressing mononuclear cells and attenuated BOS. This supports the notion that ligand/CXCR3 biology plays an important role in the recruitment of mononuclear cells, a pivotal event in the pathogenesis of BOS.     

Increased Numbers of Circulating CD8 Effector Memory T Cells before Transplantation Enhance the Risk of Acute Rejection in Lung Transplant Recipients

The effector and regulatory T cell subpopulations involved in the development of acute rejection episodes in lung transplantation remain to be elucidated. Twenty-seven lung transplant candidates were prospectively monitored before transplantation and within the first year post-transplantation. Regulatory, Th17, memory and naïve T cells were measured in peripheral blood of lung transplant recipients by flow cytometry. No association of acute rejection with number of peripheral regulatory T cells and Th17 cells was found. However, effector memory subsets in acute rejection patients were increased during the first two months post-transplant. Interestingly, patients waiting for lung transplant with levels of CD8⁺ effector memory T cells over 185 cells/mm³ had a significant increased risk of rejection [OR: 5.62 (95% CI: 1.08-29.37), p=0.04]. In multivariate analysis adjusted for age and gender the odds ratio for rejection was: OR: 5.89 (95% CI: 1.08-32.24), p=0.04. These data suggest a correlation between acute rejection and effector memory T cells in lung transplant recipients. The measurement of peripheral blood CD8⁺ effector memory T cells prior to lung transplant may define patients at high risk of acute lung rejection.     

Protection against Bronchiolitis Obliterans Syndrome Is Associated with Allograft CCR7+CD45RA? T Regulatory Cells

Bronchiolitis obliterans syndrome (BOS) is the major obstacle to long-term survival after lung transplantation, yet markers for early detection and intervention are currently lacking. Given the role of regulatory T cells (Treg) in modulation of immunity, we hypothesized that frequencies of Treg in bronchoalveolar lavage fluid (BALF) after lung transplantation would predict subsequent development of BOS. Seventy BALF specimens obtained from 47 lung transplant recipients were analyzed for Treg lymphocyte subsets by flow cytometry, in parallel with ELISA measurements of chemokines. Allograft biopsy tissue was stained for chemokines of interest. Treg were essentially all CD45RA⁻, and total Treg frequency did not correlate to BOS outcome. The majority of Treg were CCR4⁺ and CD103⁻ and neither of these subsets correlated to risk for BOS. In contrast, higher percentages of CCR7⁺ Treg correlated to reduced risk of BOS. Additionally, the CCR7 ligand CCL21 correlated with CCR7⁺ Treg frequency and inversely with BOS. Higher frequencies of CCR7⁺ CD3⁺CD4⁺CD25^hiFoxp3⁺CD45RA⁻ lymphocytes in lung allografts is associated with protection against subsequent development of BOS, suggesting that this subset of putative Treg may down-modulate alloimmunity. CCL21 may be pivotal for the recruitment of this distinct subset to the lung allograft and thereby decrease the risk for chronic rejection.     

Spectroscopic detection and identification of infected cells with herpes viruses

Matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) and Fourier transform infrared (FTIR) microspectroscopy were previously applied for the identification of various biological samples. In the present study, normal cells in culture and cells infected with herpes simplex virus type 2 (HSV-2) or varicella-zoster virus (VZV) were analyzed by MALDI-TOF and FTIR microscopy. Specific spectral biomarkers for rapid and reliable monitoring and identification of infected cells and probably for the discrimination between these viruses were searched. The results show consistent spectral peaks in all examined normal uninfected human fibroblast cells both in MALDI-T0F and FTIR microscopy. In HSV-2- or VZV-infected cells, two unique peaks for each appeared at m/z 5397 and 5813 or at m/z 3501 and 4951, respectively, in MALDI-TOF spectra. In addition, several peaks that appeared in control uninfected cells at the region m/z 13,000-20,000 disappeared completely in all examined infected samples. When these infected cells were examined by FTIR microscopy, a band at 859 cm(-1) in control uninfected cells was significantly shifted to 854 cm(-1) in both HSV2- and VZV-infected cells. In addition, phosphate levels were considerably increased in all infected cells compared to normal uninfected cells. These parameters could be used as a basis for developing a spectral method for the detection and identification of cells infected with herpes viruses.     

A pilot study of salivary N-glycome in HBV-induced chronic hepatitis,cirrhosis, and hepatocellular carcinoma

Hepatitis B is a potentially life-threatening liver infection caused by the hepatitis B virus (HBV), which can lead to chronic liver disease and put people at high risk of death from cirrhosis of the liver and liver cancer. However, little is known about the correlation of salivary N-linked glycans related to HBV-infected liver diseases. Here we investigated N-linked glycome in saliva from 200 subjects (50 healthy volunteers (HV), 40 HBV-infected patients (HB), 50 cirrhosis patients (HC), and 60 hepatocellular carcinoma patients (HCC) using MALDI-TOF/TOF-MS. Representative MS spectra of N-glycans with signal-to-noise ratios >6 were annotated using the GlycoWorkbench program. A total of 40, 47, 29, and 33 N-glycan peaks were identified and annotated from HV, HB, HC, and HCC groups, respectively. There were 15 N-glycan peaks (e.g., m/z 1647.587, 1688.613 and 2101.755) were present in all groups. Three N-glycan peaks (m/z 2596.925, 2756.962, and 2921.031) were unique in HV group, 2 N-glycan peaks (m/z 1898.676 and 1971.692) were unique in HB group, 5 N-glycan peaks (m/z 1954.677, 2507.914, 2580.930, 2637.952, and 3092.120) were unique in HC group, and 3 N-glycan peaks (m/z 2240.830, 2507.914, and 3931.338) were unique in HCC group. The proportion of fucosylated N-glycans was apparently increased in the HCC group (84.8%) than in any other group (73.1% ± 0.01), however, the proportion of sialylated N-glycans was decreased in HCC group (12.1%) than in any other group (17.23% ± 0.003). Our data provide pivotal information to distinguish between HBV-associated hepatitis, cirrhosis and HCC, and facilitate the discovery of biomarkers for HCC during its early stages based on precise alterations of N-linked glycans in saliva.     

Discovery and identification of potential biomarkers in a prospective study of chronic lymphoid malignancies using SELDI-TOF-MS

The accurate diagnosis of the different forms of chronic mature B-cell lymphocytic malignancies is of primary importance to determine an appropriate and efficient treatment. Usually, the diagnosis is achieved by morphology and immunophenotyping. Nevertheless, the diagnostic tools available are not able to discriminate pathologies with variable evolution, or to classify some of them. To discover new biomarkers, we used peptide and protein profiling SELDI-TOF-MS, to analyze 39 chronic B-cell malignancies and 20 control serum samples. Markers of interest were subsequently identified and characterized. In the obtained SELDI-MS profiles, most of the differences were observed in three mass ranges (m/z = 13 000; m/z = 9000; m/z < 2000). Identification of these biomarkers was achieved either by direct enrichment on the ProteinChip arrays followed by on-chip-MS/MS or by chromatographic fractionation, 1D-gel followed by nanoLC-MS/MS analysis. An increase of a sulfite form of transthyretin (13,841 Da) was observed in the patient group. A second set of markers at 8.6 and 8.9 kDa was identified as complement related fragment proteins, the C3a and C4a anaphylatoxins. In the low mass range, several peptides originating from N-terminal and C-terminal processing of the C3 alpha and C4 alpha chains were specifically observed in 38% of the patient sera, but in none of the control sera. This study emphasizes the usefulness of mass spectrometry studies in such malignancies.     

Evaluation of matrix-assisted laser desorption/ionization-time of flight mass spectrometry proteomic profiling: identification of alpha 2-HS glycoprotein B-chain as a biomarker of diet

Biomarkers have the potential to impact a wide range of public health concerns, including early detection of diseases, drug discovery, and improved accuracy of monitoring effects of interventions. Given new technological developments, broad-based screening approaches will likely advance biomarker discovery at an accelerated pace. Matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF MS) allows for the elucidation of individual protein masses from a complex mixture with high throughput. We have developed a method for identifying serum biomarkers using MALDI-TOF and statistical analysis. However, before applying this approach to screening of complex diseases, we evaluated the approach in a controlled dietary intervention study. In this study, MALDI-TOF spectra were generated using samples from a randomized controlled trial. During separate feeding periods, 38 participants ate a basal diet devoid of fruits and vegetables and a basal diet supplemented with cruciferous (broccoli) family vegetables. Serum samples were obtained at the end of each 7-day feeding period and treated to remove large, abundant proteins. MALDI-TOF spectra were analyzed using peak picking algorithms and logistic regression models. Our bioinformatics methods identified two significant peaks at m/z values of 2740 and 1847 that could classify participants based on diet (basal vs. cruciferous) with 76% accuracy. The 2740 m/z peak was identified as the B-chain of alpha 2-HS glycoprotein, a serum protein previously found to vary with diet and be involved in insulin resistance and immune function.     

Discrimination of intact mycobacteria at the strain level: a combined MALDI-TOF MS and biostatistical analysis

New methodologies for surveillance and identification of Mycobacterium tuberculosis are required to stem the spread of disease worldwide. In addition, the ability to discriminate mycobacteria at the strain level may be important to contact or source case investigations. To this end, we are developing MALDI-TOF MS methods for the identification of M. tuberculosis in culture. In this report, we describe the application of MALDI-TOF MS, as well as statistical analysis including linear discriminant and random forest analysis, to 16 medically relevant strains from four species of mycobacteria, M. tuberculosis, M. avium, M. intracellulare, and M. kansasii. Although species discrimination can be accomplished on the basis of unique m/z values observed in the MS fingerprint spectrum, discrimination at the strain level is predicted on the relative abundance of shared m/z values among strains within a species. For the 16 mycobacterial strains investigated in the present study, it is possible to unambiguously identify strains within a species on the basis of MALDI-TOF MS data. The error rate for classification of individual strains using linear discriminant analysis was 0.053 using 37 m/z variables, whereas the error rate for classification of individual strains using random forest analysis was 0.023 using only 18 m/z variables. In addition, using random forest analysis of MALDI-TOF MS data, it was possible to correctly classify bacterial strains as either M. tuberculosis or non-tuberculous with 100% accuracy.     

Assessment of different biomarkers provides valuable diagnostic standards in the evaluation of the risk of acute rejection

Acute rejection (AR) is a strong risk factor for chronic rejection in renal transplant recipients. Accurate and timely diagnosis of AR episodes is very important for disease control and prognosis. Therefore, objectively evaluated the immune status of patients is essential in the field of post-transplantation treatment. This longitudinal study investigated the usefulness of five biomarkers, human leukocyte antigen (HLA)-G5 and sCD30 level in sera, intracellular adenosine triphosphate (iATP) release level of CD4(+) T cells, and granzyme B/perforin expression in peripheral blood mononuclear cells (PBMCs) and biopsies, to detect AR and the resolution of biomarkers in a total of 84 cases of renal transplantation. The data demonstrated that recipients with clinical or biopsy proven rejection significantly increased iATP release level of CD4(+) T cells, and elevated sCD30 but lowered HLA-G5 level in sera compared with individuals with stable graft function. Expression levels of granzyme B and perforin were also elevated in PBMCs and graft biopsies of AR patients. Taken together, we identified that upregulation of sCD30, iATP, granzyme B, perforin, and downregulation of HLA-G5 could provide valuable diagnostic standards to identify those recipients in the risk of AR. And iATP may be a better biomarker than others for predicting the graft rejection episode.     

Classification of genus Pseudomonas by MALDI-TOF MS based on ribosomal protein coding in S10-spc-alpha operon at strain level

We have proposed a rapid phylogenetic classification at the strain level by MALDI-TOF MS using ribosomal protein matching profiling. In this study, the S10-spc-alpha operon, encoding half of the ribosomal subunit proteins and highly conserved in eubacterial genomes, was selected for construction of the ribosomal protein database as biomarkers for bacterial identification by MALDI-TOF MS analysis to establish a more reliable phylogenetic classification. Our method revealed that the 14 reliable and reproducible ribosomal subunit proteins with less than m/z 15,000, except for L14, coded in the S10-spc-alpha operon were significantly useful biomarkers for bacterial classification at species and strain levels by MALDI-TOF MS analysis of genus Pseudomonas strains. The obtained phylogenetic tree was consisted with that based on genetic sequence (gyrB). Since S10-spc-alpha operons of genus Pseudomonas strains were sequenced using specific primers designed based on nucleotide sequences of genome-sequenced strains, the ribosomal subunit proteins encoded in S10-spc-alpha operon were suitable biomarkers for construction and correction of the database. MALDI-TOF MS analysis using these 14 selected ribosomal proteins is a rapid, efficient, and versatile bacterial identification method with the validation procedure for the obtained results.     

Increased plasma mannose binding lectin levels are associated with bronchiolitis obliterans after lung transplantation

Background

Long-term lung allograft survival is limited by bronchiolitis obliterans syndrome (BOS). Mannose binding lectin (MBL) belongs to the innate immune system, participates in complement activation, and may predispose to graft rejection. We investigated mannose binding (MBL) during cold ischemia and in tissue samples from explanted lungs with BOS, and assessed MBL and complement proteins in plasma post-lung transplantation relative to BOS staging.

Methods

MBL was detected by immunohistochemistry lung tissue at the time of cold ischemia and in samples with BOS. MBL was assayed in the peripheral blood of 66 lung transplant patients transplanted between 1990–2007.

Results

MBL localized to vasculature and basement membrane during cold ischemia and BOS. Patients further out post-lung transplant > 5 years (n = 33), had significantly lower levels of MBL in the blood compared to lung transplant patients < 5 years with BOS Op-3 (n = 17), 1738 ± 250 ng/ml vs 3198 ± 370 ng/ml, p = 0.027, and similar levels to lung transplant patients < 5 years with BOS 0 (n = 16), 1738 ± 250 ng/ml vs 1808 ± 345 ng/ml. MBL levels in all BOS 0 (n = 30) vs. all BOS Op-3 (n = 36) were 1378 ± 275 ng/ml vs. 2578 ± 390 ng/ml, p = 0.001, respectively. C3 plasma levels in BOS 0 (n = 30) vs. BOS Op-3 (n = 36) were 101 ± 19.8 mg/ml vs. 114 ± 25.2 mg/ml, p = 0.024, respectively.

Conclusions

MBL localizes within the lung during graft ischemia and BOS, higher levels of plasma MBL are associated with BOS Op-3 and < 5 years post-transplant, and higher level of plasma complement protein C3 was associated with BOS Op-3 clinical status. MBL may serve as a biomarker for poorer outcome post-lung transplantation.