Bile acid aspiration associated with lung chemical profile linked to other biomarkers of injury after lung transplantation.

Aspiration of gastrointestinal contents has been linked to worse outcomes following lung transplantation but uncertainty exists about underlying mechanisms. We applied high-resolution metabolomics of bronchoalveolar lavage fluid (BALF) in patients with episodic aspiration (defined by bile acids in the BALF) to identify potential metabolic changes associated with aspiration. Paired samples, one with bile acids and another without, from 29 stable lung transplant patients were studied. Liquid chromatography coupled to high-resolution mass spectroscopy was used to interrogate metabolomic contents of these samples. Data were obtained for 7068 ions representing intermediary metabolites, environmental agents and chemicals associated with microbial colonization. A substantial number (2302) differed between bile acid positive and negative samples when analyzed by false discovery rate at q = 0.01. These included pathways associated with microbial metabolism. Hierarchical cluster analysis defined clusters of chemicals associated with bile acid aspiration that were correlated to previously reported biomarkers of lung injury including T cell granzyme B level and the chemoattractants CXCL9 and CXCL10. These data specifically link bile acids presence in lung allografts to inflammatory pathways known to segregate with worsening allograft outcome, and provide additional mechanistic insight into the association between reflux and lung allograft injury.

Cumulative exposure to gamma interferon-dependent chemokines CXCL9 and CXCL10 correlates with worse outcome after lung transplant.

Outcomes following lung transplant are suboptimal owing to chronic allograft failure termed bronchiolitis obliterans syndrome (BOS). Prior work in both mice and humans has shown that interferon gamma (IFNG)-induced chemokines, including CXCL9 and CXCL10, are elevated in patients with established BOS. We hypothesized that patients who ultimately developed BOS would have elevations in these chemokines before losing lung function. We utilized a high throughput multiplex enzyme-linked immunosorbent assay (ELISA) to measure biomarkers in bronchoalveolar lavage fluid (BALF). We modeled cumulative exposure to seven biomarkers (CXCL9, CXCL10, RANTES, IL1-RA, IL-17, MCP1 and IL-13) by calculating the 1-year area under the curve (AUC) for each biomarker in the BALF of 40 lung transplant patients who had at least four samples obtained in the first year posttransplant. Cumulative elevations in CXCL9 and CXCL10 were associated with a significant risk of subsequent graft failure after transplant (HR 9.37 and 5.52, respectively; p < 0.01 for both). Further these chemokines were also elevated in patients before the onset of BOS. CXCL9 and CXCL10 elevations were seen between 3 and 9 months before graft failure. Our data show that persistent presence of CXCL9 and CXCL10 portents worsening lung allograft function; measuring these IFNG-induced chemokines might prospectively identify patients at risk for BOS.

Cumulative exposure to CD8+ granzyme Bhi T cells is associated with reduced lung function early after lung transplantation.

Outcomes following lung transplant remain suboptimal. This is attributable to variable posttransplant recovery of lung function, and inconsistent degrees of lung function loss after peak function is reached. Granzyme B is elevated in the blood and bronchoalveolar lavage (BAL) in acute rejection. We hypothesized that persistent exposure to T cells high in granzyme B would negatively correlate with lung function. We investigated cumulative exposure measured as the area-under-the-curve (AUC) of CD8+ T cell granzyme Bhi cells in the first year posttransplant in both BAL and blood in 24 transplant recipients. We assessed the correlation between cumulative 1-year exposure and FEV1 slope. There was a negative correlation between 1-year exposure and FEV1 slope within the first year (r=-0.63; P=.001). This relationship persisted even when adjusted for transplant type, gender, age, rejection, and indication for transplantation. In contrast, no relationship was seen with the 1-year AUC and lung function after 1 year posttransplant. In contrast to the BAL granzyme Bhi levels, granzyme Bhi levels from the blood showed no relationship with lung function. These findings suggest that CD8+ T-cell-driven factors are responsible for early improvements in lung function after transplantation.

Gastroesophageal reflux disease is associated with an increased rate of acute rejection in lung transplant allografts.

PURPOSE: Gastric fundoplication (GF) for gastroesophageal reflux disease (GERD) may protect against the progression of chronic rejection in lung transplant (LT) recipients. However, the association of GERD with acute rejection episodes (ARE) is uncertain. This study sought to identify if ARE were linked to GERD in LT patients. METHODS: This single-center retrospective observational study, of patients transplanted from January 1, 2000, to January 31, 2009, correlated results of pH probe testing for GERD with ARE (≥International Society for Heart and Lung Transplantation A1 or B1). We compared the rates of ARE among patients with GERD (DeMeester Score > 14.7) versus without GERD as number of ARE per 1,000 patient-days after LT. Patients undergoing GF prior to LT were excluded. RESULTS: The analysis included 60 LT subjects and 9,249 patient-days: 33 with GERD versus 27 without GERD. We observed 51 ARE among 60 LT recipients. The rate of ARE was highest among patients with GERD: 8.49 versus 2.58, an incidence density ratio (IDR) of 3.29 (P = .00016). Upon multivariate negative binomial regression modeling, only GERD was associated with ARE (IDR 2.15; P = .009). Furthermore, GERD was associated with multiple ARE (36.4% vs 0%; P < .0001) and earlier onset compared with patients without GERD: ARE proportion at 2 months was 0.55 versus 0.26 P = .004). CONCLUSION: In LT recipients, GERD was associated with a higher rate, multiple events, and earlier onset of ARE. The efficacy of GF to reduce ARE among patients with GERD needs further evaluation.

Receptor for advanced glycation end products in donor lungs is associated with primary graft dysfunction after lung transplantation.

Development of primary graft dysfunction (PGD) is associated with poor outcomes after transplantation. We hypothesized that Receptor for Advanced Glycation End-products (RAGE) levels in donor lungs is associated with the development of PGD. Furthermore, we hypothesized that RAGE levels would be increased with PGD in recipients after transplantation. We measured RAGE in bronchoalveolar lavage fluid (BALf) from 25 donors and 34 recipients. RAGE was also detected in biopsies (transbronchial biopsy) from recipients with and without PGD. RAGE levels were significantly higher in donor lungs that subsequently developed sustained PGD versus transplanted lungs that did not display PGD. Donor RAGE level was a predictor of recipient PGD (odds ratio = 1.768 per 0.25 ng/mL increase in donor RAGE level). In addition, RAGE levels remained high for 14 days in those recipients that developed severe graft dysfunction. Recipients may be at higher risk for developing PGD if they receive transplanted organs that have higher levels of soluble RAGE prior to explantation. Moreover, the clinical and pathologic abnormalities associated with PGD posttransplantation are associated with increased RAGE expression. These findings also raise the possibility that targeting the RAGE signaling pathway could be a novel strategy for treatment and/or prevention of PGD.

Immunostimulatory properties of genomic DNA from different bacterial species.

Bacterial DNA has potent immunological properties because of its content of immunostimulatory sequences centering on CpG motifs. To investigate whether DNA from various bacterial species differ in these properties, the activity of a panel of DNA was assessed in in vitro cultures of murine spleen cells. This panel varied in base composition and included DNA from Clostridium perfringens (CP), Escherichia coli (EC), Micrococcus lysodeikticus (MC), Staphylococcus aureus (SA), and, as a mammalian DNA control, calf thymus (CT) DNA. In assays of IL-12 and IFN-gamma production as well as B cell mitogenesis, these DNA showed marked differences in their immunostimulatory activity. For both cytokine and B cell responses, EC DNA demonstrated the highest activity while CP DNA had the lowest activity among the bacterial DNA. To determine whether differences in stimulatory capacity resulted from differences in cell uptake, the activity of DNA complexed with lipofectin was tested. While the addition of lipofectin to DNA increased stimulation by all DNA, it did not change the relative potency of the DNA tested. These results indicate that bacterial DNA differ in their immunostimulatory capacity, most likely reflecting their content of CpG motifs. These differences could affect the induction of innate immunity as well as the consequences of infection.