Purpose Gastroesophageal reflux disease is common in lung transplant recipients and is thought to cause lung graft injury through aspiration of gastric contents. Bile acids in bronchoalveolar lavage (BAL) are putative markers of gastric microaspiration and associated with inflammation and earlier chronic lung allograft dysfunction (CLAD). Microaspiration is thought to augment CLAD risk through potentiation of acute rejection (AR), although this has not been demonstrated. We hypothesized that BAL bile acid levels would be associated with AR presence and severity. Methods Among all adult, first, bilateral lung transplants, performed at two large lung transplant centers 2010-2015, transbronchial biopsies obtained within the first-year post-transplant were categorized as spirometrically-significant or stable based on the presence or absence of ≥10% concurrent drop in FEV1. AR diagnosis was based histology and biopsies with concurrent infection were excluded. BAL supernatant levels of bile acids (taurocholic acid (TCA), glycocholic acid (GCA), cholic acid), and inflammatory proteins (IL6, CXCL8, S100A8, CCL2, IL1β, CCL5, IL1α, RAGE, S100A12, IL12) were compared between patient groups. Association between BA levels and subsequent CLAD or death/retransplant was assessed using Cox Proportional Hazards models, adjusted for relevant peri-transplant clinical covariates and AR group. Endpoints We identified 42 patients with spirometrically-significant AR, 56 patients with stable AR, and 81 patients with stable no-AR with available BAL samples (one sample per patient). BAL at time of spirometrically-significant AR, compared to other groups, had elevated levels of TCA (ANOVA

At time of GERD diagnosis, lung transplant recipients are more likely to have a pulmonary microbiome lower in diversity and enriched in oropharyngeal taxa. These perturbations are consistent with microaspiration and may contribute to allograft inflammation. Future studies are warranted to assess how the pulmonary microbiome changes over time in the context of GERD and its correlation with rejection and long-term outcomes.

Purpose Gastroesophageal reflux disease (GERD) is prevalent after lung transplantation (LTx) and has been associated with allograft injury and chronic lung allograft dysfunction (CLAD) presumably through chronic microaspiration of bile acids and other gastric contents with subsequent innate immune activation. Anti-reflux surgery is widely used at some centers to treat GERD in LTx; however, its role in inflammation or aspiration is unknown. Our objective was to examine the effects of early anti-GERD surgery in LTx recipients on markers of microaspiration and inflammation in the bronchoalveolar lavage (BAL). Methods We identified 18 LTx recipients who underwent Nissen fundoplication within 6 months post LTx and who had BAL samples obtained within 3 months pre- and post-Nissen. BAL levels of IL-6, IL-8, S100A8, S100A12, CCL2, IL-1α, IL-1β, CCL5, sRAGE, and IL-12p70 were measured by multiplex assay. BAL levels of 3 most prevalent bile acids−cholic acid (CA), taurocholic acid (TCA), and glycocholic acid (GCA)−were measured by mass spectrometry. Values pre- and post-Nissen were compared using the paired Wilcoxon signed-rank test. Generalized Estimating Equation models were used to adjust for concurrent rejection, infection, and their treatment. Results IL-8, S100A8, IL-1α, IL-1β, CCL5, IL-12p70, and TCA were significantly reduced post-Nissen compared to pre-Nissen after adjustment (Figure 1). Other cytokines and bile acids were not significantly different between pre- and post-Nissen. However, most bile acid levels were very low; some patients had elevated bile acid levels pre-Nissen, which did not remain elevated post-Nissen. Conclusion Early anti-GERD surgery in LTx recipients is associated with a significant decrease in lung inflammation and may also decrease markers of microaspiration. Further studies are warranted to determine whether anti-reflux surgery can prevent allograft injury and CLAD in patients at risk. Gastroesophageal reflux disease (GERD) is prevalent after lung transplantation (LTx) and has been associated with allograft injury and chronic lung allograft dysfunction (CLAD) presumably through chronic microaspiration of bile acids and other gastric contents with subsequent innate immune activation. Anti-reflux surgery is widely used at some centers to treat GERD in LTx; however, its role in inflammation or aspiration is unknown. Our objective was to examine the effects of early anti-GERD surgery in LTx recipients on markers of microaspiration and inflammation in the bronchoalveolar lavage (BAL). We identified 18 LTx recipients who underwent Nissen fundoplication within 6 months post LTx and who had BAL samples obtained within 3 months pre- and post-Nissen. BAL levels of IL-6, IL-8, S100A8, S100A12, CCL2, IL-1α, IL-1β, CCL5, sRAGE, and IL-12p70 were measured by multiplex assay. BAL levels of 3 most prevalent bile acids−cholic acid (CA), taurocholic acid (TCA), and glycocholic acid (GCA)−were measured by mass spectrometry. Values pre- and post-Nissen were compared using the paired Wilcoxon signed-rank test. Generalized Estimating Equation models were used to adjust for concurrent rejection, infection, and their treatment. IL-8, S100A8, IL-1α, IL-1β, CCL5, IL-12p70, and TCA were significantly reduced post-Nissen compared to pre-Nissen after adjustment (Figure 1). Other cytokines and bile acids were not significantly different between pre- and post-Nissen. However, most bile acid levels were very low; some patients had elevated bile acid levels pre-Nissen, which did not remain elevated post-Nissen. Early anti-GERD surgery in LTx recipients is associated with a significant decrease in lung inflammation and may also decrease markers of microaspiration. Further studies are warranted to determine whether anti-reflux surgery can prevent allograft injury and CLAD in patients at risk.

Purpose Gastroesophageal reflux disease (GERD) is thought to expose the lungs to refluxed gastric contents leading to injury and chronic lung allograft dysfunction (CLAD) in lung transplant recipients (LTRs). Prior small studies showed correlations between lung bile acids and CLAD/survival. The goal of this study was to determine whether bile acid levels in the bronchoalveolar lavage (BAL) correlate with GERD, concurrent lung allograft inflammation, or development of CLAD. Methods The cohort consisted of 25 GERD-positive and 50 GERD-negative adult sequential LTRs who underwent 24h pH/impedance reflux testing and BAL collection within 6 months post-transplant. Bile acids - taurocholic acid (TCA), glycocholic acid (GCA), and cholic acid (CA) - were measured using LC-MS/MS mass spectrometry; 10 cytokines were quantified using a multiplex assay. Levels were compared between groups using generalized linear models. Spearman correlations between biomarkers were assessed. The relationship between biomarkers and time to CLAD was examined using Cox proportional hazards models. Results TCA was significantly higher in BALs of GERD-positive patients compared to GERD-negative (0.4 vs. 0.1, p=0.04), with no significant differences in GCA, CA, or cytokines. Importantly, there were correlations (adjusted for 10 multiple comparisons) between TCA and GCA and inflammatory markers IL-6, CXCL8, CCL2, IL-1β, CCL5, IL-1α, and IL-12p70 (Fig 1A). Additionally, TCA (HR 1.37, p=0.04), IL-6 (HR 1.59, p=0.012), S100A8 (HR 1.39, p=0.033), and CCL2 (HR 1.41, p=0.03) at the time of the BAL were significantly associated with time to CLAD, independent of GERD status (Fig 1B shows additional Kaplan-Meier analysis). Conclusion BAL TCA correlates with GERD, concurrent innate immune inflammation, as well as risk of CLAD. We propose that BAL TCA levels, in conjunction with inflammatory marker measurements, may be useful in identifying LTRs with chronic aspiration of enteric contents that have a higher risk of subsequent adverse outcomes. Gastroesophageal reflux disease (GERD) is thought to expose the lungs to refluxed gastric contents leading to injury and chronic lung allograft dysfunction (CLAD) in lung transplant recipients (LTRs). Prior small studies showed correlations between lung bile acids and CLAD/survival. The goal of this study was to determine whether bile acid levels in the bronchoalveolar lavage (BAL) correlate with GERD, concurrent lung allograft inflammation, or development of CLAD. The cohort consisted of 25 GERD-positive and 50 GERD-negative adult sequential LTRs who underwent 24h pH/impedance reflux testing and BAL collection within 6 months post-transplant. Bile acids - taurocholic acid (TCA), glycocholic acid (GCA), and cholic acid (CA) - were measured using LC-MS/MS mass spectrometry; 10 cytokines were quantified using a multiplex assay. Levels were compared between groups using generalized linear models. Spearman correlations between biomarkers were assessed. The relationship between biomarkers and time to CLAD was examined using Cox proportional hazards models. TCA was significantly higher in BALs of GERD-positive patients compared to GERD-negative (0.4 vs. 0.1, p=0.04), with no significant differences in GCA, CA, or cytokines. Importantly, there were correlations (adjusted for 10 multiple comparisons) between TCA and GCA and inflammatory markers IL-6, CXCL8, CCL2, IL-1β, CCL5, IL-1α, and IL-12p70 (Fig 1A). Additionally, TCA (HR 1.37, p=0.04), IL-6 (HR 1.59, p=0.012), S100A8 (HR 1.39, p=0.033), and CCL2 (HR 1.41, p=0.03) at the time of the BAL were significantly associated with time to CLAD, independent of GERD status (Fig 1B shows additional Kaplan-Meier analysis). BAL TCA correlates with GERD, concurrent innate immune inflammation, as well as risk of CLAD. We propose that BAL TCA levels, in conjunction with inflammatory marker measurements, may be useful in identifying LTRs with chronic aspiration of enteric contents that have a higher risk of subsequent adverse outcomes.