Natural genetic competence is the ability of cells to take up extracellular DNA and is an important mechanism for horizontal gene transfer. Another potential benefit of natural competence is that exogenous DNA can serve as a nutrient source for starving bacteria because the ability to "eat" DNA is necessary for competitive survival in environments containing limited nutrients. We show here that eight Escherichia coli genes, identified as homologs of com genes in Haemophilus influenzae and Neisseria gonorrhoeae, are necessary for the use of extracellular DNA as the sole source of carbon and energy. These genes also confer a competitive advantage to E. coli during long-term stationary-phase incubation. We also show that homologs of these genes are found throughout the proteobacteria, suggesting that the use of DNA as a nutrient may be a widespread phenomenon.

Rationale: After lung transplantation, insults to the allograft generally result in one of four histopathologic patterns of injury: (1) acute rejection, (2) lymphocytic bronchiolitis, (3) organizing pneumonia, and (4) diffuse alveolar damage (DAD). We hypothesized that DAD, the most severe form of acute lung injury, would lead to the highest risk of chronic lung allograft dysfunction (CLAD) and that a type I immune response would mediate this process. Objectives: Determine whether DAD is associated with CLAD and explore the potential role of CXCR3/ligand biology. Methods: Transbronchial biopsies from all lung transplant recipients were reviewed. The association between the four injury patterns and subsequent outcomes were evaluated using proportional hazards models with time-dependent covariates. Bronchoalveolar lavage (BAL) concentrations of the CXCR3 ligands (CXCL9/MIG, CXCL10/ IP10, and CXCL11/ITAC) were compared between allograft injury patterns and "healthy" biopsies using linear mixed-effects models. The effect of these chemokine alterations on CLAD risk was assessed using Cox models with serial BAL measurements as time-dependent covariates. Measurements and Main Results: There were 1,585 biopsies from 441 recipients with 62 episodes of DAD. An episode of DAD was associated with increased risk of CLAD (hazard ratio, 3.0; 95% confidence interval, 1.9-4.7) and death (hazard ratio, 2.3; 95% confidence interval, 1.7-3.0). There were marked elevations in BAL CXCR3 ligand concentrations during DAD. Furthermore, prolonged elevation of these chemokines in serial BAL fluid measurements predicted the development of CLAD. Conclusions: DAD is associated with marked increases in the risk of CLAD and death after lung transplantation. This association may be mediated in part by an aberrant type I immune response involving CXCR3/ligands. Keywords: lung transplantation; chronic lung allograft dysfunction; bronchiolitis obliterans syndrome; diffuse alveolar damage; CXC chemokines Lung transplantation has one of the highest mortality rates among solid organ transplants: 48% at 5 years and 71% at 10 years (1). Chronic lung allograft dysfunction (CLAD) is the major factor limiting long-term survival (2). There is accumulating evidence that CLAD has two distinct phenotypes: bronchiolitis obliterans syndrome (BOS) and restrictive allograft syndrome (RAS). These subtypes of CLAD seem to differ in their clinical characteristics and prognosis (3-5). CLAD has traditionally been recognized as BOS with progressive irreversible obstruction on pulmonary function testing (PFT) caused by fibroobliteration of the small airways. Among double lung transplant recipients (LTRs), RAS has recently been identified as another phenotype of CLAD with restriction on PFT caused by fibrosis of the lung parenchyma (4). RAS seems to have significantly higher mortality compared with BOS (3-5). Because there is no known effective treatment for CLAD or its subtypes (BOS and RAS), the identification and avoidance of risk factors are critical.Prior studies ...

BACKGROUND Pulmonary non-tuberculous mycobacterial (NTM) infection is relatively common after lung transplantation, but the effect on mortality remains undetermined. Herein we describe our experience with pulmonary NTM infection after lung transplantation and hypothesized that non-tuberculous mycobacterial infection after lung transplantation would be associated with increased mortality. METHODS We retrospectively evaluated 201 primary lung transplant recipients transplanted between January 2000 and August 2006. Serial bronchoscopies with bronchoalveolar lavage and transbronchial biopsy were performed according to a surveillance protocol and when clinically indicated. The diagnosis NTM infection was established by a positive NTM culture in a bronchoalveolar lavage sample or in at least two separate expectorated sputum samples. NTM infections were further classified as “disease” or “colonization,” based on whether or not NTM infection patients developed symptoms and characteristic radiographic findings. RESULTS Thirty-six (18%) recipients were diagnosed with pulmonary NTM infection at a median of 97 days post-transplantation: 9 were classified as NTM disease and the remaining 27 as NTM colonization cases. Single lung transplant was a significant risk factor for NTM infection (HR 2.25, p = 0.02). NTM colonization was a risk factor for NTM disease (HR 8.39, p = 0.003). NTM infection significantly increased the risk of death after lung transplantation (HR 2.61, p = 0.001) and persisted in multivariate models controlling for single lung transplant and bronchiolitis obliterans syndrome. The increased risk was seen for both NTM colonization and NTM disease. Among the patients who died, non-NTM infection was a more common contributing factor in the cause of death for the NTM infection group (44% vs 12%, p = 0.04). CONCLUSIONS Non-tuberculous mycobacterial infection is common after lung transplantation. NTM colonization and treated acute rejection are risk factors for NTM disease. NTM infection is associated with increased risk of mortality independent of bronchiolitis obliterans syndrome.

Rationale: Pseudomonas aeruginosa is the most commonly isolated gram-negative bacterium after lung transplantation and has been shown to up-regulate glutamic acid-leucine-arginine-positive (ELR 1 ) CXC chemokines associated with bronchiolitis obliterans syndrome (BOS), but the effect of pseudomonas on BOS and death has not been well defined. Objectives: To determine if the influence of pseudomonas isolation and ELR 1 CXC chemokines on the subsequent development of BOS and the occurrence of death is time dependent. Methods: A three-state model was developed to assess the likelihood of transitioning from lung transplant (state 1) to BOS (state 2), from transplant (state 1) to death (state 3), and from BOS (state 2) to death (state 3). This Cox semi-Markovian approach determines state survival rates and cause-specific hazards for movement from one state to another. Measurements and Main Results: The likelihood of transition from transplant to BOS was increased by acute rejection, CXCL5, and the interaction between pseudomonas and CXCL1. The pseudomonas effect in this transition was due to infection rather than colonization. Movement from transplant to death was facilitated by pseudomonas infection and single lung transplant. Transition from BOS to death was affected by the length of time in state 1 and by the interactions between any pseudomonas isolation and CXCL5 and aspergillus, either independently or in combination. Conclusions: Our model demonstrates that common post-transplantation events drive movement from one post-transplantation state to another and influence outcomes differently depending upon when after transplantation they occur. Pseudomonas and the ELR 1 CXC chemokines may interact to negatively influence lung transplant outcomes.Keywords: transplantation; lung; BOS; pseudomonas; chemokine Lung transplantation is a life-saving procedure for end-stage lung disease. Long-term success is limited by the high incidence of chronic lung allograft dysfunction, predominantly due to bronchiolitis obliterans syndrome (BOS). Acute rejection is perhaps the most widely recognized event to increase the risk of chronic lung allograft dysfunction. There is expanding evidence that a variety of infections increase the chances of developing BOS. Fungal pneumonia or colonization (1, 2) and viral pneumonitis (1, 3, 4) are among infectious conditions shown to increase the risk of BOS. However, the most commonly isolated pathogens after lung transplantation are bacteria, broadly separated into gram-negative and gram-positive organisms (5-8). The gram-negative Pseudomonas aeruginosa is the most frequently isolated bacterium after lung transplantation (5-7, 9-12). Moreover, bacterial pulmonary infections have been associated with increased bronchoalveolar lavage fluid (BALF) levels of inflammatory markers, including the glutamic acid-leucine-arginine-positive (ELR 1 ) CXC chemokine IL-8 (CXCL8) (13-16). Prior studies have suggested that pseudomonas may influence the development of BOS by de novo colonization after lung transp...