Bronchoalveolar lavage in lung transplantation. State of the art

Prospective phase II trial of montelukast to treat bronchiolitis obliterans syndrome after hematopoietic cell transplant and investigation into BOS pathogenesis

BACKGROUND

Bronchiolitis obliterans syndrome (BOS) is a severe manifestation of chronic graft-versus-host disease (cGVHD) following hematopoietic cell transplantation (HCT). Montelukast interrupts cysteinyl leukotriene activity and may diminish the activation and homing of cells to bronchioles and subsequent fibrosis.

OBJECTIVE

We performed a prospective phase II trial to test whether montelukast altered lung decline for patients with BOS after HCT.

STUDY DESIGN

We performed a single arm, open-label, multi-institutional study with primary endpoints of: i) FEV1 stability or improvement (<15% decline) and ii) slope of FEV1<1 point decline after six months treatment. Secondary endpoints included symptom and functional response, and immune correlates investigating the role of leukotrienes in BOS progression.

RESULTS

25 patients enrolled with moderate to severe lung disease after three months of stable cGVHD therapy. Montelukast was well-tolerated and no patient required escalation of BOS-directed therapy. At the primary endpoint, all evaluable patients (n=23) met criteria for treatment success using FEV1% predicted, and all but one had stable or improved FEV1 slope. In those with >5% FEV1 improvement, clinically meaningful improvements were seen in the Lee scores of breathing, energy, and mood. Improvements in the Human Activity Profile and 6-minute-walk test were observed in those with <5% FEV1 decline. Overall survival was 87% at two-years. Immune correlates showed elevated leukotriene receptor levels on blood eosinophils and monocytes vs. healthy controls, elevated urine leukotrienes in 45% of cohort, and cysteinyl leukotriene receptors on bronchoalveolar lavage subsets and a predominance of Th2 T cells, all pre-treatment.

CONCLUSIONS

These data suggest that montelukast may safely halt progression of BOS after HCT and that leukotrienes may play a role in the biology of BOS.

Lung allograft donors with excessive alcohol use have increased levels of human antimicrobial peptide LL-37

The relatively low long-term survival rate of lung transplant recipients as compared to other organ recipients serves as an impetus to identify potential lung dysfunction as early as possible. There is an association between donor heavy alcohol use and acute lung injury in the lung allograft after transplant, known as primary graft dysfunction. Excessive alcohol use (EAU) can induce pulmonary immune dysregulation in response to an infection. Antimicrobial peptides (AMPs) are an important component of the innate immune response to pulmonary infections, but the impact of EAU on AMPs in the allograft lung has not been evaluated. Our hypothesis is that specific lung AMPs, LL-37, α-defensin-1,2,3, and β-defensin-2, are dysregulated in the lungs from organ donors who had EAU. In this prospective observational investigation, we measured AMPs via ELISA and inflammatory cytokines via multiplex bead array, in bronchoalveolar lavage (BAL) fluid of lung allograft donors, comparing results based on their alcohol consumption. LL-37 levels in lung donors with EAU were found to be increased compared to nondrinker (ND) donors [median 7.7 ng/mL (IQR 4.1-37.0) vs. 2.3 ng/mL (IQR 1.1-7.9), p = 0.004], whereas α-defensins-1,2,3 were decreased only in the presence of an infection in donors with EAU compared to ND donors [median 2.2 ng/mL (IQR 1.6-2.4) vs. 3.2 ng/mL (IQR 2.3-3.8), p = 0.049]. There was no difference in β-defensin-2 levels. Gene expression levels of these AMPs were not different. Elevated levels of CXCL8 were noted in bronchial washings of donors with EAU compared to ND donors, [median 4372 pg/mL (IQR 3352-13180) vs. 867.3 pg/mL (IQR 163.6-3675), p = 0.04], suggesting a potentially heightened inflammatory response. At 1 month post-transplant, LL-37 and CXCL8 levels are decreased compared to levels at time of transplant. In lung donors with EAU, LL-37 and α-defensins-1,2,3 dysregulated levels in the presence of an infection may be a harbinger of dysfunction of the lungs through the transplant process.

Bronchoalveolar lavage cytokines are of minor value to diagnose complications following lung transplantation

Early diagnosis and treatment of acute cellular rejection (ACR) may improve long-term outcome for lung transplant recipients (LTRs). Cytokines have become valuable diagnostic tools in many medical fields. The role of bronchoalveolar lavage (BAL) cytokines is of unknown value to diagnose ACR and distinguish rejection from infection. We hypothesized that distinct cytokine patterns obtained by surveillance bronchoscopies during the first year after transplantation are associated with ACR and microbiologic findings.

We retrospectively analyzed data from 319 patients undergoing lung transplantation at University Hospital Zurich from 1998 to 2016. We compared levels of IL-6, IL-8, IFN-γ and TNF-α in 747 BAL samples with transbronchial biopsies (TBB) and microbiologic results from surveillance bronchoscopies. We aimed to define reference values that would allow distinction between four specific groups “ACR”, “infection”, “combined ACR and infection” and “no pathologic process”. No definitive pattern was identified. Given the overlap between groups, these four cytokines are not suitable diagnostic markers for ACR or infection after lung transplantation.

Detection of lung transplant rejection in a rat model using hyperpolarized [1-13 C] pyruvate-based metabolic imaging

The current standard for noninvasive imaging of acute rejection consists of X-ray/CT, which derive their contrast from changes in ventilation, inflammation and edema, as well as remodeling during rejection. We propose the use of hyperpolarized [1-¹³ C] pyruvate MRI-which provides real-time metabolic assessment of tissue-as an early biomarker for tissue rejection. In this preliminary study, we used μCT-derived parameters and HP ¹³ C MR-derived biomarkers to predict rejection in an orthotopic left lung transplant model in both allogeneic and syngeneic rats. On day 3, the normalized lung density-a parameter that accounts for both lung volume (mL) and density (HU)-was -0.335 (CI: -0.598, -0.073) and - 0.473 (CI: -0.726, -0.220) for the allograft and isograft, respectively (not significant, 0.40). The lactate-to-pyruvate ratios-derived from the HP ¹³ C MRI-for the allograft and isograft were 0.200 (CI: 0.161, 0.240) and 0.114 (CI: 0.074, 0.153), respectively (significant, 0.020). Both techniques showed tissue rejection on day 7. A separate sub-study revealed CD8+ cells as the primary source of the lactate-to-pyruvate signal. Our study suggests that hyperpolarized (HP) [1-¹³ C] pyruvate MRI is a promising early biomarker for tissue rejection that provides metabolic assessment in real time based on changes in cellularity and metabolism of lung tissue and the infiltrating inflammatory cells, and may be able to predict tissue rejection earlier than X-ray/CT.

Plasma and bronchoalveolar lavage samples in acute lung allograft rejection: the potential role of cytokines as diagnostic markers

The role of differential cytology patterns in peripheral blood and bronchoalveolar lavage samples is increasingly investigated as a potential adjunct to diagnose acute and chronic allograft dysfunction after lung transplantation. While these profiles might facilitate the diagnosis of acute cellular rejection, low sensitivity and specificity of these patterns limit direct translation in a clinical setting. In this context, the identification of other biomarkers is needed. This review article gives an overview of cytokine profiles of plasma and bronchoalveolar lavage samples during acute cellular rejection. The value of these cytokines in supporting the diagnosis of acute cellular rejection is discussed. Current findings on the topic are highlighted and experimental settings for future research projects are identified.

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.

A pharmacokinetic analysis of posaconazole oral suspension in the serum and alveolar compartment of lung transplant recipients

Invasive fungal infections cause significant morbidity and mortality after lung transplantation. Fungal prophylaxis following lung transplantation is not standardised, with transplant centres utilising a variety of regimens. Posaconazole is a broad-spectrum antifungal triazole that requires further investigation within the setting of lung transplantation. This prospective, single-centre, observational study explored the pharmacokinetics of posaconazole oral suspension (POS) in the early perioperative period following lung transplantation in 26 patients. Organ recipients were scheduled to receive 400mg POS twice daily for 6 weeks as primary antifungal prophylaxis. Therapeutic drug monitoring (TDM) of serum posaconazole levels was performed in accordance with local clinical protocols. Bronchoalveolar lavage fluid (BALF) was sampled during routine bronchoscopies. Posaconazole levels were measured both in serum and BALF using mass spectrometry. Posaconazole levels were highly variable within lung transplant recipients during the perioperative period and did not achieve 'steady-state'. Serum posaconazole concentrations positively correlated with levels within the BALF (r=0.5527; P=0.0105). Of the 26 patients, 10 failed to complete the study for multiple reasons and so the trial was terminated early. Unlike study findings in stable recipients, serum posaconazole levels rarely achieved steady-state in the perioperative period; however, they do reflect the concentrations within the airways of newly transplanted lungs. The role of POS as primary prophylaxis in the perioperative period is uncertain, but if used TDM may be helpful for determining attainment of therapeutic levels.

Immunosuppression and allograft rejection following lung transplantation: evidence to date

The enduring success of lung transplantation is built on the use of immunosuppressive drugs to stop the immune system from rejecting the newly transplanted lung allograft. Most patients receive a triple-drug maintenance immunosuppressive regimen consisting of a calcineurin inhibitor, an antiproliferative and corticosteroids. Induction therapy with either an antilymphocyte monoclonal or an interleukin-2 receptor antagonist are prescribed by many centres aiming to achieve rapid inhibition of recently activated and potentially alloreactive T lymphocytes. Despite this generic approach acute rejection episodes remain common, mandating further fine-tuning and augmentation of the immunosuppressive regimen. While there has been a trend away from cyclosporine and azathioprine towards a preference for tacrolimus and mycophenolate mofetil, this has not translated into significant protection from the development of chronic lung allograft dysfunction, the main barrier to the long-term success of lung transplantation. This article reviews the problem of lung allograft rejection and the evidence for immunosuppressive regimens used both in the short- and long-term in patients undergoing lung transplantation.

Bronchoalveolar lavage cell immunophenotyping facilitates diagnosis of lung allograft rejection

Supplementary methods to identify acute rejection and to distinguish rejection from infection may improve clinical outcomes for lung allograft recipients. We hypothesized that distinct bronchoalveolar lavage (BAL) cell profiles are associated with rejection and infection. We retrospectively compared 2939 BAL cell counts and immunophenotypes against concomitantly obtained transbronchial biopsies and microbiologic studies. We randomly assigned 317 subjects to a derivation or validation cohort. BAL samples were classified into four groups: infection, rejection grade ≥A1, both or neither. We employed generalized estimating equation and survival modeling to identify clinical predictors of rejection and infection. We found that CD25(+) and natural killer cell percentages identified a twofold increased odds of rejection compared to either the infection or the neither infection nor rejection groups. Also, monocytes, lymphocytes and eosinophil percentages were independently associated with rejection. A four-predictor scoring system had high negative predictive value (96-98%) for grade ≥A2 rejection, predicted future rejection in the validation cohort and predicted increased risk of bronchiolitis obliterans syndrome in otherwise benign samples. In conclusion, BAL cell immunophenotyping discriminates between infection and acute rejection and predicts future outcomes in lung transplant recipients. Although it cannot replace histopathology, immunophenotyping may be a clinically useful adjunct.

Elevated CXCL10 (IP-10) in bronchoalveolar lavage fluid is associated with acute cellular rejection after human lung transplantation

BACKGROUND

CXCL10 (IP-10) is a potent chemoattractant for T cells that has been postulated to play a role in infection and acute cellular rejection (ACR) in animal models. We measured CXCL10 (IP-10) (and other cytokines previously implicated in the pathogenesis of ACR) in the bronchoalveolar lavage (BAL) of lung transplant recipients (LTRs) to determine the association between CXCL10 (IP-10) and ACR in LTRs.

METHODS

In a prospective study of 85 LTRs, expression of cytokines (tumor necrosis factor, interferon-γ, interleukin [IL]-6, IL-8, IL-15, IL-16, IL-17, CXCL10 [IP-10], and MCP-1 [CCL2]) in BAL samples (n=233) from patients with episodes of ACR (n=44), infection ("Infect"; n=25), concomitant "Infect+ACR" (n=10), and "No Infect and No ACR" (n=154) were analyzed.

RESULTS

The levels of both CXCL10 (IP-10) and IL-16 were significantly increased in histologically proven ACR compared with the "No Infect and No ACR" group (CXCL10 [IP-10]: 107.0 vs. 31.9 pg/mL [P=0.001] and IL-16: 472.1 vs. 283.01 pg/mL [P=0.01]). However, in a linear mixed-effects model, significant association was found only between CXCL10 (IP-10) and ACR. A one-log increase of CXCL10 (IP-10) was associated with a 40% higher risk of ACR (odds ratio, 1.4; 95% confidence interval, 1.12-1.84).

CONCLUSION

Higher values of CXCL10 (IP-10) in BAL fluid are associated with ACR in LTRs, suggesting a potential mechanistic role in the pathogenesis of ACR in LTRs. These results suggest that therapeutic strategies to inhibit CXCL10 (IP-10) and or its cognate receptor, CXCR3, warrant investigation to prevent and/or treat ACR in clinical lung transplantation.

Pulmonary immune changes early after laparoscopic antireflux surgery in lung transplant patients with gastroesophageal reflux disease

BACKGROUND

The biologic mechanisms by which laparoscopic antireflux surgery (LARS) might influence the inflammatory process leading to bronchiolitis obliterans syndrome are unknown. We hypothesized that LARS alters the pulmonary immune profile in lung transplant patients with gastroesophageal reflux disease.

METHODS

In 8 lung transplant patients with gastroesophageal reflux disease, we quantified and compared the pulmonary leukocyte differential and the concentration of inflammatory mediators in the bronchoalveolar lavage fluid (BALF) 4 weeks before LARS, 4 weeks after LARS, and 12 months after lung transplantation. Freedom from bronchiolitis obliterans syndrome (graded 1-3 according to the International Society of Heart and Lung Transplantation guidelines), forced expiratory volume in 1 second trends, and survival were also examined.

RESULTS

At 4 weeks after LARS, the percentages of neutrophils and lymphocytes in the BALF were reduced (from 6.6% to 2.8%, P = 0.049, and from 10.4% to 2.4%, P = 0.163, respectively). The percentage of macrophages increased (from 74.8% to 94.6%, P = 0.077). Finally, the BALF concentration of myeloperoxide and interleukin-1β tended to decrease (from 2109 to 1033 U/mg, P = 0.063, and from 4.1 to 0 pg/mg protein, P = 0.031, respectively), and the concentrations of interleukin-13 and interferon-γ tended to increase (from 7.6 to 30.4 pg/mg protein, P = 0.078 and from 0 to 159.5 pg/mg protein, P = 0.031, respectively). These trends were typically similar at 12 months after transplantation. At a mean follow-up of 19.7 months, the survival rate was 75% and the freedom from bronchiolitis obliterans syndrome was 75%. Overall, the forced expiratory volume in 1 second remained stable during the first year after transplantation.

CONCLUSIONS

Our preliminary study has demonstrated that LARS can restore the physiologic balance of pulmonary leukocyte populations and that the BALF concentration of pro-inflammatory mediators is altered early after LARS. These results suggest that LARS could modulate the pulmonary inflammatory milieu in lung transplant patients with gastroesophageal reflux disease.

Respiratory Tract and Mediastinum

Normal cytology, abnormal and atypical cells, non-cellular components, and infectious cell changes are largely described together with benign, malignant, and neuroendocrine lesions regarding exfoliative and aspiration cytology of the lung. A separate section broadly addresses diagnostic findings and differential diagnoses in bronchoalveolar washings.

The section ‘Fine needle aspiration biopsy of mediastinal disorders’ covers in particular biopsy techniques, accuracy of liquid-based cytology, and the complex lesions of the thymus gland. Cytodiagnostic algorithms of the major benign and malignant pulmonary and mediastinal lesions and their respective differential diagnoses are additionally presented in synoptic setups.

Mesenchymal stromal cells in bronchoalveolar lavage as predictors of bronchiolitis obliterans syndrome

RATIONALE

Bronchoalveolar lavage fluid (BAL) from human lung allografts demonstrates the presence of a multipotent mesenchymal stromal cell population. However, the clinical relevance of this novel cellular component of BAL and its association with bronchiolitis obliterans syndrome (BOS), a disease marked by progressive airflow limitation secondary to fibrotic obliteration of the small airways, remains to be determined.

OBJECTIVES

In this study we investigate the association of number of mesenchymal stromal cells in BAL with development of BOS in human lung transplant recipients.

METHODS

Mesenchymal colony-forming units (CFUs) were quantitated in a cohort of 405 BAL samples obtained from 162 lung transplant recipients. Poisson generalized estimating equations were used to determine the predictors of BAL mesenchymal CFU count.

MEASUREMENTS AND MAIN RESULTS

Higher CFU counts were noted early post-transplantation; time from transplant to BAL of greater than 3 months predicted 0.4-fold lower CFU counts (P = 0.0001). BOS diagnosis less than or equal to 365 days before BAL was associated with a 2.11-fold higher CFU count (P = 0.02). There were 2.62- and 2.70-fold higher CFU counts noted in the presence of histologic diagnosis of bronchiolitis obliterans (P = 0.05) and organizing pneumonia (0.0003), respectively. In BAL samples obtained from BOS-free patients greater than 6 months post-transplantation (n = 173), higher mesenchymal CFU counts (≥10) significantly predicted BOS onset in both univariate (hazard ratio, 5.61; 95% CI, 3.03-10.38; P < 0.0001) and multivariate (hazard ratio, 5.02; 95% CI, 2.40-10.51; P < 0.0001) Cox regression analysis.

CONCLUSIONS

Measurement of mesenchymal CFUs in the BAL provides predictive information regarding future BOS onset.

Detection of human cytomegalovirus in bronchoalveolar lavage fluid of lung transplant recipients reflects local virus replication and not contamination from the throat

Whether bronchoalveolar lavage (BAL) fluid may be contaminated with oropharyngeal cytomegalovirus (CMV) has never been investigated. In an analysis of CMV DNA loads in 76 simultaneously obtained BAL fluid and throat wash samples from lung transplant recipients, we show that such contamination is unlikely and that detection of CMV DNA in BAL fluid reflects virus replication in the lung.

A review of the potential applications and controversies of non-invasive testing for biomarkers of aspiration in the lung transplant population

Despite improvements in one-yr survival following lung transplantation, five-yr survival lags significantly behind the transplantation of other solid organs. The contrast in survival persists despite advancements in anti-rejection regimens, suggesting a non-alloimmune mechanism to chronic lung transplant failure. Notably, markers of aspiration have been demonstrated in bronchoalveolar lavage (BAL) fluid concurrent with bronchiolitis obliterans syndrome (BOS). This recent evidence has underscored gastroesophageal reflux (GER) and its associated aspiration risk as a non-alloimmune mechanism of chronic lung transplant failure. Given the suggested safety and efficacy of laparoscopic anti-reflux procedures in the lung transplant population, identifying those at risk for aspiration is of prime importance, especially concerning the potential for long-term improvements in morbidity and mortality. Conventional diagnostic methods for GER and aspiration, such as pH monitoring and detecting pepsin and bile salts in BAL fluid, have gaps in their effectiveness. Therefore, we review the applications and controversies of a non-invasive method of defining reflux injury in the lung transplant population: the detection of biomarkers of aspiration in the exhaled breath condensate. Only by means of assay standardization and directed collaboration may such a non-invasive method be a realization in lung transplantation.

Acute rejection and humoral sensitization in lung transplant recipients

Despite the recent introduction of many improved immunosuppressive agents for use in transplantation, acute rejection affects up to 55% of lung transplant recipients within the first year after transplant. Acute lung allograft rejection is defined as perivascular or peribronchiolar mononuclear inflammation. Although histopathologic signs of rejection often resolve with treatment, the frequency and severity of acute rejections represent the most important risk factor for the subsequent development of bronchiolitis obliterans syndrome (BOS), a condition of progressive airflow obstruction that limits survival to only 50% at 5 years after lung transplantation. Recent evidence demonstrates that peribronchiolar mononuclear inflammation (also known as lymphocytic bronchiolitis) or even a single episode of minimal perivascular inflammation significantly increase the risk for BOS. We comprehensively review the clinical presentation, diagnosis, histopathologic features, and mechanisms of acute cellular lung rejection. In addition, we consider emerging evidence that humoral rejection occurs in lung transplantation, characterized by local complement activation or the presence of antibody to donor human leukocyte antigens (HLA). We discuss in detail methods for HLA antibody detection as well as the clinical relevance, the mechanisms, and the pathologic hallmarks of humoral injury. Treatment options for cellular rejection include high-dose methylprednisolone, antithymocyte globulin, or alemtuzumab. Treatment options for humoral rejection include intravenous immunoglobulin, plasmapheresis, or rituximab. A greater mechanistic understanding of cellular and humoral forms of rejection and their role in the pathogenesis of BOS is critical in developing therapies that extend long-term survival after lung transplantation.

Lung

Experiments with animals in the 1940 and 1950s demonstrated that lung transplantation was technically possible [33]. In 1963, Dr. James Hardy performed the first human lung transplantation. The recipient survived 18 days, ultimately succumbing to renal failure and malnutrition [58]. From 1963 through 1978, multiple attempts at lung transplantation failed because of rejection and complications at the bronchial anastomosis. In the 1980s, improvements in immunosuppression, especially the introduction of cyclosporin A, and enhanced surgical techniques led to renewed interest in organ transplantation. In 1981, a 45-year-old-woman received the first successful heart–lung transplantation for idiopathic pulmonary arterial hypertension (IPAH) [106]. She survived 5 years after the procedure. Two years later the first successful single lung transplantation for idiopathic pulmonary fibrosis (IPF) [128] was reported, and in 1986 the first double lung transplantation for emphysema [25] was performed.

The dynamics and associations of airway neutrophilia post lung transplantation

Bronchoalveolar lavage (BAL) neutrophilia has been repeatedly observed in lung transplant recipients with established bronchiolitis obliterans syndrome (BOS). Little is known of the fluctuations in BAL and airway neutrophilic inflammation post-transplant. This prospective longitudinal study aimed to evaluate the dynamic changes of lung allograft neutrophils with time, immunosuppression, infection and BOS. A total of 28, initially healthy, BOS 0, lung transplant recipients underwent 134 bronchoscopic assessments, including BAL and endobronchial biopsies (EBB) (with immunohistochemistry) over 3-year follow up. Subsequently, 21 developed BOS 0p and 16 ultimately BOS. Compared to controls, there was early and persistent BAL neutrophilia (p < 0.05), contrasting with an initially normal EBB that shows a progressive increased airway wall neutrophil infiltrate. BAL neutrophilia (but not airway wall neutrophilia) was most striking when there was concomitant bronchopulmonary infection, particularly in the patients with BOS. Univariate and multivariate analyses suggested that BAL neutrophilia was linked to markers of infection while EBB neutrophilia was linked with coexistent inflammation with macrophages and lymphocytes.

IN CONCLUSION

(i) BAL neutrophilia is predominantly associated with infection; (ii) Airway wall neutrophilia (as monitored by EBB) increases with time post-transplant and is not associated with infection; (iii) By itself, BOS is not the major contributor to BAL and EBB neutrophilia.

Bronchoalveolar lavage fluid characteristics in acute and chronic lung transplant rejection

BACKGROUND

The detection of graft rejection by bronchoalveolar lavage remains controversial.

METHODS

To assess the value of bronchoalveolar lavage fluid in acute and chronic rejection after lung transplantation we analyzed bronchoalveolar lavage fluid cellular differential characteristics, lymphocyte sub-types and interleukin-6 (IL-6) and interleukin-8 (IL-8) cytokine levels in patients with exclusively either acute rejection (n = 37) or bronchiolitis obliterans (BO; n = 48). Both groups were compared with a control group of lung transplantation patients without rejection or infection, matched for the time the lavage was performed after lung transplantation.

RESULTS

The bronchiolitis obliterans group showed marked neutrophilia, high IL-8 and higher CD4(+)CD25(+) and CD8(+)CD45(+) bronchoalveolar lavage fluid levels when compared with their stable controls. When using a cut-off point of >3% neutrophils in the lavage, the sensitivity for BO is 87.0%, the specificity 77.6%. The sensitivity of IL-8 for BO when using a cut-off point of >71.4 pg/ml is 74.5%, the specificity 83.3%. Bronchoalveolar lavage fluid in acute rejection was characterized by marked lymphocytosis, but showed no difference when compared with stable controls in any of the lymphocyte sub-types studied. When using a cut-off point of <==1% lymphocytes in the lavage, the sensitivity for acute rejection (AR) is 40.4%, the specificity 95.6%. The marked neutrophilia, high IL-8 cytokine level and more activated lymphocyte population in bronchiolitis obliterans may indicate ongoing local allograft rejection.

CONCLUSIONS

In the present study we were not able to show any difference in lymphocyte sub-types when comparing acute rejection and control subjects. Cellular and soluble parameters in bronchoalveolar lavage fluid appear useful for diagnosing bronchiolitis obliterans.

Feasibility of sputum induction in lung transplant recipients

Sputum induction (SI) is nowadays being applied as a non-invasive and safe method to investigate airway inflammation in pulmonary diseases. We investigated the feasibility of SI after lung transplantation (LTX), and compared sputum and bronchoalveolar lavage (BAL) cellular characteristics and interleukin-8 (IL-8) levels. Results were also compared with 11 healthy subjects. SI as performed between 26 and 1947 d after LTX in 19 recipients, was successful in 16 of 22 attempts (73%). Six patients failed to produce sputum after induction, mostly just post-LTX and with having a lower forced expiratory volume in 1 s (FEV1). The success rate in clinically stable patients after the first month post-LTX was 93%. Side-effects were absent. Sputum recovery, viability and squamous cell contamination were comparable between LTX patients and healthy subjects. In the LTX group, total cell counts, neutrophil percentages and IL-8 levels were much higher in SI than BAL (1.6 x 10(6)/mL, 65.5% and 54.2 ng/mL vs. 0.1 x 10(6)/mL, 3.0% and 0.01 ng/mL; p < 0.001). Although LTX-neutrophil percentages in SI and BAL correlated properly (rho=0.72, p=0.04), both techniques are not interchangeable. We conclude that sputum induction is feasible, well tolerated, and without major side-effects in stable patients after the first month post-LTX. Induced sputum may be a useful tool to study inflammatory changes of the airways after LTX, and because of the large quantity of neutrophils sampled, especially for further studies on the pathogenesis of bronchiolitis obliterans.

Bronchoalveolar lavage cytokine profile in a cohort of lung transplant recipients: A predictive role of interleukin-12 with respect to onset of bronchiolitis obliterans syndrome

BACKGROUND

Bronchiolitis obliterans syndrome is the main long-term complication of lung transplantation that limits survival of lung transplant patients. Its pathophysiologic mechanisms are still poorly understood but it seems to result from a chronic immunologic/inflammatory insult leading to excessive fibroproliferation. The aim of this longitudinal study of 44 lung recipients was to determine whether a number of bronchoalveolar lavage and clinical variables are associated with a higher risk of developing bronchiolitis obliterans syndrome.

METHODS

Bronchoalveolar lavage studies involved assessment of several cytokines including: interleukin-8, monocyte chemoattractant protein-1, regulated-upon-activation normal T cell expressed and secreted (RANTES), gamma-interferon, interleukin-12, interleukin-10 and transforming growth factor-beta.

RESULTS

The predictivity of bronchoalveolar lavage (BAL) features with respect to onset of bronchiolitis obliterans syndrome was assessed by the Cox regression model. Among clinical variables, bacterial and viral infections were found to significantly predict occurrence of bronchiolitis obliterans syndrome (hazard ratio [HR] for bacterial infection: 13.044, 95% confidence interval [CI] 1.34 to 126.69, p = 0.027; HR for viral infections: 4.88, 95% CI 1.004 to 22.87, p = 0.05). Among BAL variables, only IL-12 was significantly predictive of bronchiolitis obliterans syndrome (HR 0.956, 95% CI 0.901 to 1.01, p = 0.03). In addition, in a sub-group cross-sectional analysis, bronchiolitis obliterans syndrome patients were compared with clinically stable patients, and significant increases in median levels of interleukin-8 and monocyte chemoattractant protein-1 BAL fluid were detected.

CONCLUSIONS

These findings support the contention that interleukin-12 plays a role in the modulation of the local pro-/anti-fibrotic balance of allograft airways.

Bronchoalveolar lavage in a patient with recurrence of sarcoidosis after lung transplantation

End-stage pulmonary disease due to sarcoidosis rarely leads to lung transplantation. Once a patient has undergone lung transplantation, sarcoidosis often recurs in the lung allograft. In this case report we show, for the first time, the utility of bronchoalveolar lavage fluid in diagnosing the recurrence of sarcoidosis in the transplanted allograft.

The use of multiple transbronchial biopsies as the standard approach to evaluate lung allograft rejection

Flexible bronchoscopy with transbronchial biopsy (TBB) is routinely performed in adult and pediatric lung transplant recipients. The clinical signs and symptoms of acute cellular rejection (ACR) are often identical to those of infection. TBB is a fairly sensitive and specific tool in which to diagnose ACR and can be performed safely in children of all ages. The utility of TBB is unquestioned during periods of worsening clinical symptoms. The utility of TBB for routine surveillance of the allograft remains unproven. The data suggests that during the first 4-6 months post-transplant there is a high incidence of clinically silent ACR. The significance of subclinical rejection in lung transplantation is unknown. Randomized, controlled trials are required to determine if multiple surveillance TBB, can impact the incidence of obliterative bronchiolitis.

Idiopathic chronic cough: association with organ specific autoimmune disease and bronchoalveolar lymphocytosis

BACKGROUND

We have recently reported a strong association between organ specific autoimmune disease and idiopathic chronic cough and have suggested that cough may be caused by airway inflammation secondary to aberrant homing of activated lymphocytes to the lung. An immunopathological study was undertaken to test the hypothesis that idiopathic chronic cough is associated with lymphocytic airway inflammation.

METHODS

Bronchoscopy, bronchial biopsies, bronchoalveolar lavage (BAL), and peripheral blood and BAL flow cytometry were performed in 19 patients with idiopathic chronic cough, 14 with explained chronic cough, and 11 normal subjects.

RESULTS

Organ specific autoimmune disease or positive autoantibodies were present in eight of the 19 patients with idiopathic cough, in one of the 14 patients with explained cough, and in one of the 11 normal subjects. Median BAL fluid differential lymphyocyte counts were significantly higher in patients with idiopathic cough (10.0%) than in normal subjects (6.3%, 95% confidence interval of difference 1.5 to 11.9, p = 0.01) or patients with explained cough (5.2%, 95% CI of difference 2.0 to 10.4, p = 0.001). There were no differences in bronchial biopsy T lymphocyte counts between the groups. The mean (SE) proportion of CD3+ peripheral blood mononuclear cells expressing CD4 was significantly higher in normal subjects than in patients with idiopathic cough (69 (3)% v 58 (3)%, mean difference 11%, 95% CI of difference 2 to 20, p<0.02) but not than those with explained chronic cough (63 (2)%). There were no differences in BAL T lymphocyte phenotype between groups.

CONCLUSION

BAL fluid lymphocytosis occurs in some patients with idiopathic chronic cough. The association of idiopathic chronic cough with organ specific autoimmune disease raises the possibility that this might be caused by lymphocyte homing from the primary site of autoimmune inflammation or the result of an autoimmune process in the lung.

Acute allograft rejection after lung transplantation: diagnosis and therapy

Acute rejection remains a significant problem after lung transplantation. While it generally is a treatable condition, significant resources and therapies are directed toward its prevention and resolution. Its larger significance undoubtedly rests in its contribution to the pathogenesis of BOS. Significant questions regarding the origins of AR, the role of LBB, alternative histologic appearances of acute allograft injury, and optimal therapy remain. Controversy regarding the utility of surveillance bronchoscopy and preemptive treatment of occult AR persists because of lack of conclusive evidence. Future investigations might resolve these matters and provide more efficacious and less toxic therapies that will hopefully reduce the impact of chronic rejection and improve long-term outcomes.

Monocyte chemoattractant protein-1 levels in bronchoalveolar lavage fluid of lung-transplanted patients treated with tacrolimus as rescue treatment for refractory acute rejection

BACKGROUND

Cytokines are important mediators of the complex process of extravasation and influx of peripheral mononuclear cells into a site of graft injury, an action that may be affected by the immunosuppressive regimen. The aim of this study was to compare the effect of different immunosuppressive regimens on cytokine expression in the grafted lung.

METHODS

We analyzed the cytokine profiles in broncho-alveolar lavage fluid (BAL-F) from 18 lung transplanted patients undergoing a shift from a cyclosporine- to a tacrolimus-based triple therapy regimen due to refractory acute rejection.

RESULTS

Three months after the conversion to tacrolimus, BAL-F levels of interleukin 8 (IL8), IL18, IL12 and IL10 were not significantly different than those measured before conversion. In contrast, monocyte chemoattractant protein-1 (MCP-1) levels showed a significant and sustained decrease in BAL-F during tacrolimus therapy. In addition the levels of gamma interferon (IFN-gamma) in the BAL-F were decreased albeit not significantly.

CONCLUSIONS

These findings suggest that the clinical and functional stabilization of patients observed after conversion to a tacrolimus based regimen, may be due, at least in part, to the induced down-regulation of MCP-1 production.

Sputum matrix metalloproteinase-9, tissue inhibitor of metalloprotinease-1, and their molar ratio in patients with chronic obstructive pulmonary disease, idiopathic pulmonary fibrosis and healthy subjects

BACKGROUND

Matrix-metalloproteinases (MMPs) and their inhibitors, the tissue inhibitors of metalloproteinases (TIMPs), are involved in the turnover of extracellular matrix. Chronic obstructive pulmonary disease (COPD) and idiopathic pulmonary fibrosis (IPF) are inflammatory diseases characterized by excessive matrix degradation and tissue fibrosis. We have compared sputum concentrations of MMP-9, TIMP-1 and the controlling cytokine tumor necrosis factor (TNF)-alpha in patients with COPD, IPF and healthy subjects.

METHODS

In a cross-sectional analysis, 12 patients with stable COPD, 15 patients with IPF and 14 healthy subjects underwent sputum induction. Induced sputum cells were counted and concentrations of MMP-9, TIMP-1 and TNF were measured by enzyme immunoassays.

RESULTS

Sputum neutrophils were markedly elevated in COPD and IPF patients compared with controls (P<0.001, both comparisons). Concentrations of MMP-9 and the MMP-9:TIMP-1 ratio were increased in COPD (P<0.001 vs. IPF and controls), whereas sputum TIMP-1 levels were both elevated in COPD and IPF (P<0.01 vs. controls, both comparisons). TNF levels were similar in all three groups (P>0.2, all comparisons). MMP-9 concentrations were negatively correlated with airway obstruction (FEV1 FVC) in COPD (rho=-0.62, P=0.03), but not with diffusion capacity or vital capacity (% predicted) in IPF (rho=-0.06, P=0.85, and rho=-0.3, P=0.29, respectively). MMP-9 was positively correlated with sputum neutrophils in all patients (rho=0.68, P<0.0001), and with TNF in COPD patients (rho=0.76, P=0.004).

CONCLUSIONS

These data underline the significance of protease/antiprotease imbalance for the pathogenesis of inflammatory lung diseases. Despite similar cellular inflammatory patterns both in COPD and IPF sputa, marked differences were observed with regard to MMP-9:TIMP-1 balance.

Determination of bronchoalveolar lavage leukocyte populations by flow cytometry in patients investigated for respiratory disease

BACKGROUND

Characteristic changes in the proportions of leukocyte populations in bronchoalveolar lavage (BAL) reflect different disease states in the lung. The standard method for examination of BAL leukocytes is by microscopy of cytospin preparations. This method may not be the optimum technique due to difficulties in distinguishing cell types morphologically and due to the low number of cells routinely counted. We hypothesized that flow cytometry (FCM) may be a more precise tool for investigating BAL.

METHODS

100 BALs were performed on 92 patients. All samples were stained using the pan-leukocyte marker (CD45) in combination with a granulocyte marker (CD15) and a cell viability marker (7-aminoactinomycin D). Selected samples were also stained with an eosinophil marker (CD23). These samples were run on an FCM and the results compared with leukocyte differentials obtained by light microscopy of parallel cytospin preparations.

RESULTS

Close correlations between the two methods were demonstrated for the enumeration of all leukocyte subsets, but the coefficient of variation was considerably lower by FCM than by cytospin.

CONCLUSIONS

These findings, combined with the speed of FCM and the ability to perform simple lymphocyte phenotyping, argue in favor of this becoming the method of choice for investigating BAL.

Interleukin-6 and interferon-gamma gene polymorphisms in the development of bronchiolitis obliterans syndrome after lung transplantation

BACKGROUND

A number of genetic polymorphisms have been shown to regulate the production and secretion of tumor necrosis factor (TNF)-alpha, transforming growth factor (TGF)-beta1, interferon (IFN)-gamma, interleukin (IL)-6, and IL-10. Several of these genetic polymorphisms have been shown to be associated with either acute or chronic rejection of kidney, liver, and heart allografts and with development of allograft fibrosis after lung transplantation. The aim of this study was to assess the effect of these genetic polymorphisms on the development of bronchiolitis obliterans syndrome (BOS) after lung transplantation.

METHODS

Genetic polymorphisms were detected by means of polymerase chain reaction in 93 lung allograft recipients for functional polymorphisms in the TNF-alpha (-308), TGF-beta1 (+869 and +915), IL-6 (-174), IFN-gamma (+874), and IL-10 (-1082, -819, and -592) genes. Then, a correlation between BOS development and the presence of these cytokine genotypes was determined using Kaplan-Meier actuarial analysis.

RESULTS

A significant correlation was detected between the presence of high-expression polymorphisms of the IL-6 and IFN-gamma genes and BOS development after lung transplantation (P =0.045 and 0.039, respectively). Also, patients with high-expression polymorphisms in both genes developed BOS significantly earlier than patients with low-expression polymorphisms in one or both genes, suggesting a synergistic effect of the alleles during BOS pathogenesis (P =0.016). No correlation was detected between polymorphisms of the TNF-alpha, TGF-beta1, and IL-10 genes and development of BOS after lung transplantation.

CONCLUSIONS

The presence of high-expression polymorphisms at position -174 of the IL-6 gene and position +874 of the IFN-gamma gene significantly increases the risk for BOS development after lung transplantation.

Database of bronchoalveolar lavage fluid proteins

Bronchoalveolar lavage during fiberoptic bronchoscopy is extensively used for investigating cellular and biochemical alterations of the epithelial lining fluid in various lung disorders. Two-dimensional electrophoresis (2-DE) offers the possibility to simultaneously display and analyze proteins contained in bronchoalveolar lavage fluid (BALF). We present the current status of 2-DE of BALF samples with an updated listing of the proteins already identified and of their level and/or posttranslational alterations in lung disorders. Alternatives to 2-DE of BALF samples and future prospects of proteomics to unravel lung functions and pathologies are discussed.

Longitudinal profile of bronchoalveolar lavage cell characteristics in patients with a good outcome after lung transplantation

Bronchoalveolar lavage fluid (BALF) analysis is used in patients after lung transplantation (LTX) to obtain more insight into pathological conditions such as acute and chronic allograft rejection. Information on the normal course of BALF cell characteristics in patients with "good outcome" after LTX is limited. Therefore we analyzed 169 BALF samples from 63 well-defined "good outcome" patients after LTX (no acute or chronic transplant dysfunction, bacterial, fungal, or viral infections at the time of BAL). Total cell count decreased from the first months: median (range) 234 x 10(3) (70-610) cells/ml to 103 x 10(3) (10-840) cells/ml during the second year posttransplantation (p < 0.001). Cell differential counts did not change during the 2-yr study period. The CD4/CD8 ratio increased significantly from 0.32 (0.11-0.46) just posttransplantation to 0.62 (0.16-4.27) the second year after LTX. This increasing ratio was mainly due to a sharp decreasing CD8(+) cell count. Thus, characteristics of BAL cellular patterns in patients with good outcomes after LTX show important changes over time. We have defined control values for the BALF cellular profile in patients without pathological airway conditions after LTX. We propose to use these control values as a tool for diagnosing patients with pulmonary complications after LTX and for the follow-up of treatment regimens.

Inflammation in lung transplantation for CF. Immunosuppression and modulation of inflammation

Lung transplantation is an accepted therapy for selected individuals with end-stage lung disease due to cystic fibrosis (CF). Recent data show that CF recipients of lung transplantation have survival as good as those of any other diagnostic group. After transplantation, CF patients confront the major threats to life and health of graft infection and rejection. Inflammation is the common mediator of injury to the lung in both these instances. Graft infection after lung transplantation involves the same micro-organisms as are typical with CF as well as opportunistic agents. Prophylactic strategies and aggressive diagnosis via bronchoscopy are both critical in the effective treatment of post-transplant lung infections. Graft rejection involves the detection and recognition of foreign antigen and the subsequent activation of specific T-lymphocyte clones leading to inflammatory injury to the donor organ. Immunosuppression is used to prevent and/or modulate host response to the donor organ and titrated to serum therapeutic drug monitoring and transbronchial biopsy findings. Precise clinical monitoring and aggressive diagnostic approaches are crucial to minimizing graft injury and enhancing life after transplantation. Although most CF lung transplant recipients experience both graft infection and rejection and the 5-yr survival rate remains at approx 50%, improvement in diagnosis and therapy continue over time. With the introduction of new approaches to antimicrobial therapy, new immunosuppressant agents and promising strategies to promote immune tolerance, survival after lung transplantation is likely to improve in the coming decades.

Induced sputum cell profiles in lung transplant recipients with or without chronic rejection: correlation with lung function

BACKGROUND

Sputum induction is a non-invasive procedure for measuring inflammatory processes of the lower respiratory tract. The aim of this study was to establish sputum cell counts and differentials in patients after lung transplantation (LTx), with or without chronic transplant rejection.

METHODS

Sputum induction was performed in 41 LTx patients (25 single LTx (sLTx), 16 double LTx (dLTx) and 15 healthy non-smoking volunteers. Sputum was processed according to standard protocols. Total cell count was calculated as mean (SE) cells x 10(6)/ml sputum and cell differential (%) was evaluated after staining. Cellular profiles were correlated with lung function.

RESULTS

Total sputum cell counts were increased in sLTx (9 (1.9) cells x 10(6)/ml, p=0.01) and dLTx patients (7.2 (1.5) x 10(6)/ml, p=0.01) compared with healthy controls (2.6 (0.6) x 10(6)/ml). There was also a marked sputum neutrophilia in both patient groups (59 (6)% and 62 (6)%, respectively, p<0.001 v controls). Moreover, in both sLTx and dLTx patients with chronic transplant rejection there was an increased number of sputum neutrophils compared with patients with normal graft function (p<0.05 both comparisons), and neutrophils were inversely correlated with lung function (forced expiratory volume in one second (FEV(1)) % predicted): sLTx, r=-0.61, p=0.001; dLTx, r=-0.75, p=0.001, respectively). Sputum lymphocytes and eosinophils were similar in both groups. No relevant side effects occurred during sputum induction.

CONCLUSIONS

Sputum induction is a safe and non-invasive tool for monitoring lower respiratory tract inflammation in LTx patients. Both sLTx and dLTx patients with chronic rejection had increased sputum neutrophils compared with patients with normal transplant function. These data support findings of other authors highlighting a possible role for neutrophils in the pathogenesis of chronic transplant rejection.

Induced sputum cell profiles in lung transplant recipients with or without chronic rejection: correlation with lung function

BACKGROUND

Sputum induction is a non-invasive procedure for measuring inflammatory processes of the lower respiratory tract. The aim of this study was to establish sputum cell counts and differentials in patients after lung transplantation (LTx), with or without chronic transplant rejection.

METHODS

Sputum induction was performed in 41 LTx patients (25 single LTx (sLTx), 16 double LTx (dLTx) and 15 healthy non-smoking volunteers. Sputum was processed according to standard protocols. Total cell count was calculated as mean (SE) cells × 106/ml sputum and cell differential (%) was evaluated after staining. Cellular profiles were correlated with lung function.

RESULTS

Total sputum cell counts were increased in sLTx (9 (1.9) cells × 106/ml, p=0.01) and dLTx patients (7.2 (1.5) × 106/ml, p=0.01) compared with healthy controls (2.6 (0.6) × 106/ml). There was also a marked sputum neutrophilia in both patient groups (59 (6)% and 62 (6)%, respectively, p<0.001v controls). Moreover, in both sLTx and dLTx patients with chronic transplant rejection there was an increased number of sputum neutrophils compared with patients with normal graft function (p<0.05 both comparisons), and neutrophils were inversely correlated with lung function (forced expiratory volume in one second (FEV1) % predicted): sLTx,r=–0.61, p=0.001; dLTx,r=–0.75, p=0.001, respectively). Sputum lymphocytes and eosinophils were similar in both groups. No relevant side effects occurred during sputum induction.

CONCLUSIONS

Sputum induction is a safe and non-invasive tool for monitoring lower respiratory tract inflammation in LTx patients. Both sLTx and dLTx patients with chronic rejection had increased sputum neutrophils compared with patients with normal transplant function. These data support findings of other authors highlighting a possible role for neutrophils in the pathogenesis of chronic transplant rejection.

Cxcr3 and its ligand CXCL10 are expressed by inflammatory cells infiltrating lung allografts and mediate chemotaxis of T cells at sites of rejection

The attraction of T lymphocytes into the pulmonary parenchyma represents an essential step in mechanisms ultimately leading to lung allograft rejection. In this study we evaluated whether IP-10 (CXCL10), a chemokine that is induced by interferon-gamma and stimulates the directional migration of activated T cells, plays a role in regulating the trafficking of effector T cells during lung allograft rejection episodes. Immunohistochemical examination showed that areas characterized by acute cellular rejection (grades 1 to 4) and active obliterative bronchiolitis (chronic rejection, Ca) were infiltrated by T cells expressing CXCR3, i.e., the specific receptor for CXCL10. In parallel, T cells accumulating in the bronchoalveolar lavage of lung transplant recipients with rejection episodes were CXCR3+ and exhibited a strong in vitro migratory capability in response to CXCL10. In lung biopsies, CXCL10 was abundantly expressed by graft-infiltrating macrophages and occasionally by epithelial cells. Alveolar macrophages expressed and secreted definite levels of CXCL10 capable of inducing chemotaxis of the CXCR3+ T-cell line 300-19; the secretory capability of alveolar macrophages was up-regulated by preincubation with interferon-gamma. Interestingly, striking levels of CXCR3 ligands could be demonstrated in the fluid component of the bronchoalveolar lavage in individuals with rejection episodes. These data indicate the role of the CXCR3/CXCL10 interactions in the recruitment of lymphocytes at sites of lung rejection and provide a rationale for the use of agents that block the CXCR3/CXCL10 axis in the treatment of lung allograft rejection.

Eosinophilic granulocytes and interleukin-6 level in bronchoalveolar lavage fluid are associated with the development of obliterative bronchiolitis after lung transplantation

In a prospective cohort study, we assessed whether changes in total cell counts and differentiation and interleukin-6 (IL-6), IL-8, and monocyte chemoattractant protein-1 (MCP-1) concentrations in bronchoalveolar lavage fluid (BALF) are associated with a higher risk to develop obliterative bronchiolitis (OB). We investigated 60 lung transplant patients (follow-up of 2 to 8 yr) with either histologic evidence of OB within 1 yr after lung transplantation (n = 19) or no pathology, good outcome (GO) for at least 24 mo and well-preserved lung function, i.e., FEV > or = 80% of baseline (n = 41). Median time between lung transplantation and the first BAL was 42 d for the GO group and 41 d for the OB group (p > 0.05). In the bronchial fraction, median total cell counts (0.06 x 10(3)/ml versus 0.04 x 10(3)/ml), lymphocyte (9 x 10(3)/ml versus 2 x 10(3)/ml), and eosinophilic granulocyte counts (1 x 10(3)/ml versus 0) were significantly higher in the OB group than in the GO group (p < 0.05). In the alveolar fraction, this was the case for the median value of neutrophilic granulocyte counts (19 x 10(3)/ml versus 4 x 10(3)/ml), respectively. Median values of IL-6 and IL-8 concentrations in both bronchial (IL-6: 23 versus 6 pg/ml, IL-8: 744 versus 102 pg/ml) and alveolar fractions (IL-6: 13 versus 3 pg/ml, IL-8: 110 versus 30 pg/ml) of the BALF were significantly higher in the OB group than in the GO group. By means of logistic regression, we showed that higher total cell, neutrophilic granulocyte, and lymphocyte counts, the presence of eosinophilic granulocytes, and higher concentrations of IL-6 and IL-8 were significantly associated with an increased risk to develop OB. We conclude that monitoring cell counts, neutrophilic and eosinophilic granulocytes, IL-6, and IL-8 in BALF within 2 mo after lung transplantation in addition to the transbronchial lung biopsy (TBB) pathology will contribute to a better identification and management of the group of patients at risk for developing OB within a year.