Decreased serum and bronchoalveolar lavage levels of Clara cell secretory protein (CC16) is associated with bronchiolitis obliterans syndrome and airway neutrophilia in lung transplant recipients

Donor IL-17 receptor A regulates LPS-potentiated acute and chronic murine lung allograft rejection

Chronic lung allograft dysfunction (CLAD) is a major complication after lung transplantation that results from a complex interplay of innate inflammatory and alloimmune factors, culminating in parenchymal and/or obliterative airway fibrosis. Excessive IL-17A signaling and chronic inflammation have been recognized as key factors in these pathological processes. Herein, we developed a model of repeated airway inflammation in mouse minor alloantigen-mismatched single-lung transplantation. Repeated intratracheal LPS instillations augmented pulmonary IL-17A expression. LPS also increased acute rejection, airway epithelial damage, and obliterative airway fibrosis, similar to human explanted lung allografts with antecedent episodes of airway infection. We then investigated the role of donor and recipient IL-17 receptor A (IL-17RA) in this context. Donor IL-17RA deficiency significantly attenuated acute rejection and CLAD features, whereas recipient IL-17RA deficiency only slightly reduced airway obliteration in LPS allografts. IL-17RA immunofluorescence positive staining was greater in human CLAD lungs compared with control human lung specimens, with localization to fibroblasts and myofibroblasts, which was also seen in mouse LPS allografts. Taken together, repeated airway inflammation after lung transplantation caused local airway epithelial damage, with persistent elevation of IL-17A and IL-17RA expression and particular involvement of IL-17RA on donor structural cells in development of fibrosis.

Pulmonary epithelial markers in phenotypes of chronic lung allograft dysfunction

BACKGROUND

Airway epithelial injury is thought to be a key event in the pathogenesis of chronic lung allograft dysfunction (CLAD). We investigated whether markers of epithelial activity and injury in bronchoalveolar lavage fluid (BAL) correlate with CLAD diagnosis and major CLAD phenotypes: bronchiolitis obliterans syndrome (BOS) vs restrictive allograft syndrome (RAS)-related phenotypes (including RAS, mixed phenotype, and all other patients with RAS-like opacities).

METHODS

CLAD status and phenotypes were retrospectively determined in a cohort of all consecutive adult, first, bilateral lung transplants performed 2010-2015, with available BAL samples. All patients with RAS-related phenotypes were included and 1:1 matched with BOS patients based on the time from transplant to CLAD-onset. Subjects who were CLAD-free for a minimum of 3 years post-transplant were 1:1 matched to CLAD patients and included as controls. Proteins that maintain the barrier function of the airway epithelial mucosa (club cell secretory protein, surfactant protein-D and epithelial mucins: MUC1, MUC5AC, MUC5B, MUC16), as well as epithelial cell death markers (M30&M65 representing epithelial cell apoptosis and overall death, respectively), were measured in BAL obtained within 6-months post CLAD onset using a double-sandwich ELISA or a multiplex bead assay. Protein levels were compared using Mann-Whitney-U-test. Association between protein levels and graft survival was assessed using Cox proportional hazards models, adjusted for CMV serology mismatch status and CLAD phenotype.

RESULTS

Fifty-four CLAD (27 BOS, 11 RAS, 7 mixed, 9 others with RAS-like opacities) patients and 23 CLAD-free controls were included. Median BAL levels were significantly higher in patients with CLAD compared to CLAD-free controls for M30 (124.5 vs 88.7 U/L), MUC1 (6.8 vs 3.2 pg/mL), and MUC16 (121.0 vs 30.1 pg/mL). When comparing CLAD phenotypes, M30 was significantly higher in patients with RAS-related phenotypes than BOS (160.9 vs 114.6 U/L). In multivariable models, higher M30 and MUC5B levels were associated with decreased allograft survival after CLAD onset independent of phenotype (p < 0.05 for all).

CONCLUSIONS

Airway epithelial mucins and cell death markers are enhanced in the BAL of patients with CLAD and can assist in differentiating between CLAD phenotypes and post-CLAD outcomes. Abnormal airway mucin expression and epithelial cell death may be involved in the pathogenesis of CLAD, and therefore their detection may aid in future selection of targeted therapies.

Early posttransplant reductions in club cell secretory protein associate with future risk for chronic allograft dysfunction in lung recipients: results from a multicenter study

BACKGROUND

Chronic lung allograft dysfunction (CLAD) increases morbidity and mortality for lung transplant recipients. Club cell secretory protein (CCSP), produced by airway club cells, is reduced in the bronchoalveolar lavage fluid (BALF) of lung recipients with CLAD. We sought to understand the relationship between BALF CCSP and early posttransplant allograft injury and determine if early posttransplant BALF CCSP reductions indicate later CLAD risk.

METHODS

We quantified CCSP and total protein in 1606 BALF samples collected over the first posttransplant year from 392 adult lung recipients at 5 centers. Generalized estimating equation models were used to examine the correlation of allograft histology or infection events with protein-normalized BALF CCSP. We performed multivariable Cox regression to determine the association between a time-dependent binary indicator of normalized BALF CCSP level below the median in the first posttransplant year and development of probable CLAD.

RESULTS

Normalized BALF CCSP concentrations were 19% to 48% lower among samples corresponding to histological allograft injury as compared with healthy samples. Patients who experienced any occurrence of a normalized BALF CCSP level below the median over the first posttransplant year had a significant increase in probable CLAD risk independent of other factors previously linked to CLAD (adjusted hazard ratio 1.95; p = 0.035).

CONCLUSIONS

We discovered a threshold for reduced BALF CCSP to discriminate future CLAD risk; supporting the utility of BALF CCSP as a tool for early posttransplant risk stratification. Additionally, our finding that low CCSP associates with future CLAD underscores a role for club cell injury in CLAD pathobiology.

Levels of Clara cell secretory protein and surfactant protein A in municipal solid waste management workers in Ibadan, Southwest Nigeria

Toxic pneumonitis and related respiratory symptoms are common among waste management workers (WMWs). Products of different cellular responses following exposure to toxic components of wastes can lead to the production of a variety of biomolecules. There is a growing recognition of the importance of biomarkers in risk assessment and a strong advocacy for their determination and use as indicators of health and safety. This study assessed the prevalence of respiratory symptoms and the relevance of pulmonary surfactant protein A (SP-A) and Clara cell 16 protein (CC16) as indicators of occupational inhalation exposure to toxic substances and irritants in WMW. A total of 172 subjects consisting of 112 WMWs and 60 Non-WMWs were recruited by purposive sampling. Data on socio-economic and work-related symptoms were collected using structured questionnaire. CC16 and SP-A were determined by ELISA in serum samples. Clinical history reveals a slightly higher prevalence of respiratory symptoms in WMWs relative to control subjects. Increased permeability of the lung-blood barrier, characterized by significant elevation of serum SP-A and serum CC16, was associated with respiratory symptoms in WMWs. Steady increases in SP-A and CC16, respectively, in relation to occupational duration were observed in WMWs relative to control. Receiver operating characteristic curve and multivariate analyses revealed SP-A and CC16 as important lung biomarkers for assessing sub-clinical effects of occupational exposure. Our data suggest SP-A and CC16 may be relevant indicators for assessing occupational inhalation exposure to toxic substances and irritants among WMWs.

Club Cell Secretory Protein in Lung Disease: Emerging Concepts and Potential Therapeutics

Club cell secretory protein (CCSP), also known as secretoglobin 1A1 (gene name SCGB1A1), is one of the most abundant proteins in the lung, primarily produced by club cells of the distal airway epithelium. At baseline, CCSP is found in large concentrations in lung fluid specimens and can also be detected in the blood and urine. Obstructive lung diseases are generally associated with reduced CCSP levels, thought to be due to decreased CCSP production or club cell depletion. Conversely, several restrictive lung diseases have been found to have increased CCSP levels both in the lung and in the circulation, likely related to club cell dysregulation as well as increasedlung permeability. Recent studies demonstrate multiple mechanisms by which CCSP dampens acute and chronic lung inflammation. Given these anti-inflammatory effects, CCSP represents a novel potential therapeutic modality in lung disease.

Airway secretory cell fate conversion via YAP-mTORC1-dependent essential amino acid metabolism

Tissue homeostasis requires lineage fidelity of stem cells. Dysregulation of cell fate specification and differentiation leads to various diseases, yet the cellular and molecular mechanisms governing these processes remain elusive. We demonstrate that YAP/TAZ activation reprograms airway secretory cells, which subsequently lose their cellular identity and acquire squamous alveolar type 1 (AT1) fate in the lung. This cell fate conversion is mediated via distinctive transitional cell states of damage-associated transient progenitors (DATPs), recently shown to emerge during injury repair in mouse and human lungs. We further describe a YAP/TAZ signaling cascade to be integral for the fate conversion of secretory cells into AT1 fate, by modulating mTORC1/ATF4-mediated amino acid metabolism in vivo. Importantly, we observed aberrant activation of the YAP/TAZ-mTORC1-ATF4 axis in the altered airway epithelium of bronchiolitis obliterans syndrome, including substantial emergence of DATPs and AT1 cells with severe pulmonary fibrosis. Genetic and pharmacologic inhibition of mTORC1 activity suppresses lineage alteration and subepithelial fibrosis driven by YAP/TAZ activation, proposing a potential therapeutic target for human fibrotic lung diseases.

Club Cell Protein, CC10, Attenuates Acute Respiratory Distress Syndrome Induced by Smoke Inhalation

OBJECTIVES

To evaluate the dose effects of Recombinant human Club cell 10-kDa protein (rhCC10) on lung function in a well-characterized ovine model of acute respiratory distress syndrome (ARDS) induced by smoke inhalation injury (SII); specifically, the potential of rhCC10 protein to control the inflammatory response and protect pulmonary tissue and function following SII.

DESIGN

Randomized, controlled, prospective, and large animal translational studies.

SETTING

University large animal intensive care unit.

SUBJECTS

Thirty-six adult female sheep were surgically prepared and allocated into five groups (Sham (no SII), n = 6; 1 mg/kg/d CC10, n = 8; 3 mg/kg/d CC10, n = 7; 10 mg/kg/d CC10, n = 8; Control SII, n = 7).

INTERVENTIONS

All groups except the sham group were subjected to SII with cooled cotton smoke. Then, the animals were placed on a ventilator, treated with 1, 3, and 10 mg/kg/d of intravenous rhCC10 or vehicle, divided evenly into two administrations per day every 12 h, fluid resuscitated, and monitored for 48 h in a conscious state.

MEASUREMENTS AND MAIN RESULTS

The group treated with 10 mg/kg/d rhCC10 attenuated changes in the following variables: PaO2/FiO2 ratio, oxygenation index, and peak inspiratory pressure; neutrophil content in the airway and myeloperoxidase levels; obstruction of the large and small airways; systemic leakage of fluid and proteins, and pulmonary edema.

CONCLUSIONS

In this study, high-dose rhCC10 significantly attenuated ARDS progression and lung dysfunction and significantly reduced systemic extravasation of fluid and proteins, normalizing fluid balance. Based on these results, rhCC10 may be considered a novel therapeutic option for the treatment of SII-induced ARDS.

Decline in Club Cell Secretory Proteins, Exosomes Induction and Immune Responses to Lung Self-antigens, Kα1 Tubulin and Collagen V, Leading to Chronic Rejection After Human Lung Transplantation

BACKGROUND

Chronic lung allograft dysfunction (CLAD), is a major hurdle for long-term lung allograft survival after lung transplant and roughly 50% of lung transplant recipients (LTxRs) develop CLAD within 5 years. The mechanisms of CLAD development remain unknown. Donor-specific immune responses to HLA and lung self-antigens (SAgs) are vital to the pathogenesis of CLAD. Reduction in Club cell secretory protein (CCSP) has been reported in bronchoalveolar lavage (BAL) fluid samples from LTxRs with bronchiolitis obliterans syndrome (BOS). CCSP levels in BAL fluid and development of antibodies to lung SAgs in plasma were determined by ELISA. Cytokines in BAL fluid were analyzed by 30-plex Luminex panel. Exosomes from BAL fluid or plasma were analyzed for SAgs, natural killer (NK) cells markers, and cytotoxic molecules.

RESULTS

We demonstrate that LTxRs with BOS have lower CCSP levels up to 9 months before BOS diagnosis. LTxRs with antibodies to SAgs 1-year posttransplant also developed DSA (43%) and had lower CCSP. BOS with lower CCSP also induced Interleukin-8 and reduced vascular endothelial growth factor. Exosomes from BOS contained increased SAgs, NK cells markers, and cytotoxic molecules.

CONCLUSIONS

We conclude lower CCSP leads to inflammation, pro-inflammatory cytokine production, immune responses to HLA and SAgs, and induction of exosomes. For the first time, we demonstrate that CCSP loss results in exosome release from NK cells capable of stimulating innate and adaptive immunity posttransplant. This increases the risk of BOS, suggesting a role of NK cell exosomes in CLAD development.

[Predictors for the Bronchiolitis Obliterans Syndrome in Lung Transplant Patient]

肺移植是治疗终末期肺病的有效方法。目前，肺移植术后1年生存率已达到80%，由于闭塞性细支气管炎综合症（bronchiolitis obliterans syndrome, BOS）的发生，5年生存率维持在50%左右。BOS是一个纤维化的过程，最终导致不可逆的气道闭塞。缺血-再灌注损伤、感染、氧化应激以及急性排斥反应等多个因素参与了BOS的发生。研究证实BOS的早期诊断与预后良好相关。因此，寻找灵敏、特异的BOS预测标记物对于提高肺移植患者长期生存具有重要的科学和临床意义。本文就与BOS发生发展相关的免疫调节细胞、分泌性蛋白质、细胞膜蛋白等指标的变化在BOS早期诊断中的作用进行综述。

An obligatory role for club cells in preventing obliterative bronchiolitis in lung transplants

Obliterative bronchiolitis (OB) is a poorly understood airway disease characterized by the generation of fibrotic bronchiolar occlusions. In the lung transplant setting, OB is a pathological manifestation of bronchiolitis obliterans syndrome (BOS), which is a major impediment to long-term recipient survival. Club cells play a key role in bronchiolar epithelial repair, but whether they promote lung transplant tolerance through preventing OB remains unclear. We determined if OB occurs in mouse orthotopic lung transplants following conditional transgene-targeted club cell depletion. In syngeneic lung transplants club cell depletion leads to transient epithelial injury followed by rapid club cell-mediated repair. In contrast, allogeneic lung transplants develop severe OB lesions and poorly regenerate club cells despite immunosuppression treatment. Lung allograft club cell ablation also triggers the recognition of alloantigens, and pulmonary restricted self-antigens reported associated with BOS development. However, CD8+ T cell depletion restores club cell reparative responses and prevents OB. In addition, ex-vivo analysis reveals a specific role for alloantigen-primed effector CD8+ T cells in preventing club cell proliferation and maintenance. Taken together, we demonstrate a vital role for club cells in maintaining lung transplant tolerance and propose a new model to identify the underlying mechanisms of OB.

Better therapeutic potential of bone marrow-derived mesenchymal stem cells compared with chorionic villi-derived mesenchymal stem cells in airway injury model

Aim: To determine the efficiency of mesenchymal stem cells (MSCs) of different sources on airway epithelial cells regeneration and track where and to what extent transplanted MSCs home to injured tissues. Materials & methods: We performed DiO-labeled human bone marrow-derived MSCs (hBMSCs) or human chorionic villi-derived MSCs transplantation studies using naphthalene-induced airway injury animal models. Results: Compared with human chorionic villi-derived MSCs, hBMSCs facilitated airway epithelium regeneration faster and better from day 5 after transplantation; moreover, more transplanted hBMSCs distributed in injured lung tissues at the early stage of postinjury, which was mediated by C-X-C motif chemokine ligand 12. Conclusion: hBMSCs possessed better potential of migration to the damaged lung and promoting the repair of the injured airway epithelium.

Inhibition of B cell-dependent lymphoid follicle formation prevents lymphocytic bronchiolitis after lung transplantation

Lung transplantation (LTx) is the only therapeutic option for many patients with chronic lung disease. However, long-term survival after LTx is severely compromised by chronic rejection (chronic lung allograft dysfunction [CLAD]), which affects 50% of recipients after 5 years. The underlying mechanisms for CLAD are poorly understood, largely due to a lack of clinically relevant animal models, but lymphocytic bronchiolitis is an early sign of CLAD. Here, we report that lymphocytic bronchiolitis occurs early in a long-term murine orthotopic LTx model, based on a single mismatch (grafts from HLA-A2:B6-knockin donors transplanted into B6 recipients). Lymphocytic bronchiolitis is followed by formation of B cell-dependent lymphoid follicles that induce adjacent bronchial epithelial cell dysfunction in a spatiotemporal fashion. B cell deficiency using recipient μMT-/- mice prevented intrapulmonary lymphoid follicle formation and lymphocytic bronchiolitis. Importantly, selective inhibition of the follicle-organizing receptor EBI2, using genetic deletion or pharmacologic inhibition, prevented functional and histological deterioration of mismatched lung grafts. In sum, we provided what we believe to be a mouse model of chronic rejection and lymphocytic bronchiolitis after LTx and identified intrapulmonary lymphoid follicle formation as a target for pharmacological intervention of long-term allograft dysfunction after LTx.

Sequential broncho-alveolar lavages reflect distinct pulmonary compartments: clinical and research implications in lung transplantation

Background

Bronchoalveolar lavage (BAL) has proven to be very useful to monitor the lung allograft after transplantation. In addition to allowing detection of infections, multiple BAL analytes have been proposed as potential biomarkers of lung allograft rejection or dysfunction. However, BAL collection is not well standardized and differences in BAL collection represent an important source of variation. We hypothesized that there are systematic differences between sequential BALs that are relevant to BAL analysis.

Methods

As part of 126 consecutive bronchoscopies in lung transplant recipients, two sequential BALs (BAL1 and BAL2) were performed in one location during each bronchoscopy by instilling and suctioning 50 ml of normal saline twice into separate containers. Cell concentration, viability and differentials, Surfactant Protein-D (SP-D), Club Cell Secretory Protein (CCSP), and levels of CXCL10, IL-10, CCL2, CCL5, VEGF-C, RAGE, CXCL9, CXCL1, IL-17A, IL-21, PDGF, and GCSF were compared between BAL1 and BAL2.

Results

Total cell concentration did not differ between BAL1 and BAL2; however, compared to BAL2, BAL1 had more dead cells, epithelial cells, neutrophils, and higher concentrations of airway epithelium-derived CCSP and inflammatory markers. BAL2 had a higher concentration of SP-D compared to BAL1.

Conclusion

In this study performed in lung transplant recipients, we show that sequential BALs represent different lung compartments and have distinct compositions. BAL1 represents the airway compartment with more epithelial cells, neutrophils, and epithelium-derived CCSP. Conversely, BAL2 samples preferentially the distal bronchoalveolar space with greater cell viability and higher SP-D. Our findings illustrate how the method of BAL collection can influence analyte concentrations and further emphasize the need for a standardized approach in translational research involving BAL samples.

Electronic supplementary material

The online version of this article (10.1186/s12931-018-0786-z) contains supplementary material, which is available to authorized users.

Donor Club Cell Secretory Protein G38A Polymorphism Is Associated With a Decreased Risk of Primary Graft Dysfunction in the French Cohort in Lung Transplantation

BACKGROUND

Club Cell Secretory Protein (CCSP) G38A polymorphism has recently been involved in lung epithelial susceptibility to external injuries. Lung transplantation (LT) is currently limited by ischemia-reperfusion injury leading to primary graft dysfunction (PGD). We thus hypothesized that donor CCSP G38A polymorphism might impact the risk of PGD after LT.

METHODS

We focused on LT included in the French multicentric Cohort in Lung Transplantation (COLT), performed between January 2009 and December 2014, and associated with preoperative blood samples from the donor and the recipient. Characteristics of the donors, recipients, procedures, early and late outcomes were prospectively recorded in COLT. The CCSP serum concentration and CCSP gene G38A polymorphism were retrospectively determined in a blind manner. Their association with grade 3 PGD was studied in univariate and multivariate analysis.

RESULTS

The study group included 104 LT donors and recipients, 84 with grade 0 to 2 PGD and 20 with grade 3 PGD. Preoperative CCSP serum concentration was significantly higher in the donors (median, 22.54 ng/mL; interquartile range, 9.6-43.9) than in the recipients (median, 7.03 ng/mL; interquartile range, 0.89-19.2; P < 0.001) but none impacted the risk of grade 3 PGD (P = 0.93 and P = 0.69, respectively). Donor CCSP G38A polymorphism was associated with a decreased risk of grade 3 PGD in univariate (AG + AA 3/21 = 14.2% vs GG 10/26 = 38.4%, P = 0.044) and multivariate analysis (odds ratio associated with AG + AA, 0.22; 95% confidence interval, 0.041-0.88; P = 0.045), but recipient CCSP G38A polymorphism was not.

CONCLUSIONS

Donor CCSP G38A polymorphism is associated with a decreased risk of severe PGD after LT in the COLT study. These findings should be confirmed in the frame of a prospective study.

Accumulation of Ubiquitin and Sequestosome-1 Implicate Protein Damage in Diacetyl-Induced Cytotoxicity

Inhaled diacetyl vapors are associated with flavorings-related lung disease, a potentially fatal airway disease. The reactive α-dicarbonyl group in diacetyl causes protein damage in vitro. Dicarbonyl/l-xylulose reductase (DCXR) metabolizes diacetyl into acetoin, which lacks this α-dicarbonyl group. To investigate the hypothesis that flavorings-related lung disease is caused by in vivo protein damage, we correlated diacetyl-induced airway damage in mice with immunofluorescence for markers of protein turnover and autophagy. Western immunoblots identified shifts in ubiquitin pools. Diacetyl inhalation caused dose-dependent increases in bronchial epithelial cells with puncta of both total ubiquitin and K63-ubiquitin, central mediators of protein turnover. This response was greater in Dcxr-knockout mice than in wild-type controls inhaling 200 ppm diacetyl, further implicating the α-dicarbonyl group in protein damage. Western immunoblots demonstrated decreased free ubiquitin in airway-enriched fractions. Transmission electron microscopy and colocalization of ubiquitin-positive puncta with lysosomal-associated membrane proteins 1 and 2 and with the multifunctional scaffolding protein sequestosome-1 (SQSTM1/p62) confirmed autophagy. Surprisingly, immunoreactive SQSTM1 also accumulated in the olfactory bulb of the brain. Olfactory bulb SQSTM1 often congregated in activated microglial cells that also contained olfactory marker protein, indicating neuronophagia within the olfactory bulb. This suggests the possibility that SQSTM1 or damaged proteins may be transported from the nose to the brain. Together, these findings strongly implicate widespread protein damage in the etiology of flavorings-related lung disease.

Occupational and environmental bronchiolar disorders

Occupational and environmental causes of bronchiolar disorders are recognized on the basis of case reports, case series, and, less commonly, epidemiologic investigations. Pathology may be limited to the bronchioles or also involve other components of the respiratory tract, including the alveoli. A range of clinical, functional, and radiographic findings, including symptomatic disease lacking abnormalities on noninvasive testing, poses a diagnostic challenge and highlights the value of surgical biopsy. Disease clusters in workplaces and communities have identified new etiologies, drawn attention to indolent disease that may otherwise have been categorized as idiopathic, and expanded the spectrum of histopathologic responses to an exposure. More sensitive noninvasive diagnostic tools, evidence-based therapies, and ongoing epidemiologic investigation of at-risk populations are needed to identify, treat, and prevent exposure-related bronchiolar disorders.

Biomarkers of lung injury in cardiothoracic surgery

Diagnosis of pulmonary dysfunction is currently almost entirely based on a vast series of physiological changes, but comprehensive research is focused on determining biomarkers for early diagnosis of pulmonary dysfunction. Here we discuss the use of biomarkers of lung injury in cardiothoracic surgery and their ability to detect subtle pulmonary dysfunction in the perioperative period. Degranulation products of neutrophils are often used as biomarker since they have detrimental effects on the pulmonary tissue by themselves. However, these substances are not lung specific. Lung epithelium specific proteins offer more specificity and slowly find their way into clinical studies.

Depletion of bone marrow CCSP-expressing cells delays airway regeneration

The contribution of bone marrow cells (BMC) in lung repair is controversial. We previously reported a subpopulation of BMC that express Clara cell secretory protein (CCSP). To determine the contribution of endogenous CCSP(+) BMC to airway regeneration, we performed bone marrow transplantation studies using the CCtk mouse, which expresses a thymidine kinase suicide gene under regulation of the CCSP promoter. Mice were transplanted with wild-type or CCtk BMC and treated with ganciclovir to eliminate CCSP(+) cells. After airway injury using naphthalene, mice depleted of CCSP(+) BMC had more inflammatory cells in lung and decreased levels of oxygen in arterial blood. They also had reduced expression of airway epithelial genes and less Clara cells compared to control mice that had intact CCSP(+) BMC and bone marrow derived CCSP(+) cells in the airways. After naphthalene injury, administration of CCSP reproduced the beneficial effect of CCSP(+) BMC by improving recovery of airway epithelium, reducing lung inflammation and increasing oxygen in arterial blood from mice depleted of CCSP(+) BMC. Our data demonstrate that ablation of CCSP(+) BMC delays airway recovery and suggests the beneficial effect of CCSP(+) BMC in lung recovery is in part due to production of CCSP itself.

The Effect of Pulsatile Cardiopulmonary Bypass on Lung Function in Elderly Patients

Purpose

Cardiopulmonary bypass is still a major cause of lung injury and delay in pulmonary recovery after cardiac surgery. Although it has been shown that pulsatile flow induced by intra-aortic balloon pumping is beneficial for preserving lung function, it is not clear if the same beneficial effect can be accomplished with pulsatile flow generated in the extracorporeal circuit. Therefore, we investigated the effect of pulsatile flow, produced by a centrifugal pump, on lung function in elderly patients.

Methods

Serial measurements of lung biomarkers Clara cell 16 kD protein, surfactant protein D, and elastase were performed on blood samples from 37 elderly patients (≥75 years) who underwent elective aortic valve replacement surgery with CPB, either with pulsatile perfusion or continuous perfusion. Pulmonary function was assessed by postoperative ventilation time, the arterial blood oxygenation (PaO2/FiO2), the alveolar-arterial oxygen gradient (Aa-O2 gradient) and the pulmonary vascular resistance indexed by body surface area (PVRi).

Results

There was no difference in lung function between both groups, as assessed by the postoperative ventilation time, the PaO2/FiO2 ratio, and the Aa-O2 gradient. The PVRi, however, was significantly lower in the pulsatile perfusion group 15 mins after the administration of protamine (p<0.05). The plasma concentrations of the lung biomarkers increased during surgery and peaked at 1 h ICU, there were however no differences between groups.

Conclusions

Pulsatile flow does not seem beneficial to postoperative lung function in elderly patients. Moreover, pulsatile flow does not affect lung function on a subclinical level as assessed by lung biomarkers.

Club cell secretory protein improves survival in a murine obliterative bronchiolitis model

Club cell secretory protein (CCSP) is an indirect phospholipase A2 inhibitor with some immunosuppressive and antiproliferative properties that is expressed in bronchiolar Club cells. In our murine bone marrow transplant (BMT) model of obliterative bronchiolitis (OB), CCSP is diminished; however, its role is unknown. To determine the role of CCSP, B6 wild-type (WT) or CCSP-deficient (CCSP(-/-)) mice were lethally conditioned and given allogeneic bone marrow with a sublethal dose of allogeneic splenic T cells to induce OB. We found that CCSP(-/-) mice demonstrated a higher mortality following BMT-induced OB compared with WT mice. Mice were analyzed 60 days post-BMT for protein expression, pulmonary function, and histology. CCSP levels were reduced in WT mice with BMT-induced OB, and lower levels correlated to decreased lung compliance. CCSP(-/-) had a higher degree of injury and fibrosis as measured by hydroxy proline, along with an increased lung resistance and the inflammatory markers, leukotriene B4 and CXCL1. Replacement with recombinant intravenous CCSP partially reversed the weight loss and improved survival in the CCSP(-/-) mice. In addition, CCSP replacement improved histology and decreased inflammatory cells and markers. These findings indicate that CCSP has a regulatory role in OB and may have potential as a preventive therapy.

Bronchoalveolar lavage as a tool to predict, diagnose and understand bronchiolitis obliterans syndrome

Bronchiolitis obliterans syndrome (BOS), a condition of irreversible small airway fibrosis, is the principal factor limiting long-term survival after lung transplantation. Bronchoscopy and bronchoalveolar lavage (BAL), techniques central to lung transplant clinical practice, provide a unique opportunity to interrogate the lung allograft during BOS development and identify potential disease mechanisms or biomarkers. Over the past 20 years, numerous studies have evaluated the BAL cellular composition, cytokine profiles and protein constituents in lung transplant recipients with BOS. To date, however, no summative evaluation of this literature has been reported. We developed and applied objective criteria to qualitatively rank the strength of associations between BAL parameters and BOS in order to provide a comprehensive and systematic assessment of the literature. Our analysis indicates that several BAL parameters, including neutrophil count, interleukin-8, alpha defensins and MMP-9, demonstrate highly replicable associations with BOS. Additionally, we suggest that considerable opportunity exists to increase the knowledge gained from BAL analyses in BOS through increased sample sizes, covariant adjustment and standardization of the BAL technique. Further efforts to leverage analysis of BAL constituents in BOS may offer great potential to provide additional in-depth and mechanistic insights into the pathogenesis of this complex disease.

Epithelial clara cell injury occurs in bronchiolitis obliterans syndrome after human lung transplantation

Bronchiolitis obliterans syndrome (BOS) is a condition of progressive airflow obstruction that affects a majority of lung transplant recipients and limits long-term posttransplant survival. Although epithelial injury appears central to the development of BOS, little is known regarding the specific epithelial cell types that are affected in this condition. We hypothesized that BOS would involve preferential injury to the secretory Clara cells that function in innate defense and epithelial repair. To test this hypothesis, we assessed tissue transcript, tissue protein and lung fluid protein expression of Clara cell secretory protein (CCSP), a marker for Clara cells, in lung transplant recipients with BOS, BOS-free patients and in donor controls. Our results demonstrate that CCSP tissue transcript and protein expression are significantly reduced in lung transplant recipients with BOS compared to BOS-free or donor controls. In addition, we demonstrate that CCSP protein levels are significantly reduced in the lung fluid of patients with BOS compared to BOS-free controls, in cross-sectional and longitudinal analysis. Collectively, these complementary results illustrate that BOS involves a selective alteration in the distribution and function of bronchiolar Clara cells.

Severe airway epithelial injury, aberrant repair and bronchiolitis obliterans develops after diacetyl instillation in rats

BACKGROUND

Bronchiolitis obliterans (BO) is a fibrotic lung disease that occurs in a variety of clinical settings, including toxin exposures, autoimmunity and lung or bone marrow transplant. Despite its increasing clinical importance, little is known regarding the underlying disease mechanisms due to a lack of adequate small animal BO models. Recent epidemiological studies have implicated exposure to diacetyl (DA), a volatile component of artificial butter flavoring, as a cause of BO in otherwise healthy factory workers. Our overall hypothesis is that DA induces severe epithelial injury and aberrant repair that leads to the development of BO. Therefore, the objectives of this study were 1) to determine if DA, delivered by intratracheal instillation (ITI), would lead to the development of BO in rats and 2) to characterize epithelial regeneration and matrix repair after ITI of DA.

METHODS AND MAIN RESULTS

Male Sprague-Dawley rats were treated with a single dose of DA (125 mg/kg) or sterile water (vehicle control) by ITI. Instilled DA resulted in airway specific injury, followed by rapid epithelial regeneration, and extensive intraluminal airway fibrosis characteristic of BO. Increased airway resistance and lung fluid neutrophilia occurred with the development of BO, similar to human disease. Despite rapid epithelial regeneration after DA treatment, expression of the normal phenotypic markers, Clara cell secretory protein and acetylated tubulin, were diminished. In contrast, expression of the matrix component Tenascin C was significantly increased, particularly evident within the BO lesions.

CONCLUSIONS

We have established that ITI of DA results in BO, creating a novel chemical-induced animal model that replicates histological, biological and physiological features of the human disease. Furthermore, we demonstrate that dysregulated epithelial repair and excessive matrix Tenacin C deposition occur in BO, providing new insights into potential disease mechanisms and therapeutic targets.

Elevated plasma clara cell secretory protein concentration is associated with high-grade primary graft dysfunction

Primary graft dysfunction (PGD) is the leading cause of early posttransplant morbidity and mortality after lung transplantation. Clara cell secretory protein (CC16) is produced by the nonciliated lung epithelium and may serve as a plasma marker of epithelial cell injury. We hypothesized that elevated levels of CC16 would be associated with increased odds of PGD. We performed a prospective cohort study of 104 lung transplant recipients. Median plasma CC16 levels were determined at three time points: pretransplant and 6 and 24 h posttransplant. The primary outcome was the development of grade 3 PGD within the first 72 h after transplantation. Multivariable logistic regression was performed to evaluate for confounding by donor and recipient demographics and surgical characteristics. Twenty-nine patients (28%) developed grade 3 PGD within the first 72 h. The median CC16 level 6 h after transplant was significantly higher in patients with PGD [13.8 ng/mL (IQR 7.9, 30.4 ng/mL)] than in patients without PGD [8.2 ng/mL (IQR 4.5, 19.1 ng/mL)], p = 0.02. Elevated CC16 levels were associated with increased odds of PGD after lung transplantation. Damage to airway epithelium or altered alveolar permeability as a result of lung ischemia and reperfusion may explain this association.

Clara cell protein in bronchoalveolar lavage fluid: a predictor of ventilator-associated pneumonia?

Introduction

Clara cell protein 10 (CC-10) has been associated with inflammatory and infectious pulmonary diseases. This study evaluates CC-10 concentrations in bronchoalveolar lavage (BAL) fluid as a potential marker of ventilator-associated pneumonia (VAP).

Methods

Between January 2003 and December 2007, BAL fluid samples obtained from critically ill patients at the intensive care unit of the Maastricht University Medical Centre clinically suspected of having VAP were included. Patients were divided into two groups: (1) microbiologically confirmed VAP (the VAP group) and (2) microbiologically unconfirmed VAP (the non-VAP group). The concentration of CC-10 was measured by means of a commercially available enzyme-linked immunosorbent assay kit, and retrospective analysis was performed. Areas under the curve of receiver operating characteristic curves were calculated for CC-10 concentrations.

Results

A total of 196 patients (122 men, 74 women) were included. A total of 79 (40%) of 196 cases of suspected VAP were microbiologically confirmed. The median CC-10 concentration in the VAP group was 3,019 ng/mL (range, 282 to 65,546 ng/mL) versus 2,504 ng/mL (range, 62 to 30,240 ng/mL) in the non-VAP group (P = 0.03). There was no significant difference in CC-10 concentrations between patients treated with or without corticosteroids (P = 0.26) or antibiotic therapy (P = 0.9). The CC-10 concentration did not differ significantly between patients with Gram-positive versus Gram-negative bacteria that caused the VAP (P = 0.06). However, CC-10 concentrations did differ significantly between the late-onset VAP group and the non-VAP group.

Conclusions

The CC-10 concentration in BAL fluid yielded low diagnostic accuracy in confirming the presence of VAP.

Non-invasive assessment of small airway remodelling in smokers

Smoking associated COPD progression is likely to be directly linked to differential injury and repair dynamics in small airways (SA). Although IL8 is a well-accepted marker for injured airway epithelium, Clara cells [the predominant proliferating cells in SA] and SCGB1A1 protein [their major secretory product] have only recently emerged as potential SA repair markers. We therefore postulate that the SCGB1A1/IL8 ratio in the airways of smokers would be inversely associated with physiological, radiological and clinical measures of COPD. A cross-sectional cohort of 28 smokers undergoing surgery for peripheral nodule was recruited (24M/4F, age 61 +/- 11 y, FEV1s 76 +/- 20%, smoking 40 +/- 12 p.y). SCGB1A1 and IL8 were measured by ELISA in the induced sputum (IS) 3 to 5 days prior to surgery as well as by immunohistochemistry from lung tissue (also assessed morphometrically) obtained distant to the cancer surgery site. COPD was assessed using standard clinical, functional and radiological parameters. Log-transformed IS-SCGB1A1 was linearly correlated with SCGB1A1-positive epithelial cells detected via immunohistochemistry (r = .533, p = .001), while IS-IL8 was positively related to SA infiltrating neutrophils (Elastase-positive cells). There was a striking negative correlation between IS-SCGB1A1/IL8 levels and whole airway thickness [SA < 2 mm] at morphometry (r = -0.83, p < 0.0001). IS-SCGB1A1/IL8 levels were also inversely associated with nitrogen slope [r = -0.52, p < 0.001] and HRCT SA score [r = -0.51, p < 0.001]. In a multivariate analysis the IS-SCGB1A1/IL8 ratio was a stronger predictor than both the physiological and radiological measures of SA disease assessed. The SCGB1A1/IL8 ratio measured in sputum is a potentially valuable biomarker for non-invasive assessment of SA remodelling in smokers.

Airway regeneration: the role of the Clara cell secretory protein and the cells that express it

Clara cell secretory protein (CCSP) is one of the most abundant proteins in the airway surface fluid, and has many putative functions. Recent advances in the field of stem cells and lung regeneration have identified potentially new roles of CCSP and CCSP-expressing cell populations in airway maintenance, repair and regeneration. This review focuses on the airway regenerative potential of CCSP and the cells that express this protein. The use of this protein or CCSP-expressing cells as an indication of biologic processes that contribute to lung injury or repair is highlighted.

Clara cell protein (CC16), a marker of lung epithelial injury, is decreased in plasma and pulmonary edema fluid from patients with acute lung injury

BACKGROUND

Acute lung injury (ALI) and ARDS are common clinical syndromes that are underdiagnosed. Clara cell secretory protein (CC16) is an antiinflammatory protein secreted by the Clara cells of the distal respiratory epithelium that has been proposed as a biomarker of lung epithelial injury. We tested the diagnostic and prognostic utility of CC16 in patients with non-trauma-related ALI/ARDS compared to a control group of patients with acute cardiogenic pulmonary edema (CPE).

METHODS

Plasma and pulmonary edema fluid samples were obtained from medical and surgical patients with ALI/ARDS or CPE requiring intubation for mechanical ventilation. The etiology of pulmonary edema was determined using consensus clinical criteria for ALI/ARDS and CPE and the edema fluid-to-plasma protein ratio. Plasma and edema fluid CC16 levels were measured by sandwich enzyme-linked immunosorbent assay. CC16 levels were log transformed for analysis, and comparisons were made by the Student t test or Chi(2) as appropriate.

RESULTS

Compared to patients with CPE (n = 9), patients with ALI/ARDS (n = 23) had lower median CC16 levels in plasma (22 ng/mL [interquartile range (IQR), 9 to 44 ng/mL] vs 55 ng/mL [IQR, 18 to 123 ng/mL], respectively; p = 0.053) and pulmonary edema fluid (1,950 ng/mL [IQR, 1,780 to 4,024 ng/mL] vs 4,835 ng/mL [IQR, 2,006 to 6,350 ng/mL], respectively; p = 0.044). Relative to total pulmonary edema fluid protein concentration, the median CC16 level was significantly lower in patients with ALI/ARDS (45 ng CC16/mg total protein [IQR, 4 to 64 ng CC16/mg total protein] vs 120 ng CC16/mg total protein [IQR, 87 to 257 ng CC16/mg total protein], respectively; p = 0.005). Neither plasma nor edema fluid CC16 levels predicted mortality, the number of days of unassisted ventilation, or ICU length of stay.

CONCLUSION

CC16 is a promising diagnostic biomarker for helping to discriminate ALI from CPE. Larger scale validation is warranted to better characterize the utility of CC16 in the diagnosis of this underrecognized syndrome.

Bronchiolitis obliterans syndrome: alloimmune-dependent and -independent injury with aberrant tissue remodeling

Long-term success in lung transplantation continues to be challenged by chronic graft dysfunction, which is manifest as bronchiolitis obliterans syndrome (BOS). The mechanisms of BOS involve both immune-mediated pathways (rejection, autoimmune-like mechanisms), and alloimmune-independent pathways (infection, aspiration, ischemia, primary graft failure), which lead to a fibroproliferative responses. BOS correlates histologically with obliterative bronchiolitis in terminal bronchioles and evidence of aberrant remodeling in the airway epithelium, vasculature, stroma, and lymphoid system. A potentially important mechanism that supports the progressive and therapy-resistant nature of BOS is a continuous cycle of ongoing injury and aberrant remodeling. Namely, anatomical and functional abnormalities induce and exacerbate immune-mediated and alloimmune-independent pathways through various mechanisms (e.g., epithelial remodeling decreases mucociliary clearance that exacerbates aspiration-related injury). From this viewpoint, we review current therapeutic strategies and revisit the role of transplant surgeons in attenuating the initial transplant-related injuries to prevent the lung grafts from entering the remodeling-injury cycle.

Tissue inhibitor of metalloproteinase-1 moderates airway re-epithelialization by regulating matrilysin activity

Obliterative bronchiolitis (OB) is the histopathological finding in chronic lung allograft rejection. Mounting evidence suggests that epithelial damage drives the development of airway fibrosis in OB. Tissue inhibitor of metalloproteinase (TIMP)-1 expression increases in lung allografts and is associated with the onset of allograft rejection. Furthermore, in a mouse model of OB, airway obliteration is reduced in TIMP-1-deficient mice. Matrilysin (matrix metallproteinase-7) is essential for airway epithelial repair and is required for the re-epithelialization of airway wounds by facilitating cell migration; therefore, the goal of this study was to determine whether TIMP-1 inhibits re-epithelialization through matrilysin. We found that TIMP-1 and matrilysin co-localized in the epithelium of human lungs with OB and both co-localized and co-immunoprecipitated in wounded primary airway epithelial cultures. TIMP-1-deficient cultures migrated faster, and epithelial cells spread to a greater extent compared with wild-type cultures. TIMP-1 also inhibited matrilysin-mediated cell migration and spreading in vitro. In vivo, TIMP-1 deficiency enhanced airway re-epithelialization after naphthalene injury. Furthermore, TIMP-1 and matrilysin co-localized in airway epithelial cells adjacent to the wound edge. Our data demonstrate that TIMP-1 interacts with matrix metalloproteinases and regulates matrilysin activity during airway epithelial repair. Furthermore, we speculate that TIMP-1 overexpression restricts airway re-epithelialization by inhibiting matrilysin activity, contributing to a stereotypic injury response that promotes airway fibrosis via bronchiole airway epithelial damage and obliteration.

Bronchoalveolar lavage fluid proteome in bronchiolitis obliterans syndrome: possible role for surfactant protein A in disease onset

BACKGROUND

Bronchiolitis obliterans syndrome (BOS) affects long-term survival of lung transplant (Tx) recipients (LTRs), with no consistently effective treatment strategy. Identifying early markers of BOS is of paramount importance for improving graft survival.

METHODS

We used 2-dimensional gel electrophoresis and protein identification by mass spectrometry to compare the protein profile of bronchoalveolar lavage fluid (BALf) in two groups of LTRs: one composed of patients with BOS and the other composed of patients with good graft function at >5 years post-surgery (stable LTRs). Based on the hypothesis that only proteins of lung origin could represent reliable BOS markers, we also evaluated paired plasma samples. Proteins of interest were also assessed in the BALf of control subjects and results confirmed by dot- blot analysis.

RESULTS

Among 11 differentially expressed proteins, we identified 2 locally produced factors: peroxiredoxin II (PRXII), exclusively expressed in BOS; and surfactant protein A (SP-A), expressed consistently less in BOS patients than in stable LTRs. PRXII expression was never observed in BALf from control subjects, whereas SP-A was present in higher amounts compared with stable LTRs and BOS patients. Finally, the time course of SP-A was studied in 5 LTRs who subsequently developed BOS. A reduction in BALf SP-A content was detectable early after Tx, preceding BOS onset in 4 of 5 patients.

CONCLUSIONS

Our results suggest that testing SP-A levels in BALf could predict LTR patients who are at higher risk of BOS development.

Analysis of chronic lung transplant rejection by MALDI-TOF profiles of bronchoalveolar lavage fluid

While lung transplant is an effective therapy for advanced lung disease, chronic allograph rejection remains a primary basis for lower survival rates than those for other solid organ transplants. This study used carefully controlled Zip-Tip extraction of bronchoalveolar lavage fluid (BALF) followed by MALDI-TOF MS to identify biomarkers of chronic lung transplant rejection. Many differences were observed between controls, those who did not develop chronic rejection within 100 months, and patients who had developed chronic rejection, diagnosed as bronchiolitis obliterans syndrome (BOS). Intensity ratios of peaks within the same MALDI-TOF profile were used to quantify the result. One of the best identifiers of BOS was a lowered ratio of clara cell protein (CCP m/z = 15,835) to lysozyme (m/z = 14,700), which gave 94% specificity and 74% sensitivity for diagnosis. Furthermore, low values for CCP/Lysozyme (<0.3) were observed in 66% of samples taken at 1 to 15 months prior to the diagnosis of BOS. Many other components of the profile gave similar or better outcomes for diagnosis but tended to be less valuable for the prediction of future disease. Overall, this study demonstrated the feasibility of this approach for the detection of disease biomarkers.

Gene expression profiling in murine obliterative airway disease

Lung and heart-lung transplantation are effective treatments for many diseases unresponsive to other therapy. However, long-term survival of recipients is limited by the development of obliterative bronchiolitis (OB). In this study, microarray analysis of a heterotopic mouse model of obliterative airway disease (OAD) was used to test the hypothesis that the expression and patterns of genes will correlate with specific changes in tracheal tissue developing a response to allotransplantation and the infiltrating cells manifesting these changes. Expression profiles observed were in accordance with the current paradigm of a predictable sequence of events, beginning with airway injury; an innate immune response followed by an adaptive immune response, including both cell-mediated and humoral components; and eventual loss of airway epithelial cells. These observations confirm and expand the list of genes and molecular processes that can be studied as potential surrogate markers or targets for intervention of OB.

Decreased serum levels of clara cell secretory protein (CC16) are associated with bronchiolitis obliterans and may permit early diagnosis in patients after allogeneic stem-cell transplantation

BACKGROUND

Bronchiolitis obliterans (BO) is a common complication and is associated with high mortality after allogeneic stem-cell transplantation (SCT). Early diagnosis of BO may improve outcome. Low levels of Clara cell secretory protein (CC16) have previously been associated with BO in lung transplant recipients.

METHODS

Serum samples were collected from eight patients with BO, eight patients with chronic graft-versus-host disease (GVHD), and eight control patients with neither BO nor chronic GVHD in a matched patient analysis. Patients were matched for diagnosis, conditioning, donor match, and GVHD prophylaxis. Another seven patients with BO were also analyzed separately. CC16 was measured with an enzyme-linked immunosorbent assay method.

RESULTS

In the matched analysis, eight patients were diagnosed with BO at a median of 11.5 months (range, 4-13 months) after SCT and in non-matched BO patients at a median of 12 months (range, 9-36 months). In the matched patient analysis, patients with BO had significantly lower (P=0.03) or decreasing (P=0.02) levels of CC16 compared with patients with only chronic GVHD or controls. In the matched patient analysis, measurement of CC16 showed a sensitivity of 88% and a specificity of 81%. With the criteria of low levels of CC16 or a decrease of more than 40% compared with the previous sample, BO was detected with analysis of CC16 in 13 of 15 patients. In 11 of the 13 patients, low or decreasing values of CC16 were detected at a median of 10 months (range, 1-30 months) before BO was diagnosed clinically.

CONCLUSIONS

Low levels of CC16 are associated with BO after allogeneic SCT. Monitoring of CC16 in serum after SCT may have potential as an early marker for BO.

Bronchiolitis obliterans in children

Bronchiolitis obliterans (BO) in children is a relatively rare diagnosis. The increase in lung and bone marrow transplantation in children, however, has led to a heightened interest in BO, as this is one of the important complications of those procedures. This article will discuss BO as an entity that can follow any of several illnesses or toxic exposures, in addition to following allogeneic lung or bone marrow transplantation. The complex and incompletely understood pathology, pathogenesis, and molecular pathology involved in BO remain the subject of ongoing investigations. As the prognosis for BO is uncertain and treatment is often unsuccessful, the continued need for the recognition of surrogate markers for BO in patients at risk and the development of better forms of therapy are paramount. This review will describe our current understanding of BO, and will call attention to those research areas that require continuing efforts in order to prevent or treat this entity.

Is bronchoalveolar lavage obsolete in the diagnosis of interstitial lung disease?

This review considers the literature on bronchoalveolar lavage in the diagnosis of interstitial lung disease published during the last 12 months with the aim of clarifying the role bronchoalveolar lavage can have in diagnostic work-up on the basis of current knowledge and expert opinion. Recent research findings with possible future clinical applications are presented. Various information, useful for research and clinical applications, can be obtained from performing bronchoalveolar lavage in patients with interstitial lung diseases. Indeed, evaluation of cell pattern associated with cell phenotype is used widely in clinical practice to distinguish the various forms and may be of diagnostic value in some interstitial lung diseases, as already known, when the clinical picture is compatible. Bronchoalveolar lavage may also be complementary to high-resolution CT or at least useful for diagnosis by exclusion. A major advance in the last year is recognition of a role for bronchoalveolar lavage in the diagnostic workup of idiopathic interstitial pneumonias, albeit as an auxiliary procedure. It may be useful to exclude infections and tumors, may help to decide whether to do surgical biopsy, and may aid in distinguishing different forms of interstitial lung disease. Although it is not diagnostic for idiopathic interstitial pneumonias, in the presence of cell patterns considered "typical" of the various forms, it can support clinical diagnosis in the absence of biopsy. Because further studies following standardized protocols and guidelines will presumably find new parameters for bronchoalveolar lavage in the diagnostics of interstitial lung diseases, it would be a mistake to consider bronchoalveolar lavage an obsolete tool.