Giovanni Barisione

Late Pulmonary Complications After Allogeneic Hematopoietic Stem Cell Transplantation: Diagnosis, Monitoring, Prevention, and Treatment

Bronchiolitis obliterans syndrome (BOS) is a life-threatening complication that occurs among recipients of allogeneic lung and hematopoietic stem cell transplantation (allo-HSCT). BOS usually occurs within the first 2 years but may develop as late as 5 years after allo-HSCT. Recent prevalence estimates suggest that BOS is likely underdiagnosed in the clinical setting and that 14% of all long-term survivors with chronic graft-versus-host disease (GVHD) may develop BOS. It is difficult to diagnose and once respiratory symptoms appear, most allo-HSCT recipients show severe airflow obstruction. This may be due, at least in part, to the low sensitivity of standard spirometry in detecting small airways obstruction and lack of formal recommendations for screening for this complication. The prognosis of BOS is poor with reported 5-year survival of about 15%. A key obstacle in advancing clinical research in BOS is the lack of diagnostic and therapeutic response standards, making interpretation of survival and treatment results between studies difficult. This situation has significantly improved due to the introduction of the National Institutes of Health (NIH) criteria, which provide investigators with common definitions for studying BOS and for assessing the effects of therapeutic interventions. Future advances in the therapy of BOS may need to include development of better early intervention strategies based on identification of reliable early biological markers of the disease. It would be also important to improve understanding of the biological heterogeneity of this devastating complication after allo-HSCT.

Noninflammatory mechanisms of airway hyper-responsiveness in bronchial asthma: an overview

Airway hyper-responsiveness (AHR) is a cardinal feature of asthma. Its absence has been considered useful in excluding asthma, whereas it may be present in other diseases such as atopic rhinitis and chronic obstructive pulmonary disease. AHR is often considered an epiphenomenon of airway inflammation. Actually, the response of airways to constrictor stimuli is modulated by a complex array of factors, some facilitating and others opposing airway narrowing. Thus, it has been suggested that AHR, and perhaps asthma, might be present even without or before the development of airway inflammation. We begin this review by highlighting some terminological and methodological issues concerning the measurement of AHR. Then we describe the neurohumoral mechanisms controlling airway tone. Finally, the pivotal role of airway smooth muscle and internal and external modulation of airway caliber in vivo are discussed in detail.

Acute Bronchodilator Responsiveness in Bronchiolitis Obliterans Syndrome Following Hematopoietic Stem Cell Transplantation

BACKGROUND The obstructive abnormality of bronchiolitis obliterans syndrome (BOS) after allogeneic hematopoietic stem cell transplantation (HSCT) is deemed to be virtually insensitive to treatment with inhaled bronchodilators. We studied whether nonconventional assessment of bronchodilation may help to detect physiologically meaningful airway responses missed by traditional criteria. METHODS Standard spirometry, partial and maximal expiratory flow-volume curves, and lung volumes were measured before and 90 min after inhalation of albuterol plus tiotropium in 17 patients who developed mild to very severe BOS following HSCT. RESULTS After treatment with bronchodilators, the standard criteria of reversibility based on FEV1 and FVC were met in seven out of 17 patients. In eight patients, residual volume (RV) decreased beyond its within-session spontaneous variability, and functional residual capacity (FRC) was reduced in four of them. Partial forced expiratory flow (Vpart) increased beyond its within-session spontaneous variability in nine patients. Out of 10 patients in whom neither FEV1 nor FVC met the standard criteria of reversibility, six had a positive increase in Vpart or a decrease of lung hyperinflation (ie, FRC) or RV. In six patients with limited expiratory flow during tidal breathing, the postbronchodilator increase in Vpart was correlated with a decrease in FRC (R2=0.83; P=.011). CONCLUSIONS This study suggests that airway smooth muscle tone plays a significant role in BOS after HSCT and that the common knowledge of BOS as an irreversible obstructive disease may stem from the limitation of simple spirometry to detect changes in small airways. TRIAL REGISTRY ClinicalTrials.gov; No.: NCT01112241 (BOS-01); URL: www.clinicaltrials.gov.

How to interpret reduced forced expiratory volume in 1 s (FEV1)/vital capacity ratio with normal FEV1

The aim of the present study was to determine whether the combination of low forced expiratory volume in 1 s (FEV1)/vital capacity (VC) ratio with normal FEV1 represents a physiological variant or a sign of early airflow obstruction. We studied 40 subjects presenting with low FEV1/VC, but FEV1 within the range of normality predicted by European Respiratory Society reference equations, and 10 healthy controls. All subjects completed two questionnaires and underwent comprehensive pulmonary function testing, which included methacholine challenge and single-breath nitrogen wash-out. According to the questionnaires, the subjects were assigned to three groups, i.e. rhinitis (n = 8), bronchial asthma (n = 13) and chronic obstructive pulmonary disease (COPD; n = 12). Subjects with negative responses to questionnaires were assigned to an asymptomatic group (n = 7). Airway hyperresponsiveness was found in four subjects of the rhinitis group, all of the asthma group, and 10 of the COPD group; in the last two groups, it was associated with signs of increased airway closure and gas trapping. Bronchodilator response to salbutamol was positive in only a few individuals across groups. In the asymptomatic group, no significant functional changes were observed, possibly suggesting dysanaptic lung growth. In subjects with low FEV1/VC and normal FEV1, questionnaires on respiratory symptoms together with additional pulmonary function tests may help to clarify the nature of this pattern of lung function.

Beta-Adrenergic Agonists.

Inhaled β2-adrenoceptor (β2-AR) agonists are considered essential bronchodilator drugs in the treatment of bronchial asthma, both as symptoms-relievers and, in combination with inhaled corticosteroids, as disease-controllers. In this article, we first review the basic mechanisms by which the β2-adrenergic system contributes to the control of airway smooth muscle tone. Then, we go on describing the structural characteristics of β2-AR and the molecular basis of G-protein-coupled receptor signaling and mechanisms of its desensitization/ dysfunction. In particular, phosphorylation mediated by protein kinase A and β-adrenergic receptor kinase are examined in detail. Finally, we discuss the pivotal role of inhaled β2-AR agonists in the treatment of asthma and the concerns about their safety that have been recently raised.

Pulmonary physiology: future directions for lung function testing in COPD.

Chronic obstructive pulmonary disease (COPD) is a term that encompasses different pathological conditions having excessive airflow limitation in common. A wide body of knowledge has been accumulated over the last century explaining the mechanisms by which airway (chronic bronchitis) and parenchymal (emphysema) diseases lead to an indistinguishable spirometric abnormality. Although the definition of emphysema is anatomical, early studies showed that its presence can be inferred with good approximation from measurements of lung mechanics and gas exchange, in addition to simple spirometry. Studies using tests of ventilation distribution showed that abnormalities are present in smokers with normal spirometry, although these tests were not predictive of development of COPD. At the beginning of the third millennium, new documents and guidelines for diagnosis and treatment of COPD were developed, in which the functional diagnosis of COPD was restricted, for the sake of simplicity, to simple spirometry. In recent years, there has been a resurgence of interest in separating bronchitic from emphysematous phenotype of COPD. For this purpose, high‐resolution computed tomography scanning has been added to diagnostic work‐up. At the same time, methods for lung function testing have been refined and seem promising for detection of early small airways abnormalities. Among them are the forced oscillation technique and the nitrogen phase III slope analysis of the multiple‐breath washout test, which may provide information on ventilation inhomogeneity. Moreover, the combined assessment of diffusing capacity for nitric oxide and carbon monoxide may be more sensitive than the latter alone for partitioning diffusive components at parenchymal level.

Changes in lung volumes and airway responsiveness following haematopoietic stem cell transplantation

Changes in lung volume occur following haematopoietic stem cell transplantation (HSCT); airway hyperresponsiveness was occasionally reported, without mechanistic explanation. The present authors studied 17 patients by standard methacholine (MCh) challenge before and then 3 and 12 months after HSCT (n = 16 and n = 13, respectively). Another 6 patients were challenged before and 3 months after HSCT using a modified challenge to investigate the effect of deep inhalations. No patient developed bronchiolitis obliterans or bronchiolitis obliterans organising pneumonia. At 3 months, forced vital capacity (FVC) was significantly reduced by 0.33±0.55 L, forced expiratory volume in one second (FEV1) by 0.31±0.50 L, total lung capacity (TLC) by 0.39±0.37 L and single-breath diffusing capacity of the lung for carbon monoxide (DL,CO) by 15±12%. At 12 months, TLC decreased by 0.43±0.36 L and DL,CO by 8±8%. With standard challenge, no significant changes in FEV1 response to MCh were observed after HSCT but FVC decreased significantly less after HSCT compared with prior to HSCT, suggesting less air trapping. With modified challenge, deep inhalations reversed the MCh-induced decrease in partial expiratory flow more after HSCT compared with before HSCT and this correlated with TLC decrements. In conclusion, an increase in airway responsiveness is unlikely after haematopoietic stem cell transplantation, at least in patients without pulmonary complications, and mechanisms opposing airway narrowing may blunt the bronchoconstrictor response.

Mechanisms for reduced pulmonary diffusing capacity in haematopoietic stem-cell transplantation recipients

Lung diffusing capacity for CO (DLCO) is compromised in haematopoietic stem-cell transplantation (HSCT) recipients. We derived alveolar-capillary membrane conductance (DM,CO) and pulmonary capillary volume (VC) from DLCO and diffusing capacity for NO (DLNO). Forty patients were studied before and 6 weeks after HSCT. Before HSCT, DLNO and DLCO were significantly lower than in 30 healthy controls. DM,CO was ∼40% lower in patients than in controls (p<0.001), whereas VC did not differ significantly. After HSCT, DLNO and DM,CO further decreased, the latter by ∼22% from before HSCT (p<0.01) while VC did not change significantly. Lung density, serum CRP and reactive oxygen metabolites were significantly increased, with the latter being correlated (R2=0.71, p<0.001) with the decrement in DLNO. We conclude that DLNO and, to a lesser extent, DLCO are compromised before HSCT mainly due to a DM,CO reduction. A further reduction of DM,CO without VC loss occurs after HSCT, possibly related to development of oedema, or interstitial fibrosis, or both.

Lung function testing in COPD: when everything is not so simple

Combined pulmonary fibrosis and emphysema is a condition occurring mainly in male smokers, presenting different lung mechanics and gas exchange abnormalities than emphysema or pulmonary fibrosis alone. We report the case of an elderly man, former heavy smoker, who presented with progressive exertional dyspnea for 1 year. Lung function tests showed near normal spirometry and lung volumes but marked reduction of diffusing capacity for carbon monoxide and even more nitric oxide. The arterial partial pressure of oxygen was reduced with a markedly increased alveolar‐to‐arterial difference. High‐resolution computed tomography of the chest showed a pattern consistent with upper lobe emphysema and lower lobe pulmonary fibrosis. In conclusion, this case report confirms the limitations of a simplistic approach to lung function in the diagnosis of symptomatic smokers.

Lung diffusing capacity for nitric oxide as a marker of fibrotic changes in idiopathic interstitial pneumonias.

Lung diffusing capacity for carbon monoxide (DLCO) is decreased in both usual interstitial pneumonia-idiopathic pulmonary fibrosis (UIP-IPF) and nonspecific interstitial pneumonia (NSIP), but is moderately related to computed tomography (CT)-determined fibrotic changes. This may be due to the relative insensitivity of DLCO to changes in alveolar membrane diffusive conductance (DMCO). The purpose of this study was to determine whether measurement of lung diffusing capacity for nitric oxide (DLNO) better reflects fibrotic changes than DLCO DLNO-DLCO were measured simultaneously in 30 patients with UIP-IPF and 30 with NSIP. Eighty-one matched healthy subjects served as a control group. The amount of pulmonary fibrosis was estimated by CT volumetric analysis of visually bounded areas showing reticular opacities and honeycombing. DMCO and pulmonary capillary volume (VC) were calculated. DLNO was below the lower limit of normal in all patients irrespective of extent and nature of disease, whereas DLCO was within the normal range in a nonnegligible number of patients. Both DLNO and DLCO were significantly correlated with visual assessment of fibrosis but DLNO more closely than DLCO DMCO was also below the lower limit of normal in all UIP-IPF and NSIP patients and significantly correlated with fibrosis extent in both diseases, whereas VC was weakly correlated with fibrosis in UIP-IPF and uncorrelated in NSIP, with normal values in half of patients. In conclusion, measurement of DLNO may provide a more sensitive evaluation of fibrotic changes than DLCO in either UIP-IPF or NSIP, because it better reflects DMCO.