Anti-inflammatory and immunomodulatory properties of azithromycin involved in treatment and prevention of chronic lung allograft rejection. Transplantation. 2012;94:101-109. [PMID: 22461039 DOI: 10.1097/tp.0b013e31824db9da]

The Lung Microbiome Predicts Mortality and Response to Azithromycin in Lung Transplant Recipients with Chronic Rejection

Rationale: Chronic lung allograft dysfunction (CLAD) is the leading cause of death after lung transplant, and azithromycin has variable efficacy in CLAD. The lung microbiome is a risk factor for developing CLAD, but the relationship between lung dysbiosis, pulmonary inflammation, and allograft dysfunction remains poorly understood. Whether lung microbiota predict outcomes or modify treatment response after CLAD is unknown. Objectives: To determine whether lung microbiota predict post-CLAD outcomes and clinical response to azithromycin. Methods: Retrospective cohort study using acellular BAL fluid prospectively collected from recipients of lung transplant within 90 days of CLAD onset. Lung microbiota were characterized using 16S rRNA gene sequencing and droplet digital PCR. In two additional cohorts, causal relationships of dysbiosis and inflammation were evaluated by comparing lung microbiota with CLAD-associated cytokines and measuring ex vivo P. aeruginosa growth in sterilized BAL fluid. Measurements and Main Results: Patients with higher bacterial burden had shorter post-CLAD survival, independent of CLAD phenotype, azithromycin treatment, and relevant covariates. Azithromycin treatment improved survival in patients with high bacterial burden but had negligible impact on patients with low or moderate burden. Lung bacterial burden was positively associated with CLAD-associated cytokines, and ex vivo growth of P. aeruginosa was augmented in BAL fluid from transplant recipients with CLAD. Conclusions: In recipients of lung transplants with chronic rejection, increased lung bacterial burden is an independent risk factor for mortality and predicts clinical response to azithromycin. Lung bacterial dysbiosis is associated with alveolar inflammation and may be promoted by underlying lung allograft dysfunction.

ERS/EBMT clinical practice guidelines on treatment of pulmonary chronic graft-versus-host disease in adults

Chronic graft-versus-host disease (cGvHD) is a common complication after allogeneic haematopoietic stem cell transplantation, characterised by a broad disease spectrum that can affect virtually any organ. Although pulmonary cGvHD is a less common manifestation, it is of great concern due to its severity and poor prognosis. Optimal management of patients with pulmonary cGvHD is complicated and no standardised approach is available. The purpose of this joint European Respiratory Society (ERS) and European Society for Blood and Marrow Transplantation task force was to develop evidence-based recommendations regarding the treatment of pulmonary cGvHD phenotype bronchiolitis obliterans syndrome in adults. A multidisciplinary group representing specialists in haematology, respiratory medicine and methodology, as well as patient advocates, formulated eight PICO (patient, intervention, comparison, outcome) and two narrative questions. Following the ERS standardised methodology, we conducted systematic reviews to address these questions and used the Grading of Recommendations Assessment, Development and Evaluation approach to develop recommendations. The resulting guideline addresses common therapeutic options (inhalation therapy, fluticasone-azithromycin-montelukast, imatinib, ibrutinib, ruxolitinib, belumosudil, extracorporeal photopheresis and lung transplantation), as well as other aspects of general management, such as lung functional and radiological follow-up and pulmonary rehabilitation, for adults with pulmonary cGvHD phenotype bronchiolitis obliterans syndrome. These recommendations include important advancements that could be incorporated in the management of adults with pulmonary cGvHD, primarily aimed at improving and standardising treatment and improving outcomes.

Lymphocyte Depleting and Modulating Therapies for Chronic Lung Allograft Dysfunction

Chronic lung rejection, also called chronic lung allograft dysfunction (CLAD), remains the major hurdle limiting long-term survival after lung transplantation, and limited therapeutic options are available to slow the progressive decline in lung function. Most interventions are only temporarily effective in stabilizing the loss of or modestly improving lung function, with disease progression resuming over time in the majority of patients. Therefore, identification of effective treatments that prevent the onset or halt progression of CLAD is urgently needed. As a key effector cell in its pathophysiology, lymphocytes have been considered a therapeutic target in CLAD. The aim of this review is to evaluate the use and efficacy of lymphocyte depleting and immunomodulating therapies in progressive CLAD beyond usual maintenance immunosuppressive strategies. Modalities used include anti-thymocyte globulin, alemtuzumab, methotrexate, cyclophosphamide, total lymphoid irradiation, and extracorporeal photopheresis, and to explore possible future strategies. When considering both efficacy and risk of side effects, extracorporeal photopheresis, anti-thymocyte globulin and total lymphoid irradiation appear to offer the best treatment options currently available for progressive CLAD patients. SIGNIFICANCE STATEMENT: Effective treatments to prevent the onset and progression of chronic lung rejection after lung transplantation are still a major shortcoming. Based on existing data to date, considering both efficacy and risk of side effects, extracorporeal photopheresis, anti-thymocyte globulin, and total lymphoid irradiation are currently the most viable second-line treatment options. However, it is important to note that interpretation of most results is hampered by the lack of randomized controlled trials.

[Chronic lung allograft dysfunction in 2022, past and updates]

INTRODUCTION

While short-term results of lung transplantation have improved considerably, long-term survival remains below that achieved for other solid organ transplants.

CURRENT KNOWLEDGE

The main cause of late mortality is chronic lung allograft dysfunction (CLAD), which affects nearly half of the recipients 5 years after transplantation. Immunological and non-immune risk factors have been identified. These factors activate the innate and adaptive immune system, leading to lesional and altered wound-healing processes, which result in fibrosis affecting the small airways or interstitial tissue. Several phenotypes of CLAD have been identified based on respiratory function and imaging pattern. Aside from retransplantation, which is possible for only small number of patients, no treatment can reverse the CLAD process.

PERSPECTIVES

Current therapeutic research is focused on anti-fibrotic treatments and photopheresis. Basic research has identified numerous biomarkers that could prove to be relevant as therapeutic targets.

CONCLUSION

While the pathophysiological mechanisms of CLAD are better understood than before, a major therapeutic challenge remains.

Azithromycin ameliorated cigarette smoke-induced airway epithelial barrier dysfunction by activating Nrf2/GCL/GSH signaling pathway

BACKGROUND

Airway epithelium is the first barrier against environmental insults, and epithelial barrier dysfunction caused by cigarette smoke (CS) is particularly relevant to chronic obstructive pulmonary disease (COPD) progression. Our study was to determine whether Azithromycin (AZI) ameliorates CS-induced airway epithelial barrier dysfunction and the underlying mechanisms.

METHODS

Primary bronchial epithelial cells (PBECs), human bronchial epithelial cells (HBECs), Sprague Dawley rats and nuclear factor erythroid 2-related factor 2 (Nrf2)-/- mice were pretreated with AZI and subsequently exposed to CS. Transepithelial electronic resistance (TEER), junction proteins as well as pro-inflammatory cytokines and apoptosis markers were examined to assess epithelial barrier dysfunction. Metabolomics study was applied to explore the underlying mechanism of AZI.

RESULTS

CS-induced TEER decline and intercellular junction destruction, accompanied with inflammatory response and cell apoptosis in PBECs were restored by AZI dose-dependently, which were also observed in CS-exposed rats. Mechanistically, GSH metabolism pathway was identified as the top differentially impacted pathway and AZI treatment upregulated the activities of glutamate cysteine ligase (GCL) and the contents of metabolites in GSH metabolic pathway. Furthermore, AZI apparently reversed CS-induced Nrf2 suppression, and similar effects on airway epithelial barrier dysfunction were also found for Nrf2 agonist tert-butylhydroquinone and vitamin C. Finally, deletion of Nrf2 in both HBECs and C57BL/6N mice aggravated CS-induced GSH metabolism imbalance to disrupt airway epithelial barrier and partially deprived the effects of AZI.

CONCLUSION

These findings suggest that the clinical benefits of AZI for COPD management are related with the protection of CS-induced airway epithelial barrier dysfunction via activating Nrf2/GCL/GSH pathway, providing potential therapeutic strategies for COPD.

Conventional and Novel Approaches to Immunosuppression in Lung Transplantation

Most therapeutic advances in immunosuppression have occurred over the past few decades. Although modern strategies have been effective in reducing acute cellular rejection, excess immunosuppression comes at the price of toxicity, opportunistic infection, and malignancy. As our understanding of the immune system and allograft rejection becomes more nuanced, there is an opportunity to evolve immunosuppression protocols to optimize longer term outcomes while mitigating the deleterious effects of traditional protocols.

Early onset of azithromycin to prevent CLAD in lung transplantation: Promising results of a retrospective single centre experience

INTRODUCTION

Azithromycin (AZI) may be an effective immune modulator in lung transplant (LT) recipients, and can decrease chronic lung allograft dysfunction (CLAD) rates, the leading cause of mortality after the 1st year post-LT. The aim of the study is to assess the effect of AZI initiation and its timing on the incidence and severity of CLAD in LT recipients.

METHODS

Single-center retrospective study, including LT recipients from 01/01/2011 to 30/06/2020. Four groups were established: those who started AZI at the 3rd week post-LT (group A), those who received AZI later than the 3rd week post-LT and had preserved FEV1 (B), those who did not receive AZI (C) and those who started AZI due to a decline in FEV1 (D). The dosage of AZI prescribed was 250 mg three times per week. CLAD was defined and graduated according to the 2019 ISHLT criteria.

RESULTS

We included 358 LT recipients: 139 (38.83%) were in group A, 94 (26.25%) in group B, 91 (25.42%) in group C, and 34 (9.50%) in group D. Group A experienced the lowest CLAD incidence and severity at 1 (p = .01), 3 (p < .001), and 5 years post-LT, followed by Group B. Groups C and D experienced a higher incidence and severity of CLAD (p = .015). Initiation of AZI prior to FEV1 decline (Groups A and B) proved to be protective against CLAD after adjusting for differences between the treatment groups.

CONCLUSIONS

Early initiation of AZI in LT recipients could have a role in decreasing the incidence and severity of CLAD. In addition, as long as FEV1 is preserved, initiating AZI at any time could also be useful to prevent the incidence of CLAD and reduce its severity.

Effect of azithromycin on bronchiolitis obliterans syndrome in posttransplant recipients: A systematic review and meta-analysis

BACKGROUND

Bronchiolitis obliterans syndrome (BOS) is a devastating complication that occurs after transplantation. Although azithromycin is currently used for the treatment of BOS, the evidence is sparse and controversial. The aim of this meta-analysis is to evaluate the effects of azithromycin on forced expiratory volume in 1 second (FEV1) and patient's survival.

METHODS

PubMed, Embase, Cochrane library, Web of Science databases, and the ClinicalTrials.gov registry were systematically searched from inception until December 2020 for relevant original research articles. Random-effects models were used to calculate pooled-effect estimates.

RESULTS

Searches identified 15 eligible studies involving 694 participants. For FEV1 (L), there was a significant increase after short-term (≤12 weeks; P = .00) and mid-term (12-24 weeks; P = .01) administration of azithromycin. For FEV1 (%) compared to baseline, there was a significant increase after short-term (≤12 weeks) administration of azithromycin (P = .02), while there were no statistically significant differences in the medium and long term. When pooled FEV1% was predicted, it exhibited a similar trend to FEV1 (%) compared to baseline. In addition, we discovered that azithromycin reduced the risk of death (hazard ratio = 0.26; 95% confidence interval = 0.17 to 0.40; P = .00) in patients with BOS post-lung transplantation.

CONCLUSIONS

Azithromycin therapy is both effective and safe for lung function improvement in patients with posttransplant BOS after the short- and medium-term administration. Additionally, it has been demonstrated a significant survival benefit among patients with BOS post-lung transplant. Higher quality randomized controlled trials and more extensive prospective cohort studies are needed to confirm the effect of azithromycin on patients with posttransplant BOS.

Ambient Air Pollution and Adverse Waitlist Events Among Lung Transplant Candidates

BACKGROUND

Air pollution is associated with cardiopulmonary disease and death in the general population. Fine particulate matter (PM2.5) is particularly harmful due to its ability to penetrate into areas of gas exchange within the lungs. Persons with advanced lung disease are believed to be particularly susceptible to PM2.5 exposure, but only a few studies have examined the effect of exposure on this population. Here we investigate the association between PM2.5 exposure and adverse waitlist events among lung transplant (LT) candidates.

METHODS

US registry data were used to identify LT candidates listed between January 1, 2010 and December 31, 2016. Annual PM2.5 concentration at year of listing was estimated for each candidate's ZIP Code using National Aeronautics and Space Administration's (NASA) Socioeconomic Data and Applications Center Global Annual PM2.5 Grids. We estimated crude and adjusted hazard ratios for adverse waitlist events, defined as death or removal, using Cox proportional hazards regression.

RESULTS

Of the 15 075 included candidates, median age at listing was 60, 43.8% were female individuals, and 81.7% were non-Hispanic White. Median ZIP Code PM2.5 concentration was 9.06 µg/m3. When compared with those living in ZIP Codes with lower PM2.5 exposure (PM2.5 <10.53 µg/m3), candidates in ZIP Codes in the highest quartile of PM2.5 exposure (≥10.53 µg/m3) had 1.14-fold (95% confidence interval, 1.04-1.25) risk of adverse waitlist events. The result remained significant after adjusting for demographics, education, insurance, smoking, lung allocation score, body mass index, and blood type (hazard ratio, 1.17; 95% confidence interval, 1.07-1.29).

CONCLUSIONS

Elevated ambient PM2.5 concentration was associated with adverse waitlist events among LT candidates. These findings highlight the impact of air pollution on clinical outcomes in this critically ill population.

Long-term, low-dose macrolide antibiotic treatment in pediatric chronic airway diseases

Macrolide antibiotics are one of the most commonly used broad-spectrum antibiotics. They have an inhibitory effect on a variety of respiratory pathogens; besides, they have non-anti-infective effects, including anti-inflammatory, regulating airway secretion, immune regulation, and other effects. A growing number of studies have shown that the non-anti-infective effects of macrolides have important and potential value in the treatment of pediatric chronic airway diseases; the therapy was described as "long-term, low-dose usage"; unfortunately, there is no guideline or consensus that applies to children. To better carry out the mechanism and clinical research of non-anti-infective effect and promote its rational use in children, the authors summarize the evidence of the usage of long-term, low-dose macrolide antibiotic therapy (LLMAT) in the treatment of chronic airway diseases in children and the progress in recent years. IMPACT: This review summarizes the evidence (mostly in recent 5 years) of the usage of long-term, low-dose macrolide antibiotic therapy in the treatment of chronic airway diseases. The recent studies and guidelines support and enrich the point that long-term, low-dose macrolide antibiotic therapy has potential benefit for children with severe asthma, CF, non-CF bronchiectasis, and BO, which provides clinical references and is of clinical interest. Long-term, low-dose macrolide antibiotic therapy has good safety, and no serious events have been reported; however, potential cardiac side effects and macrolide resistance should be clinically noted.

Foregut Dysmotility in the Lung Transplant Patient

PURPOSE OF REVIEW

To explore the role of upper gastrointestinal disease in the clinical course of lung transplant patients - including its pathophysiology, diagnostic testing, and treatment options.

RECENT FINDINGS

Gastroesophageal reflux disease (GERD) and foregut motility disorders are more prevalent among end-stage lung disease patients and are associated with poorer outcomes in lung transplant recipients. A proposed mechanism is the exposure of the lung allograft to aspirated contents, resulting in inflammation and rejection. Diagnostic tools to assess for these disorders include multichannel intraluminal impedance and pH (MII-pH) testing, high resolution esophageal manometry (HREM), and gastric emptying scintigraphy. The main treatment options are medical management with acid suppressants and/or prokinetic agents and anti-reflux surgery. In particular, data support the use of early anti-reflux surgery to improve outcomes. Newer diagnostic tools such as MII-pH testing and HREM allow for the identification of both acid and non-acid reflux and esophageal motility disorders, respectively. Recent studies have demonstrated that early anti-reflux surgery within six months post-transplant better protects against allograft injury and pulmonary function decline when compared to late surgery. However, further prospective research is needed to evaluate the short and long-term outcomes of these diagnostic approaches and interventions.

The macrolide antibiotic azithromycin potently inhibits hepatitis E virus in cell culture models

Hepatitis E virus (HEV) infection in immunocompromised patients, pregnant women and children requires treatment; however, no approved medication is currently available. The macrolide antibiotic azithromycin has been identified as a potent HEV inhibitor. Azithromycin inhibits HEV replication and viral protein expression in multiple cell culture models with genotype 1 and 3 strains. This is largely independent of its induction of an interferon-like response. Because it is safe and cheap, repurposing azithromycin for treating HEV infection is attractive, particularly in resource-limited settings.

Lung Transplantation: CT Assessment of Chronic Lung Allograft Dysfunction (CLAD)

Chronic lung allograft rejection remains one of the major causes of morbi-mortality after lung transplantation. The term Chronic Lung Allograft Dysfunction (CLAD) has been proposed to describe the different processes that lead to a significant and persistent deterioration in lung function without identifiable causes. The two main phenotypes of CLAD are Bronchiolitis Obliterans Syndrome (BOS) and Restrictive Allograft Syndrome (RAS), each of them characterized by particular functional and imaging features. These entities can be associated (mixed phenotype) or switched from one to the other. If CLAD remains a clinical diagnosis based on spirometry, computed tomography (CT) scan plays an important role in the diagnosis and follow-up of CLAD patients, to exclude identifiable causes of functional decline when CLAD is first suspected, to detect early abnormalities that can precede the diagnosis of CLAD (particularly RAS), to differentiate between the obstructive and restrictive phenotypes, and to detect exacerbations and evolution from one phenotype to the other. Recognition of early signs of rejection is crucial for better understanding of physiopathologic pathways and optimal management of patients.

Chronic Lung Allograft Dysfunction: Review of CT and Pathologic Findings

Chronic lung allograft dysfunction (CLAD) is the most common cause of mortality in lung transplant recipients after the 1st year of transplantation. CLAD has traditionally been classified into two distinct obstructive and restrictive forms: bronchiolitis obliterans syndrome and restrictive allograft syndrome. However, CLAD may manifest with a spectrum of imaging and pathologic findings and a combination of obstructive and restrictive physiologic abnormalities. Although the initial CT manifestations of CLAD may be nonspecific, the progression of findings at follow-up should signal the possibility of CLAD and may be present on imaging studies prior to the development of functional abnormalities of the lung allograft. This review encompasses the evolution of CT findings in CLAD, with emphasis on the underlying pathogenesis and pathologic condition, to enhance understanding of imaging findings. The purpose of this article is to familiarize the radiologist with the initial and follow-up CT findings of the obstructive, restrictive, and mixed forms of CLAD, for which early diagnosis and treatment may result in improved survival. Supplemental material is available for this article. © RSNA, 2021.

Plasma Acute Phase Proteins as Predictors of Chronic Lung Allograft Dysfunction in Lung Transplant Recipients

Cumulating reports suggest that acute phase proteins (APPs) have diagnostic and prognostic value in different clinical conditions. Among others, APPs are proposed to serve as markers that help to control the outcome of transplant recipients. Here, we questioned whether plasma concentrations of APPs mirror the development of chronic lung allograft dysfunction (CLAD). We performed blinded analysis of serial plasma samples retrospectively collected from 35 lung transplanted patients, of whom 25 developed CLAD and 10 remained stable during the follow-up period of 3 to 4.5 years. Albumin (ALB), alpha1-antitrypsin (AAT), high sensitivity C-reactive protein (CRPH), antithrombin-3 (AT3), ceruloplasmin (CER), and alpha2-macroglobulin (A2MG) were measured by the nephelometric method. We found that within the first six months post-transplantation, levels of A2MG, CER and AAT were higher in stable patients relative to those who later developed CLAD. Moreover, in stable patient’s plasma CRPH levels decreased during the follow-up period whereas opposite, in those developing CLAD, the CRPH gradually increased. The ALB levels became significantly lower at the end of the follow-up period in CLAD relative to a stable group. A logistic regression model based on A2MG, CER and AT3 at cut-offs levels of ≥175.5 mg/dL, ≥37.8 mg/dL and ≥27.35 mg/dL enabled to discriminate between stable and CLAD patients with a sensitivity of 87.5%, 100% and 62.5%, and specificity of 65.9%, 72.7% and 79.5%, respectively. We identified A2MG (below 175.5 mg/dL) as an independent predictor of CLAD (hazard ratio 11.5, 95% CI (1.5–91.3), p<0.021). Our findings suggest that profiles of certain APPs may help to predict the development of lung dysfunction at the very early stages after transplantation.

Azithromycin Partially Mitigates Dysregulated Repair of Lung Allograft Small Airway Epithelium

BACKGROUND

Dysregulated airway epithelial repair following injury is a proposed mechanism driving posttransplant bronchiolitis obliterans (BO), and its clinical correlate bronchiolitis obliterans syndrome (BOS). This study compared gene and cellular characteristics of injury and repair in large (LAEC) and small (SAEC) airway epithelial cells of transplant patients.

METHODS

Subjects were recruited at the time of routine bronchoscopy posttransplantation and included patients with and without BOS. Airway epithelial cells were obtained from bronchial and bronchiolar brushing performed under radiological guidance from these patients. In addition, bronchial brushings were also obtained from healthy control subjects comprising of adolescents admitted for elective surgery for nonrespiratory-related conditions. Primary cultures were established, monolayers wounded, and repair assessed (±) azithromycin (1 µg/mL). In addition, proliferative capacity as well as markers of injury and dysregulated repair were also assessed.

RESULTS

SAEC had a significantly dysregulated repair process postinjury, despite having a higher proliferative capacity than large airway epithelial cells. Addition of azithromycin significantly induced repair in these cells; however, full restitution was not achieved. Expression of several genes associated with epithelial barrier repair (matrix metalloproteinase 7, matrix metalloproteinase 3, the integrins β6 and β8, and β-catenin) were significantly different in epithelial cells obtained from patients with BOS compared to transplant patients without BOS and controls, suggesting an intrinsic defect.

CONCLUSIONS

Chronic airway injury and dysregulated repair programs are evident in airway epithelium obtained from patients with BOS, particularly with SAEC. We also show that azithromycin partially mitigates this pathology.

Reducing the Fatality Rate of COVID-19 by Applying Clinical Insights From Immuno-Oncology and Lung Transplantation

There is an urgent need to identify effective strategies that can stop or reverse the inflammatory process that causes acute lung injury, ARDS, and multi-organ failure in COVID-19. Adaptive clinical trials with parallel enrollment to different arms each evaluating a rationally designed combination modality could provide the foundation for the accelerated identification of effective and safe multi-modality treatment algorithms for COVID-19 pneumonia. This article summarizes the insights and lessons learned from clinical immune-oncology trials as well as lung transplantation that are informing the clinical development of promising new strategies aimed at reducing the fatality rate in COVID-19.

Immunosuppressive strategies in lung transplantation

Lung transplantation is a viable option for those with end-stage lung disease which is evidenced by the continued increase in the number of lung transplantations worldwide. However, patients and clinicians are constantly faced with acute and chronic rejection, infectious complications, drug toxicities, and malignancies throughout the lifetime of the lung transplant recipient. Conventional maintenance immunosuppression therapy consisting of a calcineurin inhibitor (CNI), anti-metabolite, and corticosteroids have become the standard regimen but newer agents and modalities continue to be developed. Here we will review induction agents, maintenance immunosuppressives, adjunctive therapies and other strategies to improve long-term outcomes.

Influence of azithromycin and allograft rejection on the post-lung transplant microbiota

BACKGROUND

Alterations in the lung microbiota may drive disease development and progression in patients with chronic respiratory diseases. Following lung transplantation (LTx), azithromycin is used to both treat and prevent chronic lung allograft dysfunction (CLAD). The objective of this study was to determine the association between azithromycin use, CLAD, acute rejection, airway inflammation, and bacterial microbiota composition and structure after LTx.

METHODS

Bronchoalveolar lavage samples (n = 219) from 69 LTx recipients (azithromycin, n = 32; placebo, n = 37) from a previously conducted randomized placebo-controlled trial with azithromycin were analyzed. Samples were collected at discharge, 1, and 2 years following randomization and at CLAD diagnosis. Bacterial microbial community composition and structure was determined using 16S ribosomal RNA gene sequencing and associated with clinically important variables.

RESULTS

At discharge and following 1 and 2 years of azithromycin therapy, no clear differences in microbial community composition or overall diversity were observed. Moreover, no changes in microbiota composition were observed in CLAD phenotypes. However, acute rejection was associated with a reduction in community diversity (p = 0.0009). Significant correlations were observed between microbiota composition, overall diversity, and levels of inflammatory cytokines in bronchoalveolar lavage, particularly CXCL8.

CONCLUSIONS

Chronic azithromycin usage did not disturb the bacterial microbiota. However, acute rejection episodes were associated with bacterial dysbiosis.

Poly(lactide-co-glycolide) grafted hyaluronic acid-based electrospun fibrous hemostatic fragments as a sustainable anti-infection and immunoregulation material

Poly(lactide-co-glycolide) (PLGA) copolymers are promising synthetic materials in the biomedical field. However, in wound management, their hydrophobic properties limit their further application because of their poor adhesion to the surface of moist wounds. Furthermore, the lack of hemostatic materials with sustainable anti-infection and immunoregulation functions remains a highly significant clinical problem, as commercially available hemostatic products, such as Arista™, Celox™ and QuikClot™, do not have sufficient infection prevention and immunoregulation properties. Herein, we employ electrospinning, ammonia dissociation and surface grafting techniques to develop a series of PLGA-based hemostatic materials, including a PLGA electrospun fibrous membrane, PLGA-NH2 fibrous particles and PLGA-hyaluronic acid fibrous fragments (PLGA-HA FFs). Notably, we load azithromycin on the PLGA-HA FFs to endow them with anti-infection and immunoregulation properties. The hemostatic mechanism analysis demonstrates that the PLGA-HA FFs show superior hemostasis performance compared to traditional gauzes. The results show that the PLGA-HA FFs can act as a versatile platform with high encapsulation of azithromycin (83.03% ± 2.81%) and rapid hemostasis (28 ± 2 s) as well as prominent cytocompatibility towards L929 cells, RAW 264.7 cells and red blood cells. We believe that the current research proposes a possible strategy to synthesize materials that achieve not only safe and effective hemostasis, but also have anti-infection and immunoregulation properties for the development of further hemostatic products.

Disease severity, debridement approach and timing of drug modify outcomes of adjunctive azithromycin in non-surgical management of chronic periodontitis: a multivariate meta-analysis

Background

Past meta-analyses have shown adjunctive systemic Azithromycin (AZI) to provide minor clinical benefits in scaling and root surface debridement (S/RSD). However, these have not considered the covariance of key outcome parameters; probing pocket depth (PPD) and Clinical Attachment Level (CAL) or systematically examined some potential sources of heterogeneity.

Aim

To jointly synthesize 6-month outcomes of systemic AZI as adjunctive to S/RSD in chronic periodontitis and investigate 3 potential sources of heterogeneity.

Methods

Four databases were searched for suitable randomized controlled clinical trials (RCTs). Standardized mean differences (SMD) in PPD and CAL between AZI + S/RSD and S/RSD alone, at 6-month follow-up were computed. Within-study covariances of PPD and CAL were derived from reported multiple time-point data. A multivariate meta-analysis with random effects jointly modelled PPD and CAL, factoring in their covariance. This model included 3 moderators with interaction effects; timing of AZI initiation (pre-therapy/post-therapy), type of S/RSD [full-mouth debridement (FMD)/partial-mouth debridement (PMD)], and baseline study-level mean values of PPD/CAL.

Results

Among 276 abstracts, 11 observations from 9 RCTs qualified for meta-analysis. Within-study correlation-coefficients of PPD with CAL significantly increased with increasing study-level baseline mean values (Spearman’s r = 0.79, p < 0.01). The full multivariate meta-analysis model showed significant effects for the 3 moderators (Q statistic = 150.03, p < 0.01), retained significant residual heterogeneity (Q statistic = 88.50, p < 0.01) but outperformed (Likelihood- ratio statistic = 102.95, p < 0.01,) a null-model with no moderators (Q statistic = 201.5, p < 0.01). A significant effect was seen only on the SMD for PPD (estimate = 1.16 mm, 95% CI: 0.27 mm–2.07 mm mm, p = 0.01) but not CAL (estimate = 0.17 mm, 95% CI: -0.92 mm-1.26 mm, p = 0.76). SMD in PPD positively interacted with study baseline value (estimate = 0.11, 95% CI: 0.08–0.15, p < 0.01). Significant negative interactions of SMD in PPD with PMD (estimate = − 1.25 mm, 95% CI: -1.73 mm- -0.78 mm, p < 0.01) and pre-therapy drug initiation (estimate = − 1.18 mm, 95% CI: -1.48 mm--0.87 mm, p < 0.01) were evident.

Conclusion

Joint synthesis of PPD and CAL showed, at 6-months, AZI + S/RSD provided a benefit over S/RSD alone for PPD alone when correlation with CAL was accounted for. Deeper study-level baseline PPD, FMD type of S/RSD, and post-therapy drug initiation associated with greater PPD reduction.

Electronic supplementary material

The online version of this article (10.1186/s12903-019-0754-0) contains supplementary material, which is available to authorized users.

Diagnosis, Pathophysiology and Experimental Models of Chronic Lung Allograft Rejection

Chronic rejection is the Achilles heel of modern lung transplantation, characterized by a slow, progressive decline in allograft function. Clinically, this manifests as obstructive disease, restrictive disease, or a mixture of the 2 depending on the underlying pathology. The 2 major phenotypes of chronic rejection include bronchiolitis obliterans syndrome and restrictive allograft syndrome. The last decade of research has revealed that each of these phenotypes has a unique underlying pathophysiology which may require a distinct treatment regimen for optimal control. Insights into the intricate alloimmune pathways contributing to chronic rejection have been gained from both large and small animal models, suggesting directions for future research. In this review, we explore the pathological hallmarks of chronic rejection, recent insights gained from both clinical and basic science research, and the current state of animal models of chronic lung rejection.

Current and future pharmacotherapy options for non-cystic fibrosis bronchiectasis

INTRODUCTION

In recent years, there has been an increasing number of clinical trials investigating the effect of pharmacological treatments on patients with bronchiectasis. Areas covered: This review provides an overview of current drugs used in bronchiectasis patients as well as those that could make a future contribution to the management of this disease. Expert commentary: Bronchiectasis is a very heterogeneous disease, so it can be studied from a phenotypic standpoint and its pathophysiological mechanisms (endotypes) can be defined. This provides an interesting field of research as it enables the identification of patients suitable for inclusion in specific clinical trials on new drugs.

High-Resolution CT Findings of Obstructive and Restrictive Phenotypes of Chronic Lung Allograft Dysfunction: More Than Just Bronchiolitis Obliterans Syndrome

OBJECTIVE

The purpose of this article is to review the high-resolution CT characteristics of individual obstructive and restrictive chronic lung allograft dysfunction (CLAD) phenotypes to aid in making accurate diagnoses and guiding treatment.

CONCLUSION

Long-term survival and function after lung transplant are considerably worse compared with after other organ transplants. CLAD is implicated as a major limiting factor for long-term graft viability. Historically thought to be a single entity, bronchiolitis obliterans syndrome, CLAD is actually a heterogeneous group of disorders with distinct subtypes.

Immunomodulatory Cell Therapy to Target Cystic Fibrosis Inflammation

Cystic fibrosis (CF) is associated with exaggerated and prolonged inflammation in the lungs, which contributes to lung injury, airway mucus obstruction, bronchiectasis, and loss of lung function. This hyperinflammatory phenotype appears to be caused by an imbalance between the pro- and antiinflammatory regulatory pathways, with heightened proinflammatory stimuli, a decreased counter-regulatory response, and reduced effectiveness of immune cell function and inflammatory resolution. Thus, therapies that can target this inflammatory environment would have a major impact on preventing the progression of lung disease. Because of the complex phenotype of CF inflammation, current antiinflammatory regimens have proven to be inadequate for the targeting of these multiple dysregulated pathways and effects. Several approaches using cell therapies have shown potential therapeutic benefit for the treatment of CF inflammation. This review provides an overview of the immune dysfunctions in CF and current therapeutic regimens; explores the field of cell therapy as a treatment for CF inflammation; and focuses on the various cell types used, their immunomodulatory functions, and the current approaches to mitigate the inflammatory response and reduce the long-term damage for patients with CF.

Prevention of chronic rejection after lung transplantation

Long-term survival after lung transplantation (LTx) is limited by chronic rejection (CR). Therapeutic strategies for CR have been largely unsuccessful, making prevention of CR an important and challenging therapeutic approach. In the current review, we will discuss current clinical evidence regarding prevention of CR after LTx.

Follicular bronchiolitis in an HIV-infected individual on combination antiretroviral therapy with low CD4+ cell count but sustained viral suppression

A 36-year-old Danish man, living in Asia, was diagnosed with Pneumocystis pneumonia (PCP) and HIV in 2013 (CD4+ count: 6 cells/µL; viral load: 518 000 copies/mL). He initiated combination antiretroviral therapy. Later that year, he was also diagnosed with granulomatosis with polyangiitis and was treated with prednisolone. Despite complete viral suppression and increasing CD4+ count (162 cells/µL), he was readmitted with PCP in April 2015. Subsequently, he returned to Denmark (CD4+ count: 80 cells/µL, viral suppression). Over the following months, he developed progressive dyspnoea. Lung function tests demonstrated severely reduced lung capacity with an obstructive pattern and a moderately reduced diffusion capacity. High resolution computer tomography revealed minor areas with tree-in-bud pattern and no signs of air trapping on expiratory views. Lung biopsy showed lymphocytic infiltration surrounding the bronchioles with sparing of the alveolar septa. He was diagnosed with follicular bronchiolitis. The patient spontaneously recovered along with an improvement of the immune system.

Azithromycin attenuates acute radiation-induced lung injury in mice

Radiation-induced lung injury (RILI) is a common and major obstacle in thoracic cancer radiotherapy, resulting in considerable morbidity and limiting the dose of radiation. However, an effective treatment option remains to be established. Therefore, the present study aimed to investigate the effects of azithromycin (AZM) in acute RILI with a mouse model. In the present study, C57BL/6 mice were given a single thoracic irradiation of 16 Gy and administered orally with AZM. The lung histopathological findings, the levels of malondialdehyde (MDA; an indicator of oxidative damage) and the concentration of pro-inflammatory and pro-fibrotic cytokines in plasma were assessed on 28 day following irradiation. In addition, the total cell counts in bronchoalveolar lavage fluid (BALF), the pro-inflammatory and pro-fibrotic cytokine gene expression in lung tissue were evaluated on day 7, 14 and 28 following irradiation. Administration with AZM markedly alleviated acute RILI as indicated by hematoxylin and eosin and Masson staining. The levels of MDA and total cell counts in BALF significantly reduced in AZM treated mice. AZM also down-regulated the concentration and mRNA expression of interleukin (IL)-1β, IL-6, tumor necrosis factor-α and transforming growth factor-β1. In addition, AZM attenuated the irradiation-induced increases in the mRNA expression of fibrotic markers (α-smooth muscle actin and α-1 type I collagen). AZM treatment mitigated the radiation-induced acute lung injury possibly by its anti-inflammatory and anti-fibrotic effects.

Effect of Azithromycin on Airflow Decline-Free Survival After Allogeneic Hematopoietic Stem Cell Transplant: The ALLOZITHRO Randomized Clinical Trial

IMPORTANCE

Bronchiolitis obliterans syndrome has been associated with increased morbidity and mortality after allogeneic hematopoietic stem cell transplant (HSCT). Previous studies have suggested that azithromycin may reduce the incidence of post-lung transplant bronchiolitis obliterans syndrome.

OBJECTIVE

To evaluate if the early administration of azithromycin can improve airflow decline-free survival after allogeneic HSCT.

DESIGN, SETTING, AND PARTICIPANTS

The ALLOZITHRO parallel-group trial conducted in 19 French academic transplant centers and involving participants who were at least 16 years old, had undergone allogeneic HSCT for a hematological malignancy, and had available pretransplant pulmonary function test results. Enrollment was from February 2014 to August 2015 with follow-up through April 26, 2017.

INTERVENTIONS

Patients were randomly assigned to receive 3 times a week either 250 mg of azithromycin (n = 243) or placebo (n = 237) for 2 years, starting at the time of the conditioning regimen.

MAIN OUTCOMES AND MEASURES

The primary efficacy end point was airflow decline-free survival at 2 years after randomization. Main secondary end points were overall survival and bronchiolitis obliterans syndrome at 2 years.

RESULTS

Thirteen months after enrollment, the independent data and safety monitoring board detected an unanticipated imbalance across blinded groups in the number of hematological relapses, and the treatment was stopped December 26, 2016. Among 480 randomized participants, 465 (97%) were included in the modified intention-to-treat analysis (mean age, 52 [SD, 14] years; 75 women [35%]). At the time of data cutoff, 104 patients (22%; 54 azithromycin vs 50 placebo) had experienced an airflow decline; 138 patients (30%) died (78 azithromycin vs 60 placebo). Two-year airflow decline-free survival was 32.8% (95% CI, 25.9%-41.7%) with azithromycin and 41.3% (95% CI, 34.1%-50.1%) with placebo (unadjusted hazard ratio [HR], 1.3; 95% CI, 1.02-1.70; P = .03). Of the 22 patients (5%) who experienced bronchiolitis obliterans syndrome, 15 (6%) were in the azithromycin group and 7 (3%) in the placebo group (P = .08). The azithromycin group had increased mortality, with a 2-year survival of 56.6% (95% CI, 50.2%-63.7%) vs 70.1% (95% CI, 64.2%-76.5%) in the placebo group (unadjusted HR, 1.5; 95% CI, 1.1-2.0; P = .02). In a post hoc analysis, the 2-year cumulative incidence of hematological relapse was 33.5% (95% CI, 27.3%-39.7%) with azithromycin vs 22.3% (95% CI, 16.4%-28.2%) with placebo (unadjusted cause-specific HR, 1.7; 95% CI, 1.2-2.4; P = .002).

CONCLUSIONS AND RELEVANCE

Among patients undergoing allogeneic HSCT for hematological malignancy, early administration of azithromycin resulted in worse airflow decline-free survival than did placebo; these findings are limited by early trial termination. The potential for harm related to relapse requires further investigation.

TRIAL REGISTRATION

clinicaltrials.gov Identifier: NCT01959100.

Repeated systemic administration of adipose tissue-derived mesenchymal stem cells prevents tracheal obliteration in a murine model of bronchiolitis obliterans

OBJECTIVE

To investigate the effect of adipose tissue-derived mesenchymal stem cell (ASC) administered either systemically or locally in a murine model of bronchiolitis obliterans.

RESULTS

When compared to controls, systemic treatment with 10⁶ ASCs on D0 and a second dose on D7 significantly prevented tracheal obliteration 28 days after heterotopic tracheal transplantation (median of 94 vs. 16%; P < 0.01). A single dose tended towards less stenosis than controls, but did not reach statistical significance (28 vs. 94%; P = 0.054). On the contrary, repeated local injection was incapable of preventing tracheal obliteration when compared to a single injection or controls (37 vs. 71 vs. 87%). Two intravenous doses also tended to be better than two local injections (16 vs. 37%; P = 0.058), and were better than a single local dose (16 vs. 71%; P < 0.01).

CONCLUSION

A second dose of ASC, given systemically after 7 days, reduces luminal obliteration in a heterotopic tracheal transplantation model in mice, suggesting that ASC can be used to prevent obliterative bronchiolitis after lung transplantation.

Antimicrobial and Immunomodulatory Surface-Functionalized Electrospun Membranes for Bone Regeneration

Guided bone regeneration (GBR) is a surgical procedure utilizing occlusive membranes for providing space maintenance and enabling selective repopulation of the damaged area. While this technique is effective in regenerating bone, bacterial infiltration occurs frequently and can compromise the regenerative outcome. In this study, the authors describe the development and characterization of a GBR membrane made of medical grade polycaprolactone (mPCL) electrospun fibers with antibacterial and immunomodulatory properties. This is achieved by the immobilization of the antibiotic azithromycin into the membrane via a solvent evaporation technique leading to a sustained release of the drug over 14 d. In vitro testing shows that this controlled release of azithromycin is proficient at inhibiting the growth of Staphylococcus aureus for 14 d. Implantation of azithromycin loaded mPCL membrane in a rodent calvarial defect induces macrophage polarization toward the M2 phenotype after one week and results in significantly more bone regeneration eight weeks post-surgery. The results suggest that this antibacterial membrane should be effective at preventing infection and also impacts on the macrophage polarization enhancing bone regeneration. The drug loading technique developed in this study is simple, effective with a strong potential for clinical translation and can be applied to different types of scaffolds and implants for applications in craniofacial and orthopedics applications.

Update on Chronic Lung Allograft Dysfunction

Chronic lung allograft dysfunction (CLAD) encompasses a range of pathologies that cause a transplanted lung to not achieve or maintain normal function. CLAD manifests as airflow restriction and/or obstruction and is predominantly a result of chronic rejection. Three distinct phenotypes of chronic rejection are now recognized: bronchiolitis obliterans, neutrophilic reversible allograft dysfunction, and restrictive allograft syndrome. Recent investigations have revealed that each phenotype has a unique pathology and histopathological findings, suggesting that treatment regimens should be tailored to the underlying etiology. CLAD is poorly responsive to treatment once diagnosed, and therefore the prevention of the factors that predispose a patient to develop CLAD is critically important. Small and large animal models have contributed significantly to our understanding of CLAD and more studies are needed to develop treatment regimens that are effective in humans.

The Belgian trial with azithromycin for acute COPD exacerbations requiring hospitalization: an investigator-initiated study protocol for a multicenter, randomized, double-blind, placebo-controlled trial

Background

Long-term use of macrolide antibiotics is effective to prevent exacerbations in chronic obstructive pulmonary disease (COPD). As risks and side effects of long-term intervention outweigh the benefits in the general COPD population, the optimal dose, duration of treatment, and target population are yet to be defined. Hospitalization for an acute exacerbation (AE) of COPD may offer a targeted risk group and an obvious risk period for studying macrolide interventions.

Methods/design

Patients with COPD, hospitalized for an AE, who have a smoking history of ≥10 pack-years and had ≥1 exacerbation in the previous year will be enrolled in a multicenter, randomized, double-blind, placebo-controlled trial (NCT02135354). On top of a standardized treatment of systemic corticosteroids and antibiotics, subjects will be randomized to receive either azithromycin or placebo during 3 months, at an uploading dose of 500 mg once a day for 3 days, followed by a maintenance dose of 250 mg once every 2 days. The primary endpoint is the time-to-treatment failure during the treatment phase (ie, from the moment of randomization until the end of intervention). Treatment failure is a novel composite endpoint defined as either death, the admission to intensive care or the requirement of additional systemic steroids or new antibiotics for respiratory reasons, or the diagnosis of a new AE after discharge.

Discussion

We investigate whether azithromycin initiated at the onset of a severe exacerbation, with a limited duration and at a low dose, might be effective and safe in the highest risk period during and immediately after the acute event. If proven effective and safe, this targeted approach may improve the treatment of severe AEs and redirect the preventive use of azithromycin in COPD to a temporary intervention in the subgroup with the highest unmet needs.

Chronic lung allograft dysfunction: evolving practice

PURPOSE OF REVIEW

Chronic lung allograft dysfunction (CLAD) was recently introduced as an overarching term covering different phenotypes of chronic allograft dysfunction, including obstructive CLAD (bronchiolitis obliterans syndrome), restrictive CLAD (restrictive allograft syndrome) and graft dysfunction due to causes not related to chronic rejection. In the present review, we will highlight the latest insights and current controversies regarding the new CLAD terminology, underlying pathophysiologic mechanisms, diagnostic approach and possible treatment options.

RECENT FINDINGS

Different pathophysiological mechanisms are clearly involved in clinically distinct phenotypes of chronic rejection, as is reflected by differences in histology, allograft function and imaging. Therefore, not all CLAD patients may equally benefit from specific therapies.

SUMMARY

The recent introduction of CLAD importantly changed the clinical practice in lung transplant recipients. Given the relative low accuracy of the current diagnostic tools, future research should focus on specific biomarkers, more sensitive pulmonary function parameters and imaging techniques for timely CLAD diagnosis and phenotyping. Personalized or targeted therapeutic options for adequate prevention and treatment of CLAD are required.

Lung Transplantation

The therapeutic options for patients with advanced pulmonary parenchymal or vascular disorders are currently limited. Lung transplantation remains one of the few viable interventions, but on account of the insufficient donor pool only a minority of these patients actually undergo the procedure each year. Following transplantation there are a number of early and late allograft complications such as primary graft dysfunction, allograft rejection, infection, post-transplant lymphoproliferative disorder and late injury that is now classified as chronic lung allograft dysfunction. The pathologist plays an essential role in the diagnosis and classification of these myriad complications. Although the transplant procedures are performed in selected centers patients typically return to their local centers. When complications arise it is often the responsibility of the local pathologist to evaluate specimens. Therefore familiarity with the pathology of lung transplantation is important.

Prophylactic Azithromycin Therapy After Lung Transplantation: Post hoc Analysis of a Randomized Controlled Trial

Prophylactic azithromycin treatment has been demonstrated to improve freedom from bronchiolitis obliterans syndrome (BOS) 2 years after lung transplantation (LTx). In the current study, we re-evaluated the long-term effects of this prophylactic approach in view of the updated classification system for chronic lung allograft dysfunction (CLAD). A retrospective, intention-to-treat analysis of a randomized controlled trial comparing prophylactic treatment with placebo (n = 43) versus azithromycin (n = 40) after LTx was performed. Graft dysfunction (CLAD), graft loss (retransplantation, mortality), evolution of pulmonary function and functional exercise capacity were analyzed 7 years after inclusion of the last study subject. Following LTx, 22/43 (51%) patients of the placebo group and 11/40 (28%) patients of the azithromycin group ever developed CLAD (p = 0.043). CLAD-free survival was significantly longer in the azithromycin group (p = 0.024). No difference was present in proportion of obstructive versus restrictive CLAD between both groups. Graft loss was similar in both groups: 23/43 (53%) versus 16/40 (40%) patients (p = 0.27). Long-term pulmonary function and functional exercise capacity were significantly better in the azithromycin group (p < 0.05). Prophylactic azithromycin therapy reduces long-term CLAD prevalence and improves CLAD-free survival, pulmonary function, and functional exercise capacity after LTx.

Azithromycin use and outcomes in severe sepsis patients with and without pneumonia

PURPOSE

Studies investigating the association between macrolides and outcomes in both pulmonary and nonpulmonary critically ill patients are limited. We aimed to examine the association between azithromycin use and clinical outcomes in severe sepsis patients with and without pneumonia receiving mechanical ventilation.

MATERIALS AND METHODS

A retrospective cohort of 105 patients admitted to an adult intensive care unit (ICU) with severe sepsis in an urban university hospital were included in the study. Multivariable linear regression was performed to assess the relationship between azithromycin use and the following outcomes: 28-day ICU-free days and 28-day ventilator-free days.

RESULTS

In univariate analysis, patients receiving azithromycin had nearly 6 more ICU-free days on average than did patients not receiving azithromycin (P = .005). The increased ICU-free days remained in multivariable analysis adjusting for age, sex, race, ICU type, and presence of shock (P = .005). In stratified analysis examining the association of azithromycin use in severe sepsis patients without pneumonia (n = 74), the results were similar to the full cohort.

CONCLUSION

Azithromycin was associated with more ICU-free days in severe sepsis patients with and without pneumonia. Further investigations are warranted to better elicit the association of macrolide use on clinical outcomes in severe sepsis patients, especially those without pneumonia.

Use of macrolides in lung diseases: recent literature controversies

OBJECTIVE

To review the mechanisms of action of macrolides in pediatric respiratory diseases and their clinical indications.

SOURCES

Review in the PubMed database, comprising the following terms in English: "macrolide and asthma"; "macrolide and cystic fibrosis"; "macrolide bronchiolitis and viral acute"; "macrolide and bronchiolitis obliterans" and "macrolide and non-CF bronchiectasis".

SUMMARY OF THE FINDINGS

The spectrum of action of macrolides includes production of inflammatory mediators, control of mucus hypersecretion, and modulation of host-defense mechanisms. The potential benefit of macrolide antibiotics has been studied in a variety of lung diseases, such as cystic fibrosis (CF), bronchiectasis, asthma, acute bronchiolitis, and non-CF bronchiectasis. Several studies have evaluated the benefits of macrolides in asthma refractory to therapy, but the results are controversial and indications should be limited to specific phenotypes. In viral bronchiolitis, there is no consistent benefit in acute conditions, although recent data have shown an effect in recurrent wheezing prevention. In patients with CF results are also contradictory, but the consensus states there is a small clinical benefit, especially for patients infected with P. aeruginosa. There was also no positive action of macrolides in patients with post-infectious bronchiolitis obliterans. Children with non-CF bronchiectasis seem to have clear benefits regarding the use of macrolides, which showed clinical advantages in parenchyma protection and lung function.

CONCLUSIONS

The long-term use of macrolides should be limited to highly selected situations, especially in patients with bronchiectasis. Careful evaluation of the benefits and potential damage are tools for their indication in specific groups.

Molecular Profiling in Lung Biopsies of Human Pulmonary Allografts to Predict Chronic Lung Allograft Dysfunction

Chronic lung allograft dysfunction (CLAD) is the main reason for poor long-term outcome of lung transplantation, with bronchiolitis obliterans (BO) representing the predominant pathological feature. BO is defined as a progressive fibrous obliteration of the small airways, thought to be triggered by a combination of nonimmune bronchial injury and alloimmune and autoimmune mechanisms. Because biopsy samples are too insensitive to reliably detect BO and a decline in lung function test results, which is clinically used to define CLAD, does not detect early stages, there is need for alternative biomarkers for early diagnosis. Herein, we analyzed the cellular composition and differential expression of 45 tissue remodeling-associated genes in transbronchial lung biopsy specimens from two cohorts with 18 patients each: patients who did not develop CLAD within 3 years after transplantation (48 biopsy specimens) and patients rapidly developing CLAD within the first 3 postoperative years (57 biopsy specimens). Integrating the mRNA expression levels of the five most significantly dysregulated genes from the transforming growth factor-β axis (BMP4, IL6, MMP1, SMAD1, and THBS1) into a score, patient groups could be confidently separated and the outcome predicted (P < 0.001). We conclude that overexpression of fibrosis-associated genes may be valuable as a tissue-based molecular biomarker to more accurately diagnose or predict the development of CLAD.

[Gastro-esophageal reflux and chronic respiratory diseases]

Gastroesophageal reflux disease (GERD) frequently occurs in association with chronic respiratory diseases although the casual link is not always clear. Several pathophysiological and experimental factors are considered to support a role for GERD in respiratory disease. Conversely, respiratory diseases and bronchodilator treatment can themselves exacerbate GERD. When cough or severe asthma is being investigated, GERD does not need to be systematically looked for and a therapeutic test with proton pump inhibitors is not always recommended. pH impedance monitoring is now the reference diagnostic tool to detect non acid reflux, a form of reflux for which proton pump inhibitor treatment is ineffective. Recent data have shown a potential role of GERD in idiopathic pulmonary fibrosis and bronchiolitis obliterans following lung transplantation, leading to discussions about the place of surgery in this context. However, studies using pH impedance monitoring are still needed to better understand and manage the association between GERD and chronic respiratory diseases.

Current views on chronic rejection after lung transplantation

Chronic lung allograft dysfunction (CLAD) was recently introduced as an overarching term mainly to classify patients with chronic rejection after lung transplantation, although other conditions may also qualify for CLAD. Initially, only the development of a persistent and obstructive pulmonary function defect, clinically identified as bronchiolitis obliterans syndrome (BOS), was considered as chronic rejection, if no other cause could be identified. It became clear in recent years that some patients do not qualify for this definition, although they developed a chronic and persistent decrease in FEV1 , without another identifiable cause. As the pulmonary function decline in these patients was rather restrictive, this was called restrictive allograft syndrome (RAS). In the present review, we will further elaborate on these two CLAD phenotypes, with specific attention to the diagnostic criteria, the role of pathology and imaging, the risk factors, outcome, and the possible treatment options.

Clinical features of post-infectious bronchiolitis obliterans in children undergoing long-term azithromycin treatment

The aim of the present study was to outline any predisposing factors and clinical and radiological features of post-infectious bronchiolitis obliterans (PIBO) in pediatric patients, and to determine the effect of long-term azithromycin treatment on these factors. In total, 16 cases of children with PIBO were retrospectively reviewed. Adenovirus and Mycoplasma pneumoniae were the most common etiological agents (12/16) in the children with PIBO. The patients presented with persistent dyspnea, a chronic cough, sputum production and wheezing following the initial lung infection. Chest X-rays indicated pulmonary overinflation and patchy ground-glass opacity. In addition, high-resolution computed tomography (HRCT) scans revealed patchy ground-glass opacity, bronchiectasis, bronchial wall thickening and mosaic perfusion in all 16 cases. A unilateral hyperlucent lung was observed in two cases. All the patients underwent treatment with low-dose azithromycin and prednisone. Follow-up examinations of the 16 cases, varying in duration between 7 and 31 months, showed that the disease condition had improved in 10 cases. However, no significant improvements were identified from the HRCT scans or were observed in the patient condition in the additional six cases. The diagnosis of BO is primarily based on a typical clinical presentation and HRCT observations. Therefore, a typical clinical history and patchy ground-glass opacity features on HRCT scans are screening indices that predict BO development. Steroids are the cornerstone of BO treatment; however, long-term azithromycin treatment can improve the condition of the patients. In summary, PIBO is a disease with a high morbidity rate and should be treated by a multidisciplinary team. Patients should receive follow-up examination for an extended period. Patchy ground-glass opacity features on HRCT scans indicate that clinical suspicion of BO is necessary in children with persistent and severe wheezing.