Azithromycin reduces airway neutrophilia and interleukin-8 in patients with bronchiolitis obliterans syndrome

Azithromycin for Preventing Bronchopulmonary Dysplasia in Extremely Preterm Infants: A Cohort Study

OBJECTIVES

To test the effect of azithromycin in reducing bronchopulmonary dysplasia (BPD) risk in extremely preterm infants (EPI) without pulmonary infection.

STUDY DESIGN

A retrospective cohort study was performed in EPI in a tertiary unit from September 2018 to September 2022. Since only Ureaplasma species positive infants were treated with azithromycin, we included infants without Ureaplasma species (no azithromycin treatment) and those diagnosed with Ureaplasma species colonization (azithromycin treatment) in the study, while infants with Ureaplasma species pneumonia were excluded. The primary outcome was grade II+ BPD, defined as BPD of grade II or higher according to the updated NICHD criteria (2018). Multiple logistic regression analysis was used to identify the independent association between grade II+ BPD and azithromycin treatment.

RESULTS

A total of 237 EPIs were included in the current study, of which 202 infants were classified as no azithromycin treatment (Ureaplasma species negative) and 35 infants were classified as azithromycin treatment (Ureaplasma species colonization). Clinical characteristics were similar between groups. Infants treated with azithromycin had a significantly lower rate of grade II+ BPD (8.6% vs. 31.2%, p = 0.006), and shorter duration of invasive ventilation (0 vs. 3 days, p = 0.045) compared to untreated ones. After adjusting for confounders, azithromycin treatment was significantly associated with reduced risk of grade II+ BPD in the whole cohort (odd ratio [OR] 0.211, 95% CI: 0.056, 0.786, p = 0.020], and infants absent of other pulmonary infection (OR 0.115, 95% CI: 0.014, 0.979, p = 0.048).

CONCLUSION

Azithromycin is associated with a reduced risk of grade II+ BPD in EPIs, likely due to its anti-inflammatory effect.

Immune dysregulation as a driver of bronchiolitis obliterans

Bronchiolitis obliterans (BO) is a disease characterized by airway obstruction and fibrosis that can occur in all age groups. Bronchiolitis obliterans syndrome (BOS) is a clinical manifestation of BO in patients who have undergone lung transplantation or hematopoietic stem cell transplantation. Persistent inflammation and fibrosis of small airways make the disease irreversible, eventually leading to lung failure. The pathogenesis of BO is not entirely clear, but immune disorders are commonly involved, with various immune cells playing complex roles in different BO subtypes. Accordingly, the US Food and Drug Administration (FDA) has recently approved several new drugs that can alleviate chronic graft-versus-host disease (cGVHD) by regulating the function of immune cells, some of which have efficacy specifically with cGVHD-BOS. In this review, we will discuss the roles of different immune cells in BO/BOS, and introduce the latest drugs targeting various immune cells as the main target. This study emphasizes that immune dysfunction is an important driving factor in its pathophysiology. A better understanding of the role of the immune system in BO will enable the development of targeted immunotherapies to effectively delay or even reverse this condition.

Heterogeneous neutrophils in lung transplantation and proteolytic CXCL8 activation in COVID-19, influenza and lung transplant patient lungs

Elevated neutrophil counts in broncho-alveolar lavage (BAL) fluids of lung transplant (LTx) patients with chronic lung allograft dysfunction (CLAD) are associated with disease pathology. However, phenotypical characteristics of these cells remained largely unknown. Moreover, despite enhanced levels of the most potent human neutrophil-attracting chemokine CXCL8 in BAL fluid, no discrimination had been made between natural NH2-terminally truncated CXCL8 proteoforms, which exhibit up to 30-fold differences in biological activity. Therefore, we aimed to characterize the neutrophil maturation and activation state, as well as proteolytic activation of CXCL8, in BAL fluids and peripheral blood of LTx patients with CLAD or infection and stable LTx recipients. Flow cytometry and microscopy revealed a high diversity in neutrophil maturity in blood and BAL fluid, ranging from immature band to hypersegmented aged cells. In contrast, the activation phenotype of neutrophils in BAL fluid was remarkably homogeneous. The highly potentiated NH2-terminally truncated proteoforms CXCL8(6-77), CXCL8(8-77) and CXCL8(9-77), but also the partially inactivated CXCL8(10-77), were detected in BAL fluids of CLAD and infected LTx patients, as well as in COVID-19 and influenza patient cohorts by tandem mass spectrometry. Moreover, the most potent proteoform CXCL8(9-77) specifically correlated with the neutrophil counts in the LTx BAL fluids. Finally, rapid proteolysis of CXCL8 in BAL fluids could be inhibited by a combination of serine and metalloprotease inhibitors. In conclusion, proteolytic activation of CXCL8 promotes neutrophilic inflammation in LTx patients. Therefore, application of protease inhibitors may hold pharmacological promise for reducing excessive neutrophil-mediated inflammation and collateral tissue damage in the lungs.

Azithromycin Exposure in a 10-Day Window of Myocardial Infarction and Short- and Long-Term Outcomes

Background

The U.S. Food and Drug Administration warned in 2012 that azithromycin (AZM) can cause potentially fatal irregular heart rhythm, particularly in patients with known cardiac risk factors.

Objectives

This study aimed to examine cardiac and hospital readmission outcomes associated with AZM exposure near the time of a myocardial infarction (MI).

Methods

This was a retrospective cohort study using Merative MarketScan databases examining adult inpatients admitted with MI from January 1, 2010 to December 31, 2017. Patients with AZM exposure 7 days pre-MI to 3 days post-MI were compared to unexposed controls. Time to subsequent MI and incident heart failure (HF) were examined up to 5 years post-MI using Cox models. All-cause, MI-related, MI and sequelae-related readmissions and incident HF diagnosis were examined 30 days post-MI using logistic regression.

Results

There were 18,066 eligible patients in the full cohort (AZM, N = 3,011), and the HF-free at baseline cohort included 9,180 patients (AZM, N = 1,530). Probability of subsequent MI up to 5 years post-MI was 15.3% in the AZM group vs 9.7% in control (HR: 1.41 [95% CI: 1.10-1.81], P = 0.0076). Probability of incident HF was 39.8% in the AZM group vs 35.5% in control (HR: 1.12 [95% CI: 0.91-1.39], P = 0.2795). Odds of all 4 30-day outcomes were significantly higher in the AZM group vs control.

Conclusions

We found an increased risk of long-term subsequent MI, 30-day hospital readmissions, and 30-day incident HF among MI patients with AZM exposure compared to controls. Our findings are consistent with the 2012 Food and Drug Administration warning.

Azithromycin targets the CD27 pathway to modulate CD27hi T-lymphocyte expansion and type-1 effector phenotype

Macrolide antibiotic azithromycin is widely used in clinical practice to treat respiratory tract infections and inflammatory diseases. However, its mechanism of action is not fully understood. Given the involvement of the CD27 pathway in the pathophysiology of various T-lymphocyte-mediated inflammatory, autoimmune, and lymphoproliferative diseases, we examined the impact of AZM on CD27 regulation and potential consequences on CD4+ and CD8+ T-cell phenotypes. Using cellular immunology approaches on healthy donors' peripheral blood mononuclear cells, we demonstrate AZM-mediated downregulation of surface CD27 expression as well as its extracellular release as soluble CD27. Notably, AZM-exposed CD27high (hi) cells were defective in their ability to expand compared to CD27intermediate (Int) and CD27low (lo) subsets. The defective CD27hi subset expansion was found to be associated with impaired cell proliferation and cell division. At the molecular level, the CD27hi subset exhibited lower mTOR activity than other subsets. Functionally, AZM treatment resulted in marked depletion of helper CD4+ (Th1) and cytotoxic CD8+ T-lymphocyte (Tc1)-associated CXCR3+CD27hi effector cells and inhibition of inflammatory cytokine IFN-γ production. These findings provide mechanistic insights on immunomodulatory features of AZM on T-lymphocyte by altering the CD27 pathway. From a clinical perspective, this study also sheds light on potential clinical benefits observed in patients on prophylactic AZM regimens against various respiratory diseases and opens avenues for future adjunct therapy against Th1- and Tc1-dominated inflammatory and autoimmune diseases.

Longitudinal lung function trajectories in response to azithromycin therapy for chronic lung disease in children with HIV infection: a secondary analysis of the BREATHE trial

BACKGROUND

Chronic lung disease (CLD) is common among children with HIV (CWH) including in those taking antiretroviral therapy (ART). Azithromycin has both antimicrobial and anti-inflammatory effects and has been effective in improving lung function in a variety of lung diseases. We investigated lung function trajectories among CWH with CLD on ART enrolled in a randomized controlled trial of adjuvant azithromycin. We also investigated factors that modified the effect of azithromycin on lung function.

METHODS

The study used data from a double-blinded placebo-controlled trial conducted in Malawi and Zimbabwe of 48 weeks on azithromycin (BREATHE: ClinicalTrials.gov NCT02426112) among CWH aged 6 to 19 years taking ART for at least six months who had a forced expiratory volume in one second (FEV1) z-score <-1.0. Participants had a further follow-up period of 24 weeks after intervention cessation. FEV1, forced vital capacity (FVC) and FEV1/FVC were measured at baseline, 24, 48 and 72-weeks and z-scores values calculated. Generalized estimating equations (GEE) models were used to determine the mean effect of azithromycin on lung-function z-scores at each follow-up time point.

RESULTS

Overall, 347 adolescents (51% male, median age 15 years) were randomized to azithromycin or placebo. The median duration on ART was 6.2 (interquartile range: 3.8-8.6) years and 56.2% had an HIV viral load < 1000copies/ml at baseline. At baseline, the mean FEV1 z-score was - 2.0 (0.7) with 44.7% (n = 155) having an FEV1 z-score <-2, and 10.1% had microbiological evidence of azithromycin resistance. In both trial arms, FEV1 and FVC z-scores improved by 24 weeks but appeared to decline thereafter. The adjusted overall mean difference in FEV1 z-score between the azithromycin and placebo arms was 0.004 [-0.08, 0.09] suggesting no azithromycin effect and this was similar for other lung function parameters. There was no evidence of interaction between azithromycin effect and baseline age, lung function, azithromycin resistance or HIV viral load.

CONCLUSION

There was no observed azithromycin effect on lung function z-scores at any time point suggesting no therapeutic effect on lung function.

TRIAL REGISTRATION

ClinicalTrials.gov NCT02426112. First registered on 24/04/2015.

Pseudomonas aeruginosa in chronic lung disease: untangling the dysregulated host immune response

Pseudomonas aeruginosa is a highly adaptable opportunistic pathogen capable of exploiting barriers and immune defects to cause chronic lung infections in conditions such as cystic fibrosis. In these contexts, host immune responses are ineffective at clearing persistent bacterial infection, instead driving a cycle of inflammatory lung damage. This review outlines key components of the host immune response to chronic P. aeruginosa infection within the lung, beginning with initial pathogen recognition, followed by a robust yet maladaptive innate immune response, and an ineffective adaptive immune response that propagates lung damage while permitting bacterial persistence. Untangling the interplay between host immunity and chronic P. aeruginosa infection will allow for the development and refinement of strategies to modulate immune-associated lung damage and potentiate the immune system to combat chronic infection more effectively.

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.

Exhaled nitric oxide is associated with inflammatory biomarkers and risk of acute respiratory exacerbations in children with HIV-associated chronic lung disease

OBJECTIVES

Chronic lung disease is a recognized complication in children with HIV. Acute respiratory exacerbations (ARE) are common among this group and cause significant morbidity. Exhaled nitric oxide (eNO) is a known marker of local airway inflammation. We investigated the association between eNO and ARE, biomarkers of systemic inflammation, and the effect of azithromycin on eNO levels.

METHODS

Individuals aged 6-19 years with HIV-associated chronic lung disease in Harare, Zimbabwe, were enrolled in a placebo-controlled randomized trial investigating the effect of 48-week azithromycin treatment on lung function and ARE. eNO levels and biomarkers were measured at inclusion and after treatment in a consecutively enrolled subset of participants. Linear regression and generalized linear models were used to study associations between eNO and ARE, biomarkers, and the effect of azithromycin on eNO levels.

RESULTS

In total, 172 participants were included in this sub-study, 86 from the placebo group and 86 from the azithromycin group. Participants experiencing at least one ARE during follow-up had significantly higher eNO levels at baseline than participants who did not (geometric mean ratio 1.13, 95% confidence interval [CI] 1.03-1.24, p = 0.015), adjusted for trial arm, age, sex and history of tuberculosis. Matrix metalloproteinase (MMP)-3, -7, and -10 were significantly associated with higher baseline eNO levels. At 48 weeks, azithromycin treatment did not affect eNO levels (geometric mean ratio 0.86, 95% CI 0.72-1.03, p = 0.103).

CONCLUSION

Higher baseline eNO levels were a risk factor for ARE. eNO was associated with proinflammatory biomarkers previously found to contribute to the development of chronic lung disease. The potential use of eNO as a marker of inflammation and risk factor for ARE in HIV-associated chronic lung disease needs further investigation.

Decreased Lymphocytic Bronchitis Severity in the Era of Azithromycin Prophylaxis

Large-airway lymphocytic inflammation (LB), assessed on endobronchial biopsies, has been associated with acute cellular rejection and chronic lung allograft dysfunction (CLAD). Azithromycin (AZI) prophylaxis has been used to prevent airway inflammation and subsequent CLAD, with inconsistent results. We hypothesized that AZI prophylaxis would be associated with reduced LB, changes in bronchoalveolar lavage (BAL) immune cell populations, and improved CLAD-free survival.

Methods

We compared frequencies of LB from endobronchial biopsies before (N = 1856) and after (N = 975) protocolized initiation of AZI prophylaxis at our center. LB was classified as none, minimal, mild, or moderate by histopathologic analysis. LB grades were compared using ordinal mixed-model regression. Corresponding automated BAL leukocyte frequencies were compared using mixed-effects modeling. The effect of AZI prophylaxis on CLAD-free survival was assessed by a Cox proportional hazards model adjusted for age, sex, ethnicity, transplant indication, and cytomegalovirus serostatus.

Results

Biopsies in the pre-AZI era had 2-fold increased odds (95% confidence interval, 1.5-2.7; P < 0.001) of higher LB grades. LB was associated with BAL neutrophilia in both eras. However, there was no difference in risk for CLAD or death between AZI eras (hazard ratio 1.3; 95% confidence interval, 0.7-2.0; P = 0.45).

Conclusions

Decreased airway inflammation in the era of AZI prophylaxis may represent a direct effect of AZI therapy or reflect other practices or environmental changes. In this cohort, AZI prophylaxis was not associated with improved CLAD-free survival.

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.

Immunomodulatory Effects of Macrolides Considering Evidence from Human and Veterinary Medicine

Macrolide antimicrobial agents have been in clinical use for more than 60 years in both human and veterinary medicine. The discovery of the non-antimicrobial properties of macrolides and the effect of immunomodulation of the inflammatory response has benefited patients with chronic airway diseases and impacted morbidity and mortality. This review examines the evidence of antimicrobial and non-antimicrobial properties of macrolides in human and veterinary medicine with a focus toward veterinary macrolides but including important and relevant evidence from the human literature. The complete story for these complex and important molecules is continuing to be written.

Chronic Lung Allograft Dysfunction Is Associated with Increased Levels of Cell-Free Mitochondrial DNA in Bronchoalveolar Lavage Fluid of Lung Transplant Recipients

Chronic Lung Allograft Dysfunction (CLAD) is a life-threatening complication that limits the long-term survival of lung transplantation patients. Early diagnosis remains the basis of efficient management of CLAD, making the need for distinctive biomarkers critical. This explorative study aimed to investigate the predictive power of mitochondrial DNA (mtDNA) derived from bronchoalveolar lavages (BAL) to detect CLAD. The study included 106 lung transplant recipients and analyzed 286 BAL samples for cell count, cell differentiation, and inflammatory and mitochondrial biomarkers, including mtDNA. A receiver operating curve analysis of mtDNA levels was used to assess its ability to detect CLAD. The results revealed a discriminatory pro-inflammatory cytokine profile in the BAL fluid of CLAD patients. The concentration of mtDNA increased in step with each CLAD stage, reaching its highest concentration in stage 4, and correlated significantly with decreasing FEV1. The receiver operating curve analysis of mtDNA in BAL revealed a moderate prediction of CLAD when all stages were grouped together (AUROC 0.75, p-value < 0.0001). This study has found the concentration mtDNA in BAL to be a potential predictor for the early detection of CLAD and the differentiation of different CLAD stages, independent of the underlying pathology.

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.

Pharmacotherapy of chronic lung allograft dysfunction post lung transplantation

Chronic lung allograft dysfunction (CLAD) remains the primary cause of death in lung transplant recipients (LTRs) in spite of improvements in immunosuppression management. Despite advances in knowledge regarding the pathogenesis of CLAD, treatments that are currently available are usually ineffective and delay progression of disease at best. There are currently no evidence-based guidelines for the optimal treatment of CLAD, and management varies widely across transplant centers. Additionally, there are minimal publications available to summarize data for currently available therapies and outcomes in LTRs. We identified the major domains of the medical management of CLAD and conducted a comprehensive search of PubMed and Embase databases to identify articles published from inception to December 2021 related to CLAD in LTRs. Studies published in English pertaining to the pharmacologic prevention and treatment of CLAD were included; highest priority was given to prospective, randomized, controlled trials if available. Prospective observational and retrospective controlled trials were prioritized next, followed by retrospective uncontrolled studies, case series, and finally case reports if the information was deemed to be pertinent. Reference lists of qualified publications were also reviewed to find any other publications of interest that were not found on initial search. In the absence of literature published in the aforementioned databases, additional articles were identified by reviewing abstracts presented at the International Society for Heart and Lung Transplantation and American Transplant Congress annual meetings between 2010-2021. This document serves to provide a comprehensive review of the literature and considerations for the prevention and medical management of CLAD. This article is protected by copyright. All rights reserved.

Bronchiolitis obliterans syndrome after lung or haematopoietic stem cell transplantation: current management and future directions

Bronchiolitis obliterans syndrome (BOS) may develop after either lung or haematopoietic stem cell transplantation (HSCT), with similarities in histopathological features and clinical manifestations. However, there are differences in the contributory factors and clinical trajectories between the two conditions. BOS after HSCT occurs due to systemic graft-versus-host-disease (GVHD), whereas BOS after lung transplantation is limited to the lung allograft. BOS diagnosis after HSCT is more challenging, as the lung function decline may occur due to extrapulmonary GVHD, causing sclerosis or inflammation in the fascia or muscles of the respiratory girdle. Treatment is generally empirical with no established effective therapies. This review provides rare insights and commonalities of both conditions, that are not well elaborated elsewhere in contemporary literature, and highlights the importance of cross disciplinary learning from experts in other transplant modalities. Treatment algorithms for each condition are presented, based on the published literature and consensus clinical opinion. Immunosuppression should be optimised, and other conditions or contributory factors treated where possible. When initial treatment fails, the ultimate therapeutic option is lung transplantation (or re-transplantation in the case of BOS after lung transplantation) in carefully selected candidates. Novel therapies under investigation include aerosolised liposomal cyclosporine, Janus kinase inhibitors, antifibrotic therapies, and (in patients with BOS after lung transplantation) B-cell–directed therapies. Effective novel treatments that have a tangible impact on survival and thereby avoid the need for lung transplantation or re-transplantation are urgently required.

Chronic Lung Allograft Dysfunction

Chronic lung allograft dysfunction (CLAD) is a syndrome of progressive lung function decline, subcategorized into obstructive, restrictive, and mixed phenotypes. The trajectory of CLAD is variable depending on the phenotype, with restrictive and mixed phenotypes having more rapid progression and lower survival. The mechanisms driving CLAD development remain unclear, though allograft injury during primary graft dysfunction, acute cellular rejection, antibody-mediated rejection, and infections trigger immune responses with long-lasting effects that can lead to CLAD months or years later. Currently, retransplantation is the only effective treatment.

Delivering macrolide antibiotics to heal a broken heart - And other inflammatory conditions

Drug carriers to deliver macrolide antibiotics, such as azithromycin, show promise as antibacterial agents. Macrolide drug carriers have largely focused on improving the drug stability and pharmacokinetics, while reducing adverse reactions and improving antibacterial activity. Recently, macrolides have shown promise in treating inflammatory conditions by promoting a reparative effect and limiting detrimental pro-inflammatory responses, which shifts the immunologic setpoint from suppression to balance. While macrolide drug carriers have only recently been investigated for their ability to modulate immune responses, the previous strategies that deliver macrolides for antibacterial therapy provide a roadmap for repurposing the macrolide drug carriers for therapeutic interventions targeting inflammatory conditions. This review describes the antibacterial and immunomodulatory activity of macrolides, while assessing the past in vivo evaluation of drug carriers used to deliver macrolides with the intention of presenting a case for increased effort to translate macrolide drug carriers into the clinic.

Mechanism of action, resistance, synergism, and clinical implications of azithromycin

Background

Azithromycin (AZM), sold under the name Zithromax, is classified as a macrolide. It has many benefits due to its immunomodulatory, anti‐inflammatory, and antibacterial effects. This review aims to study different clinical and biochemisterial aspects and properties of this drug which has a priority based on literature published worldwide.

Methods

Several databases including Web of Science, Google Scholar, PubMed, and Scopus were searched to obtain the relevant studies.

Results

AZM mechanism of action including the inhibition of bacterial protein synthesis, inhibition of proinflammatory cytokine production, inhibition of neutrophil infestation, and macrophage polarization alteration, gives it the ability to act against a wide range of microorganisms. Resistant organisms are spreading and being developed because of the irrational use of the drug in the case of dose and duration. AZM shows synergistic effects with other drugs against a variety of organisms. This macrolide is considered a valuable antimicrobial agent because of its use as a treatment for a vast range of diseases such as asthma, bronchiolitis, COPD, cystic fibrosis, enteric infections, STIs, and periodontal infections.

Conclusions

Our study shows an increasing global prevalence of AZM resistance. Thus, synergistic combinations are recommended to treat different pathogens. Moreover, continuous monitoring of AZM resistance by registry centers and the development of more rapid diagnostic assays are urgently needed.

Mucus Clearance Strategies in Mechanically Ventilated Patients

The use of airway clearance strategies as supplementary treatment in respiratory disease has been best investigated in patients with cystic fibrosis (CF) and non-cystic fibrosis bronchiectasis (NCFBE), conditions which are traditionally characterized by excessive mucus stasis and mucociliary dysfunction. A variety of airway clearance therapies both pharmacological and non-pharmacological have been shown to ameliorate disease progression in this population and have hence been assimilated into routine respiratory care. This self-propagating cycle of mucus retention and airway damage leading to chronic inflammation and infections can also be applied to patients with respiratory failure requiring mechanical ventilation. Furthermore, excessive trachea-bronchial secretions have been associated with extubation failure presenting an opportunity for intervention. Evidence for the use of adjunctive mucoactive agents and other therapies to facilitate secretion clearance in these patients are not well defined, and this subgroup still remains largely underrepresented in clinical trials. In this review, we discuss the role of mucus clearance techniques with a proven benefit in patients with CF and NCFBE, and their potential role in patients requiring mechanical ventilation while highlighting the need for standardization and adoption of mucus clearance strategies in these patient populations.

Management of chronic rejection after lung transplantation

Outcomes after lung transplantation are limited by chronic lung allograft dysfunction (CLAD). The incidence of CLAD is high, and its clinical course tends to be progressive over time, culminating in graft failure and death. Indeed, CLAD is the leading cause of death beyond the first year after lung transplantation. Therapy for CLAD has been limited by a lack of high-quality studies to guide management. In this review, we will discuss the diagnosis of CLAD in light of the recent changes to definitions and will discuss the current clinical evidence available for treatment. Recently, the diagnosis of CLAD has been subdivided into bronchiolitis obliterans syndrome (BOS) and restrictive allograft syndrome (RAS). The current evidence for treatment of CLAD mainly revolves around treatment of BOS with more limited data existing for RAS. The best supported treatment to date for CLAD is the macrolide antibiotic azithromycin which has been associated with a small improvement in lung function in a minority of patients. Other therapies that have more limited data include switching immunosuppression from cyclosporine to tacrolimus, fundoplication for gastroesophageal reflux, montelukast, extracorporeal photopheresis (ECP), aerosolized cyclosporine, cytolytic anti-lymphocyte therapies, total lymphoid irradiation (TLI) and the antifibrotic agent pirfenidone. Most of these treatments are supported by case series and observational studies. Finally, we will discuss the role of retransplantation for CLAD.

Variability in azithromycin practices among lung transplant providers in the International Society for Heart and Lung Transplantation Community

Chronic lung allograft dysfunction (CLAD) is the most important long-term complication after lung transplant (LTx), and clinical experience suggests significant variability in its management. We sought to capture azithromycin practices among LTx providers internationally. A survey was distributed via the International Society for Heart and Lung Transplantation and completed by 103 respondents (15 countries). Azithromycin indications, timing, and dosing varied significantly, and 37 (36%) reported inconsistency even within their center. Thirty (29%) reported initiating azithromycin prophylactically (during initial transplant hospitalization). Of 73 others, only 10 (14%) reported waiting until CLAD diagnosis (with persistent ≥20% pulmonary function decline). Most initiated azithromycin after a CLAD risk-factor and/or event, including 59 (81%) for a persistent ≥10% decrement in FEV₁, 32 (44%) for lymphocytic bronchiolitis, and 27 (37%) for bronchoalveolar lavage neutrophilia. Azithromycin prescribing patterns appear to vary significantly, and further study is needed to elucidate the optimal timing and indications for its initiation after LTx.

Azithromycin modulates Teff/Treg balance in retinal inflammation via the mTOR signaling pathway

Uveitis is one of the most common blindness-causing ocular disorders. Due to its complicated pathogenesis, the treatment of uveitis has been widely recognized as a challenge for ophthalmologists. Recently, the anti-inflammatory properties of the antibiotic Azithromycin (AZM) have been reported. However, the therapeutic effects of Azithromycin in experimental autoimmune uveitis (EAU), a representative model of human AU, have not been elucidated till date. We conducted this study to examine the therapeutic effects and potential mechanisms of Azithromycin in EAU. We observed that Azithromycin significantly attenuated retinal inflammation in EAU mice at day 14 after immunization along with a significantly decreased inflammatory cell infiltration and cytokine production in the retina. Furthermore, we observed that Azithromycin increased the number of regulatory T cells (Treg) and decreased the number of effector T cells (Teff) in both the draining lymph nodes and spleen of EAU mice. Additionally, Azithromycin suppressed the proliferation and activation of CD4 + T cells, and induced the apoptosis of CD4 + CD44 + memory T and CD4 + CXCR3 + Th1 cells. Mechanistically, we proved that Azithromycin could regulate Teff/Treg balance by inhibiting the phosphorylation of S6 ribosomal protein, a downstream target of mammalian target of rapamycin (mTOR). Together, our findings revealed that Azithromycin alleviated EAU by regulating the Teff/Treg balance through the mTOR signaling pathway, suggesting that Azithromycin could be a promising therapeutic candidate for AU.

Follow-up on the therapeutic effects of a budesonide, azithromycin, montelukast, and acetylcysteine (BAMA) regimen in children with post-infectious bronchiolitis obliterans

Background

Post-infectious bronchiolitis obliterans (PIBO) is a rare, severe chronic lung disease without optimal treatment. Currently, treatment in children mainly relies on systemic corticosteroids, but long-term use of these drugs may lead to adverse reactions. This study aimed to evaluate the short-term efficacy of the budesonide, azithromycin, montelukast, and acetylcysteine (BAMA) regimen in paediatric PIBO patients and whether it can reduce systemic corticosteroid use.

Methods

This was a prospective study. From June 2017 to July 2020, patients diagnosed with PIBO at Yuying Children’s Hospital of Wenzhou Medical University were treated with the BAMA regimen for 3 months. Methylprednisolone was added only when the clinical manifestations did not improve or deteriorated. All patients were followed up every 2 to 4 weeks, and changes in clinical symptoms were recorded. Pulmonary function tests and high-resolution computed tomography (HRCT) were performed, and systemic corticosteroid use was recorded after the 3-month follow-up.

Results

A total of 75 patients with PIBO were included; overall, 54 patients completed the course of treatment. After treatment, the respiratory manifestations were improved in 37 patients (68.5%), but 4 patients (7.4%) showed decreased exercise tolerance, and 2 patients (3.7%) were readmitted to the hospital. Additionally, 17 (56.7%) of the 30 patients whose pulmonary function was re-examined showed improvement, and 28 (77.8%) of the 36 patients who underwent HRCT showed marked improvement. Importantly, 20 patients (54.1%) received systemic corticosteroids for 2 weeks or less, while 31.5% of patients used no corticosteroids.

Conclusions

The BAMA regimen effectively relieved clinical symptoms and signs of PIBO in children, improved pulmonary function and HRCT manifestations, and reduced the use of systemic corticosteroids.

Managing respiratory complications in Stevens-Johnson Syndrome and Toxic Epidermal Necrolysis

In the recently published guidelines by the Society of Dermatology Hospitalists on the management of Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN), a brief section was included on airway management. These recommendations provide an easy reference on how to manage respiratory complications of the disease. Understanding the evidence that underlies these recommendations would offer physicians greater clarity on the considerations behind every decision and treatment offered. We present a review of the literature on respiratory manifestations associated with SJS and TEN. In addition, we aim to address specific concerns regarding the respiratory management of these patients. These include issues such as the indications and optimal timing of intubation, tracheostomy, role of flexible nasoendoscopy, bronchoscopy, ventilation strategies, and management of chronic respiratory complications.

Long-term course of bronchial inflammation and pulmonary function testing in children with postinfectious bronchiolitis obliterans

RATIONALE

Postinfectious bronchiolitis obliterans (PIBO) is a rare, chronic respiratory condition, which follows an acute insult due to a severe infection of the lower airways.

OBJECTIVES

The objective of this study was to investigate the long-term course of bronchial inflammation and pulmonary function testing in children with PIBO.

METHODS

Medical charts of 21 children with PIBO were analyzed retrospectively at the Children's University Hospital Frankfurt/Main Germany. Pulmonary function tests (PFTs) with an interval of at least 1 month were studied between 2002 and 2019. A total of 382 PFTs were analyzed retrospectively and per year, the two best PFTs, in total 217, were evaluated. Additionally, 56 sputum analysis were assessed and the sputum neutrophils were evaluated.

RESULTS

The evaluation of the 217 PFTs showed a decrease in FEV1 with a loss of 1.07% and a loss in z score of -0.075 per year. FEV1/FVC decreased by 1.44 per year. FVC remained stable, showing a nonsignificant increase by 0.006 in z score per year. However, FEV1 and FVC in L increased significantly with FEV1 0.032 L per cm and FVC 0.048 L/cm in height. Sputum neutrophils showed a significant increase of 2.12% per year.

CONCLUSION

Our results demonstrated that in patients with PIBO pulmonary function decreased significantly showing persistent obstruction over an average follow-up period of 8 years. However, persistent lung growth was revealed. In addition, pulmonary inflammation persisted clearly showing an increasing amount of neutrophils in induced sputum. Patients did not present with a general susceptibility to respiratory infections.

Chronic Lung Allograft Dysfunction: Evolving Concepts and Therapies

The primary factor that limits long-term survival after lung transplantation is chronic lung allograft dysfunction (CLAD). CLAD also impairs quality of life and increases the costs of medical care. Our understanding of CLAD continues to evolve. Consensus definitions of CLAD and the major CLAD phenotypes were recently updated and clarified, but it remains to be seen whether the current definitions will lead to advances in management or impact care. Understanding the potential differences in pathogenesis for each CLAD phenotype may lead to novel therapeutic strategies, including precision medicine. Recognition of CLAD risk factors may lead to earlier interventions to mitigate risk, or to avoid risk factors all together, to prevent the development of CLAD. Unfortunately, currently available therapies for CLAD are usually not effective. However, novel therapeutics aimed at both prevention and treatment are currently under investigation. We provide an overview of the updates to CLAD-related terminology, clinical phenotypes and their diagnosis, natural history, pathogenesis, and potential strategies to treat and prevent CLAD.

Bronchiolitis obliterans following toxic epidermal necrolysis: a case report

Background

Toxic epidermal necrolysis (TEN) is a rare, acute and potentially fatal skin condition usually induced by drugs. Although much attention is focused on the life threatening acute cutaneous and sight threatening ocular manifestations of this disease, chronic pulmonary complications like bronchiolitis obliterans are occasionally encountered. However, little is known about its incidence, pathogenesis, clinical course and outcome in children recovering from TEN.

Case presentation

We report a five-year-old boy who presented four months after the first manifestation of drug-induced TEN with cough and shortness of breath and was subsequently diagnosed with bronchiolitis obliterans. He was treated with supportive therapy that improved his hypercapnia allowing him to be discharged on domiciliary oxygen, chest physiotherapy and bronchodilators.

Conclusions

This case highlights the need to be vigilant for adverse drug reactions and consider chronic pulmonary complications like Bronchiolitis Obliterans in children recovering from TEN.

Immunomodulatory Effects of Azithromycin Revisited: Potential Applications to COVID-19

The rapid advancement of the COVID-19 pandemic has prompted an accelerated pursuit to identify effective therapeutics. Stages of the disease course have been defined by viral burden, lung pathology, and progression through phases of the immune response. Immunological factors including inflammatory cell infiltration and cytokine storm have been associated with severe disease and death. Many immunomodulatory therapies for COVID-19 are currently being investigated, and preliminary results support the premise of targeting the immune response. However, because suppressing immune mechanisms could also impact the clearance of the virus in the early stages of infection, therapeutic success is likely to depend on timing with respect to the disease course. Azithromycin is an immunomodulatory drug that has been shown to have antiviral effects and potential benefit in patients with COVID-19. Multiple immunomodulatory effects have been defined for azithromycin which could provide efficacy during the late stages of the disease, including inhibition of pro-inflammatory cytokine production, inhibition of neutrophil influx, induction of regulatory functions of macrophages, and alterations in autophagy. Here we review the published evidence of these mechanisms along with the current clinical use of azithromycin as an immunomodulatory therapeutic. We then discuss the potential impact of azithromycin on the immune response to COVID-19, as well as caution against immunosuppressive and off-target effects including cardiotoxicity in these patients. While azithromycin has the potential to contribute efficacy, its impact on the COVID-19 immune response requires additional characterization so as to better define its role in individualized therapy.

Relation of sputum neutrophilia to the development of chronic lung allograft dysfunction after lung transplantation

Chronic lung allograft dysfunction (CLAD) is a serious complication after lung transplantation (LuTx) and is associated with elevated proportions of neutrophils in bronchoalveolar lavage (BAL). Induced sputum is a less-invasive sampling method than BAL and assesses markers of inflammation on the surfaces of large central airways. We wanted to examine whether % neutrophil levels in induced sputum were elevated prior to CLAD diagnosis among LuTx recipients, and whether sputum markers of inflammation can be used as a tool for predicting the development of CLAD. Induced sputum samples were collected at 1, 3, 6, 12, and 24 months post-LuTx in 36 patients with a history of COPD or pulmonary fibrosis, and of these, 16 developed CLAD either during or after the sputum surveillance period. At 2 years, median (IQR) % neutrophils in induced sputum were significantly higher among patients with CLAD compared with those without CLAD [73 (52-80) % vs 59 (41-76) %, p = .01]. Interestingly, we found a significant increase in the rate of change in % neutrophils beginning at 90 days preceding the diagnosis of CLAD. This suggests using sputum neutrophil percentage as a surveillance modality for monitoring lung allograft function after LuTx.

Preventing the development of severe COVID-19 by modifying immunothrombosis

BACKGROUND

COVID-19-associated acute respiratory distress syndrome (ARDS) is associated with significant morbidity and high levels of mortality. This paper describes the processes involved in the pathophysiology of COVID-19 from the initial infection and subsequent destruction of type II alveolar epithelial cells by SARS-CoV-2 and culminating in the development of ARDS.

MAIN BODY

The activation of alveolar cells and alveolar macrophages leads to the release of large quantities of proinflammatory cytokines and chemokines and their translocation into the pulmonary vasculature. The presence of these inflammatory mediators in the vascular compartment leads to the activation of vascular endothelial cells platelets and neutrophils and the subsequent formation of platelet neutrophil complexes. These complexes in concert with activated endothelial cells interact to create a state of immunothrombosis. The consequence of immunothrombosis include hypercoagulation, accelerating inflammation, fibrin deposition, migration of neutrophil extracellular traps (NETs) producing neutrophils into the alveolar apace, activation of the NLRP3 inflammazome, increased alveolar macrophage destruction and massive tissue damage by pyroptosis and necroptosis Therapeutic combinations aimed at ameliorating immunothrombosis and preventing the development of severe COVID-19 are discussed in detail.

Clinical analysis of adenovirus postinfectious bronchiolitis obliterans and nonadenovirus postinfectious bronchiolitis obliterans in children

Background and Objective:

Postinfectious bronchiolitis obliterans (PIBO) is an uncommon and severe form of chronic obstructive lung disease in children. Adenovirus (ADV) is the main pathogen of PIBO in children. However, the risk factors of ADV-PIBO are not fully understood. This study aims to analyze the clinical characteristics of PIBO caused by ADV and compared with non-ADV-PIBO.

Materials and Methods:

A retrospective study of children under the age of 14 years diagnosed PIBO was performed in 56 ADV-PIBO cases, 29 non-ADV-PIBO, and 39 healthy controls to determine clinical characteristics of PIBO.

Results:

There was no difference between ADV-PIBO and non-ADV-PIBO cases in gender, age, individual and family atopy or history of asthma, and previous history of wheezing and no difference in the clinical manifestations and signs between the two groups. However, the hospital stay, duration of ventilator use, and multifocal pneumonia incidence of ADV-PIBO group have a significant differences compared with non-ADV-PIBO. Notably, inflammatory markers lactic dehydrogenase (LDH), interleukin 8 (IL-8), and interferon-gamma (IFN-γ) were significantly increased in PIBO patients, and those expressed in ADV-PIBO patients were higher than those in non-ADV-PIBO patients. In addition, ADV-PIBO children required a longer duration of oral prednisone and azithromycin than non-ADV-PIBO cases.

Conclusions:

Compared with non-ADV-PIBO, ADV-PIBO has a longer hospital stay, longer duration of ventilator use, increased LDH, IL-8, and IFN-γ expressions, and longer duration of oral prednisone and azithromycin treatment. Further research is needed to determine why PIBO caused by ADVs are more severe than those caused by other pathogens.

Targeting cystic fibrosis inflammation in the age of CFTR modulators: focus on macrophages

Cystic fibrosis (CF) is a life-shortening, multi-organ, autosomal recessive disease caused by mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene. The most prominent clinical manifestation in CF is the development of progressive lung disease characterised by an intense, chronic inflammatory airway response that culminates in respiratory failure and, ultimately, death. In recent years, a new class of therapeutics that have the potential to correct the underlying defect in CF, known as CFTR modulators, have revolutionised the field. Despite the exciting success of these drugs, their impact on airway inflammation, and its long-term consequences, remains undetermined. In addition, studies querying the absolute requirement for infection as a driver of CF inflammation have challenged the traditional consensus on CF pathogenesis, and also emphasise the need to prioritise complementary anti-inflammatory treatments in CF. Macrophages, often overlooked in CF research despite their integral role in other chronic inflammatory pathologies, have increasingly become recognised as key players in the initiation, perpetuation and resolution of CF lung inflammation, perhaps as a direct result of CFTR dysfunction. These findings suggest that macrophages may be an important target for novel anti-inflammatory interventional strategies to effectively treat CF lung function decline. This review will consider evidence for the efficacy of anti-inflammatory drugs in the treatment of CF, the potential role of macrophages, and the significance of targeting these pathways at a time when rectifying the basic defect in CF, through use of novel CFTR modulator therapies, is becoming increasingly viable.

Effect of Once-Weekly Azithromycin vs Placebo in Children With HIV-Associated Chronic Lung Disease: The BREATHE Randomized Clinical Trial

IMPORTANCE

HIV-associated chronic lung disease (HCLD) in children is associated with small airways disease, is common despite antiretroviral therapy (ART), and is associated with substantial morbidity. Azithromycin has antibiotic and immunomodulatory activity and may be effective in treating HCLD through reducing respiratory tract infections and inflammation.

OBJECTIVE

To determine whether prophylactic azithromycin is effective in preventing worsening of lung function and in reducing acute respiratory exacerbations (AREs) in children with HCLD taking ART.

DESIGN, SETTING, AND PARTICIPANTS

This double-blind, placebo-controlled, randomized clinical trial (BREATHE) was conducted between 2016 and 2019, including 12 months of follow-up, at outpatient HIV clinics in 2 public sector hospitals in Malawi and Zimbabwe. Participants were randomized 1:1 to intervention or placebo, and participants and study personnel were blinded to treatment allocation. Participants included children aged 6 to 19 years with perinatally acquired HIV and HCLD (defined as forced expiratory volume in 1 second [FEV1] z score < -1) who were taking ART for 6 months or longer. Data analysis was performed from September 2019 to April 2020.

INTERVENTION

Once-weekly oral azithromycin with weight-based dosing, for 48 weeks.

MAIN OUTCOMES AND MEASURES

All outcomes were prespecified. The primary outcome was the mean difference in FEV1 z score using intention-to-treat analysis for participants seen at end line. Secondary outcomes included AREs, all-cause hospitalizations, mortality, and weight-for-age z score.

RESULTS

A total of 347 individuals (median [interquartile range] age, 15.3 [12.7-17.7] years; 177 boys [51.0%]) were randomized, 174 to the azithromycin group and 173 to the placebo group; 162 participants in the azithromycin group and 146 placebo group participants had a primary outcome available and were analyzed. The mean difference in FEV1 z score was 0.06 (95% CI, -0.10 to 0.21; P = .48) higher in the azithromycin group than in the placebo group, a nonsignificant difference. The rate of AREs was 12.1 events per 100 person-years in the azithromycin group and 24.7 events per 100 person-years in the placebo groups (hazard ratio, 0.50; 95% CI, 0.27 to 0.93; P = .03). The hospitalization rate was 1.3 events per 100 person-years in the azithromycin group and 7.1 events per 100 person-years in the placebo groups, but the difference was not significant (hazard ratio, 0.24; 95% CI, 0.06 to 1.07; P = .06). Three deaths occurred, all in the placebo group. The mean weight-for-age z score was 0.03 (95% CI, -0.08 to 0.14; P = .56) higher in the azithromycin group than in the placebo group, although the difference was not significant. There were no drug-related severe adverse events.

CONCLUSIONS AND RELEVANCE

In this randomized clinical trial specifically addressing childhood HCLD, once-weekly azithromycin did not improve lung function or growth but was associated with reduced AREs; the number of hospitalizations was also lower in the azithromycin group but the difference was not significant. Future research should identify patient groups who would benefit most from this intervention and optimum treatment length, to maximize benefits while reducing the risk of antimicrobial resistance.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT02426112.

Can endolysosomal deacidification and inhibition of autophagy prevent severe COVID-19?

The possibility is examined that immunomodulatory pharmacotherapy may be clinically useful in managing the pandemic coronavirus disease 2019 (COVID-19), known to result from infection by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), a positive-sense single-stranded RNA virus. The dominant route of cell entry of the coronavirus is via phagocytosis, with ensconcement in endosomes thereafter proceeding via the endosomal pathway, involving transfer from early (EEs) to late endosomes (LEs) and ultimately into lysosomes via endolysosomal fusion. EE to LE transportation is a rate-limiting step for coronaviruses. Hence inhibition or dysregulation of endosomal trafficking could potentially inhibit SARS-CoV-2 replication. Furthermore, the acidic luminal pH of the endolysosomal system is critical for the activity of numerous pH-sensitive hydrolytic enzymes. Golgi sub-compartments and Golgi-derived secretory vesicles also depend on being mildly acidic for optimal function and structure. Activation of endosomal toll-like receptors by viral RNA can upregulate inflammatory mediators and contribute to a systemic inflammatory cytokine storm, associated with a worsened clinical outcome in COVID-19. Such endosomal toll-like receptors could be inhibited by the use of pharmacological agents which increase endosomal pH, thereby reducing the activity of acid-dependent endosomal proteases required for their activity and/or assembly, leading to suppression of antigen-presenting cell activity, decreased autoantibody secretion, decreased nuclear factor-kappa B activity and decreased pro-inflammatory cytokine production. It is also noteworthy that SARS-CoV-2 inhibits autophagy, predisposing infected cells to apoptosis. It is therefore also suggested that further pharmacological inhibition of autophagy might encourage the apoptotic clearance of SARS-CoV-2-infected cells.

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.

Late-onset "acute fibrinous and organising pneumonia" impairs long-term lung allograft function and survival

Acute fibrinous and organising pneumonia (AFOP) after lung transplantation is associated with a rapid decline in pulmonary function. However, the relation with chronic lung allograft dysfunction (CLAD) remains unclear. We investigated the association between detection of AFOP in lung allograft biopsies with clinically important endpoints.We reviewed lung allograft biopsies from 468 patients who underwent lung transplantation at the University Hospitals Leuven (2011-2017). AFOP was categorised as early new-onset (≤90 days post-transplant) or late new-onset (>90 days post-transplant); and associated with CLAD-free survival, graft survival, donor-specific antibodies, airway and blood eosinophilia.Early and late AFOP was detected in 24 (5%) and 30 (6%) patients, respectively. CLAD-free survival was significantly lower in patients with late AFOP (median survival 2.42 years; p<0.0001) compared with patients with early or without AFOP and specifically associated with development of restrictive allograft syndrome (OR 28.57, 95% CI 11.34-67.88; p<0.0001). Similarly, graft survival was significantly lower in patients with late AFOP (median survival 4.39 years; p<0.0001) compared with patients with early AFOP or without AFOP. Late AFOP was furthermore associated with detection of circulating donor-specific antibodies (OR 4.75, 95% CI 2.17-10.60; p=0.0004) compared with patients with early or without AFOP, and elevated airway and blood eosinophilia (p=0.043 and p=0.045, respectively) compared with early AFOP patients.Late new-onset AFOP is associated with a worse prognosis and high risk of CLAD development, specifically restrictive allograft syndrome. Our findings indicate that late new-onset AFOP might play a role in the early pathogenesis of restrictive allograft syndrome.

Esophageal Evaluation for Patients Undergoing Lung Transplant Evaluation: What Should We Do for Evaluation and Management

Lung transplantation is a high-risk, but lifesaving, procedure for patients with end-stage lung disease. Although 1-year survival is high, long-term survival is not nearly as high, due mainly to acute and chronic rejection. Bronchiolitis obliterans syndrome is the most common type of chronic rejection and often leads to poor outcomes. For this reason, esophageal testing in the lung transplant population has become a major issue, and this article discusses the evidence behind esophageal testing, the importance of esophageal dysmotility gastroesophageal reflux disease, both acidic and nonacidic reflux, and aspiration and the treatment of these findings.

Therapeutic effect of budesonide, montelukast and azithromycin on post-infectious bronchiolitis obliterans in children

Optimal treatment options for post-infectious bronchiolitis obliterans (PIBO) have not yet been established. The present study retrospectively analyzed the effect of budesonide, montelukast and azithromycin on treating PIBO in children <5 years old.. Based on treatment regimen, the cohort was divided into group A and group B. Group A received a combination of budesonide, montelukast and azithromycin for at least 3 months and group B received unconventional treatment (budesonide for nebulization intermittently, prednisone, montelukast and antibiotics if necessary) compared with standard treatment. Tidal pulmonary function and symptoms assessment were performed at diagnosis and after 3 months of therapy. There were no significant differences in the sex, age, pulmonary function and symptoms assessment between groups A and B at diagnosis. However, following 3 months of treatment, the time to peak tidal expiratory flow as a proportion of expiratory time, and volume to peak expiratory flow as a proportion of exhaled volume in group A were significantly higher compared with those in group B. The respiratory rate in group A was significantly lower compared with group B. The symptoms assessment score in group A was significantly higher compared with that of group B. In conclusion, the present study demonstrates that combination therapy with budesonide, montelukast and azithromycin improves pulmonary function and respiratory symptoms in PIBO children <5 years old. The present study was retrospectively registered on March 22, 2020 with register no. YY202003-008-HB03.

Mathematical modeling of peripheral blood neutrophil kinetics to predict CLAD after lung transplantation

BACKGROUND

The presence of neutrophils in the lung was identified as a factor associated with CLAD but requires invasive samples. The aim of this study was to assess the kinetics of peripheral blood neutrophils after lung transplantation as early predictor of CLAD.

METHODS

We retrospectively included all recipients transplanted in our center between 2009 and 2014. Kinetics of blood neutrophils were evaluated to predict early CLAD by mathematical modeling using unadjusted and adjusted analyses.

RESULTS

103 patients were included, 80 in the stable group and 23 in the CLAD group. Bacterial infections at 1 year were associated with CLAD occurrence. Neutrophils demonstrated a high increase postoperatively and then a progressive decrease until normal range. Recipients with CLAD had higher neutrophil counts (mixed effect coefficient beta over 3 years = +1.36 G/L, 95% Confidence Interval [0.99-1.92], p < .001). A coefficient of celerity (S for speed) was calculated to model the kinetics of return to the norm before CLAD occurrence. After adjustment, lower values of S (slower decrease of neutrophils) were associated with CLAD (Odds Ratio = 0.26, 95% Confidence Interval [0.08-0.66], p = .01).

CONCLUSION

A slower return to the normal range of blood neutrophils was early associated with CLAD occurrence.

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.

Postinfectious Bronchiolitis Obliterans in Children: Diagnostic Workup and Therapeutic Options: A Workshop Report

Bronchiolitis obliterans (BO) is a rare, chronic form of obstructive lung disease, often initiated with injury of the bronchiolar epithelium followed by an inflammatory response and progressive fibrosis of small airways resulting in nonuniform luminal obliteration or narrowing. The term BO comprises a group of diseases with different underlying etiologies, courses, and characteristics. Among the better recognized inciting stimuli leading to BO are airway pathogens such as adenovirus and mycoplasma, which, in a small percentage of infected children, will result in progressive fixed airflow obstruction, an entity referred to as postinfectious bronchiolitis obliterans (PIBO). The present knowledge on BO in general is reasonably well developed, in part because of the relatively high incidence in patients who have undergone lung transplantation or bone marrow transplant recipients who have had graft-versus-host disease in the posttransplant period. The cellular and molecular pathways involved in PIBO, while assumed to be similar, have not been adequately elucidated. Since 2016, an international consortium of experts with an interest in PIBO assembles on a regular basis in Geisenheim, Germany, to discuss key areas in PIBO which include diagnostic workup, treatment strategies, and research fields.

Clinical profile and course of children with postinfectious bronchiolitis obliterans from a tertiary care hospital

Background:

Postinfectious bronchiolitis obliterans (PIBO) is a chronic obstructive lung disease with scanty information in literature on etiology, clinical profile, treatment, and outcome.

Objective:

The objective of the study is to describe the clinical profile and course of children diagnosed with PIBO.

Methods:

A chart review of children below 18 years of age diagnosed as PIBO over the past 9 years was carried out. Details of clinical profile, laboratory investigations, imaging, treatment received, and outcome were recorded.

Results:

Eight children (boys 4) with PIBO were identified. Median (interquartile range [IQR]) age at the first episode of acute severe bronchiolitis such as illness and diagnosis of PIBO was 15 (6, 23.5) and 30 (16.5, 60) months, respectively, indicating a delay in diagnosis. The most common symptoms were recurrent episodes of cough (100%), fast breathing (100%), wheezing (87.5%), and fever (62.5%). Median (IQR) number of hospitalizations and episodes of antibiotic use prior to diagnosis were 2.5 (2, 5.5) and 2 (2, 4), respectively. Three (37.5%) children received mechanical ventilation during previous hospitalizations. Chest computed tomography revealed mosaic attenuation in 8 (100%), ground-glass opacities in 2 (25%), and bronchial wall thickening in 2 (25%). After diagnosis, 7 received oral steroids, 7 received hydroxychloroquine, 5 received azithromycin, and 2 received azathioprine. The median (IQR) duration of follow-up (n = 6) was 6 (1.5, 9.5) months. Median (IQR) number of pulmonary exacerbations in follow-up was 2 (1, 5).

Conclusion:

PIBO is still an under-recognized entity with substantial delay in diagnosis and unnecessary use of antibiotics. Clinical course with imaging findings may help to diagnose and manage this entity.

Long-term effect of azithromycin in bronchiolitis obliterans syndrome

Introduction

Azithromycin stabilises and improves lung function forced expiratory volume in one second (FEV₁) in lung transplantation patients with bronchiolitis obliterans syndrome (BOS). A post hoc analysis was performed to assess the long-term effect of azithromycin on FEV₁, BOS progression and survival .

Methods

Eligible patients recruited for the initial randomised placebo-controlled trial received open-label azithromycin after 3 months and were followed up until 6 years after inclusion (n=45) to assess FEV₁, BOS free progression and overall survival.

Results

FEV₁ in the placebo group improved after open-label azithromycin and was comparable with the treatment group by 6 months. FEV₁ decreased after 1 and 5 years and was not different between groups. Patients (n=18) with rapid progression of BOS underwent total lymphoid irradiation (TLI). Progression-free survival (log-rank test p=0.40) and overall survival (log-rank test p=0.28) were comparable. Survival of patients with early BOS was similar to late-onset BOS (log-rank test p=0.74).

Discussion

Long-term treatment with azithromycin slows down the progression of BOS, although the effect of TLI may affect the observed attenuation of FEV₁ decline. BOS progression and long-term survival were not affected by randomisation to the placebo group, given the early cross-over to azithromycin and possibly due to TLI in case of further progression. Performing randomised placebo-controlled trials in lung transplantation patients with BOS with a blinded trial duration is feasible, effective and safe.

Pathogenesis of HIV-Related Lung Disease: Immunity, Infection, and Inflammation

Despite anti-retroviral therapy (ART), human immunodeficiency virus-1 (HIV)-related pulmonary disease continues to be a major cause of morbidity and mortality for people living with HIV (PLWH). The spectrum of lung diseases has changed from acute opportunistic infections resulting in death to chronic lung diseases for those with access to ART. Chronic immune activation and suppression can result in impairment of innate immunity and progressive loss of T cell and B cell functionality with aberrant cytokine and chemokine responses systemically as well as in the lung. HIV can be detected in the lungs of PLWH and has profound effects on cellular immune functions. In addition, HIV-related lung injury and disease can occur secondary to a number of mechanisms including altered pulmonary and systemic inflammatory pathways, viral persistence in the lung, oxidative stress with additive effects of smoke exposure, microbial translocation, and alterations in the lung and gut microbiome. Although ART has had profound effects on systemic viral suppression in HIV, the impact of ART on lung immunology still needs to be fully elucidated. Understanding of the mechanisms by which HIV-related lung diseases continue to occur is critical to the development of new preventive and therapeutic strategies to improve lung health in PLWH.

Lung Transplantation and Precision Medicine

Lung transplantation is an accepted therapeutic option for end-stage lung diseases. Its history starts in the 1940s, initially hampered by early deaths due to perioperative problems and acute rejection. Improvement of surgical techniques and the introduction of immunosuppressive drugs resulted in longer survival. Chronic lung allograft dysfunction (CLAD), a new complication appeared and remains the most serious complication today. CLAD, the main reason why survival after lung transplantation is impaired compared to other solid-organ transplantations is characterized by a gradually increasing shortness of breath, reflected in a deterioration of pulmonary function status, respiratory insufficiency and possibly death.

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.

Complications of Stem Cell Transplantation that Affect Infections in Stem Cell Transplant Recipients, with Analogies to Patients with Hematologic Malignancies

This article discusses the complications of hematopoietic stem cell transplantion (HSCT) that affect infections in HSCT recipients, with analogies to patients with hematologic malignancies. Mucositis, with mucosal barrier disruption, is common and increases the risk of gram-positive and anaerobic bacterial, and fungal infections, and can evolve to typhlitis. Engraftment syndrome; graft-versus-host disease, hepatic sinusoidal obstruction syndrome; and posterior reversible encephalopathy syndrome can affect the infectious potential either directly from organ dysfunction or indirectly from specific treatment. Pulmonary infections can predispose to life threatening complications including diffuse alveolar hemorrhage, idiopathic pulmonary syndrome, bronchiolitis obliterans syndrome, and bronchiolitis obliterans with organizing pneumonia.