Efficacy of azithromycin in preventing lethal graft-versus-host disease

Prospects for macrolide therapy of asthma and COPD

Macrolide compounds, many of which are derived from natural sources, all share a lactone ring structure, but of varying sizes. Their biological activities differ with structure and size but tend to overlap. Marketed macrolide drugs include immunosuppressives and antibiotics. Some of the latter have been shown to exert anti-inflammatory activities, due to direct effects on inflammatory cells and processes when used for respiratory infections. Consequently, azithromycin is included in clinical guidelines for COPD and asthma treatment, though it has the disadvantage, as an antibiotic, of increasing bacterial resistance. COPD and asthma, however, like several chronic inflammatory diseases involving other organs, are driven to a large extent by epithelial barrier dysfunction. Recently, azithromycin was shown to directly enhance epithelial barrier function and a new class of derivatives, barriolides, is under development with the lead indication COPD. It is thus likely that by circumventing antibiosis and acting on a crucial etiological disease process, this type of agent will open up a new, safer approach to COPD and asthma therapy with macrolides.

Nonantimicrobial Actions of Macrolides: Overview and Perspectives for Future Development

Macrolides are among the most widely prescribed broad spectrum antibacterials, particularly for respiratory infections. It is now recognized that these drugs, in particular azithromycin, also exert time-dependent immunomodulatory actions that contribute to their therapeutic benefit in both infectious and other chronic inflammatory diseases. Their increased chronic use in airway inflammation and, more recently, of azithromycin in COVID-19, however, has led to a rise in bacterial resistance. An additional crucial aspect of chronic airway inflammation, such as chronic obstructive pulmonary disease, as well as other inflammatory disorders, is the loss of epithelial barrier protection against pathogens and pollutants. In recent years, azithromycin has been shown with time to enhance the barrier properties of airway epithelial cells, an action that makes an important contribution to its therapeutic efficacy. In this article, we review the background and evidence for various immunomodulatory and time-dependent actions of macrolides on inflammatory processes and on the epithelium and highlight novel nonantibacterial macrolides that are being studied for immunomodulatory and barrier-strengthening properties to circumvent the risk of bacterial resistance that occurs with macrolide antibacterials. We also briefly review the clinical effects of macrolides in respiratory and other inflammatory diseases associated with epithelial injury and propose that the beneficial epithelial effects of nonantibacterial azithromycin derivatives in chronic inflammation, even given prophylactically, are likely to gain increasing attention in the future. SIGNIFICANCE STATEMENT: Based on its immunomodulatory properties and ability to enhance the protective role of the lung epithelium against pathogens, azithromycin has proven superior to other macrolides in treating chronic respiratory inflammation. A nonantibiotic azithromycin derivative is likely to offer prophylactic benefits against inflammation and epithelial damage of differing causes while preserving the use of macrolides as antibiotics.

Donor-derived M2 macrophages attenuate GVHD after allogeneic hematopoietic stem cell transplantation

Introduction

Graft‐versus‐host disease (GVHD) is frequent and fatal complication following allogeneic hematopoietic stem cell transplantation (HSCT) and characteristically involves skin, gut, and liver. Macrophages promote tissue regeneration and mediate immunomodulation. Macrophages are divided into two different phenotypes, classically activated M1 (pro‐inflammatory or immune‐reactive macrophages) and alternatively activated M2 (anti‐inflammatory or immune‐suppressive macrophages). The anti‐inflammatory effect of M2 macrophage led us to test its effect in the pathophysiology of GVHD.

Methods

GVHD was induced in lethally irradiated BALB/c mice. M2 macrophages derived from donor bone marrow (BM) were administered intravenously, while controls received donor BM‐mononuclear cells and splenocytes. Animals were monitored for clinical GVHD and analyzed.

Results

We confirmed that administering donor BM‐derived M2 macrophages attenuated GVHD severity and prolonged survival after HSCT. Moreover, donor BM‐derived M2 macrophages significantly suppressed donor T cell proliferation by cell‐to‐cell contact in vitro.

Conclusions

We showed the protective effects of donor‐derived M2 macrophages on GVHD and improved survival in a model of HSCT. Our data suggest that donor‐derived M2 macrophages offer the potential for cell‐based therapy to treat GVHD.

Azithromycin in viral infections

Azithromycin (AZM) is a synthetic macrolide antibiotic effective against a broad range of bacterial and mycobacterial infections. Due to an additional range of anti-viral and anti-inflammatory properties, it has been given to patients with the coronaviruses SARS-CoV or MERS-CoV. It is now being investigated as a potential candidate treatment for SARS-CoV-2 having been identified as a candidate therapeutic for this virus by both in vitro and in silico drug screens. To date there are no randomised trial data on its use in any novel coronavirus infection, although a large number of trials are currently in progress. In this review, we summarise data from in vitro, murine and human clinical studies on the anti-viral and anti-inflammatory properties of macrolides, particularly AZM. AZM reduces in vitro replication of several classes of viruses including rhinovirus, influenza A, Zika virus, Ebola, enteroviruses and coronaviruses, via several mechanisms. AZM enhances expression of anti-viral pattern recognition receptors and induction of anti-viral type I and III interferon responses. Of relevance to severe coronavirus-19 disease (COVID-19), which is characterised by an over-exuberant innate inflammatory response, AZM also has anti-inflammatory properties including suppression of IL-1beta, IL-2, TNF and GM-CSF. AZM inhibits T cells by inhibiting calcineurin signalling, mammalian target of rapamycin activity and NFκB activation. AZM particularly targets granulocytes where it concentrates markedly in lysosomes, particularly affecting accumulation, adhesion, degranulation and apoptosis of neutrophils. Given its proven safety, affordability and global availability, tempered by significant concerns about antimicrobial stewardship, there is an urgent mandate to perform well-designed and conducted randomised clinical trials.

Modulating the conformation of the TIR domain by a neoteric MyD88 inhibitor leads to the separation of GVHD from GVT

Graft-versus-host disease (GVHD) remains the least curable complication after allogeneic bone marrow transplantation (BMT). Myeloid differentiation factor 88 (MyD88) is an adaptor molecule critically involved in the toll-like receptor (TLR) signaling pathway. The Toll/IL-1 receptor (TIR) domains of MyD88 and TLR are interactional modules responsible for sorting and signaling via direct or indirect TIR-TIR interactions, which can contribute to all phases of GVHD progression. Here, we describe the mechanisms of the novel MyD88 inhibitor, TJ-M2010-5, and the discovery of its immunosuppressive properties in the context of GVHD and the graft-versus-tumor (GVT) effect in a fully MHC-mismatched murine model. TJ-M2010-5 potentially interrupted the conformation of the TIR domain through its predicted DD loops, BB loops, and Poc site, and inhibited the homodimerization of MyD88, the LPS-stimulated activation of dendritic cells, and the priming of donor allogeneic T cell proliferation in a dose-dependent manner. Oral administration of TJ-M2010-5 ameliorated the inflammatory environment, decreased the number of apoptotic cells, increased tissue repair in GVHD target organs, and suppressed lethal GVHD. Further, protection against GVHD by TJ-M2010-5 did not abrogate a GVT effect against SP2/0, a myeloma cell line. Our data define the mechanisms of actions and provide novel insight into the potential clinical uses of TJ-M2010-5 for GVHD prevention.

Host MyD88 signaling protects against acute graft-versus-host disease after allogeneic bone marrow transplantation

Recent experimental strategies to reduce graft-versus-host disease (GVHD) have focused largely on modifying innate immunity. Toll-like receptor (TLR)-driven myeloid differentiation primary response 88 (MyD88)-dependent signalling pathways that initiate adaptive immune function are also critical for the pathogenesis of GVHD. This study aimed to delineate the role of host MyD88 in the development of acute GVHD following fully major histocompatibility complex-mismatched allogeneic bone marrow transplantation (BMT). When myeloablated BALB/c MyD88 knock-out recipients were transplanted with C57BL/6 (B6) donor cells, they developed significantly more severe GVHD than wild-type (WT) BALB/c hosts. The increased morbidity and mortality in MyD88^-/- mice correlated with increased serum levels of lipopolysaccharide and elevated inflammatory cytokines in GVHD target organs. Additionally, MyD88 deficiency in BMT recipients led to increased donor T cell expansion and more donor CD11c⁺ cell intestinal infiltration with apoptotic cells but reduced proliferation of intestinal epithelial cells compared with that in WT BMT recipients. Decreased expression of tight junction mRNA in epithelial cells of MyD88^-/- mice suggested that MyD88 contributes to intestinal integrity. Cox-2 expression in the GVHD-targeted organs of WT mice is increased upon GVHD induction, but this enhanced expression was obviously inhibited by MyD88 deficiency. The present findings demonstrate an unexpected role for host MyD88 in preventing GVHD after allogeneic BMT.

Effects of pre-transplant azithromycin administration on kidney graft function: study protocol for a double-blind randomized clinical trial

Background

Kidney transplantation is the best strategy for the management of end-stage renal disease; however, the outcomes need to improve further. Macrolides show antimicrobial and anti-inflammatory properties in chronic diseases and intraoperatively, and can accumulate in tissues for extended periods. Therefore, theoretically, when administered to a donor and because of accumulation in the donor kidney, macrolides can cause graft immunomodulation and improve kidney transplantation outcomes.

Methods

This study is a single-center, randomized clinical trial. A total of 60 kidney donors will be randomly allocated to the azithromycin or placebo group and treated with a single dose (1 g) of azithromycin or placebo, respectively, 1 day before surgery. Recruitment commenced in September 2016 and is expected to be completed by March 2018. The primary outcome is kidney graft function. The secondary outcomes include rejection rate, urinary tract infections in graft recipients, pain and systemic inflammatory response syndrome in live donors, and complications in both donors and recipients. Outcomes will be evaluated at baseline and every day in the first week after transplantation, as well as at 1 and 3 months post transplantation. Adverse reactions will be documented. If the efficacy of azithromycin in reducing adverse outcomes is confirmed, it would serve as an easy to use, economic intervention able to lower post-transplantation risks.

Discussion

Short and mid-term analyses of blood and urine samples as well as immunological assays will facilitate a more in-depth analysis of the effects of azithromycin on transplantation outcomes.

Trial registration

Iranian Clinical Trial Registry, IRCT201606141853N11, registered on September 5, 2016.

Electronic supplementary material

The online version of this article (10.1186/s13063-018-2744-y) contains supplementary material, which is available to authorized users.

"Phage Transplantation in Allotransplantation": Possible Treatment in Graft-Versus-Host Disease?

Graft-versus-host disease, both acute and chronic (aGvHD, cGvHD) remains a major complication in patients undergoing hematopoietic cell transplantation (HCT) and a significant therapeutic challenge, as many patients do not respond adequately to presently available therapy. Increasing antimicrobial resistance has greatly revived interest in using bacterial viruses (phages) to combat antibiotic-resistant bacteria. In recent years, evidence has accumulated indicating that phages also have anti-inflammatory and immunomodulatory activities. This article suggests how these anti-bacterial and immunomodulatory activities of phages may be translated into a novel treatment of acute GvHD.

SupplAzithromycin for Prevention of Graft-Versus-Host Disease: A Randomized Placebo-Controlled Trial

Background: Allogeneic hematopoietic stem cell transplantation has been used widely to treat various types of malignant and non-malignant disorders. Graft-versus-host disease is one of the main complications of this procedure which is associated with considerable mortality and affects quality of life. Despite careful selection of HLA-matched donors and implementing immunosuppressive therapy, the incidence rate of graft-versus-host disease remains high. Macrolide antibiotics are well-known immunomodulatory agents and have been effective as prophylaxis for graft-versus-host disease in preclinical studies. Materials and Methods: Ninety-six adult patients with acute leukemia were recruited into a double-blind, randomized, placebo-controlled trial. All patients were first-time transplant candidates for a full-matched related or unrelated donor. Patients were allocated to receive azithromycin 500 mg daily (n=48) or placebo (n=48) from day -6 to +12. All patients received high-dose chemotherapy, standard immunosuppressive regimen and supportive care according to institutional protocols. Results: The incidence of acute graft-versus-host disease grade III-IV and chronic graft-versus-host disease garde I-III was not significantly different between the two study arms. Oral mucositis grade 1-3 occurred in significantly lower number of patients in the azithromycin group compared with placebo. Conclusion: Based on the results of this study, protective effect of azithromycin on graft-versus-host disease could not be demonstrated.

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.

Azithromycin modulates immune response of human monocyte-derived dendritic cells and CD4+ T cells

Azithromycin (AZM) is a macrolide antibiotic that exhibits anti-inflammatory activity aside from its antimicrobial effect, a feature that may ameliorate certain inflammatory disorders and prevent graft-versus-host disease in patients receiving stem cell transplantation. In the present study, we investigated the ability of AZM to influence the function of human monocyte-derived dendritic cells (DCs) and CD4⁺ T cells. We found that AZM down-regulated CD80, CD86, and HLA-DR expression in lipopolysaccharide (LPS)-stimulated DCs and suppressed interleukin (IL)-6, IL-10, IL-12, and tumor necrosis factor-alpha production in these cells. In addition, AZM increased endocytosis and/or expression of Toll-like receptor (TLR)2, TLR4, and TLR9 in DCs and suppressed anti-CD3/CD28-induced CD4⁺ T cell proliferation and interferon-gamma production, an effect that was synergistic with dexamethasone. Finally, AZM suppressed DC-induced allogeneic T cell proliferation and cytokine production. Our study demonstrates that AZM modulates DC and CD4⁺ T cell function and may be of therapeutic benefit in various inflammatory disorders.

Preventive azithromycin treatment reduces noninfectious lung injury and acute graft-versus-host disease in a murine model of allogeneic hematopoietic cell transplantation

Noninfectious lung injury and acute graft-versus-host disease (GVHD) after allogeneic hematopoietic cell transplantation (allo-HCT) are associated with significant morbidity and mortality. Azithromycin is widely used in allogeneic HCT recipients for pulmonary chronic GVHD, although current data appear controversial. We induced GVHD and noninfectious lung injury in lethally irradiated B6D2F1 mice by transplanting bone marrow and splenic T cells from allogeneic C57BL/6 mice. Experimental groups were treated with oral azithromycin starting on day 14 until the end of week 6 or week 14 after transplantation. Azithromycin treatment resulted in improved survival and decreased lung injury; the latter characterized by improved pulmonary function, reduced peribronchial and perivascular inflammatory cell infiltrates along with diminished collagen deposition, and a decrease in lung cytokine and chemokine expression. Azithromycin also improved intestinal GVHD but did not affect liver GVHD at week 6 early after transplantation. At week 14, azithromycin decreased liver GVHD but had no effect on intestinal GVHD. In vitro, allogeneic antigen-presenting cell (APC)- dependent T cell proliferation and cytokine production were suppressed by azithromycin and inversely correlated with relative regulatory T cell (Treg) expansion, whereas no effect was seen when T cell proliferation occurred APC independently through CD3/CD28-stimulation. Further, azithromycin reduced alloreactive T cell expansion but increased Treg expansion in vivo with corresponding downregulation of MHC II on CD11c(+) dendritic cells. These results demonstrate that preventive administration of azithromycin can reduce the severity of acute GVHD and noninfectious lung injury after allo-HCT, supporting further investigation in clinical trials.

Azithromycin: mechanisms of action and their relevance for clinical applications

Azithromycin is a macrolide antibiotic which inhibits bacterial protein synthesis, quorum-sensing and reduces the formation of biofilm. Accumulating effectively in cells, particularly phagocytes, it is delivered in high concentrations to sites of infection, as reflected in rapid plasma clearance and extensive tissue distribution. Azithromycin is indicated for respiratory, urogenital, dermal and other bacterial infections, and exerts immunomodulatory effects in chronic inflammatory disorders, including diffuse panbronchiolitis, post-transplant bronchiolitis and rosacea. Modulation of host responses facilitates its long-term therapeutic benefit in cystic fibrosis, non-cystic fibrosis bronchiectasis, exacerbations of chronic obstructive pulmonary disease (COPD) and non-eosinophilic asthma. Initial, stimulatory effects of azithromycin on immune and epithelial cells, involving interactions with phospholipids and Erk1/2, are followed by later modulation of transcription factors AP-1, NFκB, inflammatory cytokine and mucin release. Delayed inhibitory effects on cell function and high lysosomal accumulation accompany disruption of protein and intracellular lipid transport, regulation of surface receptor expression, of macrophage phenotype and autophagy. These later changes underlie many immunomodulatory effects of azithromycin, contributing to resolution of acute infections and reduction of exacerbations in chronic airway diseases. A sub-group of post-transplant bronchiolitis patients appears to be sensitive to azithromycin, as may be patients with severe sepsis. Other promising indications include chronic prostatitis and periodontitis, but weak activity in malaria is unlikely to prove crucial. Long-term administration of azithromycin must be balanced against the potential for increased bacterial resistance. Azithromycin has a very good record of safety, but recent reports indicate rare cases of cardiac torsades des pointes in patients at risk.

Regulatory myeloid cells in transplantation

Regulatory myeloid cells (RMC) are emerging as novel targets for immunosuppressive (IS) agents and hold considerable promise as cellular therapeutic agents. Herein, we discuss the ability of regulatory macrophages, regulatory dendritic cells, and myeloid-derived suppressor cells to regulate alloimmunity, their potential as cellular therapeutic agents, and the IS agents that target their function. We consider protocols for the generation of RMC and the selection of donor- or recipient-derived cells for adoptive cell therapy. Additionally, the issues of cell trafficking and antigen (Ag) specificity after RMC transfer are discussed. Improved understanding of the immunobiology of these cells has increased the possibility of moving RMC into the clinic to reduce the burden of current IS agents and to promote Ag-specific tolerance. In the second half of this review, we discuss the influence of established and experimental IS agents on myeloid cell populations. IS agents believed historically to act primarily on T cell activation and proliferation are emerging as important regulators of RMC function. Better insights into the influence of IS agents on RMC will enhance our ability to develop cell therapy protocols to promote the function of these cells. Moreover, novel IS agents may be designed to target RMC in situ to promote Ag-specific immune regulation in transplantation and to usher in a new era of immune modulation exploiting cells of myeloid origin.

Comparative study of the efficacy of allogeneic hematopoietic stem cell transplantation from human leukocyte antigen-haploidentical related and unrelated donors in the treatment of leukemia

AIMS

To compare the efficacy of hematopoietic stem cell transplantation (HSCT) from human leukocyte antigen (HLA)-haploidentical related donors (RD) and unrelated donors (URD) in the treatment of leukemia.

METHODS

Ninety-three leukemia patients underwent allogeneic HSCT were divided into two groups: 51 cases of RD-HSCT and 42 cases of URD-HSCT. In the RD-HSCT group, a preconditioning regimen with fludarabine (Flu) + busulfan (Bu) + cytosine arabinoside (Ara-C) was used in 42 patients and total body irradiation (TBI) + Flu + Ara-C was used in the remaining 9.

RESULTS

In the URD-HSCT group, a modified preconditioning regimen with Bu + cyclophosphamide was used in 35 patients, while the other 7 patients underwent treatment with TBI + Flu. After transplantation, the occurrence rate of grade II-IV acute graft-versus-host disease (GVHD) was 46.0 and 51.2% in the two groups. Likewise, the rate of chronic GVHD was 46.0 and 63.4%, respectively. No significant differences in the occurrence of acute and chronic GVHD were detected between the two groups. The differences in early-stage infection rate after transplantation, recurrence rate, 3-year survival rate, and disease-free survival rate between the two groups were not significant.

CONCLUSION

HLA-haploidentical RD-HSCT with enhanced preconditioning and administration of immunosuppressants showed a clinical efficacy similar to that of URD-HSCT against leukemia, without the risk of increased infection and GVHD.