Summary: Macrolides have diverse biological activities and an ability to modulate inflammation and immunity in eukaryotes without affecting homeostatic immunity. These properties have led to their long-term use in treating neutrophil-dominated inflammation in diffuse panbronchiolitis, bronchiectasis, rhinosinusitis, and cystic fibrosis. These immunomodulatory activities appear to be polymodal, but evidence suggests that many of these effects are due to inhibition of extracellular signal-regulated kinase 1/2 (ERK1/2) phosphorylation and nuclear factor kappa B (NF-κB) activation. Macrolides accumulate within cells, suggesting that they may associate with receptors or carriers responsible for the regulation of cell cycle and immunity. A concern is that long-term use of macrolides increases the emergence of antimicrobial resistance. Nonantimicrobial macrolides are now in development as potential immunomodulatory therapies.

Mechanisms of Action and Clinical Application of Macrolides as Immunomodulatory Medications

Macrolides have long been recognised to exert immunomodulary and anti-inflammatory actions. They are able to suppress the “cytokine storm” of inflammation and to confer an additional clinical benefit through their immunomodulatory properties. A search of electronic journal articles was performed using combinations of the following keywords: macrolides, COPD, asthma, bronchitis, bronchiolitis obliterans, cystic fibrosis, immunomodulation, anti-inflammatory effect, diabetes, side effects and systemic diseases. Macrolide effects are time- and dose-dependent, and the mechanisms underlying these effects remain incompletely understood. Both in vitro and in vivo studies have provided ample evidence of their immunomodulary and anti-inflammatory actions. Importantly, this class of antibiotics is efficacious with respect to controlling exacerbations of underlying respiratory problems, such as cystic fibrosis, asthma, bronchiectasis, panbrochiolitis and cryptogenic organising pneumonia. Macrolides have also been reported to reduce airway hyper-responsiveness and improve pulmonary function. This review provides an overview on the properties of macrolides (erythromycin, clarithromycin, roxithromycin, azithromycin), their efficacy in various respiratory diseases and their adverse effects.

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Macrolides: from in vitro anti-inflammatory and immunomodulatory properties to clinical practice in respiratory diseases

Radiation Pulmonary Toxicity: From Mechanisms to Management

https://www.thelancet.com/pdfs/journals/lanres/PIIS2213-2600(13)70038-9.pdf

Risks of population antimicrobial resistance associated with chronic macrolide use for inflammatory airway diseases

Summary
Macrolide antibiotics were discovered over 50 years ago and following their use as antimicrobials it became apparent that this group of antibiotics also possessed anti-inflammatory properties. Subsequent clinical trials showed benefits of macrolides as long-term adjuncts in the treatment of a spectrum of chronic inflammatory respiratory diseases, particularly diffuse panbronchiolitis, cystic fibrosis, post-transplant bronchiolitis obliterans and more recently chronic obstructive pulmonary disease (COPD). The evidence for efficacy of macrolides in the long-term treatment of chronic asthma and bronchiectasis is less well established. The mechanism(s) of action of macrolides in the treatment of these diseases remains unexplained, but may be due to their antibacterial and/or anti-inflammatory actions, which include reductions in interleukin-8 production, neutrophil migration and/or function. Macrolides have additional potentially beneficial properties including anti-viral actions and an ability to restore corticosteroid sensitivity. The increased prescribing of macrolides for long-term treatment could result in the development of microbial resistance and adverse drug effects. New macrolides have been developed which do not possess any antimicrobial activity and hence lack the ability to produce microbial resistance, but which still retain immunomodulatory effects. Potentially novel macrolides may overcome a significant barrier to the use of this type of drug for the long-term treatment of chronic inflammatory airway diseases.

Long‐term macrolide treatment of chronic inflammatory airway diseases: risks, benefits and future developments

Clinical studies have demonstrated that gefitinib, an epidermal growth factor receptor inhibitor, is an effective treatment for some patients with advanced non-small cell lung cancer and is generally well-tolerated. However, several reports have also suggested that gefitinib is associated with acute lung injury and subsequent fibrosis. One hypothesis is that gefitinib exacerbates lung injury induced by radiation therapy. It is important to confirm the safety of gefitinib in radiotherapy for patients with lung cancer. In this preclinical study we aimed to clarify the effect of gefitinib on thoracic radiotherapy. Six-week-old female C57BL/6 mice were immobilized in a plastic frame, and the thorax was irradiated once with a dose of 12 Gy on day 0. Gefitinib (20, 90 and 200 mg/kg/day) was administered on days 0 to 5 (acute phase) or days 14 to 19 (late phase) postirradiation. Thoracic irradiation induced lung injury and subsequent fibrosis 5 months later. Gefitinib, administered in the acute phase, had no effect on lung fibrosis or collagen levels induced by irradiation. A high dose of gefitinib (200 mg/kg/day) administered during the late phase significantly reduced fibrosis scores and collagen levels. These results suggest that gefitinib does not exacerbate radiation-induced lung injury and fibrosis in this strain of mice. Therefore, thoracic irradiation is unlikely to be a risk factor for lung injury associated with gefitinib treatment.

Effects of gefitinib on radiation-induced lung injury in mice.

Long-term, low-dose macrolide therapy has been proven to improve survival in patients with diffuse panbronchiolitis and cystic fibrosis, although the mechanisms by which it does so remain unknown. To elucidate the molecular mechanisms of the anti-inflammatory effects of macrolides, the authors examined the effects of erythromycin (EM-A) and new derivative EM703 on transforming growth factor (TGF)-β /Smad signaling fibroblasts. EM-A and EM703 each inhibited fibroblast proliferation and the collagen production in human lung fibroblasts induced by TGF-β. EM-A and EM703 inhibited the augmentation of Smad3 mRNA induced by TGF-β. Smad7 mRNA was inhibited by TGF-β, but augmented by coincubation with EM-A or EM703. EM-A and EM703 each inhibited p-Smad2/3 proteins induced by TGF-β. Smad7 protein inhibited by TGF-β restored beyond basal level by EM-A and EM703. These findings suggest that EM-A and EM703 inhibit TGF-β signaling in human lung fibroblasts via inhibition of p-Smad2/3 through recovery of Smad7 level.

Changhe Yu

Papers

Effects of gefitinib on radiation-induced lung injury in mice.

EM703, A NEW DERIVATIVE OF ERYTHROMYCIN, INHIBITS TRANSFORMING GRWTH FACTOR-β SIGNALING IN HUMAN LUNG FIBROBLASTS