Azithromycin and Chloramphenicol Diminish Neutrophil Extracellular Traps (NETs) Release

Abstract

Neutrophils are one of the first cells to arrive at the site of infection, where they apply several strategies to kill pathogens: degranulation, respiratory burst, phagocytosis, and release of neutrophil extracellular traps (NETs). Antibiotics have an immunomodulating effect, and they can influence the properties of numerous immune cells, including neutrophils. The aim of this study was to investigate the effects of azithromycin and chloramphenicol on degranulation, apoptosis, respiratory burst, and the release of NETs by neutrophils. Neutrophils were isolated from healthy donors by density-gradient centrifugation method and incubated for 1 h with the studied antibiotics at different concentrations (0.5, 10 and 50 μg/mL—azithromycin and 10 and 50 μg/mL—chloramphenicol). Next, NET release was induced by a 3 h incubation with 100 nM phorbol 12-myristate 13-acetate (PMA). Amount of extracellular DNA was quantified by fluorometry, and NETs were visualized by immunofluorescent microscopy. Degranulation, apoptosis and respiratory burst were assessed by flow cytometry. We found that pretreatment of neutrophils with azithromycin and chloramphenicol decreases the release of NETs. Moreover, azithromycin showed a concentration-dependent effect on respiratory burst in neutrophils. Chloramphenicol did not affect degranulation, apoptosis nor respiratory burst. It can be concluded that antibiotics modulate the ability of neutrophils to release NETs influencing human innate immunity.

Neutrophil extracellular traps in nasal secretions of patients with stable and exacerbated chronic rhinosinusitis and their contribution to induce chemokine secretion and strengthen the epithelial barrier

“…31 The whereas clindamycin has no influence on NETs release. 48 In these studies, they did not compare the amount of extracellular DNA of neutrophils treated with antibiotics to that of unstimulated neutrophils. Data from six independent experiments are presented as means ± SEM and are derived from six individuals (*There is statistical significant difference in the concentration of extracellular DNA between control and dose of macrolides or glucocorticoid, P < 0.05).…”

“…Original magnification ×200 contrary, pretreatment of neutrophils with azithromycin and chloramphenicol caused a significant decrease in NETs release after stimulation with PMA. 48 In these studies, they did not compare the amount of extracellular DNA of neutrophils treated with antibiotics to that of unstimulated neutrophils. However, we measured the amount of extracellular DNA released from macrolide or corticosteroid-treated neutrophils without PMA stimulation and found that clarithromycin, azithromycin, and josamycin induces NETs release under the experimental conditions applied in the present study.…”

Ribosome-targeting antibiotics impair T cell effector function and ameliorate autoimmunity by blocking mitochondrial protein synthesis

“…Furthermore, certain RAbos were previously described as immunosuppressive. For example, chloramphenicol diminishes neutrophil extracellular trap release and doxycycline inhibits B cell class switching and IgM secretion (52, 53). However, how the reduction of immune cell function occurred was mechanistically not well understood.…”

Multifaceted Role of Pneumolysin in the Pathogenesis of Myocardial Injury in Community-Acquired Pneumonia

“…In this context, the neutrophil appears to represent the primary cellular target of macrolides, which act by suppressing the activities of various cytosolic transcription factors involved in activation of the synthesis of the neutrophil-activating chemokine, IL-8, as well, as the pro-inflammatory cytokines, IL-17A and TNF-α, by both immune/inflammatory and structural cells [reviewed in 18]. More recently, the 15-membered macrolide antibiotic, azithromycin, as well as chloramphenicol and gentamicin [ 94 , 95 ], but not the β-lactam agents amoxicillin [ 95 ] and cefotaxime [ 95 ], or the macrolide-like agent, clindamycin [ 96 ], have been reported to inhibit NET formation in vitro. In the case of azithromycin, which is commonly used in the combination therapy of CAP, these inhibitory effects on NETosis were detected at concentrations of 0.5 µg/mL, achieving statistical significance at 10 µg/mL (the next higher concentration tested) [ 94 ].…”

“…More recently, the 15-membered macrolide antibiotic, azithromycin, as well as chloramphenicol and gentamicin [ 94 , 95 ], but not the β-lactam agents amoxicillin [ 95 ] and cefotaxime [ 95 ], or the macrolide-like agent, clindamycin [ 96 ], have been reported to inhibit NET formation in vitro. In the case of azithromycin, which is commonly used in the combination therapy of CAP, these inhibitory effects on NETosis were detected at concentrations of 0.5 µg/mL, achieving statistical significance at 10 µg/mL (the next higher concentration tested) [ 94 ]. This latter concentration is attainable in blood following intravenous administration of a 4 g dose of this agent [ 97 ].…”