Effect of clarithromycin and azithromycin on production of cytokines by human monocytes

The Features and Treatment Effects on Keratoepitheliopathy for Meibomitis-Related Keratoconjunctivitis

Meibomitis-related keratoconjunctivitis (MRKC) is characterized by meibomitis with corneal epithelial abnormalities, and can be divided into two types: MRKC accompanied with phlyctenular keratitis, and MRKC accompanied with keratoepitheliopathy that is similar to superficial punctate keratopathy (SPK). The purpose of this retrospective study was to investigate the characteristic features of keratoepitheliopathy and treatment outcomes for MRKC. This study involved 27 eyes of 18 MRKC patients (3 males and 15 females). National Eye Institute (NEI) scores and visual acuity were compared at pre and post treatment. All subjects were treated with a small-dose administration of clarithromycin. Keratoepitheliopathy characteristic to MRKC, yet different in appearance from SPK, was noted in 24 of the 27 eyes. Fluorescein staining revealed granular epithelial lesions generally larger than SPK that coexisted with small dark spots. In 17 eyes, keratoepitheliopathy was located within the pupillary zone, and the visual acuity in 12 eyes was less than 1.0. Our findings showed significant improvement in the NEI score in MRKC (p < 0.0001) and in visual acuity (p = 0.0157) post treatment, and the characteristic features of keratoepitheliopathy in MRKC that are often associated with decreased visual acuity were elucidated. The treatment of clarithromycin was found to be effective for MRKC with keratoepitheliopathy.

Investigating the immunomodulatory activities of omadacycline

BACKGROUND

Apart from their antimicrobial activities, some antibiotics have immunomodulatory effects on host cells, particularly monocytes. Because hyperactivation of the pro-inflammatory cytokine response contributes to acute lung injury in patients with bacterial pneumonia and other lung diseases, antimicrobial agents with immunomodulatory activity can reduce cytokine-mediated tissue injury and improve outcomes.

OBJECTIVES

Omadacycline has been recently FDA-approved for community-acquired bacterial pneumonia and acute bacterial skin and skin-structure infections. The present study investigated omadacycline's ability to modulate LPS-induced production of pro-inflammatory cytokines (TNF-α, IL-1β), acute-phase reactants (IL-6) and anti-inflammatory cytokines (IL-4, IL-10) by human monocytes in vitro.

METHODS

Isolated human monocytes from healthy consenting adults were cultured in RPMI with 1% pooled human serum. Cells were pre-exposed to omadacycline (0.5-64 μg/mL), minocycline (25, 50 or 25 μg/mL) or azithromycin (20, 40 or 80 μg/mL) for 2 h, followed by stimulation with Escherichia coli LPS for 24 h. Cytokines elaborated in the culture supernatant were quantitated by multiplex immunoassay.

RESULTS

Omadacycline dose-dependently suppressed LPS-induced production of all cytokines tested. Only high-dose minocycline (100 μg/mL) modestly suppressed TNF-α whereas minocycline significantly increased LPS-induced IL-1β production. Lower concentrations of minocycline were also stimulatory for IFN-γ, IL-6 and IL-4. Except for suppression of IL-6, azithromycin was largely without effect.

CONCLUSIONS

Omadacycline has unique and broad immunomodulatory properties. Such activity supports its use in settings where hyperactivation of the immune response contributes to tissue injury and poor outcomes, especially at sites where pro-inflammatory M-type 1 macrophages dominate the cellular immune response.

Pleiotropic effects of antibiotics on T cell metabolism and T cell-mediated immunity

T cells orchestrate adaptive and innate immune responses against pathogens and transformed cells. However, T cells are also the main adaptive effector cells that mediate allergic and autoimmune reactions. Within the last few years, it has become abundantly clear that activation, differentiation, effector function, and environmental adaptation of T cells is closely linked to their energy metabolism. Beyond the provision of energy equivalents, metabolic pathways in T cells generate building blocks required for clonal expansion. Furthermore, metabolic intermediates directly serve as a source for epigenetic gene regulation by histone and DNA modification mechanisms. To date, several antibiotics were demonstrated to modulate the metabolism of T cells especially by altering mitochondrial function. Here, we set out to systematically review current evidence about how beta-lactam antibiotics, macrolides, fluoroquinolones, tetracyclines, oxazolidinones, nitroimidazoles, and amphenicols alter the metabolism and effector functions of CD4+ T helper cell populations and CD8+ T cells in vitro and in vivo. Based on this evidence, we have developed an overview on how the use of these antibiotics may be beneficial or detrimental in T cell-mediated physiological and pathogenic immune responses, such as allergic and autoimmune diseases, by altering the metabolism of different T cell populations.

NSAIDs/nitazoxanide/azithromycin repurposed for COVID-19: potential mitigation of the cytokine storm interleukin-6 amplifier via immunomodulatory effects

INTRODUCTION

Mediators of immunity and inflammation are playing a crucial role in COVID-19 pathogenesis and complications as demonstrated by several genetic and clinical studies. Thus, repurposing of drugs that possess anti-inflammatory and/or immune-modulatory effects for COVID-19 is considered a rational approach.

AREAS COVERED

We analyze selected studies that correlated COVID-19 with dysregulated interferon and inflammatory responses while reflecting on our academic and real-life experience using non-steroidal anti-inflammatory drugs, nitazoxanide and azithromycin for management of COVID-19. Moreover, we interpret the results that suggested a potential survival benefit of low-dose aspirin and colchicine when used for COVID-19.

EXPERT OPINION

Nitazoxanide/azithromycin combination has been first hypothesized by the author and practiced by him and several researchers to benefit COVID-19 patients due to a potential ability to augment the natural interferon response as well as their positive immunomodulatory effects on several cytokines. Furthermore, NSAIDs, that are unfortunately currently at best of second choice after paracetamol, have been early postulated and clinically practiced by the author to prevent or ameliorate COVID-19 complications and mortality due to their anti-inflammatory and immunomodulatory properties. Finally, we repeat our previous call to adopt our observational study that used these drugs in sufficiently powered double blind randomized clinical trials.

Upregulation of FOXP3 is associated with severity of hypoxia and poor outcomes in COVID-19 patients

The levels of messenger RNA (mRNA) transcription of FOXP3, IFN-γ, TNF, IL-6 and COX-2 from both COVID-19 infected and control subjects were evaluated using SYBR^TM green real-time polymerase chain reaction (RT-PCR). Severe/critical cases showed significantly lower lymphocyte counts and higher neutrophil counts than the mild or moderate cases. There were significantly lower levels of mRNA expressions of IFN-γ, TNFα and FOXP3 in COVID-19 patients than in the control group. On the other hand, IL-6 and COX-2 expressions were significantly higher in patients suffering from severe disease. FOXP3 expressions were correlated with the severities of hypoxia and were excellent in predicting the disease severity. This was followed by the IL-6, COX-2 and TNFα expressions. FOXP3 expression was the only biomarker to show a significant correlation with patient mortality. It was concluded that SARS-CoV-2 infection is associated with the downregulation of FOXP3 and upregulations of IL-6 and COX-2.

Influence of Pyrexia on Pharmacokinetics of Azithromycin and Its Interaction With Tolfenamic Acid in Goats

Azithromycin is a macrolide antimicrobial agent of the azalide group with a broad spectrum of activity against gram-negative and gram-positive bacterial organisms. Tolfenamic acid is a non-steroidal anti-inflammatory drug of the fenamate group, which is used extensively in humans and animals due to its anti-inflammatory, analgesic, and antipyretic properties. There is dearth of literature on any type of drug interaction between azithromycin and tolfenamic acid in any species, including human beings and alteration of its pharmacokinetics by fever. Therefore, the objective of this study was to investigate the alteration of disposition kinetics of azithromycin alone and in the presence of tolfenamic acid in Malabari goats by fever, following an intravenous administration at a dose rate of 20 mg/kg body weight. Blood samples collected from both afebrile and febrile goats at predetermined time intervals after the administration of azithromycin alone and then in combination with tolfenamic acid (2 mg/kg, intravenously), respectively, were analyzed using high-performance liquid chromatography. Non-compartmental analysis was used to determine the peak blood concentration (C max), time-to-peak plasma concentration (T max), half-life (t 1/2λz ), area under the curve (AUC 0-t, AUC 0-inf), area under the first moment curve (AUMC 0-inf), mean residence time (MRT0-inf), apparent volume of distribution at steady state (V ss), and the total body clearance of drug from the blood (Cl). In febrile animals, significant differences were noted in the values of C max, Cl, and V ss. Thus, azithromycin disappears into an additional compartment in febrile goats, which may be due to its extended cellular penetration into the inflammatory cells, resulting in anti-inflammatory activity. Tolfenamic acid significantly altered the pharmacokinetics of azithromycin in both normal and febrile animals. Tolfenamic acid, being a better anti-inflammatory agent, suppresses the inflammatory mediators, reducing the possibility of increased utilization of azithromycin in febrile condition.

Chlamydia pneumoniae-Induced IFN-Gamma Responses in Peripheral Blood Mononuclear Cells Increase Numbers of CD4+ but Not CD8+ T Effector Memory Cells

Background

Chlamydia pneumoniae causes respiratory infection in adults and children. Previous studies in our laboratory identified significantly higher in vitro T lymphocyte responses to C. pneumoniae in children with asthma compared to healthy controls which may indicate the presence of T effector memory (TEM) lymphocytes.

Aim

In the present study, healthy subjects were screened for the presence of TEM cells and their cytokines. CCR7 negative effector TEMs may indicate persistent infection with C. pneumoniae.

Methods

Peripheral blood mononuclear cells (PBMC) (1×10⁶/mL) from adult non-asthmatic subjects were infected for 1h ± C. pneumoniae TW-183 at a multiplicity of infection (MOI) = 0.1 and cultured (48 hrs). Distributions of lymphocytes (CD4+, CD8+) and TEM cells (CD4+CCR7+CD45RA+CD154+, CD8+CCR7+CD45RA+CD154+) were determined. Levels of intracellular interleukin (IL)-2, IL-4, and interferon (IFN)-gamma were measured (flow microfluorimetry); IFN-gamma was measured in supernatants (ELISA).

Results

C. pneumoniae infection led to a decrease in numbers of CD8+ TEM and CD8+CD154+ cells; CD4+TEM and CD4+CD154+ cells did not change. Numbers of TEM cells (CD4+IL-2+, CD8+ IL-2+) also decreased. However, number of TEM cells (CD4+IL4-+, CD8+ IL-4+) and (CD4+ IFN-gamma+, CD8+IFN-gamma+) did not change. When stratified according to IFN-gamma+ status, numbers of CD4+ IL-2+ and CD4+IL-4+ TEMs increased; CD8+IL-2+ and CD8+ IL-4+ TEMs decreased.

Conclusion

C. pneumoniae-induced PBMC IFN-gamma+ responses increased numbers of CD4+ IL-2+ and CD4+IL-4+ TEM cells, while CD8+IL-2+ and CD8+IL-4+ TEMs decreased. Production of IFN-gamma by C. pneumoniae infected PBMC should be further studied as a biomarker of persistent infection in humans.

Could Azithromycin Be Part of Pseudomonas aeruginosa Acute Pneumonia Treatment?

Azithromycin (AZM) is a 15-membered-ring macrolide that presents a broad-spectrum antimicrobial activity against Gram-positive bacteria and atypical microorganisms but suffers from a poor diffusion across the outer-membrane of Gram-negative bacilli, including Pseudomonas aeruginosa (PA). However, AZM has demonstrated clinical benefits in patients suffering from chronic PA respiratory infections, especially cystic fibrosis patients. Since the rise of multidrug-resistant PA has led to a growing need for new therapeutic options, this macrolide has been proposed as an adjunctive therapy. Clinical trials assessing AZM in PA acute pneumonia are scarce. However, a careful examination of the available literature provides good rationales for its use in that context. In fact, 14- and 15-membered-ring macrolides have demonstrated immunomodulatory and immunosuppressive effects that could be of major interest in the management of acute illness. Furthermore, growing evidence supports a downregulation of PA virulence dependent on direct interaction with the ribosomes, and based on the modulation of several key regulators from the Quorum Sensing network. First highlighted in vitro, these interesting properties of AZM have subsequently been confirmed in the animal models. In this review, we systematically analyzed the literature regarding AZM immunomodulatory and anti-PA effects. In vitro and in vivo studies, as well as clinical trials were reviewed, looking for rationales for AZM use in PA acute pneumonia.

Therapeutic Strategies to Protect the Central Nervous System against Shiga Toxin from Enterohemorrhagic Escherichia coli

Infection with Shiga toxin-producing Escherichia coli (STEC) may cause hemorrhagic colitis, hemolytic uremic syndrome (HUS) and encephalopathy. The mortality rate derived from HUS adds up to 5% of the cases, and up to 40% when the central nervous system (CNS) is involved. In addition to the well-known deleterious effect of Stx, the gram-negative STEC releases lipopolysaccharides (LPS) and may induce a variety of inflammatory responses when released in the gut. Common clinical signs of severe CNS injury include sensorimotor, cognitive, emotional and/or autonomic alterations. In the last few years, a number of drugs have been experimentally employed to establish the pathogenesis of, prevent or treat CNS injury by STEC. The strategies in these approaches focus on: 1) inhibition of Stx production and release by STEC, 2) inhibition of Stx bloodstream transport, 3) inhibition of Stx entry into the CNS parenchyma, 4) blockade of deleterious Stx action in neural cells, and 5) inhibition of immune system activation and CNS inflammation. Fast diagnosis of STEC infection, as well as the establishment of early CNS biomarkers of damage, may be determinants of adequate neuropharmacological treatment in time.

Possible mechanisms of action of clarithromycin and its clinical application as a repurposing drug for treating multiple myeloma

Clarithromycin (CAM), a semisynthetic macrolide antibiotic, is a widely used antibacterial drug. Recently, the efficacy of CAM as an add-on drug for treating multiple myeloma (MM) has been noted. Its effect on treating MM has been confirmed in combination chemotherapies that include CAM. However, a single treatment of CAM has no efficacy for treating MM. Many myeloma growth factors (MGFs) including interleukin (IL)-6 are known to be closely involved in the development of MM. CAM has been shown to suppress many MGFs, particularly IL-6. The possible mechanisms of action of CAM in treating MM have been suggested to include its immunomodulatory effect, autophagy inhibition, reversibility of drug resistance, steroid-sparing/enhancing effect and suppression of MGFs. In addition, MM is characterised by uncontrolled cell growth of monoclonal immunoglobulin (Ig)-producing neoplastic plasma cells. Large quantities of unfolded or misfolded Ig production may trigger considerable endoplasmic reticulum stress. Thus, MM is originally a fragile neoplasm particularly susceptible to autophagy-, proteasome- and histone deacetylase 6-inhibitors. Taken together, CAM plays an important role in MM treatments through its synergistic mechanisms. In addition, CAM with its pleiotropic effects on cytokines including IL-6 and indirect antiviral effects might be worth a try for treating COVID-19.

A multi-centre open-label two-arm randomised superiority clinical trial of azithromycin versus usual care in ambulatory COVID-19: study protocol for the ATOMIC2 trial

Background

Azithromycin is an orally active synthetic macrolide antibiotic with a wide range of anti-bacterial, anti-inflammatory and antiviral properties. It is a safe, inexpensive, generic licenced drug available worldwide and manufactured to scale and is a potential candidate therapy for pandemic coronavirus disease 2019 (COVID-19). Azithromycin was widely used to treat severe SARS-CoV and MERS-CoV, but to date, no randomised data are available in any coronavirus infections.

Other ongoing trials are exploring short courses of azithromycin either in early disease, within the first 7 days of symptoms, when azithromycin’s antiviral properties may be important, or late in disease when anti-bacterial properties may reduce the risk of secondary bacterial infection. However, the molecule’s anti-inflammatory properties, including suppression of pulmonary macrophage-derived pro-inflammatory cytokines such as interleukins-1β, -6, -8, and -18 and cytokines G-CSF and GM-CSF may provide a distinct therapeutic benefit if given in as a prolonged course during the period of progression from moderate to severe disease.

Methods

ATOMIC2 is a phase II/III, multi-centre, prospective, open-label, two-arm randomised superiority clinical trial of azithromycin versus standard care for adults presenting to hospital with COVID-19 symptoms who are not admitted at initial presentation. We will enrol adults, ≥ 18 years of age assessed in acute hospitals in the UK with clinical diagnosis of COVID-19 infection where management on an ambulatory care pathway is deemed appropriate. Participants will be randomised in a 1:1 ratio to usual care or to azithromycin 500 mg orally daily for 14 days with telephone follow-up at days 14 and 28. The primary objective is to compare the proportion with either death or respiratory failure requiring invasive or non-invasive mechanical ventilation over 28 days from randomisation. Secondary objectives include mortality/respiratory failure in those with a PCR-confirmed diagnosis; all-cause mortality; progression to pneumonia; progression to severe pneumonia; peak severity of illness and mechanistic analysis of blood and nasal biomarkers.

Discussion

This trial will determine the clinical utility of azithromycin in patients with moderately severe, clinically diagnosed COVID-19 and could be rapidly applicable worldwide.

Trial registration

ClinicalTrials.gov NCT04381962. Registered on 11 May 2020. EudraCT identifier 2020-001740-26. Opened for accrual on 29 May 2020.

Antibiotic eluting sinus stents

OBJECTIVES

Chronic rhinosinusitis (CRS) is a multifactorial disease affecting up to 16% of the United States population and disproportionately affecting the cystic fibrosis (CF) patient population. Despite treating the underlying infection, the use of systemic antibiotics has shown little efficacy in alleviation of symptom burden. This review seeks to discuss recent research on novel antibiotic eluting stent therapy in vitro and within animal models as well as the factors that contribute to its efficacy.

DATA SOURCES

PubMed literature review.

REVIEW METHODS

A review of all published literature related to antibiotic eluting sinus stents was conducted to integrate and summarize this innovative approach to chronic sinus infections.

RESULTS

Placement of the ciprofloxacin sinus stent (CSS) and ciprofloxacin-ivacaftor sinus stent (CISS) exhibited improvement in endoscopic and radiographic findings in rabbit CRS models. While the CSS showed an overall trend toward improvement in microscopic findings and a reduction in biofilm mass, there remained a significant quantity of planktonic bacteria due to antibiotic depletion from an initial burst release in the first 48 hours of stent placement. The CISS and ciprofloxacin-azithromycin sinus stents (CASSs) exhibited controlled antibiotic release over the study period leading to greatly reduced planktonic bacterial load and biofilm mass. In vitro studies indicate that CASS may be just as efficacious at reducing biofilm mass.

CONCLUSION

Antibiotic eluting sinus stents show significant promise as a novel therapeutic strategy for CRS. The CISS may have particular promise for the CF patient population by addressing both the infectious and genetic components of disease. Animal studies demonstrate significant promise for translation into human studies. Human clinical trials are warranted to determine the efficacy of antibiotic sinus stents in human patients.

LEVEL OF EVIDENCE

NA.

Low-dose macrolides for treating pediatric rhinosinusitis: A retrospective study and literature review

The effects of low-dose macrolide (LDM) therapy on pediatric chronic rhinosinusitis (CRS) patients are unknown. This study aimed to assess the effectiveness of LDM for treating pediatric refractory CRS. A retrospective study was conducted by a medical chart review. Pediatric CRS patients (age <15 years) who received LDM after standard medical treatments failure between 2013 and 2019 were identified. The LDM treatments with any macrolide agents, doses, and regimens were included. Any co-interventions were allowed. Duration of the LDM therapy was ≥6 weeks. Outcomes were the total nasal symptoms by the visual analogue scale (TNS), presence of individual symptoms, physician-assessment nasal discharge and adverse events. Six patients (67% male, mean age 7±3.4 years) were assessed. All patients had failed to intranasal steroids and nasal saline irrigation but continued. The addition of LDM significantly improved TNS (mean difference ± standard deviation 5.83 ± 1.33; 95% confidence interval 4.44-7.23, p< 0.001). At the end of treatment, the numbers of patients with individual symptoms were decreased: nasal obstruction (100%-67%), rhinorrhea (83%-50%), hyposmia (50%-0%), cough (100%-33%), and physician-assessment thick mucoid discharge (33%-0%). No patients had facial pain. One patient reported mild tolerable nausea. Preliminary findings of this study showed some beneficial effects of LDM added to intranasal steroids and nasal saline irrigation in pediatric CRS after standard treatments failure. The beneficial effects included the improvements of the TNS and individual nasal symptoms and decrease in thick mucoid discharge.

Evaluation of antifibrotic and antifungal combined therapies in experimental pulmonary paracoccidioidomycosis

Paracoccidioidomycosis (PCM) is a systemic mycosis caused by the Paracoccidioides genus. Most of the patients with chronic form present sequelae, like pulmonary fibrosis, with no effective treatment, leading to impaired lung functions. In the present study, we aimed to investigate the antifibrotic activity of three compounds: pentoxifylline (PTX), azithromycin (AZT), and thalidomide (Thal) in a murine model of pulmonary PCM treated with itraconazole (ITC) or cotrimoxazole (CMX). BALB/c mice were inoculated with P. brasiliensis (Pb) by the intratracheal route and after 8 weeks, they were submitted to one of the following six treatments: PTX/ITC, PTX/CMX, AZT/ITC, AZT/CMX, Thal/ITC, and Thal/CMX. After 8 weeks of treatment, the lungs were collected for determination of fungal burden, production of OH-proline, deposition of reticulin fibers, and pulmonary concentrations of cytokines and growth factors. Pb-infected mice treated with PTX/ITC presented a reduction in the pulmonary concentrations of OH-proline, associated with lower concentrations of interleukin (IL)-6, IL-17, and transforming growth factor (TGF)-β1 and higher concentrations of IL-10 compared to the controls. The Pb-infected mice treated with AZT/CMX exhibited decreased pulmonary concentrations of OH-proline associated with lower levels of TGF-β1, and higher levels of IL-10 compared controls. The mice treated with ITC/Thal and CMX/Thal showed intense weight loss, increased deposition of reticulin fibers, high pulmonary concentrations of CCL3, IFN-γ and VEGF, and decreased concentrations of IL-6, IL-1β, IL-17, and TGF-β1. In conclusion, our findings reinforce the antifibrotic role of PTX only when associated with ITC, and AZT only when associated with CMX, but Thal did not show any action upon addition.

Azithromycin decreases Chlamydia pneumoniae-mediated Interleukin-4 responses but not Immunoglobulin E responses

BACKGROUND

Chlamydia pneumoniae is an obligate intracellular bacterium that causes respiratory infection. There may exist an association between C. pneumoniae, asthma, and production of immunoglobulin (Ig) E responses in vitro. Interleukin (IL-4) is required for IgE production.

OBJECTIVE

We previously demonstrated that doxycycline suppresses C. pneumoniae-induced production of IgE and IL-4 responses in peripheral blood mononuclear cells (PBMC) from asthmatic subjects. Whereas macrolides have anti-chlamydial activity, their effect on in vitro anti-inflammatory (IgE) and IL-4 responses to C. pneumoniae have not been studied.

METHODS

PBMC from IgE- adult atopic subjects (N = 5) were infected +/- C. pneumoniae BAL69, +/- azithromycin (0.1, 1.0 ug/mL) for 10 days. IL-4 and IgE levels were determined in supernatants by ELISA. IL-4 and IgE were detected in supernatants of PBMC (day 10).

RESULTS

When azithromycin (0.1, 1.0 ug/ml) was added, IL-4 levels decreased. At low dose, IgE levels increased and at high dose, IgE levels decreased. When PBMC were infected with C. pneumoniae, both IL-4 and IgE levels decreased. Addition of azithromycin (0.1, 1.0 ug/mL) decreased IL-4 levels and had no effect on IgE levels.

CONCLUSIONS

These findings indicate that azithromycin decreases IL-4 responses but has a bimodal effect on IgE responses in PBMC from atopic patients in vitro.

Phase 2 study of clarithromycin, pomalidomide, and dexamethasone in relapsed or refractory multiple myeloma

The addition of clarithromycin enhances the efficacy of lenalidomide plus dexamethasone in treatment-naive multiple myeloma (MM). We conducted a phase 2 trial to evaluate the safety and efficacy of clarithromycin, pomalidomide, and dexamethasone (ClaPd) in relapsed or refractory multiple myeloma (RRMM) with prior lenalidomide exposure. One hundred twenty patients with a median of 5 prior lines of therapy received clarithromycin 500 mg orally twice daily, pomalidomide 4 mg orally on days 1 to 21, and dexamethasone 40 mg orally on days 1, 8, 15, and 22 of a 28-day cycle. The overall response rate (ORR) was 60% with 23% achieving at least a very good partial response. There was no statistical difference in response rates for patients who were refractory to lenalidomide (ORR, 58%), bortezomib (ORR, 55%), or both lenalidomide and bortezomib (ORR, 54%). Median progression-free survival (PFS) for the cohort was 7.7 months and median overall survival (OS) was 19.2 months. A history of dual-refractoriness to lenalidomide and bortezomib did not significantly impact either PFS or OS. The most common toxicities were neutropenia (83%), lymphopenia (74%), and thrombocytopenia (71%). The most common grade ≥3 toxicities included neutropenia (58%), thrombocytopenia (31%), and anemia (28%). ClaPd is an effective combination in RRMM with response and survival outcomes that are independent of lenalidomide- or bortezomib-refractory status. Toxicities are manageable with low rates of nonhematologic or high-grade events. ClaPd is a convenient, all-oral option in RRMM with comparable efficacy to other highly active, 3-drug, pomalidomide-based combinations. This trial was registered at www.clinicaltrials.gov as #NCT01159574.

Azithromycin suppresses Th1- and Th2-related chemokines IP-10/MDC in human monocytic cell line

BACKGROUND

Cytokines and chemokines play critical roles in the pathogenesis of asthma. Azithromycin, a macrolides, is frequently used in asthmatic children with lower respiratory tract infection and is reported having anti-inflammatory and immunomodulatory effects. However, the effects of azithromycin on the expression of TNF-α, Th1- and Th2-related chemokines, and neutrophil chemoattractant are unknown. We investigated the in vitro effects of azithromycin on the expression of TNF-α, Th1-related chemokine interferon-γ-inducible protein-10 (IP-10/CXCL10), Th2-related chemokine macrophage-derived chemokine (MDC/CCL22) and neutrophil chemoattractant growth-related oncogene-α (GRO-α/CXCL1) in THP-1 cells as a model for human monocytes.

METHODS

THP-1 cells were pretreated with various concentrations of azithromycin before Toll-like receptor 4 (TLR4) agonist lipopolysaccharide (LPS) stimulation. TNF-α, IP-10, MDC and GRO-α were measured by ELISA. Intracellular signaling was investigated by pathway inhibitors and Western blot.

RESULT

Azithromycin suppressed MDC and IP-10 expression in LPS-stimulated THP-1 cells. However, azithromycin had no effect LPS-induced TNF-α and GRO-α expression. Western blotting revealed that azithromycin suppressed LPS-induced phosphorylation of mitogen-activated protein kinase (MAPK)-JNK and ERK expression, and also suppressed LPS-induced phosphorylation of nuclear factor (NF) κB-p65 expression.

CONCLUSION

Azithromycin suppressed LPS-induced MDC expression via the MAPK-JNK and the NFκB-p65 pathway. Azithromycin also suppressed LPS-induced IP-10 via the MAPK-JNK/ERK and the NFκB-p65 pathway. Azithromycin may benefit asthmatic patients by suppressing chemokines expression.

Comparing the Effects of the mTOR Inhibitors Azithromycin and Rapamycin on In Vitro Expanded Regulatory T Cells

Adoptive transfer of autologous polyclonal regulatory T cells (Tregs) is a promising option for reducing graft rejection in allogeneic transplantation. To gain therapeutic levels of Tregs there is a need to expand obtained cells ex vivo, usually in the presence of the mTOR inhibitor Rapamycin due to its ability to suppress proliferation of non-Treg T cells, thus promoting a purer Treg yield. Azithromycin is a bacteriostatic macrolide with mTOR inhibitory activity that has been shown to exert immunomodulatory effects on several types of immune cells. In this study we investigated the effects of Azithromycin, compared with Rapamycin, on Treg phenotype, growth, and function when expanding bulk, naïve, and memory Tregs. Furthermore, the intracellular concentration of Rapamycin in CD4+ T cells as well as in the culture medium was measured for up to 48 h after supplemented. Treg phenotype was assessed by flow cytometry and Treg function was measured as inhibition of responder T-cell expansion in a suppression assay. The concentration of Rapamycin was quantified with liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS). Azithromycin and Rapamycin both promoted a FoxP3-positive Treg phenotype in bulk Tregs, while Rapamycin also increased FoxP3 and FoxP3+Helios positivity in naïve and memory Tregs. Furthermore, Rapamycin inhibited the expansion of naïve Tregs, but also increased their suppressive effect. Rapamycin was quickly degraded in 37°C medium, yet was retained intracellularly. While both compounds may benefit expansion of FoxP3+ Tregs in vitro, further studies elucidating the effects of Azithromycin treatment on Tregs are needed to determine its potential use.

Randomized controlled trial on immunomodulatory effects of azithromycin in children with steroid-dependent nephrotic syndrome

BACKGROUND

Azithromycin (AZM) is a macrolide antibiotic with anti-inflammatory and immunomodulatory effects. Our aim was to compare the immunomodulatory effects of AZM combined with steroid therapy with that of steroid therapy alone in children with steroid-dependent nephrotic syndrome (SDNS).

METHODS

We enrolled 57 patients with SDNS in a multicenter randomized control trial. Patients were classified into two groups: group A (intervention group, N = 29) and group B (control group, N = 28). After achievement of remission with full-dose daily prednisone, patients in group A received AZM in conjunction with steroids which was tapered gradually, while patients in group B received steroids alone. Urine protein creatinine ratio (uPCR) and TNF-α were measured at different points of follow-up throughout the study period (5 months after achieving remission).

RESULTS

After achievement of remission by full-dose steroids, there were significant differences of TNF-α between the two groups after 1-, 3- and 5-month follow-up (p < 0.001, 0.003, and 0.001, respectively). Also, there was significant difference of TNF-α in both intervention and control groups after exclusion of the relapsed cases at 3- and 5-month follow-up (, p = 0.031 and p = 0.003, respectively). There was significant difference between both groups after 5-month follow-up as regards the number of relapsed patients (group A = 4, group B = 11, p = 0.015).

CONCLUSION

AZM was capable of reducing serum TNF-α which is one of the inflammatory cytokines implicated in the pathogenesis of NS.

Doxycycline suppresses Chlamydia pneumoniae induced interferon-gamma responses in peripheral blood mononuclear cells in children with allergic asthma

Persistent respiratory infections caused by Chlamydia pneumoniae have been implicated in the pathogenesis of chronic diseases (e.g. asthma). Antibiotics are used to treat C. pneumoniae respiratory infections; however, the use of antibiotics as anti-inflammatory agents in treatment of asthma remains controversial. The current study investigated whether ciprofloxacin, azithromycin, or doxycycline can suppress C. pneumoniae-induced production of immunoglobulin (Ig) E or cytokines in peripheral blood mononuclear cells (PBMC) obtained from asthmatic children. Apart from blood, nasopharyngeal swab specimens were also collected to test for the presence of C. pneumoniae and/or M. pneumoniae (qPCR). PBMC (1.5 x 10⁶) from asthmatic pediatric patients (N = 18) were infected or mock infected for 1 h ± C. pneumoniae AR-39 at a multiplicity of infection (MOI) = 0.1, and cultured ± ciprofloxacin, azithromycin, or doxycycline (0.1 or 1.0 μg/mLmL) for either 48 h (cytokines) or 10 days (IgE). Interleukin (IL)-4, interferon (IFN)-γ and IgE levels in supernatants were measured (ELISA). When PBMC were infected with C. pneumoniae, IL-4 and IFNγ production increased (p = 0.06 and 0.03, respectively); IgE levels were low. The now-elevated levels of IL-4 didn't decrease significantly after addition of ciprofloxacin, azithromycin, or doxycycline. However, infected PBMC IFNγ formation decreased significantly when 0.1 μg/mL doxycycline was employed (p = 0.04); no dose of ciprofloxacin or azithromycin had any impact. This inhibitory outcome with doxycycline lends support to the use of tetracyclines as immune modulators and anti-inflammatory medications in treatment of C. pneumoniae-infected asthma patients.

Successful treatment with clarithromycin and/or tacrolimus for two patients with polymyalgia rheumatica

Polymyalgia rheumatica (PMR) is an inflammatory rheumatic disease in the elderly. Glucocorticoids (GCs) remain the mainstay of treatment. GC therapy usually dramatically improves the clinical picture, but approximately one-third of patients experience disease recurrence when the dose is reduced. Moreover, long-term use of GCs causes adverse reactions. Macrolide antibiotics have anti-inflammatory action. Several recent studies have reported the successful treatment of rheumatoid arthritis (RA) and PMR treated using clarithromycin (CAM), a macrolide, because of its anti-inflammatory action. Tacrolimus (TAC) has been indicated as a treatment for RA in patients who failed to respond to methotrexate. Recently, a case of RA was successfully treated using CAM and TAC according to one report. Reported here are two cases of PMR treated using CAM and/or TAC. Case 1: A 73-year-old man suffering from PMR was successfully treated with prednisolone (PSL) and CAM. Because his muscle pain disappeared, CAM was discontinued. However, the pain returned after that discontinuation, so CAM was successfully administered again. Case 2: An 83-year-old man suffering from PMR was successfully treated with PSL and CAM. Because muscle pain disappeared, the CAM dosage was halved. The pain returned after the dosage was reduced, so the CAM dosage was successfully resumed and the PSL dosage was reduced. When the PSL dosage was reduced, muscle pain recurred. Because the PSL and CAM dosages were not successfully increased, TAC was also administered and was found to be effective at treating muscle pain. These two cases suggest that CAM and/or TAC are effective at treating PMR.

The Role of Macrolides in Chronic Rhinosinusitis (CRSsNP and CRSwNP)

PURPOSE OF REVIEW

We assess the literature on the pharmacokinetics, indications, important considerations, and effectiveness of long-term, low-dose macrolide antibiotics in chronic rhinosinusitis (CRS).

RECENT FINDINGS

The key to effective implementation of macrolide therapy in CRS is appropriate patient selection. Macrolides have demonstrated the most benefit in Th1-mediated non-eosinophilic CRS when used for durations of at least 3 months. Macrolide antibiotics have demonstrated great benefit when used for their anti-inflammatory or immunomodulatory properties, which include the blockage of pro-inflammatory cytokines, such as interleukin (IL)-8 and tumor necrosis factor-α (TNF-α). They have been used in CRS patients not responding to traditional corticosteroid-based treatment regimens, but appear to be most effective specifically in Th1-mediated non-eosinophilic CRS in long durations and low doses. Further research is needed to better identify characteristics known to correlate with macrolide response so early directed therapy can be implemented.

Azithromycin and risk of COPD exacerbations in patients with and without Helicobacter pylori

BACKGROUND

Helicobacter pylori (HP) infection is associated with reduced lung function and systemic inflammation in chronic obstructive pulmonary disease (COPD) patients. Azithromycin (AZ) is active against HP and reduces the risk of COPD exacerbation. We determined whether HP infection status modifies the effects of AZ in COPD patients.

METHODS

Plasma samples from 1018 subjects with COPD who participated in the Macrolide Azithromycin (MACRO) in COPD Study were used to determine the HP infection status at baseline and 12 months of follow-up using a serologic assay. Based on HP infection status and randomization to either AZ or placebo (PL), the subjects were divided into 4 groups: HP+/AZ, HP-/AZ, HP+/PL, and HP-/PL. Time to first exacerbation was compared across the 4 groups using Kaplan-Meier survival analysis and a Cox proportional hazards model. The rates of exacerbation were compared using both the Kruskal-Wallis test and negative binomial analysis. Blood biomarkers at enrolment and at follow-up visits 3, 12, and 13 (1 month after treatment was stopped) months were measured.

RESULTS

One hundred eighty one (17.8%) patients were seropositive to HP. Non-Caucasian participants were nearly three times more likely to be HP seropositive than Caucasian participants (37.4% vs 13.6%; p < 0.001). The median time to first exacerbation was significantly different across the four groups (p = 0.001) with the longest time in the HP+/AZ group (11.2 months, 95% CI; 8.4-12.5+) followed by the HP-/AZ group (8.0 months, 95% CI; 6.7-9.7). Hazard ratio (HR) for exacerbations was lowest in the HP+/AZ group after adjustment for age, sex, smoking status, ethnicity, history of peptic ulcer, dyspnea, previous hospital admission, GOLD grade of severity, and forced vital capacity (HR, 0.612; 95% CI, 0.442-0.846 vs HR, 0.789; 95% CI, 0.663-0.938 in the HP-/AZ group). Circulating levels of soluble tumor necrosis factor receptor-75 were reduced only in the HP+/AZ group after 3 months of AZ treatment (-0.87 ± 0.31 μg/L; p = 0.002); levels returned to baseline after discontinuing AZ.

CONCLUSIONS

AZ is effective in preventing COPD exacerbations in patients with HP seropositivity, possibly by modulating TNF pathways related to HP infection.

Subantibiotic dose of azithromycin attenuates alveolar bone destruction and improves trabecular microarchitectures in a rat model of experimental periodontitis: A study using micro-computed tomography

Azithromycin, a macrolide antibiotic, has anti-inflammatory and immunomodulatory activities apart from its antibacterial properties. In this study, we examined the efficacy of subantibiotic dose of azithromycin on ligature-induced periodontitis in rats using micro-computed tomography (micro-CT) imaging and bone parameter analysis. Male Sprague-Dawley rats were allocated to the following four groups: non-ligation (NL) group; ligation-only (L) group; ligation-plus-subantibiotic dose azithromycin (SA) group; and 4) ligation-plus-antibiotic dose azithromycin (AA) group. The rats from Groups L, SA and AA were subjected to periodontitis by placing a ligature around lower right first molar. Immediately after ligation, the rats in SA and AA groups received daily intraperitoneal injections of azithromycin at a dosage of 3.5 or 10mg/kg body weight, respectively. The ligatures were maintained for 2weeks at which time the rats had their mandibles hemisected for micro-CT analysis. Subantibiotic dose of azithromycin strongly suppressed reductions in alveolar bone height and bone volume fraction caused by experimental periodontitis. When subantibiotic dosage of azithromycin was administered to rats, ligature-induced alterations in microarchitectural parameters of trabecular bone were significantly reversed. Rats treated with subantibiotic dose of azithromycin presented no significant difference compared to rats with antibiotic dosage in all parameters. While further studies are necessary, subantibiotic dose of azithromycin could be utilized as a host modulator for the treatment of periodontitis.

Usefulness of targeting lymphocyte Kv1.3-channels in the treatment of respiratory diseases

T lymphocytes predominantly express delayed rectifier K(+)-channels (Kv1.3) in their plasma membranes. Patch-clamp studies revealed that the channels play crucial roles in facilitating the calcium influx necessary to trigger lymphocyte activation and proliferation. Using selective channel inhibitors in experimental animal models, in vivo studies further revealed the clinically relevant relationship between the channel expression and the development of chronic respiratory diseases, in which chronic inflammation or the overstimulation of cellular immunity in the airways is responsible for the pathogenesis. In chronic respiratory diseases, such as chronic obstructive pulmonary disease, asthma, diffuse panbronchiolitis and cystic fibrosis, in addition to the supportive management for the symptoms, the anti-inflammatory effects of macrolide antibiotics were shown to be effective against the over-activation or proliferation of T lymphocytes. Recently, we provided physiological and pharmacological evidence that macrolide antibiotics, together with calcium channel blockers, HMG-CoA reductase inhibitors, and nonsteroidal anti-inflammatory drugs, effectively suppress the Kv1.3-channel currents in lymphocytes, and thus exert anti-inflammatory or immunomodulatory effects. In this review article, based on the findings obtained from recent in vivo and in vitro studies, we address the novel therapeutic implications of targeting the lymphocyte Kv1.3-channels for the treatment of chronic or acute respiratory diseases.

Azithromycin inhibits IL-1 secretion and non-canonical inflammasome activation

Deregulation of inflammasome activation was recently identified to be involved in the pathogenesis of various inflammatory diseases. Although macrolide antibiotics display well described immunomodulatory properties, presumably involved in their clinical effects, their impact on inflammasome activation has not been investigated. We compared the influence of macrolides on cytokine induction in human monocytes. The role of intracellular azithromycin-accumulation was examined by interference with Ca⁺⁺-dependent uptake. We have also analysed the signalling cascades involved in inflammasome activation, and substantiated the findings in a murine sepsis model. Azithromycin, but not clarithromycin or roxithromycin, specifically inhibited IL-1α and IL-1β secretion upon LPS stimulation. Interference with Ca⁺⁺-dependent uptake abolished the cytokine-modulatory effect, suggesting a role of intracellular azithromycin accumulation in the modulatory role of this macrolide. Azithromycin’s inhibiting effects were observed upon LPS, but not upon flagellin, stimulation. Consistent with this observation, we found impaired induction of the LPS-sensing caspase-4 whereas NF-κB signalling was unaffected. Furthermore, azithromycin specifically affected IL-1β levels in a murine endotoxin sepsis model. We provide the first evidence of a differential impact of macrolides on the inflammasome/IL-1β axis, which may be of relevance in inflammasome-driven diseases such as chronic obstructive pulmonary disease or asthma.

Roles of lymphocyte kv1.3-channels in the pathogenesis of renal diseases and novel therapeutic implications of targeting the channels

Delayed rectifier K⁺-channels (Kv1.3) are predominantly expressed in T lymphocytes. Based on patch-clamp studies, the channels play crucial roles in facilitating the calcium influx necessary to trigger lymphocyte activation and proliferation. Using selective channel inhibitors in experimental animal models, in vivo studies then revealed the clinically relevant relationship between the channel expression and the pathogenesis of autoimmune diseases. In renal diseases, in which “chronic inflammation” or “the overstimulation of cellular immunity” is responsible for the pathogenesis, the overexpression of Kv1.3-channels in lymphocytes promotes their cellular proliferation and thus contributes to the progression of tubulointerstitial fibrosis. We recently demonstrated that benidipine, a potent dihydropyridine calcium channel blocker, which also strongly and persistently inhibits the lymphocyte Kv1.3-channel currents, suppressed the proliferation of kidney lymphocytes and actually ameliorated the progression of renal fibrosis. Based on the recent in vitro evidence that revealed the pharmacological properties of the channels, the most recent studies have revealed novel therapeutic implications of targeting the lymphocyte Kv1.3-channels for the treatment of renal diseases.

Relationship between azithromycin susceptibility and administration efficacy for nontypeable Haemophilus influenzae respiratory infection

Nontypeable Haemophilus influenzae (NTHI) is an opportunistic pathogen that is an important cause of acute exacerbations of chronic obstructive pulmonary disease (AECOPD). COPD is an inflammatory disease of the airways, and exacerbations are acute inflammatory events superimposed on this background of chronic inflammation. Azithromycin (AZM) is a macrolide antibiotic with antibacterial and anti-inflammatory properties and a clinically proven potential for AECOPD prevention and management. Relationships between AZM efficacy and resistance by NTHI and between bactericidal and immunomodulatory effects on NTHI respiratory infection have not been addressed. In this study, we employed two pathogenic NTHI strains with different AZM susceptibilities (NTHI 375 [AZM susceptible] and NTHI 353 [AZM resistant]) to evaluate the prophylactic and therapeutic effects of AZM on the NTHI-host interplay. At the cellular level, AZM was bactericidal toward intracellular NTHI inside alveolar and bronchial epithelia and alveolar macrophages, and it enhanced NTHI phagocytosis by the latter cell type. These effects correlated with the strain MIC of AZM and the antibiotic dose. Additionally, the effect of AZM on NTHI infection was assessed in a mouse model of pulmonary infection. AZM showed both preventive and therapeutic efficacies by lowering NTHI 375 bacterial counts in lungs and bronchoalveolar lavage fluid (BALF) and by reducing histopathological inflammatory lesions in the upper and lower airways of mice. Conversely, AZM did not reduce bacterial loads in animals infected with NTHI 353, in which case a milder anti-inflammatory effect was also observed. Together, the results of this work link the bactericidal and anti-inflammatory effects of AZM and frame the efficacy of this antibiotic against NTHI respiratory infection.

Linezolid has unique immunomodulatory effects in post-influenza community acquired MRSA pneumonia

Introduction

Post influenza pneumonia is a leading cause of mortality and morbidity, with mortality rates approaching 60% when bacterial infections are secondary to multi-drug resistant (MDR) pathogens. Staphylococcus aureus, in particular community acquired MRSA (cMRSA), has emerged as a leading cause of post influenza pneumonia.

Hypothesis

Linezolid (LZD) prevents acute lung injury in murine model of post influenza bacterial pneumonia

Methods

Mice were infected with HINI strain of influenza and then challenged with cMRSA at day 7, treated with antibiotics (LZD or Vanco) or vehicle 6 hours post bacterial challenge and lungs and bronchoalveolar lavage fluid (BAL) harvested at 24 hours for bacterial clearance, inflammatory cell influx, cytokine/chemokine analysis and assessment of lung injury.

Results

Mice treated with LZD or Vanco had lower bacterial burden in the lung and no systemic dissemination, as compared to the control (no antibiotic) group at 24 hours post bacterial challenge. As compared to animals receiving Vanco, LZD group had significantly lower numbers of neutrophils in the BAL (9×10³ vs. 2.3×10⁴, p < 0.01), which was associated with reduced levels of chemotactic chemokines and inflammatory cytokines KC, MIP-2, IFN-γ, TNF-α and IL-1β in the BAL. Interestingly, LZD treatment also protected mice from lung injury, as assessed by albumin concentration in the BAL post treatment with H1N1 and cMRSA when compared to vanco treatment. Moreover, treatment with LZD was associated with significantly lower levels of PVL toxin in lungs.

Conclusion

Linezolid has unique immunomodulatory effects on host inflammatory response and lung injury in a murine model of post-viral cMRSA pneumonia.

Physiological significance of delayed rectifier K(+) channels (Kv1.3) expressed in T lymphocytes and their pathological significance in chronic kidney disease

T lymphocytes predominantly express delayed rectifier K(+) channels (Kv1.3) in their plasma membranes. More than 30 years ago, patch-clamp studies revealed that the channels play crucial roles in facilitating the calcium influx necessary to trigger lymphocyte activation and proliferation. In addition to selective channel inhibitors that have been developed, we recently showed physiological evidence that drugs such as nonsteroidal anti-inflammatory drugs, antibiotics, and anti-hypertensives effectively suppress the channel currents in lymphocytes, and thus exert immunosuppressive effects. Using experimental animal models, previous studies revealed the pathological relevance between the expression of ion channels and the progression of renal diseases. As an extension, we recently demonstrated that the overexpression of lymphocyte Kv1.3 channels contributed to the progression of chronic kidney disease (CKD) by promoting cellular proliferation and interstitial fibrosis. Together with our in-vitro results, the studies indicated the therapeutic potency of Kv1.3-channel inhibitors in the treatment or the prevention of CKD.

Azithromycin suppresses CD4(+) T-cell activation by direct modulation of mTOR activity

Advanced macrolides, such as azithromycin (AZM) or clarithromycin (CLM), are antibiotics with immunomodulatory properties. Here we have sought to evaluate their in vitro influence on the activation of CD4(+) T-cells. Isolated CD4(+) T-cells were stimulated with agonistic anti-CD3/anti-CD28 monoclonal antibodies in the presence of 0.6 mg/L, 2.5 mg/L, 10 mg/L or 40 mg/L AZM or CLM. Cell proliferation, cytokine level in supernatants and cell viability was assessed. Intracellular signaling pathways were evaluated using reporter cell lines, FACS analysis, immunoblotting and in vitro kinase assays. AZM inhibited cell proliferation rate and cytokine secretion of CD4(+) T-cells in a dose-dependent manner. Similarly, high concentrations of CLM (40 mg/L) also suppressed these T-cell functions. Analysis of molecular signaling pathways revealed that exposure to AZM reduced the phosphorylation of the S6 ribosomal protein, a downstream target of mTOR. This effect was also observed at 40 mg/L CLM. In vitro kinase studies using recombinant mTOR showed that AZM inhibited mTOR activity. In contrast to rapamycin, this inhibition was independent of FKBP12. We show for the first time that AZM and to a lesser extent CLM act as immunosuppressive agents on CD4(+) T-cells by inhibiting mTOR activity. Our results might have implications for the clinical use of macrolides.

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.

Combination therapy with ampicillin and azithromycin in an experimental pneumococcal pneumonia is bactericidal and effective in down regulating inflammation in mice

Objectives

Emergence of multidrug resistance among Streptococcus pneumoniae (SP), has limited the available options used to treat infections caused by this organism. The objective of this study was to compare the role of monotherapy and combination therapy with ampicillin (AMP) and azithromycin (AZM) in eradicating bacterial burden and down regulating lung inflammation in a murine experimental pneumococcal infection model.

Methods

Balb/C mice were infected with 10⁶ CFU of SP. Treatments with intravenous ampicillin (200 mg/kg) and azithromycin (50 mg/kg) either alone or in combination was initiated 18 h post infection, animals were sacrificed from 0 – 6 h after initiation of treatment. AMP and AZM were quantified in serum by microbiological assay. Levels of TNF-α, IFN-γ IL-6, and IL-10 in serum and in lungs, along with myeloperoxidase, inflammatory cell count in broncho alveolar lavage fluid, COX-2 and histopathological changes in lungs were estimated.

Results

Combination therapy down regulated lung inflammation and accelerated bacterial clearance. This approach also significantly decreased TNF-α, IFN-γ, IL-6 and increased IL-10 level in serum and lungs along with decreased myeloperoxidase, pulmonary vascular permeability, inflammatory cell numbers and COX-2 levels in lungs.

Conclusions

Combinatorial therapy resulted in comparable bactericidal activity against the multi-drug resistant isolate and may represent an alternative dosing strategy, which may help to alleviate problems with pneumococcal pneumonia.

Macrolides attenuate phorbol ester-induced tumor necrosis factor-α and mucin production from human airway epithelial cells

BACKGROUND/AIMS

Macrolide antibiotics are effective drugs in chronic bronchiolitis and chronic rhinosinusitis with mucus hypersecretion. However, the mechanism of action is unclear. This study was designed to investigate the effect of azithromycin (AZM; 15-membered) and midecamycin acetate (MDM; 16-membered) on MUC5AC and MUC2 gene expression and secretion from human airway epithelial cells. The effects of the two macrolides on tumor necrosis factor-α (TNF-α) release were also examined.

METHODS

Confluent NCI-H292 human mucoepidermoid airways epithelial cells were pretreated with AZM or MDM for 2 h and then stimulated with 200 nmol/l phorbol 12-myristate 13-acetate (PMA) for 8 h. The MUC5AC and MUC2 gene expression was measured by real-time quantitative RT-PCR. Total mucin in culture supernatants was measured using enzyme-linked lectin assay. Enzyme-linked immunosorbent assay was used to determine MUC5AC, MUC2 and TNF-α released by the cells.

RESULTS

AZM and MDM attenuated PMA-induced MUC5AC and MUC2 gene and protein expression in NCI-H292 cells. They also suppressed PMA-mediated TNF-α in the cells.

CONCLUSION

The present study demonstrates that AZM and MDM suppress the synthesis of mucin and TNF-α from human airway epithelial cells.

Differential effects of clarithromycin and azithromycin on delayed rectifier K(+)-channel currents in murine thymocytes

CONTEXT

Lymphocytes predominantly express delayed rectifier K(+)-channels (Kv1.3) in their plasma membranes, and the channels play crucial roles in the lymphocyte activation and proliferation. Since macrolide antibiotics, such as clarithromycin and azithromycin, exert immunomodulatory effects, they would affect the Kv1.3-channel currents in lymphocytes.

OBJECTIVE

This study determined the physiological involvement in the mechanisms of immunomodulation by these antibiotics.

MATERIALS AND METHODS

Employing the standard patch-clamp whole-cell recording technique in murine thymocytes, we examined the effects of 30 and 100 µM clarithromycin and azithromycin on the Kv1.3-channel currents and the membrane capacitance.

RESULTS

Clarithromycin significantly suppressed the peak currents (30 µM, 178 ± 5.6 to 111 ± 2.0 pA/pF; 100 µM, 277 ± 4.4 to 89.6 ± 10 pA/pF) and the pulse-end currents (30 µM, 47.5 ± 2.2% to 15.5 ± 3.3%; 100 µM, 48.5 ± 1.4% to 15.8 ± 1.0%) of thymocyte Kv1.3-channels without significant effects on the membrane capacitance. In contrast, azithromycin did not affect the channel currents. However, it significantly decreased the membrane capacitance (30 µM, 4.68 ± 0.14 to 3.74 ± 0.13 pF; 100 µM, 4.47 ± 0.06 to 3.37 ± 0.08 pF), indicating its accumulation in the plasma membrane.

DISCUSSION AND CONCLUSION

This study demonstrated for the first time that clarithromycin exerts inhibitory effects on thymocyte Kv1.3-channel currents, while azithromycin decreases the membrane capacitance without affecting the channel currents. These differences in the effects of the macrolide antibiotics may reflect differences in the mechanisms of immunomodulation by which they control the production of cytokines.

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

Acute graft-versus-host disease (GVHD) following allogeneic bone marrow transplantation (BMT) is initiated by donor T lymphocytes that recognize histocompatibility antigens presented by recipient dendritic cells (DCs). Current approaches to reduce GVHD are focused on suppressing donor T lymphocyte responses to alloantigens. However, these strategies may be inadequate in the setting of allogeneic transplants (particularly histoincompatible transplants), may increase the risk of tumour relapse and are associated with high rates of opportunistic infections. We hypothesized that inhibition of recipient DCs might suppress GVHD. We recently demonstrated in vitro that azithromycin, a macrolide antibiotic, also acts as a nuclear factor (NF)-κB inhibitor of murine DCs and inhibits their maturation and functions, including allogeneic responses. We investigated whether azithromycin could prevent alloreactions in a murine histoincompatibility model. Oral administration of azithromycin to recipient mice for 5 days during major-histoincompatible BMT suppressed lethal GVHD significantly, whereas ex-vivo lymphocyte function was not affected by the drug. These data suggest that azithromycin has potential as a novel prophylactic drug for lethal GVHD.

Anti-inflammatory and immunomodulatory properties of azithromycin involved in treatment and prevention of chronic lung allograft rejection

Chronic lung allograft rejection is the single most important cause of death in lung transplant recipients after the first postoperative year, resulting in a 5-year survival rate of approximately 50%, which is far behind that of other solid organ transplantations. Spirometry is routinely used as a clinical marker for assessing pulmonary allograft function and diagnosing chronic lung allograft rejection after lung transplantation (LTx). As such, a progressive obstructive decline in pulmonary allograft function (forced expiratory volume in 1 sec [FEV1]) in absence of all other causes (currently defined as bronchiolitis obliterans syndrome [BOS]) is considered to reflect the evolution of chronic lung allograft rejection. BOS has a 5-year prevalence of approximately 45% and is thought to be the final common endpoint of various alloimmunologic and nonalloimmunologic injuries to the pulmonary allograft, triggering different innate and adaptive immune responses. Most preventive and therapeutic strategies for this complex process have thus far been largely unsuccessful. However, the introduction of the neomacrolide antibiotic azithromycin (AZI) in the field of LTx as of 2003 made it clear that some patients with established BOS might in fact benefit from such therapy due to its various antiinflammatory and immunomodulatory properties, as summarized in this review. Particularly in patients with an increased bronchoalveolar lavage neutrophilia (i.e., 15%-20% or more), AZI treatment could result in an increase in FEV1 of at least 10%. More recently, it has become clear that prophylactic therapy with AZI actually may prevent BOS and improve FEV1 after LTx, most likely through its interactions with the innate immune system. However, one should always be aware of possible adverse effects related to AZI when implementing this drug as prophylactic or long-term treatment. Even so, AZI therapy after LTx can generally be considered as safe.

Topical azithromycin and clarithromycin inhibit acute and chronic skin inflammation in sensitized mice, with apparent selectivity for Th2-mediated processes in delayed-type hypersensitivity

Macrolide antibiotics inhibit the secretion of Th1 cytokines while their effects on the release of Th2 cytokines are variable. We investigated molecular and cellular markers of Th1- and Th2-mediated inflammatory mechanisms and the anti-inflammatory activity of azithromycin and clarithromycin in phorbol 12-myristate 13-acetate (PMA) and oxazolone (OXA)-induced skin inflammation. Dexamethasone (50 μg/ear), azithromycin, and clarithromycin (500 μg/ear) reduced TNF-α and interleukin (IL)-1β concentration in ear tissue by inhibiting inflammatory cell accumulation in PMA-induced inflammation. In OXA-induced early delayed-type hypersensitivity (DTH), the macrolides (2 mg/ear) and dexamethasone (25 μg/ear) reduced ear tissue inflammatory cell infiltration and secretion of IL-4 while clarithromycin also decreased IFN-γ concentration. Macrolides showed better activity when administered after the challenge. In OXA-induced chronic DTH, azithromycin (1 mg/ear) reduced the number of ear tissue mast cells and decreased the concentration of IL-4 in ear tissue and of immunoglobulin (Ig)E in serum. Clarithromycin (1 mg/ear) reduced serum IgE concentration, possibly by a mechanism independent of IL-4, while both macrolides attenuated mast cell degranulation. In conclusion, azithromycin and clarithromycin attenuate pro-inflammatory cytokine production and leukocyte infiltration during innate immune reactions, while selectively affecting Th2 rather than Th1 immunity in DTH reactions.

Clarithromycin therapy for patients with cystic fibrosis: a randomized controlled trial

The clinically significant actions of oral azithromycin in modifying progressive cystic fibrosis (CF) lung disease have been well documented. In vitro and clinical data suggests that clarithromycin has immunomodulatory properties similar to other 14-member macrolides, however two previously reported short term, open label trials of clairthromycin in small numbers of patients with CF failed to show significant benefits in modifying lung function or inflammation. We performed an international double blind, cross-over trial in which 63 subjects with CF were studied while receiving either placeo or 500 mg oral clarithromycin twice daily for 5 months, with a 1-month wash-out. The primary efficacy end point was the change in lung function (FEV(1) and FVC) during the clarithromycin treatment period compared to placebo treatment. Secondary efficacy end points included; quality of life, number of pulmonary exacerbations, height and weight, sputum inflammatory mediator content, sputum transportability and surface properties, bacterial flora, nasal potential difference, and breath condensate. No significant difference in either the primary efficacy end point or any secondary end point was seen during the period of clarithromycin treatment compared to those seen during placebo administration. We conclude that clarithromycin is not effective in treating CF lung disease.

The effect of azithromycin on the maturation and function of murine bone marrow-derived dendritic cells

Dendritic cells (DCs) are professional antigen-presenting cells capable of initiating primary/adaptive immune responses and tolerance. DC functions are regulated by their state of maturation. However, the molecular pathways leading to DC development and maturation remain poorly understood. We attempted to determine whether inhibition of nuclear factor kappa B (NF-κB), which is one of the pivotal pathways underlying these processes, could induce immunophenotypic and functional changes in lipopolysaccharide-induced mature DCs derived from murine bone marrow. A comparative in vitro study of five clinically used drugs that are known to inhibit NF-κB demonstrated that azithromycin, a macrolide antibiotic, significantly inhibited expression of co-stimulatory molecules (CD40 and CD86) and major histocompatibility complex (MHC) class II by DCs. It also reduced Toll-like receptor 4 expression, interleukin-12 production and the allostimulatory capacity of DCs. These data suggest that azithromycin, as not only an NF-κB inhibitor but also an antibiotic, has potential as a novel drug for manipulation of allogeneic responses.