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

Combinational therapy of mesenchymal stem cell-derived extracellular vesicles and azithromycin improves clinical and histopathological recovery in CLP sepsis model

BACKGROUND

Sepsis is a syndrome that occurs following an infection and marked by severe inflammatory responses, and if not treated in time, it can lead to multi-organ failure syndrome and death. This study examines the effects of a novel combination therapy using azithromycin and mesenchymal stem cell-derived extracellular vesicles (EVs) on a cecal ligation and puncture (CLP) model of sepsis.

METHODS

Human Wharton's jelly-mesenchymal stem cells were cultured, characterized, and used to extract EVs. The CLP sepsis model was induced in mice, followed by treatments: saline, AZM, EVs, and combination therapy (A+E). Clinical sepsis scores were recorded 24 h post-treatment. Serum, peritoneal fluid, and organ tissues (kidney, liver, lung) were collected and analyzed for biochemical parameters (AST ALT, and creatinine), inflammatory markers, bacterial load, and histopathological changes.

RESULTS

The A+E combined treatment improved the clinical scores of septic mice. The administration of A+E reduced bacterial loads in the peritoneum of septic mice, contributing to effective control of infection. Inflammatory markers of neutrophils-to-lymphocytes ratio (NLR) and TNF-α serum levels were significantly lower in the combinational therapy group, indicating significant anti-inflammatory effect of this combination. Additionally, combination of AZM and EVs alleviated organ damage mainly within liver, kidneys and lungs. Based on histopathological assessments and biochemical parameters, there was diminished tissue damage as well as reduced inflammation, which is correlated with improved functions of these vital organs.

CONCLUSION

The combined use of azithromycin and EVs offers a promising therapeutic approach for sepsis by effectively controlling infection and modulating the inflammatory response.

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

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

Membrane inflammasome activation by choriodecidual Ureaplasma parvum infection without intra-amniotic infection in a Non-Human Primate model†

Intrauterine infection is a significant cause of neonatal morbidity and mortality. Ureaplasma parvum is a microorganism commonly isolated from cases of preterm birth and preterm premature rupture of membranes (pPROM). However, the mechanisms of early stage ascending reproductive tract infection remain poorly understood. To examine inflammation in fetal (chorioamnionic) membranes we utilized a non-human primate (NHP) model of choriodecidual U. parvum infection. Eight chronically catheterized pregnant rhesus macaques underwent maternal-fetal catheterization surgery at ~105-112 days gestation and choriodecidual inoculation with U. parvum (105 CFU/mL, n =4) or sterile media (controls; n = 4) starting at 115-119 days, repeated at 5-day intervals until C-section at 136-140 days (term=167 days). The average inoculation to delivery interval was 21 days, and Ureaplasma infection of the amniotic fluid (AF) was undetectable in all animals. Choriodecidual Ureaplasma infection resulted in increased fetal membrane expression of MMP-9 and PTGS2, but did not result in preterm labor or increased concentrations of AF pro-inflammatory cytokines. However, membrane expression of inflammasome sensors, NLRP3, NLRC4, AIM2, and NOD2, and adaptor ASC (PYCARD) gene expression were significantly increased. Gene expression of IL-1β, IL-18, IL-18R1  , CASPASE-1, and pro-CASPASE-1 protein increased with Ureaplasma infection. Downstream inflammatory genes MYD88 and NFκB (Nuclear factor kappa-light-chain-enhancer of activated B cells) were also significantly upregulated. These results demonstrate that choriodecidual Ureaplasma infection, can cause activation of inflammasome complexes and pathways associated with pPROM and preterm labor prior to microbes being detectable in the AF.

Clinical Efficacy of Ulinastatin Combined with Azithromycin in the Treatment of Severe Pneumonia in Children and the Effects on Inflammatory Cytokines and Oxidative Stress: A Retrospective Cohort Study

Purpose

This retrospective cohort study aimed to evaluate the clinical efficacy of ulinastatin (UTI) and azithromycin (AZM) combination therapy in treating severe pneumonia in children and its impact on inflammatory cytokines and oxidative stress.

Patients and Methods

This retrospective cohort study was conducted from January 1, 2019, to January 1, 2021, involving pediatric patients diagnosed with severe mycoplasma pneumonia (SMPP). The pediatric patients were divided into two groups: those receiving UTI and AZM combination therapy (treatment group) and those receiving azithromycin alone (control group). We compared the two groups regarding clinical data, disease outcomes, inflammatory cytokines, and oxidative stress levels.

Results

Baseline characteristics did not significantly differ between the two groups. UTI, in combination with AZM, significantly improved blood oxygen levels, inflammatory infection markers, and relevant clinical symptoms in patients with SMPP on the 3rd day of treatment. Additionally, it significantly reduced the levels of inflammatory cytokines TNF-a, IL-6, IL-1β, and IL-10, as well as oxidative stress markers GSH and SOD.

Conclusion

Combining UTI and AZM can rapidly alleviate clinical symptoms and effectively control the progression of patients with SMPP. Therefore, this treatment approach deserves consideration for clinical promotion and utilization.

Membrane Inflammasome Activation by Choriodecidual Ureaplasma parvum Infection without Intra-Amniotic Infection in an NHP Model

Intrauterine infection is a significant cause of preterm labor and neonatal morbidity and mortality. Ureaplasma parvum is the micro-organism most commonly isolated from cases of preterm birth and preterm premature rupture of membranes (pPROM). However, the mechanisms during the early stages of ascending reproductive tract infection that initiate maternal-fetal inflammatory pathways, preterm birth and pPROM remain poorly understood. To examine inflammation in fetal (chorioamnionic) membranes in response to Ureaplasma parvum infection, we utilized a novel in vivo non-human primate model of early choriodecidual infection. Eight chronically catheterized pregnant rhesus macaques underwent maternal-fetal catheterization surgery at 105-112 days gestation and choriodecidual inoculation with Ureaplasma parvum (10 5 cfu/mL of a low passaged clinical isolate, serovar 1; n=4) or saline/sterile media (Controls; n=4) starting at 115-119 days gestation, repeated every 5 days until scheduled cesarean-section at 136-140d gestation (term=167d). The average inoculation to delivery interval was 21 days and Ureaplasma infection of the amniotic fluid was undetectable by culture and PCR in all animals. Inflammatory mediators in amniotic fluid (AF) were assessed by Luminex, ELISA and multiplex assays. RNA was extracted from the chorion and amnionic membranes for single gene analysis (qRT-PCR) and protein expression was determined by Western blot and immunohistochemistry. Our NHP model of choriodecidual Ureaplasma infection, representing an early-stage ascending reproductive tract infection without microbial invasion of the amniotic cavity, resulted in increased fetal membrane protein and gene expression of MMP-9 and PTGS2, but did not result in preterm labor (no increase in uterine contractility) or increased concentrations of amniotic fluid pro-inflammatory cytokines (IL-1β, IL-6, IL-8, IL-18, TNF-α). However, membrane expression of inflammasome sensor molecules, NLRP3, NLRC4, AIM2 and NOD2, and the adaptor protein ASC ( PYCARD ) gene expression were significantly increased in the Ureaplasma group when compared to non-infected controls. Gene expression of IL-1 β, IL-18, the IL-18R1 receptor , CASPASE-1 and pro-CASPASE-1 protein were also increased in the fetal membranes with Ureaplasma infection. Downstream inflammatory signaling genes MYD88 was also significantly upregulated in both the amnion and chorion, along with a significant increase in NFKB in the chorion. These results demonstrate that even at the early stages of ascending reproductive tract Ureaplasma infection, activation of inflammasome complexes and pathways associated with degradation of chorioamnionic membrane integrity are present. This study therefore provides experimental evidence for the importance of the early stages of ascending Ureaplasma infection in initiating processes of pPROM and preterm labor. These findings have implications for the identification of intrauterine inflammation before microbes are detectable in the amniotic fluid (sterile inflammation) and the timing of potential treatments for preterm labor and fetal injury caused by intrauterine infection.

Dual functional therapeutics: mitigating bacterial infection and associated inflammation

The emergence of antimicrobial resistance, coupled with the occurrence of persistent systemic infections, has already complicated clinical therapy efforts. Moreover, infections are also accompanied by strong inflammatory responses, generated by the host's innate and adaptive immune systems. The closely intertwined relationship between bacterial infection and inflammation has multiple implications on the ability of antibacterial therapeutics to tackle infection and inflammation. Particularly, uncontrolled inflammatory responses to infection can lead to sepsis, a life-threatening physiological condition. In this review, we discuss dual-functional antibacterial therapeutics that have potential to be developed for treating inflammation associated with bacterial infections. Immense research is underway that aims to develop new therapeutic agents that, when administered, regulate the excess inflammatory response, i.e. they have immunomodulatory properties along with the desired antibacterial activity. The classes of antibiotics that have immunomodulatory function in addition to antibacterial activity have been reviewed. Host defense peptides and their synthetic mimics are amongst the most sought-after solutions to develop such dual-functional therapeutics. This review also highlights the important classes of peptidomimetics that exhibit both antibacterial and immunomodulatory properties.

The Mechanism of Action and Clinical Efficacy of Low-Dose Long-Term Macrolide Therapy in Chronic Rhinosinusitis

Various chronic inflammatory airway diseases can be treated with low-dose, long-term (LDLT) macrolide therapy. LDLT macrolides can be one of the therapeutic options for chronic rhinosinusitis (CRS) due to their immunomodulatory and anti-inflammatory actions. Currently, various immunomodulatory mechanisms of the LDLT macrolide treatment have been reported, as well as their antimicrobial properties. Several mechanisms have already been identified in CRS, including reduced cytokines such as interleukin (IL)-8, IL-6, IL-1β, tumor necrosis factor-α, transforming growth factor-β, inhibition of neutrophil recruitment, decreased mucus secretion, and increased mucociliary transport. Although some evidence of effectiveness for CRS has been published, the efficacy of this therapy has been inconsistent across clinical studies. LDLT macrolides are generally believed to act on the non-type 2 inflammatory endotype of CRS. However, the effectiveness of LDLT macrolide treatment in CRS is still controversial. Here, we reviewed the immunological mechanisms related to CRS in LDLT macrolide therapy and the treatment effects according to the clinical situation of CRS.

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.

Azithromycin through the Lens of the COVID-19 Treatment

Azithromycin has become famous in the last two years, not for its main antimicrobial effect, but for its potential use as a therapeutic agent for COVID-19 infection. Initially, there were some promising results that supported its use, but it has become clear that scientific results are insufficient to support such a positive assessment. In this review we will present all the literature data concerning the activity of azithromycin as an antimicrobial, an anti-inflammatory, or an antivirus agent. Our aim is to conclude whether its selection should remain as a valuable antivirus agent or if its use simply has an indirect therapeutic contribution due to its antimicrobial and/or immunomodulatory activity, and therefore, if its further use for COVID-19 treatment should be interrupted. This halt will prevent further antibiotic resistance expansion and will keep azithromycin as a valuable anti-infective therapeutic agent.

Polyphenols, flavonoids and inflammasomes: the role of cigarette smoke in COPD

COPD is predicted to become the third leading cause of morbidity and mortality worldwide by 2030. Cigarette smoking (active or passive) is one of its chief causes, with about 20% of cigarette smokers developing COPD from cigarette smoke (CS)-induced irreversible damage and sustained inflammation of the airway epithelium. Inflammasome activation leads to the cleavage of pro-interleukin (IL)-1β and pro-IL-18, along with the release of pro-inflammatory cytokines via gasdermin D N-terminal fragment membrane pores, which further triggers acute phase pro-inflammatory responses and concurrent pyroptosis. There is currently intense interest in the role of nucleotide-binding oligomerisation domain-like receptor family, pyrin domain containing protein-3 inflammasomes in chronic inflammatory lung diseases such as COPD and their potential for therapeutic targeting. Phytochemicals including polyphenols and flavonoids have phyto-medicinal benefits in CS-COPD. Here, we review published articles from the last decade regarding the known associations between inflammasome-mediated responses and ameliorations in pre-clinical manifestations of CS-COPD via polyphenol and flavonoid treatment, with a focus on the underlying mechanistic insights. This article will potentially assist the development of drugs for the prevention and therapy of COPD, particularly in cigarette smokers.

This review compiles current investigations into the role of polyphenols/flavonoids in the alleviation of cigarette smoke-induced inflammasome; notably it provides a promising hit for rectifying the treatment of COPD.https://bit.ly/36OcUO9

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

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

Beneficial ex vivo immunomodulatory and clinical effects of clarithromycin in COVID-19

Introduction

Macrolide antibiotics have immunomodulatory properties which may be beneficial in viral infections. However, the precise effects of macrolides on T cell responses to COVID, differences between different macrolides, and synergistic effects with other antibiotics have not been explored.

Methods

We investigated the effect of antibiotics (amoxicillin, azithromycin, clarithromycin, and combined amoxicillin with clarithromycin) on lymphocyte intracellular cytokine levels and monocyte phagocytosis in healthy volunteer PBMCs stimulated ex vivo with SARS-CoV-2 S1+2 spike protein. A retrospective cohort study was performed on intensive care COVID-19 patients.

Results

Co-incubation of clarithromycin with spike protein-stimulated healthy volunteer PBMCs ex vivo resulted in an increase in CD8⁺ (p = 0.004) and CD4⁺ (p = 0.007) IL-2, with a decrease in CD8⁺ (p = 0.032) and CD4⁺ (p = 0.007) IL-10. The addition of amoxicillin to clarithromycin resulted in an increase in CD8⁺ IL-6 (p = 0.010), decrease in CD8⁺ (p = 0.014) and CD4⁺ (p = 0.022) TNF-alpha, and decrease in CD8⁺ IFN-alpha (p = 0.038). Amoxicillin alone had no effect on CD4⁺ or CD8⁺ cytokines. Co-incubation of azithromycin resulted in increased CD8⁺ (p = 0.007) and CD4⁺ (p = 0.011) IL-2. There were no effects on monocyte phagocytosis. 102 COVID-19 ICU patients received antibiotics on hospital admission; 62 (61%) received clarithromycin. Clarithromycin use was associated with reduction in mortality on univariate analysis (p = 0.023), but not following adjustment for confounders (HR = 0.540; p = 0.076).

Conclusions

Clarithromycin has immunomodulatory properties over and above azithromycin. Amoxicillin in addition to clarithromycin is associated with synergistic ex vivo immunomodulatory properties. The potential benefit of clarithromycin in critically ill patients with COVID-19 and other viral pneumonitis merits further exploration.

Antibiotics as immunomodulators: a potential pharmacologic approach for ARDS treatment

First described in the mid-1960s, acute respiratory distress syndrome (ARDS) is a life-threatening form of respiratory failure with an overall mortality rate of approximately 40%. Despite significant advances in the understanding and treatment of ARDS, no substantive pharmacologic therapy has proven to be beneficial, and current management continues to be primarily supportive. Beyond their antibacterial activity, several antibiotics such as macrolides and tetracyclines exert pleiotropic immunomodulatory effects that might be able to rectify the dysregulated inflammatory response present in patients with ARDS. This review aims to provide an overview of preclinical and clinical studies that describe the immunomodulatory effects of antibiotics in ARDS. Moreover, the underlying mechanisms of their immunomodulatory properties will be discussed. Further studies are necessary to investigate their full therapeutic potential and to identify ARDS phenotypes which are most likely to benefit from their immunomodulatory effects.

Role of non-canonical pyroptosis in sepsis and other inflammatory diseases

As a form of new programmed cell death, pyroptosis is divided into a canonical pyroptosis pathway and a non-canonical pyroptosis pathway. In recent years, it is reported that non-canonical pyroptosis is closely related to inflammatory reactions, which directly affects the occurrence, development, and outcome of sepsis, inflammatory bowel disease, respiratory disease, nerve system inflammatory disease, and other inflammatory diseases. When the cells were infected with Gram-negative bacteria or lipopolysaccharide (LPS), it can induce the activation of cysteinyl aspartate specific proteinase(caspase)-4/5/11 and directly bind to the cells to cleave gasdermin D (GSDM-D) into the active amino-terminus of GSDM-D. The amino-terminus of GSDM-D with membrane punching activity migrates to the cell membrane, triggering the rupture of the cell membrane, and the cell contents discharge, leading to the occurrence of non-canonical pyroptosis. After activation of caspase-11, it also promotes the canonical pyroptosis, activates and releases interleukin-1β and interleukin-18, which aggravated inflammation. Caspase-4/5/11, GSDM-D, Toll-like receptor 4 and high mobility group protein B1 are the key molecules of the non-canonical pyroptosis. Exploring the mechanisms of non-canonical pyroptosis and the related research progresses in inflammatory diseases intensively is of great significance for clinical prevention and treatment of the relevant diseases.

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.

Antimicrobial therapy during cancer treatment: Beyond antibacterial effects

Cancer treatment options have evolved to include immunotherapy and targeted therapy, in addition to traditional chemoradiation. Chemoradiation places the patient at a higher risk of infection through a myelosuppressive effect. High clinical suspicion and early use of antimicrobials play a major role in decreasing any associated morbidity and mortality. This has led to a widespread use of antimicrobials in cancer patients. Antimicrobial use, however, does not come without its perils. Dysbiosis caused by antimicrobial use affects responses to chemotherapeutic agents and is prognostic in the development and severity of certain cancer treatment-related complications such as graft-versus-host disease and Clostridioides difficile infections. Studies have also demonstrated that an intact gut microbiota is essential in the anticancer immune response. Antimicrobial use can therefore modulate responses and outcomes with immunotherapy targeting immune checkpoints. In this review, we highlight the perils associated with antimicrobial use during cancer therapy and the importance of a more judicious approach. We discuss the nature of the pathologic changes in the gut microbiota resulting from antimicrobial use. We explore the effect these changes have on responses and outcomes to different cancer treatment modalities including chemotherapy and immunotherapy, as well as potential adverse clinical consequences in the setting of stem cell transplant.

DeepR2cov: deep representation learning on heterogeneous drug networks to discover anti-inflammatory agents for COVID-19

Recent studies have demonstrated that the excessive inflammatory response is an important factor of death in coronavirus disease 2019 (COVID-19) patients. In this study, we propose a deep representation on heterogeneous drug networks, termed DeepR2cov, to discover potential agents for treating the excessive inflammatory response in COVID-19 patients. This work explores the multi-hub characteristic of a heterogeneous drug network integrating eight unique networks. Inspired by the multi-hub characteristic, we design 3 billion special meta paths to train a deep representation model for learning low-dimensional vectors that integrate long-range structure dependency and complex semantic relation among network nodes. Based on the representation vectors and transcriptomics data, we predict 22 drugs that bind to tumor necrosis factor-α or interleukin-6, whose therapeutic associations with the inflammation storm in COVID-19 patients, and molecular binding model are further validated via data from PubMed publications, ongoing clinical trials and a docking program. In addition, the results on five biomedical applications suggest that DeepR2cov significantly outperforms five existing representation approaches. In summary, DeepR2cov is a powerful network representation approach and holds the potential to accelerate treatment of the inflammatory responses in COVID-19 patients. The source code and data can be downloaded from https://github.com/pengsl-lab/DeepR2cov.git.

Intracellular and Extracellular Lipopolysaccharide Signaling in Sepsis: Avenues for Novel Therapeutic Strategies

Sepsis is defined as organ dysfunction due to a dysregulated systemic host response to infection. During gram-negative bacterial infection and other acute illness such as absorption from the gut infection, lipopolysaccharide (LPS) is a major mediator in sepsis. LPS is able to trigger inflammation through both intracellular and extracellular pathways. Classical interactions between LPS and host cells first involve LPS binding to LPS binding protein (LBP), a carrier. The LPS-LBP complex then binds to a receptor complex including the CD14, MD2, and toll-like receptor 4 (TLR4) proteins, initiating a signal cascade which triggers the secretion of pro-inflammatory cytokines. However, it has been established that LPS is also internalized by macrophages and endothelial cells through TLR4-independent pathways. Once internalized, LPS is able to bind to the cytosolic receptors caspases-4/5 in humans and the homologous caspase-11 in mice. Bound caspases-4/5 oligomerize and trigger the assembly of the nucleotide-binding domain, leucine-rich-containing family, pyrin domain-containing-3 inflammasome followed by the activation of inflammatory caspase-1 resulting in subsequent release of interleukin-1β. Caspases-4/5 also activate the perforin gasdermin D and purinergic receptor P2X7, inducing cell lysis and pyroptosis. Pyroptosis is a notable source of inflammation and damage to the lung endothelial barrier during sepsis. Thus, inhibition of caspases-4/5/1 or downstream effectors to block intracellular LPS signaling may be a promising therapeutic approach in adjunction with neutralizing extracellular LPS for treatment of sepsis.

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

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

Chloroquine/hydroxychloroquine: an inflammasome inhibitor in severe COVID-19?

Chloroquine and hydroxychloroquine belong to the aminoquinoline drugs. Studies revealed that chloroquine and hydroxychloroquine shows antagonism activity against COVID-19 under laboratory conditions. ARDS and ALI are conditions that occur in patients with COVID-19 as the main pathological complications of cytokine storm. Inflammasomes play a key role in the pathogenesis of many diseases associated with destructive inflammation. NLRP3 inflammasome has been shown to play a key role in the pathogenesis of viral diseases. The possible role of NLRP3 inflammasome inhibitors in the treatment of COVID-19 has been considered. We surveyed the potential inhibitory effect of chloroquine and hydroxychloroquine on inflammasome. Studies indicate that one of the possible anti-inflammatory mechanisms of chloroquine and hydroxychloroquine is inhibition of the activity of NLRP3 inflammasome.

Preventing the development of severe COVID-19 by modifying immunothrombosis

BACKGROUND

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

MAIN BODY

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

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

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

Targeting neutrophils in asthma: A therapeutic opportunity?

Suppression of airway inflammation with inhaled corticosteroids has been the key therapeutic approach for asthma for many years. Identification of inflammatory phenotypes in asthma has moreover led to important breakthroughs, e.g. with specific targeting of the IL-5 pathway as add-on treatment in difficult-to-treat eosinophilic asthma. However, the impact of interfering with the neutrophilic component in asthma is less documented and understood. This review provides an overview of established and recent insights with regard to the role of neutrophils in asthma, focusing on research in humans. We will describe the main drivers of neutrophilic responses in asthma, the heterogeneity in neutrophils and how they could contribute to asthma pathogenesis. Moreover we will describe findings from clinical trials, in which neutrophilic inflammation was targeted. It is clear that neutrophils are important actors in asthma development and play a role in exacerbations. However, more research is required to fully understand how modulation of neutrophil activity could lead to a significant benefit in asthma patients with airway neutrophilia.

The CIPAZ study protocol: an open label randomised controlled trial of azithromycin versus ciprofloxacin for the treatment of children hospitalised with dysentery in Ho Chi Minh City, Vietnam

Background: Diarrhoeal disease remains a common cause of illness and death in children <5 years of age. Faecal-oral infection by Shigella spp. causing bacillary dysentery is a leading cause of moderate-to-severe diarrhoea, particularly in low and middle-income countries. In Southeast Asia, S. sonnei predominates and infections are frequently resistant to first-line treatment with the fluoroquinolone, ciprofloxacin. While resistance to all antimicrobials is increasing, there may be theoretical and clinical benefits to prioritizing treatment of bacillary dysentery with the azalide, azithromycin. In this study we aim to measure the efficacy of treatment with azithromycin compared with ciprofloxacin, the current standard of care, for the treatment of children with bacillary dysentery. Methods and analysis: We will perform a multicentre, open-label, randomized controlled trial of two therapeutic options for the antimicrobial treatment of children hospitalised with dysentery. Children (6–60 months of age) presenting with symptoms and signs of dysentery at Children’s Hospital 2 in Ho Chi Minh City will be randomised (1:1) to treatment with either oral ciprofloxacin (15mg/kg/twice daily for 3 days, standard-of-care) or oral azithromycin (10mg/kg/daily for 3 days). The primary endpoint will be the proportion of treatment failure (defined by clinical and microbiological parameters) by day 28 (+3 days) and will be compared between study arms by logistic regression modelling using treatment allocation as the main variable. Ethics and dissemination: The study protocol (version 1.2 dated 27th December 2018) has been approved by the Oxford Tropical Research Ethics Committee (47–18) and the ethical review boards of Children's Hospital 2 (1341/NĐ2-CĐT). The study has also been approved by the Vietnamese Ministry of Health (5044/QĐ-BYT). Trial registration: Clinicaltrials.gov: NCT03854929 (February 26th 2019).

The hidden role of NLRP3 inflammasome in obesity-related COVID-19 exacerbations: Lessons for drug repurposing

COVID-19, the illness caused by SARS-CoV-2, has a wide-ranging clinical spectrum that, in the worst-case scenario, involves a rapid progression to severe acute respiratory syndrome and death. Epidemiological data show that obesity and diabetes are among the main risk factors associated with high morbidity and mortality. The increased susceptibility to SARS-CoV-2 infection documented in obesity-related metabolic derangements argues for initial defects in defence mechanisms, most likely due to an elevated systemic metabolic inflammation ("metaflammation"). The NLRP3 inflammasome is a master regulator of metaflammation and has a pivotal role in the pathophysiology of either obesity or diabetes. Here, we discuss the most recent findings suggesting contribution of NLRP3 inflammasome to the increase in complications in COVID-19 patients with diabesity. We also review current pharmacological strategies for COVID-19, focusing on treatments whose efficacy could be due, at least in part, to interference with the activation of the NLRP3 inflammasome. LINKED ARTICLES: This article is part of a themed issue on The Pharmacology of COVID-19. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v177.21/issuetoc.

Immunomodulation by macrolides: therapeutic potential for critical care

Critical illness is associated with immune dysregulation, characterised by concurrent hyperinflammation and immune suppression. Hyperinflammation can result in collateral tissue damage and organ failure, whereas immune suppression has been implicated in susceptibility to secondary infections and reactivation of latent viruses. Macrolides are a class of bacteriostatic antibiotics that are used in the intensive care unit to control infections or to alleviate gastrointestinal dysmotility. Yet macrolides also have potent and wide-ranging immunomodulatory properties, which might have the potential to correct immune dysregulation in patients who are critically ill without affecting crucial antimicrobial defences. In this Review, we provide an overview of preclinical and clinical studies that point to the beneficial effects of macrolides in acute diseases relevant to critical care, and we discuss the possible underlying mechanisms of their immunomodulatory effects. Further studies are needed to explore the therapeutic potential of macrolides in critical illness, to identify subgroups of patients who might benefit from treatment, and to develop novel non-antibiotic macrolide derivatives with improved immunomodulatory properties.

Mycobacterium abscessus Clearance by Neutrophils Is Independent of Autophagy

Mycobacterium abscessus, a rapidly growing nontuberculous mycobacterium, is increasingly prevalent in chronic lung disease, including cystic fibrosis, and infections are characterized by neutrophil-dominated environments. However, mechanisms of immune control are poorly understood. Azithromycin, a macrolide antibiotic with immunomodulatory effects, is used to treat M. abscessus infections. Recently, inhibition of macrophage bactericidal autophagy was described for azithromycin, which could be detrimental to the host. Therefore, we explored the role of autophagy in mycobactericidal neutrophils. Azithromycin did not affect M. abscessus-induced neutrophil reactive oxygen species formation, phagocytosis, or cytokine secretion, and neutrophils treated with azithromycin killed M. abscessus equally as well as untreated neutrophils from either healthy or cystic fibrosis subjects. One clinical isolate was killed more effectively in azithromycin-treated neutrophils, suggesting that pathogen-specific factors may interact with an azithromycin-sensitive pathway. Chloroquine and rapamycin, an inhibitor and an activator of autophagy, respectively, also failed to affect mycobactericidal activity, suggesting that autophagy was not involved. However, wortmannin, an inhibitor of intracellular trafficking, inhibited mycobactericidal activity, but as a result of inhibiting phagocytosis. The effects of these autophagy-modifying agents and azithromycin in neutrophils from healthy subjects were similar between the smooth and rough morphotypes of M. abscessus However, in cystic fibrosis neutrophils, wortmannin inhibited killing of a rough clinical isolate and not a smooth isolate, suggesting that unique host-pathogen interactions exist in cystic fibrosis. These studies increase our understanding of M. abscessus virulence and of neutrophil mycobactericidal mechanisms. Insight into the immune control of M. abscessus may provide novel targets of therapy.

Idiopathic chronic productive cough and response to open-label macrolide therapy: An observational study

BACKGROUND AND OBJECTIVE

Adult patients with chronic productive cough of unknown cause are commonly seen in respiratory clinics. We have previously described a subgroup of these patients who have a short-lived response to standard antibiotic treatment but a prolonged response to 3 months of low-dose azithromycin therapy.

METHODS

This observational study describes the physiological, radiological and pathological features of this patient cohort along with their response to a 12-week open-label trial of 250 mg azithromycin thrice weekly.

RESULTS

A total of 30 subjects with a mean age of 57 were recruited. The majority demonstrated airway dilatation on high-resolution computed tomography (HRCT) scan without evidence of established bronchiectasis (n = 21) and non-specific chronic inflammatory changes on bronchial biopsy (n = 15/17). Twenty-nine subjects completed 3 months of azithromycin with a significant improvement in median Leicester Cough Questionnaire (LCQ) score (-6.3 points, P < 0.00001), reduction in median 24-h sputum volume (-5.8 mL, P = 0.0003) and improvement in sputum colour (P = 0.003). Patients responsive to azithromycin (n = 22) demonstrated neutrophilic or paucigranulocytic airway inflammation, whereas five subjects with eosinophilic airways inflammation did not respond symptomatically to azithromycin.

CONCLUSION

We describe a cohort of patients with chronic productive cough not adequately described by existing disease labels whose symptoms responded well to low-dose azithromycin. Many of the features are similar to the paediatric condition protracted bacterial bronchitis.

Rhinovirus induces an anabolic reprogramming in host cell metabolism essential for viral replication

Rhinoviruses (RVs) are responsible for the majority of upper airway infections; despite their high prevalence and the resulting economic burden, effective treatment is lacking. We report here that RV induces metabolic alterations in host cells, which offer an efficient target for antiviral intervention. We show that RV-infected cells rapidly up-regulate glucose uptake in a PI3K-dependent manner. In parallel, infected cells enhance the expression of the PI3K-regulated glucose transporter GLUT1. In-depth metabolomic analysis of RV-infected cells revealed a critical role of glucose mobilization from extracellular and intracellular pools via glycogenolysis for viral replication. Infection resulted in a highly anabolic state, including enhanced nucleotide synthesis and lipogenesis. Consistently, we observed that glucose deprivation from medium and via glycolysis inhibition by 2-deoxyglucose (2-DG) potently impairs viral replication. Metabolomic analysis showed that 2-DG specifically reverts the RV-induced anabolic reprogramming. In addition, treatment with 2-DG inhibited RV infection and inflammation in a murine model. Thus, we demonstrate that the specific metabolic fingerprint of RV infection can be used to identify new targets for therapeutic intervention.

Immunomodulation to Prevent or Treat Neonatal Sepsis: Past, Present, and Future

Despite continued advances in neonatal medicine, sepsis remains a leading cause of death worldwide in neonatal intensive care units. The clinical presentation of sepsis in neonates varies markedly from that in older children and adults, and distinct acute inflammatory responses results in age-specific inflammatory and protective immune response to infection. This review first provides an overview of the neonatal immune system, then covers current mainstream, and experimental preventive and adjuvant therapies in neonatal sepsis. We also discuss how the distinct physiology of the perinatal period shapes early life immune responses and review strategies to reduce neonatal sepsis-related morbidity and mortality. A summary of studies that characterize immune ontogeny and neonatal sepsis is presented, followed by discussion of clinical trials assessing interventions such as breast milk, lactoferrin, probiotics, and pentoxifylline. Finally, we critically appraise future treatment options such as stem cell therapy, other antimicrobial protein and peptides, and targeting of pattern recognition receptors in an effort to prevent and/or treat sepsis in this highly vulnerable neonatal population.

Pentoxifylline, dexamethasone and azithromycin demonstrate distinct age-dependent and synergistic inhibition of TLR- and inflammasome-mediated cytokine production in human newborn and adult blood in vitro

Introduction

Neonatal inflammation, mediated in part through Toll-like receptor (TLR) and inflammasome signaling, contributes to adverse outcomes including organ injury. Pentoxifylline (PTX), a phosphodiesterase inhibitor which potently suppresses cytokine production in newborn cord blood, is a candidate neonatal anti-inflammatory agent. We hypothesized that combinations of PTX with other anti-inflammatory agents, the steroid dexamethasone (DEX) or the macrolide azithromycin (AZI), may exert broader, more profound and/or synergistic anti-inflammatory activity towards neonatal TLR- and inflammasome-mediated cytokine production.

Methods

Whole newborn and adult blood was treated with PTX (50–200 μM), DEX (10⁻¹⁰–10⁻⁷ M), or AZI (2.5–20 μM), alone or combined, and cultured with lipopolysaccharide (LPS) (TLR4 agonist), R848 (TLR7/8 agonist) or LPS/adenosine triphosphate (ATP) (inflammasome induction). Supernatant and intracellular cytokines, signaling molecules and mRNA were measured by multiplex assay, flow cytometry and real-time PCR. Drug interactions were assessed based on Loewe's additivity.

Results

PTX, DEX and AZI inhibited TLR- and/or inflammasome-mediated cytokine production in newborn and adult blood, whether added before, simultaneously or after TLR stimulation. PTX preferentially inhibited pro-inflammatory cytokines especially TNF. DEX inhibited IL-10 in newborn, and TNF, IL-1β, IL-6 and interferon-α in newborn and adult blood. AZI inhibited R848-induced TNF, IL-1β, IL-6 and IL-10, and LPS-induced IL-1β and IL-10. (PTX+DEX) synergistically decreased LPS- and LPS/ATP-induced TNF, IL-1β, and IL-6, and R848-induced IL-1β and interferon-α, while (PTX+AZI) synergistically decreased induction of TNF, IL-1β, and IL-6. Synergistic inhibition of TNF production by (PTX+DEX) was especially pronounced in newborn vs. adult blood and was accompanied by reduction of TNF mRNA and enhancement of IL10 mRNA.

Conclusions

Age, agent, and specific drug-drug combinations exert distinct anti-inflammatory effects towards TLR- and/or inflammasome-mediated cytokine production in human newborn blood in vitro. Synergistic combinations of PTX, DEX and AZI may offer benefit for prevention and/or treatment of neonatal inflammatory conditions while potentially limiting drug exposure and toxicity.

Autoinflammatory disease in the lung

Ascertaining the dominant cell type driving an immunological disease is essential to understanding the causal pathology and, therefore, selecting or developing an effective treatment. Classifying immunological diseases in this way has led to successful treatment regimens for many monogenic diseases; however, when the dominant cell type is unclear and there is no obvious causal genetic mutation, then identifying the correct disease classification and appropriate therapy can be challenging. In this review we focus on pulmonary immunological diseases where an innate immune signature has been identified as a predominant aspect of the immunopathology. We describe the molecular pathology of 'autoinflammatory diseases of the lung' and propose that small molecule and biological therapies, including recombinant interleukin-1 receptor antagonist, that target key innate immune pathways, are likely be beneficial in the control of pulmonary and systemic inflammation in these conditions. In addition, the successful use of macrolide antibiotics to treat lung infections in these conditions further confirms that the innate immune system is the key conductor of inflammation in these pulmonary diseases, as there is a strong body of evidence that macrolides are able to modulate the NLRP3 inflammasome and interleukin-1β and interleukin-18 secretion, both of which are central players in the innate immune response. Throughout this review we highlight the published evidence of autoinflammatory disease in chronic obstructive pulmonary disease, bronchiectasis, cystic fibrosis and rheumatoid lung disease and suggest that the fundamental pathology of these diseases places them towards the autoinflammatory pole of the immunological disease continuum.

The Immunomodulatory Effects of Macrolides-A Systematic Review of the Underlying Mechanisms

Background

The mechanisms underlying the non-antimicrobial immunomodulatory properties of macrolides are not well understood.

Objectives

To systematically review the evidence for the immunomodulatory properties of macrolides in humans and to describe the underlying mechanism and extent of their influence on the innate and adaptive immune system.

Methods

A systematic literature search was done in MEDLINE using the OVID interface from 1946 to December 2016 according to the preferred reporting items for systematic reviews and meta-analysis (PRISMA). Original articles investigating the influence of four macrolides (azithromycin, clarithromycin, erythromycin, and roxithromycin) on immunological markers in humans were included.

Results

We identified 22 randomized, controlled trials, 16 prospective cohort studies, and 8 case–control studies investigating 47 different immunological markers (186 measurements) in 1,834 participants. The most frequently reported outcomes were a decrease in the number of neutrophils, and the concentrations of neutrophil elastase, interleukin (IL)-8, IL-6, IL-1beta, tumor necrosis factor (TNF)-alpha, eosinophilic cationic protein, and matrix metalloproteinase 9. Inhibition of neutrophil function was reported more frequently than eosinophil function. A decrease in T helper (Th) 2 cells cytokines (IL-4, IL-5, IL-6) was reported more frequently than a decrease in Th1 cytokines (IL-2, INF-gamma).

Conclusion

Macrolides influence a broad range of immunological mechanisms resulting in immunomodulatory effects. To optimize the treatment of chronic inflammatory diseases by macrolides, further studies are necessary, particularly comparing different macrolides and dose effect relationships.

A single early-in-life macrolide course has lasting effects on murine microbial network topology and immunity

Broad-spectrum antibiotics are frequently prescribed to children. Early childhood represents a dynamic period for the intestinal microbial ecosystem, which is readily shaped by environmental cues; antibiotic-induced disruption of this sensitive community may have long-lasting host consequences. Here we demonstrate that a single pulsed macrolide antibiotic treatment (PAT) course early in life is sufficient to lead to durable alterations to the murine intestinal microbiota, ileal gene expression, specific intestinal T-cell populations, and secretory IgA expression. A PAT-perturbed microbial community is necessary for host effects and sufficient to transfer delayed secretory IgA expression. Additionally, early-life antibiotic exposure has lasting and transferable effects on microbial community network topology. Our results indicate that a single early-life macrolide course can alter the microbiota and modulate host immune phenotypes that persist long after exposure has ceased.High or multiple doses of macrolide antibiotics, when given early in life, can perturb the metabolic and immunological development of lab mice. Here, Ruiz et al. show that even a single macrolide course, given early in life, leads to long-lasting changes in the gut microbiota and immune system of mice.

Macrolides protect against Pseudomonas aeruginosa infection via inhibition of inflammasomes

Macrolides antibiotics have been effectively used in many chronic diseases, especially with Pseudomonas aeruginosa (P. aeruginosa) infection. The mechanisms underlying the therapeutic effects of macrolides in these diseases remain poorly understood. We established a mouse model of chronic lung infection using P. aeruginosa agar-beads, with azithromycin treatment or placebo. Lung injury, bacterial clearance, and inflammasome-related proteins were measured. In vitro, the inflammasomes activation induced by flagellin or ATP were assessed in LPS-primed macrophages with or without macrolides treatment. Plasma IL-18 levels were determined from patients who were diagnosed with bronchiectasis isolated with or without P. aeruginosa and treated with azithromycin for 3-5 days. Azithromycin treatment enhanced bacterial clearance and attenuated lung injury in mice chronically infected with P. aeruginosa, which resulted from the inhibition of caspase-1-dependent IL-1β and IL-18 secretion. In vitro, azithromycin and erythromycin inhibited NLRC4 and NLRP3 inflammasomes activation. Plasma IL-18 levels were higher in bronchiectasis patients with P. aeruginosa isolation compared with healthy controls. Azithromycin administration markedly decreased IL-18 secretion in bronchiectasis patients. The results of this study reveal that azithromycin and erythromycin exert a novel anti-inflammatory effect by attenuating inflammasomes activation, which suggests potential treatment options for inflammasome-related diseases.

Azithromycin decreases NALP3 mRNA stability in monocytes to limit inflammasome-dependent inflammation

BACKGROUND

Azithromycin, an antibiotic used for multiple infectious disorders, exhibits anti-inflammatory effects, but the molecular basis for this activity is not well characterized. Azithromycin inhibits IL-1β-mediated inflammation that is dependent, in part, on inflammasome activity. Here, we investigated the effects of azithromycin on the NACHT, LRR, and PYD domains-containing protein 3 (NALP3) protein, which is the sensing component of the NALP3 inflammasome, in human monocytes.

METHODS

THP-1 cells were treated with azithromycin alone, LPS alone, or both. NALP3 and IL-1β protein levels were determined by immunoblotting. NLRP3 gene (encoding NALP3) transcript levels were determined by quantitative qPCR. In order to measure NLRP3 transcript decay, actinomycin D was used to impair gene transcription. THP-1 Lucia cells which contain an NF-κB responsive luciferase element were used to assess NF-κB activity in response to azithromycin, LPS, and azithromycin/LPS by measuring luminescence. To confirm azithromycin's effects on NLRP3 mRNA and promoter activity conclusively, HEK cells were lipofected with luciferase reporter constructs harboring either the 5' untranslated region (UTR) of the NLRP3 gene which included the promoter, the 3' UTR of the gene, or an empty plasmid prior to treatment with azithromycin and/or LPS, and luminescence was measured.

RESULTS

Azithromycin decreased IL-1β levels and reduced NALP3 protein levels in LPS-stimulated THP-1 monocytes through a mechanism involving decreased mRNA stability of the NALP3 - coding NLRP3 gene transcript as well as by decreasing NF-κB activity. Azithromycin accelerated NLRP3 transcript decay confirmed by mRNA stability and 3'UTR luciferase reporter assays, and yet the antibiotic had no effect on NLRP3 promoter activity in cells containing a 5' UTR reporter.

CONCLUSIONS

These studies provide a unique mechanism whereby azithromycin exerts immunomodulatory actions in monocytes by destabilizing mRNA levels for a key inflammasome component, NALP3, leading to decreased IL-1β-mediated inflammation.

A human monocytic NF-κB fluorescent reporter cell line for detection of microbial contaminants in biological samples

Sensing of pathogens by innate immune cells is essential for the initiation of appropriate immune responses. Toll-like receptors (TLRs), which are highly sensitive for various structurally and evolutionary conserved molecules derived from microbes have a prominent role in this process. TLR engagement results in the activation of the transcription factor NF-κB, which induces the expression of cytokines and other inflammatory mediators. The exquisite sensitivity of TLR signalling can be exploited for the detection of bacteria and microbial contaminants in tissue cultures and in protein preparations. Here we describe a cellular reporter system for the detection of TLR ligands in biological samples. The well-characterized human monocytic THP-1 cell line was chosen as host for an NF-ᴋB-inducible enhanced green fluorescent protein reporter gene. We studied the sensitivity of the resultant reporter cells for a variety of microbial components and observed a strong reactivity towards TLR1/2 and TLR2/6 ligands. Mycoplasma lipoproteins are potent TLR2/6 agonists and we demonstrate that our reporter cells can be used as reliable and robust detection system for mycoplasma contaminations in cell cultures. In addition, a TLR4-sensitive subline of our reporters was engineered, and probed with recombinant proteins expressed in different host systems. Bacterially expressed but not mammalian expressed proteins induced strong reporter activity. We also tested proteins expressed in an E. coli strain engineered to lack TLR4 agonists. Such preparations also induced reporter activation in THP-1 cells highlighting the importance of testing recombinant protein preparations for microbial contaminations beyond endotoxins. Our results demonstrate the usefulness of monocytic reporter cells for high-throughput screening for microbial contaminations in diverse biological samples, including tissue culture supernatants and recombinant protein preparations. Fluorescent reporter assays can be measured on standard flow cytometers and in contrast to established detection methods, like luciferase-based systems or Limulus Amebocyte Lysate tests, they do not require costly reagents.

Differential inhibition of activity, activation and gene expression of MMP-9 in THP-1 cells by azithromycin and minocycline versus bortezomib: A comparative study

Gelatinase B or matrix metalloproteinase-9 (MMP-9) (EC 3.4.24.35) is increased in inflammatory processes and cancer, and is associated with disease progression. In part, this is due to MMP-9-mediated degradation of extracellular matrix, facilitating influx of leukocytes into inflamed tissues and invasion or metastasis of cancer cells. MMP-9 is produced as proMMP-9 and its propeptide is subsequently removed by other proteases to generate proteolytically active MMP-9. The significance of MMP-9 in pathologies triggered the development of specific inhibitors of this protease. However, clinical trials with synthetic inhibitors of MMPs in the fight against cancer were disappointing. Reports on active compounds which inhibit MMP-9 should be carefully examined in this regard. In a considerable set of recent publications, two antibiotics (minocycline and azythromycin) and the proteasome inhibitor bortezomib, used in cancers, were reported to inhibit MMP-9 at different stages of its expression, activation or activity. The current study was undertaken to compare and to verify the impact of these compounds on MMP-9. With exception of minocycline at high concentrations (>100 μM), the compounds did not affect processing of proMMP-9 into MMP-9, nor did they affect direct MMP-9 gelatinolytic activity. In contrast, azithromycin specifically reduced MMP-9 mRNA and protein levels without affecting NF-κB in endotoxin-challenged monocytic THP-1 cells. Bortezomib, although being highly toxic, had no MMP-9-specific effects but significantly upregulated cyclooxygenase-2 (COX-2) activity and PGE₂ levels. Overall, our study clarified that azithromycin decreased the levels of MMP-9 by reduction of gene and protein expression while minocycline inhibits proteolytic activity at high concentrations.

The ligand-bound thyroid hormone receptor in macrophages ameliorates kidney injury via inhibition of nuclear factor-κB activities

In chronic kidney disease (CKD) patients, inflammation plays a pivotal role in the progression of renal fibrosis. Hypothyroidism is associated with an increased occurrence of atherosclerosis and inflammation, suggesting protective roles of thyroid hormones and their receptors against inflammatory processes. The contribution of thyroid hormone receptors to macrophage differentiation has not been well documented. Here, we focused on the endogenous thyroid hormone receptor α (TRα) in macrophages and examined the role of ligand-bound TRα in macrophage polarization-mediated anti-inflammatory effects. TRα-deficient irradiated chimeric mice showed exacerbated tubulointerstitial injury in a unilateral ureteral obstruction model. Compared with wild-type macrophages, macrophages isolated from the obstructed kidneys of mice lacking TRα displayed increased expression of proinflammatory cytokines that was accompanied by enhanced nuclear translocation of p65. Comparison of TRα-deficient bone marrow-derived macrophages with wild-type macrophages confirmed the propensity of the former cells to produce excessive IL-1β levels. Co-culture of these macrophages with renal epithelial cells induced more severe damage to the epithelial cells via the IL-1 receptor. Our findings indicate that ligand-bound TRα on macrophages plays a protective role in kidney inflammation through the inhibition of NF-κB pathways, possibly by affecting the pro- and anti-inflammatory balance that controls the development of CKD.

Nonantibiotic macrolides restore airway macrophage phagocytic function with potential anti-inflammatory effects in chronic lung diseases

We reported defective efferocytosis associated with cigarette smoking and/or airway inflammation in chronic lung diseases, including chronic obstructive pulmonary disease, severe asthma, and childhood bronchiectasis. We also showed defects in phagocytosis of nontypeable Haemophilus influenzae (NTHi), a common colonizer of the lower airway in these diseases. These defects could be substantially overcome with low-dose azithromycin; however, chronic use may induce bacterial resistance. The aim of the present study was therefore to investigate two novel macrolides-2'-desoxy-9-(S)-erythromycylamine (GS-459755) and azithromycin-based 2'-desoxy molecule (GS-560660)-with significantly diminished antibiotic activity against Staphylococcus aureus, Streptococcus pneumonia, Moraxella catarrhalis, and H. influenzae We tested their effects on efferocytosis, phagocytosis of NTHi, cell viability, receptors involved in recognition of apoptotic cells and/or NTHi (flow cytometry), secreted and cleaved intracellular IL-1β (cytometric bead array, immunofluorescence/confocal microscopy), and nucleotide-binding oligomerization domain-like receptor family pyrin domain-containing 3 (NLRP3) using primary alveolar macrophages and THP-1 macrophages ± 10% cigarette smoke extract. Dose-response experiments showed optimal prophagocytic effects of GS-459755 and GS-560660 at concentrations of 0.5-1 µg/ml compared with our findings with azithromycin. Both macrolides significantly improved phagocytosis of apoptotic cells and NTHi (e.g., increases in efferocytosis and phagocytosis of NTHi: GS-459755, 23 and 22.5%, P = 0.043; GS-560660, 23.5 and 22%, P = 0.043, respectively). Macrophage viability remained >85% following 24 h exposure to either macrolide at concentrations up to 20 µg/ml. Secreted and intracellular-cleaved IL-1β was decreased with both macrolides with no significant changes in recognition molecules c-mer proto-oncogene tyrosine kinase; scavenger receptor class A, member 1; Toll-like receptor 2/4; or CD36. Particulate cytoplasmic immunofluorescence of NLRP3 inflammasome was also reduced significantly. We conclude that GS-459755 and GS-560660 may be useful for reducing airway inflammation in chronic lung diseases without inducing bacterial resistance.

Progress does not just come in giant leaps: adapting techniques for the study of inflammation to novel applications

INTRODUCTION

Discussion of the relevance of suitable experimental models for the effective translation of drug effects to clinical inflammatory diseases has a long history. Much emphasis is placed these days on genetically transformed mice, which may have developmental drawbacks. But are established models redundant?

FINDINGS

Drawn from personal experience, examples are provided of the success of tinkering with technology in the context of inflammation. These include the use of specific dietary deficiency conditions, the development of new applications for established drugs and the introduction of a variety of readouts to assess outcome in studies on established disease models. Such approaches have been used to demonstrate inflammation-modulating effects of prostaglandin E, in the development of ebselen, for the introduction of immunomodulatory macrolide drugs and in new approaches to the therapy of multiple sclerosis.

CONCLUSION

Fine tuning of experimental approaches and evaluation technologies can often still provide innovative, clinically relevant insights into the potential beneficial effects of drugs and pharmacological agents.