Macrolides in chronic inflammatory skin disorders

Understanding the evolution of macrolides resistance: A mini review

BACKGROUND

Macrolides inhibit the growth of bacterial cells by preventing the elongation of polypeptides during protein biosynthesis and include natural, synthetic, and semi-synthetic products. Elongation prevention occurs by blocking the passage of the polypeptide chain as the macrolides bind at the nascent peptide exit tunnel.

OBJECTIVE

Recent data of ribosome profiling via ribo-seq further proves that, other than blocking the polypeptide chain, macrolides are also able to affect the synthesis of individual proteins. Thus, this shows that the mode of action of macrolides is more complex than we initially thought. Since the discovery of macrolides in the 1950s, they have been widely used in veterinary practice, agriculture, and medicine. Due to misuse and overuse of antibiotics, bacteria have acquired resistance against them. Hence, it is of utmost importance for us to fully understand the mode of action of macrolides as well as the mechanisms of resistance against macrolides in order to mitigate antibiotic-resistance issues.

RESULTS

Chemical modifications can be performed to improve macrolide potency if we have a better understanding of their mode of action. Furthermore, a complete and detailed understanding of the mode of action of macrolides has remained vague, as new findings have challenged theories that are already in existence-due to this obscurity, research into macrolide modes of action continues to this day.

CONCLUSION

In this review, we present an overview of macrolide antibiotics, with an emphasis on the latest knowledge regarding the mode of action of macrolides as well as the mechanisms of resistance employed by bacteria against macrolides.

Rosacea: Pathogenesis and Therapeutic Correlates

Rosacea is a chronic inflammatory condition of which there is no cure. The pathogenesis of rosacea is likely multifactorial, involving genetic and environmental contributions. Current understanding suggests that pro-inflammatory pathways involving cathelicidins and inflammasome complexes are central to rosacea pathogenesis. Common rosacea triggers modulate these pathways in a complex manner, which may contribute to the varying severity and clinical presentations of rosacea. Established and emerging rosacea treatments may owe their efficacy to their ability to target different players in these pro-inflammatory pathways. Improving our molecular understanding of rosacea will guide the development of new therapies and the use of combination therapies.

Case report: Idiopathic subglottic stenosis in a girl; successful treatment with macrolides

An 8-year-old girl presented with treatment-refractory cough and inspiratory stridor. Bronchoscopies showed progressive scarring leading to narrowing of the proximal trachea (Myer-Cotton Grade 2) and epithelial metaplasia of the tracheal and bronchial mucosa. After excluding other causes of congenital and acquired tracheal stenosis, an idiopathic subglottic tracheal stenosis (iSGS) was diagnosed. Because of the patient's young age, a judicious therapeutic approach seemed appropriate. Therapy with azithromycin, followed by roxithromycin, was started. Symptoms almost completely subsided, spirometry normalized, and endoscopic and histologic findings improved considerably. Therapy has been continued for more than 3 years with normal lung function values, and no compromise on physical activities and development. In instances of iSGS, therapy with macrolides is worth considering before more invasive procedures such as dilatation, laser, intralesional injections, or surgical resection are performed.

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.

Therapeutic approaches and targets for treatment of autoimmune bullous diseases

Autoimmune bullous diseases are a heterogeneous group of diseases characterized by the development of cutaneous and mucosal vesicles, blisters, and finally erosions. The common pathogenetic mechanism is the presence of autoantibodies targeting structural proteins of the skin and mucous membranes (demosomes and hemidesmosomes): in the case of pemphigus, the antigens are intraepidermal, whereas in the case of pemphigoid, dermatitis herpetiformis, and epidermolysis bullosa acquisita they are subepidermal. Mucosal involvement typically affects the oral and ocular mucosa, but in some cases, the upper airways or the upper digestive tract are affected. The burden on patients' lives could be severe due to the impairment of normal feeding or breathing. In other cases, they may represent paraneoplastic syndromes. Since autoimmune bullous diseases may result in significant morbidity and mortality, depending on the grade of cutaneous and mucosal involvement, a prompt therapeutic approach is mandatory and, in recalcitrant cases, may be challenging. The first line therapy consists of corticosteroids, both topical and systemic. Once remission or control of the acute phase is obtained, adjuvant therapies need to be introduced in order to spare the corticosteroid load and minimize side effects such as iatrogenic diabetes or osteoporosis. Herein, we describe all current therapeutic approaches to autoimmune bullous diseases, also including emerging therapies.

A review of antibiotics and psoriasis: induction, exacerbation, and amelioration

Introduction: Psoriasis is affected by many environmental factors, including infections and antibiotics. However, the relationship between antibiotics and psoriasis is inadequately studied. Some antibiotics were listed as triggering factors; others showed benefit for psoriasis control. The aim of this article is to review current evidence that may help identify appropriate antibiotics for patients with psoriasis. Areas covered: The PubMed, Embase, Clinicalkey databases, and google scholar were searched for relevant articles published up to May 2019. Literature regarding antibiotics and psoriasis were included. Six randomized controlled trials and four controlled or cohort studies were identified in 13 kinds of antibiotics. Expert opinion: Macrolides and rifampin showed decrease of psoriasis area and severity index score in plaque-type psoriasis, while penicillin revealed no statistically significant improvement in guttate psoriasis. Previously tetracyclines were considered as triggering factors, but data were found only in cases or retrospective studies. Mechanisms were thought to be related to immunomodulation rather than bacteria inhibition. Research gap in the influence of genetic susceptibility, the impact on microbiota, and the mode of actions remain to be investigated.

Pruritus Associated with Commonly Prescribed Medications in a Tertiary Care Center

Background: Sparse data are available on rates of drug-induced pruritus, a well-recognized adverse reaction. We sought to assess relative rates of pruritus associated with commonly prescribed medications. Methods: Using the electronic medical record system EPIC, retrospective data were collected on patients seen at Johns Hopkins who received a medication of interest in a five-year period (2013–2018). Sequential criteria were used to identify the subpopulation who presented with a chief complaint of “pruritus” or diagnosis of “itching” within three months of receiving drugs. Results: We identified 9802 patients with pruritus after drug initiation and 1,085,404 patients without. A higher proportion of those with pruritus were female (70%) than those without (58%), p < 0.001. Patients in both groups were most commonly 50 to 79 years old. A higher proportion of patients with pruritus were black (40%) compared to those without (23%), p < 0.001. In this study, the highest rates of pruritus were observed with heparin (1.11%), trimethoprim-sulfamethoxazole (1.06%), and calcium channel blockers (0.92%). Psychiatric/neurologic drugs used to treat pruritus were associated with low rates of itch. Conclusions: Certain cardiovascular and antimicrobial agents are associated with increased frequencies of pruritus. This knowledge may guide providers in clinical selection of commonly used agents to minimize adverse effects associated with reduced compliance.

Efficacy of Azithromycin in Treatment of Acne Vulgaris: A Mini Review

BACKGROUND

Antibiotics are commonly used in the treatment of acne vulgaris. Considering the rise of antibiotic resistance, alternative medications may be used in the main anti-acne armamentarium. The aim of this study was to investigate the efficacy of oral azithromycin in the treatment of acne vulgaris.

METHODS

Database searches were performed in PubMed and Scopus using the keywords “azithromycin” and “acne”.

RESULTS

Azithromycin 500 mg once daily for 3 days per week or in cycles of 10 days for 12 weeks are the most commonly used regimens.

CONCLUSION

Available experimental data suggest that oral azithromycin is an effective and well-tolerated option for treatment of acne vulgaris.

Bacterial Dysbiosis and Translocation in Psoriasis Vulgaris

Psoriasis vulgaris is a chronic inflammatory skin condition, associated with both a physical and a psychological burden. Our understanding of the etiology of this disease remains incomplete. Conventionally, psoriasis has been viewed as a condition that manifests solely in the skin. However, the systemic inflammatory nature of this disease has been confirmed by the presence of a wide array of dysregulated cytokines and inflammatory markers in the serum of these patients. Both dysregulated gut and skin microbiomes have been found in association with psoriasis. An evident association also exists between inflammatory bowel disease and this condition. Regarding the skin microbiome, changes have been observed in the relative abundance of Firmicutes, Actinobacteria, and Proteobacteria. Additionally, Staphylococcus and Streptococcus spp. were detected more frequently in lesional skin. Alterations in the gut microbiome have been characterized by a decrease in the Bacteroidetes phylum and an increase in the Faecalibacterium genus. We suggest that dysbiosis of the skin and gut microbiota may contribute to psoriasis, by promoting the translocation of microbes from these sites into the bloodstream. Consistent with the Iron Dysregulation and Dormant Microbes hypothesis, these microorganisms are in a physiologically dormant state, but may be awakened periodically and shed their cell wall components, such as lipopolysaccharide and lipoteichoic acid. Both of these inflammagens may contribute significantly to maintaining a chronic inflammatory state in the host, such as is seen in individuals diagnosed with psoriasis.

Cancer risk by the subtype of alopecia

The cancer risk in patients with alopecia areata (AA) or alopecia totalis (AT)/alopecia universalis (AU) remains unknown. In this study, national statistical data were used to study the association between these forms of alopecia and the risk of cancer. We enrolled 668,604 patients who were treated for alopecia from 2007 to 2014, and age- and sex-matched control subjects. AA and AT/AU patients had slightly higher overall cancer risks (hazard ratio (HR), 1.043; 95% confidence interval (CI), 1.022-1.065 and HR, 1.07; 95% CI, 1.013-1.129, respectively) than controls, after adjusting for confounding factors. The risks of oral cavity, esophagus, liver, biliary tract, pancreas, larynx, lung, kidney, breast, cervix, ovary, uterus, testis, nerve, and skin cancers; and lymphoma, multiple myeloma, and leukemia, were not increased in alopecia patients. In AA or AT/AU patients, the only increased risk was that of thyroid cancer. In AA patients alone, the risks of bladder and prostate cancers were increased. Thus, the cancer risks varied by the alopecia subtype. Careful monitoring is needed to explore if the actual risks of thyroid, bladder, and prostate cancers are increased in alopecia patients.

Topical chlorhexidine, povidone-iodine and erythromycin in the repair of traumatic ulcers on the rat tongue: Clinical, histological and microbiological evaluation

OBJECTIVE

This study investigated the effect of topical application of 0.12% chlorhexidine, 10% povidone-iodine and 50% erythromycin on the optimization of healing process of traumatic ulcers made on ventral tongue of rats.

DESIGN

Forty-Eight Wistar rats were randomly divided into four groups: control, chlorhexidine (Chx), povidone-iodine (PvI) and erythromycin (Er). An ulcer of 5 mm in diameter was made on the ventral tongue of the animals. After 24 h, a microbiological sample was taken and daily application of the substances started. Six animals each group were euthanized at 4 days and the others at 8 days postoperative, totaling three and seven days of treatment. Prior to euthanasia, a new microbiological collection was performed.

RESULTS

The experimental groups showed less area of residual ulcer. A significant difference was seen between the PvI and Chx in relation to the control after three days of treatment (p < 0.05). Although the experimental groups displayed greater newly formed epithelial area, there was no significant difference compared to the control (p > 0.05). Er exhibed the lowest inflammation scores after seven days of treatment (p < 0.05). PvI showed reduction of microorganisms at both times and under aerobic (p < 0.01 at 3 days and p < 0.001 at 7 days) and microaerophilic (p < 0.05) conditions. Er significantly reduced the count of microorganisms in aerobic condition when compared to control group (p < 0.05 at 3 days and p < 0.01 at 7 days).

CONCLUSIONS

All drugs promoted reduction of the microorganisms at the site of the injury, which may have a direct effect on the tissue repair process.

Azithromycin impairs TLR7 signaling in dendritic cells and improves the severity of imiquimod-induced psoriasis-like skin inflammation in mice

BACKGROUND

The activation of Toll-like receptor 7 (TLR7) in dendritic cells (DCs) plays a crucial role in the pathogenesis of psoriasis. The macrolide antibiotic azithromycin (AZM) had been demonstrated to inhibit the TLR4 agonist-induced maturation and activation of murine bone marrow-derived DCs (BMDCs).

OBJECTIVE

To investigate the effects of AZM on the induction of DC maturation and activation by imiquimod (IMQ), a synthetic TLR7 agonist, as well as its potential as a therapeutic agent for psoriasis.

METHODS

The effects of AZM on IMQ-induced DC activation were investigated based on the expression of cell surface markers and cytokine secretion. The lysosomal pH, post-translational processing of TLR7, and TLR7 signaling were also examined in DCs. The therapeutic effects of AZM on psoriasis were evaluated in a murine model of IMQ-induced psoriasis-like skin inflammation.

RESULTS

AZM significantly inhibited the expression of co-stimulatory molecules (CD40 and CD80) and reduced TNF-α, IL-10, IL-12p40, IL-12p70, IL-23p19 in BMDCs and IFN-α production in plasmacytoid DCs. AZM treatment impaired lysosomal acidification, interrupted TLR7 maturation in the lysosome, and ultimately blocked the IMQ-induced NF-κB and IRF-7 nuclear translocation in DCs. AZM treatment decreased signs of IMQ-induced skin inflammation in BALB/c mice. In addition to decreasing keratinocyte hyper-proliferation and restoring their terminal differentiation, AZM treatment decreased the accumulation of DCs as well as CD4, CD8 T cells and IL-17 producing cells in psoriatic skin lesions. AZM treatment improved splenomegaly, decreased the populations of Th17 and γδ T cells, and reduced the expression of cytokines known to be involved in the pathogenesis of psoriasis, such as IL-17A, IL-17F, IL-22 and IL-23, in the skin and spleen.

CONCLUSION

AZM impaired IMQ-induced DC activation by decreasing lysosomal acidification and disrupting TLR7 maturation and signaling. AZM significantly improved the IMQ-induced psoriasis-like inflammation in mice. AZM may be a potential therapeutic candidate for psoriasis treatment.

Structure and conformational analysis of spiroketals from 6-O-methyl-9(E)-hydroxyiminoerythronolide A

Three novel spiroketals were prepared by a one-pot transformation of 6-O-methyl-9(E)-hydroxyiminoerythronolide A. We present the formation of a [4.5]spiroketal moiety within the macrolide lactone ring, but also the unexpected formation of a 10-C=11-C double bond and spontaneous change of stereochemistry at position 8-C. As a result, a thermodynamically stable structure was obtained. The structures of two new diastereomeric, unsaturated spiroketals, their configurations and conformations, were determined by means of NMR spectroscopy and molecular modelling. The reaction kinetics and mechanistic aspects of this transformation are discussed. These rearrangements provide a facile synthesis of novel macrolide scaffolds.

Individuality, phenotypic differentiation, dormancy and 'persistence' in culturable bacterial systems: commonalities shared by environmental, laboratory, and clinical microbiology

For bacteria, replication mainly involves growth by binary fission. However, in a very great many natural environments there are examples of phenotypically dormant, non-growing cells that do not replicate immediately and that are phenotypically 'nonculturable' on media that normally admit their growth. They thereby evade detection by conventional culture-based methods. Such dormant cells may also be observed in laboratory cultures and in clinical microbiology. They are usually more tolerant to stresses such as antibiotics, and in clinical microbiology they are typically referred to as 'persisters'. Bacterial cultures necessarily share a great deal of relatedness, and inclusive fitness theory implies that there are conceptual evolutionary advantages in trading a variation in growth rate against its mean, equivalent to hedging one's bets. There is much evidence that bacteria exploit this strategy widely. We here bring together data that show the commonality of these phenomena across environmental, laboratory and clinical microbiology. Considerable evidence, using methods similar to those common in environmental microbiology, now suggests that many supposedly non-communicable, chronic and inflammatory diseases are exacerbated (if not indeed largely caused) by the presence of dormant or persistent bacteria (the ability of whose components to cause inflammation is well known). This dormancy (and resuscitation therefrom) often reflects the extent of the availability of free iron. Together, these phenomena can provide a ready explanation for the continuing inflammation common to such chronic diseases and its correlation with iron dysregulation. This implies that measures designed to assess and to inhibit or remove such organisms (or their access to iron) might be of much therapeutic benefit.

Individuality, phenotypic differentiation, dormancy and 'persistence' in culturable bacterial systems: commonalities shared by environmental, laboratory, and clinical microbiology

For bacteria, replication mainly involves growth by binary fission. However, in a very great many natural environments there are examples of phenotypically dormant, non-growing cells that do not replicate immediately and that are phenotypically 'nonculturable' on media that normally admit their growth. They thereby evade detection by conventional culture-based methods. Such dormant cells may also be observed in laboratory cultures and in clinical microbiology. They are usually more tolerant to stresses such as antibiotics, and in clinical microbiology they are typically referred to as 'persisters'. Bacterial cultures necessarily share a great deal of relatedness, and inclusive fitness theory implies that there are conceptual evolutionary advantages in trading a variation in growth rate against its mean, equivalent to hedging one's bets. There is much evidence that bacteria exploit this strategy widely. We here bring together data that show the commonality of these phenomena across environmental, laboratory and clinical microbiology. Considerable evidence, using methods similar to those common in environmental microbiology, now suggests that many supposedly non-communicable, chronic and inflammatory diseases are exacerbated (if not indeed largely caused) by the presence of dormant or persistent bacteria (the ability of whose components to cause inflammation is well known). This dormancy (and resuscitation therefrom) often reflects the extent of the availability of free iron. Together, these phenomena can provide a ready explanation for the continuing inflammation common to such chronic diseases and its correlation with iron dysregulation. This implies that measures designed to assess and to inhibit or remove such organisms (or their access to iron) might be of much therapeutic benefit.

Non-anti-infective effects of antimicrobials and their clinical applications: a review

Antimicrobial agents are undoubtedly one of the key advances in the history of modern medicine and infectious diseases, improving the clinical outcomes of infection owing to their inhibitory effects on microbial growth. However, many antimicrobial agents also have biological activities stemming from their interactions with host receptors and effects on host inflammatory responses and other human or bacterial cellular biological pathways. These result in clinical uses of antimicrobial drugs that are distinct from their direct bacteriostatic or bactericidal properties. We reviewed the published literature regarding non-anti-infective therapeutic properties and proposed clinical applications of selected antimicrobials, specifically, macrolides, tetracyclines, sulfonamides, and ketoconazole. The clinical applications reviewed were varied, and we focused on uses that were clinically relevant (in terms of importance and burden of disease) and where published evidence exists. Such uses include chronic inflammatory pulmonary and skin disorders, chronic periodontitis, gastrointestinal dysmotility, rheumatoid arthritis, and cancer. Most of these potential therapeutic uses are not Food and Drug Administration approved. Clinicians need to weigh the use of antimicrobial agents for their non-anti-infective benefits, considering potential adverse effects and long-term effect on microbial resistance.

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.

Clinical application of development of nonantibiotic macrolides that correct inflammation-driven immune dysfunction in inflammatory skin diseases

BACKGROUND

Inflammation-driven immune dysfunction supports the development of several chronic human disorders including skin diseases. Nonantibiotic macrolides have anti-inflammatory and/or immunomodulatory activity that suggests the exploitation of these in the treatment of skin diseases characterized by inflammatory disorders.

MATERIALS AND METHODS

We performed an extensive review of the nonantibiotic macrolide literature published between 2005 and 2012, including cross-references of any retrieved articles. We also included some data from our own experience.

RESULTS

Calcineurin antagonists such as tacrolimus and ascomycins (e.g., pimecrolimus) act by inhibiting the activation of the nuclear factor for activated T cells (NFAT). There are new applications for these macrolides that have been available for several years and have been applied to skin and hair disorders such as atopic dermatitis, oral lichen planus, vitiligo, chronic autoimmune urticaria, rosacea, alopecia areata, pyoderma gangrenosum, Behcet's disease, neutrophilic dermatosis, and lupus erythematosus. We also reviewed new macrolides, like rapamycin, everolimus, and temsirolimus. In addition to the literature review, we report a novel class of nonantibiotic 14-member macrocycle with anti-inflammatory and immunomodulatory effects.

CONCLUSIONS

This paper summarizes the most important clinical studies and case reports dealing with the potential benefits of nonantibiotic macrolides which have opened new avenues in the development of anti-inflammatory strategies in the treatment of cutaneous disorders.