The role of tetracyclines in rosacea

CX3CL1/CX3CR1 Signaling Mediated Neuroglia Activation Is Implicated in the Retinal Degeneration: A Potential Therapeutic Target to Prevent Photoreceptor Death

Purpose

Retinal degeneration (RD) is a large cluster of retinopathies that is characterized by the progressive photoreceptor death and visual impairments. CX3CL1/CX3CR1 signaling has been documented to mediate the microglia activation and gliosis reaction during neurodegeneration. We intend to verify whether the CX3CL1/CX3CR1 signaling is involved in the RD pathology.

Methods

A pharmacologically induced RD mice model was established. AZD8797, a CX3CR1 antagonist, was injected into the vitreous cavity of an RD model to modulate the neuroglia activation. Then, the experimental animals were subjected to functional, morphological, and behavioral analysis.

Results

The CX3CL1/CX3CR1 signaling mediated neuroglia activation was implicated in the photoreceptor demise of an RD model. Intravitreal injection of AZD8797 preserved the retinal structure and enhanced the photoreceptor survival through inhibiting the CX3CL1/CX3CR1 expressions. Fundus photography showed that the distribution of retinal vessel was clear, and the severity of lesions was alleviated by AZD8797. In particular, these morphological benefits could be translated into remarkable functional improvements, as evidenced by the behavioral test and electroretinogram (mf-ERG) examination. A mechanism study showed that AZD8797 mitigated the microglia activation and migration in the degenerative retinas. The Müller cell hyper-reaction and secondary gliosis response were also suppressed by AZD8797.

Conclusions

The neuroinflammation is implicated in the photoreceptor loss of RD pathology. Targeting the CX3CL1/CX3CR1 signaling may serve as an effective therapeutic strategy. Future refinements of these findings may cast light into the discovery of new medications for RD.

Treatment strategies, including antibiotics, to target the immune component of rosacea

INTRODUCTION

Recent advances in the understanding of the pathophysiology of rosacea have led to increased focus on the disease's immunologic etiology and to the development of immunologically based treatments. With many patients suffering from incomplete control, addressing the immune components of the disease process may provide a more effective treatment option for rosacea patients that may improve quality of life.

AREAS COVERED

This review will provide a brief overview of the pathophysiology of rosacea, as well as specific immunologic contributions to the disease state. Current standard-of-care treatments will be described, including anti-parasitic, anti-inflammatory agents, and antibiotics. Emphasis will be placed on treatments that target the immune components of the disease process.

EXPERT OPINION

Rosacea remains a difficult dermatologic disease to treat, partially due to an incomplete understanding of the disease pathophysiology. The immune pathophysiology of rosacea, particularly the key role of inflammation, has been clarified over the past decade. Identification of specific molecules, including cytokines and nuclear transcription factors, may allow for the development of targeted rosacea-specific biologic and topical treatments. However, medication nonadherence is a limiting factor to achieving symptomatic control among rosacea patients. Focusing on the development of oral or injectable forms of therapy may circumvent poor adherence.

Tetracyclines and bone: Unclear actions with potentially lasting effects

Tetracyclines are a broad-spectrum class of antibiotics that have unclear actions with potentially lasting effects on bone metabolism. Initially isolated from Streptomyces, tetracycline proved to be an effective treatment for Gram +/- infections. The emergence of resistant bacterial strains commanded the development of later generation agents, including minocycline, doxycycline, tigecycline, sarecycline, omadacycline, and eravacycline. In 1957, it was realized that tetracyclines act as bone fluorochrome labels due to their high affinity for the bone mineral matrix. Over the course of the next decade, researchers discerned that these compounds are retained in the bone matrix at high levels after the termination of antibiotic therapy. Studies during this period provided evidence that tetracyclines could disrupt prenatal and early postnatal skeletal development. Currently, tetracyclines are most commonly prescribed as a long-term systemic therapy for the treatment of acne in healthy adolescents and young adults. Surprisingly, the impact of tetracyclines on physiologic bone modeling/remodeling is largely unknown. This article provides an overview of the pharmacology of tetracycline drugs, summarizes current knowledge about the impact of these agents on skeletal development and homeostasis, and reviews prior work targeting tetracyclines' effects on bone cell physiology. The need for future research to elucidate unclear effects of tetracyclines on the skeleton is addressed, including drug retention/release mechanisms from the bone matrix, signaling mechanisms at bone cells, the impact of newer third generation tetracycline antibiotics, and the role of the gut-bone axis.

Progress of clinical therapies for dry age-related macular degeneration

Dry age-related macular degeneration (AMD) is a progressive blinding disease that currently affects millions of people worldwide with no successful treatment available. Significant research efforts are currently underway to develop therapies aimed at slowing the progression of this disease or, more notably, reversing it. Here the therapies which have reached clinical trial for treatment of dry AMD were reviewed. A thorough search of PubMed, Embase, and Clinicaltrials.gov has led to a comprehensive collection of the most recent strategies being evaluated. This review also endeavors to assess the status and future directions of therapeutics for this debilitating condition.

The Role of Inflammation in Retinal Neurodegeneration and Degenerative Diseases

Retinal neurodegeneration is predominantly reported as the apoptosis or impaired function of the photoreceptors. Retinal degeneration is a major causative factor of irreversible vision loss leading to blindness. In recent years, retinal degenerative diseases have been investigated and many genes and genetic defects have been elucidated by many of the causative factors. An enormous amount of research has been performed to determine the pathogenesis of retinal degenerative conditions and to formulate the treatment modalities that are the critical requirements in this current scenario. Encouraging results have been obtained using gene therapy. We provide a narrative review of the various studies performed to date on the role of inflammation in human retinal degenerative diseases such as age-related macular degeneration, inherited retinal dystrophies, retinitis pigmentosa, Stargardt macular dystrophy, and Leber congenital amaurosis. In addition, we have highlighted the pivotal role of various inflammatory mechanisms in the progress of retinal degeneration. This review also offers an assessment of various therapeutic approaches, including gene-therapies and stem-cell-based therapies, for degenerative retinal diseases.

Rosacea: New Concepts in Classification and Treatment

Rosacea is a chronic inflammatory dermatosis mainly affecting the cheeks, nose, chin, and forehead. Rosacea is characterized by recurrent episodes of flushing or transient erythema, persistent erythema, phymatous changes, papules, pustules, and telangiectasia. The eyes may also be involved. Due to rosacea affecting the face, it has a profound negative impact on quality of life, self-esteem, and well-being. In addition to general skin care, there are several approved treatment options available for addressing these features, both topical and systemic. For some features, intense pulse light, laser, and surgery are of value. Recent advances in fundamental scientific research have underscored the roles of the innate and adaptive immune systems as well as neurovascular dysregulation underlying the spectrum of clinical features of rosacea. Endogenous and exogenous stimuli may initiate and aggravate several pathways in patients with rosacea. This review covers the new phenotype-based diagnosis and classification system reflecting pathophysiology, and new and emerging treatment options and approaches. We address new topical and systemic formulations, as well as recent evidence on treatment combinations. In addition, ongoing studies investigating novel therapeutic interventions will be summarized.

A Review of Systemic Minocycline Side Effects and Topical Minocycline as a Safer Alternative for Treating Acne and Rosacea

Resistance of Cutibacterium acnes to topical antibiotics historically used to treat acne (topical erythromycin and clindamycin and, more recently, topical azithromycin and clarithromycin) has been steadily increasing and new topical antibiotics are needed. Minocycline is a semisynthetic tetracycline-derived antibiotic currently used systemically to treat a wide range of infections caused by Gram-negative and Gram-positive bacteria. In addition to its antibiotic activity, minocycline possesses anti-inflammatory properties, such as the downregulation of proinflammatory cytokine production, suppression of neutrophil chemotaxis, activation of superoxide dismutase, and inhibition of phagocytosis, among others. These characteristics make minocycline a valuable agent for treatment of dermatological diseases such as acne vulgaris and papulopustular rosacea. However, more frequent or serious adverse effects have been observed upon the systemic administration of minocycline than with other tetracyclines. Examples of serious adverse effects include hypersensitivity syndrome reaction, drug-induced lupus, idiopathic intracranial hypertension, and other autoimmune syndromes that may cause death. Here, we review adverse effects and drug–drug interactions observed with oral administration of minocycline and contrast this with topical minocycline formulations recently approved or under development for effectively treating dermatological disorders with fewer adverse effects and less drug interaction.

Review of the Applications of Biomedical Compositions Containing Hydroxyapatite and Collagen Modified by Bioactive Components

Regenerative medicine is becoming a rapidly evolving technique in today’s biomedical progress scenario. Scientists around the world suggest the use of naturally synthesized biomaterials to repair and heal damaged cells. Hydroxyapatite (HAp) has the potential to replace drugs in biomedical engineering and regenerative drugs. HAp is easily biodegradable, biocompatible, and correlated with macromolecules, which facilitates their incorporation into inorganic materials. This review article provides extensive knowledge on HAp and collagen-containing compositions modified with drugs, bioactive components, metals, and selected nanoparticles. Such compositions consisting of HAp and collagen modified with various additives are used in a variety of biomedical applications such as bone tissue engineering, vascular transplantation, cartilage, and other implantable biomedical devices.

A Randomized, Placebo-Controlled Trial of Gamma Linolenic Acid as an Add-on Therapy to Minocycline for the Treatment of Rosacea

Background

A recent study suggested a possible role of skin barrier dysfunction in the pathogenesis of rosacea, which leads to irritation symptoms. Gamma linolenic acid (GLA) is an essential omega-6 fatty acid that is known to restore defective epidermal skin barrier. GLA supplementation has not previously been performed in rosacea patients.

Objective

To investigate the efficacy and safety of adding GLA to minocycline compared to minocycline alone in rosacea patients.

Methods

This prospective, double-blind, randomized, placebo-controlled trial enrolled 31 rosacea patients. They were randomly assigned to receive 320 mg/day of GLA (Evoprim®) (n=16) or placebo (n=15) in addition to 100 mg/day of minocycline for 8 weeks. Investigator's global assessment (IGA) and patient's global assessment (PGA) were used to assess clinical severity at weeks 0, 4, 8, and 12. Biophysical parameters including melanin index, erythema index, transepidermal water loss (TEWL), lipid concentration, and stratum corneum hydration were measured.

Results

In the GLA group, a higher proportion of patients achieved treatment success (IGA≤1) at week 8 (68.75% vs. 33.33%) and patient satisfaction (PGA≥3) at weeks 8 (75.0% vs. 40.0%) and 12 (81.3% vs. 46.6%). Both groups, throughout 12 weeks of treatment, revealed a trend toward improvement in erythema index, melanin index, TEWL, and stratum corneum hydration. Particularly, there was a significant difference in TEWL and stratum corneum hydration over time between the two groups (p=0.033, p=0.003, respectively). No serious adverse event was observed in both groups.

Conclusion

GLA is beneficial as an additional therapeutic option for rosacea patients treated with minocycline.

Age-related macular degeneration therapy: a review

PURPOSE OF REVIEW

The purpose of this review is to describe the current clinical landscape of potential future therapies for both nonexudative (dry) and exudative (wet) age-related macular degeneration (AMD). We highlight some of the more promising treatments that are furthest along in development.

RECENT FINDINGS

Patients with dry AMD have long been hoping for a highly efficacious treatment that may slow disease progression or even help regain vision. Patients with wet AMD have many effective treatment options but still there are those who have suboptimal responses or are burdened by the high frequency of treatment. We detail exciting new concepts and targets for novel medications. Specifically, for dry AMD we discuss research looking at complement inhibition, neuroprotection, visual cycle modulators, cell-based therapies, and anti-inflammatory agents. For wet AMD we summarize new, potentially more durable anti-vascular endothelial growth factor agents, extended release options, and gene therapy.

SUMMARY

There are promising new strategies for AMD. Many of the potential new treatments are in or have recently completed phase 2 or phase 3 clinical trials with promising results thus far, including some that have received US Food and Drug Administration approval. Additional therapeutic breakthroughs will likely continue to occur thanks to the number of clinical trials that are nearing the finish line.

Pharmacologic treatments for rosacea

Rosacea represents a common and chronic inflammatory skin disorder. Clinical features include transient and permanent erythema, inflammatory papules and pustules, phymatous changes, and ocular signs and symptoms. Rosacea is generally classified into four subtypes and one variant. Subtype 1, erythematotelangiectatic rosacea, includes clinical features of flushing and persistent central facial erythema with or without telangiectasia. Subtype 2, papulopustular rosacea, is characterized by persistent central facial erythema with transient papules or pustules or both on the central face. Subtype 3, phymatous rosacea, includes thickening of the skin with irregular surface nodularities and enlargement. Subtype 4, ocular rosacea, includes inflammation of different parts of the eye and eyelid. A variant, granulomatous rosacea, is noninflammatory and is characterized by hard, brown, yellow, or red cutaneous papules or nodules of uniform size. Patients may present with more than one subtype, and each individual characteristic may fluctuate. There is debate whether rosacea progresses from one subtype over time or subtypes represent discreet entities. Defining clinical presentation and improved understanding of pathophysiology has resulted in identification of novel treatment approaches. This contribution outlines a rationale for treatment, highlights an evidence-based approach with approved treatments, and considers novel developments and off-license therapy available.

Interventions for rosacea

BACKGROUND

Rosacea is a common chronic skin condition affecting the face, characterised by flushing, redness, pimples, pustules and dilated blood vessels. The eyes are often involved and thickening of the skin with enlargement (phymas), especially of the nose, can occur in some people. A range of treatment options are available but it is unclear which are most effective.

OBJECTIVES

To assess the efficacy and safety of treatments for rosacea.

SEARCH METHODS

We updated our searches, to July 2014, of: the Cochrane Skin Group Specialised Register, CENTRAL in The Cochrane Library (2014, Issue 6), MEDLINE (from 1946), EMBASE (from 1974) and Science Citation Index (from 1988). We searched five trials registers and checked reference lists for further relevant studies.

SELECTION CRITERIA

Randomised controlled trials in people with moderate to severe rosacea.

DATA COLLECTION AND ANALYSIS

Study selection, data extraction, risk of bias assessment and analyses were carried out independently by two authors.

MAIN RESULTS

We included 106 studies, comprising 13,631 participants. Sample sizes of 30-100 and study duration of two to three months were most common. More women than men were included, mean age of 48.6 years, and the majority had papulopustular rosacea, followed by erythematotelangiectatic rosacea.A wide range of comparisons (67) were evaluated. Topical interventions: metronidazole, azelaic acid, ivermectin, brimonidine or other topical treatments. Systemic interventions: oral antibiotics, combinations with topical treatments or other systemic treatments, i.e. isotretinoin. Several studies evaluated laser or light-based treatment.The majority of studies (57/106) were assessed as 'unclear risk of bias', 37 'high risk ' and 12 'low risk'. Twenty-two studies provided no usable or retrievable data i.e. none of our outcomes were addressed, no separate data reported for rosacea or limited data in abstracts.Eleven studies assessed our primary outcome 'change in quality of life', 52 studies participant-assessed changes in rosacea severity and almost all studies addressed adverse events, although often only limited data were provided. In most comparisons there were no statistically significant differences in number of adverse events, most were mild and transient. Physician assessments including investigators' global assessments, lesion counts and erythema were evaluated in three-quarters of the studies, but time needed for improvement and duration of remission were incompletely or not reported.The quality of the body of evidence was rated moderate to high for most outcomes, but for some outcomes low to very low.Data for several outcomes could only be pooled for topical metronidazole and azelaic acid. Both were shown to be more effective than placebo in papulopustular rosacea (moderate quality evidence for metronidazole and high for azelaic acid). Pooled data from physician assessments in three trials demonstrated that metronidazole was more effective compared to placebo (risk ratio (RR) 1.98, 95% confidence interval (CI) 1.29 to 3.02). Four trials provided data on participants' assessments, illustrating that azelaic acid was more effective than placebo (RR 1.46, 95% CI 1.30 to 1.63). The results from three studies were contradictory on which of these two treatments was most effective.Two studies showed a statistically significant and clinically important improvement in favour of topical ivermectin when compared to placebo (high quality evidence). Participants' assessments in these studies showed a RR of 1.78 (95% CI 1.50 to 2.11) and RR of 1.92 (95% CI 1.59 to 2.32),which were supported by physicians' assessments. Topical ivermectin appeared to be slightly more effective than topical metronidazole for papulopustular rosacea, based on one study, for improving quality of life and participant and physician assessed outcomes (high quality evidence for these outcomes).Topical brimonidine in two studies was more effective than vehicle in reducing erythema in rosacea at all time points over 12 hours (high quality evidence). At three hours the participants' assessments had a RR of 2.21 (95% CI 1.52 to 3.22) and RR of 2.00 (95% CI 1.33 to 3.01) in favour of brimonidine. Physicians' assessments confirmed these data. There was no rebound or worsening of erythema after treatment cessation.Topical clindamycin phosphate combined with tretinoin was not considered to be effective compared to placebo (moderate quality evidence).Topical ciclosporin ophthalmic emulsion demonstrated effectiveness and improved quality of life for people with ocular rosacea (low quality evidence).Of the comparisons assessing oral treatments for papulopustular rosacea there was moderate quality evidence that tetracycline was effective but this was based on two old studies of short duration. Physician-based assessments in two trials indicated that doxycycline appeared to be significantly more effective than placebo (RR 1.59, 95% CI 1.02 to 2.47 and RR 2.37, 95% CI 1.12 to 4.99) (high quality evidence). There was no statistically significant difference in effectiveness between 100 mg and 40 mg doxycycline, but there was evidence of fewer adverse effects with the lower dose (RR 0.25, 95% CI 0.11 to 0.54) (low quality evidence). There was very low quality evidence from one study (assessed at high risk of bias) that doxycycline 100 mg was as effective as azithromycin. Low dose minocycline (45 mg) was effective for papulopustular rosacea (low quality evidence).Oral tetracycline was compared with topical metronidazole in four studies and showed no statistically significant difference between the two treatments for any outcome (low to moderate quality evidence).Low dose isotretinoin was considered by both the participants (RR 1.23, 95% CI 1.05 to 1.43) and physicians (RR 1.18, 95% CI 1.03 to 1.36) to be slightly more effective than doxycycline 50-100 mg (high quality evidence).Pulsed dye laser was more effective than yttrium-aluminium-garnet (Nd:YAG) laser based on one study, and it appeared to be as effective as intense pulsed light therapy (both low quality evidence).

AUTHORS' CONCLUSIONS

There was high quality evidence to support the effectiveness of topical azelaic acid, topical ivermectin, brimonidine, doxycycline and isotretinoin for rosacea. Moderate quality evidence was available for topical metronidazole and oral tetracycline. There was low quality evidence for low dose minocycline, laser and intense pulsed light therapy and ciclosporin ophthalmic emulsion for ocular rosacea. Time needed to response and response duration should be addressed more completely, with more rigorous reporting of adverse events. Further studies on treatment of ocular rosacea are warranted.

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.

Topical azithromycin as a novel treatment for ocular rosacea

PURPOSE

Acne rosacea is a common dermatological conditions associated with blepharitis. Current treatments include artificial tears, lid hygiene, and systemic doxycycline. In this study the authors evaluate the effectiveness of topical azithromycin in ocular rosacea.

METHODS

The authors enrolled 37 ocular rosacea patients: 12 were treated with systemic doxycycline, 16 with azithromycin eyedrops, and 9 did not receive medical treatments. Ocular signs and symptoms and side effects were evaluated at baseline and at 1-month follow-up.

RESULTS

A significant improvement in TF-BUT, meibomian gland plugging, and Oxford score associated with symptom reduction was reported by all patients after 1 month. All treatments were well tolerated, with mild gastro-intestinal symptoms in 33% of the doxycycline group and mild burning after instillation in the azithromycin group.

CONCLUSIONS

Topical azithromycin may represent an additional treatment for ocular rosacea, with a shorter duration of treatment and absence of gastrointestinal side effects as compared to systemic doxycycline.

Rosacea treatments: What's new and what's on the horizon?

Rosacea is a common, chronic, cutaneous disorder presenting with recurrent episodes of facial flushing, erythema, papules, pustules and telangiectasias. It is a multifactorial disease and its various clinical presentations probably represent the consequence of combined different triggers upon a specific background. Its management is largely based on long-established treatments empirically tailored to the specific presenting symptoms and no real breakthrough has occurred to date. However, recent insights into the still rather obscure pathophysiology of rosacea seem to open the way for etiologically oriented treatments. These may include, on the one side, the more effective application of traditional drugs, such as tetracyclines and metronidazole, to specifically selected patients or, on the other side, new therapeutic options, such as vitamin D receptor antagonists. It is to be remarked that the quality of most studies evaluating rosacea treatment is rather poor, mainly due to a lack of proper standardization. For a major breakthrough to occur in the management of rosacea, we need both a better understanding of its pathogenesis and the adherence of future clinical trials to clearly defined grading and inclusion criteria, which are crucial for investigators to correctly compare and interpret the results of their work.