The skin is colonised by a diverse community of microorganisms, working synergistically to maintain structural and functional integrity of the skin barrier. On the skin’s surface, four main bacteria phyla have been identified including Actinobacteria, Firmicutes, Proteobacteria and Bateroidetes. Alterations in the balance of these microbial communities have been associated with multiple chronic cutaneous diseases including acne.
Acne is a common, inflammatory skin disease of the pilosebaceous unit, affecting approximately 80% of the adolescent population. Recent research has identified a number of key driving factors in the pathogenesis of acne:
- Increased stimulation of sebaceous glands by androgens, neuropeptides, insulin-like growth factor-1 (IGF-1) and peroxisome proliferator-activated receptors (PPAR)
- Modification of sebum composition
- Abnormal keratinisation and plugging of the sebaceous duct
- Colonisation and proliferation of virulent strains of Cutibacterium acnes
- Release of pro-inflammatory mediators including interleukin (IL)-6, IL-8 and IL-12
Acne lesions develop around hair follicles and have various presentations including non-inflamed lesions (open and closed comedomes), inflamed lesions (papules, pustules and nodules) and secondary lesions (excoriations, pigmentation). Acne typically affects regions of the body rich in sebaceous glands, including the face, neck, back and shoulders.
The cosmetic changes associated with acne can have a significant impact on the emotional, psychological and social wellbeing of the patient, often outweighing the physical impact of the disease.
The role of the microbiome
For over 50 years, the mainstay of conventional acne treatment has been antibiotic therapy, targeting the overgrowth of C. acnes bacteria. However, as our understanding of the pathogenesis of acne evolves, the long-term benefits versus negative effects of this line of treatment comes into question.
C. acnes, formerly Propionibacterium acnes, is a commensal bacteria which plays a critical role in skin homeostasis. As an anaerobe, it thrives in the sebum rich environment of the hair follicle, where it exerts its protective benefits, preventing colonisation of other harmful bacteria, regulating pH and maintaining equilibrium amongst the skin flora.
Recent research has found that proliferation of C. acnes in acne sufferers is not significantly different to that of healthy skin and therefore may not play a key pathogenic role, unlike first thought. Instead, it is hypothesised that certain, virulent strains of C. acnes may play a more significant role, potentially contributing to biofilm formation and antibiotic resistance.
Furthermore, other commensal skin bacteria, such as S. epidermidis, may also play a key role through their ability to communicate with C. acnes and maintain homeostasis of the skin in acne patients. For this reason, the total impact of acne treatments which specifically target C. acnes are not yet fully understood.
As a result of growing concerns over antibiotic resistance and microbial dysbiosis, guidelines around antibiotic use in acne have recently tightened, restricting its use as a monotherapy and limiting length of treatment to the shortest duration of 3-4 months.
There is a clear need for innovative solutions which address these concerns and provide safe and effective treatment options for acne sufferers.
Innovative treatment solutions: Emerging evidence
Diet and acne
Recent research has debunked the myth that diet has no association with acne, demonstrating a correlation between acne severity and the intake of certain food groups such as refined sugars, saturated fats and dairy. Dairy and refined sugars have been associated with the stimulation of IGF-1 and high intake of saturated fatty acids has been shown to alter sebum composition, fueling the overgrowth of C. acnes.
Differences have been found between the gut microbiome of acne sufferers compared to healthy controls, which indicates a potential connection between the gut microbiome and acne, in which diet may play a role. A study assessing the benefits of prebiotic supplementation in acne sufferers undergoing treatment with doxycycline found significant improvements in the prebiotic group in terms of therapeutic effect and patient adherence.
Further, high quality research is required to assess the relationship between diet and acne.
Natural topical treatments
A 2018, randomised, placebo-controlled study investigated the efficacy of a natural topical treatment in comparison to conventional topical antibiotic therapy in acne sufferers. The topical cream containing 20% propolis, 3% tea tree oil and 10% Aloe vera was compared to 3% erythromycin cream in 60 patients with mild to moderate acne vulgaris. Results show more significant improvements in the erythema index of erythematous scars and reduced number of lesions with the topical herbal formula when compared with erythromycin.
Results were likely due to a combination of anti-inflammatory and antimicrobial properties of the ingredients. Furthermore, prebiotic glucomannans found in aloe have been associated with improved wound healing ability as well as improved synergism with probiotic bacteria against C. acnes proliferation.
Topical treatments containing various herbal actives may provide a safe and effective alternative treatment option for acne sufferers in the face of increasing antibiotic resistance.
Innovative treatments: Looking to the future
As an opportunistic microbe, the ability of C. acnes to thrive and initiate inflammation of the skin in acne is largely dependent on its environment. Treatments that improve sebum quality, regulate inflammatory mediators, support a healthy gut and skin microbiome, and target multi-drug resistant bacteria and their biofilms may be the way of the future for acne treatments.
In light of this, one can never underestimate the importance of a healthy diet and the benefits of an integrative and holistic approach, which recognises the full impact of acne on the sufferer, beyond the skin’s surface.
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