A review of next generation sequencing technologies used in the evaluation of the skin microbiome: what a time to be alive.

The role of the microbiome in healthy and disease states of the human body is progressively being found to extend beyond the gastrointestinal tract and into other organ systems such as the skin. Researching the microbiome thus has become paramount to understanding additional physiological and pathophysiological mechanisms that may be at play between microbes and their hosts. Cell cultures have traditionally been used to study the microbiome, but in our current day and age, advanced metagenomic techniques - such as 16S rRNA amplicon sequencing and whole metagenomic shotgun sequencing - are better able to classify the microorganisms making up the microbiome. Utilizing metagenomics alone, however, does not allow for the study of the more complex effects of the microbiome, such as changes in gene expression and metabolic byproducts. Thus, incorporation of other modalities such as metatranscriptomics, metaproteomics, and metabolomics are needed to further elucidate the extensive intricacies of the skin microbiome.

Prospective Placebo-Controlled Assessment of Spore-Based Probiotic Supplementation on Sebum Production, Skin Barrier Function, and Acne.

Probiotic supplementation has been shown to modulate the gut-skin axis. The goal of this study was to investigate whether oral spore-based probiotic ingestion modulates the gut microbiome, plasma short-chain fatty acids (SCFAs), and skin biophysical properties. This was a single-blinded, 8-week study (NCT03605108) in which 25 participants, 7 with noncystic acne, were assigned to take placebo capsules for the first 4 weeks, followed by 4 weeks of probiotic supplementation. Blood and stool collection, facial photography, sebum production, transepidermal water loss (TEWL), skin hydration measurements, and acne assessments were performed at baseline, 4, and 8 weeks. Probiotic supplementation resulted in a decreasing trend for the facial sebum excretion rate and increased TEWL overall. Subanalysis of the participants with acne showed improvement in total, noninflammatory, and inflammatory lesion counts, along with improvements in markers of gut permeability. The gut microbiome of the nonacne population had an increase in the relative abundance of Akkermansia, while the subpopulation of those with acne had an increase in the relative abundance of Lachnospiraceae and Ruminococcus gnavus. Probiotic supplementation augmented the circulating acetate/propionate ratio. There is preliminary evidence for the use of spore-based probiotic supplementation to shift the gut microbiome and augment short-chain fatty acids in those with and without acne. Further spore-based supplementation studies in those with noncystic acne are warranted.

Clinical utility of daylight photodynamic therapy in the treatment of actinic keratosis - a review of the literature.

Actinic keratosis (AK) is an early in situ squamous cell carcinoma that results from UV light exposure and has the potential to evolve into invasive tumor. Therefore, it is crucial that AKs are monitored and treated appropriately. Photodynamic therapy (PDT) is a treatment option that is minimally invasive and leaves patients with cosmetically superior results. However, disadvantages of PDT include pain and lengthy clinic visits. Accordingly, there has been much interest in the use of daylight photodynamic therapy (daylight-PDT) as a more convenient and less painful alternative to conventional photodynamic therapy (c-PDT). Current evidence shows that daylight-PDT is noninferior to c-PDT in the short and long term. Patients reported decreased pain with daylight-PDT and were more satisfied with the procedure (P<0.001). Current evidence suggests that 2 hrs of daylight exposure was sufficient for treatment, and its efficacy does not appear to be limited by weather conditions. Given the decreased intensity of treatment, daylight-PDT is better for mild disease, as it is less effective in moderate-to-thick AKs. Though further studies are still needed to refine the technique, daylight-PDT is a potential alternative to c-PDT for thin-to-moderate AKs and should be offered to patients with lower pain tolerance or busy schedules.