Recent studies have suggested that the intestinal microbiome plays an important role in modulating risk of several chronic diseases, including inflammatory bowel disease, obesity, type 2 diabetes, cardiovascular disease, and cancer. At the same time, it is now understood that diet plays a significant role in shaping the microbiome, with experiments showing that dietary alterations can induce large, temporary microbial shifts within 24 h. Given this association, there may be significant therapeutic utility in altering microbial composition through diet. This review systematically evaluates current data regarding the effects of several common dietary components on intestinal microbiota. We show that consumption of particular types of food produces predictable shifts in existing host bacterial genera. Furthermore, the identity of these bacteria affects host immune and metabolic parameters, with broad implications for human health. Familiarity with these associations will be of tremendous use to the practitioner as well as the patient.

BackgroundPsoriasis impacts 1–3% of the world’s population and is characterized by hyper-proliferation of keratinocytes and increased inflammation. At the molecular level, psoriasis is commonly driven by a Th17 response, which serves as a major therapeutic target. Microbiome perturbations have been associated with several immune-mediated diseases such as atopic dermatitis, asthma, and multiple sclerosis. Although a few studies have investigated the association between the skin microbiome and psoriasis, conflicting results have been reported plausibly due to the lack of standardized sampling and profiling protocols, or to inherent microbial variability across human subjects and underpowered studies. To better understand the link between the cutaneous microbiota and psoriasis, we conducted an analysis of skin bacterial communities of 28 psoriasis patients and 26 healthy subjects, sampled at six body sites using a standardized protocol and higher sequencing depth compared to previous studies. Mouse studies were employed to examine dermal microbial-immune interactions of bacterial species identified from our study.ResultsSkin microbiome profiling based on sequencing the 16S rRNA V1–V3 variable region revealed significant differences between the psoriasis-associated and healthy skin microbiota. Comparing the overall community structures, psoriasis-associated microbiota displayed higher diversity and more heterogeneity compared to healthy skin bacterial communities. Specific microbial signatures were associated with psoriatic lesional, psoriatic non-lesional, and healthy skin. Specifically, relative enrichment of Staphylococcus aureus was strongly associated with both lesional and non-lesional psoriatic skin. In contrast, Staphylococcus epidermidis and Propionibacterium acnes were underrepresented in psoriatic lesions compared to healthy skin, especially on the arm, gluteal fold, and trunk. Employing a mouse model to further study the impact of cutaneous Staphylcoccus species on the skin T cell differentiation, we found that newborn mice colonized with Staphylococcus aureus demonstrated strong Th17 polarization, whereas mice colonized with Staphylococcus epidermidis or un-colonized controls showed no such response.ConclusionOur results suggest that microbial communities on psoriatic skin is substantially different from those on healthy skin. The psoriatic skin microbiome has increased diversity and reduced stability compared to the healthy skin microbiome. The loss of community stability and decrease in immunoregulatory bacteria such as Staphylococcus epidermidis and Propionibacterium acnes may lead to higher colonization with pathogens such as Staphylococcus aureus, which could exacerbate cutaneous inflammation along the Th17 axis.Electronic supplementary materialThe online version of this article (10.1186/s40168-018-0533-1) contains supplementary material, which is available to authorized users.

IL-17 is involved in the pathogenesis of several autoimmune diseases, however its role in vitiligo has not been well defined. Emerging human and mouse studies have demonstrated that systemic, tissue, and cellular levels of IL-17 are elevated in vitiligo. Many studies have also shown significant positive correlations between these levels and disease activity, extent, and severity. Treatments that improve vitiligo, such as ultraviolet B phototherapy, also modulate IL-17 levels. This review synthesizes our current understanding of how IL-17 may influence the pathogenesis of autoimmune vitiligo at the molecular level. This has implications for defining new vitiligo biomarkers and treatments.

IntroductionPsoriasis patients demonstrate high interest in the role of diet on their skin condition. However, data are lacking to describe dietary interventions among psoriasis patients and associated outcomes. This study aims to identify common dietary habits, interventions and perceptions among patients with psoriasis, and to examine patient-reported skin outcomes in response to these interventions.MethodsWe administered a 61-question survey to the National Psoriasis Foundation membership asking psoriasis patients about dietary habits, modifications, skin responses, and perceptions.ResultsA total of 1206 psoriasis patients responded to the survey. Compared to age- and sex-matched controls, psoriasis patients consumed significantly less sugar, whole grain fiber, dairy, and calcium (p < 0.001), while consuming more fruits, vegetables, and legumes (p < 0.01). Eighty-six percent of respondents reported use of a dietary modification. The percentage of patients reporting skin improvement was greatest after reducing alcohol (53.8%), gluten (53.4%), nightshades (52.1%), and after adding fish oil/omega-3 (44.6%), vegetables (42.5%), and oral vitamin D (41%). Specific diets with the most patients reporting a favorable skin response were Pagano (72.2%), vegan (70%), and Paleolithic (68.9%). Additionally, 41.8% of psoriasis respondents reported that a motivation for attempting dietary changes was to improve overall health.ConclusionThis national survey is among the first to report the dietary behaviors of patients with psoriasis. The data provided from this large cohort may benefit patients and clinicians as they discuss the role of diet in managing both psoriasis and associated cardiometabolic comorbidities.Electronic supplementary materialThe online version of this article (doi:10.1007/s13555-017-0183-4) contains supplementary material, which is available to authorized users.