An updated literature review detailing gut microbiome alterations in allergic and inflammatory skin diseases has been published in the Journal of the European Academy of Dermatology and Venereology and provides information regarding the impact of the gut microbiome on acne, atopic dermatitis, and rosacea.
Researchers from the Medical University of Lublin in Poland searched the MEDLINE database for studies that explored the role of gastrointestinal microflora in allergic and inflammatory skin disease development. Selected skin diseases included psoriasis, palmoplantaris pustulosis, acne, hidradenitis suppurativa, rosacea, and atopic dermatitis. A total of 131 publications were identified and included in the final review.
The researchers noted a correlation between psoriasis and bowel involvement, particularly irritable bowel disorder (IBD). Patients with psoriasis, the researchers noted, have a 3-times higher risk for Crohn disease, whereas patients with Crohn disease have a 7-times higher risk for psoriasis. The Th helper cell 17 also appears to play a pathophysiologic role in both psoriasis and IBD, linking the two conditions even further. In their review, the investigators point to research demonstrating the role of intestinal flora in the regulation of Th helper cell 17 cells. Patients with psoriasis may also have increased levels of Bacteroidetes spp and reductions in Firmicutes, Proteobacteria, and Actinobacteria spp.
In patients with acne, there are some data showing an association between greater disease severity and reductions in Actinobacteria, Bifidobacterium, Butyricicoccus, Coprobacillus, and Lactobacillus spp. These patients may also have lower levels of Firmicutes spp and increased amounts of Proteobacteria spp. Some data also suggest an effect of dietary patterns on acne, with a low-glycemic diet correlating with improvement in skin lesions and lower insulin levels. For patients with rosacea, the health of the gastrointestinal tract may play a role in disease pathogenesis. Celiac disease, alterations in gastrointestinal flora, and obesity and insulin resistance have been implicated in rosacea, the review found.
The rate of IBD may also be higher in patients with hidradenitis suppurativa compared with healthy control patients, suggesting a role of gut microbiome disruption in this inflammatory skin disease. Individuals born by cesarean delivery and exposed to prenatal antibiotics have an increased risk for atopic dermatitis, also suggesting a role of gut microflora in allergic skin diseases. Increased levels of Bacteroides, Clostridium, Enterobacteriaceae, and Staphylococcus spp early in life may be associated with a higher atopic dermatitis risk. Some studies have suggested a possible benefit with probiotic supplementation in patients with atopic dermatitis.
A primary limitation of the study was the lack of a pooled meta-analysis of the reviewed studies.
Based on the reviewed literature, the researchers concluded that several “beneficial gut microbiome functions prevent pathological flora colonization, sustain proper intestinal barrier integrity and function and take part in balancing and modulating the immune response.”
Polkowska-Pruszyńska B, Gerkowicz A, Krasowska D. The gut microbiome alterations in allergic and inflammatory skin diseases – an update [published online September 14, 2019]. J Eur Acad Dermatol Venereol. doi:10.1111/jdv.15951