Dialogue between gastrointestinal tract and skin: New insights into the Helicobacter pylori and atopic dermatitis

Probiotics ameliorate atopic dermatitis by modulating the dysbiosis of the gut microbiota in dogs

BACKGROUND

Canine atopic dermatitis (cAD) is a chronic inflammatory disease that significantly reduces the quality of life in dogs. Dysbiosis of the gut microbiota affects skin diseases through the gut-skin axis. Therefore, microbiota-targeted therapy may potentially serve as a new management strategy for cAD. The present study aimed to investigate the association between gut microbiota and cAD and to evaluate the effect of probiotics on the clinical symptoms of cAD and gut microbiota in dogs.

RESULTS

Gut microbiota was analyzed at baseline and after 8 and 16 weeks. Baseline analysis revealed significantly lower (p < 0.05) gut microbial diversity in dogs with cAD than in healthy dogs. Differential abundance analysis showed that Fusobacterium, Megamonas, Collinsella, unclassified Clostridiales, Bacillus, Helicobacter, and Caproiciproducens were significantly more abundant in healthy dogs. In contrast, Clostridioides, Erysipelatoclostridium, Clostridium, Terrisporobacter, and unclassified Ruminococcaceae were significantly more abundant in dogs with cAD, In addition, differential abundance analysis showed that the abundance of 46 metabolic pathways were significantly different between healthy dogs and dogs with cAD indicating the dysbiosis of the gut microbiota in cAD. Moreover, the clinical severity of cAD was negatively correlated (p < 0.05) with alpha diversity and the abundance of Fusobacterium and Megamonas. Notably, daily probiotic administration for 16 weeks significantly decreased the clinical severity (p < 0.05). Dogs with good prognoses exhibited significantly increased alpha diversity, whereas those with poor prognoses did not, suggesting that the therapeutic effects of probiotics may be mediated by changes in gut microbial diversity.

CONCLUSIONS

This study highlights the association between gut microbiota dysbiosis and cAD in dogs and demonstrates that probiotic administration can effectively ameliorate cAD by improving gut microbial dysbiosis. These findings provide a basis for novel microbiota-based therapies in cAD treatment.

Effect of a topical traditional Chinese herbal medicine on skin microbiota in mouse model of atopic dermatitis

This study aims to explore the impact of the herbal ointment Chushi Zhiyang Ruangao (CSZYRG) on the skin's microecological environment in a mouse model of atopic dermatitis (AD) and to understand the underlying mechanisms involved. The AD model was established in C57 mice using calpolitol (a hypocalcemic analog of vitamin D3; MC903). Medication-free matrix ointment, CSZYRG, and mometasone furoate cream (positive control group) were applied to the injured areas. The skin lesions of AD model mice were photographed. Skin lesions were applied for the hematoxylin and eosin (H&E) staining to observe any pathological changes. Serum immunoglobulin IgE was detected by enzyme-linked immunosorbent assay (ELISA). The changes in the expression of inflammation-related factors TNF-α, IL-1β, and IL-6 in mice were detected using ELISA and qRT-PCR. Skin microflora samples were taken for 16S rDNA sequencing and analyzed for changes in the skin flora diversity, abundance, and dominant flora in mice. It was concluded that CSZYRG effectively alleviates skin lesions, serum IgE, and levels of TNF-α, IL-1β, and IL-6 in AD model mice. However, CSZYRG did not affect the skin microbial diversity of AD model mice but could exert an effect on the skin microbial community in AD mice and the relative abundance of the dominant microflora. CSZYRG may play a therapeutic role in AD by affecting the skin microbial community and relative abundance of dominant microflora in AD mice.

Helicobacter pylori infection attenuates 2,4-dinitrochlorobenzene-induced atopic dermatitis-like skin lesions in C57/BL6 mice

BACKGROUND

Although numerous studies have suggested a negative correlation between Helicobacter pylori (H. pylori) infection and allergies, there has been limited research on the relationship between H. pylori infections and atopic dermatitis (AD). The present study aimed to investigate the effects of H. pylori infection in an AD mouse model and identify potential mechanisms related to type 2 immunity, skin barrier defects, and pruritus.

METHODS

A model of AD-like symptoms was established with 2,4-dinitrochlorobenzene (DNCB) after infection of the gastric cavity with H. pylori. Analysis of the expression of key inflammatory cytokines and serum levels of immunoglobulin E (IgE) was based on enzyme-linked immunosorbent assay (ELISA). The expression of filaggrin (FLG) and loricrin (LOR) were analyzed by immunohistochemistry staining. The evaluation of STAT1, STAT3, phosphorylated STAT1 (phospho-STAT1), and phosphorylated STAT3 (phospho-STAT1) expression levels in skin lesions was performed using western blot.

RESULTS

The present study showed that the H. pylori-positive AD group (HP+AD+) exhibited milder skin lesions, including erythema, erosion, swelling, and scaling, than the H. pylori-negative AD group (HP-AD+). Additionally, HP+AD+ displayed lower levels of IgE in serum, and downregulated expression of interleukins 4 and 31 (IL-4 and IL-31) in serum. Furthermore, HP+AD+ demonstrated higher expression of filaggrin and loricrin than HP-AD+. Notably, H. pylori significantly reduced the amount of phosphorylated STAT1 and STAT3.

CONCLUSION

Helicobacter pylori infection negatively regulates the inflammatory response by affecting inflammatory factors in the immune response, and repairs the defective epidermal barrier function. In addition, H. pylori infection may reduce IL-31, thereby alleviating pruritus. These effects may be associated with the inhibition of JAK-STAT signaling activation.

Skin Dialogues in Atopic Dermatitis

Atopic dermatitis (AD) is a chronic skin disorder associated with significant quality-of-life impairment and increased risk for allergic and non-allergic comorbidities. The aim of this review is to elucidate the connection between AD and most common comorbidities, as this requires a holistic and multidisciplinary approach. Advances in understanding these associations could lead to the development of highly effective and targeted treatments.

A New Formulation of Probiotics Attenuates Calcipotriol-Induced Dermatitis by Inducing Regulatory Dendritic Cells

Atopic dermatitis (AD) is a recurrent chronic inflammatory skin disease affecting up to 30% of the children population, and immuno-regulatory therapy that could modify the course of disease is urgently needed. Probiotics have demonstrated therapeutic effects on AD and could potentially regulate the disease process. However, the efficacy of probiotics for AD is inconsistent among different studies, which is mainly due to the elusive mechanism and different species and (or) strains used. In this study, we designed a mixture of five strains of probiotics (named IW5) and analyzed the effect and mechanism of IW5 on calcipotriol (MC903)-induced AD-like dermatitis. We found that IW5 significantly alleviated skin inflammation of the MC903-induced AD in mice. Administration with IW5 induced increased production of regulatory T cells and regulatory dendritic cells (DCregs) in the mesenteric lymph nodes. We also found that the diversity of the gut microbiota in the mice with MC903-induced dermatitis was increased after IW5 administration, and the level of butyrate in the gut was elevated. In cell culture, butyrate induced the production of DCregs. Our study revealed the therapeutic effects of a newly designed probiotics mixture and uncovered a possible mechanism, providing a foundation for future clinical studies.