Gut microbiota and skin pathologies: Mechanism of the gut-skin axis in atopic dermatitis and psoriasis

Therapeutic Mechanism of Kynurenine, a Metabolite of Probiotics, on Atopic Dermatitis in Mice

Atopic Dermatitis (AD) is a common inflammatory skin disease characterized primarily by its chronic and recurrent nature. This has a significant impact on productivity and human longevity. Dysbiosis of gut flora has been demonstrated to be significantly associated with the progression of AD. In our previous research, it was shown that Lactobacillus rhamnosus RL5-H3-005 (RL) and Pediococcus acidilactici RP-H3-006 (RP) have the ability to reduce the risk of disease in AD mice through the gut-mammary axis. Based on our previous work, this study aims to further investigate the effects of kynurenine (KYN), a metabolite of RL and RP, on AD mice induced by 2, 4-dinitrofluorobenzene (DNFB). In this study, we found that supplementing KYN in AD mice effectively alleviates the pathological symptoms of atopic dermatitis and further improves the levels of SCFAs in their intestines. Further research indicates that KYN's therapeutic effects on AD are primarily manifested in the reduction of secretory immunoglobulin A (sIgA), immunoglobulin E (IgE), interleukin-4 (IL-4), IL-5, IL-13, and thymic stromal lymphopoietin (TSLP) levels in mice, while also repairing the intestinal barrier function of AD mice. Overall, the metabolites KYN of probiotics RL and RP can regulate the levels of SCFAs of mice, potentially improving the symptoms of AD mice through the gut-skin axis.

Integrating network pharmacology and experimental validation to advance psoriasis treatment: Multi-target mechanistic elucidation of medicinal herbs and natural compounds

BACKGROUND

Psoriasis, a chronic immune-mediated inflammatory disease (IMID), presents significant therapeutic challenges, necessitating exploration of alternative treatments like medicinal herbs (MH) and natural compounds (NC). Network pharmacology offers predictive insights, yet a systematic evaluation connecting these predictions with experimental validation outcomes specifically for MH/NC in psoriasis is lacking. This review specifically fills this gap by comprehensively integrating and analyzing studies that combine network pharmacology predictions with subsequent experimental validation.

METHODS

A systematic literature search identified 44 studies employing both network pharmacology and in vitro or in vivo experimental methods for MH/NC targeting psoriasis. This review provides a systematic analysis of the specific network pharmacology platforms, predicted targets/pathways, in vivo and in vitro experimental validation models, and key biomarker changes reported across these integrated studies. Methodological approaches and the consistency between predictions and empirical findings were critically evaluated.

RESULTS

This first comprehensive analysis reveals that network pharmacology predictions regarding MH/NC mechanisms in psoriasis are frequently corroborated by experimental data. Key signaling pathways, including the IL-17/IL-23 axis, MAPK, and NF-κB, emerge as consistently predicted and experimentally validated targets across diverse natural products. The review maps the specific network pharmacology tools and experimental designs utilized, establishing a methodological benchmark for the field and highlighting the successful synergy between computational prediction and empirical verification.

CONCLUSION

By systematically integrating and critically assessing the linkage between network pharmacology predictions and experimental validation for MH/NC in psoriasis, this review offers a unique clarification of the current, validated state-of-the-art, differentiating it from previous literature. It confirms network pharmacology's predictive power for natural products, identifies robustly validated therapeutic pathways, and provides a crucial benchmark, offering data-driven insights for future research into artificial intelligence-enhanced natural product-based therapies for psoriasis and other IMIDs.

Mapping the global research landscape on psoriasis and the gut microbiota: visualization and bibliometric analysis

Background

Psoriasis is a common chronic inflammatory skin disease with a complex pathogenesis. Recently, the role of gut microbiota in psoriasis has attracted increasing attention. A systematic bibliometric analysis of relevant literature is necessary to understand better the current state and development trends in this field.

Materials and methods

The Web of Science Core Collection database was searched for literature indexed from 2004 to October 15, 2024. Bibliometric analysis was conducted using Bibliometrix, CiteSpace (version 6.3.R1), R 4.2.2 with the Bibliometrix package, Scimago Graphica 1.0.45, and VOSviewer (version 1.6.20.0) to visualize publication types, years, authors, countries, institutions, journal sources, references, and keywords.

Results

The development of psoriasis and gut microbiota research can be divided into two phases: slow growth (2004-2014) and rapid development (2014-2024). Lidia Rudnicka is the most active and influential author. China produced the highest number of publications, followed by the United States, which had the highest number of citations per article. The International Journal of Molecular Sciences published the most articles. In contrast, articles in the Journal of Investigative Dermatology, British Journal of Dermatology, and Journal of Allergy and Clinical Immunology were cited over 1,000 times. Keyword and co-citation analyses identified evolving research hotspots. Early studies focused on the association between gut microbiota and comorbid inflammatory diseases. Recent research has delved into specific mechanisms, such as disruption of gut barrier function, short-chain fatty acid metabolism alterations, impaired regulatory T-cell function, and excessive activation of Th17 cells. These mechanisms highlight how gut dysbiosis exacerbates psoriasis patients' systemic inflammation and skin lesions.

Conclusion

The field of psoriasis and gut microbiota research is developing rapidly despite uneven research distribution. This bibliometric evaluation assesses the current state of research and provides new perspectives for understanding the complex interactions between microbes and the host. Future efforts should strengthen international collaboration to deeply explore the mechanisms of gut microbiota's role in psoriasis, especially its potential applications in disease diagnosis and treatment.

Probiotics and Diet in Rosacea: Current Evidence and Future Perspectives

Rosacea is a common inflammatory skin disease, characterized by erythema, papules and pustules. The pathophysiology of rosacea remains unclear, but the complex interplay between environmental and genetic factors may act as a trigger to an abnormal innate immune response associated with a multifaceted neurovascular reaction. Increasing evidence suggests that the gut microbiota is significantly involved in the pathogenesis of rosacea, playing an important role in the inflammatory cutaneous response. Dysbiosis, small intestinal bacterial overgrowth, Helicobacter pylori infection and innate immune system dysregulation mutually contribute to the pathophysiology of rosacea, but more extensive future research is needed to better clarify their precise mechanisms of action. Many dietary triggers have been postulated for this disease; however, there is a lack of well-made and controlled studies able to undoubtedly demonstrate a causal relationship between rosacea and diet. We analyzed the available studies on the role of diet and gut microbiome in rosacea and the positive clinical effects reported by the current literature on probiotics, prebiotics, postbiotics and nutrients. Ultimately, this article improves our understanding of the gut-skin axis in rosacea, focusing on how probiotic supplementation and diet could improve the clinical management of patients affected by this common and debilitating disease.

Saccharomyces boulardii (CNCM I-745) ameliorates Ovalbumin-induced atopic dermatitis by modulating the NF-κB signaling in skin and colon

Atopic dermatitis (AD) is a long-lasting allergic disorder characterized by itching, redness, swelling, dry skin, scaling, inflammation, and tissue damage. The exact cause of AD is still unknown. Steroid medications are frequently utilized in treating AD, but their prolonged use can result in complications. Multiple studies suggest probiotics may regulate the immune system, boost immune functionality, or reduce overactive immune responses. The current study investigated the anti-inflammatory, antioxidant, and immunomodulatory role of Saccharomyces boulardii in Ovalbumin (OVA)-induced AD in a murine model. Balb/c mice were sensitized and challenged with OVA to induce AD-like lesions. S. boulardii 1 × 109 CFU/ml/day/mice was orally administrated either as a pretreatment (administered 7 days before OVA induction and continued till day 28) or concurrent treatment (administered from day 1 and continued till day 28). Dexamethasone (5 mg/kg/day) was used as a standard treatment. S. boulardii alleviated the macroscopic and behavioral changes. Blood inflammatory cells were significantly reduced. Serum IgE levels were decreased. Oxidative stress and histopathological changes (epidermal/dermal thickness, inflammatory cells, collagen deposition) in skin tissue were improved. Similarly, the colon's antioxidant capacity and histological architecture were also maintained. Expression of proinflammatory cytokines like TNF-⍺ and IL-1β were significantly reduced in skin and colon tissue. The probiotic S. boulardii under study reduced inflammation by downregulating NF-κB signaling in both skin and colon tissue. This study provides a basis for a possible gut-skin axis, which can be targeted to relieve AD symptoms.

Gut barrier integrity disruption in atopic dermatitis: truth or myth-a case-control study

Background

Gut dysbiosis has been linked to the onset and progression of various diseases, including atopic dermatitis, by disrupting the intestinal barrier integrity. In turn, it allows the translocation of microbes and toxins into the systemic circulation, which triggers an immune response.

Objectives

To measure serum levels of the gut integrity markers claudin 3 and intestinal fatty acid-binding protein in patients with atopic dermatitis.

Methods

This prospective study was conducted on 43 patients with atopic dermatitis. Healthy volunteers (n = 35) served as controls. The serum level of claudin 3 and intestinal fatty acid-binding protein were measured using an enzyme-linked immunosorbent assay for all participants.

Results

There were no significant differences in serum levels of claudin 3 and intestinal fatty acid-binding protein between patients with atopic dermatitis and the control group (P = 0.61 and 0.81, respectively). In addition, there was no significant correlation between the two markers, and different clinical and laboratory parameters (onset of disease, eczema area severity index, other allergic manifestations and serum IgE).

Conclusion

Alterations in the intestinal barrier may be absent in the ethnically distinct group of patients with atopic dermatitis included in our study. Nevertheless, our findings might have been influenced by factors such as the duration of the disease, diet and characteristics of the study population. Further studies are needed to investigate additional biomarkers or mechanisms that may be involved in atopic dermatitis pathogenesis, especially those related to the gut-skin axis.

The Interplay of Nutrition, the Gut Microbiota and Immunity and Its Contribution to Human Disease

Nutrition, the gut microbiota and immunity are all important factors in the maintenance of health. However, there is a growing realization of the complex interplay between these elements coalescing in a nutrition-gut microbiota-immunity axis. This regulatory axis is critical for health with disruption being implicated in a broad range of diseases, including autoimmune disorders, allergies and mental health disorders. This new perspective continues to underpin a growing number of innovative therapeutic strategies targeting different elements of this axis to treat relevant diseases. This review describes the inter-relationships between nutrition, the gut microbiota and immunity. It then details several human diseases where disruption of the nutrition-gut microbiota-immunity axis has been identified and presents examples of how the various elements may be targeted therapeutically as alternate treatment strategies for these diseases.