Skin microbiome and causal relationships in three dermatological diseases: Evidence from Mendelian randomization and Bayesian weighting

Investigating Skin Microbial Community in Malignant Melanoma Lesions

The skin microbiome is identified as one of the crucial factors in several pathological conditions, including its potential capacity in modulating cancer progression and response to treatment. A strong association of Bacilli and Betaproteobacteria classes and the Bacteroidetes phylum with melanoma is described in patients with cutaneous malignancies, while an imbalance of S. epidermidis and S. aureus is related to the progression of other skin cancers. In the present study, we characterized the microbial community in suspected lesions of 35 patients, classified, after histological analysis, as malignant melanoma lesions and benign non-melanoma lesions. Mirrored healthy skin were also included as negative control. No significant difference in alpha and beta diversity was observed when samples were categorized in four different groups (melanoma samples vs. contralateral healthy samples; melanoma samples vs. benign lesions; benign lesions vs. contralateral controls; melanoma controls vs. benign controls). The differential abundance analyses show that Corynebacterium urealyticum is more abundant in melanoma samples compared to their control, while Roseomonas gilardii is less abundant in melanoma. Staphylococcus massiliensis, Bacillus coagulans, Paracoccus yeei, Corynebacterium jeikeium, and Corynebacterium pyruviciproducens are present only in melanoma samples when compared with benign lesions.

Causal relationship between skin microbiota and Hidradenitis suppurativa: a two-sample Mendelian randomization study

BACKGROUND

Data from observational and clinical studies indicate an association between skin microbiota and hidradenitis suppurativa (HS). However, the causal relationship between skin microbiota and HS remains to be elucidated.

METHODS

We obtained data on skin microbiota and HS from summary statistics of genome-wide association studies and applied Mendelian randomization (MR) statistical methods to assess causality. Specifically, we employed both full MR and inverse MR methods, utilizing five statistical approaches, including inverse variance weighting, to evaluate causality. Furthermore, sensitivity analyses were conducted to validate the MR findings.

RESULTS

Inverse variance weighted analysis revealed that the order Burkholderiales (OR = 0.922, 95% CI 0.855-0.994, P = 0.033), the genus Enhydrobacter (OR = 0.897, 95% CI 0.815-0.986, P = 0.025), ASV037 (OR = 0.926, 95% CI 0.863-0.995, P = 0.036), and ASV016 (OR = 0.932, 95% CI 0.870-0.998, P = 0.043) exhibited a protective effect against HS. Conversely, ASV022 (OR = 1.098, 95% CI 1.027-1.175, P = 0.007) was identified as a risk factor.

CONCLUSION

Our analysis suggests a possible causal relationship between specific skin microbiota and HS. These findings shed light on the potential pathogenesis and therapeutic interventions.