Introduction: Gut dysbiosis has been associated with the development of autoimmune diseases, including systemic lupus erythematosus (SLE). Although previous studies suggest microbial alterations in SLE, evidence at the species level and its clinical relevance remain limited. This study aimed to characterise the gut microbiota at species level in SLE patients and evaluate its association with clinical features. Materials and methods: A total of 57 SLE patients and 57 matched controls were included. Faecal samples were collected using the OMNIgene-GUT kit, and microbial DNA was extracted with the Maxwell RSC PureFood GMO kit. Metagenomic sequencing was performed using the Illumina MiSeq platform, and the data was analysed with QIIME2. Microbial diversity and relative abundance were assessed using the phyloseq package, and differentially abundant taxa were identified using DESeq2. Clinical subgroups among SLE patients were identified via k-means clustering. Results: SLE patients exhibited significantly different beta diversity compared to controls (p = 0.001), with increased abundance of Pseudomonadota (3.81% vs. 6.80%, p < 0.05) and decreased Bacteroidota (53.42% vs. 38.04%, p < 0.05). Only 10 bacterial species were consistently present across all SLE samples, including Akkermansia muciniphila, Bacteroides dorei, and Lactobacillus gasseri. Hypertensive patients and those treated with corticosteroids presented a marked depletion of key microbial taxa. Conversely, Belimumab-treated patients displayed a distinct microbiota enriched in species such as Alistipes shahii and Prevotella corporis. Conclusions: This study confirms significant gut microbiota alterations in SLE and pinpoints microbial profiles associated with clinical subgroups. These findings suggest gut dysbiosis may contribute to SLE pathogenesis and indicate biomarkers for disease stratification.

Fabry disease (FD) is an X-linked genetic disorder characterized by alpha-galactosidase deficiency, leading to the accumulation of globotriaosylceramide. This accumulation causes multi-organ dysfunction, with renal involvement being particularly significant. Recently, the immunological relationship of this disease has been investigated, including the inactivation of enzyme therapies by antibodies and systemic inflammation. We present the case of a 15-year-old patient with FD and ANCA-associated vasculitis (AAV). A narrative review was conducted by searching PubMed with the terms "Fabry disease" AND "vasculitis" AND "glomerulonephritis," identifying 9 relevant articles. These cases were compared with the current one, emphasizing pathophysiological aspects. 75% of patients had fever, 50% had peripheral edema, and 25% had otorhinolaryngological involvement. Pauci-immune necrosis was found in 75%. Therapeutically, all cases were treated with plasmapheresis, 75% with cyclophosphamide, and only one case required hemodialysis during follow-up. The association of FD with vasculitis is rare, with only five cases, only one with positive ANCA. The role of the immune system in FD, still not fully understood, seems to contribute significantly to pathogenesis and complications. This case highlights the need for further research on the immunological role in FD and its relationship with vasculitis and other autoimmune diseases.