Assay of Blood and Synovial Fluid of Patients With Rheumatoid Arthritis for Staphylococcus aureus Enterotoxin D: Absence of Bacteria But Presence of Its Toxin

At Early Rheumatoid Arthritis Stage, the Infectious Spectrum Is Driven by Non-Familial Factors and Anti-CCP Immunization

Background/Objectives: Patients with rheumatoid arthritis (RA) are prone to develop infections. Methods: Accordingly, 195 untreated early (e)RA patients and 398 healthy controls were selected from women in Tatarstan's cohort to study infectious history in the anamnesis (four criteria) and in the previous year (16 criteria). Information about annual infections was collected face-to-face from year to year by a qualified rheumatologist/general practitioner and included the active use of information from medical records. Results: In the anamnesis, tuberculosis, and pneumonia, and in the previous year, respiratory tract infections, skin infections, and herpes simplex virus reactivation incidence were reported to be increased in eRA patients, as well as the event number and duration of acute and chronic tonsillitis. Moreover, more bacterial-suspected upper respiratory infections and urinary tract infections were retrieved in sporadic eRA patients as compared to familial eRA patients. An elevated immunization against CCP prevented respiratory tract infection in those with HSV exacerbation. Finally, associations were retrieved between infection (event number/delay) and RA indices: (i) chronic tonsillitis exacerbations with disease activity and health assessment (HAQ) in familial eRA; (ii) bacterial-suspected upper respiratory infections with the number of swollen and tender joints in sporadic eRA; and (iii) HSV exacerbation with inflammation in eRA patients with negative/low response against CCP. Here, we demonstrate the complex nature of the interplay of RA with specific infections. Conclusions: For the first time, differences in the patterns of annual trivial infections and their links with RA indices were found in cohorts of familial and sporadic cases of the disease. Additionally, for the first time, we identified a remarkable relationship between early RA and exacerbations of chronic tonsillitis, as well as tuberculosis in the patient's history. Altogether, this study supports the existence of a complex interplay between infections and RA at onset driven by familial status and the presence of anti-CCP Ab at elevated levels.

Genetic diversity of Staphylococcus aureus influences disease phenotype of systemic lupus erythematosus

OBJECTIVE

We investigated the genetic diversity, molecular epidemiology and evolutionary dynamics of Staphylococcus aureus (SA) isolated from SLE patients by means of phylogenetic analysis.

METHODS

Consecutive SLE patients (ACR 1997 criteria) were enrolled: clinical/laboratory data were collected and nasal swab for SA identification was performed. On the basis of the translation elongation factor (tuf) gene, a phylogenetic analysis was performed to investigate relationships and to assess significant clades. Selective pressure analysis was used to investigate the evolution of the SA tuf gene. The gene sequences from non-SLE individuals, downloaded from the GenBank database, were compared through phylogenetic analysis with the tuf gene from SLE patients.

RESULTS

We enrolled 118 patients [M/F 10/108; median (interquartile range (IQR)) age 45.5 (13.2) years; median (IQR) disease duration 120 (144) months]. Twenty-four patients (20.3%) were SA carriers (SA+), three of them MRSA. SA+ SLE showed significantly higher SLEDAI-2k values [SA+: median (IQR) 2 (3.75); SA-: 0 (2); P = 0.04]. The phylogenetic analysis, restricted to 21 non-MRSA SA+, revealed a statistically supported larger clade (A, n = 17) and a smaller one (B, n = 4). Patients located in clade A showed a significantly higher prevalence of joint involvement (88.2%) in comparison with clade B (50.0%, P < 0.0001) and SA- (62.7%, P < 0.0001). Haematological manifestations were significantly more frequent in clade A (64.7%) compared with B (50.0%, P = 0.004).

CONCLUSION

We suggest a possible role of SA nasal carriage status in SLE disease activity. Moreover, our findings support the hypothesis that bacterial genetic variants may be associated with specific disease features.

Staphylococcus aureus Nasal Carriage and Autoimmune Diseases: From Pathogenic Mechanisms to Disease Susceptibility and Phenotype

The role of infective agents in autoimmune diseases (ADs) development has been historically investigated, but in the last years has been strongly reconsidered due to the interest in the link between the microbiome and ADs. Together with the gut, the skin microbiome is characterized by the presence of several microorganisms, potentially influencing innate and adaptive immune response. S. aureus is one of the most important components of the skin microbiome that can colonize anterior nares without clinical manifestations. Data from the literature demonstrates a significantly higher prevalence of nasal colonization in ADs patients in comparison with healthy subjects, suggesting a possible role in terms of disease development and phenotypes. Thus, in the present narrative review we focused on the mechanisms by which S. aureus could influence the immune response and on its relationship with ADs, in particular granulomatosis with polyangiitis, rheumatoid arthritis, and systemic lupus erythematosus.