Detection of DNA of Chlamydophila psittaci in subjects with psoriasis: a casual or a causal link?

BACKGROUND: Recent evidence indicates that subclinical infection by Chlamydophila psittaci occurs in a significant percentage of patients with chronic inflammatory polyarthritis, including psoriatic arthritis. OBJECTIVE: To assess the prevalence of Chlamydiae infection in a large cohort of well-characterized patients with psoriasis. METHODS: The presence of a subclinical C. psittaci infection was investigated in 64 patients with psoriasis, including 12 patients with psoriatic arthritis. Two hundred and twenty-five healthy controls were also investigated. The presence of infection was assessed in peripheral blood mononuclear cells using several polymerase chain reaction protocols, targeting different regions of the bacterial genome. The DNA of other species (Chlamydophila pneumoniae and Chlamydia trachomatis) was also investigated. RESULTS: Chlamydophila psittaci infection was observed in a significantly higher percentage of patients with psoriasis (11/64, 17%) compared with healthy controls (1/225, 0.4%) (odds ratio 46.49, 95% confidence interval 5.87-368.03; P < 0.0001). No differences in age, sex or disease duration were noticed between positive and negative patients, but the majority of the positive patients were on immunomodulatory treatments. CONCLUSION: Chlamydophila psittaci may be an infectious trigger possibly involved in the pathogenesis of psoriasis.

Study on the possible role of the -174G>C IL-6 promoter polymorphism in predicting response to rituximab in rheumatoid arthritis.

OBJECTIVE: Identification of genetic biomarkers of response to biologics in rheumatoid arthritis (RA) is a relevant issue. The -174G>C interleukin-6 (IL-6) promoter polymorphism was investigated in RA patients treated with rituximab (RTX), being IL-6 a key cytokine for B cell survival and proliferation, thus possibly implicated in rituximab efficacy. METHODS: The study was conducted in a real-life retrospective cohort of 142 unselected RA patients (120F/22M) treated with RTX and referred to 7 rheumatologic centres in the north of Italy. One hundred and thirteen (79.6%) patients were rheumatoid factor (RF)-positive and 112 (78.9%) were anti-CCP antibodies positive. The response to therapy was evaluated at the end of the sixth month after the first RTX infusion, by using both the EULAR criteria (DAS28) and the ACR criteria. The IL-6 -174G>C promoter polymorphism was analyzed by RFLP following previously reported methods. RESULTS: Lack of response to RTX at month +6 by EULAR criteria was more prevalent in RA patients with the IL-6 -174 CC genotypes (9/21, 42.8%), than in the GC/GG patients (23/121, 19.0%) (OR 3.196, 95% CI=1.204-8.485; p=0.0234). Similar results were found when evaluating the response by ACR criteria. No differences were found in RA duration, baseline DAS28, baseline HAQ, RF status, anti-CCP status according to the different IL-6 -174 genotypes. CONCLUSION: IL-6 promoter genotyping may be useful to better plan treatment with RTX in RA. Larger replication studies are in course to confirm these preliminary results.