Abstract
Psoriasis is a skin inflammatory condition for which significant progress has been made in its management by the use of targeted biological drugs. Detection of latent M. tuberculosis infection (LTBI) is mandatory before starting biotherapy that is associated with reactivation risk. Together with evaluation of TB risk factors and chest radiographs, tuberculin skin tests (TST) and/or blood interferon-γ-release assays (IGRA), like the QuantiFERON (QFT), are usually performed to diagnose M. tuberculosis infection. Using this approach, 14/49 psoriatic patients prospectively included in this study were identified as LTBI (14 TST+, induration size ≥ 10mm, 8 QFT+), and 7/14 received prophylactic anti-TB treatment, the other 7 reporting past-treatment. As the specificity and sensitivity of these tests were challenged, we evaluated the added value of an IGRA in response to a mycobacterial antigen associated with latency, the heparin-binding haemagglutinin (HBHA). All but one TST+ patient had a positive HBHA-IGRA, indicating higher sensitivity than the QFT. The HBHA-IGRA was also positive for 12/35 TST-QFT- patients. Measurement for 15 psoriatic patients (12 with HBHA-IGRA+) of 8 chemokines in addition to IFN-γ revealed a broad array of HBHA-induced chemokines for TST+QFT- and TST-QFT- patients, compared to a more restricted pattern for TST+QFT+ patients. This allowed us to define subgroups within psoriatic patients characterized by different immune responses to M. tuberculosis antigens that may be associated to different risk levels of reactivation of the infection. This approach may help in prioritizing patients who should receive prophylactic anti-TB treatment before starting biotherapies in order to reduce their number.
Highlights
Psoriasis is a frequent skin inflammatory condition with a worldwide prevalence of 3%, characterized by erythematous and scaly plaques that may affect any part of the body [1, 2]
Given the limitations of the TST and the commercial interferon-g-release assays (IGRA) to diagnose latent Mycobacterium tuberculosis infection (LTBI) in patients with immune-mediated inflammatory disease (IMID), and their inability to select among LTBI subjects those who have the highest risk to reactivate the infection, we evaluated in this study the added value of an IGRA based on the latency-associated antigen heparin-binding haemagglutinin (HBHA), reported to detect LTBI with high sensitivity and specificity [18], and we compared the results of the HBHA-IGRA to those of the TST and of the QFT
Prevalence of M. tuberculosis Infection in Psoriatic Patients According to Standard Criteria In Belgium, a low-TB incidence country, forty-nine adult patients suffering from psoriasis were prospectively recruited from the outpatient clinic of the Dermatology department, as part of their evaluation before starting biotherapy
Summary
Psoriasis is a frequent skin inflammatory condition with a worldwide prevalence of 3%, characterized by erythematous and scaly plaques that may affect any part of the body [1, 2]. Patients receiving TNF-a-targeted therapies have an increased risk of reactivation of a latent Mycobacterium tuberculosis infection (LTBI), and there are few and discrepant specific reports in psoriatic patients [5], the risk of active tuberculosis (aTB) is, according to a recent meta-analysis, doubled for patients treated with anti-TNF-a [6]. The use of biological drugs to treat psoriasis was further extended to other therapeutic agents targeting the interleukin (IL)-23/IL-17 axis [7, 8], but their potential risk of reactivation of LTBI is not yet firmly established [9]. LTBI subjects are thought to present a life-long risk of reactivation of the infection, with 5 to 15% of them developing aTB during their lifetime [11]. It became evident that these last individuals are probably more at risk to reactivate the infection compared to other LTBI subjects
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