Inhibition of anti-tuberculosis T-lymphocyte function with tumour necrosis factor antagonists

Reactivation of latent Mycobacterium tuberculosis (Mtb) infection is a major complication of anti-tumour necrosis factor (TNF)-α treatment, but its mechanism is not fully understood. We evaluated the effect of the TNF antagonists infliximab (Ifx), adalimumab (Ada) and etanercept (Eta) on anti-mycobacterial immune responses in two conditions: with ex vivo studies from patients treated with TNF antagonists and with the in vitro addition of TNF antagonists to cells stimulated with mycobacterial antigens. In both cases, we analysed the response of CD4(+ )T lymphocytes to purified protein derivative (PPD) and to culture filtrate protein (CFP)-10, an antigen restricted to Mtb. The tests performed were lymphoproliferation and immediate production of interferon (IFN)-γ. In the 68 patients with inflammatory diseases (rheumatoid arthritis, spondylarthropathy or Crohn's disease), including 31 patients with a previous or latent tuberculosis (TB), 14 weeks of anti-TNF-α treatment had no effect on the proliferation of CD4(+ )T lymphocytes. In contrast, the number of IFN-γ-releasing CD4(+ )T lymphocytes decreased for PPD (p < 0.005) and CFP-10 (p < 0.01) in patients with previous TB and for PPD (p < 0.05) in other patients (all vaccinated with Bacille Calmette-Guérin). Treatments with Ifx and with Eta affected IFN-γ release to a similar extent. In vitro addition of TNF antagonists to CD4(+ )T lymphocytes stimulated with mycobacterial antigens inhibited their proliferation and their expression of membrane-bound TNF (mTNF). These effects occurred late in cultures, suggesting a direct effect of TNF antagonists on activated mTNF(+ )CD4(+ )T lymphocytes, and Ifx and Ada were more efficient than Eta. Therefore, TNF antagonists have a dual action on anti-mycobacterial CD4(+ )T lymphocytes. Administered in vivo, they decrease the frequency of the subpopulation of memory CD4(+ )T lymphocytes rapidly releasing IFN-γ upon challenge with mycobacterial antigens. Added in vitro, they inhibit the activation of CD4(+ )T lymphocytes by mycobacterial antigens. Such a dual effect may explain the increased incidence of TB in patients treated with TNF antagonists as well as possible differences between TNF antagonists for the incidence and the clinical presentation of TB reactivation

ESAT-6/CFP10 Skin Test Predicts Disease in M. tuberculosis-Infected Guinea Pigs

Background: Targeted preventive chemotherapy of individuals with progressive subclinical (incipient) disease before it becomes contagious would break the chain of tuberculosis transmission in high endemic regions. We have studied the ability of a skin test response to ESAT-6 and CFP10 (E6/C10) to predict later development of tuberculosis disease in the guinea pig model. Methods and Findings: Guinea pigs, either vaccinated with BCG or unvaccinated, were infected with a low dose of Mycobacterium tuberculosis by the aerosol route and the development of delayed type hypersensitivity responses to E6/C10 and to purified protein derivative (PPD) were followed until the onset of clinical disease. We demonstrated a negative correlation between the size of the skin test response and the time to the onset of clinical disease; a large E6/C10 skin test response correlated to a shorter survival time post skin testing, while a small E6/C10 skin test reaction correlated with a longer survival time (r = 20.6 and P,0.0001). No correlation was found using PPD. Conclusions: Our data suggest that it may be possible to develop a prognostic skin test based on E6/C10 that will allow the identification of individuals with incipient disease, who have the highest risk of developing active tuberculosis in the near future

Commercial Serological Antibody Detection Tests for the Diagnosis of Pulmonary Tuberculosis: A Systematic Review

Based on a systematic review, Madhukar Pai and colleagues conclude that none of the commercial immune-based tests for pulmonary tuberculosis so far evaluated perform well enough to replace sputum smear microscopy

Relationship between disease outcome and skin test response to E6/C10 and PPD.

<p>Depicted is the size of the skin test reaction to E6/C10 (figure A) and PPD (figure B) against weeks of survival post skin testing for each animal. Each symbol represents a skin reaction from one animal tested either at week at 4, 8 or 12 weeks post infection (the first skin test for each animal). There is a negative correlation between E6/C10 skin test response and survival time post skin testing (P<0.0001) but no correlation between PPD responses and survival (P = 0.095). Triangles represent data points from BCG vaccinated animals and open squares represent data points from naïve animals.</p

Survival curves and skintest responses in <i>M. tuberculosis</i> infected guinea pigs.

<p>Survival curves of BCG vaccinated guinea pigs (triangles) and unvaccinated guinea pigs (open squares) after <i>M. tuberculosis</i> infection. The animals were sacrificed when they had lost 15% of the maximum weight or had clinical symptoms indicative of severe TB (<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0001978#pone-0001978-g001" target="_blank">Fig 1A</a>). Mean skin test reaction (+/−SEM) for <i>M. tuberculosis-</i>infected unimmunized and BCG vaccinated guinea pigs (n = 7), measured as erythema after intradermal injection of 2 ug E6/C10 (Fig. 1B) or 10 T.U. PPD (Fig. 1C). Each animal received a maximum of 4 tests with more than 8 weeks interval and this schedule did not sensitize naïve animals. The experiment was repeated twice with the same overall result and data shown for a representative experiment.</p

Two-Dimensional Electrophoresis for Analysis of Mycobacterium tuberculosis Culture Filtrate and Purification and Characterization of Six Novel Proteins

Culture filtrate from Mycobacterium tuberculosis contains molecules which promote high levels of protective immunity in animal models of subunit vaccination against tuberculosis. We have used two-dimensional electrophoresis for analysis and purification of six novel M. tuberculosis culture filtrate proteins (CFPs): CFP17, CFP20, CFP21, CFP22, CFP25, and CFP28. The proteins were tested for recognition by M. tuberculosis-reactive memory cells from different strains of inbred mice and for their capacity to induce a skin test response in M. tuberculosis-infected guinea pigs. CFP17, CFP20, CFP21 and CFP25 induced both a high gamma interferon release and a strong delayed-type hypersensitivity response, and CFP21 was broadly recognized by different strains of inbred mice. N-terminal sequences were obtained for the six proteins, and the corresponding genes were identified in the Sanger M. tuberculosis genome database. In parallel we established a two-dimensional electrophoresis reference map of short-term culture filtrate components and mapped novel proteins as well as already-known CFP