Human dendritic cell maturation and cytokine secretion upon stimulation with Bordetella pertussis filamentous haemagglutinin.

In addition to antibodies, Th1-type T cell responses are also important for long-lasting protection against pertussis. However, upon immunization with the current acellular vaccines, many children fail to induce Th1-type responses, potentially due to immunomodulatory effects of some vaccine antigens, such as filamentous haemagglutinin (FHA). We therefore analysed the ability of FHA to modulate immune functions of human monocyte-derived dendritic cells (MDDC). FHA was purified from pertussis toxin (PTX)-deficient or from PTX- and adenylate cyclase-deficient Bordetella pertussis strains, and residual endotoxin was neutralized with polymyxin B. FHA from both strains induced phenotypic maturation of human MDDC and cytokine secretion (IL-10, IL-12p40, IL-12p70, IL-23 and IL-6). To identify the FHA domains responsible for MDDC immunomodulation, MDDC were stimulated with FHA containing a Gly→Ala substitution at its RGD site (FHA-RAD) or with an 80-kDa N-terminal moiety of FHA (Fha44), containing its heparin-binding site. Whereas FHA-RAD induced maturation and cytokine production comparable to those of FHA, Fha44 did not induce IL-10 production, but maturated MDDC at least partially. Nevertheless, Fha44 induced the secretion of IL-12p40, IL-12p70, IL-23 and IL-6 by MDDC, albeit at lower levels than FHA. Thus, FHA can modulate MDDC responses in multiple ways, and IL-10 induction can be dissociated from the induction of other cytokines.

LPS-binding protein and IL-6 Mark paradoxical tuberculosis immune reconstitution inflammatory syndrome in HIV patients

Background: Tuberculosis-associated immune reconstitution inflammatory syndrome (TB-IRIS) remains a poorly understood complication in HIV-TB co-infected patients initiating antiretroviral therapy (ART). The role of the innate immune system in TB-IRIS is becoming increasingly apparent, however the potential involvement in TB-IRIS of a leaky gut and proteins that interfere with TLR stimulation by binding PAMPs has not been investigated before. Here we aimed to investigate the innate nature of the cytokine response in TB-IRIS and to identify novel potential biomarkers. Methods: From a large prospective cohort of HIV-TB co-infected patients receiving TB treatment, we compared 40 patients who developed TB-IRIS during the first month of ART with 40 patients matched for age, sex and baseline CD4 count who did not. We analyzed plasma levels of lipopolysaccharide (LPS)-binding protein (LBP), LPS, sCD14, endotoxin-core antibody, intestinal fatty acid-binding protein (I-FABP) and 18 pro-and anti-inflammatory cytokines before and during ART. Results: We observed lower baseline levels of IL-6 (p = 0.041), GCSF (p = 0.036) and LBP (p = 0.016) in TB-IRIS patients. At IRIS event, we detected higher levels of LBP, IL-1RA, IL-4, IL-6, IL-7, IL-8, G-CSF (p ≤ 0.032) and lower I-FABP levels (p = 0.013) compared to HIV-TB co-infected controls. Only IL-6 showed an independent effect in multivariate models containing significant cytokines from pre-ART (p = 0.039) and during TB-IRIS (p = 0.034). Conclusion: We report pre-ART IL-6 and LBP levels as well as IL-6, LBP and I-FABP levels during IRIS-event as potential biomarkers in TB-IRIS. Our results show no evidence of the possible contribution of a leaky gut to TB-IRIS and indicate that IL-6 holds a distinct role in the disturbed innate cytokine profile before and during TB-IRIS. Future clinical studies should investigate the importance and clinical relevance of these markers for the diagnosis and treatment of TB-IRIS. Copyright: © 2013 Goovaerts et al.