IL-18/IL-37/IP-10 signalling complex as a potential biomarker for discriminating active and latent TB

BACKGROUND:Currently, there are serious limitations in the direct diagnosis of active tuberculosis (ATB). We evaluated the levels of the IL-18/IL-37/IP-10 signalling complex proteins in Mycobacterium tuberculosis (M.tb)-specific antigen-stimulated QuantiFERON® Gold In-Tube (QFT) cultures and in serum samples from ATB patients, healthy individuals with latent M.tb infection (LTBI) and healthy controls (HC) to examine whether combined analyses of these proteins were useful in the differentiation of M.tb states. METHODS:The concentrations of IL-18, IL-18BP, IFN-γ, IL-37 and IP-10 in the serum and QFT supernatants were measured using specific enzyme-linked immunosorbent assay (ELISA) kits. Free IL-18 levels were calculated using the law of mass action. RESULTS:Increased concentrations of total and free IL-18, IL-18BP, IFN-γ and IP-10 in the sera of ATB patients were detected. These increases were not counterbalanced by the overproduction of IL-37. Complex co-expression of serum IL-18BP and IL-37, IP-10 and IFN-γ was identified as the highest discriminative biomarker set for the diagnosis of ATB. CONCLUSIONS:Our results suggest that the IL-18 signalling complex might be exploited by M. tuberculosis to expand the clinical manifestations of pulmonary TB. Therefore, direct analysis of the serum components of the IL-18/IL-37 signalling complex and IP-10 may be applicable in designing novel diagnostic tests for ATB

CD14-159C/T polymorphism in the development of delayed skin hypersensitivity to tuberculin

The skin tuberculin test (TST), an example of a delayed-type hypersensitivity (DTH) reaction, is based on measuring the extent of skin induration to mycobacterial tuberculin (PPD). Little is known about the genetic basis of TST reactivity, widely used for diagnosing TB infection. The study investigated the relationship of the single base change polymorphic variants in CD14 gene (CD14(-159C/T)) with the development of DTH to PPD in BCG-vaccinated Polish Caucasian individuals. We found persistent lack of TST reactivity in about 40% of healthy subjects despite receiving more than one dose of BCG. The TST size was negatively correlated with the number of BCG inoculations. The distribution of C/T genotype was significantly more frequent among TST-negative compared with TST-positive individuals. The concentration of serum sCD14 was positively associated with mCD14 expression, but not with the TST status or CD14(-159C/T) polymorphism. A significant increase in mCD14 expression and serum sCD14 levels was found in TB group. We hypothesize that CD14(-159C/T) polymorphic variants might be one of genetic components in the response to attenuated M. bovis BCG bacilli

Mycobacteria-derived biomarkers for tuberculosis diagnosis

Tuberculosis (TB) remains an escalating problem worldwide. The current diagnostic methods do not always guarantee reliable diagnosis. TB treatment is a time-consuming process that requires the use of several chemotherapeutics, to which mycobacteria are becoming increasingly resistant. This article focuses on the potential utility of biomarkers of mycobacterial origin with potential implications for TB diagnosis. Properly standardized indicators could become new diagnostic tools, improving and streamlining the identification of Mycobacterium tuberculosis infection and the implementation of appropriate therapy. These markers can also potentially provide a quick confirmation of effectiveness of new anti-mycobacterial drugs and TB vaccines, leading to a possible application in practice

Interleukin 18 (IL-18) as a target for immune intervention

Interleukin 18 (IL-18) is a pleiotropic cytokine involved in the regulation of innate and acquired immune response. In the milieu of IL-12 or IL-15, IL-18 is a potent inducer of IFN-gamma in natural killer (NK) cells and CD4 T helper (Th) 1 lymphocytes. However, IL-18 also modulates Th2 and Th17 cell responses, as well as the activity of CD8 cytotoxic cells and neutrophils, in a host microenvironment-dependent manner. It is produced by various hematopoietic and nonhematopoietic cells, including dendritic cells and macrophages. In an organism, bioactivity of the cytokine depends on the intensity of IL-18 production, the level of its natural inhibitory protein - IL-18BP (IL-18 binding protein) and the surface expression of IL-18 receptors (IL-18R) on the responding cells. This review summarizes the biology of the IL-18/IL-18BP/IL-18R system and its role in the host defense against infections. The prospects for IL-18 application in immunotherapeutic or prophylactic interventions in infectious and non-infectious diseases are discussed

Immune response gene polymorphisms in tuberculosis

Tuberculosis (TB), an infectious disease caused by Mycobacterium tuberculosis (M.tb), remains a leading public health problem in most parts of the world. Despite the discovery of the bacilli over 100 years ago, there are still many unanswered questions about the host resistance to TB. Although one third of the world's population is infected with virulent M.tb, no more than 5-10% develop active disease within their lifetime. A lot of studies suggest that host genetic factors determine the outcome of M.tb-host interactions, however, specific genes and polymorphisms that govern the development of TB are not completely understood. Strong evidence exists for genes encoding pattern recognition receptors (TLR, CD14), C-type lectins, cytokines/chemokines and their receptors (IFN-γ, TNF-α, IL-12, IL-10, MCP-1, MMP-1), major histocompatibility complex (MHC) molecules, vitamin D receptor (VDR), and proton-coupled divalent metal ion transporters (SLC11A1). Polymorphisms in these genes have a diverse influence on the susceptibility to or protection against TB among particular families, ethnicities and races. In this paper, we review recent discoveries in genetic studies and correlate these findings with their influence on TB susceptibility

The role of IL-18 in dendritic cell interactions with <em>M. bovis</em> Bacille Calmette-Guérin (BCG)

International audienceINTRODUCTION. The initiation and maintenance of specific responses to infective agents depend on dendritic cells (DC) playing the role of antigen presenting cells. IFN-γ has been demonstrated to be crucial to antimycobacterial immunity. The production of this cytokine by Th1 cells is effectively enhanced by IL-18, however, the role of IL-18 in human responsiveness to M. bovis BCG vaccine remains poorly understood. AIM. We asked a question whether human IL-18 released by the recombinant BCG strain (rBCGhIL-18) influences DC driven response to mycobacterial antigens in healthy humans who were vaccinated with BCG in childhood. MATERIALS AND METHODS. Immature DC were obtained from CD14+ monocytes, separated by magnetic sorting and stimulated for 6-days with IL-4 and GM-CSF. Dendritic cell response to live rBCGhIL-18 and BCG strains was estimated on the level of DC receptors (flow cytometry) and cytokines (ELISA) in 24-h cultures. RESULTS. Both mycobacterial strains caused a significant decrease in specific dendritic cell DC-SIGN receptor and an increase in CD86 co-receptor of the immune synapse. Neither rBCGhIL-18 nor BCG changed the expression of CD40 and HLA-DR on DC. Recombinant rBCGhIL-18 but not nonrecombinant BCG enhanced the DC expression of CD80 co-receptor and production of IP-10 chemokine, which promotes T cell migration to lymph nodes. Recombinant rBCGhIL-18 stimulated the production of T cell activating IL-23 and regulatory IL-10 by DC more intensively than nonrecombinant BCG. CONCLUSIONS. The obtained results suggest that IL-18 can positively modulate adaptive immune response to BCG bacilli by the intensification of antigen presentation and regulatory functions of dendritic cells

Naive helper T cells from BCG-vaccinated volunteers produce IFN-gamma and IL-5 to mycobacterial antigen-pulsed dendritic cells

Mycobacterium bovis bacillus Calmette-Guerin (BCG) is a live vaccine that has been used in routine vaccination against tuberculosis for nearly 80 years. However, its efficacy is controversial. The failure of BCG vaccination may be at least partially explained by the induction of poor or inappropriate host responses. Dendritic cells (DCs) are likely to play a key role in the induction of immune response to mycobacteria by polarizing the reactivity of T lymphocytes toward a Th1 profile, contributing to the generation of protective cellular immunity against mycobacteria. In this study we aimed to investigate the production of Th1 and Th2 cytokines by naive CD4(+) T cells to mycobacterial antigen-pulsed DCs in the group of young, healthy BCG vaccinated volunteers. The response of naive helper T cells was compared with the response of total blood lymphocytes. Our present results clearly showed that circulating naive CD45RA(+)CD4(+) lymphocytes from BCG-vaccinated subjects can become effector helper cells producing IFN-gamma and IL-5 under the stimulation by autologous dendritic cells presenting mycobacterial protein antigen-PPD or infected with live M. bovis BCG bacilli

Helicobacter pylorilipopolysaccharide in the il-2 milieu activates lymphocytes from dyspeptic children

In this study, we assessed the proliferative response of peripheral blood mononuclear leukocytes (PBML) from 33 children/young adolescents with chronic dyspepsia, to H. pylori LPS in the presence and absence of IL-2 as a T cell growth factor. A rapid urease test (RUT) and a presence of Helicobacter-like organisms (HLO) in the biopsy specimens allowed us to distinguish RUT/HLO-positive (17/33) and -negative (16/33) patients. H. pylori LPS alone induced a proliferation of PBML from 4 out of 33 dyspeptic patients. IL-2 increased the prevalence of the response to LPS to 59% and 74% of RUT/HLO-positive and -negative patients, respectively. PBML from RUT/HLO-positive patients responded significantly less intensively to H. pylori LPS in the presence of IL-2, to IL-2 alone and to H. pylori LPS+IL-2. However, there was no difference in PHA-driven proliferation of PBML from the patients of those two groups. A negative correlation between the responsiveness to H. pylori LPS of PBML and occurrence of type B inflammation in gastric mucosa was demonstrated. The results suggest a contribution of H. pylori LPS to an outcome of H. pylori infection. It is speculated that H. pylori LPS by an activation of immunocompetent cells may reduce gastric inflammation, decrease bacterial load and prolong H. pylori infection. (C) 2003 Federation of European Microbiological Societies. Published by Elsevier Science B.V. All rights reserved