Molecular and functional analysis of interleukin 18 (IL-18), its receptor (IL-18R) and IL-18 binding protein (IL-18BP) in active tuberculosis and latent tuberculosis infection

Za kluczowy element w odpowiedzi odpornościowej na mykobakterie uważa się aktywność grasiczo-zależnych limfocytów T pomocniczych Th (T helper) o fenotypie Th1, które rozpoznają antygeny prątków wydzielając IFN-γ (interferon-gamma), uznawany za główną cytokinę kontrolującą rozwój M.tb. Do ważnych cytokin nasilających wytwarzanie IFN-γ należy interleukina-18 (IL-18), należąca do rodziny IL-1. Celem rozprawy doktorskiej było zweryfikowanie hipotezy, że IL-18 wraz z rozpoznającym ją receptorem (IL-18R) i wiążącym białkiem IL-18BP (IL-18 binding protein), a także cytokiny współdziałające z IL-18, IL-37 i IFN-γ, to ważne ogniwa odpowiedzi odpornościowej na mykobakterie, mogące korelować ze statusem latentnego lub aktywnego zakażenia M.tb. Duże znaczenie IL-18 w rozwoju odporności przeciwgruźliczej uzasadnia podjęcie w prezentowanej rozprawie doktorskiej badań będących próbą rozszerzenia wiedzy o molekularnych i funkcjonalnych wyznacznikach udziału tej cytokiny w inicjowanych przez M.tb procesach odpornościowych i zweryfikowaniu sugestii o potencjalnej wartości oznaczania IL-18 i białek funkcjonalnego kompleksu tej cytokiny (IL-18BP, IL-37, IFN-γ) w diagnozowaniu gruźlicy aktywnej i latentnej. Wyniki przeprowadzonych badań wykazały, iż wzrost ekspresji mRNA IL-18, zmniejszona ekspresja mRNA IL-18R i brak wzrostu ekspresji mRNA IFN-γ mogą być nowym zestawem wskaźników charakteryzujących stan równowagi między odpowiedzią odpornościową gospodarza a metabolicznym uśpieniem M.tb w trakcie utajonego bezobjawowego zakażenia. Jednocześnie stwierdzono, iż nadprodukcja IL-18, nie zrównoważona przez IL-18BP, w aktywnej gruźlicy płuc, może wskazywać na potencjalną rolę IL-18 w patomechanizmie tej choroby. Natomiast ilościowa analiza surowiczych białek kompleksu IL-18/IL-18BP/IL-37 poszerzona o ocenę poziomu chemokiny IP-10, potencjalnie może mieć zastosowanie w diagnostyce aktywnego lub utajonego zakażenia M.tb i różnicowaniu nieprątkowego zapalenia płuc.Grant Narodowego Centrum Nauki (NCN), Preludium 10, Molekularna i funkcjonalna analiza interleukiny 18 (IL-18), jej receptora (IL-18R) i wiążącego ją białka w aktywnej gruźlicy i latentnej infekcji. Nr projektu 2015/19/N/NZ6/01385. Lata 2016-2019, kierownik projektu Sebastian Wawrocki. Dotacje celowe na działalność związaną z prowadzeniem badań naukowych lub prac rozwojowych oraz zadań z nimi związanych, służących rozwojowi młodych naukowców oraz uczestników studiów doktoranckich w latach: 2017, 2018, 2019

Cytokine Receptors-Regulators of Antimycobacterial Immune Response

Cytokine receptors are critical regulators of the antimycobacterial immune response, playing a key role in initiating and coordinating the recruitment and activation of immune cells during infection. They recognize and bind specific cytokines and are involved in inducing intracellular signal transduction pathways that regulate a diverse range of biological functions, including proliferation, differentiation, metabolism and cell growth. Due to mutations in cytokine receptor genes, defective signaling may contribute to increased susceptibility to mycobacteria, allowing the pathogens to avoid killing and immune surveillance. This paper provides an overview of cytokine receptors important for the innate and adaptive immune responses against mycobacteria and discusses the implications of receptor gene defects for the course of mycobacterial infection. Keywords: cytokine; cytokine receptors; immune response; mycobacteri

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

Epithelial barrier hypothesis and the development of allergic and autoimmune diseases

The “epithelial barrier hypothesis” proposes that genetic predisposition to epithelial barrier damage, exposure to various epithelial barrier–damaging agents and chronic periepithelial inflammation are responsible for the development of allergic and autoimmune diseases. Particularly, the introduction of more than 200,000 new chemicals to our daily lives since the 1960s has played a major role in the pandemic increase of these diseases. The epithelial barrier constitutes the first line of physical, chemical, and immunological defence against external factors. A leaky epithelial barrier initiates the translocation of the microbiome from the surface of affected tissues to interepithelial and even deeper subepithelial areas. In tissues with a defective epithelial barrier, colonization of opportunistic pathogens, decreased microbiota biodiversity, local inflammation, and impaired regeneration and remodelling takes place. A dysregulated immune response against commensals and opportunistic pathogens starts. Migration of inflammatory cells to other tissues and their contribution to tissue injury and inflammation in the affected tissues are key events in the development and exacerbation of many chronic inflammatory diseases. Understanding the underlying factors that affect the integrity of epithelial barriers is essential to find preventive measures or effective treatments to restore its function. The aim of this review is to assess the origins of allergic and autoimmune diseases within the framework of the epithelial barrier hypothesis

Genetic basis for variation in plasma IL-18 levels in persons with chronic hepatitis C virus and human immunodeficiency virus-1 infections

Inflammasomes are multi-protein complexes integrating pathogen-triggered signaling leading to the generation of pro-inflammatory cytokines including interleukin-18 (IL-18). Hepatitis C virus (HCV) and human immunodeficiency virus (HIV) infections are associated with elevated IL-18, suggesting inflammasome activation. However, there is marked person-to-person variation in the inflammasome response to HCV and HIV. We hypothesized that host genetics may explain this variation. To test this, we analyzed the associations of plasma IL-18 levels and polymorphisms in 10 genes in the inflammasome cascade. About 1538 participants with active HIV and/or HCV infection in three ancestry groups are included. Samples were genotyped using the Illumina Omni 1-quad and Omni 2.5 arrays. Linear regression analyses were performed to test the association of variants with log IL-18 including HCV and HIV infection status, and HIV RNA in each ancestry group and then meta-analyzed. Eleven highly correlated single-nucleotide polymorphisms (r²=0.98–1) in the IL-18-BCO2 region were significantly associated with log IL-18; each T allele of rs80011693 confers a decrease of 0.06 log pg ml⁻¹ of IL-18 after adjusting for covariates (rs80011693; rs111311302 β=−0.06, P-value=2.7 × 10⁻⁴). In conclusion, genetic variation in IL-18 is associated with IL-18 production in response to HIV and HCV infection, and may explain variability in the inflammatory outcomes of chronic viral infections

Inflammasomes in Mycobacterium tuberculosis-Driven Immunity

The development of effective innate and subsequent adaptive host immune responses is highly dependent on the production of proinflammatory cytokines that increase the activity of immune cells. The key role in this process is played by inflammasomes, multimeric protein complexes serving as a platform for caspase-1, an enzyme responsible for proteolytic cleavage of IL-1β and IL-18 precursors. Inflammasome activation, which triggers the multifaceted activity of these two proinflammatory cytokines, is a prerequisite for developing an efficient inflammatory response against pathogenic Mycobacterium tuberculosis (M.tb). This review focuses on the role of NLRP3 and AIM2 inflammasomes in M.tb-driven immunity

Cytokine Receptors—Regulators of Antimycobacterial Immune Response

Cytokine receptors are critical regulators of the antimycobacterial immune response, playing a key role in initiating and coordinating the recruitment and activation of immune cells during infection. They recognize and bind specific cytokines and are involved in inducing intracellular signal transduction pathways that regulate a diverse range of biological functions, including proliferation, differentiation, metabolism and cell growth. Due to mutations in cytokine receptor genes, defective signaling may contribute to increased susceptibility to mycobacteria, allowing the pathogens to avoid killing and immune surveillance. This paper provides an overview of cytokine receptors important for the innate and adaptive immune responses against mycobacteria and discusses the implications of receptor gene defects for the course of mycobacterial infection