interleukin-8 and Mycobacterium-Infections

Pulmonary tuberculosis (TB), caused by the intracellular bacterial pathogen Mycobacterium tuberculosis (Mtb), is a major world health problem. The production of reactive nitrogen species (RNS) is a potent cytostatic and cytotoxic defense mechanism against intracellular pathogens. Nevertheless, the protective role of RNS during Mtb infection remains controversial. Here we use an anti-nitrotyrosine antibody as a readout to study nitration output by the zebrafish host during early mycobacterial pathogenesis. We found that recognition of Mycobacterium marinum, a close relative of Mtb, was sufficient to induce a nitrosative defense mechanism in a manner dependent on MyD88, the central adaptor protein in Toll like receptor (TLR) mediated pathogen recognition. However, this host response was attenuated by mycobacteria via a virulence mechanism independent of the well-characterized RD1 virulence locus. Our results indicate a mechanism of pathogenic mycobacteria to circumvent host defense in vivo. Shifting the balance of host-pathogen interactions in favor of the host by targeting this virulence mechanism may help to alleviate the problem of infection with Mtb strains that are resistant to multiple drug treatments.

Topics: Animals; Animals, Genetically Modified; Disease Models, Animal; Interleukin-8; Mycobacterium; Mycobacterium Infections; Myeloid Differentiation Factor 88; Neutrophils; Peroxidase; Reactive Nitrogen Species; Receptors, Interleukin-1; Receptors, Interleukin-8B; Signal Transduction; Toll-Like Receptors; Tyrosine; Zebrafish

Inadequacy of T-cell responses may result in the development of tuberculosis (TB). Myeloid-derived suppressor cells (MDSCs) have been described as suppressors of T-cell function in cancer biology and recently in several infectious diseases.. To explore the presence and role of MDSCs in TB.. We analyzed surface markers of MDSCs in peripheral blood and at the site of disease in TB cases and in patients with lung cancer, and in peripheral blood of asymptomatic tuberculin skin test-positive individuals with recent (household) or remote exposure to Mycobacterium tuberculosis (M.tb) and in uninfected healthy control subjects. To evaluate the suppressive capacity of MDSCs, cells of household contacts infected with M.tb and TB cases were isolated and cocultured with CD3(+) T cells.. Our results demonstrate an increased presence of MDSCs after recent M.tb infection and disease. We confirm their suppression of CD4(+) T-cell function, including reduced cytokine responses and inhibition of CD4(+) T-cell proliferation. Only MDSCs from TB cases reduced T-cell activation, altered T-cell trafficking, and suppressed CD8(+) T-cell functions. M.tb-expanded MDSCs were associated with significantly higher IL-1β, IL-6, IL-8, granulocyte colony-stimulating factor, and monocyte chemotactic protein-1, and reduced granulocyte-macrophage colony-stimulating factor and macrophage inflammatory protein-1 beta levels in coculture.. These data reveal that innate MDSCs are induced not only during active TB at similar levels as found in cancer, but also in healthy individuals after recent exposure to M.tb. These cells diminish protective T-cell responses and may contribute to the inability of hosts to eradicate the infection and add to the subsequent development of TB disease.

Topics: CD4-Positive T-Lymphocytes; CD8-Positive T-Lymphocytes; Cytokines; Flow Cytometry; Granulocyte Colony-Stimulating Factor; Granulocyte-Macrophage Colony-Stimulating Factor; Humans; Interleukin-1beta; Interleukin-6; Interleukin-8; Lung Neoplasms; Mycobacterium Infections; Mycobacterium tuberculosis; Myeloid Cells; T-Lymphocytes; Tuberculin Test; Tuberculosis

Hodgkin's disease (HD) shows rare neoplastic Hodgkin and Reed-Sternberg cells embedded in an abundant reactive infiltrate containing, among other cell types, neutrophilic granulocytes. Interleukin (IL)-8 is chemotactic for neutrophils. The expression of IL-8 was tested by in situ hybridization with 35S-labeled IL-8-specific RNA probes on 38 cases of HD. Reactive lesions, non-Hodgkin's lymphomas of B and T phenotype, and Langerhans cell histiocytosis served as controls. IL-8 expression was observed in Hodgkin and Reed-Sternberg cells in 3 of 33 cases of classical HD and in reactive cells in 20 of 33 HD cases as evidenced by combined isotopic in situ hybridization and immunohistology for the demonstration of cell-type-characteristic antigens or enzyme histochemistry for chloroacetate esterase. IL-8-positive cells were more numerous in cases of nodular sclerosing HD as compared with the mixed cellularity histotype (P = 0.01). The number of IL-8-positive cells and the density of neutrophils were positively correlated (P < 0. 01). In 5 cases of lymphocyte-predominant HD, IL-8 expression was not displayed. Non-Hodgkin's lymphoma cases contained IL-8 transcripts only in 1 of 23 cases in sparse reactive cells. In 4 of 7 cases of Langerhans cell histiocytosis, IL-8-specific signals were displayed in S100-negative cells. In conclusion, IL-8 expression in HD is largely confined to reactive cells and associated with infiltration by neutrophils. Elaboration of other cytokines by Hodgkin and Reed-Sternberg cells and reactive cells may explain the frequent expression of this cytokine in HD, particularly in the nodular sclerosing type.

Topics: Cell Count; Histiocytosis, Langerhans-Cell; Hodgkin Disease; Humans; Interleukin-8; Lymphoma, Non-Hodgkin; Mycobacterium Infections; Neutrophils; Palatine Tonsil