Tissue factor expression by myeloid cells contributes to protective immune response against Mycobacterium tuberculosis infection: Innate Immunity

Tissue Factor (TF) is a transmembrane glycoprotein that plays an essential role in hemostasis by activating coagulation. TF is also expressed by monocytes/macrophages as part of the innate immune response to infections. In the current study, we determined the role of TF expressed by myeloid cells during Mycobacterium tuberculosis (M. tb) infection by using mice lacking the TF gene in myeloid cells (TFΔ) and human monocyte derived macrophages (MDMs). We found that during M. tb infection, a deficiency of TF in myeloid cells was associated with reduced inducible nitric oxide synthase (iNOS) expression, enhanced arginase 1 (Arg1) expression, enhanced IL-10 production and reduced apoptosis in infected macrophages, which augmented M. tb growth. Our results demonstrate that a deficiency of TF in myeloid cells promotes M2 like phenotype in M .tb infected macrophages. A deficiency in TF expression by myeloid cells was also associated with reduced fibrin deposition and increased matrix metalloproteases (MMP)-2 and MMP-9 mediated inflammation in M. tb infected lungs. Our studies demonstrate that TF expressed by myeloid cells has newly recognized abilities to polarize macrophages and to regulate M. tb growth

NK-CD11c+ Cell Crosstalk in Diabetes Enhances IL-6-Mediated Inflammation during Mycobacterium tuberculosis Infection

In this study, we developed a mouse model of type 2 diabetes mellitus (T2DM) using streptozotocin and nicotinamide and identified factors that increase susceptibility of T2DM mice to infection by Mycobacterium tuberculosis (Mtb). All Mtb-infected T2DM mice and 40% of uninfected T2DM mice died within 10 months, whereas all control mice survived. In Mtb-infected mice, T2DM increased the bacterial burden and pro- and anti-inflammatory cytokine and chemokine production in the lungs relative to those in uninfected T2DM mice and infected control mice. Levels of IL-6 also increased. Anti-IL-6 monoclonal antibody treatment of Mtb-infected acute- and chronic-T2DM mice increased survival (to 100%) and reduced pro- and anti-inflammatory cytokine expression. CD11c+ cells were the major source of IL-6 in Mtb-infected T2DM mice. Pulmonary natural killer (NK) cells in Mtb-infected T2DM mice further increased IL-6 production by autologous CD11c+ cells through their activating receptors. Anti-NK1.1 antibody treatment of Mtb-infected acute-T2DM mice increased survival and reduced pro- and anti-inflammatory cytokine expression. Furthermore, IL-6 increased inflammatory cytokine production by T lymphocytes in pulmonary tuberculosis patients with T2DM. Overall, the results suggest that NK-CD11c+ cell interactions increase IL-6 production, which in turn drives the pathological immune response and mortality associated with Mtb infection in diabetic mice

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Figure S6. IL-6 is responsible for the increased pro-inflammatory cytokine production in type 2 diabetic patients with pulmonary tuberculosis. Blood from 20 pulmonary tuberculosis patients with T2DM and 20 pulmonary tuberculosis patients without diabetes was obtained. Whole blood was cultured with 10 µg/ml of purified protein derivative (PPD) as indicated in the methods section. A representative flow cytometric contour plot showing the frequency of cells expressing IFN-, TNF-, IL-17 and IL-2 is shown

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Figure S2. Type 2 diabetes enhances pro- and anti-inflammatory responses during Mtb infection. Control and T2DM mice were infected with 50-100 CFU of aerosolized Mtb H37Rv. One and six months p.i., lung homogenates were collected from uninfected control and diabetic mice and from Mtb-infected control and diabetic mice and subjected to multiplex ELISA to determine the various cytokines and chemokines. Mean values, p-values and SEs are shown. *P < 0.05, **P < 0.01, ***P < 0.001

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Figure S1. Mtb infection enhances the dissemination of bacteria in T2DM. Control and T2DM mice were infected with 50-100 CFU of aerosolized Mtb H37Rv A & B. Bacterial burden in the spleen and liver six months post-infection. C & D. Random blood glucose levels and body weight were measured at monthly intervals for up to 6 months

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Figure S5 Natural killer and dendritic cell interaction enhanced IL-6 production in Mtb-infected type 2 diabetic mice. Control and T2DM mice were infected with 50-100 CFU of aerosolized Mtb H37Rv. Six months p.i., lungs from Mtb-infected control and T2DM mice were isolated and formalin-fixed. Paraffin-embedded tissue sections were prepared and confocal microscopy analysis was performed to determine NK (pink), IL-6+ (green) and dendritic (red) cell co-localization. Scale bar: 20 µm (yellow bar) and 5 µm (white bar). Representative images of staining pattern of three independent experiments, each with three per group were shown