Bacteriophage therapy for the treatment of Mycobacterium tuberculosis infections in humanized mice

The continuing emergence of new strains of antibiotic-resistant bacteria has renewed interest in phage therapy; however, there has been limited progress in applying phage therapy to multi-drug resistant Mycobacterium tuberculosis (Mtb) infections. In this study, we show that bacteriophage strains D29 and DS6A can efficiently lyse Mtb H37Rv in 7H10 agar plates. However, only phage DS6A efficiently kills H37Rv in liquid culture and in Mtb-infected human primary macrophages. We further show in subsequent experiments that, after the humanized mice were infected with aerosolized H37Rv, then treated with DS6A intravenously, the DS6A treated mice showed increased body weight and improved pulmonary function relative to control mice. Furthermore, DS6A reduces Mtb load in mouse organs with greater efficacy in the spleen. These results demonstrate the feasibility of developing phage therapy as an effective therapeutic against Mtb infection.

HIV-Differentiated Metabolite N-Acetyl-L-Alanine Dysregulates Human Natural Killer Cell Responses to Mycobacterium tuberculosis Infection

Mycobacterium tuberculosis (Mtb) has latently infected over two billion people worldwide (LTBI) and caused ~1.6 million deaths in 2021. Human immunodeficiency virus (HIV) co-infection with Mtb will affect the Mtb progression and increase the risk of developing active tuberculosis by 10-20 times compared with HIV- LTBI+ patients. It is crucial to understand how HIV can dysregulate immune responses in LTBI+ individuals. Plasma samples collected from healthy and HIV-infected individuals were investigated using liquid chromatography-mass spectrometry (LC-MS), and the metabolic data were analyzed using the online platform Metabo-Analyst. ELISA, surface and intracellular staining, flow cytometry, and quantitative reverse-transcription PCR (qRT-PCR) were performed using standard procedures to determine the surface markers, cytokines, and other signaling molecule expressions. Seahorse extra-cellular flux assays were used to measure mitochondrial oxidative phosphorylation and glycolysis. Six metabolites were significantly less abundant, and two were significantly higher in abundance in HIV+ individuals compared with healthy donors. One of the HIV-upregulated metabolites, N-acetyl-L-alanine (ALA), inhibits pro-inflammatory cytokine IFN-γ production by the NK cells of LTBI+ individuals. ALA inhibits the glycolysis of LTBI+ individuals' NK cells in response to Mtb. Our findings demonstrate that HIV infection enhances plasma ALA levels to inhibit NK-cell-mediated immune responses to Mtb infection, offering a new understanding of the HIV-Mtb interaction and providing insights into the implication of nutrition intervention and therapy for HIV-Mtb co-infected patients.

HIV-differentiated metabolite N-Acetyl-L-Alanine dysregulates human natural killer cell responses to Mycobacterium tuberculosis infection

Background

Mycobacterium tuberculosis ( Mtb ) has latently infected over two billion people worldwide (LTBI) and causes 1.8 million deaths each year. Human immunodeficiency virus (HIV) co-infection with Mtb will affect the Mtb progression and increase the risk of developing active tuberculosis by 10-20 times compared to the HIV-LTBI+ patients. It is crucial to understand how HIV can dysregulate immune responses in LTBI+ individuals.

Methods

Plasma samples collected from healthy and HIV-infected individuals were investigated by liquid chromatography-mass spectrometry (LC-MS), and the metabolic data were analyzed using an online platform Metabo-Analyst. ELISA, surface and intracellular staining, flow cytometry, quantitative reverse transcription PCR (qRT-PCR) were performed by standard procedure to determine the surface markers, cytokines and other signaling molecule expression. Seahorse extra cellular flux assays were used to measure the mitochondrial oxidative phosphorylation and glycolysis.

Results

Six metabolites were significantly less abundant, and two were significantly higher in abundance in HIV+ individuals compared to healthy donors. One of the HIV-upregulated metabolites, N-Acetyl-L-Alanine (ALA), inhibits pro-inflammatory cytokine IFN-□ production by NK cells of LTBI+ individuals. ALA inhibits glycolysis of LTBI+ individuals' NK cells in response to Mtb .

Conclusions

Our findings demonstrate that HIV infection enhances plasma ALA levels to inhibit NK cell-mediated immune responses to Mtb infection, offering a new understanding of the HIV- Mtb interaction and providing the implication of nutrition intervention and therapy for HIV- Mtb co-infected patients.

Bacteriophage therapy for the treatment of Mycobacterium tuberculosis infections in humanized mice

The continuing emergence of new strains of antibiotic-resistant bacteria has renewed interest in phage therapy; however, there has been limited progress in applying phage therapy to multi-drug resistant Mycobacterium tuberculosis (Mtb) infections. In this study, we tested three bacteriophage strains for their Mtb-killing activities and found that two of them efficiently lysed Mtb H37Rv in 7H10 agar plates. However, only phage DS6A efficiently killed H37Rv in liquid culture and in Mtb-infected human primary macrophages. In subsequent experiments, we infected humanized mice with aerosolized H37Rv, then treated these mice with DS6A intravenously to test its in vivo efficacy. We found that DS6A treated mice showed increased body weight and improved pulmonary function relative to control mice. Furthermore, DS6A reduced Mtb load in mouse organs with greater efficacy in the spleen. These results demonstrated the feasibility of developing phage therapy as an effective therapeutic against Mtb infection.

Metabolites enhance innate resistance to human Mycobacterium tuberculosis infection

To determine the mechanisms that mediate resistance to Mycobacterium tuberculosis (M. tuberculosis) infection in household contacts (HHCs) of patients with tuberculosis (TB), we followed 452 latent TB infection-negative (LTBI-) HHCs for 2 years. Those who remained LTBI- throughout the study were identified as nonconverters. At baseline, nonconverters had a higher percentage of CD14+ and CD3-CD56+CD27+CCR7+ memory-like natural killer (NK) cells. Using a whole-transcriptome and metabolomic approach, we identified deoxycorticosterone acetate as a metabolite with elevated concentrations in the plasma of nonconverters, and further studies showed that this metabolite enhanced glycolytic ATP flux in macrophages and restricted M. tuberculosis growth by enhancing antimicrobial peptide production through the expression of the surface receptor sialic acid binding Ig-like lectin-14. Another metabolite, 4-hydroxypyridine, from the plasma of nonconverters significantly enhanced the expansion of memory-like NK cells. Our findings demonstrate that increased levels of specific metabolites can regulate innate resistance against M. tuberculosis infection in HHCs of patients with TB who never develop LTBI or active TB.

Histone Deacetylase-2 Controls IL-1β Production through the Regulation of NLRP3 Expression and Activation in Tuberculosis Infection

Histone deacetylases (HDACs) are critical immune regulators. However, their roles in interleukin-1β (IL-1β) production remain unclear. By screening 11 zinc-dependent HDACs with chemical inhibitors, we found that HDAC1 inhibitor, 4-(dimethylamino)-N-[6-(hydroxyamino)-6-oxohexyl]-benzamide (DHOB), enhanced IL-1β production by macrophage and dendritic cells upon TLR4 stimulation or Mycobacterium tuberculosis infection through IL-1β maturation via elevated NLRP3 expression, increased cleaved caspase-1, and enhanced ASC oligomerization. DHOB rescued defective IL-1β production by dendritic cells infected with M. tuberculosis with ESAT-6 deletion, a virulence factor shown to activate NLRP3 inflammasome. DHOB increased IL-1β production and NLRP3 expression in a tuberculosis mouse model. Although DHOB inhibited HDAC activities of both HDAC1 and HDAC2 by direct binding, knockdown of HDAC2, but not HDAC1, increased IL-1β production and NLRP3 expression in M. tuberculosis-infected macrophages. These data suggest that HDAC2, but not HDAC1, controls IL-1β production through NLRP3 inflammasome activation, a mechanism with a significance in chronic inflammatory diseases including tuberculosis.

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HDAC1 inhibitor, DHOB, increased IL-1β production via NLRP3 inflammasome activation

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DHOB suppressed deacetylase activities of both HDAC1 and HDAC2 by direct interaction

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Deletion of HDAC2, but not HDAC1, increased IL-β production by increased NLRP3 expression

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DHOB increased IL-1β and NLRP3 expression in a mouse model of TB infection

Early IL-17A production helps establish Mycobacterium intracellulare infection in mice

Nontuberculous mycobacteria (NTM) infection is common in patients with structural lung damage. To address how NTM infection is established and causes lung damage, we established an NTM mouse model by intranasal inoculation of clinical isolates of M. intracellulare. During the 39-week course of infection, the bacteria persistently grew in the lung and caused progressive granulomatous and fibrotic lung damage with mortality exceeding 50%. Lung neutrophils were significantly increased at 1 week postinfection, reduced at 2 weeks postinfection and increased again at 39 weeks postinfection. IL-17A was increased in the lungs at 1–2 weeks of infection and reduced at 3 weeks postinfection. Depletion of neutrophils during early (0–2 weeks) and late (32–34 weeks) infection had no effect on mortality or lung damage in chronically infected mice. However, neutralization of IL-17A during early infection significantly reduced bacterial burden, fibrotic lung damage, and mortality in chronically infected mice. Since it is known that IL-17A regulates matrix metalloproteinases (MMPs) and that MMPs contribute to the pathogenesis of pulmonary fibrosis, we determined the levels of MMPs in the lungs of M. intracellulare-infected mice. Interestingly, MMP-3 was significantly reduced by anti-IL-17A neutralizing antibody. Moreover, in vitro data showed that exogenous IL-17A exaggerated the production of MMP-3 by lung epithelial cells upon M. intracellulare infection. Collectively, our findings suggest that early IL-17A production precedes and promotes organized pulmonary M. intracellulare infection in mice, at least in part through MMP-3 production.

To determine how nontuberculous mycobacteria (NTM) infection is established and how NTM disease progresses, we established a chronic NTM mouse model by intranasal inoculation of M. intracellulare, one of the most frequently isolated strains in NTM patients. The bacteria persistently grew in the lungs and caused fibrotic lung damage with over 50% mortality over 39 weeks. Neutrophils and IL-17A rapidly increased in the lung during early (1–2 weeks) infection, and neutrophils reappeared at 39 weeks postinfection. Depletion of neutrophils during early (0–2 weeks) and chronic (32–34 weeks) infection had no effect on mortality or lung damage in chronically infected mice. Neutralization of IL-17A during early (0–2 weeks) infection significantly reduced mortality, bacterial burden, fibrotic lung damage, and lung matrix metalloproteinase (MMP)-3 at 39 weeks postinfection. Exogenous IL-17A exaggerated the production of MMP-3, but not MMP-9, by lung epithelial cells upon M. intracellulare infection. This study demonstrates that early IL-17A production contributes to established M. intracellulare infection in mice.

Phage Display-Derived Peptide for the Specific Binding of SARS-CoV-2

Beginning from the end of 2019, the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic swept all over the world and is still afflicting the whole global population. Given that the vaccine-manufacturing ability is limited and the virus can evolve quickly, vaccination alone may not be able to end the pandemic, thus developing fast and accurate diagnoses and effective therapeutics will always be unmet needs. Phage display peptide library has been used in screening antigen-specific peptides for the invention of novel mimic receptors/ligands. Here, we report that a 12-mer phage display peptide library has been screened against the SARS-CoV-2 receptor-binding domain (RBD), and five of the screened peptides show binding ability with the RBD protein by the enzyme-linked immune sorbent assay. The surface plasmon resonance assay further demonstrates that peptide no. 1 can specifically bind to SARS-CoV-2 RBD with a binding affinity constant (K d) of 5.8 μM. Transmission electron microscopy coupled with a magnetic bead assay further confirms that the screened peptide can specifically bind the inactivated SARS-CoV-2 virus. This SARS-CoV-2-specific peptide holds great promise as a new bioreceptor/ligand for the rapid and accurate detection of SARS-CoV-2.

Defective expansion and function of memory like natural killer cells in HIV+ individuals with latent tuberculosis infection

Purpose

Tuberculosis (TB) is the leading cause of infectious disease related mortality, and only 10% of the infected individuals develop active disease. The likelihood of progression of latent tuberculosis infection (LTBI) to active TB disease is high in HIV infected individuals. Identification of HIV+ individuals at risk would allow treating targeted population, facilitating completion of therapy for LTBI and prevention of TB development. NK cells have an important role in T cell independent immunity against TB, but the exact role of NK cell subsets in LTBI and HIV is not well characterized.

Methods

In this study, we compared the expansion and function of memory like NK cells from HIV-LTBI+ individuals and treatment naïve HIV+LTBI+ patients in response to Mtb antigens ESAT-6 and CFP-10.

Results

In freshly isolated PBMCs, percentages of CD3^-CD56⁺ NK cells were similar in HIV+LTBI+ patients and healthy HIV-LTBI+ individuals. However, percentages of CD3^-CD56⁺CD16⁺ NK cells were higher in healthy HIV-LTBI+ individuals compared to HIV+LTBI+ patients. HIV infection also inhibited the expansion of memory like NK cells, production of IL-32α, IL-15 and IFN-γ in response to Mtb antigens in LTBI+ individuals.

Conclusion

We studied phenotypic, functional subsets and activation of memory like-NK cells during HIV infection and LTBI. We observed that HIV+LTBI+ patients demonstrated suboptimal NK cell and monocyte interactions in response to Mtb, leading to reduced IL-15, IFN-γ and granzyme B and increased CCL5 production. Our study highlights the effect of HIV and LTBI on modulation of NK cell activity to understand their role in development of interventions to prevent progression to TB in high risk individuals.

Reduced thyroxine production in young household contacts of tuberculosis patients increases active tuberculosis disease risk

In the current study, we followed 839 household contacts (HHCs) of tuberculosis (TB) patients for 2 years and identified the factors that enhanced the development of TB. Fourteen of the 17 HHCs who progressed to TB were in the 15- to 30-year-old age group. At baseline (the “0“ time point, when all the individuals were healthy), the concentration of the thyroid hormone thyroxine (T4) was lower, and there were increased numbers of Tregs in PBMCs of TB progressors. At baseline, PBMCs from TB progressors stimulated with early secretory antigenic target 6 (ESAT-6) and 10 kDa culture filtrate antigen (CFP-10) produced less IL-1α. Thyroid hormones inhibited Mycobacterium tuberculosis (Mtb) growth in macrophages in an IL-1α–dependent manner. Mtb-infected Thra1^PV/+ (mutant thyroid hormone receptor) mice had increased mortality and reduced IL-1α production. Our findings suggest that young HHCs who exhibit decreased production of thyroid hormones are at high risk of developing active TB disease.

Mycobacterium tuberculosis stimulates IL-1β production by macrophages in an ESAT-6 dependent manner with the involvement of serum amyloid A3

Despite its critical roles in immune responses against tuberculosis infection and immune pathology, the molecular details of interleukin (IL)-1β production in tuberculosis infection remain elusive. To explore IL-1β production in tuberculosis infection, we infected mouse bone marrow-derived macrophages (BMDM) with Mycobacterium tuberculosis (Mtb) H37Rv, its early secreted antigenic target protein of 6 kDa (ESAT-6) gene deletion (H37Rv:Δ3875) or complemented strain (H37Rv:Δ3875C) and evaluated IL-1β production. H37Rv induced significantly increased IL-1β production by BMDMs compared to non-infected BMDMs. In contrast, H37Rv:Δ3875 induced significantly less mature IL-1β production despite eliciting comparable levels of pro-IL-1β and IL-8 from BMDMs compared to H37Rv and H37Rv:Δ3875C. Blocking either NLRP3 or K⁺ efflux diminished H37Rv-induced IL-1β production by BMDMs. Infection of mice intranasally with H37Rv:Δ3875 induced less IL-1β production in the lungs compared with H37Rv. Intranasal delivery of ESAT-6 but not CFP10 induced production of IL-1β in mouse lungs and RNA-Seq analysis identified serum amyloid A (SAA) 3 as one of the highly expressed genes in mouse lungs. Infection of mice with H37Rv but not H37Rv:Δ3875 induced expression of lung SAA3 mRNA and protein, consistent with the effect of intranasal delivery of ESAT-6. Silencing SAA3 reduced Mtb-induced IL-1β production by BMDMs. We conclude that SAA3 plays critical role in ESAT-6 dependent IL-1β production by macrophages in tuberculosis infection.

Histone deacetylase-1 controls IL-1β production through the regulation of NLRP3 expression and activation in tuberculosis infection

Although IL-1b is required for the protection against Mycobacterium tuberculosis (Mtb) infection, its uncontrolled production is associated with chronic inflammation and lung damage in Tuberculosis. Epigenetic effector molecules histone deacetylases (HDACs) play critical roles in tumorigenesis and immune regulation, however their roles in IL-1β production remain unexplored. Initial screening of 11 variants of HDAC with their chemical inhibitors identified that inhibition of HDAC-1 promotes secretion of IL-1β and increases the lysine acetylation of histone H3 by primary macrophages and dendritic cells (DCs) in response to LPS/CD40L, IFN-γ stimulation or Mtb infection without affecting pro-IL-1β and IL-6. Inhibition of NLRP3 or Caspase-1 reversed this effect of HDAC-1 inhibition without affecting cell viability, implying the involvement of NLRP3 inflammasome activation. Consistently, HDAC-1 inhibition further elevated the expression of both mRNA and protein of NLRP3 in macrophages and DCs under stimulation and increased levels of cleaved Caspase-1 and mature IL-1β in the culture supernatants. Mtb infection and stimulation with LPS/CD40L of these cells induced increased expression and phosphorylation of HDAC-1 and increased HDAC-1 activity in cell lysates which was suppressed by HDAC-1 inhibitor. Treatment of low dose aerosol Mtb-infected mice with HDAC-1 inhibitor increased IL-1β in mice lungs without affecting IL-6 production. These suggest that HDAC-1 controls IL-1β maturation via regulation of NLRP3 expression and activation, thus suggesting a novel mechanism for the regulation of IL-1β, a major inflammatory cytokine in tuberculosis infection and other inflammatory diseases.

NK cells exhibit memory and stem cell like features after Zika virus infection

Natural Killer (NK) cells are the components of innate immune system known for their role in virus infection and tumor immunity. Their importance is appreciated from the case studies where lack of NK cells leads to life threatening herpes virus infection and increased host susceptibility to certain cancers. Recent development in the NK field have opened a new frontier bringing to light that innate immune cells can demonstrate memory features too. In line with the above-mentioned development, we report NK memory cell generation post Zika virus infection in mice. Our detailed transcriptomics, epigenetic and functional analysis revealed that CD27+ memory like NK cell that developed post Zika virus infection exhibited stem cell like properties and shared gene signatures with memory CD8 T cells, stem cells and stem like T cells from chronic infection and cancer. We termed these cells as “NK memory stem cells” which also possessed greater antiviral function when adoptively transferred into Zika infected mice. We next performed single cell RNA-seq on NK memory stem cells and identified multiple subpopulations which differed in gene expression profiles. Our work revealed NK cells with memory like and stemness features that are helpful in fighting viral infection. We also detected subpopulations in NK memory stem cells and efforts are ongoing to evaluate the role of these NK subpopulations in antiviral immunity.

Memory like NK cells display stem cell like properties after Zika virus infection

NK cells have been shown to display adaptive traits such as memory formation akin to T and B lymphocytes. Here we show that Zika virus infection induces memory like NK cells that express CD27. Strikingly, these cells exhibit stem-like features that include expansion capacity, self-renewal pathway, differentiation into effector cells, longer telomeres and gene signature associated with hematopoietic stem cell (HSC) progenitors. This subset shared transcriptional and epigenetic changes with memory CD8 T cells, stem cells and stem like T cells. These NK cells with memory and stem cell features, which we term "NK memory stem cells", demonstrated greater antiviral potential than CD27- or naïve CD27+ NK when adoptively transferred to Zika infected mice. Our results also suggest a role for the transcription factor TCF-1 in memory and stemness features of this NK subset. This study defines a unique TCF1hi CD27+ NK subset with memory capacity and stem cell features that play a role in antiviral immunity.

Defective macrophage mediated immune responses in HIV negative Mycobacterium avium complex (MAC) patients with pulmonary diseases

Mycobacterium avium complex (MAC), which includes M. avium and M. intracellulare, is widely distributed in the environment, and exposure to these organisms is inevitable. Despite widespread exposure, the disease is unusual in immunocompetent hosts. During the past two decades, MAC represents a common cause of progressive pulmonary disease in the United States. To gain insight into the immunologic factors that predispose persons to MAC infections, we evaluated the immune responses of HIV negative (-) MAC patients with pulmonary diseases in comparison to their healthy HIV− household contacts (HHCs). Whole blood from 20 pairs of HIV− MAC patients and healthy HHCs was immunolabeled, and the percentages of various immune cell populations were determined by flow cytometry. Among various cell types, MAC patients have significantly lower ratio of monocytes compared to healthy HHCs. In 11 pairs of HIV− MAC patients and healthy HHCs, peripheral blood mononuclear cells (PBMC) of MAC patients produced lower levels of interleukin (IL)-10 and IL-1 family (IL-1β, IL-18, IL-1α) out of 34 cytokines and chemokines measured by multiplex ELISA upon MAC stimulation, compared with that of healthy HHCs. In two MAC patients, PBMC restricted MAC growth less efficiently compared with their healthy HHCs despite there was no deficiency in restricting MAC growth by monocyte derived macrophages of six MAC patients. Our findings suggest that the interactions among various immune cells are required for efficient clearance of MAC by macrophages in MAC patients. Studies are underway to pinpoint the nature of defective immune responses that prevents efficient clearance of MAC by macrophages of MAC patients.

Phenotypic and functional characterization of lung resident lymphocytes of BCG vaccinated mice

Mycobacterium tuberculosis (Mtb) remains to be a leading cause of morbidity and mortality, causing an estimated 1.3 million deaths annually. It is known that intranasal Mycobacterium bovis Bacille Calmette-Guérin (BCG) vaccination in mice has proven to provide superior protection against pulmonary TB, as compared to parenterally administered BCG. In the current study, we determined the phenotype and function of lung-resident lymphocytes in intranasally BCG vaccinated mice. C57BL/6 mice were vaccinated intranasally with live-attenuated BCG and lung lymphocytes were isolated and stained for immunophenotyping via flow cytometry at 24, 48, and 72 hours post-vaccination. At 48 hours post-vaccination, we have observed an expansion of CD69+, CD103+, and CD69+CD103+ lymphocytes within the lung of vaccinated mice. Studies are underway to determine the phenotype and function of lung-resident lymphocyte subsets and their expansion capacity at three months after BCG vaccination and Mtb infection.

Ornithine-A urea cycle metabolite enhances autophagy and controls Mycobacterium tuberculosis infection

Alveolar macrophages (AMs) are the first cells encountered by TB pathogen and serve as the primary defense against Mycobacterium tuberculosis (Mtb) in the lungs. Studies have shown that liver macrophages (Kupffer cells; KCs) can control Mtb growth but, it is not clear how KCs completely eliminate mycobacterial infections. Thus, identification of these mechanisms will facilitate the development of immunomodulatory strategies to boost AM-mediated immunity to Mtb. In the current study, we compared Mtb growth in murine AMs, peritoneal (PMs), liver macrophages (Kupffer cells; KCs) and bone marrow-derived monocytes (BDMs). KCs restricted Mtb growth more efficiently than all other macrophages and monocytes despite equivalent infections. Differences in Mtb growth restriction were not due to differences in cytokine production, expression of Toll-like receptors 2 and 4, M1/M2 paradigm or apoptosis. We provide evidence that the enhanced autophagy efficiently restricts Mtb growth in KCs using flow cytometry, western blot, RT-PCR and confocal microscopy. A metabolomic comparison of Mtb-infected macrophages by liquid chromatography mass spectrometry indicated that ornithine (VIP=1.8) and imidazole (VIP=1.6) were two top-scoring metabolites found in Mtb-infected KCs and that acetylcholine was top-scoring in Mtb-infected AMs. Ornithine and imidazole inhibited Mtb growth in AMs by enhancing AMPK mediated autophagy whereas imidazole directly killed Mtb by reducing cytochrome P450 activity. Intranasal delivery of ornithine or imidazole or together restricted Mtb growth in Mtb-infected mouse lungs. Our study demonstrates that the metabolic differences in Mtb-infected AMs and KCs leads to differences in the restriction of Mtb growth.

BCG vaccination reduces the mortality of Mycobacterium tuberculosis-infected type 2 diabetes mellitus (T2DM) mice through the induction of CXCR3+ T-regulatory cells

Diabetes is a significant risk factor for the development of active tuberculosis. In this study, we used mouse model of Streptozotocin/Nicotinamide (STZ/NA) induced non-obese type 2 diabetes mellitus (T2DM) to determine the effect of prior BCG vaccination on survival and immune responses to Mycobacterium tuberculosis (Mtb) infection. We found that at 6–7 months post-Mtb infection, 90% of the Mtb-infected T2DM mice died, whereas only 50% of BCG-vaccinated T2DM-Mtb-infected mice died. Moreover, 40% of the PBS-treated uninfected T2DM mice and 30% of the uninfected BCG-vaccinated T2DM mice died, whereas all uninfected and infected nondiabetic mice survived. BCG vaccination was less effective in reducing the lung bacterial burden of Mtb infected T2DM mice compared to Mtb-infected non-diabetic mice, however it reduced immunopathology of lung tissues. Further, we found increased survival of BCG vaccinated Mtb infected T2DM mice is associated with 2-fold expansion of IL-13 producing CXCR3+ T-regulatory cells as measured by flow cytometry, qRT-PCR and confocal microscopy. We also found that prior BCG vaccination restored the immunosuppressive function of T-regulatory cells of Mtb-infected T2DM mice and reduced inflammation. IL-13 producing T-regulatory cells of BCG vaccinated Mtb-infected T2DM mice converted proinflammatory M1 macrophages (iNOS) to anti-inflammatory M2 macrophage (Arg1) phenotype to suppress the inflammation. In contrast, anti-IL-13R antibody inhibited the conversion of macrophages from M1 to the M2 phenotype and enhanced the inflammatory cytokines (IL-6 and TNF-α) production. Our findings suggest a novel role for BCG in preventing excessive inflammation and mortality in T2DM mice infected with Mtb.

A rho GDP dissociation inhibitor produced by a subset of T-regulatory cells enhances mitophagy in Mycobacterium tuberculosis infected human macrophages

Previously, we found that a Rho GDP dissociation inhibitor (D4GDI), produced by apoptotic T regulatory cells inhibit Mycobacterium tuberculosis (Mtb) growth in human macrophages through reactive oxygen species (ROS) mediated IL-1β production. Mitochondria is an important source of ROS and critical for antibacterial properties. In the current study, we evaluated the effects of D4GDI on mitochondrial homeostasis and anti-microbial scheme during Mtb infection. Recombinant D4GDI (rD4GDI) treatment of Mtb infected human macrophages enhanced the accumulation of LC3B protein on the mitochondria and triggered mitophagy. rD4GDI treatment significantly enhanced the expression of a mitophagy receptor BCL2 and adenovirus E1B 19-kDa-interacting protein 3-like (BNIP3L). BNIP3L siRNA inhibited rD4GDI dependent accumulation of LC3B protein on the mitochondria and enhanced Mtb growth in human macrophages. Further we found that rD4GDI treatment of Mtb infected macrophages induces the expression of antimicrobial peptide phospholipase family protein phospholipase A2 group VII (PLA2G7). Further studies are underway to determine the interactions between BNIP3L, PLA2G7 and mitophagy in rD4GDI treated macrophages to inhibit Mtb growth in human macrophages.

BCG vaccination reduces the mortality of Mycobacterium tuberculosis-infected type 2 diabetes mellitus mice

Diabetes is a significant risk factor for the development of active tuberculosis. In this study, we used a mouse model of type 2 diabetes mellitus (T2DM) to determine the effect of prior Bacillus Calmette-Guérin (BCG) vaccination on immune responses to Mycobacterium tuberculosis (Mtb) infection. We found that, at 6-7 months after Mtb infection, 90% of the Mtb-infected T2DM mice died, whereas only 50% of BCG-vaccinated T2DM-Mtb-infected mice died. Moreover, 40% of the PBS-treated uninfected T2DM mice and 30% of the uninfected BCG-vaccinated T2DM mice died, whereas all uninfected and infected nondiabetic mice survived. BCG vaccination was less effective in reducing the lung bacterial burden of Mtb-infected T2DM mice compared with Mtb-infected nondiabetic mice. BCG vaccination significantly reduced lung inflammation in Mtb-infected T2DM mice compared with that of unvaccinated T2DM mice infected with Mtb. Furthermore, reduced mortality of BCG-vaccinated Mtb-infected T2DM mice is associated with expansion of IL-13-producing CXCR3+ Tregs in the lungs of Mtb-infected T2DM mice. Recombinant IL-13 and Tregs from BCG-vaccinated Mtb-infected T2DM mice converted proinflammatory M1 macrophages to antiinflammatory M2 macrophages. Our findings suggest a potentially novel role for BCG in preventing excess inflammation and mortality in T2DM mice infected with Mtb.

IL-22 produced by type 3 innate lymphoid cells (ILC3s) reduces the mortality of type 2 diabetes mellitus (T2DM) mice infected with Mycobacterium tuberculosis

Previously, we found that pathological immune responses enhance the mortality rate of Mycobacterium tuberculosis (Mtb)-infected mice with type 2 diabetes mellitus (T2DM). In the current study, we evaluated the role of the cytokine IL-22 (known to play a protective role in bacterial infections) and type 3 innate lymphoid cells (ILC3s) in regulating inflammation and mortality in Mtb-infected T2DM mice. IL-22 levels were significantly lower in Mtb-infected T2DM mice than in nondiabetic Mtb-infected mice. Similarly, serum IL-22 levels were significantly lower in tuberculosis (TB) patients with T2DM than in TB patients without T2DM. ILC3s were an important source of IL-22 in mice infected with Mtb, and recombinant IL-22 treatment or adoptive transfer of ILC3s prolonged the survival of Mtb-infected T2DM mice. Recombinant IL-22 treatment reduced serum insulin levels and improved lipid metabolism. Recombinant IL-22 treatment or ILC3 transfer prevented neutrophil accumulation near alveoli, inhibited neutrophil elastase 2 (ELA2) production and prevented epithelial cell damage, identifying a novel mechanism for IL-22 and ILC3-mediated inhibition of inflammation in T2DM mice infected with an intracellular pathogen. Our findings suggest that the IL-22 pathway may be a novel target for therapeutic intervention in T2DM patients with active TB disease.

Interleukin-21 Regulates Natural Killer Cell Responses During Mycobacterium tuberculosis Infection

Background

In the current study, we determined the effects of interleukin (IL)-21 on human natural killer (NK) cells and monocyte responses during Mycobacterium tuberculosis (Mtb) infection.

Methods

We found that Mtb stimulated CD4+ and NK T cells from healthy individuals with latent tuberculosis infection (LTBI+) are major sources of IL-21. CD4+ cells from tuberculosis patients secreted less IL-21 than did CD4+ cells from healthy LTBI+ individuals. Interleukin-21 had no direct effect on Mtb-stimulated monocytes.

Results

Interleukin-21-activated NK cells produced interferon (IFN)-γ, perforin, granzyme B, and granulysin; lysed Mtb-infected monocytes; and reduced Mtb growth. Interleukin-21-activated NK cells also enhanced IL-1β, IL-18, and CCL4/macrophage-inflammatory protein (MIP)-1β production and reduced IL-10 production by Mtb-stimulated monocytes. Recombinant IL-21 (1) inhibited Mtb growth, (2) enhanced IFN-γ, IL-1β, IL-18, and MIP-1β, and (3) reduced IL-10 expression in the lungs of Mtb-infected Rag2 knockout mice.

Conclusions

These findings suggest that activated T cells enhance NK cell responses to lyse Mtb-infected human monocytes and restrict Mtb growth in monocytes through IL-21 production. Interleukin-21-activated NK cells also enhance the immune response by augmenting IL-1β, IL-18, and MIP-1β production and reducing IL-10 production by monocytes in response to an intracellular pathogen.

IL-22 reduces the mortality of type 2 diabetes mellitus (T2DM) mice infected with Mycobacterium tuberculosis

IL-22 play an important role in protective immune responses against bacterial infections including Mtb and maintains homeostasis by regulating excess inflammation. IL-22 can also regulate glucose homeostasis, suggesting IL-22 pathway as a novel target for therapeutic intervention. Previously, we developed a mouse model of type 2 diabetes mellitus (T2DM) and found that pathological immune response enhances mortality of Mycobacterium tuberculosis (Mtb) infected T2DM mice. In the current study, we determined the role of IL-22 during Mtb infection in T2DM mice. We found innate lymphoid 3 cells (ILC3) are the major source for IL-22 and IL- 22 production was significantly reduced in the lungs and serum of T2DM mice infected with Mtb. Recombinant IL- 22 or adoptive transfer of ILC3 cells prolonged the survival of Mtb infected T2DM mice. Recombinant IL-22 prevented neutrophil accumulation near alveoli, reduced the serum insulin level and improved the lipid metabolism. Recombinant IL-22 also prevented neutrophil-mediated epithelial cell damage by inhibiting elastase production by neutrophils. Further, we found serum IL-22 levels were significantly less in tuberculosis (TB) patients with T2DM compared to TB patients without T2DM. Our findings suggest that IL-22 produced by ILC3 cells is essential to inhibit excess inflammation, epithelial cell damage in T2DM mice infected with Mtb.

Prior Bacillus Calmette-Guérin (BCG) vaccination ameliorates the pathogenesis of Type 2 diabetes mellitus mice infected with Mycobacterium tuberculosis

Previously, we found experimentally induced type 2 diabetes mellitus (T2DM) mice are highly susceptible to Mycobacterium tuberculosis (Mtb) infection. In the present study, we determined whether prior BCG vaccination has any effect on the susceptibility of T2DM mice infected with Mtb. C57BL/6 mice were vaccinated with BCG or treated with PBS, three months later some mice were induced with T2DM and after another month fifty percent of all groups of mice were challenged with Mtb. All Mtb infected T2DM mice and 40% of uninfected T2DM mice died within 10 months. In contrast, only 40% of Mtb infected BCG vaccinated T2DM mice and 20% of uninfected BCG vaccinated T2DM mice died. Lung bacterial burden was significantly less in Mtb infected BCG vaccinated T2DM mice compared to PBS treated Mtb infected mice. Pro and anti-inflammatory cytokine levels were significantly high in the lungs of Mtb infected BCG vaccinated T2DM mice compared to all other groups of vaccinated and PBS treated mice infected with Mtb. Our findings suggest that prior BCG vaccination protects Mtb infected mice from T2DM induced pathogenesis. Studies are underway to determine the BCG induced mechanism/s those protect T2DM mice challenged with Mtb.

Liver macrophages controls Mycobacterium tuberculosis growth by enhancing autophagy

Alveolar macrophages are the first cells to come in contact with TB pathogen in lung, but unable to eliminate Mycobacterium tuberculosis (M. tb) completely and serves as niche. In the current study, we compared M. tb growth and cytokine production by murine alveolar and liver macrophages. We found three-fold higher CFU in alveolar macrophages compared to liver macrophages (5 ± 1.7 × 106 vs. 1.776 ± 0.5 ×106 CFU) indicating that liver macrophages are more efficient in inhibiting M. tb growth. In contrast, M. tb H37Rv infected alveolar and liver macrophages produced equal amounts of TNF-α, IL-6, IL-10 & IL-1β. There is no significant difference in the apoptosis and M1/M2 paradigm of M. tb infected alveolar and liver macrophages. Flow cytometry analysis revealed the percentage of LC-3B+ M. tb infected liver macrophages were two-fold higher compared to percentage of LC-3B+ M. tb infected alveolar macrophage. This was confirmed by real time PCR. We also noted distinctly enhanced LC-3B puncta formation in infected liver macrophages as examined by confocal microscopy. We found significantly enhanced M. tb CFU in liver macrophages transfected with LC-3B, ATG-5, ATG-7 and Beclin-1 siRNA compared to liver macrophages transfected with control siRNA (p<0.01; 0.006; 0.01&0.002) respectively. Our results suggest that autophagy is involved in better restriction of M. tb growth by liver macrophages. Studies are underway to compare metabolic changes of control and M. tb H37Rv infected alveolar and liver macrophages and in vivo relevance to our current findings using mouse model of M. tb infection.

Down regulation of RANTES in pleural site is associated with inhibition of antigen specific response in tuberculosis

Tuberculosis is the most common infectious reason for death and a major cause of pleural effusion globally. To understand the role of chemokines in trafficking of cells during TB pleurisy, we studied the responses to MTB, Ag85A in cells from pleural fluids and peripheral blood. Patients with TB pleural effusions, malignant effusions and asymptomatic healthy controls were enrolled. High expression (p < 0.05) of IP-10, MCP-1, MIG, IL-8, IFN-γ and IL-23 were observed in pleural fluids of TB patients compared to their plasma where expression of RANTES was significantly higher (p < 0.05). On specific stimulation of PFMCs with Ag85A, expression of RANTES was significantly lower in TB compared to NTB patients. We also observed increased expression of T regs and PD1 on CD8+T cells in PFMC of TB patients. Though some of the inflammatory chemokine/cytokines were up-regulated in pleura of TB patients, antigenic stimulation failed to induce them indicating poor antigenic responses at the site. Low expression of RANTES might be a reason for decreased trafficking of cells to the site and dissemination of infection into pleural site. The pattern of RANTES expression in pleural fluid vs serum is interesting. The observations necessitate further studies to investigate the levels of RANTES for its potential biological relevance in TB immunity and its use as a biomarker for diagnosis of pleural TB.

Alcohol enhances type 1 interferon-α production and mortality in young mice infected with Mycobacterium tuberculosis

In the current study, we used a mouse model and human blood samples to determine the effects of chronic alcohol consumption on immune responses during Mycobacterium tuberculosis (Mtb) infection. Alcohol increased the mortality of young mice but not old mice with Mtb infection. CD11b+Ly6G+ cells are the major source of IFN-α in the lungs of Mtb-infected alcohol-fed young mice, and IFN-α enhances macrophage necroptosis in the lungs. Treatment with an anti-IFNAR-1 antibody enhanced the survival of Mtb-infected alcohol-fed young mice. In response to Mtb, peripheral blood mononuclear cells (PBMCs) from alcoholic young healthy individuals with latent tuberculosis infection (LTBI) produced significantly higher amounts of IFN-α than those from non-alcoholic young healthy LTBI+ individuals and alcoholic and non-alcoholic old healthy LTBI+ individuals. Our study demonstrates that alcohol enhances IFN-α production by CD11b+Ly6G+ cells in the lungs of young Mtb-infected mice, which leads to macrophage necroptosis and increased mortality. Our findings also suggest that young alcoholic LTBI+ individuals have a higher risk of developing active TB infection.

Chronic alcohol consumption modulates the host immune defense mechanism(s) and makes the host susceptible to various fungal, viral and bacterial infections, including Mycobacterium tuberculosis (Mtb). However, limited information is available about the mechanisms involved in alcohol-mediated host susceptibility to Mtb and other intracellular bacterial infections. In the current study, we fed control and alcohol diets to young and old mice and determined the mortality rates and the immune mechanisms involved in host susceptibility to Mtb infection. We found that alcohol increases the mortality of young mice but not old mice infected with Mtb. The increased mortality in alcohol-fed Mtb-infected young mice was due to IFN-α production by CD11b+Ly6G+ cells. We also found that PBMCs from young alcoholic individuals with latent tuberculosis infection (LTBI) produced significantly higher amounts of IFN-α than those from young non-alcoholic, old alcoholic and old non-alcoholic LTBI+ individuals. Our findings suggest that young alcoholic LTBI+ individuals have a higher risk of developing active TB infection. Our studies provide the first evidence that chronic alcohol consumption induces IFN-α production in young Mtb-infected mice and increases their mortality rates. Further characterization of CD11b+Ly6G+ cells and delineation of the mechanisms through which alcohol enhances IFN-α production in Ly6G+ cells during Mtb infection will facilitate the development of therapies for alcoholic individuals with latent and active Mtb.

IL-17 and IL-22 production in HIV+ individuals with latent and active tuberculosis

BACKGROUND

IL-17 and IL-22 cytokines play an important role in protective immune responses against Mycobacterium tuberculosis (Mtb) infection. Information on the production of these cytokines and the factors that regulate their production in the context of human immunodeficiency virus (HIV) and latent tuberculosis infection (LTBI) or active tuberculosis disease (ATB) is limited. In the current study, we compared the production of these two cytokines by PBMC of HIV-LTBI+ and HIV + LTBI+ individuals in response to Mtb antigens CFP-10 (culture filtrate protein) and ESAT-6 (Early Secretory Antigenic Target). We also determined the mechanisms involved in their production.

METHODS

We cultured Peripheral Blood Mononuclear Cells (PBMCs) from HIV- individuals and HIV+ patients with latent tuberculosis and active disease with CFP-10 and ESAT-6. Production of IL-17, IL-22 and PD1 (Programmed Death 1), ICOS (Inducible T-cell Costimulator), IL-23R and FoxP3 (Forkhead box P3) expression on CD4+ T cells was measured.

RESULTS

In response to Mtb antigens CFP-10 and ESAT-6, freshly isolated PBMCs from HIV+ LTBI+ and HIV+ active TB patients produced less IL-17 and IL-22 and more IL-10, expressed less IL-23R, and more PD1 and expanded to more FoxP3+ cells. Active TB infection in HIV+ individuals further inhibited antigen specific IL-17 and IL-22 production compared to those with LTBI. Neutralization of PD1 restored IL-23R expression, IL-17 and IL-22 levels and lowered IL-10 production and reduced expansion of FoxP3 T cells.

CONCLUSIONS

In the current study we found that increased PD1 expression in HIV + LTBI+ and HIV+ active TB patients inhibits IL-17, IL-22 production and IL-23R expression in response to Mtb antigens CFP-10 and ESAT-6.

Defective MyD88 and IRAK4 but not TLR-2 expression in HIV+ individuals with latent tuberculosis infection

HIV infection markedly increases the likelihood of latent tuberculosis infection progressing to active TB. Information on expression of TLR-2, myeloid differentiation factor (MyD88), IL-1R- associated kinase-4 (IRAK4) and nuclear factor kappa B (NF-kB) in HIV+LTBI+ and HIV+ patients with active TB disease is limited. We found significantly higher percentages of CD14+TLR2+ cells in PBMCs of HIV+LTBI+ patients compared to HIV-LTBI+ individuals. γ-irradiated Mtb was unable to induce MyD88, IRAK4 expression and IL-1β, MCP-1, IP-10 production in HIV+LTBI+ patients. Pleural fluids from HIV+TB+ patients had low IL-1β, MCP-1, IP-10 and high IL-10, TNF-α production. γ-irradiated Mtb stimulated CD14+ cells from HIV+TB+ patients had low IL-1β, MCP-1, IP-10 production and MyD88, IRAK4 and similar NF-kB expression compared to those from of HIV-TB+ patients. Our results suggest defective MyD88, IRAK4 but not NF-kB inhibit IL-1β, MCP-1 and IP-10 production by CD14+ cells of HIV+ individuals with LTBI and active TB disease in peripheral blood and at the site of disease.

ALCOHOL ENHANCES TYPE 1 INTERFERON-α AND MORTALITY OF YOUNG MICE INFECTED WITH Mycobacterium tuberculosis

In the current study, we determined the effects of chronic alcohol consumption on the mortality of young and old mice and immune responses during Mycobacterium tuberculosis (Mtb) infection. Eighty percent of Mtb H37Rv infected alcohol-fed young mice died in five months compared to twenty-five percent in Mtb infected alcohol-fed old mice. There is no significant difference in lung bacterial burden of control and alcohol diet fed young and old mice. IFN-α levels were significantly higher in the lungs of Mtb infected alcohol-fed young mice and treatment with anti-IFNAR-1 antibody enhanced their survival. There are significantly higher numbers of CD11b+Ly6G+ neutrophils in the lungs of Mtb infected alcoholic young mice compared to Mtb infected alcohol-fed old mice and Mtb infected control diet-fed young mice. CD11b+Ly6G+ neutrophils are the major source of IFN-α in Mtb-infected alcohol-fed young mice and IFN-α enhanced the expression of RIP-1 and RIP-3 molecules, which are known to be involved in necroptosis. Alcohol-fed old Mtb infected mice and Mtb infected control diet-fed old and young mice expressed low level of IFN-α and RIP-1 and RIP-3 in their lungs. In response to Mtb stimulation, peripheral blood mononuclear cells (PBMC) from young healthy alcoholic individuals with latent tuberculosis infection (LTBI) produced significantly higher amounts of IFN-α compared to non-alcoholic young, alcoholic and non-alcoholic old healthy LTBI+ individuals. Our findings demonstrate that in Mtb infected young mice, alcohol enhances CD11b+Ly6G+ neutrophil infiltration in lungs and excess IFN-α production by neutrophils causes lung macrophage necroptosis and enhanced mortality.

Type 2 diabetes mellitus induces TNFR1 mediated necroptotic cell death of mice alveolar macrophages infected with Mycobacterium tuberculosis

Previously, we developed a mouse model of type 2 diabetes mellitus (T2DM) using streptozotocin and nicotinamide and found that T2DM mice are susceptible to Mycobacterium tuberculosis (Mtb) infection. We also found that alveolar macrophages from T2DM mice were more permissive to Mtb growth ex vivo compared to non-diabetic controls. In the current study, we determined the defective mechanisms that make T2DM mice alveolar macrophages more susceptible to Mtb infection. Mtb infected alveolar macrophages from T2DM mice produced more TNF-α (973.8 ± 13.3 pg/ml vs. 614.6 ± 27.2 pg/ml, p&lt;0.003) and less apoptotic (4.7 ± 1.8% vs. 28.6 ± 2.3%, p&lt;0.001) compared to Mtb infected non-diabetic control mice. Mtb infected alveolar macrophages from T2DM mice expressed higher levels of TNFR1 (12.8 ± 0.5 vs. 2.09 ± 0.01, p&lt;0.001) and markers of necroptosis RIPK1 (11.5 ± 0.57 vs. 2.94 ± 0.20, p&lt;0.002), RIPK3 (16.1 ± 0.58 vs. 2.89 ± 0.2, p&lt;0.001) and MLKL (9.2 ± 0.56 vs. 1.58 ± 0.72, p&lt;0.02) compared to Mtb infected alveolar macrophages from non-diabetic control mice as determined by real-time PCR. This finding was again proved by Western blot and confocal microscopy. Anti-TNFR1 antibody treatment of alveolar macrophages from T2DM mice before or after Mtb infection reduced RIPK1, RIPK3 and MLKL expression as determined by RT-PCR. Our findings demonstrate that T2DM induces necroptosis of alveolar macrophages upon Mtb infection. Enhanced TNFR1 signaling in T2DM mice alveolar macrophages is responsible for enhanced necroptosis. We are also determining the subpopulations of T2DM mice alveolar macrophages that express higher levels of TNFR1 upon Mtb infection. Studies are underway to determine the in vivo relevance of our current findings to Mtb growth in T2DM mice.

Kupffer cells restricts Mycobacterium tuberculosis growth better than alveolar macrophages

Kupffer cells protect liver from bacterial infections. In the current study, we compared Mycobacterium tuberculosis (M.tb) growth and cytokine production by mice kupffer cells and alveolar macrophages. M.tb H37Rv infected kupffer cells and alveolar macrophages produced equal amounts of TNF-α, IL-6, IL-10 & IL-1β. In contrast, kupffer cells restricted M.tb growth better than alveolar macrophages (1 ± 0.346×106 CFU vs. 4 ± 0.916×106 CFU, p&lt;0.03). There is no significant difference in the apoptosis of M.tb infected kupffer cells and alveolar macrophages. In contrast, M.tb infected kupffer cells expressed significant higher amounts of autophagy molecules LC-3B, ATG-7, ATG-5 and Beclin-1 (p&lt;0.005, p&lt;0.002, p&lt;0.0032 & p&lt;0.004 respectively) compared to M.tb infected alveolar macrophages as determined by real-time PCR. This was confirmed by Western blot and confocal microscopy. Our results suggest autophagy is involved in better restriction of M.tb growth by kupffer cells. Prime PCR analysis for 35 intracelluar signaling molecules those are involved in autophagy as well as in cytoskeleton indicated that M.tb infected kupffer cells significantly express higher levels of VASP (Vasodilator-stimulated phosphoprotein), RhoA (Ras homolog gene family member A) and Arp3 (Actin–related protein 3) genes (two fold, p&lt;0.01, p&lt;0.02&p&lt;0.02 respectively) compared to M.tb infected alveolar macrophages. Studies are underway 1. To confirm whether autophagy is involved in better restriction of M.tb growth in kupffer cells. 2. Determine the role of cytoskeleton proteins those are involved in enhanced autophagy and M.tb growth inhibition in kupffer cells. 3. Determining in vivo relevance to our current findings using mouse model of M.tb infection.

IL-21 Receptor Signaling Is Essential for Optimal CD4+ T Cell Function and Control of Mycobacterium tuberculosis Infection in Mice

In this study, we determined the role of IL-21R signaling in Mycobacterium tuberculosis infection, using IL-21R knockout (KO) mice. A total of 50% of M. tuberculosis H37Rv-infected IL-21R KO mice died in 6 mo compared with no deaths in infected wild type (WT) mice. M. tuberculosis-infected IL-21R KO mice had enhanced bacterial burden and reduced infiltration of Ag-specific T cells in lungs compared with M. tuberculosis-infected WT mice. Ag-specific T cells from the lungs of M. tuberculosis-infected IL-21R KO mice had increased expression of T cell inhibitory receptors, reduced expression of chemokine receptors, proliferated less, and produced less IFN- γ, compared with Ag-specific T cells from the lungs of M. tuberculosis-infected WT mice. T cells from M. tuberculosis-infected IL-21R KO mice were unable to induce optimal macrophage responses to M. tuberculosis. This may be due to a decrease in the Ag-specific T cell population. We also found that IL-21R signaling is associated with reduced expression of a transcriptional factor Eomesodermin and enhanced functional capacity of Ag-specific T cells of M. tuberculosis-infected mice. The sum of our findings suggests that IL-21R signaling is essential for the optimal control of M. tuberculosis infection.

IL-21-dependent expansion of memory-like NK cells enhances protective immune responses against Mycobacterium tuberculosis

Natural killer (NK) cells are traditionally considered as innate cells, but recent studies suggest that NK cells can distinguish antigens, and that memory NK cells expand and protect against viral pathogens. Limited information is available about the mechanisms involved in memory-like NK cell expansion, and their role in bacterial infections and vaccine-induced protective immune responses. In the current study, using a mouse model of tuberculosis (TB) infection, we found that interferon-gamma producing CD3-NKp46+CD27+KLRG1+ memory-like NK cells develop during Bacille Calmette-Guérin vaccination, expand, and provide protection against challenge with Mycobacterium tuberculosis (M. tb). Using antibodies, short interfering RNA and gene-deleted mice, we found that expansion of memory-like NK cells depends on interleukin 21 (IL-21). NKp46+CD27+KLRG1+ NK cells expanded in healthy individuals with latent TB infection in an IL-21-dependent manner. Our study provides first evidence that memory-like NK cells survive long term, expansion depends on IL-21, and involved in vaccine-induced protective immunity against a bacterial pathogen.

c-Jun N-terminal kinase 1 defective CD4+CD25+FoxP3+ cells prolong pancreatic allograft survival in type 1 diabetic mice

CD4+CD25+FoxP3+ cells (Tregs) inhibit inflammatory immune responses to allografts. Here we found that co-transplantation of allogeneic pancreatic islets with Tregs that are defective in JNK1 signaling prolong the islet allograft survival in the liver parenchyma of the T1D mice. Deletion of the JNK1 in Tregs increased the expression of anti-apoptotic molecules Mcl-1, Bcl-Xl and anti-inflammatory cytokine IL-10 production. JNK1−/− Tregs persist for long period in the transplanted liver and prolong the islet allograft survival compared to WT Tregs. JNK1−/− Tregs demonstrated improved control of allo-inflammation compared to WT Tregs in the T1D liver upon co-transplantation. JNK1−/− Tregs specifically inhibit IL-17 and IL-21 medited alloimmune response. Inhibition of alloimmune response by JNK1−/− Tregs independently mediated through the LAG3 on its cell surface and the increased production of IL-10. Our study identifies a novel role of JNK1 signaling in the Tregs function and co-transplantation of JNK1 deficient Tregs enhances the islet allograft survival in the liver parenchyma of T1D mice.

A TLR9 agonist promotes IL-22-dependent pancreatic islet allograft survival in type 1 diabetic mice

Pancreatic islet transplantation is a promising potential cure for type 1 diabetes (T1D). Islet allografts can survive long term in the liver parenchyma. Here we show that liver NK1.1+ cells induce allograft tolerance in a T1D mouse model. The tolerogenic effects of NK1.1+ cells are mediated through IL-22 production, which enhances allograft survival and increases insulin secretion. Increased expression of NKG2A by liver NK1.1+ cells in islet allograft-transplanted mice is involved in the production of IL-22 and in the reduced inflammatory response to allografts. Vaccination of T1D mice with a CpG oligonucleotide TLR9 agonist (ODN 1585) enhances expansion of IL-22-producing CD3-NK1.1+ cells in the liver and prolongs allograft survival. Our study identifies a role for liver NK1.1+ cells, IL-22 and CpG oligonucleotides in the induction of tolerance to islet allografts in the liver parenchyma.

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.

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

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 (TF(Δ) ) 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.

IL-6 regulates pro- and anti-inflammatory cytokine production and mortality of Mycobacterium tuberculosis infected type 2 diabetic mice (INC2P.418)

In this study, to determine whether diabetic (DM) mice are susceptible to Mycobacterium tuberculosis (Mtb) infection, we developed experimentally induced diabetes in wild type C57BL/6 mice with streptozotocin & nicotinamide. We then infected non-DM and DM mice with Mtb H37Rv by aerosol. Around 50% of Mtb infected DM (p=0.05) and 25% of uninfected DM (p=0.07) mice died in 5 to 6 months compared to no deaths in infected control mice. Six months after Mtb infection, there was a statistically significant but marginal increase in bacterial burden in the lungs of Mtb infected DM mice compared to non-DM infected mice (3.1 ± 0.4 x106 vs 0.9 ± 0.1 x 106, p=0.001) suggesting increased mortality was not due to increased bacterial burden. Real time PCR analysis of Mtb infected DM lungs indicated significantly increased pro- and anti-inflammatory cytokine gene expression compared to uninfected DM and infected control mice, including increased levels of IL-6 mRNA. Anti-IL-6 antibody treatment of Mtb infected DM mice enhanced the survival (100% vs 60% survival in isotype control antibody treated, p=0.02) and reduced pro- and anti-inflammatory cytokine production. Dendritic cells (DC), but not other immune cells were the major source for IL-6 in Mtb infected DM mice. NK cells of Mtb infected DM mice further enhanced IL-6 production by autologous DCs. Our results suggest NK-DC interaction enhance IL-6 production which drives the immune pathology and mortality of Mtb infected diabetic mice

CD4+CD25+Foxp3+ cells from JNK-/- mice prolong pancreatic allograft survival in type 1 diabetic mice (TRAN2P.970)

In the current study we asked whether modified CD4+CD25+FoxP3+ regulatory T-cells (T-regs) can induce long term allograft tolerance. Pancreatic islets from BALB/c mice survived in a type 1 diabetic C57BL/6 mice (recipient mice) liver up to 18-21 days (n=5). Preloading islets with T-regs from WT (wild type) C57BL/6 mice, enhanced survival up to 37 days (N=5 and p = 0.003). Further preloading islets with T-regs from JNK1-/- mice (C57BL/6 background) enhanced survival up to 107 days (N=5 and p = 0.002). In contrast preloading islets with T-regs from FAS-/- (C57BL/6 background) did not enhance islet survival beyond 45 days. T-cell receptor stimulation of T-regs from JNK1-/- mice produced significant high amount of IL-10 (14.67 ± 2.784 vs 3.803 ± 0.8325, p = 0.009) and TGF-β (27.93 ± 7.563 vs 9.920 ± 1.212, p = 0.05) compared to T-regs from WT mice. Preloading islets with T-regs from JNK1-/- mice reduced IL-1β (30.91 ± 2.41 vs 16.13 ± 2.76; p = 0.003), TNF-α (3.802 ± 0.69 vs 1.888 ± 0.26; p = 0.03) IL-17 (24.82 ± 4.07 vs 4.708 ± 1.57; p = 0.0017). Studies are underway to determine the JNK1-/-T-regs mediated mechanisms involved in prolongation of allograft survival.

IL-21 is essential for the optimal control of Mycobacterium tuberculosis infection (INC2P.416)

IL-21 is a Th17 cytokine and is known for its anti-tumor and anti-viral effects. In the current study using IL-21receptor (IL-21r-/-) and IL-21 knockout (IL-21-/-) mice, we determined the role of IL-21 and IL-21r in Mycobacterium tuberculosis (M. tb) infection. Around 50% of M. tb H37Rv infected IL-21r-/- mice died in six months compared to no deaths in infected control mice. M. tb infected IL-21r-/- mice have enhanced bacterial burden (7.3 ± 1.0 x 106 vs. 0.7 ± 0.08 x 106,p&lt;0.001), reduced infiltration of CD4+ T-cells (0.9 ± 0.01 x 105 vs. 1.4 ± 0.03 x 105, p&lt;0.001), increased frequency of PD-1,2B4,CD160 & EOMES (transcription factor) and reduced frequency of IL-12Rβ positive T-cells in lungs compared to wild type M. tb infected mice. T-cells from M. tb infected IL-21-/- mice proliferated less, produced less IFN- γ in response γ-irradiated M. tb and expressed more EOMES compared to wild type M. tb infected mice, and this was reversed by recombinant IL-21. EOMES siRNA increased IFN- γ production (p=0.007) and IL-12Rβ expression by T-cells of M. tb infected wild type mice. We also found T-cells from M. tb infected IL-21-/- mice enhance production of IFN-α (p=0.01), IL-10 (p=0.01), reduce IL-12 (p=0.02) and IL-1β (p=0.04) expression by M. tb infected macrophages and were unable control bacterial growth in macrophages compared to T-cells from M. tb infected wild type mice. The sums of our findings suggest that IL-21 and IL-21r are essential for optimal control of M. tb in mice

Liver NK1.1 cells and IL-22 promote pancreatic islets allograft survival in type 1 diabetic mice (TRAN2P.969)

We determined the role of liver NK1.1 cells in allograft survival. Pancreatic islets from BALB/c mice survived in a type 1 diabetic C57BL/6 mice liver up to 15-21 days (n=5, p=0.001). Anti NK1.1 but not isotype control antibody treatment of type 1 diabetic C57BL/6 mice before and after pancreatic islet transfer rejected graft within 3 days (n=5, p=0.001). Anti-NK1.1 antibody treatment enhanced IL-1β (45.13 ± 5.9 vs 94.25 ± 5.5; p = 0.0003), TNF-α (4.746 ± 2.4 vs 11.92 ± 1.8; p = 0.047) and IFN-γ (2.714 ± 0.45 vs 4.344 ± 0.4; p = 0.036) and inhibited IL-22 (24.82 ± 4.07 vs 11.01 ± 2.186; p = 0.01) gene expression by liver lymphocytes of recipient mice. NK1.1 cells are major source of IL-22 in islets recipient mice liver and anti-IL-22 antibody treatment of recipient mice reduced allograft survival to 6-9 days compared to 18-21 days in isotype control antibody treated mice. Recombinant IL-22 but not IFN-γ enhanced insulin production by pancreatic islets of BALB/c mice (102.0 ± 22.65 vs 33.41 ± 12.07; p = 0.03) and enhanced expression of genes Reg2, Reg3a and Reg3g involved in islet survival. Further studies indicated that immunization and challenge of type 1 diabetic C57BL/6 mice with TLR9 agonist can enhance IL-22 production by NK1.1 cells and prolongs pancreatic allograft survival from 15 days to 45 days. The sum of our studies suggests that IL-22 produced by liver NK1.1 cells enhance allograft survival and TLR9 agonist can be used to prolong pancreatic allograft survival.

A Rho GDP dissociation inhibitor produced by apoptotic T cells inhibits growth of Mycobacterium tuberculosis (INC2P.415)

In the current study, we found that a subpopulation of apoptotic T-cells (CD4+CD25+ and 85% Foxp3+) from persons with latent tuberculosis (TB) infection, inhibits growth of M. tuberculosis (M. tb) in human monocyte-derived macrophages (MDMs) from 16.5 ± 1.2 x 106 vs 2.2 ± 1.1 x 106 CFU (p=0.001). Analysis of culture supernatants from T-cells by 2D gel electrophoresis and LC MS/MS indicated that a soluble factor, Rho GDP dissociation inhibitor (D4GDI), produced by apoptotic T-cells is responsible for this inhibition of M.tb growth in MDMs and in mice. M. tb-expanded CD4+CD25+Foxp3+D4GDI+ cells do not produce IL-10, TGF-β and IFN-γ. D4GDI inhibited growth of M. tb from 10.4 ± 1.1 x 106 vs 2.8 ± 0.6 x 106 CFU (p&lt;0.001) and D4GDI siRNA reversed T-cells-dependent M. tb growth inhibition in MDMs from 1.8 ± 0.3 x 106 to 5.5 ± 1 x 106 CFU (p=0.001). D4GDI enhanced production of IL-1β (43 ± 33 to 193 ± 104 pg/ml, p=0.02), TNF-α (88 ± 126 to 129 ± 111 pg/ml, p=0.03) and ROS production and enhanced apoptosis of M. tb-infected MDMs to inhibit M.tb growth. D4GDI was concentrated at the site of disease in TB patients, with higher levels detected in pleural fluid than in serum. However, in response to M. tb, PBMC from TB patients produced less D4GDI than PBMC from persons with LTBI (13.7 ± 9.3 vs. 40.6 ± 3.2, p=0.02). Our study provides the first evidence that a subpopulation of T-cells enhances immunity to M. tb, and that production of D4GDI by this subpopulation inhibits M. tb growth.

A rho GDP dissociation inhibitor produced by apoptotic T-cells inhibits growth of Mycobacterium tuberculosis

In this study, we found that a subpopulation of CD4⁺CD25⁺ (85% Foxp3⁺) cells from persons with latent tuberculosis infection (LTBI) inhibits growth of M. tuberculosis (M. tb) in human monocyte-derived macrophages (MDMs). A soluble factor, Rho GDP dissociation inhibitor (D4GDI), produced by apoptotic CD4⁺CD25⁺ (85% Foxp3⁺) cells is responsible for this inhibition of M. tb growth in human macrophages and in mice. M. tb-expanded CD4⁺CD25⁺Foxp3⁺D4GDI⁺ cells do not produce IL-10, TGF-β and IFN-γ. D4GDI inhibited growth of M. tb in MDMs by enhancing production of IL-1β, TNF-α and ROS, and by increasing apoptosis of M. tb-infected MDMs. D4GDI was concentrated at the site of disease in tuberculosis patients, with higher levels detected in pleural fluid than in serum. However, in response to M. tb, PBMC from tuberculosis patients produced less D4GDI than PBMC from persons with LTBI. M. tb-expanded CD4⁺CD25⁺ (85% Foxp3⁺) cells and D4GDI induced intracellular M. tb to express the dormancy survival regulator DosR and DosR-dependent genes, suggesting that D4GDI induces a non-replicating state in the pathogen. Our study provides the first evidence that a subpopulation of CD4⁺CD25⁺ (85% Foxp3⁺) cells enhances immunity to M. tb, and that production of D4GDI by this subpopulation inhibits M. tb growth.

Most people who are infected with Mycobacterium tuberculosis (M. tb) have latent tuberculosis infection (LTBI) with protective immunity. Patients with active tuberculosis have severe disease and ineffective immunity. Understanding how LTBI individuals control infection without developing disease provides important insight into the mechanisms of protective immunity against tuberculosis, and this information is essential for development of an effective vaccine. It is known that a lymphocyte population called T-cells contributes significantly to protective immunity against tuberculosis infection. In the current study, using human and murine models of M. tb infection, we found that a soluble factor, Rho GDP dissociation inhibitor (D4GDI), produced by a subpopulation of T-cells (CD4⁺CD25⁺Foxp3⁺) inhibits M. tb growth. We also found that D4GDI induces M. tb genes that are expressed during the non-replicative state. Our results suggest that D4GDI has a previously undescribed positive effect on immunity by enhancing host antimicrobial activity. These findings also may aid in understanding the factors that induce LTBI. Further, this information will facilitate development of improved vaccines and immunotherapeutic strategies to prevent and treat tuberculosis, respectively.

Phosphorylated STAT3 and PD-1 regulate IL-17 production and IL-23 receptor expression in Mycobacterium tuberculosis infection

We studied the factors that regulate IL-23 receptor expression and IL-17 production in human tuberculosis infection. Mycobacterium tuberculosis (M. tb)-stimulated CD4(+) T cells from tuberculosis patients secreted less IL-17 than did CD4(+) T cells from healthy tuberculin reactors (PPD(+) ). M. tb-cultured monocytes from tuberculosis patients and PPD(+) donors expressed equal amounts of IL-23p19 mRNA and protein, suggesting that reduced IL-23 production is not responsible for decreased IL-17 production by tuberculosis patients. Freshly isolated and M. tb-stimulated CD4(+) T cells from tuberculosis patients had reduced IL-23 receptor and phosphorylated STAT3 (pSTAT3) expression, compared with cells from PPD(+) donors. STAT3 siRNA reduced IL-23 receptor expression and IL-17 production by CD4(+) T cells from PPD(+) donors. Tuberculosis patients had increased numbers of PD-1(+) T cells compared with healthy PPD(+) individuals. Anti-PD-1 antibody enhanced pSTAT3 and IL-23R expression and IL-17 production by M. tb-cultured CD4(+) T cells of tuberculosis patients. Anti-tuberculosis therapy decreased PD-1 expression, increased IL-17 and IFN-γ production and pSTAT3 and IL-23R expression. These findings demonstrate that increased PD-1 expression and decreased pSTAT3 expression reduce IL-23 receptor expression and IL-17 production by CD4(+) T cells of tuberculosis patients.

Interleukin 22 inhibits intracellular growth of Mycobacterium tuberculosis by enhancing calgranulin A expression

Previously, we found that interleukin 22 (IL-22) inhibits intracellular growth of Mycobacterium tuberculosis in human monocyte-derived macrophages (MDMs). In the current study, we determined the mechanisms underlying these effects. We found that W7, a phagolysosomal fusion inhibitor, abrogates IL-22-dependent M. tuberculosis growth inhibition in MDMs, suggesting that IL-22 acts through enhanced phagolysosomal fusion. Our microarray analysis indicated that recombinant IL-22 (rIL-22) enhances the expression of an intracellular signaling molecule, calgranulin A. This was confirmed by real-time polymerase chain reaction, Western blot, and confocal microscopy. Calgranulin A small interfering RNA (siRNA) abrogated rIL-22-dependent growth inhibition of M. tuberculosis in MDMs. IL-22 enhanced Rab7 expression and downregulated Rab14 expression of M. tuberculosis-infected MDMs, and these effects were reversed by calgranulin A siRNA. These results suggest that M. tuberculosis growth inhibition by IL-22 depends on calgranulin A and enhanced phagolysosomal fusion, which is associated with increased Rab7 and reduced Rab14 expression.