Early pulmonary cytokine and chemokine responses in mice immunized with three different vaccines against Mycobacterium tuberculosis determined by PCR array

DNA and RNA vaccines against tuberculosis: a scoping review of human and animal studies

Introduction

To comprehensively identify and provide an overview of in vivo or clinical studies of nucleic acids (NA)-based vaccines against TB we included human or animal studies of NA vaccines for the prevention or treatment of TB and excluded in vitro or in silico research, studies of microorganisms other than M. tuberculosis, reviews, letters, and low-yield reports.

Methods

We searched PubMed, Scopus, Embase, selected Web of Science and ProQuest databases, Google Scholar, eLIBRARY.RU, PROSPERO, OSF Registries, Cochrane CENTRAL, EU Clinical Trials Register, clinicaltrials.gov, and others through WHO International Clinical Trials Registry Platform Search Portal, AVMA and CABI databases, bioRxiv, medRxiv, and others through OSF Preprint Archive Search. We searched the same sources and Google for vaccine names (GX-70) and scanned reviews for references. Data on antigenic composition, delivery systems, adjuvants, and vaccine efficacy were charted and summarized descriptively.

Results

A total of 18,157 records were identified, of which 968 were assessed for eligibility. No clinical studies were identified. 365 reports of 345 animal studies were included in the review. 342 (99.1%) studies involved DNA vaccines, and the remaining three focused on mRNA vaccines. 285 (82.6%) studies used single-antigen vaccines, while 48 (13.9%) used multiple antigens or combinations with adjuvants. Only 12 (3.5%) studies involved multiepitope vaccines. The most frequently used antigens were immunodominant secretory antigens (Ag85A, Ag85B, ESAT6), heat shock proteins, and cell wall proteins. Most studies delivered naked plasmid DNA intramuscularly without additional adjuvants. Only 4 of 17 studies comparing NA vaccines to BCG after M. tuberculosis challenge demonstrated superior protection in terms of bacterial load reduction. Some vaccine variants showed better efficacy compared to BCG.

Systematic review registration

https://osf.io/, identifier F7P9G.

Biomarkers to identify Mycobacterium tuberculosis infection among borderline QuantiFERON results

BACKGROUND

Screening for tuberculosis (TB) infection often includes QuantiFERON-TB Gold Plus (QFT) testing. Previous studies showed that two-thirds of patients with negative QFT results just below the cut-off, so-called borderline test results, nevertheless had other evidence of TB infection. This study aimed to identify a biomarker profile by which borderline QFT results due to TB infection can be distinguished from random test variation.

METHODS

QFT supernatants of patients with a borderline (≥0.15 and <0.35 IU·mL-1), low-negative (<0.15 IU·mL-1) or positive (≥0.35 IU·mL-1) QFT result were collected in three hospitals. Bead-based multiplex assays were used to analyse 48 different cytokines, chemokines and growth factors. A prediction model was derived using LASSO regression and applied further to discriminate QFT-positive Mycobacterium tuberculosis-infected patients from borderline QFT patients and QFT-negative patients RESULTS: QFT samples of 195 patients were collected and analysed. Global testing revealed that the levels of 10 kDa interferon (IFN)-γ-induced protein (IP-10/CXCL10), monokine induced by IFN-γ (MIG/CXCL9) and interleukin-1 receptor antagonist in the antigen-stimulated tubes were each significantly higher in patients with a positive QFT result compared with low-negative QFT individuals (p<0.001). A prediction model based on IP-10 and MIG proved highly accurate in discriminating patients with a positive QFT (TB infection) from uninfected individuals with a low-negative QFT (sensitivity 1.00 (95% CI 0.79-1.00) and specificity 0.95 (95% CI 0.74-1.00)). This same model predicted TB infection in 68% of 87 patients with a borderline QFT result.

CONCLUSIONS

This study was able to classify borderline QFT results as likely infection-related or random. These findings support additional laboratory testing for either IP-10 or MIG following a borderline QFT result for individuals at increased risk of reactivation TB.

Characterization of cytokine profile to distinguish latent tuberculosis from active tuberculosis and healthy controls

BACKGROUND

Tuberculosis (TB) is an infectious disease and its mortality rate ranks first. Latent tuberculosis infection (LTBI) means that a patient is infected with Mycobacterium tuberculosis, but has no relative clinical symptoms. It has been estimated that approximately 10% of patients with LTBI would develop into active tuberculosis. Therefore, it was urgent to search for more efficient biomarkers to discriminate LTBI from healthy population.

METHODS

The Luminex assay was employed to detect the quantity of cytokines secreted by mononuclear cells from peripheral blood stimulated with the ESAT6 protein among TB, LTBI and healthy controls. The cytokine profile was analyzed by principal components analysis and the receiver operating characteristic curve analysis.

RESULTS

The principal components analysis indicated that LTBI and TB were clearly separated from healthy controls, and that LTBI was also successfully differentiated from healthy controls. The cytokine profiling method to distinguish LTBI from healthy controls has a sensitivity and specificity of 100%. Nine potential biomarkers, including IL-23, IL-21, HGF, Bngf, IL-27, IL-31, IL-1β, IL-22 and IL-18, were identified, and these cytokines were considered as a potential cytokine complex for more effectively discriminating LTBI from healthy controls.

CONCLUSION

IL-23, IL-21, HGF, Bngf, IL-27, IL-31, IL-1β, IL-22 and IL-18 were demonstrated to be the potential cytokine complex for the assessment between LTBI and healthy controls.

Effects of various radiation doses on induced T-helper cell differentiation and related cytokine secretion

Exposure to ionizing radiation often induces T helper (Th) cell differentiation, resulting in an imbalance of Th1 and Th2 cellular subtypes, which can affect the efficacy of cancer radiotherapy. The aim of this study was to analyze differential expression of Th1, Th2 and Th3/Type 1 regulatory T cell (Tr1) subtype-related genes and cytokines in mouse thymocytes after high- and low-dose systemic radiation, using functional classification gene arrays and Elisa assays, and to explore the molecular mechanisms underlying radiation's immune effects and their relationship with Th1/Th2 immunity. We found that expression of 8 genes was upregulated after LDR, while expression of 5 genes was downregulated. After HDR, 54 genes were upregulated and 3 genes were downregulated, including genes related to Th1, Th2 and Th3/Tr1 cellular subtypes, Th1/Th2-type immune response genes and transcription factor-related genes. In the foregoing results, LDR and HDR in the thymus induced opposite patterns of expression for Th1-, Th2- and Th3-type related cytokines TGF-β, C/EBP-β and TNF-α. We also found that expression of Interferon-γ (IFN-γ) and Interleukin-2 (IL-2), which have a moderating effect on immune function, was upregulated after LDR. Furthermore, the secretion of negative regulatory factors Interleukin-1β (IL-1β), Interleukin-4 (IL-4), transforming growth factor-β (TGF-β) and Interleukin-21 (IL-21) was reduced after LDR, but HDR produced the opposite effect and stimulated their expression. These findings suggest that LDR may induce a Th1-type immune response, while HDR may lead to a Th2-type immune response.

Expression profile of CXCL12 chemokine during M. tuberculosis infection with different therapeutic interventions in guinea pig

Mycobacterium indicus pranii (MIP) already established as an immune-modulator in mycobacterial infections generates immune response by acting on CXC chemokines. In the present study, the immunomodulatory effect of MIP in conjunction with chemotherapy against M.tb infection was evaluated by colony forming units (CFUs) following aerosol infection to guinea pig and by measuring CXCL12 chemokine expression using q-PCR and in situ RT-PCR. Different experimental groups included, infection (Rv), immunoprophylaxis (RvMw), chemotherapy (RvCh) and combination of immunoprophylaxis+chemotherapy (RvChMw) group and normal healthy (NH) group. In the combination of immunoprophylaxis+chemotherapy (RvChMw) group, the CFU counts reduced significantly (p<0.001) at 4th week of infection as compared to other treated groups (RvMw and RvCh group). The expression of CXCL12 was recorded in all the treated groups of animals. The study demonstrated suppressed expression of CXCL 12 in both immunoprophylaxis as well as chemotherapy groups (6th and 8th week) that become elevated in immunoprophylaxis plus chemotherapy group (10th week), at which time point no CFUs were detected in RvCh and RvChMw group. The findings indicate that the expression of CXCL12 is associated with good response to anti - tubercular treatment. Thus, prior immunization with MIP appears to show good immunomodulatory effect to release CXCL12 chemokine during infection and also correlates with enhanced effect to chemotherapy.

IL-21 signaling is essential for optimal host resistance against Mycobacterium tuberculosis infection

IL-21 is produced predominantly by activated CD4⁺ T cells and has pleiotropic effects on immunity via the IL-21 receptor (IL-21R), a member of the common gamma chain (γ_c) cytokine receptor family. We show that IL-21 signaling plays a crucial role in T cell responses during Mycobacterium tuberculosis infection by augmenting CD8⁺ T cell priming, promoting T cell accumulation in the lungs, and enhancing T cell cytokine production. In the absence of IL-21 signaling, more CD4⁺ and CD8⁺ T cells in chronically infected mice express the T cell inhibitory molecules PD-1 and TIM-3. We correlate these immune alterations with increased susceptibility of IL-21R^−/− mice, which have increased lung bacterial burden and earlier mortality compared to WT mice. Finally, to causally link the immune defects with host susceptibility, we use an adoptive transfer model to show that IL-21R^−/− T cells transfer less protection than WT T cells. These results prove that IL-21 signaling has an intrinsic role in promoting the protective capacity of T cells. Thus, the net effect of IL-21 signaling is to enhance host resistance to M. tuberculosis. These data position IL-21 as a candidate biomarker of resistance to tuberculosis.

Induction of Unconventional T Cells by a Mutant Mycobacterium bovis BCG Strain Formulated in Cationic Liposomes Correlates with Protection against Mycobacterium tuberculosis Infections of Immunocompromised Mice

Earlier studies aimed at defining protective immunity induced by Mycobacterium bovis BCG immunization have largely focused on the induction of antituberculosis CD4(+) and CD8(+) T cell responses. Here we describe a vaccine consisting of a BCGΔmmaA4 deletion mutant formulated in dimethyl dioctadecyl-ammonium bromide (DDA) with d-(+)-trehalose 6,6'-dibehenate (TDB) (DDA/TDB) adjuvant (A4/Adj) that protected TCRδ(-/-) mice depleted of CD4(+), CD8(+), and NK1.1(+) T cells against an aerosol challenge with M. tuberculosis These mice were significantly protected relative to mice immunized with a nonadjuvanted BCGΔmmaA4 (BCG-A4) mutant and nonvaccinated controls at 2 months and 9 months postvaccination. In the absence of all T cells following treatment with anti-Thy1.2 antibody, the immunized mice lost the ability to control the infection. These results indicate that an unconventional T cell population was mediating protection in the absence of CD4(+), CD8(+), NK1.1(+), and TCRγδ T cells and could exhibit memory. Focusing on CD4(-) CD8(-) double-negative (DN) T cells, we found that these cells accumulated in the lungs postchallenge significantly more in A4/Adj-immunized mice and induced significantly greater frequencies of pulmonary gamma interferon (IFN-γ)-producing cells than were seen in the nonvaccinated or nonadjuvanted BCG control groups. Moreover, pulmonary DN T cells from the A4/Adj group exhibited significantly higher IFN-γ integrated median fluorescence intensity (iMFI) values than were seen in the control groups. We also showed that enriched DN T cells from mice immunized with A4/Adj could control mycobacterial growth in vitro significantly better than naive whole-spleen cells. These results suggest that formulating BCG in DDA/TDB adjuvant confers superior protection in immunocompromised mice and likely involves the induction of long-lived memory DN T cells.

Correlates of Vaccine-Induced Protection against Mycobacterium tuberculosis Revealed in Comparative Analyses of Lymphocyte Populations

A critical hindrance to the development of a novel vaccine against Mycobacterium tuberculosis is a lack of understanding of protective correlates of immunity and of host factors involved in a successful adaptive immune response. Studies from our group and others have used a mouse-based in vitro model system to assess correlates of protection. Here, using this coculture system and a panel of whole-cell vaccines with varied efficacy, we developed a comprehensive approach to understand correlates of protection. We compared the gene and protein expression profiles of vaccine-generated immune peripheral blood lymphocytes (PBLs) to the profiles found in immune splenocytes. PBLs not only represent a clinically relevant cell population, but comparing the expression in these populations gave insight into compartmentally specific mechanisms of protection. Additionally, we performed a direct comparison of host responses induced when immune cells were cocultured with either the vaccine strain Mycobacterium bovis BCG or virulent M. tuberculosis. These comparisons revealed host-specific and bacterium-specific factors involved in protection against virulent M. tuberculosis. Most significantly, we identified a set of 13 core molecules induced in the most protective vaccines under all of the conditions tested. Further validation of this panel of mediators as a predictor of vaccine efficacy will facilitate vaccine development, and determining how each promotes adaptive immunity will advance our understanding of antimycobacterial immune responses.

Functional Heterogeneity and Antimycobacterial Effects of Mouse Mucosal-Associated Invariant T Cells Specific for Riboflavin Metabolites

Mucosal-associated invariant T (MAIT) cells have a semi-invariant TCR Vα-chain, and their optimal development is dependent upon commensal flora and expression of the nonpolymorphic MHC class I-like molecule MR1. MAIT cells are activated in an MR1-restricted manner by diverse strains of bacteria and yeast, suggesting a widely shared Ag. Recently, human and mouse MR1 were found to bind bacterial riboflavin metabolites (ribityllumazine [RL] Ags) capable of activating MAIT cells. In this study, we used MR1/RL tetramers to study MR1 dependency, subset heterogeneity, and protective effector functions important for tuberculosis immunity. Although tetramer(+) cells were detected in both MR1(+/+) and MR1(-/-) TCR Vα19i-transgenic (Tg) mice, MR1 expression resulted in significantly increased tetramer(+) cells coexpressing TCR Vβ6/8, NK1.1, CD44, and CD69 that displayed more robust in vitro responses to IL-12 plus IL-18 and RL Ag, indicating that MR1 is necessary for the optimal development of the classic murine MAIT cell memory/effector subset. In addition, tetramer(+) MAIT cells expressing CD4, CD8, or neither developing in MR1(+/+) Vα19i-Tg mice had disparate cytokine profiles in response to RL Ag. Therefore, murine MAIT cells are considerably more heterogeneous than previously thought. Most notably, after mycobacterial pulmonary infection, heterogeneous subsets of tetramer(+) Vα19i-Tg MAIT cells expressing CXCR3 and α4β1 were recruited into the lungs and afforded early protection. In addition, Vα19iCα(-/-)MR(+/+) mice were significantly better protected than were Vα19iCα(-/-)MR1(-/-), wild-type, and MR1(-/-) non-Tg mice. Overall, we demonstrate considerable functional diversity of MAIT cell responses, as well as that MR1-restricted MAIT cells are important for tuberculosis protective immunity.

Development of an unbiased antigen-mining approach to identify novel vaccine antigens and diagnostic reagents for bovine tuberculosis

Previous experiments for the identification of novel diagnostic or vaccine candidates for bovine tuberculosis have followed a targeted approach, wherein specific groups of proteins suspected to contain likely candidates are prioritized for immunological assessment (for example, with in silico approaches). However, a disadvantage of this approach is that the sets of proteins analyzed are restricted by the initial selection criteria. In this paper, we describe a series of experiments to evaluate a nonbiased approach to antigen mining by utilizing a Gateway clone set for Mycobacterium tuberculosis, which constitutes a library of clones expressing 3,294 M. tuberculosis proteins. Although whole-blood culture experiments using Mycobacterium bovis-infected animals and M. bovis BCG-vaccinated controls did not reveal proteins capable of differential diagnosis, several novel immunogenic proteins were identified and prioritized for efficacy studies in a murine vaccination/challenge model. These results demonstrate that Rv3329-immunized mice had lower bacterial cell counts in their spleens following challenge with M. bovis. In conclusion, we demonstrate that this nonbiased approach to antigen mining is a useful tool for identifying and prioritizing novel proteins for further assessment as vaccine antigens.

Molecular analysis of non-specific protection against murine malaria induced by BCG vaccination

Although the effectiveness of BCG vaccination in preventing adult pulmonary tuberculosis (TB) has been highly variable, epidemiologic studies have suggested that BCG provides other general health benefits to vaccinees including reducing the impact of asthma, leprosy, and possibly malaria. To further evaluate whether BCG immunization protects against malarial parasitemia and to define molecular correlates of this non-specific immunity, mice were vaccinated with BCG and then challenged 2 months later with asexual blood stage Plasmodium yoelii 17XNL (PyNL) parasites. Following challenge with PyNL, significant decreases in parasitemia were observed in BCG vaccinated mice relative to naïve controls. To identify immune molecules that may be associated with the BCG-induced protection, gene expression was evaluated by RT-PCR in i) naïve controls, ii) BCG-vaccinated mice, iii) PyNL infected mice and iv) BCG vaccinated/PyNL infected mice at 0, 1, 5, and 9 days after the P. yoelii infection. The expression results showed that i) BCG immunization induces the expression of at least 18 genes including the anti-microbial molecules lactoferrin, eosinophil peroxidase, eosinophil major basic protein and the cathelicidin-related antimicrobial peptide (CRAMP); ii) an active PyNL infection suppresses the expression of important immune response molecules; and iii) the extent of PyNL-induced suppression of specific genes is reduced in BCG-vaccinated/PyNL infected mice. To validate the gene expression data, we demonstrated that pre-treatment of malaria parasites with lactoferrin or the cathelicidin LL-37 peptide decreases the level of PyNL parasitemias in mice. Overall, our study suggests that BCG vaccination induces the expression of non-specific immune molecules including antimicrobial peptides which may provide an overall benefit to vaccinees by limiting infections of unrelated pathogens such as Plasmodium parasites.

Diagnostic value of interleukin 21 and carcinoembryonic antigen levels in malignant pleural effusions

The aim of this study was to evaluate the diagnostic value of interleukin 21 (IL-21) and carcinoembryonic antigen (CEA) in tuberculous pleural effusions (TPEs) and malignant pleural effusions (MPEs). Pleural effusion samples from 103 patients were classified on the basis of diagnosis as TPE (n=51) and MPE (n=52). The concentration of IL-21 was determined by ELISA. Lactate dehydrogenase (LDH), adenosine dehydrogenase (ADA) and CEA levels were also determined in all patients. A significant difference was observed in the levels of ADA and CEA (P<0.01), but not in the levels of LDH (P>0.05) between TPE and MPE. The concentration of IL-21 in MPE was significantly higher compared to TPE (P<0.01). With a threshold value of 4.32 pg/ml, IL-21 had a sensitivity of 76.9% (40/52) and a specificity of 80.4% (41/51). Combined detection of IL-21 and CEA had a sensitivity of 69.2% (36/52) and a specificity of 92.2% (47/51). These two markers can contribute to the differential diagnosis of MPEs.

Autocrine CCL5 signaling promotes invasion and migration of CD133+ ovarian cancer stem-like cells via NF-κB-mediated MMP-9 upregulation

The concept of cancer stem cells (CSCs) proposes that solely CSCs are capable of generating tumor metastases. However, how CSCs maintain their invasion and migration abilities, the most important properties of metastatic cells, still remains elusive. Here we used CD133 to mark a specific population from human ovarian cancer cell line and ovarian cancer tissue and determined its hyperactivity in migration and invasion. Therefore, we labeled this population as cancer stem-like cells (CSLCs). In comparison to CD133- non-CSLCs, chemokine CCL5 and its receptors, CCR1, CCR3, and CCR5, were consistently upregulated in CSLCs, and most importantly, blocking of CCL5, CCR1, or CCR3 effectively inhibits the invasive capacity of CSLCs. Mechanistically, we identified that this enhanced invasiveness is mediated through nuclear factor κB (NF-κB) activation and the consequently elevated MMP9 secretion. Our results suggested that the autocrine activation of CCR1 and CCR3 by CCL5 represents one of major mechanisms underlying the metastatic property of ovarian CSLCs.

Expression of CXCL10 (IP-10) and CXCL11 (I-TAC) chemokines during Mycobacterium tuberculosis infection and immunoprophylaxis with Mycobacterium indicus pranii (Mw) in guinea pig

Mycobacterium indicus pranii (earlier known as Mycobacterium w) has been used as an immunmodulatory agent in leprosy and tuberculosis by mediating the release of various cytokines and chemokines. CXCL10 (IP-10) and CXCL11 (I-TAC) chemokines are involved in T-cell migration and stimulation of natural killer cells in Mycobacterium tuberculosis infection. In this study, the effect of heat killed M. indicus pranii (alone and in conjunction with chemotherapy) on disease progression was determined by colony forming units (CFUs) in guinea pig lung following their aerosol infection and the expression levels of CXCL10 and CXCL11 were studied by quantitative Reverse Transcriptase Polymerase Chain Reaction (qRT-PCR) and in situ RT-PCR. Four groups of animals included; infection only (Rv), immunoprophylaxis (RvMw), chemotherapy (RvCh) and combination of immunoprophylaxis with chemotherapy (RvChMw). In the group where immunoprophylaxis was given in combination with chemotherapy, the CFU counts reduced significantly at 4th week post-infection as compared to animals that received immunoprophylaxis or chemotherapy alone. At the same time, all groups of animals had elevated expression of CXCL 10 which was significantly high only in animals that received Mw with or without chemotherapy. Unlike to CXCL 10, study demonstrated suppressed expression CXCL 11 in both immunoprophylaxis as well as chemotherapy groups that became up-regulated in synergistic response of immunoprophylaxis and chemotherapy. Taken together, data indicates that the expression of CXCL10 and CXCL11 positively correlates with anti-tubercular treatment (at least with combination of immunoprophylaxis and chemotherapy). Therefore, prior immunization with Mw appears to be a good immunomodulator for release of chemokines and augments the effect of chemotherapy.

The expression of ferritin, lactoferrin, transferrin receptor and solute carrier family 11A1 in the host response to BCG-vaccination and Mycobacterium tuberculosis challenge

Iron is an essential cofactor for both mycobacterial growth during infection and for a successful protective immune response by the host. The immune response partly depends on the regulation of iron by the host, including the tight control of expression of the iron-storage protein, ferritin. BCG vaccination can protect against disease following Mycobacterium tuberculosis infection, but the mechanisms of protection remain unclear. To further explore these mechanisms, splenocytes from BCG-vaccinated guinea pigs were stimulated ex vivo with purified protein derivative from M. tuberculosis and a significant down-regulation of ferritin light- and heavy-chain was measured by reverse-transcription quantitative-PCR (P≤0.05 and ≤0.01, respectively). The mechanisms of this down-regulation were shown to involve TNFα and nitric oxide. A more in depth analysis of the mRNA expression profiles, including genes involved in iron metabolism, was performed using a guinea pig specific immunological microarray following ex vivo infection with M. tuberculosis of splenocytes from BCG-vaccinated and naïve guinea pigs. M. tuberculosis infection induced a pro-inflammatory response in splenocytes from both groups, resulting in down-regulation of ferritin (P≤0.05). In addition, lactoferrin (P≤0.002), transferrin receptor (P≤0.05) and solute carrier family 11A1 (P≤0.05), were only significantly down-regulated after infection of the splenocytes from BCG-vaccinated animals. The results show that expression of iron-metabolism genes is tightly regulated as part of the host response to M. tuberculosis infection and that BCG-vaccination enhances the ability of the host to mount an iron-restriction response which may in turn help to combat invasion by mycobacteria.

Systemic BCG immunization induces persistent lung mucosal multifunctional CD4 T(EM) cells which expand following virulent mycobacterial challenge

To more closely understand the mechanisms of how BCG vaccination confers immunity would help to rationally design improved tuberculosis vaccines that are urgently required. Given the established central role of CD4 T cells in BCG induced immunity, we sought to characterise the generation of memory CD4 T cell responses to BCG vaccination and M. bovis infection in a murine challenge model. We demonstrate that a single systemic BCG vaccination induces distinct systemic and mucosal populations of T effector memory (T_EM) cells in vaccinated mice. These CD4⁺CD44^hiCD62L^loCD27⁻ T cells concomitantly produce IFN-γ and TNF-α, or IFN-γ, IL-2 and TNF-α and have a higher cytokine median fluorescence intensity MFI or ‘quality of response’ than single cytokine producing cells. These cells are maintained for long periods (>16 months) in BCG protected mice, maintaining a vaccine–specific functionality. Following virulent mycobacterial challenge, these cells underwent significant expansion in the lungs and are, therefore, strongly associated with protection against M. bovis challenge. Our data demonstrate that a persistent mucosal population of T_EM cells can be induced by parenteral immunization, a feature only previously associated with mucosal immunization routes; and that these multifunctional T_EM cells are strongly associated with protection. We propose that these cells mediate protective immunity, and that vaccines designed to increase the number of relevant antigen-specific T_EM in the lung may represent a new generation of TB vaccines.

Transcriptional suppression of IL-27 production by Mycobacterium tuberculosis-activated p38 MAPK via inhibition of AP-1 binding

Mycobacterium tuberculosis remains a major global challenge to human health care, and the mechanisms of how M. tuberculosis evades host immune surveillance to favor its survival are still largely unknown. In this study, we found that bacillus Calmette-Guérin (BCG) and viable M. tuberculosis as well as M. tuberculosis lysates could activate IL-27 expression in human and mouse macrophages by induction of p28 subunit transcription. However, in parallel with these effects, BCG and M. tuberculosis lysate stimulation of macrophages induced activation of p38 MAPK signaling molecules MLK3/MKK3/MK2 to prevent maximal IL-27 production. M. tuberculosis lysate-induced p28 transcription was dependent on MyD88 signaling pathway. AP-1/c-Fos was shown to bind directly to the p28 promoter and induce p28 expression after M. tuberculosis lysate stimulation. Overexpression of p38α inhibited the binding of c-Fos to the p28 promoter but had no effect on c-Fos protein expression or phosphorylation in response to M. tuberculosis lysate stimulation. Furthermore, blockade of p38 by SB203580 enhanced M. tuberculosis-induced AP-1 binding to the p28 promoter. Importantly, we show that adding exogenous IL-27 to increase the levels produced by PBMCs stimulated with live mycobacteria enhanced the ability of BCG-expanded T cells to inhibit intracellular mycobacterial growth in human macrophages. Taken together, our data demonstrate that mycobacterial stimulation induces both IL-27 production and p38 MAPK activation. Strategies designed to tip the balance toward positive regulation of p28 induction by mycobacteria could lead to enhanced protective tuberculosis immunity.

Mycobacterium bovis-BCG vaccination induces specific pulmonary transcriptome biosignatures in mice

Background

In the present study, we applied microarray technology to define biosignatures by microarray transcriptome analysis in lung and spleen samples after BCG vaccination and M. bovis infection of BALB/c mice. The aims were two-fold, namely to define biosignatures that could predict vaccine success before challenge, and biomarker patterns that correlated with anamnestic protective responses following exposure to virulent M. bovis. Further, these biosignatures should be detectable without in vitro antigenic challenge.

Principal Findings

After BCG vaccination, we defined a specific pulmonary gene expression signature related to the connective tissue development and function network that predicted vaccine success before M. bovis challenge. In addition, a Th17-related cytokine profile was found that correlated with vaccine-induced protective immunity following infection with virulent M. bovis in the lung as well as additional genes that were up-regulated in the spleens of vaccinated animals post-infection related to neutrophil biology and inflammation.

Conclusions

This study has therefore prioritized both biomarkers predicting vaccination success before challenge and bio-signatures that are potentially associated with protective immune responses that will be useful to evaluate future vaccine candidates.

Highly persistent and effective prime/boost regimens against tuberculosis that use a multivalent modified vaccine virus Ankara-based tuberculosis vaccine with interleukin-15 as a molecular adjuvant

Novel immunization strategies are needed to enhance the global control of tuberculosis (TB). In this study, we assessed the immunizing activity of a recombinant modified vaccinia Ankara (MVA) construct (MVA/IL-15/5Mtb) which overexpresses five Mycobacterium tuberculosis antigens (antigen 85A, antigen 85B, ESAT6, HSP60, and Mtb39), as well as the molecular adjuvant interleukin-15 (IL-15). Homologous prime/boost studies showed that the MVA/IL-15/5Mtb vaccine induced moderate but highly persistent protective immune responses for at least 16 months after the initial vaccination and that the interval between the prime and boost did not significantly alter vaccine-induced antituberculosis protective immunity. At 16 months, when the Mycobacterium bovis BCG and MVA/IL-15/5Mtb vaccine-induced protection was essentially equivalent, the protective responses after a tuberculous challenge were associated with elevated levels of gamma interferon (IFN-gamma), IL-17F, Cxcl9, and Cxcl10. To amplify the immunizing potential of the MVA/IL-15/5Mtb vaccine, a heterologous prime/boost regimen was tested using an ESAT6-antigen 85B (E6-85) fusion protein formulated in dimethyldiotacylammonium bromide/monophosphoryl lipid A (DDA/MPL) adjuvant as the priming vaccine and the MVA/IL-15/5Mtb recombinant virus as the boosting agent. When MVA/IL-15/5Mtb vaccine boosting was done at 2 or 6 months following the final fusion protein injections, the prime/boost regimen evoked protective responses against an aerogenic M. tuberculosis challenge which was equivalent to that induced by BCG immunization. Long-term memory after immunization with the E6-85-MVA/IL-15/5Mtb combination regimen was associated with the induction of monofunctional CD4 and CD8 IFN-gamma-producing T cells and multifunctional CD4 and CD8 T cells expressing IFN-gamma/tumor necrosis factor alpha (TNF-alpha), TNF-alpha/IL-2, and IFN-gamma/TNF-alpha/IL-2. In contrast, BCG-induced protection was characterized by fewer CD4 and CD8 monofunctional T cells expressing IFN-gamma and only IFN-gamma/TNF-alpha and IFN-gamma/TNF-alpha/IL-2 expressing multifunctional T (MFT) cells. Taken together, these results suggest that a heterologous prime/boost protocol using an MVA-based tuberculosis vaccines to boost after priming with TB protein/adjuvant preparations should be considered when designing long-lived TB immunization strategies.

Cellular and molecular immune responses of the sea bass (Dicentrarchus labrax) experimentally infected with betanodavirus

Naïve sea bass juveniles (38.4 + or - 4.5 g) were intramuscularly infected with a sublethal dose of betanodavirus isolate 378/I03, followed after 43 days by a similar boosting. This infection resulted in an overall mortality of 7.6%. At various intervals, sampling of fish tissues was performed to investigate: i) B and T lymphocyte content in organs and tissues; ii), proliferation of leucocytes re-stimulated in vitro with inactivated virus; iii) presence of serum antibody specific for betanodavirus; iv) expression of genes coding for the following immunoregulatory molecules involved in innate and acquired responses: type I IFN, Mx, IL-1, Cox-2; IL-10, TGF-beta, TCRbeta, CD4, CD8alpha, IgM, by using a quantitative PCR array system developed for sea bass. The obtained results showed a detectable increase of T cells and B cells in PBL during betanodavirus infection. Furthermore, leucocytes obtained from blood, head kidney, and gills showed a detectable "in vitro" increase in viability upon addition of inactivated viral particles, as determined by measuring intracellular ATP concentration. ELISA analysis of sera showed that exposure to nodavirus induced a low, but specific antibody titer measured 43 days after infection, despite the presence of measurable levels of natural antibody. Finally, a strong upregulation of genes coding for type I IFN, Mx, and IgM was identified after both infection and boosting. Interestingly, an upregulation of Cox-2 until boosting, and of TGF-beta and IL-10 after boosting was also observed, while the other tested genes did not show any significant variations with respect to mock-treated fish. Overall, our work represents a first comprehensive analysis of cellular and molecular immune parameters in a fish species exposed to a pathogenic virus.

A practical in vitro growth inhibition assay for the evaluation of TB vaccines

New vaccines and novel immunization strategies are needed to improve the control of the global tuberculosis epidemic. To facilitate vaccine development, we have been creating in vitro mycobacterial intra-macrophage growth inhibition assays. Here we describe the development of an in vitro assay designed for BSL-2 laboratories which measures the capacity of vaccine-induced immune splenocytes to control the growth of isoniazid-resistant Mycobacterium bovis BCG (INH(r) BCG). The use of the INH(r) BCG as the infecting organism allows the discrimination of BCG bacilli used in murine vaccinations from BCG used in the in vitro assay. In this study, we showed that protective immune responses evoked by four different types of Mycobacterium tuberculosis vaccines [BCG, an ESAT6/Antigen 85B fusion protein formulated in DDA/MPL adjuvant, a DNA vaccine expressing the same fusion protein, and a TB Modified Vaccinia Ankara construct expressing four TB antigens (MVA-4TB)] were detected. Importantly, the levels of vaccine-induced protective immunity seen in the in vitro assay correlated with the results from in vivo protection studies in the mouse model of pulmonary tuberculosis. Furthermore, the growth inhibition data for the INH(r) BCG assay was similar to the previously reported results for a M. tuberculosis infection assay. The cytokine expression profiles at day 7 of the INH(r) BCG growth inhibition studies were also similar but not identical to the cytokine patterns detected in earlier M. tuberculosis co-culture assays. Overall, we have shown that a BSL-2 compatible in vitro growth inhibition assay using INH(r) BCG as the intra-macrophage target organism should be useful in developing and evaluating new TB immunization strategies.

Development of a murine mycobacterial growth inhibition assay for evaluating vaccines against Mycobacterium tuberculosis

The development and characterization of new tuberculosis (TB) vaccines has been impeded by the lack of reproducible and reliable in vitro assays for measuring vaccine activity. In this study, we developed a murine in vitro mycobacterial growth inhibition assay for evaluating TB vaccines that directly assesses the capacity of immune splenocytes to control the growth of Mycobacterium tuberculosis within infected macrophages. Using this in vitro assay, protective immune responses induced by immunization with five different types of TB vaccine preparations (Mycobacterium bovis BCG, an attenuated M. tuberculosis mutant strain, a DNA vaccine, a modified vaccinia virus strain Ankara [MVA] construct expressing four TB antigens, and a TB fusion protein formulated in adjuvant) can be detected. Importantly, the levels of vaccine-induced mycobacterial growth-inhibitory responses seen in vitro after 1 week of coculture correlated with the protective immune responses detected in vivo at 28 days postchallenge in a mouse model of pulmonary tuberculosis. In addition, similar patterns of cytokine expression were evoked at day 7 of the in vitro culture by immune splenocytes taken from animals immunized with the different TB vaccines. Among the consistently upregulated cytokines detected in the immune cocultures are gamma interferon, growth differentiation factor 15, interleukin-21 (IL-21), IL-27, and tumor necrosis factor alpha. Overall, we have developed an in vitro functional assay that may be useful for screening and comparing new TB vaccine preparations, investigating vaccine-induced protective mechanisms, and assessing manufacturing issues, including product potency and stability.