Immunomodulatory activity of hyaluronidase is associated with metabolic adaptations during acute inflammation.

OBJECTIVE AND DESIGN: Investigate survival outcomes, and immunological and metabolomic effects of hyaluronidase (Hz) treatment during mouse models of acute inflammation and sepsis. METHODS: Survival of C57Bl/6 mice was monitored after lethal challenge with lipopolysaccharide (LPS) or cecal and ligation puncture (CLP)-induced sepsis and treated with Hz or saline. Mice were also challenged with LPS and treated with Hz for leukocyte counting, cytokine quantification and determination of metabolomic profiles in the peritoneal fluid. RESULTS: Hz treatment improved survival outcomes after lethal challenge with LPS or CLP-induced sepsis. LPS challenge promoted acute neutrophil accumulation and production of interleukin-1ß (IL-1ß) and IL-6 in the peritoneum, whereas Hz treatment suppressed neutrophil infiltration and cytokine production. We further characterized the metabolomic alterations caused by LPS challenge, which predicted activity of metabolic pathways related to fatty acids and eicosanoids. Hz treatment had a profound effect over the metabolic response, reflected by reductions of the relative levels of fatty acids. CONCLUSION: Collectively, these data demonstrate that Hz treatment is associated with metabolic reprogramming of pathways that sustain the inflammatory response.

New strategy for testing efficacy of immunotherapeutic compounds for diabetes in vitro.

BACKGROUND: The valuable role of immunotherapy in treating autoimmune diseases is increasingly recognized by those involved in the research and clinical application of new biopharmaceuticals products. However, many aspects related to the mechanisms of immune-modulated therapies remain to be elucidated in order to explore fully the emerging opportunities. The non-obese diabetic NOD mouse develops insulin-dependent diabetes mellitus spontaneously as a consequence of an autoimmune process in the presence of pathogenic CD4(+) T cells that typically exhibit Th17 cell phenotypes. The change of a Th17 phenotype into a pattern of regulatory T cells (Treg) is extremely important in controlling autoimmune diseases. Heat shock proteins (HSPs) are stress-induced proteins with immunoregulatory properties. In the current study, the capacity of Hsp65 and Hsp70 mycobacterial HSPs and a constructed DNA encoded Hsp65 (DNAhsp65) to transform the pattern of the immune response from Th17 into Treg cells has been studied in vitro using co-cultures of antigen presenting cells (APCs) and T cells in NOD mice. RESULTS: Cells harvested from NOD mice and cultured for 48 h (without immunoregulatory compounds) presented with Th1/Th17 patterns and secretions of IL-6, IFN-γ, IL-10 and IL-17 cytokines. The cultured cells from the non-diabetic BALB/C mice exhibited a Th1 pattern and the production of IL 6 and IFN-γ secretions. An up-regulation was observed in the supernatants from the co-cultures of NOD cells that were stimulated with DNAhsp65, Hsp65 or Hsp70 through increased levels of IL-10 secretion and the suppression of IL-6, IFN-γ and IL-17 production. In addition, immunoregulation was demonstrated through IL-17 suppression in the co-culture stimulated by the specific insulin antigen. Moreover, an increase of immunoregulatory compounds were observed in the co-culture through the expression of CD11b(+)CD86(+) activation markers on APCs, as well as the frequency of Treg cells expressing CD4(+)CD3(+) and CD4(+)CD25(hi). CONCLUSIONS: The in vitro observation of Th17 cells differentiating into Tregs in NOD mice could raise the hypothesis that the immune regulatory activity of HSPs could be an efficient strategy for diabetes prevention and treatment.

Synergy of chemotherapy and immunotherapy revealed by a genome-scale analysis of murine tuberculosis.

OBJECTIVES: Although TB immunotherapy improves the results of conventional drug treatment, the effects of combining chemotherapy and immunotherapy have never been systematically evaluated. We used a comprehensive lung transcriptome analysis to directly compare the activity of combined chemotherapy and immunotherapy with that of single treatments in a mouse model of TB. METHODS: Mycobacterium tuberculosis-infected mice in the chronic phase of the disease (day 30) received: (i) isoniazid and rifampicin (drugs) daily for 30 days; (ii) DNA immunotherapy (DNA), consisting of four 100 µg injections at 10 day intervals; (iii) both therapies (DNA + drugs); or (iv) saline. The effects were evaluated 10 days after the end of treatment (day 70 post-infection). RESULTS: In all groups a systemic reduction in the load of bacilli was observed, bacilli became undetectable in the drugs and DNA + drugs groups, but the whole lung transcriptome analysis showed 867 genes exclusively modulated by the DNA + drugs combination. Gene enrichment analysis indicated that DNA + drugs treatment provided synergistic effects, including the down-regulation of proinflammatory cytokines and mediators of fibrosis, as confirmed by real-time PCR, ELISA, histopathology and hydroxyproline assay. CONCLUSIONS: Our results provide a molecular basis for the advantages of TB treatment using combined chemotherapy and DNA immunotherapy and demonstrate the synergistic effects obtained with this strategy.

Investigation of local anesthetic and antimycobacterial activity of Ottonia martiana Miq. (Piperaceae).

Ottonia martiana is a plant popularly known in Brazil by the use for toothache. Ethanolic extract (EE), hexane fraction (HF), dichloromethane fraction (DF) and piperovatine obtained from O. martiana were assayed in vitro and in vivo. The acute toxicity of EE was determined, and LD50 values of 164.5 and 65.0 mg/kg by the oral and intraperitoneal routes, respectively, indicated a high toxicity for EE in vivo, explaining its popular use by topical administration only. A local anesthetic-like effect of EE and its fractions was observed in experimental models using pain induction, and such effect involved an analgesic action. The antimycobacterial activity of EE, HF, DF and piperovatine was evaluated against Mycobacterium tuberculosis H37Rv ATCC 27924. EE, HF, DF, and piperovatine showed a potential antimycobacterial effect with MICs of 16.0, 62.0, 62.0 and 8.0 µg/mL, respectively. Piperovatine was more effective than the EE or the other fractions. The selectivity index (SI=IC50/MIC) values calculated for EE, HF, DF and piperovatine based on the MICs and the cytotoxicity against J774 macrophages (IC50 by MTT assay) revealed values of 6.43, 2.34, 1.5 and 9.66, respectively.

Mycobacterium tuberculosis expressing phospholipase C subverts PGE2 synthesis and induces necrosis in alveolar macrophages.

BACKGROUND: Phospholipases C (PLCs) are virulence factors found in several bacteria. In Mycobacterium tuberculosis (Mtb) they exhibit cytotoxic effects on macrophages, but the mechanisms involved in PLC-induced cell death are not fully understood. It has been reported that induction of cell necrosis by virulent Mtb is coordinated by subversion of PGE2, an essential factor in cell membrane protection. RESULTS: Using two Mtb clinical isolates carrying genetic variations in PLC genes, we show that the isolate 97-1505, which bears plcA and plcB genes, is more resistant to alveolar macrophage microbicidal activity than the isolate 97-1200, which has all PLC genes deleted. The isolate 97-1505 also induced higher rates of alveolar macrophage necrosis, and likewise inhibited COX-2 expression and PGE2 production. To address the direct effect of mycobacterial PLC on cell necrosis and PGE2 inhibition, both isolates were treated with PLC inhibitors prior to macrophage infection. Interestingly, inhibition of PLCs affected the ability of the isolate 97-1505 to induce necrosis, leading to cell death rates similar to those induced by the isolate 97-1200. Finally, PGE2 production by Mtb 97-1505-infected macrophages was restored to levels similar to those produced by 97-1200-infected cells. CONCLUSIONS: Mycobacterium tuberculosis bearing PLCs genes induces alveolar macrophage necrosis, which is associated to subversion of PGE2 production.

Low-dose plasmid DNA treatment increases plasma vasopressin and regulates blood pressure in experimental endotoxemia.

BACKGROUND: Although plasmid DNA encoding an antigen from pathogens or tumor cells has been widely studied as vaccine, the use of plasmid vector (without insert) as therapeutic agent requires further investigation. RESULTS: Here, we showed that plasmid DNA (pcDNA3) at low doses inhibits the production of IL-6 and TNF-α by lipopolysaccharide (LPS)-stimulated macrophage cell line J774. These findings led us to evaluate whether plasmid DNA could act as an anti-inflammatory agent in a Wistar rat endotoxemia model. Rats injected simultaneously with 1.5 mg/kg of LPS and 10 or 20 µg of plasmid DNA had a remarkable attenuation of mean arterial blood pressure (MAP) drop at 2 hours after treatment when compared with rats injected with LPS only. The beneficial effect of the plasmid DNA on MAP was associated with decreased expression of IL-6 in liver and increased concentration of plasma vasopressin (AVP), a known vasoconstrictor that has been investigated in hemorrhagic shock management. No difference was observed in relation to nitric oxide (NO) production. CONCLUSION: Our results demonstrate for the first time that plasmid DNA vector at low doses presents anti-inflammatory property and constitutes a novel approach with therapeutic potential in inflammatory diseases.

Antimycobacterial activity of 2-phenoxy-1-phenylethanone, a synthetic analogue of neolignan, entrapped in polymeric microparticles.

Conventional treatment of tuberculosis (TB) demands a long course therapy (6 months), known to originate multiple drug resistant strains (MDR-TB), which emphasizes the urgent need for new antituberculous drugs. The purpose of this study was to investigate a novel treatment for TB meant to improve patient compliance by reducing drug dosage frequency. Polymeric microparticles containing the synthetic analogue of neolignan, 1-phenyl-2-phenoxiethanone (LS-2), were obtained by a method of emulsification and solvent evaporation and chemically characterized. Only representative LS-2-loaded microparticles were considered for further studies involving experimental murine TB induced by Mycobacterium tuberculosis H37Rv ATCC 27294. The LS-2-loaded microparticles were spherical in shape, had a smooth wall and showed an encapsulation efficiency of 93% in addition to displaying sustained release. Chemotherapeutic potential of LS-2 entrapped in microparticles was comparable to control groups. These findings are encouraging and indicate that LS-2-loaded microparticles are a potential alternative to conventional chemotherapy of TB.

B cells Can Modulate the CD8 Memory T Cell after DNA Vaccination Against Experimental Tuberculosis.

BACKGROUND: Although B cells are important as antigen presenting cells (APC) during the immune response, their role in DNA vaccination models is unknown. METHODS: In this study in vitro and in vivo experiments were performed to evaluate the ability of B cells to protect mice against Mycobacterium tuberculosis challenge. RESULTS: In vitro and in vivo studies showed that B cells efficiently present antigens after naked plasmid pcDNA3 encoding M. leprae 65-kDa heat shock protein (pcDNA3-Hsp65) internalization and protect B knock-out (BKO) mice against Mycobacterium tuberculosis infection. pcDNA3-Hsp65-transfected B cells adoptively transferred into BKO mice rescued the memory phenotypes and reduced the number of CFU compared to wild-type mice. CONCLUSIONS: These data not only suggest that B cells play an important role in the induction of CD8 T cells but also that they improve bacterial clearance in DNA vaccine model.

Expression of Mycobacterium leprae HSP65 in tobacco and its effectiveness as an oral treatment in adjuvant-induced arthritis.

Transgenic plants are able to express molecules with antigenic properties. In recent years, this has led the pharmaceutical industry to use plants as alternative systems for the production of recombinant proteins. Plant-produced recombinant proteins can have important applications in therapeutics, such as in the treatment of rheumatoid arthritis (RA). In this study, the mycobacterial HSP65 protein expressed in tobacco plants was found to be effective as a treatment for adjuvant-induced arthritis (AIA). We cloned the hsp65 gene from Mycobacterium leprae into plasmid pCAMBIA 2301 under the control of the double 35S promoter from cauliflower mosaic virus. Agrobacterium tumefaciens bearing the pChsp65 plasmid was used to transform tobacco plants. Incorporation of the hsp65 gene was confirmed by PCR, reverse transcription-PCR, histochemistry, and western blot analyses in several transgenic lines of tobacco plants. Oral treatment of AIA rats with the HSP65 protein allowed them to recover body weight and joint inflammation was reduced. Our results suggest a synergistic effect between the HSP65 expressed protein and metabolites presents in tobacco plants.

Intranasal vaccination with messenger RNA as a new approach in gene therapy: use against tuberculosis.

BACKGROUND: mRNAs are highly versatile, non-toxic molecules that are easy to produce and store, which can allow transient protein expression in all cell types. The safety aspects of mRNA-based treatments in gene therapy make this molecule one of the most promising active components of therapeutic or prophylactic methods. The use of mRNA as strategy for the stimulation of the immune system has been used mainly in current strategies for the cancer treatment but until now no one tested this molecule as vaccine for infectious disease. RESULTS: We produce messenger RNA of Hsp65 protein from Mycobacterium leprae and show that vaccination of mice with a single dose of 10 µg of naked mRNA-Hsp65 through intranasal route was able to induce protection against subsequent challenge with virulent strain of Mycobacterium tuberculosis. Moreover it was shown that this immunization was associated with specific production of IL-10 and TNF-alpha in spleen. In order to determine if antigen presenting cells (APCs) present in the lung are capable of capture the mRNA, labeled mRNA-Hsp65 was administered by intranasal route and lung APCs were analyzed by flow cytometry. These experiments showed that after 30 minutes until 8 hours the populations of CD11c+, CD11b+ and CD19+ cells were able to capture the mRNA. We also demonstrated in vitro that mRNA-Hsp65 leads nitric oxide (NO) production through Toll-like receptor 7 (TLR7). CONCLUSIONS: Taken together, our results showed a novel and efficient strategy to control experimental tuberculosis, besides opening novel perspectives for the use of mRNA in vaccines against infectious diseases and clarifying the mechanisms involved in the disease protection we noticed as well.

DNA vaccine containing the mycobacterial hsp65 gene prevented insulitis in MLD-STZ diabetes.

BACKGROUND: Our group previously demonstrated that a DNA plasmid encoding the mycobacterial 65-kDa heat shock protein (DNA-HSP65) displayed prophylactic and therapeutic effect in a mice model for tuberculosis. This protection was attributed to induction of a strong cellular immunity against HSP65. As specific immunity to HSP60 family has been detected in arthritis, multiple sclerosis and diabetes, the vaccination procedure with DNA-HSP65 could induce a cross-reactive immune response that could trigger or worsen these autoimmune diseases. METHODS: In this investigation was evaluated the effect of a previous vaccination with DNA-HSP65 on diabetes development induced by Streptozotocin (STZ). C57BL/6 mice received three vaccine doses or the corresponding empty vector and were then injected with multiple low doses of STZ. RESULTS: DNA-HSP65 vaccination protected mice from STZ induced insulitis and this was associated with higher production of IL-10 in spleen and also in the islets. This protective effect was also concomitant with the appearance of a regulatory cell population in the spleen and a decreased infiltration of the islets by T CD8+ lymphocytes. The vector (DNAv) also determined immunomodulation but its protective effect against insulitis was very discrete. CONCLUSION: The data presented in this study encourages a further investigation in the regulatory potential of the DNA-HSP65 construct. Our findings have important implications for the development of new immune therapy strategies to combat autoimmune diseases.

In vitrouptake and antimycobacterial activity of liposomal usnic acid formulation.

The cellular uptake and antimycobacterial activity of usnic acid (UA) and usnic acid-loaded liposomes (UA-LIPOs) were assessed on J774 macrophages. The minimal inhibitory concentration (MIC) and the minimal bactericidal concentration (MBC) of UA and UA-LIPO against Mycobacterium tuberculosis were determined. Concentrations required to inhibit 50% of cell proliferation (IC(50)) were 22.5 (+/-0.60) and 12.5 (+/-0.26) microg/ml, for UA and UA-LIPO, respectively. The MICs of UA and UA-LIPO were 6.5 and 5.8 microg/mL, respectively. The MBC of UA-LIPO was twice as low (16 microg/mL) as that of UA (32 microg/mL). An improvement in the intracellular uptake of UA-LIPO was found (21.6 x 10(4) +/- 28.3 x 10(2) c.p.s), in comparison with UA (9.5 x 10(4) +/- 11.4 x 10(2) c.p.s). In addition, UA-LIPO remains much longer inside macrophages (30 hours). All data obtained from the encapsulation of usnic acid into liposomes as a drug delivery system (DDS) indicate a strong interaction between UA-liposomes and J774 macrophages, thereby facilitating UA penetration into cells. Considering such a process as ruling the Mycobacterium-transfection by magrophages, we could state that associating UA with this DDS leads to an improvement in its antimycobacterial activity.

Therapeutic effect of DNA vaccine encoding the 60-kDa-heat shock protein from Paracoccidoides brasiliensis on experimental paracoccidioidomycosis in mice.

Paracoccidioidomycosis (PCM) is a systemic mycosis autochthonous to Latin America and endemic to Brazil, which has the majority of the PCM cases. PCM is acquired through the inhalation of propagules of fungi from genus Paracoccidioides spp. and mainly affects the lungs. We have previously shown that P. brasiliensis-infected mice treated with single-dose of recombinant 60-kDa-heat shock protein from P. brasiliensis (rPbHsp60) had a worsening infection in comparison to animals only infected. In this study, we investigate whether the treatment of infected mice with PB_HSP60 gene cloned into a plasmid (pVAX1-PB_HSP60) would result in efficient immune response and better control of the disease. The harmful impact of single-dose therapy with protein was not seen with plasmid preparations. Most importantly, three doses of pVAX1-PB_HSP60 and protein induced a beneficial effect in experimental PCM with a reduction in fungal load and lung injury when compared with infected mice treated with pVAX1 or PBS. The increase of the cytokines IFN-γ, TNF, and IL-17 and the decrease of IL-10 observed after treatment with three doses of pVAX1-PB_HSP60 appears to be responsible for the control of infection. These results open perspectives of the therapeutic use of Hsp60 in PCM.

Protection against tuberculosis by a single intranasal administration of DNA-hsp65 vaccine complexed with cationic liposomes.

BACKGROUND: The greatest challenges in vaccine development include optimization of DNA vaccines for use in humans, creation of effective single-dose vaccines, development of delivery systems that do not involve live viruses, and the identification of effective new adjuvants. Herein, we describe a novel, simple technique for efficiently vaccinating mice against tuberculosis (TB). Our technique consists of a single-dose, genetic vaccine formulation of DNA-hsp65 complexed with cationic liposomes and administered intranasally. RESULTS: We developed a novel and non-toxic formulation of cationic liposomes, in which the DNA-hsp65 vaccine was entrapped (ENTR-hsp65) or complexed (COMP-hsp65), and used to immunize mice by intramuscular or intranasal routes. Although both liposome formulations induced a typical Th1 pattern of immune response, the intramuscular route of delivery did not reduce the number of bacilli. However, a single intranasal immunization with COMP-hsp65, carrying as few as 25 microg of plasmid DNA, leads to a remarkable reduction of the amount of bacilli in lungs. These effects were accompanied by increasing levels of IFN-gamma and lung parenchyma preservation, results similar to those found in mice vaccinated intramuscularly four times with naked DNA-hsp65 (total of 400 microg). CONCLUSION: Our objective was to overcome the significant obstacles currently facing DNA vaccine development. Our results in the mouse TB model showed that a single intranasal dose of COMP-hsp65 elicited a cellular immune response that was as strong as that induced by four intramuscular doses of naked-DNA. This formulation allowed a 16-fold reduction in the amount of DNA administered. Moreover, we demonstrated that this vaccine is safe, biocompatible, stable, and easily manufactured at a low cost. We believe that this strategy can be applied to human vaccines to TB in a single dose or in prime-boost protocols, leading to a tremendous impact on the control of this infectious disease.

A DNA vaccine against tuberculosis based on the 65 kDa heat-shock protein differentially activates human macrophages and dendritic cells.

BACKGROUND: A number of reports have demonstrated that rodents immunized with DNA vaccines can produce antibodies and cellular immune responses presenting a long-lasting protective immunity. These findings have attracted considerable interest in the field of DNA vaccination. We have previously described the prophylactic and therapeutic effects of a DNA vaccine encoding the Mycobacterium leprae 65 kDa heat shock protein (DNA-HSP65) in a murine model of tuberculosis. As DNA vaccines are often less effective in humans, we aimed to find out how the DNA-HSP65 stimulates human immune responses. METHODS: To address this question, we analysed the activation of both human macrophages and dendritic cells (DCs) cultured with DNA-HSP65. Then, these cells stimulated with the DNA vaccine were evaluated regarding the expression of surface markers, cytokine production and microbicidal activity. RESULTS: It was observed that DCs and macrophages presented different ability to uptake DNA vaccine. Under DNA stimulation, macrophages, characterized as CD11b+/CD86+/HLA-DR+, produced high levels of TNF-alpha, IL-6 (pro-inflammatory cytokines), and IL-10 (anti-inflammatory cytokine). Besides, they also presented a microbicidal activity higher than that observed in DCs after infection with M. tuberculosis. On the other hand, DCs, characterized as CD11c+/CD86+/CD123-/BDCA-4+/IFN-alpha-, produced high levels of IL-12 and low levels of TNF-alpha, IL-6 and IL-10. Finally, the DNA-HSP65 vaccine was able to induce proliferation of peripheral blood lymphocytes. CONCLUSION: Our data suggest that the immune response is differently activated by the DNA-HSP65 vaccine in humans. These findings provide important clues to the design of new strategies for using DNA vaccines in human immunotherapy.

Gr-1+ cells play an essential role in an experimental model of disseminated histoplasmosis.

Recent studies have shown the participation of Gr-1(+) cells in many types of infections; however, the role played by these cells in the immune response to fungal pathogens is controversial. In this study we determined whether Gr-1(+) cells are involved in the protective immune response in systemic Histoplasma capsulatum infection. Depletion of Gr-1(+) cells using the monoclonal antibody (MAb) RB6-8C5 increased histoplasmosis severity and inhibited the subsequent development of a protective immune response. In addition to the increased fungal burden in lungs and spleens, the Th1 response was found to be unbalanced in these mice and the suppression of the cellular immune response seemed to be associated with increased nitric oxide production. Taken together, these results indicate that Gr-1(+) cell depletion at the beginning of infection allows yeast multiplication and increases mice mortality. This study improves the understanding of the role of Gr-1(+) cells on the protective immunity in histoplasmosis.

Inhibition of leukotriene biosynthesis abrogates the host control of Mycobacterium tuberculosis.

Leukotrienes produced from arachidonic acid by the action of 5-lipoxygenase (5-LO) are classical mediators of inflammatory responses. Recently, it has been demonstrated that leukotrienes also play an important role in host defense against microorganisms. In vitro studies have shown that leukotrienes augmented the anti-mycobacterial activity of neutrophils. In this study, we examined the role of leukotrienes in regulating host response and cytokine generation in a murine model of tuberculosis. Administration of the 5-LO pathway inhibitor MK 886, which reduced lung levels of both the leukotriene B(4) and the anti-inflammatory substance lipoxin A(4) by approximately 50%, increased 60-day mortality from 14% to approximately 57% in Mycobacterium tuberculosis-infected mice, and increased lung bacterial burden by approximately 15-fold. Although MK 886-treated animals exhibited no reduction in pulmonary leukocyte accumulation, they did manifest reduced levels of nitric oxide generation and of the protective type 1 cytokines interleukin-12 and gamma interferon. Together our results demonstrate that 5-LO pathway product(s) - presumably leukotrienes - positively regulate protective Th1 responses against mycobacterial infection in vivo. Moreover, the immunosuppressive phenotype in infected mice observed with MK 886 is most consistent with inhibition of an activator (LTB(4)) rather than a suppressor (LXA(4)) of antimicrobial defense, suggesting the major effect of leukotrienes.

Improve protective efficacy of a TB DNA-HSP65 vaccine by BCG priming.

Vaccines are considered by many to be one of the most successful medical interventions against infectious diseases. But many significant obstacles remain, such as optimizing DNA vaccines for use in humans or large animals. The amount of doses, route and easiness of administration are also important points to consider in the design of new DNA vaccines. Heterologous prime-boost regimens probably represent the best hope for an improved DNA vaccine strategy. In this study, we have shown that heterologous prime-boost vaccination against tuberculosis (TB) using intranasal BCG priming/DNA-HSP65 boosting (BCGin/DNA) provided significantly greater protection than that afforded by a single subcutaneous or intranasal dose of BCG. In addition, BCGin/DNA immunization was also more efficient in controlling bacterial loads than were the other prime-boost schedules evaluated or three doses of DNA-HSP65 as a naked DNA. The single dose of DNA-HSP65 booster enhanced the immunogenicity of a single subcutaneous BCG vaccination, as evidenced by the significantly higher serum levels of anti-Hsp65 IgG2a Th1-induced antibodies, as well as by the significantly greater production of IFN-gamma by antigen-specific spleen cells. The BCG prime/DNA-HSP65 booster was also associated with better preservation of lung parenchyma. The improvement of the protective effect of BCG vaccine mediated by a DNA-HSP65 booster suggests that our strategy may hold promise as a safe and effective vaccine against TB.

Tissue distribution of DNA-Hsp65/TDM-loaded PLGA microspheres and uptake by phagocytic cells.

This study aimed to demonstrate that microspheres, used as delivery vehicle of DNA-Hsp65/TDM [plasmid DNA encoding heat shock protein 65 (Hsp65) coencapsulated with trehalose dimycolate (TDM) into PLGA microspheres], are widely spread among several organs after intramuscular administration in BALB/c mice. In general, we showed that these particles were phagocytosed by antigen presenting cells, such as macrophages and dendritic cells. Besides, it was demonstrated herein that draining lymph node cells presented a significant increase in the number of cells expressing costimulatory molecules (CD80 and CD86) and MHC class II, and also that the administration of the DNA-Hsp65/TDM and vector/TDM formulations resulted in the up-regulation of CD80, CD86 and MHC class II expression when compared to control formulations (vector/TDM and empty). Regarding the intracellular trafficking we observed that following phagocytosis, the microspheres were not found in the late endosomes and/or lysosomes, until 15 days after internalization, and we suggest that these constructions were hydrolysed in early compartments. Overall, these data expand our knowledge on PLGA [poly (lactic-co-glycolic acid)] microspheres as gene carriers in vaccination strategies, as well as open perspectives for their potential use in clinical practice.

Genetic vaccine for tuberculosis (pVAXhsp65) primes neonate mice for a strong immune response at the adult stage.

BACKGROUND: Vaccination of neonates is generally difficult due to the immaturity of the immune system and consequent higher susceptibility to tolerance induction. Genetic immunization has been described as an alternative to trigger a stronger immune response in neonates, including significant Th1 polarization. In this investigation we analysed the potential use of a genetic vaccine containing the heat shock protein (hsp65) from Mycobacterium leprae (pVAXhsp65) against tuberculosis (TB) in neonate mice. Aspects as antigen production, genomic integration and immunogenicity were evaluated. METHODS: Hsp65 message and genomic integration were evaluated by RT-PCR and Southern blot, respectively. Immunogenicity of pVAXhsp65 alone or combined with BCG was analysed by specific induction of antibodies and cytokines, both quantified by ELISA. RESULTS: This DNA vaccine was transcribed by muscular cells of neonate mice without integration into the cellular genome. Even though this vaccine was not strongly immunogenic when entirely administered (three doses) during early animal's life, it was not tolerogenic. In addition, pVAXhsp65 and BCG were equally able to prime newborn mice for a strong and mixed immune response (Th1 + Th2) to pVAXhsp65 boosters administered later, at the adult life. CONCLUSION: These results suggest that pVAXhsp65 can be safely used as a priming stimulus in neonate animals in prime-boost similar strategies to control TB. However, priming with BCG or pVAXhsp65, directed the ensuing immune response triggered by an heterologous or homologous booster, to a mixed Th1/Th2 pattern of response. Measures as introduction of IL-12 or GM-CSF genes in the vaccine construct or even IL-4 neutralization, are probably required to increase the priming towards Th1 polarization to ensure control of tuberculosis infection.