Arlete A. M. Coelho-Castelo

Immunotherapy with plasmid DNA encoding mycobacterial hsp65 in association with chemotherapy is a more rapid and efficient form of treatment for tuberculosis in mice

Tuberculosis (TB) remains a threat for public health, killing around 3 million people a year. Despite the fact that most cases can be cured with antibiotics, the treatment is long and patients relapse if chemotherapy is not continued for at least 6 months. Thus, a better characterization of the working principles of the immune system in TB and identification of new immunotherapeutic products for the development of shorter regimens of treatment are essential to achieve an effective management of this disease. In the present work, we demonstrate that immunotherapy with a plasmid DNA encoding the Mycobacterium leprae 65 kDa heat-shock protein (hsp65) in order to boost the efficiency of the immune system, is a valuable adjunct to antibacterial chemotherapy to shorten the duration of treatment, improve the treatment of latent TB infection and be effective against multidrug-resistant bacilli (MDR-TB). We also showed that the use of DNA-hsp65 alone or in combination with other drugs influence the pathway of the immune response or other types of inflammatory responses and should augment our ability to alter the course of immune response/inflammation as needed, evidencing an important target for immunization or drug intervention.

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

BackgroundmRNAs 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.ResultsWe 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).ConclusionsTaken 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.

Immune regulatory effect of pHSP65 DNA therapy in pulmonary tuberculosis: activation of CD8+ cells, interferon-γ recovery and reduction of lung injury

A DNA vaccine based on the heat‐shock protein 65 Mycobacterium leprae gene (pHSP65) presented a prophylactic and therapeutic effect in an experimental model of tuberculosis. In this paper, we addressed the question of which protective mechanisms are activated in Mycobacterium tuberculosis‐infected mice after immune therapy with pHSP65. We evaluated activation of the cellular immune response in the lungs of infected mice 30 days after infection (initiation of immune therapy) and in those of uninfected mice. After 70 days (end of immune therapy), the immune responses of infected untreated mice, infected pHSP65‐treated mice and infected pCDNA3‐treated mice were also evaluated. Our results show that the most significant effect of pHSP65 was the stimulation of CD8+ lung cell activation, interferon‐γ recovery and reduction of lung injury. There was also partial restoration of the production of tumour necrosis factor‐α. Treatment with pcDNA3 vector also induced an immune stimulatory effect. However, only infected pHSP65‐treated mice were able to produce significant levels of interferon‐γ and to restrict the growth of bacilli.

Comparison of different delivery systems of vaccination for the induction of protection against tuberculosis in mice

The way to deliver antigens and cellular requirements for long-lasting protection against tuberculosis are not known. Immunizations with mycobacterial 65 kDa heat shock protein (hsp65) expressed from J774-hsp65 cells (antigen-presenting cells that endogenously produce hsp65 antigen) or from plasmid DNA, or with the protein entrapped in cationic liposomes, can each give protective immunity similar to that obtained from live Bacillus Calmette Guérin (BCG), whereas injecting the protein in Freunds incomplete adjuvant (FIA) has minimal effect. Protective procedures elicited high frequencies of antigen-reactive alphabeta T cells with CD4+/CD8- and CD8+/CD4- phenotypes. Protection correlated with the abundance of hsp65-dependent cytotoxic CD8+/CD4-/CD44hi cells. The frequency of these cells and the level of protection declined during 8 months after J774-hsp65 or liposome-mediated immunization with hsp65 protein but were sustained or steadily increased over this period after hsp65-DNA or BCG immunizations. IFN-gamma predominated over IL-4 among the hsp65-reactive CD8+/CD4- and CD4+/CD8- populations after J774-hsp65-, hsp65-liposome-, and hsp65-DNA-mediated immunizations, but similar levels of these cytokines prevailed after BCG vaccination.

B-lymphocytes in bone marrow or lymph nodes can take up plasmid DNA after intramuscular delivery.

Nucleic acid vaccines are an attractive alternative to conventional protein vaccines because of their ability to induce de novo production of antigens in a given tissue after DNA delivery. Although DNA vaccines are highly effective in inducing both cell-mediated and humoral immunity, little is known about the many cell types involved in plasmid DNA uptake in vivo. Here we demonstrate, for the first time, that plasmid DNA can be taken up by both bone marrow and lymph node B cells after intramuscular immunization. Plasmid DNA was also detected in CD11b+ and CD11c+ cells. This phenomenon was not restricted to plasmid DNA encoding mycobacterial 65-kd heat shock protein (pcDNA3-hsp65) because we observed similar results with plasmid-encoding green fluorescent protein (GFP-pEGFP-2C). In addition to plasmid DNA uptake, B cells also express the encoded protein, suggesting that B cells play a role in the immune response after DNA immunization. The biodistribution of plasmid DNA in B cells opens a new perspective in B-cell gene therapy for the in vivo use of plasmid DNA.

The synergy between structural stability and DNA-binding controls the antibody production in EPC/DOTAP/DOPE liposomes and DOTAP/DOPE lipoplexes

We present a comparative study of the physico-chemical properties, in vitro cytotoxicity and in vivo antibody production of surface-complexed DNA in EPC/DOTAP/DOPE (50/25/25% molar) liposomes and DOTAP/DOPE (50/50% molar) lipoplexes. The study aims to correlate the biological behavior and structural properties of the lipid carriers. We used DNA-hsp65, whose naked action as a gene vaccine against tuberculosis has already been demonstrated. Additionally, surface-complexed DNA-hsp65 in EPC/DOTAP/DOPE (50/25/25% molar) liposomes was effective as a single-dose tuberculosis vaccine. The results obtained showed that the EPC inclusion stabilized the DOTAP/DOPE structure, producing higher melting temperature and lower zeta potential despite a close mean hydrodynamic diameter. Resemblances in morphologies were identified in both structures, although a higher fraction of loaded DNA was not electrostatically bound in EPC/DOTAP/DOPE. EPC also induced a striking reduction in cytotoxicity, similar to naked DNA-hsp65. The proper immune response lead to a polarized antibody production of the IgG2a isotype, even for the cytotoxic DOTAP/DOPE. However, the antibody production was detected at 15 and 30 days for DOTAP/DOPE and EPC/DOTAP/DOPE, respectively. Therefore, the in vivo antibody production neither correlates with the in vitro cytotoxicity, nor with the structural stability alone. The synergistic effect of the structural stability and DNA electrostatic binding upon the surface of structures account for the immunological effects. By adjusting the composition to generate proper packing and cationic lipid/DNA interaction, we allow for the optimization of liposome formulations for required immunization or gene therapy. In a specific manner, our results contribute to studies on the tuberculosis therapy and vaccination.

HSP65 DNA as therapeutic strategy to treat experimental paracoccidioidomycosis

The conventional treatment for paracoccidioidomycosis, the most prevalent mycosis in Latin America, involves long periods of therapy resulting in sequels and high frequency of relapses. The search for new alternatives of treatment is necessary. Previously, we have demonstrated that the hsp65 gene from Mycobacterium leprae shows prophylactic effects against murine paracoccidioidomycosis. Here, we tested the DNAhsp65 immunotherapy in BALB/c mice infected with Paracoccidioides brasiliensis, the agent of paracoccidioidomycosis. We observed an increase of Th1 cytokines accompanied by a reduction in fungal burden and pulmonary injury. These results provide new prospects for immunotherapy of paracoccidioidomycosis and other mycoses.

Protective efficacy of different strategies employing Mycobacterium leprae heat-shock protein 65 against tuberculosis

Background: Tuberculosis is a major threat to human health. The high disease burden remains unaffected and the appearance of extremely drug-resistant strains in different parts of the world argues in favor of the urgent need for a new effective vaccine. One of the promising candidates is heat-shock protein 65 when used as a genetic vaccine (DNAhsp65). Nonetheless, there are substantial data indicating that BCG, the only available anti-TB vaccine for clinical use, provides other important beneficial effects in immunized infants. Methods: We compared the protective efficacy of BCG and Hsp65 antigens in mice using different strategies: i) BCG, single dose subcutaneously; ii) naked DNAhsp65, four doses, intramuscularly; iii) liposomes containing DNAhsp65, single dose, intranasally; iv) microspheres containing DNAhsp65 or rHsp65, single dose, intramuscularly; and v) prime–boost with subcutaneous BCG and intramuscular DNAhsp65. Results: All the immunization protocols were able to protect mice against infection, with special benefits provided by DNAhsp65 in liposomes and prime–boost strategies. Conclusion: Among the immunization protocols tested, liposomes containing DNAhsp65 represent the most promising strategy for the development of a new anti-TB vaccine.

Comprehensive gene expression profiling in lungs of mice infected with Mycobacterium tuberculosis following DNAhsp65 immunotherapy

The continued increase in tuberculosis (TB) rates and the appearance of extremely resistant Mycobacterium tuberculosis strains (XDR‐TB) worldwide are some of the great problems of public health. In this context, DNA immunotherapy has been proposed as an effective alternative that could circumvent the limitations of conventional drugs. Nonetheless, the molecular events underlying these therapeutic effects are poorly understood.

Endocytosis of DNA-Hsp65 alters the pH of the late endosome/lysosome and interferes with antigen presentation.

Background Experimental models using DNA vaccine has shown that this vaccine is efficient in generating humoral and cellular immune responses to a wide variety of DNA-derived antigens. Despite the progress in DNA vaccine development, the intracellular transport and fate of naked plasmid DNA in eukaryotic cells is poorly understood, and need to be clarified in order to facilitate the development of novel vectors and vaccine strategies. Methodology and Principal Findings Using confocal microscopy, we have demonstrated for the first time that after plasmid DNA uptake an inhibition of the acidification of the lysosomal compartment occurs. This lack of acidification impaired antigen presentation to CD4 T cells, but did not alter the recruitment of MyD88. The recruitment of Rab 5 and Lamp I were also altered since we were not able to co-localize plasmid DNA with Rab 5 and Lamp I in early endosomes and late endosomes/lysosomes, respectively. Furthermore, we observed that the DNA capture process in macrophages was by clathrin-mediated endocytosis. In addition, we observed that plasmid DNA remains in vesicles until it is in a juxtanuclear location, suggesting that the plasmid does not escape into the cytoplasmic compartment. Conclusions and Significance Taken together our data suggests a novel mechanism involved in the intracellular trafficking of plasmid DNA, and opens new possibilities for the use of lower doses of plasmid DNA to regulate the immune response.