Mycobacterium tuberculosis induces delayed lipid droplet accumulation in dendritic cells depending on bacterial viability and virulence.

Tuberculosis remains a global health threat with high morbidity. Dendritic cells (DCs) participate in the acute and chronic inflammatory responses to Mycobacterium tuberculosis (Mtb) by directing the adaptive immune response and are present in lung granulomas. In macrophages, the interaction of lipid droplets (LDs) with mycobacteria-containing phagosomes is central to host-pathogen interactions. However, the data available for DCs are still a matter of debate. Here, we reported that bone marrow-derived DCs (BMDCs) were susceptible to Mtb infection and replication at similar rate to macrophages. Unlike macrophages, the analysis of gene expression showed that Mtb infection induced a delayed increase in lipid droplet-related genes and proinflammatory response. Hence, LD accumulation has been observed by high-content imaging in late periods. Infection of BMDCs with killed H37Rv demonstrated that LD accumulation depends on Mtb viability. Moreover, infection with the attenuated strains H37Ra and Mycobacterium bovis-BCG induced only an early transient increase in LDs, whereas virulent Mtb also induced delayed LD accumulation. In addition, infection with the BCG strain with the reintroduced virulence RD1 locus induced higher LD accumulation and bacterial replication when compared to parental BCG. Collectively, our data suggest that delayed LD accumulation in DCs is dependent on mycobacterial viability and virulence.

Safety and Immunogenicity of an In Vivo Muscle Electroporation Delivery System for DNA-hsp65 Tuberculosis Vaccine in Cynomolgus Monkeys.

A Bacille Calmette-Guérin (BCG) is still the only licensed vaccine for the prevention of tuberculosis, providing limited protection against Mycobacterium tuberculosis infection in adulthood. New advances in the delivery of DNA vaccines by electroporation have been made in the past decade. We evaluated the safety and immunogenicity of the DNA-hsp65 vaccine administered by intramuscular electroporation (EP) in cynomolgus macaques. Animals received three doses of DNA-hsp65 at 30-day intervals. We demonstrated that intramuscular electroporated DNA-hsp65 vaccine immunization of cynomolgus macaques was safe, and there were no vaccine-related effects on hematological, renal, or hepatic profiles, compared to the pre-vaccination parameters. No tuberculin skin test conversion nor lung X-ray alteration was identified. Further, low and transient peripheral cellular immune response and cytokine expression were observed, primarily after the third dose of the DNA-hsp65 vaccine. Electroporated DNA-hsp65 vaccination is safe but provides limited enhancement of peripheral cellular immune responses. Preclinical vaccine trials with DNA-hsp65 delivered via EP may include a combination of plasmid cytokine adjuvant and/or protein prime-boost regimen, to help the induction of a stronger cellular immune response.

A protocol update for the Selenium Treatment and Chagasic Cardiomyopathy (STCC) trial.

Several studies evaluating clinical forms of chronic Chagas disease show that about one-third of patients present cardiac involvement. Heart failure, sudden death and cardioembolic stroke are the main mechanisms of death in Chagas heart disease. The impact of specific etiologic treatment on the prognosis of patients with chronic Chagas heart disease is very limited regardless of the presence or absence of heart failure. Patients with symptomatic Chagas heart disease present serum selenium (Se) levels lower than patients without Chagas heart disease. Moreover, Se supplementation in animal models showed promising results. The aim of this trial is to estimate the effect of Se treatment on prevention of heart disease progression in patients with Chagas cardiomyopathy. However, we had to introduce some protocol modifications in order to keep trial feasibility, as follows: the primary outcome was restricted to left ventricular ejection fraction as a continuous variable, excluding disease progression; the follow-up period was decreased from 5 years to 1 year, an adjustment that might increase the participation rate of our study; the superior age limit was increased from 65 to 75 years; and diabetes mellitus was no longer considered an exclusion criterion. All of these protocol modifications were extensively debated by the research team enrolled in the design, recruitment and conduction of the clinical trial to guarantee a high scientific quality. TRIAL REGISTRATION: Clinical Trials.gov, NCT00875173 . Registered on 20 October 2008.