Lúcia de Paula

Comparison of different delivery systems of DNA vaccination for the induction of protection against tuberculosis in mice and guinea pigs

The great challenges for researchers working in the field of vaccinology are optimizing DNA vaccines for use in humans or large animals and creating effective single-dose vaccines using appropriated controlled delivery systems. Plasmid DNA encoding the heat-shock protein 65 (hsp65) (DNAhsp65) has been shown to induce protective and therapeutic immune responses in a murine model of tuberculosis (TB). Despite the success of naked DNAhsp65-based vaccine to protect mice against TB, it requires multiple doses of high amounts of DNA for effective immunization. In order to optimize this DNA vaccine and simplify the vaccination schedule, we coencapsulated DNAhsp65 and the adjuvant trehalose dimycolate (TDM) into biodegradable poly (DL-lactide-co-glycolide) (PLGA) microspheres for a single dose administration. Moreover, a single-shot prime-boost vaccine formulation based on a mixture of two different PLGA microspheres, presenting faster and slower release of, respectively, DNAhsp65 and the recombinant hsp65 protein was also developed. These formulations were tested in mice as well as in guinea pigs by comparison with the efficacy and toxicity induced by the naked DNA preparation or BCG. The single-shot prime-boost formulation clearly presented good efficacy and diminished lung pathology in both mice and guinea pigs.

Mast cells modulate pulmonary acute inflammation and host defense in a murine model of tuberculosis.

BACKGROUND Mast cells (MCs) participate in host resistance to several pathogens, but little is known about the role played by MCs in Mycobacterium tuberculosis infection. METHODS Compound 48/80 (C48/80)-treated mice and nontreated mice were infected intratracheally with 1 x 10(5) viable M. tuberculosis bacilli (MTB; strain H37Rv). RESULTS Infected BALB/c mice developed an acute pulmonary inflammation and had higher levels of tumor necrosis factor- alpha , interleukin-1, keratinocyte-derived chemokine, monocyte chemotactic protein-1, and macrophage inflammatory protein-2 in the lungs by day 15. In vivo degranulation of MCs by C48/80 led to a reduction in the inflammatory reaction that was associated with a marked decline in lung proinflammatory cytokine and chemokine levels. The magnitude of the cellular immune response was also partially impaired in infected mice treated with C48/80. The number of Mycobacteria bacilli recovered from the lungs of infected mice treated with C48/80 was 1 log higher than that recovered from untreated infected mice. C48/80 treatment attenuated the granulomatous inflammation in the lung parenchyma seen in untreated MTB-infected mice. CONCLUSIONS These findings suggest that MCs participate in host defense against M. tuberculosis infection through the production and secretion of cytokines and chemokines that play a role in the recruitment and activation of inflammatory cells in this experimental model.

Histamine modulates mast cell degranulation through an indirect mechanism in a model IgE‐mediated reaction

Histamine is released in inflammatory reactions and exerts an immunoregulatory function on cells present in the microenvironment. In this study, we compared the effect of histamine on degranulation of mast cells derived from animals bearing a parasitic infection with those from uninfected animals. Peritoneal mast cells (PMC) were obtained 24 days after infection of Wistar rats with Toxocara canis. The degree of degranulation was assessed either morphologically or by measuring the release of β‐hexosaminidase and TNF‐α. Non‐purified PMC or mast cells immunomagnetically purified with mAb AA4 were used. An increase in degranulation of non‐purified mast cells from infected animals was observed after incubation with histamine in vitro or when histamine was injected into the peritoneal cavity. When a purified mast cell population was used, this effect was no longer observed. Supernatants from spleen cells stimulated with histamine induced degranulation of purified mast cells, and again, this was potentiated with PMC from infected animals. However, when supernatants from peritoneal macrophages similarly stimulated were used, a reduction in the degranulation of PMC from infected animals was observed. Our results suggest that histamine may act as a regulator of mast cell degranulation, thus modulating inflammatory responses due to infection with certain parasites.

Análise comparativa randomizada entre dois tipos de sistema de aspiração traqueal em recém-nascidos

OBJECTIVE: The objective of this study was to quantify and compare variations of oxygen saturation during the whole suction procedure (before, during and after), using two types of suction systems: open (OSS) and closed (CSS). METHODS: A controlled, randomized prospective study was carried out with 39 newborn of gestational ages > to 34 weeks using mechanical ventilation devices with a continuous flow, limited to pressure and cycled in time. Newborn were classified in two groups according to the ventilator parameters. Group I was ventilated using PEEP > to 5 cmH2O and MAP > to 8 cmH2O and Group II using PEEP < of 5 cmH2O and MAP < than 8 cmH2O. RESULTS: No statistically significant differences among the studied variable (oxygen saturation) were found in the population under study, when the two suction systems open and closed were compared , in the two groups. The oxygen saturation was statistically high after the tracheal suction in both groups. CONCLUSION: Both tracheal suction systems can be used without any drawbacks of the OSS in relation to the CSS, since the casuistry is similar to the one presented in this study.

Atelectasia pós-extubação em recém-nascidos com doenças cirúrgicas: relato de dois casos de uso de cateter nasal de alto fluxo

Atelectasis is a pulmonary disorder that lengthens the hospitalization time of newborns in intensive care units, resulting in increased morbidity among these infants. High-flow nasal cannulae have been used in newborns to prevent atelectasis and/or expand pulmonary regions affected by atelectasis; however, to date, no evidence-based data regarding this approach have been reported. In this paper, we report on the cases of two male newborn patients. The first and second patients described in this report were hospitalized for a neurosurgical procedure and the treatment of abdominal disease, respectively, and were subjected to invasive mechanical ventilation for 4 and 36 days, respectively. After extubation, these patients continued receiving oxygen therapy but experienced clinical and radiological worsening typical of atelectasis. In both cases, by 24 hours after the implantation of an high-flow nasal cannulae to provide noninvasive support, radiological examinations revealed the complete resolution of atelectasis. In these cases, the use of an high-flow nasal cannulae was effective in reversing atelectasis. Thus, this approach may be utilized as a supplemental noninvasive ventilatory therapy to avoid unnecessary intubation.