Theranostic applications of phage display to control leishmaniasis: selection of biomarkers for serodiagnostics, vaccination, and immunotherapy

AbstractPhage display is a high-throughput subtractive proteomic technology used for the generation and screening of large peptide and antibody libraries. It is based on the selection of phage-fused surface-exposed peptides that recognize specific ligands and demonstrate desired functionality for diagnostic and therapeutic purposes. Phage display has provided unmatched tools for controlling viral, bacterial, fungal, and parasitic infections, and allowed identification of new therapeutic targets to treat cancer, metabolic diseases, and other chronic conditions. This review presents recent advancements in serodiagnostics and prevention of leishmaniasis -an important tropical parasitic disease- achieved using phage display for the identification of novel antigens with improved sensitivity and specificity. Our focus is on theranostics of visceral leishmaniasis with the aim to develop biomarker candidates exhibiting both diagnostic and therapeutic potential to fight this important, yet neglected, tropical disease.

Comparative study of lymphocytes from individuals that were vaccinated and unvaccinated against the pandemic 2009-2011 H1N1 influenza virus in Southern Brazil

ABSTRACTINTRODUCTION:While no single factor is sufficient to guarantee the success of influenza vaccine programs, knowledge of the levels of immunity in local populations is critical. Here, we analyzed influenza immunity in a population from Southern Brazil, a region with weather conditions that are distinct from those in the rest of country, where influenza infections are endemic, and where greater than 50% of the population is vaccinated annually.METHODS:Peripheral blood mononuclear cells were isolated from 40 individuals. Of these, 20 had received the H1N1 vaccine, while the remaining 20 were unvaccinated against the disease. Cells were stimulated in vitro with the trivalent post-pandemic influenza vaccine or with conserved major histocompatibility complex I (MHC I) peptides derived from hemagglutinin and neuraminidase. Cell viability was then analyzed by [3-(4,5-dimethylthiazol-2-yl)-2,5- diphenyltetrazolium bromide)]-based colorimetric assay (MTT), and culture supernatants were assayed for helper T type 1 (Th1) and Th2-specific cytokine levels.RESULTS:Peripheral blood lymphocytes from vaccinated, but not unvaccinated, individuals exhibited significant proliferation in vitro in the presence of a cognate influenza antigen. After culturing with vaccine antigens, cells from vaccinated individuals produced similar levels of interleukin (IL)-10 and interferon (IFN)-γ, while those from unvaccinated individuals produced higher levels of IFN-γ than of IL-10.CONCLUSIONS:Our data indicate that peripheral blood lymphocytes from vaccinated individuals are stimulated upon encountering a cognate antigen, but did not support the hypothesis that cross-reactive responses related to previous infections can ameliorate the immune response. Moreover, monitoring IL-10 production in vaccinated individuals could comprise a valuable tool for predicting disease evolution.

The Role of B-Type Natriuretic Peptide in the Diagnosis of Congestive Heart Failure in Patients Presenting to an Emergency Department with Dyspnea

OBJECTIVE: To determine the utility of B-type natriuretic peptide (BNP) in the diagnosis of congestive heart failure (CHF) in patients presenting with dyspnea to an emergency department (ED). METHODS: Seventy patients presenting with dyspnea to an ED from April to July 2001 were included in the study. Mean age was 72±16 years and 33 (47%) were male. BNP was measured in all patients at the moment of admission to the ED. Emergency-care physicians, blinded to BNP values, were required to assign a probable initial diagnosis. A cardiologist retrospectively reviewed the data (blinded to BNP measurements) and assigned a definite diagnosis, which was considered the gold standard for assessing the diagnostic performance of BNP. RESULTS: The mean BNP concentration was higher in patients with CHF (n=36) than in those with other diagnoses (990±550 vs 80±67 pg/mL, p<0.0001). Patients with systolic dysfunction had higher BNP levels than those with preserved systolic function (1,180±641 vs 753±437 pg/mL, p=0.03). At a blood concentration of 200 pg/mL, BNP showed a sensitivity of 100%, specificity of 97.1%, positive predictive value of 97.3%, and negative predictive value of 100%. The application of BNP could have potentially corrected all 16 cases in which the diagnosis was missed by the emergency department physician. CONCLUSION: BNP measurement is a useful tool in the diagnosis of CHF in patients presenting to the ED with dyspnea.

Assessing Strategies for Heart Failure with Preserved Ejection Fraction at the Outpatient Clinic

Background: Heart failure with preserved ejection fraction (HFPEF) is the most common form of heart failure (HF), its diagnosis being a challenge to the outpatient clinic practice. Objective: To describe and compare two strategies derived from algorithms of the European Society of Cardiology Diastology Guidelines for the diagnosis of HFPEF. Methods: Cross-sectional study with 166 consecutive ambulatory patients (67.9±11.7 years; 72% of women). The strategies to confirm HFPEF were established according to the European Society of Cardiology Diastology Guidelines criteria. In strategy 1 (S1), tissue Doppler echocardiography (TDE) and electrocardiography (ECG) were used; in strategy 2 (S2), B-type natriuretic peptide (BNP) measurement was included. Results: In S1, patients were divided into groups based on the E/E'ratio as follows: GI, E/E'> 15 (n = 16; 9%); GII, E/E'8 to 15 (n = 79; 48%); and GIII, E/E'< 8 (n = 71; 43%). HFPEF was confirmed in GI and excluded in GIII. In GII, TDE [left atrial volume index (LAVI) ≥ 40 mL/m2; left ventricular mass index LVMI) > 122 for women and > 149 g/m2 for men] and ECG (atrial fibrillation) parameters were assessed, confirming HFPEF in 33 more patients, adding up to 49 (29%). In S2, patients were divided into three groups based on BNP levels. GI (BNP > 200 pg/mL) consisted of 12 patients, HFPEF being confirmed in all of them. GII (BNP ranging from 100 to 200 pg/mL) consisted of 20 patients with LAVI > 29 mL/m2, or LVMI ≥ 96 g/m2 for women or ≥ 116 g/m2 for men, or E/E'≥ 8 or atrial fibrillation on ECG, and the diagnosis of HFPEF was confirmed in 15. GIII (BNP < 100 pg/mL) consisted of 134 patients, 26 of whom had the diagnosis of HFPEF confirmed when GII parameters were used. Measuring BNP levels in S2 identified 4 more patients (8%) with HFPEF as compared with those identified in S1. Conclusion: The association of BNP measurement and TDE data is better than the isolated use of those parameters. BNP can be useful in identifying patients whose diagnosis of HF had been previously excluded based only on TDE findings.

Soluble ST2 Testing: A Promising Biomarker in the Management of Heart Failure

Abstract ST2 is a member of the interleukin-1 receptor family biomarker and circulating soluble ST2 concentrations are believed to reflect cardiovascular stress and fibrosis. Recent studies have demonstrated soluble ST2 to be a strong predictor of cardiovascular outcomes in both chronic and acute heart failure. It is a new biomarker that meets all required criteria for a useful biomarker. Of note, it adds information to natriuretic peptides (NPs) and some studies have shown it is even superior in terms of risk stratification. Since the introduction of NPs, this has been the most promising biomarker in the field of heart failure and might be particularly useful as therapy guide.