Alexander Leonardo Silva-Junior

Dr. Alexander Leonardo Silva-Junior

Centro Universitário do Norte, Manaus, Amazonas, Brazil
+3
orcid

Research Focus & Metrics

Academic Career Length

8Years (2019-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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11 March 2021 in Frontiers in Immunology
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Journal Article
Open access
ASAlexander Leonardo Silva-Junior
Alexander Leonardo Silva-Junior
NGNadja Pinto Garcia
Nadja Pinto Garcia
ECEvilázio Cunha Cardoso
Evilázio Cunha Cardoso
SDStephanny Dias
Stephanny Dias
ATAndrea Monteiro Tarragô
Andrea Monteiro Tarragô
AMAdriana Malheiro
Adriana Malheiro
Sickle Cell Anemia (SCA) is the most common genetic disorder around the world. The mutation in the β-globin gene is responsible for a higher hemolysis rate, with further involvement of immunological molecules, especially cytokines, chemokines, growth factors, and anaphylatoxins. These molecules are responsible for inducing and attracting immune cells into circulation, thus contributing to increases in leukocytes and other pro-inflammatory mediators, and can culminate in a vaso-occlusive crisis (VOC). This study aimed to characterize the levels of these molecules in SCA patients in different clinical conditions in order to identify potential hallmarks of inflammation in these patients. An analytical prospective study was conducted using the serum of SCA patients in steady-state (StSt; n = 27) and VOC (n = 22), along with 53 healthy donors (HD). Samples from the VOC group were obtained on admission and on discharge, in the convalescent phase (CV). Levels of chemokines (CXCL8, CXCL10, CL2, CLL3, CCL4, CL5, and CCL11), cytokines (IL-1β, IL-1ra, IL-2, IL-4, IL-5, IL-6, IL-7, IL-10, IL-12p70, IL-13, IL-17A, TNF-α, and IFN-γ) and growth factors (VEGF, FGFb, PDGF-BB, GM-CSF, and G-CSF) were measured using a Luminex assay, and anaphylatoxins (C3a, C4a, and C5a) were measured using Cytometric Bead Array. SCA patients in StSt showed a pro-inflammatory profile, and were indicated as being higher producers of CCL2, IL-1β, IL-12p70, IFN-γ, IL-17A, and GM-CSF, while VOC is highlighted by molecules IL-4 and IL-5, but also IL-2, IL-7, PDGF-BB, and G-CSF. PDGF-BB and IL-1ra seemed to be two important hallmarks for the acute-to-chronic stage, due to their significant decrease after crisis inflammation and statistical difference in VOC and CV groups. These molecules show higher levels and a strong correlation with other molecules in VOC. Furthermore, they remain at higher levels even after crisis recovery, which suggest their importance in the role of inflammation during crisis and participation in immune cell adhesion and activation. These results support a relevant role of cytokines, neutrophil and monocytes, since these may act as markers of VOC inflammation in SCA patients.

22 August 2019 in PLOS ONE
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ASAlexander Leonardo Silva-Junior
Alexander Leonardo Silva-Junior
FAFabíola Silva Alves
Fabíola Silva Alves
MKMarlon Wendell Athaydes Kerr
Marlon Wendell Athaydes Kerr
LXLilyane Amorim Xabregas
Lilyane Amorim Xabregas
FGFábio Magalhães Gama
Fábio Magalhães Gama
ACAllyson Guimarães Costa
Allyson Guimarães Costa
Leukemia is the most common cancer in children and has the highest rates of incidence in industrialized countries, followed by developing countries. This epidemiologic profile can mainly be attributed to the availability of diagnostic resources. In Brazil, leukemia diagnosis is a challenge due to financial viability, lack of hemovigilance services in isolated regions and the vast size of the territory. Its incidence in the state of Amazonas has been increasing since 2010. Therefore, this study aims to describe the epidemiological pattern and spatial distribution of patients with acute lymphoid leukemia and acute myeloid leukemia in Amazonas and identify the predictors of comorbidity and death. A retrospective cross-sectional study was carried out based on patients’ data which was obtained from the database of a referral center for the period of 2005 to 2015. Variables included age, gender, ethnicity, civil status, schooling, income, location of residence, subtype of leukemia, comorbidities, and date of death. The spatial distribution was performed using QGIS v.2.18. Stata software was used for univariable and multivariable logistic regression to evaluate the association between both comorbidities and death for all characteristic groups of ALL and AML. The group that was studied was composed of 577 ALL and 266 AML patients. For both, most patients were male, with a schooling period of 1–4 years, received60 years old and with family history of the disease had the highest risk of developing comorbidities (OR = 5.06, p = 0.038; OR = 2.44, p = 0.041, respectively). Furthermore, patients with ALL and in the 41-50-year age group had a higher risk of death (OR = 31.12; p = 0.001). No association between death and explanatory variables were found in patients with AML. In addition, significant difference was observed in time to death (chi2 = 4,098.32, p = 0.000), with 50% of patients with AML dying within two years after diagnosis, whereas in ALL, this percentual of death only is reached in approximately 5 years. Our study describes the data of patients with acute leukemia in Amazonas, a remote region in the north of Brazil. In addition, it highlights the importance of hemovigilance in an Amazon region state, while focusing on peripheral areas which don't have prevention, diagnosis and treatment tools for this disease.

8 January 2020 in Journal of Immunology Research
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NGNadja Pinto Garcia
Nadja Pinto Garcia
ASAlexander Leonardo Silva-Junior
Alexander Leonardo Silva-Junior
GSGeyse Adriana S. Soares
Geyse Adriana S. Soares
TCThainá Cristina C. Costa
Thainá Cristina C. Costa
ASAlicia Patrine C. dos Santos
Alicia Patrine C. dos Santos
AMAdriana Malheiro
Adriana Malheiro
Background. Sickle cell anemia (SCA) is associated with a chronic proinflammatory state characterized by elevated leukocyte count, mortality from severe recurrent infections, and subsequent vasoocclusive complications with leukocyte adhesion to the endothelium and increased plasma levels of inflammatory cytokines. The immune system has a close connection with morbidity in SCA, but further studies are needed to uncover the involvement of innate and adaptive immunities in modulating the SCA physiopathology. We performed measurements of the frequency of innate and adaptive immunity cells, cytokines, chemokines, and growth factors and immunophenotyping of Toll-like receptor and adhesion molecule expression in the blood of SCA patients and healthy donors to evaluate the different profiles of these biomarkers, the relationship among them, and their correlation to laboratory records and death risk. Material and Methods. Immunophenotyping of cells, Toll-like receptors, and adhesion molecules were performed from peripheral blood samples of SCA patients and healthy donors by flow cytometry and cytokine/chemokine/growth factor measurement by the Luminex technique performed from the serum of the same subjects. Results. Cells of adaptive immunity such as IL-12, IL-17, and IL-10 cytokines; IL-8, IP-10, MIP-1α, MIP-1β, and RANTES chemokines; and VEGF, FGF-basic, and GM-CSF growth factors were higher in SCA patients than healthy donors regardless of any laboratorial and clinical condition. However, high death risk appears to have relevant biomarkers. Conclusion. In the SCA pathophysiology at steady state, there is a broad immunological biomarker crosstalk highlighted by TCD4+CD69+ lymphocytes, IL-12 and IL-17 inflammatory and IL-10 regulatory cytokines, MIP-1α, MIP-1β, and IP-10 chemokines, and VEGF growth factor. High expression of TLR2 in monocytes and VLA-4 in TCD8+ lymphocytes and high levels of MIP-1β and RANTES appear to be relevant in high death risk conditions. The high reticulocytosis and high death risk conditions present common correlations, and there seems to be a balance by the Th2 profile.

31 August 2022 in Vaccines
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LBLewis Fletcher Buss
Lewis Fletcher Buss
CJCarlos Augusto Prete Jr.
Carlos Augusto Prete Jr.
CWCharles Whittaker
Charles Whittaker
TSTassila Salomon
Tassila Salomon
MOMarcio Oikawa
Marcio Oikawa
ESEster Cerdeira Sabino
Ester Cerdeira Sabino
SARS-CoV-2 serologic surveys estimate the proportion of the population with antibodies against historical variants, which nears 100% in many settings. New approaches are required to fully exploit serosurvey data. Using a SARS-CoV-2 anti-Spike (S) protein chemiluminescent microparticle assay, we attained a semi-quantitative measurement of population IgG titers in serial cross-sectional monthly samples of blood donations across seven Brazilian state capitals (March 2021–November 2021). Using an ecological analysis, we assessed the contributions of prior attack rate and vaccination to antibody titer. We compared anti-S titer across the seven cities during the growth phase of the Delta variant and used this to predict the resulting age-standardized incidence of severe COVID-19 cases. We tested ~780 samples per month, per location. Seroprevalence rose to >95% across all seven capitals by November 2021. Driven by vaccination, mean antibody titer increased 16-fold over the study, with the greatest increases occurring in cities with the highest prior attack rates. Mean anti-S IgG was strongly correlated (adjusted R2 = 0.89) with the number of severe cases caused by Delta. Semi-quantitative anti-S antibody titers are informative about prior exposure and vaccination coverage and may also indicate the potential impact of future SARS-CoV-2 variants.

17 March 2023 in Immuno
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Journal Article
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ASAlexander Leonardo Silva-Junior
Alexander Leonardo Silva-Junior
LOLucas da Silva Oliveira
Lucas da Silva Oliveira
NBNara Caroline Toledo Belezia
Nara Caroline Toledo Belezia
ATAndrea Tarragô
Andrea Tarragô
ACAllyson Guimarães Costa
Allyson Guimarães Costa
AMAdriana Malheiro
Adriana Malheiro
COVID-19 is a viral disease that has caused millions of deaths around the world since 2020. Many strategies have been developed to manage patients in critical conditions; however, comprehension of the immune system is a key factor in viral clearance, tissue repairment, and adaptive immunity stimulus. Participation of immunity has been identified as a major factor, along with biomarkers, prediction of clinical outcomes, and antibody production after infection. Immune cells have been proposed not only as a hallmark of severity, but also as a predictor of clinical outcomes, while dynamics of inflammatory molecules can also induce worse consequences for acute patients. For convalescent patients, mild disease was related to higher antibody production, although the factors related to the specific antibodies based on a diversity of antigens were not clear. COVID-19 was explored over time; however, the study of immunological predictors of outcomes is still lacking discussion, especially in convalescent patients. Here, we propose a review using previously published studies to identify immunological markers of COVID-19 outcomes and their relation to antibody production to further contribute to the clinical and laboratorial management of patients.

17 July 2024 in The Brazilian Journal of Infectious Diseases
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Journal Article
Open access
MSMaria Ivaldete Siqueira de Souza
Maria Ivaldete Siqueira de Souza
MCMyuki Alfaia Esashika Crispim
Myuki Alfaia Esashika Crispim
NFNelson Abrahim Fraiji
Nelson Abrahim Fraiji
ASAlexander Leonardo Silva-Junior
Alexander Leonardo Silva-Junior
MSMariane M. A. Stefani
Mariane M. A. Stefani
Background: The Amazonas state/AM and Manaus rank among the highest AIDS detection rates in Brazil. High proportion of HIV infected blood donors and transmission clusters of multidrug antiretroviral/ARV resistant viruses were described in HEMOAM blood donors, a main Amazonas public blood bank. Recent and long-term infections among previously genotyped donors are reported. Methods/materials: The recency immunoassay Lag Avidity EIA (Maxim, USA) was employed. Clinical/CD4/viral load medical file data of the main local HIV management center (FMT-HVD) and ARV treatment/ART data were reviewed. Results: Among 142 HIV-blood donors, chronic infection predominated (n = 87; 61.3 %), 79 based on LAg EIA and 8 undisclosed HIV identified in FMT-HVD records, mostly young adult, single males, 4 repeat donors, all ART-naive. Recent infections represented 30.3 % (n = 43), 39 identified by LAg EIA and 4 immunologic windows (antibody negative/NAT/RNA positive). The overall profile of recent and long-term infections was similar, including moderate rate of transmitted drug resistance/TDR, however with multiple resistance mutations to more than one ARV-class, suggesting ART/failure. Discussion: Recent/acute and undisclosed/long-term HIV infections represent blood safety alerts suggesting test-seeking behavior of at-risk populations. Early ART use in Brazil, can turn HIV diagnosis more challenging representing a blood transfusion risk in the highly endemic Brazilian Amazon.