Enhanced immunogenicity and protective efficacy in mice following a Zika DNA vaccine designed by modulation of membrane-anchoring regions and its association to adjuvants

Zika virus (ZIKV) is a re-emerging pathogen with high morbidity associated to congenital infection. Despite the scientific advances since the last outbreak in the Americas, there are no approved specific treatment or vaccines. As the development of an effective prophylactic approach remains unaddressed, DNA vaccines surge as a powerful and attractive candidate due to the efficacy of sequence optimization in achieving strong immune response. In this study, we developed four DNA vaccine constructs encoding the ZIKV prM/M (pre-membrane/membrane) and E (envelope) proteins in conjunction with molecular adjuvants. The DNA vaccine candidate (called ZK_ΔSTP), where the entire membrane-anchoring regions were completely removed, was far more immunogenic compared to their counterparts. Furthermore, inclusion of the tPA-SP leader sequence led to high expression and secretion of the target vaccine antigens, therefore contributing to adequate B cell stimulation. The ZK_ΔSTP vaccine induced high cellular and humoral response in C57BL/6 adult mice, which included high neutralizing antibody titers and the generation of germinal center B cells. Administration of ZK-ΔSTP incorporating aluminum hydroxide (Alum) adjuvant led to sustained neutralizing response. In consistency with the high and long-term protective response, ZK_ΔSTP+Alum protected adult mice upon viral challenge. Collectively, the ZK_ΔSTP+Alum vaccine formulation advances the understanding of the requirements for a successful and protective vaccine against flaviviruses and is worthy of further translational studies

SARS-CoV-2 recombinant proteins stimulate distinct cellular and humoral immune response profiles in samples from COVID-19 convalescent patients

OBJECTIVES: In this preliminary study we investigated cellular and humoral immune responses to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) antigens in blood samples from 14 recovered coronavirus disease 2019 (COVID-19) patients and compared them to those in samples from 12 uninfected/unvaccinated volunteers. METHODS: Cellular immunity was assessed by intracellular detection of IFN-γ in CD3+ T lymphocytes after stimulation with SARS-CoV-2 spike (S1), nucleocapsid (NC), or receptor-binding domain (RBD) recombinant proteins or overlapping peptide pools covering the sequence of SARS-CoV-2 spike, membrane and nucleocapsid regions. The humoral response was examined by ELISAs and/or chemiluminescence assays for the presence of serum IgG antibodies directed to SARS-CoV-2 proteins. RESULTS: We observed differences between humoral and cellular immune profiles in response to stimulation with the same proteins. Assays of IgG antibodies directed to SARS-CoV-2 NC, RBD and S1/S2 recombinant proteins were able to differentiate convalescent from uninfected/unvaccinated groups. Cellular immune responses to SARS-CoV-2 protein stimuli did not exhibit a specific response, as T cells from both individuals with no history of contact with SARS-CoV-2 and from recovered donors were able to produce IFN-γ. CONCLUSIONS: Determination of the cellular immune response to stimulation with a pool of SARS-CoV-2 peptides but not with SARS-CoV-2 proteins is able to distinguish convalescent individuals from unexposed individuals. Regarding the humoral immune response, the screening for serum IgG antibodies directed to SARS-CoV-2 proteins has been shown to be specific for the response of recovered individuals

Dysfunctional purinergic signaling correlates with disease severity in COVID-19 patients

Ectonucleotidases modulate inflammatory responses by balancing extracellular ATP and adenosine (ADO) and might be involved in COVID-19 immunopathogenesis. Here, we explored the contribution of extracellular nucleotide metabolism to COVID-19 severity in mild and severe cases of the disease. We verified that the gene expression of ectonucleotidases is reduced in the whole blood of patients with COVID-19 and is negatively correlated to levels of CRP, an inflammatory marker of disease severity. In line with these findings, COVID-19 patients present higher ATP levels in plasma and reduced levels of ADO when compared to healthy controls. Cell type-specific analysis revealed higher frequencies of CD39+ T cells in severely ill patients, while CD4+ and CD8+ expressing CD73 are reduced in this same group. The frequency of B cells CD39+CD73+ is also decreased during acute COVID-19. Interestingly, B cells from COVID-19 patients showed a reduced capacity to hydrolyze ATP into ADP and ADO. Furthermore, impaired expression of ADO receptors and a compromised activation of its signaling pathway is observed in COVID-19 patients. The presence of ADO in vitro, however, suppressed inflammatory responses triggered in patients’ cells. In summary, our findings support the idea that alterations in the metabolism of extracellular purines contribute to immune dysregulation during COVID-19, possibly favoring disease severity, and suggest that ADO may be a therapeutic approach for the disease

Design and efficacy evaluation of a DNA vaccine against zika virus in mice

Os efeitos congênitos e pós-natais da infecção pelo vírus Zika (ZIKV) somado a sua relevância epidemiológica, ressaltam a importância para o desenvolvimento de estratégias vacinais profiláticas e, até o momento, não há nenhuma vacina licenciada para uso. Neste projeto, desenvolvemos formulações vacinais de DNA codificando para as proteínas pré-membrana/membrana e envelope (E) do ZIKV objetivando abordagens de otimização para almejar imunogenicidade adequada. Uma candidata vacinal de DNA (descrita como ZK_&#914STP) utilizando a sequência líder tPA-SP tissue plasminogen activator signal peptide para aumento da expressão e secreção das proteínas sintetizadas, com remoção da região de ancoramento stem da proteína E, foi selecionada pela maior imunogenicidade. A imunização de camundongos C57BL/6 imunocompetentes com ZK_&#914STP, foi capaz de induzir células esplênicas secretoras de IFN-ϒ ZIKV-específicas por até três meses e geração de anticorpos neutralizantes. A imunização com ZK_&#914STP em camundongos adultos C57-IFNα/ß-/- contribuiu para proteção ao desafio de infecção por ZIKV, com redução da carga viral no cérebro aos 21 dias após infecção (dpi) em relação ao grupo controle (PBS). Adicionalmente, 42% destes animais mostraram carga viral abaixo do limite de detecção. Os títulos de anticorpos IgG anti-ZIKV exibiram queda a partir do segundo mês da vacinação, o que comprometeu a proteção da prole de mães imunizadas em período superior a dois meses. Contudo, a imunização associada ao adjuvante Alum foi capaz de elevar os títulos e duração dos anticorpos neutralizantes, promovendo efeito protetor a curto e longo prazo em camundongos adultos. A curto prazo, a carga viral foi indetectável no cérebro de animais vacinado aos 10dpi. A longo prazo, dois terços dos animais vacinados, com ou sem dose de reforço adicional, tiveram carga viral no cérebro abaixo do limite de detecção aos 10 dpi. A fim de aumentar a expressão dos antígenos vacinais, foi desenvolvido um sistema de 16 nanopartículas (NPs) funcionalizadas com escovas de polímeros catiônicos, utilizando o polímero poli(dimetilaminoetil metacrilato) (PDMAEMA) para entrega de DNA plasmideal (pDNA). Este sistema mostrou ligação de alta afinidade ao pDNA com formação de complexos catiônicos e sua internacionalização celular. Esta abordagem também permitiu a transfecção celular com eficiência comparável à sistemas de transfecção comerciais, porém sem efeito citotóxico pronunciado. Por fim, esta abordagem foi eficiente na transfecção da vacina candidata ZK_&#914STP com expressão da proteína do E do ZIKV. Em conjunto, os resultados apontam para uma estratégia vacinal que pode ser promissora em proteger contra a infecção por ZIKV e seus efeitos adversos. Da mesma forma, o racional para o desenho desta formulação e sistema de entrega baseado em NPs policatiônicas emergem como uma estratégia inovadora e potencial para outras vacinas de DNA e RNA. Oferecendo subsídios não apenas para vacinas gênicas, mas também para outras imunoterapias.Congenital and postnatal outcomes of Zika virus (ZIKV) infection, added to its epidemiological relevance, highlight the importance for prophylactic vaccine strategies development and, to date, there is no vaccine licensed. In this project, we developed DNA vaccine formulations encoding to ZIKV premembrane/ membrane and envelope (E) proteins, aiming different optimization approaches to achieve adequate immunogenicity. A DNA vaccine candidate (described as ZK_&#914STP) using the tPA-SP (tissue plasminogen activator signal peptide) leader sequence to increase expression and secretion of synthesized proteins, with depletion of the stem anchoring region of the E protein was selected due higher immunogenicity. Immunization of immunocompetent C57BL/6 mice with ZK_&#914STP was able to induce ZIKV-specific IFN-ϒ-secreting splenic cells for up to three months and generation of neutralizing antibodies. Immunization with ZK_&#914STP in adult C57-IFNα/ß-/- mice contributed to protection against ZIKV challenge, with reduced viral load in the brain at 21 days post infection (dpi) in comparison to the control group (PBS). In addition, 42% of these animals showed a viral load below the detection limit. Anti-ZIKV IgG antibody titers decreased from the second month of vaccination, which compromised the protection of the offspring from immunized mothers for a period longer than two months. However, the immunization associated with the Alum adjuvant was able to increase the titers and duration of neutralizing antibodies, promoting a short- and long-term protective effect in adult mice. At the short term, viral load was undetectable in the brains of animals vaccinated at 10dpi. While at the long term, two-thirds of animals vaccinated, with or without an additional booster dose, showed a brain viral load below the detection limit at 10 dpi. In order to increase the expression of vaccine antigens, a system of nanoparticles (NPs) functionalized with cationic polymer brushes was developed, using the polymer poly(dimethylaminoethyl methacrylate) (PDMAEMA) to deliver plasmid DNA (pDNA). This system showed high affinity binding to pDNA with formation of cationic complexes and their 18 cellular internationalization. This approach also allowed cell transfection with efficiency comparable to commercial transfection systems, but without pronounced cytotoxic effect. Finally, this approach was efficient in transfecting the ZK_&#914STP candidate vaccine with ZIKV E protein expression. Taken together, the results point to a vaccine strategy that may be promising to protect against ZIKV infection and its adverse outcomes. As well as, the rational design for this formulation and delivery system based on polycationic NPs emerges as an innovative and potential strategy for other DNA and RNA vaccines. Offering support not only for genetic vaccines, but also for other immunotherapies

Evaluation of response to the DNA vaccine LAMP-1/p55Gag of HIV-1 and generation of follicular T cells in the neonatal mice

O número de jovens infectados por HIV vem aumentando nas últimas décadas, o que salienta a necessidade de estratégias vacinais que sejam imunogênicas em fase precoce de vida capazes de induzir resposta de longa duração. A vacina quimérica LAMP-1/p55Gag, associa o gene que codifica a LAMP-1 (proteína de associação da membrana lisossomal) e o gene da gag do HIV-1, direciona o tráfego da proteína viralpara os compartimentos MIIC, possibilitando a apresentação dos peptídeos virais pela classe II do Complexo Principal de Histocompatibilidade (MHC II). Esta vacina quimérica é imunogênica em camundongos BALB/c adultos e neonatos e crucial para induzir resposta T e B de longa duração, com produção de elevados níveis de anticorpos. Contudo, os mecanismos imunológicos envolvidos na indução da resposta humoral da vacina LAMP/Gag, como a geração de células T auxiliares foliculares (TFH), ainda não são conhecidos no período neonatal. O objetivo do estudo foi avaliar a geração de células TFH, T citotóxicos e B foliculares em camundongos neonatos submetidos à imunização com as vacinas LAMP/Gag (LG) e Gag (G). Inicialmente,avaliamos a imunogenicidade das vacinas gênicas na imunização neonatal aos sete dias de idade em camundongos de linhagem C57BL/6. Os resultados mostram que a imunização neonatal com a vacina LG é capaz de aumentara frequência de células secretoras de IFN-&#978 aos peptídeos imunodominantes da região gag do HIV-1 e de células T CD8&#43IFN-&#978&#43 comparadas a vacina Gag. A imunização neonatal com a vacina LG também levou a produção de títulos elevados de anticorpos IgG1 anti-p24 e aumento da porcentagem de células secretoras de IgG1 Gag-específicas. O priming neonatal com LG é capaz de promover resposta celular e humoral anti-Gag de longa duração. Além disto, a imunização neonatal (ip) com LG foi capaz de induzir células TFH (CD4&#43CXCR5&#43PD-1&#43Bcl-6&#43), linfócitos T CD8&#43 foliculares (TFC) (CD8&#43CXCR5&#43) e formação de centro germinativo (CG) nos linfonodos mesentéricos, contudo, ambas as vacinas induziram células B foliculares (CD19&#43CXCR5&#43). Apesar da menor frequência de TFH dos neonatos em relação a adultos na imunização com LG, houve frequência similar de células TFC. A imunização intradérmica convencional induziu aumento do número de células TFH nos linfonodos inguinais já ao terceiro dia após o reforço vacinal, embora frequência similar de células TFH, TFC e B foliculares. Neste período foi possível observar que a vacina LG também induziu a geração de células B de CG. Outra peculiaridade da vacina LG neonatal foi o aumento da expressão gênica da enzima citidina deaminase (AID). Os resultados mostram que a vacina L/AMP/Gag é imunogênica na fase neonatal de camundongos C57BL/6 quanto à geração de resposta celular e humoral antígeno-específica e resposta de longa duração, similarmente aos camundongos BALB/c. Os dados mostraram que a vacina LG é eficaz na indução de células T foliculares, na maturação de tecidos linfoides com formação de CGs e na indução de transcritos para AID. No conjunto, os achados evidenciam que a estratégia da vacina quimérica L/AMP/Gag é eficaz neste período da vida, e possui importante papel adjuvante na maturação da resposta humoral.The number of young people infected with HIV has been increasing in recent decades, which highlights the need for vaccine strategies that are immunogenic at early phase of life able of inducing long-term response. The chimeric LAMP-1/p55Gag vaccine, associates the gene encoding LAMP-1 (lysosomal associated membrane protein) and the HIV-1 gag gene, directs the traffic of viral protein to MIIC compartments, leading to presentation of the viral peptides through class II of the Major Histocompatibility Complex (MHC II). This chimeric vaccine is immunogenic in adult and neonatal BALB/c mice and crucial to induce long-term T and B responses, producing high levels of antibodies. However, the immunological mechanisms involved in the induction of the humoral response of the LAMP/Gag vaccine, such as the generation of T follicular helper cells (TFH), are unknown in the neonatal period. The objective of this study was to evaluate the generation of TFH, and follicular cytotoxic T cells and B cells in neonates submitted to immunization with the LAMP/Gag (LG) and Gag (G) vaccines. The results show that neonatal immunization at seven days-old in C57BL/6 mice strain with the LG vaccine is able to increasing the frequency of IFN-&#978-secreting cells to the immunodominant peptides of the HIV-1 gag region and of CD8&#43IFN-&#978&#43 T cells compared to the Gag vaccine. Neonatal immunization with the LG vaccine led to the production of high titers of anti-p24 IgG1 antibodies and the increased percentage of Gag-specific IgG1 secreting cells. Neonatal priming with LG is able to promote long-lasting anti-Gag humoral and cellular response. Moreover, neonatal (ip) immunization with LG was able to induce TFH cells (CD4&#43CXCR5&#43PD-1&#43Bcl-6 &#43), follicular CD8 &#43 T cells (TFC) (CD8&#43CXCR5&#43) and germinal center (GC) formation in the mesenteric lymph nodes, whereas both vaccines induced follicular B cells (CD19&#43CXCR5&#43). Despite the lower frequency of TFH in neonates in relation to adult counterpartin the immunization with LG, a similar percentage of TFC cells was observed. Conventional immunization by intradermal immunization induced an increased number of TFH cells in inguinal lymph nodes on the third day after booster vaccination, despite the similar frequency of follicular TFH, TFC and B cells. In this period the LG vaccine also induced generation of CG B cells. Another peculiarity of the LG neonatal vaccine was the increase in the gene expression of the enzyme activation-induced cytidine deaminase (AID).The results show that the LAMP/Gag vaccine is immunogenic in the neonatal phase of C57BL/6 mice for the generation of antigen-specific humoral and cellular response and long-term response, similar to BALB/c mice. The findings showed effective induction of follicular T cells, maturation of lymphoid tissues with formation of GCs and up-regulation oftranscripts for AID. Taken together, our findings demonstrate that the LAMP/Gag chimeric vaccine strategy is effective at this time in life, and has an important adjuvant role in the maturation of the humoral response

Impact of Retinoic Acid on Immune Cells and Inflammatory Diseases

Vitamin A metabolite retinoic acid (RA) plays important roles in cell growth, differentiation, organogenesis, and reproduction and a key role in mucosal immune responses. RA promotes dendritic cells to express CD103 and to produce RA, enhances the differentiation of Foxp3+ inducible regulatory T cells, and induces gut-homing specificity in T cells. Although vitamin A is crucial for maintaining homeostasis at the intestinal barrier and equilibrating immunity and tolerance, including gut dysbiosis, retinoids perform a wide variety of functions in many settings, such as the central nervous system, skin aging, allergic airway diseases, cancer prevention and therapy, and metabolic diseases. The mechanism of RA is interesting to explore as both a mucosal adjuvant and a combination therapy with other effective agents. Here, we review the effect of RA on innate and adaptive immunity with a special emphasis on inflammatory status

Delivery of microRNAs by Extracellular Vesicles in Viral Infections: Could the News be Packaged?

Extracellular vesicles (EVs) are released by various cells and recently have attracted attention because they constitute a refined system of cell–cell communication. EVs deliver a diverse array of biomolecules including messenger RNAs (mRNAs), microRNAs (miRNAs), proteins and lipids, and they can be used as potential biomarkers in normal and pathological conditions. The cargo of EVs is a snapshot of the donor cell profile; thus, in viral infections, EVs produced by infected cells could be a central player in disease pathogenesis. In this context, miRNAs incorporated into EVs can affect the immune recognition of viruses and promote or restrict their replication in target cells. In this review, we provide an updated overview of the roles played by EV-delivered miRNAs in viral infections and discuss the potential consequences for the host response. The full understanding of the functions of EVs and miRNAs can turn into useful biomarkers for infection detection and monitoring and/or uncover potential therapeutic targets

Outlining the skin-homing and circulating CLA+NK cells in patients with severe atopic dermatitis

Abstract Atopic dermatitis (AD) is a complex, multifactorial skin disease, characterized by pruritus and predominant Th2 inflammation. Innate immune cells may play a role in AD development and are composed of granulocytes, macrophages, innate-like T cells, and innate lymphoid cells. This study investigates the phenotypic and functional profile of circulating CLA+ natural killer (NK) cells and its role in the skin-homing to NK cells infiltrated in adults’ skin with AD. We selected 44 AD patients and 27 non-AD volunteers for the study. The results showed increased frequencies of both CLA+CD56bright and CLA+CD56dim NK cell populations in the peripheral blood, mainly in severe AD patients. Upon SEB stimulation, we observed an augmented percentage of CLA+CD56dim NK cells expressing CD107a, IFN-γ, IL-10, and TNF, reinforcing the role of staphylococcal enterotoxins in AD pathogenesis. Additionally, we demonstrated increased dermal expression of both NK cell markers NCAM-1/CD56 and pan-granzyme, corroborating the skin-homing, mostly in severe AD. Further studies are necessary to elucidate the potential role of NK cells in the chronification of the inflammatory process in AD skin, as well as their possible relationship with staphylococcal enterotoxins, and as practicable therapeutic targets