The Effect of Live Attenuated Influenza Vaccine and Experimental Human Pneumococcal Carriage on Human Immunity

Live Attenuated Influenza Vaccine (LAIV) is used in immunisation campaigns but may alter the dynamics of naturally occurring nasal colonisation by Streptococcus pneumoniae (Spn), a common human pathogen. We tested how the attenuated influenza viruses contained in the vaccine and Spn interact in the host’s nasopharynx using for the first time an Experimental Human Pneumococcal Challenge model (EHPC) with multiple live pathogens: LAIV and Spn of serotype 6B. Two double blinded randomised clinical trials represented two scenarios of controlled co-infection: 1) Antecedent LAIV administration followed by nasopharyngeal Spn inoculation or 2) Concurrent LAIV administration during established Spn colonisation, separated by a 3 day interval. We validated non-invasive micro-sampling techniques for mucosal immunity analysis by comparing reliability and reproducibility of available methods. Absorptive matrices and nasal curettes were established as the preferred techniques to investigate lining fluid and immune cells in the nasal mucosa. In addition, we collected nasal wash, BAL and serum from healthy adults to investigate immune cell recruitment, cytokine and influenza-specific antibody responses using flow cytometer, human cytokine 30-plex panel and ELISA analysis. Here, we showed that LAIV-induced inflammation in the nasopharynx was associated with Spn colonisation. Immune responses to Spn and to the attenuated influenza virus were impaired by LAIV, reducing chemoattractant cytokines, recruitment of monocytes, and activation of T-cells and neutrophils. In the lung, our results demonstrated that LAIV induces inflammatory cytokines produced by T-cells and that tissue-resident memory T-cells have an important role in producing specific cytokines against the attenuated influenza virus. In short, LAIV was shown to be immunogenic in healthy adults, but less in Spn colonised individuals, highlighting the significance of nasal microbiota when developing vaccines and assessing its efficacy

A reabilitação cardiopulmonar em pacientes críticos pós-COVID-19: Cardiopulmonary rehabilitation in critically ill patients post-COVID-19

O novo Coronavírus é uma doença infecciosa causada pelo vírus SARS-CoV-2, detectado em dezembro de 2019, que se alastrou rapidamente ocasionando sintomas como febre, dispneia, tosse seca, mialgia, fadiga generalizada, anosmia e disgeusia em casos mais leves (ADIL 2021).&nbsp

Viral diversity in oral cavity from Sapajus nigritus by metagenomic analyses

Sapajus nigritus are non-human primates which are widespread in South America. They are omnivores and live in troops of up to 40 individuals. The oral cavity is one of the main entry routes for microorganisms, including viruses. Our study proposed the identification of viral sequences from oral swabs collected in a group of capuchin monkeys (n = 5) living in a public park in a fragment of Mata Atlantica in South Brazil. Samples were submitted to nucleic acid extraction and enrichment, which was followed by the construction of libraries. After high-throughput sequencing and contig assembly, we used a pipeline to identify 11 viral families, which are Herpesviridae, Parvoviridae, Papillomaviridae, Polyomaviridae, Caulimoviridae, Iridoviridae, Astroviridae, Poxviridae, and Baculoviridae, in addition to two complete viral genomes of Anelloviridae and Genomoviridae. Some of these viruses were closely related to known viruses, while other fragments are more distantly related, with 50% of identity or less to the currently available virus sequences in databases. In addition to host-related viruses, insect and small vertebrate-related viruses were also found, as well as plant-related viruses, bringing insights about their diet. In conclusion, this viral metagenomic analysis reveals, for the first time, the profile of viruses in the oral cavity of wild, free ranging capuchin monkeys

Inflammation induced by influenza virus impairs human innate immune control of pneumococcus

Secondary bacterial pneumonia following influenza infection is a significant cause of mortality worldwide. Upper respiratory tract pneumococcal carriage is important as both determinants of disease and population transmission. The immunological mechanisms that contain pneumococcal carriage are well-studied in mice but remain unclear in humans. Loss of this control of carriage following influenza infection is associated with secondary bacterial pneumonia during seasonal and pandemic outbreaks. We used a human type 6B pneumococcal challenge model to show that carriage acquisition induces early degranulation of resident neutrophils and recruitment of monocytes to the nose. Monocyte function associated with clearance of pneumococcal carriage. Prior nasal infection with live attenuated influenza virus induced inflammation, impaired innate function and altered genome-wide nasal gene responses to pneumococcal carriage. Levels of the cytokine IP-10 promoted by viral infection at the time of pneumococcal encounter was positively associated with bacterial density. These findings provide novel insights in nasal immunity to pneumococcus and viral-bacterial interactions during co-infection

Interaction between the nasal microbiota and S. pneumoniae in the context of live-attenuated influenza vaccine

Streptococcus pneumoniae is the main bacterial pathogen involved in pneumonia. Pneumococcal acquisition and colonization density is probably affected by viral co-infections, the local microbiome composition and mucosal immunity. Here, we report the interactions between live-attenuated influenza vaccine (LAIV), successive pneumococcal challenge, and the healthy adult nasal microbiota and mucosal immunity using an experimental human challenge model. Nasal microbiota profiles at baseline are associated with consecutive pneumococcal carriage outcome (non-carrier, low-dense and high-dense pneumococcal carriage), independent of LAIV co-administration. Corynebacterium/Dolosigranulum-dominated profiles are associated with low-density colonization. Lowest rates of natural viral co-infection at baseline and post-LAIV influenza replication are detected in the low-density carriers. Also, we detected the fewest microbiota perturbations and mucosal cytokine responses in the low-density carriers compared to non-carriers or high-density carriers. These results indicate that the complete respiratory ecosystem affects pneumococcal behaviour following challenge, with low-density carriage representing the most stable ecological state

Pneumococcal colonization impairs mucosal immune responses to live attenuated influenza vaccine.

Influenza virus infections affect millions of people annually, and current available vaccines provide varying rates of protection. However, the way in which the nasal microbiota, particularly established pneumococcal colonization, shape the response to influenza vaccination is not yet fully understood. In this study, we inoculated healthy adults with live Streptococcus pneumoniae and vaccinated them 3 days later with either tetravalent-inactivated influenza vaccine (TIV) or live attenuated influenza vaccine (LAIV). Vaccine-induced immune responses were assessed in nose, blood, and lung. Nasal pneumococcal colonization had no impact upon TIV-induced antibody responses to influenza, which manifested in all compartments. However, experimentally induced pneumococcal colonization dampened LAIV-mediated mucosal antibody responses, primarily IgA in the nose and IgG in the lung. Pulmonary influenza-specific cellular responses were more apparent in the LAIV group compared with either the TIV or an unvaccinated group. These results indicate that TIV and LAIV elicit differential immunity to adults and that LAIV immunogenicity is diminished by the nasal presence of S. pneumoniae. Therefore, nasopharyngeal pneumococcal colonization may affect LAIV efficacy

Nasal Pneumococcal Density is Associated with Microaspiration and Heightened Human Alveolar Macrophage Responsiveness to Bacterial Pathogens.

RATIONALE Pneumococcal pneumonia remains a global health problem. Colonization of the nasopharynx with S.pneumoniae (Spn), although, a prerequisite of infection, is the main source of exposure and immunological boosting in children and adults. However, our knowledge of how nasal colonization impacts on the lung cells, especially on the predominant alveolar macrophage (AM) population, is limited. OBJECTIVES Using a Controlled Human Infection Model to achieve nasal colonization with 6B serotype, we investigated the effect of Spn colonization on lung cells. METHODS We collected bronchoalveolar lavages from healthy pneumococcal challenged participants aged 18-49 years. Confocal microscopy, molecular and classical microbiology were used to investigate microaspiration and pneumococcal presence in the lower airways. AM opsonophagocytic capacity was assessed by functional assays in vitro, whereas flow cytometry and transcriptomic analysis were used to assess further changes on the lung cellular populations. MEASUREMENTS AND MAIN RESULTS AM from Spn-colonized exhibited increased opsonophagocytosis to pneumococcus (11.4% median increase) for four months after clearance of experimental pneumococcal colonization. AM had also increased responses against other bacterial pathogens. Pneumococcal DNA detected in the BAL samples of Spn-colonized were positively correlated with nasal pneumococcal density (r=0.71, p=0.029). Similarly, AM heightened opsonophagocytic capacity was correlated with nasopharyngeal pneumococcal density (r=0.61, p=0.025). CONCLUSIONS Our findings demonstrate that nasal colonization with pneumococcus and microaspiration prime AM, leading to brisker responsiveness to both pneumococcus and unrelated bacterial pathogens. The relative abundance of AM in the alveolar spaces, alongside with their potential for non-specific protection, render them an attractive target for novel vaccines. Clinical trial registration available at http://www.isrctn.com, ID: ISRCTN16993271

Two randomized trials of effect of live attenuated influenza vaccine on pneumococcal colonization

The human nasopharynx is frequently colonized by Streptococcus pneumoniae (the pneumococcus), serving as the reservoir for transmission, a state which necessarily precedes invasive pneumococcal infection. Influenza infection increases pneumococcal colonization density and dysregulates host immune responses, increasing the risk of secondary bacterial pneumonia and death

The impact of maternal HIV infection on cord blood lymphocyte subsets and cytokine profile in exposed non-infected newborns

<p>Abstract</p> <p>Background</p> <p>Children born to HIV+ mothers are exposed intra-utero to several drugs and cytokines that can modify the developing immune system, and influence the newborn's immune response to infections and vaccines. We analyzed the relation between the distribution of cord blood lymphocyte subsets and cytokine profile in term newborns of HIV+ mothers using HAART during pregnancy and compared them to normal newborns.</p> <p>Methods</p> <p>In a prospective, controlled study, 36 mother-child pairs from HIV+ mothers and 15 HIV-uninfected mothers were studied. Hematological features and cytokine profiles of mothers at 35 weeks of pregnancy were examined. Maternal and cord lymphocyte subsets as well as B-cell maturation in cord blood were analyzed by flow cytometry. The non-stimulated, as well as BCG- and PHA-stimulated production of IL2, IL4, IL7, IL10, IL12, IFN-γ and TNF-alpha in mononuclear cell cultures from mothers and infants were quantified using ELISA.</p> <p>Results</p> <p>After one year follow-up none of the exposed infants became seropositive for HIV. An increase in B lymphocytes, especially the CD19/CD5+ ones, was observed in cord blood of HIV-exposed newborns. Children of HIV+ hard drug using mothers had also an increase of immature B-cells. Cord blood mononuclear cells of HIV-exposed newborns produced less IL-4 and IL-7 and more IL-10 and IFN-γ in culture than those of uninfected mothers. Cytokine values in supernatants were similar in infants and their mothers except for IFN-γ and TNF-alpha that were higher in HIV+ mothers, especially in drug abusing ones. Cord blood CD19/CD5+ lymphocytes showed a positive correlation with cord IL-7 and IL-10. A higher maternal age and smoking was associated with a decrease of cord blood CD4+ cells.</p> <p>Conclusions</p> <p>in uninfected infants born to HIV+ women, several immunological abnormalities were found, related to the residual maternal immune changes induced by the HIV infection and those associated with antiretroviral treatment. Maternal smoking was associated to changes in cord CD3/CD4 lymphocytes and maternal hard drug abuse was associated with more pronounced changes in the cord B cell line.</p