krn-7000 and Pneumococcal-Infections

CD4

Topics: Animals; B-Lymphocytes; Cells, Cultured; Galactosylceramides; Humans; Immunity, Humoral; Immunoglobulin G; Immunoglobulin M; Lymphocyte Activation; Mice; Nanoparticles; Natural Killer T-Cells; Pneumococcal Infections; Polysaccharides, Bacterial; Streptococcal Vaccines; Streptococcus pneumoniae; T-Lymphocytes

Interleukin-7 (IL-7) is a critical cytokine in B- and T-lymphocyte development and maturation. Recent evidence suggests that IL-7 is a preferential homeostatic and survival factor for RORγt

Topics: Animals; Antibodies, Blocking; Cells, Cultured; Galactosylceramides; Humans; Immunity, Innate; Immunotherapy; Interleukin-17; Interleukin-7; Mice; Mice, Inbred C57BL; Mice, Knockout; Natural Killer T-Cells; Neutrophils; Nuclear Receptor Subfamily 1, Group F, Member 3; Pneumococcal Infections; Respiratory Tract Infections; Streptococcus pneumoniae

Pneumococcal infections remain a major public health concern worldwide. The currently available vaccines in the market are based on pneumococcal capsular polysaccharides but they still need to be improved to secure an optimal coverage notably in population at risk. To circumvent this, association of virulence pneumococcal proteins to the polysaccharide valencies has been proposed with the hope to observe an additive - if not synergistic - protective effect. Along this line, the use of the highly conserved and ubiquitous pneumococcal surface adhesin A (PsaA) as a protein carrier for a synthetic pneumococcal oligosaccharide is demonstrated herein for the first time. A tetrasaccharide mimicking functional antigenic determinants from the S. pneumoniae serotype 14 capsular polysaccharide (Pn14TS) was chemically synthesised. The mature PsaA (mPsaA) was expressed in E. coli and purified using affinity chromatography. The Pn14PS was conjugated to mPsaA using maleimide-thiol coupling chemistry to obtain mPsaA-Pn14PS conjugate (protein/sugar molar ratio: 1/5.4). The mPsaA retained the structural conformation after the conjugation and lyophilisation. The prepared glycoconjugate adjuvanted with α-galactosylceramide, a potent activator of invariant Natural Killer T cells, was tested in mice for its immunological response upon subcutaneous injection in comparison with mPsaA alone and a model BSA conjugate (BSA-Pn14PS, used here as a control). Mice immunised with the mPsaA-Pn14TS produced a robust IgG response against mPsaA and against the capsular polysaccharide from pneumococcal serotype 14. These data provide the basis for novel pneumococcal vaccine development.

Topics: Animals; Bacterial Proteins; Escherichia coli; Female; Galactosylceramides; Glycoconjugates; Immunization; Mice; Mice, Inbred BALB C; Mice, Inbred C57BL; Pneumococcal Infections; Pneumococcal Vaccines; Streptococcus pneumoniae; Vaccination

Despite the application of vaccination programs and antiviral drugs, influenza A virus (IAV) infection is responsible for widespread morbidity and mortality (500,000 deaths/year). Influenza infections can also result in sporadic pandemics that can be devastating: the 1918 pandemic led to the death of 50 million people. Severe bacterial infections are commonly associated with influenza and are significant contributors to the excess morbidity and mortality of influenza. Today's treatments of secondary bacterial (pneumococcal) infections are still not effective enough, and antibiotic resistance is a major issue. Hence, there is an urgent need for novel therapies. In the present study, we set out to evaluate the efficacy of α-galactosylceramide (α-GalCer)-a potent agonist of invariant NKT cells that is currently in clinical development-in a mouse model of postinfluenza, highly invasive pneumococcal pneumonia. Our data indicate that treatment with α-GalCer reduces susceptibility to superinfections and, when combined with the corticosteroid dexamethasone, reduces viral-bacterial pneumonia.

Topics: Administration, Intranasal; Animals; Disease Models, Animal; Galactosylceramides; Lymphocyte Activation; Mice; Natural Killer T-Cells; Orthomyxoviridae Infections; Pneumococcal Infections; Time Factors; Treatment Outcome

Invariant NKT (iNKT) cells are glycolipid-specific innate lymphocytes emerging as critical players in the immune response to diverse infections and disease. iNKT cells are activated through cognate interactions with lipid-loaded APCs, by Ag-independent cytokine-mediated signaling pathways, or a combination of both. Although each of these modes of iNKT cell activation plays an important role in directing the humoral and cell-mediated immune response, the spatio-temporal nature of these interactions and the cellular requirements for activation are largely undefined. Combining novel in situ confocal imaging of αGalactosylceramide-loaded CD1d tetramer labeling to localize the endogenous iNKT cell population with cytokine reporter mice, we reveal the choreography of early murine splenic iNKT cell activation across diverse settings of glycolipid immunization and systemic infection with Streptococcus pneumoniae. We find that iNKT cells consolidate in the marginal zone and require dendritic cells lining the splenic marginal zone for activation following administration of cognate glycolipids and during systemic infection but not following exogenous cytokine administration. Although further establishing the importance of cognate iNKT cell interactions with APCs, we also show that noncognate iNKT-dependent mechanisms are sufficient to mediate effector outcomes, such as STAT signaling and dendritic cell licensing throughout the splenic parenchyma. Collectively, these data provide new insight into how iNKT cells may serve as a natural adjuvant in facilitating adaptive immune responses, irrespective of their tissue localization.

Topics: Adaptive Immunity; Animals; Antigen-Presenting Cells; Antigens, CD1d; Cell Communication; Cytokines; Dendritic Cells; Galactosylceramides; Lymphocyte Activation; Mice; Mice, Inbred BALB C; Mice, Knockout; Natural Killer T-Cells; Pneumococcal Infections; Signal Transduction; Spleen; Streptococcus pneumoniae

Exogenous activation of pulmonary invariant natural killer T (iNKT) cells, a population of lipid-reactive αβ T lymphocytes, with use of mucosal α-galactosylceramide (α-GalCer) administration, is a promising approach to control respiratory bacterial infections. We undertook the present study to characterize mechanisms leading to α-GalCer-mediated protection against lethal infection with Streptococcus pneumoniae serotype 1, a major respiratory pathogen in humans.. α-GalCer was administered by the intranasal route before infection with S. pneumoniae. We showed that respiratory dendritic cells (DCs), most likely the CD103(+) subset, play a major role in the activation (IFN-γ and IL-17 release) of pulmonary iNKT cells, whereas alveolar and interstitial macrophages are minor players. After challenge, S. pneumoniae was rapidly (4 hours) eliminated in the alveolar spaces, a phenomenon that depended on respiratory DCs and neutrophils, but not macrophages, and on the early production of both IFN-γ and IL-17. Protection was also associated with the synthesis of various interferon-dependent and IL-17-associated genes as revealed by transcriptomic analysis.. These data imply a new function for pulmonary CD103(+) DCs in mucosal activation of iNKT cells and establish a critical role for both IFN-γ and IL-17 signalling pathways in mediating the innate immune response to S. pneumoniae.

Topics: Animals; Antigens, CD; Bronchoalveolar Lavage Fluid; Dendritic Cells; Galactosylceramides; Immunity, Innate; Integrin alpha Chains; Interferon-gamma; Interleukin-17; Kaplan-Meier Estimate; Male; Mice; Mice, Inbred C57BL; Natural Killer T-Cells; Pneumococcal Infections; Signal Transduction; Streptococcus pneumoniae