Memory B cells in common variable immunodeficiency: clinical associations and sex differences

Common variable immunodeficiency (CVID) is a heterogeneous syndrome characterized by impaired antibody responses, recurrent infections, inflammatory, autoimmune and malignancy-related conditions. We evaluated the relationship between memory B cell phenotype, sex, age at diagnosis, immunologic and clinical conditions in 105 CVID subjects from one medical center. Reduced numbers of switched memory B cells (cutoff Collapse

Key Words

• cvid
• igm memory b cells
• switched memory b cells
• pneumococcal antibody
• sex differences
• igg
• splenectomy

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MESH Headings

• Adolescent
• Adult
• Aged
• Aged, 80 and over
• Antibodies/blood
• Autoimmunity
• B-Lymphocyte Subsets/immunology
• B-Lymphocyte Subsets/metabolism
• Child
• Child, Preschool
• Common Variable Immunodeficiency/immunology
• Common Variable Immunodeficiency/metabolism
• Common Variable Immunodeficiency/surgery
• Female
• Humans
• Immunoglobulin A/blood
• Immunoglobulin G/blood
• Immunologic Memory
• Immunophenotyping
• Male
• Middle Aged
• Pneumococcal Vaccines/immunology
• Pneumococcal Vaccines/metabolism
• Sex Characteristics
• Splenectomy
• Splenomegaly/immunology

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Grants

• AI 101093 NIAID NIH HHS
• P01 AI061093 NIAID NIH HHS
• R18 AI048693 NIAID NIH HHS
• AI-467320 NIAID NIH HHS
• AI-48693 NIAID NIH HHS
• R21 AI101093 NIAID NIH HHS

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Collaborators Collapse

Identification of a novel pneumococcal vaccine antigen preferentially expressed during meningitis in mice

Streptococcus pneumoniae is the most common cause of severe bacterial meningitis in children, the elderly, and immunocompromised individuals. To identify virulence factors preferentially expressed during meningitis, we conducted niche-specific genome-wide in vivo transcriptomic analysis after intranasal infection of mice with serotype 4 or 6A pneumococci. The expression of 34 bacterial genes was substantially altered in brain tissue of mice infected with either of the 2 strains. Ten upregulated genes were common to both strains, 7 of which were evaluated for their role in the development of meningitis. One previously uncharacterized protein, α-glycerophosphate oxidase (GlpO), was cytotoxic for human brain microvascular endothelial cells (HBMECs) via generation of H(2)O(2). A glpO deletion mutant was defective in adherence to HBMECs in vitro as well as in progression from the blood to the brain in vivo. Mutant bacteria also induced markedly reduced meningeal inflammation and brain pathology compared with wild type, despite similar levels of bacteremia. Immunization of mice with GlpO protected against invasive pneumococcal disease and provided additive protection when formulated with pneumolysin toxoid. Our results provide the basis of a strategy that can be adapted to identify genes that contribute to the development of meningitis caused by other pathogens.

23-valent polysaccharide vaccine (PPSV23)-targeted serotype-specific identification of Streptococcus pneumoniae using the loop-mediated isothermal amplification (LAMP) method

Reports of invasive disease due to Streptococcus pneumoniae have declined since the introduction of pneumococcal conjugate vaccines (PCV7 and PCV13). The incidence of invasive diseases due to S. pneumoniae that are not addressed by the vaccines, however, has increased in children and adults, creating a global public health problem. Previously, we established the loop-mediated isothermal amplification (LAMP) method for a PCV13 serotype-specific assay. In the current study, we developed a rapid, simple, and cost-effective assay to detect serotypes in the 23-valent pneumococcal polysaccharide vaccine (PPSV23) using the LAMP method. In this study, LAMP primer sets for serotypes 2, 8, 9N, 10A, 11A, 12F, 15B, 17F, 20, 22F, and 33F of S. pneumoniae were developed. The reactivity, specificity, and sensitivity of LAMP assays were determined and compared to those of conventional PCR. The feasibility of LAMP assays in clinical application in patients with invasive pneumococcal diseases was validated by defining the detection limit of the LAMP assay with bacterial genomic DNA-spiked blood specimens. The specificity of each LAMP assay was determined using 44 serotypes of pneumococcal strains. Their sensitivity was 100 copies per reaction versus 103 to 106 copies per reaction for PCR assays. Using DNA-spiked blood specimens, excluding the LAMP assay that targeted serotype 22F (103 copies per reaction), the limit of detection of the LAMP assay was similar to that with purified DNA as the template (102 copies per reaction), compared with 103 to >106 copies per reaction for PCR assays. In conclusion, a rapid and simple LAMP-based PPSV23-targeted serotype detection assay was developed for use in many countries. This study is the first report of a LAMP-based assay for identification of PPSV23 serotypes. Further evaluation of this assay is needed through surveillance and vaccine efficacy studies.

Differential V gene expression detected in the immune response to Streptococcus pneumoniae capsular polysaccharide between elderly and young adults

Streptococcus pneumoniae is one of the major causative agents of respiratory infections in the elderly population. The 23-valent pneumococcal polysaccharide vaccine is recommended for use in this age group. However, research has indicated that the protective efficacy of the vaccine declines with age. Although similar levels of antibody induction are seen in both young and elderly adults, following immunization with this vaccine, recent studies have indicated that the elderly possess antibodies with lower opsonophagocytic activity and avidity than young adults. We investigated whether a shift in V(H) gene usage may be responsible for this observation. To this end we utilized anti-idiotypic determinants to detect V(H)1 and V(H)3 gene usage by antibodies to pneumococcal capsular polysaccharides in both young and elderly subjects by enzyme-linked immunosorbent assay (ELISA). We found no significant difference in V(H)3 idiotypic expression in antibody responses to capsular polysaccharide from serotype 14 (PPS14). In response to PPS14 a significant higher level of V(H)1 idiotypic expressing antibodies was detected in the elderly as compared with young adults. V(H)1 idiotypic expression in response to capsular polysaccharide from serotype 4 (PPS4) was identical in young and elderly individuals. V(H)3 idiotypic expression in the elderly response to PPS4 was significantly lower than that seen in young individuals. These patterns of idiotypic expression are discussed in relation to recent studies of functional activity of pneumococcal reactive antibodies from young and aged humans.

Novel method for production and purification of untagged pneumococcal surface protein A from clade 1

Streptococcus pneumoniae can cause diseases with high mortality and morbidity. The licensed vaccines are based on capsular polysaccharides and induce antibodies with low cross reactivity, leading to restricted coverage of serotypes. For surpassing this limitation, new pneumococcal vaccines are needed for induction of broader protection. One important candidate is the pneumococcal surface protein A (PspA), which can be classified in 6 clades and 3 families. We have reported an efficient process for production and purification of untagged recombinant PspA from clade 4 (PspA4Pro). We now aim to obtain a highly pure recombinant PspA from clade 1 (PspA1) to be included, together with PspA4Pro, in a vaccine formulation to broaden response against pneumococci. The vector pET28a-pspA1 was constructed and used to transform Escherichia coli BL21(DE3) strain. One clone with high production of PspA1 was selected and adapted to high-density fermentation (HDF) medium. After biomass production in 6 L HDF using a bioreactor, the purification was defined after testing 3 protocols. During the batch bioreactor cultivation, plasmid stability remained above 90% and acetate formation was not detected. The final protein purification process included treatment with a cationic detergent after lysis, anion exchange chromatography, cryoprecipitation, cation exchange chromatography, and multimodal chromatography. The final purification process showed PspA1 purity of 93% with low endotoxin content and an overall recovery above 20%. The novel established process can be easily scaled-up and proved to be efficient to obtain a highly pure untagged PspA1 for inclusion in vaccine formulations. KEY POINTS: • Purification strategy for recombinant PspA1 from Streptococcus pneumoniae • Downstream processing for untagged protein antigens, the case of PspA1 • Purification strategy for PspA variants relies on buried amino acids in their sequences.