Standardization and performance evaluation of mononuclear cell cytokine secretion assays in a multicenter study

BACKGROUND: Cryopreservation of peripheral blood mononuclear cells has been used to preserve and standardize immunologic measurements for multicenter studies, however, effects of cryopreservation on cytokine responses are incompletely understood. In designing immunologic studies for a new multicenter birth cohort study of childhood asthma, we performed a series of experiments to determine the effects of two different methods of cryopreservation on the cytokine responses of cord and peripheral blood mononuclear cells. RESULTS: Paired samples of PBMC were processed freshly, or after cryopreservation in a Nalgene container (NC) or a controlled-rate freezer (CRF). Although there were some differences between the methods, cryopreservation inhibited PHA-induced IL-10 secretion and Der f 1-induced IL-2 secretion, and augmented PHA-induced IL-2 secretion and spontaneous secretion of TNF-α. In separate experiments, NC cryopreservation inhibited secretion of several cytokines (IL-13, IL-10, IFN-γ, TNF-α) by PHA-stimulated cord blood mononuclear cells. With the exception of PHA-induced IL-13, results from fresh and cryopreserved cord blood samples were not significantly correlated. Finally, in reproducibility studies involving processing of identical cell samples in up to 4 separate laboratories, variances in cytokine responses of fresh cells stimulated at separate sites did not exceed those in cryopreserved cells stimulated at a central site. CONCLUSION: Collectively, these studies indicate that cryopreservation can affect mononuclear cell cytokine response profiles, and that IL-10 secretion and antigen-induced responses may be especially vulnerable. These studies also demonstrate that mononuclear cell responses can be standardized for performance in a small number of laboratories for multicenter studies, and underscore the importance of measuring reproducibility and of testing whether cryopreservation techniques alter specific immunologic outcomes

Airway Microbiota Dynamics Uncover a Critical Window for Interplay of Pathogenic Bacteria and Allergy in Childhood Respiratory Disease.

Repeated cycles of infection-associated lower airway inflammation drive the pathogenesis of persistent wheezing disease in children. In this study, the occurrence of acute respiratory tract illnesses (ARIs) and the nasopharyngeal microbiome (NPM) were characterized in 244 infants through their first five years of life. Through this analysis, we demonstrate that >80% of infectious events involve viral pathogens, but are accompanied by a shift in the NPM toward dominance by a small range of pathogenic bacterial genera. Unexpectedly, this change frequently precedes the detection of viral pathogens and acute symptoms. Colonization of illness-associated bacteria coupled with early allergic sensitization is associated with persistent wheeze in school-aged children, which is the hallmark of the asthma phenotype. In contrast, these bacterial genera are associated with "transient wheeze" that resolves after age 3 years in non-sensitized children. Thus, to complement early allergic sensitization, monitoring NPM composition may enable early detection and intervention in high-risk children

Enhanced Neutralizing Antibody Responses to Rhinovirus C and Age-Dependent Patterns of Infection

Knowledge of prevalent RV types, antibody responses, and populations at risk based on age and genetics may guide the development of vaccines or other novel therapies against this important respiratory pathogen.Longitudinal data from the Childhood Origins of ASThma (COAST) birth cohort study were analyzed to determine relationships between age and RV-C infections. Neutralizing antibodies specific for rhinovirus A (RV-A) and RV-C (3 types each) were determined using a novel polymerase chain reaction-based assay. We pooled data from 14 study cohorts in the United States, Finland, and Australia and used mixed-effects logistic regression to identify factors related to the proportion of RV-C versus RV-A detection.In COAST, RV-A and RV-C infections were similarly common in infancy, while RV-C was detected much less often than RV-A during both respiratory illnesses and scheduled surveillance visits (pRhinovirus C (RV-C) can cause asymptomatic infection and respiratory illnesses ranging from the common cold to severe wheezing.To identify how age and other individual-level factors are associated with susceptibility to RV-C illnesses.</div

Airway Microbiota Dynamics Uncover a Critical Window for Interplay of Pathogenic Bacteria and Allergy in Childhood Respiratory Disease.

Repeated cycles of infection-associated lower airway inflammation drive the pathogenesis of persistent wheezing disease in children. In this study, the occurrence of acute respiratory tract illnesses (ARIs) and the nasopharyngeal microbiome (NPM) were characterized in 244 infants through their first five years of life. Through this analysis, we demonstrate that >80% of infectious events involve viral pathogens, but are accompanied by a shift in the NPM toward dominance by a small range of pathogenic bacterial genera. Unexpectedly, this change frequently precedes the detection of viral pathogens and acute symptoms. Colonization of illness-associated bacteria coupled with early allergic sensitization is associated with persistent wheeze in school-aged children, which is the hallmark of the asthma phenotype. In contrast, these bacterial genera are associated with "transient wheeze" that resolves after age 3 years in non-sensitized children. Thus, to complement early allergic sensitization, monitoring NPM composition may enable early detection and intervention in high-risk children

The infant nasopharyngeal microbiome impacts severity of lower respiratory infection and risk of asthma development

The nasopharynx (NP) is a reservoir for microbes associated with acute respiratory infections (ARIs). Lung inflammation resulting from ARIs during infancy is linked to asthma development. We examined the NP microbiome during the critical first year of life in a prospective cohort of 234 children, capturing both the viral and bacterial communities and documenting all incidents of ARIs. Most infants were initially colonized with Staphylococcus or Corynebacterium before stable colonization with Alloiococcus or Moraxella. Transient incursions of Streptococcus, Moraxella, or Haemophilus marked virus-associated ARIs. Our data identify the NP microbiome as a determinant for infection spread to the lower airways, severity of accompanying inflammatory symptoms, and risk for future asthma development. Early asymptomatic colonization with Streptococcus was a strong asthma predictor, and antibiotic usage disrupted asymptomatic colonization patterns. In the absence of effective anti-viral therapies, targeting pathogenic bacteria within the NP microbiome could represent a prophylactic approach to asthma

Effects of Omalizumab on Rhinovirus Infections, Illnesses, and Exacerbations of Asthma.

RATIONALE: Allergic inflammation has been linked to increased susceptibility to viral illnesses, but it is unclear whether this association is causal. OBJECTIVES: To test whether omalizumab treatment to reduce IgE would shorten the frequency and duration of rhinovirus (RV) illnesses in children with allergic asthma. METHODS: In the PROSE (Preventative Omalizumab or Step-up Therapy for Severe Fall Exacerbations) study, we examined children with allergic asthma (aged 6-17 yr; n = 478) from low-income census tracts in eight U.S. cities, and we analyzed virology for the groups randomized to treatment with guidelines-based asthma care (n = 89) or add-on omalizumab (n = 259). Weekly nasal mucus samples were analyzed for RVs, and respiratory symptoms and asthma exacerbations were recorded over a 90-day period during the fall seasons of 2012 or 2013. Adjusted illness rates (illnesses per sample) by treatment arm were calculated using Poisson regression. MEASUREMENTS AND MAIN RESULTS: RVs were detected in 97 (57%) of 171 exacerbation samples and 2,150 (36%) of 5,959 nonexacerbation samples (OR, 2.32; P \u3c 0.001). Exacerbations were significantly associated with detection of rhinovirus C (OR, 2.85; P \u3c 0.001) and rhinovirus A (OR, 2.92; P \u3c 0.001), as well as, to a lesser extent, rhinovirus B (OR, 1.98; P = 0.019). Omalizumab decreased the duration of RV infection (11.2 d vs. 12.4 d; P = 0.03) and reduced peak RV shedding by 0.4 log units (95% confidence interval, -0.77 to -0.02; P = 0.04). Finally, omalizumab decreased the frequency of RV illnesses (risk ratio, 0.64; 95% confidence interval, 0.49-0.84). CONCLUSIONS: In children with allergic asthma, treatment with omalizumab decreased the duration of RV infections, viral shedding, and the risk of RV illnesses. These findings provide direct evidence that blocking IgE decreases susceptibility to RV infections and illness. Clinical trial registered with www.clinicaltrials.gov (NCT01430403)