Newborns and infants are at risk of infection and respond sub-optimally to vaccines due in part to impaired Th1-polarizing responses of antigen-presenting cells and lymphocytes. Characterization of the underlying mechanisms may identify novel approaches to neonatal immunization. We have shown that neonatal blood plasma has higher concentrations of adenosine (Ado), an endogenous purine metabolite that acts via Ado receptors to increase cytosolic cyclic Ado mono-phosphate (cAMP) and thereby impairs Th1-polarizing immune responses. Neonatal plasma contains high concentrations of Ado-generating alkaline phosphatase (AP) and 5'ectonucleotidase CD73 while containing less Ado deaminase (ADA) than adult plasma, resulting in higher Ado concentrations at birth. Monocyte (Mo)-derived dendritic cells (MoDCs) are sensitive to Ado inhibition and express cell-associated Ado-generating (CD73) and metabolizing (ADA) enzymes. To better simulate endogenous Ado-based regulation of neonatal immune responses, we have developed an autologous three-dimensional neonatal tissue construct (NTC) and a corresponding adult tissue construct (ATC), comprised of extracellular matrix, autologous plasma, and an overlying endothelium upon which cryopreserved cord blood- or peripheral blood-mononuclear cells or CD33-selected Mos extravasate and autonomous MoDC development and activation can be studied. The project objective is to characterize the impact of neonatal purine metabolism on immune responses to adjuvants, including Toll-like receptor (TLR) agonists, and vaccines, by pursuing the following Specific Aims:
In Aim 1, we will assess the relative contribution of AP, CD73 and ADA to Ado accumulation in human neonatal vs. adult blood plasma. We will employ thin layer chromatography, pharmacologic inhibitors, enzyme immunodepletion, and high performance liquid chromatography. The ontogeny of purine-metabolizing enzymes will be characterized using neonatal and infant plasma samples.
In Aim 2, we will determine effects of soluble and cell-associated AP, CD73 and ADA on activation of autonomously generated MoDCs. We will employ the novel NTC, interrogating the ability of adjuvants and vaccines, such as Bacillus Calmette-Guerin (BCG), hepatitis B vaccine, and pneumoccal conjugate vaccine to induce ADA, modulate Ado levels, and trigger differentiation and activation of mature MoDCs as measured by migration, up-regulation of co-stimulatory molecules, and induction of Th1/Th2/Th17- polarizing cytokines.
In Aim 3, we will characterize enhancing effects of Ado-refractory adjuvants, TLR8 agonists and ADA, on Ag-specific neonatal vaccine responses in vitro. We will employ co-culture of NTC-derived MoDCs and autologous lymphocytes in vaccine antigen prime, boost, and challenge assays using the NTC. These studies will provide insight into neonatal immunity, establish novel platforms for studying immune ontogeny, assess Ado-refractory adjuvants, and inform neonatal vaccine development.

Public Health Relevance

Over 2,000,000 newborns and young infants die due to infection every year, in part due to their relatively weak immune responses. Our project makes use of blood components to model immune responses of newborns and infants to vaccines. By studying mechanisms and factors that impair immune responses early in life, we hope to identify more effective ways to immunize newborns, thereby protecting them from infection and enhancing public health.

Agency
National Institute of Health (NIH)
Institute
National Institute of Allergy and Infectious Diseases (NIAID)
Type
Research Project (R01)
Project #
1R01AI100135-01
Application #
8299300
Study Section
Special Emphasis Panel (ZAI1-LGR-I (J1))
Program Officer
Prabhudas, Mercy R
Project Start
2012-08-16
Project End
2015-07-31
Budget Start
2012-08-16
Budget End
2013-07-31
Support Year
1
Fiscal Year
2012
Total Cost
$435,000
Indirect Cost
$185,000
Name
Children's Hospital Boston
Department
Type
DUNS #
076593722
City
Boston
State
MA
Country
United States
Zip Code
02115
Pettengill, Matthew Aaron; Levy, Ofer (2016) Circulating Human Neonatal Naïve B Cells are Deficient in CD73 Impairing Purine Salvage. Front Immunol 7:121
Fish, Eleanor N; Flanagan, Kate L; Furman, David et al. (2016) Changing oral vaccine to inactivated polio vaccine might increase mortality. Lancet 387:1054-5
Oh, Djin-Ye; Dowling, David J; Ahmed, Saima et al. (2016) Adjuvant-induced Human Monocyte Secretome Profiles Reveal Adjuvant- and Age-specific Protein Signatures. Mol Cell Proteomics 15:1877-94
Pettengill, Matthew A; van Haren, Simon D; Li, Ning et al. (2016) Distinct TLR-mediated cytokine production and immunoglobulin secretion in human newborn naïve B cells. Innate Immun 22:433-43
van Haren, Simon D; Ganapathi, Lakshmi; Bergelson, Ilana et al. (2016) In vitro cytokine induction by TLR-activating vaccine adjuvants in human blood varies by age and adjuvant. Cytokine 83:99-109
Goodridge, Helen S; Ahmed, S Sohail; Curtis, Nigel et al. (2016) Harnessing the beneficial heterologous effects of vaccination. Nat Rev Immunol 16:392-400
Bi, Dan; Qiao, Lili; Bergelson, Ilana et al. (2015) Staphylococcus epidermidis Bacteremia Induces Brain Injury in Neonatal Mice via Toll-like Receptor 2-Dependent and -Independent Pathways. J Infect Dis 212:1480-90
Levy, Orly; Levy, Ofer (2015) Ready to benefit from training: heterologous effects of early life immunization. Trans R Soc Trop Med Hyg 109:3-4
Dowling, David J; Levy, Ofer (2015) Pediatric Vaccine Adjuvants: Components of the Modern Vaccinologist's Toolbox. Pediatr Infect Dis J 34:1395-8
Amenyogbe, Nelly; Levy, Ofer; Kollmann, Tobias R (2015) Systems vaccinology: a promise for the young and the poor. Philos Trans R Soc Lond B Biol Sci 370:

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