Microphysiologic Human Tissue Constructs Reproduce Autologous Age-Specific BCG and HBV Primary Immunization in vitro

Abstract

Current vaccine development disregards human immune ontogeny, relying on animal models to select vaccine candidates targeting human infants, who are at greatest risk of infection worldwide, and receive the largest number of vaccines. To help accelerate and de-risk development of early-life effective immunization, we engineered a human age-specific microphysiologic vascular-interstitial interphase, suitable for pre-clinical modeling of distinct age-targeted immunity in vitro. Our Tissue Constructs (TCs) enable autonomous extravasation of monocytes that undergo rapid self-directed differentiation into migratory Dendritic Cells (DCs) in response to adjuvants and licensed vaccines such as Bacille Calmette-Guérin (BCG) or Hepatitis B virus Vaccine (HBV). TCs contain a confluent human endothelium grown atop a tri-dimensional human extracellular matrix substrate, employ human age-specific monocytes and autologous non heat-treated plasma, and avoid the use of xenogenic materials and exogenous cytokines. Vaccine-pulsed TCs autonomously generated DCs that induced single-antigen recall responses from autologous naïve and memory CD4+ T lymphocytes, matching study participant immune-status, including BCG responses paralleling donor PPD status, BCG-induced adenosine deaminase (ADA) activity paralleling infant cohorts in vivo, and multi-dose HBV antigen-specific responses as demonstrated by lymphoproliferation and TCR sequencing. Overall, our microphysiologic culture method reproduced age- and antigen-specific recall responses to BCG and HBV immunization, closely resembling those observed after a birth immunization of human cohorts in vivo, offering for the first time a new approach to early pre-clinical selection of effective age-targeted vaccine candidates.

BCG as a Case Study for Precision Vaccine Development: Lessons From Vaccine Heterogeneity, Trained Immunity, and Immune Ontogeny

“…BCG is considered a 'self-adjuvanted' vaccine, as components of the formulation capable of engaging multiple Pattern Recognition Receptors (PRRs), including Toll-like receptor (TLR)2 and TLR4 (Heldwein et al, 2003), TLR8 (Dowling et al, 2017), as well as the C-type lectin receptors Dectin-1 and Mincle (Yadav and Schorey, 2006;Matsunaga and Moody, 2009;Schoenen et al, 2010) are thought to enhance vaccineinduced immunity. Unlike hepatitis B vaccine which requires multiple doses to achieve lymphoproliferation, BCG induces single shot lymphoproliferation (Sanchez-Schmitz et al, 2018). Most recently, in an Indian adult human cohort, a hypermorphic gain of function single nucleotide polymorphism in TLR8, a PRR that is activated by microbial single stranded RNA, was associated with improved BCG vaccine-mediated protection against pulmonary TB (Ugolini et al, 2018).…”

Artificial Intelligence Applied to in vitro Gene Expression Testing (IVIGET) to Predict Trivalent Inactivated Influenza Vaccine Immunogenicity in HIV Infected Children

“…Four out of five of the subset/condition selected for the final score included the stimulated condition and more precisely three out of the five refer to data derived from the difference in gene expression between the stimulated and unstimulated condition. Overall these results suggest that this in vitro stimulation approach in combination with others in vitro tests recently described ( 34 ) may provide important information in term of prediction of vaccine responsiveness and early pre-clinical selection of effective vaccine candidates for VPs. Our data may thus confirm that gene expression after a relatively short (16 h) in vitro stimulation may emulate early transcriptional changes that were analyzed in vivo both in mice ( 35 ) and in humans ( 36 , 37 ).…”

Neonatal monocytes demonstrate impaired homeostatic extravasation into a microphysiological human vascular model

“…Human type I collagen solution (VitroCol, 3 mg/mL) was purchased from Advanced Biomatrix (San Diego, CA 3D vascular-interstitial model. Building from prior tissue engineering efforts 31,77 , our three-dimensional model consists of a confluent quiescent monolayer of human endothelial cells grown over a basement mem- Figure 7. Neonatal monocytes demonstrate impaired homeostatic extravasation into a microphysiological human vascular model.…”

“…To better characterize the autonomous extravasation capacity of human newborn monocytes, we followed a tissue engineering approach to recreate the microanatomy and physiology of a human capillary vein and compared the extravasation of newborn and adult monocytes under more natural circumstances. Consisting of a confluent monolayer of primary human endothelial cells grown atop an extracellular matrix cushion, our three-dimensional (3D) vascular-interstitial interphase model enables the homeostatic translocation of purified monocytes through quiescent endothelia in the absence of exogenous cytokines 31 . Using this microphysiological tissue construct (TC) both the CD16− and CD16+ newborn monocytes demonstrated lower adherence and homeostatic extravasation through quiescent endothelia as compared to adult monocytes.…”