Cellular responses at the application site of a high-density microarray patch delivering an influenza vaccine in a randomized, controlled phase I clinical trial.

Alexandra C I Depelsenaire,Katey Witham,Steve Rockman,Jason D Lickliter,James W Wells,Angus H Forster,Christopher D Anderson,Jesse Bodle,Margaret Veitch,Peter Treasure,Germain J P Fernando,Julian Hickling,Patricia Evelyn Fast

doi:10.1371/journal.pone.0255282

Abstract

Microarray patches (MAPs) have the potential to be a safer, more acceptable, easier to use and more cost-effective method for administration of vaccines when compared to the needle and syringe. Since MAPs deliver vaccine to the dermis and epidermis, a degree of local immune response at the site of application is expected. In a phase 1 clinical trial (ACTRN 12618000112268), the Vaxxas high-density MAP (HD-MAP) was used to deliver a monovalent, split inactivated influenza virus vaccine into the skin. HD-MAP immunisation led to significantly enhanced humoral responses on day 8, 22 and 61 compared with IM injection of a quadrivalent commercial seasonal influenza vaccine (Afluria Quadrivalent®). Here, the aim was to analyse cellular responses to HD-MAPs in the skin of trial subjects, using flow cytometry and immunohistochemistry. HD-MAPs were coated with a split inactivated influenza virus vaccine (A/Singapore/GP1908/2015 [H1N1]), to deliver 5 μg haemagglutinin (HA) per HD-MAP. Three HD-MAPs were applied to the volar forearm (FA) of five healthy volunteers (to achieve the required 15 μg HA dose), whilst five control subjects received three uncoated HD-MAPs (placebo). Local skin response was recorded for over 61 days and haemagglutination inhibition antibody titres (HAI) were assessed on days 1, 4, 8, 22, and 61. Skin biopsies were taken before (day 1), and three days after HD-MAP application (day 4) and analysed by flow-cytometry and immunohistochemistry to compare local immune subset infiltration. HD-MAP vaccination with 15 μg HA resulted in significant HAI antibody titres compared to the placebo group. Application of uncoated placebo HD-MAPs resulted in mild erythema and oedema in most subjects, that resolved by day 4 in 80% of subjects. Active, HA-coated HD-MAP application resulted in stronger erythema responses on day 4, which resolved between days 22–61. Overall, these erythema responses were accompanied by an influx of immune cells in all subjects. Increased cell infiltration of CD3+, CD4+, CD8+ T cells as well as myeloid CD11b+ CD11c+ and non-myeloid CD11b- dendritic cells were observed in all subjects, but more pronounced in active HD-MAP groups. In contrast, CD19+/CD20+ B cell counts remained unchanged. Key limitations include the use of an influenza vaccine, to which the subjects may have had previous exposure. Different results might have been obtained with HD-MAPs inducing a primary immune response. In conclusion, influenza vaccine administered to the forearm (FA) using the HD-MAP was well-tolerated and induced a mild to moderate skin response with lymphocytic infiltrate at the site of application.

Highlights

Whilst conventional immunisation routes such as intramuscular (IM), subcutaneous (SC), or intradermal (ID) injection are the standard, dermal immunisation by microneedle array patches (MAPs) offers an alternative [1]
This is believed to be due to the ability of dermal immunisations to deliver the antigen directly into the vicinity of antigen presenting cells (APCs) such as dermal dendritic cells, and the local network of draining lymphatic vessels carrying antigen to the draining lymph nodes [9]
This study demonstrated for the first-time in humans, dose-sparing using high-density MAP (HD-MAP) to deliver a vaccine compared with IM injection [19]

Summary

Introduction

Whilst conventional immunisation routes such as intramuscular (IM), subcutaneous (SC), or intradermal (ID) injection are the standard, dermal immunisation by microneedle array patches (MAPs) offers an alternative [1]. Dermal routes take advantage of the skin’s high abundance of antigen presenting cells (APCs) and have been reported in humans to require only a fraction of the antigen dose needed by IM or SC injection to achieve protective responses [2,3,4,5,6,7,8]. This is believed to be due to the ability of dermal immunisations to deliver the antigen directly into the vicinity of APCs such as dermal dendritic cells (dDCs), and the local network of draining lymphatic vessels carrying antigen to the draining lymph nodes (dLN) [9]. No clinical study to date has assessed the cellular responses in situ at the application sites following vaccine delivery by MAPs, presenting a significant gap in the scientific literature of local skin responses to MAP vaccination

Methods

Results

Conclusion