Temporal dynamics of intradermal cytokine response to tuberculin in Mycobacterium bovis BCG-vaccinated cattle using sampling microneedles

Sabine Steinbach,Sreenidhi Srinivasan,Sonya Middleton,Michael Coad,Darrell J Irvine,Vivek Kapur,Sasan Jalili-Firoozinezhad,Martin Vordermeier,Paula T Hammond,Mariane B Melo,Timm Konold

doi:10.1038/s41598-021-86398-6

Abstract

Bovine tuberculosis (bTB) is a disease of livestock with severe and worldwide economic, animal welfare and zoonotic consequences. Application of test-and-slaughter-based control polices reliant on tuberculin skin testing has been the mainstay of bTB control in cattle. However, little is known about the temporal development of the bovine tuberculin skin test response at the dermal sites of antigen injection. To fill this knowledge gap, we applied minimally-invasive sampling microneedles (SMNs) for intradermal sampling of interstitial fluid at the tuberculin skin test sites in Mycobacterium bovis BCG-vaccinated calves and determined the temporal dynamics of a panel of 15 cytokines and chemokines in situ and in the peripheral blood. The results reveal an orchestrated and coordinated cytokine and local chemokine response, identified IL-1RA as a potential soluble biomarker of a positive tuberculin skin response, and confirmed the utility of IFN-γ and IP-10 for bTB detection in blood-based assays. Together, the results highlight the utility of SMNs to identify novel biomarkers and provide mechanistic insights on the intradermal cytokine and chemokine responses associated with the tuberculin skin test in BCG-sensitized cattle.

Highlights

Bovine Tuberculosis is a disease of economic importance in livestock species such as cattle, sheep and goats and world-wide in distribution
BTB surveilance in the UK is performed with the comparative cervical tuberculin test (CCT, referred to as single intradermal compartive cervical tuberculin test, SICCT) based on the comparative responses to intradermal innoculation of a purified protein derative of tuberculin (PPD) prepared from M. avium and PPD prepared from M. bovis
The microneedle array was coated with a biocompatible alginate-based hydrogel to enable sampling of the interstitial fluid at the site of insertion: an alginate/sucrose solution was dried on the microneedle tines, crosslinked by addition of calcium solution, and dried as previously described[18]

Summary

Introduction

Bovine Tuberculosis (bTB) is a disease of economic importance in livestock species such as cattle, sheep and goats and world-wide in distribution. Whilst tuberculin skin testing of cattle has led to the control and eradication of bTB in many countries, few studies[7] have aimed to study the temporal development of tuberculin-induced injection skin responses and none has evaluated the kinetics of local cytokine and chemokine responses directly at the local sites of PPD injection that drive the hypersensitivity reaction development. Such information would allow mechanistic insights into the development of tuberculin skin test reactivity in bovines, but could lead to improved diagnostic cytokine read-out systems, when local responses can be compared to systemic responses. With these objectives in mind, we sought a minimally-invasive method to collect interstitial fluid directly from skin test sites, thereby obviating the need for serial biopsies from a large number of animals and minimizing animal welfare concerns

Methods

Results

Conclusion