Tracking of an Oral Salmonella-Based Vaccine for Type 1 Diabetes in Non-obese Diabetic Mice.

Mohamed I Husseiny,Pablo A Garcia,Fouad Kandeel,Jacques C Mbongue,Nelson Gonzalez,Ali Alhoshani,Jeffrey Rawson,Kevin Ferreri

doi:10.3389/fimmu.2020.00712

Mohamed I Husseiny, Pablo A Garcia + Show 6 more

Open Access

https://doi.org/10.3389/fimmu.2020.00712

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Abstract

Type 1 diabetes (T1D) arises secondary to immune-driven destruction of pancreatic β-cells and manifests as insulin-deficient hyperglycemia. We showed that oral vaccination with live attenuated Salmonella, which simultaneously delivers autoantigens and a TGFβ expression vector to immune cells in the gut mucosa, provides protection against the progression of T1D in non-obese diabetic (NOD) mice. In this study we employed the Sleeping Beauty (SB) transposon system that is composed of a transposase and transposon encoding the td-Tomato to express red fluorescent protein (RFP) to permanently mark the cells that take up the Salmonella vaccine. After animal vaccination, the transposon labeled-dendritic cells (DCs) with red fluorescence appeared throughout the secondary lymphoid tissues. Furthermore, Sleeping Beauty containing tgfβ1 gene (SB-tgfβ1) co-expressed TGFβ and RFP. The labeled DCs were detected predominantly in Peyer’s patches (PP) and mesenteric lymph nodes (MLN) and expressed CD103 surface marker. CD103+ DCs induced tolerogenic effects and gut homing. TGFβ significantly increased programmed death-ligand-1 (PDL-1 or CD274) expression in the DCs in the MLN and PP of treated mice. Also, TGFβ increased cytotoxic T-lymphocyte-associated protein-4 (CTLA-4) levels in CD4+ cells in MLN and PP. Interestingly, DCs increased in all lymphatic organs of mice vaccinated with oral live Salmonella-based vaccine expressing preproinsulin (PPI), in combination with TGFβ, IL10, and subtherapeutic-doses of anti-CD3 mAb compared with vehicle-treated mice. These DCs are mostly tolerogenic in MLN and PP. Furthermore the DCs obtained from vaccine-treated but not vehicle-treated mice suppressed in vitro T cell proliferation. These data suggest that the MLN and the PP are a central hub for the beneficial anti-diabetic effects of an oral Salmonella-based vaccine prevention of diabetes in rodents.

Highlights

Type 1 diabetes (T1D) results from auto-reactive killing of the pancreatic islet insulin-producing β-cells [1]
The expression of TGFβ was detected in supernatant only after infection of macrophages with pSBbi-RP-TGFβ and pCMV(CAT)T7-SB100 (Figure 1B), implying that TGFβ was secreted after expression by host cells under the control of the CMV promoter
We found that CD4+CD25+ Treg cells from vehicle-treated mice efficiently suppressed proliferation and activation of responder T cells when combined with equal amount of dendritic cells (DCs) from vaccinated mice but did not alter proliferation when cultured with DCs from vehicletreated animals (Figure 7A)

Summary

Introduction

Type 1 diabetes (T1D) results from auto-reactive killing of the pancreatic islet insulin-producing β-cells [1]. Oral Vaccine for Type 1 Diabetes antigen-specific vaccines of live attenuated (non-pathogenic) Salmonella typhimurium diabetic autoantigens have been delivered to mice [6, 7]. Fusion of heterologous antigens to specific SPI2-T3SS proteins causes them to be presented to lymphocytes within the gut mucosa [12, 19, 20] This minimizes and/or bypasses intestinal lumen antigen expression and subsequent degradation of the same. A novel diabetes vaccine enabled direct expression of tolerogenic cytokines like TGFβ and IL10 and induced tolerance to diabetic auto-antigens [10, 23] These APCs process and produce the antigens which migrate to other organs in the gut and stimulate the immune cells [9, 24]

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