Local Administration of Soluble CD40:Fc to the Salivary Glands of Non-Obese Diabetic Mice Does Not Ameliorate Autoimmune Inflammation

Nienke Roescher,Toshimitsu Uede,Zhenan Lai,Jelle L Vosters,John A Chiorini,Paul P Tak,Esther Lutgens

doi:10.1371/journal.pone.0051375

Abstract

ObjectiveCD40–CD154 (CD40 ligand) interaction in the co-stimulatory pathway is involved in many (auto)immune processes and both molecules are upregulated in salivary glands of Sjögren’s syndrome (SS) patients. Interference within the CD40 pathway has ameliorated (auto)inflammation in a number of disease models. To test the potential role of the CD40 pathway in loss of gland function and inflammation in SS, an inhibitor of CD40-CD154 interaction was overexpressed in the salivary glands (SGs) of a spontaneous murine model of SS; the Non-Obese Diabetic (NOD) mouse.Materials and MethodsAt different disease stages an adeno associated viral vector encoding CD40 coupled to a human Fc domain (CD40:Fc) was injected locally into the SGs of NOD mice. Delivery was confirmed by PCR. The overall effect on local inflammation was determined by assessment of the focus score (FS), quantification of infiltrating cell types, immunoglobulin levels, and microarray analysis. The effect on SG function was determined by measuring stimulated salivary flow.ResultsCD40:Fc was stably expressed in the SG of NOD mice, and the protein was secreted into the blood stream. Microarray analysis revealed that expression of CD40:Fc affected the expression of many genes involved in regulation of the immune response. However, FS, infiltrating cell types, immunoglobulin levels, and salivary gland output were similar for treated and control mice.DiscussionAlthough endogenous CD40 is expressed in SG inflammatory foci in the SG of NOD mice, the expression of soluble CD40:Fc did not lead to reduced overall inflammation and/or improved salivary gland function. These data indicate possible redundancy of the CD40 pathway in the SG and suggests that targeting CD40 alone may not be sufficient to alter the disease phenotype.

Highlights

The inflammatory foci observed in the salivary gland (SG) of non-obese diabetic (NOD) mice resemble the foci comprised of mononuclear cells seen in salivary glands (SGs) of patients with Sjogren’s syndrome (SS) [1]
CD40:Fc was stably expressed in the SG of NOD mice, and the protein was secreted into the blood stream
Discussion: endogenous CD40 is expressed in SG inflammatory foci in the SG of NOD mice, the expression of soluble CD40:Fc did not lead to reduced overall inflammation and/or improved salivary gland function

Summary

Introduction

The inflammatory foci observed in the salivary gland (SG) of non-obese diabetic (NOD) mice resemble the foci comprised of mononuclear cells seen in SGs of patients with Sjogren’s syndrome (SS) [1]. SS is a chronic inflammatory autoimmune disease mainly affecting the lachrymal and salivary glands (LG and SG respectively). It is very common with an estimated prevalence of 0.5%–2% in the general population (of which 9 out of 10 is female). The local autoimmune process is characterized by the influx of T cells and to a lesser degree B cells, and a variety of other immune cells that accumulate in the secretory glands and reorganize over time [2] It is unclear what initiates the inflammatory process, but the upregulation of costimulatory-, adhesion- and antigen-presenting molecules is thought to play a role in the recruitment and the organization of inflammatory cells in the SG of both patients and mice. CD154 can be found in the clustered infiltrating cells [5,6]

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