The Vbeta13 T Cell Receptor Monoclonal Antibody Reduces Hyaluronan and CD68+, CD3+, and CD8+ Cell Infiltrations to Delay Diabetes in Congenic BB DRLyp/Lyp Rats.

Marika Bogdani,Malin Fex,Linda Faxius,Elizabeth P Blankenhorn,Anita Ramelius,Åke Lernmark,Anya Wernersson,John P Mordes

doi:10.3389/fendo.2021.629242

Abstract

The depleting Vβ13a T cell receptor monoclonal antibody (mAb) 17D5 prevents both induced and spontaneous autoimmune diabetes in BB rats. Here it was tested in congenic DRLyp/Lyp rats, all of which spontaneously developed diabetes. Starting at 40 days of age, rats were injected once weekly with either saline, His42 Vβ16 mAb, or 17D5 mAb and monitored for hyperglycemia. Diabetes occurred in 100% (n = 5/5) of saline-treated rats (median age, 66 days; range 55–73), and in 100% (n = 6/6) of His42-treated rats (median age, 69 days; range 59–69). Diabetes occurred in fewer (n = 8/11, 73%) 17D5-treated rats at a later age (median 76 days, range 60–92). Three (27%) of the 17D5-treated rats were killed at 101–103 days of age without diabetes (17D5 no-diabetes rats). Survival analysis demonstrated that 17D5 mAb delayed diabetes onset. Saline- and His42-treated rats had severely distorted islets with substantial loss of insulin-positive cells. These rats exhibited prominent hyaluronan (HA) staining, with the intra-islet HA+ accumulations measuring 5,000 ± 2,400 µm2 and occupying 36 ± 12% of islet area, and severe (grade 4) insulitis with abundant infiltration by CD68+, CD3+, and CD8+ cells. The 17D5 mAb-treated rats with delayed diabetes onset exhibited less severe insulitis (predominantly grade 3). In contrast, the 17D5 no-diabetes rats had mostly normal islets, with insulin+ cells representing 76 ± 3% of islet cells. In these rats, the islet HA deposits were significantly smaller than in the diabetic rats; the intra-islet HA+ areas were 1,200 ± 300 µm2 and accounted for 8 ± 1% of islet area. Also, islet-associated CD68+ and CD3+ cells occurred less frequently (on average in 60 and 3% of the islets, respectively) than in the diabetes rats (present in >95% of the islets). No CD8+ cells were detected in islets in all 17D5 no-diabetes rats. We conclude that mAb 17D5 delayed diabetes in DRLyp/Lyp rats and markedly reduced expression of HA and concomitant infiltration of CD68+, CD3+, and CD8+ cells. Our findings underscore the importance of refining immune suppression in prevention or intervention clinical trials to use mAb reagents that are directed against specific T cell receptors.

Highlights

The spontaneously diabetes BB rat was described in 1978 [1] and since 1980 [2] subjected to targeted breeding to dissect the genetic mechanisms underlying islet beta cell destruction [reviewed in [3,4,5]]
The aim of the present study was to administer the 17D5 TCR Vb13 mAb to DRLyp/Lyp rats in an attempt 1) to replicate the delay in onset or prevention of diabetes reported in BB DR rats treated with virus or the viral mimetic polyinosinic:polycytidylic acid as well as in BB-DP [15] and LEW.1WR1 [19] rats; 2) to compare CD3-positive (CD3+) and CD8+ T cell and CD68+ monocyte infiltration to that previously reported in the BB rat [20] and human insulitis [21,22,23,24], and 3) to examine if islet mononuclear cell infiltration affects HA deposition in islets whether the islets were protected from insulitis, or not, by the 17D5 TCR Vb13 mAb
Treatment With 17D5 mAb Delayed or Prevented Diabetes Onset in BBM DRLyp/ Lyp Rats

Summary

Introduction

The spontaneously diabetes BB rat was described in 1978 [1] and since 1980 [2] subjected to targeted breeding to dissect the genetic mechanisms underlying islet beta cell destruction [reviewed in [3,4,5]]. Successive crosses of the lymphopenic, diabetes BB-DP rat with the diabetes resistant, non-lymphopenic BB-DR rat allowed the development of the congenic DRLyp/Lyp rat In this rat, 1) spontaneous diabetes rarely occurs before 50 days of age; 2) 100% of the rats of both sexes develop diabetes before 80 days of age; and 3) a diabetes genetic susceptibility locus, Iddm, was identified proximal to the Gimap mutation [11]. 1) spontaneous diabetes rarely occurs before 50 days of age; 2) 100% of the rats of both sexes develop diabetes before 80 days of age; and 3) a diabetes genetic susceptibility locus, Iddm, was identified proximal to the Gimap mutation [11] This factor was later shown to be a TCR beta chain gene, Tcrb-V13, the Tcrb-V13S1A1 allele. This allele encodes the Vb13a TCR beta chain [11,12,13]

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