Background: Nanoparticles containing gliadin (TAK-101) induce antigen-specific immune tolerance in mouse celiac disease models and in patients with celiac disease. We assessed the duration of the TAK-101 treatment effect in human leukocyte antigen (HLA)-DQ8 transgenic mice, performed a transcriptomic study (bulk RNA-Sequencing [RNA-seq]) of fractionated spleen cells and developed a functional assay to determine the immunoregulatory effect of B cells derived from TAK-101-treated animals.

Methods: Two groups of adult HLA-DQ8 mice were pretreated intravenously on Day −11 and Day −3 with TAK-101 2.5 mg or with an empty nanoparticle control (‘sham’). On Day 0, animals from three groups (‘TAK-101’, ‘sham’ and ‘immunization only’) were immunized with gliadin in complete Freund’s adjuvant and boosted with gliadin in incomplete Freund’s adjuvant on Day 14. A fourth group remained untreated (‘no treatment’). After 1 month, one set of mice from all groups was sacrificed (n = 13–15 mice per group). Two other sets of mice were monitored for 3 or 6 months. From these, mice from all immunized groups were boosted one additional time, 14 days before sacrifice. Spleen cells from each group and time point were independently cultured for 3 days with gliadin, supernatants were collected and interleukin (IL)-17 levels were analyzed by enzyme-linked immunosorbent assay (ELISA). Magnetic-activated cell sorting (MACS)-fractionated splenic T cells derived from the ‘immunization only’ group were cocultured with B cells, with the latter derived either from the ‘no treatment’ or ‘TAK-101’ groups, at variable ratios. Serum anti-gliadin IgG2c antibodies were determined by ELISA. RNA-Seq was performed on splenic MACS-fractionated B cell, T cell, dendritic cell or macrophage RNA.

Results: The results for IL-17 and serum anti-gliadin IgG2c demonstrated that the TAK-101 treatment effect is maintained for at least 6 months in mice. The transcriptomics study pinpointed splenic B cells as the cell population harboring the largest number of genes differentially expressed between the group treated with ‘TAK-101’ and the ‘sham’ group. Finally, B cells from animals from the ‘TAK-101’ but not the ‘no treatment’ groups were able to regulate the secretion of IL-17 by T cells from mice immunized with gliadin (‘immunization only’).

Conclusions: TAK-101 induced a sustained tolerance effect in HLA-DQ8 mice. B cells appear to be important in immunomodulation of the gliadin recall response by TAK-101.

Lisa Barnett

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