A plant cell-expressed recombinant anti-TNF fusion protein is biologically active in the gut and alleviates immune-mediated hepatitis and colitis.

UNLABELLED: The orally administered BY-2 plant cell-expressed recombinant anti-TNF fusion protein (PRX-106) (n=6) consists of the soluble form of the human TNF receptor (TNFR) fused to the Fc component of a human antibody IgG1 domain.

AIM: To evaluate the immune modulatory effect of the oral administration of plant cells expressing PRX-106.

METHODS

Mice treated with Concanavalin A (ConA) to induce immune hepatitis was orally treated with cells expressing PRX-106 containing 0.5 or 5μg PRX 106. In the colitis model, TNBS-colitis was induced in mice followed by the oral administration of plant cells expressing PRX-106. The immune modulatory effect was determined through follow-up to assess the clinical effect, histology, and serum cytokine levels and by FACS analysis for lymphocyte subsets.

RESULTS

The oral administration of BY-2 cells expressing PRX-106 alleviated immune-mediated liver injury. Serum AST and ALT levels decreased and were comparable to those of mice that had received high-dose steroids. The beneficial effect was also observed as a marked decrease in hepatic necrosis. In the colitis model, the oral administration of BY-2 plant cells expressing PRX-106 alleviated weight loss associated with immune-mediated colitis and improved bowel histology. A reduction in I-IkB-alpha phosphorylation in treated mice was also observed. These effects were associated with a significant alteration in the distribution of CD4+CD25+FOXP3+ cells.

CONCLUSIONS

Plant cells expressing recombinant anti-TNF fusion protein show biological activity when orally administered, exerting an immune modulatory effect through the alleviation of immune-mediated hepatitis and immune-mediated colitis.