Effective Polarization of Human Th17 Cells with Biologically Relevant HumanKine® Recombinant Human TGFβ1, TGFβ2, TGFβ3
Transforming growth factors beta (TGFß) are highly pleiotropic cytokines that act as cellular switches and regulate immune function, proliferation and epithelial-mesenchymal transition. These proteins are produced as precursors then a furin-like convertase processes the proprotein to generate an N-terminal latency-associated peptide (LAP) and a C-terminal mature TGFß. Disulfide-linked homodimers of LAP and TGFß remain non-covalently associated after secretion, forming the small latent TGFß complex. Covalent linkage of LAP to latent TGFß binding proteins creates a large latent complex that may interact with the extracellular matrix. Commercially available TGFß proteins are produced as a recombinant protein expressed in CHO cells or as purified native protein from human platelets. Due to complex post-proteolytic modifications, TGFß yield is low and the products are not available in economic bulk quantity. HumanZyme has developed an efficient human-cell based technology, HumaXpress®, for scalable production of human cytokines and produces TGFß1, ß2, and ß3 from engineered human 293 cells. The proteins are highly purified disulfide-linked dimers of 25kD that can be cost-effectively produced in large scale.
TGFßs, which are important for the polarization of murine Th17 cells, are reported not required, and are even inhibitory, for human Th17 polarization. In this study, whole CD4+ cells isolated from a healthy donor were stimulated with 10 µg/ml plate bound aniti-CD3 and 10 µg/ml soluble anti-CD28 in the presence of Th17 polarizing cytokines from HumanZyme and another commercial vendor. After 5 days, supernatants were harvested for measurement of IL-17 by ELISA. The results show that all the HumanKine TGFßs are effective at inducing IL-17 secretion with an optimal concentration of 0.1 ng/ml TGFß.
In contrast, TGFß1 from insect cells showed only marginal or even inhibitory effects. The results indicate that using biologically relevant cytokines can more effectively induce Th17 cell polarization and lead to a more accurate scientific understanding of the human biological process.