Effect of growth hormone and IgG aggregates on dendritic cells activation and T‐cells polarization

Abstract

Patients treated with therapeutic biological products (BP) frequently develop anti-drug antibodies (ADA) with potential neutralizing capacities leading to loss of clinical response or serious side effects. BP aggregates have been suggested to promote immunogenicity, thus enhancing ADA production. Dendritic cells (DC) are key effectors in T-cell and B-cell fates, and the subsequent generation of immunogenicity. The objective of this work was to determine if BP aggregates can participate to DC maturation and T-cell activation. We compared aggregates from three different proteins: human growth hormone (hGH), Rituximab, a chimeric anti-CD20 antibody and a serum-purified human IgG1. All three proteins underwent a stir stress, generating comparable populations of aggregated particles. Maturation of human monocyte-derived DC (moDC) upon exposure to native BPs or aggregates was evaluated in vitro. Results showed that hGH aggregates induced an increased expression of moDC co-stimulation markers, and augmented levels of IL-6, IL-8, IL-12p40, CCL2, CCL3, CCL4 and CXCL10. Both antibodies aggregates were also able to modify DC phenotype, but cytokine and chemokine productions were seen only with IL-6, IL-8, IL-12p40 and CXCL10. Aggregates-treated moDC enhanced allogenic T-cell proliferation and cytokines production, suggesting Th1 polarization with hGH, and mixed T-cell responses with antibodies aggregates. These results showed that BP aggregates provoked DC maturation, thus driving adaptive T-cell responses and polarization.

Why the Immune System Should Be Concerned by Nanomaterials?

“…Several studies have shown that under accelerated stress conditions, proteins can give mixtures of soluble aggregates that are submicron species including oligomers or multimers, mostly detected with dynamic light scattering method, and insoluble aggregates that are above the micrometer range (37). This was the case for human growth hormone submitted to a stir stress that gave homogenous aggregates around 892 nm (38), or antibody preparations that underwent stir stress (39), or thermal stress (40, 41). Another study showed the appearance of nanosized antibody aggregates upon heat or pH-shift stress that persisted when preparations were diluted in human serum, highlighting the interactions of aggregated proteins with biological fluids (42).…”

“…As therapeutic proteins can be processed by DCs to be presented to T cells, aggregates can interact with pattern recognition receptors, and then induce DCs activation. Indeed, several studies have shown that antibodies or growth hormone (GH) aggregates have the capacity to induce monocyte-derived dendritic cells maturation, evidenced by an increase in phenotypic markers expression, as well as cytokine or chemokine production (38, 57, 58). Both GH and antibodies aggregates could induce the production of IL-6, IL-8, IL-12p40, and CXCL10 whereas CCL2, CCL3, CCL4 production was only seen with GH aggregates (38).…”

“…Indeed, several studies have shown that antibodies or growth hormone (GH) aggregates have the capacity to induce monocyte-derived dendritic cells maturation, evidenced by an increase in phenotypic markers expression, as well as cytokine or chemokine production (38, 57, 58). Both GH and antibodies aggregates could induce the production of IL-6, IL-8, IL-12p40, and CXCL10 whereas CCL2, CCL3, CCL4 production was only seen with GH aggregates (38). These observations could be extended using the monocytic cell line THP-1, that secreted inflammatory cytokines upon incubation with aggregated intravenous immunoglobulin preparations (55).…”

“…These observations could be extended using the monocytic cell line THP-1, that secreted inflammatory cytokines upon incubation with aggregated intravenous immunoglobulin preparations (55). Antibody aggregates are able to induce an increase in CD4+ T-cell proliferation and to drive T-cell polarization, compared to native counterparts through DCs phenotype modifications (38, 53, 57, 58). Cellular mechanisms by which protein aggregates induce DCs maturation remain to be clarified; however, a few elements are available.…”

Growth Hormone Aggregates Activation of Human Dendritic Cells Is Controlled by Rac1 and PI3 Kinase Signaling Pathways

“…3 We, and others, have previously shown that protein aggregates could act as a danger signal and be recognized by dendritic cells inducing their maturation and CD4 þ T-cell response. 5,6 In a previous work, we demonstrated that human growth hormone (hGH) aggregates were able to induce monocytederived DC (moDC) maturation, showed by a significant increase of surface markers expression and a high production of proinflammatory cytokines and inflammatory chemokines with notably an increase in CXCL10 secretion compared to the native protein.…”