# Aptamers Targeting IL17A and Its Receptor Suppress IL17 Signaling in Different Cell Types

## TL;DR

Aptamers targeting IL17A and its receptor effectively suppress inflammation in cell models of rheumatic diseases, offering a potential alternative to monoclonal antibodies.

## Contribution

This study introduces aptamers as a novel alternative to monoclonal antibodies for targeting IL-17A signaling in inflammatory arthropathies.

## Key findings

- Aptamers suppressed IL-17A-induced IL-6 secretion and cell proliferation in PBMCs with 65–85% efficacy.
- RA10-6 maintained high efficacy in axSpA-derived FLS at 24 h, while anti-IL-17A aptamers showed reduced activity.
- Combining receptor-targeting and anti-IL-17A aptamers resulted in synergistic IL-6 suppression.

## Abstract

Background/Objectives: Interleukin-17A (IL-17A) is a key pathogenic cytokine in autoimmune arthropathies. Current monoclonal antibody inhibitors targeting the IL-17/IL-17RA axis demonstrate clinical efficacy but face significant limitations, including immunogenicity, the loss of therapeutic response, and cold-chain storage. Our study evaluated oligonucleotide aptamers targeting IL-17A and its receptor as an alternative to monoclonal antibodies to suppress an IL-17A-induced inflammatory response in cell models relevant to immunoinflammatory rheumatic diseases. Methods: We examined three aptamers: 2′-F-RNA aptamers Apt21-2 and Apt3-4 specific to IL-17A and DNA aptamer RA10-6 targeting the receptor of IL-17A. Their ability to suppress IL-17A functional activity was assessed in peripheral blood mononuclear cells (PBMCs) from healthy donors and personalized fibroblast-like synoviocytes (FLSs) from patients with axial spondyloarthritis (axSpA) and rheumatoid arthritis (RA). Inhibition was measured by quantifying IL-6 and MMP-13 secretion using ELISA and flow cytometry, using secukinumab as a reference control. Results: In PBMC, all aptamers suppressed IL-17A-stimulated IL-6 secretion and cell proliferation in a concentration-dependent manner (17–200 nM), with a 65–85% efficacy, comparable to that of secukinumab. In axSpA-derived FLS, we observed time-dependent efficacy: At 4 h, all three aptamers suppressed IL-6 to the same extent as secukinumab; at 24 h, RA10-6 maintained high efficacy while Apt21-2 and Apt3-4 showed reduced activity. A combination of receptor-targeting RA10-6 with anti-IL-17A aptamers resulted in synergistic IL-6 suppression. All aptamers reduced MMP-13 to basal levels. RA-derived FLS showed diminished responses to all inhibitors. Conclusions: Aptamers demonstrate high specificity and sustained efficacy in suppressing IL-17A signaling for an in vitro model of spondyloarthritis, with superior performance over antibodies. Disease-dependent differential efficacy in RA FLS reflects heterogeneity consistent with limited clinical anti-IL-17 efficacy in RA. These findings show the strong potential of the studied aptamers as an alternative to monoclonal antibodies for IL-17-associated inflammatory arthropathies, particularly spondyloarthritis.