133: Human Osteoarthritis Synovial Fluid Reveals Neuropilin-1 as a Driver of NGF-Mediated Pain

Topic: Basic Science
Subtopic: Pain category (ICD-11), Chronic secondary musculoskeletal pain, , , , , , , , , , Pharmacological interventions, Transgenic models, Behavioral studies

Background and Aims: Osteoarthritis (OA) affects more than 1 out of 7 adults in the U.S. and is the leading cause of chronic pain and disability (1). Although Nerve Growth Factor (NGF) is a validated target for OA pain management (2), clinical trials using NGF-targeting monoclonal antibodies have been limited by serious adverse effects, including joint damage (3, 4). These limitations highlight the need for safer and more selective therapeutic strategies. We identified Neuropilin-1 (NRP1), a non-signaling transmembrane receptor, as a novel co-receptor and modulator of NGF-induced pain signaling (6); however, its role in NGF-mediated OA pain has not been defined.

Methods: Direct NGF–NRP1 interaction was assessed using crosslinking assays and peptide arrays to map the NRP1 binding site on NGF. Functional relevance of NRP1 was evaluated in vivo using the sodium monoiodoacetate (MIA)–induced OA model in mice which were treated with NRP1-targeting agents. Nociceptor-specific roles of NRP1 were examined by selectively silencing Nrp1 in Nav1.8⁺ nociceptors using a Cre-dependent adeno-associated viral vector. NGF levels in human OA synovial fluid were quantified by ELISA. Neuronal excitability was assessed by patch-clamp recordings, and nociceptive responses were evaluated following intra-articular injection of human OA synovial fluid into the mouse knee.

Results: NGF binds the b1 domain of NRP1 via its C-end Rule (CendR) motif and induces NRP1 redistribution at the plasma membrane in HEK293T cells, consistent with ligand-dependent complex formation. Pharmacological and genetic inhibition of NRP1 significantly reduced mechanical allodynia, restored weight-bearing symmetry, and improved motor coordination in MIA-induced OA mice. NGF levels were elevated in human OA synovial fluid compared to non-OA controls. Importantly, an in house NRP1-blocking monoclonal antibody reversed nociceptor excitability and pain behaviors induced by human OA synovial fluid.

Conclusions: Together, these findings identify NRP1 as a critical co-receptor that modulates NGF-driven OA pain signaling at the level of nociceptors. By directly interacting with NGF through its CendR motif, NRP1 facilitates pain-related signaling and neuronal excitability in both preclinical OA models and in response to human OA SF. Selective pharmacological and genetic disruption of the NGF–NRP1 interaction robustly attenuated OA pain behaviors. These results support a model in which NRP1 functions as a key amplifier of NGF-mediated nociception and highlight NRP1 as a promising, more selective therapeutic target for the treatment of osteoarthritis pain.

References: 1. Wang Y, Tang X, Peng JR, Deng Y, Lan S, Yen Y, Tang Y. Global, regional, and national burden of osteoarthritis among middle-aged and older adults: estimates from the global burden of disease study 2021 and projections to 2050. Front Med (Lausanne). 2025 Dec 16;12:1696929. https://doi.org/10.3389/fmed.2025.1696929.
2. Denk, F., Bennett, D. L. & McMahon, S. B. Nerve Growth Factor and Pain Mechanisms. Annu Rev Neurosci 40, 307-325 (2017). https://doi.org/10.1146/annurev-neuro-072116-031121
3. Wise, B. L., Seidel, M. F. & Lane, N. E. The evolution of nerve growth factor inhibition in clinical medicine. Nat Rev Rheumatol 17, 34-46 (2021). https://doi.org/10.1038/s41584-020-00528-4
4. Hochberg, M. C. et al. Long-Term Safety and Efficacy of Subcutaneous Tanezumab Versus Nonsteroidal Antiinflammatory Drugs for Hip or Knee Osteoarthritis: A Randomized Trial. Arthritis Rheumatol 73, 1167-1177 (2021). https://doi.org/10.1002/art.41674
5. Peach, C. J. et al. Neuropilin-1 inhibition suppresses nerve growth factor signaling and nociception in pain models. J Clin Invest 135 (2024). https://doi.org/10.1172/JCI183873

Presenting Author: Elisa Damo
Submitting Author: Elisa Damo

Senior Author: Nigel W Bunnett

IASP 2026 Global Year theme of Neuropathic Pain: No

• Elisa Damo - New York University
• Renato Bruni - New York University
• Raquel Tonello - New York University
• Nestor Jimenez Vargas - New York University
• Mayura Panjalingam - New York University
• Maria Fernanda Pessano Fialho - New York University
• Eric Strauss - New York University
• Saumya Saurabh - New York University
• Shohei Koide - New York University
• Nigel W. Bunnett - New York University