Journal: Frontiers in Immunology
Article Title: Pro Nerve Growth Factor and Its Receptor p75NTR Activate Inflammatory Responses in Synovial Fibroblasts: A Novel Targetable Mechanism in Arthritis
doi: 10.3389/fimmu.2022.818630
Figure Lengend Snippet: The pro-inflammatory p75NTR/proNGF loop in RA-FLS. (A) Inflammatory stimuli activate an autocrine loop involving proNGF and p75NTR. Inflammatory stimuli strongly induce the contemporary expression of p75NTR, the specific proNGF receptor, and of its ligand, proNGF, in RA-FLS. The increased p75NTR expression results in a higher binding capacity of RA-FLS for proNGF, whose endogenous production is strongly induced by inflammatory stimuli. (B) The active p75NTR/proNGF axis enhances inflammatory cytokines production. The high amounts of endogenously-produced proNGF, released by activated RA-FLS, interact with the p75NTR receptors highly expressed on RA-FLS membrane. The activation of p75NTR intracellular pathways (i.e. p38 and JNK) results in an amplified production of inflammatory cytokines (i.e. IL-6). (C) Inhibition of the p75NTR/proNGF loop decreases inflammatory cytokines production. The blocking of p75NTR using LM11A-31, a small molecule that specifically blocks the binding site of p75NTR for proNGF, results in a net reduction of inflammatory cytokine production (i.e. IL-6). The endogenous proNGF released by active RA-FLS cannot bind to p75NTR and, consequently, does not activate p75NTR intracellular pathways that induce inflammatory cytokine production.
Article Snippet: RA-FLS and OA-FLS were fixed in 4% paraformaldehyde, permeabilized with 0.5% Triton X-100 PBS, incubated for 1 hour at RT with 1% BSA, 5% goat serum (Abcam, Cambridge, UK) PBS and then with mouse anti-p75NTR antibody (Merck, Darmstadt, Germany, clone 8211) or rabbit anti-proNGF (Merck AB9040) and Alexa Fluor secondary antibodies (Invitrogen).
Techniques: Expressing, Binding Assay, Produced, Activation Assay, Amplification, Inhibition, Blocking Assay