Immuno-based profiling of knee osteoarthritis patients identifies baseline characteristics associated with positive response to autologous platelet-rich plasma injection at one-year follow-up

Background Osteoarthritis (OA) is a degenerative musculoskeletal disease of multifactorial origin causing chronic disability, despite numerous treatment options for which there are no predictive biomarkers on the different endotypes. We aimed at defining a peripheral blood (PB) profile potentially predictive of early and sustained response to intra-articular injection of autologous platelet-rich plasma (PRP). Methods A prospective study was conducted on male and female patients aged 40–74 years, with Kellgren-Lawrence knee OA grade 2–3 candidates to PRP injection. PB was obtained from patients at enrollment prior to PRP injection to assess immune phenotype of PBMCs with multiparametric flow cytometry; serum antioxidant capacity; PBMC expression of molecules involved in inflammatory pathways; serum concentrations of related inflammatory cytokines and chemokines. After one year of follow-up, response was defined based on WOMAC questionnaires and clinical criteria and correlated with the immune profile. Results Among 109 enrolled patients, 60 had early and sustained response to treatment and 49 were non-responders, irrespective of age, sex, and previous conservative therapy or surgery. Responders had lower oxidative stress and a peculiar profile of inflammatory markers (higher CD40L, Eotaxin 1; G-CSF, GROα, MIP3b, and PD-L1; lower TNFα, PTX3, and PDGF-AA) and immune cell composition (higher circulating CD14 + ; higher central memory CD8 + , lower effector memory CD4 + and terminal effector CD4 + and CD8 + cells; lower Tregs) in the PB at baseline. Discussion We describe an immunophenotype associated with early and sustained response to PRP treatment in knee OA and submit that this may be candidate to validation for predicting clinical benefit.