PTGS2 and rheumatoid arthritis: Gene therapy combing with anti-inflammatory effects has shown high potency in RA treatment.299,303 Park et al. demonstrated that the co-delivery of COX-2 siRNA and anti-inflammatory dexamethasone (Dex) showed promising therapeutic efficacy against RA.311 The co-delivery markedly downregulated the apoptosis-related and inflammatory factors, for example, caspase 3 and TNF-α in C28/I2 cells, compared to mono-treatment with Dex.