CAMP and rheumatoid arthritis: LL37 is also present in neutrophil extracellular trap (NET)-like structures and is highly expressed in the skin, inflamed joints, and kidney in chronic diseases such as psoriasis, systemic sclerosis (SSc), psoriatic arthritis (PsA), rheumatoid arthritis (RA), and systemic lupus erythematosus (SLE) [6,7,8,9,10,11,12,13].