In chronic inflammation, a key step in the formation process of ELF is the transition of resident stromal cells (e.g., fibroblasts) to LTo-like phenotype after receiving the stimulation of inflammatory stimuli: for example, in synovial tissues of RA patients, the enhancement of IL-6 signal can lead to increased IL-7 production in synovial fibroblasts, which can induce LTi recruitment into the affected tissues and promote ELF formation (57–60). This evidence concerns the gene IL6 and rheumatoid arthritis.