SLC15A4 and systemic lupus erythematosus: Lack of SLC15A4 is related with impaired function of SLE pathogenesis associated cytokines and protein, such as toll-like receptor 7 (TLR7)- and TLR9 dependent cytokines including type 1 interferon (IFN) and nucleotide oligomerization domain-1 (NOD1)13,14.