Several studies described an imbalance of the Treg to Th17 ratio in psoriasis.30,31 It was reported that the percentage of CD4+CD25+Foxp3+ (Tregs) was increased and that the percentage of CD4+IL-17+ (Th17) cells was decreased in rheumatoid arthritis after MSC treatment.32 Junji Xu et al. reported that MSC infusion directed T cells toward Treg and Th2 cells while suppressing Th17 responses and alleviating Sjogren syndrome (SS) symptoms.13 Collectively, these studies suggest that MSCs play an important role in regulating immune homeostasis. This evidence concerns the gene CD4 and psoriasis.