Allosteric inhibition of SHP2 uncovers aberrant TLR7 trafficking in aggravating psoriasis

Psoriasis is a complex chronic inflammatory Skin Disease with unclear molecular mechanisms. We found that the Src homology-2 domain-containing protein tyrosine phosphatase-2 (SHP2) was highly expressed in both psoriatic patients and imiquimod (IMQ)-induced psoriasis-like mice. Also, the SHP2 allosteric inhibitor SHP099 reduced pro-inflammatory cytokine expression in PBMCs taken from psoriatic patients. Consistently, SHP099 significantly ameliorated IMQ-triggered Skin Inflammation in mice. Single-cell RNA Sequencing of murine skin demonstrated that SHP2 inhibition impaired Skin Inflammation in myeloid cells, especially Macrophages. Furthermore, IMQ-induced psoriasis-like Skin Inflammation was significantly alleviated in myeloid cells (monocytes, mature Macrophages, and granulocytes)-but not dendritic cells conditional SHP2 knockout mice. Mechanistically, SHP2 promoted the trafficking of Toll-like Receptor 7 (TLR7) from the Golgi to the endosome in Macrophages by dephosphorylating TLR7 at Tyr1024, boosting the ubiquitination of TLR7 and NF-κB-mediated Skin Inflammation. Importantly, TLR7 point-mutant knock-in mice showed an attenuated psoriasis-like phenotype compared to wild-type littermates following IMQ treatment. Collectively, our findings identify SHP2 as a novel regulator of Psoriasis and suggest that SHP2 inhibition may be a promising therapeutic approach for psoriatic patients.