Serpin e1

phKCs (Lonza) were cultured in KBM‐Gold medium supplemented with KBM‐Gold SingleQuot KC (Lonza) for 3 days before use.¹⁰ Murine neurons were isolated from postnatal d5 C57BL/6 mice after deep anesthetization. The ganglia were digested and cultured in DMEM supplemented with 5% (v/v) FBS (Sigma), 100 U/ml penicillin, 100 μg/ml streptomycin, 1 × B27, and 50 ng/ml nerve growth factor (Sigma). Seven days of culture in the presence of 10 µM cytosine β‐d‐arabinofuranoside (Sigma) enriched >95% neurons characterized by NeuN staining. For RNA‐seq, neurons were incubated with a medium with either Pam3CSK4 (1 µg/ml, Novus), FSL‐1 (1 µg/ml, Sigma), Serpin E1 (20 µg/ml, Raybiotech), or the appropriate vehicle for 6 h.

Sensory neurons were challenged with a medium containing shRNA lentiviral particles specifically targeting PLAUR or ITGAV (HanBio Technology Co. Ltd.), or non‐targeted scrambled lentiviral particles, and incubated for 9 days.³¹ Cells were either lysed for Western blotting using specific antibodies against PLAUR (1:1000, ab103791, Abcam) or ITGAV (1:1000, ab179475, Abcam) for confirmation of gene knockdown efficiency or stimulated with Serpin E1 (20 µg/ml, Raybiotech) for intracellular calcium imaging.

Sensory neurons or phKCs were incubated with Serpin E1 (20 µg/ml, Raybiotech) or OSM (500 ng/ml, R&D) or the appropriate vehicle for 24 h. Cell culture supernatants were collected and subjected to a cytokine array following the manufacturer's protocol (R&D).