TRPV1 and arthritic joint disease: TRPV1 signaling can be activated or facilitated by a number of endogenous factors and intracellular signaling mechanisms, including extracellular protons at levels found in tissue acidosis associated with arthritis and other conditions (94), cannabinoid anandamide (95), bioactive lipids such as LPC (96), and PLA2 (97); these may be modulated in TC because we found changes in amino acids, lipids, PC to LPC levels and evidence for conversion (98).