Local mechanical stimuli like pressure may also trigger the release of neuropeptides, such as nerve growth factor (NGF), and alarmin cytokines like interleukin-33 (IL-33) by mast cells in inflamed skin, mediating immune reactions and sensory neuron activation that further augments Th2-inflammation through the mechanical stress-induced exacerbation, leading to the presence of wheals and itch of pressure-related urticaria (Figure 3) [37]. This evidence concerns the gene NGF and urticaria.