TNF and polyarteritis nodosa: IL-1ß mRNA levels are increased, but IL-6 levels are decreased, and TNF-alpha levels are minimally increased following PAN treatment: We next looked at downstream inflammatory signatures associated with PRR signaling and discovered that 24 h of PAN treatment leads to an upregulation of IL-1ß mRNA compared to control (p < 0.0001; Figure 1D).