IL-1R1 is expressed by NP TRPV1⁺ sensory neurons of human DRGs. (A and B) Validation of the specificity of the anti–IL-1R1 antibody by the absence of IL-1R1 immunostaining in fresh frozen human DRG sections preincubated with the blocking agent anakinra. (C–N) Immunofluorescence confocal microscopy of a postmortem human lumbar DRG immunostained for IL-1R1 (C, G, and K), TRPV1 (E, H, and L), and CGRP (D, I, and M). (O) Quantification of the relative number of DRG neurons expressing IL-1R1 and TRPV1. Data are expressed as a percentage of the total HuC/D⁺ neuronal population in lumbar DRGs and represent means ± SEM of five individuals. (P) The expression of CGRP was assessed in the total IL-1R1⁺ TRPV1⁺ double-positive subpopulation (set at 100%). Data are shown as mean ± SEM. Scale bars: 200 µm (B and F); 25 µm (J); and 12.5 µm (N).