Proline metabolism plays an essential part in innate immune response, as infection of Caenorhabditis elegans with P. aeruginosa, results in the catabolism of Pro into P5C by proline dehydrogenase (PRODH), with the resultant P5C regulating ROS homeostasis and SKN-1 activation, to induce antibacterial response (208). This evidence concerns the gene PYCR1 and infection.