At equal concentrations of 1 ng/mL, the proinflammatory cytokine IL-1β, which is elevated in the serum and vitreous humor of patients with DR [31, 32], promoted the strongest elevation of prostanoid production in human Muller glia compared with TNFα, another cytokine also elevated in DR patient serum and vitreous humor, or lipopolysaccharide (LPS), an endotoxin found in gram-negative bacteria that serves as an inflammatory stimulus not related to diabetes (supplemental Fig. 1D). This evidence concerns the gene IL1B and diabetes mellitus.