TNF and bacterial urinary tract infection: Since the renal CD is the first nephron segment to encounter an ascending UPEC‐UTI, the relative abundances of cytokines (TNFα, IL‐1β, IL‐6) and chemokines (CXCL 1, 2, and 5) mRNA were quantitated in RNA isolated from DBA+ CDs enriched from collagenase‐digested kidney via lectin‐mediated magnetic sorting as described in Methods and outlined in Figure 4.