Figure 4. Impact of thyroid hormones on N. meningitidis growth.

(A) Effect of THs on meningococcal growth in GC liquid. FAM20 were suspended in GC liquid containing 100 nM T3 or 1 µM T4 and allowed to grow for up to 48 h. At indicated time points, the growth of bacteria was monitored by optical measurement at 600 nm. Bacteria grown in GC liquid were set as a control. (B) Effect of THs on meningococcal growth in serum. Serum was collected from mice treated with T4 or vehicle as described in Figure 1 and mixed with FAM20. As a control, DMEM was mixed with bacteria in the same way. The bacterial solutions were incubated for 1 h at 37°C, plated after serial dilutions and the number of surviving bacteria was counted the next day. Bacterial growth index was defined as (CFU after incubation)/(CFU before incubation) and bacterial growth in DMEM was set as 1. Experiments were performed in triplicate and data are presented as means ±SD.