FOXP3 and infection: In PBMCs alone, TGF-β1 and FoxP3 expression levels decreased in response to C. trachomatis infection with or without the addition of azithromycin (Fig. 3, B), whereas in the presence of ECC1 cells, TGF-β1 and FoxP3 expression levels were upregulated in response to infection (Fig. 3, a and c).