TLR4 and infection: Indeed, it was shown that L. (Viannia) panamensis infection results in up-regulation of TLR1, TLR2, TLR3, and TLR4 expression [59], inducing activation of infected macrophages, whereas infection with L. donovani suppresses the TLR2–NF-κB–mediated pro-inflammatory cytokine response [60].