TLR9 and major depressive disorder: - MS/MDD patients had: ​ ● Higher proliferation and Th17-related cytokine production in CD4+ and CD8+ T-cell cultures in response to TLR2 and TLR4 (but not TLR5 or TLR9) agonists ​ ● Reduced IL-10 release in response to TL4 stimulation in in vitro cultures ​ ● Higher TLR2 and TLR4 expression on CD4+ and CD8+ T-cell surfaces - Treatment of patients with SSRI or in vitro addition of an SSRI resulted in reduced production of Th17-related cytokines in response to agonism of TLR2 and TLR4