Fig. 3.

TLR2 plays a pivotal role in peptidoglycan (PGN) recognition by primary microglia and subsequent proinflammatory cytokine production. TLR2 knockout (KO) and wild-type (WT) microglia were seeded at 2 × 10⁵ cells per well in 96-well plates and incubated overnight. The following day, cells were exposed to 10⁷ heat-inactivated S. aureus, 10 μg/ml PGN, or 100 ng/ml LPS for 24 h. Conditioned supernatants were collected and analyzed for TNF-α (A) and IL-12 p40 (B) by ELISA. Results are presented as the amount of cytokine (ng) per ml of culture supernatant (mean ± SD). Microglial cell viability was assessed using a standard MTT assay and the raw OD₅₇₀ absorbance values are reported (mean ± SD, C). Significant differences between TLR2 WT and KO microglia are denoted with asterisks (**P < 0.001). Results are representative of four independent experiments.