Figure 6.

Detailed histological grading confirms marked reduction of pulmonary inflammation Toll-like receptor (TLR)-2 gene-disrupted animals following intratracheal (i.t.) challenge with Propionibacterium acnes. Pathology of non-sensitized and sensitized wild-type mice (n = 6 in each case) and of sensitized TLR-2^–/– animals (n = 10) was evaluated. As detailed in the text, lungs of P. acnes-sensitized and challenged TLR-2^–/– mice displayed significantly less inflammation than did sensitized, challenged wild-type mice in peribronchovascular, alveolar and interstitial regions. Overall inflammation scores were also significantly lower in TLR-2^–/– mice (a). The percentage of peribronchovascular-lymphatic bundles and veins involved in the inflammatory response to P. acnes was significantly lower in TLR-2^–/– mice than in sensitized wild-type animals (b). Similarly, the overall proportion of the lung tissue involved in the inflammatory response of TLR-2^–/– mice was remarkably lower than that of wild-type mice and, in fact, did not differ significantly from that observed in non-sensitized wild-type mice (c). In all figures, findings in non-sensitized wild-type animals are represented by unshaded bars, sensitized wild-type animals by shaded bars and sensitized TLR-2^–/– mice by striped bars.