Catalase expression of Propionibacterium acnes may contribute to intracellular persistence of the bacterium in sinus macrophages of lymph nodes affected by sarcoidosis

We examined catalase expression in culturedP. acnes isolated from 19 sarcoid and 18 control lymph nodes and immunohistochemical localization of the protein in lymph nodes from 43 sarcoidosis and 102 control patients using a novelP. acnes-specific antibody (PAC) that reacts with the catalase protein, together with the previously reportedP. acnes-specific PAB and TIG antibodies. High catalase expression ofP. acnes cells was found during stationary phase in more isolates from sarcoid than from non-sarcoid lymph nodes and was associated with bacterial survival under H2O2-induced oxidative stress. In many sarcoid and some control lymph nodes, catalase expression was detected at the outer margins of PAB-reactive Hamazaki-Wesenberg (HW) bodies in sinus macrophages, the same location as catalase expression on the surface of culturedP. acnes and the same distribution as bacterial cell membrane-bound lipoteichoic acid in HW bodies. Some or no catalase expression was detected in sarcoid granulomas with PAB reactivity or in clustered paracortical macrophages packed with many PAB-reactive small-round bodies. HW bodies expressing catalase may be persistentP. acnes in sinus macrophages whereas PAB-reactive small-round bodies with undetectable catalase may be activatedP. acnes proliferating in paracortical macrophages. Intracellular proliferation ofP. acnes in paracortical macrophages may lead to granuloma formation by this commensal bacterium in sarcoidosis patients with Th1 hypersensitivit...
Source: Immunologic Research - Category: Allergy & Immunology Source Type: research