Cleavage of CD14 and LBP by a protease from Prevotella intermedia

Abstract

Periodontitis is an inflammatory disease caused by subgingival microorganisms and their components, such as lipopolysaccharide (LPS). Responses of the host to LPS are mediated by CD14 and LPS-binding protein (LBP). In this study, it was determined that proteases from a periodontal pathogen, Prevotella intermedia, cleave CD14 and LBP, and thereby modulate the virulence of LPS. Culture supernatants from two strains of P. intermedia (ATCC 25611 and 25261) cleaved CD14 and LBP in a concentration-dependent manner. Zymographic and molecular mass analysis revealed the presence of a membrane-associated, 170-kDa, monomeric protease. Class-specific inhibitors and stimulators demonstrated that this enzyme is a metal-requiring, thiol-activated, cysteine protease. The protease was stable over a wide range of temperatures (4-56 degrees C) and pH values (4.5-8.5). This enzyme also decreased the expression of interleukin-1beta (IL-1beta)-specific mRNA in the LPS-activated macrophage-like cell lines U937 and THP-1 in a concentration-dependent manner, indicating that it also cleaves membrane-associated CD14. Furthermore, addition of soluble CD14 abrogated protease-mediated inhibition of IL-1 mRNA expression induced by LPS. The observations suggest that proteolysis of CD14 and LBP by P. intermedia protease might modulate the virulence of LPS at sites of periodontal infections.

Major Secretory Antigens of the Helminth Fasciola hepatica Activate a Suppressive Dendritic Cell Phenotype That Attenuates Th17 Cells but Fails To Activate Th2 Immune Responses

“…Similar proteases from this family, such as gingipain, a protease from Prevotella intermedia, and bromelain, a protease extracted from pineapple, both cleave CD14 from the surfaces of monocytes, rendering them hyporesponsive to LPS (14). However, we have shown that CD14 surface expression in response to rFhCL1 is unaltered (data not shown).…”

Innate immune responses of gingival epithelial cells to nonperiodontopathic and periodontopathic bacteria

“…F. nucleatum facilitates the colonization of many periodontopathic bacteria (3), invades oral epithelia (28), produces a serine protease (31,32) and induces inflammatory cytokines from host cells (13,33). Similarly, P. intermedia invades oral epithelia and has proteolytic activity (1,34). Furthermore, a weak (but significant) association between the prevalence of these two bacteria and the clinical index of periodontitis has been reported (25).…”

New Insights into Prevotella Diversity and Medical Microbiology

“…LPS of P. nigrescens and of P. intermedia may also contribute to tissue destruction by stimulating the production of nitric oxide in host cells [103,104]. However, a cysteine protease produced by P. intermedia may help attenuate the deleterious effects of LPS by cleaving CD14 and the LPS-binding protein [105]. Bacterial internalization may also induce a cytokine response from invaded cells.…”