Outer surface lipoproteins ofBorrelia burgdorferivary in their ability to induce experimental joint injury

Abstract

Objective. To examine the ability of bacterial lipoproteins from the spirochete Borrelia burgdorferi to cause in vivo tissue injury (arthritis).Methods. Outer surface proteins (OSPs) from B burgdorferi were used in a rat model of antigen-induced allergic arthritis. Intraarticular challenge with recombinant OspA, OspB, and OspC in nonlipidated (peptide) and lipidated forms was performed in the left knee joint; the contralateral joint received buffer as control. Inflammation was monitored by technetium scintigraphy and histology.Results. Nonlipidated (peptide) OspA, OspB, and OspC did not induce arthritis; the only exception was polymerized OspA, which was tested in preimmunized rats. Lipidated OspA from 2 different strains and lipidated OspC induced severe arthritis, whereas lipidated OspB failed to induce injury. A synthetic analog of the OSP lipid modification, lipopeptide Pam 3 Cys-SerLys 4 -OH, either alone or coupled to bovine serum albumin, also failed to induce injury. Injury did not develop in control groups that were given the appropriate buffers or lipopolysaccharide. This showed that lipidated borrelial OSPs can be potent arthritogens but vary greatly with respect to their injury-inducing potential. The possession of a lipid modification is essential but is not sufficient to render an OSP arthritogenic.Conclusion. This is the first study to demonstrate that individual lipoproteins from B burgdorferi can induce experimental joint injury in vivo. These results may help elucidate the pathogenesis of Lyme arthritis and, above all, underline the importance of bacterial lipoproteins as major virulence factors.Lipoproteins are now being recognized as prime virulence factors of bacteria. For many decades this group of molecules played the role of poor relation to the lipopolysaccharides (LPS), but particularly the discovery that lipoproteins can act as ligands for the Toll-like receptor (TLR) complex has rekindled interest (1). In earlier studies, a number of naturally occurring bacterial lipoproteins and their synthetic lipopeptide analogs were shown to possess impressive biologic activities. The Braun protein, a prototype lipoprotein, can stimulate lymphocytes (2), and the corresponding synthetic lipopeptide is in fact now used as an adjuvant (3). Membrane lipoproteins and the corresponding lipopeptides from mycoplasma could induce mononuclear phagocytes to secrete cytokines; a particular lipopeptide from Mycoplasma fermentans, macrophage activating lipopeptide 2, was effective even at concentrations in the picogram range (4). The outer surface lipoproteins (OSPs) of Borrelia burgdorferi have been shown to exhibit similar stimulatory effects (5-8).Results of recent in vitro studies indicated that the lipid moiety plays a key role, and that the CD14/ TLR-2 receptors can be involved (9-11). Lipoproteins have been shown to be capable of inducing tissue injury in animals, mimicking certain common clinical manifestations of the corresponding infection in man. First, synthetic lipopeptide analogs of treponemal and...

Infection of Mice with Lyme Disease Spirochetes Constitutively Producing Outer Surface Proteins A and B

“…Although the exact etiology of treatment-resistant Lyme arthritis is not known, some investigators believe that an OspA-induced autoimmune reaction is responsible for this condition (1,2,12,18). An arthritic reaction to OspA has also been shown in rats (5), suggesting that constitutive OspA production might lead to higher levels of arthritis. A study by Yang et al (28) showed that an OspAB-negative mutant actually caused a more pronounced arthritis than the wild-type strain, suggesting that OspA is not linked to arthritis in the murine model of Lyme disease.…”

“…Despite the apparent lack of OspA production in rodents, signals present at sites of inflammation in the murine model have been shown to increase OspA production (9). In addition, lipidated OspA injected into rat joints caused arthritis (5). In summary, a large body of work supports the view that B. burgdorferi OspA is primarily a protein that is expressed in the vector for attachment of spirochetes to the tick gut epithelium.…”

Lipoproteins and Diseases of the Brain

“…These components can cause neuropsychiatric manifestations such as lymphocytic meningitis, cranial and peripheral neuropathy, and cerebral infarcts [29,30]. When compared to LPS, bacterial lipoproteins activate inflammatory pathways more vigorously [31], leading to more severe damage to tissue [32]. Bacterial lipoproteins still remain in the tissue even after the degradation of bacteria by antibiotic therapies [33,34].…”

“…at the N-terminus of the peptide is responsible for immune activation and tissue injury [46,47], whereas the peptide portion of ospA is not effective at activating immune pathways [32]. Thus, tripalmitoyl-S-glyceryl-cysteine (Pam3-Cys), a synthetic lipopeptide mimicking the N-termini of osp, is often used for studying bacterial infection in a wide range of research fields involving immunology and neuroscience [48,49].…”

“…Thus, tripalmitoyl-S-glyceryl-cysteine (Pam3-Cys), a synthetic lipopeptide mimicking the N-termini of osp, is often used for studying bacterial infection in a wide range of research fields involving immunology and neuroscience [48,49]. Although all of ospA, ospB, and ospC share common immune pathways (e.g., NF-κB activation) via TLR2, ospA shows higher toxicity to tissues when compared with ospB and ospC [32]. The reason for distinct toxic effects among these different lipoproteins continues to remain elusive.…”