Acylated proteins in Borrelia hermsii, Borrelia parkeri, Borrelia anserina, and Borrelia coriaceae

Acute pancreatitis affects non-parenchymal liver cells by a mechanism dependent on platelet-activating factor

BACKGROUND/AIM

During acute experimental pancreatitis, inflammatory mediators/cytokines are released by the pancreas and enter the portal venous system, reaching the liver. We investigate some aspects of the liver cell function under conditions of acute pancreatitis and the effect of in vivo treatment with a selective platelet-activating factor (PAF) antagonist.

METHODS

Cells were isolated from Wistar rats 24 h after induction of acute pancreatitis by retrograde injection of sodium taurocholate into the main pancreatic duct. The non-parenchymal cell population was separated by Percoll gradient and the adherent cell population (Kupffer cells) obtained. The cells were cultured for 24 h and supernatants assayed for nitrite by Griess reaction and for tumour necrosis factor (TNF) by bioassay in L929 cells. The microbicidal activity was evaluated by killing of Candida albicans. The PAF antagonist WEB2170 (10 mg/kg i.v.) was administered 30 min before induction of pancreatitis.

RESULTS

We found that liver cells produce nitric oxide (NO) only under lipopolysaccharide stimulation and that WEB-2170 treatment reduces the NO production by liver cells in the pancreatitis group only. Cells from both groups produced TNF spontaneously, and the levels were further increased after lipopolysaccharide stimulation. WEB-2170 treatment did not affect the TNF levels. Moreover, killing of C. albicans by Kupffer cells wassignificantly increased by the PAF antagonist.

CONCLUSION

These results suggest that PAF released during acute pancreatitis upregulates the NO production by non-parenchymal liver cells and inhibits Kupffer cell microbicidal activity which could explain the increased bacterial dissemination observed in acute pancreatitis.

Uptake and killing of Leptospira interrogans and Borrelia burgdorferi, spirochetes pathogenic to humans, by reticuloendothelial cells in perfused rat liver

In situ-perfused rat livers were infused with a single dose of 1.5 x 10(7) radiolabeled cells of Leptospira interrogans serovar icterohaemorrhagiae, the agent of leptospirosis, or with Borrelia burgdorferi IRS, the agent of Lyme disease. Significant (P<0.0001) differences in the liver uptake of L. interrogans and of B. burgdorferi were observed, the uptakes being 37.4%+/-2.3% for L. interrogans and 60.5%+/-3.1% for B. burgdorferi. Leptospires, in contrast to borreliae, were recovered from the livers when liver samples were cultured in growth medium. Leptospires but not borreliae were recovered in bile within 30 min of infusion. The association of leptospires and borreliae with reticuloendothelial cells of the liver was demonstrated by immunohistochemistry. Leptospires and borreliae were found to be associated with vimentin-positive cells and not with desmin-positive cells. Few leptospires but no borreliae were also seen associated with vimentin- and desmin-negative cells, suggesting the presence of leptospires outside the sinusoidal spaces, in the liver parenchyma.

Genetic characteristics of Borrelia coriaceae isolates from the soft tick Ornithodoros coriaceus (Acari: Argasidae)

Two Borrelia isolates (CA434 and CA435) cultured from the soft tick Ornithodoros coriaceus were analyzed by contour-clamped homogeneous electric field gel electrophoresis of unrestricted and ApaI-restricted DNA, standard electrophoresis of BamHI- and HindIII-restricted DNA, Southern hybridization, restriction fragment length polymorphism and sequencing of the 16S rRNA gene, and amplification of the 5S-23S intergenic spacer region. These isolates were compared with Borrelia coriaceae type strain Co53, B. burgdorferi sensu stricto strain CA4, and the relapsing-fever spirochete B. parkeri (undesignated). The 16S rRNA region of CA434 and CA435 differed from that of B. coriaceae type strain Co53 by the presence of 1 base (C) at position 367 (GenBank accession no. U42286). The linear plasmid profile of CA434 was similar to that of Co53, and the ApaI, BamHI, and HindIII restriction fingerprints of the total cellular DNA of CA434 and Co53 were similar. In contrast, CA435 differed somewhat from CA434 and Co53, which demonstrates that B. coriaceae is genetically diverse. Southern hybridization showed that the DNAs of CA434 and CA435 hybridized strongly with the digoxigenin-labeled DNA of Co53. Low homology was found between the DNA of Co53 and that of B. parkeri. The 16S rRNA sequence of B. parkeri was identical to previously published results for B. parkeri strain M3001 (GenBank accession number U42296). CA434 and CA435 represent only the second and third isolates of B. coriaceae obtained from any source since its initial isolation from an O. coriaceus tick in 1985. All three B. coriaceae isolates were derived from adult ticks collected from the same locality in northwestern California. Difficulties encountered in detecting B. coriaceae in, and isolating this spirochete from, the tissues of O. coriaceus are discussed. The lack of concordance between different detection or isolation methods suggests that reliance upon a single technique may grossly underestimate the true prevalence of spirochetal infection in wild-caught O. coriaceus ticks.

Specific antibodies reactive with the 22-kilodalton major outer surface protein of Borrelia anserina Ni-NL protect chicks from infection

An outer surface lipoprotein of 22 kDa was identified in the avian pathogen Borrelia anserina Ni-NL by using antibody preparations reactive with bacterial surface-exposed proteins. Amino acid sequence analysis of the 22-kDa protein demonstrated 90% identity with VmpA of B. turicatae, suggesting that the protein belongs to the family of 20-kDa outer surface proteins of the genus Borrelia. All of the 60 chicks intramuscularly treated with antibodies specifically reacting with the 22-kDa protein and infected with strain Ni-NL were completely protected from infection, since no spirochetemia was detected, and from death. Control chicks were treated with immune sera raised against apathogenic strain B. anserina Es, which expresses a prominent 20-kDa polypeptide that is also a member of the Vmp family but does not cross-react immunologically with the 22-kDa protein of the Ni-NL strain. These animals, infected with B. anserina Ni-NL, showed a high degree of spirochetemia 10 days after infection, and all died between 14 and 21 days after infection. The results showed that the 22-kDa surface protein of B. anserina Ni-NL is a determinant of the pathogenic potential of the strain and also confirmed that only strain-specific antibodies are protective against B. anserina infection.

Uptake and killing of Lyme disease and relapsing fever borreliae in the perfused rat liver and by isolated Kupffer cells

In situ-perfused rat livers were infused with a single dose of 1.5 x 10(7) radiolabeled borreliae. Significant (P < 0.00005) differences in the liver uptake of the agents of Lyme borreliosis, Borrelia burgdorferi IRS, Borrelia afzelii VS461, and Borrelia garinii PBi, and that of the agents of relapsing fever, Borrelia hermsii, Borrelia parkeri, and Borrelia turicatae, were observed. The liver uptakes ranged between 65.9% for B. burgdorferi IRS and 40.5% for B. turicatae. Neither relapsing fever nor Lyme disease borreliae were recovered from infected livers when the livers were cultured in Barbour-Stoenner-Kelly II medium. The in vitro uptake of B. burgdorferi IRS by isolated rat Kupffer cells was rapid, and within 30 min of the infection, large intracellular aggregates of amorphous material were detectable by immunofluorescence with specific anti-B. burgdorferi antibody. The reculturing of B. burgdorferi IRS from Kupffer cells incubated for 24 h in RPMI medium before inoculation with bacteria was negative. The results obtained in this study indicated that borreliae are efficiently taken up and killed by rat hepatic macrophages in the absence of serum factors.

Borrelia in pigeons: no serological evidence of Borrelia burgdorferi infection

In order to clarify the supposed involvement of urban pigeons (Columba livia livia) in the epidemiology of Lyme disease, the presence of antibodies against Borrelia burgdorferi and Borrelia anserina in pigeons' sera, collected in 12 areas of northern and central Italy, was evaluated. This evaluation was carried out using a classic immunofluorescence assay (IFA), a surface immunofluorescence assay (SIFA) and a standard Western Blot (WB) assay. A total of 104 out of 3,186 (3.26%) serum samples were positive for both spirochetes when tested by IFA, with titres ranging from 1/40 to 1/1280. All positive specimens showed the same or a higher reactivity against B. anserina than against B. burgdorferi. Of the IFA positive samples, 30 were tested by WB and SIFA to evaluate further the specificity of the antibody response, i.e. to try to clarify against which spirochete the antibodies were raised. The presence of antibodies against the 23 kDa protein exclusive to B. anserina, and against epitopes which are not surface-exposed and which are common to B. anserina and B. burgdorferi, was assessed by WB and SIFA. No serological evidence that B. burgdorferi can infect pigeons was found.

Functional activities of antibodies directed against surface lipoproteins of Borrelia hermsii

Enriched preparations for mouse polyclonal immunoglobulin G (IgG) antibodies reactive with surface-exposed epitopes (Ab-SEE) of the 22-kDa and 24-kDa membrane lipoproteins of living Borrelia hermsii (HS 1 strain) cells were obtained by an antibody absorption technique using living spirochetes. In vitro, the antibody preparations both inhibited spirochetal growth and were borreliacidal in the presence of complement. The monovalent Fab antibody fragments, prepared from antibody-enriched preparations, did not inhibit the growth of the bacteria, whereas they killed the bacteria in the presence of complement. The two-dimension gel electrophoresis of B. hermsii cells showed that 3H-labeled fatty acids incorporated into the 22-kDa and 24-kDa lipoproteins were resolved into one and three compact spots, respectively. The spots were recognized by the Ab-SEE preparations reactive with the 22-kDa and 24-kDa proteins, by Western blotting.