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CD18 hypomorph mice expressing reduced levels of the common {szligbeta}2 integrin chain develop aggravated Lyme carditis, compared to that developed by wild-type (WT) mice, upon infection with the spirochete Borrelia burgdorferi. The enhancement of Lyme carditis in these mice is characterized by increased macrophage infiltration, correlating with augmented expression of the monocyte/macrophage chemoattractant protein 1 (MCP-1). The lack of CD18 results in the deficiency of all {szligbeta}2 integrins, i.e., CD11a/CD18 (LFA-1), CD11b/CD18 (Mac-1/CR3), CD11c/CD18 (p150,95/CR4), and CD11d/CD18. To determine the roles of the various {szligbeta}2 integrins in controlling the development of aggravated Lyme carditis, disease induction was analyzed in CD11a–/–, CD11b–/–, and CD11c–/– mice. CD11a–/– and CD11c–/– mice, but not CD11b–/– mice, developed aggravated Lyme carditis after exposure to B. burgdorferi. Similarly to CD18 hypomorph mice, CD11c–/– mice expressed higher levels of MCP-1, compared to both WT and CD11a–/– mice, as determined by in vitro analysis of MCP-1 secretion by bone marrow-derived dendritic cells and in vivo analysis of MCP-1 mRNA expression in B. burgdorferi-infected hearts. On the other hand, CD11a deficiency was associated with heightened heart B. burgdorferi burden relative to that of WT mice. Overall, our results suggest that the increased severity of Lyme carditis in CD18 hypomorph mice is caused by deficiency in CD11a or CD11c, possibly via different mechanisms.

ABSTRACTCD18 hypomorph mice expressing reduced levels of the common β2 integrin chain develop aggravated Lyme carditis, compared to that developed by wild-type (WT) mice, upon infection with the spirochete Borrelia burgdorferi. The enhancement of Lyme carditis in these mice is characterized by increased macrophage infiltration, correlating with augmented expression of the monocyte/macrophage chemoattractant protein 1 (MCP-1). The lack of CD18 results in the deficiency of all β2 integrins, i.e., CD11a/CD18 (LFA-1), CD11b/CD18 (Mac-1/CR3), CD11c/CD18 (p150,95/CR4), and CD11d/CD18. To determine the roles of the various β2 integrins in controlling the development of aggravated Lyme carditis, disease induction was analyzed in CD11a−/−, CD11b−/−, and CD11c−/−mice. CD11a−/−and CD11c−/−mice, but not CD11b−/−mice, developed aggravated Lyme carditis after exposure to B. burgdorferi. Similarly to CD18 hypomorph mice, CD11c−/−mice expressed higher levels of MCP-1, compared to both WT and CD11a−/−mice, as determined by in vitro analysis of MCP-1 secretion by bone marrow-derived dendritic cells and in vivo analysis of MCP-1 mRNA expression in B. burgdorferi-infected hearts. On the other hand, CD11a deficiency was associated with heightened heart B. burgdorferiburden relative to that of WT mice. Overall, our results suggest that the increased severity of Lyme carditis in CD18 hypomorph mice is caused by deficiency in CD11a or CD11c, possibly via different mechanisms.

OBJECTIVE: To investigate the presence of a host-encoded superantigen as possible etiologic factor in pediatric rheumatic disease. We measured the expression and the ability of interferon-a (IFN-a) to induce the human endogenous retrovirus HERV-K18 superantigen in juvenile rheumatoid arthritis (JRA) and pediatric systemic lupus erythematosus (SLE). METHODS: Expression levels of HERV-K18 were measured in peripheral blood or synovial fluid mononuclear cells (SFMC) from 13 patients with JRA, 11 pediatric SLE patients, and 24 healthy controls, by semiquantitative reverse transcription-polymerase chain reaction, comparing 18S ribosomal transcripts as endogenous standard. IFN-a induction was tested by pretreatment of samples with 2000 U/ml. RESULTS: HERV-K18 expression was significantly elevated in peripheral blood from patients with JRA (mean ratio of HERV-K18 to 18S ribosomal transcripts 2.456, SD 2.122; p = 0.014), but not patients with SLE (mean 0.997, SD 0.579; p = 0.258), compared to controls (mean 0.749, SD 0.598). HERV-K18 transcripts were detected in SFMC of 7/7 JRA patients. IFN-a induced HERV-K18 strongly in JRA (mean fold induction = 8.934, SD 15.556) and controls (mean 8.270, SD 6.609), but weakly in SLE (mean 2.432, SD 2.219; p = 0.009). HERV-K18 levels were found to be independent of previously determined modifiers of expression, including Epstein-Barr virus infection, IFN-a levels, or the percentage of B cells in peripheral blood. CONCLUSION: HERV-K18 superantigen levels were elevated in JRA patients, but not pediatric patients with SLE, suggesting a possible mechanism for autoimmunity in the former group by superantigen stimulation of autoreactive T cells.

Infection of C57BL/6 (B6) mice with the Lyme disease spirochete Borrelia burgdorferi can result in development of arthritis and carditis. B. burgdorferi induces expression of {szligbeta}2/CD18 integrins, adhesion molecules that mediate the firm adhesion of leukocytes to the endothelium necessary for cellular extravasation during inflammation. The important role of {szligbeta}2/CD18 integrins during extravasation suggests that these molecules play a role in the development of Lyme arthritis and carditis. The dependency of these inflammatory processes on the {szligbeta}2 integrins was investigated in CD18 hypomorph mice, which express low levels of CD18. The results indicate that CD18 deficiency did not abrogate development of Lyme arthritis or carditis. Moreover, it resulted in increased severity of Lyme carditis. B. burgdorferi-infected CD18 hypomorph mice showed an increased macrophage infiltration of the heart, while they produced lower levels of borreliacidal anti-B. burgdorferi antibodies compared to wild-type mice. In accordance with these results, we demonstrate that dendritic cells from CD18 hypomorph mice secrete higher levels of monocyte/macrophage chemoattractant protein 1 (MCP-1/CCL2) in response to B. burgdorferi. Similarly, we show by real-time PCR that B. burgdorferi-infected hearts from CD18 hypomorph mice express increased levels of MCP-1 RNA compared to wild-type mice. Overall, our results indicate that {szligbeta}2 integrin deficiency does not abrogate B. burgdorferi-induced inflammation; rather, it results in increased recruitment of macrophages into the B. burgdorferi-infected heart, likely due to the increased expression of MCP-1 in this tissue. Thus, {szligbeta}2 integrins may play a regulatory role in B. burgdorferi-induced inflammation beyond mediating adhesion of leukocytes to the endothelium.

ABSTRACTAntibody responses to outer surface protein A (OspA) of Borrelia burgdorferimay occur during periods of arthritis late in the clinical course of untreated Lyme disease. These antibody responses are paradoxical, given the conclusive evidence demonstrating that B. burgdorferitransmitted to the mammalian host expresses little or no OspA. The parallel occurrence of OspA antibodies and arthritic episodes suggests that OspA expression is upregulated during infection with B. burgdorferi. We hypothesized that this was due to the inflammatory environment caused by the immune response to the spirochete. To test our hypothesis, we adapted an in vivo model that mimics the host-pathogen interaction. Dialysis chambers containing B. burgdorferiwere implanted into the peritoneal cavities of mice in the presence or absence of zymosan, a yeast cell wall extract that induces inflammation. Spirochetes were harvested 2 days later, and OspA expression was assessed at the protein and transcription level by Western blotting and real-time reverse transcription-PCR, respectively. Flow cytometry was also utilized to evaluate OspA protein expression on individual spirochetes. B. burgdorferimaintained in an inflammatory in vivo environment show an increased OspA expression relative to B. burgdorferikept under normal in vivo conditions. Furthermore, host-adapted B. burgdorferiwith a low OspA phenotype upregulates OspA expression when transferred to an inflammatory in vivo environment. The results obtained by these techniques uniformly identify inflammation as a mediator of in vivo OspA expression in host-adapted B. burgdorferi, providing insights into the behavior of live spirochetes in the mammalian host.

Molecular characterization of infectious mouse mammary tumor viruses (MMTVs) has been hampered due to the problem of cloning a full-length exogenous virus into a plasmid. The present report describes our strategy for obtaining a full-length clone of an exogenous MMTV from a mouse mammary tumor that arose spontaneously in a wild Chinese mouse free of endogenous MMTV and shows that the cloned virus (JYG-MMTV) is expressed in rat RBA cells. Four-week-old C58/J × CBA/CaJ female mice, free of both endogenous and exogenous MMTVs, were injected with virus-secreting RBA cells. The progeny of these mice were bred, and their offspring were tested for the presence of MMTV. These third-generation mice were found to actively produce MMTV that was shed in their milk and transmitted to their offspring. The virus was detected not only in the mammary glands of these young mice, but also in their spleens and bone marrow. These results suggest that our plasmid-cloned exogeneous JYG-MMTV is infectious. This virus can now be used effectively in manipulating the various genes of JYG-MMTV and other MMTV strains to understand their structure/function relationships.

To explore further the association of antibiotic treatment–resistant Lyme arthritis and T cell reactivity with outer surface protein A (OspA) of Borrelia burgdorferi, including the identification of T cell epitopes associated with this treatment-resistant course. The responses of peripheral blood and, if available, synovial fluid lymphocytes to B burgdorferi proteins, fragments, and synthetic peptides, as determined by proliferation assay and interferon-γ production, were compared in 16 patients with treatment-responsive and 16 with treatment-resistant Lyme arthritis. The maximum severity of joint swelling correlated directly with the response to OspA. Moreover, the only significant difference between patients with treatment-resistant and treatment-responsive arthritis was in reactivity with N-terminal and C-terminal fragments of OspA, OspA1 (amino acids [aa] 16–106), and OspA3 (aa 168–273). Epitope mapping showed that 14 of the 16 patients with treatment-resistant arthritis had responses to OspA peptides (usually 4 or 5 epitopes), whereas only 5 of the 16 patients with treatment-responsive arthritis had reactivity with these peptides (usually 1 or 2 epitopes) (P = 0.003). Patients with HLA–DRB1 alleles associated with treatment-resistant arthritis were more likely to react with peptide 15 (aa 154–173) and, to a lesser degree, with peptide 21 (aa 214–233) than patients with other alleles, whereas the responses to other epitopes were similar in both groups. The maximum severity of joint swelling and the duration of Lyme arthritis after antibiotic treatment are associated with T cell responses to specific epitopes of OspA.

The addition of AlCl3, to a dichloromethane solution of a triphosphenium tetrachloroaluminate R3P-P-PR3AICI4leads to chloromethylation of the latter, and in a subsequent reaction to the formation of 1,2-diphosphonio-diphosphirane tetrachloroalum inates. It is essential for this second step, that at least one R3P group of the two triphosphenium ions entering the reaction is aminosubstituted. The structure o f the diphosphonio-diphosphirane ions is established by NMR spectroscopy and in one case by X-ray investigation

Thirteen healthy, normal weight young women were studied throughout a control cycle and a diet cycle, during which they lost 1kg per week on a vegetarian 800kcal diet. Blood was sampled daily in the morning, and at weekly intervals, collected at 10-minute intervals for 6 hours. Follicle growth was monitored by ultrasonic measurement. All subjects showed normal cyclic gonadal function during the control cycle. Cyclic gonadal function remained unaltered in two subjects during the diet cycle. No dominant follicle developed in seven others, while another four showed apparently normal follicular development but impaired progesterone secretion by the corpus luteum. Comparison of both cycles revealed that episodic luteinizing hormone (LH) secretion during the follicular phase was altered by dieting. Average LH concentrations and the frequency of episodic secretions were significantly reduced during the follicular phase but not during the luteal phase. Follicle-stimulating hormone was unaltered.

Murine mammary tumor viruses are retroviruses which encode superantigens capable of stimulating T cells via superantigen-reactive T-cell receptor Vß chains. Murine mammary tumor viruses are transmitted to the suckling offspring through the milk. We have established that B cell-deficient pups which were foster-nursed by virus-secreting mice do not transfer infectious murine mammary tumor viruses to their offspring. No murine mammary tumor virus proviruses could be detected in the spleen and mammary tissue of these mice. We conclude that B cells are essential for the completion of the viral life cyclein vivo. This indicates that B cells are infected first and that viral amplification takes place only if infected B cells present the murine mammary tumor virus superantigen on their surface, which, in turn, results in activation of T cells expressing the appropriate T-cell receptor Vß chains. These activated T cells secrete factors which stimulate B cells, enabling viral replication.