Antibodies to extracellular matrix proteins in the sera of MRL-lpr mice

The peripheral benzodiazepine receptor ligand PK 11195 inhibits arthritis in the MRL-lpr mouse model

OBJECTIVE

Mice of the MRL-lpr strain develop a severe autoimmune arthritic condition when primed with complete Freund's adjuvant. The pathology is similar to that seen in human rheumatoid arthritis. We investigated whether PK 11195, a powerful ligand for peripheral benzodiazepine receptors, would have preventative or therapeutic effects in this model.

METHODS

MRL-lpr mice were primed with complete Freund's adjuvant at 13-14 weeks of age. Daily PK 11195 injections were started on the same day as priming to test for preventative effects. Daily PK 11195 injections were started 10 days after priming to test therapeutic effects.

RESULTS

PK 11195 showed both preventative and therapeutic effects. At 1 mg/kg/day, it inhibited disease onset. At 3 mg/kg/day, it inhibited established disease progression.

CONCLUSION

The evidence suggests that PK 11195 may be the prototype of a new class of anti-inflammatory agents.

Genetic dissection of lupus pathogenesis: a recipe for nephrophilic autoantibodies

Sle1 and Sle3 are 2 loci that confer susceptibility to lupus nephritis in the NZM2410 strain of mice. Our previous work has shown that B6.NZMc1 mice, congenic for Sle1, exhibit loss of tolerance to chromatin but do not develop any pathogenic autoantibodies or disease. B6.NZMc7 mice, congenic for Sle3, exhibit low-grade polyclonal B- and T-cell activation, elevated CD4/CD8 ratios, and mildly penetrant glomerulonephritis. In contrast to these monocongenics, the present study reveals that B6.NZMc1|c7 mice, bicongenic for Sle1 and Sle3, exhibit splenomegaly, significantly expanded populations of activated B and CD4(+) T cells, and a robust, variegated IgG autoantibody response targeting multiple components of chromatin (including double-stranded DNA), intact glomeruli, and basement membrane matrix antigens. As one might predict, these mice, particularly the females, exhibit highly penetrant glomerulonephritis. These findings lend strong support to a two-step epistatic model for the formation of pathogenic, nephrophilic autoantibodies in lupus. Whereas loci such as Sle1 may serve to breach tolerance to chromatin, full-blown pathogenic maturation of the autoantibody response appears to require additional input from other loci (such as Sle3) and gender-based factors.

Surface topography and serum concentration affect the appearance of tenascin in human gingival fibroblasts in vitro

Tenascin is an extracellular matrix glycoprotein which affects cell behavior such as cell migration. This study was undertaken to investigate the time of appearance of tenascin (TN) in human gingival fibroblasts (HGF) and how it was affected by the surface topography of the titanium substratum or by serum concentration in the medium. HGF were cultured for 4 to 24 h and then processed for confocal immunofluorescence microscopy. Very few cells stained positive for TN 4 h after plating, but the number of TN-positive HGF gradually increased between 8 and 18 h after plating. The increase in the rate of the proportion of TN-positive cells on the grooved surface lagged behind that of HGF cultured on the smooth surface. The number of TN-positive cells in medium + 15% serum was significantly greater than that of cells in 5% serum or serum-free medium. The number of TN-positive cells was greater on the smooth titanium surface than on the grooved titanium surface in both 15% serum and 5% serum-containing medium. These findings suggest that TN production by fibroblasts in vitro can be modulated by factors in serum and by the surface topography of the substratum.

Evaluation of the immunotoxicity of benzoporphyrin derivative (BPD-MA) in mice

Photodynamic therapy has been shown to selectively eliminate activated lymphocytes in a number of experimental situations. These findings have important implications in therapies involving selective immunomodulation. In this study we report the effects of intravenous dosing with the photosensitizer benzoporphyrin derivative-monoacid A(BPD) on normal immunological function. Therapeutic doses of BPD and light had no effect on natural killer cell activity, the mixed lymphocyte reaction, cell-mediated lympholysis, the primary immune response to sheep red blood cells, or the secondary memory response to T cell-dependent antigens. In non-light treated controls, BPD at concentrations up to 10-fold higher had a limited effect on cell-mediated lympholysis. We conclude that the primary effect of BPD in several therapeutic modalities in not due to a generalized suppression of the immune system.

Serum laminin and basic fibroblast growth factor concentrations in patients with complicated Plasmodium falciparum malaria

Serum concentrations of laminin and basic fibroblast growth factor (FGF) were measured in 20 patients suffering from complicated Plasmodium falciparum malaria in Bangkok. Significant higher mean serum concentrations of laminin were determined prior to treatment (1973 ng/ml) and 7 days after starting medication (1025 ng/ml) in comparison to the control (412 ng/ml). The values remained numerically higher for at least 21 days. With regard to serum basic FGF concentrations, a peak was found 7 day after starting treatment (35.61 pg/ml). In addition, a significant correlation was found for parasite clearance time and basic FGF concentration on day 7 (P < 0.01). These increased values of laminin and basic FGF may be the consequence of endothelial and basement membrane damage induced by sequestration of the parasites. Furthermore, basic FGF might play a role in endothelial repair mechanisms after the clearance of the parasites.

In vitro detection of apoptotic stimuli by use of the HL-60 myeloid leukemic cell line

The human histiocytic lymphoma line HL-60 has served as a model of myeloid cell differentiation and can be induced to differentiate along the neutrophil or monocytic lineage, depending on the external stimulus. The nondifferentiated cell line retains a premyeloid leukemic phenotype and is capable of anchorage-independent growth and proliferation. The role of apoptosis in the regulation of immunologic and inflammatory events associated with homeostasis and disease has been most intensively studied in lymphocytes. In the present study, nondifferentiated HL-60 has served as a model for studying myeloid cell apoptosis by investigating apoptotic changes induced by camptothecin, a DNA topoisomerase inhibitor, as well as physiologic stimuli, including ceramide analogs and a monoclonal antibody against the Fas antigen. Multiparameter flow cytometry was used to evaluate apoptosis by measuring changes in both side scatter and propidium iodide staining. The appearance of apoptotic cells was confirmed biochemically by measuring DNA endonuclease activity by both enzyme-linked immunosorbent assay quantitation and DNA ladder formation on agarose gels and morphologically with the detection of micronuclei by confocal laser microscopy. These studies demonstrate that HL-60 can serve as an in vitro model for the detection of physiologic and pharmacologic apoptotic stimuli and for understanding the early and late cellular changes associated with induction of the apoptotic program.

Stimulation of enzyme and cytokine production by methyl mercaptan in human gingival fibroblast and monocyte cell cultures

The volatile sulphur compound methyl mercaptan (CH3SH) is a by-product of protein metabolism and a principal component of oral malodour. This investigation examines the effect of CH3SH on the enzymatic activities of cathepsins B and G and elastase, and on the production by human gingival fibroblasts of two key factors, prostaglandin E (PGE) and cAMP, of the PGE2-cAMP-dependent pathway, which may contribute to the increased production of collagenase and tissue destruction in human periodontal disease. The results demonstrate that CH3SH alone, or in combination with interleukin-1 (IL-1) or lipopolysaccharide, can significantly enhance the secretion of PGE2, cAMP and procollagenase by human gingival fibroblasts. CH3SH also stimulated mononuclear cells to produce IL-1, which can increase cAMP production, and act in synergism with the direct effect of CH3SH on cAMP. CH3SH also significantly enhanced the activity of cathepsin B, moderately suppressed that of cathepsin G, but did not significantly affect elastase. These results provide evidence that CH3SH could be a contributing factor in the enzymatic and immunological cascade of events leading to tissue degradation in periodontal diseases.

Evaluation of a model for post-partum arthritis and the role of oestrogen in prevention of MRL-lpr associated rheumatic conditions

Sixty-eight percent of female MRL-lpr mice developed a post-partum exacerbation of their mild spontaneous arthritis within 30 days of parturition. The flare became evident between 5 and 15 days after delivery. Histologically it was characterized by a significant increase of subsynovial inflammation and synovial hyperplasia without changes in the level of cartilage and bone erosion. Immunohistologically, marked subsynovial and frequent synovial staining of MHC class II bearing cells was noted, along with the sporadic presence of CD3, CD4, and CD43 receptor-bearing cells in the subsynovium. Injection of physiological levels (0.08 mg/kg) of estradiol on days 2, 3, 9, 15 and 20 post-partum delayed and reduced the flare to 23% of the animals. Administration of pharmacological amounts (0.4 mg/kg per day for 2 weeks following Freund's complete adjuvant injection) prevented adjuvant-enhanced arthritis, reducing the incidence from 67% to the baseline 21% level. Deleterious changes in the underlying systemic lupus erythematosus (SLE), as demonstrated by proteinuria and mortality rate increases, were elicited only by the employed pharmacological amounts of estradiol. These results indicate that the MRL-lpr mice might serve as a model for post-partum flare of arthritis in SLE and rheumatoid arthritis by providing an approach to study the complexity of the effects of pregnancy on autoimmune diseases, and to obtain further evidence for the involvement of oestrogen in arthritis.

Photodynamic therapy; a comparison with other immunomodulatory treatments of adjuvant-enhanced arthritis in MRL-lpr mice

Although numerous experimental immunomodulatory regimens have been reported to be effective in the treatment of rheumatoid arthritis, they also produce undesirable side effects. An alternative specific modality of localized treatment is photodynamic therapy (PDT). In this study we treated 13-week-old MRL-lpr mice whose spontaneous arthritis was enhanced by intradermal injection of Freund's complete adjuvant (FCA). One group received transcutaneous photodynamic therapy at days 0, 10, and 20, following the FCA injection. The other groups were injected with 1 mg/kg per day indomethacin, 40 mg/kg per day cyclosporin A (CsA), or treated with 3 Gy sublethal whole body irradiation (WBI). The development of swelling was monitored for 1 month, at which time proteinuria, lymphadenopathy and the histopathology of the joints and kidneys were assessed. The results demonstrated that PDT and the conventional treatments significantly ameliorated swelling of the hindlimbs from 70% in the untreated FCA-injected animals to below the 19% level characteristic of the unmanipulated control. Histological examination showed a reduction in pannus formation, and cartilage and bone destruction, the characteristics of adjuvant-enhanced arthritis. PDT did not affect the survival rate, lymphoproliferation, or proteinuria of the treated animals. However, indomethacin increased proteinuria, and was less effective in preventing cartilage and bone destruction. Furthermore, lower doses of CsA and WBI exacerbated arthritis activity. These results indicate that photodynamic therapy can inhibit the development of adjuvant-enhanced arthritis in MRL-lpr mice with similar effectiveness to the conventional treatments, but without their negative side effects.

Spontaneous development of anti-collagen type II antibodies with NTA, and anti-DNA antibodies in senescence-accelerated mice

We previously reported that circulating natural thymocytotoxic autoantibody (NTA) and IgG-anti-DNA antibodies were the major serological characteristics of a substrain of SAM, SAM-P/1. We present here a study of ageing in which we further measured and compared various kinds of circulating IgG antibodies including anti-collagen type II, rheumatoid factor (RF), and anti-2,4,-dinitrophenol (DNP), between SAM-P/1 and control SAM-R/1 mice. The results showed that age-associated increases in anti-collagen type II antibodies in SAM-P/1 were distinctively higher than those in SAM-R/1 when the mice were over 4 months of age, and the increases were significantly correlated with increases in NTA, anti-DNA antibodies, RF activities and anti-DNP antibodies. Anti-collagen type II antibody activity was not significantly inhibited by preincubating the antibodies with DNA, IgG-Fc and DNP-BSA samples. These findings suggest that antibodies specifically directed against collagen type II can be produced in a background of polyclonal B cell activation, and that these antibodies in association with NTA and anti-DNA antibodies may play a pathogenic role in the development of accelerated senescence in SAM-P/1 mice.