Impact of Fli-1 transcription factor on autoantibody and lupus nephritis in NZM2410 mice.

The transcription factor Fli-1 is implicated in the pathogenesis of both murine and human lupus. Increased levels of Fli-1 mRNA were present in the peripheral blood lymphocytes from lupus patients; furthermore, transgenic overexpression of Fli-1 in normal mice resulted in the development of a lupus-like disease. Lupus nephritis is a major cause of death in both lupus patients as well as in animal models. In this study, we generated Fli-1 heterozygous knockout (Fli-1(+/)⁻ ) NZM2410 mice (of which the wild-type is a widely used lupus murine model) that expressed decreased levels of Fli-1 and investigated the impact of Fli-1 expression on lupus nephritis development and survival. Ninety-three per cent of the Fli-1(+/)⁻ NZM2410 mice survived to the age of 52 weeks compared to only 35% of wild-type NZM2410 mice. Autoantibodies, including anti-dsDNA and anti-glomerular basement antigen, in Fli-1(+/)⁻ NZM2410 mice were statistically significantly lower when compared to wild-type NZM2410 mice at the ages of 30 and 34 weeks. Total B cell and activated B cell populations in the spleens from Fli-1(+/)⁻ NZM2410 mice were decreased significantly compared to wild-type NZM2410 mice. Fli-1(+/)⁻ NZM2410 mice also had remarkably diminished proteinuria and decreased renal pathological scores when compared with wild-type NZM2410 mice. Expression of early growth response 1 (Egr-1) was decreased significantly in the kidneys from Fli-1(+/)⁻ NZM2410 mice when compared to wild-type littermates. Our data indicate that expression of Fli-1 plays an important role in lupus disease development in NZM2410 mice.

Decreased expression of Fli-1 in bone marrow-derived haematopoietic cells significantly affects disease development in Murphy Roths Large/lymphoproliferation (MRL/lpr) mice.

The transcription factor Fli-1 is implicated in the pathogenesis of both murine and human lupus. Decreased expression of Fli-1 in heterozygous (Fli-1(+/-)) Murphy Roths Large (MRL)/lpr mice resulted in significantly lower kidney pathological scores and markedly increased survival. In this study, bone marrow (BM) transplantation was used to investigate the role of decreased expression of Fli-1 in haematopoietic versus non-haematopoietic cell lineages in autoimmune disease development. Wild-type (WT) MRL/lpr that received BM from Fli-1(+/-) MRL/lpr mice had statistically significantly lower autoantibodies, less proteinuria, reduced renal disease and prolonged survival compared to WT MRL/lpr mice that received BM from WT MRL/lpr mice. Although not statistically significant, Fli-1(+/-) MRL/lpr mice that received BM from WT MRL/lpr mice also had lower autoantibodies and improved survival compared to WT MRL/lpr mice that received BM from WT MRL/lpr mice. Our data indicate that expression of Fli-1 in haematopoietic cell lineages has a significant effect on disease development in MRL/lpr mice.

A Leishmania infantum multi-component antigenic protein mixed with live BCG confers protection to dogs experimentally infected with L. infantum.

The capacity of a quimeric protein, formed by the genetic fusion of five antigenic determinants from four Leishmania proteins, formulated with BCG, to protect dogs against Leishmania infantum infection is described. The data showed that after i.v. administration of 500,000 parasites of the L. infantum M/CAN/ES/96/BCN150 strain, zymodeme MON-1, the animals became infected as suggested by the humoral response against the parasite antigens. All control unvaccinated dogs had parasites in the lymph nodes at day 150 post-infection. One of these unvaccinated infected dog was parasite negative at day 634 behaving, thus, as resistant. In contrast, only 50% of the immunized dogs had parasites in the lymph nodes at day 150 post-infection. Four of these dogs became parasite negative by day 634 post-infection. The control animals developed at various times during the follow-up period clinical symptoms associated with Leishmaniasis. The control diseased dogs developed also in the liver and spleen some of the abnormal histological features associated with natural visceral Leishmaniasis. The immunized dogs, however, were not only normal at the clinical but also at the anatomo-pathological level. A positive delayed type hypersensitivity (DTH) response was observed in nine of the immunized protected dogs. The data indicated that Q+BCG confers 90% protection against infection and at least 90% protection at the clinical level.

Meningeal leishmaniosis induced by Leishmania infantum in naturally infected dogs.

We report two cases of meningitis caused by Leishmania infantum in naturally infected dogs. In both of these dogs the typical phenotypic features of granulomatous meningitis were observed with important lympho-plasma-cellular infiltrates and the presence of large numbers of parasites inside and outside macrophages. The immunological study of the cerebrospinal fluid of both animals showed that a large number of protein bands were recognized by those fluids and that they were similar to the ones recognized by the sera from the same animals. To our knowledge, this is the first description of meningitis associated to leishmaniosis.

Complement component C3 is not required for full expression of immune complex glomerulonephritis in MRL/lpr mice.

Complement activation and tissue deposition of complement fragments occur during disease progression in lupus nephritis. Genetic deficiency of some complement components (e.g., Factor B) and infusion of complement inhibitors (e.g., Crry, anti-C5 Ab) protect against inflammatory renal disease. Paradoxically, genetic deficiencies of early components of the classical complement pathway (e.g., C1q, C4, and C2) are associated with an increased incidence of lupus in humans and lupus-like disease in murine knockout strains. Complement protein C3 is the converging point for activation of all three complement pathways and thus plays a critical role in biologic processes mediated by complement activation. To define the role of C3 in lupus nephritis, mice rendered C3 deficient by targeted deletion were backcrossed for eight generations to MRL/lpr mice, a mouse strain that spontaneously develops lupus-like disease. We derived homozygous knockout (C3(-/-)), heterozygous (C3(+/-)), and C3 wild-type (C3(+/+)) MRL/lpr mice. Serum levels of autoantibodies and circulating immune complexes were similar among the three groups. However, there was earlier and significantly greater albuminuria in the C3(-/-) mice compared with the other two groups. Glomerular IgG deposition was also significantly greater in the C3(-/-) mice than in the other two groups, although overall pathologic renal scores were similar. These results indicate that C3 and/or activation of C3 is not required for full expression of immune complex renal disease in MRL/lpr mice and may in fact play a beneficial role via clearance of immune complexes.

Effect of a genetic deficiency of terminal deoxynucleotidyl transferase on autoantibody production by C57BL6 Fas(lpr) mice.

Terminal deoxynucleotidyl transferase (TdT) adds nontemplate coded nucleotides (N additions) between the recombining ends of immunoglobulin and T cell receptor genes. These nucleotides add significant diversity to the Ig and TCR repertoires. Amino acids coded for by these nucleotides play a key role in the binding of self antigens by autoantibodies and autoreactive T cells. To determine the effect of a lack of N additions on autoantibody production, we bred the TdT knockout genotype onto the autoimmune C57BL/6-Fas(lpr) background. TdT-deficient mice had significantly lower sera anti-DNA and rheumatoid factor activity than their TdT-producing littermates. C57BL/6-Fas(lpr) TdT-deficient mice had shorter VH CDR3 regions and fewer VH CDR3 arginines [0.6% versus 4. 7%] than their TdT-producing littermates. These data indicate that the absence of TdT limited the production of anti-DNA antibodies and rheumatoid factors in C57BL/6-Fas(lpr) mice, likely due to constraints on Ig diversity secondary to the lack of TdT-derived N additions.

Role of the alpha 1 beta 1 integrin complex in collagen gel contraction in vitro by fibroblasts.

Matrix remodeling, critical to embryonic morphogenesis and wound healing, is dependent on the expression of matrix components, their receptors, and matrix proteases. The collagen gel assay has provided an effective model for the examination of the functional role(s) of each of these groups of molecules in matrix remodeling. Previous investigations have indicated that collagen gel contraction involves the beta 1 integrin family of matrix receptors and is stimulated by several growth factors, including TGF-beta, PDGF, and angiotensin II. In particular, collagen gel remodeling by human cells involves the alpha 2 beta 1 and, to a lesser extent, the alpha 1 beta 1 integrin complexes. The present studies were undertaken to determine the role of the alpha 1 integrin chain, a collagen/laminin receptor, in collagen gel contraction by rodent and avian fibroblasts. A high degree of correlation was found between the expression of the alpha 1 beta 1 integrin complex and the relative ability of cells to contract collagen gels. Further studies using antibodies and antisense oligonucleotides against the alpha 1 integrin indicated a significant role for this integrin chain in contraction of collagen gels by rat cardiac fibroblasts. In addition, antibodies to the alpha 1 integrin chain inhibited migration of these fibroblasts on a collagen substratum, suggesting that at least one role of this integrin is in migration of cells in collagen gels. These results indicate that the alpha 1 beta 1 integrin complex plays a significant role in cellular interactions with interstitial collagen that are involved in matrix remodeling such as is seen during morphogenesis and wound healing.