Experimental autoimmune adrenalitis: a murine model for Addison's disease.

Experimental autoimmune adrenalitis was produced in mice by immunizing 8 times or more at intervals of 30 days with syngeneic adrenal extract mixed with Klebsiella O3 lipopolysaccharide (KO3 LPS) as a potent adjuvant. The cortex regions of the adrenal glands after the 8th injection were definitely infiltrated with polymorphonuclear leukocytes (PMN). The main infiltrates in the lesions after the 9th injection were replaced by mononuclear cells, such as small lymphocytes and macrophages, and further by fibrous connective tissues. There were no histological changes in the medullary regions. The repeated immunization developed the delayed type hypersensitivity to adrenal extract and production of anti-adrenocortical autoantibody in those immunized mice. Moreover, the adrenalitis could be produced in normal mice by transfer of spleen cells from hyperimmunized mice, suggesting the critical role of the cell-mediated immunity. This experimental model might be useful to study immunological phenomena in the pathogenesis of Addison's disease.     

Characterization of autoreactive helper T cells in a murine model of autoimmune haemolytic disease.

Repeated immunization of mice with rat red blood cells (RRBC) results in the production of both erythrocyte autoantibodies and anti-RRBC antibodies. The manner in which erythrocyte self-tolerance is broken has been little studied. It has been assumed that help for autoreactive B cells is provided by Th cells specific for the foreign RRBC. We show here that autoreactive Th cells can be recovered from RRBC-immunized mice. The Th cells proliferate in vitro whether stimulated by self or rat erythrocytes. Analysis of the specificity of the proliferating cells revealed extensive cross-reactivity for the two types of erythrocytes. It is therefore surprising that, in initial cultures, a slower response is evident when mouse erythrocytes are used as the antigen. From cytotoxic depletion of T-cell subsets, the phenotype of the proliferating cells was identified as Thy-1.2+, Lyt-1.1+, Lyt-2.1-, L3T4+. During in vitro stimulation of the T cells, growth factors characteristic of Th cells are secreted. Finally, we demonstrate that the responding T cells are able to help primary in vitro antibody responses to self and rat erythrocytes. We conclude that autoreactive Th cells are likely to be involved in the experimental induction of autoimmune haemolytic disease in mice.     

Anomalous renal effects of tin protoporphyrin in a murine model of sickle cell disease

In human and murine models of sickle cell disease (SCD), heme oxygenase-1 (HO-1) is induced in the kidney, an organ commonly involved in SCD. The present study assessed the role of HO-1 by using a competitive inhibitor of HO activity, tin protoporphyrin (SnPP), in protocols affording a composite, clinically relevant analysis of the kidney in SCD under unstressed and stressed conditions. Whereas short-term administration of SnPP exerted comparable renal hemodynamic effects in wild-type and sickle mice, chronic administration of SnPP exerted divergent effects: SnPP provoked tubulointerstitial inflammation and up-regulation of injury-related genes in wild-type mice, whereas in sickle mice SnPP reduced expression of injury-related genes and vascular congestion without provoking tubulointerstitial inflammation. SnPP also protected against the heightened sensitivity to renal ischemia observed in sickle mice, preventing ischemia-induced worsening of renal injury in sickle mice above that observed in wild-type mice. Effective and comparable inhibition of HO activity by SnPP in wild-type and sickle mice was confirmed. These findings suggest that induction of HO-1, at least as assessed by this approach, may contribute to renal injury in this murine model of SCD and uncover an experimental maneuver that protects the kidney in murine SCD.     

Chemokine receptor CCR1 disruption limits renal damage in a murine model of hemolytic uremic syndrome

Shiga toxin (Stx)-producing Escherichia coli is the main etiological agent that causes hemolytic uremic syndrome (HUS), a microangiopathic disease characterized by hemolytic anemia, thrombocytopenia, and acute renal failure. Although direct cytotoxic effects on endothelial cells by Stx are the primary pathogenic event, there is evidence that indicates the inflammatory response mediated by polymorphonuclear neutrophils and monocytes as the key event during HUS development. Because the chemokine receptor CCR1 participates in the pathogenesis of several renal diseases by orchestrating myeloid cell kidney infiltration, we specifically addressed the contribution of CCR1 in a murine model of HUS. We showed that Stx type 2-treated CCR1(-/-) mice have an increased survival rate associated with less functional and histological renal damage compared with control mice. Stx type 2-triggered neutrophilia and monocytosis and polymorphonuclear neutrophil and monocyte renal infiltration were significantly reduced and delayed in CCR1(-/-) mice compared with control mice. In addition, the increase of the inflammatory cytokines (tumor necrosis factor-α and IL-6) in plasma was delayed in CCR1(-/-) mice compared with control mice. These data demonstrate that CCR1 participates in cell recruitment to the kidney and amplification of the inflammatory response that contributes to HUS development. Blockade of CCR1 could be important to the design of future therapies to restrain the inflammatory response involved in the development of HUS.     

Immunology: Defective maternal--fetal interaction in a murine autoimmune model

Anti-cardiolipin antibodies (ACA) are associated with recurrentfetal loss, but their role in this pathological condition isunknown. We recently developed an experimental mouse model ofthe anti-phospholipid syndrome, in which immunization of femalemice with a monoclonal anti-cardiolipin antibody resulted insubstantial failure of pregnancy. We observed that pre-implantationembryos derived from ACA-injected mothers exhibited morphologicalabnormalities and failed to implant in vitro. In the presentstudy, we designed embryo transfer experiments to determinewhether defective embryonic development originated as a maternaldefect, an embryonic defect or both. Embryos (3.5 day old),taken from ACA- and control-immunized mothers were transferredinto either an ACA-or a control-treated uterine environment(day 2.5 pseudo-pregnant females). On day 14 of gestation theincidence of pregnancy, the average number of fetuses per femaleand fetal resorptions were assessed. The ACA-treated uterineenvironment was found to be non-supportive for the developmentand implantation of normal embryos. Moreover, embryos derivedfrom ACA-immunized mothers, even after their removal from theACA-environment and transfer to a normal uterus, remained deficientThese results demonstrate that both the maternal and the embryoniccompartments were defective, as a result of previous exposureto the ACA.     

NO contributes to proliferative suppression in a murine model of filariasis

Infection of BALB/c mice with microfilariae (mf) of Brugia pahangi leads to the suppression of antigen (Ag)-specific proliferative responses in the spleen. The proliferative defect is dependent on inducible nitric oxide synthase (iNOS) activity, since inhibition of iNOS with either L-N-monomethyl arginine (L-NMMA) or aminoguanidine reversed defective proliferation. Splenocytes from mf-infected animals produce high levels of gamma interferon (IFN-gamma) upon in vitro restimulation with Ag, and experiments in IFN-gamma receptor-deficient (IFN-gamma R(-/-)) mice demonstrated that signaling via the IFN-gamma R is essential in the induction of NO production and subsequent proliferative suppression. Restimulation of splenocytes from mf-infected animals with an extract of Acanthocheilonema viteae, a related filarial worm which lacks endosymbiotic bacteria, also resulted in NO production and proliferative suppression, demonstrating that lipopolysaccharide of bacterial origin is not essential to the induction of iNOS activity. These results extend previous observations that infection with different life cycle stages of Brugia leads to the development of differentially polarized immune responses and demonstrate one method by which these differences may exert their effects on the proliferative potential of cells from infected animals.     

The IL-12 role in donor cell engraftment in a murine model of semiallogenic GVH disease with signs of autoimmune disease

We analyzed the IL-12 effect in an autoimmune disease induced in a semiallogenic murine model of graft-vs-host disease (GVHD) Balb/c semiallogenic lymphoid cells i.v. infected in hybrid mice (Balb/c x A/J) F1 (CAF). IL-12 was administered 1 h before cell transplantation following two different protocols: (a) injecting 2 microg of mrIL-12 (murine recombinant IL-12) per mouse before the first semiallogenic cell injection; or (b) injecting the 2 microg of mrIL-12 fractionated in 5 days. ATh1 response was produced but an acute GVHD did not appear although differences in class I and II major histocompatibility complex (MHC) antigens were present. Four days after the semiallogenic cell transfer, IL-12 treated mice showed a marked reduction in the percent of spleen B cells compared with CAF1 control and CAF1 + Balb/c GVHD mice. After 5-6 months of follow-up, the donor cell chimerism increased significantly in spleen (70 +/- 31 vs. 43 +/- 31%) and in thymus. Flow cytometry of spleen lymphocytes demonstrated that donor chimerism was made up of TCD4, TCD8 and B lymphocytes and was higher in animals injected with IL-12. Moreover, CD8 T lymphocytes were 100% donor origin in the IL-12-injected group of GVHD animals and 50% origin in the IL-12-non-injected CAF1 + Balb/c group of animals. This paper shows that: (1) IL- 12 may play a role in the mechanisms of donor cell engraftment, probably produced by a CTL donor anti-host mechanism; (2) no acute GVHD was induced in spite of class I and II MHC differences; (3) IL-12 did not show any effect on the AR-like clinical signs of disease developed in this model of GVHD although histological subclinical signs were less frequent, and no glomerulonephritis was detected in the IL-12-treated GVHD mice.     

Insulin promotes T cell recovery in a murine model of autoimmune myocarditis

Glucose‐insulin‐potassium (GIK) is a useful adjunct to myocarditis. Besides its essential action in energy metabolism, insulin also exerts an anti‐inflammatory effect. This study investigated the effect of insulin on myocardial inflammation in experimental autoimmune myocarditis (EAM) in mice and its potential role in T cell regulation. Mice were divided randomly into a normal control group, a saline‐treated EAM group and an insulin‐treated EAM group. The histopathological changes of myocardium, α‐myosin heavy chain (MyHCα)_614–629 antigen‐specific autoantibody titre, the serum level of cardiac troponin I (cTnI), mitogen‐activated protein kinase (MAPK) family members' activity and content were measured. Furthermore, the phenotype of T lymphocyte subsets in splenocytes was analysed to evaluate the immune status of mice. Insulin reduced serum cTnI of EAM mice on days 14 and 21 (P < 0·05) after immunization, with no changes in blood glucose and autoantibody production. Western blot revealed that extracellular signal‐regulated protein kinase (ERK1/2) may be a determining factor in this process. Total ERK1/2 and phospho‐ERK1/2 (p‐ERK1/2) were both up‐regulated in insulin‐treated mice after immunization. We also found that insulin treatment promoted T cell recovery without changing the naive‐to‐memory T‐cell ratio; in particular, CD3⁺ T cells in insulin‐treated mice proliferated more vigorously than in control mice (P < 0·05). We report here for the first time that insulin alleviates myocarditis in the EAM model. These data show that insulin has a direct effect on T cell proliferation in EAM. It is possible that GIK or insulin may assist T cell recovery towards normal in myocarditis, especially for diabetic or hyperglycaemic patients.     

Type 2 autoimmune hepatitis murine model: the influence of genetic background in disease development

Genetic predisposition is recognized as an important factor for the development of autoimmune hepatitis (AIH). To assess the potential contribution of MHC and non-MHC genes, type 2 AIH was reproduced in three mice strains, taking advantage of their different genetic makeup with regard to MHC and non-MHC genes. Mice (C57BL/6, 129/Sv and BALB/c) were DNA vaccinated with a pCMV-CTLA4-CYP2D6-FTCD plasmid coding for the extracellular region of CTLA-4 and for the antigenic region of the CYP2D6 and FTCD, and with pCMV-IL12. ALT and total IgG levels, liver histology, FACS analysis and liver T-cell cytotoxicity assays were monitored up to 8 months post-injection. C57BL/6 mice showed elevated serum ALT levels, autoantibodies, antigen-specific cytotoxic T-cells and lobular and periportal inflammatory infiltrate. The 129/Sv mice showed slightly elevated ALT levels, sparse liver lobular infiltrate and cytotoxic T-cells. The BALB/c mice showed no liver inflammation. All mice had elevated total serum IgG levels. This murine model of type 2 AIH shows that MHC and non-MHC genes contribute to the susceptibility to autoimmune hepatitis. The understanding of the genetic determinants implicated in AIH development will be a major advance in the study of its pathogenesis and could lead to a better diagnostic approach and preventive strategies.     

Phenotypic characteristics of cells involved in induced suppression to murine experimental autoimmune thyroiditis

Suppression of induced experimental autoimmune thyroiditis can be consistently transferred with spleen cells to syngeneic recipients, provided they are first treated with 200 rads irradiation. Treatment with anti-Thy-1 in vivo immediately prior to transfer abrogates the suppression, while depleting B cells has no effect. The in situ induced tolerance can be prevented by treatment with monoclonal antibodies to the Ly-1 or L3T4 molecules either prior to or post tolerization. Anti-Ly-2 treatment has no effect. In the transfer, again treatment of donors with anti-L3T4 prior to transfer prevents the demonstration of suppression in the recipients, while anti-Ly-2 does not affect suppression. These data suggest that the suppression is being mediated either by a CD4+ T suppressor cell or a CD4+ suppressor inducer cell. Preliminary experiments do not support the possibility of a CD8+ suppressor cell being activated in the recipient.     

The involvement of IL-12 in murine experimentally induced autoimmune thyroid disease.

Experimental autoimmune thyroid disease (EAT) can be induced experimentally in mice following immunization with mouse thyroglobulin (mTg) and the adjuvants lipopolysaccharide (LPS) or complete Freund's adjuvant (CFA). EAT can also be transferred to naive recipients by CD4+ T cells from mTg-primed mice. Here we demonstrate a role for IL-12 in the development of EAT by the ability of neutralizing antibody to IL-12 to reduce disease severity and by the lack of significant levels of thyroid infiltration in IL-12p40-deficient mice following immunization with mTg and CFA. A single injection of 300 ng IL-12 at the time of initial immunization with mTg and LPS was able to increase the degree of thyroid infiltration. These data are all consistent with EAT being a Th1-mediated disease. Conversely, however, administration of IL-12 over a prolonged period markedly inhibited the induction of EAT by mTg and CFA and, if given to recipients, inhibited the transfer of EAT by mTg-primed lymph node cells. The development of an autoantibody response to mTg was also inhibited when IL-12 was administered throughout the experimental period, suggesting that sustained exposure to IL-12 can be immunosuppressive.     

The role of complement in autoimmune renal disease

The predominance of renal involvement in autoimmune diseases can most likely be assigned to the specialised function of the kidneys filtrating over 120 ml plasma per minute. Complement activation by autoantibodies directed against planted antigens or antigens already present in renal tissue in the subendothelial and mesangial regions provoke an inflammatory response ultimately resulting in renal damage. New data also suggest complement involvement in the pathogenesis of renal disease caused by subepithelial immune complex deposition. On the other hand complement itself can also be a target of an autoimmune responses causing renal damage as seen in SLE. The results on intervention of complement activation in clinical practise are awaited.     

Role of SOCS2 in modulating heart damage and function in a murine model of acute Chagas disease

Infection with Trypanosoma cruzi induces inflammation, which limits parasite proliferation but may result in chagasic heart disease. Suppressor of cytokine signaling 2 (SOCS2) is a regulator of immune responses and may therefore participate in the pathogenesis of T. cruzi infection. SOCS2 is expressed during T. cruzi infection, and its expression is partially reduced in infected 5-lipoxygenase-deficient [knockout (KO)] mice. In SOCS2 KO mice, there was a reduction in both parasitemia and the expression of interferon-γ (IFN-γ), tumor necrosis factor-α (TNF-α), IL-6, IL-10, SOCS1, and SOCS3 in the spleen. Expression of IFN-γ, TNF-α, SOCS1, and SOCS3 was also reduced in the hearts of infected SOCS2 KO mice. There was an increase in the generation and expansion of T regulatory (Treg) cells and a decrease in the number of memory cells in T. cruzi-infected SOCS2 KO mice. Levels of lipoxinA(4) (LXA(4)) increased in these mice. Echocardiography studies demonstrated an impairment of cardiac function in T. cruzi-infected SOCS2 KO mice. There were also changes in calcium handling and in action potential waveforms, and reduced outward potassium currents in isolated cardiac myocytes. Our data suggest that reductions of inflammation and parasitemia in infected SOCS2-deficient mice may be secondary to the increases in Treg cells and LXA(4) levels. This occurs at the cost of greater infection-associated heart dysfunction, highlighting the relevance of balanced inflammatory and immune responses in preventing severe T. cruzi-induced disease.     

Characterization of thyroid fibrosis in a murine model of granulomatous experimental autoimmune thyroiditis

This study was initiated to identify and characterize thyroid fibrosis in a murine model of granulomatous experimental autoimmune thyroiditis (G-EAT) and determine if TGF-beta1 might be involved in fibrosis. G-EAT was induced by transfer of mouse thyroglobulin-sensitized spleen cells activated in vitro with thyroglobulin, anti-IL-2R, and IL-12. There was almost complete destruction of thyroid follicles, leading to fibrosis of the gland and reduced serum T4 levels. Fibrosis was confirmed by staining for collagen and alpha smooth-muscle actin, a marker of myofibroblasts. Kinetic studies characterized the onset and development of thyroid fibrosis. TGF-1beta was increased at mRNA and protein levels, and expression of TGF-beta1 protein paralleled G-EAT severity. Comparison of staining patterns showed that TGF-beta1 was expressed in areas of myofibroblast and collagen accumulation, implying that TGF-beta1 may play a role in fibrosis in G-EAT. Further studies demonstrated that myofibroblasts, macrophages, and thyrocytes contributed to TGF-beta1 production. This provides an excellent model to study the mechanisms of fibrosis associated with autoimmune damage.     

Effect of auranofin on autoimmune disease in a mouse model

The effect of an oral gold preparation, auranofin, on the autoimmune disease mouse MRL/l was examined. Oral administration of auranofin on consecutive days from 6 weeks of age reduced anti-DNA antibody production, IgM rheumatoid factor production, hypergammaglobulinemia, polyclonal B cell activation and renal disease, but did not prevent massive lymphadenopathy or restore the low level of either IL-2 production or mitogen response associated with 1pr gene. In contrast to the effect on autoantibody production, little suppressive activity on the immune response to exogenous antigen SRBC was observed. These results indicate that autoimmune disease in MRL/l mice can be prevented without abrogation of T cell abnormalities and that autoimmune-selective suppression can be induced by chemical compound(s) like auranofin.     

Alteration in progression of murine autoimmune disease by treatment with a novel immunomodulator, SM-8849.

The effects of SM-8849 on the development of autoimmune disease in MRL/Mp-1pr/1pr mice were examined. SM-8849 improved survival as well as renal disease, restored the deficits in splenic cell responsiveness to stimulation by mitogens or conventional antigens, and prevented lymphadenopathy and splenomegaly coincident with a decrease in the number of Thy-1+/Lyt-2-/L3T4- cells. SM-8849 also suppressed the production of the B-cell differentiation factor, possibly with a resulting preferential reduction of autoantibodies. In addition, SM-8849 depressed the production of hydrogen peroxide from macrophages. These results suggest that the administration of SM-8849 to a subject with autoimmune diseases can induce immunological improvements with possible clinical effectiveness.     

Comparison of differentially expressed genes in T lymphocytes between human autoimmune disease and murine models of autoimmune disease

A general view is that critical genes involved in biological pathways are highly conserved among species. To understand human autoimmune diseases, a great deal of effort has been devoted to the study of murine models that mirror many pathologic properties observed in the human disease. We have found that lymphocytes from humans with different autoimmune disease all carry a common conserved gene expression profile. Therefore, we wanted to determine if lymphocytes from common murine models of autoimmune disease carried a gene expression profile similar to the human profile and if both mouse models carried a shared gene expression profile. We identified numerous differentially expressed genes (DEGs) in the autoimmune strains compared to non-autoimmune strains. However, we found very little overlap in the gene expression profile between human autoimmune disease and murine models of autoimmune disease and between different murine autoimmune models. Our research further confirms that murine models of autoimmunity do not perfectly match human autoimmune diseases.     

Adoptive transfer murine model of granulomatous experimental autoimmune thyroiditis

Experimental autoimmune thyroiditis (EAT) is a chronic inflammatory autoimmune disease that can be induced in genetically susceptible animals by immunization with mouse thyroglobulin (MTg) in an appropriate adjuvant or by the adoptive transfer of MTg-sensitized donor spleen cells, activated in vitro with MTg, into naive recipients. In the adoptive transfer model used in our laboratory, donor cells activated with MTg alone induce a relatively mild chronic lymphocytic form of EAT (L-EAT), in which the thyroid infiltrate consists primarily of mononuclear cells, and the thyroid inflammation persists for several months. When the same donor cells are activated with MTg together with anti-IL-2R and/or IL-12, a more severe and histologically distinct granulomatous form of EAT is induced in recipient mice. In addition to having distinct histopathologic features, granulomatous EAT (G-EAT) differs from L-EAT in that granulomatous thyroid lesions are not chronic. After reaching maximal severity 21 days after cell transfer, G-EAT thyroid lesions either resolve or the thyroids become atrophic and fibrotic by day 35. In this review, the histopathologic features of G-EAT and L-EAT are described, and our studies with the adoptive transfer G-EAT model which have focused on the mechanisms involved in induction of G-EAT in mice, and the evolution of G-EAT lesions to resolution of inflammation or fibrosis, are reviewed.     

Host-protective immunity and its suppression in a parasitic disease: murine cutaneous leishmaniasis

The accumulation of knowledge on the cellular immunology of host parasite relationships can be very rapid when infection of mice with a human parasite causes a disease resembling that seen in man. This is so of Old World cutaneous leishmaniasis (‘oriental sore’). As must be the case in all chronic infectious diseases, manifestations of the clinical disease spectrum in cutaneous leishmaniosis reflect both host and parasite factors. In this article Graham Mitchell describes how this spectrum can be exploited in inbred mice injected with isolates of Leishmania trop ica major (L. major) for detailed analysis of interactions between host and parasite.