Susceptible Mouse Strains Research Articles

A hole in the T-cell repertoire induced after retroviral infection of immunocompetent adult mice

Background Acute virus infections resolve following the establishment of host immune responses, and this is also true for infections with most simple retroviruses. Thus, inoculation into neonates and the resultant induction of immune tolerance are required for the development of murine gammaretrovirus-induced leukemia/lymphoma. On the other hand, most complex retroviruses establish persistent infection in immunocompetent adult animals and induce pathologies after a prolonged latent period. Friend virus (FV) composed of two simple gammaretroviruses, replication-competent Friend murine leukemia virus (F-MuLV) and acutely growth-inducing but defective spleen focus-forming virus, is a prominent exception to the above general rules and can induce a rapid development of fatal leukemia when inoculated into immunocompetent adult mice of susceptible strains [1]. Virus antigen-reactive CD8 cells undergo an unusually rapid process of exhaustion in the presence of massively expanding FV-infected cells [2], resulting in profound failure in maintaining FV-specific memory T cells. However, even when acute splenomegaly is resolved in resistant animals, they cannot reject FV-induced leukemia cells and die after tumor cell injection, suggesting that FV-infected mice fail to generate virus antigen-specific naive T cells.

Virus‐induced dilated cardiomyopathy is characterized by increased levels of fibrotic extracellular matrix proteins and reduced amounts of energy‐producing enzymes

The most relevant clinical phenotype resulting from chronic enteroviral myocarditis is dilated cardiomyopathy (DCM). Mice of the susceptible mouse strain A.BY/SnJ mimick well human DCM since they develop as a consequence of persistent infection and chronic inflammation a dilation of the heart ventricle several weeks after coxsackievirus B3 (CVB3) infection. Therefore, this model is well suited for the analysis of changes in the heart proteome associated with DCM. Here, we present a proteomic survey of the dilated hearts based on differential fluorescence gel electrophoresis and liquid chromatography-mass spectrometric centered methods in comparison to age-matched non-infected hearts. In total, 101 distinct proteins, which belong to categories immunity and defense, cell structure and associated proteins, energy metabolism and protein metabolism/modification differed in their levels in both groups. Levels of proteins involved in fatty acid metabolism and electron transport chain were found to be significantly reduced in infected mice suggesting a decrease in energy production in CVB3-induced DCM. Furthermore, proteins associated with muscle contraction (MLRV, MLRc2, MYH6, MyBPC3), were present in significantly altered amounts in infected mice. A significant increase in the level of extracellular matrix proteins in the dilated hearts indicates cardiac remodeling due to fibrosis.

Model systems duplicating epidermolysis bullosa acquisita: A methodological review

Epidermolysis bullosa acquisita (EBA) is a chronic mucocutaneous autoimmune skin blistering disease, in which generation of autoantibodies to type VII collagen (COL7) is the key factor for pathogenesis. Much of this current understanding of EBA pathogenesis has been obtained through the development and further application of respective model systems. In vitro model systems of EBA duplicate neutrophil activation by immune complexes of COL7 and anti-COL7 antibodies. Blister induction by anti-COL7 antibodies can be reproduced ex vivo by incubation of cryosections of human skin with anti-COL7 antibodies and neutrophils. Furthermore, EBA can be induced in mice by transfer of human or rabbit anti-COL7 IgG into adult mice, or by immunization of susceptible mouse strains with an immunodominant fragment within the non-collagenous 1 domain of COL7. However, our understanding of EBA pathogenesis is largely limited to mechanisms in autoantibody-induced tissue injury. Furthermore, these model systems of EBA have not been used to a large extent to evaluate the potential of novel treatment options. To foster a broader use of these elaborate model systems to specifically address these open issues, this review focuses on a detailed description of model systems for EBA, which should allow for a broad use of these models. This will hopefully lead to a better understanding of EBA pathogenesis, as well to a benefit in patient care.

Immunotherapy of Murine Retrovirus-Induced Acquired Immunodeficiency by CD4 T Regulatory Cell Depletion and PD-1 Blockade

LP-BM5 retrovirus induces a complex disease featuring an acquired immunodeficiency syndrome termed murine AIDS (MAIDS) in susceptible strains of mice, such as C57BL/6 (B6). CD4 T helper effector cells are required for MAIDS induction and progression of viral pathogenesis. CD8 T cells are not needed for viral pathogenesis, but rather, are essential for protection from disease in resistant strains, such as BALB/c. We have discovered an immunodominant cytolytic T lymphocyte (CTL) epitope encoded in a previously unrecognized LP-BM5 retroviral alternative (+1 nucleotide [nt]) gag translational open reading frame. CTLs specific for this cryptic gag epitope are the basis of protection from LP-BM5-induced immunodeficiency in BALB/c mice, and the inability of B6 mice to mount an anti-gag CTL response appears critical to the initiation and progression of LP-BM5-induced MAIDS. However, uninfected B6 mice primed by LP-BM5-induced tumors can generate CTL responses to an LP-BM5 retrovirus infection-associated epitope(s) that is especially prevalent on such MAIDS tumor cells, indicating the potential to mount a protective CD8 T-cell response. Here, we utilized this LP-BM5 retrovirus-induced disease system to test whether modulation of normal immune down-regulatory mechanisms can alter retroviral pathogenesis. Thus, following in vivo depletion of CD4 T regulatory (Treg) cells and/or selective interruption of PD-1 negative signaling in the CD8 T-cell compartment, retroviral pathogenesis was significantly decreased, with the combined treatment of CD4 Treg cell depletion and PD-1 blockade working in a synergistic fashion to substantially reduce the induction of MAIDS.

H5N1 Influenza Virus Pathogenesis in Genetically Diverse Mice Is Mediated at the Level of Viral Load

ABSTRACTThe genotype of the host is one of several factors involved in the pathogenesis of an infectious disease and may be a key parameter in the epidemiology of highly pathogenic H5N1 influenza virus infection in humans. Gene polymorphisms may affect the viral replication rate or alter the host’s immune response to the virus. In humans, it is unclear which aspect dictates the severity of H5N1 virus disease. To identify the mechanism underlying differential responses to H5N1 virus infection in a genetically diverse population, we assessed the host responses and lung viral loads in 21 inbred mouse strains upon intranasal inoculation with A/Hong Kong/213/03 (H5N1). Resistant mouse strains survived large inocula while susceptible strains succumbed to infection with 1,000- to 10,000-fold-lower doses. Quantitative analysis of the viral load after inoculation with an intermediate dose found significant associations with lethality as early as 2 days postinoculation, earlier than any other disease indicator. The increased viral titers in the highly susceptible strains mediated a hyperinflamed environment, indicated by the distinct expression profiles and increased production of inflammatory mediators on day 3. Supporting the hypothesis that viral load rather than an inappropriate response to the virus was the key severity-determining factor, we performed quantitative real-time PCR measuring the cytokine/viral RNA ratio. No significant differences between susceptible and resistant mouse strains were detected, confirming that it is the host genetic component controlling viral load, and therefore replication dynamics, that is primarily responsible for a host’s susceptibility to a given H5N1 virus.

Early Detection of Susceptibility to Acute Lung Inflammation by Molecular Imaging in Mice Exposed to Cigarette Smoke

Matrix metalloproteinases (MMPs) are extracellular proteolytic enzymes involved in acute lung inflammation in response to cigarette smoke exposure (CSE). We present the in vivo detection of MMP activity using a specific MMP-activatable, near-infrared, polymer-based proteolytic probe in strains of mice with different susceptibility to developing smoking-induced emphysema (susceptible mice, C57BL/6j, and resistant mice, 129S2/SvHsd) to characterize the distinctive profile of CSE-induced acute inflammation. In vivo imaging of pulmonary inflammation expressing MMPs revealed a significantly different median ratio twofold higher in smoker than in nonsmoker susceptible mice (C57BL/6j) and no significant differences between the smoker and the nonsmoker group in resistant mice (129S2/SvHsd). Ex vivo imaging of the lungs of each group of mice confirmed the same in vivo experiment results obtained for both strains of mice. In the biochemical study of lung tissue, the proteolytic signal colocalized with the endogenously expressed MMP protein levels, with MMP-9 levels that are 2.2 times higher than in the nonsmoke-exposed group in C57BL/6j mice and no significant differences in the 129S2/SvHsd mice. The MMP-activatable probe provides a useful reagent for the in vivo and ex vivo detection of MMP-selective proteolytic activity. We are able to distinguish between susceptible and resistant strains of mice in terms of the profile of MMP activity in the early stages of pulmonary disease.

Exceptional Hyperthyroidism and a Role for both Major Histocompatibility Class I and Class II Genes in a Murine Model of Graves' Disease

Autoimmune hyperthyroidism, Graves' disease, can be induced by immunizing susceptible strains of mice with adenovirus encoding the human thyrotropin receptor (TSHR) or its A-subunit. Studies in two small families of recombinant inbred strains showed that susceptibility to developing TSHR antibodies (measured by TSH binding inhibition, TBI) was linked to the MHC region whereas genes on different chromosomes contributed to hyperthyroidism. We have now investigated TSHR antibody production and hyperthyroidism induced by TSHR A-subunit adenovirus immunization of a larger family of strains (26 of the AXB and BXA strains). Analysis of the combined AXB and BXA families provided unexpected insight into several aspects of Graves' disease. First, extreme thyroid hyperplasia and hyperthyroidism in one remarkable strain, BXA13, reflected an inability to generate non-functional TSHR antibodies measured by ELISA. Although neutral TSHR antibodies have been detected in Graves' sera, pathogenic, functional TSHR antibodies in Graves' patients are undetectable by ELISA. Therefore, this strain immunized with A-subunit-adenovirus that generates only functional TSHR antibodies may provide an improved model for studies of induced Graves' disease. Second, our combined analysis of linkage data from this and previous work strengthens the evidence that gene variants in the immunoglobulin heavy chain V region contribute to generating thyroid stimulating antibodies. Third, a broad region that encompasses the MHC region on mouse chomosome 17 is linked to the development of TSHR antibodies (measured by TBI). Most importantly, unlike other strains, TBI linkage in the AXB and BXA families to MHC class I and class II genes provides an explanation for the unresolved class I/class II difference in humans.

To B or not to B: Role of B cells in pathogenesis of arthritis in HLA transgenic mice

Population studies have shown that amongst all the genetic factors linked with autoimmune disease development, MHC class II genes are the most significant. Experimental autoimmune arthritis resembling human rheumatoid arthritis (RA) can be induced in susceptible strains of mice following immunization with type II collagen (CIA). We generated transgenic mice lacking endogenous class II molecules and expressing various HLA genes including RA-associated, HLA-DRB1*0401 and HLA-DQ8, and RA-resistant, DRB1*0402, genes. The HLA molecules in these mice are expressed on the cell surface and can positively select CD4+ T cells expressing various Vβ T cell receptors. Endogenous class II invariant chain is required for proper functioning of the class II transgene. Arthritis development in transgenic mice is CD4+ and B cells dependent. Studies in humanized mice showed that B cells are required as antigen presenting cells in addition to antibody producing cells for the development of CIA. The transgenic mice expressing *0401 and *0401/DQ8 genes developed sex-biased arthritis with predominantly females being affected, similar to that of human RA. Further, the transgenic mice produced autoantibodies like rheumatoid factor and anti-cyclic antibodies. Antigen presentation by B cells leads to a sex-specific immune response in DRB1*0401 mice suggesting a role of B cells and HLA-DR in rendering susceptibility to develop arthritis in females.

Mitotic Arrest in Teratoma Susceptible Fetal Male Germ Cells

Formation of germ cell derived teratomas occurs in mice of the 129/SvJ strain, but not in C57Bl/6 inbred or CD1 outbred mice. Despite this, there have been few comparative studies aimed at determining the similarities and differences between teratoma susceptible and non-susceptible mouse strains. This study examines the entry of fetal germ cells into the male pathway and mitotic arrest in 129T2/SvJ mice. We find that although the entry of fetal germ cells into mitotic arrest is similar between 129T2/SvJ, C57Bl/6 and CD1 mice, there were significant differences in the size and germ cell content of the testis cords in these strains. In 129T2/SvJ mice germ cell mitotic arrest involves upregulation of p27KIP1, p15INK4B, activation of RB, the expression of male germ cell differentiation markers NANOS2, DNMT3L and MILI and repression of the pluripotency network. The germ-line markers DPPA2 and DPPA4 show reciprocal repression and upregulation, respectively, while FGFR3 is substantially enriched in the nucleus of differentiating male germ cells. Further understanding of fetal male germ cell differentiation promises to provide insight into disorders of the testis and germ cell lineage, such as testis tumour formation and infertility.

NADPH-oxidase but not inducible nitric oxide synthase contributes to resistance in a murine Staphylococcus aureus Newman pneumonia model

Staphylococcus aureus is a pathogen that often causes severe nosocomial infections including pneumonia. The present study was designed to examine innate phagocyte mediated immune mechanisms using a previously described murine S. aureus Newman pneumonia model. We found that BALB/c mice represent a more susceptible mouse strain compared to C57BL/6 mice after intranasal S. aureus Newman challenge. Depletion experiments revealed that neutrophils are a crucial determinant for resistance whereas depletion of alveolar macrophages protected mice to some degree from acute pulmonary S. aureus challenge. C57BL/6 mice lacking the subunit gp91phox of the NADPH-oxidase ( gp91phox− /− mice) proved to be highly susceptible against the pathogen. In contrast, C57BL/6 inducible nitric oxidase synthase deficient ( iNOS−/−) mice did not differ in their clinical outcome after infection. Neither bone marrow macrophages from iNOS−/− nor from gp91phox−/− mice were impaired in controlling intracellular persistence of S. aureus. Our data suggest that neutrophil and NADPH-oxidase mediated mechanisms are essential components in protecting the host against pulmonary S. aureus Newman challenge. On contrary, macrophages as well as NO mediated mechanisms do not seem to play a critical role for resistance in this model.

Interleukin 10 deficiency attenuates induction of anti-TSH receptor antibodies and hyperthyroidism in a mouse Graves' model

Experimental Graves'-like hyperthyroidism can be induced in susceptible mouse strains by repetitive immunizations with recombinant adenovirus expressing the human full-length TSH receptor (TSHR) or its A-subunit. Previous studies have shown that splenocytes from immunized mice produce interferon (IFN)-γ and interleukin (IL) 10 in response to antigen stimulation in an in vitro T cell recall assay. Although IFN-γ is now well known to be essential for disease induction, the role(s) played by IL10 are unknown. Therefore, this study was conducted to clarify the significance of endogenous IL10 in the pathogenesis of experimental Graves' disease using IL10 deficient (IL10(-/-)) mice. Our results show that T cell response was augmented when estimated by their antigen-specific secretion of the key cytokine IFN-γ, but B cell function was dampened, that is, anti-TSHR antibody titers were decreased in IL10(-/-) mice, resulting in a lower incidence of Graves' hyperthyroidism (54% in IL10(+/+) vs 25% in IL10(-/-)). Thus, in addition to IFN-γ, these data clarified the role of IL10 for optimizing anti-TSHR antibody induction and eliciting Graves' hyperthyroidism in our Graves' mouse model.

Immunotherapy of murine retrovirus-induced acquired immunodeficiency by CD4 T regulatory cell depletion and PD-1 blockade (154.37)

Abstract LP-BM5 retrovirus induces a disease featuring an acquired immunodeficiency syndrome termed murine AIDS (MAIDS) in susceptible strains of mice, such as C57BL/6 (B6). CD4 T helper effector cells are critical to MAIDS induction and progression of viral pathogenesis. CD8 T cells are not needed for viral pathogenesis, but rather are essential for protection from disease in resistant strains, such as BALB/c. We have discovered an immunodominant cytolytic T lymphocyte (CTL) epitope encoded in a previously un-recognized LP-BM5 retroviral alternative (+1 NT) gag translational open reading frame. CTLs specific for this cryptic gag epitope are the basis of protection from LP-BM5-induced immunodeficiency in BALB/c mice, and the inability of B6 mice to mount an anti-gag CTL response is critical to MAIDS pathogenesis. However, uninfected B6 mice can generate CTL responses to LP-BM5 retrovirus-associated epitope(s) especially prevalent on LP-BM5-induced tumors. Here, we utilized this LP-BM5 retrovirus-induced disease model to test whether modulation of normal immune down-regulatory mechanisms can modulate retroviral pathogenesis. Following in vivo depletion of CD4 T regulatory (Treg) cells, and/or selective interruption of PD-1 negative signaling in the CD8 T-cell compartment, retroviral pathogenesis, but not viral load, was substantially decreased, with the combined treatment of CD4 Treg depletion and PD-1 blockade working in a synergistic fashion to eliminate induction of MAIDS.

Preferential induction of protective T cell responses to Theiler’s virus in resistant (C57BL/6 x SJL)F1 mice (67.14)

Abstract Infection of the CNS with Theiler's murine encephalomyelitis virus (TMEV) induces an immune-mediated demyelinating disease in susceptible mouse strains such as SJL/J (H-2(s)), but not in strains such as C57BL/6 (H-2(b)). In addition, it has been shown that (SJL/J x C57BL/6)F1 mice, which carry both resistant and susceptible MHC haplotypes (H-2(b/s)), are resistant to both viral persistence and TMEV-induced demyelinating disease. In this study, we further analyzed the immune responses underlying resistance of F1 mice. Our study shows that the resistance of F1 mice is associated with a higher level of the initial virus-specific H-2(b)-restricted CD8(+) T cell responses vs. the H-2(s)-restricted CD8(+) T cell responses. In contrast, pathogenic Th17 responses to viral epitopes are lower in F1 mice compared to that in susceptible SJL mice. Dominant effects of resistant genes expressed in antigen-presenting cells of F1 mice on regulating viral replication and inducing protective T cell responses appear to play a crucial role in disease resistance. Although the F1 mice are resistant to disease, the level of viral RNA in the CNS was intermediate between those of SJL/J and C57BL/6 mice, indicating the presence of a threshold of viral expression for pathogenesis.

Genetic susceptibility to chronic trichuris muris induced experimental colitis: translation and relevance to human Crohn's disease

IntroductionUnraveling the genetic architecture of complex traits presents a true challenge. The analysis of experimental models with strict phenotypic documentation and homology to human traits, alongside sensitive scientific methodologies, will...

Memory cells specific for myelin oligodendrocyte glycoprotein govern the transfer of experimental autoimmune encephalomyelitis (101.26)

Abstract Multiple sclerosis (MS) is a chronic, inflammatory disease of the central nervous system thought to be initiated by CD4+ T cells specific for myelin antigens. Experimental autoimmune encephalomyelitis (EAE), a model of MS, is induced in susceptible mouse strains by immunization with myelin antigens such as myelin oligodendrocyte glycoprotein (MOG). MOG35-55-specific T cell receptor transgenic (2D2) mice are susceptible to EAE following immunization with MOG peptide. To better understand the role of T cells in EAE initiation, we explored several approaches for effecting adoptive transfer of EAE using 2D2 T cells. Surprisingly, despite robust proliferation and production of IFN-γ and IL-17 following a variety of culture conditions, EAE was not transferred. Only when 2D2 whole splenocyte preparations contained CD44+ T cells and were Th1-differentiated using MOG peptide and IL-12 did they reliably transfer EAE. Further, we found that CD44hiCD62Llo effector/memory CD4+ T cells are likely responsible for disease transfer due to up-regulation of the adhesion molecule CD44 following differentiation. We also observed a sex dimorphism in 2D2 mice with males transferring more severe EAE, associated with a larger population of effector/memory CD4+ T cells in males compared to females. Given the importance of MOG in MS pathogenesis, mechanistic insights into adoptively transferred EAE by MOG-specific Th1 cells could prove valuable in MS research.

Prevention of autoimmune myocarditis by angiotensin inhibition (164.13)

Abstract Myocarditis, inflammation of the heart, is one of many cardiac pathologic states that can ultimately lead to heart failure. A variety of infectious and noninfectious agents can cause myocarditis, and certain individuals will develop autoimmune responses to various cardiac antigens. To study the autoimmune aspects of the disease, an animal model of experimental autoimmune myocarditis (EAM) has been developed in which immunization of susceptible mouse strains with cardiac myosin induces cardiac inflammation, hypertrophy, and fibrosis through mechanisms dependent on CD4+ T cells. We tested the ability of the antifibrotic, angiotensin-converting enzyme (ACE) inhibitor captopril to inhibit the massive fibrosis that develops during EAM. To our initial surprise, not only did captopril prevent fibrosis, but also it prevented inflammation primarily. Captopril treatment did not appear to directly affect T cell function, since T cells from captopril-treated mice proliferated and secreted proinflammatory cytokines. However, preliminary data indicate that immune cells from spleens of captopril-treated mice show reduced ability to transmigrate across endothelium ex vivo, suggesting that ACE inhibition somehow affects cell trafficking into the myocardium. Current studies are underway to further elucidate the mechanisms by which ACE inhibition mediates these effects with respect to how ACE and ACE products provide proinflammatory signals during EAM.

A convenient method for producing the bleomycin-induced mouse model of scleroderma by weekly injections using a methylcellulose gel

Systemic sclerosis (SSc) is a connective tissue disease characterized by vasculopathy, excessive accumulation of extracellular matrix, and fibrosis of the skin and internal organs. An animal model of SSc, the bleomycin-induced mouse model, has been established and used extensively to investigate the pathogenesis of SSc and to seek novel therapeutic agents. We recently developed thermo-reversible combination gels that can be injected subcutaneously and are made in aqueous solution by forming a complex coacervate with the substance of interest and cationic macromolecules, followed by co-formulation with methylcellulose (MC) as a negative thermosensitive polysaccharide. The objective of this study was to demonstrate whether weekly injections of bleomycin using combination gels loaded with bleomycin can induce the skin fibrosis model of SSc in susceptible mouse strains. A low molecular weight MC (4%) gel with 4.5% ammonium sulfate was made in aqueous solution, and mixed with bleomycin. This was injected subcutaneously into female C3H/He mice at weekly intervals. Control mice were injected with the gel made with phosphate-buffered saline. After 4 weeks, histological examination and gene expression assays of cytokines were performed. Examination in vitro showed that more than 80% of the bleomycin was released from the gel by the 4th day. Histological examination showed that dermal thickness increased in the MC-bleomycin-injected group compared with the control, and semi-quantitative analysis indicated that the extent of inflammation did not differ between the groups. In the MC-bleomycin-injected group, dermal fibrosis assessed with the Masson-Trichrome stain and numbers of alpha-smooth muscle actin-positive fibroblastic cells also increased. The procedure for inducing scleroderma in which bleomycin is injected weekly as an easily-made gel system using methylcellulose, can induce dermal fibrosis in susceptible mice without causing inflammation. We believe this system represents a time- saving and convenient procedure that should facilitate research on SSc.

Distinct roles for nitric oxide in resistant C57BL/6 and susceptible BALB/c mice to control Burkholderia pseudomallei infection

BackgroundBurkholderia pseudomallei is the causative agent of melioidosis, an emerging bacterial infectious disease in tropical and subtropical areas. We recently showed that NADPH oxidase but not nitric oxide (NO) contributes to resistance in innately resistant C57BL/6 mice in a B. pseudomallei respiratory infection model. However, the function of NO for resistance was shown to differ among distinct strains of mice and proved also to be stage dependent in various infection models. The present study therefore aimed to examine the role of NO in a systemic infection model of melioidosis and to test whether the function of NO differs among innately resistant C57BL/6 and susceptible BALB/c mice after B. pseudomallei infection.ResultsC57BL/6 iNOS-/- mice that were intravenously infected with B. pseudomallei survived several weeks, whereas most of the wild type animals succumbed during this period. The bacterial burden in liver and spleen was significantly higher in wild type animals compared to iNOS-/- mice 13 days after challenge. In contrast, BALB/c mice that were treated with amminoguanidine to inhibit NO expression in vivo showed significantly enhanced mortality rates and higher bacterial loads in liver and spleen compared to control animals. The bactericidal function of IFN-γ stimulated C57BL/6 iNOS-/- macrophages were not altered after B. pseudomallei infection, but BALB/c macrophages exhibited reduced killing activity against the pathogen when NO was inhibited.ConclusionOur present data indicate a dual role of NO among resistant and susceptible mouse strains after B. pseudomallei infection. NO mediated mechanisms are an essential component to control the infection in susceptible BALB/c mice. In contrast, NO production in B. pseudomallei infected C57BL/6 mice rather harmed the host likely due to its detrimental effects.

The role of Intelectin-2 in resistance toAscaris suumlung larval burdens in susceptible and resistant mouse strains

The underlying mechanism of predisposition to Ascaris infection is not yet understood but host genetics are thought to play a fundamental role. We investigated the association between the Intelectin-2 gene and resistance in F2 mice derived from mouse strains known to be susceptible and resistant to infection. Ascaris larvae were isolated from murine lungs and the number of copies of the Intelectin-2 gene was determined in F2 mice. Intelectin-2 gene copy number was not significantly linked to larval burden. In a pilot experiment, the response to infection in parental mice of both sexes was observed in order to address the suitability of female F2 mice. No overall significant sex effect was detected. However, a divergence in resistance/susceptibility status was observed between male and, female hybrid offspring. The responsiveness to Ascaris in mice is likely to be controlled by multiple genes and, despite a unique absence from the susceptible C57BL/6j strain, the Intelectin-2 gene does not play a significant role in resistance. The observed intra-strain variation in larval burden requires further investigation but we hypothesize that it stems from social/dominance hierarchies created by the presence of female mice and possibly subsequent hormonal perturbations that modify the intensity of the immune response.

The endocannabinoid anandamide downregulates IL-23 and IL-12 subunits in a viral model of multiple sclerosis: Evidence for a cross-talk between IL-12p70/IL-23 axis and IL-10 in microglial cells

Theiler’s virus (TMEV) infection of the central nervous system (CNS) induces an immune-mediated demyelinating disease in susceptible mouse strains and serves as a relevant infection model for human multiple sclerosis (MS). The endocannabinoid system represents a novel therapeutic target for autoimmune and chronic inflammatory diseases due to its anti-inflammatory properties by regulating cytokine network. IL-12p70 and IL-23 are functionally related heterodimeric cytokines that play a crucial role in the pathogenesis of MS. In the present study we showed that the endocannabinoid anandamide (AEA) downregulated the gene expression of IL-12p70 and IL-23 forming subunits mRNAs in the spinal cord of TMEV-infected mice and ameliorated motor disturbances. This was accompanied by significant decreases on the serological levels of IL-12p70/IL-23 and more interestingly, of IL-17A. In contrast, serum levels of IL-10 resulted elevated. In addition, we studied the signalling pathways involved in the regulation of IL-12p70/IL-23 and IL-10 expression in TMEV-infected microglia and addressed the possible interactions of AEA with these pathways. AEA acted through the ERK1/2 and JNK pathways to downregulate IL-12p70 and IL-23 while upregulating IL-10. These effects were partially mediated by CB2 receptor activation. We also described an autocrine circuit of cross-talk between IL-12p70/IL-23 and IL-10, since endogenously produced IL-10 negatively regulates IL-12p70 and IL-23 cytokines in TMEV-infected microglia. This suggests that by altering the cytokine network, AEA could indirectly modify the type of immune responses within the CNS. Accordingly, pharmacological modulation of endocannabinoids might be a useful tool for treating neuroinflammatory diseases.