Effect of IL-12 encoding plasmid administration on tight-skin mouse

IL-12 sensing in neurons induces neuroprotective CNS tissue adaptation and attenuates neuroinflammation in mice

Interleukin-12 (IL-12) is a potent driver of type 1 immunity. Paradoxically, in autoimmune conditions, including of the CNS, IL-12 reduces inflammation. The underlying mechanism behind these opposing properties and the involved cellular players remain elusive. Here we map IL-12 receptor (IL-12R) expression to NK and T cells as well as neurons and oligodendrocytes. Conditionally ablating the IL-12R across these cell types in adult mice and assessing their susceptibility to experimental autoimmune encephalomyelitis revealed that the neuroprotective role of IL-12 is mediated by neuroectoderm-derived cells, specifically neurons, and not immune cells. In human brain tissue from donors with multiple sclerosis, we observe an IL-12R distribution comparable to mice, suggesting similar mechanisms in mice and humans. Combining flow cytometry, bulk and single-nucleus RNA sequencing, we reveal an IL-12-induced neuroprotective tissue adaption preventing early neurodegeneration and sustaining trophic factor release during neuroinflammation, thereby maintaining CNS integrity in mice.

Fibrillin microfibrils and proteases, key integrators of fibrotic pathways

Supramolecular networks composed of multi-domain ECM proteins represent intricate cellular microenvironments which are required to balance tissue homeostasis and direct remodeling. Structural deficiency in ECM proteins results in imbalances in ECM-cell communication resulting often times in fibrotic reactions. To understand how individual components of the ECM integrate communication with the cell surface by presenting growth factors or providing fine-tuned biomechanical properties is mandatory for gaining a better understanding of disease mechanisms in the quest for new therapeutic approaches. Here we provide an overview about what we can learn from inherited connective tissue disorders caused primarily by mutations in fibrillin-1 and binding partners as well as by altered ECM processing leading to defined structural changes and similar functional knock-in mouse models. We will utilize this knowledge to propose new molecular hypotheses which should be tested in future studies.

A GWAS follow-up study reveals the association of the IL12RB2 gene with systemic sclerosis in Caucasian populations

A single-nucleotide polymorphism (SNP) at the IL12RB2 locus showed a suggestive association signal in a previously published genome-wide association study (GWAS) in systemic sclerosis (SSc). Aiming to reveal the possible implication of the IL12RB2 gene in SSc, we conducted a follow-up study of this locus in different Caucasian cohorts. We analyzed 10 GWAS-genotyped SNPs in the IL12RB2 region (2309 SSc patients and 5161 controls). We then selected three SNPs (rs3790567, rs3790566 and rs924080) based on their significance level in the GWAS, for follow-up in an independent European cohort comprising 3344 SSc and 3848 controls. The most-associated SNP (rs3790567) was further tested in an independent cohort comprising 597 SSc patients and 1139 controls from the USA. After conditional logistic regression analysis of the GWAS data, we selected rs3790567 [P(MH)= 1.92 × 10(-5) odds ratio (OR) = 1.19] as the genetic variant with the firmest independent association observed in the analyzed GWAS peak of association. After the first follow-up phase, only the association of rs3790567 was consistent (P(MH)= 4.84 × 10(-3) OR = 1.12). The second follow-up phase confirmed this finding (P(χ2) = 2.82 × 10(-4) OR = 1.34). After performing overall pooled-analysis of all the cohorts included in the present study, the association found for the rs3790567 SNP in the IL12RB2 gene region reached GWAS-level significant association (P(MH)= 2.82 × 10(-9) OR = 1.17). Our data clearly support the IL12RB2 genetic association with SSc, and suggest a relevant role of the interleukin 12 signaling pathway in SSc pathogenesis.

Pathogenesis and therapeutic approaches for improved topical treatment in localized scleroderma and systemic sclerosis

SSc is a chronic progressive disorder of unknown aetiology characterized by excess synthesis and deposition of collagen and other extracellular matrix components in a variety of tissues and organs. Localized scleroderma (LS) differs from SSc in that with LS only skin and occasionally subcutaneous tissues are involved. Although rarely life threatening, LS can be disfiguring and disabling and, consequently, can adversely affect quality of life. There is no known effective treatment for LS, and various options, including, as examples, corticosteroids and other immunomodulatory agents, ultraviolet radiation and vitamin D analogues, are of unproven efficacy. Clinical trials evaluating combination therapy such as corticosteroids with MTX or UVA1 exposure with psoralens have not been established as consistently effective. New immunomodulators such as tacrolimus and thalidomide are also being evaluated. A better understanding of the molecular and cellular mechanisms of LS has led to evaluation of new treatments that modulate profibrotic cytokines such as TGF-beta and IL-4, regulate assembly and deposition of extracellular matrix components, and restore Th1/Th2 immune balance by administering IL-12 or IFN-gamma. IFN-gamma acts by directly inhibiting collagen synthesis and by restoring immune balance. In this review, we evaluate current and future treatment options for LS and cutaneous involvement in SSc. Recent advances in therapy focus mainly on anti-fibrotic agents. Delivery of these drugs into the skin as the target tissue might be a key factor in developing more effective and safer therapy.

The immunobiology of systemic sclerosis

OBJECTIVES

Systemic sclerosis (SSc) is a chronic connective tissue disease characterized by vascular damage, autoimmunity, and excessive collagen deposition. Despite advances in disease-specific treatment of other rheumatologic diseases, disease-targeted treatment in SSc continues to be elusive. In this review, our goal was to place the contemporary immunobiology of SSc in the perspective of clinical medicine.

METHODS

We performed a PubMed search for the period from 1989 to 2007, using the keyword, "systemic sclerosis," resulting in a total of 9099 publications, including 1252 reviews. Articles were then selected based on their discussion of recent advances in the elusive pathogenesis of SSc. A final total of 259 articles were chosen for the review.

RESULTS

The SSc hallmarks of vascular damage, immunologic activation, and collagen deposition can be traced to 4 major factors: T-cells, fibroblasts, B-cells, and cytokines/chemokines. T-cells are a major component of the infiltrate in skin and lung, exhibiting increased expression of activation markers and showing signs of antigen-driven expansion. Preliminary data indicate that induction of oral tolerance with collagen, a target of SSc T-cell responses, is associated with clinical benefits. Although this suggests that T-cells participate in the pathogenesis of SSc, their precise role and antigen specificity largely remain to be elucidated. Defective numbers and functions of certain T-cell subsets, such as natural killer and gammadelta T-cells, may be involved in the failure to maintain tolerance. Other data suggest that gammadelta T-cells may themselves be effector cells in endothelial cell cytotoxicity. There are several lines of evidence for a pathogenic role of B-cells in SSc, in particular, through the production of autoantibodies. Antibody-dependent cell-mediated cytotoxicity is a primary pathogenic event in an animal model of SSc and is likely to be involved in human SSc. Nonetheless, there is as yet no convincing evidence for the pathogenicity of SSc-specific antibodies. SSc fibroblasts exhibit a specific phenotype characterized not only by excessive collagen production but also by increased responsiveness to and production of cytokines and chemokines. This phenotype is induced by a complex network of cytokines and chemokines but appears to be maintained in the absence of exogenous stimuli via the autocrine production of some of these factors by SSc fibroblasts themselves, particularly transforming growth factor, platelet-derived growth factor, monocyte chemoattractant protein 1, and interleukin-1.

CONCLUSIONS

Significant variations in laboratory data among patients suggest that the pathology reflects a heterogeneous disease. Nonetheless, the possibility of achieving clinical benefits by inducing oral tolerance highlights the importance of characterizing SSc T-cell antigens. It is hoped that the identification of some of the key players in the induction and maintenance of the SSc fibroblast phenotype may yield new disease-targeted treatment regimens for patients with SSc.

BAFF Antagonist Attenuates the Development of Skin Fibrosis in Tight-Skin Mice

The tight-skin (TSK/+) mouse, a genetic model for systemic sclerosis (SSc), develops cutaneous fibrosis and autoimmunity. Although immunological abnormalities have been demonstrated in TSK/+ mice, the roles of B-cell-activating factor belonging to the tumor necrosis factor family (BAFF), a potent B-cell survival factor, have not been investigated. Serum BAFF levels in TSK/+ mice were examined by ELISA. Newborn TSK/+ mice were treated with BAFF antagonist, and then skin fibrosis of 8-week-old mice was assessed. Serum BAFF levels were significantly elevated in TSK/+ mice. Remarkably, BAFF antagonist inhibited the development of skin fibrosis, hyper-gamma-globulinemia, and the autoantibody production in TSK/+ mice. The skin from TSK/+ mice showed upregulated expressions of fibrogenic cytokines, such as IL-6 and IL-10, while BAFF antagonist significantly suppressed them. Reciprocally, BAFF antagonist augmented antifibrogenic cytokines, such as IFN-gamma, in the skin of TSK/+ mice. Furthermore, TSK/+ B cells with BAFF stimulation had a significantly enhanced ability to produce IL-6. The results suggest that BAFF/BAFF receptor system is critical for the development of skin fibrosis in TSK/+ mice and could be a potent therapeutical target.

Intercellular Adhesion Molecule-1 Deficiency Attenuates the Development of Skin Fibrosis in Tight-Skin Mice

The tight-skin (TSK/+) mouse, a genetic model for systemic sclerosis, develops cutaneous fibrosis. Although a fibrillin 1 gene mutation and immunological abnormalities have been demonstrated, the roles of adhesion molecules have not been investigated. To directly assess roles of adhesion molecules in skin fibrosis, TSK/+ mice lacking L-selectin and/or ICAM-1 were generated. The deficiency of ICAM-1, but not L-selectin, significantly suppressed ( approximately 48%) the development of skin sclerosis in TSK/+ mice. Similarly, ICAM-1 antisense oligonucleotides inhibited skin fibrosis in TSK/+ mice. Although T cell infiltration was modest into the skin of TSK/+ mice, ICAM-1 deficiency down-regulated this migration, which is consistent with the established roles of endothelial ICAM-1 in leukocyte infiltration. In addition, altered phenotype or function of skin fibroblasts was remarkable and dependent on ICAM-1 expression in TSK/+ mice. ICAM-1 expression was augmented on TSK/+ dermal fibroblasts stimulated with IL-4. Although growth or collagen synthesis of TSK/+ fibroblasts cultured with IL-4 was up-regulated, it was suppressed by the loss or blocking of ICAM-1. Collagen expression was dependent on the strain of fibroblasts, but not on the strain of cocultured T cells. Thus, our findings indicate that ICAM-1 expression contributes to the development of skin fibrosis in TSK/+ mice, especially via ICAM-1 expressed on skin fibroblasts.

Physiopathologie de la sclérodermie systémique: état des lieux sur une affection aux multiples facettes

Systemic sclerosis is a rare disease characterized by vascular hyperreactivity and collagen deposition. Endothelial cell, fibroblast and lymphocyte abnormalities have been reported in systemic sclerosis. Fibroblast dysfunction is characterized by uncontrolled activation of the transforming growth factor-beta (TGF-beta) pathway and excess synthesis of both connective tissue growth factor (CTGF) and free radicals. These promote the accumulation of extracellular matrix. Endothelial cells produce excess quantities of endothelin 1 and inducible NO synthase. They also undergo early apoptosis. Oxidative stress appears to play a major role in disease progression. Increased levels of interleukin 4, a profibrotic cytokine, have been detected in plasma and skin of systemic sclerosis patients. Autoantibodies are detectable in the serum of almost all systemic sclerosis patients. Some are directed against well-identified ubiquitous nuclear proteins and have no demonstrated pathogenic role. Other autoantibodies bind to endothelial cells or fibroblasts and may have a pathogenic role.

B-lymphocyte depletion reduces skin fibrosis and autoimmunity in the tight-skin mouse model for systemic sclerosis

Systemic sclerosis (scleroderma) is an autoimmune disease characterized by excessive extracellular matrix deposition in the skin. A direct role for B lymphocytes in disease development or progression has remained controversial, although autoantibody production is a feature of this disease. To address this issue, skin sclerosis and autoimmunity were assessed in tight-skin mice, a genetic model of human systemic sclerosis, after circulating and tissue B-cell depletion using an anti-mouse CD20 monoclonal antibody before (day 3 after birth) and after disease development (day 56). CD20 monoclonal antibody treatment (10 to 20 microg) depleted the majority (85 to 99%) of circulating and tissue B cells in newborn and adult tight-skin mice by days 56 and 112, respectively. B-cell depletion in newborn tight-skin mice significantly suppressed (approximately 43%) the development of skin fibrosis, autoantibody production, and hypergammaglobulinemia. B-cell depletion also restored a more normal balance between Th1 and Th2 cytokine mRNA expression in the skin. By contrast, B-cell depletion did not affect skin fibrosis, hypergammaglobulinemia, and autoantibody levels in adult mice with established disease. Thereby, B-cell depletion during disease onset suppressed skin fibrosis, indicating that B cells contribute to the initiation of systemic sclerosis pathogenesis in tight-skin mice but are not required for disease maintenance.

Pathogenesis of systemic sclerosis: altered B cell function is the key linking systemic autoimmunity and tissue fibrosis

Systemic sclerosis (SSc) is characterized by autoimmunity and tissue fibrosis. There is a close association between specific autoantibodies and clinical features in patients with SSc. A number of studies have demonstrated that various cytokines, such as transforming growth factor-beta, modulate the synthesis of extracellular matrix by fibroblasts. However, it is not clear as to how autoimmunity and tissue fibrosis interact with each other. Recent studies have revealed that B cells play a critical role in various systemic autoimmune disorders. CD19 is a central regulator of B cell signaling threshold, and B cells from SSc patients exhibit an increased expression of CD19 that induces SSc-specific autoantibody production in transgenic mice. Furthermore, SSc patients have intrinsic B cell abnormalities characterized by decreased but activated memory B cells, which is possibly due to CD19 overexpression. Similarly, B cells from a tight-skin mouse, a model of SSc, show augmented CD19 signaling and chronic B cell activation. Remarkably, CD19 loss results in inhibition of chronic B cell hyper-reactivity and elimination of autoantibody production, which is associated with improvement in skin fibrosis and a parallel decrease in IL-6 production by B cells. Therefore, augmented cytokine production by B cells is a potential candidate for the induction of skin sclerosis. Alternatively, B cells may influence tissue fibrosis by regulating T cell activation and cytokine production through their antigen-presenting and co-stimulatory abilities. Thus, altered B cell function may result in tissue fibrosis, as well as autoimmunity, in SSc.

CpG oligodeoxynucleotides prevent the development of scleroderma-like syndrome in tight-skin mice by stimulating a Th1 immune response

Tight-skin (Tsk/+) mice develop a disease similar to human scleroderma, characterized by the spontaneous appearance of cutaneous hyperplasia, anti-nuclear antibodies, and emphysema. T helper (Th) 2 cells secreting interleukin (IL)-4 are known to play a critical role in the etiopathogenesis of this disease. Th2-mediated responses can be blocked by treatment with synthetic oligodeoxynucleotides (ODN) containing immunomodulatory CpG motifs. Thus, we examined whether CpG ODN might be of therapeutic benefit in Tsk/+ mice. Administering CpG ODN to Tsk/+ mice every 3 wk starting at 1 wk of age abrogated skin fibrosis. This reduction in skin thickness persisted even after the cessation of therapy, and was accompanied by increased serum levels of IL-12 and an increased ratio of T cells available to secrete interferon-gamma rather than IL-4. CpG ODN therapy also reduced autoantibody production, but did not inhibit the incidence of lung emphysema. Delaying the initiation of CpG ODN treatment until 6 wk of age failed to prevent skin disease. These results indicate that by preferentially promoting the development of a Th1-biased immune milieu in young Tsk/+ mice, CpG ODN can ameliorate Th2-driven scleroderma-like syndrome.

Therapeutic effect of CpG-enriched plasmid administration on the tight-skin mouse model of scleroderma

Immunostimulatory CpG motifs can preferentially induce Th1 immune responses and have been applied to treat Th2-dominant disease. In this study, we investigated whether a plasmid with the addition of 20 copies of an immunostimulatory CpG motif (pB-CpG20) might prevent the development of scleroderma-like syndrome in tight-skin (Tsk/+) mice. Administration of pB-CpG20 to Tsk/+mice every 3 weeks starting at the age of 1 week reduced skin thickness and collagen content compared to that of pB or saline. The reduction was long lasting even after halting the treatment. Furthermore, this treatment partially reduced the production of anti-nuclear antibodies although it did not decrease the incidence of lung emphysema. pB-CpG20 increased the number of spleen cells secreting IFN-gamma and reduced that of the cells secreting IL-4 in vivo and in vitro compared to saline. These results suggest that repeated administration of a CpG-enriched plasmid can ameliorate scleroderma-like syndrome by biasing Th1 immunity in young Tsk/+mice.

The use of streptolysin o for the treatment of scars, adhesions and fibrosis: initial investigations using murine models of scleroderma

Diseases and conditions involving the deposition of excessive amounts of collagen include scleroderma, fibrosis, and scar and surgical adhesion formation. Diseases such as scleroderma may result from acute and chronic inflammation, disturbances in the normal parenchymal area, and activation of fibroblasts. ML-05, a modified form of the hemolytic and cytotoxic bacterial toxin, streptolysin O, is being developed for the treatment of such collagen-related disorders. At sublytic concentrations in vitro, ML-05 was shown to activate CD44 expression. This may modulate production of collagen, hyaluronate, and their associated enzymes to allow a restoration of normal extracellular matrices within tissues. More importantly, ML-05 appeared to decrease skin collagen levels in two in vivo models of collagen disorders, the tight skin mouse (Tsk) model of scleroderma, and the bleomycin-induced mouse skin fibrosis model. In the Tsk model, levels of hydroxyproline (a measure of total collagen) decreased by 25% in the Tsk+ML-05 treatment group relative to the Tsk+saline control group over a 3-month period. In the bleomycin-induced skin fibrosis study, hydroxyproline levels decreased from 15-22% over a 6-week period in a bleomycin-induced ML-05 treatment group (relative to levels in a bleomycin-induced, untreated control group). Hydroxyproline levels in samples from this treatment group were only slightly greater than levels in an uninduced control group at 8 weeks. Thus, ML-05 treatment appeared to reduce collagen levels in two separate mouse skin fibrosis models, one genetically based and the other chemically induced.

Myocardial injection of CA promoter-based plasmid mediates efficient transgene expression in rat heart

BACKGROUND

Although naked plasmid injection is the safest and most convenient method for gene delivery, a major limitation of this approach is currently poor transgene expression. The CA promoter (chicken beta-actin promoter with cytomegalovirus, CMV, enhancer) is one of the strongest transcriptional control modules found; however, it is uncertain whether a CA promoter-based vector is efficient enough for naked gene therapy in a cardiovascular context.

METHODS

The beta-galactosidase (LacZ) expression provided by CA promoter plasmid (pCAZ2) injection into the skeletal muscle or the heart of Lewis rats was compared with CMV promoter plasmid or adenoviral vector (AxCAZ3). The effect of Simian virus 40 of the replication origin (SV40ori) deletion from pCAZ2 on transgene expression was also evaluated.

RESULTS

pCAZ2 showed the highest LacZ expression in both skeletal muscle and heart in comparison with the CMV promoter-based vector 5 days after naked plasmid injection. LacZ expression in the heart obtained using 20 micro g of pCAZ2 was almost equivalent to that shown with AxCAZ3 at 6.0 x 10(9) optical particle units. The time course of transgene expression driven by CMV and CA promoters in the heart were similar, with the CA promoter providing significantly higher gene expression than the CMV promoter across all time points examined. SV40ori deletion from pCAZ2 did not affect transgene expression in either skeletal muscle or heart.

CONCLUSIONS

Transgene expression mediated by naked CA promoter-based plasmid injection was shown to be quite efficient in the heart. We propose that the CA promoter vector is suitable for myocardial gene therapy.

Complex cytokine regulation of tissue fibrosis

Tissue fibrosis, a serious and even deadly complication of chronic inflammation and environmental exposures, is regulated by a host of factors including interactions with the extracellular matrix, surface of inflammatory cells, hormones, and an extremely complex and redundant network of profibrotic cytokines. The nature of mechanisms by which cytokines regulate fibrosis is dual - indirect, through attraction of inflammatory cells, and direct, through binding to specific receptors on fibroblasts and stimulating proliferation, collagen production and secretion of autocrine factors. This review focuses on systematizing the direct effects of cytokines on fibroblasts. Understanding of the complexity of the cytokine-driven mechanisms of fibrosis is important for identification of potential molecular targets for future pharmacological interventions in prevention and treatment of tissue fibrosis.

Murine animal models of systemic sclerosis

Animal models of systemic connective tissue diseases have provided valuable insights into the causative mechanisms and the pathogenesis of these diseases, and have provided the means to test potentially useful therapeutic interventions. Although numerous animal models for systemic sclerosis (SSc) have been described, the most extensively studied are murine. One advantage of murine animal models is the large body of genetic information available for the mouse that is not available for other species. No animal model described to date reproduces precisely all manifestations of SSc. However, all animal models display tissue fibrotic changes similar to those present in SSc. The prudent interpretation of the results obtained from the study of animal models has provided substantial and valuable information about the pathogenesis of the human disease.

Disrupting the IL-4 gene rescues mice homozygous for the tight-skin mutation from embryonic death and diminishes TGF-beta production by fibroblasts

The TSK/TSK mutation is embryonic lethal; embryos have been reported to die at 7-8 days of gestational age. Crossing TSK/+, IL-4+/- mice revealed that disrupting one or both IL-4 alleles allowed survival of 29 and 47%, respectively, of TSK/TSK mice. These mice failed to develop cutaneous hyperplasia but did exhibit the emphysema that is found in TSK/+ mice. We showed that IL-4 stimulation of fibroblasts increased the level of transforming growth factor-beta (TGF-beta) mRNA and that lungs of TSK/+, IL-4-/- mice had substantially less TGF-beta mRNA than lungs of TSK/+, IL-4+/+ mice. Thus IL-4 seems to regulate the expression of TGF-beta in fibroblasts, providing an explanation for the absence of cutaneous hyperplasia in TSK/+, IL-4Ralpha-/- and TSK/+, TGF-beta+/- mice.