Interleukin-1 Receptor Antagonist Deficient Mice Research Articles

Autotaxin inhibition attenuates the aortic valve calcification by suppressing inflammation-driven fibro-calcific remodeling of valvular interstitial cells

BackgroundPatients with fibro-calcific aortic valve disease (FCAVD) have lipid depositions in their aortic valve that engender a proinflammatory impetus toward fibrosis and calcification and ultimately valve leaflet stenosis. Although the lipoprotein(a)-autotaxin (ATX)-lysophosphatidic acid axis has been suggested as a potential therapeutic target to prevent the development of FCAVD, supportive evidence using ATX inhibitors is lacking. We here evaluated the therapeutic potency of an ATX inhibitor to attenuate valvular calcification in the FCAVD animal models.MethodsATX level and activity in healthy participants and patients with FCAVD were analyzed using a bioinformatics approach using the Gene Expression Omnibus datasets, enzyme-linked immunosorbent assay (ELISA), immunohistochemistry, and western blotting. To evaluate the efficacy of ATX inhibitor, interleukin-1 receptor antagonist-deficient (Il1rn-/-) mice and cholesterol-enriched diet-induced rabbits were used as the FCAVD models, and primary human valvular interstitial cells (VICs) from patients with calcification were employed.ResultsThe global gene expression profiles of the aortic valve tissue of patients with severe FCAVD demonstrated that ATX gene expression was significantly upregulated and correlated with lipid retention (r = 0.96) or fibro-calcific remodeling-related genes (r = 0.77) in comparison to age-matched non-FCAVD controls. Orally available ATX inhibitor, BBT-877, markedly ameliorated the osteogenic differentiation and further mineralization of primary human VICs in vitro. Additionally, ATX inhibition significantly attenuated fibrosis-related factors’ production, with a detectable reduction of osteogenesis-related factors, in human VICs. Mechanistically, ATX inhibitor prohibited fibrotic changes in human VICs via both canonical and non-canonical TGF-β signaling, and subsequent induction of CTGF, a key factor in tissue fibrosis. In the in vivo FCAVD model system, ATX inhibitor exposure markedly reduced calcific lesion formation in interleukin-1 receptor antagonist-deficient mice (Il1rn-/-, P = 0.0210). This inhibition ameliorated the rate of change in the aortic valve area (P = 0.0287) and mean pressure gradient (P = 0.0249) in the FCAVD rabbit model. Moreover, transaortic maximal velocity (Vmax) was diminished with ATX inhibitor administration (mean Vmax = 1.082) compared to vehicle control (mean Vmax = 1.508, P = 0.0221). Importantly, ATX inhibitor administration suppressed the effects of a high-cholesterol diet and vitamin D2-driven fibrosis, in association with a reduction in macrophage infiltration and calcific deposition, in the aortic valves of this rabbit model.ConclusionsATX inhibition attenuates the development of FCAVD while protecting against fibrosis and calcification in VICs, suggesting the potential of using ATX inhibitors to treat FCAVD.

Role of interleukin-25 in development of spontaneous arthritis in interleukin-1 receptor antagonist-deficient mice

Interleukin (IL)-25, which is a member of the IL-17 family of cytokines, induces production of such Th2 cytokines as IL-4, IL-5, IL-9 and/or IL-13 by various types of cells, including Th2 cells, Th9 cells and group 2 innate lymphoid cells (ILC2). On the other hand, IL-25 can suppress Th1- and Th17-associated immune responses by enhancing Th2-type immune responses. Supporting this, IL-25 is known to suppress development of experimental autoimmune encephalitis, which is an IL-17-mediated autoimmune disease in mice. However, the role of IL-25 in development of IL-17-mediated arthritis is not fully understood. Therefore, we investigated this using IL-1 receptor antagonist-deficient (IL-1Ra-/-) mice, which spontaneously develop IL-17-dependent arthritis. However, development of spontaneous arthritis (incidence rate, disease severity, proliferation of synovial cells, infiltration of PMNs, and bone erosion in joints) and differentiation of Th17 cells in draining lymph nodes in IL-25-/- IL-1Ra-/- mice were similar to in control IL-25+/+ IL-1Ra-/- mice. These observations indicate that IL-25 does not exert any inhibitory and/or pathogenic effect on development of IL-17-mediated spontaneous arthritis in IL-1Ra-/- mice.

Interleukin-1 receptor antagonist deficient mice provide insights into pathogenesis of human intervertebral disc degeneration

ObjectivesInterleukin 1 (IL-1) is potentially important in the pathogenesis of intervertebral disc (IVD) degeneration; increasing production of matrix degradation enzymes and inhibiting matrix synthesis. Although IL-1 polymorphisms have been linked...

Interleukin-1β–Driven Inflammation Promotes the Development and Invasiveness of Chemical Carcinogen–Induced Tumors

The role of microenvironment interleukin 1 (IL-1) on 3-methylcholanthrene (3-MCA)-induced carcinogenesis was assessed in IL-1-deficient mice, i.e., IL-1beta(-/-), IL-1alpha(-/-), IL-1alpha/beta(-/-) (double knockout), and mice deficient in the naturally occurring inhibitor of IL-1, the IL-1 receptor antagonist (IL-1Ra). Tumors developed in all wild-type (WT) mice, whereas in IL-1beta-deficient mice, tumors developed slower and only in some of the mice. In IL-1Ra-deficient mice, tumor development was the most rapid. Tumor incidence was similar in WT and IL-1alpha-deficient mice. Histologic analyses revealed fibrotic structures forming a capsule surrounding droplets of the carcinogen in olive oil, resembling foreign body-like granulomas, which appeared 10 days after injection of 3-MCA and persisted until the development of local tumors. A sparse leukocyte infiltrate was found at the site of carcinogen injection in IL-1beta-deficient mice, whereas in IL-1Ra-deficient mice, a dense neutrophilic infiltrate was observed. Treatment of IL-1Ra-deficient mice with recombinant IL-1Ra but not with an inhibitor of tumor necrosis factor abrogated the early leukocytic infiltrate. The late leukocyte infiltrate (day 70), which was dominated by macrophages, was also apparent in WT and IL-1alpha-deficient mice, but was nearly absent in IL-1beta-deficient mice. Fibrosarcoma cell lines, established from 3-MCA-induced tumors from IL-1Ra-deficient mice, were more aggressive and metastatic than lines from WT mice; cell lines from IL-1-deficient mice were the least invasive. These observations show the crucial role of microenvironment-derived IL-1beta, rather than IL-1alpha, in chemical carcinogenesis and in determining the invasive potential of malignant cells.

High‐resolution multipinhole single‐photon–emission computed tomography in experimental and human arthritis

To image inflammatory arthritic lesions in experimental arthritis and in patients with arthritis, using a newly developed high-resolution multipinhole single-photon-emission computed tomography (MPH-SPECT) technique. Six interleukin-1 receptor antagonist-deficient mice with arthritis of the front and back paws and 2 control BALB/c mice were imaged with MPH-SPECT and scored macroscopically for arthritis. SPECT imaging was performed with a conventional gamma camera upgraded with a pyramidal lead collimator affixed with MPH apertures. All images were reconstructed, and uptake in the paws was quantified in counts/weight and injected activity. To transfer the imaging technique to humans we examined the clinically dominant hand of 6 individuals (3 with established rheumatoid arthritis [RA], 1 with early RA, 1 with osteoarthritis, and 1 healthy control). MPH-SPECT images were high-resolution 3-dimensional tomographic images, which allowed exact localization and quantifiable observation of increased bone metabolism. MPH-SPECT counts of inflamed joints in mice correlated with macroscopic scoring and histologic joint analysis postmortem. In humans, MPH-SPECT images depicted a detailed visualization of tracer accumulation in bony structures of hand and finger joints, and were also capable of imaging increased bone metabolism that had appeared normal with other imaging modalities, e.g., magnetic resonance imaging. The MPH-SPECT technique represents a new diagnostic tool in the detection of bone pathology in small-animal arthritis research. Compared with macroscopic scoring, this new method provides a more objective and higher-precision quantifiable measurement of bone reaction, allowing visualization of inflammatory processes of the whole skeleton in vivo. These results suggest that MPH-SPECT may be useful as a diagnostic instrument for monitoring experimental arthritis, with further potential for use in human studies of RA.

Immunoregulatory Effects of Allogeneic Mixed Chimerism Induced by T-Cell Depleted, Nonmyeloablative Bone Marrow Transplantation on Chronic Inflammatory Arthritis and Autoimmunity Developed in Interleukin-1 Receptor Antagonist-Deficient Mice.

Objective: To investigate the immunoregulatory effects of allogeneic mixed chimerism induced by T-cell depleted, nonmyeloablative bone marrow transplantation (TCD-NMT) on chronic inflammatory arthritis and autoimmunity developed in interleukin-1 receptor antagonist-deficient (IL-1Ra−/ −) mice.Methods: IL-1Ra−/ − mice (H-2kd) were treated with anti-asialoGM1 Ab, TBI 500 cGy, and TCD-NMT from C57BL/6 mice (H-2kb). Engraftment and chimerism were evaluated on peripheral blood (PB), lymph node, and spleen by multi-color flow cytometry. The severity of arthritis was evaluated by clinical score and histopathology. IgG1 and IgG2a subtype of anti-type II collagen (CII) were measured in PB samples. After T cells were stimulated with CII, ovalbumin, and phytohemagglutinin, T-cell proliferation response and cytokines production (INF-g, TNF-a, IL-10, and IL-17) in culture supernatant were assayed.Results: All the transplanted IL-1Ra mice showed marked improvement of arthritis within 3 weeks after transplantation as well as successful induction of mixed chimerism. Mice in mixed chimerism showed higher level of anti-CII IgG1 and lower level of anti-CII IgG2a and weaker T cell proliferative response than in control groups, such as no-treatment and conditioning only without BM rescue. In mixed chimera, INF-g, TNF-a and IL-17 production from CII-stimulated T cells was significantly suppressed and IL-10 production was significantly increased as compared to the control groups.Conclusion: These observations indicate that the introduction of allogeneic mixed chimerism has a strong immunoregulatroy potential to correct established chronic inflammatory arthritis and autoimmunity originating from dysregulated proinflammatory cytokine network.