Upregulated protein arginine methyltransferase 1 by IL-4 increases eotaxin-1 expression in airway epithelial cells and participates in antigen-induced pulmonary inflammation in rats.

Protein arginine methyltransferases (PRMTs), catalyzing methylation of both histones and other cellular proteins, have emerged as key regulators of various cellular processes. This study aimed to identify key PRMTs involved in Ag-induced pulmonary inflammation (AIPI), a rat model for asthma, and to explore the role of PRMT1 in the IL-4-induced eosinophil infiltration process. E3 rats were i.p. sensitized with OVA/alum and intranasally challenged with OVA to induce AIPI. The expressions of PRMT1-6, eotaxin-1, and CCR3 in lungs were screened by real-time quantitative PCR. Arginine methyltransferase inhibitor 1 (AMI-1, a pan-PRMT inhibitor) and small interfering RNA-PRMT1 were used to interrupt the function of PRMT1 in A549 cells. In addition, AMI-1 was administrated intranasally to AIPI rats to observe the effects on inflammatory parameters. The results showed that PRMT1 expression was mainly expressed in bronchus and alveolus epithelium and significantly upregulated in lungs from AIPI rats. The inhibition of PRMTs by AMI-1 and the knockdown of PRMT1 expression were able to downregulate the expressions of eotaxin-1 and CCR3 with the IL-4 stimulation in the epithelial cells. Furthermore, AMI-1 administration to AIPI rats can also ameliorate pulmonary inflammation, reduce IL-4 production and humoral immune response, and abrogate eosinophil infiltration into the lungs. In summary, PRMT1 expression is upregulated in AIPI rat lungs and can be stimulated by IL-4. Intervention of PRMT1 activity can abrogate IL-4-dependent eotaxin-1 production to influence the pulmonary inflammation with eosinophil infiltration. The findings may provide experimental evidence that PRMT1 plays an important role in asthma pathogenesis.

Inflammatory role of ASC in antigen-induced arthritis is independent of caspase-1, NALP-3, and IPAF.

Because IL-1beta plays an important role in inflammation in human and murine arthritis, we investigated the contribution of the inflammasome components ASC, NALP-3, IPAF, and caspase-1 to inflammatory arthritis. We first studied the phenotype of ASC-deficient and wild-type mice during Ag-induced arthritis (AIA). ASC(-/-) mice showed reduced severity of AIA, decreased levels of synovial IL-1beta, and diminished serum amyloid A levels. In contrast, mice deficient in NALP-3, IPAF, or caspase-1 did not show any alteration of joint inflammation, thus indicating that ASC associated effects on AIA are independent of the classical NALP-3 or IPAF inflammasomes. Because ASC is a ubiquitous cytoplasmic protein that has been implicated in multiple cellular processes, we explored other pathways through which ASC may modulate inflammation. Ag-specific proliferation of lymph node and spleen cells from ASC-deficient mice was significantly decreased in vitro, as was the production of IFN-gamma, whereas IL-10 production was enhanced. TCR ligation by anti-CD3 Abs in the presence or absence of anti-CD28 Abs induced a reduction in T cell proliferation in ASC(-/-) T cells compared with wild-type ones. In vivo lymph node cell proliferation was also significantly decreased in ASC(-/-) mice, but no effects on apoptosis were observed either in vitro or in vivo in these mice. In conclusion, these results strongly suggest that ASC modulates joint inflammation in AIA through its effects on cell-mediated immune responses but not via its implication in inflammasome formation.

Extract of Toxicodendron quercifolium caused genotoxicity and antigenotoxicity in bone marrow cells of CD1 mice.

As has been shown in numerous studies, naturally occurring compounds can have protective effects towards mutagens and carcinogens. In the present study, the genotoxic/antigenotoxic effect of Toxicodendron quercifolium (poison ivy) extract, which has been identified as antigenotoxic in human HepG2 cells in former studies, was examined in the in vivo micronucleus assay using polychromatic erythrocytes (PCE) of bone marrow of CD1-mice. For this, D0 (1:10), D0 (1:25), D0 (1:50), D1 (1:50), D2 (1:50), and D4 (1:50) dilutions of ethanolic plant extract prepared on the basis of the "Hömoopathisches Arzneimittelbuch (HAB 2000)" were administered orally to CD1 mice over a period of two days. A significant increase (p < 0.05) in micronucleus frequencies was found after administration of D0 (1:10), the highest tolerated dose. Additionally, antigenotoxic effects of T. quercifolium towards benzo(a)pyrene-induced micronucleus formation were studied. For that, four dilutions of the plant extract [D0, D2, D4, D6, each 1:50] were administered orally to CD1 mice for five days prior to the administration of benzo(a)pyrene (250 mg/kg b.w.) for another two days. It was found that the administration of the dilutions D0 (1:50) and D2 (1:50) of T. quercifolium extract significantly inhibited benzo(a)pyrene-induced micronucleus formation (p < 0.0001). The results of this study indicated that T. quercifolium extract has the character of a so-called "Janus"-genotoxin: High doses led to a weak but significant increase of micronucleus frequencies whereas low doses showed chemopreventive effects towards benzo(a)pyrene-induced DNA damage. The constituents of T. quercifolium responsible for the genotoxic and antigenotoxic effects may be flavonoids, which are known to have prooxidative and scavenging effects and identified by HPLC-MS/MS.

Effect of orally administered Hochu-ekki-to, a Japanese herbal medicine, on contact hypersensitivity caused by repeated application of antigen.

The effects of oral administration of Hochu-ekki-to (HET; bu-zhong-yi-qi-tang in Chinese), a traditional Japanese and Chinese herbal medicine, on chronic contact hypersensitivity were investigated. HET suppressed ear swelling due to chronic contact hypersensitivity caused by repeated application of 2,4,6-trinitro-1-chlorobenzene (TNCB). HET significantly suppressed not only increases in hapten-specific immunoglobulin E (IgE) and IgG1 titer due to repeated application of TNCB, but also total IgE and IgG1 concentration in the serum. Interleukin 4 (IL-4) level in inflamed ear tissue was significantly increased by repeated application of TNCB, and this increase in IL-4 level in the ear was significantly suppressed by oral administration of HET. Interferon gamma (IFN-gamma), IL-2, IL-5, IL-10 and IL-12 levels are not changed as much as IL4 by TNCB and HET did not alter these cytokines as much as IL-4. These results suggest that oral administration of HET suppresses chronic contact hypersensitivity, and it can be assumed that the suppression of serum Ig E and Ig G1 and IL-4 in inflamed ear.

Effects of Poncirus trifoliata on type I hypersensitivity reaction.

A study was carried out to examine the effect of an aqueous extract from immature fruit of Poncirus trifoliata L. (Rutaceae) (PTIFE) on the type I hypersensitivity reaction. Forty-eight hour PCA (passive cutaneous anaphylaxis) in rats was significantly inhibited by the oral administration of PTIFE (200 mg/kg). It also inhibited histamine release from rat peritoneal mast cells (RPMC) induced by mouse anti-dinitrophenyl (DNP)-IgE and dinitrophenyl-human serum albumin (DNP-HSA). These results suggest that PTIFE has anti-allergic action against the type I hypersensitivity reaction.

Experimental autoimmune uveoretinitis and pinealitis induced by interphotoreceptor retinoid-binding protein and S-antigen: induction of intraretinal and subretinal neovascularization.

Experimental autoimmune uveoretinitis (EAU) and pinealitis were induced in Lewis rats following hind foot pad injection of interphotoreceptor retinoid-binding protein (IRBP) or S-antigen. A comparison is made in this study of the in vivo and histological changes in uveoretinitis and pinealitis induced by administering similar doses of highly-purified IRBP and S-antigen emulsified in complete Freund's adjuvant (CFA). The time of onset of ocular inflammation after inoculation was slightly later in S-antigen (14-18 days) as compared with IRBP-inoculated animals (10-14 days), while the severity of the inflammation was lower in the latter group. The distribution of inflammation in the anterior segment was similar in both the S-antigen and IRBP sensitized animals but there was major variation in the location of the posterior segment disease. Vasculitis was a predominant feature of IRBP induced disease while chorioretinitis and photoreceptor destruction was more prominent in the S-antigen sensitized animals. A striking feature of this study is that both antigens induced intraretinal and subretinal neovascularization, an observation which has not been reported previously. Inflammation was induced in all pineal glands and as with EAU the severity was closely related to the type of antigen inoculated.