Unexpected T cell regulatory activity of anti-histone H1 autoantibody: its mode of action in regulatory T cell-dependent and -independent manners.

Induction of anti-nuclear antibodies against DNA or histones is a hallmark of autoimmune disorders, but their actual contribution to disease predisposition remains to be clarified. We have previously reported that autoantibodies against histone H1 work as a critical graft survival factor in a rat model of tolerogeneic liver transplantation. Here we show that an immunosuppressive anti-histone H1 monoclonal antibody (anti-H1 mAb) acts directly on T cells to inhibit their activation in response to T cell receptor (TCR) ligation. Intriguingly, the T cell activation inhibitory activity of anti-H1 mAb under suboptimal dosages required regulatory T (Treg) cells, while high dose stimulation with anti-H1 mAb triggered a Treg cell-independent, direct negative regulation of T cell activation upon TCR cross-linking. In the Treg cell-dependent mode of immunosuppressive action, anti-H1 mAb did not induce the expansion of CD4(+-)Foxp3(+) Treg cells, but rather potentiated their regulatory capacity. These results reveal a previously unappreciated T cell regulatory role of anti-H1 autoantibody, whose overproduction is generally thought to be pathogenic in the autoimmune settings.

A novel peptide mimotope identified as a potential immunosuppressive vaccine for organ transplantation.

We reported that anti-histone H1 autoantibody is one of the main immunosuppressive factors in serum that is induced after orthotopic liver transplantation in a rat tolerogenic model. We generated a novel anti-histone H1 IgM mAb produced by hybridoma 16G9 (16G9 mAb) that shows MLR-inhibitory activity. Identification of a functional epitope responsible for the immunosuppressive activity of 16G9 mAb may lead to the establishment of a novel therapeutic strategy. We used a combinatorial phage display peptide library to screen for peptides that bind to 16G9 mAb. Consequently, two peptides that bind to 16G9 mAb, SSV and LPQ, were selected from the library. The binding of 16G9 mAb to histone H1 was inhibited by SSV. SSV was recognized by rat tolerogenic post-orthotopic liver transplantation serum and the binding to SSV was inhibited by histone H1. Mice were immunized with keyhole limpet hemocyanin-conjugated SSV and LPQ. Abs induced by SSV immunization inhibited Con A-stimulated splenocyte proliferation, and the inhibition was neutralized by preincubation with SSV. Splenocytes stimulated by anti-CD3 Ab were inhibited by SSV-induced Abs using CFSE labeling. SSV immunization in rats before heterotopic heart transplantation resulted in significant prolonged allograft survival. These findings suggested that SSV is a functional histone H1-binding epitope for 16G9 mAb. SSV is capable of determining serum immunoreactivity against histone H1 as an index marker for tolerance. The inhibitory activity of SSV-induced Abs on blast cell proliferation and the prolonged graft survival that results from SSV immunization imply a potential for the development of an immunosuppressive vaccine.

Immunological aspects and therapeutic significance of an autoantibody against histone H1 in a rat model of concanavalin A-induced hepatitis.

We previously demonstrated the immunosuppressive activity of anti-histone H1 autoantibody induced in experimental and clinical liver allograft tolerance. This study aimed to explore the immunological aspects of anti-histone H1 autoantibody in liver injury induced by concanavalin A (Con A). To establish a Con A-hepatitis model, 20 mg/kg Con A was intravenously injected into rats, after which liver function and histopathological analyses were performed. In this model, anti-histone H1 autoantibody was transiently induced in the sera during the natural recovery stage, 3-7 days after Con A injection. To evaluate the therapeutic significance of anti-histone H1 autoantibody, a polyclonal antibody against histone H1 was intraperitoneally injected immediately after Con A injection. We found that injection of anti-histone H1 antibody could reduce Con A-induced liver damage. Further mechanical analyses revealed that anti-histone H1 antibody altered the intracellular activation of mitogen-activated protein kinase, nuclear factor-kappaB and calcineurin via T-cell receptor signalling, suggesting that anti-histone H1 antibody may protect the liver from Con A-induced injury by inhibiting activation of effector T cells. These findings suggest that anti-histone H1 autoantibody may be a natural immune regulatory factor that protects inflamed livers suffering from autoimmune hepatitis and may lead to T-cell unresponsiveness through the selective regulation of mitogen-activated protein kinase/nuclear factor-kappaB and calcineurin signalling.

Molecular cloning and immunochemical characterization of a novel major Japanese cedar pollen allergen belonging to the aspartic protease family.

BACKGROUND: Japanese cedar (Cryptomeria japonica) pollen is a major cause of seasonal pollinosis in Japan. Protease activity in the pollen grains may trigger pro-allergic responses but no such proteases have yet been identified as pollen allergens. OBJECTIVES: We report the molecular cloning and immunochemical characterization of a novel C. japonica pollen allergen belonging to the aspartic protease family. METHODS: We focused on the C. japonica pollen allergen spot No. 63 (CPA63, 47.5% IgE binding frequency) on our 2-dimensional IgE immunoblot map. The internal amino acid sequences were determined using time-of-flight mass spectrometry. Full-length cpa63 cDNA was cloned by rapid amplification of cDNA ends (RACE)-PCR. Recombinant CPA63 (r-CPA63) was expressed using the baculovirus-insect cell culture system and its IgE binding capacity was analyzed by enzyme-linked immunosorbent assay (ELISA). The proteolytic activity of r-CPA63 was also assessed using a putative mature enzyme produced upon autolysis. RESULTS: cpa63 cDNA encoded a 472 amino acid polypeptide showing about 40% sequence identity to members of the plant atypical aspartic protease family. ELISA showed that r-CPA63 was recognized by IgE antibodies in the serum of 58% (18/31) of Japanese cedar pollinosis patients. We also demonstrated an aspartic protease-like enzyme activity of the putative mature r-CPA63. CONCLUSIONS: We have identified the first plant aspartic protease allergen from Japanese cedar pollen. The availability of the CPA63 sequence and its recombinant allergen production system are useful not only for pharmaceutical applications but also for further examination of the role of protease activity in the pathogenesis of cedar pollinosis.

Skin permeability of tulobuterol in two transdermal formulations and their followability.

Various generic transdermal formulations of tulobuterol containing rubber and acrylate base polymers are commercially available in Japan. However, none of the formulations have been compared directly with respect to the skin permeability of tulobuterol and to their follow ability. Tulobuterol Tape Sawai of rubber base and Tulobuterol Tape NP of acrylate base were used to conduct the in vitro 24-hour skin permeability test of tulobuterol at receiver solution temperatures of 32°C, 37°C, and 40°C. Furthermore, the followability of these tapes were examined by measuring the depth of the pores that were formed in their adhesive layer. Consequently, the maximum flux of tulobuterol was greater for Tulobuterol Tape NP. Arrhenius plot analysis revealed that Tulobuterol Tape Sawai was more sensitive to skin surface temperature compared with Tulobuterol Tape NP. Skin abrasion had a greater effect on the skin permeability of tulobuterol in Tulobuterol Tape Sawai than in Tulobuterol Tape NP. Followability was greater for Tulobuterol Tape NP than for Tulobuterol Tape Sawai. These results suggest that a transdermal formulation of acrylate base is preferable to that with a rubber base when skin surface temperature varies or when the skin is abraded. In clinical settings, therefore, a formulation of acrylate base is preferable to a formulation of rubber base when skin surface temperature varies or when the skin is abraded. The formulation needs to be applied to the skin of less asperity for the achievement of better transdermal absorption of tulobuterol.

Impact of Histone H1 on the Progression of Allergic Rhinitis and Its Suppression by Neutralizing Antibody in Mice.

Nuclear antigens are known to trigger off innate and adaptive immune responses. Recent studies have found that the complex of nucleic acids and core histones that are derived from damaged cells may regulate allergic responses. However, no fundamental study has been performed concerning the role of linker histone H1 in mast cell-mediated type I hyperreactivity. In this study, we explored the impact of histone H1 on mast cell-mediated allergic responses both in vitro and in vivo. In the course of a bona-fide experimental allergen sensitization model upon co-injection with alum adjuvant, ovalbumin (OVA), but not PBS, induced elevated levels of circulating histone H1. Intranasal challenge with histone H1 to OVA/alum- (but not PBS/alum)-sensitized mice induced significantly severer symptoms of allergic rhinitis than those in mice sensitized and challenged with OVA. A monoclonal antibody against histone H1 not only suppressed mast cell degranulation, but also ameliorated OVA-induced nasal hyperreactivity and IgE-mediated passive cutaneous anaphylaxis. Our present data suggest that nuclear histone H1 represents an alarmin-like endogenous mediator acting on mast cells, and that its blockage has a therapeutic potential for mast cell-mediated type I hyperreactivity.

A novel anti-histone H1 monoclonal antibody, SSV monoclonal antibody, improves lung injury and survival in a mouse model of lipopolysaccharide-induced sepsis-like syndrome.

BACKGROUND: Histones play important roles in both host defenses and inflammation related to microbial infection. A peptide mimotope (SSV) was identified from a novel histone H1 monoclonal antibody (16G9 mAb) that was shown to inhibit the mixed lymphocyte reaction. In the present study, an anti-SSV producing hybridoma was established. We investigated the effects of SSV mAb in a mouse acute inflammation model induced by intraperitoneal injection of lipopolysaccharide (LPS). METHODS: SSV mAb was generated and characterized. Mice were treated with SSV mAb or a control IgG antibody prior to LPS injection. Evaluation of survival rate and lung tissue on histological score was performed. The levels of inflammatory cytokines and histones H1, H3, and H4 in plasma and lung tissue were measured by ELISA. RESULTS: Competitive ELISA revealed that SSV mAb binds to histone H1. SSV mAb improved lung injury and prolonged the survival of LPS-injected mice. Increased levels of histones H1, H3, and H4 and inflammatory cytokines (TNF-α, IL-1ß, and IL-6) in plasma and lung tissue after LPS injection were ameliorated by SSV mAb. CONCLUSION: SSV mAb is shown to have anti-inflammatory activity and organ-protective effects, highlighting the importance of controlling histone H1 as well as H3 and H4 levels during inflammation.

Molecular cloning and immunochemical characterization of a new Japanese cedar pollen allergen homologous to plant subtilisin-like serine protease.

Protease activities in allergen sources are thought to be involved in triggering allergic inflammation through the disruption of epithelial barrier or the induction of proinflammatory cytokines. Protease allergens may also work as type 2 helper T cell (TH2) adjuvants through the cleavage of cell surface receptors. Here, we report molecular cloning and immunochemical characterization of a new Japanese cedar (Cryptomeria japonica) pollen allergen (CPA9) homologous to serine protease, which is initially found as a high IgE-binding spot on our two-dimensional (2-D) IgE immunoblotting map. The cpa9 cDNA encoded a 757 amino acid polypeptide showing a significant sequence identity with plant subtilisin-like serine protease family members including melon major allergen Cuc m 1. We found that native CPA9 purified from C. japonica pollen showed a high IgE-binding frequency and IgE cross-reactivity with melon extract.

Development of a two-step chromatography procedure that allows the purification of a high-purity anti-histone H1 monoclonal immunoglobulin M antibody with immunosuppressant activity.

In organ transplantation, the development of a novel immunosuppressant free of the need for permanent administration and any serious side effects has eagerly been awaited. We have previously reported that an anti-histone H1 polyclonal antibody has immunosuppressant activity. Here we prepared an anti-histone H1 monoclonal antibody as an analytical tool to elucidate its mechanism of immunosuppression. The isotype of this monoclonal antibody was immunoglobulin M. A monoclonal antibody prepared for administration to organ transplantation model animals should not contain any allogenic proteins and should have high purity. Therefore, we conducted a two-step chromatography procedure, consisting of strong anion-exchange chromatography and gel filtration chromatography, to purify an anti-histone H1 monoclonal immunoglobulin M antibody from the serum-free culture supernatant of hybridomas. Consequently, we successfully purified the monoclonal antibody at 96%, a purification rate at which its administration to organ transplantation model animals is possible.