Atsushi Ihata

Protective immunity against influenza A virus induced by immunization with DNA plasmid containing influenza M gene.

DNA vaccination is characterized by its preferential induction of the cytotoxic T cell lymphocyte (CTL) response and is expected to be a useful means of protection against viral infection. We examined the protective effect of an expression plasmid (pME18S-M) containing M1 and M2 genes of influenza A/PR/8/34. We detected the CTL activity by introducing these plasmids into BALB/c mice by either the intramuscular or the intranasal route. The influenza-specific antibody response was also induced, although its neutralizing effect against influenza virus was not observed. From 70 to 80% protection was observed in the mice immunized with the pME18S-M plasmid followed by lethal infection with influenza viruses of the A/WSN/33 and A/PR/8/34 strains, whereas all mice without the plasmid vaccination failed to survive. This protective activity was significantly weakened when the CD8(+) cells of these immunized mice were eliminated by several injections of anti-CD8 antibody. The protective activity was also weakened when anti-CD4 antibody was injected in the early phase of DNA vaccination. These data suggest that the pME18S-M plasmid is useful as a DNA vaccine for overcoming highly mutational influenza viruses.

Protection against influenza virus challenge by topical application of influenza DNA vaccine.

We studied the use of a DNA vaccine expressing the matrix (M) gene of the influenza virus A/PR/8/34. Mice were immunized by painting the DNA vaccine three times on the skin after removal of its keratinocytic layers. Immunization by this method produced M-specific antibodies and cytotoxic T lymphocyte (CTL) response, and acquired resistance against influenza virus challenge. This protection was abrogated by the in vivo injection of anti-CD8 or anti-CD4 monoclonal antibody. We further found that simultaneous topical application (t.a.) of GM-CSF expression plasmid (pGM-CSF) or liposomes plus mannan produced stronger immune response competence and enhanced the protective effect against influenza virus challenge. The present study revealed that administering DNA vaccine by topical application can elicit both humoral and cell-mediated immunity (CMI).

CpG Oligodeoxynucleotides Enhance Neonatal Resistance to Listeria Infection

Infection by Listeria monocytogenes causes serious morbidity and mortality during the neonatal period. Previous studies established that immunostimulatory CpG oligodeoxynucleotides (ODN) can increased the resistance of adult mice to many infectious pathogens, including Listeria. This work examines the capacity of CpG ODN to stimulate a protective immune response in newborns. Results indicate that dendritic cells, macrophages, and B cells from 3-day-old mice respond to CpG stimulation by secreting IFN-γ, IL-12, and/or TNF-α. Spleen cells from CpG-treated neonates produce large amounts of cytokine and NO when exposed to bacteria in vitro. Newborns treated with CpG ODN are protected from lethal Listeria challenge and generate Ag-specific CD4 and CD8 T cells that afford long-term protection against subsequent infection. These results demonstrate that cellular elements of the neonatal immune system respond to stimulation by CpG ODN, thereby reducing host susceptibility to infectious pathogens.

Ultrasonography is a potent tool for the prediction of progressive joint destruction during clinical remission of rheumatoid arthritis

ObjectivesAlthough “clinical remission” has been a realistic goal of treatment in rheumatoid arthritis (RA), there is evidence that subclinical synovitis is associated with ongoing structural damage even after clinical remission is achieved. In the study reported here, we assessed whether ultrasonography (US) can predict progressive joint destruction during clinical remission of RA.MethodsThirty-one patients with RA in clinical remission based on the disease activity score in 28 joints were recruited for this study. Bilateral wrists and all of the metacarpophalangeal and proximal interphalangeal (PIP) joints were examined by power Doppler (PD) ultrasonography (US), and the PD signals were scored semiquantitatively in each joint. The total PD score was calculated as the sum of individual scores for each joint.ResultsAmong 22 RA patients who maintained clinical remission during the 2-year follow-up period, seven showed radiographic progression. Radiographic progression was strongly associated with total PD score at entry, with all patients showing radiographic progression having a total PD score of ≥2 at entry and none of the patients with a total PD score of ≤1 showing any radiographic progression. There was no significant association of therapeutic agents with progressing or non-progressing cases.ConclusionsPD-US detects synovitis causing joint destruction even when the patient is in clinical remission. Thus, remission visible on US is essential to reach “true remission” of RA.

Time‐dependent increased risk for serious infection from continuous use of tumor necrosis factor antagonists over three years in patients with rheumatoid arthritis

To investigate associations between continuous treatments with tumor necrosis factor (TNF) antagonists and risk for developing serious infections (SIs) over 3 years in Japanese patients with rheumatoid arthritis (RA) enrolled in the Registry of Japanese RA Patients for Long‐Term Safety (REAL) database.

Screening of tuberculosis by interferon-γ assay before biologic therapy for rheumatoid arthritis

Infection with Mycobacterium tuberculosis (M. tuberculosis) is a critical complication in anti-TNF therapies. In 141 BCG vaccinated healthy individuals and 71 rheumatoid arthritis (RA) patients as screening before anti-TNF therapies, M. tuberculosis specific immune responses were evaluated by tuberculin skin test (TST) and enzyme-linked immunospot assay (ELISPOT), which detected antigen specific IFN-gamma secreting cells in peripheral blood mononuclear cells simulated with either purified protein derivative (PPD), early secretory antigen target 6 (ESAT-6) or culture filtrate protein 10 (CFP-10). Induration over 5 mm in TST was found in 87.9% of controls and 21.4% of RA patients. Erythema size in TST was significantly suppressed in RA patients, especially those receiving prednisolone (PSL), whereas the PPD specific IFN-gamma secretion was less attenuated. Significant responses to either ESAT-6 or CFP-10 in ELISPOT were detected in 14.1% of RA patients including those having positive TST, while the ELISPOT assay was negative in all healthy individuals and 73.3% of RA patients having positive TST. Of ELISPOT positive RA patients, mean dosage of PSL was 4.58 mg and 1.25 mg in TST negative and positive patients, respectively. Thus, ELISPOT is useful for screening of tuberculosis in RA patients, even in those receiving corticosteroids.

Drug retention rates and relevant risk factors for drug discontinuation due to adverse events in rheumatoid arthritis patients receiving anticytokine therapy with different target molecules

Objective To compare reasons for discontinuation and drug retention rates per reason among anticytokine therapies, infliximab, etanercept and tocilizumab, and the risk of discontinuation of biological agents due to adverse events (AE) in patients with rheumatoid arthritis (RA). Method This prospective cohort study included Japanese RA patients who started infliximab (n=412, 636.0 patient-years (PY)), etanercept (n=442, 765.3 PY), or tocilizumab (n=168, 206.5 PY) as the first biological therapy after their enrolment in the Registry of Japanese Rheumatoid Arthritis Patients for Long-term Safety (REAL) database. Drug retention rates were calculated using the Kaplan–Meier method. To compare risks of drug discontinuation due to AE for patients treated with these biological agents, the Cox proportional hazard model was applied. Results The authors found significant differences among the three therapeutic groups in demography, clinical status, comorbidities and usage of concomitant drugs. Development of AE was the most frequent reason for discontinuation of biological agents in the etanercept and tocilizumab groups, and the second most frequent reason in the infliximab group. Discontinuation due to good control was observed most frequently in the infliximab group. Compared with etanercept, the use of infliximab (HR 1.69; 95% CI 1.14 to 2.51) and tocilizumab (HR 1.98; 95% CI 1.04 to 3.76) was significantly associated with a higher risk of discontinuation of biological agents due to AE. Conclusions Reasons for discontinuation are significantly different among biological agents. The use of infliximab and tocilizumab was significantly associated with treatment discontinuation due to AE compared with etanercept.

Association of reduced heme oxygenase-1 with excessive Toll-like receptor 4 expression in peripheral blood mononuclear cells in Behcet's disease.

IntroductionToll-like receptors (TLRs) mediate signaling that triggers activation of the innate immune system, whereas heme oxygenase (HO)-1 (an inducible heme-degrading enzyme that is induced by various stresses) suppresses inflammatory responses. We investigated the interaction between TLR and HO-1 in an inflammatory disorder, namely Behçets disease.MethodsThirty-three patients with Behçets disease and 30 healthy control individuals were included in the study. Expression levels of HO-1, TLR2 and TLR4 mRNA were semiquantitatively analyzed using a real-time PCR technique, and HO-1 protein level was determined by immunoblotting in peripheral blood mononuclear cells (PBMCs) and polymorphonuclear leukocytes. In some experiments, cells were stimulated with lipopolysaccharide or heat shock protein-60; these proteins are known to be ligands for TLR2 and 4.ResultsLevels of expression of HO-1 mRNA were significantly reduced in PBMCs from patients with active Behçets disease, whereas those of TLR4, but not TLR2, were increased in PBMCs, regardless of disease activity. Moreover, HO-1 expression in PBMCs from patients with Behçets disease was repressed in the presence of either lipopolysaccharide or heat shock protein-60.ConclusionThe results suggest that upregulated TLR4 is associated with HO-1 reduction in PBMCs from patients with Behçets disease, leading to augmented inflammatory responses.

Immunomodulatory effect of a plasmid expressing CD40 ligand on DNA vaccination against human immunodeficiency virus type‐1

CD40 ligand is a costimulatory molecule which acts a potent immunomodulator. We found the mice inoculated with human CD40 ligand expression plasmid (pMEhCD40L) combined with human immunodeficiency virus type‐1 (HIV‐1) DNA vaccine exhibited both humoral and cellular antigen‐specific immunological enhancement. The expression of hCD40L induced predominantly antigen‐specific immunoglobulin G (IgG) antibody response while it failed to induce mucosal IgA response. Delayed‐type hypersensitivity (DTH) and cytotoxic T lymphocyte (CTL) activity were induced in a dose‐dependent manner. Examination of the relative levels of the two IgG subclasses showed that co‐injection of pMEhCD40L enhanced IgG2a response without suppressing IgG1 response. Similarly, the expression of pMEhCD40L enhanced not only T helper 1 (Th1)‐ but also Th2‐type cytokine production. In conclusion, co‐inoculation of pMEhCD40L with DNA vaccine was shown to be a useful way to enhance CTL responses without suppressing the humoral immune response in acquired immune deficiency syndrome (AIDS) patients.

Therapeutic angiogenesis in patients with systemic sclerosis by autologous transplantation of bone-marrow-derived cells

We examined the efficacy and safety of autologous transplantation of bone-marrow-derived cells in patients with intractable ulcers caused by systemic sclerosis. Eight patients with ulcers resistant to treatment were enrolled. Bone marrow cells were gathered from the bilateral iliac crests with multiple repositioning bone marrow needles, and bone-marrow-derived mononuclear cells were isolated and injected into skeletal muscles of the ischemic limb. Visual analog scale (VAS), Sclerosis Health Assessment Questionnaire (SHAQ), modified Rodnan total skin score (mTSS), and the size and depth of the ulcer were examined. Thermography, capillaroscopy, intra-arterial digital subtraction angiography (IA-DSA), and laser Doppler flowmetry were also examined before and after transplantation. In all patients, reduction of ulcer size and improvement of VAS were observed after treatment. Elevation of surface temperature, increase of blood flow volume, and new capillaries of the nail bed were also found after our treatment. There were no major adverse effects of this treatment. Autologous transplantation of bone-marrow-derived cells was shown to be a novel and useful approach to intractable ulcers in systemic sclerosis.