Takeshi Kinjo

CpG DNA as a vaccine adjuvant

Synthetic oligodeoxynucleotides (ODNs) containing unmethylated CpG motifs trigger cells that express Toll-like receptor 9 (including human plasmacytoid dendritic cells and B cells) to mount an innate immune response characterized by the production of Th1 and proinflammatory cytokines. When used as vaccine adjuvants, CpG ODNs improve the function of professional antigen-presenting cells and boost the generation of humoral and cellular vaccine-specific immune responses. These effects are optimized by maintaining ODNs and vaccine in close proximity. The adjuvant properties of CpG ODNs are observed when administered either systemically or mucosally, and persist in immunocompromised hosts. Preclinical studies indicate that CpG ODNs improve the activity of vaccines targeting infectious diseases and cancer. Clinical trials demonstrate that CpG ODNs have a good safety profile and increase the immunogenicity of coadministered vaccines.

TLR-based immune adjuvants

This work describes the nature and strength of the immune response induced by various Toll-like receptor ligands and their ability to act as vaccine adjuvants. It reviews the various ligands capable of triggering individual TLRs, and then focuses on the efficacy and safety of those agents for which clinical results are available.

Critical role of Vα14+ natural killer T cells in the innate phase of host protection against Streptococcus pneumoniae infection

The present study was designed to elucidate the role of Vα14+ NKT cells in the host defense against pulmonary infection with Streptococcus pneumoniae using Jα281 gene‐disrupted mice (Jα281KO mice) that lacked this lymphocyte subset. In these mice, pneumococcal infection was severely exacerbated, as shown by the shorter survival time and marked increase of live bacteria in the lung compared to wild‐type (WT) mice. The proportion of Vα14+ NKT cells, detected by an α‐galactosylceramide (α‐GalCer)‐loaded CD1d tetramer, increased in thelung after S. pneumoniae infection. This increase was significantly reduced in mice with a genetic disruption of monocyte chemotactic protein (MCP)‐1, which was produced in the early phaseof infection in WT mice. In the lungs of Jα281KO mice, the number of neutrophils was significantly lower at 12 h than that in WT mice. In support of this finding, macrophage inflammatory protein (MIP)‐2 and TNF‐α synthesis in infected lungs was significantly reduced at 3 h and at both 3 and 6 h, respectively, in Jα281KO mice, compared to WT mice. In addition, treatment of mice with α‐GalCer significantly improved the outcome of this infection. Our results demonstrated MCP‐1‐dependent recruitment of Vα14+ NKT cells and their critical role in early host protection against S. pneumoniae by promoting the trafficking of neutrophils to the site of infection.

Lower expression of Th1‐related cytokines and inducible nitric oxide synthase in mice with streptozotocin‐induced diabetes mellitus infected with Mycobacterium tuberculosis

Diabetes mellitus is an important predisposing factor for tuberculosis. The aim of this study was to investigate the mechanism underlying this association using a murine model. Mice with streptozotocin‐induced diabetes mellitus were prone to Mycobacterium tuberculosis infection, as indicated by increased numbers of live bacteria in lung, liver and spleen. In diabetic mice, the levels of IL‐12 and IFN‐γ in the lung, liver and spleen were lower than those in control animals on day 14 postinfection, while the opposite was true for IL‐4 levels in the lung and liver. The expression pattern of inducible nitric oxide synthase (iNOS), in the two mice types was as for IL‐12 and IFN‐γ. In addition, peritoneal exudate cells obtained from diabetic mice produced lower amounts of IL‐12 and NO than those from control mice, when stimulated in vitro with M. bovis BCG. Spleen cells from diabetic mice infected with M. tuberculosis produced a significantly lower amount of IFN‐γ upon restimulation with purified protein derivatives (PPD) than those from infected nondiabetic mice. Interestingly, addition of high glucose levels (33 mM) to the cultures of PPD‐restimulated spleen cells reduced the synthesis of IFN‐γ only in diabetic mice, and not in nondiabetic mice. Finally, control of blood glucose levels by insulin therapy resulted in improvement of the impaired host protection and Th1‐related cytokine synthesis. Our results suggest that the reduced production of Th1‐related cytokines and NO account for the hampered host defense against M. tuberculosis infection under diabetic conditions.

Accumulation of γδ T Cells in the Lungs and Their Regulatory Roles in Th1 Response and Host Defense against Pulmonary Infection with Cryptococcus neoformans

The present study was designed to elucidate the role of γδ T cells in the host defense against pulmonary infection with Cryptococcus neoformans. The γδ T cells in lungs commenced to increase on day 1, reached a peak level on day 3 or 6, and then decreased on day 10 after intratracheal infection. The increase of these cells was similar in monocyte chemoattractant protein (MCP)-1-deficient mice, although that of NK and NKT cells was significantly reduced. The number of live microorganisms in lungs on days 14 and 21 was significantly reduced in mice depleted of γδ T cells by a specific mAb compared with mice treated with control IgG. Similarly, elimination of this fungal pathogen was promoted in γδ T cell-deficient (TCR-δ−/−) mice compared with control littermate mice. Finally, lung and serum levels of IFN-γ on days 7 and 14 and on day 7 postinfection, respectively, were significantly higher in TCR-δ−/− mice than in littermate mice, whereas levels of TGF-β showed the opposite results. IL-4 and IL-10 were not different between these mice. IFN-γ production by draining lymph node cells upon restimulation with cryptococcal Ags was significantly higher in the infected TCR-δ−/− mice than in control mice. Our results demonstrated that γδ T cells accumulated in the lungs in a manner different from NK and NKT cells after cryptococcal infection and played a down-modulatory role in the development of Th1 response and host resistance against this fungal pathogen.

Dectin‐1 Is Not Required for the Host Defense to Cryptococcus neoformans

Dectin‐1 is known as a sole receptor for β‐glucan, a major cell wall component of fungal microorganisms. In the current study, we examined the role of this molecule in the host defense to Cryptococcus neoformans, an opportunistic fungal pathogen in AIDS patients. There was no significant difference in the clinical course and cytokine production between dectin‐1 gene‐deficient and control mice. These results indicate that dectin‐1 is not likely essential for the development of host protective responses to C. neoformans.

CpG oligodeoxynucleotides promote the host protective response against infection with Cryptococcus neoformans through induction of interferon-gamma production by CD4+ T cells.

In the present study, we elucidated the effect of synthetic CpG‐containing oligodeoxynucleotides (ODN) on pulmonary and disseminated infection caused by Cryptococcus neoformans. CDF‐1 mice were inoculated intratracheally with a highly virulent strain of this pathogen, which resulted in massive bacterial growth in the lung, dissemination to the brain and death. Administration of CpG‐ODN promoted the clearance of C. neoformans in the lungs, decreased their dissemination to brain and prolonged the survival of infected mice. These effects correlated well with the enhanced production of interleukin (IL)‐12 and interferon (IFN)‐γ and attenuated secretion of IL‐4 in bronchoalveolar lavage fluids (BALF) and promoted development of Th1 cells, as indicated by the increased production of IFN‐γ by paratracheal lymph node cells upon restimulation with cryptococcal antigens. The IFN‐γ synthesis in BALF was inhibited by depletion of CD8+ and CD4+ T cells on days 7 and 14 after infection, respectively, but not by depletion of NK and γδ T cells. Consistent with these data, intracellular expression of IFN‐γ was detected predominantly in CD8+ and CD4+ T cells in the lung on days 7 and 14, respectively. The protective effect of CpG‐ODN, as shown by the prolonged survival, was completely and partially inhibited by depletion of CD4+ or CD8+ T cells, respectively, but not by depletion of other cells. Finally, TNF‐α was markedly induced by CpG‐ODN, and the protective effect of this agent was strongly inhibited by neutralizing anti‐TNF‐α MoAb. Our results indicate that CpG‐ODN alters the Th1–Th2 cytokine balance and promotes host resistance against infection with C. neoformans.

A Compendium for Mycoplasma pneumoniae

Historically, atypical pneumonia was a term used to describe an unusual presentation of pneumonia. Currently, it is used to describe the multitude of symptoms juxtaposing the classic symptoms found in cases of pneumococcal pneumonia. Specifically, atypical pneumonia is a syndrome resulting from a relatively common group of pathogens including Chlamydophila sp., and Mycoplasma pneumoniae. The incidence of M. pneumoniae pneumonia in adults is less than the burden experienced by children. Transmission rates among families indicate children may act as a reservoir and maintain contagiousness over a long period of time ranging from months to years. In adults, M. pneumoniae typically produces a mild, “walking” pneumonia and is considered to be one of the causes of persistent cough in patients. M. pneumoniae has also been shown to trigger the exacerbation of other lung diseases. It has been repeatedly detected in patients with bronchitis, asthma, chronic obstructive pulmonary disorder, and cystic fibrosis. Recent advances in technology allow for the rapid diagnosis of M. pneumoniae through the use of polymerase chain reaction or rapid antigen tests. With this, more effort has been afforded to identify the causative etiologic agent in all cases of pneumonia. However, previous practices, including the overprescribing of macrolide treatment in China and Japan, have created increased incidence of macrolide-resistant M. pneumoniae. Reports from these countries indicate that >85% of M. pneumoniae pneumonia pediatric cases are macrolide-resistant. Despite its extensively studied past, the smallest bacterial species still inspires some of the largest questions. The developments in microbiology, diagnostic features and techniques, epidemiology, treatment and vaccines, and upper respiratory conditions associated with M. pneumoniae in adult populations are included within this review.

Effect of Suppressive Oligodeoxynucleotides on the Development of Inflammation-Induced Papillomas

Inflammation contributes to the development of papillomas and squamous cell carcinomas in the well-established 7,12-dimethylbenz(a)anthracene (DMBA)/12-O-tetradecanoylphorbol-l3-acetate (TPA) model of skin carcinogenesis. Synthetic oligonucleotides (ODN) containing repetitive TTAGGG motifs have been shown to block deleterious inflammatory reactions in murine models of autoimmunity, pneumonitis, and shock. This article examines whether treatment with suppressive (Sup) ODN can interfere with DMBA/TPA-induced inflammation, thereby reducing papilloma formation. Results indicate that Sup ODN block TPA-dependent skin hyperplasia, edema, and leukocytic infiltration. Sup ODN also inhibit the upregulation of genes encoding pro-oncogenic chemokines and other markers of inflammation including CXCL2, CCL2, COX-2, and ODC (ornithine decarboxylase). Of greatest import, Sup ODN reduce papilloma formation in a dose- and sequence-dependent manner. These findings suggest that Sup ODN may provide a novel means of preventing inflammation and associated oncogenesis. Cancer Prev Res; 4(5); 752–7. ©2011 AACR.

Addison’s disease due to tuberculosis that required differentiation from SIADH

A 77-year-old man was admitted to our hospital complaining of general fatigue. Serum sodium was 116 mEq/l and serum antidiuretic hormone (ADH) was elevated. Radiologic examination revealed nodules in the brain as well as in both adrenal glands. Based on the findings of fluorine-18 fluorodeoxyglucose positron emission tomography (FDG-PET), we had considered that the cause of the hyponatremia was syndrome of inappropriate secretion of antidiuretic hormone (SIADH) due to active extrapulmonary tuberculosis. Against our expectations, the patient’s condition got worse just after he began antituberculous therapy; we finally diagnosed Addison’s disease by additional hormonal tests. His condition recovered immediately with the administration of high-dose hydrocortisone, and the tuberculous lesions became smaller with antituberculous medications. Although tuberculous Addison’s disease has been decreasing markedly in recent years, we have to consider the possibility of adrenal insufficiency when hyponatremia is observed in patients with active tuberculosis or those having a past history of tuberculosis.