Mitsunori Yamakawa

Toll-Like Receptor-2 Modulates Ventricular Remodeling After Myocardial Infarction

Background—Toll-like receptors (TLRs) are members of the interleukin-1 receptor family and transduce similar signals as interleukin-1 receptor in response to exogenous pathogens. Recent studies have demonstrated that TLRs are activated by endogenous signals, such as heat shock proteins and oxidative stress, that may contribute to ventricular remodeling after myocardial infarction. In this study, we determined whether TLR-2 was involved in cardiac remodeling after myocardial infarction. Methods and Results—Myocardial infarction was induced by surgical left anterior descending coronary artery ligation on wild-type (WT) mice and TLR-2–knockout (KO) mice. The survival rate was significantly higher in KO mice than in WT mice 4 weeks after myocardial infarction (65% versus 43%, P <0.03). Infarct size and degree of inflammatory cell infiltration in infarct area were similar between WT and KO mice. However, myocardial fibrosis in the noninfarct area of KO mice was much less than in WT mice (P <0.01) and was accompanied by reduced transforming growth factor-&bgr;1 and collagen type 1 mRNA expressions (P <0.01 and P <0.05, respectively). Left ventricular dimensions at end diastole were smaller in KO mice than in WT mice at 1 week (P <0.05) and 4 weeks (P <0.01) after surgery. Furthermore, fractional shortening was higher (27.7±2.5% versus 21.2±2.6%, P <0.05, at 1 week, and 24.3±2.0% versus 16.6±2.5%, P <0.01, at 4 weeks) in KO mice compared with WT mice. Conclusions—These data suggest that TLR-2 plays an important role in ventricular remodeling after myocardial infarction.

Phosphorylation of Akt/PKB is required for suppression of cancer cell apoptosis and tumor progression in human colorectal carcinoma

Akt/protein kinase B (PKB), which is included in phosphatidyl inositol‐3‐OH kinase (PI3K) signaling, controls many intracellular processes, such as the suppression of apoptosis and the promotion of the cell cycle. Therefore, the authors investigated phosphorylated Akt (Ser473) in colorectal carcinomas to reveal the role of PI3K signaling during the development of colorectal carcinoma.

Expression of HDAC1 and CBP/p300 in human colorectal carcinomas

Background: The histone-modifying enzymes histone deacetylase (HDAC) and histone acetyltransferase (HAT) control gene transcriptional activation and repression in human malignancies. Aims: To analyse the expression of HDAC/HAT-associated molecules such as HDAC1, CREB-binding protein (CBP) and p300 in human colorectal carcinomas, and investigate the relationship between their expression levels and clinicopathological parameters. Methods: Expression levels of HDAC1, CBP, and p300 in human colorectal cancer were investigated by immunohistochemistry. In situ hybridisation (ISH) and reverse transcription (RT)-PCR analyses were also carried out to confirm mRNA expression levels of these genes. Immunoreactivity was evaluated semi-quantitatively using a staining index (SI). The relationships between the SIs and clinicopathological findings were analysed and survival curves were calculated using the Kaplan–Meier method and log-rank tests. Results: The mean SIs for HDAC1, CBP, and p300 in this series of tumours were much higher than those in normal colonic mucosa. The presence of HDAC1 and CBP mRNAs on colorectal carcinoma cells as well as normal epithelial cells was confirmed by ISH analysis. A marked increase in p300 mRNA levels was detected in a majority of cases by RT-PCR. Among the patients with colorectal cancer, overexpression of p300 (SI>11.9) correlated with a poor prognosis, whereas high CBP expression levels (SI>16.6) indicated long-term survival. Conclusion: Results showed the up-regulation of these three histone-modifying molecules in this series of colorectal cancers and suggested that monitoring of CBP and p300 may assist prediction of the prognosis in patients with colorectal adenocarcinoma.

Expression of cell cycle markers in colorectal carcinoma : Superiority of cyclin A as an indicator of poor prognosis

Our aim was to analyze the relationship between the proliferative activity of cancer cells, assessed using some cell cycle markers, and clinicopathological factors in colorectal carcinoma patients. Immunostaining for Ki‐67 (pan‐cell cycle marker), cyclin D1 (G1‐phase marker) and cyclin A (S‐ to G2‐phase marker), and in situ hybridization for histone H3 mRNA (S‐phase marker) were carried out. Immunoreactivity was evaluated semiquantitatively using a scoring system to calculate a staining index (SI). The expression of cyclin D1, histone H3 mRNA and cyclin A correlated significantly with Ki‐67 antigen expression. The SIs of Ki‐67, cyclin A and histone H3 mRNA were significantly higher in patients ≥65 years of age than in those <65. The SIs of Ki‐67 and cyclin D1 in poorly differentiated adenocarcinomas were significantly higher than in the other tumor types. Furthermore, the SI of cyclin D1 in carcinomas with lymph node metastasis was higher than in carcinomas without metastasis and was higher in advanced carcinomas than early carcinomas. The overall survival was significantly lower in patients with cyclin A overexpression than in those without. Multivariate analysis indicated that cyclin A overexpression is an independent prognostic factor in patients with colorectal adenocarcinoma. Our results indicate that cyclin D1 overexpression correlates with poor adenocarcinoma differentiation and tumor progression, and cyclin A overexpression is a superior indicator of poor prognosis compared with the other cell cycle markers tested. Int. J. Cancer (Pred. Oncol.) 84:225–233, 1999.

Morphology, function and pathology of follicular dendritic cells

The precise ultrastructural morphology and functions In reactive conditions of lymphoid follicles (LF) and dendritic cells, including follicular dendrltic cells (FDC) are reviewed; as Well as the pathognomonic role of FDC In some disease conditions and finally, the cellular origin of FDC. In reactive conditions, FDC In each of the fivre follicular zones have distinct ultrastructural features, retlecting the different three dimensional structures and functions of these zones. The FDC framework may be supported by some characteristic factors, including desmosome‐like junctions between FDC and the expression of flbronectin and laminin receptors and caldeasmon on FDC. FDC, especially In the light zone, express various cytokine receptors, but produce only one cytokine, TGF‐β. The outer zone may not only be a cellular pathway in the LF, but may also provide a site for germinal center B cell prollferation, and the FDC‐lymphocyte cluster Is not the site of germinal center B cell division. In patients with autoimmune diseases, such as Hashimotos thyroiditis and rheumatoid arthritis, FDC may be in a hyperfunctional state, whereas those In patients w*H immunosuppressive disorders, such as Kimuras disease and AIDS, may be in a dysfunctional state. FDC may be derived from fibroblastic reticulum cells in lymphatic tissues rather than in bone marrow cells. The data discussed In this retview provide fascinating insight into the roles of FDC, which are intimately related to the migration, proliferation, cell selection and differentiation of B cells in secondary LF.

Mature dendritic cells make clusters with T cells in the invasive margin of colorectal carcinoma.

Dendritic cells (DCs) take up tumour‐specific antigen and migrate to regional lymph nodes to generate anti‐tumour immunity. Although DC infiltration within human tumour tissue has been reported, the subset distribution has not been fully investigated. This study used immunohistochemistry to investigate DC subset distribution in colorectal adenocarcinoma. DCs expressing CD83, which are considered to be mature DCs, were present mainly in the invasive margin of cancer stroma. CD83+ DCs in the invasive margin formed clusters with lymphocytes, the majority of which were CD45RO+ T cells. The number of CD4+ T cells was greater than that of CD8+ T cells in these DC–lymphocyte clusters. The elongated cytoplasmic processes of CD83+ DCs engulfed CD4+ T cells. DCs that express CD1a were located throughout tumour tissue. Although the number of CD1a+ DCs was almost the same as that of CD83+ DCs in the invasive margin of cancer stroma, CD1a+ DCs were mostly scattered and rarely formed clusters with lymphocytes. DCs that expressed both CD1a and CD83 were rare. Moreover, about 20% of lymphocytes in DC–lymphocyte clusters were positive for Ki‐67, and CD83+ DCs were attached to Ki‐67+ cells. CD83+ DCs were also present in T‐cell areas that had a distinctive structure involving the presence of B‐cell lymphoid follicles. These results suggest that in the invasive margin of the colorectal cancer stroma, mature CD83+ DCs form clusters with T cells to promote T‐cell activation for the generation of tumour‐specific immunity. Copyright

Protection of thyroid cancer cells by complement-regulatory factors.

Background. Clinical and experimental studies have suggested that complement activation may play a role in tumor cytotoxicity. Little information is available concerning the presence of complement activation and the localization of complement‐regulatory factors in cells or tissues of malignant tumors. The aim of the present study was to examine, using immunohistochemistry and immunoelectron microscopy, whether the complement system is activated in tissues of thyroid carcinoma and whether thyroid carcinoma cells are protected from cell lysis by in situ complement activation.

Phosphorylated Akt/PKB controls cell growth and apoptosis in intraductal papillary-mucinous tumor and invasive ductal adenocarcinoma of the pancreas.

Introduction Akt/PKB promotes cell proliferation and rescues cells from apoptosis. Aim To evaluate the role of Akt/PKB, a key molecule in phosphatidylinositol 3-OH kinase (PI3K) signaling, during the development of pancreatic duct neoplasias such as intraductal papillary–mucinous tumor (IPMT) and invasive ductal adenocarcinoma (IDAC) of the pancreas. Methodology and Results In PK-45H pancreatic cancer cells, the growth-inhibitory and apoptosis-inducing effects of LY294002, a PI3K inhibitor, were detected in a concentration-dependent manner, followed by the reduction of phosphorylated Akt levels. Immunohistochemical analyses revealed that frequent overexpression of phosphorylated Akt (Ser473) was detected in 10 (63%) of 16 IPMTs and 14 (70%) of 20 IDACs. It is interesting that the incidence of Akt phosphorylation closely correlated with Ki-67 immunoreactivity and had an inverse association with the number of cases of apoptotic bodies in both IPMT and IDAC. Although there was no good correlation with other clinicopathologic parameters, the two patients with recurrent IPMT had high levels of phosphorylated Akt. Conclusion Our findings suggest that activation of Akt plays an important role during the progression of these pancreatic duct neoplasias at the early stage. Furthermore, inhibition of the PI3K–Akt/PKB pathway may have therapeutic potential in the treatment of pancreatic duct tumors.

Infiltrating dendritic/Langerhans cells in primary breast cancer.

It is fully anticipated that dendritic cells (DCs) will become a mainstay for inclusion in biological therapies for patients with cancer including breast cancer. To elucidate the cellular composition of DCs infiltrating human breast cancers, we investigated the correlations between the density of infiltrating DCs and some clinicopathological factors of breast cancer patients, examined cytokine expression on cancer cells and finally, assessed the numbers of CD45RO+ tumor infiltrating lymphocytes (TIL). Tissues adjacent to cancer nests contained significantly more S-100 protein+ and S-100 protein+ CD1a− DCs, but less CD1a+ DCs, than the nests. In invasive ductal carcinomas infiltration by S-100 protein+ DCs within and adjacent to nests, CDla+ DCs within nests and S-100 protein+ CD1a− DCs adjacent to nests was denser than that in non-invasive carcinomas. With respect to the histological subtypes, there were fewer DCs in scirrhous carcinomas. Patients with stage IV disease had significantly fewer DCs of primary lesions than at other clinical stages. There were good correlations between infiltration by S-100 protein+ DCs and expression of the cytokines GM-CSF, IL-1α and TNF-α on cancer cells and between GM-CSF expression and S-100 protein+ CD1a− DCs. There was a close correlation between CD45RO+ TIL and S-100 protein+ DC densities both within and adjacent to the cancer nests and the S-100 protein+ CD1a− DC density adjacent to the cancer nests. Despite extensive immunoelectron microscopic observation, CD1a+ DCs within cancer nests contained only few Birbecks granule-like structure. These data indicate that cancer nests are infiltrated predominantly by CD1a+ DCs, whereas S-100 protein+ CD1a− DCs predominate in surrounding tissues, and a infiltration by DCs may require cytokine expression on cancer cells and simultaneous lymphocyte infiltration. The findings of this clinicopathological study indicate the importance of evaluating simultaneously the types and localizations of infiltrating DCs in cancer tissues.

Expression of Toll-like receptors and their signaling pathways in rheumatoid synovitis.

Objective. Toll-like receptors (TLR) recognizing endogenous and exogenous danger signals could play a role in rheumatoid arthritis (RA). Our aim was to describe the presence, localization, and extent of expression of TLR and their adapters. Methods. TLR 1, 2, 3, 4, 5, 6, and 9 receptors, and myeloid differentiation primary response protein 88, Toll/interleukin receptor (TIR) domain-containing adapter protein MyD88 adapter-like, and TIR domain-containing adapter-inducing interferon/TIR-containing adapter molecule-1 adapters were analyzed in RA (n = 10) and osteoarthritis (OA; n = 5) samples using real-time polymerase chain reaction (PCR). Their colocalization with cellular markers CD68, CD15, CD3, CD4, CD8, CD20, dendritic cell lysosomal-associated membrane protein (DC-LAMP), CD123, and 5B5 was analyzed in double immunofluorescence staining. Results. In RA, ß-actin standardized messenger RNA of TLR 2, 3, and 9 (p < 0.001) were particularly high. TLR 5 and 6 were also elevated (p < 0.05), but TLR 1 and 4 and adapters did not differ between RA and OA. In double-staining, TLR and adapters were strongly labeled in myeloid and plasmacytoid dendritic cells (DC), moderately in CD68+ type A lining cells/macrophages, and weakly to moderately in 5B5+ type B lining cells/fibroblasts. CD3+/CD4+ and CD3+/CD8+ T cells and CD20+ B cells in perivenular areas and in lymphoid follicles were moderately TLR- and weakly adapter-positive. In OA, TLR and adapters were weakly immunolabeled in vascular, lining, and inflammatory cells. Conclusion. RA synovium showed abundant expression of TLR. RA synovitis tissue seems to be responsive to TLR ligands. DC, type A cells/macrophages, and type B cells/fibroblasts are, in that order from highest to lowest, equipped with TLR, suggesting a hierarchical responsiveness. In RA, danger-associated molecular patterns to TLR interactions may particularly drive DC to autoinflammatory and autoimmune cascades/synovitis.