Tomohisa Baba

CCL3-CCR5 Axis Regulates Intratumoral Accumulation of Leukocytes and Fibroblasts and Promotes Angiogenesis in Murine Lung Metastasis Process

Metastasis proceeds through interaction between cancer cells and resident cells such as leukocytes and fibroblasts. An i.v. injection of a mouse renal cell carcinoma, Renca, into wild-type mice resulted in multiple metastasis foci in lungs and was associated with intratumoral accumulation of macrophages, granulocytes, and fibroblasts. A chemokine, CCL3, was detected in infiltrating cells and, to a lesser degree, tumor cells, together with an infiltration of leukocytes expressing CCR5, a specific receptor for CCL3. A deficiency of the CCL3 or CCR5 gene markedly reduced the number of metastasis foci in the lung, and the analysis using bone marrow chimeric mice revealed that both bone marrow- and non-bone marrow-derived cells contributed to metastasis formation. CCL3- and CCR5-deficient mice exhibited a reduction in intratumoral accumulation of macrophages, granulocytes, and fibroblasts. Moreover, intratumoral neovascularization, an indispensable process for metastasis, was attenuated in these gene-deficient mice. Intrapulmonary expression of matrix metalloproteinase (MMP)-9 and hepatocyte growth factor (HGF) was enhanced in wild-type mice, and the increases were markedly diminished in CCL3- and CCR5-deficient mice. Furthermore, MMP-9 protein was detected in macrophages and granulocytes, the cells that also express CCR5 and in vitro stimulation by CCL3-induced macrophages to express MMP-9. Intratumoral fibroblasts expressed CCR5 and HGF protein. In vitro CCL3 stimulated fibroblasts to express HGF. Collectively, the CCL3-CCR5 axis appears to regulate intratumoral trafficking of leukocytes and fibroblasts, as well as MMP-9 and HGF expression, and as a consequence to accelerate neovascularization and subsequent metastasis formation.

Crucial Contribution of Thymic Sirpα+ Conventional Dendritic Cells to Central Tolerance against Blood-Borne Antigens in a CCR2-Dependent Manner

Thymic dendritic cells (DCs) as well as thymic epithelial cells are presumed to be major sentinels in central tolerance by inducing the apoptosis of autoreactive T progenitor cells. The thymic DC population is composed of heterogeneous subsets including CD11c+B220+ plasmacytoid DCs, CD11c+B220−CD8α+ signal regulatory protein α (Sirpα)− and CD11c+B220−CD8α−Sirpα+ conventional DCs (cDCs). However, the distinctive role of each DC subset remains undefined. We show herein that Sirpα+ cDCs, a minor subpopulation, was disseminated in the thymic cortical area with some of them uniquely localized inside perivascular regions and nearby small vessels in the thymus. The Sirpα+ but not Sirpα− cDC subset can selectively capture blood-circulating Ags. Moreover, in CCR2-deficient mice, the thymic Sirpα+ cDC subset, but not other thymic cell components, was moderately decreased especially in the perivascular regions. Concomitantly, these mice exhibited a modest impairment in intrathymic negative selection against blood-borne Ags, with the reduced capacity to uptake blood-borne Ags. Given their intrathymic cortical localization, CD11c+B220−CD8α−Sirpα+ cDCs can have a unique role in the development of central tolerance against circulating peripheral Ags, at least partially in a CCR2-dependent manner.

Decreased proteasomal activity causes age-related phenotypes and promotes the development of metabolic abnormalities.

The proteasome is a multicatalytic enzyme complex responsible for the degradation of both normal and damaged proteins. An age-related decline in proteasomal activity has been implicated in various age-related pathologies. The relevance of decreased proteasomal activity to aging and age-related diseases remains unclear, however, because suitable animal models are not available. In the present study, we established a transgenic (Tg) mouse model with decreased proteasomal chymotrypsin-like activity. Tg mice exhibited a shortened life span and developed age-related phenotypes. In Tg mice, polyubiquitinated and oxidized proteins accumulated, and the expression levels of cellular proteins such as Bcl-xL and RNase L were altered. When Tg mice were fed a high-fat diet, they developed more pronounced obesity and hepatic steatosis than did wild-type mice. Consistent with its role in lipid droplet formation, the expression of adipose differentiation-related protein (ADRP) was elevated in the livers of Tg mice. Of note, obesity and hepatic steatosis induced by a high-fat diet were more pronounced in aged than in young wild-type mice, and aged wild-type mice had elevated levels of ADRP, suggesting that the metabolic abnormalities present in Tg mice mimic those in aged mice. Our results provide the first in vivo evidence that decreased proteasomal chymotrypsin-like activity affects longevity and aggravates age-related metabolic disorders, such as obesity and hepatic steatosis.

Chemokines in tumor development and progression.

Chemokines were originally identified as mediators of the inflammatory process and regulators of leukocyte trafficking. Subsequent studies revealed their essential roles in leukocyte physiology and pathology. Moreover, chemokines have profound effects on other types of cells associated with the inflammatory response, such as endothelial cells and fibroblasts. Thus, chemokines are crucial for cancer-related inflammation, which can promote tumor development and progression. Increasing evidence points to the vital effects of several chemokines on the proliferative and invasive properties of tumor cells. The wide range of activities of chemokines in tumorigenesis highlights their roles in tumor development and progression.

Safety and efficacy of pirfenidone in idiopathic pulmonary fibrosis in clinical practice

BACKGROUND Previous pirfenidone trials have only involved patients with mild-to-moderate idiopathic pulmonary fibrosis (IPF). The aim of this study was to investigate the safety and efficacy of pirfenidone in patients with mild-to-severe IPF in clinical practice. METHODS The clinical records of 76 patients who were diagnosed with IPF and received pirfenidone were reviewed. RESULTS The most frequent adverse event was anorexia, although the grade of anorexia in most patients was mild. Dose reduction of pirfenidone improved anorexia in 84% affected patients, which resulted in a high medication compliance rate. The mean forced vital capacity (FVC) at the initiation of pirfenidone therapy in this study was approximately 10% lower than that in previous clinical trials. The mean change in FVC during the 6-month period prior to the therapy initiation was -188 mL, which improved to -19 mL during the 6-month period after therapy. Significant attenuation in percentage predicted diffusion capacity of the lung for carbon monoxide decline was also achieved after pirfenidone therapy initiation. The efficacy of pirfenidone in attenuating the degree of FVC decline was higher in the group with FVC decline of ≥150 mL during the 6-month period prior to therapy initiation. The levels of serum markers, such as KL-6 and SP-D, were also lowered by the therapy. CONCLUSIONS These results showed that pirfenidone was well-tolerated and had beneficial effects in patients with mild-to-severe and/or progressive IPF. The degree of disease progression prior to the initiation of pirfenidone therapy had an impact on the response to the therapy.

Exclusive expression of proteasome subunit β5t in the human thymic cortex

The ubiquitin-proteasome pathway, which degrades intracellular proteins, is involved in numerous cellular processes, including the supply of immunocompetent peptides to the antigen presenting machinery. Proteolysis by proteasomes is conducted by three beta subunits, beta1, beta2, and beta5, of the 20S proteasome. Recently, a novel beta subunit expressed exclusively in cortical thymic epithelial cells was discovered in mice. This subunit, designated beta5t, is a component of the thymoproteasome, a specialized type of proteasomes implicated in thymic positive selection. In this study, we show that, like its mouse counterpart, human beta5t is expressed exclusively in the thymic cortex. Human beta5t was expressed in approximately 80% of cortical thymic epithelial cells and some cortical dendritic cells. Human beta5t was incorporated into proteasomes with two other catalytically active beta subunits beta1i and beta2i, forming 20S proteasomes with subunit compositions characteristic of thymoproteasomes. The present study demonstrates, for the first time, the existence of thymoproteasomes in the human thymic cortex, indicating that thymoproteasome function is likely conserved between humans and mice.

Crucial involvement of the CX3CR1-CX3CL1 axis in dextran sulfate sodium-mediated acute colitis in mice.

Ingestion of DSS solution can induce in rodents acute colitis with a massive infiltration of neutrophils and macropahges, mimicking pathological changes observed in the acute phase of UC patients. Concomitantly, DSS ingestion enhanced the expression of a potent macrophage‐tropic chemokine, CX3CL1/fractalkine, and its receptor, CX3CR1, in the colon. WT but not CX3CR1‐deficient mice exhibited marked body weight loss and shortening of the colon after DSS ingestion. Moreover, inflammatory cell infiltration was attenuated in CX3CR1‐deficient mice together with reduced destruction of glandular architecture compared with WT mice. DSS ingestion enhanced intracolonic iNOS expression by macrophages and nitrotyrosine generation in WT mice, but iNOS expression and nitrotyrosine generation were attenuated in CX3CR1‐deficient mice. The analysis on bone marrow chimeric mice revealed that bone marrow‐derived but not non‐bone marrow‐derived CX3CR1‐expressing cells were a major source of iNOS. These observations would indicate that the CX3CL1‐CX3CR1 axis can regulate the expression of iNOS, a crucial mediator of DSS‐induced colitis. Thus, targeting the CX3CL1‐CX3CR1 axis may be effective for the treatment of IBDs such as UC.

Antitumor effect after radiofrequency ablation of murine hepatoma is augmented by an active variant of CC chemokine ligand 3/macrophage inflammatory protein-1á

Several chemokines are used for immunotherapy against cancers because they can attract immune cells such as dendritic and cytotoxic T cells to augment immune responses. Radiofrequency ablation (RFA) is used to locally eliminate cancers such as hepatocellular carcinoma (HCC), renal cell carcinoma, and lung cancer. Because HCC often recurs even after an eradicative treatment with RFA, additional immunotherapy is necessary. We treated tumor-bearing mice by administering ECI301, an active variant of CC chemokine ligand 3, after RFA. Mice were injected s.c. with BNL 1ME A.7R.1, a murine hepatoma cell line, in the bilateral flank. After the tumor became palpable, RFA was done on the tumor of one flank with or without ECI301. RFA alone eliminated the treated ipsilateral tumors and retarded the growth of contralateral non-RFA-treated tumors accompanied by massive T-cell infiltration. Injection of ECI301 augmented RFA-induced antitumor effect against non-RFA-treated tumors when administered to wild-type or CCR5-deficient but not CCR1-deficient mice. ECI301 also increased CCR1-expressing CD11c(+) cells in peripheral blood and RFA-treated tumors after RFA. Deficiency of CCR1 impairs accumulation of CD11c(+), CD4(+), and CD8(+) cells in RFA-treated tumors. Furthermore, in IFN-gamma-enzyme-linked immunospot assay, ECI301 augmented tumor-specific responses after RFA whereas deficiency of CCR1 abolished this augmentation. Thus, we proved that ECI301 further augments RFA-induced antitumor immune responses in a CCR1-dependent manner.

Accelerated hepatocellular carcinoma development in mice expressing the Pim-3 transgene selectively in the liver

Pim-3, a proto-oncogene with serine/threonine kinase activity, was enhanced in hepatocellular carcinoma (HCC) tissues. To address the roles of Pim-3 in HCC development, we prepared transgenic mice that express human Pim-3 selectively in liver. The mice were born at a Mendelian ratio, were fertile and did not exhibit any apparent pathological changes in the liver until 1 year after birth. Pim-3-transgenic mouse-derived hepatocytes exhibited accelerated cell cycle progression. The administration of a potent hepatocarcinogen, diethylnitrosamine (DEN), induced accelerated proliferation of liver cells in Pim-3 transgenic mice in the early phase, compared with that observed for wild-type mice. Treatment with DEN induced lipid droplet accumulation with increased proliferating cell numbers 6 months after the treatment. Eventually, wild-type mice developed HCC with a frequency of 40% until 10 month after the treatment. Lipid accumulation was accelerated in Pim-3 transgenic mice with higher proliferating cell numbers, compared with that observed for wild-type mice. Pim-3 transgenic mice developed HCC with a higher incidence (80%) and a heavier burden, together with enhanced intratumoral CD31-positive vascular areas, compared with that observed for wild-type mice. These observations indicate that Pim-3 alone cannot cause, but can accelerate HCC development when induced by a hepatocarcinogen, such as DEN.

Chemokines in Cancer Development and Progression and Their Potential as Targeting Molecules for Cancer Treatment

Chemokines were initially identified as bioactive substances, which control the trafficking of inflammatory cells including granulocytes and monocytes/macrophages. Moreover, chemokines have profound impacts on other types of cells associated with inflammatory responses, such as endothelial cells and fibroblasts. These observations would implicate chemokines as master regulators in various inflammatory responses. Subsequent studies have further revealed that chemokines can regulate the movement of a wide variety of immune cells including lymphocytes, natural killer cells, and dendritic cells in both physiological and pathological conditions. These features endow chemokines with crucial roles in immune responses. Furthermore, increasing evidence points to the vital effects of several chemokines on the proliferative and invasive properties of cancer cells. It is widely acknowledged that cancer develops and progresses to invade and metastasize in continuous interaction with noncancerous cells present in cancer tissues, such as macrophages, lymphocytes, fibroblasts, and endothelial cells. The capacity of chemokines to regulate both cancerous and noncancerous cells highlights their crucial roles in cancer development and progression. Here, we will discuss the roles of chemokines in carcinogenesis and the possibility of chemokine targeting therapy for the treatment of cancer.