CD73-generated adenosine promotes osteoblast differentiation.

CD731 is a GPI-anchored cell surface protein with ecto-5'-nucleotidase enzyme activity that plays a crucial role in adenosine production. While the roles of adenosine receptors (AR) on osteoblasts and osteoclasts have been unveiled to some extent, the roles of CD73 and CD73-generated adenosine in bone tissue are largely unknown. To address this issue, we first analyzed the bone phenotype of CD73-deficient (cd73(-/-)) mice. The mutant male mice showed osteopenia, with significant decreases of osteoblastic markers. Levels of osteoclastic markers were, however, comparable to those of wild-type mice. A series of in vitro studies revealed that CD73 deficiency resulted in impairment in osteoblast differentiation but not in the number of osteoblast progenitors. In addition, over expression of CD73 on MC3T3-E1 cells resulted in enhanced osteoblastic differentiation. Moreover, MC3T3-E1 cells expressed adenosine A(2A) receptors (A(2A)AR) and A(2B) receptors (A(2B)AR) and expression of these receptors increased with osteoblastic differentiation. Enhanced expression of osteocalcin (OC) and bone sialoprotein (BSP) observed in MC3T3-E1 cells over expressing CD73 were suppressed by treatment with an A(2B)AR antagonist but not with an A(2A) AR antagonist. Collectively, our results indicate that CD73 generated adenosine positively regulates osteoblast differentiation via A(2B)AR signaling.

Fibroblast growth factor-2 stimulates directed migration of periodontal ligament cells via PI3K/AKT signaling and CD44/hyaluronan interaction.

Fibroblast growth factor-2 (FGF-2) regulates a variety of functions of the periodontal ligament (PDL) cell, which is a key player during tissue regeneration following periodontal tissue breakdown by periodontal disease. In this study, we investigated the effects of FGF-2 on the cell migration and related signaling pathways of MPDL22, a mouse PDL cell clone. FGF-2 activated the migration of MPDL22 cells and phosphorylation of phosphatidylinositol 3-kinase (PI3K) and akt. The P13K inhibitors, Wortmannin and LY294002, suppressed both cell migration and akt activation in MPDL22, suggesting that the PI3K/akt pathway is involved in FGF-2-stimulated migration of MPDL22 cells. Moreover, in response to FGF-2, MPDL22 showed increased CD44 expression, avidity to hyaluronan (HA) partly via CD44, HA production and mRNA expression of HA synthase (Has)-1, 2, and 3. However, the distribution of HA molecular mass produced by MPDL22 was not altered by FGF-2 stimulation. Treatment of transwell membrane with HA facilitated the migration of MPDL22 cells and an anti-CD44 neutralizing antibody inhibited it. Interestingly, the expression of CD44 was colocalized with HA on the migrating cells when stimulated with FGF-2. Furthermore, an anti-CD44 antibody and small interfering RNA for CD44 significantly decreased the FGF-2-induced migration of MPDL22 cells. Taken together, PI3K/akt and CD44/HA signaling pathways are responsible for FGF-2-mediated cell motility of PDL cells, suggesting that FGF-2 accelerates periodontal regeneration by regulating the cellular functions including migration, proliferation and modulation of extracellular matrix production.

Intraosseous fat necrosis associated with alcoholic pancreatitis.

A 50-year-old man with a 30-year history of alcohol abuse was admitted because of abdominal pain. Based on an elevated serum amylase level and abdominal computed tomography findings, a diagnosis of alcoholic pancreatitis was made. The pancreatitis improved after 1 month of conservative therapy, but the patient complained of a tender right ankle that showed no abnormal findings on X-ray examination. Two months later, the patient was readmitted for recurrent pancreatitis and a swollen, warm, tender right ankle. Imaging studies, including plain radiographs, magnetic resonance imaging, and a bone scintigram showed the typical findings of intraosseous fat necrosis of the right tibia. We report a rare case of intraosseous fat necrosis associated with alcoholic pancreatitis.

[A case of groove pancreatitis observed from initial stage].

We report a case of groove pancreatitis. A 60-year-old man was admitted to our hospital because of nausea and vomitting. CT showed a mass lesion in the groove between the pancreas head, duodenum and common bile duct. He was given a diagnosis of the groove pancreatitis, and underwent endoscopic balloon dilation. Groove pancreatitis is rare, and we discuss this case with references.

CD73-generated adenosine restricts lymphocyte migration into draining lymph nodes.

After an inflammatory stimulus, lymphocyte migration into draining lymph nodes increases dramatically to facilitate the encounter of naive T cells with Ag-loaded dendritic cells. In this study, we show that CD73 (ecto-5'-nucleotidase) plays an important role in regulating this process. CD73 produces adenosine from AMP and is expressed on high endothelial venules (HEV) and subsets of lymphocytes. Cd73(-/-) mice have normal sized lymphoid organs in the steady state, but approximately 1.5-fold larger draining lymph nodes and 2.5-fold increased rates of L-selectin-dependent lymphocyte migration from the blood through HEV compared with wild-type mice 24 h after LPS administration. Migration rates of cd73(+/+) and cd73(-/-) lymphocytes into lymph nodes of wild-type mice are equal, suggesting that it is CD73 on HEV that regulates lymphocyte migration into draining lymph nodes. The A(2B) receptor is a likely target of CD73-generated adenosine, because it is the only adenosine receptor expressed on the HEV-like cell line KOP2.16 and it is up-regulated by TNF-alpha. Furthermore, increased lymphocyte migration into draining lymph nodes of cd73(-/-) mice is largely normalized by pretreatment with the selective A(2B) receptor agonist BAY 60-6583. Adenosine receptor signaling to restrict lymphocyte migration across HEV may be an important mechanism to control the magnitude of an inflammatory response.

Fibroblast growth factor-2 regulates expression of osteopontin in periodontal ligament cells.

Osteopontin is a protein found in the bone-related matrix and plays multiple regulatory roles in mineralizing and non-mineralizing tissue. In osteogenic cell-lines, the expression of osteopontin increases with the progression of differentiation, but both the expression and function of osteopontin vary with the cell type and its activation state. In this study, we examined the expression of osteopontin by clones established from mouse periodontal ligament, in response to inorganic phosphate and fibroblast growth factor (FGF)-2, which can induce periodontal tissue regeneration. The involvement of inorganic phosphate in the expression of osteopontin during the course of cell differentiation of a clone MPDL22 was confirmed by addition of foscarnet, an inorganic phosphate transport inhibitor. Although FGF-2 decreased the mRNA expression of almost every bone-related protein in MPDL22, FGF-2 upregulated the expression of osteopontin in MPDL22 at both mRNA and protein levels. Interestingly, FGF-2 enhanced the concentration of osteopontin in the culture supernatant of MPDL22, whereas inorganic phosphate did not. The FGF-2-induced osteopontin in the culture supernatant seems to be involved in cell survival activity. An immunohistochemical study showed that the FGF-2-induced osteopontin was mainly present in perinuclear matrices while the inorganic phosphate-induced osteopontin was associated with extracellular matrices in addition to perinuclear matrices. The present results indicated that FGF-2 induces unique expression of osteopontin, which may play a role different from the other bone-related proteins during the process of periodontal tissue regeneration by FGF-2.

[A case of endocrine carcinoma of the sigmoid colon].

We report a case of endocrine carcinoma of the sigmoid colon. A 71-year-old man was admitted to our hospital because of constipation and bloody stool. Colonoscopy showed a mass lesion with irregular ulceration in the sigmoid colon. He was given a diagnosis of the poorly differentiated adenocarcinoma of the colon, and underwent sigmoidectomy with dissection of the lymph nodes. Histological and immunohistochemical examinations of the resected specimen revealed endocrine carcinoma. Endocrine carcinoma of the colon is rare, and the prognosis is very poor. We discuss this case with references.

Basic fibroblast growth factor regulates expression of heparan sulfate in human periodontal ligament cells.

Heparan sulfate (HS) proteoglycan is a widely distributed biological molecule that mediates a variety of physiological responses in development, cell growth, cell migration, and wound healing. We examined the effects of basic fibroblast growth factor-2 (FGF-2), which is known to modulate extracellular matrix (ECM) production of various cell types, on the production of HS proteoglycan by human periodontal ligament (HPDL) cells. We also examined the effects of FGF-2 on the expression of syndecans, a major family of membrane-bound HS proteoglycans. Treatment of HPDL cells with FGF-2 for 72 h resulted in a pronounced increase in the level of HS in the culture supernatant in a dose-dependent manner. However, reverse transcription-polymerase chain reaction data (RT-PCR) revealed that FGF-2 marginally reduced the gene expression of syndecan-1, -2, and -4, and did not alter the level of syndecan-3 mRNA. Furthermore, FGF-2 did not have an effect on the mRNA expression of enzymes associated with HS biosynthesis. Interestingly, FACS analysis revealed that the syndecan family displayed diverse alterations in response to FGF-2. FGF-2 barely altered the expression of syndecan-1, but decreased the expression of syndecan-2 and -4 on HPDL cells. Moreover, dot blot analysis showed that FGF-2 did not alter the level of syndecan-1 and -2, but enhanced the level of syndecan-4 in culture supernatants of FGF-2-stimulated HPDL cells. These results suggest that the FGF-2-activated increase in the level of HS in conditioned medium may be a result of shedding of syndecan-4 from the HPDL cell surface. Taken together, FGF-2 may differentially regulate the expression of HS proteoglycans in a HS-proteoglycan-subtype-dependent manner. The diversity of the expression patterns of HS proteoglycans may be associated with the FGF-2-induced biological functions of HPDL cells.