Hajime Sano

Cyclooxygenase-1 and -2 expression in rheumatoid synovial tissues. Effects of interleukin-1 beta, phorbol ester, and corticosteroids.

High levels of immunoreactive cyclooxygenase (Cox; prostaglandin H synthase) are present in synovia from patients with rheumatoid arthritis (RA). We now show that the recently identified inducible isoform of Cox, Cox-2, is expressed in synovia from patients with RA. To further explore modulation of the Cox isoforms in RA synovial tissues, we examined the expression and modulation of Cox-1 and -2 in rheumatoid synovial explant cultures and cultured rheumatoid synovial fibroblast-like cells (synoviocytes). Immunoprecipitation of in vitro labeled proteins and Western blot analysis demonstrated the presence of both Cox-1 and -2 under basal conditions in freshly explanted rheumatoid synovial tissues. De novo synthesis of Cox-2 polypeptide was enhanced by IL-1 beta or PMA, and dramatically suppressed by dexamethasone (dex). Cox-1 expression, under the same conditions, showed only minor variation. Since mRNA for Cox-2 is highly unstable, we examined the regulation of Cox-2 transcripts in cultured rheumatoid synoviocytes. Under basal conditions both Cox-1 and -2 mRNAs were present at low levels, but Cox-2 mRNA was markedly increased by treatment with IL-1 beta or PMA. dex markedly suppressed the induction of Cox-2 mRNA. In sharp contrast, Cox-1 transcripts were not modulated by IL-1 beta or dex. These data suggest that modulation of Cox-2 expression by IL-1 beta and corticosteroids may be an important component of the inflammatory process in synovial tissues from patients with RA.

15-deoxy-delta(12,14)-PGJ(2) induces synoviocyte apoptosis and suppresses adjuvant-induced arthritis in rats.

Peroxisome proliferator–activated receptors (PPARs) are members of the nuclear hormone receptor superfamily and have a dominant regulatory role in adipocyte and monocyte differentiation. PPAR-γ agonists are also negative regulators of macrophage activation and have modulatory effects on tumorigenesis. In this study we demonstrate that synovial tissue localized expression of PPAR-γ in patients with rheumatoid arthritis (RA). We detected markedly enhanced expression of PPAR-γ in macrophages, as well as modestly enhanced expression in the synovial lining layer, fibroblasts, and endothelial cells. Activation of the PPAR-γ by 15-deoxy-Δ12,14-prostaglandin J2 (15d-PGJ2) and the synthetic PPAR-γ ligand (troglitazone) induced RA synoviocyte apoptosis in vitro. Moreover, intraperitoneal administration of these PPAR-γ ligands ameliorated adjuvant-induced arthritis with suppression of pannus formation and mononuclear cell infiltration in female Lewis rats. Anti-inflammatory effects of 15d-PGJ2 were more potent than troglitazone. These findings suggest that PPAR-γ may be an important immunoinflammatory mediator and its ligands, especially 15d-PGJ2, may be useful in the treatment of RA.

In vivo cyclooxygenase expression in synovial tissues of patients with rheumatoid arthritis and osteoarthritis and rats with adjuvant and streptococcal cell wall arthritis.

Cyclooxygenase (COX), or prostaglandin (PG) H synthase, plays a role in inflammatory diseases, but very limited data exist on the regulation of COX in vivo. We, therefore, studied the in vivo expression of COX in synovia from patients with rheumatoid arthritis (RA) and osteoarthritis (OA), as well as joints of rats with streptococcal cell wall (SCW) and adjuvant arthritis. Extensive and intense intracellular COX immunostaining, which correlated with the extent and intensity of mononuclear cell infiltration, was observed in cells throughout RA synovia. Significantly less or equivocal staining was noted in OA and normal human synovia. Similarly, COX immunostaining was equivocal in the joints of normal and arthritis-resistant F344/N rats. In contrast, high level expression developed rapidly in euthymic female Lewis (LEW/N) rats throughout the hindlimb joints and overlying tissues including skin, preceding or paralleling clinically apparent experimental arthritis. COX was expressed in the joints of athymic LEW.rnu/rnu rats 2-4 d after injection of SCW or adjuvant but was not sustained. Physiological doses of antiinflammatory glucocorticoids, but not progesterone, suppressed both arthritis and COX expression in LEW/N rats. These observations suggest that, in vivo, (a) COX expression is upregulated in inflammatory joint diseases, (b) the level of expression is genetically controlled and is a biochemical correlate of disease severity, (c) sustained high level up-regulation is T cell dependent, and (d) expression is down-regulated by antiinflammatory glucocorticoids.

Expression of cyclooxygenase-2 in prostate carcinoma

Nonsteroidal antiinflammatory drugs inhibiting cyclooxygenase (COX) enzyme activity in both its constitutive (COX‐1) and inducible (COX‐2) isoforms were shown also to inhibit the development of colon carcinoma in animal models. COX‐2 is an inducer of angiogenesis of new blood vessels. The expression of COX‐1 and COX‐2 in prostate tissues from patients with prostate carcinoma was investigated using reverse transcriptase‐polymerase chain reaction (RT‐PCR) and immunohistochemistry.

Intracellular Role for Sphingosine Kinase 1 in Intestinal Adenoma Cell Proliferation

ABSTRACT Sphingosine kinase (Sphk) enzymes are important in intracellular sphingolipid metabolism as well as in the biosynthesis of sphingosine 1-phosphate (S1P), an extracellular lipid mediator. Here, we show that Sphk1 is expressed and is required for small intestinal tumor cell proliferation in ApcMin/+ mice. Adenoma size but not incidence was dramatically reduced in ApcMin/+Sphk−/− mice. Concomitantly, epithelial cell proliferation in the polyps was significantly attenuated, suggesting that Sphk1 regulates adenoma progression. Although the S1P receptors (S1P1R, S1P2R, and S1P3R) are expressed, polyp incidence or size was unaltered in ApcMin/+S1p2r−/−, ApcMin/+S1p3r−/−, and ApcMin/+S1p1r+/− bigenic mice. These data suggest that extracellular S1P signaling via its receptors is not involved in adenoma cell proliferation. Interestingly, tissue sphingosine content was elevated in the adenomas of ApcMin/+Sphk1−/− mice, whereas S1P levels were not significantly altered. Concomitantly, epithelial cell proliferation and the expression of the G1/S cell cycle regulator CDK4 and c-myc were diminished in the polyps of ApcMin/+Sphk1−/− mice. In rat intestinal epithelial (RIE) cells in vitro, Sphk1 overexpression enhanced cell cycle traverse at the G1/S boundary. In addition, RIE cells treated with sphingosine but not C6-ceramide exhibited reduced cell proliferation, reduced retinoblastoma protein phosphorylation, and cyclin-dependent kinase 4 (Cdk4) expression. Our findings suggest that Sphk1 plays a critical role in intestinal tumor cell proliferation and that inhibitors of Sphk1 may be useful in the control of intestinal cancer.

Local secretion of corticotropin-releasing hormone in the joints of Lewis rats with inflammatory arthritis

Corticotropin-releasing hormone (CRH), the principal regulator of the hypothalamic-pituitary-adrenal axis, is also secreted in peripheral inflammatory sites, where it acts as a local proinflammatory agent. Arthritis-susceptible LEW/N rats have profoundly deficient hypothalamic CRH responses to inflammatory stimuli and other stressors. Arthritis-resistant F344/N rats, on the other hand, have a robust increase in hypothalamic CRH in response to the same stimuli. Contrasting with these hypothalamic CRH responses, we now show that CRH expression is markedly increased in the joints and surrounding tissues of LEW/N rats with streptococcal cell wall- and adjuvant-induced arthritis, whereas it is not increased in similarly treated F344/N rats and is only transiently increased in congenitally athymic nude LEW.rnu/rnu rats. Glucocorticoid treatment suppressed, but did not eliminate, CRH immunoreactivity in the joints of LEW/N rats. CRH mRNA was present in inflamed synovia, as well as in spinal cord, and inflamed synovia also expressed specific CRH-binding sites. We compared CRH expression in inflamed joints with another well-characterized proinflammatory neuropeptide, substance P (SP), and found that SP immunoreactivity paralleled that of CRH. In summary, although LEW/N rats have deficient hypothalamic CRH responses to inflammatory stimuli compared with F344/N rats, they express relatively high levels of CRH at the site of inflammation. Analogous to SP, CRH may be delivered to the inflammatory site by peripheral nerves and/or synthesized at the inflammatory site. These data provide further support for the concept that CRH not only triggers the pituitary-adrenal antiinflammatory cascade, but also functions as an antithetically active local mediator of acute and chronic inflammatory arthritis. These data also illustrate the complex interrelationships of the nervous, endocrine, immune, and inflammatory systems.

Relationship of CD4+CD25+ regulatory T cells to immune status in HIV-infected patients.

Objective:To determine whether the frequencies of CD4+CD25+ regulatory T cells (T Reg) were related to immune status in HIV-infected patients. Methods:Peripheral blood CD4 T-cell populations were examined for T-helper 1 cells (Th1), T-helper 2 cells (Th2), and T Reg by intracellular staining for interferon (IFN)-γ and interleukin (IL)-4, and surface staining for CD25, respectively. The immunoregulatory properties of T Reg were assessed by measurement of the inhibitory effects of isolated CD4+CD25+ T Reg on CD4+CD25− T-cell proliferation. Results:Isolated CD4+CD25+ T Reg from both HIV-infected patients and healthy controls strongly expressed CD45RO, HLA-DR, and FoxP3. HIV-infected patients with detectable plasma HIV-1 RNA showed a statistically significant increase in CD4+CD25high T Reg frequencies (P < 0.05) compared to healthy controls, with T Reg frequency inversely proportional to CD4 T-cell count (P < 0.01). However, in HIV-infected patients with undetectable plasma HIV-1 RNA, CD4+CD25high T Reg frequencies were not increased and were not related to CD4 T-cell counts. In both HIV-infected patient groups, T Reg frequency was inversely related to Th1 frequency (detectable HIV-1 RNA: P < 0.05; undetectable: P < 0.001), but positively related to Th2 frequency (detectable HIV-1 RNA: P < 0.01; undetectable: P < 0.001). T Reg activity was lower in patients with detectable plasma HIV-1 RNA than in patients with undetectable plasma HIV-1 RNA. Conclusions:Increased T Reg frequencies in peripheral blood were related to low peripheral blood CD4 T-cell counts and polarization toward Th2 immune responses in HIV-infected patients.

Local secretion of corticotropin-releasing hormone by enterochromaffin cells in human colon

BACKGROUND/AIMS Corticotropin-releasing hormone (CRH) is a regulator of the hypothalamic-pituitary-adrenal axis and a coordinator of the gastrointestinal response to stress. In addition to its central effects, CRH has peripheral effects on the immune system. CRH is present in several human tissues, such as the brain, spinal cord, adrenal medulla, lung, liver, peripheral blood leukocytes, as well as the gastrointestinal tract. The current study examined the local production of CRH in the normal human colon. METHODS Normal human colonic tissues obtained by endoscopic biopsy were immunostained with anti-CRH and anti-5-hydroxytryptamine antibody and analyzed for CRH messenger (m)RNA by a reverse-transcribed polymerase chain reaction method and by in situ hybridization. RESULTS Immunoreactive CRH and CRH mRNA were detected in the colonic mucosal cells in the neighborhood of the base of the crypts. The mucosal cells that expressed CRH mRNA also immunostained with anti-5-hydroxytryptamine antibody. CONCLUSIONS Normal human colonic mucosal enterochromaffin cells produce CRH. CRH in the colonic mucosa may play a role in the modulation of the intestinal immune system and/or other gastrointestinal functions basally during stressful conditions.

Expression of peroxisome proliferator-activated receptors (PPARs) in human urinary bladder carcinoma and growth inhibition by its agonists.

Recent studies have demonstrated that peroxisome proliferator activator‐receptors(PPAR)‐γ is expressed in various cancer tissues and its ligand induces growth arrest of these cancer cells through apoptosis. In our study, we investigated the expression of PPAR‐α, β and γ in human bladder tumor (BT) and normal bladder (NB) tissues as well as the effects of PPAR‐γ ligands. Specimens were obtained from 170 patients with BT and 20 with NB. The expressions were investigated using RT‐PCR and immunohistochemical methods. We also investigated the inhibitory effect of PPAR‐γ ligands on BT‐derived cell line. Immunoreactive PPAR‐α and ‐β were significantly apparent in both BT and NB tissues. Although no marked expression of PPAR‐γ was observed in NB tissue, significant expression was found in BT tissue. The extent and intensity of immunoreactive PPAR‐γ polypeptides in BT cells were statistically much greater than those of NB cells. Correlation between PPAR‐γ expression and tissue type or progression of bladder cancer was observed; PPAR‐γ expression was higher in G3 of bladder cancer than in G1 and was higher in advanced than in early cancer. PPAR‐γ agonists, troglitazone and 15‐deoxy‐Δ12, 14‐prostaglandin J2 inhibited the growth of the BT cells. PPAR‐γ is expressed in bladder tumor, and results suggest that PPAR‐γ ligands may mediate potent antiproliferative effects against BT cells. Thus, PPAR‐γ has the ability to become a new target in treatment of bladder tumor.

Transin/stromelysin expression in the synovium of rats with experimental erosive arthritis. In situ localization and kinetics of expression of the transformation-associated metalloproteinase in euthymic and athymic Lewis rats.

Transin is a neutral metalloproteinase initially isolated from malignantly transformed rat fibroblasts and subsequently shown to be homologous to human stromelysin. We performed Northern blot analysis on synovial tissue specimens from Lewis rats with proliferative and invasive streptococcal cell wall (SCW) arthritis. Transin mRNA was present in abundance, as was the mRNA of the c-myc oncogene, which is associated with cellular proliferation. Immunohistochemical staining of synovia from rats with chronic SCW arthritis showed high-level transin expression in the cells of the lining layer and underlying stroma, as well as in chondrocytes and osteoclasts in subchondral bone. Intense nuclear staining for the Myc oncoprotein was also detected with a cross-reactive antibody to v-Myc. Transin stained similarly in the early, rapid-onset, thymus-independent, acute phase of SCW arthritis. In the T cell-dependent adjuvant arthritis, transin expression was noted by day 4, 6 d before the influx of mononuclear cells and the onset of clinical disease. Athymic rats did not express transin. We concluded that transin is a marker of proliferative, invasive arthritis in rats and appears early in the course of disease development, but requires a competent immune system to sustain its expression in these model arthropathies.