JTP-117968, a novel selective glucocorticoid receptor modulator, exhibits significant anti-inflammatory effect while maintaining bone mineral density in mice.

Classic glucocorticoids have been prescribed for various inflammatory diseases, such as rheumatoid arthritis, due to their outstanding anti-inflammatory effects. However, glucocorticoids cause numerous unwanted side effects, including osteoporosis and diabetes. Hence, selective glucocorticoid receptor modulators (SGRMs), which retain anti-inflammatory effects with minimized side effects, are among the most anticipated drugs in the clinical field. The assumption is that there are two major mechanisms of action via glucocorticoid receptors, transrepression (TR) and transactivation (TA). In general, anti-inflammatory effects of glucocorticoids are largely due to TR, while the side effects associated with glucocorticoids are mostly mediated through TA. We previously reported that JTP-117968, a novel SGRM, maintained partial TR activity while remarkably reducing the TA activity. In this study, we investigated the anti-inflammatory effect of JTP-117968 on a lipopolysaccharide (LPS) challenge model and collagen-induced arthritis (CIA) model in mice. Meanwhile, we tested the effect of JTP-117968 on the bone mineral density (BMD) in mouse femur to evaluate the side effect. Based on the evaluation, JTP-117968 reduced the plasma levels of tumor necrosis factor α induced by LPS challenge in mice significantly. Remarkably, CIA development was suppressed by JTP-117968 comparably with prednisolone and PF-802, an active form of fosdagrocorat that has been developed clinically as an orally available SGRM. Strikingly, the side effect of JTP-117968 on mouse femoral BMD was much lower than those of PF-802 and prednisolone. Therefore, JTP-117968 has attractive potential as a new therapeutic option against inflammatory diseases with minimized side effects compared to classic glucocorticoids.

JTZ-951 (enarodustat), a hypoxia-inducibe factor prolyl hydroxylase inhibitor, stabilizes HIF-α protein and induces erythropoiesis without effects on the function of vascular endothelial growth factor.

JTZ-951 (enarodustat) is an oral hypoxia-inducible factor (HIF) prolyl hydroxylase inhibitor. JTZ-951 has inhibitory activities on human HIF-prolyl hydroxylase 1-3, but not on various receptors or enzymes. In Hep3B cells, JTZ-951 increased HIF-1α and HIF-2α protein levels, erythropoietin (EPO) mRNA levels, and EPO production. In normal rats, after a single oral dose of JTZ-951, the hepatic and renal EPO mRNA levels and plasma EPO concentrations were also increased. In 5/6-nephrectomized rats, repeated oral doses of JTZ-951 once daily or intermittent dosing showed the erythropoiesis stimulating effect. The administration of JTZ-951 at a high dose increased plasma vascular endothelial growth factor (VEGF) levels; however, retinal VEGF mRNA levels and the retinal vascular permeability were not changed. Finally, we evaluated the effect of JTZ-951 in a colorectal cancer cell-inoculated mouse model. Although JTZ-951 at a high dose increased the plasma VEGF, it had no effect on tumor growth. In summary, JTZ-951 induces erythropoiesis without affecting VEGF function. Therefore, it is expected that JTZ-951 will be a new oral candidate that increases and maintains hemoglobin concentrations in renal anemia patients.

Prostaglandin E2 stimulates granulocyte colony-stimulating factor production via the prostanoid EP2 receptor in mouse peritoneal neutrophils.

G-CSF is a hemopoietic growth factor involved in granulocytic differentiation of progenitor cells. In this study, we investigated the effects of PGE2 on G-CSF production in murine peritoneal neutrophils in vitro and in vivo. PGE2 augmented LPS-primed G-CSF release from peritoneal neutrophils. This augmentation was mimicked by a type E prostanoid receptor (EP)2-selective agonist but not by other EP-specific agonists. Indeed, the effect of PGE2 on G-CSF release was abolished in neutrophils isolated from EP2-deficient mice. PGE2 and an EP2 agonist have the ability to stimulate G-CSF gene expression even in the absence of LPS. In the casein-induced peritonitis model, the appearance of G-CSF in the casein-injected peritoneal cavity associated well with the timing of neutrophil infiltration as well as PGE2 levels in exudates, with a peak value at 6 h postinjection. Inhibition of endogenous PG synthesis by indomethacin resulted in a marked decrease in G-CSF content and neutrophil number in the peritoneal cavity. Moreover, EP2-deficient mice exhibited a strikingly reduced G-CSF content in peritoneal exudates with comparable responses in neutrophil migration and local PGE2 production at 6 h postinjection. These results suggest that the PGE2-EP2 system contributes to the local production of G-CSF during acute inflammation.

Expression of L-histidine decarboxylase in granules of elicited mouse polymorphonuclear leukocytes.

Infiltrating polymorphonuclear leukocytes (PMN) in the peritoneal cavity were found to express L-histidine decarboxylase (HDC), the rate-limiting enzyme of histamine synthesis, in a csein-induced peritonitis model. Expression of HDC was detected in the elicited PMN, but not in the peripheral blood leukocytes. The peritoneal lavage fluids in this model were found to augment histamine synthesis in PMN isolated from the bone marrow. Rapid post-translational processing of HDC was observed in PMN, and the dominant form of HDC was the mature 53-kDa form, which was found to co-localize with a granule enzyme, matrix metalloproteinase-9 (MMP-9). Treatment of PMN with the phorbol ester PMA, which stimulates the release of MMP-9, did not liberate the granular HDC. Immunofluorescence studies using an anti-HDC antibody strongly suggested that HDC is bound to the cytosolic side of the granule membranes. These observations suggest that HDC is induced upon infiltration of PMN into the mouse peritoneal cavity and that histamine is synthesized by HDC attached to the granule membranes of PMN.

Uptake of histamine by mouse peritoneal macrophages and a macrophage cell line, RAW264.7.

We have previously demonstrated that dietary histamine is accumulated in the spleens of l-histidine decarboxylase (HDC)-deficient mice, which lack endogenous histamine synthesis. To characterize the clearance system for dietary histamine in mice, we investigated the cell type and mechanism responsible for histamine uptake in the spleens of HDC-deficient mice. Immunohistochemical analyses using an antihistamine antibody indicated that a portion of the CD14+ cells in the spleen is involved in histamine storage. Peritoneal macrophages obtained from Balb/c mice and a mouse macrophage cell line, RAW264.7, had potential for histamine uptake, which was characterized by a low affinity and high capacity for histamine. The histamine uptake by RAW264.7 cells was observed at physiological temperature and was potently inhibited by pyrilamine, chlorpromazine, quinidine, and chloroquine, moderately inhibited by N alpha-methylhistamine, dopamine, and serotonin, and not affected by tetraethylammonium and 1-methyl-4-phenylpyridinium. Intracellular histamine was not metabolized in RAW264.7 cells and was released at physiological temperature in the absence of extracellular histamine. These results suggest that histamine uptake by macrophages may be involved in the clearance of histamine in the local histamine-enriched environment.