Christine Abreu

Transcriptional induction of prostaglandin G/H synthase-2 by basic fibroblast growth factor.

In serum-free mouse osteoblastic MC3T3-E1 cells, basic fibroblastic growth factor (bFGF) induced mRNA and protein for prostaglandin G/H synthase-2 (PGHS-2), the major enzyme in arachidonic acid (AA) conversion to prostaglandins. mRNA accumulation peaked at 1 h with bFGF 1 nM. In cells stably transfected with a 371-bp PGHS-2 promoter-luciferase reporter, bFGF stimulated luciferase activity, which peaked at 2-3 h with bFGF 1-10 nM. In the presence of exogenous AA, bFGF stimulated PGE2 production, which paralleled luciferase activity. In serum-free neonatal mouse calvarial cultures, bFGF stimulated PGE2 production in the absence of exogenous AA. bFGF stimulated PGHS-2 mRNA accumulation, which peaked at 2-4 h and then decreased; there were later mRNA elevations at 48 and 96 h that were inhibited by indomethacin. In both MC3T3-E1 cells and neonatal calvariae, bFGF produced smaller and slower increases in PGHS-1 mRNA levels than for PGHS-2. bFGF stimulated bone resorption in mouse calvariae with a maximal increase of 80% at 1 nM. Stimulation was partially inhibited by nonsteroidal anti-inflammatory drugs. We conclude that bFGF rapidly stimulates PGE2 production in osteoblasts, largely through transcriptional regulation of PGHS-2, and that prostaglandins mediate some of bFGFs effects on bone resorption.

INTACT INSULIN-LIKE GROWTH FACTOR BINDING PROTEIN-5 (IGFBP-5) ASSOCIATES WITH BONE MATRIX AND THE SOLUBLE FRAGMENTS OF IGFBP-5 ACCUMULATED IN CULTURE MEDIUM OF NEONATAL MOUSE CALVARIAE BY PARATHYROID HORMONE AND PROSTAGLANDIN E2-TREATMENT

We examined the distribution of insulin‐like growth factor binding proteins (IGFBPs) in cultured neonatal mouse calvariae. IGFBP‐3 and ‐4 were predominantly found in the conditioned medium. IGFBP‐2 was partitioned between conditioned medium and bone and extracellular matrix (BECM), while intact (31‐kDa) IGFBP‐5 was most abundant in BECM extracts. After treatment with parathyroid hormone (PTH, 10−8 M) or prostaglandin E2 (PGE2, 10−6 M), immunoreactive IGFBP‐5 accumulated in the conditioned medium in a 21‐kDa form which did not bind IGF‐I on Western ligand blots. PTH and PGE2 did not alter the level of steady‐state IGFBP‐5 mRNA, nor markedly stimulate IGFBP‐5 synthesis in the calvariae, and thus accumulation of 21‐kDa IGFBP‐5 was largely due to release from BECM. This accumulation of truncated IGFBP‐5 in the conditioned medium was not dependent on osteoclastic bone resorption, since it was not blocked by calcitonin or a bisphosphonate which inhibited PTH‐ and PGE2‐stimulated 45Ca‐release. The conditioned medium from PTH‐ or PGE2‐treated cultures degraded recombinant human IGFBP‐5 into lower molecular weight fragments. Addition of IGF‐I at 10−8 M into the culture resulted in accumulation of native 31‐kDa IGFBP‐5. However, even in the presence of IGF‐I, the native IGFBP‐5 was degraded and the 21‐kDa product accumulated in the culture medium. These results suggested a possible proteolytic mechanism for 21‐kDa IGFBP‐5 accumulation, responsive to PTH and PGE2. Aprotinin, leupeptin, cystatin, and bestatin did not inhibit the effects of PTH and PGE2 in the cultures. The localization of IGFBP‐5 in BECM and its release and proteolysis induced by PTH and PGE2 could play a role in the local regulation of bone metabolism.

Immune Evasion and Recognition of the Syphilis Spirochete in Blood and Skin of Secondary Syphilis Patients: Two Immunologically Distinct Compartments

Background The clinical syndrome associated with secondary syphilis (SS) reflects the propensity of Treponema pallidum (Tp) to escape immune recognition while simultaneously inducing inflammation. Methods To better understand the duality of immune evasion and immune recognition in human syphilis, herein we used a combination of flow cytometry, immunohistochemistry (IHC), and transcriptional profiling to study the immune response in the blood and skin of 27 HIV(-) SS patients in relation to spirochetal burdens. Ex vivo opsonophagocytosis assays using human syphilitic sera (HSS) were performed to model spirochete-monocyte/macrophage interactions in vivo. Results Despite the presence of low-level spirochetemia, as well as immunophenotypic changes suggestive of monocyte activation, we did not detect systemic cytokine production. SS subjects had substantial decreases in circulating DCs and in IFNγ-producing and cytotoxic NK-cells, along with an emergent CD56−/CD16+ NK-cell subset in blood. Skin lesions, which had visible Tp by IHC and substantial amounts of Tp-DNA, had large numbers of macrophages (CD68+), a relative increase in CD8+ T-cells over CD4+ T-cells and were enriched for CD56+ NK-cells. Skin lesions contained transcripts for cytokines (IFN-γ, TNF-α), chemokines (CCL2, CXCL10), macrophage and DC activation markers (CD40, CD86), Fc-mediated phagocytosis receptors (FcγRI, FcγR3), IFN-β and effector molecules associated with CD8 and NK-cell cytotoxic responses. While HSS promoted uptake of Tp in conjunction with monocyte activation, most spirochetes were not internalized. Conclusions Our findings support the importance of macrophage driven opsonophagocytosis and cell mediated immunity in treponemal clearance, while suggesting that the balance between phagocytic uptake and evasion is influenced by the relative burdens of bacteria in blood and skin and the presence of Tp subpopulations with differential capacities for binding opsonic antibodies. They also bring to light the extent of the systemic innate and adaptive immunologic abnormalities that define the secondary stage of the disease, which in the skin of patients trends towards a T-cell cytolytic response.

A Functional Serotonin Transporter Gene Polymorphism and Depressive Effects Associated With Interferon-α Treatment

BACKGROUND Interferon-alpha (IFN-alpha) treatment frequently induces depression, potentially leading to early dose reductions or a shorter duration of treatment, which can adversely affect outcomes, including quality of life. OBJECTIVE Defining relevant risk factors for IFN-alpha-induced depression is essential in order to identify prophylactic treatment strategies. METHOD The authors examined whether a functional polymorphism (5-HTTLPR) in the gene encoding the serotonin transporter moderates IFN-alpha-induced depressive symptoms in 1,015 patients with chronic hepatitis C (CHC) receiving pegylated IFN-alpha and ribavirin. Depressive symptoms were assessed at baseline, 12 weeks, and 20 weeks of treatment. RESULTS Depression symptoms increased during antiviral treatment; 5-HTTLPR genotype moderated IFN-alpha-induced depression symptoms in both non-Hispanic Caucasians and Hispanic patients, although the opposite risk allele was associated with depression in the two populations. CONCLUSION 5-HTTLPR may moderate risk for the development of depressive symptoms during IFN-alpha therapy for CHC in a population-specific manner.

Lack of Association Between Androgen Receptor Polymorphisms and Bone Mineral Density or Physical Function in Older Men

Individuals whose androgen receptors have short polyglutamine tracts (resulting from CAG repeats) may have greater receptor signaling activity of the androgen receptor. We evaluated the association between bone mineral density (BMD) and CAG repeats in 91 older men with normal (control) and low femoral neck (FN) BMD (OP) or a history of femoral fracture (FX). Bioavailable testosterone (BioT) and physical performance, including composite score (EPESE) and physical activity (PASE), were also measured. Comparing FX, OP, and control subjects, we observed BMD T scores of 22.16 6 1.08, 22.26 6 0.74, and 20.20 6 0.40 (p < 0.001); CAG repeat lengths of 21.9 6 2.7, 22.5 6 2.4, and 22.3 6 2.9 (p = 0.63); BioT levels of 2.29 6 1.25, 2.19 6 1.11, and 3.99 6 1.25 nmol/L (p < 0.001); EPESE scores of 8.0 6 3.0, 9.7 6 2.0, and 11.3 6 0.9 (p < 0.001); and PASE scores of 91 6 66, 122 6 66, and 200 6 55 (p < 0.001), respectively. There were no significant correlations between CAG repeats and BioT or physical performance. Men with osteoporosis or fracture had lower BioT, physical performance, and physical activity than controls. This study found no association between CAG repeats and FN BMD in older men with normal or low BMD or FX.