Emma Persson

IL-6, Leukemia Inhibitory Factor, and Oncostatin M Stimulate Bone Resorption and Regulate the Expression of Receptor Activator of NF-κB Ligand, Osteoprotegerin, and Receptor Activator of NF-κB in Mouse Calvariae

IL-6, leukemia inhibitory factor (LIF), and oncostatin M (OSM) are IL-6-type cytokines that stimulate osteoclast formation and function. In the present study, the resorptive effects of these agents and their regulation of receptor activator of NF-κB ligand (RANKL), RANK, and osteoprotegerin (OPG) were studied in neonatal mouse calvaria. When tested separately, neither human (h) IL-6 nor the human soluble IL-6R (shIL-6R) stimulated bone resorption, but when hIL-6 and the shIL-6R were combined, significant stimulation of both mineral and matrix release from bone explants was noted. Semiquantitative RT-PCR showed that hIL-6 plus shIL-6R enhanced the expression of RANKL and OPG in calvarial bones, but decreased RANK expression. Human LIF, hOSM, and mouse OSM (mOSM) also stimulated 45Ca release and enhanced the mRNA expression of RANKL and OPG in mouse calvaria, but had no effect on the expression of RANK. In agreement with the RT-PCR analyses, ELISA measurements showed that both hIL-6 plus shIL-6R and mOSM increased RANKL and OPG proteins. 1,25-Dihydroxyvitamin D3 (D3) also increased the RANKL protein level, but decreased the protein level of OPG. OPG inhibited 45Ca release stimulated by RANKL, hIL-6 plus shIL-6R, hLIF, hOSM, mOSM, and D3. An Ab neutralizing mouse gp130 inhibited 45Ca release induced by hIL-6 plus shIL-6R. These experiments demonstrated stimulation of calvarial bone resorption and regulation of mRNA and protein expression of RANKL and OPG by D3 and IL-6 family cytokines as well as regulation of RANK expression in preosteoclasts/osteoclasts of mouse calvaria by D3 and hIL-6 plus shIL-6R.

Lack of selectivity of URB602 for 2-oleoylglycerol compared to anandamide hydrolysis in vitro.

Two compounds, URB602 and URB754, have been reported in the literature to be selective inhibitors of monoacylglycerol lipase, although a recent study has questioned their ability to prevent 2‐arachidonoyl hydrolysis by brain homogenates and cerebellar membranes. In the present study, the ability of these compounds to inhibit monoacylglycerol lipase and fatty acid amide hydrolase has been reinvestigated.

Inhibition of Hormone and Cytokine-stimulated Osteoclastogenesis and Bone Resorption by Interleukin-4 and Interleukin-13 Is Associated with Increased Osteoprotegerin and Decreased RANKL and RANK in a STAT6-dependent Pathway

Interleukin (IL)-4 and IL-13 are cytokines that inhibit bone resorption. Data showing an inhibitory effect of IL-4 and IL-13 on RANK mRNA in mouse calvariae were first reported at the 22nd American Society for Bone and Mineral Research Meeting (Lerner, U.H., and Conaway, H. H. 2000) J. Bone Min. Res. 15, Suppl. 1, Abstr. SU 230). In the present study, release of 45Ca from cultured mouse calvarial bones stimulated by different cytokines, peptides, and steroid hormones was inhibited by IL-4 and IL-13. IL-4 and IL-13 decreased receptor activator of nuclear factor-κB ligand (RANKL) and RANK mRNA and increased osteoprotegerin (OPG) mRNA in calvariae. Additionally, the cytokines decreased RANKL protein and increased OPG protein in calvarial bones. In osteoblasts isolated from calvariae, both an increase in RANKL mRNA and a decrease in OPG mRNA and protein elicited by vitamin D3 were reversed by IL-4 and IL-13. IL-4 and IL-13 decreased the number of tartrate-resistant acid phosphatase positive multinucleated cells and the mRNA expression of calcitonin receptor, tartrate-resistant acid phosphatase, and cathepsin K in mouse spleen cells and bone marrow macrophages (BMM) treated with macrophage colony-stimulating factor and RANKL. Inhibition of mRNA for RANK and the transcription factor NFAT2 was also noted in spleen cell and BMM cultures treated with IL-4 and IL-13. In addition, RANK mRNA and RANK protein were decreased by IL-4 and IL-13 in RAW 264.7 cells. Osteoblasts, spleen cells, and BMM expressed mRNA for the four proteins making up the IL-4 and IL-13 receptors. No effects by IL-4 on bone resorption and osteoclast formation or on RANKL and RANK mRNA expression were seen in Stat6–/– mice. The data indicate that IL-4 and IL-13, via a STAT6-dependent pathway, inhibit osteoclast differentiation and bone resorption by activating receptors on osteoblasts and osteoclasts that affect the RANKL/RANK/OPG system.

Death receptor ligation or exposure to perforin trigger rapid egress of the intracellular parasite Toxoplasma gondii.

The obligate intracellular parasite Toxoplasma gondii chronically infects up to one-third of the global population, can result in severe disease in immunocompromised individuals, and can be teratogenic. In this study, we demonstrate that death receptor ligation in T. gondii-infected cells leads to rapid egress of infectious parasites and lytic necrosis of the host cell, an active process mediated through the release of intracellular calcium as a consequence of caspase activation early in the apoptotic cascade. Upon acting on infected cells via death receptor- or perforin-dependent pathways, T cells induce rapid egress of infectious parasites able to infect surrounding cells, including the Ag-specific effector cells.

Fatty Acid Amide Hydrolase in Prostate Cancer: Association with Disease Severity and Outcome, CB1 Receptor Expression and Regulation by IL-4

Background Recent data have indicated that there may be a dysregulation of endocannabinoid metabolism in cancer. Here we have investigated the expression of the endocannabinoid metabolising enzyme fatty acid amide hydrolase (FAAH) in a well characterised tissue microarray from patients diagnosed with prostate cancer at transurethral resection for voiding problems. Methodology/Principal Findings FAAH immunoreactivity (FAAH-IR) was assessed in formalin-fixed paraffin-embedded non-malignant and tumour cores from 412 patients with prostate cancer. CB1 receptor immunoreactivity (CB1IR) scores were available for this dataset. FAAH-IR was seen in epithelial cells and blood vessel walls but not in the stroma. Tumour epithelial FAAH-IR was positively correlated with the disease severity at diagnosis (Gleason score, tumour stage, % of the specimen that contained tumour) for cases with mid-range CB1IR scores, but not for those with high CB1IR scores. For the 281 cases who only received palliative therapy at the end stages of the disease, a high tumour epithelial FAAH-IR was associated with a poor disease-specific survival. Multivariate Cox proportional-hazards regression analyses indicated that FAAH-IR gave additional prognostic information to that provided by CB1IR when a midrange, but not a high CB1IR cutoff value was used. Interleukin-4 (IL-4) receptor IR was found on tumour epithelial cells and incubation of prostate cancer PC-3 and R3327 AT1 cells with IL-4 increased their FAAH activity. Conclusions/Significance Tumour epithelial FAAH-IR is associated with prostate cancer severity and outcome at mid-range, but not high, CB1IR scores. The correlation with CB1IR in the tumour tissue may be related to a common local dysregulation by a component of the tumour microenvironment.

Kinin B1 and B2 receptor expression in osteoblasts and fibroblasts is enhanced by interleukin-1 and tumour necrosis factor-α. Effects dependent on activation of NF-κB and MAP kinases

Pro-inflammatory mediators formed by the kallikrein-kinin system can stimulate bone resorption and synergistically potentiate bone resorption induced by IL-1 and TNF-alpha. We have shown that the effect is associated with synergistically enhanced RANKL expression and enhanced prostaglandin biosynthesis, due to increased cyclooxygenase-2 expression. In the present study, the effects of osteotropic cytokines and different kinins on the expression of receptor subtypes for bradykinin (BK), des-Arg10-Lys-BK (DALBK), IL-1beta and TNF-alpha have been investigated. IL-1beta and TNF-alpha enhanced kinin B1 and B2 receptor binding in the human osteoblastic cell line MG-63 and the mRNA expression of B1 and B2 receptors in MG-63 cells, human gingival fibroblasts and intact mouse calvarial bones. Kinins did not affect mRNA expression of IL-1 or TNF receptors. EMSA showed that IL-1beta and TNF-alpha activated NF-kappaB and AP-1 in MG-63 cells. IL-1beta stimulated NF-kappaB via a non-canonical pathway (p52/p65) and TNF-alpha via the canonical pathway (p50/p65). Activation of AP-1 involved c-Jun in both IL-1beta and TNF-alpha stimulated cells, but c-Fos only in TNF-alpha stimulated cells. Phospho-ELISA and Western blots showed that IL-1beta activated JNK and p38, but not ERK 1/2 MAP kinase. Pharmacological inhibitors showed that NF-kappaB, p38 and JNK were important for IL-1beta induced stimulation of B1 receptors, and NF-kappaB and p38 for B2 receptors. p38 and JNK were important for TNF-alpha induced stimulation of B1 receptors, whereas NF-kappaB, p38 and JNK were involved in TNF-alpha induced expression of B2 receptors. These data show that IL-1beta and TNF-alpha upregulate B1 and B2 receptor expression by mechanisms involving activation of both NF-kappaB and MAP kinase pathways, but that signal transduction pathways are different for IL-1beta and TNF-alpha. The enhanced kinin receptor expression induced by the pro-inflammatory cytokines IL-1beta and TNF-alpha might be one important mechanism involved in the synergistic enhancement of prostaglandin formation caused by co-treatment with kinins and one of the two cytokines. These mechanisms might help to explain the enhanced bone resorption associated with inflammatory disorders, including periodontitis and rheumatoid arthritis.

Retinoids inhibit differentiation of hematopoetic osteoclast progenitors

Whether vitamin A promotes skeletal fragility, has no effect on fracture rate, or protects against bone loss is unclear. In the present study, effects of retinoids on osteoclast differentiation in cultured mouse bone marrow cells (BMCs), bone marrow macrophages (BMMs), spleen cells, and RAW264.7 cells were evaluated by analyzing osteoclast formation and expression of genes important in signal transduction and osteoclast function. All‐irans‐retinoic acid (ATRA) did not stimulate osteoclastogenesis in BMCs, but inhibited hormone and RANKL‐induced gene expression and formation of osteoclasts. In BMMs, spleen cells, and RAW264.7 cells, osteoclast differentiation and formation stimulated by M‐CSF/RANKL were inhibited (IC50 = 0.3 nM) by ATRA The effect was exerted at an early step of RANKL‐induced differentiation. ATRA also abolished increases of the transcription factors c‐Fos and NFAT2 stimulated by RANKL and suppressed down‐regulation of the antiosteoclastogenic transcription factor MafB. By comparing effects of several compounds structurally related to ATRA, as well as by using receptor antagonists, evaluation pointed to inhibition being mediated by RARα, with no involvement of PPARβ/δ. The results suggest that activation of RARα by retinoids in myeloid hematopoietic precursor cells decreases osteoclast formation by altering expression of the transcription factors c‐Fos, NFAT2, and MafB.—Conaway, H. H., Persson, E., Halen, M., Granholm, S., Svensson, O., Pettersson, U., Lie, A., Lerner, U. H. Retinoids inhibit differentiation of hematopoetic osteoclast progenitors. FASEB J. 23, 3526–3538 (2009). www.fasebj.org

Targeting the Endocannabinoid System for the Treatment of Cancer – A Practical View

In recent years, considerable interest has been generated by findings that cannabinoids not only have useful palliative effects, but also can affect the viability and invasivity of a variety of different cancer cells. In the present review, the potential of targeting the cannabinoid system for the treatment of cancer is considered from a practical, rather than a mechanistic viewpoint, addressing questions such as whether human tumour cells express CB receptors; whether the potencies of action of cannabinoids in vitro match the potencies expected on the base of receptor theory; what is known about the in vivo effects of cannabinoids and cancer, and how relevant the experiments undertaken are to the clinical situation; and finally, what approaches can be taken to minimise unwanted effects of cannabinoid treatment. It is concluded that cannabinoids (or agents modulating the endogenous cannabinoid system) are an attractive target for drug development in the cancer area, but that more in vivo studies, particularly those investigating the potential of cannabinoids as an addition to current treatment strategies, are needed.

Kinins and Neuro-osteogenic Factors

Publisher Summary This chapter reviews the effects of kinins on bone and the neuronal influence on bone tissue, as well as the interactions among kinins, neuro-osteogenic factors, and cytokines, on bone metabolism. Kinins are blood-derived short peptides released from kininogens due to the enzymatic action of kallikreins, which are proteolytic enzymes present in most tissues and body fluids. The biological effects of the kallikrein-kinin system are mainly exerted by bradykinin (BK) and kallidin (Lys-BK) acting on a variety of cells via cell surface receptors of the B2 subtype. In addition, BK and kallidin, without the carboxy-terminal arginine residue can exert effects via BK B 1 receptors. Activation of the plasma kallikrein system is initiated by the Hageman factor, a single chain globulin of molecular weight 80,000, which can be activated by exposure to an activating macromolecular anionic surface and by endotoxin, as well as by an autocatalytic mechanism. Plasma prekallikrein is a single chain globulin encoded by a single gene and is synthesized and secreted by hepatocytes as an inactive proenzyme. Activated plasma kallikrein acts on high molecular weight (HMW) kininogen at two sites, Lys-Arg and Arg-Ser, to release B K, a peptide consisting of nine amino acids with arginine at both the amino and the carboxy-terminal ends. The possibility that kinins may interact with cytokines is supported by the findings that B K can stimulate IL-1 and TNF production in murine macrophages. The capacity of BK to affect cytokine production has also been demonstrated in human gingival fibroblasts where BK does not affect IL-1 production, but potentiates the stimulatory effect of TNF on the biosynthesis of IL-1α and IL-1β.

Retinoids Stimulate Periosteal Bone Resorption by Enhancing the Protein RANKL, a Response Inhibited by Monomeric Glucocorticoid Receptor

Increased vitamin A (retinol) intake has been suggested to increase bone fragility. In the present study, we investigated effects of retinoids on bone resorption in cultured neonatal mouse calvarial bones and their interaction with glucocorticoids (GC). All-trans-retinoic acid (ATRA), retinol, retinalaldehyde, and 9-cis-retinoic acid stimulated release of 45Ca from calvarial bones. The resorptive effect of ATRA was characterized by mRNA expression of genes associated with osteoclast differentiation, enhanced osteoclast number, and bone matrix degradation. In addition, the RANKL/OPG ratio was increased by ATRA, release of 45Ca stimulated by ATRA was blocked by exogenous OPG, and mRNA expression of genes associated with bone formation was decreased by ATRA. All retinoid acid receptors (RARα/β/γ) were expressed in calvarial bones. Agonists with affinity to all receptor subtypes or specifically to RARα enhanced the release of 45Ca and mRNA expression of Rankl, whereas agonists with affinity to RARβ/γ or RARγ had no effects. Stimulation of Rankl mRNA by ATRA was competitively inhibited by the RARα antagonist GR110. Exposure of calvarial bones to GC inhibited the stimulatory effects of ATRA on 45Ca release and Rankl mRNA and protein expression. This inhibitory effect was reversed by the glucocorticoid receptor (GR) antagonist RU 486. Increased Rankl mRNA stimulated by ATRA was also blocked by GC in calvarial bones from mice with a GR mutation that blocks dimerization (GRdim mice). The data suggest that ATRA enhances periosteal bone resorption by increasing the RANKL/OPG ratio via RARα receptors, a response that can be inhibited by monomeric GR.