Administration of Cyclooxygenase-2 Inhibitor Reduces Joint Inflammation but Exacerbates Osteopenia in IL-1α Transgenic Mice Due to GM-CSF Overproduction

Cytokines and Bone: Osteoimmunology

Cytokines and hematopoietic growth factors have traditionally been thought of as regulators of the development and function of immune and blood cells. However, an ever-expanding number of these factors have been discovered to have major effects on bone cells and the development of the skeleton in health and disease (Table 1). In addition, several cytokines have been directly linked to the development of osteoporosis in both animal models and in patients. In order to understand the mechanisms regulating bone cells and how this may be dysregulated in disease states, it is necessary to appreciate the diverse effects that cytokines and inflammation have on osteoblasts, osteoclasts, and bone mass. This chapter provides a broad overview of this topic with extensive references so that, if desired, readers can access specific references to delve into individual topics in greater detail.

The expression of matrix metalloproteinases and their inhibitors in corneal fibroblasts by alarmins from necrotic corneal epithelial cells

PURPOSE

Sterile ulceration is frequently observed in the cornea following persistent corneal epithelial damage. We examined the effect of alarmins released by necrotic corneal epithelial cells (HCE) on the production of matrix metalloproteinases (MMPs) and tissue inhibitors of metalloproteinases (TIMPs) by corneal fibroblasts.

METHODS

IL-1α and high-mobility group box 1 protein (HMGB1) released into the supernatant derived from necrotic HCE cells were measured with enzyme-linked immunosorbent assay (ELISA). MMPs and TIMPs produced by corneal fibroblasts, stimulated with the supernatant from necrotic HCE cells, were analyzed and measured with protein array and ELISA. To investigate dynamic expression of alarmins in the corneal epithelium, we used immunohistochemistry to observe the expression of human IL-1α in the corneal epithelium of human IL-1α Tg mice with or without cryopexy. We also investigated the expression of MMPs in corneal stroma of the mice treated with cryopexy, using RT-PCR.

RESULTS

We detected IL-1α and HMGB-1 in the supernatant of necrotic HCE cells. These supernatants increased the expression of MMP-3 and MMP-1, and decreased that of TIMP-1 and TIMP-2 in human corneal fibroblasts. Almost always these were inhibited by IL-1 receptor antagonist. Recombinant IL-1α increased the production MMP-3 and MMP-1 in corneal fibroblasts. After cryopexy of the epithelium of human IL-1α Tg mice, the expression of human IL-1α was recognized in the cytoplasm but not nucleus of epithelial cells. The level of MMP-3 and MMP-1 mRNAs was elevated in the corneal stroma in mice treated with cryopexy.

CONCLUSION

Alarmins, especially IL-1α, released from necrotic HCE cells may play an important role in the expression of MMPs and TIMPs by corneal fibroblast, resulting in sterile ulceration.

[Research progress of correlation between traumatic brain injury and fracture healing]

Objective

To review the current status and advances of the correlation between traumatic brain injury (TBI) and fracture healing.

Methods

The related domestic and abroad literature about the correlation between TBI and fracture healing was extensively reviewed and analyzed.

Results

There are a variety of studies on the correlation between TBI and fracture healing, which can be divided into two major aspects: revascularization and osteogenesis; the local and systemic changes of the neuropeptide and hormone after TBI.

Conclusion

TBI facilitates callus formation, the further research is needed to clarify the exact mechanism.

Host-targeted approaches to managing animal health: old problems and new tools

Our fellow medical and regulatory scientists question the animal producer's dependence on antibiotics and antimicrobial chemicals in the production of animal products. Retail distributors and consumers are putting even more pressure on the animal industry to find new ways to produce meat without antibiotics and chemicals. In addition, federal funding agencies are increasingly pressuring researchers to conduct science that has application. In the review that follows, we outline our approach to finding novel ways to improve animal performance and health. We use a strict set of guidelines in our applied research as follows: (1) Does the work have value to society? (2) Does our team have the skills to innovate in the field? (3) Is the product we produce commercially cost-effective? (4) Are there any reasons why the general consumer will reject the technology? (5) Is it safe for the animal, consumer, and the environment? Within this framework, we describe 4 areas of research that have produced useful products, areas that we hope other scientists will likewise explore and innovate such as (1) methods to detect infection in herds and flocks, (2) methods to control systemic and mucosal inflammation, (3) improvements to intestinal barrier function, and (4) methods to strategically potentiate immune defense. We recognize that others are working in these areas, using different strategies, but believe our examples will illustrate the vast opportunity for research and innovation in a world without antibiotics. Animal scientists have been given a new challenge that may help shape the future of both animal and human medicine.

The GM-CSF/IL-3/IL-5 cytokine receptor family: from ligand recognition to initiation of signaling

Granulocyte-macrophage colony-stimulating factor (GM-CSF), interleukin-3 (IL-3), and IL-5 are members of a discrete family of cytokines that regulates the growth, differentiation, migration and effector function activities of many hematopoietic cells and immunocytes. These cytokines are involved in normal responses to infectious agents, bridging innate and adaptive immunity. However, in certain cases, the overexpression of these cytokines or their receptors can lead to excessive or aberrant initiation of signaling resulting in pathological conditions, with chronic inflammatory diseases and myeloid leukemias the most notable examples. Recent crystal structures of the GM-CSF receptor ternary complex and the IL-5 binary complex have revealed new paradigms of cytokine receptor activation. Together with a wealth of associated structure-function studies, they have significantly enhanced our understanding of how these receptors recognize cytokines and initiate signals across cell membranes. Importantly, these structures provide opportunities for structure-based approaches for the discovery of novel and disease-specific therapeutics. In addition, recent biochemical evidence has suggested that the GM-CSF/IL-3/IL-5 receptor family is capable of interacting productively with other membrane proteins at the cell surface. Such interactions may afford additional or unique biological activities and might be harnessed for selective modulation of the function of these receptors in disease.

Arsenic trioxide affects bone remodeling by effects on osteoblast differentiation and function

Arsenic trioxide (ATO) is widely used in tumor treatment, but excessive arsenic exposure can have adverse health effects. This study was to examine the association between ATO treatment and bone remodeling. The effects of ATO on osteoblast function were investigated in primary cell cultures and in an in vivo study in rats. Sprague-Dawley rats (n=30) were randomly assigned to 3 groups which were injected intraperitoneally with saline or 5 or 10 mg/kg of ATO for 4 weeks. In cell culture, ATO decreased osteoblast mineralization by decreasing alkaline phosphatase (ALP) expression and this effect was prevented by co-addition of inorganic phosphate (Pi). Moreover, levels of mRNAs for the transcription factors runt-related transcription factor 2 (Runx2) and osterix, the osteoblast osteogenic gene osteocalcin, and the adherence molecule vascular cell adhesion molecule-1 (VCAM-1) were decreased by ATO. Levels of mRNAs for the cytokine IL-6 were also decreased, whereas GM-CSF mRNA levels were increased. Similar effects of ATO on osteoblasts were seen in in vivo experiments in the rat. Moreover, decreases of bone turnover markers of osteocalcin, Procollagen type I N-terminal propeptide (PINP), and C-terminal cross-linked telopeptide (CTX) as well as bone mineral density (BMD) and trabecular bone volume of femur were observed in ATO-treated rats. These results suggest that ATO interferes with bone remodeling mostly through changes in osteoblast differentiation and function.

Optical tomographic imaging discriminates between disease-modifying anti-rheumatic drug (DMARD) and non-DMARD efficacy in collagen antibody-induced arthritis

Introduction

Standard measurements used to assess murine models of rheumatoid arthritis, notably paw thickness and clinical score, do not align well with certain aspects of disease severity as assessed by histopathology. We tested the hypothesis that non-invasive optical tomographic imaging of molecular biomarkers of inflammation and bone turnover would provide a superior quantitative readout and would discriminate between a disease-modifying anti-rheumatic drug (DMARD) and a non-DMARD treatment.

Methods

Using two protease-activated near-infrared fluorescence imaging agents to detect inflammation-associated cathepsin and matrix metalloprotease activity, and a third agent to detect bone turnover, we quantified fluorescence in paws of mice with collagen antibody-induced arthritis. Fluorescence molecular tomographic (FMT) imaging results, which provided deep tissue detection and quantitative readouts in absolute picomoles of agent fluorescence per paw, were compared with paw swelling, clinical scores, a panel of plasma biomarkers, and histopathology to discriminate between steroid (prednisolone), DMARD (p38 mitogen-activated protein kinase (MAPK) inhibitor) and non-DMARD (celecoxib, cyclooxygenase-2 (COX-2) inhibitor) treatments.

Results

Paw thickness, clinical score, and plasma biomarkers failed to discriminate well between a p38 MAPK inhibitor and a COX-2 inhibitor. In contrast, FMT quantification using near-infrared agents to detect protease activity or bone resorption yielded a clear discrimination between the different classes of therapeutics. FMT results agreed well with inflammation scores, and both imaging and histopathology provided clearer discrimination between treatments as compared with paw swelling, clinical score, and serum biomarker readouts.

Conclusions

Non-invasive optical tomographic imaging offers a unique approach to monitoring disease pathogenesis and correlates with histopathology assessment of joint inflammation and bone resorption. The specific use of optical tomography allowed accurate three-dimensional imaging, quantitation in picomoles rather than intensity or relative fluorescence, and, for the first time, showed that non-invasive imaging assessment can predict the pathologist's histology inflammation scoring and discriminate DMARD from non-DMARD activity.

Effects of NSAIDs on Differentiation and Function of Human and Murine Osteoclasts - Crucial 'Human Osteoclastology'

Osteoclasts play a critical role in both normal bone metabolism and bone resorption in the joints of patients with rheumatoid arthritis. It has been reported that non-steroidal anti-inflammatory drugs (NSAIDs) inhibit murine osteoclastogenesis in vitro and murine arthritis models in vivo, but not the destruction of joints of patients with rheumatoid arthritis. In the current review article, we review the recent findings in the effect of NSAIDs on the formation and function of human and murine osteoclasts both in vitro and in vivo, underlining the importance of studies using human osteoclasts. Since 2009, we have suggested a novel term ‘human osteoclastology’.

Prostaglandins in bone: bad cop, good cop?

Prostaglandins (PGs) are multifunctional regulators of bone metabolism that stimulate both bone resorption and formation. PGs have been implicated in bone resorption associated with inflammation and metastatic bone disease, and also in bone formation associated with fracture healing and heterotopic ossification. Recent studies have identified roles for inducible cyclooxygenase (COX)-2 and PGE(2) receptors in these processes. Although the effects of PGs have been most often associated with cAMP production and protein kinase A activation, PGs can engage an extensive G-protein signaling network. Further analysis of COX-2 and PG receptors and their downstream G-protein signaling in bone could provide important clues to the regulation of skeletal cell growth in both health and disease.

Treatment with cyclooxygenase-2 inhibitors enables repeated administration of vaccinia virus for control of ovarian cancer

Metastatic ovarian cancer is the leading cause of death among women with gynecologic malignancies in the United States. The lack of effective treatment for patients with advanced ovarian cancer warrants development of innovative therapies. Cancer therapy using oncolytic viruses represents a promising new approach for controlling tumors. Vaccinia virus has been shown to preferentially infect tumor cells but not normal tissue. However, oncolytic therapy using recombinant viruses faces the limitation of viral clearance due to generation of neutralizing antibodies. In the current study, we found that cyclooxygenase-2 (Cox-2) inhibitors circumvented this limitation, enabling repeated administration of vaccinia virus without losing infectivity. We quantified the antivaccinia antibody response using enzyme-linked immunosorbent assay (ELISA) and neutralization assays to show that treatment of Cox-2 inhibitors inhibited the generation of neutralizing antibodies. Furthermore, we showed that combination treatment of Cox-2 inhibitors with vaccinia virus was more effective that either treatment alone in treating MOSEC/luc tumor-bearing mice. Thus, the combination of Cox-2 inhibitors and vaccinia virus represents a potential innovative approach to controlling ovarian tumors.

The granulocyte-macrophage colony-stimulating factor receptor: linking its structure to cell signaling and its role in disease

Already 20 years have passed since the cloning of the granulocyte-macrophage colony-stimulating factor (GM-CSF) receptor alpha-chain, the first member of the GM-CSF/interleukin (IL)-3/IL-5 family of hemopoietic cytokine receptors to be molecularly characterized. The intervening 2 decades have uncovered a plethora of biologic functions transduced by the GM-CSF receptor (pleiotropy) and revealed distinct signaling networks that couple the receptor to biologic outcomes. Unlike other hemopoietin receptors, the GM-CSF receptor has a significant nonredundant role in myeloid hematologic malignancies, macrophage-mediated acute and chronic inflammation, pulmonary homeostasis, and allergic disease. The molecular mechanisms underlying GM-CSF receptor activation have recently been revealed by the crystal structure of the GM-CSF receptor complexed to GM-CSF, which shows an unexpected higher order assembly. Emerging evidence also suggests the existence of intracellular signosomes that are recruited in a concentration-dependent fashion to selectively control cell survival, proliferation, and differentiation by GM-CSF. These findings begin to unravel the mystery of cytokine receptor pleiotropy and are likely to also apply to the related IL-3 and IL-5 receptors as well as other heterodimeric cytokine receptors. The new insights in GM-CSF receptor activation have clinical significance as the structural and signaling nuances can be harnessed for the development of new treatments for malignant and inflammatory diseases.

Colony-stimulating factors in inflammation and autoimmunity

Although they were originally defined as haematopoietic-cell growth factors, colony-stimulating factors (CSFs) have been shown to have additional functions by acting directly on mature myeloid cells. Recent data from animal models indicate that the depletion of CSFs has therapeutic benefit in many inflammatory and/or autoimmune conditions and as a result, early-phase clinical trials targeting granulocyte/macrophage colony-stimulating factor and macrophage colony-stimulating factor have now commenced. The distinct biological features of CSFs offer opportunities for specific targeting, but with some associated risks. Here, I describe these biological features, discuss the probable specific outcomes of targeting CSFs in vivo and highlight outstanding questions that need to be addressed.

Selective cyclooxygenase-2 inhibitor prevents reduction of trabecular bone mass in collagen-induced arthritic mice in association with suppression of RANKL/OPG ratio and IL-6 mRNA expression in synovial tissues but not in bone marrow cells

We performed this study to clarify whether celecoxib, a selective cyclooxygenase-2 (COX-2) inhibitor, prevents trabecular bone mass reduction by suppressing arthritis-related increase of bone resorption, and to discriminate differences in actions on bone among celecoxib, SC-58560 (a selective COX-1 inhibitor), and indomethacin. Eight-week-old DBA/1J male mice were divided into six groups as follows. Control untreated (Normal) and collagen-induced arthritic (CIA) mice were compared with four treatment groups: celecoxib was orally administered to CIA mice at doses of 0 (Vehicle), 16 (COX2L), and 75 (COX2H) mg/kg, in addition to two groups of mice treated with SC-58560 (COX1) or indomethacin (IND). Histomorphometry showed a significant decrease in tibial trabecular bone volume in arthritic mice, which was corrected by COX2H. The increased osteoclast surface and number in the Vehicle group were suppressed by COX2L, COX2H, and IND. The decreased bone formation rate in Vehicle was elevated by COX2H without statistical significance. A high ratio of mRNA expression of receptor activator of NF-kappaB ligand (RANKL)/osteoprotegerin (OPG) in Vehicle synovial tissue was suppressed by COX2L and COX2H. The increased expression of interleukin (IL)-6 mRNA in Vehicle was suppressed by COX2L, COX2H, and IND, although no difference in this expression was observed in bone marrow cells among all groups. In conclusion, in CIA mice, celecoxib suppresses arthritis-related increase in bone resorption at low and high doses and prevents trabecular bone mass reduction at high doses in association with suppression of osteoclast development in bone marrow through inhibition of RANKL/OPG ratio and IL-6 mRNA expression in inflammatory synovial tissue.