Multiple cytokines produced by immune cells induce remodeling and aid in maintaining bone homeostasis through differentiation of bone forming osteoblasts and bone resorbing osteoclasts. Here, we investigate bone remodeling controlled by the TNF superfamily cytokine LIGHT. LIGHT-deficient mice (Tnfsf14-/- ) exhibit spine deformity, and reduced femoral cancellous bone mass associated with an increase in the osteoclast number and a slight decrease of osteoblasts compared to WT mice. The effect of LIGHT in bone cells can be direct or indirect, mediated by both the low expression of the anti-osteoclastogenic osteoprotegerin (OPG) in B and T cells, and reduced levels of the pro-osteoblastogenic Wnt10b in CD8+ T cells in Tnfsf14-/- . LIGHT stimulation increases OPG levels in B, CD8+ T, and osteoblastic cells, as well as Wnt10b expression in CD8+ T cells. The high bone mass in Light and T and B cell deficient mice (Rag- /Tnfsf14- ) supports the cooperative role of the immune system in bone homeostasis. These results implicate LIGHT as a potential target in bone disease. This article is protected by copyright. All rights reserved.

It has been recently reported that, after physical activity, the skeletal muscle releases Irisin, the newly identified myokine able of driving transition of white adipocytes into brown. This result supported the role of skeletal muscle as endocrine organ, suggesting that it could target other tissues besides adipose tissue. In our previous work, we demonstrated that conditioned media collected from primary myoblasts of exercised mice were able to increase OB differentiation and this effect was Irisin-mediated. Here we show that Irisin has positive effect on cortical mineral density and geometry in vivo. Young male mice were injected with r-Irisin and cortical bone adaptation was analyzed by micro-CT at tibial midshaft. Our results show that cortical tissue mineral density is significantly increased in Irisin-injected mice compared to vehicle-injected littermates (+8,16%; p<0,02). Furthermore, this higher density of calcium hydroxyapatite at cortical site is accompanied by increase in periosteal circumference (+7,5%; p<0,03) and polar moment of Inertia (pMOI +19,21%; p<0,01). A greater pMOI indicates stronger resistance of a long bone to torsion and, together with higher bone mineral density, suggests higher protection against fracture. The effect of Irisin is fully comparable to the effect of physical activity that is widely accepted method for increasing bone mineral density and bone size in healthy populations. In view of further proving the involvement of Irisin in bone metabolism, we validate its direct effect on osteoblasts in vitro. Phosphorylation of the MAP kinase ERK and the expression of Atf4 were significantly increased after Irisin treatment, as well as ALP and pro-Collagen I mRNA expression. Our data highlight a novel link in muscle-fat-bone axis demonstrating that Irisin targets bone tissue directly. Based on this study, future investigation could satisfy the ongoing research of exercise-mimetic therapies with anabolic action on the skeleton.

It has been recently reported that, after physical exercise activity, the skeletal muscle releases Irisin, the newly identified myokine able of driving transition of white adipocytes into brown, following a phenomenon known as the browning response. This result suggested that skeletal muscle is crucial in the regulation of energy homeostasis, supporting its role as endocrine organ that targets adipose tissue by promoting energy expenditure. In accordance with this new finding, we demonstrated that conditioned media (CM) collected from primary myoblasts of exercised mice were able to induce osteoblast differentiation in a greater extent than those of mice housed in resting conditions and this effect is Irisin-mediated. In view of further proving the involvement of Irisin in bone metabolism, we validate its direct effect on osteoblasts by using r-Irisin. Here we show that phosphorylation of MAP kinase ERK and expression of Atf 4 (p<0,001), the key trascription factor of osteoblast differentiation, were significantly increased after Irisin treatment. Furthermore, ALP and pro-Collagen I mRNA resulted up regulated (p<0,001), as we already demonstrated by treating osteoblasts with conditioned medium from primary myoblasts of exercised mice. To recapitulate in vivo the effect of physical exercise, we injected mice with r-Irisin. Our results show that BV/TV of Irisin-treated mice was higher than vehicle-injected mice. In elderly, the severe decline of skeletal muscle function, known as Sarcopenia, is associated with impaired function of bone (Osteopenia) and these two simultaneous losses of function lead to increased risk of bone fractures. In order to reveal new strategies for treatment of sarcopenia and osteopenia, we also analyzed the effect of physical activity in old mice. Our findings demonstrate that mRNA levels of the most relevant bone proteins resulted up regulated in ex-vivo osteoblast obtained from exercised old mice compared with mice kept in resting conditions. Our data highlight a novel link in muscle-fat-bone axis demonstrating that Irisin targets bone tissue directly. Future perspectives, based on these studies, could satisfy the ongoing research of exercise-mimetic therapies with anabolic action on the skeleton

Medication-related osteonecrosis of the jaw (MRONJ) is a well-recognized severe complication of bisphosphonate (BPs) treatment in patients with osteoporosis or metastatic cancer. Microbiological infection has been hypothesized as a contributing factor to bisphosphonate related osteonecrosis of the jaw (BRONJ). Despite infection being present in BRONJ patients, there is no clear data as to whether infection plays a role in the pathophysiology. Moreover, microbial cultures have not been helpful in directing therapy because specific pathogens have not been identified. The objective of this study was to determine the bacterial colonization of jawbone and identify the bacterial phylotypes associated with BRONJ. Twenty oncologic patients, aged 48-87 years (average age 70.65 ± 8.86 years) with BRONJ were enrolled in this study and underwent three different microbiological samplings. Overall, 60 samples were obtained from oral mucosa, necrotic bone fragments and fistula drainage. The same procedure was performed for the laboratory culture of all these specimens. No significant differences regarding either gram+ and gram– species (Chi-squared= 0.1642; p = 0.6854) or aerobes and anaerobes bacteria (Chi-squared= 3.084; p = 0.0791) were found. Compared to other sampling techniques, the oral swab allowed to obtain valuable microbial data in order to recognize pathogens responsible for the infection and to outline a focused antimicrobial therapy.

Background: Stem cells are defined as clonogenic cells capable of self-renewal and multi-lineage differentiation. A population of these cells has been identified in human Dental Follicle (DF). Dental Follicle Stem Cells (DFSCs) were found in pediatric unerupted wisdom teeth and have been shown to differentiate, under particular conditions, into various cell types of the mesenchymal tissues. Aim: The aim of this study was to investigate if cells isolated from DF show stem features, differentiate toward osteoblastic phenotype and express osteoblastic markers. Methods: We studied the immunophenotype of DFSCs by flow cytometric analysis, the osteoblastic markers of differentiated DFSCs were assayed by histochemical methods and real-time PCR. Results: We demonstrated that DFSCs expressed a heterogeneous assortment of makers associated with stemness. Moreover DFSCs differentiated into osteoblast-like cells, producing mineralized matrix nodules and expressed the typical osteoblastic markers, Alkaline Phosphatase (ALP) and Collagen I (Coll I). Conclusion: This study suggests that DFSCs may provide a cell source for tissue engineering of bone.

The objective of this study was to assess frequency and extension of the defects affecting the dentin-post interface after using different combinations of irrigants and sealers. The experimental work was conducted on single-rooted teeth extracted for orthodontic reasons. The specimens were divided into different groups, according to irrigant and endodontic cement utilized, and endodontically instrumented. After fiberglass posts cementation, cross sections were obtained at apical, middle and coronal level of the root and submitted to quantitative analyses. Different types of defects were found: bubbles, bonding defects, polymerization defect, and cement residues. The percent extension of each defect and its frequency were related to the specific irrigant/sealer combination and to the root level. Detachments of the material from dentin were found only at apical and middle levels. Chlorhexidine digluconate seems to have more beneficial effects if compared to sodium hypochlorite: samples prepared with chlorhexidine digluconate showed a higher performance, with roots including null to few defects. In detail, samples treated with chlorhexidine digluconate and Pulp Canal Sealer showed the lowest frequency and the smallest dimension of defects.

The purpose of this case series was to describe the historical, clinical, radiographic details, outcome and histhopathological findings of 2 cases of NSH in pony. CASE 1 A 3 years old, male pony was referred in 2003 for severe dyspnoea and deformity of the bones of the skull. At clinical examination, the pony had general fatigue, severe dyspnea and inspiratory breath sounds. X‐ray examination showed signs of severe thinning of the cranial bones with loss of definition of the plot medullary and cortical thinning cancellous bone. The results of parathyroid hormone by radioimmunological showed an increase in the values of PTH .Treatment has been provided using tiludronate (TILDREN 1mg/kg‐ ®‐Ceva Vetem SpA, Milan). The patient's clinical condition showed significant improvements, the clinical symptoms (inability to maintain the station, lameness and respiratory sounds) had resolved. The pony was dismissed. CASE 2 In October of 2012 was referred a 5 years old Shetland male pony, and the owners permanent recumbency since 3 days.General clinical examination showed persistent recumbency , slight enlargement of facial bones and pain at flexion of hindlimbs. Based on the clinical symptoms, X‐rays and laboratory tests, the diagnosis was of NSH related to fibrous osteodystrophy. The clinical condition of the horse showed no improvement and the subject was not able to take quadrupedal station. The owner disagrees with Tiludronate therapy and pony was euthanized, and some bone samples were harvested in order to deepen the diagnostic picture. Microradioghaphs of frontal serial sections show modifications of bone tissue arrangement and mineralization.. The trabecular network appears rarefied owing to a thinning of the trabeculae or their total erosion. Both spongy and compact bone frequently exhibit large osteocytic lacunae. On the other hand new bone, less mineralized, is exthensively present. The deposition fronts show a wide osteoid with voluminous osteoblast, but sometimes exhibit numerous preosteoblasts with a fibroblasts morphology. In many area, fibrous connective tissue covers the trabecular surfaces and replaces part of the marrow reticular stroma. The appearance of micro X‐ray, never described in the horse, and the histological evidence and confirm the diagnosis of fibrous osteodystrophy. Bisphosphonate therapy is a therapeutic option, and it is valid for the possible remission of clinical symptoms but not certain deformities of the disease. The association of such therapy with a balanced diet can be part of the treatment protocol in the course of NSH of dietary origin. David et all., the bisposphonate Tiludronate is a potent inhibitor of the osteoclast vacuola hatpase, Journal of Bone and Mineral Research, 11, 1498‐1507, 1996 Estepa, J. C., Aguilera‐Tejero, E., Mayer‐Valor, R., Almeden, Y., Felsenfeld, A.J. & Rodriguez, M. Measured of parathyroid hormone in horses. Equine Veterinary Journal 30, 476‐481, 1998

Psoriasis is a chronic, remitting and relapsing inflammatory disorder, involving the skin, nails, scalp and mucous membranes, that impairs patients' quality of life to varying degrees. Psoriatic arthritis is a chronic seronegative, inflammatory arthritis, usually preceded by psoriasis. Temporomandibular disorders is a generic term referred to clinical conditions involving the jaw muscles and temporomandibular joint. The aim of this study was to assess symptoms and signs of temporomandibular disorders in psoriasis patients with and without psoriatic arthritis.

LIGHT (TNFSF14), expressed by different cells of the immune system, binds two trans-membrane receptors: HVEM and LTβR. It is over-expressed in erosive rheumatoid arthritis and lytic myeloma-bone disease and controversial data have been published on its role osteoclast (OC) formation in vitro. Here, we investigated the role of LIGHT on in vitro murine osteoclastogenesis model and bone phenotype in LIGHT−/− mice. Firstly, we showed that murine macrophages stimulated with LIGHT alone did not differentiate into OCs. Consistently, the addition of agonist anti-HVEM and anti-LTβR antibodies did not affect osteoclastogenesis in the same cultures. Interestingly, the presence of LIGHT and sub-optimal RANKL concentration displayed synergic effects on OC formation through the early and sustained activation of Akt, NFκB and JNK pathways. Secondly, by microCT we found that the femurs of LIGHT−/− mice exhibited a 30% (P<0.01) decrease in trabecular BV/TV due to a significant reduction in trabecular thickness and number as well as the increase in trabecular spaces respect to WT mice. Furthermore, a fivefold increase of OC number/bone surface was found in femora from KO mice compared to WT (P<0.004). To investigate the possible molecular mechanism/s responsible for this bone phenotype in LIGHT−/− mice we studied OPG levels in whole bone marrow (BM) extracts from the femurs of these mice and demonstrated a significant reduction in OPG mRNA transcript respect to WT (fourfold, P<0.001). Further investigations showed that BM CD8+ T cells and B cell subpopulations from KO mice expressed lower levels of OPG compared to those from WT mice. Consistently, LIGHT treatment in a dose dependent manner increase OPG expression in BM CD8+ T cells and B-cells. In conclusion, our results identified LIGHT as a new important modulator of bone remodeling and highlighted a new modulator of OPG expression.