Baicalin inhibits apoptosis and enhances chondrocyte proliferation in thiram-induced tibial dyschondroplasia in chickens by regulating Bcl-2/Caspase-9 and Sox-9/Collagen-II expressions

Avian tibial dyschondroplasia (TD) is a skeletal disease affecting fast growing chickens, resulting in non-mineralized avascular cartilage. This metabolic disorder is characterized by lameness and reduced growth performance causing economic losses. The aim of this study was to investigate the protective effects of baicalin against TD caused by thiram exposure. A total of two hundred and forty (n = 240) one day-old broiler chickens were uniformly and randomly allocated into three different groups (n = 80) viz. control, TD, and baicalin groups. All chickens received standard feed, however, to induce TD, the TD and baicalin groups received thiram (tetramethylthiuram disulfide) at a rate of 50 mg/kg feed from days 4-7. The thiram induction in TD and baicalin groups resulted in lameness, high mortality, and enlarged growth-plate, poor production performance, reduction in ALP, GSH-Px, SOD, and T-AOC levels, and increased AST and ALT, and MDA levels. Furthermore, histopathological results showed less vascularization, and mRNA and protein expression levels of Sox-9, Col-II, and Bcl-2 showed significant downward trend, while caspase-9 displayed significant up-regulation in TD-affected chickens. After the TD induction, the baicalin group was orally administered with baicalin at a rate of 200 mg/kg from days 8-18. Baicalin administration increased the vascularization, and chondrocytes with intact nuclei, alleviated lameness, decreased GP size, increased productive capacity, and restored the liver antioxidant enzymes and serum biochemical levels. Furthermore, baicalin significantly up-regulated the gene and protein expressions of Sox-9, Col-II, and Bcl-2, and significantly down-regulated the expression of caspase-9 (p < 0.05). Therefore, the obtained results suggest that baicalin could be a possible choice in thiram toxicity alleviation by regulating apoptosis and chondrocyte proliferation in thiram-induced tibial dyschondroplasia.

Mmp2 Deficiency Leads to Defective Parturition and High Dystocia Rates in Mice

Parturition is the final and essential step for mammalian reproduction. While the uterus is quiescent during pregnancy, fundamental changes arise in the myometrial contractility, inducing fetal expulsion. Extracellular matrix (ECM) remodeling is fundamental for these events. The gelatinases subgroup of matrix metalloproteinases (MMPs), MMP2 and MMP9, participate in uterine ECM remodeling throughout pregnancy and parturition. However, their loss-of-function effect is unknown. Here, we determined the result of eliminating Mmp2 and/or Mmp9 on parturition in vivo, using single- and double-knockout (dKO) mice. The dystocia rates were measured in each genotype, and uterine tissue was collected from nulliparous synchronized females at the ages of 2, 4, 9 and 12 months. Very high percentages of dystocia (40-55%) were found in the Mmp2-/- and dKO females, contrary to the Mmp9-/- and wild-type females. The histological analysis of the uterus and cervix revealed that Mmp2-/- tissues undergo marked structural alterations, including highly enlarged myometrial, endometrial and luminal cavity. Increased collagen deposition was also demonstrated, suggesting a mechanism of extensive fibrosis in the Mmp2-/- myometrium, which may result in dystocia. Overall, this study describes a new role for MMP2 in myometrium remodeling during mammalian parturition process, highlighting a novel cause for dystocia due to a loss in MMP2 activity in the uterine tissue.

Effects of cold stress on growth performance, carcass traits and tibia attributes in broiler chickens with thiram-induced dyschondroplasia

The objective of this study was to investigate the effect of cold stress (CS) on growth performance and tibia attributes in broiler chickens with thiram-induced dyschondroplasia (TD). Four hundred 10-day-old male broilers were randomly allocated into four groups including, NT0: normal temperature (NT) without thiram; NT50: NT + thiram; CS0: CS without thiram; and CS50: CS + thiram in a completely randomised. The birds in CS groups were placed at a constant temperature of 15 ± 1°C during 11-20 days. Thiram (50 mg/kg) was added to the diet during 11-14 days to induce TD. Results showed that main effects of CS and thiram significantly decreased body weight and daily weight gain during 11-42 days (p < 0.05). Feed intake in the thiram50 group was significantly lower than the group thiram0 during 25-42 days (p < 0.05). Feed conversion ratio in CS birds was significantly more than NT group during 25-42 days (p < 0.05). On day 16, tibia width (TW) and TW to tibia length (TL) ratio were significantly higher in CS chicks compared to the NT group. TW was significantly higher in thiram50 group than thiram0 group (p < 0.05). On day 19, TL in CS chicks was significantly shorter than NT (p < 0.05). On day 23, growth plate width (GPW) in thiram50 group was significantly higher than thiram0 birds. In general, thiram increased tibial GPW and CS decreased TD severity as well as decreased growth performance in broilers.

Enhanced Extracellular Matrix Degradation in Growth Plate Contributes to Manganese Deficiency-Induced Tibial Dyschondroplasia in Broiler Chicks

Manganese (Mn) is a crucial trace element for poultry nutrition, and its deficiency compromises tibial cartilage development, leading to perosis and a higher incidence of slipped tendon. Tibial dyschondroplasia (TD) is a metabolic cartilage disease characterized by disruption of endochondral bone formation, which is closely related to extracellular matrix (ECM) degradation, in which Mn deficiency plays an important role. Previous studies have confirmed the role of matrix metalloproteinases (MMPs) in the pathogenesis of TD, but whether dysregulated ECM degradation and MMP expression profiles in growth plate are involved in Mn deficiency-induced avian TD has not been fully elucidated yet. Thus, this study was conducted to clarify these issues. Firstly, we successfully established TD model induced by Mn deficiency in broiler chicks. Mn deficiency decreased the number of chondrocytes, contents of proteoglycan, and type II collagen in tibial growth plate, demonstrating the tibial growth plate damage with enhanced ECM degradation. Also, Mn deficiency inhibited the Nrf2 signaling pathway and enhanced the protein levels of NLRP3, active caspase-1, and active IL-1β in tibial growth plate, indicating the oxidative stress and inflammatory response in Mn deficiency-induced TD. Additionally, upregulated expression levels of MMPs (MMP1, 9, and 13) were observed in tibial growth plate of Mn deficiency group. In summary, these findings suggest that Mn deficiency-enhanced ECM degradation is involved in avian TD, which may be correlated with oxidative stress, inflammatory response, and upregulation of MMPs.

Effect of BMP6 on the proliferation and apoptosis of chicken chondrocytes induced by thiram

The development of skeleton system is a complex biological process and be regulated by many transcription factors. Previous studies have shown that BMP6 is involved in skeleton development and other cells transforming to chondrocytes, but it is still not known whether do something to tibial dyschondroplasia (TD) broilers chondrocytes. In this study, RT-PCR revealed that the expression level of BMP6 in TD broiler chondrocytes at 7 days age was significantly decreased compared with normal group (P < 0.05). CCK-8 and EdU assay showed that the proliferation of cells transfected with interference BMP6 was significantly decreased compared with control siRNA, while cell proliferation was significantly increased after overexpression of BMP6. Meanwhile, the proportion of G0/G1 phase cells was significantly increased and the proportion of G2/M phase cells was significantly decreased after interference of BMP6 for 48 h in TD chicken chondrocytes (P < 0.05). In addition, flow cytometry analysis exhibited that interference BMP6 significantly increased apoptosis rate and necrotizing rate of cells. In conclusion, these results suggest that BMP6 plays a positive role in the growth and development of TD broiler chondrocytes. Our findings reveal a new target for TD prevention in broiler chickens.

Treatment of tibial dyschondroplasia with traditional Chinese medicines: "Lesson and future directions"

Tibial dyschondroplasia (TD) is a metabolic tibiotarsal bone disease in rapidly growing birds throughout the world, which is characterized by gait disorders, reduced growth, and in an unrecoverable lameness in many cases. The short production cycle in chickens, long metabolism cycle in most of the drugs with the severe drug residue, and high treatment cost severely restrict the enthusiasm for the treatment of TD. Traditional Chinese medicine (TCM) has been used for the prevention, treatment, and cure of avian bone diseases. Previously, a couple of traditional Chinese medicines has been reported being useful in treating TD. This review will discuss the TCM used in TD and the alternative TCM to treat TD. Selecting a TCM approach and its pharmacologic effects on TD chickens mainly focused on the differentiation, proliferation, and apoptosis of chondrocytes, angiogenesis, matrix metabolism, oxidative damage, cytokines, and calcification of cartilage in tibia.

Conserved role of matrix metalloproteases 2 and 9 in promoting the migration of neural crest cells in avian and mammalian embryos

Neural crest cells (NCCs) are a unique embryonic cell population that initially reside at the dorsal neural tube but later migrate in the embryo and differentiate into multiple types of derivatives. To acquire motility, NCCs undergo epithelial-to-mesenchymal transition and invade the surrounding extracellular matrix (ECM). Matrix metalloproteases (MMPs) are a large family of proteases which regulate migration of various embryonic and adult cells via ECM remodeling. The gelatinase's subgroup of MMPs is the most studied one due to its key role in metastasis. As it is composed of only two proteases, MMP2 and MMP9, it is important to understand whether each is indispensable or redundant in its biological function. Here we explored the role of the gelatinases in executing NCC migration, by determining whether MMP2 and/or MMP9 regulate migration across species in singular, combined, or redundant manners. Chick and mouse embryos were utilized to compare expression and activity of both MMPs using genetic and pharmacological approaches in multiple in vivo and ex vivo assays. Both MMPs were found to be expressed and active in mouse and chick NCCs. Inhibition of each MMP was sufficient to prevent NCC migration in both species. Yet, NCC migration was maintained in MMP2^-/- or MMP9^-/- mouse mutants due to compensation between the gelatinases, but reciprocal pharmacological inhibition in each mutant prevented NCC migration. This study reveals for the first time that both gelatinases are expressed in avian and mammalian NCCs, and demonstrates their fundamental and conserved role in promoting embryonic cell migration.

Chlorogenic Acid Alleviates Thiram-Induced Tibial Dyschondroplasia by Modulating Caspases, BECN1 Expression and ECM Degradation

Chlorogenic acid (CGA) is a widely applied traditional Chinese medicine ingredient which can be used for the treatment of osteoporosis. In this experiment, we investigated the potential therapeutic effect of chlorogenic acid on thiram-induced tibial dyschondroplasia (TD) and explored the underlying mechanisms that have been rarely mentioned by others yet. Performance indicator analysis and tibial parameter analysis showed that CGA exhibited a definite positive effect on thiram-induced TD chickens. In order to further explore the mechanisms underlying the positive actions of CGA, apoptotic, autophagic genes and MMPs involved in matrix mineralization of growth plate were evaluated in this study. The results showed that CGA decreased the expression of pro-apoptotic genes caspases-3 and caspases-9, leading to the reduction of apoptotic cells accumulated in growth plate. In addition, CGA also increased the level of BECN1, an important gene involved in autophagy, which benefits the survival of abnormal cells. Furthermore, CGA also increased the expression of MMP-9, MMP-10, and MMP-13, which can directly affect the ossification of bones. Altogether, these results demonstrate that CGA possesses a positive therapeutic effect on thiram-induced TD via modulating the expression of caspases and BECN1 and regulating the degradation of ECM (extracellular matrix).

Effect of Anacardic Acid against Thiram Induced Tibial Dyschondroplasia in Chickens via Regulation of Wnt4 Expression

Simple Summary

This study evaluated the ameliorating effect of anacardic acid (AA) in tibial dyschondroplasia (TD) chickens. Our results showed that AA can increase the feed conversion ratio, improve the weight, length and width of the tibia. AA administration restored the antioxidant parameters significantly (p < 0.05). The gene expression analysis revealed a decrease in wingless-type member 4 (Wnt4) expressions in TD chickens as compared to the control group, while AA treatment up-regulated the Wnt4 expression. The present study demonstrates that the AA plays an important role to prevent the lameness and restore the size of the tibial growth plate of chickens by regulating the expression of Wnt4.

Abstract

Tibial dyschondroplasia (TD) is a tibia bone problem in broilers. Anacardic acid (AA) is a traditional Chinese medicine, which is commonly used to treat arthritis in human. The purpose of the present study is to investigate the effect of AA against TD. A total of 300 day-old poultry birds were equally divided and distributed into three different groups: Control, TD and AA groups. The results showed that the feed conversion ratio was significantly lower in the TD group than control chickens. The tibia bone parameters including weight, length and width were of low quality in TD chickens, while the width of the tibial growth plate was enlarged remarkably. Whereas, in the AA treatment group, the tibia bone parameters showed improvement and tend to return to normal. The antioxidant parameters level of glutathione peroxidase (GSH-Px), superoxide dismutase (SOD), total and antioxidant capacity (T-AOC) was significantly decreased, while malondialdehyde (MDA) level was increased significantly in TD affected chickens. AA administration restored the antioxidant parameters significantly. The gene expression revealed a decrease in Wnt4 expression in TD chickens as compared to control chickens, while AA treatment up-regulated the Wnt4 expression. The present study demonstrates that the AA plays an important role to prevent the lameness and restore the size of tibial growth plate of chickens by regulating the expression of Wnt4.

Clinical efficiency and safety of Hsp90 inhibitor Novobiocin in avian tibial dyschondroplasia

Tibial dyschondroplasia (TD) is a bone defect of broilers and other poultry birds that disturbs growth plate and it causes lameness. Previously we evaluated differential expression of multiple genes involved in growth plate angiogenesis and reported the safety and efficacious of medicinal plant root extracted for controlling TD. In this study, clinical and protective effect of an antibiotic Novobiocin (Hsp90 inhibitor) and expression of Hsp90 and proteoglycan aggrecan was examined. The chicks were divided into three groups; Control, thiram-induced TD, and Novobiocin injected TD. After the induction of TD, the Novobiocin was administered through intraperitoneal route to TD-affected birds until the end of the experiment. The expressions and localization of Hsp90 were evaluated by qRT-PCR, immunohistochemistry (IHC) and western blot, respectively. Morphological, histological examinations, and serum biomarker levels were evaluated to assess specificity and protective effects of Novobiocin. The results showed that TD causing retarded growth, enlarged growth plate, distended chondrocytes, irregular columns of cells, decreased antioxidant capacity, reduced protein levels of proteoglycan aggrecan, and upregulated in Hsp90 expression (p < 0.05) in dyschondroplastic birds as compared with control. Novobiocin treatment restored growth plate morphology, reducing width, stimulated chondrocyte differentiation, sprouting blood vessels, corrected oxidative imbalance, decreased Hsp90 expressions and increased aggrecan level. Novobiocin treatment controlled lameness and improved growth in broiler chicken induced by thiram. In conclusion, the accumulation of the cartilage and up-regulated Hsp90 are associated with TD pathogenesis and irregular chondrocyte morphology in TD is along with reduced aggrecan levels in the growth plate. Our results indicate that Novobiocin treatment has potential to reduce TD by controlling the expression of Hsp90 in addition to improve growth and hepatic toxicity in broiler chicken.

Effect of Icariin on Tibial Dyschondroplasia Incidence and Tibial Characteristics by Regulating P2RX7 in Chickens

Tibial dyschondroplasia (TD) is a disease of rapid growing chickens that occurs in many avian species; it is characterized by nonvascular and nonmineralized growth plates, along with tibia bone deformation and lameness. Icariin is widely used to treat bone diseases in humans, but no report is available regarding the effectiveness of icariin against avian TD. Therefore, this study was designed to determine its effect against TD. For this purpose, a total of 180 broiler chicks were distributed into three groups including control, TD, and icariin group. Control group was given a standard normal diet, while TD and icariin groups received normal standard diet containing 50 mg/kg thiram to induce TD from days 3 to 7 after hatch. After the induction of TD, the chicks of icariin group were fed with standard normal diet by adding 10 mg/kg icariin in water. Then morphological and production parameters analysis of tibial bone indicators, physiological index changes, and gene expression were examined. The results showed that icariin administration not only decreased the mortality but also mitigated the lameness and promoted the angiogenesis, which diminished the TD lesion and significantly increased the expression of P2RX7 (P < 0.05) in TD affected thiram induced chicks. In conclusion, present findings suggest that icariin has a significant role in promoting the recovery of chicken growth plates affected by TD via regulating the P2RX7. Our findings reveal a new target for clinical treatment and prevention of TD in broiler chickens.

Icariin Ameliorate Thiram-Induced Tibial Dyschondroplasia via Regulation of WNT4 and VEGF Expression in Broiler Chickens

Tibial dyschondroplasia (TD) is main bone problem in fast growing poultry birds that effect proximal growth plate (GP) of tibia bone. TD is broadly defined as non-vascularized and non-mineralized, and enlarged GP with tibia bone deformation and lameness. Icariin (Epimedium sagittatum) is a traditional Chinese medicine, which is commonly practiced in the treatment of various bone diseases. Recently, many researcher reports about the beneficial effects of icariin in relation to various types of bone conditions but no report is available about promoting effect of icariin against TD. Therefore, current study was conducted to explore the ameliorating effect of icariin in thiram-induced TD chickens. A total of 180 broiler chicks were equally distributed in three groups; control, TD induced by thiram (50 mg/kg), and icariin group (treated with icariin @10 mg/kg). All groups were administered with normal standard diet ad libitum regularly until the end of experiment. The wingless-type member 4 (WNT4) and vascular endothelial growth factor (VEGF) genes and proteins expression were analyzed by quantitative real-time polymerase chain reaction and western blot analysis respectively. Tibial bone parameters, physiological changes in serum, antioxidant enzymes, and chicken growth performance were determined to assess advantage and protective effect of the medicine in broiler chicken. The expression of WNT4 was decreased while VEGF increased significantly (P < 0.05) in TD affected chicks. TD enhanced the GP, lameness, and irregular chondrocytes, while reduced the liver function, antioxidant enzymes in liver, and performance of chickens. Icariin treatment up-regulated WNT4 and down-regulated VEGF gene and protein expressions significantly (P < 0.05), restored the GP width, increased growth performance, corrected liver functions and antioxidant enzymes levels in liver, and mitigated the lameness in broiler chickens. In conclusion, icariin administration recovered GP size, normalized performance and prevented lameness significantly. Therefore, icariin treatments are encouraged to reduce the incidence of TD in broiler chickens.

Effect of tetramethylpyrazine on tibial dyschondroplasia incidence, tibial angiogenesis, performance and characteristics via HIF-1α/VEGF signaling pathway in chickens

Tibial dyschodroplasia (TD) is a most common pathological condition in many avian species that is characterized by failure of growth plate (GP) modeling that leads to the persistence of avascular lesion in the GP. Tetramethylpyrazine (TMP) is widely used to treat neurovascular disorders and pulmonary hypertension, but no report is available about promoting effect of TMP against TD. Therefore, a total of 210 broiler chicks were equally divided into three groups; Control, TD and TMP. During the experiment mortality rate, chicken performance indicators (daily weight, average daily feed intake, average daily weight gain and feed conversion ratio), tibia bone indicators (weight, length, width of tibial and the size of GP) in addition to gene expression of HIF-1α and VEGF were examined. The results showed that TMP administration restore the GP width, increase growth performance, and mitigated the lameness in broiler chickens. The expression of HIF-1α and VEGF increased significantly in TD affected thiram induced chicks. Whereas, TMP treatment down-regulated HIF-1α and VEGF genes and proteins expressions. The present study demonstrates that the TMP plays an important role in angiogenesis during the impairment and recovery of GP in TD via regulation of the HIF-1α/VEGF signaling pathway in chickens.

Matrix metalloproteinases-2 and -9 in Campylobacter jejuni-induced paralytic neuropathy resembling Guillain-Barré syndrome in chickens

Inflammation in Guillain-Barré syndrome (GBS) is manifested by changes in matrix metalloproteinase (MMP) and pro-inflammatory cytokine expression. We investigated the expression of MMP-2, -9 and TNF-α and correlated it with pathological changes in sciatic nerve tissue from Campylobacter jejuni-induced chicken model for GBS. Campylobacter jejuni and placebo were fed to chickens and assessed for disease symptoms. Sciatic nerves were examined by histopathology and immunohistochemistry. Expressions of MMPs and TNF-α, were determined by real-time PCR, and activities of MMPs by zymography. Diarrhea developed in 73.3% chickens after infection and 60.0% of them developed GBS like neuropathy. Pathology in sciatic nerves showed perinodal and/or patchy demyelination, perivascular focal lymphocytic infiltration and myelin swelling on 10th- 20th post infection day (PID). MMP-2, -9 and TNF-α were up-regulated in progressive phase of the disease. Enhanced MMP-2, -9 and TNF-α production in progressive phase correlated with sciatic nerve pathology in C. jejuni-induced GBS chicken model.

Effect of a new formulation of micronized and ultramicronized N-palmitoylethanolamine in a tibia fracture mouse model of complex regional pain syndrome

Complex regional pain syndrome type 1 (CRPS-I) is a disabling and frequently chronic condition. It involves the extremities and is a frequent consequence of distal tibia and radius fractures. The inflamed appearance of the affected CRPS-I limb suggests that local production of inflammatory mediators may be implicated in the ensuing etiology. A rodent tibia fracture model, characterized by inflammation, chronic unilateral hindlimb warmth, edema, protein extravasation, allodynia and hyperalgesia resembles the clinical features of patients with acute CRPS-I. N-palmitoylethanolamine (PEA), a member of the family of naturally-occurring N-acylethanolamines, is well-known for its ability to modulate inflammatory processes and regulate pain sensitivity. However, the large particle size and lipidic nature of PEA may limit its bioavailability and solubility when given orally. Micronized formulations are frequently used to enhance the dissolution rate of drug and reduce its variability of absorption when orally administered. The aim of this study was to assess the effects of a formulation of micronized and ultramicronized PEA (PEA-MPS), given orally in a mouse model of CRPS-I. CD-1 male mice were subjected to distal tibia fracture and divided into two groups: control and treated with PEA-MPS (PEA micronized 300 mg/kg and ultramicronized 600 mg/kg). Sensibility to pain was monitored in all mice throughout the course of the experiment. Twenty-eight days after tibia fracture induction animals were sacrificed and biochemical parameters evaluated. The PEA-MPS-treated group showed an improved healing process, fracture recovery and fibrosis score. PEA-MPS administration decreased mast cell density, nerve growth factor, matrix metalloproteinase 9 and cytokine expression. This treatment also reduced (poly-ADP)ribose polymerase activation, peroxynitrite formation and apoptosis. Our results suggest that PEA-MPS may be a new therapeutic strategy in the treatment of CRPS-I.

Earlier hatching time predisposes Cobb broiler chickens to tibial dyschondroplasia

Fertile eggs from Cobb 500 broiler breeder hens were incubated to provide low starting egg shell temperatures (EST; 36.9°C to 37.3°C) which were gradually increased to 37.8°C during the first 7 to 15 days of incubation compared with eggs incubated with a constant EST of 37.8°C (standard conditions) over the first 18 days of incubation. Time of individual chick hatching (measured at 6 h intervals from 468 h of incubation), chick weight, chick length and yolk weight were measured at take-off and BW was measured at 7, 14, 28, 34 and 42 days of age. Male birds at 34 and 42 days of age were assessed for their ability to remain standing in a latency-to-lie test. At 34 and 42 days, male birds were examined for leg symmetry, foot pad dermatitis, hock bruising and scored (scale 0 to 4, where 0=no lesion and 4=lesions extending completely across the tibial growth plate) for tibial dyschondroplasia (TD) lesions. The lower EST profiles caused chicks to hatch later than those incubated under the standard EST profile. Chicks which hatched at ⩽498 h incubation grew faster over the first 7 days than those that hatched later. There were significantly more birds (only males were studied) that hatched from the lower EST profiles with TD scores of 0 and 1 and fewer with score 4 at 34 days than those hatched under the standard profile. Male birds at 34 days with TD lesions ⩾3 stood for significantly shorter times than males with TD scores ⩽2. Moreover, male birds at 34 and 42 days with TD lesion scores of ⩾3 hatched significantly earlier and grew significantly faster over the first 2 weeks of age than did male birds with TD scores ⩽2. It appears possible to decrease the severity and prevalence of TD in the Cobb 500 broiler by ensuring that the birds do not hatch before 498 h of incubation.

Targeting gene expression during the early bone healing period in the mandible: A base for bone tissue engineering

PURPOSE

Although bone tissue engineering techniques have become more and more sophisticated than in the past, natural bone healing mechanisms have not been sufficiently considered for further improvement of these techniques so far. We used an established animal model with transcriptome analysis to generate an unbiased picture of early bone healing to support tissue engineering concepts.

MATERIAL AND METHODS

In 30 Wistar rats, a 3-mm bone defect was created in the mandibular angle. Tissue was sampled at 5, 10, and 15 days, and the former defect area was excised to undergo transcriptome analysis after RNA extraction. Five differentially expressed genes were further evaluated with reverse transcription-polymerase chain reaction (rt-PCR).

RESULTS

Transcriptome analysis revealed 2467 significantly over- and under-expressed transcripts after 5 days and 2265 after 15 days of bone healing, respectively. Validation via rt-PCR confirmed overexpression of osteoactivin, angiopoietin-like factor-4, and metallomatrix proteinase-9 and underexpression of mastcellprotease-10 and proteoglycane-2 in comparison to values in the control group.

CONCLUSION

This systematic genome-wide transcriptome analysis helps to decipher the physiological mechanisms behind physiological bone healing. The exemplary depiction of 5 genes demonstrates the great complexity of metabolic processes during early bone healing. Here, BMP-2 signaling pathways and local hypoxia play decisive roles in bone formation.

Differential expression of extracellular matrix metalloproteinase inducer (EMMPRIN/CD147) in avian tibial dyschondroplasia

Tibial dyschondroplasia (TD) is an avian bone disorder of different aetiologies that may be associated with lameness. The disorder is characterized by focal disruption of endochondral bone formation, with a lack of matrix proteolysis and an accumulation of non-mineralized avascular cartilage. The aim of this study was to determine the expression of extracellular matrix metalloproteinase inducer (EMMPRIN/CD147) in normal, thiram-induced TD lesions and in the process of recovery from TD in broiler chickens. An extracellular matrix (ECM) degrading enzyme, matrix metalloproteinase-9 (MMP-9), was selected to investigate the effects of CD147 in the degradation of ECM. Gene expression was analysed by quantitative real-time polymerase chain reaction and protein levels by immunohistochemistry and western blotting. The birds were divided into three groups: thiram fed; recovery; and controls. Genes encoding CD147 and MMP-9 were down-regulated during the development of the disease, and were up-regulated during recovery. Western blotting also showed lower protein levels of CD147 in TD, which increased during the recovery phase associated with ECM degradation and growth plate repair. The findings of this study suggest that ECM has a crucial role in the occurrence of TD and that CD147 appears to play a pivotal role in matrix proteolysis in the chicken, similar to that in other species.

Screening of differentially expressed genes in the growth plate of broiler chickens with tibial dyschondroplasia by microarray analysis

Background

Tibial dyschondroplasia (TD) is a common skeletal disorder in broiler chickens. It is characterized by the presence of a non-vascularized and unmineralized cartilage in the growth plate. Previous studies have investigated differential expression of genes related to cartilage development during latter stages of TD. The aim of our study was to identify differentially expressed genes (DEGs) in the growth plate of broiler chickens, which were associated with early stage TD. We induced TD using tetramethylthiuram disulfide (thiram) for 1, 2, and 6 days and determined DEGs with chicken Affymetrix GeneChip assays. The identified DEGs were verified by quantitative polymerase chain reaction (qPCR) assays.

Results

We identified 1630 DEGs, with 82, 1385, and 429 exhibiting at least 2.0-fold changes (P < 0.05) at days 1, 2, and 6, respectively. These DEGs participate in a variety of biological processes, including cytokine production, oxidation reduction, and cell surface receptor linked signal transduction on day 1; lipid biosynthesis, regulation of growth, cell cycle, positive and negative gene regulation, transcription and transcription regulation, and anti-apoptosis on day 2; and regulation of cell proliferation, transcription, dephosphorylation, catabolism, proteolysis, and immune responses on day 6. The identified DEGs were associated with the following pathways: neuroactive ligand-receptor interaction on day 1; synthesis and degradation of ketone bodies, terpenoid backbone biosynthesis, ether lipid metabolism, JAK-STAT, GnRH signaling pathway, ubiquitin mediated proteolysis, TGF-β signaling, focal adhesion, and Wnt signaling on day 2; and arachidonic acid metabolism, mitogen-activated protein kinase (MAPK) signaling, JAK-STAT, insulin signaling, and glycolysis on day 6. We validated seven DEGs by qPCR.

Conclusions

Our findings demonstrate previously unrecognized changes in gene transcription associated with early stage TD. The DEGs we identified by microarray analysis will be used in future studies to clarify the molecular pathogenic mechanisms of TD. From these findings, potential pathways involved in early stage TD warrant further investigation.

MMP9 regulates the cellular response to inflammation after skeletal injury

Like other tissue injuries, bone fracture triggers an inflammatory response, which plays an important role in skeletal repair. Inflammation is believed to have both positive and negative effects on bone repair, but the underlying cellular mechanisms are not well understood. To assess the role of inflammation on skeletal cell differentiation, we used mouse models of fracture repair that stimulate either intramembranous or endochondral ossification. In the first model, fractures are rigidly stabilized leading to direct bone formation, while in the second model, fracture instability causes cartilage and bone formation. We compared the inflammatory response in these two mechanical environments and found changes in the expression patterns of inflammatory genes and in the recruitment of inflammatory cells and osteoclasts. These results suggested that the inflammatory response could influence skeletal cell differentiation after fracture. We then exploited matrix metalloproteinase 9 (MMP9) that is expressed in inflammatory cells and osteoclasts, and which we previously showed is a potential regulator of cell fate decisions during fracture repair. Mmp9(-/-) mice heal stabilized fractures via endochondral ossification, while wild type mice heal via intramembranous ossification. In parallel, we observed increases in macrophages and T cells in the callus of Mmp9(-/-) compared to wild type mice. To assess the link between the profile of inflammatory cells and skeletal cell fate functionally, we transplanted Mmp9(-/-) mice with wild type bone marrow, to reconstitute a wild type hematopoietic lineage in interaction with the Mmp9(-/-) stroma and periosteum. Following transplantation, Mmp9(-/-) mice healed stabilized fractures via intramembranous ossification and exhibited a normal profile of inflammatory cells. Moreover, Mmp9(-/-) periosteal grafts healed via intramembranous ossification in wild type hosts, but healed via endochondral ossification in Mmp9(-/-) hosts. We observed that macrophages accumulated at the periosteal surface in Mmp9(-/-) mice, suggesting that cell differentiation in the periosteum is influenced by factors such as BMP2 that are produced locally by inflammatory cells. Taken together, these results show that MMP9 mediates indirect effects on skeletal cell differentiation by regulating the inflammatory response and the distribution of inflammatory cells, leading to the local regulation of periosteal cell differentiation.

The role of matrix gla protein in ossification and recovery of the avian growth plate

Extracellular matrix mineralization is an essential physiologic process in bone, teeth, and hypertrophic cartilage. Matrix Gla protein (MGP), an inhibitor of mineralization, is expressed by chondrocytes and vascular smooth muscle cells to inhibit calcification of those soft tissues. Tibial dyschondroplasia (TD), a skeletal abnormality apparent as a plug of non-vascularized, non-mineralized, white opaque cartilage in the tibial growth plate of avian species can serve as a good model for studying process and genes involved in matrix mineralization and calcification. In this work, we studied the involvement of MGP in the development of TD, as well as in the processes of spontaneous and induced recovery from this syndrome. First, we found that during normal bone development, MGP is expressed in specific time and locations, starting from wide-spread expression in the yet un-ossified diaphysis during embryonic development, to specific expression in hypertrophic chondrocytes adjacent to the chondro-osseous junction and the secondary ossification center just prior to calcification. In addition, we show that MGP is not expressed in the impaired TD lesion, however when the lesion begins to heal, it strongly express MGP prior to its calcification. Moreover, we show that when calcification is inhibited, a gap is formed between the expression zones of MGP and BMP2 and that this gap is closed during the healing process. To conclude, we suggest that MGP, directly or through interaction with BMP2, plays a role as ossification regulator that acts prior to ossification, rather then simple inhibitor.

Expression of hindbrain boundary markers is regulated by FGF3

Compartment boundaries act as organizing centers that segregate adjacent areas into domains of gene expression and regulation, and control their distinct fates via the secretion of signalling factors. During hindbrain development, a specialized cell-population forms boundaries between rhombomeres. These boundary cells demonstrate unique morphological properties and express multiple genes that differs them from intra-rhombomeric cells. Yet, little is known regarding the mechanisms that controls the expression or function of these boundary markers.Multiple components of the FGF signaling system, including ligands, receptors, downstream effectors as well as proteoglycans are shown to localize to boundary cells in the chick hindbrain. These patterns raise the possibility that FGF signaling plays a role in regulating boundary properties. We provide evidence to the role of FGF signaling, particularly the boundary-derived FGF3, in regulating the expression of multiple markers at hindbrain boundaries. These findings enable further characterization of the unique boundary-cell population, and expose a new function for FGFs as regulators of boundary-gene expression in the chick hindbrain.

Bone Gla protein increases HIF-1alpha-dependent glucose metabolism and induces cartilage and vascular calcification

OBJECTIVE

Bone Gla Protein (BGP, osteocalcin) is commonly present in the calcified vasculature and was recently shown as energy metabolism-regulating hormone. This study investigates the role of BGP in cartilage and vasculature mineralization.

METHODS AND RESULTS

We established an in vitro BGP-overexpression model in chondrocytes (ATDC5) and vascular smooth muscle cells (MOVAS). BGP overexpression upregulated markers of chondrogenic differentiation and intensified staining for minerals. BGP overexpression enhanced glucose uptake and increased expression of glucose transporters and glycolysis enzymes while decreasing gluconeogenesis enzymes. Treatment with purified BGP activated insulin signaling pathway and upregulated genes of glucose transport and utilization. Both BGP overexpression and treatment with purified BGP resulted in stabilization of hypoxia-inducible factor 1α (HIF-1α) in chondrocytes and vascular smooth muscle cells, shown essential in mediating the direct metabolic effect of BGP. The in vivo model of 1,25(OH)(2)D(3)-induced vascular calcification in rats revealed a correlation between calcification, elevated BGP levels, and increased HIF-1α expression in aortas and bone growth plates. The in vivo introduction of BGP siRNA, coadministered with 1,25(OH)(2)D(3), prevented 1,25(OH)(2)D(3)-induced HIF-1α stabilization, and diminished osteochondrogenic differentiation and mineralization of aortas.

CONCLUSIONS

This study demonstrates novel mechanism by which BGP locally shifts cells toward glycolytic breakdown of glucose, in a HIF-1α-dependent manner, and stimulates calcification of cartilage and vasculature.

Hsp90 and angiogenesis in bone disorders—lessons from the avian growth plate

Thiram-induced tibial dyschondroplasia (TD) and vitamin-D deficiency rickets are avian bone disorders of different etiologies characterized by abnormal chondrocyte differentiation, enlarged and unvascularized growth plates, and lameness. Heat-shock protein 90 (Hsp90) is a proangiogenic factor in mammalian tissues and in tumors; therefore, Hsp90 inhibitors were developed as antiangiogenic factors. In this study, we evaluated the association between Hsp90, hypoxia, and angiogenesis in the chick growth plate. Administration of the Hsp90 inhibitor to TD- and rickets-afflicted chicks at the time of induction resulted in reduction in growth-plate size and, contrary to its antiangiogenic effect in tumors, a major invasion of blood vessels occurred in the growth plates. This was the result of upregulation of the VEGF receptor Flk-1, the major rate-limiting factor of vascularization in TD and rickets. In addition, the abnormal chondrocyte differentiation, as characterized by collagen type II expression and alkaline phosphatase activity, and the changes in hypoxia-inducible factor-1α (HIF-1α) in both disorders were restored. All these changes resulted in prevention of lameness. Inhibition of Hsp90 activity reduced growth-plate size, increased vascularization, and mitigated lameness also in TD chicks with established lesions. In summary, this is the first reported demonstration of involvement of Hsp90 in chondrocyte differentiation and growth-plate vascularization. In contrast to the antiangiogenic effect of Hsp90 inhibitors observed in mammals, inhibition of Hsp90 activity in the unvascularized TD- and rickets-afflicted chicks resulted in activation of the angiogenic switch and reinstated normal growth-plate morphology.