Transcriptome analysis reveals the pathogenesis of spontaneous tibial dyschondroplasia in broilers

Tibial dyschondroplasia (TD) is a severe bone disease that affects fast-growing broiler chickens and causes economic loss. Despite previous studies, the regulatory mechanism of TD remains unclear and is thought to be primarily based on thiram induction, which may differ from that of naturally occurring diseases. To better understand TD, a digital X-ray machine was used in the present study to determine its incidence in four hundred yellow-feathered broiler chickens. The results showed that the incidence of TD was 22% after 6 weeks and gradually decreased after 8 and 10 weeks. The body weight of broilers with TD decreased significantly compared to that of NTD broilers. In addition, the length and density of the tibia were reduced after eight and 10 weeks, and the density of the tibia was reduced after 6 weeks compared with the NTD chickens. This study also examined tibial quality parameters from TD (n = 12) and NTD broilers (n = 12) and found that bone mineral content, bone mineral density, bone ash content, calcium content, and phosphorus content were significantly reduced in TD broilers. Transcriptome analysis revealed 849 differentially expressed genes (DEGs) in the growth plate between TD (n = 6) and NTD groups (n = 6). These genes were enriched in ECM-receptor interaction, cytokine-cytokine receptor interaction, calcium signaling pathway, and TGF-β signaling. Genes encoding the alpha chain of type XII collagen, that is, COL1A1, COL5A1, and COL8A1) were identified as critical in the regulatory network of TD. Gene set enrichment analysis (GSEA) revealed that the pathways of cartilage development, circulatory system development, and nervous system development were changed in the growth plates of TD birds. In the blood transcriptome, 12 DEGs were found in TD (n = 4) and NTD chickens (n = 4), and GSEA revealed that the pathways from TD broilers' blood related to the phagosome, linoleic acid metabolism, monoatomic ion homeostasis, and calcium ion transport were downregulated. This study provides a comprehensive understanding of TD, including its effects on tibial quality, tibial changes, and the circulatory system, along with identifying important genes that may lead to the development of TD.

Molecular mechanism of thiram-induced abnormal chondrocyte proliferation via lncRNA MSTRG.74.1-BNIP3 axis

Thiram, a widely used organic pesticide in agriculture, exhibits both bactericidal and insecticidal effects. However, prolonged exposure to thiram has been linked to bone deformities and cartilage damage, contributing to the development of tibial dyschondroplasia (TD) in broilers and posing a significant threat to global agricultural production. TD, a prevalent nutritional metabolic disease, manifests as clinical symptoms like unstable standing, claudication, and sluggish movement in affected broilers. In recent years, there has been growing recognition of the regulatory role of long non-coding RNA (lncRNA) in tibial cartilage formation among broilers through diverse signaling pathways. This study employs in vitro experimental models, growth performance analysis, and clinical observation to assess broilers' susceptibility to thiram pollution. Transcriptome sequencing analysis revealed a significant elevation in the expression of lncRNA MSTRG.74.1 in both the con group and the thiram-induced in vitro group. The results showed that lncRNA MSTRG.74.1 plays a pivotal role in influencing the proliferation and abnormal differentiation of chondrocytes. This regulation occurs through the negative modulation of apoptotic genes, including Bax, Cytc, Bcl2, Apaf1, and Caspase3, along with genes Atg5, Beclin1, LC3b, and protein p62. Moreover, the overexpression of lncRNA MSTRG.74.1 was found to regulate broiler chondrocyte development by upregulating BNIP3. In summary, this research sheds light on thiram-induced abnormal chondrocyte proliferation in TD broilers, emphasizing the significant regulatory role of the lncRNA MSTRG.74.1-BNIP3 axis, which will contribute to our understanding of the molecular mechanisms underlying TD development in broilers exposed to thiram.

Homeostatic Regulation of Pro-Angiogenic and Anti-Angiogenic Proteins via Hedgehog, Notch Grid, and Ephrin Signaling in Tibial Dyschondroplasia

Precise coupling of two fundamental mechanisms, chondrogenesis and osteogenesis via angiogenesis, plays a crucial role during rapid proliferation of growth plates, and alteration in their balance might lead to pathogenic conditions. Tibial dyschondroplasia (TD) is characterized by an avascular, non-mineralized, jade-white "cartilaginous wedge" with impaired endochondral ossification and chondrocyte proliferation at the proximal end of a tibial bone in rapidly growing poultry birds. Developing vascular structures are dynamic with cartilage growth and are regulated through homeostatic balance among pro and anti-angiogenic proteins and cytokines. Pro-angiogenic factors involves a wide spectrum of multifactorial mitogens, such as vascular endothelial growth factors (VEGF), platelet-derived growth factors (PDGF), basic fibroblast growth factor (bFGF), placental growth factors, transforming growth factor-β (TGF-β), and TNF-α. Considering their regulatory role via the sonic hedgehog, notch-gridlock, and ephrin-B2/EphB4 pathways and inhibition through anti-angiogenic proteins like angiostatin, endostatin, decoy receptors, vasoinhibin, thrombospondin, PEX, and troponin, their possible role in persisting inflammatory conditions like TD was studied in the current literature review. Balanced apoptosis and angiogenesis are vital for physiological bone growth. Any homeostatic imbalance among apoptotic, angiogenetic, pro-angiogenic, or anti-angiogenic proteins ultimately leads to pathological bone conditions like TD and osteoarthritis. The current review might substantiate solid grounds for developing innovative therapeutics for diseases governed by the disproportion of angiogenesis and anti-angiogenesis proteins.

Sodium butyrate ameliorates thiram-induced tibial dyschondroplasia and gut microbial dysbiosis in broiler chickens

Thiram is a dithiocarbamate pesticide widely used in agriculture as a fungicide for storing grains to prevent fungal diseases. However, its residues have threatened the safety of human beings and the stability of the ecosystem by causing different disease conditions, e.g., tibial dyschondroplasia (TD), which results in a substantial economic loss for the poultry industry. So, the research on TD has a great concern for the industry and the overall GDP of a country. In current study, we investigated whether different concentrations (300, 500, and 700 mg/kg) of sodium butyrate alleviated TD induced under acute thiram exposure by regulating osteogenic gene expression, promoting chondrocyte differentiation, and altering the gut microbial community. According to the findings, sodium butyrate restored clinical symptoms in broilers, improved growth performance, bone density, angiogenesis, and chondrocyte morphology and arrangement. It could activate the signal transduction of the Wnt/β-catenin pathway, regulate the expression of GSK-3β and β-catenin, and further promote the production of osteogenic transcription factors Runx2 and OPN for restoration of lameness. In addition, the 16S rRNA sequencing revealed a significantly different community composition among the groups. The TD group increased the abundance of the harmful bacteria Proteobacteria, Subdoligranulum, and Erysipelatoclostridium. The sodium butyrate enriched many beneficial bacteria, such as Bacteroidetes, Verrucomicrobia, Faecalibacterium, Barnesiella, Rikenella, and Butyricicoccus, etc., especially at the concentration of 500 mg/kg. The mentioned concentration significantly limited the intestinal disorders under thiram exposure, and restored bone metabolism.

Morinda officinalis Polysaccharides Ameliorates Bone Growth by Attenuating Oxidative Stress and Regulating the Gut Microbiota in Thiram-Induced Tibial Dyschondroplasia Chickens

Tibial dyschondroplasia (TD) occurs in chickens and other fast-growing birds, affecting their cartilage growth and leading to reduced meat quality in broilers. Morinda officinalis polysaccharide (MOP) is one of the chief active components of Morinda officinalis, which promotes bone formation, inhibiting bone loss and having anti-oxidant and anti-inflammatory properties. A total of 120 AA chickens were randomly divided into the CON group (basal diet), TD group (100 mg/kg thiram + basal diet), and MOP group (100 mg/kg thiram + basal diet + water with 500 mg/kg MOP). The experiment lasted 21 days. The results showed that MOP could alleviates broiler lameness caused by TD, restore the morphological structure of tibial growth plate (TGP), increase tibial weight (p < 0.05), balance the disorder of calcium and phosphorus metabolism, and promote bone formation by increasing the expression of BMP-2, Smad4, and Runx2 genes In addition, MOP supplementation stimulated the secretion of plasma antioxidant enzymes (T-SOD and GSH-Px) by regulating the expression of SOD and GPX-1 genes, thereby enhancing the antioxidant capacity of TD broilers. Interestingly, we observed MOP can also improve gut microbiota by increasing the beneficial bacteria count and decreasing the harmful bacteria count. These findings indicated that MOP can regulate bone formation through the BMP/Smads signaling pathway, attenuating oxidative stress and regulating the gut microbiota of TD broilers, so as to achieve the effect of treating TD. This suggests that MOP might be a potential novel drug in the treatment of TD in chickens.

Regulatory Role of Apoptotic and Inflammasome Related Proteins and Their Possible Functional Aspect in Thiram Associated Tibial Dyschondroplasia of Poultry

Tibial dyschondroplasia debilities apoptotic and inflammasomal conditions that can further destroy chondrocytes. Inflammasomes are specialized protein complexes that process pro-inflammatory cytokines, e.g., interleukin-1β (IL-1β) and IL-18. Moreover, there is mounting evidence that many of the signaling molecules that govern programmed cell death also affect inflammasome activation in a cell-intrinsic way. During the last decade, apoptotic functions have been described for signaling molecules involving inflammatory responses and cell death pathways. Considering these exceptional developments in the knowledge of processes, this review gives a glimpse of the significance of these two pathways and their connected proteins in tibial dyschondroplasia. The current review deeply elaborates on the elevated level of signaling mediators of mitochondrial-mediated apoptosis and the inflammasome. Although investigating these pathways’ mechanisms has made significant progress, this review identifies areas where more study is especially required. It might lead to developing innovative therapeutics for tibial dyschondroplasia and other associated bone disorders, e.g., osteoporosis and osteoarthritis, where apoptosis and inflammasome are the significant pathways.

Integrated Fecal Microbiome and Metabolomics Reveals a Novel Potential Biomarker for Predicting Tibial Dyschondroplasia in Chickens

Tibial dyschondroplasia (TD) is a metabolic tibial-tarsal disorder occurring in fast-growing poultry, and its diagnosis is mainly based on an invasive method. Here, we profiled the fecal gut microbiome and metabolome of broilers with and without TD to identify potential non-invasive and non-stress biomarkers of TD. First, TD broilers with the most pronounced clinical signs during the experiment were screened and faecal samples were collected for integrated microbiome and metabolomics analysis. Moreover, the diagnostic potential of identified biomarkers was further validated throughout the experiment. It was noted that the microbial and metabolic signatures of TD broilers differed from those of normal broilers. TD broilers were characterized by enriched bacterial OTUs of the genus Klebsiella, and depleted genera [Ruminococcus], Dorea, Ruminococcus, Oscillospira, Ochrobactrum, and Sediminibacterium. In addition, a total of 189 fecal differential metabolites were identified, mainly enriched in the purine, vitamin and amino acid metabolism, which were closely associated with differential microbiota and tibia-related indicators. Furthermore, three fecal metabolites were screened, including 4-hydroxybenzaldehyde, which distinguished TD from normal broilers with extremely high specificity and was superior to serum bone markers. These results indicated that gut microbiota equilibrium might influence the pathogenesis of TD by modulating host metabolism, and the identified fecal metabolite 4-hydroxybenzaldehyde might be a potential and non-invasive biomarker for predicting TD in chickens.

Prediction of the Molecular Mechanism of Eucommiae Cortex - Achyranthis Bidentatae Radix in the treatment of Osteoarthritis: Network Pharmacology and Molecular Docking

OBJECTIVE

To retrieve the core drug of osteoarthritis in clinic using Data Mining, predict the drug molecular action target through the Network Pharmacology, identify the key nodes of the interaction by combining with the related targtes of osteoarthritis, explore the pharmacological mechanism of Traditional Chinese Medicine against osteoarthritis and other possible mechanisms of actions.

METHODS

to retrieve the commonly used therapeutic formulations for osteoarthritis patients in clinical with PubMed, CNKI, VIP, CBM, WanFang Database and other databases, and screen out the core drugs through the Ancient and Modern Medical Case Cloud Platform and software Gephi, filter out the core drug molecules and targets combined with TCMSP database and the targets of osteoarthritis in Genecard and OMIM database, plunge those data into R project and Cytoscape to construct the intersection model of Drug molecule-osteoarthritis, establish PPI network and GO and conduct KEGG enrichment analysis with String database. Vina molecular docking was finally implemented to draw molecular docking diagram, and the results were analyzed after comprehensive analysis.

RESULTS

The core drug pairs were identified as "Eucommiae Cortex - Achyranthis Bidentatae Radix" through correlation analysis, complex network analysis based on the coefficient. "Eucommiae Cortex - Achyranthis Bidentatae Radix" can intervene cell behavior through multiple pathways and regulate cell metabolism, cytokine synthesis, oxidative and cellular immunity with the help of topology analysis in String Database.

CONCLUSIONS

The core molecules of Quercetin and Kaempferol derived from "Eucommia bark - achyranthes" can change the spatial conformation of PTGSs by hydrogen bonding with PTGSs, the hydrophobic bonds and van der Waals forces generated by Baicalein, Wogonin and β-carotene, thereby changing the activity of PTGSs and affecting bone properties the process of osteoarthritis.

Identification of key miRNAs affecting broilers with valgus-varus deformity by RNA sequencing and analysis of miRNA-mRNA interactions

Valgus-varus Deformity (VVD) leg disease often affects chickens raised in modern large-scale breeding operations. Losses due to VVD are costly to farmers, and the condition also causes significant suffering in affected birds. In this study, we profiled RNAs from the spleens of VVD (BS) and healthy (JS) broilers using high-throughput sequencing to identify miRNAs that might be involved in the development of the disease. Fifty differentially expressed miRNAs (DEMs) were found, of which 30 were up-regulated and 20 were down-regulated in VVD-affected birds (|log 2 Fold Change| ≥ 1 and q-value < 0.05). DEMs were matched with putative target genes and 864 target genes were found. Gene Ontology (GO) analyses of these target genes showed that they were significantly enriched in the "cytoplasm" term (q-value < 0.05), and most of the target genes were enriched in "cellular component". Kyoto encyclopedia of genes and genomes (KEGG) analysis showed that they were significantly enriched in 11 signaling pathways (P-value < 0.05), including metabolic pathways, 2-oxocarboxylic acid metabolism, regulation of actin cytoskeleton, purine metabolism, endocytosis and so on. And we found that they were enriched in immune-related pathways in which MAPK, Notch, JAK-Stat, Toll-like receptor, p53 and other single pathways were involved in the development of skeletal diseases. Differentially expressed mRNAs obtained from our previous study were used to construct an interaction network consisting of 16 DEMs and 21 differentially expressed mRNAs (|log 2 Fold Change| ≥ 1 and q-value < 0.05). We found that miR-12247-5p, miR-15c-5p, miR-15b-5p, FKBP5 and HSP90AB1 were at the center of network interaction. This study provides a foundation for further investigations of the pathogenesis and genetic mechanisms underlying VVD.

Screening of toll-like receptor signaling pathway-related genes and the response of recombinant glutathione S-transferase A3 protein to thiram induced apoptosis in chicken erythrocytes

The expression of genes related to the Toll-like receptors (TLRs) signaling pathway were determined. Group A, B and C fed with basal diet and group D, E and F induced TD by feeding a basal diet containing 100 mg·kg-1 thiram. rGSTA3 protein was injected at 20 μg·kg-1 in group B, E and at 50 μg·kg-1 in C, F. Results suggested that lameness and death of chondrocytes were significant on day 14. TLRs signaling pathway related genes were screened based on the transcriptome enrichment, and validated on qPCR. IL-7, TLR2, 3, 4, 5, 7, 15, MyD88, MHC-II, MDA5 and TRAF6 were significantly (p < 0.05) expressed in group E and F as compared to group D on day 14 and 23. IL-7, MHCII, TRAF6, TLR3, TLR5, TLR7, and TLR15 determined insignificant in group D compared to group A on day 23. TD occur in an early phase and alleviated in the later period. rGSTA3 protein can prevent apoptosis and repair degraded chondrocytes.

LPS-induced inflammation disorders bone modeling and remodeling by inhibiting angiogenesis and disordering osteogenesis in chickens

Inflammation plays a negative role in the growth and development of bone. However, the underlining mechanisms of inflammation caused abnormal bone development and even bone disease are still poorly understood, especially in chickens. In this study, we explored the influence of inflammation on bone formation in broilers for the first time by using lipopolysaccharide (LPS) to establish systemic inflammatory models in chickens with tibia as the research object. The measurements of production and tibial parameters showed an inefficient production performance and lower growth rate in LPS group. We also found a large amount of platelets, inflammatory cells in chickens' blood and higher levels of inflammatory factors in serum after LPS injection, meanwhile, increase in thrombus, chondrocyte nucleolysis, and osteoclasts and a reduction in blood vessels were observed in growth plate through histological observation. The qPCR analysis showed that the mRNA expression levels of NF-κB, TLR4, TF, TPO, and its receptor C-MPL enhanced, while VEGFA was inhibited in LPS group. In addition, in OPG/RANKL system, OPG was decreased while RANKL enhanced. It was also observed that the mRNA levels of MMP-9 and its inducing factor CD147 enhanced in LPS group. The western blot results were basically in consistent with mRNA test. Thus, we infer that inflammation can inhibit bone modeling and remodeling by affecting angiogenesis and osteogenesis, and result in negative effect on bone formation furtherly.

Recombinant glutathione-S-transferase A3 protein regulates the angiogenesis-related genes of erythrocytes in thiram induced tibial lesions

Tibial dyschondroplasia (TD) is a skeletal deformity disease in broilers that occurs when vascularization in the growth plate (GP) is below normal. Although, blood vessels have been reported to contribute significantly in bone formation. Therefore, in the current study, we have examined the mRNA expression of angiogenesis-related genes in erythrocytes of thiram induced TD chickens by qRT-PCR and performed histopathological analysis to determine regulatory effect of recombinant Glutathione-S-Transferase A3 (rGSTA3) protein in response to the destructive effect of thiram following the injection of rGSTA3 protein. Histopathology results suggested that, blood vessels of GPs were damaged in thiram induced TD chicken group (D), it also affected the area and density of blood vessels. In the 20 and 50 μg·kg^-1 of rGSTA3 protein-administered groups, E and F vessels appeared to be normal and improved on day 6 and 15. Furthermore, qRT-PCR results showed that rGSTA3 protein significantly (P < .05) up-regulated the expression of the most important angiogenesis-related integrin family genes ITGA2, ITGA5, ITGB2, ITGB3, ITGAV. The expression level of other genes including TBXA2R, FYN, IQGAP2, IL1R1, GIT1, RAP1B, RPL17, RAC2, MAML3, PTPN11, VAV1, PTCH1, NCOR2, CLU and ITGB3 up-regulated on dosage of rGSTA3 protein. In conclusion, angiogenesis is destroyed in thiram induced TD broilers, and rGSTA3 protein injection improved the vascularization of GPs by upregulating the angiogenesis related genes most importantly integrin family genes ITGAV, ITGA2, ITGB2, ITGB3, ITGA5.

The role of blood vessels in broiler chickens with tibial dyschondroplasia

Tibial dyschondroplasia (TD) is an intractable tibiotarsal bone disorder of rapid growing avian species, which leads to huge economic losses and compromised poultry welfare. However, the exact pathogenesis and treatment of TD remain largely unknown. Based on continuous research findings, we propose the TD pathogenesis hypothesis: during skeletal development of TD chickens, due to the absence of vasculature of proximal tibial growth plates (TGP), hypertrophic chondrocytes of the TGP are unable to complete calcification in normal bone development and less dead chondrocytes in the corresponding area can be timely transported through the blood vessels. Moreover, recent studies demonstrate that the TD formation mechanism gradually tends to a large number of dead chondrocytes in the TGP region or apoptosis occur due to various factors (such as, reduction of vascular invasion and blood cells, and increased weight or mechanical force of the tibia), while the reduction of blood vessels is insufficient to remove these chondrocytes and eventually leads to the TD formation. Recognizing the possible role of the blood vessels in the incidence of TD and can propose that the improvement in vasculature might be a novel therapeutic approach for ending TD in chickens.

Puerarin enhance vascular proliferation and halt apoptosis in thiram-induced avian tibial dyschondroplasia by regulating HIF-1α, TIMP-3 and BCL-2 expressions

Tetramethyl thiuram disulfide (thiram) is a dithiocarbamate pesticide used for crop protection and storage. But, it's widespread utilization is associated with deleterious growth plate cartilage disorder in broilers termed as avian tibial dyschondroplasia (TD). TD results in non-mineralized and less vascularized proximal tibial growth plate cartilage causing lameness and poor growth performance. This study investigated the therapeutic potential of puerarin against thiram toxicity in TD affected chickens. One-day-old broiler chickens (n = 240) were alienated into three equal groups i.e. control, TD and puerarin (n = 80) and were offered standard feed. Additionally, TD and puerarin groups were offered thiram at 50 mg/kg of feed from 4 to 7 days for TD induction followed by puerarin therapy at 120 mg/kg to puerarin group only from 8 to 18 days for TD treatment. Thiram feeding to TD and puerarin group chickens caused lameness, mortality, and increased the aspartate aminotransferase (AST), alanine aminotransferase (ALT), malondialdehyde (MDA) levels and growth plate (GP) size and upregulated HIF-1α expression. Besides, the production parameters, alkaline phosphatase (ALP), superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) levels and the expressions of TIMP-3 and BCL-2 were decreased (p < 0.05). Puerarin alleviated lameness, enhanced angiogenesis and growth performance and serum and antioxidant enzymes, decreased apoptosis and recuperated GP width by significantly downregulating HIF-1α and upregulating the TIMP-3 and BCL-2 mRNA and protein expressions in puerarin group chickens (p < 0.05). In conclusion, the toxic effects associated with thiram can be mitigated using puerarin.

Plastrum Testudinis Extract Mitigates Thiram Toxicity in Broilers via Regulating PI3K/AKT Signaling

Tibial dyschondroplasia (TD) negatively affects broilers all over the world, in which the accretion of the growth plate (GP) develops into tibial proximal metaphysis. Plastrum testudinis extract (PTE) is renowned as a powerful antioxidant, anti-inflammatory, and bone healing agent. The current study was conducted to evaluate the efficacy of PTE for the treatment of thiram-induced TD chickens. Broilers (day old; n = 300) were raised for 3 days with normal feed. On the 4th day, three groups (n = 100 each) were sorted, namely, the control (normal diet), TD, and PTE groups (normal diet+ thiram 50 mg/kg). On the 7th day, thiram was stopped in the TD and PTE group, and the PTE group received a normal diet and PTE (30 mg/kg/day). Plastrum testudinis extract significantly restored (p < 0.05) the liver antioxidant enzymes, inflammatory cytokines, serum biochemicals, GP width, and tibia weight as compared to the TD group. The PTE administration significantly increased (p < 0.05) growth performance, vascularization, AKT (serine/threonine-protein kinase), and PI3K expressions and the number of hepatocytes and chondrocytes with intact nuclei were enhanced. In conclusion, PTE has the potential to heal TD lesions and act as an antioxidant and anti-inflammatory drug in chickens exposed to thiram via the upregulation of AKT and PI3K expressions.

Ligustrazine recovers thiram-induced tibial dyschondroplasia in chickens: Involvement of new molecules modulating integrin beta 3

Tetramethyl thiuram disulfide (thiram) is a dithiocarbamate, which is extensively used in agriculture as pesticide and fungicide for treating grains intended for seed purposes and also for storing food grains. One of the most evident and detrimental effect produced by thiram is tibial dyschondroplasia (TD) in many avian species, by feeding diets containing thiram, a growth plate cartilage disease. TD is characterized by the lack of blood vessels and impaired vascular invasion of the hypertrophic chondrocyte resulting in the massive cell death. This study investigated the effects of ligustrazine on the treatment and control of thiram induced-TD. A total of 210 chicks were divided into three equal groups (n = 70): control group (received standard diet), TD group (feed on thiram containing diet from day 3-7), and ligustrazine group (feed on thiram containing diet from day 3-7 and after that ligustrazine @ 30 mg/kg from day 8 to day 18). During the experiment, the lameness, production parameters, tibia bone indicators, pathological index changes and integrin beta 3 (ITGB3) expressions were examined. The results reveal that ligustrazine plays an important role in improving angiogenesis and decreasing chondrocytes damage in TD chicks via a new molecule modulating ITGB3. So, the administration of ligustrazine can be an important way to cope with the losses and costs associated with TD in commercial poultry farming and animal welfare issue due to environmental contamination of thiram.

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 tetramethyl thiuram disulfide (thiram) in relation to tibial dyschondroplasia in chickens

Tetramethyl thiuram disulfide (thiram) is one of the important pesticides, which is extensively used in agriculture, but if it is combined with the cell membrane, then it causes membrane damage, bone morphogenic inactivation, and inhibited angiogenesis. Thiram has been considered a common cause of tibial dyschondrolplasia (TD) in various avian species, because it becomes the part of feed due to environmental contamination and its overuse in agriculture as pesticides or fungicide. However, there is no systematic study on the changes of the correlation indexes with toxic effect of the thiram in chickens. Therefore, we evaluated the toxic effects of thiram on growth performance of chickens, viscera organ index, pathological changes in tissue, and gene expression associated with osteoblast differentiation, vascularization, and tibial bone development. For this study, 1-day chickens (n = 300) were randomly distributed into two equal groups, control group (normal basal diet) and thiram group (adding thiram 40 mg/kg in basal diet). The result presented that thiram group chickens were looking unhealthy, lazy, and showing clinical symptoms like lameness. Thiram treatment significantly reduced the performance of chickens, liver index, and tibial length compared with control group. The toxic effect of thiram increased the visceral organ index (spleen and cardiac), tibia index, and TD severity considerably. It also increased serum Ca²⁺ and P³⁺ concentration and decreased tibial density compared to control chickens but the difference was not significant. Histopathology of tibia and liver showed that there were severe lesions due to toxic effect of thiram. Furthermore, HIF-1α and VEGF antibody localizations were increased and WNT4 localization was reduced significantly in immunohistochemical analysis. This systemic study of toxic effects of thiram in chicken concluded that thiram reduced the growth performance of chickens through decreasing liver index, whereas increasing kidney, cardiac, and spleen index, and induced TD by changing the expressions of VEGF, HIF-1α, and WNT4.

Role of Angiopoietin-like 4 on Bone Vascularization in Chickens Exposed to High-altitude Hypoxia

The aim of this study was to investigate the role and expression of a novel angiogenic factor (angiopoietin-like 4, ANGPTL4) in tibial growth plates of broiler chickens exposed to high-altitude hypoxia. One-day-old healthy broiler chickens (n = 120) were transported from lowland to a high-altitude hypoxic region (nearly 3,000 m above sea level) and were reared under hypoxic- (natural lower oxygen content) and normoxic conditions (nearly 21% oxygen content) for 14 days. The effect of hypoxia on angiogenesis in the tibial growth plates and hypoxia-inducible factor (HIF)-1α and ANGPTL4 expressions were determined by histological examination, quantitative reverse transcriptase polymerase chain reaction (qRT-PCR), western blot and enzyme-linked immunosorbent assay (ELISA) techniques. The increase in vascular distribution to the hypertrophic chondrocyte zone of tibial growth plates contributed to promoting growth and development of the tibia under hypoxic conditions, which was highly correlated with the upregulation of ANGPTL4 at both the mRNA and protein levels together with activation of HIF-1α under hypoxic conditions. These findings demonstrate that angiogenic factor ANGPTL4 upregulation is involved in tibial growth plate angiogenesis to promote the development of the tibia in broiler chickens under hypoxic conditions. They also suggest that ANGPTL4 may serve as a new molecular therapeutic target for ameliorating tibial dyschondroplasia chicken bone vascularization.

Role and regulation of growth plate vascularization during coupling with osteogenesis in tibial dyschondroplasia of chickens

Tibial dyschondroplasia (TD) is the most-prevalent leg disorder in fast-growing chickens; it is intractable and characterized by abnormal endochondral bone formation of proximal tibial growth-plates (TGPs). Previous studies have shown that bone is a highly vascularized tissue dependent on the coordinated coupling between angiogenesis and osteogenesis, but the underlying mechanisms of bone formation and bone remodeling are poorly defined in TD chickens. Here, we observed that inhibition of vasculogenesis and angiogenesis remarkably impaired vascular invasion in the hypertrophic chondrocyte zone of the TGPs, resulting in the massive death of chondrocytes due to a shortage of blood vessels and nutrients. Moreover, the balance of the OPG (osteoprotegerin)/RANKL (receptor activator of nuclear factor-kB ligand) system is also severely disrupted during the osteogenesis process while coupling with angiogenesis, both of which eventually lead to abnormal endochondral bone formation in TD chickens. Thus, the process of vascular formation in endochondral bone appears to initiate the pathological changes in TD, and improvement of this process during coupling with osteogenesis may be a potential therapeutic approach to treat this intractable disease.

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.

Tibial dyschondroplasia is highly associated with suppression of tibial angiogenesis through regulating the HIF-1α/VEGF/VEGFR signaling pathway in chickens

Tibial dyschondroplasia (TD) is an intractable poultry problem that is characterized by the appearance of non-vascularized and non-mineralized cartilage masses in tibial growth plates (TGPs). However, the role of angiogenesis inhibition in the occurrence of TD remains unknown. In this study, we found that, compared to low-altitude Arbor Acres chickens (AACs), high-altitude Tibetan chickens showed higher tibial vascular distributions that were accompanied by up-regulation of hypoxia-inducible factor-1α (HIF-1α), vascular endothelial growth factor A (VEGFA) and VEGF receptors. These observations provide insights into hypoxia-induced angiogenesis, which may be related to the absence of TD in high-altitude native Tibetan chickens. Importantly, hypoxia experiments also showed that during hypoxia, tibial angiogenesis was enhanced, which was due to pro-angiogenic factor up-regulation (including VEGFA, VEGFR1, VEGFR2, and IL-8), in AACs. Moreover, we observed that thiram-induced TD could strongly inhibit tibial angiogenesis in the hypertrophic zone through coordinated down-regulation of HIF-1α and pro-angiogenic factors, leading to a disruption in the blood supply to the TGP. Taken together, these findings reveal that the occurrence of TD is highly associated with inhibition of tibial angiogenesis through down-regulated expression of HIF-1α, VEGFA and VEGF receptors, which results in suppression of TGP development.

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.