Effects of Active Vitamin D or FGF23 Antibody on Hyp Mice Dentoalveolar Tissues

Mutations in the PHEX gene lead to X-linked hypophosphatemia (XLH), a form of inherited rickets featuring elevated fibroblast growth factor 23 (FGF23), reduced 1,25-dihydroxyvitamin D (1,25D), and hypophosphatemia. Hyp mutant mice replicate the XLH phenotype, including dentin, alveolar bone, and cementum defects. We aimed to compare effects of 1,25D versus FGF23-neutralizing antibody (FGF23Ab) monotherapies on Hyp mouse dentoalveolar mineralization. Male Hyp mice, either injected subcutaneously with daily 1,25D or thrice weekly with FGF23 blocking antibody from 2 to 35 d postnatal, were compared to wild-type (WT) controls and untreated Hyp mice. Mandibles were analyzed by high-resolution micro-computed tomography (micro-CT), histology, and immunohistochemistry. Both interventions maintained normocalcemia, increased serum phosphate levels, and improved dentoalveolar mineralization in treated versus untreated Hyp mice. 1,25D increased crown dentin volume and thickness and root dentin/cementum volume, whereas FGF23Ab effects were limited to crown dentin volume. 1,25D increased bone volume fraction, bone mineral density, and tissue mineral density in Hyp mice, whereas FGF23Ab failed to significantly affect these alveolar bone parameters. Neither treatment fully attenuated dentin and bone defects to WT levels, and pulp volumes remained elevated regardless of treatment. Both treatments reduced predentin thickness and improved periodontal ligament organization, while 1,25D promoted a more profound improvement in acellular cementum thickness. Altered cell densities and lacunocanalicular properties of alveolar and mandibular bone osteocytes and cementocytes in Hyp mice were partially corrected by either treatment. Neither treatment normalized the altered distributions of bone sialoprotein and osteopontin in Hyp mouse alveolar bone. Moderate improvements from both 1,25D and FGF23Ab treatment regimens support further studies and collection of oral health data from subjects receiving a newly approved anti-FGF23 therapy. The inability of either treatment to fully correct Hyp mouse dentin and bone prompts further experiments into underlying pathological mechanisms to identify new therapeutic approaches.

Role of Discoidin Domain Receptor 2 in Craniofacial Bone Regeneration

Bone loss caused by trauma, neoplasia, congenital defects, or periodontal disease is a major cause of disability and human suffering. Skeletal progenitor cell-extracellular matrix interactions are critical for bone regeneration. Discoidin domain receptor 2 (DDR2), an understudied collagen receptor, plays an important role in skeletal development. Ddr2 loss-of-function mutations in humans and mice cause severe craniofacial and skeletal defects, including altered cranial shape, dwarfing, reduced trabecular and cortical bone, alveolar bone/periodontal defects, and altered dentition. However, the role of this collagen receptor in craniofacial regeneration has not been examined. To address this, calvarial subcritical-size defects were generated in wild-type (WT) and Ddr2-deficient mice. The complete bridging seen in WT controls at 4 wk postsurgery was not observed in Ddr2-deficient mice even after 12 wk. Quantitation of defect bone area by micro-computed tomography also revealed a 50% reduction in new bone volume in Ddr2-deficient mice. Ddr2 expression during calvarial bone regeneration was measured using Ddr2-LacZ knock-in mice. Expression was restricted to periosteal surfaces of uninjured calvarial bone and, after injury, was detected in select regions of the defect site by 3 d postsurgery and expanded during the healing process. The impaired bone healing associated with Ddr2 deficiency may be related to reduced osteoprogenitor or osteoblast cell proliferation and differentiation since knockdown/knockout of Ddr2 in a mesenchymal cell line and primary calvarial osteoblast cultures reduced osteoblast differentiation while Ddr2 overexpression was stimulatory. In conclusion, Ddr2 is required for cranial bone regeneration and may be a novel target for therapy.

The impact of exogenous dietary nucleotides in ameliorating Clostridium perfringens infection and improving intestinal barriers gene expression in broiler chicken

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Nucleotides are an integral part of the genetic information in each cell.

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Nucleotides are naturally present in all feeds of animal and vegetable origin but lower concentrations.

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Dietary nucleotides improve the intestinal barrier function and intestinal histomorphology which positively reflected on the growth performance of C.perfringens infected chickens.

The current study aimed to evaluate the efficiency of dietary nucleotides-supplementation on broiler chickens to alleviate the intestinal Clostridium perfringens (C. perfringens) levels and its adverse effect on gut and growth performance parameters. In this study, a total of 270 one-day-old mixed broiler chicks (Cobb 500) were randomly divided into six treatment groups with three replicates of 15 chicks/ replicate. Treatment 1 (CX), a negative control group was fed corn-soybean basal diet without added nucleotides. Treatment 2 (CN 0.05) and treatment 3 (CN 0.1), consisted of chicks were fed the basal diet with the addition of nucleotides on top at two levels (0.05 and 0.1%) respectively. Treatment 4 (PX), treatment 5 (PN 0.05), and treatment 6 (PN 0.1) consisted of chicks that were challenged with C. perfringens inoculum (~4 × 10⁸ CFU/ml) on day 14, 15, 16 and 17of the experiment and were fed diets similar to treatments 1, 2, and 3 respectively. The trial continued for 35 days. At the end of the experiment, the intestinal C. perfringens counts, microscopic lesion scores, intestinal histomorphology, intestinal barriers (occludin and mucin mRNA expression) and growth parameters were determined. The results showed that the pathogen challenge significantly (P˂0.05) increased both C. perfringens levels and intestinal lesion scores. Which adversely affects intestinal barriers and intestinal histomorphology resulting in a significant decrease (P˂0.05) in body weight gain (BWG) with an increase in feed conversion ratio (FCR). Whereas, nucleotides-supplementation, at 0.1%, significantly decreased both C. perfringens levels and intestinal lesion scores, and significantly improved intestinal barriers and intestinal histomorphology which consequently resulted in improved growth performance parameters to be nearly the same as that of the control un-supplemented group. In conclusion, nucleotides markedly ameliorated the negative effects of C. perfringens challenge by improving the intestinal barrier function and intestinal histomorphology which positively reflected on the growth performance of challenged birds.