LRP3

Objective: To investigate the influence of reactive oxygen species (ROS) responsive self-assembled nanomicelle loaded with pyroptosis inhibitor on full-thickness skin defects in diabetic rats. Methods: Experimental research methods were employed. A nucleotide-binding oligomerization domain (NOD) 1/2 inhibitor (NOD-IN-1) was encapsulated with nanomicelle polyethylene glycol-block-polypropylene sulfide (PEG-b-PPS), and the resulting product was called PEPS@NOD-IN-1. The morphology and hydration particle size of PEG-b-PPS and PEPS@NOD-IN-1 were observed by transmission electron microscope and particle size analyzer, respectively, and the encapsulation rate and drug loading rate of PEPS@NOD-IN-1 to NOD-IN-1 and the cumulative release rate of NOD-IN-1 by PEPS@NOD-IN-1 in phosphate buffer solution (PBS) alone and hydrogen peroxide-containing PBS within 40 h were measured and calculated by microplate reader, and the sample number was 3. Twenty-four male Sprague-Dawley rats aged 6-7 weeks were injected with streptozotocin to induce type 1 diabetes mellitus. Six full-thickness skin defect wounds were made on the back of each rat. The injured rats were divided into PBS group, NOD-IN-1 group, PEG-b-PPS group, and PEPS@NOD-IN-1 group with corresponding treatment according to the random number table, with 6 rats in each group. The wound healing was observed on post injury day (PID) 3, 7, and 12, and the wound healing rate was calculated. The ROS levels in wound tissue were detected by immunofluorescence method on PID 3. On PID 7, the granulation tissue thickness in wound was assessed by hematoxylin-eosin staining, the mRNA expressions of NOD1 and NOD2 were detected by real-time fluorescence quantitative reverse transcription polymerase chain reaction, and the protein expressions of NOD1, NOD2, and GSDMD-N terminals were detected by Western blotting. Six wounds from different rats in each group were taken for detection of the above indicators. Wound tissue (3 samples per group) was taken from rats in PBS group and PEPS@NOD-IN-1 group on PID 7, and transcriptome sequencing was performed using high-throughput sequencing technology platform. Differentially expressed genes (DEGs) significantly down-regulated in PEPS@NOD-IN-1 group as compared with PBS group were screened, and the enrichment analysis of Kyoto Encyclopedia of Genes and Genomes (KEGG) was performed. The DEG heatmap of the NOD-like receptor pathway, a pyroptosis-related pathway, was made. Protein-protein interaction (PPI) analysis of DEGs in heatmap was performed through the STRING database to screen key genes of PEPS@NOD-IN-1 regulating the NOD-like receptor pathway. Data were statistically analyzed with analysis of variance for repeated measurement, one-way analysis of variance, and Tukey test. Results: PEG-b-PPS and PEPS@NOD-IN-1 were in spherical structures of uniform size, with hydration particle sizes of (134.2±3.3) and (143.1±2.3) nm, respectively. The encapsulation rate of PEPS@NOD-IN-1 to NOD-IN-1 was (60±5)%, and the drug loading rate was (15±3)%. The release of NOD-IN-1 from PEPS@NOD-IN-1 in PBS alone was slow, and the cumulative release rate at 40 h was only (12.4±2.3)%. The release of NOD-IN-1 from PEPS@NOD-IN-1 in hydrogen peroxide-containing PBS within 10 h was very rapid, and the cumulative release rate at 10 h reached (90.1±3.6)%. On PID 3 and 7, the wounds of rats in the four groups were gradually healed, and the healing in PEPS@NOD-IN-1 group was better than that in the other three groups. On PID 12, the wound scab area in PBS group was large, the wound epithelialization in NOD-IN-1 group and PEG-b-PPS group was obvious, and the wound in PEPS@NOD-IN-1 group was close to complete epithelialization. Compared with those in PBS group, NOD-IN-1 group, and PEG-b-PPS group, the wound healing rates on PID 7 and 12 in PEPS@NOD-IN-1 group were significantly increased (P<0.05), the level of ROS in wound tissue on PID 3 was significantly decreased (P<0.05), the thickness of granulation tissue in wound on PID 7 was significantly thickened (P<0.05), and the mRNA expressions of NOD1 and NOD2 and the protein expressions of NOD1, NOD2, and GSDMD-N terminals in wound tissue on PID 7 were significantly decreased (P<0.05). KEGG pathway analysis showed that DEGs significantly down-regulated in PEPS@NOD-IN-1 group as compared with PBS group were significantly enriched in NOD-like receptors, hypoxia-inducible factors, mitogen-activated protein kinases, and tumor necrosis factor (TNF) pathways. In the DEG heatmap of NOD-like receptor pathway, the genes regulating pyroptosis mainly involved NOD1, NOD2, NOD-like receptor thermoprotein domain-related protein 3, Jun, signal transduction and transcriptional activator 1 (STAT1), TNF-α-induced protein 3. The PPI results showed that NOD1, NOD2, and STAT1 were the key genes of PEPS@NOD-IN-1 regulating the NOD-like receptor pathway. Conclusions: PEPS@NOD-IN-1 can down-regulate the level of local ROS in wounds and the expression of NOD1, NOD2, and GSDMD-N terminals, the key regulators of pyroptosis, thereby promoting the repair of full-thickness skin defect wounds in diabetic rats. PEPS@NOD-IN-1 can also significantly down-regulate the pyroptosis, inflammation, and hypoxia-related pathways of wounds, and regulate NOD-like receptor pathways by down-regulating key genes NOD1, NOD2, and STAT1.

Lipoprotein receptors, including low-density lipoprotein receptor (LDLr) relatives (Lrs) and LDLr-related proteins (Lrps), belong to the LDLr supergene family and participate in diverse physiological functions. In this study, novel sequences of lr and lrp genes expressed in the ovary of the short-finned eel, Anguilla australis, during early gonadal development are presented. The genes encoding the LDLr-like, Lrp1-like, Lrp1b-like, Lrp3, Lrp4-like, Lrp5-like, Lrp6, Lrp10, Lrp11, Lrp12-like, and Lr11-like proteins were found and identified by sequence and structure analysis, in addition to phylogenetic analysis. Genes encoding proteins previously implicated in follicle development and vitellogenin (Vtg) uptake in oviparous vertebrates were also identified, i.e. lr8 (including lr8 + and lr8- variants) and lrp13; their identification was reinforced by conserved synteny with orthologues in other teleost fish. Compared to other lr/lrp genes, the genes encoding Lr8 + , Lr8-, and Lrp13 were highly expressed in ovary during early development, decreasing as oocyte development advanced when induced by hypophysation. Furthermore, lr8 + , lr8-, and lrp13 were dominantly expressed in the ovary when compared with 17 other tissues. Finally, this study successfully detected the expression of both lr8 variants, which showed different expression patterns to those reported in other oviparous vertebrates and provided the first characterisation of Lrp13 in Anguilla sp. We propose that lr8 + , lr8-, and lrp13 encode putative Vtg receptors in anguillid eels.

Emerging evidence suggests that osteoarthritis is associated with high cholesterol levels in some osteoarthritis patients. However, the specific mechanism under this metabolic osteoarthritis phenotype remains unclear. We find that cholesterol metabolism-related gene, LRP3 (low-density lipoprotein receptor-related protein 3) is significantly reduced in high-cholesterol diet mouse's cartilage. By using Lrp3^-/- mice in vivo and LRP3 lentiviral-transduced chondrocytes in vitro, we identify that LRP3 positively regulate chondrocyte extracellular matrix metabolism, and its deficiency aggravate the degeneration of cartilage. Regardless of diet, LRP3 overexpression in cartilage attenuate anterior cruciate ligament transection induced osteoarthritis progression in rats and Lrp3 knockout-induced osteoarthritis progression in mice. LRP3 knockdown upregulate syndecan-4 by activating the Ras signaling pathway. We identify syndecan-4 as a downstream molecular target of LRP3 in osteoarthritis pathogenesis. These findings suggest that cholesterol-LRP3- syndecan-4 axis plays critical roles in osteoarthritis development, and LRP3 gene therapy may provide a therapeutic regimen for osteoarthritis treatment.