Prolyl-hydroxylase inhibitor-induced regeneration of alveolar bone and soft tissue in a mouse model of periodontitis through metabolic reprogramming

Vitamin A family suppresses periodontitis by restoring mitochondrial metabolic reprogramming in macrophages through JAK-STAT pathway

Objective

Mitochondrial metabolic reprogramming in macrophages is crucial in the development and progression of inflammation. Given vitamin A's antioxidant properties and its therapeutic effects on inflammation, this study aims to elucidate how vitamin A influences mitochondrial metabolic reprogramming in inflammatory states, specifically in periodontitis, through genetic bioinformatics and experimental methods.

Method

The study utilized the GSE16134 dataset from the Gene Expression Omnibus (GEO) database, focusing on human periodontitis. Vitamin A-targeted genes (ATGs) were identified and analyzed using CIBERSORT to explore their role in inflammation. Cluster analysis revealed two phenotypes associated with ATGs, showing differential expression of genes like COX1, IL-1β, and STAT3, and immune activation patterns. Weighted Gene Co-expression Network Analysis (WGCNA) identified 145 markers correlated with ATG-guided phenotypes and inflammation. Machine learning models, combined with Gene Set Variation Analysis (GSVA), identified five key genes (RGS1, ACAT2, KDR, TUBB2A, TDO2) linked to periodontitis. Cell Type-Specific Enrichment Analysis (CSEA) highlighted macrophages as critical in metabolic reprogramming, validated by external datasets with an AUC of 0.856 in GSE10334 and 0.750 in GSE1730678. Experimental validation showed vitamin A's role in suppressing endoplasmic reticulum stress and altering mitochondrial dynamics, as well as metabolic reprogramming influencing inflammation via the STAT3 pathway in RAW 264.7 cells.

Results

The study identified 13 differentially expressed ATGs in periodontitis, showing strong correlations with inflammation, particularly in plasma cells, macrophages, dendritic cells, neutrophils, and mast cells. Two ATG-guided phenotypes were identified, differing in gene expression and immune activation. WGCNA and machine learning models identified 145 markers and five key genes associated with periodontitis. GSVA and CSEA analyses highlighted the JAK-STAT pathway and macrophage involvement in metabolic reprogramming. Experimental data confirmed vitamin A's effects on mitochondrial dynamics and metabolic reprogramming through the STAT3 pathway.

Conclusion

The study demonstrates that vitamin A's therapeutic effect on periodontitis is mediated through JAK-STAT pathway-guided mitochondrial metabolic reprogramming in macrophages. It identifies two genetic and immune-related phenotypes and five genetic identifiers associated with periodontitis risk.

Synergistic effect of ROS-generating polydopamine on drug-induced bone tissue regeneration

A PHD (prolyl hydroxylase) inhibitor, 1,4-dihydrophenonthrolin-4-one-3-carboxylic acid (1,4-DPCA), is a drug that can artificially promote tissue regeneration by enhancing metabolic activity through the upregulation of hypoxia inducible factor 1 subunit alpha (Hif-1α) under normoxic conditions. This study presents a novel design methodology for a drug delivery system to maximize the regenerative effect of 1,4-DPCA. Specifically, by encapsulating 1,4-DPCA in polydopamine (PDA) that generates reactive oxygen species (ROS), the combined effects of Hif-1α upregulation and the induction of cellular antioxidant defense mechanisms by localized ROS can significantly enhance tissue regeneration. The study confirmed that each material (PDA and 1,4-DPCA) triggers a positive synergistic effect on the regenerative mechanisms. As a result, the use of a PDA drug delivery system loaded with 1,4-DPCA showed approximately six times greater bone regeneration compared to the control (no treatment) in a mouse calvarial defect model.

A Pro-Regenerative Supramolecular Prodrug Protects Against and Repairs Colon Damage in Experimental Colitis

Structural repair of the intestinal epithelium is strongly correlated with disease remission in inflammatory bowel disease (IBD); however, ulcer healing is not addressed by existing therapies. To address this need, this study reports the use of a small molecule prolyl hydroxylase (PHD) inhibitor (DPCA) to upregulate hypoxia-inducible factor one-alpha (HIF-1α) and induce mammalian regeneration. Sustained delivery of DPCA is achieved through subcutaneous injections of a supramolecular hydrogel, formed through the self-assembly of PEG-DPCA conjugates. Pre-treatment of mice with PEG-DPCA is shown to protect mice from epithelial erosion and symptoms of dextran sodium sulfate (DSS)-induced colitis. Surprisingly, a single subcutaneous dose of PEG-DPCA, administered after disease onset, leads to accelerated weight gain and complete restoration of healthy tissue architecture in colitic mice. Rapid DPCA-induced restoration of the intestinal barrier is likely orchestrated by increased expression of HIF-1α and associated targets leading to an epithelial-to-mesenchymal transition. Further investigation of DPCA as a potential adjunctive or stand-alone restorative treatment to combat active IBD is warranted.

Epithelial-mesenchymal transition: an organizing principle of mammalian regeneration

Introduction: The MRL mouse strain is one of the few examples of a mammal capable of healing appendage wounds by regeneration, a process that begins with the formation of a blastema, a structure containing de-differentiating mesenchymal cells. HIF-1α expression in the nascent MRL wound site blastema is one of the earliest identified events and is sufficient to initiate the complete regenerative program. However, HIF-1α regulates many cellular processes modulating the expression of hundreds of genes. A later signal event is the absence of a functional G1 checkpoint, leading to G2 cell cycle arrest with increased cellular DNA but little cell division observed in the blastema. This lack of mitosis in MRL blastema cells is also a hallmark of regeneration in classical invertebrate and vertebrate regenerators such as planaria, hydra, and newt. Results and discussion: Here, we explore the cellular events occurring between HIF-1α upregulation and its regulation of the genes involved in G2 arrest (EVI-5, γH3, Wnt5a, and ROR2), and identify epithelial-mesenchymal transition (EMT) (Twist and Slug) and chromatin remodeling (EZH-2 and H3K27me3) as key intermediary processes. The locus of these cellular events is highly regionalized within the blastema, occurring in the same cells as determined by double staining by immunohistochemistry and FACS analysis, and appears as EMT and chromatin remodeling, followed by G2 arrest determined by kinetic expression studies.