Overview of signal transduction between LL37 and bone marrow-derived MSCs

Molecular roles in membrane receptor signaling pathways and cascade reactions in chondrocytes: a review

Articular cartilage (AC) is a specialized connective tissue with unique biological and mechanical properties, which depends on the biological effects of each resident chondrocyte and its surrounding extracellular matrix (ECM) to form a unit that operates in a constant and balanced feedback loop. The surface membrane receptors of chondrocytes play a crucial role in the feedback balance of this biological unit. Various biological signals outside chondrocytes, such as water-soluble chemical signal molecules and mechanical signals, are unable to directly enter the cell and must first bind to the plasma membrane receptors to induce changes in the level and activity of intracellular signal transduction molecules. These changes then transmit through signaling cascade pathways into the nucleus, changing the cell phenotype, and producing physiological or pathological changes. Specific chemical and mechanical signals break the feedback balance of cartilage tissue units through membrane receptors. In the ECM environment, the molecular actions of chondrocyte membrane receptors in response to these specific signals, along with associated ion channel receptors, collectively regulate the biological effects of chondrocytes. This leads to decreased chondrocyte survival and an imbalance in ECM regulation, ultimately disrupting the tissue's molecular framework and physiological feedback mechanisms, and resulting in pathological changes in cartilage tissue. To provide insights into addressing the complexities associated with cartilage tissue injury and repair engineering, this review provides a comprehensive overview of the molecular mechanisms and biological implications of chondrocyte membrane receptor-mediated signal transduction, including G protein-coupled receptors (GPCRs), enzyme-linked receptors (tyrosine kinase receptors (TKRs)), and integrin receptors.

LL-37 regulates odontogenic differentiation of dental pulp stem cells in an inflammatory microenvironment

BACKGROUND

Inflammation often causes irreversible damage to dental pulp tissue. Dental pulp stem cells (DPSCs), which have multidirectional differentiation ability, play critical roles in the repair and regeneration of pulp tissue. However, the presence of proinflammatory factors can affect DPSCs proliferation, differentiation, migration, and other functions. LL-37 is a natural cationic polypeptide that inhibits lipopolysaccharide (LPS) activity, enhances cytokine production, and promotes the migration of stem cells. However, the potential of LL-37 in regenerative endodontics remains unknown. This study aimed to investigate the regulatory role of LL-37 in promoting the migration and odontogenic differentiation of DPSCs within an inflammatory microenvironment. These findings establish an experimental foundation for the regenerative treatment of pulpitis and provide a scientific basis for its clinical application.

MATERIALS AND METHODS

DPSCs were isolated via enzyme digestion combined with the tissue block adhesion method and identified via flow cytometry. The impact of LL-37 on the proliferation of DPSCs was evaluated via a CCK-8 assay. The recruitment of DPSCs was assessed through a transwell assay. The mRNA expression levels of inflammatory and aging-related genes were assessed via reverse transcription‒polymerase chain reaction (RT‒PCR), western blotting, and enzyme‒linked immunosorbent assay (ELISA). The odontogenic differentiation of DPSCs was assessed through alkaline phosphatase (ALP) staining, alizarin red staining, and RT‒PCR analysis.

RESULTS

LL-37 has the potential to enhance the migration of DPSCs. In an inflammatory microenvironment, LL-37 can suppress the expression of genes associated with inflammation and aging, such as TNF-α, IL-1β, IL-6, P21, P38 and P53. Moreover, it promotes odontogenic differentiation in DPSCs by increasing ALP activity, increasing calcium nodule formation, and increasing the expression of dentin-related genes such as DMP1, DSPP and BSP.

CONCLUSION

These findings suggest that the polypeptide LL-37 facilitates the migration of DPSCs and plays a crucial role in resolving inflammation and promoting cell differentiation within an inflammatory microenvironment. Consequently, LL-37 has promising potential as an innovative therapeutic approach for managing inflammatory dental pulp conditions.

Antimicrobial peptides and proteins against drug-resistant pathogens

The rise of drug-resistant pathogens, driven by the misuse and overuse of antibiotics, has created a formidable challenge for global public health. Antimicrobial peptides and proteins have garnered considerable attention as promising candidates for novel antimicrobial agents. These bioactive molecules, whether derived from natural sources, designed synthetically, or predicted using artificial intelligence, can induce lethal effects on pathogens by targeting key microbial structures or functional components, such as cell membranes, cell walls, biofilms, and intracellular components. Additionally, they may enhance overall immune defenses by modulating innate or adaptive immune responses in the host. Of course, development of antimicrobial peptides and proteins also face some limitations, including high toxicity, lack of selectivity, insufficient stability, and potential immunogenicity. Despite these challenges, they remain a valuable resource in the fight against drug-resistant pathogens. Future research should focus on overcoming these limitations to fully realize the therapeutic potential of antimicrobial peptides in the infection control.

Recent Research on Hybrid Hydrogels for Infection Treatment and Bone Repair

The repair of infected bone defects (IBDs) is still a great challenge in clinic. A successful treatment for IBDs should simultaneously resolve both infection control and bone defect repair. Hydrogels are water-swollen hydrophilic materials that maintain a distinct three-dimensional structure, helping load various antibacterial drugs and biomolecules. Hybrid hydrogels may potentially possess antibacterial ability and osteogenic activity. This review summarizes the recent progress of different kinds of antibacterial agents (including inorganic, organic, and natural) encapsulated in hydrogels. Several representative hydrogels of each category and their antibacterial mechanism and effect on bone repair are presented. Moreover, the advantages and disadvantages of antibacterial agent hybrid hydrogels are discussed. The challenge and future research directions are further prospected.