KR‑12‑a6 promotes the osteogenic differentiation of human bone marrow mesenchymal stem cells via BMP/SMAD signaling

Antimicrobial peptides in bone regeneration: mechanism and potential

INTRODUCTION

Antimicrobial peptides (AMPs) are small-molecule peptides with a unique antimicrobial mechanism. Other notable biological activities of AMPs, including anti-inflammatory, angiogenesis, and bone formation effects, have recently received widespread attention. These remarkable bioactivities, combined with the unique antimicrobial mechanism of action of AMPs, have led to their increasingly important role in bone regeneration.

AREAS COVERED

In this review, on the one hand, we aimed to summarize information about the AMPs that are currently used for bone regeneration by reviewing published literature in the PubMed database. On the other hand, we also highlight some AMPs with potential roles in bone regeneration and their possible mechanisms of action.

EXPERT OPINION

The translation of AMPs to the clinic still faces many problems, but their unique antimicrobial mechanisms and other conspicuous biological activities suggest great potential. An in-depth understanding of the structure and mechanism of action of AMPs will help us to subsequently combine AMPs with different carrier systems and perform structural modifications to reduce toxicity and achieve stable release, which may be a key strategy for facilitating the translation of AMPs to the clinic.

Functional mechanism of miR-92b-3p in osteogenic differentiation of fibroblasts in patients with ankylosing spondylitis via the TOB1/BMP/Smad pathway

BACKGROUND

Ankylosing spondylitis (AS) is a chronic inflammatory arthritis. Upregulation of microRNA (miR)-92b-3p is associated with enhanced osteoblastic differentiation. The current study sought to investigate the functional mechanism of miR-92b-3p in osteogenic differentiation of AS fibroblasts.

METHODS

First, fibroblasts were isolated from AS and non-AS patients and cultured. Next, cell morphology was observed, cell proliferation was assessed and the vimentin expression pattern was determined. Alkaline phosphatase (ALP) activity and levels of osteogenic markers RUNX2, OPN, OSX, and COL I were additionally measured, followed by determination of miR-92b-3p and TOB1 levels. The binding site of miR-92b-3p and TOB1 was predicted, and their target relationship was validated. Lastly, miR-92b-3p inhibitor, si-TOB1, and the BMP/Smad signaling pathway inhibitor LDN193189 were delivered into AS fibroblasts to evaluate the osteogenic differentiation of AS fibroblasts and the activation of the BMP/Smad pathway.

RESULTS

miR-92b-3p was highly expressed in AS fibroblasts. AS fibroblasts showed enhanced osteogenic differentiation and proliferation, while inhibition of miR-92b-3p suppressed osteogenic differentiation and proliferation of AS fibroblasts. miR-92b-3p targeted TOB1, and TOB1 was poorly expressed in AS fibroblasts. The concurrent downregulation of TOB1 and inhibition of miR-92b-3p elevated the levels of RUNX2, OPN, OSX, and COL I and ALP activity and further enhanced the proliferation of AS fibroblasts. The BMP/Smad pathway was activated in AS fibroblasts. Silencing miR-92b-3p could inhibit the activation of the BMP/Smad pathway by upregulating TOB1. Inhibition of the BMP/Smad pathway reduced the number of calcified nodules and hindered the osteogenic differentiation and proliferation of AS fibroblasts.

CONCLUSION

Our findings highlighted that silencing miR-92b-3p inhibited the osteogenic differentiation and proliferation of AS fibroblasts by upregulation of TOB1 and inhibition of the BMP/Smad pathway.

Strategies in Translating the Therapeutic Potentials of Host Defense Peptides

The golden era of antibiotics, heralded by the discovery of penicillin, has long been challenged by the emergence of antimicrobial resistance (AMR). Host defense peptides (HDPs), previously known as antimicrobial peptides, are emerging as a group of promising antimicrobial candidates for combatting AMR due to their rapid and unique antimicrobial action. Decades of research have advanced our understanding of the relationship between the physicochemical properties of HDPs and their underlying antimicrobial and non-antimicrobial functions, including immunomodulatory, anti-biofilm, and wound healing properties. However, the mission of translating novel HDP-derived molecules from bench to bedside has yet to be fully accomplished, primarily attributed to their intricate structure-activity relationship, toxicity, instability in host and microbial environment, lack of correlation between in vitro and in vivo efficacies, and dwindling interest from large pharmaceutical companies. Based on our previous experience and the expanding knowledge gleaned from the literature, this review aims to summarize the novel strategies that have been employed to enhance the antimicrobial efficacy, proteolytic stability, and cell selectivity, which are all crucial factors for bench-to-bedside translation of HDP-based treatment. Strategies such as residues substitution with natural and/or unnatural amino acids, hybridization, L-to-D heterochiral isomerization, C- and N-terminal modification, cyclization, incorporation with nanoparticles, and "smart design" using artificial intelligence technology, will be discussed. We also provide an overview of HDP-based treatment that are currently in the development pipeline.