Mouse β-defensin-14 for inducing the maturation of dendritic cells

Yak DEFB123 alleviates lung injury caused by Klebsiella pneumoniae through MAPKs signaling pathway

Beta-defensins, such as β-defensin 123 (DEFB123), are vital components of the immune system's defense against infections due to their strong antimicrobial properties and capacity for modulating the body's immunological responses. In this study, we successfully cloned and analyzed the yak DEFB123 gene sequence. Subsequently, we obtained recombinant protein DEFB123 (rDEFB123) through prokaryotic expression. Our results demonstrate that rDEFB123 effectively inhibits the growth of Escherichia coli, Klebsiella pneumoniae, and Staphylococcus aureus. Furthermore, rDEFB123 enhances the phagocytic activity of macrophages by regulating specific factors. In a mouse model infected with Klebsiella pneumoniae, the administration of rDEFB123 showed significantly lower levels of serum ALT and AST compared to the control group. Moreover, IFN-γ and IgG were significantly increased in the rDEFB123-treated groups, indicating an enhanced immune response. In the MAPKs signaling pathway of the infected mouse lungs, the expressions of JNK, TRAF2, TRAF6, MIF, and IL-1β genes were downregulated in the rDEFB123-treated groups. Moreover, the levels of p-JNK protein were significantly decreased in these groups as well. Klebsiella pneumoniae caused systemic infection with organ damage in mice. However, the administration of rDEFB123 suppressed the expressions of inflammatory factors, thereby mitigating organ injury and regulating the activity of apoptosis-related factors to enhance immunity. These findings provide valuable theoretical data for future exploration of the functionality and potential applications of DEFB123 in yak.

Defensins regulate cell cycle: Insights of defensins on cellular proliferation and division

Defensins are a class of small antimicrobial peptides that play a crucial role against pathogens. However, recent research has highlighted defensins exhibit the ability to influence cell cycle checkpoints, promoting or inhibiting specific phases such as G1 arrest or S/M transition. By regulating the cell cycle, defensins impact the proliferation of normal and cancerous cells, with implications for cancer development and progression. Dysregulation of defensin expression can disrupt the delicate balance of cell cycle regulation, leading to uncontrolled cell growth and an increased risk of tumor formation. Defensins contribute to the resolution of inflammation, stimulate angiogenesis, and enhance the migration and proliferation of cells involved in tissue repair. Furthermore, The ability of defensins to respond to microenvironmental changes further demonstrates the significance of these peptides in host defense mechanisms and immune function. By adjusting their expression, defensins continue to combat pathogens effectively and maintain homeostasis within the body. This review highlights the multifaceted role of defensins in regulating the cell cycle and their broader implications in cancer progression, tissue repair, and microenvironmental response.

Defensins: A novel weapon against Mycobacterium tuberculosis?

Tuberculosis (TB) is a serious airborne communicable disease caused by organisms of the Mycobacterium tuberculosis (Mtb) complex. Although the standard treatment antimicrobials, including isoniazid, rifampicin, pyrazinamide, and ethambutol, have made great progress in the treatment of TB, problems including the rising incidence of multidrug-resistant tuberculosis (MDR-TB) and extensively drug-resistant tuberculosis (XDR-TB), the severe toxicity and side effects of antimicrobials, and the low immunity of TB patients have become the bottlenecks of the current TB treatments. Therefore, both safe and effective new strategies to prevent and treat TB have become a top priority. As a subfamily of cationic antimicrobial peptides, defensins are rich in cysteine and play a vital role in resisting the invasion of microorganisms and regulating the immune response. Inspired by studies on the roles of defensins in host defence, we describe their research history and then review their structural features and antimicrobial mechanisms, specifically for fighting Mtb in detail. Finally, we discuss the clinical relevance, therapeutic potential, and potential challenges of defensins in anti-TB therapy. We further debate the possible solutions of the current application of defensins to provide new insights for eliminating Mtb.

The Contribution of Antimicrobial Peptides to Immune Cell Function: A Review of Recent Advances

The development of novel antimicrobial agents to replace antibiotics has become urgent due to the emergence of multidrug-resistant microorganisms. Antimicrobial peptides (AMPs), widely distributed in all kingdoms of life, present strong antimicrobial activity against a variety of bacteria, fungi, parasites, and viruses. The potential of AMPs as new alternatives to antibiotics has gradually attracted considerable interest. In addition, AMPs exhibit strong anticancer potential as well as anti-inflammatory and immunomodulatory activity. Many studies have provided evidence that AMPs can recruit and activate immune cells, controlling inflammation. This review highlights the scientific literature focusing on evidence for the anti-inflammatory mechanisms of different AMPs in immune cells, including macrophages, monocytes, lymphocytes, mast cells, dendritic cells, neutrophils, and eosinophils. A variety of immunomodulatory characteristics, including the abilities to activate and differentiate immune cells, change the content and expression of inflammatory mediators, and regulate specific cellular functions and inflammation-related signaling pathways, are summarized and discussed in detail. This comprehensive review contributes to a better understanding of the role of AMPs in the regulation of the immune system and provides a reference for the use of AMPs as novel anti-inflammatory drugs for the treatment of various inflammatory diseases.

Antibacterial peptides-loaded bioactive materials for the treatment of bone infection

Bacterial bone infection in open fractures is an urgent problem to solve in orthopedics. Antimicrobial peptides (AMPs), as a part of innate immune defense, have good biocompatibility. Their antibacterial mechanism and therapeutic application against bacteria have been widely studied. Compared with traditional antibiotics, AMPs do not easily cause bacterial resistance and can be a reliable substitute for antibiotics in the future. Therefore, various physical and chemical strategies have been developed for the combined application of AMPs and bioactive materials to infected sites, which are conducive to maintaining the local stability of AMPs, reducing many complications, and facilitating bone infection resolution. This review explored the molecular structure, function, and direct and indirect antibacterial mechanisms of AMPs, introduced two important AMPs (LL-37 and β-defensins) in bone tissues, and reviewed advanced AMP loading strategies and different bioactive materials. Finally, the latest progress and future development of AMPs-loaded bioactive materials for the promotion of bone infection repair were discussed. This study provided a theoretical basis and application strategy for the treatment of bone infection with AMP-loaded bioactive materials.

Biomimetic nanofibrous hybrid hydrogel membranes with sustained growth factor release for guided bone regeneration

A biomimetic nanofibrous membrane can immobilize growth factors or agents to obtain sustained release and prolonged effect in tissue engineering.

The Improvement of Immune Effect of Recombinant Human Beta-Defensin 2 on Hepatitis B Vaccine in Mice

Immunization with hepatitis B vaccine is an effective measure for prevention and control of hepatitis B Virus (HBV) infection. Although lots of efforts to improve the effect of hepatitis B vaccine have been made, the function of human beta defensin 2 (hBD2) on hepatitis B vaccine keeps unclear. In this article, we report that hBD2 not only promoted the activation and maturation of immature dendritic cells (iDCs) by increasing MHC II and CD86 expression, but it also significantly upregulated the mRNA level of IL-6 and IL-12B in mouse bone marrow-derived dendritic cells. The serum concentrations of IFN-γ in mice stimulated with 300 ng hBD2 increased from 25.21 to 42.04 pg/mL, with a time extension from 4 to 12 h post-injection. During the process of three times immunization (1, 14, 28 days) with 3 μg hepatitis B vaccine combined with or without 300 ng hBD2 with a 2 week interval in BALB/c mice, the antibody against HBsAg (HBsAb) concentration in serum at every time point of observation in the combined group was statistically higher than the hepatitis B vaccine group. The serum concentration of IgG2a subclass HBsAb on the 14th day post last injection in the combined group was significantly higher than the hepatitis B vaccine group. Further, the splenic cells from the mice treated with both hBD2 and hepatitis B vaccine possessed a greater ability to produce a surface antigen of hepatitis B virus (HBsAg) specific IFN-γ than those treated with hepatitis B vaccine alone. The percentages of CD3⁺/CD4⁺ T cells and CD3⁺/CD8⁺ T lymphocytes in spleens from the mice treated with 300 ng hBD2 were statistically higher than the phosphate buffered saline group. These data suggest that hBD2 improves iDC maturation and the immune efficiency of hepatitis B vaccine in BALB/c mice.

Effect of Bifunctional β Defensin 2-Modified Scaffold on Bone Defect Reconstruction

Bone tissue engineering has emerged as an effective alternative treatment to the problem of bone defect. To repair a bone defect, antibiosis and osteogenesis are two essential aspects of the repair process. By searching the literature and performing exploratory experiments, we found that β defensin 2 (BD2), with bifunctional properties of antibiosis and osteogenesis, was a feasible alternative for traditional growth factors. The antimicrobial ability of BD2 against Staphylococcus aureus and Escherichia coli was studied by the spread plate and live/dead staining methods (low effective concentration of 20 ng/mL). BD2 was also demonstrated to enhance osteogenesis, with higher messenger RNA (mRNA) and protein expression of the osteogenic markers collagen I (Col1), runt-related transcription factor 2 (Runx2), osteopontin (Opn), and osteocalcin (Ocn) in vitro (1.5-2.5-fold increase compared with the control group in the most effective concentration group), which was consistent with the alkaline phosphatase (ALP) and alizarin red S (ARS) staining results. We implanted poly(sebacoyl diglyceride) (PSeD) combined with BD2 and rat bone tissue-derived mesenchymal stem cells (rBMSCs) under the back skin of rats and found that the inflammatory response was significantly lower with this combination than with the PSeD/rBMSCs scaffold without BD2 and the pure PSeD group and was similar to the control group. Importantly, when assessed in a critical-sized in vivo rat 8 m diameter calvaria defect model, a scaffold we developed combining bifunctional BD2 with porous organic polymer displayed an osteogenic effect that was 160-200% greater than the control group. The in vivo study results revealed a significant osteogenic response and antimicrobial effect and were consistent with the in vitro results. In summary, BD2 displayed a great potential of simultaneously promoting bone regeneration and preventing infection and could provide a viable alternative to traditional growth factors applied in bone defect repair.