MiR-27a-3p Targets GLP1R to Regulate Differentiation, Autophagy, and Release of Inflammatory Factors in Pre-Osteoblasts via the AMPK Signaling Pathway

Role of LRP5/6/GSK-3β/β-catenin in the differences in exenatide- and insulin-promoted T2D osteogenesis and osteomodulation

BACKGROUND AND PURPOSE

Insulin and exenatide are two hypoglycaemic agents that exhibit different osteogenic effects. This study compared the differences between exenatide and insulin in osseointegration in a rat model of Type 2 diabetes (T2D) and explored the mechanisms promoting osteogenesis in this model of T2D.

EXPERIMENTAL APPROACH

In vivo, micro-CT was used to detect differences in the peri-implant bone microstructure in vivo. Histology, dual-fluorescent labelling, immunofluorescence and immunohistochemistry were used to detect differences in tissue, cell and protein expression around the implants. In vitro, RT-PCR and western blotting were used to measure the expression of osteogenesis- and Wnt signalling-related genes and proteins in bone marrow mesenchymal stromal cells (BMSCs) from rats with T2D (TBMSCs) after PBS, insulin and exenatide treatment. RT-PCR was used to detect the expression of Wnt bypass cascade reactions under Wnt inactivation.

KEY RESULTS

Micro-CT and section staining showed exenatide extensively promoted peri-implant osseointegration. Both in vivo and in vitro experiments showed exenatide substantially increased the expression of osteogenesis-related and activated the LRP5/6/GSK-3β/β-catenin-related Wnt pathway. Furthermore, exenatide suppressed expression of Bmpr1a to inhibit lipogenesis and promoted expression of Btrc to suppress inflammation.

CONCLUSION AND IMPLICATIONS

Compared to insulin, exenatide significantly improved osteogenesis in T2D rats and TBMSCs. In addition to its dependence on LRP5/6/GSK-3β/β-catenin signalling for osteogenic differentiation, exenatide-mediated osteomodulation also involves inhibition of inflammation and adipogenesis by BMPR1A and β-TrCP, respectively.

miR-27a-3p promotes inflammatory response in infectious endophthalmitis via targeting TSC1

Infectious endophthalmitis (IE) poses a significant threat to vision. This study aimed to explore the impact of microRNA (miR)-27a-3p on inflammation in IE. A rat model was developed through intravitreal injection of lipopolysaccharide. Clinical and demographic data were collected for 54 participants: 31 diagnosed with IE and 23 non-infectious patients with idiopathic macular holes. Expression levels of miR-27a-3p and inflammatory genes were quantified via reverse transcription quantitative polymerase chain reaction. Concentrations of inflammatory cytokines in human vitreous samples were measured using enzyme-linked immunosorbent assay. In vitro studies were conducted to explore the target gene of miR-27a-3p. The final animal experiments further verified the role of miR-27a-3p and tuberous sclerosis complex (TSC)1 in inflammatory responses. Results showed that miR-27a-3p was elevated in LPS-treated rats and IE patients. Thirty-one IE patients were divided into the High (n = 15) and Low (n = 16) groups according to the expression of miR-27a-3p. No significant differences were observed in baseline clinical and demographic characteristics between the control and IE patient groups. Pro-inflammatory cytokine mRNA levels and concentrations were notably increased in both LPS-treated rats and the High group of patients. Besides, results showed that TSC1 is a target gene of miR-27a-3p. Moreover, TSC1 inhibition promoted inflammation in rat vitreous samples. In summary, our findings suggested that miR-27a-3p exacerbated inflammatory responses in IE though targeting TSC1, offering novel insights for potential therapeutic strategies targeting miR-27a-3p in the clinical management of IE.

Normothermic liver perfusion derived extracellular vesicles have concentration-dependent immunoregulatory properties

Extracellular vesicles (EVs) are major contributors to immunological responses following solid organ transplantation. Donor derived EVs are best known for their role in transplant rejection through transferring donor major histocompatibility complex proteins to recipient antigen presenting cells, a phenomenon known as ‛cross-decoration'. In contrast, donor liver-derived EVs are associated with organ tolerance in small animal models. Therefore, the cellular source of EVs and their cargo could influence their downstream immunological effects. To investigate the immunological effects of EVs released by the liver in a physiological and transplant-relevant model, we isolated EVs being produced during normothermic ex vivo liver perfusion (NEVLP), a novel method of liver storage prior to transplantation. We found EVs were produced by the liver during NEVLP, and these EVs contained multiple anti-inflammatory miRNA species. In terms of function, liver-derived EVs were able to cross-decorate allogeneic cells and suppress the immune response in allogeneic mixed lymphocyte reactions in a concentration-dependent fashion. In terms of cytokine response, the addition of 1 × 109 EVs to the mixed lymphocyte reactions significantly decreased the production of the inflammatory cytokines TNF-α, IL-10 and IFN-γ. In conclusion, we determined physiologically produced liver-derived EVs are immunologically regulatory, which has implications for their role and potential modification in solid organ transplantation.

Enhanced bone regeneration via endochondral ossification using Exendin-4-modified mesenchymal stem cells

Nonunions and delayed unions pose significant challenges in orthopedic treatment, with current therapies often proving inadequate. Bone tissue engineering (BTE), particularly through endochondral ossification (ECO), emerges as a promising strategy for addressing critical bone defects. This study introduces mesenchymal stem cells overexpressing Exendin-4 (MSC-E4), designed to modulate bone remodeling via their autocrine and paracrine functions. We established a type I collagen (Col-I) sponge-based in vitro model that effectively recapitulates the ECO pathway. MSC-E4 demonstrated superior chondrogenic and hypertrophic differentiation and enhanced the ECO cell fate in single-cell sequencing analysis. Furthermore, MSC-E4 encapsulated in microscaffold, effectively facilitated bone regeneration in a rat calvarial defect model, underscoring its potential as a therapeutic agent for bone regeneration. Our findings advocate for MSC-E4 within a BTE framework as a novel and potent approach for treating significant bone defects, leveraging the intrinsic ECO process.

Genome-Wide Association Study for Somatic Skeletal Traits in Duroc × (Landrace × Yorkshire) Pigs

The pig bone weight trait holds significant economic importance in southern China. To expedite the selection of the pig bone weight trait in pig breeding, we conducted molecular genetic research on these specific traits. These traits encompass the bone weight of the scapula (SW), front leg bone weight (including humerus and ulna) (FLBW), hind leg bone weight (including femur and tibia) (HLBW), and spine bone weight (SBW). Up until now, the genetic structure related to these traits has not been thoroughly explored, primarily due to challenges associated with obtaining the phenotype data. In this study, we utilized genome-wide association studies (GWAS) to discern single nucleotide polymorphisms (SNPs) and genes associated with four bone weight traits within a population comprising 571 Duroc × (Landrace × Yorkshire) hybrid pigs (DLY). In the analyses, we employed a mixed linear model, and for the correction of multiple tests, both the false discovery rate and Bonferroni methods were utilized. Following functional annotation, candidate genes were identified based on their proximity to the candidate sites and their association with the bone weight traits. This study represents the inaugural application of GWAS for the identification of SNPs associated with individual bone weight in DLY pigs. Our analysis unveiled 26 SNPs and identified 12 promising candidate genes (OPRM1, SLC44A5, WASHC4, NOPCHAP1, RHOT1, GLP1R, TGFB3, PLCB1, TLR4, KCNJ2, ABCA6, and ABCA9) associated with the four bone weight traits. Furthermore, our findings on the genetic mechanisms influencing pig bone weight offer valuable insights as a reference for the genetic enhancement of pig bone traits.

Brain-protective mechanisms of autophagy associated circRNAs: Kick starting self-cleaning mode in brain cells via circRNAs as a potential therapeutic approach for neurodegenerative diseases

Altered autophagy is a hallmark of neurodegeneration but how autophagy is regulated in the brain and dysfunctional autophagy leads to neuronal death has remained cryptic. Being a key cellular waste-recycling and housekeeping system, autophagy is implicated in a range of brain disorders and altering autophagy flux could be an effective therapeutic strategy and has the potential for clinical applications down the road. Tight regulation of proteins and organelles in order to meet the needs of complex neuronal physiology suggests that there is distinct regulatory pattern of neuronal autophagy as compared to non-neuronal cells and nervous system might have its own separate regulator of autophagy. Evidence has shown that circRNAs participates in the biological processes of autophagosome assembly. The regulatory networks between circRNAs, autophagy, and neurodegeneration remains unknown and warrants further investigation. Understanding the interplay between autophagy, circRNAs and neurodegeneration requires a knowledge of the multiple steps and regulatory interactions involved in the autophagy pathway which might provide a valuable resource for the diagnosis and therapy of neurodegenerative diseases. In this review, we aimed to summarize the latest studies on the role of brain-protective mechanisms of autophagy associated circRNAs in neurodegenerative diseases (including Alzheimer's disease, Parkinson's disease, Huntington's disease, Spinal Muscular Atrophy, Amyotrophic Lateral Sclerosis, and Friedreich's ataxia) and how this knowledge can be leveraged for the development of novel therapeutics against them. Autophagy stimulation might be potential one-size-fits-all therapy for neurodegenerative disease as per considerable body of evidence, therefore future research on brain-protective mechanisms of autophagy associated circRNAs will illuminate an important feature of nervous system biology and will open the door to new approaches for treating neurodegenerative diseases.

BMSC-derived exosomal miR-27a-3p and miR-196b-5p regulate bone remodeling in ovariectomized rats

Background

In the bone marrow microenvironment of postmenopausal osteoporosis (PMOP), bone marrow mesenchymal stem cell (BMSC)-derived exosomal miRNAs play an important role in bone formation and bone resorption, although the pathogenesis has yet to be clarified.

Methods

BMSC-derived exosomes from ovariectomized rats (OVX-Exo) and sham-operated rats (Sham-Exo) were co-cultured with bone marrow-derived macrophages to study their effects on osteoclast differentiation. Next-generation sequencing was utilized to identify the differentially expressed miRNAs (DE-miRNAs) between OVX-Exo and Sham-Exo, while target genes were analyzed using bioinformatics. The regulatory effects of miR-27a-3p and miR-196b-5p on osteogenic differentiation of BMSCs and osteoclast differentiation were verified by gain-of-function and loss-of-function analyses.

Results

Osteoclast differentiation was significantly enhanced in the OVX-Exo treatment group compared to the Sham-Exo group. Twenty DE-miRNAs were identified between OVX-Exo and Sham-Exo, among which miR-27a-3p and miR-196b-5p promoted the expressions of osteogenic differentiation markers in BMSCs. In contrast, knockdown of miR-27a-3p and miR-196b-5p increased the expressions of osteoclastic markers in osteoclast. These 20 DE-miRNAs were found to target 11435 mRNAs. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes pathway analyses revealed that these target genes were involved in several biological processes and osteoporosis-related signaling pathways.

Conclusion

BMSC-derived exosomal miR-27a-3p and miR-196b-5p may play a positive regulatory role in bone remodeling.