An adaptive biodegradable zinc alloy with bidirectional regulation of bone homeostasis for treating fractures and aged bone defects

Healing of fractures or bone defects is significantly hindered by overactivated osteoclasts and inhibited osteogenesis in patients with abnormal bone metabolism. Current clinical approaches using titanium alloys or stainless steel provide mechanical support but have no biological effects on bone regeneration. Therefore, designing and fabricating degradable metal materials with sufficient mechanical strength and bidirectional regulation of both osteoblasts and osteoclasts is a substantial challenge. Here, this study first reported an adaptive biodegradable Zn-0.8 Mg alloy with bidirectional regulation of bone homeostasis, which promotes osteogenic differentiation by activating the Pi3k/Akt pathway and inhibits osteoclast differentiation by inhibiting the GRB2/ERK pathway. The anti-osteolytic ability of the Zn-0.8 Mg alloy was verified in a mouse calvarial osteolysis model and its suitability for internal fracture fixation with high-strength screws was confirmed in the rabbit femoral condyle fracture model. Furthermore, in an aged postmenopausal rat femoral condyle defect model, 3D printed Zn-0.8 Mg scaffolds promoted excellent bone regeneration through adaptive structures with good mechanical properties and bidirectionally regulated bone metabolism, enabling personalized bone defect repair. These findings demonstrate the substantial potential of the Zn-0.8 Mg alloy for treating fractures or bone defects in patients with aberrant bone metabolism.

A novel bidirectional regulation mechanism of mancozeb on the dissemination of antibiotic resistance

The high abundance of antibiotic resistance genes (ARGs) in the fungicide residual environment, posing a threat to the environment and human health, raises the question of whether and how fungicide promotes the prevalence and dissemination of antibiotic resistance. Here, we reported a novel mechanism underlying bidirectional regulation of a typical heavy-metal-containing fungicide mancozeb on the horizontal transfer of ARGs. Our findings revealed that mancozeb exposure significantly exerted oxidative and osmotic stress on the microbes and facilitated plasmid-mediated ARGs transfer, but its metallic portions (Mn and Zn) were potentially utilized as essential ions by microbes for metalating enzymes to deal with cellular stress and thus reduce the transfer. The results of transcriptome analysis with RT-qPCR confirmed that the expression levels of cellular stress responses and conjugation related genes were drastically altered. It can be concluded mancozeb bidirectionally regulated the ARGs dissemination which may be attributed to the diverse effects on the microbes by its different portions. This novel mechanism provides an updated understanding of neglected fungicide-triggered ARGs dissemination and crucial insight for comprehensive risk assessment of fungicides.

Bidirectional role of acupuncture in the treatment of drug addiction

Drug addiction is a chronically relapsing disorder, affecting people from all walks of life. Studies of acupuncture effects on drug addiction are intriguing in light of the fact that acupuncture can be used as a convenient therapeutic intervention for treating drug addiction by direct activation of brain pathway. The current review aims to discuss the neurobiological mechanisms underlying acupuncture's effectiveness in the treatment of drug addiction, on the basis of two different theories (the incentive sensitization theory and the opponent process theory) that have seemingly opposite view on the role of the mesolimbic reward pathways in mediating compulsive drug-seeking behavior. This review provides evidence that acupuncture may reduce relapse to drug-seeking behavior by regulating neurotransmitters involved in drug craving modulation via somatosensory afferent mechanisms. Also, acupuncture normalizes hyper-reactivity or hypoactivity of the mesolimbic dopamine system in these opposed processes in drug addiction, suggesting bidirectional role of acupuncture in regulation of drug addiction. This proposes that acupuncture may reduce drug craving by correcting both dysfunctions of the mesolimbic dopamine pathway.

Oncogenic miR-20b-5p contributes to malignant behaviors of breast cancer stem cells by bidirectionally regulating CCND1 and E2F1

BACKGROUND

Breast cancer is the leading cause of cancer mortality in women worldwide. Therefore, it is of great significance to identify the biological mechanism of tumorigenesis and explore the development of breast cancer to achieve a better prognosis for individuals suffering from breast cancer. MicroRNAs (miRNAs) have become a hot topic in cancer research, but the underlying mechanism of its involvement in cancer remains unclear.

METHODS

The miRNA profile between breast cancer stem cells (BCSCs, CD44⁺CD24^-/low) and control MCF-7 breast cancer cells was obtained in a previous study. Based on biological analysis, miR-20b-5p was hypothesized to be a key factor due to the malignant behavior of BCSCs. Then, agomir-20b-5p and antagomir-20b-5p were transfected into MCF-7 and T47D breast cancer cells to detect cell migration, wound healing and proliferation, and lentivirus vectors silencing or overexpressing miR-20b-5p were transfected into T47D-CSCs to detect proliferation and apoptosis. The effect of miR-20b-5p on xenograft growth was investigated in vivo by transfection of a lentivirus-overexpression vector into T47D cells. The target genes were predicted by the online programs picTar, miRanda and TargetScan and verified by dual luciferase assay, and changes in protein expression were detected by western blot.

RESULTS

MiR-20b-5p had the highest degree in both the miRNA-gene network and miRNA-GO network to regulate BCSCs. Overexpression of miR-20b-5p significantly promoted the migration and wound healing ability of MCF-7 cells and T47D cells compared with the control (P < 0.05). In addition, miR-20b-5p facilitated the proliferation of MCF-7 cells and T47D-CSCs (P < 0.05) and inhibited the apoptosis of T47D-CSCs (P < 0.05). Moreover, miR-20b-5p promoted xenograft growth compared with the control group (P < 0.05). Accordingly, potential targets of both CCND1 and E2F1 were predicted by bioinformatics analysis. MiR-20b-5p directly targeted both CCND1 and E2F1 in a dual luciferase assay, while antagomir-20b-5p downregulated the protein levels of CCND1 and E2F1.

CONCLUSIONS

Oncogenic miR-20b-5p was confirmed to promote the malignant behaviors of breast cancer cells and BCSCs. The underlying mechanism lies in that miR-20b-5p overall enhanced both CCND1 and E2F1 targets via bidirectional regulation probably involving direct downregulation and indirect upregulation.

Hyperbranched lipoid-based lipid nanoparticles for bidirectional regulation of collagen accumulation in liver fibrosis

Liver fibrosis leads to over one million deaths annually worldwide. Hepatic stellate cells (HSCs) have been identified as the main executors of liver fibrosis. Unfortunately, no drug has yet been approved for clinical use against liver fibrosis, largely because the tested drugs have been unable to access HSCs and efficiently remove the collagen accumulation involved in fibrogenesis. Here, we designed an efficient HSC-targeting lipid delivery system that carried dual siRNAs intended to both inhibit collagen synthesis and promote collagen degradation, with the goal of realizing enhanced anti-liver fibrosis by bidirectional regulation of collagen accumulation. The delivery system was constructed by using amphiphilic cationic hyperbranched lipoids (C₁₅-PA) for siRNA complexation and helper lipoids (cholesterol-polyethylene glycol-vitamin A, Chol-PEG-VA) for HSCs targeting. The generated vitamin A-decorated and hyperbranched lipoid-based lipid nanoparticles (VLNPs) showed excellent gene-binding ability and transfection efficiency, and enhanced the delivery of siRNAs to HSCs. Fibrotic mice treated with dual siRNA-loaded VLNPs showed a great reduction in the collagen accumulation seen in this model; the enhanced effect of bidirectional regulation reduced the collagen accumulation level in treated mice to almost that seen in normal mice. There was no notable sign of toxicity or tissue inflammation in mice exposed to repeated intravenous administration of the dual siRNA-loaded VLNPs. In conclusion, our results indicate that biocompatible VLNPs designed to exploit precise targeting and an effective bidirectional regulation strategy hold promise for treating liver fibrosis.

Gegen Qinlian decoction maintains colonic mucosal homeostasis in acute/chronic ulcerative colitis via bidirectionally modulating dysregulated Notch signaling

BACKGROUND

Gegen Qinlian decoction (GQ) is a well-known traditional Chinese medicine that has been clinically proven to be effective in treating ulcerative colitis (UC). However, its therapeutic mechanism has not been fully elucidated. Notch signaling plays an essential role in the regeneration of the intestinal epithelium.

PURPOSE

This study was designed to ascertain the mechanism by which GQ participates in the recovery of the colonic mucosa by regulating Notch signaling in acute and chronic UC models.

METHODS

Acute and chronic UC mice (C57BL/6) were established with 3 and 2% dextran sulfate sodium (DSS), respectively, and treated with oral administration of GQ. The expression of the Notch target gene Hes1 and the Notch-related proteins RBP-J, MAML and Math1 was analyzed by western blotting. PTEN mRNA levels were detected by qRT-PCR. Mucin production that is characteristic of goblet cells was determined by Alcian blue/periodic acid-Schiff staining and verified by examining MUC2 mRNA levels by qRT-PCR. Cell proliferation was assayed by immunohistochemistry analysis of Ki67. HT-29 and FHC cells and Toll-like receptor 4 knockout (TLR4^-/-) acute UC mice were also used in this study.

RESULTS

GQ restored the injured colonic mucosa in both acute and chronic UC models. We found that Notch signaling was hyperactive in acute UC mice and hypoactive in chronic UC mice. GQ downregulated Hes1, RBP-J and MAML proteins and augmented goblet cells in the acute UC models, whereas GQ upregulated Hes1, RBP-J and MAML proteins in chronic UC mice, reducing goblet cell differentiation and promoting crypt base columnar (CBC) stem cell proliferation. Hes1 mRNA was suppressed in TLR4^-/- UC mice, and GQ treatment reversed this effect. In vitro, GQ reduced Hes1 protein in Notch-activated HT29 and FHC cells but increased Hes1 protein in Notch-inhibited cells.

CONCLUSIONS

GQ restored the colonic epithelium by maintaining mucosal homeostasis via bidirectional regulation of Notch signaling in acute/chronic UC models.

[Bidirectional regulation of acupuncture and its plausible mechanisms]

The effects of acupuncture on functional regulation of biological systems have been studied extensively. The most interesting feature of acupuncture is the bidirectional regulatory ability to restore homeostatic values of body systems from either up or down states, which was found by Chinese biomedical researchers several decades ago, and has recently been observed by peers internationally. Acupuncture can produce two physiological response patterns, an immediate short-term response or/and a long-lasting response. The bidirectional regulatory effects of acupuncture are rarely observed under physiological states (normal homeostasis), rather, they are usually observed under pathological states (abnormal homeostasis) with long-lasting response patterns. This suggests that the effects of acupuncture under pathological states are different from the mechanisms under normal physiological states. This is important for understan-ding and developing acupuncture therapy, and also gives insight into understanding the biological control process itself. The present paper reviews the experimental literature and discusses the four conditions that produce bidirectional regulation of acupuncture, i.e. the inherent properties of the target systems, the functional states of the target system, the acupoint characteristics, and the stimulation parameters. Finally, two hypotheses are proposed to explain the mechanisms of bidirectional effects of acupuncture. The possible peripheral mechanism is that acupuncture can stimulate different types of peripheral nerve fibers to produce opposite regulatory effects; and the possible central mechanisms is that acupuncture might activate the adaptive control process of the central nervous system to restore homeostatic balance.

Characteristics of nobiletin-induced effects on jejunal contractility

Nobiletin, a citrus polymethoxylated flavone, exhibits multiple biological properties including anti-inflammatory, anti-carcinogenic, and anti-insulin resistance effects. The present study found that nobiletin exerted significant stimulatory effects on the contractility of isolated rat jejunal segments in all 6 different low contractile states, and meanwhile significant inhibitory effects in all 6 different high contractile states, showing characteristics of bidirectional regulation (BR). Nobiletin-exerted BR on jejunal contractility was abolished in the presence of c-kit receptor tyrosine kinase inhibitor imatinib or Ca(2+) channel blocker verapamil. In the presence of neuroxin tetrodotoxin, nobiletin only exerted stimulatory effects on jejunal contractility in both low and high contractile states. Hemicholinium-3 and atropine partially blocked nobiletin-exerted stimulatory effects on jejunal contractility in low-Ca(2+)-induced low contractile state. Phentolamine or propranolol or l-NG-nitro-arginine significantly blocked nobiletin-exerted inhibitory effects on jejunal contractility in high-Ca(2+)-induced high contractile state respectively. The effects of nobiletin on myosin light chain kinase (MLCK) mRNA expression, MLCK protein content, and myosin light chain phosphorylation extent were also bidirectional. In summary, nobiletin-exerted BR depends on the contractile states of rat jejunal segments. Nobiletin-exerted BR requires the enteric nervous system, interstitial cell of Cajal, Ca(2+), and myosin phosphorylation-related mechanisms.

Characteristics of deslanoside-induced modulation on jejunal contractility

AIM: To characterize the dual effects of deslanoside on the contractility of jejunal smooth muscle.

METHODS: Eight pairs of different low and high contractile states of isolated jejunal smooth muscle fragment (JSMF) were established. Contractile amplitude of JSMF in different low and high contractile states was selected to determine the effects of deslanoside, and Western blotting analysis was performed to measure the effects of deslanoside on myosin phosphorylation of jejunal smooth muscle.

RESULTS: Stimulatory effects on the contractility of JSMF were induced (45.3% ± 4.0% vs 87.0% ± 7.8%, P < 0.01) by deslanoside in 8 low contractile states, and inhibitory effects were induced (180.6% ± 17.8% vs 109.9% ± 10.8%, P < 0.01) on the contractility of JSMF in 8 high contractile states. The effect of deslanoside on the phosphorylation of myosin light chain of JSMF in low (78.1% ± 4.1% vs 96.0% ± 8.1%, P < 0.01) and high contractile state (139.2% ± 8.5% vs 105.5 ± 7.34, P < 0.01) was also bidirectional. Bidirectional regulation (BR) was abolished in the presence of tetrodotoxin. Deslanoside did not affect jejunal contractility pretreated with the Ca²⁺ channel blocker verapamil or in a Ca²⁺-free assay condition. The stimulatory effect of deslanoside on JSMF in a low contractile state (low Ca²⁺ induced) was abolished by atropine. The inhibitory effect of deslanoside on jejunal contractility in a high contractile state (high Ca²⁺ induced) was blocked by phentolamine, propranolol and L-NG-nitro-arginine, respectively.

CONCLUSION: Deslanoside-induced BR is Ca²⁺ dependent and is related to cholinergic and adrenergic systems when JSMF is in low or high contractile states.

Role of early growth response 1 in liver injury

Liver injury is a sophisticated pathophysiological process caused by many factors. Currently, the role of early growth response 1 (EGR1) in liver injury is still controversial. Some studies show that EGR1 can amplify the systemic inflammatory response and promote apoptosis in galactosamine/lipopolysaccharide-induced acute liver injury and alpha-naphthylisothiocyanate (ANIT)-induced intrahepatic cholestasis as well as other non-liver injuries, while some other studies indicate that EGR1 protects the liver from CCl₄ exposure by regulating the expression of inducible nitric oxide synthase, cyclooxygenase-2, and tumor necrosis factor-α-regulated genes that have hepatoprotective function.