Tailor-made molecular imprints for biological event intervention.

Molecular imprints, which are crosslinked architectures containing specific molecular recognition cavities for targeting compounds, have recently transitioned from in vitro diagnosis to in vivo treatment. In current application scenarios, it has become an important topic to create new biomolecular recognition pathways through molecular imprinting, thereby inhibiting the pathogenesis and regulating the development of diseases. This review starts with a pathological analysis, mainly focusing on the corresponding artificial enzymes, enzyme inhibitors and antibody mimics with enhanced functions that are created by molecular imprinting strategies. Recent advances are highlighted in the use of molecular imprints as tailor-made nanomedicines for the prevention of three major diseases: metabolic syndrome, cancer, and bacterial/viral infections.

Reduced Sirtuin1 signalling exacerbates diabetic mice hindlimb ischaemia injury and inhibits the protective effect of a liver X receptor agonist.

Diabetes mellitus causes endothelial dysfunction, which further exacerbates peripheral arterial disease (PAD). Improving endothelial function via reducing endothelial oxidative stress (OS) may be a promising therapy for diabetic PAD. Activation of liver X receptor (LXR) inhibits excessive OS and provides protective effects on endothelial cells in diabetic individuals. Therefore, we investigated the effects of LXR agonist treatment on diabetic PAD with a focus on modulating endothelial OS. We used a streptozotocin-induced diabetes mouse model combined with a hindlimb ischaemia (HLI) injury to mimic diabetic PAD, which was followed by LXR agonist treatment. In our study, the LXR agonist T0901317 protected against HLI injury in diabetic mice by attenuating endothelial OS and stimulating angiogenesis. However, a deficiency in endothelial Sirtuin1 (SIRT1) largely inhibited the therapeutic effects of T0901317. Furthermore, we found that the underlying therapeutic mechanisms of T0901317 were related to SIRT1 and non-SIRT1 signalling, and the isoform LXRß was involved in LXR agonist-elicited SIRT1 regulation. In conclusion, LXR agonist treatment protected against HLI injury in diabetic mice via mitigating endothelial OS and stimulating cellular viability and angiogenesis by LXRß, which elicited both SIRT1-mediated and non-SIRT1-mediated signalling pathways. Therefore, LXR agonist treatment may be a promising therapeutic strategy for diabetic PAD.

Noninvasive monitoring of the development and treatment response of ischemic hindlimb by targeting matrix metalloproteinase-2 (MMP-2).

Critical limb ischemia (CLI) is a common cause of high vascular morbidity and mortality. Monitoring the development and treatment response of hindlimb ischemia (HI) in an animal model enables a better understanding of the pathological mechanisms underlying CLI, and evaluation of the efficacy of novel therapeutic approaches. Matrix metalloproteinase (MMP) activity is essential for remodeling of ischemic tissue including extracellular matrix degradation and angiogenesis. Herein, a mouse HI model is established and subjected to noninvasive optical imaging with a novel and ultra-sensitive MMP activatable probe, termed MMP-P12, for analyzing the development and treatment response of HI. Our results show that angiogenesis development during HI was well correlated with MMP-2 activity alteration as examined by western blot, histological staining and MMP-P12 fluorescence signal recovery. Moreover, vascular endothelial growth factor (VEGF) mediated HI treatment was also monitored by MMP-P12. Up-regulated MMP-2 expression and an enhancement of angiogenesis were observed after VEGF treatment, which peaked at 7 days after the treatment. Overall, our results showed that MMP-2 plays an important role in the monitoring of angiogenesis during HI development and therapy. Application of MMP-P12 to visualize MMP-2 activity alteration can serve as a promising noninvasive optical imaging strategy to monitor angiogenesis and its response to therapy in CLI.

A Novel Mechanism of Mesenchymal Stromal Cell-Mediated Protection against Sepsis: Restricting Inflammasome Activation in Macrophages by Increasing Mitophagy and Decreasing Mitochondrial ROS.

Sepsis, a systemic inflammatory response to infection, is the leading cause of death in the intensive care unit (ICU). Previous studies indicated that mesenchymal stromal cells (MSCs) might have therapeutic potential against sepsis. The current study was designed to investigate the effects of MSCs on sepsis and the underlying mechanisms focusing on inflammasome activation in macrophages. The results demonstrated that the bone marrow-derived mesenchymal stem cells (BMSCs) significantly increased the survival rate and organ function in cecal ligation and puncture (CLP) mice compared with the control-grouped mice. BMSCs significantly restricted NLRP3 inflammasome activation, suppressed the generation of mitochondrial ROS, and decreased caspase-1 and IL-1ß activation when cocultured with bone marrow-derived macrophages (BMDMs), the effects of which could be abolished by Mito-TEMPO. Furthermore, the expression levels of caspase-1, IL-1ß, and IL-18 in BMDMs were elevated after treatment with mitophagy inhibitor 3-MA. Thus, BMSCs exert beneficial effects on inhibiting NLRP3 inflammasome activation in macrophages primarily via both enhancing mitophagy and decreasing mitochondrial ROS. These findings suggest that restricting inflammasome activation in macrophages by increasing mitophagy and decreasing mitochondrial ROS might be a crucial mechanism for MSCs to combat sepsis.

Activation of cannabinoid receptor type II by AM1241 protects adipose-derived mesenchymal stem cells from oxidative damage and enhances their therapeutic efficacy in myocardial infarction mice via Stat3 activation.

The poor survival of cells in ischemic sites diminishes the therapeutic efficacy of stem cell therapy. Previously we and others have reported that Cannabinoid receptor type II (CB2) is protective during heart ischemic injury for its anti-oxidative activity. However, whether CB2 activation could improve the survival and therapeutic efficacy of stem cells in ischemic myocardium and the underlying mechanisms remain elusive. Here, we showed evidence that CB2 agonist AM1241 treatment could improve the functional survival of adipose-derived mesenchymal stem cells (AD-MSCs) in vitro as well as in vivo. Moreover, AD-MSCs adjuvant with AM1241 improved cardiac function, and inhibited cardiac oxidative stress, apoptosis and fibrosis. To unveil possible mechanisms, AD-MSCs were exposed to hydrogen peroxide/serum deprivation to simulate the ischemic environment in myocardium. Results delineated that AM1241 blocked the apoptosis, oxidative damage and promoted the paracrine effects of AD-MSCs. Mechanistically, AM1241 activated signal transducers and activators of transcription 3 (Stat3) through the phosphorylation of Akt and ERK1/2. Moreover, the administration of AM630, LY294002, U0126 and AG490 (inhibitors for CB2, Akt, ERK1/2 and Stat3, respectively) could abolish the beneficial actions of AM1241. Our result support the promise of CB2 activation as an effective strategy to optimize stem cell-based therapy possibly through Stat3 activation.

Reduced silent information regulator 1 signaling exacerbates sepsis-induced myocardial injury and mitigates the protective effect of a liver X receptor agonist.

Myocardial injury and dysfunction are critical manifestations of sepsis. Previous studies have reported that liver X receptor (LXR) activation is protective during sepsis. However, whether LXR activation protects against septic heart injury and its underlying mechanisms remain elusive. This study was designed to determine the role of LXR activation in the septic heart with a focus on SIRT1 (silent information regulator 1) signaling. Male cardiac-specific SIRT1 knockout mice (SIRT1-/-) and their wild-type littermates were subjected to sepsis by cecal ligation and puncture (CLP) in the presence or absence of LXR agonist T0901317. The survival rate of mice was recorded during the 7-day period post CLP. Our results demonstrated that SIRT1-/- mice suffered from exacerbated mortality and myocardial injury in comparison with their wild-type littermates. Meanwhile, T0901317 treatment improved mice survival, accompanied by significant ameliorations of myocardial injury and dysfunction in wild-type mice but not in SIRT1-/- mice. Furthermore, the levels of myocardial inflammatory cytokines (TNF-α, IL-6, IL-1ß, MCP-1, MPO and HMGB1), oxidative stress (ROS generation, MDA), endoplasmic-reticulum (ER) stress (protein levels of CHOP, GRP78, GRP94, IRE1α, and ATF6), and cardiac apoptosis following CLP were inhibited by T0901317 treatment in wild-type mice but not in SIRT1-/- mice. Mechanistically, T0901317 enhanced SIRT1 signaling and the subsequent deacetylation and activation of antioxidative FoxO1 and anti-ER stress HSF1, as well as the deacetylation and inhibition of pro-inflammatory NF-ΚB and pro-apoptotic P53, thereby alleviating sepsis-induced myocardial injury and dysfunction. Our data support the promise of LXR activation as an effective strategy for relieving heart septic injury.

Endothelial deletion of mTORC1 protects against hindlimb ischemia in diabetic mice via activation of autophagy, attenuation of oxidative stress and alleviation of inflammation.

Peripheral arterial disease (PAD) complicated with diabetes mellitus (DM) still remains a thorny issue due to lack of effective strategies. Our previous study has demonstrated that inhibition of mTORC1 protected adipose-derived stromal cells from hindlimb ischemic injury in PAD mice. However, whether inhibition of mTORC1 could protect against PAD in diabetes mellitus and the underlying mechanisms remained elusive. In this study, we employed endothelial-specific raptor (an essential component of the mTORC1 signaling complex) knockout (KO) mice (Tie2-mTORC1ko) to investigate whether and how mTORC1 downregulation could alleviate hindlimb ischemic injury in diabetic mice. Tie2-mTORC1ko mice and their wild-type littermates were intraperitoneally injected with streptozocin to induce type 1 diabetic model, after which the hyperglycemic mice were randomly allocated to sham operation or PAD operation (femoral artery ligation). The restoration of hindlimb blood perfusion and recovery of limb functions were improved in diabetic Tie2-mTORC1ko PAD mice with significant improvements of autophagy, angiogenesis and vascular integrity as well as attenuation of apoptosis, inflammation and oxidative stress. In vitro, high glucose combining with hypoxia/serum deprivation treatment (HG+H/SD) significantly triggered apoptosis, reactive oxygen species generation and inflammation while inhibited autophagy and tube formation in HUVECs. The effect could be accentuated and attenuated by mTORC1 over-expression (TSC2 siRNA) and mTORC1 silencing (raptor siRNA), respectively. Moreover, autophagy inhibitor 3-MA could simulate the effects of TSC2 siRNA while autophagy inducer rapamycin could mimic the effects of raptor siRNA, suggesting that the beneficial effects of mTORC1 deletion were associated with autophagy induction. In conclusion, our present study demonstrates that endothelial mTORC1 deletion protects against hindlimb ischemic injury in diabetic mice possibly via activation of autophagy, attenuation of oxidative stress and alleviation of inflammation. Therapeutics targeting mTORC1 may therefore represents a promising strategy to rescue limb ischemia in diabetes mellitus.

Mesenchymal stem cells in alleviating sepsis-induced mice cardiac dysfunction via inhibition of mTORC1-p70S6K signal pathway.

Sepsis-induced cardiac dysfunction remains a major cause of morbidity and mortality in patients suffered from severe trauma. Mesenchymal stem cells (MSCs) -based treatment has been verified as a promising approach to mitigate the sepsis-induced cardiac dysfunction, but the mechanism is still ambiguous. Thus, our study was designed to explore the potential role of MSCs in sepsis-induced cardiac dysfunction. In vivo bioluminescence imaging revealed 80% acute donor cell death of bone marrow-derived MSCs (BM-MSCs) within 3 days after transplantation. However, echocardiography demonstrated that systolic function in wild-type mice group were reduced after sepsis, while the cardiac function was relatively well persevered in cardiac-conditional deletion of Raptor (component of mTORC1 complex) mice group. Raptor KO group treated with BM-MSCs appeared better cardiac function than other groups (P<0.05). In vitro cell study revealed that co-culture of H9C2 (Raptor-Knock down) and BM-MSC could attenuate the level of proinflammatory cytokines and promote the expression of anti-inflammatory cytokine accompanied by mTORC2-Akt activation (P<0.05). In contrast, co-culture H9C2 (Raptor-O.E) and BM-MSC could aggravate the inflammatory response accompanied by the activation of mTORC1-p70S6K and inhibition of mTORC2-Akt (P<0.05). The immunomodulatory property of MSC is related to the inhibition of mTORC1-p70S6K and activation of mTORC2-Akt signaling pathway. mTORC1-p70S6K and mTORC2-Akt pathways were involved in the therapeutic adjuncts of MSC. The possible mechanism due to MSC`s immunomodulatory property through activation of mTORC2-Akt and inhibition of mTORC1-p70S6K signal pathways which may lead to modulate the expression of inflammation cytokines.