Hypoglycemic mechanisms of Polygonatum sibiricum polysaccharide in db/db mice via regulation of glycolysis/gluconeogenesis pathway and alteration of gut microbiota.

Polygonatum rhizoma polysaccharide (PP) is a main ingredient of Polygonatum rhizoma , which is both food and traditional herbal medicine. In this study, we aimed to investigate the hypoglycemic effect of PP and the underlying mechanisms in db/db mice. Our finding showed that PP significantly ameliorates diabetic symptoms by reducing glucose levels in blood and urine and increasing insulin and leptin abundance in the serum. Histopathological examination revealed that PP improved the pathological state and increased hepatic glycogen storage in liver. Additionally, RT-qPCR results indicated that PP significantly down-regulated the expression of phosphoenolpyruvate carboxykinase 1. Furthermore, 16s rRNA sequencing results demonstrated that PP intervention resulted in an increase in beneficial bacteria genus and a reduction in harmful genus. Redundancy analysis revealed the correlation between intestinal flora and clinical factors. Taken together, these results suggest that PP has a significant hypoglycemic effect on type 2 diabetes (T2D) through up-regulating serum insulin and leptin, as well as hepatic glycogen storage, and down-regulating hepatic phosphoenolpyruvate carboxykinase 1 expression, as well as modulating gut microbiota composition. In conclusion, this study investigated the mechanisms of PP in the treatment of diabetes in db/db mice. To the best of our knowledge, this is the first study to explore the positive and negative correlations between gut microbiota and clinical factors, such as oxidative stress injury in liver and glucose related indicators in the blood.

Scutellarin suppresses triple-negative breast cancer metastasis by inhibiting TNFα-induced vascular endothelial barrier breakdown.

Triple-negative breast cancer (TNBC) is an aggressive subtype of breast cancer with high vascularity and frequent metastasis. Tumor-associated abnormal vasculature was reported to accelerate TNBC metastasis. Scutellarin (SC) is a natural flavonoid with a cardiovascular protective function. In this study, SC reduced TNBC metastasis and alleviated tumor-associated vascular endothelial barrier injury in vivo. SC rescued the tumor necrosis factor-α (TNFα)-induced diminishment of endothelial junctional proteins and dysfunction of the endothelial barrier in vitro. SC reduced the increased transendothelial migration of TNBC cells through a monolayer composed of TNFα-stimulated human mammary microvascular endothelial cells (HMMECs) or human umbilical vein endothelial cells (HUVECs). TNFα induced the nuclear translocation of enhancer of zeste homolog-2 (EZH2), and its chemical inhibitor GSK126 blocked TNFα-induced endothelial barrier disruption and subsequent TNBC transendothelial migration. TNF receptor 2 (TNFR2) is the main receptor by which TNFα regulates endothelial barrier breakdown. Extracellular signal-regulated protein kinase (ERK)1/2 was found to be downstream of TNFα/TNFR2 and upstream of EZH2. Additionally, SC abrogated the TNFR2-ERK1/2-EZH2 signaling axis both in vivo and in vitro. Our results suggest that SC reduced TNBC metastasis by suppressing TNFα-initiated vascular endothelial barrier breakdown through rescuing the reduced expression of junctional proteins by regulating the TNFR2-ERK1/2-EZH2 signaling pathway.

Scutellarein alleviates the dysfunction of inner blood-retinal-barrier initiated by hyperglycemia-stimulated microglia cells.

AIM: To investigate the alleviation of scutellarein (SN) against inner blood-retinal-barrier (iBRB) dysfunction in microglia cells stimulated by hyperglycemia and to elucidate the engaged mechanism. METHODS: Microglia BV2 cells were stimulated by using 25 mmol/L D-glucose. The same concentration of mannitol (25 mmol/L) was applied as an isotonic contrast. Real-time PCR, Western-blot assay and immunofluorescence staining assay was performed. The dysfunction of iBRB in vitro was detected by using transendothelial electrical resistance (TEER) assay. Additionally, the leakage of fluorescein isothiocyanate (FITC)-conjugated dextran (70 kDa) was detected. RESULTS: SN abrogated microglia BV2 cells activation and reduced the phosphorylated activation of extracellular signal-regulated protein kinase (ERK)1/2. SN also decreased the transcriptional activation of nuclear factor κB (NFκB) and the elevated expression of tumor necrosis factor α (TNFα), interleukin (IL)-6 and IL-1ß in BV2 cells treated with D-glucose (25 mmol/L). SN attenuated iBRB dysfunction in human retinal endothelial cells (HRECs) or choroid-retinal endothelial RF/6A cells when those cells were treated with TNFα, IL-1ß or IL-6, or co-cultured with microglia cells stimulated by D-glucose. Moreover, SN restored the decreased protein expression of tight junctions (TJs) in TNFα-treated HRECs and RF/6A cells. CONCLUSION: SN not only alleviate iBRB dysfunction via directly inhibiting retinal endothelial injury caused by TNFα, IL-1ß or IL-6, but also reduce the release of TNFα, IL-1ß and IL-6 from microglia cells by abrogating hyperglycemia-mediated the activation of microglia cells.

TRPV1 mediates astrocyte activation and interleukin-1ß release induced by hypoxic ischemia (HI).

BACKGROUND: Hypoxic-ischemic encephalopathy (HIE) is a serious birth complication with high incidence in both advanced and developing countries. Children surviving from HIE often have severe long-term sequela including cerebral palsy, epilepsy, and cognitive disabilities. The severity of HIE in infants is tightly associated with increased IL-1ß expression and astrocyte activation which was regulated by transient receptor potential vanilloid 1 (TRPV1), a non-selective cation channel in the TRP family. METHODS: Neonatal hypoxic ischemia (HI) and oxygen-glucose deprivation (OGD) were used to simulate HIE in vivo and in vitro. Primarily cultured astrocytes were used for investigating the expression of glial fibrillary acidic protein (GFAP), IL-1ß, Janus kinase 2 (JAK2), signal transducer and activator of transcription 3 (STAT3), and activation of the nucleotide-binding, oligomerization domain (NOD)-like receptor pyrin domain-containing protein 3 (NLRP3) inflammasome by using Western blot, q-PCR, and immunofluorescence. Brain atrophy, infarct size, and neurobehavioral disorders were evaluated by Nissl staining, 2,3,5-triphenyltetrazolium chloride monohydrate (TTC) staining and neurobehavioral tests (geotaxis reflex, cliff aversion reaction, and grip test) individually. RESULTS: Astrocytes were overactivated after neonatal HI and OGD challenge. The number of activated astrocytes, the expression level of IL-1ß, brain atrophy, and shrinking infarct size were all downregulated in TRPV1 KO mice. TRPV1 deficiency in astrocytes attenuated the expression of GFAP and IL-1ß by reducing phosphorylation of JAK2 and STAT3. Meanwhile, IL-1ß release was significantly reduced in TRPV1 deficiency astrocytes by inhibiting activation of NLRP3 inflammasome. Additionally, neonatal HI-induced neurobehavioral disorders were significantly improved in the TRPV1 KO mice. CONCLUSIONS: TRPV1 promotes activation of astrocytes and release of astrocyte-derived IL-1ß mainly via JAK2-STAT3 signaling and activation of the NLRP3 inflammasome. Our findings provide mechanistic insights into TRPV1-mediated brain damage and neurobehavioral disorders caused by neonatal HI and potentially identify astrocytic TRPV1 as a novel therapeutic target for treating HIE in the subacute stages (24 h).

Scutellaria barbata attenuates diabetic retinopathy by preventing retinal inflammation and the decreased expression of tight junction protein.

AIM: To observe the attenuation of ethanol extract of Herba Scutellaria barbata (SE) against diabetic retinopathy (DR) and its engaged mechanism. METHODS: C57BL/6J mice were intraperitoneally injected with streptozotocin (STZ, 55 mg/kg) for 5 consecutive days to induce diabetes. The diabetic mice were orally given with SE (100, 200 mg/kg) for 1mo at 1mo after STZ injection. Blood-retinal barrier (BRB) breakdown was detected by using Evans blue permeation assay. Real-time polymerase chain reaction (RT-PCR), Western blot and immunofluorescence staining were used to detect mRNA and protein expression. Enzyme-linked immunosorbent assay (ELISA) was used to detect serum contents of tumor necrosis factor-α (TNF-α) and interleukin (IL)-1ß. RESULTS: SE (100, 200 mg/kg) reversed the breakdown of BRB in STZ-induced diabetic mice. The decreased expression of retinal claudin-1 and claudin-19, which are both tight junction (TJ) proteins, was reversed by SE. SE decreased the increased serum contents and retinal mRNA expression of TNF-α and IL-1ß. SE also decreased the increased retinal expression of intercellular cell adhesion molecule-1 (ICAM-1). SE reduced the increased phosphorylation of nuclear factor kappa B (NFκB) p65 and its subsequent nuclear translocation in retinas from STZ-induced diabetic mice. Results of Western blot and retinal immunofluorescence staining of ionized calcium-binding adapter molecule 1 (Iba1) demonstrated that SE abrogated the activation of microglia cells in STZ-induced diabetic mice. CONCLUSION: SE attenuates the development of DR by inhibiting retinal inflammation and restoring the decreased expression of TJ proteins including claudin-1 and claudin-19.