The critical role of KLF4 in regulating the activation of A1/A2 reactive astrocytes following ischemic stroke.

BACKGROUND: We have previously demonstrated that the expression of kruppel-like transcription factor-4 (KLF-4) is upregulated in astrocytes following acute ischemic stroke (AIS) and found that KLF4 confers vascular protection against cerebral ischemic injury. However, the functional role of KLF4 in astrocyte after AIS is far from clear. METHODS: The intrinsic relationship between KLF4 and A1/A2 reactive astrocytes and the impact of astrocytic KLF4 on the activation of A1/A2 subtype astrocytes were evaluated in middle cerebral artery occlusion (MCAO) mice and oxygen-glucose deprivation and restoration (OGD/R) astrocytes. RESULTS: Our results demonstrated that astrocytic KLF4 expression and complement C3-positive A1 and S100 calcium binding protein A10 (S100A10)-positive A2 astrocytes were induced in the ischemic penumbra following focal cerebral ischemia, and the time course of upregulation of astrocytic KLF4 correlated closely with the activation of A2 astrocytes. The dual immunofluorescent studies displayed that in the ischemic hemisphere, where the high levels of KLF4 were expressed, there were relatively low levels of C3 expressed in the reactive astrocytes and vice versa, but KLF4 was always co-stained well with S100A10. Mechanistic analyses revealed that astrocytic KLF4 inhibited the activation of A1 astrocyte but promoted A2 astrocyte polarization after OGD/R by modulating expressions of nuclear factor-kB. CONCLUSIONS: Astrocyte-derived KLF4 has a critical role in regulating the activation of A1/A2 reactive astrocytes following AIS.

[Matrine inhibits inflammatory response induced by TNF-α in human umbilical vein endothelial cells through miR-25-3p-mediated Klf4 pathway].

This study aimed to analyze the effect of matrine on tumor necrosis factor-α(TNF-α)-induced inflammatory response in human umbilical vein endothelial cells(HUVECs) and explore whether the underlying mechanism was related to the miR-25-3p-mediated Krüppel-like factor 4(Klf4) pathway. The HUVEC cell inflammation model was induced by TNF-α stimulation. After 24 or 48 hours of incubation with different concentrations of matrine(0.625, 1.25, and 2.5 mmol·L~(-1)), CCK-8 assay was used to detect cell proliferation. After treatment with 2.5 mmol·L~(-1) matrine for 48 h, the expression of TNF-α, interleukin-6(IL-6), interleukin-1ß(IL-1ß), and Klf4 mRNA and miR-25-3p was detected by real-time fluorescence-based quantitative PCR, and the protein expression of TNF-α, IL-6, IL-1ß, and Klf4 was detected by Western blot. The anti-miR-25-3p was transfected into HUVECs, and the effect of anti-miR-25-3p on TNF-α-induced cell proliferation and inflammatory factors was detected by the above method. The cells were further transfected with miR-25-3p and incubated with matrine to detect the changes in proliferation and expression of related inflammatory factors, miR-25-3p, and Klf4. The targeting relationship between miR-25-3p and Klf4 was verified by bioinformatics analysis and dual luciferase reporter gene assay. The results displayed that matrine could inhibit TNF-α-induced HUVEC proliferation, decrease the mRNA and protein expression of TNF-α, IL-6, and IL-1ß, increase the mRNA and protein expression of Klf4, and reduce the expression of miR-25-3p. Bioinformatics analysis showed that there were specific complementary binding sites between miR-25-3p and Klf4 sequences. Dual luciferase reporter gene assay confirmed that miR-25-3p negatively regulated Klf4 expression in HUVECs by targeting. The inhibition of miR-25-3p expression can reduce TNF-α-induced cell proliferation and mRNA and protein expression of TNF-α, IL-6, and IL-1ß. MiR-25-3p overexpression could reverse the effect of matrine on TNF-α-induced cell proliferation and the mRNA and protein expression of TNF-α, IL-6, IL-1ß, and Klf4. This study shows that matrine inhibits the inflammatory response induced by TNF-α in HUVECs through miR-25-3p-mediated Klf4 pathway.

MiR-506-3p Promotes the Proliferation and Migration of Vascular Smooth Muscle Cells via Targeting KLF4.

BACKGROUND: The dysregulation of proliferation and migration of vascular smooth muscle cells (VSMCs) is one of the major causes of atherosclerosis (AS). Accumulating studies confirm that Kruppel-like factor 4 (KLF4) can regulate the proliferation and differentiation of VSMCs through multiple signaling pathways. However, the mechanism of KLF4 dysregulation remains unknown. METHODS: Apolipoprotein E-knockout (ApoE-/-) mice and human VSMCs were used to establish AS animal model and cell model, respectively. qRT-PCR was employed to determine the expressions of miR-506-3p and KLF4. Cell Counting Kit -8, Transwell, TUNEL assays, and flow cytometry were performed to measure the proliferation, migration, and apoptosis of VSMCs. The upstream miRNAs of KLF4 were predicted by microT, miRanda, miRmap, and TargetScan databases. The interaction between KLF4 and miR-506-3p was confirmed using qRT-PCR, Western blot, and luciferase reporter gene assay. RESULTS: KLF4 expression was significantly decreased in the VSMCs of ApoE-/- mice fed with high-fat diet and in human VSMCs treated with oxidized low-density lipoprotein in time-dependent and dose-dependent manners. The transfection of miR-506-3p mimics or KLF4 shRNA promoted the proliferation and migration of VSMCs but inhibited the apoptosis while miR-506-3p inhibitors and pcDNA3.1-KLF4 exerted opposite effects. Additionally, KLF4 was confirmed as a target gene of miR-506-3p and could be negatively regulated by miR-506-3p. CONCLUSION: MiR-506-3p can promote the proliferation and migration of VSMCs via targeting KLF4, which can probably contribute to the pathogenesis of AS.

KLF4 alleviates cerebral vascular injury by ameliorating vascular endothelial inflammation and regulating tight junction protein expression following ischemic stroke.

BACKGROUND: Although inflammatory cell adhesion molecules (CAMs) and anti-inflammation factor Kruppel-like transcription factor (KLF) 4 have all been reported to be induced after cerebral ischemic stroke (CIS), the close temporal and spatial relationship between expressions of CAMs and KLF4 following CIS and whether and how CAMs and KLF-4 contribute to the development of CIS-induced vascular injury are still unclear. METHODS: Here, we first examined the correlation between serum levels of CAMs/KLF4 and infarct volume in acute CIS patients. Then, we determined the relationship between CAMs and KLF4 in mice after focal cerebral ischemia. Finally, we investigated the mechanism of KLF4 in protecting against oxygen-glucose deprivation-induced brain endothelial cell injury. RESULTS: Our results demonstrated that patients with moderate to severe CIS had higher serum levels of three CAMs including E-selectin, inter-cellular adhesion molecule 1 (ICAM-1), and vascular cell adhesion molecule 1 (VCAM-1) but lower levels of KLF4 at 48 h after an acute event as compared to patients with minor CIS. The expression levels of three CAMs as well as KLF4 all correlated well with the infarct volume in all the CIS subjects at that time. Although the expressions of three CAMs and KLF4 were all induced in the ischemic hemisphere following focal cerebral ischemia, the peak timing and distribution patterns of their expression were different: the induction of KLF4 lagged behind that of the CAMs in the ischemic penumbra; furthermore, the dual immunofluorescent studies displayed that high expression of KLF4 was always associated with relatively less cerebral vascular endothelial inflammation response in the ischemic hemisphere and vice versa. Mechanistic analyses revealed that KLF4 alleviated CIS-induced cerebral vascular injury by regulating endothelial expressions of CAMs, nuclear factor-kB, and tight junction proteins. CONCLUSIONS: These data indicate that KLF4 confers vascular protection against cerebral ischemic injury, suggesting that circulating CAMs and KLF4 might be used as potential biomarkers for predicting the prognosis of acute ischemic stroke and also providing a new proof of concept and potential targets for future prevention and treatment of CIS.

Paeoniflorin suppresses kidney inflammation by regulating macrophage polarization via KLF4-mediated mitophagy.

BACKGROUND: Macrophages M1 polarization involved in the process of renal inflammatory injury, is a well-established hallmark of chronic kidney disease (CKD). Paeoniflorin (PF), a water-soluble monoterpene glycoside extracted from Paeonia lactiflora, revealed renal anti-inflammatory activities in our previous study. However, the potential molecular mechanism of PF on CKD remains unknown. PURPOSE: The present study aims to investigate the regulation of PF on macrophage polarization in CKD. METHODS: A CKD model was established by cationic bovine serum albumin and a murine macrophage cell line RAW264.7 induced with lipopolysaccharide (LPS) were used to clarify the underlying mechanisms of PF in CKD. RESULTS: Results showed that PF exhibited favorable protective effects on CKD model mice by promoting renal function, ameliorating renal pathological injury and podocyte damage. Furthermore, PF inhibited the infiltration of M1 macrophage marker CD68 and iNOS in kidney tissue, but increased the proportion of M2 macrophage marker CD206. In RAW264.7 cells stimulated with LPS, the levels of cytokines including IL-6, IL-1ß, TNF-α, MCP-1 were lessened under PF treatment, while the levels of Arg1, Fizz1, IL-10 and Ym-1 were augmented. These results indicated that PF promoted macrophage polarization from M1 to M2 in vivo and in vitro. More importantly, PF repaired the damaged mitochondria through increasing mitochondrial membrane potential and reducing ROS accumulation. The mitophagy-related proteins PINK1, Parkin, Bnip3, P62 and LC3 were up-regulated by PF, accompanied by the incremental expressions of Krüppel-like transcription factor 4 (KLF4). Moreover, the promotion of mitophagy and inhibition of M1 macrophage polarization owing to PF were reversed by mitophagy inhibitor Mdivi-1 or silencing KLF4. CONCLUSION: Overall, PF suppressed renal inflammation by promoting macrophage polarization from M1 to M2 and inducing mitophagy via regulating KLF4. It is expected to provide a new strategy for exploring the effects of PF in treating CKD.

Serum inflammatory cell adhesion molecules predict malignant cerebral edema and clinical outcome early after mechanical thrombectomy in stroke.

BACKGROUND: Early prediction of life-threatening malignant cerebral edema (MCE) after mechanical thrombectomy (MT) is of clinical importance. Although inflammatory cell adhesion molecules (CAMs) and anti-inflammation factor Kruppel-like transcription factor (KLF) 4 are induced after acute ischemic stroke (AIS), the relationship between expressions of these molecules after MT and MCE as well as outcome in AIS patients have rarely been explored. METHODS: We retrospectively reviewed the data of all AIS patients with large-vessel occlusion in anterior circulation who underwent MT from our stroke centers. The serum levels of CAMs and KLF4 were determined at 12 h after MT. MCE was assessed on follow-up head computed tomography within 5 days after MT. RESULTS: Of 91 included patients, 18 (19.8 %) patients experienced MCE. Patients with MCE were more likely to have higher levels of E-selectin and inter-cellular adhesion molecule 1 (ICAM-1) than those without MCE (P < 0.05). More specifically, elevated E-selectin, but not of vascular cell adhesion molecule 1 (VCAM-1), ICAM-1 and KLF4, was significantly associated with MCE after adjusting for hypertension, admission NIHSS, Alberta Stroke Program Early CT Scores, serum glucose, collateral circulation and onset to recanalization time respectively (P < 0.05). ROC curve suggested that E-selectin had considerable discrimination to predict MCE (AUC=0.7, 95 % CI: 0.55-0.83). Moreover, after adjusting by confounders, serum levels of E-selectin and ICAM-1 were independently associated with 3-month outcome in AIS patients after MT (both P < 0.05). CONCLUSIONS: These data indicate that of three CAMs, serum E-selectin level early after MT is the best predictor for MCE and outcome in AIS.

Pioneer transcription factors, progesterone receptor and Krüppel like transcription factor 4, cooperatively stimulate the bovine herpesvirus 1 ICP0 early promoter and productive late protein expression.

Bovine herpesvirus 1 (BoHV-1), including commercially available modified live vaccines, readily infect the fetus and ovaries, which can cause reproductive failure. The BoHV-1 latency-reactivation cycle in sensory neurons further complicates reproductive failure because progesterone sporadically induces reactivation from latency. The progesterone receptor (PR) and Krüppel-like transcription factor 15 (KLF15) cooperatively stimulate productive infection and the immediate early transcription unit 1 (IEtu1) promoter. In addition to the IEtu1 promoter, the bICP0 gene also contains a separate early (E) promoter. In this study, we tested the hypothesis that PR and KLF family members transactivate the bICP0 E promoter. PR and KLF4 stimulated bICP0 E promoter activity and expression of late productive viral protein expression in a cooperative manner. Additional studies revealed three enhancer domains within the bICP0 E promoter were responsive to PR and KLF4. Chromatin immunoprecipitation studies demonstrated PR and KLF4 occupy bICP0 E promoter sequences in transfected Neuro-2A cells and at late times following infection of bovine kidney cells. Co-immunoprecipitation studies indicated PR and KLF4 stably interact with each other. These studies suggest cooperative activation of the bICP0 E promoter by PR and KLF4 correlate with interactions between these pioneer transcription factors.

Kruppel-Like Transcription Factor-4 Gene Expression and DNA Methylation Status in Type 2 Diabetes and Diabetic Nephropathy Patients.

BACKGROUND/AIM: Diabetic nephropathy (DN) is one of the most serious microvascular complications in diabetic patients. The kruppel-like transcription factor-4 (KLF-4) affects the expression of genes involved in the pathogenesis of DN. The present study aims to identify the KLF-4 expression and DNA methylation (DNAMe) status in patients with type-2 diabetes (T2D) and DN and to reveal the contribution of the KLF-4 to the development of DN. MATERIAL AND METHODS: The cohort study was performed with blood samples from 120 individuals; T2D group (n = 40), DN group (n = 40) and control group (n = 40). The expression level of the KLF-4 gene was analyzed using the real-time polymerase chain reaction (qRT-PCR) and the methylation profile detected using the methylation-specific PCR (MS-PCR) technique. RESULTS: According to our findings, KLF-4 mRNA expression in the T2D group was 1.60 fold lower than in the control group (p = 0.001). In the DN group, the expression of KLF-4 mRNA was 2.92-fold less than that of the T2D group (p = 0.001). There was no significant alteration in the DNAMe status among the groups. CONCLUSION: Our findings showed that regardless of the DNAMe status, KLF-4 gene expression may play a role in the development of T2D and DN. This suggests that the KLF-4 gene may be the target gene in understanding the mechanism of nephropathy, which is the most important complication of diabetes, and planning nephropathy-related treatments, but the data should be supported with more studies.

Matrine inhibits inflammatory response induced by TNF-α in human umbilical vein endothelial cells through miR-25-3p-mediated Klf4 pathway / 中国中药杂志

This study aimed to analyze the effect of matrine on tumor necrosis factor-α(TNF-α)-induced inflammatory response in human umbilical vein endothelial cells(HUVECs) and explore whether the underlying mechanism was related to the miR-25-3p-mediated Krüppel-like factor 4(Klf4) pathway. The HUVEC cell inflammation model was induced by TNF-α stimulation. After 24 or 48 hours of incubation with different concentrations of matrine(0.625, 1.25, and 2.5 mmol·L~(-1)), CCK-8 assay was used to detect cell proliferation. After treatment with 2.5 mmol·L~(-1) matrine for 48 h, the expression of TNF-α, interleukin-6(IL-6), interleukin-1β(IL-1β), and Klf4 mRNA and miR-25-3p was detected by real-time fluorescence-based quantitative PCR, and the protein expression of TNF-α, IL-6, IL-1β, and Klf4 was detected by Western blot. The anti-miR-25-3p was transfected into HUVECs, and the effect of anti-miR-25-3p on TNF-α-induced cell proliferation and inflammatory factors was detected by the above method. The cells were further transfected with miR-25-3p and incubated with matrine to detect the changes in proliferation and expression of related inflammatory factors, miR-25-3p, and Klf4. The targeting relationship between miR-25-3p and Klf4 was verified by bioinformatics analysis and dual luciferase reporter gene assay. The results displayed that matrine could inhibit TNF-α-induced HUVEC proliferation, decrease the mRNA and protein expression of TNF-α, IL-6, and IL-1β, increase the mRNA and protein expression of Klf4, and reduce the expression of miR-25-3p. Bioinformatics analysis showed that there were specific complementary binding sites between miR-25-3p and Klf4 sequences. Dual luciferase reporter gene assay confirmed that miR-25-3p negatively regulated Klf4 expression in HUVECs by targeting. The inhibition of miR-25-3p expression can reduce TNF-α-induced cell proliferation and mRNA and protein expression of TNF-α, IL-6, and IL-1β. MiR-25-3p overexpression could reverse the effect of matrine on TNF-α-induced cell proliferation and the mRNA and protein expression of TNF-α, IL-6, IL-1β, and Klf4. This study shows that matrine inhibits the inflammatory response induced by TNF-α in HUVECs through miR-25-3p-mediated Klf4 pathway.

Changes of microRNA-206 in peripheral blood mononuclear cells from children with respiratory syncytial virus bronchiolitis / 中华实用儿科临床杂志

Objective To explore the role of microRNA-206 (miR-206) in peripheral blood mononuclear cells (PBMCs) in infantile bronchiolitis caused by respiratory syncytial virus (RSV).Methods Thirty-five cases of infantile bronchiolitis and 25 cases of healthy controls were enrolled into the current study.PBMCs were isolated from the peripheral blood of both healthy subjects and those with infantile bronchiolitis in the acute and the convalescent stages.Total RNAs were extracted from PBMCs which were stimulated by phorbol-12-myristate-13-acetate (PMA) and Ionomycin, and then the RNA was transcribed reversely into cDNA.The expressions of miR-206 and Kruppel-like transcription factor 4 (KLF4) were detected by real-time quantitative polymerase chain reaction (qRT-PCR) method.Plasma interleukin-17 (IL-17) was determined by enzyme linked immunosorbent assay (ELISA).Results There was a significant difference in miR-206 levels of children with RSV bronchiolitis in the acute stage(0.055 ±0.018) and the convalescent stage(0.187 ±0.069) as well as the healthy controls(0.204 ± 0.075).Through pairwise comparison, the miR-206 levels in the children in the acute stage were significantly lower than those in the convalescent stage and healthy control group (P ＜ 0.01), but no statistical significance was found between the convalescent stage group and healthy control group(P ＞ 0.05).The levels of KLF4 mRNA of children in the acute stage,convalescent stage as well as the healthy subjects were 0.588 ± 0.161,0.086±0.024,0.075 ±0.019, respectively,which was significantly difference (P ＜ 0.01).The levels of IL-17 were (58.26 ±25.88) ng/L, (9.87 ± 3.01) ng/L, (7.65 ± 2.16) ng/L, respectively (P ＜ 0.01).Compared to the convalescent and the normal control group,both the KLF4 mRNA and IL-17 levels were markedly higher in the acute stage (P ＜ 0.01), but there were no significant differences between children with RSV bronchiolitis in convalescent stage and in the healthy controls (P ＞ 0.05).Furthermore, the result of this study showed a negative correlation between the expression of miR-206 and KLF4(r =-0.624 ,P ＜0.01)and IL-17 (r =-0.609 ,P ＜0.01) in children in the acute stage and a positive correlation between KLF4 mRNA and IL-17 in children in the acute stage (r =0.662, P ＜ 0.01).Conclusion The levels of miR-206 may play a role in the onset of RSV associated post-bronchiolitis (PB) and the low expression of miR-206 in children infected with RSV may increase the susceptibility to PB.