RGMa promotes dedifferentiation of vascular smooth muscle cells into a macrophage-like phenotype in vivo and in vitro.

Repulsive guidance molecule a (RGMa) is a glycosylphosphatidylinositol-anchored glycoprotein that has been demonstrated to influence inflammatory-related diseases in addition to regulating neuronal differentiation and survival during brain development. However, any function or mechanism of RGMa in dedifferentiation of contractile vascular smooth muscle cells (VSMCs) during inflammatory-related atherosclerosis is poorly understood. In the current study, we found that RGMa is expressed in VSMCs-derived macrophage-like cells from the fibrous cap of type V atherosclerotic plaques and the neointima of ligated carotid artery in ApoE-/- mice. We determined levels of RGMa mRNA and protein increased in oxidized LDL (ox-LDL)-induced VSMCs. Knockdown of RGMa, both in vivo and in vitro, inhibited the dedifferentiation of ox-LDL-induced VSMCs and their ability to proliferate and migrate, reduced the thickness of the neointima after ligation of the left common carotid artery in ApoE-/- mice. Additionally, we show RGMa promoted the dedifferentiation of VSMCs via enhancement of the role of transcription factor Slug. Slug knockdown reversed the dedifferentiation of ox-LDL-induced VSMCs promoted by RGMa overexpression. Thus, inhibition of RGMa may constitute a therapeutic strategy for atherosclerotic plaques prone to rupture and restenosis following mechanical injury.

The Circulating Biomarker Fractalkine and Platelet-Derived Growth Factor BB are Correlated with Carotid Plaque Vulnerability Assessed by Computed Tomography Angiography.

OBJECTIVES: Although studies have demonstrated that inflammatory and lipid/ lipoproteins-related biomarkers, genetic mutations, and epigenetic mechanisms could be candidates for diagnosis and prognosis of ischemic stroke, there is still no consensus on how to identify vulnerable plaques based on circulating biomarkers. MATERIALS AND METHODS: Histological and immunohistochemical staining were performed in the aorta sections of ApoE-/- and WT mice. Eighty-nine patients who underwent CTA were included in this study. The degree of carotid stenosis and the wall features of plaque components were quantitatively analyzed. And the serum concentration of FKN and PDGF-BB were measured. RESULTS: (1) The type V vulnerable atherosclerotic plaques deposited on the aortas of ApoE-/- mice after feeding with western diet for 16 weeks. And the expression of CX3CR1 and PDGFR-ß increased in the areas of atherosclerotic plaques, especially inside the fibrous cap of plaque. (2) Patients with symptomatic carotid stenosis showed larger LNRC, smaller calcified plaques and more plaque ulceration detected by CTA than asymptomatic stenosis patients. Plaque ulceration and size of LNRC were high risk factors for stroke while plaque calcification was less frequently associated with cerebrovascular ischemia. (3) The serum concentration of FKN was lower and of PDGF-BB was higher in the patients with carotid artery stenosis. Correlation analysis suggested that FKN and PDGF-BB correlated positively with carotid plaque calcification and LNRC respectively. CONCLUSIONS: For prediction it is recommended to combine circulating biomarkers (FKN and PDGF-BB) and imaging biomarkersfor comprehensive diagnosis and risk stratification in carotid atherosclerotic stroke.

Serum Interleukin-33 is a Novel Predictive Biomarker of Hemorrhage Transformation and Outcome in Acute Ischemic Stroke.

INTRODUCTION: Hemorrhage Transformation (HT) in acute ischemic stroke (AIS) depends on multiple factors. Some studies have shown that serum interleukin-33 (IL-33) is of central significance as a neuroprotective factor. However, the relationship between serum IL-33 and HT in AIS has not been evaluated. OBJECTIVE: To investigate the relationship between serum IL-33 concentration and HT in AIS. METHODS: We recruited 151 consecutive non-thrombolytic patients with AIS clinically diagnosed in The First Affiliated Hospital of Chongqing Medical University from December 2018 to October 2019. If the patients showed radiographic presentation of HT within two weeks following admission, they were assigned to the HT group; others were assigned to the non-HT group. There were 40 healthy control subjects recruited during the same period. Serum IL-33 concentration was detected by ELISA and the independent risk value of HT in AIS was predicted by multivariate logistic regression. The accuracy was analyzed by receiver operating characteristic (ROC) curves. In three months after admission, the functional outcome was measured by modified Rankin scale (mRS). RESULTS: ROC curve showed that the area under the curve (AUC) of serum IL-33 was 0.739 (95% CI: 0.657-0.821, P < .001) in predicting HT in AIS. When serum IL-33 concentration was ≤ 67.66 ng/L, the sensitivity and specificity of the prediction were 81.3% and 63%, respectively. Multivariate logistic regression analysis showed that serum IL-33 concentration ≤ 67.66 ng/L was an independent predictor of HT in AIS (OR = 5.773, 95% CI: 1.685-19.792, P = .005). The follow-up results of mRS showed a higher probability of an unfavorable outcome in those with HT compared to those without HT (OR = 6.520, 95% CI: 2.530-16.803, P < .001). CONCLUSIONS: HT in AIS is negatively correlated with outcome. Furthermore, serum IL-33 is an independent predictive biomarker of HT and outcome in AIS.

Caffeine Inhibits Activation of the NLRP3 Inflammasome via Autophagy to Attenuate Microglia-Mediated Neuroinflammation in Experimental Autoimmune Encephalomyelitis.

The activation of microglia is an important cause of central nervous system (CNS) inflammatory cell infiltration and inflammatory demyelination in experimental autoimmune encephalomyelitis (EAE). Furthermore, the proinflammatory response induced by the NLR family pyrin domain containing 3 (NLRP3) inflammasome can be amplified in microglia after NLRP3 inflammasome activation. Autophagy is closely related to the inflammatory response. Caffeine exerts anti-inflammatory and autophagy-stimulating effects, but the specific mechanism remains unclear. This study examined the mechanism underlying the anti-inflammatory effect of caffeine on EAE. In this study, C57BL/6 mice were immunized to induce EAE and treated with caffeine to observe its effect on prognosis. The effects of caffeine on autophagy and inflammation were also analysed in mouse primary microglia (PM) and the BV2 cell line. The data demonstrated that caffeine reduced the clinical score, the infiltration of inflammatory cells, the demyelination level, and the activation of microglia in EAE mice. Furthermore, caffeine increased the LC3-II/LC3-I levels and decreased the NLRP3 and P62 levels in EAE mice, whereas the autophagy inhibitor 3-methylamine (3-MA) blocked these effects. In vitro, caffeine promoted autophagy by suppressing the mechanistic target of rapamycin (mTOR) pathway and inhibited activation of the NLRP3 inflammasome. However, autophagy-related gene 5 (ATG5)-specific siRNA abolished the anti-inflammatory effect of caffeine treatment in PM and BV2 cells. Taken together, these data suggest that caffeine exerts a newly discovered effect on EAE by reducing NLRP3 inflammasome activation via the induction of autophagy in microglia.

Common Polymorphisms in the RGMa Promoter Are Associated With Cerebrovascular Atherosclerosis Burden in Chinese Han Patients With Acute Ischemic Cerebrovascular Accident.

Repulsive guidance molecule a (RGMa) plays a vital role in the progression of numerous inflammatory diseases. However, whether it participates in atherosclerosis development is not known. Here, we explored the influence of RGMa in atherogenesis by investigating whether an association exists between functional polymorphisms in the RGMa promoter and cerebrovascular atherosclerosis burden (CAB) in Chinese Han patients diagnosed with acute ischemic cerebrovascular accident. To this end, we conducted a genetic association study on 201 patients with prior diagnoses of acute ischemic stroke or transient ischemic attack recruited from our hospital. After admission, we conducted three targeted single-nucleotide polymorphisms (SNPs) genotyping and evaluated CAB by computed tomography angiography. We used logistic regression modeling to analyze genetic associations. Functional polymorphism analysis indicated an independent association between the rs725458 T allele and increased CAB in patients with acute ischemic cerebrovascular accident [adjusted odds ratio (OR) = 1.66, 95% confidence interval (CI) = 1.01-2.74, P = 0.046]. In contrast, an association between the rs4778099 AA genotype and decreased CAB (adjusted OR = 0.10, 95% CI = 0.01-0.77, P = 0.027) was found. Our Gene Expression Omnibus analysis revealed lower RGMa levels in the atherosclerotic aortas and in the macrophages isolated from plaques than that in the normal aortas and macrophages from normal tissue, respectively. In conclusion, the relationship between RGMa and cerebrovascular atherosclerosis suggests that RGMa has a potential vasoprotective effect. The two identified functional SNPs (rs725458 and rs4778099) we identified in the RGMa promoter are associated with CAB in patients diagnosed with acute ischemic cerebrovascular accident. These findings offer a promising research direction for RGMa-related translational studies on atherosclerosis.

MBNL1 reverses the proliferation defect of skeletal muscle satellite cells in myotonic dystrophy type 1 by inhibiting autophagy via the mTOR pathway.

Skeletal muscle atrophy is one of the clinical symptoms of myotonic dystrophy type 1 (DM1). A decline in skeletal muscle regeneration is an important contributor to muscle atrophy. Skeletal muscle satellite cells (SSCs) drive skeletal muscle regeneration. Increased autophagy can reduce the proliferative capacity of SSCs, which plays an important role in the early regeneration of damaged skeletal muscle in DM1. Discovering new ways to restore SSC proliferation may aid in the identification of new therapeutic targets for the treatment of skeletal muscle atrophy in DM1. In the pathogenesis of DM1, muscleblind-like 1 (MBNL1) protein is generally considered to form nuclear RNA foci and disturb the RNA-splicing function. However, the role of MBNL1 in SSC proliferation in DM1 has not been reported. In this study, we obtained SSCs differentiated from normal DM1-04-induced pluripotent stem cells (iPSCs), DM1-03 iPSCs, and DM1-13-3 iPSCs edited by transcription activator-like (TAL) effector nucleases (TALENs) targeting CTG repeats, and primary SSCs to study the pathogenesis of DM1. DM1 SSC lines and primary SSCs showed decreased MBNL1 expression and elevated autophagy levels. However, DM1 SSCs edited by TALENs showed increased cytoplasmic distribution of MBNL1, reduced levels of autophagy, increased levels of phosphorylated mammalian target of rapamycin (mTOR), and improved proliferation rates. In addition, we confirmed that after MBNL1 overexpression, the proliferative capability of DM1 SSCs and the level of phosphorylated mTOR were enhanced, while the autophagy levels were decreased. Our data also demonstrated that the proliferative capability of DM1 SSCs was enhanced after autophagy was inhibited by overexpressing mTOR. Finally, treatment with rapamycin (an mTOR inhibitor) was shown to abolish the increased proliferation capability of DM1 SSCs due to MBNL1 overexpression. Taken together, these data suggest that MBNL1 reverses the proliferation defect of SSCs in DM1 by inhibiting autophagy via the mTOR pathway.